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Biomedical subjects

M Richard

Publications and source records attributed to M Richard.

At least 109 records · Page 6Linked to original sources
PubMed1990

Glycosyltransferase activities in chondrocytes from osteoarthritic and normal human articular cartilage.

Six glycosyltransferases (mannosyl-, glucosyl-, N-acetyl-glucosaminyl-, galactosyl-, sialyl- and fucosyltransferases) are studied and characterized for their optimal conditions and their relations with interfering reactions (glycosyl-nucleotide pyrophosphatases, glycosidases and proteinases) in chondrocytes from osteoarthritic and normal human articular cartilage. Osteoarthritis induces increased activities for five glycosyl-transferases. The observed modifications are not explained by alterations in physico-chemical parameters of the enzymes or by intervention of glycosyl-nucleotide pyrophosphatases, glycosidases or proteolytic enzymes.

Cartilage, Articular↗
PubMed1990

Intestinal glycosyl-transferase activities. Nutritional regulation by a chemically-modified protein: methionyl-casein.

In order to estimate the effect of a chemically modified casein, glycosylation processes were studied in rats fed a diet containing this protein. Two groups of rats were fed either a methionyl-casein diet or a normal casein diet. The methionyl-casein was enriched in methionine by covalent linkage of this amino-acid. The nutritional data (growth, protein intake...) were not modified by the diet. The microsomal N-acetylgalactosaminyl- and fucosyl-transferase activities were unaffected by the diet. On the contrary, the soluble fucosyl-transferase activity was enhanced and the activation of fucose transfer in cytosol from methionyl-casein-diet fed rats disappeared after enzyme purification by DEAE-cellulose chromatography. The activation was not explained by changes in some interfering reactions (glycosyl-nucleotide pyrophosphatase, oxidase, protease activities).

Animals↗
PubMed1990

Histaminergic H1, serotoninergic, beta adrenergic and dopaminergic receptors in human osteoarthritic cartilage.

Using radioligand binding assays, histaminergic H1, serotoninergic, dopaminergic and Beta adrenergic receptors were studied in human normal and osteoarthritic cartilage. The four studied receptors were present in normal cartilage; serotoninergic, dopaminergic and Beta adrenergic receptors were significantly increased in osteoarthritic cartilage while histaminergic H1 receptors were significantly increased only in osteophytic cartilage. The results are consistent with a non specific activation of osteoarthritic chondrocytes.

Cartilage, Articular↗
PubMed1990

[Value of immunofixation for the typing of serum and urine monoclonal proteins].

Typing of monoclonal proteins can be performed, after screening by cellulose acetate electrophoresis, by immunoelectrophoresis (IEP) or immunofixation (IF). For sera, IF must be preferred to IEP because this methods is more sensitive and more easy to interpretate, particularly for small monoclonal components and biclonal abnormalities. For urine, patterns obtained by IF must be interpretated cautionaly because of the frequent polycondensed aspect of the non monoclonal light chains from tubular renal failures, and must be verified by a polyacrylamide agarose electrophoresis.

Antibodies, Monoclonal↗
PubMed1989

Glycosyltransferase activities in normal and leukaemic monocytic cells.

Glycosyltransferase activities were measured in normal monocytes and in leukaemic monoblasts. Biosynthesis of glycosylated derivatives of dolichyl-monophosphate, which act as intermediates in glycosylation, was measured. Transfer of mannose from GDP-mannose was greatly increased in leukaemic monoblasts. Galactosyltransferase activities, using endogenous protein acceptors, were increased in leukaemic cells of the monocytic lineage compared to normal cells. No significant difference was observed on specific exogenous glycoprotein acceptors. These selective increases of some glycosyltransferase activities in normal and leukaemic monocytic cells can be correlated either with different expression of specific carbohydrate structures or with changes in glycosylation regulation.

Biomarkers, Tumor↗
PubMed1989

Pattern of human chorionic gonadotropin binding in the polycystic ovary.

The histologic evolution of polycystic ovaries in the estradiol valerate-treated rat coincides with the development of a unique plasma pattern of luteinizing hormone. To assess the role of luteinizing hormone in polycystic ovaries, it is necessary to evaluate the luteinizing hormone sensitivity of the specific tissues in the polycystic ovary. Therefore, we examined the pattern of luteinizing hormone binding sites in polycystic ovaries. Rats at 4 or 8 weeks after estradiol valerate treatment each received an intrajugular injection of iodine 125-labeled human chorionic gonadotropin. Some rats also received a 1000-fold excess of unlabeled human chorionic gonadotropin in the same injection. Ovaries were prepared for autoradiography. Dense accumulations of grains occurred over the theca of normal and atretic secondary follicles in all ovaries and over clusters of secondary interstitial cells. The iodine label was variable over the typically hypertrophied theca of precystic follicles. The theca of definitive cysts showed little or no label. These results indicate that cyst formation coincides with the loss of luteinizing hormone/human chorionic gonadotropin binding to the affected follicles.

Animals↗
PubMed1989

Effects of tiaprofenic acid on interleukin 1, phospholipase A2 activity, prostaglandins, neutral protease, and collagenase activity in rheumatoid synovial fluid.

IL-1 and prostaglandin (PGE2, PGF2 alpha, TXB2) concentrations, PLA2 activity, neutral protease activity, and collagenase activity specific for types I and II collagen were determined in the SF of patients suffering from RA, before and after treatment with TA. Active and latent forms of protease and collagenases were regularly detected but were unrelated to IL-1, PLA2, and PGE2. TA induced a significant decrease in tested eicosanoids but IL-1, PLA2, and proteases were unchanged.

Adult↗
PubMed1989

Phospholipase A2 activity in human osteoarthritic cartilage.

Phospholipase A2 (PLA2) activity was measured in articular cartilage from normal and osteoarthritic (OA) human femoral heads. Protoglycanase and collagenase activity was determined in the same specimens using radiolabelled human proteoglycan subunit and type II collagen, respectively. Grossly normal and fibrillated OA cartilage samples showed a significant increase in PLA2 activity which was not found in osteophytic cartilage. PLA2 activity was found to be correlated with proteoglycanase but unrelated to collagenase activity. Tiaprofenic acid induced in vitro a concomitant increase in PLA2 and a decrease in proteoglycanase activity. PLA2 which may be activated by cytokines as well as mechanical factors is suggested as a key enzyme in chondrocyte metabolism regulation. Tiaprofenic acid is shown as a potential chondroprotective nonsteroidal anti-inflammatory drug.

Aged↗
PubMed1989

[A new marker in oncology. Assay of gangliosides bound to sialic acid].

Gangliosides are released from cells proliferating in serum and can be assayed by a LASA method. The authors report the assay method for sialic acid bound exclusively to glycosphingolipids (GASA method). They study the reliability and discuss the preliminary factors concerning this upper respiratory tract squamous cell marker.

Biomarkers, Tumor↗
PubMed1989

Tumor size-dependent elevations of serum gangliosides in patients with head and neck carcinomas.

Serum gangliosides were studied in 100 patients with benign or tumoral head and neck lesions. Whereas very few changes over the normal level were noticed in benign cases, 78% of patients with head and neck carcinomas had a significant elevation of serum gangliosides, mostly accounted for by GM3 and GD3. Such an increase was correlated with the observed tumor size, and the level of serum gangliosides returned to normal within one month after surgery. Follow-up of patients showed that further elevations of serum gangliosides were associated with relapses.

Biomarkers, Tumor↗
PubMed1988

Characterization of insulin-like growth factor I (IGF-I) receptors of human breast cancer cells.

Studies of binding of IGF-I to a plasma-membrane-enriched subcellular fraction prepared from MCF-7 human breast cancer cells reveal the presence of 0.2 pmols specific binding sites for this mitogen per mg membrane protein, with an equilibrium affinity constant of 1.45 nM-1. Competition studies with insulin, IGF-II, and an anti-IGF-I receptor antibody are consistent with the presence of specific IGF-I receptors, and SDS-PAGE showed binding to a 130 kDa subunit identical to that of receptors from human placenta. In addition, we show that IGF-I is more potent than estradiol and comparable to EGF in stimulating in vitro proliferation of MCF-7 cells, and that IGF-I-stimulated proliferation of these cells is inhibited by a blocking monoclonal antibody against the IGF-I receptor. These results demonstrate that IGF-I is an important mitogen for MCF-7 cells and that the mitogenic effect is mediated by specific IGF-I receptors.

Breast Neoplasms↗
PubMed1988

Associated norepinephrine loss following calcium-induced spinal paralysis.

A 10% calcium chloride solution or normal physiological saline was instilled onto the intact dorsal surface of the spinal cord via a specially constructed catheter-canopy system fixed above the T9 level in conscious rats. Within 5 min after calcium instillation rats developed flaccid paralysis of the lower limbs with sensory loss. Sensory loss was accompanied by abnormal or negative evoked potentials. Rats instilled with physiological or 10% sodium chloride remained normal. Rats were sacrificed at 1, 16 and 48 h post-calcium exposure and following full functional recovery from paralysis. Spinal cords were removed for histologic and high-performance liquid chromatography (HPLC) analysis. Histologic examination for catecholamines using SPG histofluorescence showed loss of catecholamine-containing varicosities in gray matter below calcium exposure which returned to normal levels upon sensorimotor recovery of hindlimbs about 14 days pce. Light microscopic examination of vascular permeability and general morphology of cord tissue axons and neurons remained normal in calcium and saline instilled rats. HPLC analysis of spinal cord below calcium exposure, also showed norepinephrine (NE) and 3-methoxy-4-hydroxyphenylglycol (MHPG) tissue level reductions which returned to normal upon sensorimotor recovery of paralysis about 2 weeks later. No significant changes were noted in dopamine or serotonin levels in any group. Our findings suggest an impairment of ascending and descending tract transmitter transport, specifically reflected in the noradrenergic bulbospinal pathway. The results implicate a neurofilament-microtubule disassembly in axonal cytoskeleton triggered by the sudden calcium influx.

Animals↗