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Biomedical subjects

M Charles

Publications and source records attributed to M Charles.

At least 55 records · Page 3Linked to original sources
PubMed1990

[Cysts of the thoracic canal. Apropos of a subclavicular site].

The authors report a case of cystic dilatation of the terminal portion of the thoracic duct which clinically corresponded to a swelling in the root of the left side of the neck. Pathogeny and evolutive mode of this exceptional affection are ill known. Echography and scanography show the cystic nature of the mass. Diagnosis is made by direct puncture which can prove the chylous nature of the content and permits the opacification of the cyst. Lymphography shows the type of junction with the thoracic duct.

Adolescent↗
PubMed1988

Accuracy of rotavirus diagnosis: modified genome electrophoresis versus electron microscopy.

530 human faecal samples were examined for the presence of rotavirus by electron microscopy (EM) and by a modified electrophoretic analysis of viral genome (PAGE). 516 stools gave identical results by both methods (97.4% agreement). The proportion of EM+, PAGE- samples (1/530) was significantly lower than the proportion of EM-, PAGE + samples (13/530) (P less than 0.01 with McNemar test). Relative sensitivity was 99.6% for PAGE and 95% for EM. False positive results could be excluded for each method because of the characteristic morphology of rotavirus particles (EM) and specificity of rotavirus electrophoretypes (PAGE). Discrepant cases were reexamined whenever possible and the causes of misdiagnosis are discussed.

Electrophoresis, Polyacrylamide Gel↗
PubMed1984

Immunological events in new onset diabetes.

Data from our laboratory are reviewed showing that both cell-mediated cytotoxicity, complement-dependent antibody-mediated cytotoxicity, antibody-dependent cellular cytotoxicity, and complement-augmented antibody-dependent cellular cytotoxicity may provide mechanisms which kill pancreatic islets during pathogenesis of insulin-dependent (type I) diabetes. Xenogenic test systems employing dispersed rat islet target cells were employed. Most of the findings were reversible during clinical remission of diabetes.

Animals↗
PubMed1982

Binding between immobilized anti-colipase purified antibodies and colipase. Radioimmunoassay of colipase from pig plasma and pancreatic juice.

Procedures for purification of porcine colipase II (Gly6-Gly89) and for obtaining purified anti-colipase antibodies are described. The interactions between antibodies immobilized on an Ultrogel AcA 22 column and colipase were investigated and colipase radioimmunoassay carried out. The immobilized antibody-colipase binding was preserved in the presence of mixed micelles, lipase, or both when added to the elution mixture. Bound colipase maintained its capability of interacting with mixed micelles, but not with lipase in either the presence or the absence of mixed micelles. It could be inferred that the antigenic site(s) is independent of the interfacial recognition site and close to the site of lipase recognition. Results are reported suggesting that one or both colipase histidyl residue-containing sequences are involved as antigenic determinant(s). Immunoreactive colipase, bound to a macromolecular protein complex, was found in the plasma of pig. This finding could be explained by an endocrine 'leakage' of colipase from the exocrine pancreatic cell rather than by passage through the intestinal mucosa.

Animals↗
PubMed1982

Pancreatic colipase: crystallographic and biochemical aspects.

A detailed study of the crystallization of hog and horse colipases has been undertaken. Several crystallographic varieties have been obtained and a 0.3-nm resolution structure determination is actually in progress. The sequence of the A form of horse colipase (one methionine) is given. From spectrophotometric experiments and sequence comparisons, the involvement of the aromatic residue in position 52 in the micelle binding site has been demonstrated.

Amino Acid Sequence↗
PubMed1982

Removal and addition of bile in the intestine, and pancreatic colipase activity in the pig: effect of a high-lipid diet.

The aim of the reported study was to investigate the effects of the removal and addition of bile in the intestine on the tissue pancreatic colipase of pigs fed a high-lipid diet (25% peanut oil). Experiments were carried out on fistulated pigs. In one group of animals, bile was removed for 8 days; in a second group an excess of bile was added in the intestine for 8 days. Results were compared to those obtained in pigs in which the collected bile was entirely returned. When bile was removed, the tissue enzyme activities of pancreatic lipase and colipase significantly decreased; the latter increased when bile was added in the intestine of pigs whose enterohepatic cycle was fully maintained.

Animals↗
PubMed1980

[Effect of bile salt excess in the duodenal lumen on the enzymatic equipment of pancreatic tissue in the pig].

This study reports the effect of long-term (8 days) addition of bile salts in the duodenal lumen of the pig in which the bile enterohepatic cycle was fully maintained. Seventeen pigs were fitted with permanent fistulae in the bile duct and the duodenum. The bile collected in 9 pigs was returned to the intestine, while that of the other 8 pigs was returned after a 30 p. 100 excess in bile salts, supplied by lyophilized porcine bile, had been added. At the end of the 8-day experimental period, the enzymes were determined in the fresh total pancreatic glands of all the pigs. The results showed no significant differences in lipase, colipase, amylase, chymotrypsin or trypsin activities in either group of animals. The existence of an in vivo relationship between bile salts and colipase secretions is hypothesized.

Amylases↗
PubMed1978

Adsorption and activation of pancreatic lipase at interfaces.

The first step of the lipase-catalyzed hydrolysis of insoluble long chain triglycerides is the adsorption of the enzyme to the interface. This adsorption, which is spontaneous when the interface is hydrophobic, is hindered by bile salts. Under these conditions, a small protein cofactor designated colipase adsorbs first and then anchors lipase at the interface. Interfacial adsorption enhances lipase activity, due, at least in part, to an acceleration of the rate-limiting deacylation step of the reaction. In this respect, lipase appears to be a most interesting model of an enzyme being activated by the presence of a lipid. The 3 steps of the heterogeneous catalysis induced by lipase, interfacial adsorption, interfacial activation and catalysis proper are under the control, respectively, of a serine hydroxyl group, a carboxyl and a histidine imidazole.

Adsorption↗
PubMed1976

Electrochemical characterization of immobilized NAD+.

Nicotinamide adenine dinucleotide (NAD+) has been covalently attached to alginic acid using carbodiimide coupling, thereby producing a macromolecular adduct of NAD, which can be rendered either soluble or insoluble by adjustment of pH. It was found that this NAD+-alginic acid complex was enzymatically active, and also that the oxidized form could be electrochemically reduced without loss in enzymatic activity. This NAD+ adduct has now also been polarographically characterized as to its two-step reduction waves, which are slightly shifted toward more cathodic potential as compared to free NAD+. When controlled electrolysis was conducted to reduce the bound NAD+ at the cathode, the NADH so formed by electrochemical action was found to be again oxidizable either enzymatically or electrochemically without loss in co-enzymatic function. The NADH adduct produced by electrochemical reduction of the NAD+ adduct has also been characterized by voltammetry.

Alginates↗
PubMed1976

Preparation and properties of soluble-insoluble nicotinamide coenzymes.

A soluble-insoluble form of nicotinamide adenine dinucleotide (NAD+), which can be rendered either soluble or insoluble by simply adjusting the pH, has been prepared by covalently coupling NAD to alginic acid using 1,2,7,8-diepoxyoctane. The NAD bound to the alginic acid showed the coenzymic function in the soluble state and could be collected for further use as precipitate by lowering the pH to below 3. Coupling soluble-insoluble coenzymes with insolubilized apoenzymes is possible in fluidized and fixed-bed reactors.

Chemical Phenomena↗
PubMed1976

Electrolytic regeneration of the reduced from the oxidized form of immobilized NAD.

A covalently bound adduct of nicotinamide adenine dinucleotide (NAD) with alginic acid has been found to be enzymatically active and to undergo electrochemical oxidation or reduction without significant loss of its enzymatic activity. The preparation of the adduct itself (from NAD+, alginic acid, and 1-cyclohexyl-3-(2-morpholinoethyl)-carbodiimide metho-p-toluenesulfonate) is also accomplished with substantially complete retention of enzymatic activity. This adduct has been converted from the oxidized to the reduced form by controlled potential electrolysis using mercury and stainless-steel electrodes. This electrolytically produced NADH complex could be oxidized again to the enzymatically active NAD+ complex by enzymatic reaction with the proton acceptor, 2,6-dichlorophenol indophenol, as catalyzed by diaphorase. Using this electrolytic method with immobilized NAD, it is now possible to carry out redox reactions in which NADH is enzymatically oxidized to NAD+, with the simultaneous electrolytic regeneration of the reduced form, NADH, from the oxidized form, NAD+, produced in the enzymatic reaction.

Electrolysis↗