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Biomedical subjects

S Lavy

Publications and source records attributed to S Lavy.

At least 19 recordsLinked to original sources
PubMed1983

Effect of exercise on cerebral circulation.

The effect of supine physical exercise on cerebral blood flow (CBF) was measured in 30 normal subjects with the 133Xe inhalation technique. The CBF measurements were correlated to changes in PCO2, heart rate, and blood pressure, and to cardiac output and right atrial pressure in 10 of the subjects who underwent Swan-Ganz catheterization. No significant change was found in CBF during physical exercise, although a marked increase in cardiac output, blood pressure, and right atrial pressure and a mild decrease in PCO2 were found. Cerebrovascular resistance increased by 38%, in contrast to a decrease of 33% in the peripheral vascular resistance. The factors that affect the mechanism of cerebrovascular autoregulation during exercise are discussed.

Adult↗
PubMed1979

Regional cerebral blood flow in patients with Parkinson's disease.

Regional cerebral blood flow (rCBF) was measured by the xenon 133 inhalation method in 60 patients with Parkinson's disease and compared with flow data obtained in 51 age-matched normal control subjects. Mean brain rCBF was significantly reduced in patients with parkinsonism (9.5%, P less than .001). The most marked and significant rCBF decreases were observed in the older patients (18.8%, P less than .001). There was no correlation between degree of rCBF reduction and duration of parkinsonism. Decreases in hemispheric mean rCBF values were similar in both hemispheres even in patients with unilateral signs. The present study provides additional evidence for involvement of the cerebral cortex in Parkinson's disease. The rCBF decline may be associated in part with high prevalence of mental impairment and cortical atrophy and with diminished cerebral metabolic rate due to brain dopamine deficiency in patients with parkinsonism.

Adult↗
PubMed1979

Transient hemiparesis: a rare manifestation of diphenylhydantoin toxicity. Report of two cases.

Among the common side effects of diphenylhydantoin (DPH) overdose, the most frequently encountered neurological signs are those of cerebellar dysfunction. Very rarely, the toxic neurological manifestations of this drug are of cerebral origin. Two patients are presented who suffered progressive hemiparesis due to DPH overdose. Both had brain surgery before DPH treatment. It is assumed that patients with some cerebral damage are liable to manifest DPH toxicity as focal neurological signs.

Adult↗
PubMed1979

Organ blood flow, cardiac output, arterial blood pressure, and vascular resistance in rats exposed to various oxygen pressures.

Blood flow in different organs, cardiac output, and arterial blood pressure were measured in unanesthetized rats under 1, 2, 3.5, 5, and 7 ATA O2, during first electrical discharge developed at 7 ATA O2 and following decompression. Brain, spinal cord, and hypophysis blood flow were reduced after 10 min of exposure to 2, 3.5, and 5 ATA O2 and were normal before and during first electrical discharge. Liver and muscle blood flow were significantly reduced under all investigated pressures, while myocardium, lung, kidney, and adrenal blood flow remained unchanged except for a significant increase in myocardium and lung blood flow under 1 ATA O2. Cardiac output was significantly decreased while arterial blood pressure was significantly decreased under all investigated pressures. The total peripheral resistance increased 36 to 81% at various oxygen pressures. These results are discussed in relation to the possible involvement of hemodynamic changes in awake animals, in the development of the adverse effects of HOP.

Adrenal Glands↗
PubMed1978

Bihemispheric decreases of regional cerebral blood flow in dementia: correlation with age-matched normal controls.

Regional cerebral blood flow (rCBF) was measured by the xenon 133 inhalation method in 20 patients with senile and presenile dementia, and values were compared with flow data obtained in a series of 44 age-matched normal controls. The rCBF was reduced in patients with both presenile and senile dementia, and the degree of decrease exceeded the age-related rCBF decline in normal subjects. Similar rCBF reductions were observed in the left and right cerebral hemispheres and in general were homogeneously distributed in the various areas. The rCBF reductions in normal aging and in dementia may be associated with similar underlying cerebral morphological changes. Our findings suggest that the greater rCBF decreases in dementia compared with the values in age-matched controls may quantitatively reflect more severe pathological alterations in the brains of patients with intellectual deterioration.

Adult↗
PubMed1978

Regional cerebral blood flow in parkinsonism. Measurement before and after levodopa.

Data from recent studies in experimental animals suggest that central dopaminergic mechanisms may be involved in regulation of the regional cerebral blood flow (rCBF) in the mammalian brain. In order to evaluate possible effects of dopaminergic stimulation on human cerebral circulation, rCBF was measured by the 133Xenon inhalation technique in 26 patients with Parkinson's disease before and after the chronic oral administration of levodopa combined with a peripheral Dopa-decarboxylase inhibitor. Treatment with levodopa did not induce significant alterations in the mean brain, mean hemispheric or regional flow values in these patients. These findings suggest that the dopaminergic system does not play an important role in modulation of the rCBF in man.

Adult↗
PubMed1978

Correlation between regional cerebral blood flow and brain atrophy in dementia. Combined study with 133Xenon inhalation and computerised tomography.

Measurement of the regional cerebral blood flow (rCBF) by the 133Xenon inhalation method and computerised tomography were performed in 25 patients with presenile and senile dementia. Reduction of rCBF and various degrees of ventricular enlargement and cortical sulcal widening were demonstrated in the majority of demented subjects. However, there was no correlation between rCBF values and the severity of ventricular dilatation or cortical atrophy. These findings suggest that loss of brain substance is not an important factor in the reduction of rCBF in dementia.

Adult↗
PubMed1978

Blood flow in rat brain during exposure to high oxygen pressure.

Total cerebral blood flow and blood flow in 10 brain structures of unanesthetized rats were measured by the indicator fractionation technique under different oxygen pressures. The first electrical discharge seen under high oxygen pressure was considered as an early sign of brain oxygen toxicity. It was found that the effect of high oxygen pressure on cerebral blood flow was time- and pressure-dependent. Exposure to 2 and 3.5 ATA of O2 led to vasoconstriction. Exposure to 5 ATA of O2 produced an initial vasoconstriction followed by a secondary vasodilatation to normal level. Cerebral blood flow was not reduced during exposure to 7 ATA of oxygen. Non-decreased blood flow preceded the appearance of the first electrical discharge in all investigated structures of the brain. There was no change in electrical activity of the brain as long as a decrease in cerebral blood flow was maintained. It is suggested that changes in electrical activity of the brain may be produced by toxic levels of brain tissue PO2. Vasoconstriction resulting in decreased cerebral blood flow was considered as a protective mechanism against the toxic effects of high tissue PO2.

Action Potentials↗