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Biomedical subjects

M Huet

Publications and source records attributed to M Huet.

At least 55 records · Page 3Linked to original sources
PubMed1978

Glucorticoid resistance in murine lymphoma and thymoma lines.

The thymoma line W7 contains 30,000 dexamethasone-binding sites per cell and gives rise to glucocorticoid-resistant variants at a frequency less than 1.6 X 10(-9); the lymphoma S49 contains one-half that amount of receptor, is resistant to low concentrations of dexamethasone, and gives rise to fully resistant variants at high frequency. These results suggest that S49 is functionally haploid (r+/-) for a gene coding for the receptor while W7 appears diploid for that locus (r+/+). Derivatives of the W7 (r+/+) line, selected for resistance to low concentrations of dexamethasone, have the same properties as S49. These putative W7's (r+/-) give rise to the same types of receptor variants as S49 and in the same proportion; 80 to 90% are "receptorless" (r-) while 10 to 20% are "nuclear transfer defective" (nt-). A total of 127 variants resistant to high concentrations of dexamethasone were derived from the W7 (r+/+) line after mutagenesis. All are receptor variants but N-methyl-N'-nitro-N-nitrosoguanidine and ethyl methanesulfonate induce only 60 to 70% r- variants, confirming the presence of two r+ alleles in the parental line. Ultraviolet light induces a higher proportion (87%) of r+ variants, as expected from the introduction of breaks and deletions in DNA.

Animals↗
PubMed1976

Molecular forms of Electrophorus acetylcholinesterase. Molecular weight and composition.

Molecular weights for the series of six Electrophorus acetylcholinesterase forms have been determined either by the sedimentation-diffusion equilibrium method or, particularly in the case of the very scarce G' and G inches forms, from their Stokes radius and sedimentation coefficient values. Both methods are in excellent agreement. The results provide good evidence for the model previously proposed, G inches, G' and G containing one, two and four subunits, whereas A, C and D possess, in addition to respectively one, two and three tetrameric sets of such subunits, a structural element, the tail. Although the amino acid composition of 'tailed' and globular forms did not reveal any significant feature of this element, its mass, about 100 000 daltons, could be deduced from a comparison of molecular weights for the two classes of acetylcholinesterase forms. This value is in close agreement with electron microscopic data. The tail is thought to consist of three 30 000-dalton strands.

Acetylcholinesterase↗
PubMed1976

[Evaluation of meningococcal polysaccharide vaccines by the reduction of bacteremia in mice].

After peritoneal inoculation of live meningococci suspension to Mice immunized with homologous meningococcal polysaccharide, the level of bacteremia is considerably reduced in the group of Mice that has received the vaccine in comparison to the control group. This reaction is specific with polysaccharide A or C, and there is no cross reaction between the two. Under rigorous experimental conditions, the reduction of bacteremia can be quantified and thus the utilization of this method for the in vivo evaluation of meningococcal polysaccharide vaccines may be envisaged.

Animals↗
PubMed1976

[Heterotopic autotransplantation of the atrium in the rat. Effect on specific granules (author's transl)].

A technique for the autotransplantation of part of the right atrium in the rat kidney is described. The morphology of these grafts has been studied by light and electron microscopy at intervals varying from 15 to 346 days after transplantation. On light microscopy, the grafts show an organoid organization with a central cavity filled with blood surrounded by an endothelium around which concentric layers of cardiocytes are present. Electron microscopy reveals that the population of specific granules is not affected by transplantation. In the beginning, the cardiocytes show severe abnormalities of myofilaments, mitochondria and sarcoplasmic reticulum. The granular sarcoplasmic reticulum is much more abundant than in control cardiocytes. Most of these changes regress with time so that, after 346 days the transplanted cardiocytes appear almost normal. These experiments indicate that the specific granule population of atrial cardiocytes probably does not contain any appreciable amount of catecholamine and is not dependant on the nervous system or on a local stimulus.

Animals↗
PubMed1975

Factors affecting the molecular structure and the agglutinating ability of concanavalin A and other lectins.

Ultracentrifugation analyses were performed on lectins under varying conditions of pH, ionic strength and temperature. It has been demonstrated that the phytohemagglutinin from Phaseolus vulgaris, the wheat germ agglutinin and the soybean agglutinin are stable when these parameters are varied, whereas the concanavalin A molecule exhibits a striking reversible dimer-tetramer transition with variation in pH (from 6.0 to 7.2) and temperature (from 4 degrees up to 37 degrees C). It has also been demonstrated that, in agglutination experiments undertaken at different temperatures, cells do eventually aggregate with the first three lectins provided that incubation time is sufficient, whereas the concanavalin-A-induced agglutination was previously found to be temperature-sensitive. These results strongly suggest that the effect of temperature on agglutination by lectins may essentially be due to a structural transition of the lectin itself and nott only to modification of cell surface properties.

Agglutination↗
PubMed1975

Hemodynamic evaluation of patients with intrahepatic portal hypertension. Relationship between bleeding varices and the portohepatic gradient.

Between January 1970 and December 1974, 389 patients presenting an upper gastrointestinal hemorrhage had an emergency fiberoptic esophagogastroscopy at the time of bleeding. In 103 cases, esophageal and/or gastric varices were visualized and in 46 of these cases, bleeding originiated from varices. Hemodynamic data was available in 19 cases of intrahepatic portal hypertension who had bled from varices. Combined hepatic and umbilicoportal catherterization was perform in 17 cases whereas only hepatic vein catherterization was possible in 2. The portohepatic gradient (FPVP-FHVP or WHVP-FHVP) was utilized as an index of portal hypertension. In the 19 patients studied, the portohepatic gradient ranged from 12 to 24.5 mm Hg with a mean of 18.4 mm Hg; only one patient had a portohepatic gradient of less than 14.5 mm Hg. The present data strongly suggest that in intrahepatic portal hypertension, bleeding varices are observed only if significant portal hypertension exists. Hemodynamic studies may thus be helpful in evaluating bleeding patients with varices particularly when the origin of the bleeding cannot be determined at endoscopy. The finding of a portohepatic gradient of less than 12 mm Hg would strongly suggest that varices were not the source of bleeding and in these cases, shunt surgery should not be considered.

Adult↗
PubMed1975

[Role of the nervous system during the regeneration of an arm in a starfish: Asterina gibbosa Penn. (Echinodermata, Asteriidae)].

In Asterina gibbosa regeneration of a cut-off arm tip cannot occur if the radial nerve has been removed. This regeneration needs the presence of the oral nerve ring connected with the radial nerve intact up to the level of the wound tissues. The oral nerve ring can be considered as a central nervous system. Exposure of the radial nerve to irradiation induces a delay in regeneration. These data suggest there is a stimulation from the oral nerve ring up to the wound tissues. When the tissues involved in regeneration, except for the radial nerve, have been destroyed by irradiation, regeneration is inhibited. Stimulation by a healthy radial nerve is necessary to maintain differentiation and growth of the blasternal cells. The amount of blasternal growth and differentiation depends on the time when the radial nerve ceases to stimulate regeneration. The action of the nervous system is needed throughout the whole course of regeneration.

Animals↗
PubMed1975

Chemical nature of atrial specific granules.

The specific granules are argentafugic when ultrathin sections of Araldite-embedded atria are stained according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiery. The entire core of the atrial specific granules is moderately positive after ultrathin sections of glutaraldehyde-fixed, glycol methacrylate- (GMA-) embedded atria are stained with phosphotungstic acid at a low pH. A similar reaction is shown by the cell coat, intercalated discs, residual bodies (C-granules), and Z-discs, as well as by a very small portion of the Golgi complex. Analogous results are obtained with semithin sections of GMA- embedded atria stained according to the periodic acid-Schiff (PAS) technique. In ultrathin sections of GMA-embedded atria stained with dialyzed colloidal iron (DI), the cell coat of the cardiocytes is positive, unlike all the other cytoplasmic organelles. When ultrathin sections of GMA-embedded atria are incubated with proteolytic enzymes (pronase, pepsin, or trypsin), atrial specific granules and Z-bands and, to a much lesser degree, cell coat and sarcolemma are selectively digested. Proteins are also distinctly demonstrated in the paranuclear specific granules by a variety of histochemical techniques. These results indicate that atrial specific granules are rich in proteins and possess a weak complement of complex carbohydrates.

Animals↗
PubMed1975

The chemical nature of human atrial specific granules.

The nature of human auricular specific granules was assessed by a variety of cytochemical and histochemical methods. The specific granules were found to be argentaphobic when ultrathin sections of Araldite-embedded auricular appendages were stained according to the periodic acid-thiocarbohydrazide-silver proteinate technique of Thiery. The entire core of these granules was moderately positive after ultrathin sections of glutaraldehyde-fixed, glycol methacrylate (GMA)-embedded auricles were stained with phosphotungstic acid (PTA) at a low pH. A similar reaction was shown by the cell coat, residual bodies (C-granules), lysosomes, Z-discs as well as by a very small portion of the Golgi complex. Analogous results were obtained in semithin sections of GMA-embedded auricles stained by the periodic acid-Schiff (PAS) technique. Incubation of ultrathin sections (fixed in glutaraldehyde and embedded in GMA) with proteolytic enzymes (pronase, pepsin, trypsin, or alpha-chymotrypsin) elicited selective digestion of atrial specific granules and Z-bands and, to a much lesser degree, of the cell coat. It is concluded that human auricular specific granules, as in rat atrial cardiocytes, are composed mostly of proteins. In addition, these granules may contain complex carbohydrates.

Chemical Phenomena↗