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Biomedical subjects

M Richard

Publications and source records attributed to M Richard.

At least 145 records · Page 8Linked to original sources
PubMed1984

[Anterior ligamentoplasty of the knee under arthroscopic control].

In the technique reported here an anterior cruciate ligament of the knee made of Dacron is inserted under arthroscopy, thus avoiding the usual wide tissue damage and delay in recovery. The very small incisions make it possible to install the prosthesis within an isometric, and therefore reliable, framework. Dacron is used alone for patients who underwent several unsuccessful operations on the knee, and Dacron wrapped in fascia lata, as suggested by Mansat, for patients operated upon for the first time. The results are very encouraging, with no post-operative complications, but the future of this technique will depend on the discovery of a better prosthetic material. This approach to reconstruction of the cruciate ligament might be considered a breakthrough in the treatment of chronic laxity of the knee.

Arthroscopy↗
PubMed1984

Glycosyltransferase activities in the rat intestinal mucosa: comparison between standard commercial and semi-synthetic diets.

Two groups of rats were fed either a commercial (C group) or a semi-synthetic (S group) diet of very similar quantitative composition, which induce similar growth in the animals. Glycosyltransferase activities are very different in the two groups: fucosyltransferase is lower in S group than in C group, regardless of the expression of the results (specific activity versus protein or DNA). The other activities (galactosyl-, N-acetylglucosaminyl-, N-acetylgalactosaminyltransferases) are modified when expressed versus DNA content; N-acetylneuraminyltransferase specific activity is not altered. Since the weight of mucosa is significantly lower in the S group than in the C group, all the total activities are decreased in the S group. The fucosylation process is further characterized by partial purification of the enzyme and study of the synthesis of GDP-fucose. In each case, interfering reactions (glycosyl-nucleotide pyrophosphatases and proteinases) are controlled. The results give evidence that glycosyltransferases are very sensitive to the qualitative composition of the diet.

Animals↗
PubMed1983

Conformational changes and possible structure of the oxoglutarate translocator of rat-heart mitochondria revealed by the kinetic study of malate and oxoglutarate uptake.

Initial rates of the exchanges [14C]malateout:malatein, ([14C]oxoglutarate + malate)out:malatein and ([14C]malate + oxoglutarate)out:malatein catalysed by the oxoglutarate carrier of rat-heart mitochondria have been studied under conditions where internal and external substrates may be varied. It is shown that contrary to external oxoglutarate which induces a conformational change of the translocator subunit to which it binds, external malate does not induce conformational changes during its binding and is a Michaelian substrate. The study of the effect of external malate on the rate of oxoglutarate uptake shows that external malate and external oxoglutarate are competitive. External oxoglutarate affects the catalytic rate constant of malate uptake in a modulated way. After substrate binding, the exchange reaction between an external dicarboxylate and an internal dicarboxylate is accompanied by conformational changes. The particular form of the rate equation strongly suggests that during a first step the external substrate bound to an external binding subunit at the external surface of the membrane, and the internal substrate bound to an internal binding subunit at the internal surface of the membrane, are transferred to a catalytic subunit (channel?) deeper in the membrane. Two models, one with a single channel, and the other with several associated channels, are proposed. It is demonstrated that a binding subunit which has transferred its substrate to a catalytic subunit is left in a conformation which does not depend on the substrate that has 'passed through it'. It is also demonstrated that all the catalytic subunits are identical. These theoretical deductions allow a simple description of the complicated effect that external oxoglutarate has on the rate of malate uptake. The fact that all the external binding subunits are equivalent regarding external malate binding and that all the catalytic subunits are identical support the view that the mitochondrial preparation contains a single species of oxoglutarate translocator and not an isozymic mixture.

Animals↗
PubMed1982

Impaired glycosylation in liver microsomes of orotic-acid-fed rats.

In rats fed orotic acid, the incorporation in liver subcellular fractions of sugars injected intraperitonealy is altered only for mannose, but not for fucose or galactose. Direct determinations of several glycosyltransferases are done in smooth and rough microsomes: fucosyl-, glactosyl-, N-acetylglucosaminyltransferase activities are at quite similar levels in normal and fatty livers. By contrast, sialyltransferase activity is increased (+50%) in smooth microsomes of fatty livers, while mannosyltransferase activity is inhibited by 30%. These alterations are not caused by interfering reactions (pyrophosphatases or proteases). For the mannosyltransferase activity, the inhibition is found in the dolichylphosphorylmannose intermediates. Kinetic studies suggest that there is deficiency of both enzyme and endogenous dolichyl phosphate.

Animals↗
PubMed1982

[Clinical symptoms of mitral valve prolapse. Treatment with metoprolol (author's transl)].

Twelve patients with symptomatic mitral valve prolapse were given metoprolol. The efficacy of the drug was evaluated on clinical improvement and changes in echocardiograms, exercise testing and 24 h ambulatory electrocardiograms. The efficacy of metoprolol was remarkable on palpitations and cardiac arrhythmias recorded on ambulatory electrocardiograms.

Adolescent↗
PubMed1982

Characterization of a mannosyl-lipid compound of microsomal fractions of rat pancreas and influence of diet.

1. High-starch diet induces an activation of rat pancreatic microsomal mannosyl-transferase activity as compared with a standard diet or a high-fat diet. 2. This increase is found in a mannose-containing lipid which is identified as a dolichyl-phosphoryl-mannose on the criteria of DEAE-cellulose chromatography, alkaline and acid hydrolysis, thin-layer chromatography and identity of this endogenous product with the [14C]mannose-containing product synthesized in presence of exogenous dolichyl-monophosphate added to the incubation medium. 3. Kinetic parameters (Km and Vmax) of the enzyme versus polyprenic acceptor are not modified by the diet. 4. The results indicate that the activation of the mannose transfer is principally due to an increase of the polyprenic endogenous acceptor by the high-starch diet.

Animals↗
PubMed1981

[Kinetic parameters of a soluble purified intestinal fucosyl-transferase].

The soluble fucosyl-transferase of the rat small intestinal mucosa was purified by passing through a Sephadex G-100 column, then resolved in two isoenzymes F1 (pHi = 4,47) and F2 (pHi = 4,96) by isoelectric focusing. The use in the first step of DEAE-cellulose instead of Sephadex G-100 leads to another component F3 (pHi = 8,70). Kinetic parameters (KM et Vm) for the three isoenzymes are given. The enzymatic mechanism seems to be a bi-bi random type for the three isoenzymes, and F3 appears as the most active species.

Animals↗
PubMed1981

Biosynthesis of glycoproteins in the intestinal mucosa. II. Influence of diets.

To determine the effect of diets on the biosynthesis of glycoproteins in the intestinal mucosa, male Sprague-Dawley rats were fed, ad libitum, high-carbohydrate high-fat and high-protein diets. In in vivo methodology, the animals from each dietary group received an intraperitoneal injection of [14C]-fucose, or [14C]-galactose or [14C]-glucosamine. Incorporated radioactivity was detected in the different subcellular fractions. In in vitro methodology, five glycosyl-transferases were studied on microsomes and cell sap. In vivo, only the high-fat diet induces a decrease in the incorporation of [14C]-glucosamine in the macromolecules. In vitro, only the fucosyl-transferase activity is modified by several diets: as compared with an increase in the activity of the control with the age of the animals, high-protein diet induces a slight activation after 2 weeks of diet, while high-carbohydrate and particularly high-fat diets inhibit the enzyme activity. The inhibition is the same when high-fat diet consists of either oil mixture or triolein or oleic acid or linoleic acid and becomes significant with a supplementation rate of 10%.

Animals↗
PubMed1981

[Mechanism of lipid inhibitory effect on intestinal fucosyl-transferase in the rat].

High-fat diets decrease microsomic and soluble fucosyl-transferase activities in rat intestinal mucosa. This inhibition is not due to qualitative (pHi) or quantitative (relative activities) changes ion three isoenzymes, nor is it caused by alterations in the kinetic behaviour of these enzymes (Km, V). It is also not due to a direct effect of the fatty acids on the enzyme activities. It seems reasonable to suggest that a decreased biosynthesis of the fucosyl-transferase occurs as a result of the high-fat diets.

Animals↗
PubMed1979

Common exposure outbreak of gastroenteritis due to type 2 rotavirus with high secondary attack rate within families.

A sharp outbreak of gastroenteritis associated with human rotavirus type 2 involved not only all of nine infants and young children in a playgroup but also seven of 10 parents and grandparents studied. The source of the outbreak appeared to be two non-playgroup siblings. Six of 11 individuals studied shed human rotavirus type 2, and each of seven from whom paired sera were obtained developed a type 2 sero-response. Overall, evidence of infection with rotavirus type 2 was demonstrated in 10 of 11 individuals by detection of virus in stools and/or a serologic response in an enzyme-linked immunosorbent assay.

Antibodies, Viral↗
PubMed1979

[Recent progress in immunologic technics for the diagnosis of systemic mycoses].

The new immunological techniques used for the diagnosis of systemic mycoses are very specific. Purified antigens are now available and new methods allow the detection of various classes of specific antibodies. Precipitation tests, such as bidimensional electrophoresis and electroimmunodiffusion, are compared with passive agglutination tests; radioimmunoassay and enzyme immunoassays are analyzed. The value and utilization of cellular immunity and various other tests are discussed.

Agglutination Tests↗
PubMed1978

Study of nuclear mannosyl-transferase: lipids intermediates.

Mannosyl-transferase of rat liver nuclei catalyzed the transfer of mannose, from GDP-mannose, to endogeneous lipids and proteins. Two solubility-different glycolipids were characterized: a mannosyl-phosphoryl-dolichol and an oligosaccharide-lipid. The labeling of the two lipids was consistent with a role in mannose transfer to nuclear glycoproteins, but not according to the Lennarz' scheme.

Animals↗