Metabolism cerebral

Cerebral arteriosclerosi Cerebral metabolism Cerebrocuprein Cerebrospinal fluid... 

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. 

Idebenone, an inhibitor of lipid peroxidation, was shown to prolong survival time and delay the onset of ischaemic seizures in a bilateral carotid occlusion model in rats. It is marketed in Japan as a therapy to improve cerebral metabolism and performance after a stroke (Suno and Nagaoka, 1984). Cerebral protective effects after an ischaemic insult in dogs and rabbits have been seen with the hydroxyl radical scavenger, mannitol (Meyer et al., 1987). 

Relatively few human imaging studies have evaluated the effects of marijuana or THC on metabolism or blood flow. Acute intravenous THC in both normal controls and habitual marijuana users led to increased an increased regional cerebral metabolic rate (CMR) in the cerebellum. This increase is positively correlated both with concentrations of THC in the plasma and with the intensity of the subjective sense of intoxication [5]. In a 1997 PET/[lsO]water study with 32 abusers [6], THC dose-depend-ently increased cerebral blood flow (CBF) in the frontal regions, insula... 

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. 

London, E.D., Simon, S.L., Berman, S.M. et al. Mood disturbances and regional cerebral metabolic abnormalities in recently abstinent methamphetamine abusers. Arch. Gen. Psychiatry. 61 73, 2004. 

L-acetylcarnitine is produced naturally in the CNS and indirectly stimulates acetylcholine production, as well as purportedly modulating cerebral metabolism. A study of nearly 500 geriatric patients in Italy provided evidence that L-acetylcarnitine... 

Increased cerebral metabolism increased cerebral oxygen delivery. 

The evidence cited here is only a very small sample of the vast quantity of research into putative cognitive enhancers. However, many of these compounds that have demonstrated positive effects are believed to influence cerebral metabolism, whether through increased blood flow, glucose metabolism or other indirect routes, as outlined above. Furthermore, these metabolic effects are hypothesised to be at least partly responsible for the cognitive improvements documented. Indeed, many of the putative cognitive enhancers currently available claim modes of influence (Table 14.1) that would fall in line with a metabolic model of cognitive enhancement. 

Cerebral metabolic rate increases during early development 535... 

Cerebral metabolic rate declines from developmental levels and plateaus after maturation 535... 

TABLE 31-2 Cerebral metabolic rates (CMR) are regionally and activity-dependent... 

The rate of blood flow in different structures of the brain reaches peak levels at different developmental stages, depending on the maturation rate of the particular structure. In structures that consist predominantly of white matter, the peaks coincide roughly with maximal rates of myelination. From these peaks, blood flow and, probably, cerebral metabolic rate decline to the levels characteristic of adulthood [2,39,44],... 

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 ... 

Kinnala, A., Suhonen-Polvi, H., Aarimaa, T. etal. Cerebral metabolic rate for glucose during the first six months of life an FDG positron emission tomography study. Arch. Dis. Child. Fetal Neonat. Ed. 74 F153-F157,1996. 

Heiss, W. D., Pawlik, G., Herholz, K. etal. Regional kinetic constants and cerebral metabolic rate for glucose in normal human volunteers determined by dynamic positron... 

Blumberg, R. M., Cady, E. B., Wigglesworth, J. S. etal. Relation between delayed impairment of cerebral metabolism and infarction following transient focal hypoxia-ischemia in the developing brain. Exp. Brain Res. 113 130-137, 1997. 

Ammonia concentrations in arterial blood of patients with liver failure rise to 0.5-1 mmol/1, in contrast to the normal range of 0.01-0.02 mmol/1. Using positron emission tomography (PET see Ch. 58), increases of the cerebral metabolic rate for ammonia (CMRA), i.e. the rate at which ammonia is taken up and metabolized by the brain, have been reported in chronic liver failure [9]. Increased CMRA in chronic liver failure is accompanied... 

FIGURE 34-3 Positron emission tomography using 13NH3 showing increased brain ammonia uptake in a patient with liver cirrhosis and mild hepatic encephalopathy. CMRA, cerebral metabolic ratio for ammonia HE, hepatic encephalopathy PS, permeability/surface area product. (With permission from reference [9].)... 

F. A Welsh (eds), Cerebral Metabolism and Neural Function. Baltimore Williams Wilkins, 1980, pp. 243-254. 

Christensen, J. D., Kaufman, M. J., Levin, J. M. et al. Abnormal cerebral metabolism in polydrug abusers during early withdrawal a 31P MR spectroscopy study. Magn. Reson. Med. 35 658-663,1996 . 

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