PubMed Health⌕ Search

Biomedical subjects

M Le Poncin Lafitte

Publications and source records attributed to M Le Poncin Lafitte.

6 recordsLinked to original sources
PubMed1986

[Cerebral glucose consumption. The effect of Ginkgo biloba extract].

Deoxyglucose is transported under the same conditions as glucose from blood to cerebral tissue. Deoxyglucose-6-phosphate, which cannot be neither metabolized nor eliminated, accumulates in cells. This accumulation is correlated with glucose consumption. In this study, two parameters, transfer rate of deoxyglucose and glucose consumption were measured by means of quantitative autoradiography in two experimental models: normobaric hypoxia and carotid clamping in rats. Normobaric hypoxia induced a decrease in both transfer rate and glucose consumption. Ligature of the carotid artery induced a diminution of glucose consumption greater than that of transfer rate. After administration of Ginkgo biloba extract, glucose consumption was partly reestablished in both experimental models, but the transfer rate of deoxyglucose was increased only in normobaric hypoxia.

Animals↗
PubMed1986

Age and learning: experimental and clinical aspects.

Memory loss and similar cognitive associated dysfunctions are commonly recognized as being the most serious symptoms of ageing and dementia. In this work, a deterioration of cognitive function which is appreciated in old rats (learning test in a maze--or, in aged humans, memory verbal test) is determined during the measurement of local cerebral blood flow and metabolism. In the animal, the disturbance by the learning test is observed by a decrease of blood flow in the hippocampus, diencephalon, and corpus striatum. In man, the cognitive dysfunctions appear although there is an increase of blood flow in the frontal cortex. These data show a new organization in the ageing brain which only appears during cerebral stimulation.

Aged↗
PubMed1986

Psychometric tests in ageing.

In order to detect and analyze early cognitive disorders related to ageing, we selected a battery of psychometric techniques. This battery includes a generally accepted test (the PRM of A. Rey) and new computerized tests (reaction-time test and video objects test) designed by ourselves. We used this battery with aged adults ('normal' and 'impaired' outpatients) and young adults ('normal'). Preliminary results indicate an early decline of spatial structuralization and intellectual associative mechanisms necessary to the efficiency of memory, and also confirm the slowing down in the visual-auditory-motor coordination. The data show how new computerized techniques can be helpful tools to quantify early cognitive disorders.

Aged↗
PubMed1980

Effects of Ginkgo Biloba on changes induced by quantitative cerebral microembolization in rats.

Unilateral embolization of the brain was performed in rats by the intracarotid injection of 4000 radioactive microspheres (50 micron). The local blood flow was determined using the iodoantipyrine technique in the hippocampus, hypothalamus, striatum and remainder of the brain. Embolization resulted in a decrease in the blood flow and a modification of the distribution of microflow. Besides, the embolization produced changes in energy metabolism, specially a fall in ATP and glucose levels and an increase in lactate level. Subsequently severe vasogenic cerebral edema developed. There was a correlation between the number of microspheres injected and the extent of edema. Pretreatment with an extract of Ginkgo Biloba leaves partially suppressed the effects of the embolization. An increase in the blood flow associated with normalization of cellular energy metabolism explained the decrease in brain edema.

Adenosine Triphosphate↗
PubMedDate not supplied

Evidence for the role of ammonia in the intracerebral transfer and metabolism of tryptophan.

After portacaval shunt in the rat, the transport of tryptophan and other neutral amino acids across the blood-brain barrier is enhanced. To determine the role of NH3 in the intracerebral transfer of tryptophan and serotonin metabolism, solutions containing either saline or NH3 or tryptophan or NH3 + tryptophan together were infused, respectively, into the internal carotid artery of rats in order to achieve blood levels similar to those observed after liver ischemia. After tryptophan infusion, a significant increase in the hypothalamic levels of tryptophan and 5-hydroxyindoleacetic acid was observed. A similar increment was found after NH3 infusion. NH3 + tryptophan infusion induced a significant increment in hypothalamic tryptophan and 5-hydroxyindoleacetic acid levels which were 2-fold greater than after tryptophan infusion. There was no significant change in 5-hydroxytryptamine levels in any of these experiments. Glutamine levels increased significantly after NH3 infusion. When tryptophan and NH3 were infused simultaneously, a significant reduction in glutamine levels occurred. These results cannot be explained by any modification of cerebral blood flow nor of the cerebral intercellular pH. Our data suggest that NH3 enhances the transfer of tryptophan across the blood-brain barrier and thus stimulates serotonin metabolism. The mechanism by which tryptophan transfer across the blood-brain barrier is facilitated is unknown. The reduction in glutamine levels in the hypothalamus when NH3 and tryptophan are infused together may be explained either by an inhibition of synthesis or by an intercellular influx of neutral amino acids and an efflux of glutamine as suggested by James et al.

Amino Acids↗