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Biomedical subjects

J M Reymann

Publications and source records attributed to J M Reymann.

49 records · Page 3Linked to original sources
PubMed1980

[Effect of ascorbic acid during acute iterative anoxia, hypothesis of an anti-oxidizing mechanism of action in comparison with the effect of hydroquinone].

Some of the problems which appear during senescence, are said to be caused by cerebral oxygen deficiency and various experiments have been set up to try to imitate this particular aspect of the ageing process. We have already studied the action of many drugs with regard to acute repeated anoxia. Our work has given us clear evidence of the activity of ascorbic acid, which delays the moment of electroencephalographic silence in rats and decreases the latent period up to the reappearance of electrical activity. In order to pinpoint the mechanism of action, we compared the influence of lysine aceto-salicylate with that of hydroquinone. Very small doses of the latter drug produce a marked effect and lead us to put forward the hypothesis that it may be anti-oxydising. However, although all the drugs which proved effective in these experiments may be grouped together (despite their varying pharmacological profiles) and described as "anabiotic" drugs, it is not possible to revert to a single mechanism of action for the group as a whole.

Animals↗
PubMed1979

Plasmatic renin activity in patients treated with L-dopa and inhibitor of dopa decarboxylase (IDC).

Plasmatic renin activity (PRA) was studied in patients receiving L-dopa, together with a decarboxylase inhibitor, at rest times and after periods of physical exertion. Although we can superimpose the results from unrelated Parkinson's disease patients on those of the control group, the results are inversed in stabilized patients (lowered PRA) and dyskinetic patients (increased PRA). There is a definite correlation between the increase in PRA and intensity of the dyskinesia. Dosage is the only other factor differentiating the two groups of Parkinsonians treated. The figures relative to arterial pressure are studied in the various groups.

Adult↗
PubMed1979

[Neuropharmacological data on the striatum].

The striatum constitutes the most voluminous basal ganglia in man. It is issued from ganglionic eminences which are very early bound by limbic kernels. If the cortical and reticulo-spinal projections have been first described the existence of anatomical connexions with the limbic system offers a large number of functional possibilities. The knowledge of the distribution of the different chemical substances which are present within this structure as well as the enzymes necessary for their synthesis and destruction permits to establish a chemical mapping, the dopaminergic one being the best known. The dopaminergic synaptic function in the striatum helps to understand the respective roles of the pre and post-synaptic receptors as well as the mechanisms by which the other neuromediators can modulate the dopaminergic activity, the cyclic nucleotides being often necessary for this action. These fundamental data subtend the mechanism of action of most of the drugs which are involved in extrapyramidal phenomenons (neuroleptics, dopaminergic agonists) and allows to put forth physiopathological hypothesis on Parkinson disease, Huntington chorea, as well as certain induced or spontaneous dyskinetic states. The functions of the striatum are then evoked: if the role of this structure in motor control is critical, its involvement in complex behaviours is strongly suggested.

Animals↗
PubMed1979

[Influence of a tributyltin oxide oily aerosol on the exploratory behaviour toward the mouse (author's transl)].

Inhalation of an oily aerosol of bis (tributyltin oxide) (TBTO) after single or repeated expositions (1 hour) disturb the exploratory behaviour in the mouse. Weak concentrations (42 and 84 ppm) stimulate exploratory activity while large doses (170 and 340 ppm) significantly decrease it. Modification in brain amine levels may appear but the observed perturbance seems to be more dependent from oily vehicule than TBTO itself.

Aerosols↗
PubMedDate not supplied

Effect of triethyltin chloride on the central aminergic neurotransmitters and their metabolites: relationship with pathophysiology of aging.

Triethyltin (TET) salt intoxication provokes a myelinic vacuolisation associated with a white matter cerebral edema. The central nervous system disturbances accompanying these phenomena (Na-K-ATPase activity, neurological symptoms, water and sodium cerebral content) can be counteracted by drugs used in age-related brain failure; consequently, TET intoxication could be suggested as an experimental model for studying the aging process. The aim of the present study is to follow-up the biogenic amine concentrations in different brain areas of TET treated rats, knowing that modifications of cerebral amines exist throughout the aging process. The following results are obtained: the cerebral water content of the TET treated rats is significantly increased, confirming the existence of a brain edema. Monoamine concentrations are significantly decreased, specifically noradrenaline (in hypothalamus, mesencephalon, cerebellum); serotonin (in striatum, hypothalamus, mesencephalon); dopamine only in hypothalamus; these are accompanied by an increase of the metabolites 5 HIAA (in striatum and mesencephalon) and HVA (striatum). These modifications are compared to those occurring in physiological aging, and hypothetical mechanisms are reviewed. We conclude that TET intoxication must not be considered as a pathophysiological model of brain aging, but may be considered as a useful pharmacological tool for studying experimental drugs liable to counteract brain age-induced disturbances.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Procedural memory in recent-onset Parkinson's disease.

Parkinson's disease is accompanied by cognitive disorders which may affect procedural memory. Procedural memory uses a specific knowledge resource that expresses itself through pre-established acting procedures. The aim of this study was to better define the characteristics of procedural memory, first of all, by trying to determine the level of involvement of that memory in the acquisition process (during learning and/or during procedure maintenance), then by specifying the effect of the type of resource involved (verbal or motor). To achieve this, we compared the mnestic performances of 20 recent-onset parkinsonian patients with those of 20 healthy controls, using two memory tasks with a fixed rule (poetry, visuomotor tracking). Result analysis revealed that parkinsonian patients had more difficulty than controls in learning the two rules, regardless of the material involved. Their deficiencies were often associated with an impairment of executive functions, and the procedural memory problems described in parkinsonian patients are linked to the involvement of these resources in the various tasks.

Aged↗
PubMedDate not supplied

Effect of normal aging and of Alzheimer's disease on, episodic memory.

Performances of 12 patients with Alzheimer's disease (AD), 15 healthy elderly subjects and 20 young healthy volunteers were compared on two episodic memory tests. The first, a learning test of semantically related words, enabled an assessment of the effect of semantic relationships on word learning by controlling the encoding and retrieval processes. The second, a dual coding test, is about the assessment of automatic processes operating during drawings encoding. The results obtained demonstrated quantitative and qualitative differences between the population. Manifestations of episodic memory deficit in AD patients were shown not only by lower performance scores than in elderly controls, but also by the lack of any effect of semantic cues and the production of a large number of extra-list intrusions. Automatic processes underlying dual coding appear to be spared in AD, although more time is needed to process information than in young or elderly subjects. These findings confirm former data and emphasize the preservation of certain memory processes (dual coding) in AD which could be used in future therapeutic approaches.

Aged↗
PubMedDate not supplied

Procedural memory and Parkinson's disease.

A detailed analysis of the mnestic deficits associated with Parkinson's disease (PD) contributes to explaining the cognitive disorders and their well documented consequences. This study was designed to show that, in PD declarative as well as procedural memory is severely impaired. Three tests designed to explore this aspect of mnestic functioning were proposed to a group of 16 parkinsonian patients whose motoricity was controlled: inverted reading, braille reading, sound form association. The results obtained, compared with those of young and aged controls, show that PD is associated with marked deficits in both declarative and procedural memory. Declarative memory impairment was similar to that observed in the control population (healthy elderly subjects, age-matched with the PD patients) but more marked in PD subjects. The procedural memory deficit was linked with age and pathology. Procedural memory involves a variety of processing modules dedicated to the type of information (visual, auditive, tactile codes). The deficits observed were more like a loss of automatism than procedural impairment stricto sensu ('knowing how'). It would be worth pursuing research by studying akinesia and motor disorders from the angle of automatic memory impairment.

Adult↗
PubMedDate not supplied

[Modification of aminergic neurotransmitters and neurobehavioral correlates in acute cerebral ischemia in the rat].

Aminergic neurotransmitters and their main metabolites concentrations are measured in four areas (posterior cortex, striatum, hippocampus, hypothalamus) of the rat brain, 24 hours after an acute ischemic injury (created by the occlusion of the four cephalic vessels). Simultaneously, spontaneous motility and neurological status are evaluated. The main results are the increase of 5 HIAA in striatum, hippocampus and cortex, associated with an increase of HVA in striatum. Motility as well as neurological scores are significantly decreased in ischemic animals when compared with controls. The conclusion is that this model of cerebral ischemia is may be useful for pharmacological assessment of drugs liable to antagonize cerebrovascular disorders.

Animals↗
PubMedDate not supplied

[Anti-cerebral edema properties of PEG 300 in triethyltin poisoning].

The polyethylene glycols (PEG) frequently used as solvents of non hydrosoluble molecules present toxic and pharmacodynamic properties. The effect of PEG 300 (10 ml/kg) on the modifications of the central nervous system (CNS) previously induced by a subchronic intoxication with triethyltin salt (TEE) (2 mg/kg p.o. for 5 days) has been studied in rat. The following parameters are recorded: measure of brain edema, concentration of the aminergic neurotransmitters in four different brain areas, neurological status, behaviour, mortality. The PEG 300 antagonizes or reduces some of the effects of the TEE: edema, behavioral disturbances, mortality. On the opposite, no change in the amines and their metabolites induced modifications is observed. This selective antagonism towards some of the components of TEE brain toxicity brings more information on pharmacological properties of this solvent and opens a discussion on the role of neurotransmitters on brain edema.

Animals↗
PubMedDate not supplied

[Comparative effects of seven beta adrenolytic agents on blood pressure after injection into the posterior hypothalamus of rats. The frequency heart and the plasma renin activity (author's transl)].

The author's studied the central action of seven beta-blocking agents: alprenolol, atenolol, bupranolol, oxprenolol, pindolol, practolol, propranolol. The drugs were stereotactically injected into the posterior hypothalamus of non anaesthesized rats. Three dosages were used. Blood pressure, heart rate and plasma renin activity (PRA) were recorded. 2. The seven beta-blocking drugs used decreased heart frequency for at least one dosages PRA always decreased but blood pressure was lowered only after administration of alprenolol, oxprenolol, pindolol. 3. The discussion deals with: --the specificity of the target, --the involvement of the central beta receptors into the PRA regulation, --the correlations between the cardiovascular responses and the pharmacological properties of the different molecules; the hypothetic role of the intrinsic activity is postulated --the dissociation between heart rate and blood pressure responses, suggesting the existence of two different receptors for the specific control of those two parameters.

Adrenergic beta-Antagonists↗