Some factors affecting drug distribution include regional blood flow rates, molecular size, polarity and binding to serum proteins, forming a complex. Distribution can be a serious problem at some natural barriers like the blood–brain barrier.
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The ARAS also helps mediate transitions from relaxed wakefulness to periods of high attention. There is increased regional blood flow (presumably indicating an increased measure of neuronal activity) in the midbrain reticular formation (MRF) and thalamic intralaminar nuclei during tasks requiring increased alertness and attention.
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Patients with damage to their left amygdala lesions rated fearful faces less fearful than normal subjects. Similar findings showed that regional blood flow increased in response to fear faces while decreased to euphoric faces in the left amygdala. Chimpanzees, other primates, and humans produce asymmetrical facial expressions with greater expression on the left side of the face (right hemisphere of the brain).Fernandez-Carriba, S., A. Loeches, A. Morcillo, and W.D. Hopkins.
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Farmacocinética III:Distribución Available on (in Spanish). Visited 10 January 2009 The distribution of a drug between tissues is dependent on vascular permeability, regional blood flow, cardiac output and perfusion rate of the tissue and the ability of the drug to bind tissue and plasma proteins and its lipid solubility. pH partition plays a major role as well. The drug is easily distributed in highly perfused organs such as the liver, heart and kidney.
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Contrary to popular belief, the disorder is not always caused from a lack of sexual arousal. Possible causes of the disorder include psychological and emotional factors, such as depression, anger, and stress; relationship factors, such as conflict or lack of trust; medical factors, such as depleted hormones, reduced regional blood flow, and nerve damage; and drug use. The lack of sexual arousal may be due to a general lack of sexual desire or due to a lack of sexual desire for the current partner (i.e., situational).
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The "experimental cancer metastasis assay" has some resemblance to the above method to measure regional blood flow. Groups of syngeneic and age matched mice are given intravenous injections of equal-sized aliquots of suspensions of cloned cancer cells and then after a set period of time their lungs are removed and the number of cancer metastases enumerated within each pair of lungs. If other groups of mice are injected with different cancer cell clones then the number of metastases per group will differ in accordance with the metastatic potentials of the clones. It has been long recognized that there can be considerable intraclonal variation in the numbers of metastases per mouse despite the best attempts to keep the experimental conditions within each clonal group uniform.
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This variation is larger than would be expected on the basis of a Poisson distribution of numbers of metastases per mouse in each clone and when the variance of the number of metastases per mouse was plotted against the corresponding mean a power law was found. The variance-to-mean power law for metastases was found to also hold for spontaneous murine metastases and for cases series of human metastases. Since hematogenous metastasis occurs in direct relationship to regional blood flow and videomicroscopic studies indicate that the passage and entrapment of cancer cells within the circulation appears analogous to the microsphere experiments it seemed plausible to propose that the variation in numbers of hematogenous metastases could reflect heterogeneity in regional organ blood flow. The blood flow model was based on the Tweedie compound Poisson–gamma distribution, a distribution governing a continuous random variable.
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Pilot-cosmonaut Aleksandr Serebrov described being issued and using Phenylpiracetam, as well as it being included in the Soyuz spacecraft's standard emergency medical kit, during his 197-days working in space aboard the Mir space station. He reported "the drug acts as the equalizer of the whole organism, 'combs' it(sic причесывает), completely excluding impulsiveness and irritability inevitable in the stressful conditions of space flight." Clinical trials were conducted at the Serbsky State Scientific Center for Social and Forensic Psychiatry. The Serbsky Center, Moscow Institute of Psychiatry, and Russian Center of Vegetative Pathology are reported to have confirmed the effectiveness of Phenylpiracetam(Phenytropil) describing the following effects: improvement of regional blood flow in ischemic regions of the brain, reduction of depressive and anxiety disorders, increase the resistance of brain tissue to hypoxia and toxic effects, improving concentration and mental activity, a psychoactivating(sic) effect, increase in the threshold of pain sensitivity, improvement in the quality of sleep, and an anticonvulsant action, though with the side effect of an anorexic effect in extended use.
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