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Biomedical subjects

A Barbeau

Publications and source records attributed to A Barbeau.

At least 199 records · Page 11Linked to original sources
PubMed1976

Pyruvate metabolism in Friedreich's ataxia.

Friedreich's ataxia patients show evidence of an abnormally elevated and prolonged response of pyruvate and lactate to a glucose load, with normal fasting levels. However, ther is a bimodal distribution of this response with high and low pyruvate responders. This trait appears to be determined genetically, However, although in vivo tests suggest low oxidation of pyruvate, we were unable to confirm any in vitro impairment of each of the components of the pyruvate dehydrogenase (PDH) complex. We conclude that the defect is in the metabolic regulation of PDH, probably at the E3 (lipoamide dehydrogenase) step.

Alanine Transaminase↗
PubMed1976

Friedreich's ataxia 1976-an overview.

The prospective investigation of 50 cases of possible Friedreich's ataxia has permitted the clinical and biochemical celineation of the typical disease and an hypothesis on its pathogenesis. A tentative definition of the disorder could read: "Friedreich's ataxia is a progressive degenerative disease always inherited in an autosomal recessive fashion and characterized by a cardiomyopathy and a ganglioneuropathy with dying back phenomenon. It is probably secondary to a defect in the membrane transport of taurine and beta-alanine and/or a defect in the regulation of pyruvate oxidation." The existence of two pathogenetically distinct distinct entities with the same phenotype is a strong possibility.

Bilirubin↗
PubMed1976

Progress in understanding and treating Parkinson's disease.

This review evaluates the long-term results of Levodopa therapy in Parkinson's disease upon quality of life, prolongation of survival and excess mortality. It also focuses on recent and new therapeutic approaches: Levodopa in combindation with a Dopa-decarboxylase inhibitor or MAO-B inhibitor, dopamine agonists and an active tripeptide: L-prolyl-L-leucylglycine amide (MIF-I). It ends by looking at new avenues of etiological research in Parkinson's disease which may indicate specific accelerated ageing of catecholaminergic (pigmented) neuronal systems.

Aromatic Amino Acid Decarboxylase Inhibitors↗
PubMed1976

Circadian variations of the urinary excretion of catecholamines and electrolytes.

Concomitant measurements of circadian variations in the urinary excretion of dopamine (DA), homovanillic acid (HVA), norepinephrine (NE), epinephrine (E) as well as of creatinine, sodium and potassium under controlled dietary conditions during relative physical and emotional rest in 13 volunteers have shown that maximum excretion of all these substances occurred in the afternoon period between 14:30h and 18:00h, and minimum excretion in the morning between 4:00h and 5:00h. The changes were in some cases progressive from one collection period to the other, and synchronized for NE and E. DA and HVA excretions fluctuated from subject to subject. Excretory rhythms of sodium and potassium were found to be similar to those of the catecholamines. This can be explained by diurnal changes in renal blood flow and different renal excretory mechanisms of catecholamines. None of the catecholamines correlated with the urinary volume but urinary NE and E positively correlated with urinary creatinine, urinary NE and E with urinary DA and urinary sodium with urinary E. There are some common patterns in the diurnal rhythms of catecholamines and electrolytes but their interrelationship is different for individual catecholamines.

Adult↗
PubMed1976

Some properties of acetylcholinesterase from rat retina.

Acetylcholinesterase (AChE, EC 3.1.1.7) of rat retina was studied with respect to its kinetic and other properties, and a comparison was made with the enzyme from brain. The subcellular distribution of the retinal AChE showed that the enzyme was concentrated in the synaptosomal-mitochondrial fraction although in the brain the AChE was distributed more evenly between the fractions studied. The enzyme from both retina and brain was easily solubilised and exhibited a Km of the order of 10(-4) M. The pH optimum was 8.3-8.6 for the AChE from both tissues for both the soluble and particulate enzyme.

Acetylcholinesterase↗
PubMed1976

Six-year results of treatment with levodopa plus benzerazide in Parkinson's disease.

A combination of levodopa and a peripheral dopa-decarboxylase inhibitor, benzerazide (Ro 4-4602), was studied over a 75-month period of observation in 132 patients with Parkinson's disease. The combined therapeutic approach was without biological toxicity, was well tolerated by 95 percent of patients, and was highly effective: 72 percent of patients improved by more than 50 percent on a functional activity scale and the group as a whole improved on an objective battery by a mean of 46 percent. Neurologic side effects of abnormal involuntary movements, falls, and oscillations in performance were not improved over levodopa used alone. The combined therapy is to be preferred over the use of levodopa alone in the symptomatic management of Parkinson's disease.

Adult↗
PubMed1976

Role of manganese in dystonia.

In this chapter, we have attempted to demonstrate that chronic manganese intoxication, in both animals and man, is a better model of dystonia than of Parkinson's disease. It is proposed that many of the monoamine and endocrine changes in dystonia may be the result of disturbances in manganese metabolism. A search for such modifications in human dystonia victims is presently underway. Preliminary studies indicate that head and pubic hair manganese concentrations are elevated in dystonia patients.

Animals↗
PubMed1975

Potentiation of levodopa effect by intravenous L-prolyl-L-leucyl-glycine amide in man.

L-prolyl-L-leucyl-glycine amide (P.L.G.) has melanocyte-stimulating-hormone-inhibitory hormone (M.I.F.) activity. When injected intravenously as a bolus of 200 mg, it greatly potentiated the effect of an oral levodopa dose upon motor performance objectively measured by a battery of tests. This amelioration in motility was accompanied by improvement in intellectual functioning.

Administration, Oral↗
PubMed1975

Behavioral effects in rats following intrastriatal microinjection of manganese.

We have demonstrated that injection of manganese into one caudate nucleus in rats results in a predominant ipsilateral turning behavior, accompanied at higher doses by an intermittent, alternating and dose-related incidence of contralateral turning and stereotypies. Although the pharmacological evidence produced (effect of alpha-MT, L-DOPA, pargyline) indicates a definite participation of the dopaminergic system in the latter two phenomena, it is probable that ipsilateral turning is the result of involvement of other transmitter systems as well. Tegmental serotoninergic and intrastriatal cholinergic pathways appear to be involved in the production of the basic postural asymmetry resulting in turning. The amount of interference with the nigrostriatal and mesolimbic dopaminergic pathways may determine the speed of circling, and the concurrent inhibition of locomotion. This is more evident with bilateral injections. Manganese appears to act at presynaptic levels within the striatum by blocking release of the transmitter, thus creating a localized, relative deficit in caudate function. The end result is the release of the dominant "ipsilateral syndrome-inducing system' from its inhibitory control. Repeated or chronic administration of this metal in man or animals is known to result in a brain dopamine and/or serotonin deficit commensurate with the clinical manifestations of bradykinesia and dystonia. Our results are compatible with the anatomical findings of Poirier and collaborators and tend to support the dual ipsilateral and contralateral syndrome-inducing systems in the caudate postulated by Cools, and the complementary roles of dopamine, serotonin and acetylcholine within that nucleus. No one transmitter is involved alone in the experimental production of the manganese syndrome, or of its component symptoms.

Aggression↗
PubMed1975

Urinary homovanillic acid, dopamine and norepinephrine excretion in patients with essential hypertension.

Urinary excretion of dopamine, norepinephrine and homovanillic acid was measured in normotensive subjects and in patients with either labile of stable hypertension under conditions controlled for posture, sodium and potassium intake and time of day. Mean homovanillic acid excretion was 313.5 plus or minus 77.7 (SE) mug/4h in the normotensive patients. Mean values for the patients with labile or stable hypertension were significantly greater, at 2506 plus or minus 476 mug/4 h (P smaller than 0.001) and 795 plus or minus 170 mug/4 h (P smaller than 0.01), respectively. Urinary excretion of dopamine and norepinephrine tended to be elevated in patients with labile hypertension when compared with values in the control subjects and the patients with stable hypertension. The data are compatible with the hypothesis of adrenergic hyperactivity in labile hypertension and underline the biochemical heterogeneity of essential hypertension. Because the overlapping of values between control subjects and patients with labile hypertension was minimal, it is proposed that an elevated valve for urinary homovanillic acid could be used as a biochemical marker to identify the patients with labile hypertension.

Adolescent↗