Blood flow, brain

Blood pressure lowering drugs reduce risk of stroke (and myocardial infarction and death) in middle aged patients and even better in the elderly (NNT 86 vs 29 over 5 years) (Pearce 1998). However in the elderly the dysfunction in the autoregulation of brain blood flow, salt and fluids, and increased sensitivity to adverse effects and symptoms may change the picture. 

Ibrahim et al. 1963). Aiken and Braitman (1989) determined that cyanide has a direct effect on neurons not mediated by its inhibition of metabolism. Consistent with the view that cyanide toxicity is due to the inability of tissue to utilize oxygen is a report that in cyanide-intoxicated rats, arterial p02 levels rose, while carbon dioxide levels fell (Brierley et al. 1976). The authors suggested that the low levels of carbon dioxide may have led to vasoconstriction and reduction in brain blood flow therefore, brain damage may have been due to both histotoxic and anoxic effects. Partial remyelination after cessation of exposure has been reported, but it is apparent that this process, unlike that in the peripheral nervous system, is slow and incomplete (Hirano et al. 1968). The topographic selectivity of cyanide-induced encephalopathy may be related to the depth of acute intoxication and distribution of blood flow, which may result in selected regions of vascular insufficiency (Levine 1969). 

CDP-choline Choline donor Endogenous nucleotide APOE Retrospective Prospective Genotype dependent Genotype dependent Cognition Brain blood flow Brain mapping Bio-chemistry Replicated in two studies... 

Brain blood flow Brain mapping Immune markers Cognition... 

BRAIN BLOOD FLOW SALIVARY GLAND BLOOD FLOW... 

It is used for arterial hypertension, chronic, stable angina pectoris, preventing angina pectoris, and for ischemic-type abnormalities of brain blood flow. Synonyms of this drug are nerdipina, carden, and others. 

Another class of commonly used radiopharmaceuticals measure regional brain blood flow. In PET, [ 0]H20 is used as a radiopharmaceutical and in SPECT, [99mjc]HMPAQ, [99> Tc]ECD, or [ 9 ] /]p are used. Studies of patients with AD with the use of these radiopharmaceuticals have been thoroughly reviewed elsewhere [e,g, 34-36] and it is out of the scope of this chapter to further discuss these studies. 

The meta-orientation of the two methoxyl groups does, however, greatly increase the susceptibility of the aromatic ring to electrophilic attack. This is one of the three possible meta-dimethoxy substituted amphetamines, and it is the best studied one in the pursuit of potential radio-halogen substituted brain blood-flow agents. This strategy is discussed under 1DNNA the other two meta-compounds are discussed under 3,4-DMA. 

Both the 2,6- and the 3,5-isomers, as the N,N-dimethyl homologues, have been looked at as potential radio-halogen recipients in the search for positron-emitting brain blood-flow indicators, as discussed in the recipe for IDNNA. Both were made from the appropriate nitrostyrene via the corresponding phenylacetone. 

Several of the alpha-ethyl analogues of ARIADNE were N,N-dialky lated, and were target compounds for halogenation with radio-iodine or radio-fluorine, for evaluation as potential brain blood-flow indicators. In these studies, all examples followed a common flow diagram. The reaction of the appropriate benzaldehyde... 

A brief comment on two of the N,N-dimethylhomologues of methoxy-amphetamine. One was 4-methoxy-N,N-dimethylamphetamine, 4-MNNA. This material, made by the reductive animation of 4-methoxyphenylacctone with dimethylamine, was a colorless oil, which distilled at 70-85 °C at 0.3 mm/Hg. The corresponding 2-methoxy-N,N-dimethylamphetamine was similarly made. 2-MNNA was also a colorless oil and had the same bp. Both of them were fluorinated with l8F labelled acetyl hypofluorite (3% and 6% yields respectively) but neither of them was pursued any further in the search for a brain blood flow indicator. 

Henry, T., Bakay, R., Pennell, P., Epstein, C., Votaw, J. (2004). Brain blood-flow alterations induced by therapeutic vagus nerve stimulation in partial epilepsy II. Prolonged effects at high and low levels of stimulation. Epilepsia, 45, 1064-1070. 

The brain uses a substantial proportion of body oxygen and there is a generous blood supply to the brain from the carotid and vertebral arteries. Interruption of brain blood flow for more than a very short time causes neuronal damage and ultimately cell death. Cerebral blood flow is normally controlled by autoregulation. 

Surgeons are concerned with brain blood flow to patients undergoing cardiopulmonary bypass surgery. An intensive study by Chow et al. was conducted where blood flows were restricted to patients from age 2 weeks to over 20 years [48]. Near-IR was used to correlate blood flow rate with NIR spectra of the brain. Flows of 0.6, 1.2, and 2.4 L/mVmin-1 were used. Their results showed that flow was related to mean arterial pressure, but did not correspond to pulsatility. This was interesting in that pulse rate is often used as a diagnostic to assure sufficient blood flow to the brain during surgery. 

Raichle ME, Martin WR, Herscovitch P, Mintun MA, Markham J (1983) Brain blood flow measured with intravenous H2(15)O. IL Implementation and validation. J Nucl Med 24 790-798... 

Brown CG, Werman HA, Davis EA, et al. Comparative effect of graded doses of epinephrine on regional brain blood flow during CPR in a swine model. Ann Emerg Med 1986 15 1138-1144. 

In rabbits, an increase in plasma renin activity was also observed in acute testing with intravenously administered Aviptadil. Brain blood flow was decreased, and there was an increase in heart and pancreatic blood flow which was comparable to the effects seen in dogs [10-12]. 

Semple WE, Goyer P, McCormick R. Preliminary report brain blood flow using PET in patients with posttraumatic stress disorder and substance abuse histories. Biol Psychiatry 1993 34 115-118. 

When normal subjects were shown film clips that provoked the emotions of happiness, fear, or disgust, oxygen-15 water studies of regional brain blood flow showed increased neuronal blood flow in the primary and secondary visual cortex, as well as in limbic regions [Paradiso et al.. Am. J. Psychiatry 154(3) 384-389,1997]. 

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