Cerebral blood flow , and

In other applications of CT, orally administered barium sulfate or a water-soluble iodinated CM is used to opacify the GI tract. Xenon, atomic number 54, exhibits similar x-ray absorption properties to those of iodine. It rapidly diffuses across the blood brain barrier after inhalation to saturate different tissues of brain as a function of its lipid solubility. In preliminary investigations (99), xenon gas inhalation prior to brain CT has provided useful information for evaluations of local cerebral blood flow and cerebral tissue abnormalities. Xenon exhibits an anesthetic effect at high concentrations but otherwise is free of physiological effects because of its nonreactive nature. 

Rempp KA, Brix G, Wenz F, Becker CR, Guckel F, Lorenz WJ. Quantification of regional cerebral blood flow and volume with dynamic susceptibility contrast-enhanced MR imaging. Radiology 1994 193 637-641. 

Sorensen AG, Copen WA, 0stergaard L, Buonanno FS, Gonzalez RG, Rordorf G, Rosen BR, Schwamm LH, Weisskoff RM, Koroshetz WJ. Hyperacute stroke simultaneous measurement of relative cerebral blood volume, relative cerebral blood flow, and mean tissue transit time. Radiology 1999 210 519-527. 

Grandin CB, Duprez TP, Smith AM, Mataigne F, Peeters A, Oppenheim C, Cosnard G. Usefulness of magnetic resonance-derived quantitative measurements of cerebral blood flow and volume in prediction of infarct growth in hyperacute stroke. Stroke. 2001 32 1147-1153. 

KawaiN, Keep RE, Betz AL. Effects of hyperglycemia on cerebral blood flow and edema formation after carotid artery occlusion in Fischer 344 rats. Acta Neurochir Suppl 1997 70 34-36. 

Hartman A, Dettmers C, Schott H, Beyenburg S. Cerebral blood flow and rheologic alterations by hyperosmolar therapy in patients with brain oedema. Acta Neurochir Suppl (Wein) 1990 51 168-169. 

In the face of the failure of rational approaches in the treatment of AzD it is perhaps not surprising that there have been many less rational ones. These include the use of vasodilators and nootropics. The former, such as hydergine, a mixture of ergot alkaloids, are intended to increase cerebral blood flow and neuronal metabolism despite some reduction in blood pressure, while the latter, like piracetam, are metabolic stimulants that increase cerebral metabolism and ATP production. Neither are of proven value in AzD. 

Blood tends to pool in the highly distensible veins. Furthermore, the excessive filtration of fluid out of the capillaries and into the tissues that occurs causes edema or swelling of the ankles and feet. As a result, VR and therefore CO are decreased, leading to a decrease in MAP. This fall in MAP can cause a decrease in cerebral blood flow and, possibly, syncope (fainting). 

Kennedy, C. Sokoloff, L. (1957). An adaptation of the nitrous oxide method to the study of the cerebral circulation in children normal values for cerebral blood flow and cerebral metabolic rate during childhood. J. Clin. Invest. 36, 1130-7. 

Kety SS (1956). Human cerebral blood flow and oxygen consumption as related to aging. Journal of Chronic Disease, 3, 478-486. 

Cerebral metabolic rate declines from developmental levels and plateaus after maturation. Reliable quantitative data on the changes in cerebral circulation and metabolism in humans from the middle of the first decade of life to old age have been reported [2,39,44]. By 6 years of age, cerebral blood flow and oxygen consumption already have attained high rates, and they decline thereafter to the rates of normal young adulthood [45]. Oxygen is utilized in the brain almost entirely for the oxidation of carbohydrates [46]. The equation for the complete oxidation of glucose is ... 

Linde, R., Schmalbruch, I. K., Paulson, O. B. etal. The Kety-Schmidt technique for repeated measurements of global cerebral blood flow and metabolism in the conscious rat. Acta Physiol. Scand. 165 395-401,1999. 

Nakao, Y., Itoh, Y., Kuang, T. Y. etal. Effects of anesthesia on functional activation of cerebral blood flow and metabolism. Proc. Natl Acad. Sci. U.S.A. 98 7593-7598, 2001. 

Settergren, G., Lindblad, B. S. and Persson, B. Cerebral blood flow and exchange of oxygen, glucose, ketone bodies, lactate, pyruvate and amino acids in infants. Acta Paediatr. 

Takahashi, T., Shirane, R., Sato, S. etal. Developmental changes of cerebral blood flow and oxygen metabolism in children. Am. J. Neuroradiol. 20 917-922,1999. 

Rodriguez, G., Cogorno, P., Gris, A. et al. Regional cerebral blood flow and anxiety a correlation study in neuro-logically normal patients. /. Cereb. Blood Flow Metab, 9 410-416,1989. 

Shiraishi, H., Chang, C. C., Kanno, H. and Yamamoto, I. The relationship between cerebral blood flow and cognitive function in patients with brain insult of various etiology. /. Clin. Neurosci. 11 138-141, 2004. 

The final result of both thrombus formation and embolism is arterial occlusion, decreasing cerebral blood flow and causing ischemia and ultimately infarction distal to the occlusion. 

Elevated blood pressure should remain untreated in the acute period (first 7 days) after ischemic stroke because of the risk of decreasing cerebral blood flow and worsening symptoms. The pressure should be lowered if it exceeds 220/120 mm Hg or there is evidence of aortic dissection, acute myocardial infarction, pulmonary edema, or hypertensive encephalopathy. If blood pressure is treated in the acute phase, short-acting parenteral agents (e.g., labetalol, nicardipine, nitroprusside) are preferred. 

Neuromuscular symptoms include altered mental status, abnormal behavior, seizures, stupor, and coma. Hypercapnia can mimic a stroke or CNS tumor by producing headache, papilledema, focal paresis, and abnormal reflexes. CNS symptoms are caused by increased cerebral blood flow and are variable, depending in part on the acuity of onset. 

Vincamine (91) is the major alkaloid of V. minor, a plant used against headache and vertigo. It exerts a sedative CNS action and produces a fall in blood pressure. The principal activity is a moderate cerebral vasodilation. Clinical studies have demonstrated that i.v. administration of 91 to humans reduces the arterial blood pressure and increases cerebral blood flow and oxygen consumption. The improved cerebral hemodynamic conditions significantly and positively affect the state of patients with advanced arteriosclerosis with beneficial effects on memory, concentration, and behavior. It has thereafter been introduced under several trade names as a pharmaceutical in many European countries (232). Vobasine (32) has been widely studied it exhibits a weak CNS depressive, analgesic, and antipyretic action (21). 

M. Cope and D.T. Delpy. System for long-term measurement of cerebral blood flow and tissue oxygenation on newborn infants by infra-red transillumination. Medical and Biological Engineering and Computing, 28 289-294, 1988. 

C. E. Elwell, H. Owen-Reece, J. S. Wyatt, M. Cope, E. O. Reynolds, and D. T. Delpy. Influence of respiration and changes in expiratory pressure on cerebral hemoglobin concentration measured by near infrared spectroscopy. Journal of Cerebral Blood Flow and Metabolism, 16 353-357, 1996. 

H. R. Heekeren, M. Kohl, H. Obrig, R. Wenzel, W. v. Pannwitz, S. Matcher, U. Dirnagl, C. E. Cooper, and A. Villranger. Noninvasive assessment of changes in cytochrom-c-oxidase oxidation in human subjects during visual stimulation. Journal of Cerebral Blood Flow and Metabolism, 19 592-603, 1999. 

H. Obrig and A. Villringer. Beyond the visible-imaging the human brain with light. Journal of Cerebral Blood Flow and Metabolism, 23 1-18, 2003. 

Klimmek R, Roddewig C, Fladerer H, et al. 1983. Effects of 4-dimethylaminophenol, Co2EDTA, or NaN02 on cerebral blood flow and sinus blood homeostasis of dogs in connection with acute cyanide poisoning. Toxicology 26 143-154. 

The inhibition of sympathetic tone to the venous system (capacitance vessels) results in increased pooling of blood in the venous vascular bed with consequent decreased venous return to the heart and decreased cardiac output. This phenomenon is more pronounced in upright positions because of the effect of gravity. The hemodynamic effects of ganglionic blockers include decreases in cardiac output, renal blood flow, cerebral blood flow and orthostatic hypotension(20,21). 

Senile dementia is another type of mental disease for which physical and chemical causes, aside from aging itself, are known. Cerebral arteriosclerosis is a every common accompaniment, and this is known to decrease the cerebral blood flow and the total metabolism of the brain. 11 This itself is enough to account for the deranged metabolism and the accompanying deranged mental functions. 

Cerebral blood flow and glucose metabolism Nicotine increases cerebral blood flow (Hara et al. 1993 Yokoi et al. 1993). Functional MRI of smokers who were administered intravenous nicotine shows increases of cerebral blood flow in several areas of the brain. Corresponding to feelings of mood elevation, nicotine activates the nucleus accumbens, amygdala, cingulate cortex, and frontal lobes. This activation is very consistent with functional systems subserving arousal and reinforcement. 

Cerebral blood flow and glucose utilization Local cerebral blood flow is increased by ginkgo extract in multiple regions of the brain in conscious rats (Kriegistein et al. 1986). Ginkgo increases cerebral blood flow in humans as well (Heiss and Podreka 1978). 

---