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Biomedical subjects

J Biguet

Publications and source records attributed to J Biguet.

At least 19 recordsLinked to original sources
PubMed1983

Endoprotease in Plasmodium yoelii nigeriensis.

1. P. yoelli nigeriensis has an acid endoprotease (cathepsin D) and an endoarylamidase. 2. The acid endoprotease is specific towards haemogloblin. It is found in 2 molecular forms, of molecular weight 100,000 and 50,000. It is inhibited by hematin and pepsatin. 3. In mouse normal red blood cells we find an acid protease having physico-chemical properties similar to those of the enzyme present in P. yoelii nigeriensis extracts, except as regards the pHi. 4. In parasite extracts there exists an enzyme active on the synthesis substrate N-acetyl alanine 4 nitro anilide. The main properties of this enzyme have been determined. 5. This enzyme must be also involved in the mechanism of haemoglobin degradation.

Aminopeptidases↗
PubMed1983

Antigenic variations of Candida albicans in vivo and in vitro--relationships between P antigens and serotypes.

Serum samples from patients with candidosis and from rabbits experimentally infected with serotype B C. albicans strains consistently showed higher antibody titers against Candida strains with serotype A antigens than strains with serotype B antigens, in indirect fluorescent antibody tests. When sera from rabbits infected with C. albicans serotype B strains were absorbed with blastospores of the homologous strain they continued to react against strains of C. albicans serotype A and a C. tropicalis strain with serotype A antigens. Serotype A-specific antisera reacted against tissue forms of C. albicans serotype B in vivo and against serotype B germ tubes, but not their parent blastospores, in vitro. These findings suggest that C. albicans B serotype cells may sometimes express, in vitro or in vivo, one or several antigens so far considered as specific of serotype A. The results have implications for the classical concept of C. albicans serotypes and for the serological diagnosis of candidosis in relation with the previously described strain P variable antigens.

Agglutination Tests↗
PubMed1981

[An ultrastructural study of spermatogenesis in Trichinella spiralis Owen 1835 (Nématode Trichuroide) (author's transl)].

The ultrastructural study of spermatogenesis in T. spiralis demonstrated the main characteristics of the male germ cells in the class Nematoda, i.e. lack of flagella, lack of reconstitution of the nuclear envelope after the meiotic divisions, and atypical structure of the centriole. The spermatozoon of T. spiralis was compared with previous classifications of the nematoda spermatozoa.

Animals↗
PubMed1981

Localization of chitin in the cell wall of Candida albicans by means of wheat germ agglutinin. Fluorescence and ultrastructural studies.

Cytochemical localization of wheat germ agglutinin binding sites in the cell wall of Candida albicans was investigated with fluorescence and electron microscopy. Various analytical techniques were employed in order to obtain a good penetration of the cytochemical markers, glycosylated horseradish peroxidase or glycosylated ferritin. In blastospores sectioned by cryostatic methods, a weak and continuous labelling of the blastospore periphery was observed with peroxidase, whereas bud scars and inner cell wall areas were labelled with ferritin. Following enzymatic treatment with pronase whose efficiency was followed by the periodic acid-thiocarbohydrazide -- Silver proteinate technique, the inner cell wall layers of bud are strongly stained with both fluorescein and the reactions products of peroxidase. After pronase-chitinase treatment, fluorescence was observed only in the mother cell wall. Finally, ultrathin glycol methacrylate sections showed a labelling both in inner and outer layers. All these results suggest that chitin was essentially distributed in the inner wall layers near the plasmalemma and in a smaller amount in outer wall layers. On the basis of the present findings, a hypothesis of wall assembly is proposed.

Binding Sites↗
PubMed1981

[Contribution to the study of nervous system in larval and adult forms of Schistosoma mansoni Sambon, 1907 (Trematoda Digenea). II. Role of serotonine and dopamine (author's transl)].

This study provides details concerning the localization and role of 5-HT and DA in Schistosoma: 1) 3H-5HT is incorporated selectively by the nerve fibers containing dense granules measuring 820 +/- 20 A (type 2 granules), combined at times with other structures; the presence of "cold" dopamine in the environment does not alter the incorporation; 2) 3H-DA is also incorporated in vitro by the nerve fibers and occasionally by the muscle fibers of the adult Schistosoma; 3) neither the intraovular miracidium, the first and second generation sporocystes, nor the intrasporocystic cercariae appear to incorporate the 3H-5-HT or the 3H-DA, under our working conditions. The two amines are, however, incorporated by the hepatopancreas of Biomphalaria glabrata and the 3H-5-HT produced marking on certain neuromuscular zones of the tentacle.

Animals↗
PubMed1980

[Effect of glucose and nitrogen concentrations on the morphology of Candida albicans and the formation of chlamydospores in synthetic culture media].

Candida albicans was grown in the darkness, at 28 degrees C, in a synthetic medium in which glucose and nitrogen concentrations were varied. Numeric appraisal of the chlamydospore index was possible only in the medium where glucose concentration was 0,08 g/1 or less. When the glucose concentration raised, pseudomycelial thalli bore numerous chlamydospores but sometimes also chains of cells with a dense granular content. These thalli bud yeast cells which separate and bud again in the medium. The different morphological aspects of the cultures are decribed, illustrated and classified according to the glucose and nitrogen concentration of the medium.

Ammonium Sulfate↗
PubMed1980

Experimental study of resistance to infection by Trichophyton mentagrophytes: demonstration of memory skin cells.

The mechanisms governing the development of local immunity in experimental dermatophytosis were studied by injecting intravenously trichophytin in guinea pigs cured of a prior Trichophyton mentagrophytes infestation. Dermal cell modifications were observed which were greater in the healed zones than in those not affected during the prior dermatophyte inoculation. These modifications included lymphocyte activation and accumulation and an accumulation of basophilic leukocytes. These observations suggest that after an acute dermatophyte infection heals, immunocompetent cells remain which are more numerous at the sites of lesions and that these cells would be responsible for the increased rate of elimination of the fungus during a reinfection. This hypothesis is discussed in the framework of the relationships observed in dermatophyte infections between delayed type hypersensitivity and resistance.

Animals↗
PubMed1980

Production of Eremofortins A, B, and C Relative to Formation of PR Toxin by Penicillium roqueforti.

The production of various eremophilane-type sesquiterpenes by Penicillium roqueforti strains has allowed us to propose a biochemical pathway for PR toxin synthesis. A time-course study of P. roqueforti metabolite production by high-performance liquid chromatography was performed to check this hypothetical pathway. The results obtained suggested that eremofortin C was the direct precursor of PR toxin in the P. roqueforti cell. Attempts to determine the amount of PR toxin in the mycelium failed. It was shown that the absence of PR toxin in mycelium was due to its instability during the extraction procedure.

Journal Article↗
PubMed1980

[Changes of serum lipoproteins during the course of human malaria (author's transl)].

Triacylglycerides (TAG), total cholesterol (TC) and serum lipoproteins (SLP) were studied during the course of 12 cases of human malaria and one case of simian inui malaria. The erythrocytic schizogony induced quickly an increase of TAG, a decrease of TC and modifications of SLP such an increase of VLDL parallel with a decrease or a disappearance of HDL. These modifications, always clear-cut, were not correlated with the intensity of parasitaemia or the species of Plasmodium. They were transient but longer than those described in connection with experimental rodent malaria. The changes of HDL could be associated with defective triglyceride removal of the plasma compartment due to an inhibition of the lipoprotein lipase induced by the parasite.

Animals↗
PubMed1979

[Cytochemical and ultrastructural studies of the cell wall of Candida albicans (author's transl)].

The ultrastructural localization of polysaccharides in the cell wall of Candida albicans was carried out by means of Concanavalin A on glycol methacrylate ultrathin sections. The sections were incubated successively with horseradish peroxydase, 3-3' diaminobenzidine and H2O2, for revealing the binding sites of the lectin. This method allowed us to localize mannan, since Concanavalin A does not react with other polysaccharides of the C. albicans cell wall. In these conditions mannan was found to be located in two continuous reactive layers at the periphery of blastospores cell wall. The results are discussed in relation with those obtained by another method using the polysaccharide detection technique described by Thiery (PATAg).

Candida albicans↗
PubMed1979

[Partial characterization of 2 extracellular aminopeptidases (arylamidases) from the dermatophyte Keratinomyces ajelloi].

Two aminopeptidases AP1 and AP2 have been isolated from Keratinomyces ajelloi filtrates. The molecular weight is about 27 000 for AP1 and 23 000 for AP2. Both aminopeptidases present maximum activity at pH 9.35 but 50 p. 100 of maximum activity is observed between pH 7.5 and pH 8.5. Km values measured at pH 9.35 with L-leucine-p-nitroanilide as substrate are 0.38 X 10(-3) M for AP1 and 0.43 X 10(-3) M for AP2. kcat at the same pH are 63.6 sec.-1 for AP-1 and 62.8 sec-1 for AP2. Both aminopeptidases are inhibited by mercuric chloride, o-phenanthroline, dithiothreitol and 2-mercaptoethanol. Some of their characters make them similar to Streptomyces griseus pronase aminopeptidases.

Aminopeptidases↗
PubMed1979

[Parasitic adaptation phenomena of pathogenic fungi in human and veterinary medicine].

The pathogen species involved in medical and veterinary mycology can be divided into three categories according to their level of increasing adaptation to parasitism. Only the third category includes a few species (some dermatophytes) which can be regarded as genuine parasites. The opportunistic fungi belong to the first or the first two the third categories according to the given definition. The various possible factors of preadaptation or adaptation to parasitic life (physical factors, biochemical factors, avoidance of the immunological pressure and ecological factors) are discussed. Except for the species belonging to the first category the probably are efficient only if the host does not react normally.

Adaptation, Physiological↗