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Biomedical subjects

M Caron

Publications and source records attributed to M Caron.

At least 127 records · Page 7Linked to original sources
PubMed1983

Further evidence for a role of carbohydrates in insulin binding: studies in lectin-purified receptors.

Purification of liver membrane insulin receptors on concanavalin A- and ricin I-lectin columns gave a 15-fold enrichment in the insulin binding capacity per milligram of protein. Final receptor and protein recoveries were 53 and 3.8% respectively. Lectin-purification increased the receptor affinity for insulin, as indicated by a left-ward shift in the binding competition curve and a steeper slope in the Scatchard plot. Lectin-purification increased the receptor sensitivity towards the glycosidic probes. The maximal effects of beta-galactosidase, ricin I (galactose-binding lectin) and alpha-mannosidase were markedly amplified: 80, 90 and 60% inhibition, versus 45, 40 and 15% with particulate membranes. The limulus polyphemus (LPA) and wheat germ (WGA) agglutinins (sialic acid- and N-acetyl-glucosaminyl-binding lectins) became effective in modifying the insulin binding: 45 and 80% inhibition, respectively. The effects were dose-dependent, reversed by the monosaccharide competitors (lectin effects) and unrelated to the state of receptor occupancy. These findings indicate that, within the hormone recognition area, peptide chains containing galactose, mannose and N-acetyl-glucosamine are strictly required for insulin-receptor interaction and suggest that change in the receptor affinity is related to the role of carbohydrate in insulin binding.

Animals↗
PubMed1983

Single oral dose of ornidazole in women with vaginal trichomoniasis.

Fifty-nine women with trichomonal vaginitis were randomly allocated to receive treatment with a single oral dose of either 0.5, 1.0, or 1.5 g of ornidazole. One week after treatment, a parasitologic cure was observed in 100% of patients treated with 1.5 g, in 95% of patients treated with 1.0 g, and in 65% of patients given 0.5 g. At the one-month follow-up visit, the cure rate remained at 100% for the 1.5-g dose group but dropped to 85 and 45% in the 1.0- and 0.5-g dose groups, respectively. The disappearance of symptomatic complaints was also dose related: the clinical cure was 100, 85, and 40% at the first follow-up visit and 89, 80, and 30% at the second follow-up visit. Adverse effects of mild or moderate severity were reported by 13 patients. These were encountered mostly in the 1.5- and the 1.0-g dose groups. The most frequent adverse effects were dizziness and gastrointestinal distress. Laboratory safety test did not reveal any significant toxicity. This study confirms that single-dose treatment of trichomoniasis with an oral dose of 1.5 or 1.0 g of ornidazole is effective and well tolerated.

Adult↗
PubMed1982

Ultraviolet difference spectroscopy study of peanut lectin binding to Mono- and disaccharides.

Ultraviolet difference spectroscopy was used to study the interaction of peanut (Arachis hypogaea) lectin with complementary carbohydrates. A correlation was observed between variations of ultraviolet spectra during the binding of sugars to the lectin and the specificity and the strength of the binding. The association constant, free energy, enthalpy and entropy for peanut lectin-lactose interactions were calculated over the temperature range 10-30 degrees C. The binding constants for 10 mono- and disaccharides containing a D-galactopyranosyl or a D-talopyranosyl residue were calculated. Comparing their effectiveness to interact with peanut lectin, methyl alpha-D-galactopyranoside appeared to have a more marked affinity than lactose; D-galacturonic acid and methyl 7-deoxy-D-glycero-beta-D-galacto-heptopyranoside had no measurable affinity; the other sugars showed a lower affinity than lactose. The correlations between these differences and the conformations of the sugars obtained by X-ray analysis are discussed.

Binding Sites↗
PubMed1982

[Laser nephelometry for the quantitative determination of the interaction between peanut lectins and asialoglycoproteins].

The reaction of precipitation between peanut lectin and human serum desialylated glycoproteins was measured by means of laser nephelometry. Such a study can be used for the interactions with a purified asialoglycoprotein or with a whole serum. So, nephelometry allows investigations of abnormal or modified circulated molecules in a number of pathological situations.

Arachis↗
PubMed1982

[Biological importance of the reactions between lectins and glycoconjugates in man].

Glucidic structures are now widely shown to be responsible of many recognition phenomenons. The biological efficiency of cellular membrane associated receptors depends on their stereospecific interactions with ligands. Glucidic structures are implicated in the interactions occurring between lectins and glycoconjugates. Although the knowledge about human lectins is still limited, such activities are now widely obvious for several cells: --erythrocytes: hemagglutin activity of glycophorin; --lymphocytes: Ts and NK cells; --platelets: plasma membrane and cell secreted lectins; --hepatic cells: lectins of hepatocytes and Kupffer cells; --muscular cells: galactose and heparin inhibitable lectins; --cells of human glomerular basement membrane: N-acetylosamines and N-acetyl neuraminic acid inhibitable lectins. To this list may be added the cytoagglutinating activity of fibronectin involved in cell-cell, cell-molecule or molecule-molecule interactions. The importance of lectinic agglutinins may be emphasized for several fundamental physiological mechanisms involved in molecular and cellular recognition: defenses against infection, coagulation, aging.

Adult↗
PubMed1982

[Traumatic etiology of Kienboeck's disease. (Perilunate subluxations and semilunate necrosis)].

The authors have studied the incidence of lunate necrosis in 110 perilunate dislocations. Twenty-one cases (19%) developed a necrosis. The classification into three types, according to the amount of damage to the perilunar ligaments, is of prognostic value. There is no risk of necrosis in type 1, 17% in type II, and 50% in type III. An associated fracture of the scaphoid does not modify the risk. In neglected lesions, reduction of the lunate dislocation should be attempted, even at a late date, the risk of necrosis then being 50%. Surgical reduction increases the risk of secondary necrosis to a greater extent than does orthopedic treatment, but it is generally use in the most complex cases too. The authors advocate a closed reduction with percutaneous pin fixation.

Adolescent↗
PubMed1981

Identification of liver cell membrane galactoglycoproteins involved in the process of insulin binding.

The glycoproteinic nature of the insulin receptor was indicated using two different approaches: 1. [125I] insulin binding to soluble receptors from mouse liver was inhibited by digestion with beta-galactosidase or pretreatment with Ricinus communis I or concanavalin A. An other enzyme (neuraminidase) and lectins (wheat germ agglutinin, Dolichos biflorus) did not affect the binding reaction. These data confirmed that insulin directly interacts with the galactoglycoproteins of liver membranes. 2. The galactose oxidase-sodium boro[3H] hydride technique, previously used for labeling accessible membrane galactoglycoproteins, was again utilized to discern the components that interact with insulin. When liver membranes were equilibrated with 10-7 M insulin prior to labeling, the SDS gel radioactive profiles were specifically modified with two galactoglycoprotein of apparent molecular sizes 195 000 and 145 000, compatible with their participation in the insulin binding interaction. Membrane pretreatment with beta-galactosidase or Sophora japonica lectin reduced the labeling in most peaks, thus supporting the argument for labeling sensitivity. Preincubation of membranes with 10-7 M proinsulin slightly hindered labeling, while pretreatment with 10-7 M glucagon was ineffective, suggesting a specificity of the insulin effect. These data indicate that glycoprotein nature of the insulin receptor for two reasons: alteration of insulin binding after modification of the galactoglycoproteins, and alteration of galactoglycoprotein labeling after insulin binding. Two galactoglycoproteins, with apparent molecular weights 145 000 and 195 000, respectively, were identified and they are suggested to have insulin binding properties.

Animals↗
PubMed1981

Further characterization of the insulin receptor glycosidic moiety in rat adipocytes.

Simultaneous or sequential treatment of rat adipocytes with neuraminidase plus beta-galactosidase decreased insulin binding by 43%. No modification was observed with either enzyme individually. alpha-Mannosidase enhanced insulin binding (38%), whereas beta-N-acetylglucosaminidase and alpha-L-fucosidase were ineffective. Lectins that interact with galactose (Ricinus communis I, RCAI), mannose, Lens culinaris agglutinin (LCA), Concanavalin A (Con A) or N-acetylglucosamine (wheat-germ agglutinin, WGA) decreased insulin binding by 43, 57, 59 and 85% respectively. Lectin inhibition was dose-dependent, saturable and prevented by specific monosaccharides. RCAI, LCA, Con A and WGA decreased the insulin dissociation process by 45, 90, 78 and 84% respectively. Lectins specific for sialic acid, terminal galactose, N-acetylgalactosamine or fucose (Limulus polyphemus, peanut, soybean and Ulex I agglutinins) did not modify either insulin binding or dissociation. These results indicate involvement of penultimate D-galactose, internal N-acetyl-D-glucosamine and D-mannose residues in both processes. They suggest that, in rat adipocytes, a glycosidic moiety participates in the insulin-receptor interaction through N-linked oligosaccharides of the 'complex type'.

Acetylglucosaminidase↗
PubMed1980

Comparative evaluation of carprofen and indomethacin in rheumatoid patients.

Thirty-six patients with definite or classical rheumatoid arthritis were studied in a 6-week double-blind parallel trial. They were randomly divided into three groups and received either carprofen stepwise 150, 200, and 250 mg/day, carprofen 350, 400, and 450 mg/day or indomethacin 100 mg/day. Classical methods and parameters for evaluating the disease activity of rheumatoid arthritis were used. A large panel of laboratory tests were also involved in the assessment of toxicity. Although the incidence of adverse effects was similar for both drugs, cutaneous and gastrointestinal symptoms were more frequent with carprofen than with indomethacin, whereas central nervous system reactions were elicited more often with the latter drugs. For most of the efficacy variables studied, the carprofen high dosage regimen at weeks 5 and 6 was shown statistically superior or at least not different from the indomethacin group; both of these were superior to the carprofen low dosage regimen.

Anti-Arrhythmia Agents↗
PubMed1979

A rapid method for the purification of antibody--enzyme conjugates.

A method is described for a rapid and efficient separation of enzyme-labelled antibodies from the free enzyme following the coupling reaction. A single passage of the reaction mixture on a protein A--Sepharose CL-4B column gave a sharp separation of the free enzyme from the conjugate.

Antibodies↗
PubMed1978

Involvement of glycoconjugates in insulin-receptor interactions. Studies in liver plasma membranes of control and diabetic mice.

The involvement of glycoconjugates in the insulin-receptor interactions in mouse liver is tested by digestions of membranes with various enzymes. Trypsin decreased the binding of [125I]insulin to liver membranes. After digestion with beta-galactosidase no ""high affinity'' receptor sites could be detected. The effects observed with plant lectins confirm the involvement of galactoconjugates in the insulin binding process. Sophora japonica and Ricinus communis lectins (with galactose specificity) and concanavalin A largely inhibit the binding process of insulin and those effects concern the ""high affinity'' receptor sites. Other lectins (wheat germ agglutinin, Dolichos) and enzymes (alpha-L-fucosidase, beta-N-acetyl-hexosaminidase and neuraminidase) are without effect on insulin binding. Comparative studies performed on diabetic mouse liver membrane (KK mice), previously characterized by decreased number of insulin receptors, are in good agreement with qualitatively similar receptor sites in both non-diabetic (control) and diabetic mice. Effects of enzymes and lectins yielded same results as compared to control membranes. Plasma membrane proteins and glycoproteins in both types of mouse are indistinguishable with respect to enzymic and chemical analysis. Sodium dodecyl sulphate acrylamide gel electrophoresis shows identical patterns. Moreover, the decrease in the number of insulin receptors is easily reversed with diet restriction. These data are consistent with the similarity of receptor sites in control and diabetic liver membrane.

Animals↗