The relative importance of the two was disputed, but many scientists concluded that those plaques and fibrils clog the brain as coffee grounds clog a drain.
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Solanezumab is a monoclonal antibody that removes amyloid by attaching itself to free-floating amyloid protein before the protein forms into plaques, while several other antibody drugs also attack amyloid fibrils that are part of the plaques.
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You can read endless treatises by food science wonks about precisely how low-temperature cooking takes meat from tough to tender and back again, not to mention the roles played by plasma, muscle fibrils and collagen in how it tastes.
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Fibrillogenesis is the development of fine fibrils normally present in collagen fibers of connective tissue. It is derived from the Greek fibrillo (meaning fibrils, or pertaining to fibrils) and genesis (to create, the process by which something is created). The assembly of collagen fibrils, fibrillogenesis appears to be a self-assembly process although there is much speculation about the specifics of the mechanism through which the body produces collagen fibrils. In the body, collagen fibrils are composed of several types of collagen as well as macromolecules.
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Moreover, longitudinally oriented fibrils improve tensile strength, whereas the addition of 20° tilted fibrils, exclusive to latewood tracheids, provides stability against compression.
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Short fibronectin fibrils then begin to form between adjacent cells. As matrix assembly proceeds, the soluble fibrils are converted into larger insoluble fibrils that comprise the extracellular matrix. Fibronectin's shift from soluble to insoluble fibrils proceeds when cryptic fibronectin-binding sites are exposed along the length of a bound fibronectin molecule. Cells are believed to stretch fibronectin by pulling on their fibronectin-bound integrin receptors.
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During deformation, the shear component of the applied stress causes the hydrogen bonds between fibrils to break and then reform after fibril adjustment. # Collagen fibrils stretch: Collagen fibrils can elastically stretch, resulting in fibrils re-orientating to align with the tensile direction. # Tensile opening of interfibillar gaps: Fibrils highly misoriented with the tensile direction can separate, creating an opening. # "Sympathetic" lamella rotation: A lamella is able to rotate away from the tensile direction if it is sandwiched between two lamellae that are reorienting themselves towards the tensile direction.
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Adjustment of the Bouligand structure during loading has been measured using small angle X-ray scattering (SAXS). The two adjustment effects are the change in angle between the collagen fibrils and tensile axis, and the stretching of collagen fibrils. There are four mechanisms through which these adjustments occur. # Fibrils rotate because of interfibrillar shear: As a tensile force is applied, fibrils rotate to align with the tensile direction.
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He also identified fibrils in the dentinal tubes, which later became known as "Tomes's fibers". He speculated on the possible structural and functional significance of the tubes and fibrils.
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Hierarchical structure of hair in the cortex and cuticle, highlighting the scale which defines fibrils. Fibrils (from the Latin fibra) are structural biological materials found in nearly all living organisms. Not to be confused with fibers or filaments, fibrils tend to have diameters ranging from 10-100 nanometers (whereas fibers are micro to milli-scale structures and filaments have diameters approximately 10-50 nanometers in size). Fibrils are not usually found alone but rather are parts of greater hierarchical structures commonly found in biological systems.
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Stirring of a given sample of amylose is said to form fibrillar crystals which are said to precipitate out of the mother liquor. These long fibrils can be imaged using electron microscopy revealing transverse striations resembling a shish-kebab. Amylose fibrils are categorized with having one of two morphologies: ones with small rodlike fibrils and others with lath-shaped crystals.
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Type I collagen is the most abundant structural macromolecule within the vertebrate body and also represents the most abundant collagen found within various collagen fibrils There are immense differences in the types of collagen fibrils that exist within the body. For instance, fibrils within the tendon vary in width and are banded into aggregates that form fibril bundles that resist forces of tension within one dimension. Similarly, fibrils that form the translucent corneal stromal matrix form orthogonal sheets and withstand the force of traction in two dimensions. These two structurally different collagen fibrils are speculated to be formed from the same molecules with type I collagen being the primary collagen found within both structures.
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She observed that fibrils start as delicate lines in the exoplasm and become bundles that are passed between cells. Lewis also found no evidence of vacuoles forming fibrils as was believed to be the case by other researchers.
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The dermatan sulfate side chains of decorin aggregate in solution, and this behavior can assist with the assembly of the collagen fibrils. When decorin molecules are bound to a collagen fibril, their dermatan sulfate chains may extend and associate with other dermatan sulfate chains on decorin that is bound to separate fibrils, therefore creating interfibrillar bridges and eventually causing parallel alignment of the fibrils.
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Fibrils are composed of linear biopolymers, and are characterized by rod-like structures with high length-to-diameter ratios. Oftentimes, they spontaneously arrange into helical structures. In biomechanics problems, fibrils can be characterized as classical beams with a roughly circular cross-sectional area on the nanometer scale. As such, simple beam bending equations can be applied to calculate flexural strength of fibrils under ultra-low loading conditions.
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The collagen in tendons are held together with proteoglycan (a compound consisting of a protein bonded to glycosaminoglycan groups, present especially in connective tissue) components including decorin and, in compressed regions of tendon, aggrecan, which are capable of binding to the collagen fibrils at specific locations. The proteoglycans are interwoven with the collagen fibrils their glycosaminoglycan (GAG) side chains have multiple interactions with the surface of the fibrils showing that the proteoglycans are important structurally in the interconnection of the fibrils. The major GAG components of the tendon are dermatan sulfate and chondroitin sulfate, which associate with collagen and are involved in the fibril assembly process during tendon development. Dermatan sulfate is thought to be responsible for forming associations between fibrils, while chondroitin sulfate is thought to be more involved with occupying volume between the fibrils to keep them separated and help withstand deformation.
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The collagen fibrils are made of a mixture of type I and type V collagens. These molecules are tilted by about 15 degrees to the fibril axis, and because of this, the axial periodicity of the fibrils is reduced to 65 nm (in tendons, the periodicity is 67 nm). The diameter of the fibrils is remarkably uniform and varies from species to species. In humans, it is about 31 nm.
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Proteoglycan protein cores attach to the surface of the collagen fibrils with the GAG chains projecting outwards. The GAG chains are able to form antiparallel links with other GAG chains from adjacent fibrils, perhaps through the mediation of positively charged ions. In such a way, bridges are formed between adjacent collagen fibrils. These bridges are subject to thermal motion which prevents them from assuming a fully extended conformation.
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The stabilized balls of protein fragments are called oligomers. The oligomers can aggregate together and further stabilize to make amyloid fibrils. Both the oligomers and amyloid fibrils are toxic to cells and can interfere with proper organ function., Karp, Judith E., ed.
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This mutation accelerates Aβ oligomerization but the proteins do not form amyloid fibrils suggesting that it is the Aβ oligomerization rather than the fibrils that may be the cause of this disease. Mice expressing this mutation have all usual pathologies of Alzheimer's disease.
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This results in forces that tend to move adjacent fibrils close to each other. At the same time the charges on the GAG chains attract ions and water molecules by the Donnan effect. The increased water volume between the fibrils results in forces that tend to push the fibrils apart. A balance between attractive and repulsive forces is reached for specific inter-fibrillar distances, which depends on the type of proteoglycans present.
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Locally, the separations between adjacent collagen fibrils are very uniform. Stromal transparency is mainly a consequence of the remarkable degree of order in the arrangement of the collagen fibrils in the lamellæ and of fibril diameter uniformity. Light entering the cornea is scattered by each fibril. The arrangement and the diameter of the fibrils is such that scattered light interferes constructively only in the forward direction, allowing the light through to the retina.
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Collagen triple helices are often bundled into fibrils which themselves form larger fibres, as in tendon.
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This enables it bind to collagen molecules within a collagen fibril, thus helping keep adjacent fibrils apart.
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It also has a low toxicity in the body and is inert in the intestines. Chitin also has antibacterial properties. Chitin forms crystals that make fibrils that become surrounded by proteins. These fibrils can bundle to make larger fibers that contribute to the hierarchical structure of many biological materials.
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SEM photo of chrysotile. Bulk chrysotile has a hardness similar to a human fingernail and is easily crumbled to fibrous strands composed of smaller bundles of fibrils. Naturally-occurring fibre bundles range in length from several millimetres to more than ten centimetres, although industrially-processed chrysotile usually has shorter fibre bundles. The diameter of the fibre bundles is 0.1–1 µm, and the individual fibrils are even finer, 0.02–0.03 µm, each fibre bundle containing tens or hundreds of fibrils.
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These fibrils are made of 3 nm diameter canals which link the interior and exterior of the shell.
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In mammals, the fibrillar collagens involved in the formation of cross-striated fibrils are types I–III, V, and XI. Type II and type XI collagens compose the fibrils present in cartilage. These can be distinguished from collagens located in non-cartilaginous tissues, which include type I, III, and V collagens.
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Such protofilaments merge and intertwist, yielding thin fibrils, which are capable of further association and twining, producing mature amyloid.
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It is closely related to Inocybe fastigiata, but can again be distinguished by colour; I. fastigiata has lighter coloured fibrils.
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If the body does not destroy the improper collagen, the relationship between the collagen fibrils and hydroxyapatite crystals to form bone is altered, causing brittleness. Another suggested disease mechanism is that the stress state within collagen fibrils is altered at the locations of mutations, where locally larger shear forces lead to rapid failure of fibrils even at moderate loads as the homogeneous stress state found in healthy collagen fibrils is lost. These recent works suggest that OI must be understood as a multi-scale phenomenon, which involves mechanisms at the genetic, nano-, micro- and macro-level of tissues. Most people with OI receive it from a parent but in 35% of cases it is an individual (de novo or "sporadic") mutation.
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Rats and mice have six substitutions (three of which are proline substitutions at positions 25, 28 and 29) that are believed to prevent the formation of amyloid fibrils, although not completely as seen by its propensity to form amyloid fibrils in vitro. Rat IAPP is nontoxic to beta-cells when overexpressed in transgenic rodents.
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Collagen fibres coalesce into macroaggregates. After secretion from the cell, cleaved by procollagen N- and C-proteases, the tropocollagen molecules spontaneously assemble into insoluble fibrils. A collagen molecule is about 300 nm long and 1-2 nm wide, and the diameter of the fibrils that are formed can range from 50-500 nm. In tendons, the fibrils then assemble further to form fascicles, which are about 10 mm in length with a diameter of 50-300 μm, and finally into a tendon fibre with a diameter of 100-500 μm.
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Like most biopolymers, stress-strain relationships of fibrils tend to show a characteristic toe-heel region before a linear, elastic region. Unlike biopolymers, fibrils do not behave like homogeneous materials, as yield strength has been shown to vary with volume, indicating structural dependencies. Differences in structure between fibrils of different origin is typically determined by x-ray diffraction. A scanning electron microscope (SEM) can be used to observe specific details on larger fibril species such as the characteristic 67 nm bands in collagen, but often is not fine enough to determine the full structure.
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A 2012 study generated a high resolution structure of IAPP fibrils using a combination of SDSL, pulse EPR and computational biology.
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Fiber surfaces can also be dull or bright. Dull surfaces reflect more light while bright tends to transmit light and make the fiber more transparent. Very short and/or irregular fibers have been called fibrils. Natural cellulose, such as cotton or bleached kraft, show smaller fibrils jutting out and away from the main fiber structure.Hans-J. Koslowski.
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The cap is initially convex before flattening out, and reaches a diameter of . The cap surface is dry, smooth, reddish-brown to coco-brown with silky fibrils or sometimes with flattened scales and often has a slight umbo. In maturity, the fibrils usually darken to walnut brown. The flesh is light brown and does not change color in KOH.
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In the fibrils, collagen molecules are embedded with hydroxyapatite mineral nanocrystals. Collagen fibrils align in the same direction to make a layer of collagen lamella, of about 50 μm in thickness. Lamellae are stacked with a misalignment in orientation, creating a Bouligand structure. When the scales bend during an attack, stress is distributed due to the corrugated morphology.
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As a result, collagen fibrils are not assembled properly; they appear ribbon-like and disorganized under the microscope. Cross-links, or chemical interactions, between collagen fibrils are also affected. These defects weaken connective tissue (the tissue that binds and supports the body's muscles, ligaments, organs, and skin), which causes the signs and symptoms of the disorder.
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Anchoring fibrils are thought to form a structural link between the epidermal basement membrane and the fibrillar collagens in the upper dermis.
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PD-1 counteracts the effects of the fibrils by boosting immune activity and triggering an immune pathway that allows for brain repair.
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Fibrils with a large Ψ are compressed, since adjacent lamellae contract in accordance with Poisson's ratio, which is a function of strain anisotropy.
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Additional assembly of fibrils is guided by fibroblasts, which deposit fully formed fibrils from fibripositors. In the fibrillar collagens, molecules are staggered to adjacent molecules by about 67 nm (a unit that is referred to as ‘D’ and changes depending upon the hydration state of the aggregate). In each D-period repeat of the microfibril, there is a part containing five molecules in cross- section, called the “overlap”, and a part containing only four molecules, called the "gap". These overlap and gap regions are retained as microfibrils assemble into fibrils, and are thus viewable using electron microscopy.
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The pathogenicity of prions and proteins with prion-like domains is hypothesized to arise from their self-templating ability and the resulting exponential growth of amyloid fibrils. The presence of amyloid fibrils in patients with degenerative diseases has been well documented. These amyloid fibrils are seen as the result of pathogenic proteins that self-propagate and form highly stable, non-functional aggregates. While this does not necessarily imply a causal relationship between amyloid and degenerative diseases, the toxicity of certain amyloid forms and the overproduction of amyloid in familial cases of degenerative disorders supports the idea that amyloid formation is generally toxic.
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Only a fraction of the polypeptide chain is in a β-strand conformation in the fibrils, the remainder forms structured or unstructured loops or tails. For a long time our knowledge of the atomic-level structure of amyloid fibrils was limited by the fact that they are unsuitable for the most traditional methods for studying protein structures. Recent years have seen progress in experimental methods, including solid-state NMR spectroscopy and Cryo-Electron Microscopy. Combined, these methods have provided 3D atomic structures of amyloid fibrils formed by amyloid β peptides, α-synuclein, tau, and the FUS protein, associated with various neurodegenerative diseases.
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Anchoring fibrils (composed largely of type VII collagen) extend from the basal lamina of epithelial cells and attach to the lamina reticularis (also known as the reticular lamina) by wrapping around the reticular fiber (collagen III) bundles. The basal lamina and lamina reticularis together make up the basement membrane. Anchoring fibrils are essential to the functional integrity of the dermoepidermal junction.
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The four mechanisms through which adjustments occur are fibril rotation, collagen fibril stretching, tensile opening between fibrils, and sympathetic lamella rotation. Fibrils adapting to the loading environment enhance the flexibility of the lamellae. This contributes resistance to scale bending, and therefore increases fracture resistance. As a whole, the outer scale layer is hard and brittle, while the inner layer is ductile and tough.
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The anterior lamellæ interweave more than posterior lamellæ. The fibrils of each lamella are parallel with one another, but at different angles to those of adjacent lamellæ. The lamellæ are produced by keratocytes (corneal connective tissue cells), which occupy about 10% of the substantia propria. Apart from the cells, the major non-aqueous constituents of the stroma are collagen fibrils and proteoglycans.
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Casein proteins have potential for use as nanomaterials due to their readily available source (milk) and their propensity to self-assemble into amyloid fibrils.
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Due to the prevalence of fibrils in biological systems, their study is of great importance in the fields of microbiology, biomechanics, and materials science.
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The word fibrillation () is related to the word fibril in the sense of muscle fibrils, the proteins that make up each muscle fiber (muscle cell).
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Fibronectin promotes particle phagocytosis by both macrophages and fibroblasts. Collagen deposition at the wound site by fibroblasts takes place with the help of fibronectin. Fibronectin was also observed to be closely associated with the newly deposited collagen fibrils. Based on the size and histological staining characteristics of the fibrils, it is likely that at least in part they are composed of type III collagen (reticulin).
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Since they are noncovalently bound to the fibrils, they may reversibly associate and disassociate so that the bridges between fibrils can be broken and reformed. This process may be involved in allowing the fibril to elongate and decrease in diameter under tension.Cribb, A. M.; Scott, J.E. (1995). In Tendon response to tensile-stress - an ultrastructural investigation of collagen - proteoglycan interactions in stressed tendon,1995; Cambridge Univ Press.
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An alternative model assumes that PrPSc exists only as fibrils, and that fibril ends bind PrPC and convert it into PrPSc. If this were all, then the quantity of prions would increase linearly, forming ever longer fibrils. But exponential growth of both PrPSc and of the quantity of infectious particles is observed during prion disease. This can be explained by taking into account fibril breakage.
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Native-like amyloid fibrils in which native β-sheet containing proteins maintain their native-like structure in the fibrils have also been proposed. One complicating factor in studies of amyloidogenic polypeptides is that identical polypeptides can fold into multiple distinct amyloid conformations. This phenomenon is typically described as amyloid polymorphism. It has notable biological consequences given that it is thought to explain the prion strain phenomenon.
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Type XI collagen also helps maintain the spacing and diameter of type II collagen fibrils. Type II collagen is an important component of the eye and mature cartilage tissue. The size and arrangement of type II collagen fibrils is essential for the normal structure of these tissues. The pro-alpha2(XI) chain combines with pro-alpha1(XI) and pro-alpha1(II)collagen chains to form a procollagen molecule.
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The fruit bodies have convex to broadly convex caps, sometimes with a broad umbo, and measure in diameter. Its color is pale gray, sometimes with tints of brown in the center. The dry cap surface is made of densely interwoven fibrils in the center, and radiating interwoven fibrils elsewhere; there are scattered squamules. The flesh is pale gray, with no distinctive odor and a hot, peppery or bitter taste.
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Amyloids are mostly fibrils, while also containing a P component, apolipoprotein, collagen, fibronectin, and laminin. The P component, a pentameric protein, stabilizes the fibrils of the amyloid, which reduces their clearance from the body. Deposits of the amyloids can occur through out of the body, including the heart, liver, kidneys, spleen, adrenal glands, and bones. Deposits in the extracellular cardiac space can stiffen the heart, resulting in restriction of the ventricles.
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Fibrillogenesis is the expansion of fine fibrils which is common in collagen fibers of connective tissue. The definite mechanisms of fibrillogenesis are still unknown, although many hypotheses resulting from basic research help discover many possible mechanisms. In early experiments, collagen I could be distilled from tissues and recombined into fibrils with controlling the solutions. Later studies help understand the composition and structure of binding sites on the collagen monomers.
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Structure of Collagen I fibrils Collagen is the major structural protein outside cells in many connective tissues of animals. As the primary component of connective tissue, it has the largest amount among protein in mammals, occupying 25% to 35% of all protein content in the body. The fibrils in collagen are packed in a crimp structure. The stress/strain curve of collagen, such as tendon, can be subdivided into several regions.
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Streptococcus cristatus is a species of viridans Streptococcus with tufted fibrils, first isolated from the human oral cavity and throat. The type strain is strain CR311 (= NCTC 12479).
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Perichromatin fibrils are visible only under electron microscope. They are located next to the transcriptionally active chromatin and are hypothesized to be the sites of active pre-mRNA processing.
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The name of this species refers to the fibrils on the Stipe (mycology) that turn bluish in age, or when handled. This species is closely related to Psilocybe subfimetaria.
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The wild-type form of all of these proteins show a tendency to self-assemble into amyloid fibrils, while the pathogenic mutations exacerbate this behaviour and lead to excess accumulation.
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Decorin's name is a derivative of both the fact that it "decorates" collagen type I, and that it interacts with the "d" and "e" bands of fibrils of this collagen.
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This general template of recruitment is also characteristic in the condition sickle cell anemia in which the red blood cells are misshapen because of the formation of extended polymer fibrils.
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It is covered in fibrils of an orange colour, and sometimes has minute scales. The dried cap turns blackish-red when potassium hydroxide is applied.Guzmán-Dávalos et al. 2009, p. 198.
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Cortinarius hemitrichus, also known as the frosty webcap, is a basidiomycete mushroom of the genus Cortinarius. Young mushrooms are characterized by their brown cone-shaped caps covered with dense white fibrils.
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ADPs can be generated in a spontaneous nature by the existence of multiple thermodynamic states and the kinetic equilibrium between the alpha helix and beta-pleated sheets polymerizing into extended fibrils.
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The fibrillar structure of wood is said to play a significant role in both the mechanical stability and ability of wood to possess channels to transport minerals and water. Sprucewood (Picea abies), among others, are reported to possess cellulose fibrils with a normalized diameter of 2.5 nm. There is also a reported link between the age of the wood and the spiral angle of the fibrils with respect to the longitudinal direction. Earlywood is said to have a consistent 4.6 ± 0.6° rest angle, whereas latewood is said to have a transition region from 4.6° to 19.8 ± 0.7°. In latewood, the two spiral angle regions of cellulose fibrils are not continuous, meaning that there are two independent tracheid structures in “older” trees meeting different mechanical requirements.
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These tropocollagen molecules are intercalated with the mineral phase (hydroxyapatite, a calcium phosphate) forming fibrils that curl into helicoids of alternating directions. These "osteons" are the basic building blocks of bones, with the volume fraction distribution between organic and mineral phase being about 60/40. In another level of complexity, the hydroxyapatite crystals are mineral platelets that have a diameter of approximately 70–100 nm and thickness of 1 nm. They originally nucleate at the gaps between collagen fibrils.
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Intrinsic toughening mechanisms are not as well defined as extrinsic mechanisms, because they operate on a smaller length-scale than extrinsic mechanisms (usually ~1 μm). Plasticity is usually associated with “soft” materials such as polymers and cartilage, but bone also experiences plastic deformation. One example of an extrinsic mechanism is fibrils (length scale ~10’s nm) sliding against one another, stretching, deforming, and/or breaking. This movement of fibrils causes plastic deformation resulting in crack tip blunting.
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Partial dephosphorylation of the RS domain causes the SR proteins to leave the nucleus and SR proteins with unphosphorylated RS domains are found in the cytosol. SR proteins are located in two different types of nuclear speckles, interchromatin granule clusters and perichromatin fibrils. Interchromatin granule clusters are for the storage and reassembly of pre-mRNA splicing proteins. Perichromatin fibrils are areas of gene transcription and where SR proteins associate with RNA polymerase II for co- transcriptional splicing.
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Crazes can be seen because light reflects off the surfaces of the gaps. The gaps are bridged by fine filament called fibrils, which are molecules of the stretched backbone chain. The fibrils are only a few nanometers in diameter, and cannot be seen with a light microscope, but are visible with an electron microscope. The thickness profile of a crazing is like a sewing needle: the very tip of the crazing may be as thin as several atoms.
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Type XI collagen plays an important role in the structure and function of the inner ear. When mutations in the COL11A2 gene affect the structure of collagen fibrils, hearing loss can result.
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The matrix crazing theory focuses on explaining the toughening effects of crazing. Crazes start at the equator where principal strain is highest, propagate perpendicular to the stress, and end when they meet another particle. Crazes with perpendicular fibrils can eventually become a crack if the fibrils break. The volume expansion associated with small crazes distributed through a large volume compared to the small volume of a few large cracks in untoughened polymer accounts for a large fraction of the increase in fracture energy.
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Islands-in-the-sea extrusions are also called matrix-fibril, because fibrils of one polymer are distributed in the matrix of another polymer. The matrix is known as the "sea", and the fibrils are known as islands. The matrix is a soluble material that is washed away by a suitable solvent at some point in the manufacturing process. What remains at the microscopic level are bundles of thin parallel fibers, resulting in a fabric that is very soft and flexible.
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These proteins undergo a conformational change from largely random coil or alpha helix structures to the highly ordered beta sheet structures found in amyloid fibrils. Most beta sheets in known proteins are "twisted" about 15° for optimal hydrogen bonding and steric packing; however, some evidence from electron crystallography suggests that at least some amyloid fibrils contain "flat" sheets with only 1–2.5° of twist.Jimenez, J. L., Nettleton, E. J., Bouchard, M., Robinson, C. V., Dobson, C. M. & Saibil, H. R. (2002).
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A component of the Rosetta software suite, RosettaDesign, was used to accurately predict which regions of amyloidogenic proteins were most likely to make amyloid-like fibrils. By taking hexapeptides (six amino acid-long fragments) of a protein of interest and selecting the lowest energy match to a structure similar to that of a known fibril forming hexapeptide, RosettaDesign was able to identify peptides twice as likely to form fibrils as are random proteins. Rosetta@home was used in the same study to predict structures for amyloid beta, a fibril- forming protein that has been postulated to cause Alzheimer's disease. Preliminary but as yet unpublished results have been produced on Rosetta- designed proteins that may prevent fibrils from forming, although it is unknown whether it can prevent the disease.
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Decorin and biglycan are thought to be the result of a gene duplication. This protein is a component of connective tissue, binds to type I collagen fibrils, and plays a role in matrix assembly.
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In addition, because the tendon is a multi-stranded structure made up of many partially independent fibrils and fascicles, it does not behave as a single rod, and this property also contributes to its flexibility. The proteoglycan components of tendons also are important to the mechanical properties. While the collagen fibrils allow tendons to resist tensile stress, the proteoglycans allow them to resist compressive stress. These molecules are very hydrophilic, meaning that they can absorb a large amount of water and therefore have a high swelling ratio.
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Other forms of tendinosis that have not led to rupture have also shown the degeneration, disorientation, and thinning of the collagen fibrils, along with an increase in the amount of glycosaminoglycans between the fibrils. The third is paratenonitis with tendinosis, in which combinations of paratenon inflammation and tendon degeneration are both present. The last is tendinitis, which refers to degeneration with inflammation of the tendon as well as vascular disruption. Tendinopathies may be caused by several intrinsic factors including age, body weight, and nutrition.
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The cap, in diameter, is initially almost hemispherical in shape, transforming to broadly convex and finally to flattened or with edges upturned in age. The cap surface is dry, with fibrils when young, but later the fibrils form large, dark brown appressed squamules (2–9 mm long by 2–5 mm broad). The cap color may be various shades of brown depending on the maturity of the specimen. The cap flesh is typically thick, firm, white, and stains deep red 20–30 seconds after injury or bruising.
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Nanocellulose, which is also called cellulose nanofibers (CNF), microfibrillated cellulose (MFC) or cellulose nanocrystal (CNC), can be prepared from any cellulose source material, but woodpulp is normally used. The nanocellulose fibrils may be isolated from the wood-based fibers using mechanical methods which expose the pulp to high shear forces, ripping the larger wood-fibres apart into nanofibers. For this purpose, high-pressure homogenizers, grinders or microfluidizers can be used. The homogenizers are used to delaminate the cell walls of the fibers and liberate the nanosized fibrils.
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Structural analysis of Alzheimer's beta(1-40) amyloid: protofilament assembly of tubular fibrils. Biophys. J. 74, 537–545. Xu,Xu S. Aggregation drives "misfolding" in protein amyloid fiber formation. Amyloid 2007 Jun;14(2):119-31.
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The amyloid hypothesis is initially compelling because the gene for the amyloid beta precursor APP is located on chromosome 21, and patients with trisomy 21 - better known as Down syndrome - who have an extra gene copy exhibit AD-like disorders by 40 years of age. The amyloid hypothesis points to the cytotoxicity of mature aggregated amyloid fibrils, which are believed to be the toxic form of the protein responsible for disrupting the cell's calcium ion homeostasis and thus inducing apoptosis. This hypothesis is supported by the observation that higher levels of a variant of the beta amyloid protein known to form fibrils faster in vitro correlate with earlier onset and greater cognitive impairment in mouse models and with AD diagnosis in humans. However, mechanisms for the induced calcium influx, or proposals for alternative cytotoxic mechanisms, by mature fibrils are not obvious.
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The formation of the cellulose pellicle at the surface of the broth yields a product with unique characteristics that both bacteria and consumers find advantageous. Upon inoculation into the culture, bacteria such as Acetobacter immediately begin pulling glucose molecules together outside of the cell and joining them via β(1-4) linkages to form long, slender structures extending from their cell membranes called fibrils. The nanocellulose composing these fibrils demonstrates great strength and stability while still allowing hydrophilic interactions and biocompatibility, making it a great resource for the culture to use. A variety of inter and intramolecular bonding events join numerous fibrils together into the final, much larger structures known as microfibrils; because of the integrity of the microfibrils and the organized, linear nature of cellulose bonds, the resulting biofilm can also be referred to as a matrix or mat.
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To ensure the success of dental pulp and dentin regeneration in the adult, exogenously delivered and/or endogenous growth factors must induce the sprouting of neural fibrils and endothelial cells along with other blood vessel resident cells.
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This haziness is the result of crazing, where fibrils are formed within the material in regions of high hydrostatic stress. The material may go from an ordered appearance to a "crazy" pattern of strain and stretch marks.
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A foam-like material can be obtained from the gel by displacing the solvent with benzene, then freezing and subliming the benzene. Polyacetylene has a bulk density of 0.4 g/cm3, while density of the foam is significantly lower, at 0.02–0.04 g/cm3. The morphology consists of fibrils, with an average width of 200 Å. These fibrils form an irregular, web- like network, with some cross-linking between chains. The insolubility of polyacetylene makes it difficult to characterize this material and to determine the extent of cross-linking in the material.
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The triple helical tropocollagens in the microfibrils are arranged in a quasihexagonal packing pattern. The D-period of collagen fibrils results in visible 67nm bands when observed by electron microscopy. There is some covalent crosslinking within the triple helices, and a variable amount of covalent crosslinking between tropocollagen helices forming well organized aggregates (such as fibrils). Larger fibrillar bundles are formed with the aid of several different classes of proteins (including different collagen types), glycoproteins, and proteoglycans to form the different types of mature tissues from alternate combinations of the same key players.
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The cap margins of young specimens are usually curved inwards, and have irregular, wavy edges; young specimens may also have fragments of the partial veil hanging off the margin. The whitish partial veil is similar to those of the genus Cortinarius—cobwebby, and made of silky fibrils. When the cap expands and the veil rips, the fibrils remains briefly as an annular zone on the stem, before fading into nothing. The gills have an adnate or adnexed attachment to the stem, which later becomes seceding (pulled away from the stem).
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The spacing of the narrow gills is close to crowded, and the gill color is initially dull gray before maturing spores cause the color to change to purplish-brown. The stem is long and thick, and more or less equal in width throughout its length or slightly larger near the base. The hollow, brittle, stem is pale brown on the upper part, and reddish-brown near the bottom. The stem is densely covered with whitish fibrils that are pressed flat against the surface; the fibrils slough off in maturity to leave a smooth surface.
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In a study of enzymatically pre-treated nanocellulose fibrils in a suspension the size and size-distribution were established using cryo-TEM. The fibrils were found to be rather mono-dispersed mostly with a diameter of ca. 5 nm although occasionally thicker fibril bundles were present. By combining ultrasonication with an "oxidation pretreatment", cellulose microfibrils with a lateral dimension below 1 nm has been observed by AFM. The lower end of the thickness dimension is around 0.4 nm, which is related to the thickness of a cellulose monolayer sheet.
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Many other amphiphilic compounds, such as pepducins, strongly interact with biological membranes by insertion of the hydrophobic part into the lipid membrane, while exposing the hydrophilic part to the aqueous medium, altering their physical behavior and sometimes disrupting them. Aβ proteins form antiparallel β sheets which are strongly amphiphilic, and which aggregate to form toxic oxidative Aβ fibrils. Aβ fibrils themselves are composed of amphiphilic 13-mer modular β sandwiches separated by reverse turns. Hydropathic waves optimize the description of the small (40,42 aa) plaque- forming (aggregative) Aβ fragments.
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Blocking of PD-1 leads to a reduction in cerebral amyloid-β plaques and improves cognitive performance in mice. Immune blockade of PD-1 evoked an IFN-γ dependent immune response that recruited monocyte- derived macrophages to the brain that were then capable of clearing the amyloid-β plaques from the tissue. Repeated administrations with anti-PD-1 were found to be necessary to maintain the therapeutic effects of the treatment. Amyloid fibrils are immunosuppressive and this finding has been separately confirmed by examining the effects of the fibrils in neuroinflammatory diseases.
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Fibrils grow subsequently from these nuclei through the addition of monomers in the exponential phase. A different model, called ‘nucleated conformational conversion’ and marked by blue arrows in the figure below, was introduced later on to fit some experimental observations: monomers have often been found to convert rapidly into misfolded and highly disorganized oligomers distinct from nuclei. Only later on, will these aggregates reorganise structurally into nuclei, on which other disorganised oligomers will add and reorganise through a templating or induced-fit mechanism (this ‘nucleated conformational conversion’ model), eventually forming fibrils.
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The template synthesis method uses a nanoporous membrane template composed of cylindrical pores of uniform diameter to make fibrils (solid nanofiber) and tubules (hollow nanofiber). This method can be used to prepare fibrils and tubules of many types of materials, including metals, semiconductors and electronically conductive polymers. The uniform pores allow for control of the dimensions of the fibers so nanofibers with very small diameters can be produced through this method. However, a drawback of this method is that it cannot make continuous nanofibers one at a time.
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Imaging chromatin nanostructure with binding-activated localization microscopy based on DNA structure fluctuations. Recently, the significant enhancement of fluorescence quantum yield of NIAD-4 upon binding to an amyloid was exploited for BALM imaging of amyloid fibrils and oligomers.
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Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. The word 'Corneal blindness' is commonly used to describe blindness due to corneal opacity.
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It is finely pruinose, punctate at the top with whitish fibrils near the base when young or undisturbed. Psilocybe aucklandiae spores are dark violet brown, oblong to ellipsoid, and 7 x 4 µm. Paul Stamets. Psilocybin Mushrooms of the World.
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It is solid, dry or moist but has no gelatinous universal veil present. When young, the stem surface is evenly covered with tiny fibrils and a fine whitish powder; over time it loses the hairs and the powder and becomes smooth.
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The peripheral end of the cell terminates at the gustatory pore in a fine hair filament, the gustatory hair. The central process passes toward the deep extremity of the bud, and there ends in single or bifurcated varicosities. The nerve fibrils after losing their medullary sheaths enter the taste bud, and end in fine extremities between the gustatory cells; other nerve fibrils ramify between the supporting cells and terminate in fine extremities; these, however, are believed to be nerves of ordinary sensation and not gustatory. Salt, sweet, sour and umami tastes causes depolarization of the taste cells, although different mechanisms are applied.
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Among the hydrophobic residues, aromatic amino-acids are found to have the highest amyloidogenic propensity. Cross-polymerization (fibrils of one polypeptide sequence causing other fibrils of another sequence to form) is observed in vitro and possibly in vivo. This phenomenon is important, since it would explain interspecies prion propagation and differential rates of prion propagation, as well as a statistical link between Alzheimer's and type 2 diabetes. In general, the more similar the peptide sequence the more efficient cross-polymerization is, though entirely dissimilar sequences can cross- polymerize and highly similar sequences can even be "blockers" that prevent polymerization.
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The curved petals form a paraboloidal dish which directs the sun's heat to the reproductive parts at the centre of the flower, keeping it some degrees Celsius above the ambient temperature. Surface gratings, consisting of ordered surface features due to exposure of ordered muscle cells on cuts of meat. The structural coloration on meat cuts appears only after the ordered pattern of muscle fibrils is exposed and light is diffracted by the proteins in the fibrils. The coloration or wavelength of the diffracted light depends on the angle of observation and can be enhanced by covering the meat with translucent foils.
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Gelsolin remains attached to the fast-growing (barbed/plus) end of actin, producing short, slow-growing fibrils. These actions are similar to those of cytoplasmic form of pGSN, cGSN, which contributes to structural changes of cells through both nucleating/polymerizing and severing/capping.
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Procollagen peptidase is an enzyme necessary for the post-translational modification of procollagen into collagen. Because of the abnormalities in the formation of collagen fibrils, affected cats produce twisted collagen ribbons, rather than the normal collagen cylinders one would expect to find.
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Opticin may noncovalently bind collagen fibrils and regulate fibril morphology, spacing, and organization. The opticin gene is mapped to a region of chromosome 1 that is associated with the inherited eye diseases age-related macular degeneration (AMD) and posterior column ataxia with retinosa pigmentosa (AXPC1).
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There are two tiers of lamellulae (short gills) interspersed between the gills. Like most Hygrophorus species, crushed gills have a waxy feel. The stipe measures long by thick and tapers abruptly at the base. Usually somewhat twisted, its surface comprises longitudinally arranged flattened fibrils.
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The correct intracellular trafficking of proSP-C has also been reported to depend on the propeptide. The structure of the BRICHOS domain has been solved. Mutations in this domain also lead to amyloid fibrils made up of the mature peptide, suggesting a chaperone activity.
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The size scales in biological testing are in the micron range, with structures that are typically very compliant. This requires the development of devices with high displacement capabilities and very high force resolution. Recent examples are the tensile characterization of collagen fibrils and DNA bundles.
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Once these molecules are processed, they arrange themselves into long, thin fibrils that cross-link to one another in the spaces around cells. The cross-links result in the formation of very strong mature type I collagen fibers. Collagenous function includes rigidity and elasticity.
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Tonofibrils are cytoplasmic protein structures in epithelial tissues that converge at desmosomes and hemidesmosomes. They consist of fine fibrils in epithelial cells that are anchored to the cytoskeleton. They were discovered by Rudolf Heidenhain, and first described in detail by Louis-Antoine Ranvier in 1897.
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The inner plexiform layer is an area of the retina that is made up of a dense reticulum of fibrils formed by interlaced dendrites of retinal ganglion cells and cells of the inner nuclear layer. Within this reticulum a few branched spongioblasts are sometimes embedded.
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Lewy bodies may be found in the brainstem (within the substantia nigra) or within the cortex. A classical Lewy body is an eosinophilic cytoplasmic inclusion consisting of a dense core surrounded by a halo of 10-nm-wide radiating fibrils, the primary structural component of which is alpha-synuclein. Cortical Lewy bodies are also composed of alpha- synuclein fibrils, but are less defined and lack halos. In histopathology, cortical Lewy bodies are a distinguishing feature for dementia with Lewy bodies (DLB), but may occasionally be seen in ballooned neurons characteristic of Pick's disease and corticobasal degeneration, as well as in patients with other tauopathies.
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During this time, the synthesis of collagen and GAGs is decreased, and the cellularity is also decreased as the tissue becomes more fibrous as a result of increased production of collagen I and the fibrils become aligned in the direction of mechanical stress. The final maturation stage occurs after ten weeks, and during this time there is an increase in crosslinking of the collagen fibrils, which causes the tissue to become stiffer. Gradually, over about one year, the tissue will turn from fibrous to scar-like. Matrix metalloproteinases (MMPs) have a very important role in the degradation and remodeling of the ECM during the healing process after a tendon injury.
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Toward the margin, either minute fibers or scales develop. The cap's fibrils are generally a brownish colour. The cap has an indistinct odor with a mild taste. The context can be as large as 5 mm thick, soft, and bruises irregularly a vinaceous colour where cut.
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The spines are composed of a moderately electron-dense material with denser fibrils embedded within it. A diplectanid genus Squamodiscus Yamaguti, 1934 was created but is now consideredYamaguti, S.(1963). Systema Helminthum Volume IV Monogenea and Aspidocotylea: John Wiley & Sons. a synonym of Diplectanum Diesing, 1858.
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Bone matrix composed of collagen fibrils. Nanofiber scaffolds are able to mimic such structure. In tissue engineering, a highly porous artificial extracellular matrix is needed to support and guide cell growth and tissue regeneration. Natural and synthetic biodegradable polymers have been used to create such scaffolds.
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Load- induced non-rupture tendinopathy in humans is associated with an increase in the ratio of collagen III:I proteins, a shift from large to small diameter collagen fibrils, buckling of the collagen fascicles in the tendon extracellular matrix, and buckling of the tenocyte cells and their nuclei.
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Ingestion of hydrolyzed collagen may affect the skin by increasing the density of collagen fibrils and fibroblasts, thereby stimulating collagen production. It has been suggested, based on mouse and in vitro studies, that hydrolyzed collagen peptides have chemotactic properties on fibroblasts or an influence on growth of fibroblasts.
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G. maritimus forms a more inclusive clade along with the members of spectabilis–imperialis; while it produces the smallest fruit bodies, it shares with the other members strong, sturdy mushrooms, caps with fibrils (sometimes with scales) and large, warty spores that turn red in Melzer's reagent or Lugol's iodine.
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The stipe is 3–8 cm long and 0.5 cm thick. It has an equal structure only enlarging near the base. The stipe is striate, pallid to yellow brown with fine fibrils that stain blue when handled. The stipe has a cortina that sometimes leaves a fragile annular zone.
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In bone, the origin ductility is at the nanoscale. The nano interfaces in Bone are the interface between individual collagen fibrils. The interface is filled with non-collagenous proteins, mainly osteopontin (OPN) and osteocalcin (OC). The osteopontin and osteocalcin form a sandwich structure with HAP minerals at nano-scale.
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The extracellular matrix of bone is laid down by osteoblasts, which secrete both collagen and ground substance. These synthesise collagen within the cell, and then secrete collagen fibrils. The collagen fibers rapidly polymerise to form collagen strands. At this stage they are not yet mineralised, and are called "osteoid".
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The chemical formula of cellulose is (C6H10O5)n where n is the degree of polymerization and represents the number of glucose groups.Chapter 2: Chemical Composition and Structure of Natural Lignocellulose Plant-derived cellulose is usually found in a mixture with hemicellulose, lignin, pectin and other substances, while bacterial cellulose is quite pure, has a much higher water content and higher tensile strength due to higher chain lengths. Cellulose consists of fibrils with crystalline and amorphous regions. These cellulose fibrils may be individualized by mechanical treatment of cellulose pulp, often assisted by chemical oxidation or enzymatic treatment, yielding semi-flexible cellulose nanofibrils generally 200 nm to 1 μm in length depending on the treatment intensity.
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The mechanical properties of the tendon are dependent on the collagen fiber diameter and orientation. The collagen fibrils are parallel to each other and closely packed, but show a wave-like appearance due to planar undulations, or crimps, on a scale of several micrometers. In tendons, the collagen fibres have some flexibility due to the absence of hydroxyproline and proline residues at specific locations in the amino acid sequence, which allows the formation of other conformations such as bends or internal loops in the triple helix and results in the development of crimps. The crimps in the collagen fibrils allow the tendons to have some flexibility as well as a low compressive stiffness.
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Certain MMPs including MMP-1, MMP-2, MMP-8, MMP-13, and MMP-14 have collagenase activity, meaning that, unlike many other enzymes, they are capable of degrading collagen I fibrils. The degradation of the collagen fibrils by MMP-1 along with the presence of denatured collagen are factors that are believed to cause weakening of the tendon ECM and an increase in the potential for another rupture to occur. In response to repeated mechanical loading or injury, cytokines may be released by tenocytes and can induce the release of MMPs, causing degradation of the ECM and leading to recurring injury and chronic tendinopathies. A variety of other molecules are involved in tendon repair and regeneration.
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The disease is caused by a defect in the structure of the type-IV collagen fibrils of the glomerular basement membrane. As a consequence, the collagen fibrils of the glomerular basement membrane are unable to form cross-links, so the structural integrity is weakened and the membrane is more susceptible to "wear-and-tear" damage. As the structure of the basement membrane begins to degenerate, plasma proteins are lost in the urine and symptoms begin to appear. Affected males appear healthy for the first three months of life, but then symptoms start to appear and worsen as the disease progresses: the dog becomes lethargic and muscle wastage occurs, as a result of proteinuria.
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A postulated solution to the problem of denaturation, is that newly formed collagen gets stored in vacuoles. The storage vacuoles also contain molecular aggregates that provide the required thermal stability to allow for fibrillogenesis to occur within the body. In the body, fibrillar collagens have over 50 known binding partners. The cell accounts for the variety of binding partners through the localization of the fibrillogenesis process to the plasma membrane in order to maintain control of which molecules bind to each other and further ensure both fibril diversity and assemblies of certain collagen fibrils in different tissues Kader, Hill, and Canty-Larid published a plausible mechanism for the formation of collagen fibrils.
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The cap is initially round to convex before flattening, reaching a diameter of . The caps of young fruit bodies have a smooth surface that is covered with smooth fibrils. The cap color is white to pale grey, changing to grayish brown in maturity. The cap margin is initially rolled inward.
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The angular pores are greater than 1 mm wide. The fruit body of Suillus sibiricus is a medium-sized bolete. The cap is at first hemispherical and straw yellow, but expands with maturity and finally flattens out becoming darker with reddish brown spots or fibrils. The cap diameter is up to .
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There are fibrils near the top of the stem. The partial veil is cortinate (cobweb-like, similar to the partial veil of Cortinarius species), and soon disappears. The flesh is whitish to yellowish, and bruises blue when injured. The taste and odor are slightly farinaceous (similar to freshly ground flour).
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The straight shape allows the molecules to pack closely. Cellulose is very common in application due to its abundant supply, its biocompatibility, and is environmentally friendly. Cellulose is used vastly in the form of nano-fibrils called nano-cellulose. Nano-cellulose presented at low concentrations produces a transparent gel material.
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The cortina (a cobweb-like partial veil consisting of silky fibrils) is violet. The flesh is violet lilac or violet, paling slightly when mature, and with a weak, unpleasant smell and mild taste. When cut or broken it turns purple, like the gills. It is an edible mushroom of medium quality.
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The surface of apex is white, and silky- striate. The lower portion is white, with the fibrils forming scattered appressed squamules. In contrast, the base of the stipe discolors slowly a dull orange-brown where handled. The flesh changes sporadically from a cream- yellow to tawny-brown when injured or cut.
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Polycarpa fibrosa is a species of tunicate in the family Styelidae. It is brown and globular and its outer surface is covered with a mat of fibrils. It normally lies buried in soft sediment on the seabed with only its two siphons protruding. It occurs in the Arctic Ocean and northern Atlantic Ocean.
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Polyp prey includes copepods and fish larvae.Chang, T.D. and Sullivan, J.M. "Temporal associations of coral and zooplankton activity on a Caribbean reef " Dartmouth Studies in Tropical Ecology. 2008. Accessed 2009-06-21. Longitudinal muscular fibrils formed from the cells of the ectoderm allow tentacles to contract when conveying the food to the mouth.
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With junctional epidermolysis bullosa, layers of the lamina lucida (part of the basal lamina) separate. This is caused by mutations in integrin α6β4, laminin 322 and BPAG2. In dystrophic epidermolysis bullosa, the layers of the papillary dermis separate from the anchoring fibrils. This is caused by mutations in the collagen 7 gene.
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Other birds with breast muscle more suitable for sustained flight, such as ducks and geese, have red muscle (and therefore dark meat) throughout. Some cuts of meat including poultry expose the microscopic regular structure of intracellular muscle fibrils which can diffract light and produce iridescent colors, an optical phenomenon sometimes called structural coloration.
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However, thinner fibrils can also be detected. Wågberg et al. reported fibril widths of 5–15 nm for a nanocellulose with a charge density of about 0.5 meq./g. The group of Isogai reported fibril widths of 3–5 nm for TEMPO-oxidized cellulose having a charge density of 1.5 meq./g.
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Healthy ovaries present in SHG a uniform epithelial layer and well-organized collagen in their stroma, whereas abnormal ones show an epithelium with large cells and a changed collagen structure. The r ratio is also used to show that the alignment of fibrils is slightly higher for cancerous than for normal tissues.
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In the acquired form of FX deficiency an insufficient amount of factor X is produced by the liver due to liver disease, vitamin K deficiency, buildup of abnormal proteins in organs (amyloidosis) or certain medications (i.e. warfarin). In amyloidosis FX deficiency develops as FX and other coagulation factors are absorbed by amyloid fibrils.
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Crazing occurs in regions of high hydrostatic tension, or in regions of very localized yielding, which leads to the formation of interpenetrating microvoids and small fibrils. If an applied tensile load is sufficient, these bridges elongate and break, causing the microvoids to grow and coalesce; as microvoids coalesce, cracks begin to form.
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Although they are in an amorphous mineral phase while inside the vesicles, the mineral destabilizes as it passes out of the cell and crystallizes. In bone, studies have shown that calcium phosphate nucleates within the hole area of the collagen fibrils and then grows in these zones until it occupies the maximum space.
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Misfolded proteins can form protein aggregates or amyloid fibrils, get degraded, or refold back to its native structure. Protein aggregation is a biological phenomenon in which intrinsically disordered proteins or mis-folded proteins aggregate (i.e., accumulate and clump together) either intra- or extracellularly. Mis-folded protein aggregates are often correlated with diseases.
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Aquamelts were defined as a new class of polymeric material as a result of a comparison between the spinning feedstock of the Chinese silkworm (Bombyx mori) and molten high- density polyethylene (HDPE) using shear induced polarised light imaging (SIPLI). The current understanding of shear induced fibrillation requires polymer chains to undergo the following series of steps i) long-chain molecules are stretched, ii) and form persistent point nuclei, which iii) align under flow into rows and then iv) grow to create a crystalline fibrils. For these fibrils to remain, the temperature of the sample must be lowered to below the polymers melt point. This process is analogous to the fibrilogenesis of natural silk-polymers in which proteins align (refold), nucleate (denature), and crystallize (aggregate).
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The ultrastructure of several species is well known. The periplast of H. brunnescens has crystalline plates and an unusual secondary layer composed of small "sausage-like" fibrils. The nucleomorph is located outside the pyrenoid between the pyrenoid and the nucleus. The flagella are covered with a layer of fibrillary scales overlapping with each other.
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Mushrooms with an appearance similar to S. lakei can often be distinguished by their associations with trees. For example, the eastern North American species S. spraguei grows in association with Eastern White Pine. The cap of S. spraguei has red fibrils on a yellow background. S. cavipes and S. ochraceoroseus always grow with Larch.
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The dermis is thinned because of this. In heterozygous cats, normal and abnormal fibrils often exist inside of the same collagen fiber. Homozygous cats are not likely to survive for very long. The autosomal recessive form of feline cutaneous asthenia results in a deficiency of procollagen peptidase or a structural abnormality at its cleavage site.
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The stipe is 5–12 cm long and 0.7-2.0 cm in diameter, usually thicker at the base. It is covered with brown vertical fibrils on a white ground. The flesh is soft and white. The mushroom has a mild to earthy radish smell and a mild taste at first, which may become slightly bitter.
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Evidence for the existence of alpha-sheet in a mutant form of transthyretin has been presented.Hilaire MR, Ding B, Mukherjee D, Chen J, Gai F. (2018). Possible existence of alpha-sheets in the amyloid fibrils formed by a mutant form of a peptide from transthyretin. Journal of the American Chemical Society 140:629-635.
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Histologically, the Descemet's membrane in CHED becomes diffusely thickened and laminated. Multiple layers of basement membrane-like material appear to form on the posterior part of Descemet's membrane. The endothelial cells are sparse - they become atrophic and degenerated, with many vacuoles. The corneal stroma becomes severely disorganised; the lamellar arrangement of the fibrils becomes disrupted.
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This can happen if the bonding between these lamellae is high. Ψ refers to the angle between the tensile axis and the collagen fibril. Mechanisms 1 and 2 both decrease Ψ. Mechanisms 3 and 4 can increase Ψ, as in, the fibril moves away from the tensile axis. Fibrils with a small Ψ stretch elastically.
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Groups at risk include people who do manual labor, musicians, and athletes. Less common causes include infection, arthritis, gout, thyroid disease, and diabetes. Diagnosis is typically based on symptoms, examination, and occasionally medical imaging. A few weeks following an injury little inflammation remains, with the underlying problem related to weak or disrupted tendon fibrils.
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Epidermolysis bullosa dystrophica, also known as Dystrophic EB (DEB) is a chronic skin condition caused when anchoring fibrils are abnormal, diminished, or absent. This causes a weak dermoepidermal junction, where the epidermis easily separates from the dermis causing much pain. This condition is caused by a mutation of COL7A1, the gene that codes for a type of collagen 7.
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It has yellowish fibrils surrounding its base, as well as white rhizomorphs attaching the base to the substrate. The mushroom has thin, cream- colored flesh with an indistinct odor and a taste that is initially mild before becoming slightly bitter. The spore print is white. Spores are elliptical, thin-walled, and amyloid, measuring 4.2–6 by 2.5–3.5 µm.
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This gene encodes a DEAD box protein, which exhibits RNA-dependent ATPase and ATP-dependent RNA- unwinding activities. This protein is recruited to the cytoplasmic fibrils of the nuclear pore complex, where it participates in the export of mRNA from the nucleus. Multiple alternatively spliced transcript variants encoding different isoforms have been found for this gene.
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The stipe is 9–19 cm long, 3–5 cm thick, and equal to clavate. The core of the stem is stuffed, while the surface is dry and white with scattered fibrils at the apex. However, the base is a discoloring dingy brownish-red to ochraceous. Also, the stipe can be smooth to patchy fibrillose below.
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It is solid (i.e., not hollow), white to pale yellow, and covered with tufts of soft woolly hairs or fibrils. It has a large basal bulb, swollen in the middle, which roots in the ground up to . The partial veil is yellowish-white to pale yellow, forming a ring which is thick, woolly, delicate, and soon falls away.
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The top of the stem is covered with short fibrils, pure white, sometimes becoming grayish or dirty with age. It is initially stuffed with cotton-like mycelia, then later becomes hollow. The caps of dried fruit bodies will typically remain white, while the stems will dry darker, especially if they are initially waterlogged.Smith, 1947, pp. 253–55.
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In vitro tests yield evidence that suggest tenascin X accelerates collagen fibril formation through an additive mechanism when collagen VI is present. In addition to tenascin X, multiple proteins, glycoconjugates, and small molecules have shown to influence not only the rate of collagen fibrillogenesis, but also the structure of collagen fibrils as well as their size in lab studies.
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The stipe, or stalk, is tall, and thick. Due to its swollen, bulbous nature, the base of the stipe can sometimes be as wide as . The stipe is a similar colour to the cap, and covered in wool- like fibrils; purple mycelium can be present at the base. Younger specimens feature a veil, but this vanishes quickly.
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Alterations in the organization or polarity of the collagen fibrils can be signs of pathology,. In particular, the anisotropy of alignment of collagen fibers allowed to discriminate healthy dermis against pathological scars in skin. Also, pathologies in cartilage such as osteoarthritis can be probed by polarization- resolved SHG microscopy,. SHIM was later extended to fibro-cartilage (meniscus).
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These adhesion fibrils are also seen in other species of skates. The surface of the capsule is striated and presents a rough surface though it is relatively smooth. Atlantoraja castelnaui capsule's are also the largest egg capsule in its genus and compared to other co-occurring species in the same area and depth of the ocean.
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The cap features an umbo that is usually very prominent. Around the umbo, the cap surface is smooth, but towards the cap margin, the surface is defined by fibrils running from the margin towards the umbo. The cap sometimes splits along these. The cap's colour varies from yellow-brown to pale brown, and is palest at the margins.
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As opposed to their northern counterparts, the southern subspecies have eggs that lack filaments (adhesive chorionic fibrils) and they often deposit those eggs inside empty mussel shells. The two subspecies are also distinguished based on slight morphological and genomic differences. Most mummichogs become sexually mature when two years old, around in length. Normal lifespan is four years.
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APP appears to play roles in normal neuron growth, survival and post-injury repair. APP is cleaved into smaller fragments by enzymes such as gamma secretase and beta secretase. One of these fragments gives rise to fibrils of beta-amyloid which can self-assemble into the dense extracellular deposits known as senile plaques or amyloid plaques.
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His current work focuses on formation of amyloid fibrils and his research has shown multiple pathways of aggregation in the formation of amyloid fibrils of different morphologies. Udgaonkar has published a number of articles in peer reviewed journals detailing his researches, Google Scholar and ResearchGate, two online repositories of scientific articles, have listed several of them. A former guest editor of the Current Opinion in Structural Biology of Elsevier (2013 and 2015) and a former editorial board member of Folding and Design (1996–98), he is an associate editor of the Biochemistry journal and a member of the editorial board of Protein Engineering, Design and Selection (since 2003), an Oxford journal. He is also a member of the Asia-Pacific International Molecular Biology Network since 2001 and has mentored several scholars in their doctoral researches.
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The cross-β pattern is considered a diagnostic hallmark of amyloid structure. Amyloid fibrils are generally composed of 2–8 protofilaments (four are shown in the figure), each 2–7 nm in diameter, that interact laterally as flat ribbons that maintain the height of 2–7 nm (that of a single protofilament) and are 30 nm wide; more often protofilaments twist around each other to form the typically 5–15 nm wide fibrils. Each protofilament possesses the typical cross-β structure and may be formed by 1–4 β-sheets (two are shown in the figure) stacked on each other. Each individual protein molecule can contribute one to several β-strands in each protofilament and the strands can be arranged in antiparallel β-sheets, but more often in parallel β-sheets.
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Then the osteoblasts create an extracellular matrix containing Type-I collagen fibrils, which is osteoid. The osteoblasts, while lining the periphery of the nidus, continue to form osteoid in the center of the nidus. Some of the osteoblasts become incorporated within the osteoid to become osteocytes. Light micrograph of an undecalcified nidus consisting of rudimentary bone tissue that is lined by numerous osteoblasts.
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Closeup image of the skin of a marbled eel The cross helical fiber arrangement of the two dermal fibers types collagen and elastin, are responsible for the mechanical properties of the skinL. Yang. Mechanical properties of native and cross-linked type i collagen fibrils. Biophysical Journal, 94(6):2204–2211, March 2008. such as the two dimensional stiffness seen in the eel skin.
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Boletus reticuloceps is a species of fungus in the family Boletaceae. The species was first described scientifically in 1993 as Aureoboletus reticuloceps, and later transferred to the genus Boletus in 2005. The fruit bodies have a dry cap, that is yellowish-brown, deeply wrinkled and reticulated, and covered with fibrils that form minute brown scales. Its stem is finely reticulated.
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When an action potential causes cells to contract, calcium is released from the sarcoplasmic reticulum of the cells as well as the T tubules. The calcium release triggers sliding of the actin and myosin fibrils leading to contraction. A plentiful supply of mitochondria provide the energy for the contractions. Typically, cardiomyocytes have a single, central nucleus, but can also have two or more.
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The cap is campanulate (bell- shaped), and later flattens, but retains a broad umbo (shield-like central boss). It is usually between across, brownish ochre, or umber and with a darker centre. It is covered in fine fibrils, and is dry. The stipe is usually the same colour as the cap or paler, and is smooth, or finely fibrillose like the cap.
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These fibrils can form randomly oriented networks that provide the mechanical strength of the organic layer in different biological materials. Chitin provides protection and structural support to many living organisms. It makes up the cell walls of fungi and yeast, the shells of mollusks, the exoskeletons of insects and arthropods. In shells and exoskeletons, the chitin fibers contribute to their hierarchical structure.
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Collagen is a structural protein, often referred to as “the steel of biological materials”. There are multiple types of collagen: Type I (comprising skin, tendons and ligaments, vasculature and organs, as well as teeth and bone); Type II (a component in cartilage); Type III (often found in reticular fibers); and others. Collagen has a hierarchical structure, forming triple helices, fibrils, and fibers.
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The surface textures ranges from smooth to covered with scattered appressed fibrils and scales. The closely spaced gills are whitish but develop brownish to reddish-brown stains in maturity. They are narrowly attached to the stipe, sometimes by a notch. The often hollow stipe measures long by thick, and is either roughly the same width throughout, or tapers slightly to the base.
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Nucleoli are usually multiple and prominent. Subcellular characteristics often noted in the malignant giant cells of GCCL cases include abundant mitochondria, concentric whorls of tonofilament-like fibrils, and aggregates of several pairs of centrioles. Both "tumor cell-tumor cell" and "leukocyte-tumor cell" emperipolesis (i.e. active penetration of the latter by the former) is very commonly seen in cases of GCCL.
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Surrounded by the amorphous mineral phase are chitin fibrils, which make up a Bouligand structure. The layered arrangement of the periodic region corresponds to a compete 180° rotation of the fibers. The impact region has a similar structure, but with a larger pitch distance (length between compete 180° rotation). The striated region is made of highly aligned parallel chitin fiber bundles.
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The stipe is hollow, whitish in color, and covered with white fibrils. It is the same color as the cap, and stains blue when bruised. The odor and taste are slightly like grain meal (farinaceous). Spores have been recorded in the range of 10.4-12.8 by 6.4-8 μm and have a thick wall with a flattened, broad germ pore.
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The region of small strains, "toe" region, corresponds to the removal of a macroscopic crimp, uncrimping, in the collagen fibrils, visible in light microscope. At larger strains, "heel" and "linear" region, there's no further structural change visible. Tropocollagen is the molecular component fiber, consisting of three left handed polypeptide chains (red, green, blue) coiled around each other, forming a right-handed triple helix.
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ADAMTS2 is responsible for processing several types of procollagen proteins. Procollagens are the precursors of collagens, the proteins that add strength and support to many body tissues. Specifically, this enzyme clips a short chain of amino acids off one end of the procollagen. This clipping step is necessary for collagen molecules to function normally and assemble into fibrils outside cells.
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Cupula is a gelatinous sack covering over hair like neuromast protruding from the skin. Cupula formed over neuromast is another feature that developed over time that provides a better response to the flow field. Cupular fibrils extend from the hair-like neuromast. Cupula helps attenuate low- frequency signals by virtue of its inertia and amplify higher frequency signals due to the leverage.
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Unlike primary dentin, mantle dentin lacks phosphorylation, has loosely packed collagen fibrils and is less mineralized. Below it lies the circumpulpal dentin, more mineralized dentin which makes up most of the dentin layer and is secreted after the mantle dentin by the odontoblasts. Circumpulpal dentin is formed before the root formation is completed. Newly secreted dentin is unmineralized and is called predentin.
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No calretinin expression is seen in the nerve trunks in the rest of the aganglionic segment. It has faint expression in the thick nerve trunks from the areas without ganglion cells. Faint positivity of the thick submucosal and subserosal nerves in the absence of ganglion cells and calretinin positive nerve fibrils, is characteristic of the junction of the aganglionic-to-normal rectum.
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Human bone marrow derived Mesenchymal stem cell showing fibroblast-like morphology seen under phase contrast microscope (carl zeiss axiovert 40 CFL) at 63 x magnification An example of human mesenchymal stem cells imaged with a live cell imaging microscope Mesenchymal stem cells are characterized morphologically by a small cell body with a few cell processes that are long and thin. The cell body contains a large, round nucleus with a prominent nucleolus, which is surrounded by finely dispersed chromatin particles, giving the nucleus a clear appearance. The remainder of the cell body contains a small amount of Golgi apparatus, rough endoplasmic reticulum, mitochondria and polyribosomes. The cells, which are long and thin, are widely dispersed and the adjacent extracellular matrix is populated by a few reticular fibrils but is devoid of the other types of collagen fibrils.
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Both chemical pulps and mechanical pulps may be bleached to a high brightness. Chemical pulping dissolves the lignin that bonds fibres to one another, and binds the outer fibrils that compose individual fibres to the fibre core. Lignin, like most other substances that can separate fibres from one another, acts as a debonding agent, lowering strength. Strength also depends on maintaining long cellulose molecule chains.
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This action unravels the outer layer of the fibres, causing the fibrils of the fibres to partially detach and bloom outward, increasing the surface area to promoting bonding. Refining thus increases tensile strength. For example, tissue paper is relatively unrefined whereas packaging paper is more highly refined. Refined stock from the refiner then goes to a refined stock chest, or blend chest, if used as such.
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A skeletal muscle fiber is surrounded by a plasma membrane called the sarcolemma, which contains sarcoplasm, the cytoplasm of muscle cells. A muscle fiber is composed of many fibrils, which give the cell its striated appearance. Skeletal muscles are sheathed by a tough layer of connective tissue called the epimysium. The epimysium anchors muscle tissue to tendons at each end, where the epimysium becomes thicker and collagenous.
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Polycarpa fibrosa is globular or ovoid in shape and is about in diameter. It has a sac-like body with a tough covering known as a tunic, and is densely clad in short fibrils. There are two long, tapering, four-lobed siphons on the upper surface. Water is drawn into the body cavity through one of these, the buccal siphon, and expelled through the atrial siphon.
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Fruitbodies have yellow-olivaceous or olive-tan caps that measure in diameter. There are grooves on the cap margin that extend about 40% of the distance from the margin to the apex. The spores are spherical or nearly so, typically measuring by . The white stipe is ornamented with slightly darker fibrils, and there are sac-like remnants of the volva at the stipe base.
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On evidence of immunofluorescence analysis, the CKAP2 product is a cytoplasmic protein associated with cytoskeletal fibrils. The CKAP2 gene is in chromosome 13q14. Rearrangements of this region result in various tumors. Thus deletions have been detected in multiple myeloma, prostate cancer, head-and-neck squamous-cell carcinoma, B-cell prolymphocytic leukemia, non-Hodgkin lymphoma, and in more than half cases of B-cell chronic lymphocytic leukemia.
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The latter is similar, though run at much higher temperatures, to melt-blown thermoplastic nonwovens. Wet laid mat is almost always wet resin bonded with a curtain coater, while batts are usually spray bonded with wet or dry resin. An unusual process produces polyethylene fibrils in a Freon-like fluid, forming them into a paper-like product and then calendering them to create Tyvek.
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Most ligaments are mostly made of highly aligned collagen fibres which do not permit stretching. Structurally, the nuchal ligament is formed with the association of both elastin proteins as well as type III collagen (45%). The collagen fibrils share a consistent size as well as helical pattern which gives the ligament its tensile strength. The elastin on the other hand is a protein that allows for flexibility.
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These include collagen, cellulose, chitin and tunican. These structural proteins must be processed before use in composites. To use cellulose as an example, semicrystalline microfibrils are sheared in the amorphous region, resulting in microcrystalline cellulose (MCC). These small, crystalline cellulose fibrils are at this points reclassified as a whisker and can be 2 to 20 nm in diameter with shapes ranging from spherical to cylindrical.
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Static light scattering allows monitoring of the sizes of the species in solution. Since proteins typically aggregate upon denaturation (or form fibrils) the detected species size will go up. This is label-free and independent of specific residues in the protein or buffer composition. The only requirement is that the protein actually aggregates/fibrillates after denaturation and that the protein of interest has been purified.
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This occurs when the stress applied is sufficient to separate the closely bound water from the protein, splitting the nanocomposite. This results in conformational changes to the protein and an increased probability to form hydrogen bonding between protein chains and subsequent solidification. Multiscale structures, i.e., fibrils or foams are the result of a combination of directional stress fields and the self-assembly properties of the aquamelt.
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In certain molluscs, a glial-interstitial fluid barrier is observed without the presence of tight junctions. Cephalopod molluscs, in particular, have cerebral ganglia that have microcirculation, often seen in the composition of higher organisms. Often, the glial cells will form a seamless sheath completely around the blood space. The barrier consists of zonular intercellular junctions, rather than tight junctions, with clefts formed by extracellular fibrils.
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Cellulose is synthesized by cellulose synthase or Rosette terminal complexes which reside on a cells membrane. As cellulose fibrils are synthesized and grow extracellularly they push up against neighboring cells. Since the neighboring cell can not move easily the Rosette complex is instead pushed around the cell through the fluid phospholipid membrane. Eventually this results in the cell becoming wrapped in a microfibril layer.
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One of them proposes the micellar nucleus is formed by several submicelles, the periphery consisting of microvellosities of κ-casein. Another model suggests the nucleus is formed by casein-interlinked fibrils. Finally, the most recent model proposes a double link among the caseins for gelling to take place. All three models consider micelles as colloidal particles formed by casein aggregates wrapped up in soluble κ-casein molecules.
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Gymnopilus maritimus is a fungus species of the family Cortinariaceae first collected in northern Sardinia, Italy, in 2006. The species produces moderately sized, sturdy mushrooms of a reddish-orange colour. The cap, which can measure up to across, is covered in orange fibrils, and sometimes has small scales. The yellowish stem measures up to in length by in width, and sometimes shows remnants of the partial veil.
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Scanning electron microscopy image of bone mineral Bone mineral (also called inorganic bone phase, bone salt, or bone apatite) is the inorganic component of bone tissue. It gives bones their compressive strength. Bone mineral is formed from carbonated hydroxyapatite with lower crystallinity. Bone mineral is formed from globular and plate structures distributed among the collagen fibrils of bone and forming yet a larger structure.
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The fetal membranes separate maternal tissue from fetal tissue at a basic mechanical level. The fetal membrane is composed of a thick cellular chorion covering a thin amnion composed of dense collagen fibrils. The amnion is in contact with the amniotic fluid and ensures structural integrity of the sac due to its mechanical strength. The underlying chorion is fused to the decidua at the maternal-fetal interface.
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The gene expression signature associated with emphysema severity included 127 genes, involved in inflammation and repair. Using the Connectivity Map, researchers established that the peptide GHK downregulated genes involved in lung destruction and inflammation, while upregulating genes involved in tissue repair. Addition of 10 nanomolar GHK to lung fibroblasts from emphysema lungs restored their ability to remodel collagen and assemble it into properly organized fibrils.
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The cap surface is smooth, the margin is even and in young specimens, rolled inward and covered with short fibrils. The flesh is white, thick in the center of the cap but thinning toward the margin. The odor and taste are mild. The gills are somewhat arcuate-decurrent, meaning they are shaped like a bow, curving upward and then running down the stem for a short distance.
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Hydration has been shown to produce a noticeable effect in the mechanical properties of fibrillar materials. The presence of water has been shown to decrease the stiffness of collagen fibrils, as well as increase their rate of stress relaxation and strength. From a biological standpoint, water content acts as a toughening mechanism for fibril structures, allowing for higher energy absorption and greater straining capabilities.
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Collagen is synthesized as a soluble precursor, procollagen, which supports collagen self-assembly. Since collagen fibrils have almost 50 binding components in vivo, the definite requirement to generate fibrillogenesis in vivo is still cryptic. With acidic or saline solution, collagen can be extracted from tissues and rearrange into fibril by changing temperature or pH value. Experiments discovered attractive force between collagen monomers which helps the rearrangement.
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Human cornea is a transparent membrane which allows light to pass through it. The word corneal opacification literally means loss of normal transparency of cornea. The term corneal opacity is used particularly for the loss of transparency of cornea due to scarring. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma.
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The stipe is 2.0-7.0 cm long, 1.5-3.0 cm thick, and more or less equal except for a bulbous base. In addition, it has a narrow, cottony central core. The surface of the apex is palled and finely striate, while the lower stipe can vary from glabrous to sparsely covered with whitish fibrils, occasionally sheathed with cottony-floccose veil remnants. Like the cap, it yellows.
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The stroma of the cornea (or substantia propria) is a fibrous, tough, unyielding, perfectly transparent and the thickest layer of the cornea of the eye. It is between Bowman's membrane anteriorly, and Descemet's membrane posteriorly. At its centre, human corneal stroma is composed of about 200 flattened lamellæ (layers of collagen fibrils), superimposed one on another. They are each about 1.5-2.5 μm in thickness.
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The human form of IAPP has the amino acid sequence KCNTATCATQRLANFLVHSSNNFGAILSSTNVGSNTY, with a disulfide bridge between cysteine residues 2 and 7. Both the amidated C-terminus and the disulfide bridge are necessary for the full biological activity of amylin. IAPP is capable of forming amyloid fibrils in vitro. Within the fibrillization reaction, the early prefibrillar structures are extremely toxic to beta-cell and insuloma cell cultures.
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There are also two hierarchical structures on the nanoscale. The first being the structure inside the ultrastructure that are fibrils and extrafibrillar space, at a scale of several hundred nanometres. The second are the elementary components of mineralized tissues at a scale of tens of nanometres. The components are the mineral crystals of hydroxyapatite, cylindrical collagen molecules, organic molecules such as lipids and proteins, and finally water.
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This process is reversible, as reverting the temperature and humidity changes caused the sample to unroll again. Understanding anisotropic swelling and mapping the alignment of printed fibrils allowed A. Sydney Gladman et al. to mimic the nastic behavior of plants. Branches, stems, bracts, and flowers respond to environmental stimuli such as humidity, light, and touch by varying the internal turgor of their cell walls and tissue composition.
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Type II collagen is the basis for articular cartilage and hyaline cartilage, formed by homotrimers of collagen, type II, alpha 1 chains. It makes up 50% of all protein in cartilage and 85–90% of collagen of articular cartilage. Type II collagen does form fibrils. This fibrillar network of collagen allows cartilage to entrap the proteoglycan aggregate as well as provide tensile strength to the tissue.
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In all of these instances, an aberrant form of the protein itself appears to be the pathogenic agent. In some cases, the deposition of one type of protein can be experimentally induced by aggregated assemblies of other proteins that are rich in β-sheet structure, possibly because of structural complementarity of the protein molecules. For example, AA amyloidosis can be stimulated in mice by such diverse macromolecules as silk, the yeast amyloid Sup35, and curli fibrils from the bacterium Escherichia coli. In addition, apolipoprotein AII amyloid can be induced in mice by a variety of β-sheet rich amyloid fibrils, and cerebral tauopathy can be induced by brain extracts that are rich in aggregated Aβ. There is also experimental evidence for cross-seeding between prion protein and Aβ. In general, such heterologous seeding is less efficient than is seeding by a corrupted form of the same protein.
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Proline or hydroxyproline is often found in the X- and Y-position giving the triple helix stability. In addition to being an integral structural component of many organs, type III collagen is also an important regulator of the diameter of type I and II collagen fibrils. Type III collagen is also known to facilitate platelet aggregation through its binding to platelets and therefore, play an important role in blood clotting.
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The buccal siphon has a ring of up to 60 tentacles round the rim. These function to prevent particles that are too large from being drawn into the body cavity. This tunicate is a brownish colour and is well camouflaged, as particles of sand, shell fragments and mud adhere to the fibrils. It is usually partially buried in the sediment on the seabed with the two siphons projecting.
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Asbestos (pronounced: or ) is a term used to refer to six naturally occurring silicate minerals. All are composed of long and thin fibrous crystals, each fibre being composed of many microscopic 'fibrils' that can be released into the atmosphere by abrasion and other processes. Asbestos is an excellent electrical insulator and is highly heat-resistant, so for many years it was used as a building material.Bureau of Naval Personnel, Basic Electricity.
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The stem base is rooted among the leaves and debris, and the base is covered with short stiff hairs pressed flat against the surface. Its surface is covered sparsely with minute purplish brown fibrils. The stem is dull reddish brown overall, but the color fades near the top. When mushroom tissue is cut or injured, it oozes a dull reddish-brown juice or, in old specimens, a dull orange juice.
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Maternal cells also synthesize and contribute a store of ribosomes that are required for the translation of proteins before the zygotic genome is activated. In mammalian oocytes, maternally derived ribosomes and some mRNAs are stored in a structure called cytoplasmic lattices. These cytoplasmic lattices, a network of fibrils, protein, and RNAs, have been observed to increase in density as the number of ribosomes decrease within a growing oocyte.
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PFM has been successfully applied to a range of biological materials such as teeth, bone, lung, and single collagen fibrils. It has been hypothesized that the endogenous piezoelectricity in these materials may be relevant in their mechanobiology. For example, using PFM it has been shown that a single collagen fibril as small as 100 nm behaves predominantly as a shear piezoelectric materials with an effective piezoelectric constant of ~1 pm/V.
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The individual macrocilium is between 50 and 60 micrometres long and 6 to 10 micrometres thick, with the cilia bonded together in a hexagonal cross-sectional structure by permanent fibrils in three different planes. A system of tubules connects the basal bodies from which the macrocilia grow. The macrocilia move in unison. They are angled towards the gullet and are stacked on top of each other like roof tiles.
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The same research also showed highly increased PARP activation in dopamine producing cells in the presence of MPTP. Alpha-synuclein is a protein that binds to DNA and modulates DNA repair. A key feature of Parkinson’s disease is the pathologic accumulation and aggregation of alpha-synuclein. In the neurons of individuals with Parkinson’s disease, alpha-synuclein is deposited as fibrils in intracytoplasmic structures referred to as Lewy bodies.
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Amyloidosis is a group of diseases in which abnormal proteins, known as amyloid fibrils, build up in tissue. Symptoms depend on the type and are often variable. They may include diarrhea, weight loss, feeling tired, enlargement of the tongue, bleeding, numbness, feeling faint with standing, swelling of the legs, or enlargement of the spleen. There are about 30 different types of amyloidosis, each due to a specific protein misfolding.
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In AA, symptoms may improve if the underlying condition is treated; eprodisate has been shown to slow renal impairment by inhibiting polymerization of amyloid fibrils. In ATTR, liver transplant is a curative therapy because mutated transthyretin which forms amyloids is produced in the liver. In 2018, patisiran was not recommended by NICE in the UK for hereditary transthyretin-related amyloidosis. As of July 2019 further review however is occurring.
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Caps range in shape from conical to bell-shaped, and have a prominent umbo. Stems are densely covered with whitish fibrils pressed flat against the surface. The P. yungensis fruit bodies have caps that are conical to bell-shaped in maturity, and reach a diameter of up to . The cap surface is smooth and sticky, and, in moist specimens, has faint radial striations (grooves) that extend almost to the margin.
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Identification of the core structure of lysozyme amyloid fibrils by proteolysis. J Mol Biol 361(3):551-61. A mechanism for direct alpha sheet and beta sheet interconversion has also been suggested, based on peptide plane flipping in which the αRαL dipeptide inverts to produce a ββ dihedral angle conformation. This process has also been observed in simulations of transthyretinYang MF, Lei M, Yordanov B, Huo SH. (2006).
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Fibrillogenesis can be analyzed through the use of turbidity tests. Turbidity is way of measuring the haziness, cloudiness, or fogginess of sample and also can be used to test the light-scattering properties of said sample. A turbidity test on fibrillogenesis will start with a sample of collagen triple-helices, which will have a low-level of turbidity. After fibrillogenesis is completed, the triple-helices will have formed fibrils.
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The anthropod exoskeleton is highly hierarchical. Polysaccharide chitin fibrils arrange with proteins to form fibers, the fibers coalesce into bundles, and then the bundles arrange into horizontal planes which are stacked helicoidally, forming the twisted plywood Bouligand structure. Repeating Bouligand structures form the exocuticle and endocuticle. Differences in the Bouligand structure of the exocuticle and endocuticle have been found to be critical for analyzing the mechanical properties of both regions.
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The stipe is 5–12 cm long, 2–3 mm thick, hollow, and vertically striate. It is blackish towards the base, greyish towards the apex, and pallid to whitish fibrils run the length of the stipe. The stipe is equal to slightly swollen at the base and lacks a partial veil. Panaeolus tropicalis spores are dark violet to jet black, ellipsoid, and 10.5–12.0 x 7–9 µm.
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There are over 30 collagens in nature that are similar in chemical composition but differ in terms of crystal structure. By far, collagen I and II are the most abundant. They initiatively form fibrils in vitro, while fibronectin, fibronectin-binding, collagen-binding integrins and collagen V are essential for collagen I forming and collagen XI for collagen II forming. Therefore, cellular mechanisms play key role in the protein self- assembly process.
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This enzyme cross-links tropocollagen into strong collagen fibrils. The defective collagen contributes to many of the aforementioned connective tissue manifestations of this disease. If copper levels become excessive, the protein will travel to the cell membrane and eliminate excess copper from the cell. Mutations in the ATP7A gene such as deletions and insertions lead to parts of the gene being deleted, resulting in a shortened ATP7A protein.
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There is not parental care so the eggs have a capsule that protects the embryo's development once the mother leaves. Collected egg capsules typically are rectangular and have horny process in each corner. They are also shiny and are medium brown in color. The capsules on the eggs are covered by adhesion fibrils that allow the egg to attach itself to the sea floor immediately after the mother releases them.
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Fibronectin is a glycoprotein that is believed to act as a template for the oriented deposition of the collagen fibers, stabilizing the collagen fibrils. Fibronectin also acts as a skeleton for the elastic tissue formation. Reticular and collagenous fibers were seen to run along the edges of the VF throughout the entire lamina propria. Fibronectin in the Reinke's space appeared to guide those fibers and orient the fibril deposition.
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The fibrils in the lamellae are directly continuous with those of the sclera, in which they are grouped together in fibre bundles. More collagen fibres run in a temporal- nasal direction than run in the superior-inferior direction. During development of the embryo, the corneal stroma is derived from the neural crest (a source of mesenchyme in the head and neck) which has been shown to contain mesenchymal stem cells.
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A significant quantity of fibrils resulting from primary nucleation and fibril elongation may be formed during the lag phase and secondary steps, rather than only fibril elongation, can be the dominant processes contributing to fibril growth during the exponential phase. With this new model, any perturbing agents of amyloid fibril formation, such as putative drugs, metabolites, mutations, chaperones, etc., can be assigned to a specific step of fibril formation.
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When moist, the surface is waxy and glossy. When it is dry, there is sometimes a zone of a different colour around the umbo, or radial streaks (that is, streaks from the center of the cap to the cap margin). The club-shaped stem measures from in height, and is thick. The stem is somewhat white, and, in texture, the surface can be silk-like or covered in fibrils.
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Once APP is activated, it is cut into smaller sections of other proteins. One of the fragments produced in this cutting process is β-amyloid. β-amyloid is “stickier” than any other fragment produced from cut-up APP, so it starts an accumulation process in the brain, which is due to various genetic and biochemical abnormalities. Eventually, the fragments form oligomers, then fibrils, beta-sheets, and finally plaques.
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The dihedral angles (φ, ψ) are about (–120°, 115°) in parallel sheets. It is rare to find less than five interacting parallel strands in a motif, suggesting that a smaller number of strands may be unstable, however it is also fundamentally more difficult for parallel β-sheets to form because strands with N and C termini aligned necessarily must be very distant in sequence . There is also evidence that parallel β-sheet may be more stable since small amyloidogenic sequences appear to generally aggregate into β-sheet fibrils composed of primarily parallel β-sheet strands, where one would expect anti-parallel fibrils if anti-parallel were more stable. In parallel β-sheet structure, if two atoms C and C are adjacent in two hydrogen-bonded β-strands, then they do not hydrogen bond to each other; rather, one residue forms hydrogen bonds to the residues that flank the other (but not vice versa).
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The pellicle rips into shreds when peeled. The pliant flesh is thin, 2 mm in the center of the cap and tapered evenly to the margin. The cap surface is covered with grayish fibrils; underneath the fibrils the color is initially the same as the cap, but becomes blackish-brown in age at the base or over lower parts. The gills are slightly darker than the cap in color, broadly adnate, but develop a slight decurrent tooth in age (when the gill separates slightly from the stem). The gills are broad (about 3 mm), with a close to subdistant spacing. Roughly 24 gills reach the cap edge from the stem; there are additionally 2 or three tiers of lamellulae—short gills that do not extend completely from the stem to the cap edge. The stem is long by 1.5–2.5 mm thick, and equal in width throughout its length. It is attached to its substrate (wood or sticks) by a grayish mat of mycelium.
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Normally folded proteins have to unfold partially before aggregation can take place through one of these mechanisms. In some cases, however, folded proteins can aggregate without crossing the major energy barrier for unfolding, by populating native-like conformations as a consequence of thermal fluctuations, ligand release or local unfolding occurring in particular circumstances. In these native-like conformations, segments that are normally buried or structured in the fully folded and possessing a high propensity to aggregate become exposed to the solvent or flexible, allowing the formation of native-like aggregates, which convert subsequently into nuclei and fibrils. This process is called ‘native-like aggregation’ (green arrows in the figure) and is similar to the ‘nucleated conformational conversion’ model. A more recent, modern and thorough model of amyloid fibril formation involves the intervention of secondary events, such as ‘fragmentation’, in which a fibril breaks into two or more shorter fibrils, and ‘secondary nucleation’, in which fibril surfaces (not fibril ends) catalyze the formation of new nuclei.
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The deficiency in anchoring fibrils impairs the adherence between the epidermis and the underlying dermis. The skin of DEB patients is thus highly susceptible to severe blistering. Collagen VII is also associated with the epithelium of the esophageal lining, and DEB patients may suffer from chronic scarring, webbing, and obstruction of the esophagus. Affected individuals are often severely malnourished due to trauma to the oral and esophageal mucosa and require feeding tubes for nutrition.
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20 kHz are used, which demands special equipment. A number of intermediate techniques, with samples of partial alignment or reduced mobility, is currently being used in NMR spectroscopy. Applications in which solid-state NMR effects occur are often related to structure investigations on membrane proteins, protein fibrils or all kinds of polymers, and chemical analysis in inorganic chemistry, but also include "exotic" applications like the plant leaves and fuel cells. For example, Rahmani et al.
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Skd3 is a potent disaggregase in vitro and is activated by PARL to increase disaggregation activity by over 10-fold. Indeed, PARL-activated Skd3 is capable of disassembling alpha-synuclein fibrils in vitro. Even though the bacterial orthologue, ClpB, contributes to the thermotolerance of cells, it is yet unclear if Skd3 plays a similar role within mitochondria. The interaction with protein like HAX1 suggests that human Skd3 may be involved in apoptosis.
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This is achieved by a distributed, internal network of cooperative interactions (hydrophobic, polar and covalent). Protein structural robustness results from few single mutations being sufficiently disruptive to compromise function. Proteins have also evolved to avoid aggregation as partially folded proteins can combine to form large, repeating, insoluble protein fibrils and masses. There is evidence that proteins show negative design features to reduce the exposure of aggregation- prone beta-sheet motifs in their structures.
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Amyloid cardiomyopathy (stiff heart syndrome) is a condition resulting in the death of part of the myocardium (heart muscle). It is associated with the systemic production and release of many amyloidogenic proteins, especially immunoglobulin light chain or transthyretin (TTR). It can be characterized by the extracellular deposition of amyloids, foldable proteins that stick together to build fibrils in the heart. The amyloid can be seen under polarized light in congo red stained biopsy.
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The tenocytes produce the collagen molecules, which aggregate end-to-end and side-to-side to produce collagen fibrils. Fibril bundles are organized to form fibres with the elongated tenocytes closely packed between them. There is a three-dimensional network of cell processes associated with collagen in the tendon. The cells communicate with each other through gap junctions, and this signalling gives them the ability to detect and respond to mechanical loading.
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The structure is cone-shaped with its apex forming a binding site for HDL and heparin. The N-terminal helices 1 and 3 have been identified as amyloidogenic peptides of SAA1.1, that are not presence on protein surface in native SAA1 protein. These findings provide the structural basis for the formation of amyloid A fibrils. The human SAA1.1 is comparable at the subunit level with the recently solved structure of mouse Saa3.
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Substances containing gelatin or functioning in a similar way are called gelatinous substances. Gelatin is an irreversibly hydrolyzed form of collagen, wherein the hydrolysis reduces protein fibrils into smaller peptides; depending on the physical and chemical methods of denaturation, the molecular weight of the peptides falls within a broad range. Gelatin is in gelatin desserts; most gummy candy and marshmallows; and ice creams, dips, and yogurts. Gelatin for cooking comes as powder, granules, and sheets.
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Modified proteins such as immunoglobulin light chains abnormally accumulate between cells, forming fibrils. Multiple folds of these fibers line up and take on a beta-pleated sheet conformation. Congo red dye intercalates between the folds and, when observed under polarized light, causes birefringence. In ophthalmology, binocular retinal birefringence screening of the Henle fibers (photoreceptor axons that go radially outward from the fovea) provides a reliable detection of strabismus and possibly also of anisometropic amblyopia.
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It is more common in the radicular pulp. Pulp stones with regular calcification grow in size by addition of collagen fibrils to their surface, whereas the irregular type of pulp stones are formed by calcification of pre-existing collagen fibres. Pulp stones may also form around epithelial cells such as remnants of Hertwig's epithelial root sheath. It is presumed that epithelial remnants are able to induce adjacent mesenchymal stem cells to differentiate into odontoblast.
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While the pathogenesis of LECT2 amyloidosis is unclear, the intact LECT2 protein may have a tendency to fold abnormally thereby forming non-soluble fibrils that are deposited in tissues. It has been suggested that individuals with the disease have an increase in LECT2 production and/or a decrease in LECT2 catabolism (i.e. breakdown) which leads to its tissue deposition. However, there appears to be clear genetic variations which lead LECT2 tissue deposition.
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The sample nanostructures are flash freeze at −196 °C and can be studied three-dimensionally. Transmission electron microscopy was used. Using computer technology, a molecular model of peptides and their interactions can be built and studied. Specific tests can be performed on certain peptides; for example a fluorescent emission test could be applied to amyloid fibrils by using the dye Thioflavin T that binds specifically to the peptide and emits blue fluorescence when excited.
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The conformational change is widely accepted as the result of protein misfolding. What distinguishes TSEs from other protein misfolding diseases is its transmissible nature. The ‘seeding’ of the infectious PrPSc, either arising spontaneously, hereditary or acquired via exposure to contaminated tissues, can cause a chain reaction of transforming normal PrPc into fibrils aggregates or amyloid like plaques consist of PrPSc. The molecular structure of PrPSc has not been fully characterized due to its aggregated nature.
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Thus, the single spermatozoa is about 130 μm long overall, with a diameter of 0.7 μm, which becomes narrower near the tail area, reaching 0.2 μm. The sperm is arranged into an agglomeration of around 340-350 individual spermatozoa that create a torch-like shape. The cup part is made up of acrosomes and nucleus, while the handle is made up by the tails. The spermatozoa in the package are held together by fibrils.
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Fibrils also coat the package itself to ensure cohesion. The large ovaries of females run within the gonocoel along the entire length of the trunk and are ventral to the trophosome. Eggs at different maturation stages can be found in the middle area of the ovaries, and depending on their developmental stage, are referred to as: oogonia, oocytes, and follicular cells. When the oocytes mature, they acquire protein and lipid yolk granules.
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The protofilament structure of insulin amyloid fibrils. Proc. Natl. Acad. Sci. USA 99, 9196–9201. An alpha-sheet amyloid intermediate is suggested to explain some anomalous features of the amyloid fibrillization process, such as the evident amino acid sequence dependence of amyloidogenesis despite the belief that the amyloid fold is mainly stabilized by the protein backbone.Fraser, P. E., Duffy, L. K., O'Mally, M. B., Nguyen, J., Inouye, H. & Kirschner, D. A. (1991).
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Nanocellulose Nanocellulose is a term referring to nano-structured cellulose. This may be either cellulose nanocrystal (CNC or NCC), cellulose nanofibers (CNF) also called nanofibrillated cellulose (NFC), or bacterial nanocellulose, which refers to nano-structured cellulose produced by bacteria. CNF is a material composed of nanosized cellulose fibrils with a high aspect ratio (length to width ratio). Typical fibril widths are 5–20 nanometers with a wide range of lengths, typically several micrometers.
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C1q is a 400 kDa protein formed from 18 peptide chains in 3 subunits of 6. Each 6 peptide subunit consists of a Y-shaped pair of triple peptide helices joined at the stem and ending in a globular non-helical head. The 80-amino acid helical component of each triple peptide contain many Gly-X-Y sequences, where X and Y are proline, isoleucine, or hydroxylysine; they, therefore, strongly resemble collagen fibrils.
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The parasite was discovered in the jaú catfish (Zungaro jahu). The plasmodia were found in the connective tissue of the gill arch, skin, serosa of the body cavity, urinary bladder and eye. They were white and round and measured 0.3-2.0mm in diameter. They were surrounded by double layered collagen capsule: the outer layer possessed fibers with distinct orientation from the adjacent connective tissue while the inner layer was composed of more delicate fibrils.
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It is used commercially in perfumes and other cosmetics. It has been shown that cuminaldehyde, as a small molecule, inhibits the fibrillation of alpha-synuclein, which, if aggregated, forms insoluble fibrils in pathological conditions characterized by Lewy bodies, such as Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. Cuminaldehyde can be prepared synthetically by the reduction of 4-isopropylbenzoyl chloride or by the formylation of cumene. The thiosemicarbazone of cuminaldehyde has antiviral properties.
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The hexagonal pores are a characteristic feature The fruit bodies of P. alveolaris are in diameter, rounded to kidney- or fan-shaped. Fruit bodies sometimes have stems, but they are also found attached directly to the growing surface. The cap surface is dry, covered with silk-like fibrils, and is an orange-yellow or reddish-orange color, which weathers to cream to white. The context is thin (2 mm), tough, and white.
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Spicules last for about 15 minutes; at the solar limb they appear elongated (if seen on the disk, they are known as "mottles" or "fibrils"). They are usually associated with regions of high magnetic flux; their mass flux is about 100 times that of the solar wind. They rise at a rate of 20 km/s (or 72,000 km/h) and can reach several thousand kilometers in height before collapsing and fading away.
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Hyalocytes, also known as vitreous cells, are cells of the vitreous body, which is the clear gel that fills the space between the lens and the retina of the eye. Hyalocytes occur in the peripheral part of the vitreous body, and may produce hyaluronic acid, collagen, fibrils, and hyaluronan. Hyalocytes are star-shaped (stellate) cells with oval nuclei. The development of the vitreous is organized into three stages: primary, secondary, and tertiary.
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Cortinarius badiolaevis produces mushrooms which each feature a smooth, brown to reddish-brown cap of between in diameter. The caps are initially hemispherical in shape, but as the mushrooms age, they become a low convex or even almost flat. There is a broad, blunt umbo in the center of the cap, and a white margin, covered in small fibrils. The cap is hygrophanous, meaning it changes colour depending on its moisture content.
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For example, Xiaochen Bai in his group solved the structure of human Gamma secretase in a collaboration with Shi Yigong, and Anthony Fitzpatrick in his group solved the structure of Amyloid fibrils of Tau protein from the brain of an individual with Alzheimer's disease in a collaboration with Michel Goedert. Scheres has been a member of the Faculty of 1000 from 2016, and a member of the Board of Reviewing Editors for eLife since 2014.
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The ECM of joint cartilage comprises many classes of macromolecules; collagen (type I, II, VI, X collagen fibrils) and proteoglycans. The ratio and the proportion of collagen play an important role in the tensile and compressive strength, as well as the elasticity of the tissue. The content of collagen in cartilage is different between joints and soft tissue structures. For example, cartilage in the knee has a different structure to the ankle.
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Females tend to be paler, without bars or the intense yellow on the belly, and their dorsal fin is uniformly coloured. Adults of the two subspecies can be distinguished based on slight morphological differences. and genomic Further, eggs of the northern subspecies have filaments (adhesive chorionic fibrils) that eggs of the southern subspecies lack. While the northern subspecies deposits eggs in the sand, the southern subspecies often deposits eggs inside empty mussel shells.
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The cloth is woven in a three-to-one herringbone twill composed of flax fibrils. Its most distinctive characteristic is the faint, brownish image of a front and back view of a naked man with his hands folded across his groin. The two views are aligned along the midplane of the body and point in opposite directions. The front and back views of the head nearly meet at the middle of the cloth.
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APP is critical to neuron growth, survival, and post-injury repair. In Alzheimer's disease, gamma secretase and beta secretase act together in a proteolytic process which causes APP to be divided into smaller fragments. One of these fragments gives rise to fibrils of amyloid beta, which then form clumps that deposit outside neurons in dense formations known as senile plaques. AD is also considered a tauopathy due to abnormal aggregation of the tau protein.
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The main features of the disease are numerous opaque flaky or feathery areas of clouding in the stroma that multiply with age and eventually preclude visibility of the endothelium. Strabismus or primary open angle glaucoma was noted in some of the patients. Thickness of the cornea stays the same, Descemet's membrane and endothelium are relatively unaffected, but the fibrils of collagen that constitute stromal lamellae are reduced in diameter and lamellae themselves are packed significantly more tightly.
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This force partially unfolds the fibronectin ligand, unmasking cryptic fibronectin-binding sites and allowing nearby fibronectin molecules to associate. This fibronectin-fibronectin interaction enables the soluble, cell- associated fibrils to branch and stabilize into an insoluble fibronectin matrix. A transmembrane protein, CD93, has been shown to be essential for fibronectin matrix assembly (fibrillogenesis) in human dermal blood endothelial cells. As a consequence, knockdown of CD93 in these cells resulted in the disruption of the fibronectin fibrillogenesis.
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The stipe is long by thick, roughly spindle-shaped (fusiform), with red-brown fibrils and a sharply defined zone of white color at the stalk apex, especially in more mature specimens. The flesh is white or cream, smelling strongly of meal, with a bitter taste.Gryzyby―Fungi of Poland Spores have a roughly spherical or ellipsoid shape, are hyaline, smooth, non-amyloid, and have dimensions of 5.5—7.0 x 4.5—5.5 µm. Basidia are 4-spored and cystidia are absent.
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The lamina densa is a component of the basement membrane zone between the epidermis and dermis of the skin, and is an electron-dense zone between the lamina lucida and dermis, synthesized by the basal cells of the epidermis, and composed of (1) type IV collagen, (2) anchoring fibrils made of type VII collagen, and (3) dermal microfibrils.James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. Page 5-6. .
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Dermatopontin is a component of the intercellular junction that holds membranes of adjacent cells together (2). The components of the ECM are connected to proteins embedded in the plasma membrane, which in turn are connected to the internal cytoskeleton of the cell. These connections also facilitate cell-to-cell communication (1). Dermatopontin mediates adhesion by cell surface integrin binding and accelerates collagen fibril formation that determines the size and arrangement of collagen fibrils within the extracellular matrix (2).
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Interchromatin granules are structures undergoing constant change, and their components exchange continuously with the nucleoplasm, active transcription sites and other nuclear locations. Research on dynamics of interchromatin granules has provided new insight into the functional organisation of the nucleus and gene expression. Interchromatin granule clusters vary in size anywhere between one and several micrometers in diameter. They are composed of 20–25 nm granules that are connected in a beaded chain fashion appearance by thin fibrils.
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These triple-stranded, ropelike procollagen molecules must be processed by enzymes in the cell. Once processed, these procollagen molecules leave the cell and arrange themselves into long, thin fibrils that cross-link to one another in the spaces around cells. The cross-linkages result in the formation of very strong mature type XI collagen fibers. The COL11A2 gene is located on the short (p) arm of chromosome 6 at position 21.3, from base pair 33,238,446 to base pair 33,268,222.
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Each microfibril is interdigitated with its neighboring microfibrils to a degree that might suggest they are individually unstable, although within collagen fibrils, they are so well ordered as to be crystalline. Three polypeptides coil to form tropocollagen. Many tropocollagens then bind together to form a fibril, and many of these then form a fibre. A distinctive feature of collagen is the regular arrangement of amino acids in each of the three chains of these collagen subunits.
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The mesohyl, formerly known as mesenchyme or as mesoglea, is the gelatinous matrix within a sponge. It fills the space between the external pinacoderm and the internal choanoderm. The mesohyl resembles a type of connective tissue and contains several amoeboid cells such as amebocytes, as well as fibrils and skeletal elements. For a long time, it has been largely accepted that sponges lack true tissue, but it is currently debated as to whether mesohyl and pinacoderm layers are tissues.
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The pore surface of a young specimen The cap of S. lakei is up to in diameter and initially convex, but flattens out somewhat in maturity. The cap is fleshy, dry, yellowish to reddish-brown but fades with age. It is covered with pressed-down hairs or minute tufted scales in the center, with the yellowish flesh visible between the scales. Heavy rain can wash the fibrils off the cap surface, leaving a sticky, glutinous layer behind.
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J. Struct. Biol. 169(2):183-191. Energy storing tendons have been shown to utilise significant amounts of sliding between fascicles to enable the high strain characteristics they require, whilst positional tendons rely more heavily on sliding between collagen fibres and fibrils. However, recent data suggests that energy storing tendons may also contain fascicles which are twisted, or helical, in nature - an arrangement that would be highly beneficial for providing the spring-like behaviour required in these tendons.
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When Sup35 undergoes a conformational change to the [PSI+] prion state, it forms amyloid fibrils and is sequestered, leading to more frequent stop codon read-through and the development of novel phenotypes. With over 20 prion-like domains identified in yeast, this gives rise to the opportunity for a significant amount of variation from a single proteome. It has been posited that this increased variation gives a selectable advantage to a population of genetically homogeneous yeast.
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Collagen is a major component in skin tissue and in tendons. While scientists originally suspected that the problem lay in the production of the type I collagen molecule, it is now known that type V collagen is the molecule which is incorrectly produced. Although scientists do not know exactly how, many suspect that type V collagen assists in packaging type I collagen. Collagen fibrils are often abnormally sized and have unusually large amounts of space between them.
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Unlike deodorant, which simply reduces axillary odor without affecting body functions, antiperspirant reduces both eccrine and apocrine sweating. Antiperspirants, which are classified as drugs, cause proteins to precipitate and mechanically block eccrine (and sometimes apocrine) sweat ducts. The metal salts found in antiperspirants alters the keratin fibrils in the ducts; the ducts then close and form a "horny plug". The main active ingredients in modern antiperspirants are aluminum chloride, aluminum chlorohydrate, aluminum zirconium chlorohydrate, and buffered aluminum sulfate.
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Clitocybe albirhiza is a brown colored mushroom with similar stature, but it may be distinguished by the white rhizomorphs at the base of its stem, as well as fibrils on the cap that are arranged in zones. Melanoleuca angelesiana is another species found in the same environment; mature specimens of both species resemble each other. They are easier to differentiate when young, however, as C. glacialis has a silvery-grey bloom that is lacking in M. angelesiana.
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These disorders are known as synucleinopathies. In vitro models of synucleinopathies revealed that aggregation of alpha-synuclein may lead to various cellular disorders including microtubule impairment, synaptic and mitochondrial dysfunctions, oxidative stress as well as dysregulation of Calcium signaling, proteasomal and lysosomal pathway. Alpha-synuclein is the primary structural component of Lewy body fibrils. Occasionally, Lewy bodies contain tau protein; however, alpha-synuclein and tau constitute two distinctive subsets of filaments in the same inclusion bodies.
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The jay's nest is typically built above the ground next to a tree trunk. The base of the azure-hooded jay's first studied nest was coarsely made out of twigs that were long. That nest was about wide inside and wide overall depending on the length of the exterior twigs. The nest is deep and has an interior constructed with woven thin fibrils and twigs, and no feathers or other softening devices are used in the nest's construction.
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Laccaria amethystinaThe cap is 1-6 cm in diameter, and is initially convex, later flattening, and often with a central depression (navel). When moist it is a deep purplish lilac, which fades upon drying out. It is sometimes slightly scurfy at the center, and has pale striations at the margin. Electronmicroscopic image of spores of Laccaria amethystina The stem is the same colour as the cap, and has whitish fibrils at the base, which become mealy at the top.
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The mechanical differences between the single and double twisted bouligand structure has been observed. It was shown that the double bouligand structure is stiffer and tougher than the more common single bouligand structure. The increase in stiffness is also accompanied by a reduction of flexibility. The increased strength is attributed in part to an addition to the structure of "inter-bundle fibrils" that run up and down the stack of layers, perpendicular to the twisted fiber planes.
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This also influences how much a single scale will bend when a predator attacks. In the species Arapaima gigas, each scale has two distinct structural regions which results in a scale that is resistant to puncture and bending. The outer layer is about 0.5 mm thick and is highly mineralized, which makes it hard, promoting predator tooth fracture. The inner layer is about 1 mm thick and is made of mineralized collagen fibrils arranged in a Bouligand structure.
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However, the tissue can scatter the generated light, and a part of the SHG in forward can be retro-reflected in the backward direction. Then, the forward-over-backward ratio F/B can be calculated, and is a metric of the global size and arrangement of the SHG converters (usually collagen fibrils). It can also be shown that the higher the out-of-plane angle of the scaterrer, the higher its F/B ratio (see fig. 2.14 of ).
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The precise cause of amyloid purpura is unknown, but several mechanisms are thought to contribute. One may be a decrease in the level of circulating factor X, a clotting factor necessary for coagulation. The proposed mechanism for this decrease in factor X is that circulating amyloid fibrils bind and inactivate factor X. Another contributing factor may be enhanced fibrinolysis, the breakdown of clots. Subendothelial deposits of amyloid may weaken blood vessels and lead to the extravasation of blood.
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The peristome is made of radially arranged fibrils that clump together at the apex in groups of unequal length to form an opening that appears jagged or torn. The circular area bordering the peristome is a paler color. Spores are thought to be dispersed by the wind sucking them out when it blows over the hole, or when falling raindrops hit the flexible endoperidium, creating a puff of air that forces the spores through the ostiole.
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The cap is up to , initially almost spherical, then expanded convex and finally flattened. The cap has a broad, blunt and low umbo, which frequently lies in a depression since the margin which is initially rolled inward, then straight, often becomes turned upward. The cap cuticle is dry and difficult to peel. The cap surface is dry or humid, non- shiny in the center, but shiny towards the margin which is covered with fibrils when young.
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The fourth type is a chromoplast which only contains crystals. An electron microscope reveals even more, allowing for the identification of substructures such as globules, crystals, membranes, fibrils and tubules. The substructures found in chromoplasts are not found in the mature plastid that it divided from. The presence, frequency and identification of substructures using an electron microscope has led to further classification, dividing chromoplasts into five main categories: Globular chromoplasts, crystalline chromoplasts, fibrillar chromoplasts, tubular chromoplasts and membranous chromoplasts.
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The 10 to 15 mm- diameter stems have no ring, are bright yellow and the lower part is covered in coral-red fibrils and has a constant elliptical to fusiform diameter throughout its length of 4 to 8 cm tall. The cream-colored stem flesh turns blue when cut. X. chrysenteron has large, yellow, angular pores, and produces an olive brown spore print. Fruit bodies of Xerocomellus chrysenteron are also prone to infestation by the bolete eater (Hypomyces chrysospermus).
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Membrane proteins and amyloid fibrils, the latter related to Alzheimer's disease and Parkinson's disease, are two examples of applications where solid-state NMR spectroscopy complements solution-state NMR spectroscopy and beam diffraction methods (e.g. X-ray crystallography, electron microscopy). Solid-state NMR structure elucidation of proteins has traditionally been based on secondary chemical shifts and spatial contacts between heteronuclei. Currently, paramagnetic contact shifts and specific proton-proton distances are also used for higher resolution and longer-range distance restraints.
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The two families, Deinopoidea and Araneoidea, have similar behavioral sequences and spinning apparatuses to produce architecturally similar webs. The Araneidae weave true viscid silk with an aqueous glue property, and the Deinopoidea use dry fibrils and sticky silk. The Deinopoidea (including the Uloboridae), have a cribellum – a flat, complex spinning plate from which the cribellate silk is released. They also have a calamistrum – an apparatus of bristles used to comb the cribellate silk from the cribellum.
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The disease is inherited by autosomal dominant transmission with complete penetrance but variable expression. This means that children of an affected parent that carries the gene have a 50% chance of developing the disorder, although the extent to which they are affected is variable. Bart syndrome is caused by ultrastructural abnormalities in the anchoring fibrils. Genetic linkage of the inheritance of the disease points to the region of chromosome 3 near the collagen, type VII, alpha 1 gene (COL7A1).
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The COL1A1 gene produces the pro-alpha1(I) chain. This chain combines with another pro-alpha1(I) chain and also with a pro-alpha2(I) chain (produced by the COL1A2 gene) to make a molecule of type I procollagen. These triple-stranded, rope-like procollagen molecules must be processed by enzymes outside the cell. Once these molecules are processed, they arrange themselves into long, thin fibrils that cross-link to one another in the spaces around cells.
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Amyloid beta monomers are soluble and contain short regions of beta sheet and polyproline II helix secondary structures in solution, though they are largely alpha helical in membranes; however, at sufficiently high concentration, they undergo a dramatic conformational change to form a beta sheet-rich tertiary structure that aggregates to form amyloid fibrils. These fibrils deposit outside neurons in dense formations known as senile plaques or neuritic plaques, in less dense aggregates as diffuse plaques, and sometimes in the walls of small blood vessels in the brain in a process called cerebral amyloid angiopathy. AD is also considered a tauopathy due to abnormal aggregation of the tau protein, a microtubule-associated protein expressed in neurons that normally acts to stabilize microtubules in the cell cytoskeleton. Like most microtubule-associated proteins, tau is normally regulated by phosphorylation; however, in Alzheimer's disease, hyperphosphorylated tau accumulates as paired helical filaments that in turn aggregate into masses inside nerve cell bodies known as neurofibrillary tangles and as dystrophic neurites associated with amyloid plaques.
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The Bowman's membrane (Bowman's layer, anterior limiting lamina, anterior elastic lamina) is a smooth, acellular, nonregenerating layer, located between the superficial epithelium and the stroma in the cornea of the eye. It is composed of strong, randomly oriented collagen fibrils in which the smooth anterior surface faces the epithelial basement membrane and the posterior surface merges with the collagen lamellae of the corneal stroma proper.Kenyon, KR. Morphology and pathologic responses of the cornea to disease. In: Smolin G, Thoft RA, eds.
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Older specimens generally have dry and velvety cap surfaces. The texture of the cap surface is rough, at first because of flattened-down (appressed) fibrils, and later with bent-back (recurved) scales or sometimes with cracked rough patches that resemble dried cracked mud. Young specimens may have a small flap of thin tissue attached to the margin or edge of the cap, remnants of a reduced partial veil. The surface is covered with tufts of soft woolly hairs, and has persistent papillae.
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Suillus americanus contains a polysaccharide known as a beta glucan that laboratory tests suggest may have anti-inflammatory activity. Known specifically as a (1→3)-, (1→4)-β-D-glucan, its natural function is as a component of the fungal cell wall, where it forms microcrystalline fibrils in the wall that give it rigidity and strength. The anti-inflammatory activity results from the polysaccharide's ability to inhibit the production of nitric oxide in activated macrophages, a cell of the immune system.
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The body and oral kinetids make up the infraciliature, an organization unique to the ciliates and important in their classification, and include various fibrils and microtubules involved in coordinating the cilia. The infraciliature is one of the main components of the cell cortex. Others are the alveoli, small vesicles under the cell membrane that are packed against it to form a pellicle maintaining the cell's shape, which varies from flexible and contractile to rigid. Numerous mitochondria and extrusomes are also generally present.
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Positive α-Synuclein staining of a Lewy body from a patient who had Parkinson's disease. Classically considered an unstructured soluble protein, unmutated α-synuclein forms a stably folded tetramer that resists aggregation. This observation, though reproduced and extended by several labs, is still a matter of debate in the field due to conflicting reports. Nevertheless, alpha-synuclein aggregates to form insoluble fibrils in pathological conditions characterized by Lewy bodies, such as Parkinson's disease, dementia with Lewy bodies and multiple system atrophy.
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2009, p. 202. Though G. maritimus and G. arenophilus show similarities in their biogeography and ecology, the typically slightly smaller G. arenophilus differs from G. maritimus morphologically. While G. maritimus has a cap covered in fibrils with small scales, G. arenophilus can sometimes be completely smooth, and spore ornamentation differs, with G. maritimus typically displaying larger warts. Like G. maritimus, G. fulgens has been recorded growing on sand-dune heathland; further, the spores are similar in appearance to those of G. maritimus.
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This also creates voids which are known as cavitation and can be seen at a macroscopic level as a stress-whitened region as shown in Figure 1. These voids surround the aligned polymer regions. The stress in the aligned fibrils will carry majority of the stress as the covalent bonds are significantly stronger than the van der Waals bonds. The plastic like behavior of polymers leads to a greater assumed plastic deformation zone in front of the crack tip altering the failure process.
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All parts of the mushroom stain dark blue if bruised or injured. The shape of the cap of B. rubroflammeus is convex to broadly convex, and reaches a diameter of . The margin of the cap extends slightly beyond the tubes. The cap surface is dry and initially appears appressed-fibrillose (with fibrils pressed down flat against the surface) or has a matted grayish tomentum, but later the hairs slough off and the matted tomentum is present only along the cap margin.
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When examined by phase-contrast and transmission electron microscopy cells were observed to be nonmotile, rod shaped, with sizes ranging from 0.5-0.7 µm in width and 2.5-5.0 µm in length. F. ginsengisoli carried peritrichous fibrils, which were very fine and hairy and projected out from the cell wall. Spore formation was not observed. When investigated in one-half R2A media, cultures of F. ginsengisoli were observed to be strictly aerobic with no evidence of growth under anaerobic conditions.
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Pulp chemistry has a significant influence on nanocellulose microstructure. Carboxymethylation increases the numbers of charged groups on the fibril surfaces, making the fibrils easier to liberate and results in smaller and more uniform fibril widths (5–15 nm) compared to enzymatically pre-treated nanocellulose, where the fibril widths were 10–30 nm. The degree of crystallinity and crystal structure of nanocellulose. Nanocellulose exhibits cellulose crystal I organization and the degree of crystallinity is unchanged by the preparation of the nanocellulose.
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A sample of fibrils will have a high- level of turbidity when compared to that of a sample of triple-helices. As fibrillogenesis is taking place, there is a change in the light-scattering properties of the sample over time, which can be measured with a spectrophotometer. The wavelength typically used to measure fibrillogenesis with a spectrophotometer ranges from 310nm to 313nm. Turbidity tests done on type I collagen triple-helices will display a sigmoidal curve when plotted on a graph.
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In order to mimic a mature bone matrix, self-assembled fibrils can be used to align a given mineral matrix. This is accomplished using a self- assembling molecule with a hydrophobic alkyl tail and a hydrophilic oligopeptide head. These molecules form micellar structures in situ, and disulfide bridges at low pH, leading to the formation and crystallization of 200 kDa polymeric nanofibrils. The mineral matrix ultimately interacts with the synthetic fibril via a phosphoserine residue which results in mineral nucleation and growth.
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Protein structural robustness results from few single mutations being sufficiently disruptive to compromise function. Proteins have also evolved to avoid aggregation as partially folded proteins can combine to form large, repeating, insoluble protein fibrils and masses. There is evidence that proteins show negative design features to reduce the exposure of aggregation- prone beta-sheet motifs in their structures. Additionally, there is some evidence that the genetic code itself may be optimised such that most point mutations lead to similar amino acids (conservative).
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The vitreous humour is in contact with the vitreous membrane overlying the retina. Collagen fibrils attach the vitreous at the optic nerve disc and the ora serrata (where the retina ends anteriorly), at the Wieger-band, the dorsal side of the lens. The vitreous also firmly attaches to the lens capsule, retinal vessels, and the macula, the area of the retina which provides finer detail and central vision. Aquaporin 4 in Müller cell in rats transports water to the vitreous body.
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Later amyloid fiber structures also seem to have some cytotoxic effect on cell cultures. Studies have shown that fibrils are the end product and not necessarily the most toxic form of amyloid proteins/peptides in general. A non-fibril forming peptide (1–19 residues of human amylin) is toxic like the full-length peptide but the respective segment of rat amylin is not. It was also demonstrated by solid-state NMR spectroscopy that the fragment 20-29 of the human-amylin fragments membranes.
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Some cuts of meat also show structural coloration due to the exposure of the periodic arrangement of the muscular fibres. Many of these photonic mechanisms correspond to elaborate structures visible by electron microscopy. In the few plants that exploit structural coloration, brilliant colours are produced by structures within cells. The most brilliant blue coloration known in any living tissue is found in the marble berries of Pollia condensata, where a spiral structure of cellulose fibrils produces Bragg's law scattering of light.
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Collagen alpha-1(XII) chain is a protein that in humans is encoded by the COL12A1 gene. This gene encodes the alpha chain of type XII collagen, a member of the FACIT (fibril-associated collagens with interrupted triple helices) collagen family. Type XII collagen is a homotrimer found in association with type I collagen, an association that is thought to modify the interactions between collagen I fibrils and the surrounding matrix. Alternatively spliced transcript variants encoding different isoforms have been identified.
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The main effect is thought to be on the formation of collagen. Symptoms are similar to those of scurvy and copper deficiency, which share the common feature of inhibiting proper formation of collagen fibrils. Seeds of the sweet pea contain beta-aminopropionitrile that prevents the cross-linking of collagen by inhibiting lysyl oxidase and thus the formation of allysine, leading to loose skin. Recent experiments have attempted to develop this chemical as a treatment to avoid disfiguring skin contractions after skin grafting.
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This protein has more than one known point-mutation, one being A53T where amino acid residue 53 is mutated from its native alanine to a threonine. Wild-type alpha-synuclein fibrils are known to be the primary component of Lewy bodies, which are found in the brain of Parkinson's disease patients. The A53T mutation has been shown have faster kinetics of fibrilization than the wild-type protein. A53T alpha-synuclein has also been linked to early on-set familial Parkinson's disease.
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When examining the tissues of periapical granuloma for disease, hyperaemia, oedema and chronic inflammation is observed in the periodontal ligament. The vascular amplification and inflammation is adjacent to the bone, and bone absorption occurs next to a large growth in fibroblast and endothelial cells which is composed of the minute fibers (fibrils) with small vascular conduits (channels of passage for fluids). The lesion is predominantly composed of plasma cells that are mixed with macrophages and lymphocytes with endothelial cells and fibroblasts.
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The black fruit body (technically called an apothecium) is cup-shaped, covered with either scales or small silk-like surface fibrils (fibrillose), and up to in diameter. The upper margin of the fruit body cup may be rounded with scalloped or lobed edges (crenate). The short, slender stipe (typically tall) is black on the upper part, but gray at the base; it is cylindrical and tapering (terete) with rounded ribs at its base. The odor and taste are not distinctive.
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Night monkeys have large brown eyes; the size improves their nocturnal vision increasing their ability to be active at night. They are sometimes said to lack a tapetum lucidum, the reflective layer behind the retina possessed by many nocturnal animals. Other sources say they have a tapetum lucidum composed of collagen fibrils. At any rate, night monkeys lack the tapetum lucidum composed of riboflavin crystals possessed by lemurs and other strepsirrhines, which is an indication that their nocturnalitiy is a secondary adaption evolved from ancestral diurnal primates.
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Other functions of dermatopontin include stabilizing collagen fibrils against low temperature dissociation, inhibiting cell proliferation, enhancing TGFB1 activity, and possibly serving as a communication link between the dermal fibroblast cell surface and its extracellular environment (3). Dermatopontin itself is a noncollagenous ECM protein but it facilitates collagen binding (2). Dermatopontin is an extracellular matrix protein with possible functions in cell-matrix interactions and matrix assembly. The extracellular matrix (ECM) is known as a non-cellular component that is found in all organs and tissues.
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The intervertebral disc functions to separate the vertebrae from each other and provides the surface for the shock-absorbing gel of the nucleus pulposus. The nucleus pulposus of the disc functions to distribute hydraulic pressure in all directions within each intervertebral disc under compressive loads. The nucleus pulposus consists of large vacuolated notochord cells, small chondrocyte-like cells, collagen fibrils, and aggrecan, a proteoglycan that aggregates by binding to hyaluronan. Attached to each aggrecan molecule are glycosaminoglycan (GAG) chains of chondroitin sulfate and keratan sulfate.
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Most skins used for parchment are between 1 – 3 mm in thickness before processing. Animal skin used for parchment all has the same basic structure, with slight variations due to the species, age and diet of the specific animal. Skin is composed of innumerable fibrils made up of the protein collagen, which are held in bundles that interweave in a three dimensional manner through the skin. The fibrous material is composed of many long chain molecules of collagen, which can react with certain environmental factors.
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People with recalcitrant recurrent corneal erosions often show increased levels of matrix metalloproteinase (MMP) enzymes. These enzymes dissolve the basement membrane and fibrils of the hemidesmosomes, which can lead to the separation of the epithelial layer. Treatment with oral tetracycline antibiotics (such as doxycycline or oxytetracycline) together with a topical corticosteroid (such as prednisolone), reduce MMP activity and may rapidly resolve and prevent further episodes in cases unresponsive to conventional therapies. Some have now proposed this as the first line therapy after lubricants have failed.
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They are crowded closely together, and have edges that are usually wavy and scalloped. The stem is long and thick, solid, and thickened at the base in an emarginate bulb that is roughly club-shaped to ventricose. The stem surface is covered with silky fibrils, and is whitish-violet when very young, later losing the violet tones. The surface becomes fibrillosely floccose or whitish at the base and violet at the top, later becoming covered with the violet to whitish silky cortina (a cobwebby partial veil).
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Procollagen C-endopeptidase enhancer 1 is an enzyme that in humans is encoded by the PCOLCE gene. Fibrillar collagen types I-III are synthesized as precursor molecules known as procollagens. These precursors contain amino- and carboxyl-terminal peptide extensions known as N- and C-propeptides, respectively, which are cleaved, upon secretion of procollagen from the cell, to yield the mature triple helical, highly structured fibrils. This gene encodes a glycoprotein which binds and drives the enzymatic cleavage of type I procollagen and heightens activity.
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In particular, it specifically binds to Aβ40 and Aβ42 fibrils and insoluble plaques containing the aforementioned Aß peptides. PiB does not bind with great affinity to soluble or nonfibrillar Aß plaques until plaques have reached a crucial magnitude, which has yet to be determined. Furthermore, this radiotracer does not bind to neurofibrillary tangles (NFTs) in the neuronal regions of the brain during postmortem autopsies. A typical injected dose ranges from 250-450 MBq and the imaging time normally varies between 40 and 90 minutes.
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The stipe is long, 0.5–1 mm thick, and, above the level of the flat circular disc at the base, is equal in width throughout. The stipe is covered with fine white scattered fibrils, or is delicately pruinose (as if covered with a fine white powder), but it later becomes smooth. Its color is bluish-gray when fresh but soon it fades to gray. The basal disc is grooved (from gill impressions) and pruinose or covered with fine minute hairs, but soon becomes smooth.
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The stipe is (3) 5 – 12 cm long, (0.4) 1.0 — 1.5 cm (4) thick, and has a more or less equal structure. It is covered with appressed fibrils, soon disappearing. It is smooth, dry, dusted with rusty orange spores and has a cottony, scanty, yellowish, partially fibrillose veil that leaves an evanescent zone of hairs near the apex of the stipe. It is colored more or less like the cap; it is flesh whitish, tinged greenish or bluish green, becoming yellowish or pinkish brown when dry.
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Figure 1 - Crack-tip Craze ZoneAs metals yield through dislocation motions in the slip planes, polymer yield through either shear yielding or crazing. In shear yielding, molecules move with respect to one another as a critical shear stress is being applied to the system resembling a plastic flow in metals. Yielding through crazing is found in glassy polymers where a tensile load is applied to a highly localized region. High concentration of stress will lead to the formation of fibrils in which molecular chains form aligned sections.
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The dermoepidermal junction or dermal-epidermal junction (DEJ) is the area of tissue that joins the epidermal and the dermal layers of the skin. The basal cells in the stratum basale of the epidermis connect to the basement membrane by the anchoring filaments of hemidesmosomes; the cells of the papillary layer of the dermis are attached to the basement membrane by anchoring fibrils, which consist of type VII collagen. Stevens–Johnson syndrome and toxic epidermal necrolysis are diseases where there is a breakdown of the dermoepidermal junction.
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Krukenberg's spindle is the name given to the pattern formed on the inner surface of the cornea by pigmented iris cells that are shed during the mechanical rubbing of posterior pigment layer of the iris with the zonular fibrils that are deposited as a result of the currents of the aqueous humor. The sign was described in 1899 by Friedrich Ernst Krukenberg (1871-1946), who was a German pathologist specialising in ophthalmology.Krukenberg F. (1899) Beiderseitige angeborene Melanose der Hornhaut. Klin Mbl Augenheilkd 37:254-258.
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There is no concrete evidence or agreement on the exact mechanisms of fibrillogenesis, however, multiple hypotheses based on primary research have put forth various mechanisms to consider. Collagen fibrillogenesis occurs in the plasma membrane during embryonic development. Collagen within the body has a denaturation temperature between 32-40 degrees Celsius, the physiological temperature also falls within this range and thereby poses a significant problem. It is not known how collagen survives within the tissues in order to yield itself to the formation of collagen fibrils.
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Based on research using mice and studies of Ehlers-Danlos syndromes (EDS), which is characterized by hypermobility of the joints, and high levels of skin laxity, researcher found that tenascin X expression levels correlated with the number of present collagen fibrils. In humans, tenascin X is associated with EDS. Through their research, researcher confounded the original hypothesis that tenascin X interfered with collagen fibrillogenesis and suggest that it acts rather as a regulator of collagen fibrillogenesis. Data suggest tenascin is a regulator of collagen fibril spacing.
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Micrograph demonstrating amyloid deposition (red-orange) with Congo red staining in cardiac amyloidosis. In histology and microscopy, Congo red is used for staining in amyloidosis, and for the cell walls of plants and fungi, and for the outer membrane of Gram- negative bacteria. Apple-green birefringence of Congo red stained preparations under polarized light is indicative of the presence of amyloid fibrils. Additionally, Congo red is used for the diagnostics of the Shigella flexneri serotype 2a, where the dye binds the bacterium's unique lipopolysaccharide structure.
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The correct three-dimensional structure is essential to function, although some parts of functional proteins may remain unfolded, so that protein dynamics is important. Failure to fold into native structure generally produces inactive proteins, but in some instances misfolded proteins have modified or toxic functionality. Several neurodegenerative and other diseases are believed to result from the accumulation of amyloid fibrils formed by misfolded proteins. Many allergies are caused by incorrect folding of some proteins, because the immune system does not produce antibodies for certain protein structures.
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Moreover, the Gardel lab has shown that invasive motility of MDCK cells in acini requires Dia1, which regulates cell adhesions to individual collagen fibrils. Meanwhile, other groups have demonstrated the requirement for cell-ECM adhesion proteins or their regulators in MDCK branching morphogenesis. Using a modified protocol for MDCK cell culture and branching morphogenesis, Gierke and Wittman established the requirement for microtubule dynamics in regulating the early steps in branching. They observed deficient cell adhesive coupling to the collagen matrix when microtubules were deregulated.
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The reasons why amyloid cause diseases are unclear. In some cases, the deposits physically disrupt tissue architecture, suggesting disruption of function by some bulk process. An emerging consensus implicates prefibrillar intermediates, rather than mature amyloid fibers, in causing cell death, particularly in neurodegenerative diseases. The fibrils are, however, far from innocuous, as they keep the protein homeostasis network engaged, release oligomers, cause the formation of toxic oligomers via secondary nucleation, grow indefinitely spreading from district to district and, in some cases, may be toxic themselves.
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In Hirschsprung disease, calretinin immunohistochemistry offers additional diagnostic value in specimens with inadequate amount of submucosa and rarely seen ganglion cells. The presence of ganglion cells consistently correlated with calretinin-positive thin nerve fibrils in the lamina propria, muscularis mucosae and superficial submucosa. These calretinin-positive thin neurofibrils are absent in the aganglionic segments of bowel and in the areas without ganglion cells from the junction of normal with diseased rectum. Calretinin is strongly expressed in the submucosal and subserosal nerve trunks in the ganglionic segment.
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Taking precedent from this, the team developed a composite hydrogel architecture with local anisotropic swelling behavior that mimics the structure of a typical cell wall. Cellulose fibrils combine during the printing process into microfibrils with a high aspect ratio (~100) and an elastic modulus on the scale of 100 GPa. These microfibrils are embedded into a soft acrylamide matrix for structure. The viscoelastic ink used to print this hydrogel composite is an aqueous solution of N,N-dimethylacrylamide, nanoclay, glucose oxidase, glucose, and nanofibrillated cellulose.
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Because spin labels are exquisitely sensitive to motion, this has profound effects on its EPR spectrum. The assembly of multi-subunit membrane protein complexes has also been studied using spin labeling. The binding of the PsaC subunit to the PsaA and PsaB subunits of the photosynthetic reaction center, Photosystem I, has been analyzed in great detail using this technique. Dr. Ralf Langen's group showed that SDSL with EPR (University of Southern California, Los Angeles) can be used to understand the structure of amyloid fibrils and the structure of membrane bound Parkinson's disease protein alpha-synuclein.
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LECT2 as a hepatokine, a substance made and released into the circulation by liver hepatocyte cells that acts as a hormone or signaling agent to regulate the function of other cells. While the pathogenesis of LECT2 amyloidosis is unclear, the intact LECT2 protein may have a tendency to fold abnormally thereby forming non-soluble fibrils that are deposited in tissues. It has been suggested that individuals with the disease have an increase in LECT2 production and/or a decrease in LECT2 catabolism (i.e. breakdown) which may increase its tendency to deposit in tissues.
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Class I monolayer contains the same core structure as amyloid fibrils, and is positive to Congo red and thioflavin T. The monolayer formed by class I hydrophobins has a highly ordered structure, and can only be dissociated by concentrated trifluoroacetate or formic acid. Monolayer assembly involves large structural rearrangements with respect to the monomer. Fungi make complex aerial structures and spores even in aqueous environments. Hydrophobins have been identified in lichens as well as non-lichenized ascomycetes and basidiomycetes; whether they exist in other groups is not known.
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Inborn deficiency of factor X is very rare (1:1,000,000), and may present with epistaxis (nosebleeds), hemarthrosis (bleeding into joints) and gastrointestinal blood loss. Apart from congenital deficiency, low factor X levels may occur occasionally in a number of disease states. For example, factor X deficiency may be seen in amyloidosis, where factor X is adsorbed to the amyloid fibrils in the vasculature. Deficiency of vitamin K or antagonism by warfarin (or similar medication) leads to the production of an inactive factor X. In warfarin therapy, this is desirable to prevent thrombosis.
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This model was supported by further studies showing higher resolution in the late 20th century. The packing structure of collagen has not been defined to the same degree outside of the fibrillar collagen types, although it has been long known to be hexagonal. As with its monomeric structure, several conflicting models alleged that either the packing arrangement of collagen molecules is 'sheet-like' or microfibrillar. The microfibrillar structure of collagen fibrils in tendon, cornea and cartilage was imaged directly by electron microscopy in the late 20th century and early 21st century.
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Therefore, sufficient transparency for camouflage is more easily achieved in deeper waters. Glass frogs like Hyalinobatrachium uranoscopum use partial transparency for camouflage in the dim light of the rainforest. Some tissues such as muscles can be made transparent, provided either they are very thin or organised as regular layers or fibrils that are small compared to the wavelength of visible light. A familiar example is the transparency of the lens of the vertebrate eye, which is made of the protein crystallin, and the vertebrate cornea which is made of the protein collagen.
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The β-sheet (also β-pleated sheet) is a common motif of regular secondary structure in proteins. Beta sheets consist of beta strands (also β-strand) connected laterally by at least two or three backbone hydrogen bonds, forming a generally twisted, pleated sheet. A β-strand is a stretch of polypeptide chain typically 3 to 10 amino acids long with backbone in an extended conformation. The supramolecular association of β-sheets has been implicated in formation of the protein aggregates and fibrils observed in many human diseases, notably the amyloidoses such as Alzheimer's disease.
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The structure of these fibers, like the majority of collagen fibers, forms a triple helix structure. Proteoglycans resist the compression generally put upon cartilage and generate the swelling pressure responsible for stress shielding the matrix from compression loading. They attach themselves to up to 100 Chondroitin sulfate molecules and up to 50 keratan sulfate glycoaminoglycan chains. These chains together are attached to a hyaluronic acid backbone which, in conjunction with the collagen fibrils, create an interstitial intrafibrillar space in which water is held in by the negative charge of the proteoglycans.
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An odontoblast process (also called Tomes's fibers or Tomes fibers, or by a dated term Tomes's fibrils) is an extension of a cell called an odontoblast, which forms dentin in a tooth. The odontoblast process is located in dentinal tubules. It forms during dentinogenesis and results from a part of the odontoblast staying in its location as the main body of the odontoblast moves toward the center of the tooth's pulp. The odontoblast process causes the secretion of hydroxyapatite crystals and mineralization of the matrix secreted by the odontoblasts.
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Genomic duplication and triplication of the gene appear to be a rare cause of Parkinson's disease in other lineages, although more common than point mutations. Hence certain mutations of alpha-synuclein may cause it to form amyloid-like fibrils that contribute to Parkinson's disease. Over-expression of human wild-type or A53T-mutant alpha-synuclein in primates drives deposition of alpha-synuclein in the ventral midbrain, degeneration of the dopaminergic system and impaired motor performance. Certain sections of the alpha-synuclein protein may play a role in the tauopathies.
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Measuring the size of a protein molecule is useful as an overall quality indicator, since misfolding, unfolding, oligomerization, aggregation or degradation can all affect size. The literature specifically demonstrates the use of MDS in sizing protein-nanobody complexes, monitoring the formation of α-synuclein amyloid fibrils. and in observing protein assembly into oligomers MDS can also be used to size membrane proteins, as the use of a protein specific labelling and detection system allows other species present in the solution (such as free lipid micelles or detergents) to be ignored.
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Aebi is recognized as a pioneer in integrative structural biology as well as mechano- and nanobiology. His work focused on the elucidation of the structure, function and assembly of the cyto- and nucleoskeleton and the nuclear pore complex (NPC), as well as the amyloid fibrils that are a hallmark of Alzheimer's disease. He studied the architecture of diverse supramolecular assemblies using a combination of light, electron and atomic force microscopy, X-ray crystallography, and protein engineering. Among others, Aebi determined the 3-dimensional structure of the NPC by cryo-electron tomography.
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Furthermore, another study performed at the University of California determined that the modulus (the stress/strain) of fibrin adhesives was on average 53.56 kPA. To seal together tissues the human body uses collagen and elastin to obtain superior shear strength. Type I collagen which includes collagen strands bundled into strong fibrils has a unique tri-helical structure which increases the proteins structural integrity. In fact, a study performed by the Department of Medicine in University College London experimentally determined that pure type I collagen has a modulus of 5 GPa to 11.5 GPa.
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Proteins can bind to other proteins as well as to small-molecule substrates. When proteins bind specifically to other copies of the same molecule, they can oligomerize to form fibrils; this process occurs often in structural proteins that consist of globular monomers that self-associate to form rigid fibers. Protein–protein interactions also regulate enzymatic activity, control progression through the cell cycle, and allow the assembly of large protein complexes that carry out many closely related reactions with a common biological function. Proteins can also bind to, or even be integrated into, cell membranes.
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Corynebacterium minutissimum is the bacteria that causes this infection, often club shaped rods when observed under a microscope following a staining procedure, which is a result of snapping division which makes them look like a picket fence. This bacteria is gram positive, which means it has a very thick cell wall that cannot be easily penetrated. Electron microscopy confirms the bacterial nature of erythrasma, it shows decreased electron density in keratinized cells at the sites of proliferation. This means that the bacteria causes erythrasma by breaking down keratin Fibrils in the skin.
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Space fill model of cellulose, prior to winding into fibrils The primary cell wall derives its notable tensile strength from cellulose molecules, or long-chains of glucose residues stabilized by hydrogen bonding. Cellulose chains are observed to align in overlapping parallel arrays, with the similar polarity forming a cellulose microfibril. In plants, these cellulose microfibrils arrange themselves into layers, formally known as lamellae, and are stabilized in the cell wall by surface, long cross-linking glycan molecules. Glycan molecules increase the complexity of the potential networks plant-based cellulose can configure itself into.
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The structure elements are combined in structural systems. The majority of everyday load-bearing structures are section-active structures like frames, which are primarily composed of one-dimensional (bending) structures. Other types are Vector-active structures such as trusses, surface-active structures such as shells and folded plates, form-active structures such as cable or membrane structures, and hybrid structures. Load-bearing biological structures such as bones, teeth, shells, and tendons derive their strength from a multilevel hierarchy of structures employing biominerals and proteins, at the bottom of which are collagen fibrils.
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The cap surface in young specimens is smooth but soon forms appressed scale-like spots, which may transform into scales in age. Initially, the cap has white margins and a brownish-violet center with scale-like spots; the center later becomes orange-brownish or ochraceous brown. According to Canadian mycologist James Ginns, who described North American Albatrellus species in 1997, some North American specimens may be covered with blackish-gray to purple-gray fibrils, but this characteristic is not seen in European collections. The cap discolors yellowish when bruised.
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The stem color is white with a slight blue to lilac tinge at the top that later disappears, slightly yellowish-cream below, changing to completely pale yellowish-ochre when old. The cortina (a cobweb-like partial veil made of silky fibrils) is and white, but later becomes cinnamon when the mushroom drops its spores. The flesh is firm, finely and compactly fleshy, white in the cap, later with a faint yellow tinge, undulatingly fibrillose in the stem and with a faint yellowish tinge. The odor is "pleasant", and the taste is also pleasant and mild.
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At first it is almost the same color as the gills, vivid yellow or yellow later with a more or less olive tone, and in some places turning brown. It is covered with fibrils from the veil, which forms one or two incomplete, oblique, and usually fugacious zones. The flesh is thin, in the cap pale yellow or yellow with olive tones, a little darker in the stem, yellow to olive, with a faint slightly radishy smell and mild taste. The spore deposit is a light rusty saffron color.
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Nowick received his bachelor's degree from Columbia University in 1985 and his Ph.D. from the Massachusetts Institute of Technology in 1990. He joined the faculty at University of California, Irvine in 1991. Nowick's research group studies the synthesis and design of peptidomimetic molecules, or those that resemble peptides, with particular interest in molecules that replicate features of beta sheets such as their characteristic hydrogen bonding patterns. Beta sheet interactions are known to be involved in the formation of amyloid fibrils found in the brains of patients with Alzheimer's disease and in other protein misfolding diseases.
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Lysyl oxidase is an extracellular copper-dependent enzyme that catalyzes formation of aldehydes from lysine residues in collagen and elastin precursors. These aldehydes are highly reactive, and undergo spontaneous chemical reactions with other lysyl oxidase-derived aldehyde residues, or with unmodified lysine residues. This results in cross-linking collagen and elastin, which is essential for stabilization of collagen fibrils and for the integrity and elasticity of mature elastin. Complex cross-links are formed in collagen (pyridinolines derived from three lysine residues) and in elastin (desmosines derived from four lysine residues) that differ in structure.
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Cyptotrama asprata (alternatively spelled aspratum), commonly known as the golden-scruffy collybia, is a saprobic species of mushroom in the family Physalacriaceae. Widely distributed in tropical regions of the world, it is characterized by the bright orange to yellow cap that in young specimens is covered with tufts of fibrils resembling small spikes. This fungus has had a varied taxonomical history, having been placed in fourteen genera before finally settling in Cyptotrama. This species is differentiated from several other similar members of genus Cyptotrama by variations in cap color, and spore size and shape.
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In bone, mineralization starts from a heterogeneous solution having calcium and phosphate ions. The mineral nucleates, inside the hole area of the collagen fibrils, as thin layers of calcium phosphate, which then grow to occupy the maximum space available there. The mechanisms of mineral deposition within the organic portion of the bone are still under investigation. Three possible suggestions are that nucleation is either due to the precipitation of calcium phosphate solution, caused by the removal of biological inhibitors or occurs because of the interaction of calcium-binding proteins.
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Advancements in technology have allowed the development of transgenic mice expressing A53T alpha-synuclein that have been used in multiple studies on Parkinson's disease. Wild-type alpha-synuclein has been shown to form oligomeric species termed protofibrils before forming full fibrils. Research has been conducted to test the hypothesis that the oligomeric protofibril species is neurotoxic rather than the fibrillar species. Electron microscopy has revealed that the A53T mutant protein formed annular and tubular protofibrils easily, whereas the wild-type protein formed annular protofibrils only after extended incubation.
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Activated or ameboid microglia and macrophages that contain myelin debris, lipid droplets and brown autofluorescent pigment granules are found in the areas with demyelination and axonal spheroids. In severely degenerated areas there are many large, reactive astrocytes filled with glial fibrils. In autopsy cases, it has been shown that white matter abnormalities are relatively confined to the cerebrum while avoiding the cerebellum and many of the major fiber tracts of the nervous system. The exception is the corticospinal tracts(pyramidal tracts) in the brainstem and sometimes spinal cord.
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When there are changes in the non-covalent interactions, as may happen with a change in the amino acid sequence, the protein is susceptible to misfolding or unfolding. In these cases, if the cell does not assist the protein in re-folding, or degrade the unfolded protein, the unfolded/misfolded protein may aggregate, in which the exposed hydrophobic portions of the protein may interact with the exposed hydrophobic patches of other proteins. There are three main types of protein aggregates that may form: amorphous aggregates, oligomers, and amyloid fibrils.
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The stem measures long by thick, and is equal in width throughout its length. The top of the stem is colored yellowish and has a silky fibrillose texture, while lower it is brownish. There is a ring, or a remnant ring zone area left by the degraded partial veil, whose pale yellow fibrils may initially be covered with a thin layer of slime.Smith and Hesler (1969), p. 245. The spore print is dark rusty brown, and the spores are smooth, broadly egg-shaped to elliptical, and measure 7–9 by 5–6 μm.
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In the 1970s a special eleven-member Turin Commission conducted several tests. Conventional and electron microscopic examination of the Shroud at that time revealed an absence of heterogeneous coloring material or pigment. In 1979, Walter McCrone, upon analyzing the samples he was given by STURP, concluded that the image is actually made up of billions of submicrometre pigment particles. The only fibrils that had been made available for testing of the stains were those that remained affixed to custom-designed adhesive tape applied to thirty-two different sections of the image.
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The large globular domains from both ends of the molecule are removed by C- and amino(N)-terminal-proteinases to generate triple-helical type III collagen monomers called tropocollagen. In addition, crosslinks form between certain lysine and hydroxylysine residues. In the extracellular space in tissues, type III collagen monomers assemble into macromolecular fibrils, which aggregate into fibers, providing a strong support structure for tissues requiring tensile strength. The triple-helical conformation, which is a characteristic feature of all fibrillar collagens, is possible because of the presence of a glycine as every third amino acid in the sequence of about 1000 amino acids.
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Aside from the cellular form, the only other known isoform is Gelsolin-3, an identical non-secreted protein containing an 11 AA, rather than 24 AA, N-terminal extension. It has been found in brain, testis, and lung oligodendrocytes, and is reportedly involved in myelin remodeling during spiralization around the axon. Plasma Gelsolin is highly conserved and its only known mutations are single point mutations. One of several such mutations leads to Finnish Familial Amyloidosis, a disorder in which pGSN becomes more conformationally flexible and susceptible to enzymatic cleavage resulting in accumulation of peptide fragments into amyloid fibrils.
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In another application, multiwall carbon nanotube (MWCNT) and single wall carbon nanotube (SWCNT) tips were used to image amyloid β (1-40) derived protofibrils and fibrils by tapping mode AFM. Functionalized probes can be used in Chemical Force Microscopy (CFM) to measure intermolecular forces and map chemical functionality. Functionalized SWCNT probes can be used for chemically sensitive imaging with high lateral resolution and to study binding energy in chemical and biological system. Probe tips that have been functionalized with either hydrophobic or hydrophilic molecules can be used to measure the adhesive interaction between hydrophobic-hydrophobic, hydrophobic-hydrophilic, and hydrophilic-hydrophilic molecules.
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The Cords of Billroth (also known as splenic cords or red pulp cords) are found in the red pulp of the spleen between the sinusoids, consisting of fibrils and connective tissue cells with a large population of monocytes and macrophages. These cords contain half of the mouse body's monocytes as a reserve so that after tissue injury these monocytes can move in and aid locally sourced monocytes in wound healing. Erythrocytes pass through the cords of Billroth before entering the sinusoids. The passage into the sinusoids may be seen as a bottleneck, where erythrocytes need to be flexible in order to pass through.
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The notes have two security threads, the first being an opaque band, and the second being the text "50 MIL PESOS COLOMBIA" which can be seen under direct light. There is a watermark of Jorge Isaacs' face, along with many examples of relief printing. Under ultraviolet light, the note appears to be orange with yellow fibrils. It is also protected by a serial number, and various microprinting and colour-shifting ink is used on the front for the number 50 (which the colour-shifting ink causes to change from a golden to green colour when tilted).
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It is paramount to understand how odontoblast differentiate from ectomesenchymal cells to allow comprehension and explanation of normal development and to be able to affect their recruitment when needed to start repairing the dentin. Growth factors in the cells of the inner enamel epithelium and expressions of signaling molecules bring about the differentiation of odontoblast through normal development of the dental papilla. Exhibiting a central nucleus and few organelles, the dental papilla cells are small and undifferentiated. At this stage, the cells are separated by an acellular zone, that consist of some fine collagen fibrils, from the inner enamel epithelium.
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Below the ring-like annular zone the stem is nattered; above, it is white and smooth. The cap of H. olivaceoalbus is wide and is hemispherical in young fungi; they become flatter and wider with age, but they keep their characteristic dark umbo. Underneath the slimy grey to sooty-brown surface, the cap cuticle is streaked with fine, dark grey radially arranged fibers. Young fruit bodies are covered by two velum layers; the inner velum, composed of dark fibrils, becomes a ring or sheath (annular zone) on the stem that is covered by the gelatinous outer layer.
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Type II collagen, which adds structure and strength to connective tissues, is found primarily in cartilage, the jelly-like substance that fills the eyeball (the vitreous), the inner ear, and the center portion of the discs between the vertebrae in the spine (nucleus pulposus). Three pro-alpha1(II) chains twist together to form a triple-stranded, ropelike procollagen molecule. These procollagen molecules must be processed by enzymes in the cell. Once these molecules are processed, they leave the cell and arrange themselves into long, thin fibrils that cross- link to one another in the spaces around cells.
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Alpha keratin is found in mammalian hair, skin, nails, horn and quills, while beta keratin can be found in avian and reptilian species in scales, feathers, and beaks. The two different structures of keratin have dissimilar mechanical properties, as seen in their dissimilar applications. The relative alignment of the keratin fibrils has a significant impact on the mechanical properties. In human hair the filaments of alpha keratin are highly aligned, giving a tensile strength of approximately 200MPa. This tensile strength is an order of magnitude higher than human nails (20MPa), because human hair’s keratin filaments are more aligned.
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Monomeric α-synuclein is natively unfolded in solution but can also bind to membranes in an α-helical form. It seems likely that these two species exist in equilibrium within the cell, although this is unproven. From in vitro work, it is clear that unfolded monomer can aggregate first into small oligomeric species that can be stabilized by β-sheet-like interactions and then into higher molecular weight insoluble fibrils. In a cellular context, there is some evidence that the presence of lipids can promote oligomer formation: α-synuclein can also form annular, pore-like structures that interact with membranes.
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A young fruit body Spores 1000x The fruit bodies of Lepiota castaneidisca have white, bell-shaped to convex caps in diameter, with an orange-reddish to pale orange-brown center. Mature specimens fade and lose the reddish shades. The cap surface develops small pale pink or cream patches (especially on the outermost zone) on a white background that has radially arranged fibrils. The gills are somewhat crowded to moderately distant, with typically 40–45 full length gills, and 1–5 tiers of interspersed lamellulae (short gills that do not extend fully from the cap margin to the stem).
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Similarly, the hierarchy of abalone shell begins at the nanolevel, with an organic layer having a thickness of 20–30 nm. This layer proceeds with single crystals of aragonite (a polymorph of CaCO3) consisting of "bricks" with dimensions of 0.5 and finishing with layers approximately 0.3 mm (mesostructure). Crabs are arthropods whose carapace is made of a mineralized hard component (which exhibits brittle fracture) and a softer organic component composed primarily of chitin. The brittle component is arranged in a helical pattern. Each of these mineral ‘rods’ (1 μm diameter) contains chitin–protein fibrils with approximately 60 nm diameter.
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However, for silks, fibrils persist without the need for a drop in temperature. From a macromolecular perspective the two processes are thought to be similar due to a native protein's unique interaction with its closely bound water. Much like an individual polymer chain in a melt, a native protein and its closely bound water molecules may be considered not as a solution but as a single processable entity, a nanocomposite termed an "aquamelt". The differences between a typical polymer and an aquamelt are highlighted by an aquamelt's ability to solidify in response to stress at environmental temperatures.
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The 1953 Science article mentioned above concluded that the reticular and regular collagenous materials contains the same four sugars – galactose, glucose, mannose, and fucose – but in a much greater concentration in the reticular than in the collagenous material. In a 1993 paper, the reticular fibers of the capillary sheath and splenic cord were studied and compared in the pig spleen by transmission electron microscopy. This paper attempted to reveal their components and the presence of sialic acid in the amorphous ground substance. Collagen fibrils, elastic fibers, microfibrils, nerve fibers, and smooth muscle cells were observed in the reticular fibers of the splenic cord.
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The stem-like cone granules, fewer in number than the rod granules, are placed close to the membrana limitans externa, through which they are continuous with the cones of the layer of rods and cones. They do not present any cross-striation, but contain a pyriform nucleus, which almost completely fills the cell. From the inner extremity of the granule a thick process passes into the outer plexiform layer, and there expands into a pyramidal enlargement or foot plate, from which are given off numerous fine fibrils, that come in contact with the outer processes of the cone bipolars.
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Although McLeish's work is mostly theoretical, he also works closely with those performing experiments and in industry. He has made significant advances in modelling the structure and properties of complex entangled molecules, blends of substances that don't usually mix (multiphasic liquids like oil and water) see reptation and crazing. This allows us to more easily predict complex fluid behaviour and processing in an industrial setting. Since 2000 he has increasingly worked on biological physics: applying soft matter physics to self-assembly of protein fibrils, protein fluctuation dynamics and its role in allosteric signalling, and statistical mechanics approaches to evolution.
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Furthermore, analytical capabilities of these instruments such as spectroscopy and diffraction can be used to further characterize the sample, providing a complete picture of the evolution of the specimen as it is loaded and fails. Owing to the development of mature MEMS microfabrication technologies, the use of these microsystems for research purposes has been increasing in recent years. Most of the current developments aim to implement in situ mechanical testing coupled with other type of measurements, such as electrical or thermal, and to extend the range of samples tested to the biological domain, testing specimens such as cells and collagen fibrils.
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Fenestrated capillaries have pores known as fenestrae (Latin for "windows") in the endothelial cells that are 60–80 nm in diameter. They are spanned by a diaphragm of radially oriented fibrils that allows small molecules and limited amounts of protein to diffuse. In the renal glomerulus there are cells with no diaphragms, called podocyte foot processes or pedicels, which have slit pores with a function analogous to the diaphragm of the capillaries. Both of these types of blood vessels have continuous basal laminae and are primarily located in the endocrine glands, intestines, pancreas, and the glomeruli of the kidney.
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The gills are distantly spaced and have an emarginate attachment to the stem The cap is wide, convex, with a flattish or more pointed umbo (occasionally the umbo may be lacking), watery date brown, hygrophanous. In damp weather the cap surface is almost chestnut brown in young specimens, in dry weather grayish-brown to tan brown. The surface is soon silky and the margin almost white from floccose, white fibrils (these are easily washed off by rain), otherwise only very slightly whitish fibrillose, finally even bare. When the tip of the stem is hollow, the cap which is thinly fleshy and quite tough.
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The gills are distantly spaced, grayish-earthy, then ochraceous ferruginous, later almost cinnamon, broadly emarginate (notched), broad, slightly ventricose, with lightly scalloped edge. The stem is cylindrical, quite slender, usually slightly crooked, long and thick, light brown inside with thin, winding fibers, then eventually hollow. It is white, covered with silky fibrils on the surface, often with an ephemeral white zone in the middle which may be poorly developed, otherwise pale dirty gray, with steel gray to violet tinge at the apex. The flesh is watery brown in damp weather, then much lighter, whitish with brownish tinge.
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Beneath the cap there is a golden yellow ring-like region. On the rest of the stem there are sometimes remnants of the partial veil as yellowish-saffron hairy tufts, which form incomplete rings or scattered minute scales. The cortina (a cobweb-like partial veil consisting of silky fibrils) is thick, whitish, and lasts only a short time. The flesh in the cap is thin, rarely thicker than , whitish to pale violet or pale lilac in the upper part of the stem when young, but soon fading, grayish-white in the lower part of the stem.
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In 2010, this mouse model allowed a new insight into myopathy and tendinopathy, which are often associated with PSACH and MED. These patients show increased skeletal muscle stress, as indicated by the increase in myofibers with central nuclei. Myopathy in the mutant mouse results from underlying tendinopathy, because the transmission of forces is altered from the normal state. There is a higher proportion of larger diameter fibrils of collagen, but the cross-sectional area of whole mutant tendons was also significantly less than that of the wild-type tendons causing joint laxity and stiffness, easy tiring and weakness.
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Recently, significant enhancement of fluorescence quantum yield of NIAD-4 was exploited to super-resolution fluorescence imaging of amyloid fibrils and oligomers. To avoid nonspecific staining, other histology stains, such as the hematoxylin and eosin stain, are used to quench the dyes' activity in other places such as the nucleus, where the dye might bind. Modern antibody technology and immunohistochemistry has made specific staining easier, but often this can cause trouble because epitopes can be concealed in the amyloid fold; in general, an amyloid protein structure is a different conformation from the one that the antibody recognizes.
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Mice that have the lumican gene knocked out (Lum-/-) develop opacities of the cornea in both eyes and fragile skin. The lumican (LUM) gene was thought to be a candidate susceptibility gene for high myopia; however, a meta-analysis showed no association between LUM polymorphism and high myopia susceptibility in all genetic models studied. Lum knockout mice also have abnormal collagen in their heart tissue, with fewer and thicker fibrils. Mice deficient in both lumican and fibromodulin develop severe tendinopathy (tendon pathology), revealing the importance of these SLRPs in the development of correctly sized and aligned collagen fibers in tendon.
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The IbpB protein, whose expression is regulated by the IbpB thermometer, is 48% identical to IbpA (at the level of amino acid sequence) yet fulfils a different role in heat shock. When IbpB is absent, IbpA protein will form long fibrils which is unusual for a heat shock protein; IbpB, acting as a co-chaperone, inhibits IbpA from forming this structure. Under heat shock, IbpB protein dissociates to give two smaller subunits and also rearranges its tertiary structure. This "remarkable conformational transformation" is thought to be essential for IbpB to act as a co-chaperone with IbpA under heat shock.
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Exactly how disturbances of production and aggregation of the beta-amyloid peptide give rise to the pathology of AD is not known. The amyloid hypothesis traditionally points to the accumulation of beta-amyloid peptides as the central event triggering neuron degeneration. Accumulation of aggregated amyloid fibrils, which are believed to be the toxic form of the protein responsible for disrupting the cell's calcium ion homeostasis, induces programmed cell death (apoptosis). It is also known that Aβ selectively builds up in the mitochondria in the cells of Alzheimer's-affected brains, and it also inhibits certain enzyme functions and the utilisation of glucose by neurons.
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Formication is etymologically derived from the Latin word formica, meaning "ant", precisely because of this similarity in sensation to that of crawling insects. The term has been in use for several hundred years. In the 1797 edition of the Encyclopædia Britannica, a description of the condition raphania includes the symptom: Described again in an instructional text from 1890: > A variety of itching, often encountered in the eczema of elderly people, is > formication; this is described as exactly like the crawling of myriads of > animals over the skin. It is probably due to the successive irritation of > nerve fibrils in the skin.
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The elongation and the strain of the collagen fibrils alone have been shown to be much lower than the total elongation and strain of the entire tendon under the same amount of stress, demonstrating that the proteoglycan- rich matrix must also undergo deformation, and stiffening of the matrix occurs at high strain rates. This deformation of the non-collagenous matrix occurs at all levels of the tendon hierarchy, and by modulating the organisation and structure of this matrix, the different mechanical properties required by different tendons can be achieved.Gupta H.S., Seto J., Krauss S., Boesecke P.& Screen H.R.C. (2010). In situ multi-level analysis of viscoelastic deformation mechanisms in tendon collagen.
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The first category of tendinopathy is paratenonitis, which refers to inflammation of the paratenon, or paratendinous sheet located between the tendon and its sheath. Tendinosis refers to non-inflammatory injury to the tendon at the cellular level. The degradation is caused by damage to collagen, cells, and the vascular components of the tendon, and is known to lead to rupture. Observations of tendons that have undergone spontaneous rupture have shown the presence of collagen fibrils that are not in the correct parallel orientation or are not uniform in length or diameter, along with rounded tenocytes, other cell abnormalities, and the ingrowth of blood vessels.
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In 1956, the microcrack theory became the first to explain the toughening effect of a dispersed rubber phase in a polymer. Two key observations that went into the initial theory and subsequent expansion were as follows: (1) microcracks form voids over which styrene-butadiene copolymer fibrils form to prevent propagation, and (2) energy stored during elongation of toughened epoxies is released upon breaking of rubber particles. The theory concluded that the combined energy to initiate microcracks and the energy to break rubber particles could account for the increased energy absorption of toughened polymers. This theory was limited, only accounting for a small fraction of the observed increase in fracture energy.
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These ß-sheets form a parallel left-handed beta-helix. Three PrPSc molecules are believed to form a primary unit and therefore build the basis for the so- called scrapie-associated fibrils. The catalytic activity depends on the size of the particle. PrPSc particles which consist of only 14-28 PrPc molecules exhibit the highest rate of infectivity and conversion. Despite the difficulty to purify and characterize PrPSc, from the known molecular structure of PrPc and using transgenic mice and N-terminal deletion, the potential ‘hot spots’ of protein misfolding leading to the pathogenic PrPSc could be deduced and Folding@home could be of great value in confirming these.
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Molecular surface model of K-Casein Caseins are a family of phosphoproteins (αS1, αS2, β, κ) that account for nearly 80% of bovine milk proteins and that form soluble aggregates are known as "casein micelles" in which κ-casein molecules stabilize the structure. There are several models that account for the special conformation of casein in the micelles. One of them proposes that the micellar nucleus is formed by several submicelles, the periphery consisting of microvellosities of κ-casein Another model suggests that the nucleus is formed by casein-interlinked fibrils. Finally, the most recent model proposes a double link among the caseins for gelling to take place.
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A transparency of 50 per cent is enough to make an animal invisible to a predator such as cod at a depth of ; better transparency is required for invisibility in shallower water, where the light is brighter and predators can see better. For example, a cod can see prey that are 98 per cent transparent in optimal lighting in shallow water. Therefore, transparency is most effective in deeper waters. The transparent goby Some tissues such as muscles can be made transparent, provided either they are very thin or organised as regular layers or fibrils that are small compared to the wavelength of visible light.
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In a MCC composite however this is not the case, if the interaction between the filler and matrix is stronger than the filler-filler interaction the mechanical strength of the composite is noticeably decreased. Difficulties in natural fiber nanocomposites arise from dispersity and the tendency small fibers to aggregate in the matrix. Because of the high surface area to volume ratio the fibers have a tendency to aggregate, more so than in micro-scale composites. Additionally secondary processing of collagen sources to obtain sufficient purity collagen micro fibrils adds a degree of cost and challenge to creating a load bearing cellulose or other filler based nanocomposite.
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The alpha sheet has been proposed as a possible intermediate state in the conformational change in the formation of amyloid fibrils by peptides and proteins such as amyloid beta, poly-glutamine repeats, lysozyme, prion proteins, and transthyretin repeats, all of which are associated with protein misfolding disease. For example, amyloid beta is a major component of amyloid plaques in the brains of Alzheimer's disease patients, and polyglutamine repeats in the huntingtin protein are associated with Huntington's disease.Armen RS, Bernard BM, Day R, Alonso DO, Daggett V. (2005). Characterization of a possible amyloidogenic precursor in glutamine-repeat neurodegenerative diseases. Proc Natl Acad Sci USA 102(38):13433-8.
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TTR amyloid fibrils infiltrate the myocardium, leading to diastolic dysfunction from restrictive cardiomyopathy, and eventual heart failure. Both mutant and wild-type transthyretin comprise the aggregates because the TTR blood protein is a tetramer composed of mutant and wild-type TTR subunits in heterozygotes. Several mutations in TTR are associated with FAC, including V122I, V20I, P24S, A45T, Gly47Val, Glu51Gly, I68L, Gln92Lys, and L111M. One common mutation (V122I), which is a substitution of isoleucine for valine at position 122, occurs with high frequency in African-Americans, with a prevalence of approximately 3.5%. FAC is clinically similar to senile systemic amyloidosis,Westermark, P., Sletten, K., Johansson, B. & Cornwell, G. G., 3rd. (1990).
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Therefore, the proteasome pathway may not be efficient enough to degrade the misfolded proteins prior to aggregation. Misfolded proteins can interact with one another and form structured aggregates and gain toxicity through intermolecular interactions. Aggregated proteins are associated with prion- related illnesses such as Creutzfeldt–Jakob disease, bovine spongiform encephalopathy (mad cow disease), amyloid-related illnesses such as Alzheimer's disease and familial amyloid cardiomyopathy or polyneuropathy, as well as intracellular aggregation diseases such as Huntington's and Parkinson's disease. These age onset degenerative diseases are associated with the aggregation of misfolded proteins into insoluble, extracellular aggregates and/or intracellular inclusions including cross-β amyloid fibrils.
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A. brunnescens According to Singer, the species is often mistaken for A. verna in the eastern United States. A. verna, however, has ellipsoid spores. Other white amanitas within the range of A. aestivalis include the deadly toxic species A. virosa (has a more loose cottony stem), A. phalloides (the cap usually has an olive-green tint) and A. bisporigera (typically has two-spored basidia). A. aestivalis is sometimes considered a white form of A. brunnescens, but this latter species has dusky brownish gray radial stripes and usually has many fibrils (short section of hyphae) projecting from the surface, to produce a fine, hairy appearance.
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Towards the right: Phragmoplast enlarges in a donut-shape towards the outside of the cell, leaving behind mature cell plate in the center. The cell plate will transform into the new cell wall once cytokinesis is complete.P.H. Raven, R.F. Evert, S.E. Eichhorn (2005): Biology of Plants, 7th Edition, W.H. Freeman and Company Publishers, New York, ISBN 0-7167-1007-2 Another synapomorphy of this clade is the synthesis of cellulose microfibrils by a complex of octameric cellulose synthetases. This complex crosses the plasma membrane and polymerizes molecules from the cytoplasm into cellulose microfibrils, which, together with each other, form fibrils, necessary in the formation of the wall.
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This biofilm is a natural defense mechanism for the co- culture, and can withstand extreme conditions such as temperature and UV radiation. Two additional characteristics of the nanofibril cellulose SCOBY—its high purity and crystallinity—are currently a target in biomedical research in the formation of biocompatible tissue scaffolds, cardiovascular components such as blood vessels, bone grafts, and connective tissue replacements. The nanocellulose fibrils can also be extracted via acid hydrolysis and used in the food packaging, clothing, and wastewater treatment industries. The thickness of a kombucha SCOBY is contingent on all brewing conditions, but one study reported an average a thickness of two to five millimeters.
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On the other hand, there are genetic variations which appear to cause the deposition of LECT2 in tissues. Studies to date have failed to obtain evidence for LECT2 gene mutations in the disorder but most cases examined in the United States are associated with a particular homozygous single nucleotide polymorphism (i.e. SNP) in the LECT2 gene. This SNP occurs in exon 3 at codon 58 of the gene, contains a guanine rather than adenine nucleotide at this site, and consequently codes for the amino acid valine rather than isoleucine. Although not yet proven to occur in vivo, the Val58Ile variant of LECT2 may have a propensity to fold abnormally, form insoluble fibrils, and therefore deposits in tissues.
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Robert Tycko is an American biophysicist whose research primarily involves solid state NMR, including the development of new methods and applications to various areas of physics, chemistry, and biology. He is a member of the Laboratory of Chemical Physics in the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health in Bethesda, Maryland, USA. He was formerly a member of the Physical Chemistry Research and Materials Chemistry Research departments of AT&T; Bell Labs in Murray Hill, New Jersey. His work has contributed to our understanding of geometric phases in spectroscopy, physical properties of fullerenes, skyrmions in 2D electron systems, protein folding, and amyloid fibrils associated with Alzheimer’s disease and prions.
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For example, using AFM–based nanoindentation it has been shown that a single collagen fibril is a heterogeneous material along its axial direction with significantly different mechanical properties in its gap and overlap regions, correlating with its different molecular organizations in these two regions. Collagen fibrils/aggregates are arranged in different combinations and concentrations in various tissues to provide varying tissue properties. In bone, entire collagen triple helices lie in a parallel, staggered array. 40 nm gaps between the ends of the tropocollagen subunits (approximately equal to the gap region) probably serve as nucleation sites for the deposition of long, hard, fine crystals of the mineral component, which is hydroxylapatite (approximately) Ca10(OH)2(PO4)6.
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The short gills are truncate to subtruncate to subattenuate to attenuate to attenuate in steps, unevenly distributed, of diverse lengths, and plentiful. The stem is 52-150 (5.2–15 cm) × 7–14 mm (0.7-1.4 cm), usually narrowing upward, infrequently narrowing downward, flaring at the top, yellow to white or very pale yellowish white and pruinose to finely powdery above the ring, white to yellow or occasionally with scattered yellowish surface fibrils and fibrillose below the ring, sometimes silky longitudinally striate. The bulb is 15 - 25 × 15 – 21 mm, more or less turnip-shaped, with light red-pinkish stains; interior of the bulb is often the place where wine-red staining first appears intensely.
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According to the Web of Science, the most-cited articles of this journal are: # "'Automated docking of flexible ligands: Applications of AutoDock", Volume 9, Issue 1, Jan-Feb 1996, Pages: 1-5, Goodsell DS, Morris GM, Olson AJ. # "Improving biosensor analysis", Volume 12, Issue 5, Sep-Oct 1999, Pages: 279-284, Myszka DG. # "Reversible and irreversible immobilization of enzymes on Graphite Fibrils(TM)", Volume 9, Issue 5-6, Sep-Dec 1996, Pages: 383-388, Dong LW, Fischer AB, Lu M, et al. # "Isothermal titration calorimetry and differential scanning calorimetry as complementary tools to investigate the energetics of biomolecular recognition", Volume 12, Issue 1, Jan-Feb 1999, Pages: 3–18, Jelesarov I, Bosshard HR.
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Lewis observed that the connective tissue fibrils resulted from the cytoplasmic transformations of the cells. In her studies of explanted tissue cultures, Lewis noted that the cells choose to migrate away from the tissue sample and divide as individual cells, resulting in loss of the tissue’s characteristic appearance. However, she also made the distinction that the cells do not become more embryonic like Champy and others claimed, but instead lose their differentiated appearance as a tissue. This spreading of the cells and lack of characteristic tissue form caused fibril development in many tissue cultures to be lacking; however, there were a few cultures where connective tissue fibers did develop, and their progression could be tracked.
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Other membrane proteins that Hong's group has studied include β-hairpin antimicrobial peptides, channel-forming colicins, and viral fusion proteins. She determined the structure of the membrane toroidal pores formed by the antimicrobial peptide protegrin-1, which explained the membrane-disruptive mechanism of this peptide. She showed that the transmembrane domain of viral fusion proteins can be conformationally plastic, and the β-sheet conformation can correlate with the generation of membrane curvature and membrane dehydration, which are necessary for virus-cell fusion. Hong has also investigated the structure and dynamics of amyloid proteins, including full- length tau and Aβ peptides involved in neurodegenerative diseases as well as amyloid fibrils formed by designed peptides.
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It is pseudo-plastic and exhibits thixotropy, the property of certain gels or fluids that are thick (viscous) under normal conditions, but become less viscous when shaken or agitated. When the shearing forces are removed the gel regains much of its original state. The fibrils are isolated from any cellulose containing source including wood-based fibers (pulp fibers) through high-pressure, high temperature and high velocity impact homogenization, grinding or microfluidization (see manufacture below). Nanocellulose can also be obtained from native fibers by an acid hydrolysis, giving rise to highly crystalline and rigid nanoparticles which are shorter (100s to 1000 nanometers) than the cellulose nanofibrils (CNF) obtained through homogenization, microfluiodization or grinding routes.
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SFTPC is a 197-residue protein made up of two halves: a unique N-terminal propeptide domain and a C-terminal BRICHOS domain. The around 100-aa long propeptide domain actually contains not only the cleaved part, but also the mature peptide. It can be further broken down into a 23-aa helical transmembrane propeptide proper, the mature secreted SP-C (24-58), and a linker (59-89) that connects to the BRICHOS domain. The propeptide of pulmonary surfactant C has an N-terminal alpha-helical segment whose suggested function was stabilization of the protein structure, since the mature peptide can irreversibly transform from its native alpha-helical structure to beta- sheet aggregates and form amyloid fibrils.
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It is not completely clear whether the aggregates are the cause or merely a reflection of the loss of protein homeostasis, the balance between synthesis, folding, aggregation and protein turnover. Recently the European Medicines Agency approved the use of Tafamidis or Vyndaqel (a kinetic stabilizer of tetrameric transthyretin) for the treatment of transthyretin amyloid diseases. This suggests that the process of amyloid fibril formation (and not the fibrils themselves) causes the degeneration of post-mitotic tissue in human amyloid diseases. Misfolding and excessive degradation instead of folding and function leads to a number of proteopathy diseases such as antitrypsin-associated emphysema, cystic fibrosis and the lysosomal storage diseases, where loss of function is the origin of the disorder.
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For example, an interaction with CD40 on T-cells induced their proliferation inhibition and cell death. Galectin-9 also has important cytoplasmic, intracellular functions and controls AMPK in response to lysosomal damage that can occur upon exposure to endogenous and exogenous membrane damaging agents such as crystalline silica, cholesterol crystals, microbial toxins, proteopathic aggregates such as tau fibrils and amyloids, and signaling pathways inducing lysosomal permeabilization such as those initiated by TRAIL. Mild lysosomal damage, such as that caused by the anti-diabetes drug metformin may contribute to the therapeutic action of metformin by activating AMPK. The mechanism of how Galectin-9 activates AMPK involves recognition of exposed lysosomal lumenal glycoproteins such as LAMP1, LAMP2, SCRAB2, TMEM192, etc.
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Mesenchymal stem cells within mesenchyme or the medullary cavity of a bone fracture initiate the process of intramembranous ossification. A mesenchymal stem cell, or MSC, is an unspecialized cell that can develop into an osteoblast. Before it begins to develop, the morphological characteristics of a MSC are: A small cell body with a few cell processes that are long and thin; a large, round nucleus with a prominent nucleolus that is surrounded by finely dispersed chromatin particles, giving the nucleus a clear appearance; and a small amount of Golgi apparatus, rough endoplasmic reticulum, mitochondria, and polyribosomes. Furthermore, the mesenchymal stem cells are widely dispersed within an extracellular matrix that is devoid of every type of collagen, except for a few reticular fibrils.
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A single collagen molecule, tropocollagen, is used to make up larger collagen aggregates, such as fibrils. It is approximately 300 nm long and 1.5 nm in diameter, and it is made up of three polypeptide strands (called alpha peptides, see step 2), each of which has the conformation of a left-handed helix – this should not be confused with the right-handed alpha helix. These three left-handed helices are twisted together into a right-handed triple helix or "super helix", a cooperative quaternary structure stabilized by many hydrogen bonds. With type I collagen and possibly all fibrillar collagens, if not all collagens, each triple-helix associates into a right-handed super-super-coil referred to as the collagen microfibril.
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Similarly, circularly disposed muscular fibrils formed from the endoderm permit tentacles to be protract or thrust out once they are contracted. These muscle fibres belong to the same two systems, thus allows the whole body to retract or protrude outwards. We can distinguish therefore in the body of a polyp the column, circular or oval in section, forming the trunk, resting on a base or foot and surmounted by the crown of tentacles, which enclose an area termed the peristome, in the centre of which again is the mouth. As a rule there is no other opening to the body except the mouth, but in some cases excretory pores are known to occur in the foot, and pores may occur at the tips of the tentacles.
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TTR misfolding and aggregation is known to be associated with the amyloid diseases senile systemic amyloidosis (SSA), familial amyloid polyneuropathy (FAP), and familial amyloid cardiomyopathy (FAC). TTR tetramer dissociation is known to be rate-limiting for amyloid fibril formation. However, the monomer also must partially denature in order for TTR to be mis-assembly competent, leading to a variety of aggregate structures, including amyloid fibrils. While wild type TTR can dissociate, misfold, and aggregate, leading to SSA, point mutations within TTR are known to destabilize the tetramer composed of mutant and wild-type TTR subunits, facilitating more facile dissociation and/or misfolding and amyloidogenesis. A replacement of valine by methionine at position 30 (TTR V30M) is the mutation most commonly associated with FAP.
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These ultimately leave the trabecular sheaths, and terminate in the proper substance of the spleen in small tufts or pencils of minute arterioles, which open into the interstices of the reticulum formed by the branched sustentacular cells. Each of the larger branches of the artery supplies chiefly that region of the organ in which the branch ramifies, having no anastomosis with the majority of the other branches. The arterioles, supported by the minute trabeculae, traverse the pulp in all directions in bundles (penicilli) of straight vessels. Their trabecular sheaths gradually undergo a transformation, become much thickened, and converted into adenoid tissue; the bundles of connective tissue becoming looser and their fibrils more delicate, and containing in their interstices an abundance of lymph corpuscles.
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In 1859, Friedreich and Kekulé demonstrated that, rather than consisting of cellulose, "amyloid" actually is rich in protein. Subsequent research has shown that many different proteins can form amyloid, and that all amyloids show birefringence in cross-polarized light after staining with the dye Congo red, as well as a fibrillar ultrastructure when viewed with an electron microscope. However, some proteinaceous lesions lack birefringence and contain few or no classical amyloid fibrils, such as the diffuse deposits of amyloid beta (Aβ) protein in the brains of people with Alzheimer's. Furthermore, evidence has emerged that small, non-fibrillar protein aggregates known as oligomers are toxic to the cells of an affected organ, and that amyloidogenic proteins in their fibrillar form may be relatively benign.
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Studies investigating cyst wall composition have shown that the wall specifically contains chitin, chitosan fibrils, and chitin binding proteins. As opposed to walls of plants and fungi who have multilayered walls, the Entamoeba cyst wall is homogenous—containing only one layer. The combination of these elements confers resistance to extreme environmental conditions such as desiccation, heat, and detergent Despite the amount of research conducted to date, the formation of the cyst wall during encystation has not yet been clearly defined. Scientists do know that during this process, the level of cytoplasmic vesicles is significantly reduced, which is thought to be caused by vesicles fusing with the plasma membrane in order to deposit the cyst wall on the exterior of the cell.
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The cap is quite thinly fleshy, in diameter, initially quite spherical, later bluntly convex to bell-shaped, usually with an umbo, and often irregular and bent or wavy towards the margin. The margin is initially curved inward, then straight, sometimes at the margin itself slightly flexuosely rugose or even briefly fimbriate. The cap surface is dry and opaque, fibrillosely squamulose, tomentose, at first vivid yellow ochre to yellow or copper olivaceous, later glabrescent or quite glabrous and when mature brownish olive or light olive, often with a saffron tint at the margin, and with numerous fibrils from the universal veil when young; later the margin is mostly concolorous. The gills are crowded closely together and have an emarginate attachment to the stem.
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A hypothesis formed by M. Harold and his colleagues suggests that tip growth in higher plans is amoebic in nature, and isn't caused by turgor pressure as is widely believed, meaning that extension is caused by the actin cytoskeleton in these plant cells. Regulation of cell growth is implied to be caused by cytoplasmic micro-tubules which control the orientation of cellulose fibrils, which are deposited into the adjacent cell wall and results in growth. In plants, the cells are surrounded by cell walls and filamentous proteins which retain and adjust the plant cell's growth and shape. As explained in the paper, lower plants grow through apical growth, which differs since the cell wall only expands on one end of the cell.
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An initial goal of ADNI was to understand the development of AD pathology by tracking imaging and CSF biomarkers throughout disease progression according to the amyloid hypothesis. A model of how different AD biomarkers change during the development of the AD proposed that biomarkers become abnormal in the following order: # β-amyloid (indicating deposition of amyloid in plaques outside the cell, measured in CSF and by amyloid PET) # Tau (indicating the formation of tau fibrils with the neurons) # Glucose metabolism (measured on PET, indicating damage to neurons) # Structural MRI (indicating damage to brain structure) # Cognitive impairment This model has been largely validated using longitudinal ADNI data in patients who have abnormal levels of amyloid deposition, consistent with the amyloid hypothesis.
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They suggested two possibilities of such arrangements: circular arrangement (armchair nanotube) and a spiral, helical arrangement (chiral tube).Izvestiya Akademii Nauk SSSR, Metals. 1982, #3, pp. 12–17 (in Russian) In 1987, Howard G. Tennent of Hyperion Catalysis was issued a U.S. patent for the production of "cylindrical discrete carbon fibrils" with a "constant diameter between about 3.5 and about 70 nanometers..., length 102 times the diameter, and an outer region of multiple essentially continuous layers of ordered carbon atoms and a distinct inner core...." Iijima's discovery of multi-walled carbon nanotubes in the insoluble material of arc-burned graphite rods in 1991 and Mintmire, Dunlap, and White's independent prediction that if single-walled carbon nanotubes could be made, then they would exhibit remarkable conducting properties helped create the initial excitement associated with carbon nanotubes.
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Although degeneration of basal forebrain cholinergic cells has been observed in many other dementias, Alzheimer's has two distinctive histological hallmarks: Beta amyloid plaques and neurofibrillary tangles. The Beta amyloid plaques are high-molecular weight fibrils and are major components of the senile Alzheimer's disease brain. There appears to be a vast, intrinsic microvascular pathology of the brain in these cases, which suggests a link between Beta amyloid production, impairments in cerebrovascular function, and basal forebrain cholinergic deficits in AD. It appears that Beta amyloid (1-42) mediates its cytotoxic action by affecting key proteins that play a role in apoptosis induction. There is also evidence that shows beta amyloid proteins actually bind to cholinergic neurons and physically inhibit ChAT activity in cultures treated with oligomers of beta amyloid.
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The first investigation of sperm flagellar morphology was begun in 1888, by German cytologist Ballowitz, who observed using light microscopy and mordant stains that a rooster sperm flagellum could be splayed into as many as 11, longitudinal fibrils. About 60 years later, Grigg and Hodge in 1949 and a year later Manton and Clarke observed these 11 fibers in splayed flagella by electron microscopy (EM) ; these investigators proposed that two thinner fibers were surrounded by nine thicker outer fibers. In 1952, using advancements in fixation, embedding, and ultramicrotomy, Fawcett and Porter proved by EM thin sections that the core of epithelial cilia within the ciliary membrane consisted of nine doublet microtubules surrounding two central, singlet microtubules (i.e., the “central pair microtubule apparatus”), and hence the term, the “9 + 2” axonema.
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An injectable form of glucagon may be part of first aid in cases of low blood sugar when the person is unconscious or for other reasons cannot take glucose orally or by intravenous. The glucagon is given by intramuscular, intravenous or subcutaneous injection, and quickly raises blood glucose levels. To use the injectable form, it must be reconstituted prior to use, a step that requires a sterile diluent to be injected into a vial containing powdered glucagon, because the hormone is highly unstable when dissolved in solution. When dissolved in a fluid state, glucagon can form amyloid fibrils, or tightly woven chains of proteins made up of the individual glucagon peptides, and once glucagon begins to fibrilize, it becomes useless when injected, as the glucagon cannot be absorbed and used by the body.
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At the beginning of his career, Oschkinat worked in the field of solution-state NMR, and made fundamental contributions to establish the role of multidimensional NMR spectroscopy in structural biology. After using solution-state NMR spectroscopy to determine three-dimensional structures of soluble proteins such as the pleckstrin homology domain and the WW domain, characterise protein–protein interactions involving the latter, with applications in fragment-based drug discovery, he moved on to focus on the investigation of biological systems by solid-state NMR (ssNMR) with magic angle spinning. His group was the first to solve a protein structure using ssNMR; the structure solved was that of a microcrystalline preparation of a SH3 domain. Since 2005, his research group investigates complex biomolecular systems such as membrane proteins within the native lipid environment, amyloid fibrils, and oligomers.
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However, a 1999 study of Amanita specimens in Japanese herbaria concluded that they were closely related but distinct species, due to differences in spore shape and in the microstructure of the volval remnants. Another similar species, A. magniverrucata, is differentiated from A. abrupta by a number of characteristics: the universal veil is clearly separated from the flesh of the cap; the volval warts disappear more quickly because the surface of the cap cuticle gelatinizes; the partial veil is more persistent; the spores are smaller and roughly spherical; on the underside of the partial veil, the stem has surface fibrils that are drawn upward so as to somewhat resemble a cortina (a cobweb-like protective covering over the immature spore bearing surfaces); A. magniverrucata has a known distribution limited to the south western coast of North America.
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TRACE image of a coronal arcade Wave and oscillatory phenomena are observed in the hot plasma of the corona mainly in EUV, optical and microwave bands with a number of spaceborne and ground-based instruments, e.g. the Solar and Heliospheric Observatory (SOHO), the Transition Region and Coronal Explorer (TRACE), the Nobeyama Radioheliograph (NoRH, see the Nobeyama radio observatory). Phenomenologically, researchers distinguish between compressible waves in polar plumes and in legs of large coronal loops, flare-generated transverse oscillations of loops, acoustic oscillations of loops, propagating kink waves in loops and in structures above arcades (an arcade being a close collection of loops in a cylindrical structure, see image to right), sausage oscillations of flaring loops, and oscillations of prominences and fibrils (see solar prominence), and this list is continuously updated. Coronal seismology is one of the aims of the Atmospheric Imaging Assembly (AIA) instrument on the Solar Dynamics Observatory (SDO) mission.
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The presenilins are components of a proteolytic complex involved in APP processing and degradation. Although amyloid beta monomers are harmless, they undergo a dramatic conformational change at sufficiently high concentration to form a beta sheet-rich tertiary structure that aggregates to form amyloid fibrils that deposit outside neurons in dense formations known as senile plaques or neuritic plaques, in less dense aggregates as diffuse plaques, and sometimes in the walls of small blood vessels in the brain in a process called amyloid angiopathy or congophilic angiopathy. AD is also considered a tauopathy due to abnormal aggregation of the tau protein, a microtubule-associated protein expressed in neurons that normally acts to stabilize microtubules in the cell cytoskeleton. Like most microtubule-associated proteins, tau is normally regulated by phosphorylation; however, in AD patients, hyperphosphorylated tau accumulates as paired helical filaments that in turn aggregate into masses inside nerve cell bodies known as neurofibrillary tangles and as dystrophic neurites associated with amyloid plaques.
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Like most proteins PrP can exist in two forms, one major and one minor, an alpha helix structure and a beta-pleated sheet structure respectively, that are balanced during nearly all conditions, but with dominance granted to the stable helix form. In certain instances, it may be possible for two beta forms to contact each other at the same time, and in this case the pair can form bonds that successfully stabilize the beta forms thermodynamically and allowing these structures to remain. This is termed the “seed” of polymerization as from this point the continued interaction, or recruitment, amongst the beta forms is increased perpetually, since there is a constant presence of stable beta forms, as well as the fact that beta forms, or beta-pleated sheets, have a greater number of reactive nucleation sites. This progression forms extended fibrils slowly over time that will then cause localized cytopathology, resulting in the characteristic sites of cell degradation or “sponginess”.
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Because of their antiquity, an unexpected exception to the alteration of an organism's tissues by chemical reduction of the complex organic molecules during fossilization has been the discovery of soft tissue in dinosaur fossils, including blood vessels, and the isolation of proteins and evidence for DNA fragments. In 2014, Mary Schweitzer and her colleagues reported the presence of iron particles (goethite-aFeO(OH)) associated with soft tissues recovered from dinosaur fossils. Based on various experiments that studied the interaction of iron in haemoglobin with blood vessel tissue they proposed that solution hypoxia coupled with iron chelation enhances the stability and preservation of soft tissue and provides the basis for an explanation for the unforeseen preservation of fossil soft tissues. However, a slightly older study based on eight taxa ranging in time from the Devonian to the Jurassic found that reasonably well-preserved fibrils that probably represent collagen were preserved in all these fossils and that the quality of preservation depended mostly on the arrangement of the collagen fibers, with tight packing favoring good preservation.
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Neither is known much about the mechanism of the protein misfolding nor its kinetics. Using the known structure of PrPc and the results of the in vitro and in vivo studies described below, Folding@home could be valuable in elucidating how PrPSc is formed and how the infectious protein arrange themselves to form fibrils and amyloid like plaques, bypassing the requirement to purify PrPSc or dissolve the aggregates. The PrPc has been enzymatically dissociated from the membrane and purified, its structure studied using structure characterization techniques such as NMR spectroscopy and X-ray crystallography. Post- translational PrPc has 231 amino acids (aa) in murine. The molecule consists of a long and unstructured amino terminal region spanning up to aa residue 121 and a structured carboxy terminal domain. This globular domain harbours two short sheet-forming anti-parallel β-strands (aa 128 to 130 and aa 160 to 162 in murine PrPc) and three α-helices (helix I: aa 143 to 153; helix II: aa 171 to 192; helix III: aa 199 to 226 in murine PrPc), Helices II and III are anti- parallel orientated and connected by a short loop.
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These include experiments showing that the translation of a vibrating body causes it to emit waves differing in length from those produced by the same vibrating body when stationary; a method of detecting the phases of vibration in the air surrounding a sounding body, leading to his invention of the topophone; mode of measuring the wavelengths and velocities of sound in gases, resulting in the invention of an acoustic pyrometer; the determination of relative intensities of sound; five new methods of sonorous analysis for the decomposition of a compound sound into its elementary tones; the discovery that the fibrils of the antennae of the male mosquito vibrate sympathetically to notes which have the range of pitch of the sounds given out by the female mosquito; and the determination of the laws of vibration of tuning forks, especially in the direction of the bearing of these laws on the action of the chronoscopes that are used in determining the velocities of projectiles. Mayer received the degree of Ph.D. from Pennsylvania College in 1866. He was a member of scientific societies, and in 1872 was elected to the National Academy of Sciences.
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The cap of Amanita umbrinolutea is usually free of volval remnants, 45 – 90 mm wide, at first conico-paraboloid, then somewhat campanulate to convex and finally planar, umbonate, with a strongly striate margin (margins occupying around 25 - 35% of the whole cap's radius). The cap has a distinctive pattern of color, often dark in the center, then pale, then dark over the inner edges of the lamellae and on the ridges between the marginal striations and at other times pallid in the center, but also strongly zonate; intensity of pigmentation is variable, with the center ranging from umber to grayish umber-brown to beige or pale grayish brown even within a single collection. The gills are free, crowded, off-white to sordid pale cream in mass, and up to 6 mm (0.6 cm) broad; the short gills are truncate, of varying length, scattered and unevenly distributed. The stem is 115 - 185 × 6 – 11 mm, pale cream to pale beige or isabella color or pale grayish brown, with a faint appressed zigzag girdles of fibrils, with a fleshy membranous sack-like volva at the base.
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The ion channel hypothesis of Alzheimer’s disease (AD), also known as the channel hypothesis or the amyloid beta ion channel hypothesis, is a more recent variant of the amyloid hypothesis of AD, which identifies amyloid beta (Aβ) as the underlying cause of neurotoxicity seen in AD. While the traditional formulation of the amyloid hypothesis pinpoints insoluble, fibrillar aggregates of Aβ as the basis of disruption of calcium ion homeostasis and subsequent apoptosis in AD, the ion channel hypothesis in 1993 introduced the possibility of an ion-channel-forming oligomer of soluble, non- fibrillar Aβ as the cytotoxic species allowing unregulated calcium influx into neurons in AD. The ion channel hypothesis is broadly supported as an explanation for the calcium ion influx that disrupts calcium ion homeostasis and induces apoptosis in neurons. Because the extracellular deposition of Aβ fibrils in senile plaques is not sufficient to predict risk or onset of AD, and clinical trials of drugs that target the Aβ fibrillization process have largely failed, the ion channel hypothesis provides novel molecular targets for continued development of AD therapies and for better understanding of the mechanism underlying onset and progression of AD.
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