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Biomedical subjects

G Dandrifosse

Publications and source records attributed to G Dandrifosse.

At least 55 records · Page 3Linked to original sources
PubMed1984

Determination of thiamine and thiamine phosphates in excitable tissues as thiochrome derivatives by reversed-phase high-performance liquid chromatography on octadecyl silica.

The analysis of thiamine and thiamine phosphates by high-performance liquid chromatography owes its high sensitivity to the fluorescent derivatives or thiochromes obtained by chemical oxidation in alkaline medium. The possibility of performing precolumn oxidation with potassium ferricyanide instead of using the hazardous cyanogen bromide has been investigated. The derivatization step has been optimized with respect to the following parameters: concentration of alkali and oxidant, presence of methanol and stability of the thiochromes . A gradient separation with 25 mM phosphate buffer (pH 8.4) and methanol as mobile phase components and an octadecyl silica column as stationary phase has been set up. The analytical run takes 14 min with the following elution order: thiochrome triphosphate, thiochrome pyrophosphate, thiochrome monophosphate and thiochrome. The minimum detectable amount is 0.05 pmol. The method was found suitable for the determination of thiamine compounds in excitable tissues such as nerves and electric organs as well as in proteins extracted from membranes of these organs. It may be useful to study the role of thiamine in the electrical activity of these tissues at the molecular level.

Animals↗
PubMed1984

Phosphate derivatives of thiamine and Na+ channel in conducting membranes.

The results show that thiamine derivatives are copurified with the specific proteins forming the Na+ channel in conducting membranes. Therefore, thiamine derivatives could well play a specific role in the molecular aspects of bioelectrogenesis , an interpretation that could help explain the neurological symptoms observed in human pathology as well as in animals experimentally rendered deficient in vitamin B1.

Animals↗
PubMed1984

Diamine oxidase and disaccharidase activities in small intestinal biopsies of children.

A relationship between disaccharidase and diamine oxidase (DAO) activities was looked for by measuring these enzyme activities in histologically normal small intestinal biopsies of 18 children. The range for disaccharidase activities expressed in U g-1 wet weight was 0.1-5.7, 7.1-36.7, and 2.3-8.5 for lactase, maltase, and sucrase, respectively. The range for DAO activities expressed in nmol h-1 g-1 wet weight was 202-974. Significant correlations were found between disaccharidase and DAO activities (lactase versus DAO: n = 17, r = 0.80, P less than 0.001; maltase versus DAO: n = 18, r = 0.70, P less than 0.001; sucrase versus DAO: n = 18, r = 0.55, P less than 0.05). Our results further support the hypothesis that DAO is a marker of small intestinal functional integrity in children.

Amine Oxidase (Copper-Containing)↗
PubMed1984

Binding of [3H]ethylenediamine di-tetrodotoxin to its solubilized receptor from excitable tissues. Binding measurements by rapid gel-filtration and receptor stabilization by phosphatidylcholine.

The molecular study of bioelectrogenesis requires the purification of the membrane proteins involved in the Na-channel electrical activity. This complex biological structure contains various binding sites for different classes of neurotoxins. Labelled forms of the blocking agent, tetrodotoxin, are used to identified and quantified the solubilized membrane proteins during the purification. Such a specific probe was synthetized in our laboratory and this work reports the experimental set-up of the binding technique. A fast-gel-filtration method has been optimized with respect to column design, centrifugation time and speed and, delay between sample application and column centrifugation.

Animals↗
PubMed1982

Purification of muscle acyl-CoA dehydrogenases extracted from Astacus fluviatilis pallipes.

1. Three acyl-CoA dehydrogenases were purified from muscles of Astacus fluviatilis. 2. The electrophoretic pattern of these enzymes was close to the one reported in the case of the same proteins coming from mammals. 3. Each of the acyl-CoA dehydrogenases extracted showed a great specificity of substrate. 4. These enzymes had no activity when tested in the absence of a protein purified from the crayfish muscles, which has the same electrophoretic pattern as the electron transferring protein of mammals.

Ammonium Sulfate↗
PubMed1980

Protein phosphorylation and sodium conductance in nerve membrane.

High molecular weight proteins extracted from the walking nerves of the shore crab (Carcinus maenas) exhibit a cycle of phosphorylation-dephosphorylation that is influenced by neurotropic compounds and inorganic ions. The net phosphorylation state of the proteins is increased in the presence of K+ ions and decreased with Na+ ions. In the absence of Mg2+ there is no phosphorylation. Ca2+ ions at low concentrations are necessary for optimal phosphorylation. At high concentration (above 0.1 mM), Ca2+ ions are inhibitory. Neurotropic compounds generally inhibit the phosphorylation process. More specifically, tetrodotoxin and veratridine, depending on the ionic composition of the medium, have opposite effects on the phosphorylation process, a result in agreement with their known physiological action. It is suggested that the high molecular weight components thus identified are part of the sodium permeation sites and that the conductance state of those sites is controlled by a phosphorylation process.

Action Potentials↗
PubMed1975

Transport of amylase across the apical membrane of the pancreatic exocrine cells. Quantitative analysis of zymogen granules.

The number or the size of the zymogen granules was calculated in a determined volume slice of pigeon pancreas and in a total cellular fraction of zymogen granules isolated from a part of this organ having the same volume. The obtained values were not significantly different. These results are discussed in relation to the mechanism of digestive enzyme secretion. They confirm that amylase can be transported molecule by molecule across the intact apical membrane of the pancreatic exocrine cells.

Amylases↗