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Biomedical subjects

A Barbeau

Publications and source records attributed to A Barbeau.

At least 37 records · Page 2Linked to original sources
PubMed1979

Friedreich's ataxia 1979: an overview.

This overview summarizes the investigations carried out during the second part of Phase Two of the Quebec Cooperative Study of Friedreich's Ataxia. These investigations outline in more details the fundamental role played by an abnormality in the fatty acid composition (deficient linoleic acid, 18:2) of the cholesterol esters of high density lipoproteins (HDL) in the phenotypic expression of the disease. They postulate a defective incorporation of linoleic acid to surface phosphatidylcholine of chylomicrons and consequent relative and absolute decreases in lipoprotein protein components because of overpacking with defective cholesteryl esters. Secondarily to these changes, the postulated lack of activation of the lipoamide dehydrogenase (LAD) of the pyruvate dehydrogenase (PDH) complex could result in slow pyruvate oxidation, glucose intolerance, deficient synthesis of acetylcholine, and depletion of glutamic and aspartic acid pools. In parallel, abnormal phosphatidyl-choline molecules could be incorporated to membranes, resulting in specific defects in some functions of these membranes, including transport of calcium and/or taurine and myelinization. The framework of an understanding of Friedreich's ataxia is now available, but much fundamental and clinical work remains to be done to fill in and prove each one of these postulated steps.

Friedreich Ataxia↗
PubMed1979

Comparison of neurobehavioral effects induced by various experimental models of ataxia in the rat.

The purpose of the present study was to design a standard battery of tests capable of quantitatively characterizing ataxia and concomitant neurological signs in the rat. In addition to a systematic analysis of the walking gait of animals, tests for activity, catalepsy, rigidity and various reflexive responses were included in the battery. The standardization of the test system was performed by determining and comparing neurobehavioral effects produced by 3-acetyl pyridine, acrylamide, pyrithiamine and thiamine deficiency, four experimental treatments reported to induce ataxia in animals. Results indicate that profiles of neurobehavioral disturbances accompanying ataxia in animals varied distinctively with each experimental treatment.

Acrylamide↗
PubMed1978

Differential behavioral activities from anterior and posterior hypothalamic lesions in the rat.

Bilateral 6-hydroxydopamine injections into the anterolateral (AL) or posterolateral (PL) portions of the hypothalamus produced hypokinesia, catalepsy, rigidity and severe weight losses due to aphagia and adipsia. Subcutaneous administration of apomorphine, 1 mg/kg, 48 hr after 6-OHDA injections reversed temporarily the hypokinesia in both AL and PL 6-OHDA groups. However, qualitative and quantitative differences in the behavioral responses to the drug were observed. Motor activity as measured by photocell counts was significantly greater in AL 6-OHDA rats. Apomorphine induced stereotyped behavior in both groups; however, the predominant behavioral responses were oral stereotypies in PL 6-OHDA animals and sniffing in AL 6-OHDA rats.

Animals↗
PubMed1978

Hypokinesia produced by anterolateral hypothalamic 6-hydroxydopamine lesions and its reversal by some antiparkinson drugs.

Hypokinesia produced by stereotaxic microinjection of solutions of 6-hydroxydopamine into the anterolateral hypothalamus of male rats is accompanied by a generalized reduction in brain noradrenaline levels and a reduction of dopamine in the striatum and cerebral cortex. The hypokinesia is reversed by the putative dopamine-receptor agonists apomorphine, ET-495 and CB-154 as well as by the amino acids L-Dopa and m-tyrosine when administered in combination with the peripheral decarboxylase inhibitor Ro 4-4602. The relative importance of noradrenergic and dopaminergic systems in the mediation of the action of anti-akinesia drugs is discussed.

Animals↗
PubMed1978

Accumulation and removal of Hg203 in different regions of the rat brain.

We have studied the brain regional distribution of methyl mercury following intravenous administration of CH3 203HgCl in rat. Early peak levels were obtained in cerebellum, medulla oblongata and midbrain. The efficacy of removal of 203Hg by different chelators is also region dependent. The most efficient chelator for brain mercury proved to be mesodimercaptosuccinic acid.

Animals↗
PubMed1978

Ouabain induced stereotyped behavior in rats.

Stereotyped behavior was induced in rats with ouabain administered intraventricularly in doses of 2, 3 and 4 microgram in 50 microliter saline. Haloperiodol reduced the stereotyped behaviour. Monoamine turnover studies showed a reduction in concentration of norepinephrine in hippocampus and midbrain, an increase in norepinephrine turnover in the medulla oblongata and a reduction in dopamine turnover in the striatum. The interpretation of these finds is discussed. It is suggested that this model could be significant clinically as it demonstrates that impairment of Na+-K+-ATP'ase may result in behavioral abnormalities characterised by stereotypy.

Animals↗
PubMed1978

Ouabain induced seizures: site of production and response to anticonvulsants.

Ouabain, an inhibitor of Na+ -K" -ATP'ase, has been administered intraventricularly to rats to study the effect of impairment of membrane transport mechanisms on the genesis of seizures. Running and leaping seizures occur rapidly after injection of ouabain in a low volume (10 microliter) when the maximal uptake of ouabain (39.8%) is the hippocampus. Generalized clonic-tonic seizures are induced by higher volume injections (50 microliter) associated with wider distribution of ouabain, including the cerebellum and brainstem. Ouabain was injected into cerebral cortex, caudate nucleus, dorsal hippocampus, fastigeal nucleus, ventrolateral mesencephalic reticular formation and cerebellar cortex. The cerebellar injections produced both running and leaping and generalized clonic-tonic seizures. It is suggested that this results from decreased inhibitory effect of vermal and paravermal Purkinje cells on intra-cerebellar nuclei, which alters cerebellar influence on the reticular formation and the limbic system. Diphenylhydantoin, phenobarbitone, phenacemide, carbamezepine and clonazepam but not ethosuximide are effective against generalized clonic-tonic seizures, suggesting that this is a model for "grand mal" but not "petit mal" seizure mechanisms. It is furthermore suggested that running and leaping are subcortical, probably limbic, seizures that are most relevant as a model for temporal lobe seizures.

Animals↗
PubMed1978

Regulation of brain pyruvate dehydrogenase multienzyme complex.

A number of excellent and comprehensive reviews on various aspects of pyruvate dehydrogenase multienzyme complex have been written recently. The purpose of the present review is to summarize briefly the reaction mechanism and the regulation of this enzyme. Emphasis is put on the most recent literature not covered by previous reviews. Particular attention is also paid to the regulation of brain pyruvate dehydrogenase multienzyme complex, since a number of patients with neuromuscular diseases, such as Friedreich's ataxia, show a decreased rate of pyruvate oxidation.

Animals↗