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Biomedical subjects

A Barbeau

Publications and source records attributed to A Barbeau.

At least 217 records · Page 12Linked to original sources
PubMed1975

A reliable method for the simultaneous estimation of dopamine, noradrenaline and serotonin in discrete areas of brain.

1. Sub-microgram levels of dopamine (DA), noradrenaline (NA) and serotonin (5HT) were estimated simultaneously in small discrete areas of brain by a simple combined alumina adsorption-spectrofluorometric technique. 2. The method does not depend on the use of ninhydrin which is reported to interfere with the spectrofluorometric assay of 5HT nor does the method involve the use of phosphate buffers which reportedly are a source of error in catecholamine assays. 3. The method described is suitable for the measurement of amine levels both in normal conditions and when amino levels have been severly reduced by amine-depleting drugs. Neither reserpine nor alpha-methyl-p-tyrosine interfere in the assay.

Animals↗
PubMed1975

Progress in understanding Huntington's chorea.

The present paper analyses the new data accumulated since 1972 concerning the etiology and pathogenesis of Huntington's chorea. Particular attention is paid to the respective roles of the dopaminergic and GABA-ergic systems.

Acetylcholine↗
PubMed1975

The brain, the heart and taurine.

This paper reviews some recent developments concerning the "non-essential" amino acid Taurine. It is shown that taurine is important in metabolic regulations within the heart, muscle and brain. Particular attention is paid to the neuropharmacology of taurine, such as its possible role in epilepsy.

Analgesia↗
PubMed1975

Sex differences in the urinary catecholamines.

Urinary excretion of dopamine, norepinephrine and epinephrine was measured in a group of adult men and women of comparable age during recumbency and then during stimulation by upright posture. Urinary norepinephrine was found to be significantly higher in women (30.3 +/- 4.4 ng/min/m2 B.S.) than in men (18.3 +/- 2.7 ng/min/m2 B.S.) during recumbency; there was no significant sex difference in dopamine and epinephrine excretion. There was no apparent trend indicating a difference in urinary catecholamine excretion during the follicular or luteal phase of the menstrual cycle. In response to upright posture, there was a significant decrease in the urinary dopamine-norepinephrine ratio in both sexes; the magnitude of the decrease was, however, significantly higher in men (-9.9 +/- 3.0) than in women (-2.05 +/- 0.72). The mechanisms of the sex differences in urinary catecholamine excretion are unknown. Clinical studies involving catecholamines have to take these sex differences into account.

Catecholamines↗
PubMed1975

Apomorphine: sterotyped behavior and regional distribution in rat brain.

The distribution of apomorphine following subcutaneous injection of 20 mg/kg (as the hydrochloride) was measured spectrofluorometrically in specific regions of rat brain. Measurable concentrations were found in the brain within a few minutes of injection, the drug was still detectable for at least 60 min in all regions, and maximum concentration was observed 20 min after injection. Stereotyped behavior, characteristic of apomorphine action, followed a time course parallel to accumulation of the drug in the brain.

Animals↗
PubMed1975

Labile (borderline) hypertension--new aspects of a common disorder.

Labile hypertension in patients under 50 years of age (the non-atherosclerotic form) was found to be characterized by higher urinary excretion of catecholamines and particularly of homovanillic acid; when further analyzed it was shown to be a heterogeneous entity with two types of patients clinically and biochemically distinguishable from each other, from control subjects and from patients with stable hypertension. Reactivity to assuming an upright posture distinguishes one type of labile hypertension having a normal postural pulse rate response from another having an excessive postural increase in pulse rate. The first group also showed normal responses of plasma norepinephrine concentration and of urinary cyclic AMP to posture. The group with excessive pulse rate response, in contrast, showed a decrease in plasma norepinephrine and an excessive increase of urinary cyclic AMP excretion in response to upright posture. The results suggest that not only circulating catecholamines but also the reactivity of their target tissues (as probably reflected by cyclic AMP measurements) are important in bringing about signs of adrenergic excess. The hypothesis that cyclic AMP changes reflect beta-adrenergic receptor reactivity is strongly favoured by data indicating qualitative differences in cyclic AMP responses to beta-adrenergic stimulation or inhibition between control subjects and those labile hypertensive patients with clinical signs of excessive sympathetic reactivity. The study stresses the need for more precise definition of labile hypertension, for dynamic clinical and biochemical correlative studies, and for consideration not only of the circulating hormones but also of the "second messengers" (such as cyclic AMP and cyclic GMP) which reflect the cellular action of hormones. Blood pressure is a very labile parameter in health and disease. In one sense, therefore, hypertension can be considered "labile" in every hypertensive patient. Usually, however, labile (or borderline) hypertension is regarded as characterized by a blood pressure over 140/90 mmHg, falling below these values with physical and emotional rest. This clinical entity, which affects some 20% (variously estimated between 16 and 30%) of the adult population, gives rise to uncertainties in both definition and prognosis. In some patients labile hypertension represents the precursor of a fixed hypertensive state, whereas in many others it remains labile throughout life, never progressing to the stable phase nor becoming associated with hypertensive cardiovascular disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Catecholamines↗
PubMed1975

Uptake and efflux of 14-C-dopamine in platelets: evidence for a generalized defect in Parkinson's disease.

Thirty-five parkinsonian patients (five untreated, six with levodopa only, seven with levodopa plus Ro 4-4602, nine with anticholinergic and/or antihistaminic medication, and eight with the anticholinergic/antihistaminic medication plus amantadine) and 35 age-matched control subjects were studied. Platelets isolated from each individual plasma were incubated with 14C-dopamine. Uptake was found to be decreased to a significant degree in all treated or untreated parkinsonian patients when compared with control subjects. Anticholinergic and/or antihistaminic medication, with or without amantadine, further decreased the dopamine uptake into platelets, while levodopa alone or with Ro 4-4602 returned uptake values to near normal. Dopamine efflux paralleled exactly the uptake values. The fact that parkinsonian platelets exhibit impaired dopamine uptake, while age-matched control platelets do not, constitutes the first direct evidence in favor of a generalized dopamine defect in Parkinson's disease.

Adult↗
PubMed1975

Apomorphine and piribedil in rats: biochemical and pharmacologic studies.

We studied the biochemical and pharmacologic modes of action of piribedil and apomorphine in the rat. Although both drugs have many points in common, they are also different in many of their manifestations. Apomorphine causes high-intensity, short-duration stereotyped behavior; it is distributed within the brain in uneven fashion, the striatum being the area of lowest concentration as measured by fluorometry. Direct stereotactic injection within the dopaminergic mesolimbic system, and particularly the tuberculum olfactorium, produced constant intense responses. All effects of apomorphine can be blocked by pimozide, but propanolol, a beta blocker, only reduces aggression and ferocity, leaving stereotyped behaviors intact. Finally, L-5-HTP tends to reduce aggression, ferocity, and to a lesser extent stereotypy; MIF or piribedil, as well as reserpine, potentiates the stereotyped behaviors induced by apomorphine, whereas L-DOPA usually decreases them. Piribedil, on the other hand, causes low-intensity, long-duration stereotyped behavior. It is distributed within the brain almost uniformly. Most effects of piribedil can be blocked by pimozide, but propanolol blocks only aggression and ferocity, leaving stereotyped behaviors intact. On the other hand, clonidine, an alpha-receptor agonist, blocks stereotyped behaviors induced by piribedil but markedly increases aggression, ferocity, and motor activity. L-5-HTP and L-DOPA have little effect on piribedil-induced manifestations. Reserpine decreases piribedil stereotypy. The main metabolite of piribedil, S 584, had no clear-cut pharmacologic action in our hands at the dosage used. It is concluded that both apomorphine and piribedil produce stereotyped behavior by modifying the physiologic balance between mesolimbic and nigrostriatal dopaminergic systems. The other actions of apomorphine and piribedil upon aggression, ferocity, and motor activity are not always in parallel and depend probably on the fact that piribedil is less specific, affecting also noradrenergic, serotonergic, histaminergic, and/or cholinergic circuits. The usefulness of piribedil against some forms of human tremor and its low-intensity antiakinetic action probably result from this pattern of pharmacologic activity.

Amygdala↗