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Biomedical subjects

A Barbeau

Publications and source records attributed to A Barbeau.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1978

Emerging treatments: replacement therapy with choline or lecithin in neurological diseases.

This review evaluates the theoretical background and experimental data behind a new development: the replacement therapy of deficient central cholinergic systems with the dietary precursors choline or lecithin. Cholinergic deficiency states are possibly present in five neurological entities: Huntington's chorea, Tardive Dyskinesia, Gilles de la Tourette's disease, Friedreich's ataxia and pre-senile dementia. Preliminary data from various laboratories, including our own, in each of these disorders indicate that some clinical improvement can occasionally be seen, and that this approach deserves further investigation.

Animals↗
PubMed1978

Plasma lipids and lipoproteins in Friedreich's ataxia and familial spastic ataxia--evidence for an abnormal composition of high density lipoproteins.

A systematic study of plasma lipids and lipoproteins was carried out in 11 cases of Friedreich's ataxia and 6 cases of familial spastic ataxia (Charlevoix-Saguenay disease) using 11 healthy normolipidemic volunteers of comparable age and sex as controls. No differences were noted in the fatty acid profile of the total lipid fraction, in the total cholesterol and phospholipids or in the percentage distribution of the individual phospholipid classes. The triglycerides were significantly higher in Friedreich's ataxia, but remained within the normal range. Although no systematic abnormalities could be detected in the electrophoretic pattern of plasma lipoproteins or in the apolipoprotein profile on polyacrylamide gel electrophoresis, major differences were found in the high density lipoprotein (HDL) fraction. Their total amount was reduced and their composition was abnormal in both neurological diseases. In Friedreich patients, the relative proportion of cholesterol and triglycerides was increased while the relative protein content was greatly reduced. In Charlevoix disease, a similar abnormality was seen except for the excess of triglycerides. The proportion of phospholipids in HDL was the same in the three groups of patients. In addition, the low density lipoprotein (LDL) fraction was slightly reduced in both diseases. This anomaly of the HDL fraction could indicate that the HDL apolipoprotein moiety has a greater affinity for cholesterol and triglycerides in Friedreich's ataxia than its normal counterpart.

Adolescent↗
PubMed1978

[Physiological trials with MIF-I in Parkinson's disease (author's transl)].

The writers present some physiological (and not therapeutic) acute and sub-acute trials with tripeptide: L-propyl-L-leucyl-glycine amide (M.I.F.-I) in Parkinson's Disease. This work confirms the earlier observation that M.I.F.-I employed alone or in combination with Levodopa is active against Parkinson's disease. The writers evoke the hypothesis that this action takes place at the postsynaptic receptors, whose configuration may be modified in the sense of a hypersensitivity. These studies justify undertaking a series of controlled therapeutic trials when the cost of the product permits and as well instituting development work on analogues active orally.

Aged↗
PubMed1978

Familial hyperbilirubinemia in Friedreich's ataxia.

The combined metabolic stresses of fasting and the intravenous injection of 50 mg nicotinic acid in Friedreich's ataxia resulted in the delineation of two sub-groups of responses. High bilirubin ataxics maintained abnormally elevated levels of bilirubin, while normal bilirubin ataxics behaved like the normal control group. It is postulated that this finding infers the possible linkage of the gene for Friedreich's ataxia and that for Gilbert's disease.

Bilirubin↗
PubMed1978

Lipoamide dehydrogenase regulation in rat brain.

The Pyruvate dehydrogenase multienzyme complex (PDHC) purified from rat brain is phosphorylated in the presence of low concentrations of ATP and MgCl2. The phosphorylated PDHC is incapable of catalyzing the oxidative decarboxylation of pyruvate. In the presence of high concentrations (10 mM) of MgCl2, the phosphorylated (inactive) PDHC is converted back to the dephospho-form of PDHC which is catalytically active. The dihydrolipoyl dehydrogenase (LAD) component, E3, of PDHC is inactivated by pyridoxal phosphate (PLP) and the PLP-inactivated LAD can be reactivated by an amino acid, taurine. These results indicate the reversible formation of Schiff base between PLP and LAD. They also provide clear evidence for the involvement of LAD (E3) in the previously reported inactivation of PDHC by PLP.

Adenosine Triphosphate↗
PubMed1978

Serum and platelet lipoamide dehydrogenase in Friedreich's ataxia.

Pyruvate dehydrogenase (PDH), alpha-keto glutarate dehydrogenase (alpha-KGDH) and lipoamide dehydrogenase (LAD) were measured in platelets of 11 patients with typical Friedreich's ataxia and 10 normal control subjects. Serum LAD was also evaluated in the same patients. No statistically significant changes were found in platelets for the group as a whole, although some patients had low values (more than one standard deviation below control mean). Serum LAD was significantly reduced in the patients with Friedreich's ataxia. This was not due to associated diabetes.

Blood Platelets↗
PubMed1978

Lipoamide dehydrogenase in Friedreich's ataxia fibroblasts.

Lipoamide dehydrogenase was measured in cultivated skin fibroblasts from twelve patients with Friedreich's ataxia and nine normal controls. No difference in specific activity, subcellular distribution and Vmax or Km was observed between patients and controls.

Cells, Cultured↗
PubMed1978

Platelet taurine uptake in spinocerebellar degeneration.

The uptake of 14C-taurine was studied in the platelets of 20 ataxic patients and 20 age-matched normal control subjects. No significant differences were found in uptake or kinetics of taurine between the two groups of subjects. If a transport defect in taurine exists in Friedreich's ataxia, it is not present in all tissues. Preliminary indication was obtained in favor of heterogenity of the uptake pattern between ataxic individuals.

Adolescent↗
PubMed1978

Taurine in cerebrospinal fluid in Friedreich's ataxia.

In a previous study we reported low values of taurine and aspartic acid in the CSF of patients with Friedreich's ataxia, when the results were compared to the literature. Further studies have revealed that unforetold difficulties with the advertised methodology of sequential multi-sample amino acid analysis were responsible for low values in the determination of these two amino acids in the small volumes necessary for CSF. A corrected method is presented. With the latter method the differences disappear for CSF taurine and aspartic acid, but they remain valid for the previously reported blood and urine values in Friedreich's ataxia. GABA levels are also normal in Friedreich's ataxia CSF.

Adolescent↗
PubMed1978

Cerebellar ataxia produced by 3-acetyl pyridine in rat.

A single intraperitoneal injection of 3-acetyl pyridine produces, within 24 hours of administration, signs of cerebellar ataxia and damage to the medulla oblongata and to the climbing fibers of the cerebellum. These changes are accompanied by changes in the concentration of certain amino acids in the appropriate areas. Glutamic acid is decreased in cerebellum, medulla, cortex, striatum, hippocampus, retina and olfactory bulbs, while taurine is specifically decreased in the cerebellum and medulla oblongata and aspartic acid in the retina. The concentrations of GABA and glycine are not modified in any of the areas studied. Glutamine is generally increased in concentration in areas of cell damage.

Amino Acids↗
PubMed1978

Effect of alloxan diabetes on cerebellar amino acids.

Rats rendered diabetic by alloxan monohydrate were studied to investigate the effect of increased blood glucose upon the concentration of various putative neurotransmitter amino acids in the cerebellum. No modification was found in the concentrations of glutamate, gamma aminobutyric acid (GABA), glutamine, glycine or taurine, but there was a significant decrease in the cerebellar concentration of aspartate in the diabetic animals. This raises the question of the specificity of the aspartic acid defect found in some form of ataxia.

Amino Acids↗
PubMed1978

Friedreich's Ataxia 1978--an overview.

In the present overview an attempt is made to summarize the investigations carried out during the first part of Phase Two of the Quebec Cooperative Study of Friedreich's Ataxia. These investigations delineated the relative importance of various biochemical leads uncovered during the preliminary survey. It is possible to indicate some findings that may be primary and which should be pursued in subsequent investigations. Among these, the observation of an abnormal composition of high density lipoproteins in Friedreich's Ataxia appears to be the most important.

Adolescent↗
PubMed1978

Autosomal recessive spastic ataxia of Charlevoix-Saguenay.

A new syndrome of autosomal recessive spastic ataxia has been isolated in the Charlevoix-Saguenay region of Quebec. This syndrome is remarkably homogeneous and includes: spasticity, dysarthria, distal muscle wasting, foot deformities, truncal ataxia, absence of sensory evoked potentials in the lower limbs, retinal striation reminiscent of early Leber's atrophy and the frequent presence (57%) of a prolapse of the mitral valve. Biochemically, many cases show impaired pyruvate oxidation, others have hyperbilirubinaemia and some have low serum beta-lipoproteins and HDL apoproteins. These features are similar to those found in typical Friedreich's ataxia.

Adolescent↗
PubMed1978

Clinical and electronystagmographic findings in Friedreich's ataxia.

A thorough investigation of vestibular function has been carried out in 16 patients with typical Friedreich's ataxia. Electronystagmography and caloric tests revealed a number of inconstant abnormalities. Most abnormal findings were related to ocular dysmetria, disorganized pursuit and square waves.

Adolescent↗