The leading causes of sports-related deaths among high school students are sudden cardiac arrest, head and neck injuries, and exertion-induced heatstroke or sickling, which occurs in athletes who carry the sickle cell trait.
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Scientists at Albert Einstein College of Medicine in New York City had recently discovered that ingesting cyanate salts could prevent the "sickling" of red blood cells that leads to the anemia and pain of sickle cell disease.
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Dr. Jackson, who is now at Howard University, thinks that while cassava consumption in the region was insufficient to protect against malaria directly, people who had two copies of the sickle cell gene still ate enough to partly avoid sickling.
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More than 90 percent of sudden deaths in sport are due to sudden cardiac arrest, exertional heat stroke, head injuries and exertional sickling, the dangerous decrease in blood flow that can occur in athletes who carry the sickle cell trait, the authors write.
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The drug, known chemically as voxelotor, works by preventing red blood cells from sickling, a deformation that restricts flow of oxygen in blood vessels, leading to severe pain and organ damage Its approval comes three months ahead of the FDA target date for such a decision, and just over a week after Novartis AG's sickle cell drug, Adakveo, won U.S. regulatory clearance.
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Acute chest syndrome is often precipitated by a lung infection, and the resulting inflammation and loss of oxygen saturation leads to further sickling of red cells, thus exacerbating pulmonary and systemic hypoxemia, sickling, and vaso-occlusion.
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Scanning electron micrograph showing a mixture of red blood cells, some with round normal morphology, some with mild sickling showing elongation and bending The loss of red blood cell elasticity is central to the pathophysiology of sickle cell disease. Normal red blood cells are quite elastic and have a biconcave disc shape, which allows the cells to deform to pass through capillaries. In sickle cell disease, low oxygen tension promotes red blood cell sickling and repeated episodes of sickling damage the cell membrane and decrease the cell's elasticity. These cells fail to return to normal shape when normal oxygen tension is restored.
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The terms "sickle cell crisis" or "sickling crisis" may be used to describe several independent acute conditions occurring in patients with SCD, which results in anaemia and crises that could be of many types, including the vaso-occlusive crisis, aplastic crisis, sequestration crisis, haemolytic crisis, and others. Most episodes of sickle cell crises last between five and seven days. "Although infection, dehydration, and acidosis (all of which favor sickling) can act as triggers, in most instances, no predisposing cause is identified."Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009-05-28).
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Sickle cell retinopathy is a major ocular complication of the sickle cell disease (SCD) which causes permanent loss of vision. Retinopathy can occur in sickling hemoglobinopathies like sickle cell disease, sickle cell C disease, and sickle cell thalassaemia disease.
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The slow blood flow in the straight arterioles makes them a likely location of thrombosis from thrombophilia, or tissue loss due to red blood cell sickling in sickle cell disease. Ischemia that results may lead to renal papillary necrosis.
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Sickle cell nephropathy is a type of nephropathy associated with sickle cell disease which causes kidney complications as a result of sickling of red blood cells in the small blood vessels. The hypertonic and relatively hypoxic environment of the renal medulla, coupled with the slow blood flow in the vasa recta, favors sickling of red blood cells, with resultant local infarction (papillary necrosis). Functional tubule defects in patients with sickle cell disease are likely the result of partial ischemic injury to the renal tubules. Also the sickle cell disease in young patients is characterized by renal hyperperfusion, glomerular hypertrophy, and glomerular hyperfiltration.
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The sickling reaction is reversible after re-oxygenating the hemoglobin, therefore, red blood cells can go through cycles of sickling and unsickling depending on the concentration of oxygen present in the bloodstream. Red blood cells that are sickle-shaped lack flexibility and stick to the walls of blood vessels decreasing or stopping the flow of oxygen to nearby tissues. This decrease in oxygen to the tissues cause vaso-occlusive crisis which presents itself in muscle pain and injury to tissues. Some symptoms of sickle cell anemia include fever, fatigue from anemia, swelling of the hands and feet, stroke, and organ failure.
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To prevent blindness due to sickle cell retinopathy, complete ophthalmic examination twice a year is recommended for all sickle cell patients. Since the use of carbonic anhydrase inhibitors increase the chance of sickling and vascular occlusions, its use is contraindicated in sickle cell patients.
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It can be effective in treating chronic paronychia. The preferred treatment of tinea infections is therefore with clotrimazole monotherapy. Topical and oral clotrimazole can be used in both adults and children. Additionally, clotrimazole may be used to treat the sickling of cells (related to sickle cell anemia).
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The leading causes of death in youth sports are sudden cardiac arrest, concussion, heat illness and external sickling. Cardiac-related deaths are usually due to an undiagnosed cardiovascular disorder.Brion, R. “Sport-Related Sudden Death and Its Prevention.” Bulletin de l’Académie Nationale de Médecine 194.7 (2010): 1237-47. Abstract. Print.
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Sometimes sports injuries can be so severe as to result in actual death. Over the past year, 48 youths died from sports injuries. The leading causes of death in youth sports are sudden cardiac arrest, concussion, heat illness and external sickling. Cardiac-related deaths are usually due to an undiagnosed cardiovascular disorder.
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In general on alkaline electrophoresis in order of increasing mobility are hemoglobins A2, E=O=C, G=D=S=Lepore, F, A, K, J, Bart's, N, I, and H. In general a sickling test (sodium bisulfite) is performed on abnormal hemoglobins migrating in the S location to see if the red cells precipitate in solution.
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The most frequent cause of autosplenectomy is sickle cell anemia which causes progressive splenic hypofunction over time. Increased deoxygenation causes sickling of red blood cells, which adhere to the spleen wall and splenic macrophages causing ischemia. This ischemia can result in splenic sequestration, where large amounts of blood pool in the spleen but do not flow within vasculature. This lack of blood flow can cause atrophy in the spleen and can lead to autosplenectomy.
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Compound heterozygotes with sickle-hemoglobin E disease result when the gene of hemoglobin E is inherited from one parent and the gene for hemoglobin S from the other. As the amount of fetal hemoglobin decreases and hemoglobin S increases, a mild hemolytic anemia appears in the early stage of development. Patients with this disease experience some of the symptoms of sickle cell anemia, including mild-moderate anemia, increased risk of infection, and painful sickling crises.
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Ballet training places great emphasis on ballet technique because precise technique is an essential element of the aesthetics of ballet performance. Ballet technique is drilled into ballet students to develop the desired aesthetics and to prevent injury. For example, students are taught to avoid sickling of the foot, which is an undesirable aesthetic and can result in ankle injuries when performing en pointe. The ballet barre is a tool for learning ballet technique.
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One of the earliest clinical manifestations is dactylitis, presenting as early as six months of age, and may occur in children with sickle cell trait. The crisis can last up to a month. Given that pneumonia and sickling in the lung can both produce symptoms of acute chest syndrome, the patient is treated for both conditions. It can be triggered by painful crisis, respiratory infection, bone-marrow embolisation, or possibly by atelectasis, opiate administration, or surgery.
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As of 2009, there have been approximately 120 reported cases of renal medullary carcinoma. In every instance except for one, the patients were positive for cell sickling. Wilms' tumor, the most common renal tumor of childhood, is responsible for 6-7% of childhood cancer whereas all remaining primary renal tumors (among which is included renal medullary carcinoma) collectively account for less than 1% of all childhood cancer and less than 10% of primary kidney tumors in childhood.
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A few examples are priapism, stroke and systemic blood pressure. As hemoglobin F are only produced by some red blood cells, in different quantities, only a subpopulation of cells are protected against sickling. It could be that the symptoms that high hemoglobin F doesn't prevent are quite sensitive to the rupture of the sickled non-F cells. Hydroxyurea is a chemical that promotes the production of fetal hemoglobin and reduces the premature rupturing of red blood cells.
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Individuals with sickle cell–hemoglobin C (HbSC), have inherited the gene for sickle cell disease (HbS) from one parent and the gene for hemoglobin C disease (HbC) from the other parent. Since HbC does not polymerize as readily as HbS, there is less sickling in most cases. There are fewer acute vaso-occlusive events and therefore in some cases fewer sickle cell crises. The peripheral smear demonstrates mostly target cells and only a few sickle cells.
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John Sickling was a priest and academic in the late fifteenth and early sixteenth centuries.Alumni Cantabrigienses: A Biographical List of All Known Students, Graduates and Holders of Office at the University of Cambridge, from the Earliest Times to 1900, John Venn/John Archibald Venn Cambridge University Press > (10 volumes 1922 to 1953) Part I. 1209-1751 Vol. iv. Saal – Zuinglius, (1927) p74 Sicking was educated at Christ's College, Cambridge, graduating B.A. in 1482 and MA in 1485. He was Fellow of Christ's from 1485 to 1505.
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In HbS, the complete blood count reveals haemoglobin levels in the range of 6–8 g/dl with a high reticulocyte count (as the bone marrow compensates for the destruction of sickled cells by producing more red blood cells). In other forms of sickle cell disease, Hb levels tend to be higher. A blood film may show features of hyposplenism (target cells and Howell-Jolly bodies). Sickling of the red blood cells, on a blood film, can be induced by the addition of sodium metabisulfite.
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The presence of sickle haemoglobin can also be demonstrated with the "sickle solubility test". A mixture of haemoglobin S (HbS) in a reducing solution (such as sodium dithionite) gives a turbid appearance, whereas normal Hb gives a clear solution. Abnormal haemoglobin forms can be detected on haemoglobin electrophoresis, a form of gel electrophoresis on which the various types of haemoglobin move at varying speeds. Sickle cell haemoglobin (HgbS) and haemoglobin C with sickling (HgbSC)—the two most common forms—can be identified from there.
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Hemoglobin c (abbreviated as HbC) is an abnormal hemoglobin in which glutamic acid residue at the 6th position of the β-globin chain is replaced with a lysine residue due to a point mutation in the HBB gene. It produces sickle cell trait but not the disease, as it causes only mild sickling of the RBCs. Thus, it is the least dangerous among sickle cell trait-producing hemoglobins such as HbS and HbO. HbC was discovered by Harvey Itano and James V. Neel in 1950 from two African-American families.
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Papillary infarcts, demonstrable radiographically in 50% of patients with sickle trait, lead to an increased risk of bacterial infection in the scarred kidney tissues and functional tubule abnormalities. The presence of visible blood in the urine without pain occurs with a higher frequency in sickle trait than in sickle cell disease and likely results from infarctive episodes in the renal medulla. Functional tubule abnormalities such as nephrogenic diabetes insipidus result from marked reduction in vasa recta blood flow, combined with ischemic tubule injury. This concentrating defect places these patients at increased risk of dehydration and, hence, sickling crises.
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In people heterozygous for HbS (carriers of sickling haemoglobin), the polymerisation problems are minor because the normal allele is able to produce half of the haemoglobin. In people homozygous for HbS, the presence of long-chain polymers of HbS distort the shape of the red blood cell from a smooth, doughnut-like shape to ragged and full of spikes, making it fragile and susceptible to breaking within capillaries. Carriers have symptoms only if they are deprived of oxygen (for example, while climbing a mountain) or while severely dehydrated. HBB gene (responsible for sickle cell anaemia) is located on the short (p) arm of chromosome 11 at position 15.5.
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Linus Pauling was a prominent physical chemist at the California Institute of Technology (a main focal point of Warren Weaver's efforts to promote what he called "molecular biology" through Rockefeller Foundation grants). In the mid-1930s, Pauling turned his attention to the physical and chemical nature of hemoglobin. In 1946, he set graduate student Harvey Itano (who had been previously trained as a physician) the task of finding differences in hemoglobin that might explain sickle cell disease. After failing to find any differences in size, weight, or acid-base titration (despite the advanced instruments available at Caltech), Itano found that oxygen could inhibit the sickling process while various reducing agents could speed it up; this was the basis of Pauling and Itano's first publication on the disease.
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A newer theory suggests that the selective pressure on the CCR5 Delta 32 mutation was caused by smallpox instead of the bubonic plague. Malaria resistance: An example of a harmful mutation is sickle-cell disease, a blood disorder in which the body produces an abnormal type of the oxygen- carrying substance hemoglobin in the red blood cells. One-third of all indigenous inhabitants of Sub-Saharan Africa carry the allele, because, in areas where malaria is common, there is a survival value in carrying only a single sickle-cell allele (sickle cell trait). Those with only one of the two alleles of the sickle-cell disease are more resistant to malaria, since the infestation of the malaria Plasmodium is halted by the sickling of the cells that it infests.
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Sickle cell trait describes a condition in which a person has one abnormal allele of the hemoglobin beta gene (is heterozygous), but does not display the severe symptoms of sickle cell disease that occur in a person who has two copies of that allele (is homozygous). Those who are heterozygous for the sickle cell allele produce both normal and abnormal hemoglobin (the two alleles are codominant with respect to the actual concentration of hemoglobin in the circulating cells). Sickle cell disease is a blood disorder wherein there is a single amino acid substitution in the hemoglobin protein of the red blood cells, which causes these cells to assume a sickle shape, especially when under low oxygen tension. Sickling and sickle cell disease also confer some resistance to malaria parasitization of red blood cells, so that individuals with sickle-cell trait (heterozygotes) have a selective advantage in environments where malaria is present.
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His work has established that hemoglobin in red blood cells not only carries oxygen and carbon dioxide to support cellular respiration, but also carries NO as an S-nitrosothiol that is critical for autoregulation of blood flow through tissue microcapillaries. Thus, the respiratory cycle may be viewed as a 3-gas system (O2/NO/CO2) where oxygen delivery to tissue by hemoglobin is linked to oxygen-dependent R- and T-state conformational changes of hemoglobin to load NO on cysteine 93 of beta-globin in high oxygen and to deliver this SNO to dilate blood vessels in low oxygen. The SNO-hemoglobin content of RBCs is low in multiple clinical conditions, including pulmonary hypertention, COPD, vascular disease and sickle cell disease, which impairs vasodilation by RBCs. For example, the ability of hemoglobin to undergo conformation-dependent S-nitrosylation is impaired in red blood cells from sickle cell disease patients, impairing vasodilation (subserving microcirculatory blood flow and tissue oxygen delivery) beyond that caused by red blood cell sickling.
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"Sickle Cell Anemia, a Molecular Disease" is a 1949 scientific paper by Linus Pauling, Harvey A. Itano, Seymour J. Singer and Ibert C. Wells that established sickle-cell anemia as a genetic disease in which affected individuals have a different form of the metalloprotein hemoglobin in their blood. The paper, published in the November 25, 1949 issue of Science, reports a difference in electrophoretic mobility between hemoglobin from healthy individuals and those with sickle-cell anemia, with those with sickle cell trait having a mixture of the two types. The paper suggests that the difference in electrophoretic mobility is probably due to a different number of ionizable amino acid residues in the protein portion of hemoglobin (which was confirmed in 1956 by Vernon Ingram), and that this change in molecular structure is responsible for the sickling process. It also reports the genetic basis for the disease, consistent with the simultaneous genealogical study by James V. Neel: those with sickle-cell anemia are homozygous for the disease gene, while heterozygous individuals exhibit the usually asymptomatic condition of sickle cell trait.
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