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Biomedical subjects

D Gros

Publications and source records attributed to D Gros.

At least 73 records · Page 4Linked to original sources
PubMed1980

Pinocytotic function of the membrane vesicles, or caveolae, in heart muscle cells.

The structure of membrane vesicles present in the sinus node, the atrium, and the ventricular cells of rabbits and mice was investigated. The results described in this study support the idea that membrane vesicles are not pinocytotic vesicles, but structural components of the membrane that increase the sarcolemmal surface area. That is the reason why we prefer to call them caveolae. Why these caveolae are much more abundant in sinus node cells and in Purkinje fibers, as shown by Mobley and Page (1972), than in working myocardium is still unknown.

Animals↗
PubMed1979

The plasma membrane of leading pacemaker cells in the rabbit sinus node. A qualitative and quantitative ultrastructural analysis.

We studied the fine structure of the plasma membrane of electrophysiologically identified leading pacemaker cells from the rabbit sinus node, using both ultrathin sections of fixed tissue and replicas of freeze-cleaved material. We found that differences exist between sinus node and working myocardial membranes, but these are only quantitative. The caveolae or sarcolemmal invaginations are present in very large numbers; they increase the surface area of the plasma membrane by about 100%. The small macular nexuses that are present represent 0.2% of the membrane surface area. Nexuses are therefore about 10 times less numerous in leading sinus node cells than in working myocardium cells. A single equivalent electrical representation of the sinus node shows, nevertheless, that an appreciable electrical coupling may be expected.

Animals↗
PubMed1978

Formation and growth of gap junctions in mouse myocardium during ontogenesis: a freeze-cleave study.

The freeze-cleave technique demonstrates the presence of gap junctions at early stages of mouse cardiac muscle ontogenesis. The formation and growth of these junctions were studied at 4 stages of development: 10, 14, 18 days post-coitum (dpc) and at the adult stage. The diverse aspects of the gap junctions are interpreted as different steps in their formation. The first indication of this formation seems to be the presence of linear arrays of 9-nm particles on PF faces. At one end of these arrays a small aggregate of particles appears which acts as nucleation site and grows by incorporating individual gap particles and/or linear arrays. Nexuses with arms and/or central particle-free zones would represent intermediate steps in the formation of junctions. The largest nexuses could be formed by fusion of smaller ones and/or by accretion of gap particles. Analysis of the size distribution of gap junctions shows their growth during their development. At 10 dpc the surface area (S) of nexuses ranges from 0.1 to 3 x 10(-2) micrometer2, at 14 dpc from 0.1 to 15 x 10(-2) micrometer2, at 18 dpc from 0.1 to 26 x 10(-2) micrometer2, and at the adult stage from 0.1 to 54 x 10(-2) micrometer2. The percentage of large nexuses (Sgreater than 0.5 x 10(-2) micrometer2) steadily increases from 10 dpc to the adult stage. Fixation by glutaraldehyde before glycerol infiltration does not induce any modification in the size distribution of adult heart gap junctions.

Animals↗
PubMed1977

[Results of radical radiotherapy in breast cancer].

In 17790 examinations over a 5-year period, 1174 breast carcinomas have been detected and treated in the Department of Senology, University Hospital, Strasbourg, France. 467 carcinomas were treated by radiotherapy alone. Five-year survival has been studied. Over half of the carcinomas treated were T3 and T4-sized. Overall survival is 46%.

Breast Neoplasms↗
PubMed1977

Ultrastructural visualization of cellular carbohydrate components by means of lectins on ultrathin glycol methacrylate sections.

A method for the visualization of cellular carbohydrate components by both light and electron microscopy using lectins on glycol methacrylate sections is proposed. This method, which is an application of the lectin-peroxidase affinity technique, solves the problem of limited penetration when it is attempted to demonstrated lectins receptors within the tissue block. Following partial dissolution of glycol methacrylate from thin sections using alcohol, they are incubated successively with lectin (Concanavalin A or wheat germ agglutinin), horseradish peroxidase (Sigma, type II), 3-3' diaminobenzidine and H2O2 and then with OsO4-Different kinds of tissues and cells have been used to test the method: mouse myocardium, rat epididymis, a protozoon Gregarina blaberae and the bacterium Escherichia coli. The localization of carbohydrate residues deomonstrated by this method within the different tissues and cells is consistent with the findings from other published studies. Controls have been performed (i.e., omission of the lectin, lectin and its inhibitor) and these demonstrate the specificity of the method.

Animals↗
PubMed1976

Early development of gap junctions between the mouse embryonic myocardial cells. A freeze-etching study.

Using the freeze-etch technique, nexuses have been shown to exist at a very early stage in developing mouse hearts (10 dpc). At this time they are rare, but become more progressively frequent and extensive at 12 and 14 dpc. Special arrangements of particles progressively observed on the fracture faces PF (linear arrays, small associated groups of linear arrays, then hexagonal arrays with 'arms' formed by linear clusters) suggest that in ontogenesis the gap junctions may be built up by successive aggregation of the linear arrays of particles.

Animals↗
PubMed1976

Lysogenization by bacteriophage lambda IV inhibition of phage DNA synthesis by the products of genes cII and cIII.

In direct measurements of phage lambda DNA synthesis, we have detected an inhibition caused by the cII and cIII gene products. This inhibition was more clearly observed when P amber phages were grown in a permissive host, presumably because of the limitation in DNA synthesis due to uncomplete suppression. The inhibition takes place in cells infected at high multiplicity, but not in cells infected at low multiplicity. To explain these findings, we propose a model in which the bacterial population is heterogeneous with respect to its ability to support phage DNA synthesis. An initial limitation caused by host factors would be amplified by the action of the cII and cIII products, at high multiplicity only, and the resulting inhibition would be essential in the "choice" towards lysogeny.

Chromosome Mapping↗
PubMed1975

The coating of mouse myocardial cells. A cytochemical electron microscopical study.

The coating of mouse myocardial cells has been investigated with a variety of cytochemical methods. The coating of the surface membrane gives a positive reaction with ruthenium red, colloidal thorium, phosphotungstic acid (PTA) at low pH, silver methenamine after periodic oxidation (PA-silver technique) and with silver proteinate after periodic oxidation and thiocarbohydrazide treatment (PA-TCH-silver technique). The coating of the T system gives almost similar results. The nexuses do not react with PTA nor with the PA-silver and PA-TCH-silver techniques, but they are strongly stained with ruthenium red which reveals periodic structures in their gaps. The specificities of the colloidal thorium technique and PAT staining have been tested by chemical treatments (methylation, acetylation, saponification), enzymatic digestions (pronase, trypsin, hyaluronidase, neuraminidase) and carbohydrate extractions (with 0.1 N NaOH and 0.05 M H2SO4). These cytochemical data indicate, considering the specificity of the reactions, that the coating of the membrane surface and the T system contains polyanionic groups. A part of them, at least, would belong to a carbohydrate-containing material (glycoproteins), whereas at the level of nexuses the sugar residues would probably be absent.

Animals↗
PubMed1974

Function of individual 30S subunit proteins of Escherichia coli. Effect of specific immunoglobulin fragments (Fab) on activities of ribosomal decoding sites.

Specific anti-30S protein immunoglobulin G fragments (Fab) were used to determine the contribution of each of the 30S ribosomal proteins to: (1) polyphenylalanine synthesis, (2) initiation factor-dependent binding of fMet-tRNA, (3) T-factor-dependent binding of phenylalanyl-tRNA, and (4) fixation of radioactive dihydrostreptomycin. Twenty of the 21 possible antibodies (antibody against S17 excepted) were used. In conditions where all the 30S proteins were accessible to Fabs, all of these monovalent antibodies strongly inhibited polyphenylalanine synthesis in vitro. Antibodies against S4, S6, S7, S12, S15, and S16, however, showed a weaker effect.30S proteins can be classified into four categories by their contributions to the function of sites "A" and "P": class I appears nonessential for tRNA positioning at either site (S4, S7, S15, and S16); class II includes proteins whose role in initiation is critical (S2, S5, S6, S12, and S13); class III (S8, S9, S11, and S18) corresponds to proteins whose blockade prevents internal (elongation factor Tudependent) positioning; and class IV includes entities that are essential for activities of both "A" and "P" sites (S1, S3, S10, S14, S19, S20, and S21). Dihydrostreptomycin fixation to the 30S or 70S ribosomes was inhibited by antibodies against S1, S10, S11, S18, S19, S20, and S21, but only weakly by the anti-S12 (Str A protein) Fab. The significance of these results is discussed in relation to 30S protein function, heterogeneity, and topography.

Antigen-Antibody Reactions↗