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Biomedical subjects

J Renaud

Publications and source records attributed to J Renaud.

At least 37 records · Page 2Linked to original sources
PubMed1987

Endonuclease G: a (dG)n X (dC)n-specific DNase from higher eukaryotes.

An endonuclease activity (termed endonuclease G) that selectively cleaves DNA at (dG)n X (dC)n tracts has been partially purified from immature chicken erythrocyte nuclei. Sites where n greater than or equal to 9 are cleaved in a manner that resembles types II and III restriction nucleases. The nicking rate of the G-strand is 4- to 10-fold higher than that of the C-strand depending on the length of the (dG)n X (dC)n tract and/or nucleotide composition of the flanking sequences. Endonuclease G hydrolyzes (dG)24 X (dC)24 of supercoiled DNA in a bimodal way every 9-11 nucleotides, the maxima in one strand corresponding to minima in the opposite, suggesting that it binds preferentially to one side of the double helix. The nuclease produces 5' phosphomonoester ends and its activity is dependent on Mg2+ or Mn2+. The wide distribution and high relative activity of endonuclease G in a variety of tissues and species argues for a general role of the enzyme. The striking correlation between genetic instability and poly(dG) X poly(dC) tracts in DNA suggests that these sequences and endonuclease G are involved in recombination processes.

Animals↗
PubMed1987

Regulation of histone and beta A-globin gene expression during differentiation of chicken erythroid cells.

The expression of the genes for several histones and beta A-globin was examined in the chicken erythroid cells lineage. During the transition from CFU-(E) to the mature erythrocyte, histone H5 gradually increased fourfold in nuclei with little concomitant displacement of the H1 histones. This resulted in a 70% net increase in linker histone (H1 plus H5) content. The differential accumulation of H5 reflected (i) an increase in the transcriptional activity of the H5 gene occurring at the erythroblast stage, (ii) an apparent longer half-life of H5 mRNA, and (iii) a higher stability of the protein. Although the transcriptional activity of the histone genes (except H5) decreased with cell age, it was not tightly coupled to the S phase. On the other hand, the mRNA levels for these histones were tightly regulated during the cell cycle. Use of protein and DNA synthesis inhibitors indicated that the content of H5 mRNA was regulated at the posttranscriptional level by a control mechanism(s) differing from those for the other histones. Although the transcription rates of the H5 and beta A-globin genes were comparable, differential accumulation of beta A-globin mRNA led to a 30- to 170-fold-higher copy number of the beta A-globin mRNA as the cell matured.

Animals↗
PubMed1986

Fine analysis of the active H5 gene chromatin of chicken erythroid cells at different stages of differentiation.

We have analyzed the chromatin structure of a region that encompasses 14.4 X 10(3) base-pairs of the chicken histone H5 locus in adult erythroid cells at different stages of maturation. Seven of eight major lineage-specific DNase I-hypersensitive sites, some of which show complex substructure, were found in the flanking regions of the gene. The hypersensitivity of some of these sites is modulated during erythrocyte maturation in a way that parallels the transcriptional activity of the gene. DNase I, micrococcal nuclease, and S1 nuclease recognize the same regions, which differ from those cleaved by S1 on supercoiled plasmid DNA. This suggests that hypersensitivity of DNA in chromatin reflects a greater accessibility of the DNA rather than its altered conformation. The DNA sequence of some of the DNase I target sites contains repeated motifs, (T-C-C-C)2, (T-C-C)2, (T-G-G-G-G)2, which are found in the hypersensitive sites of other genes. Detailed analysis across sections of the H5 gene and flanking sequences revealed differences in the DNase I sensitivity of the different regions examined. Notably, the first one-third of the gene is more sensitive than the rest. The sequences downstream from the region where most RNA polymerases terminate transcription were found to be the most resistant.

Animals↗
PubMed1984

[Places and agents: the ethnic and sexual division of labor in Quebec from 1931 to 1981].

The socio-professional distribution of Quebec's total labor force has changed during the 20th century, as one can observe from the 1931-81 Canadian censuses that provide comparative occupation codes. As well, the sexual and ethnic composition of the labor force has changed substantially during this period. The authors analyze the manner in which these sexual and ethnic cleavages are, at various moments, called upon to assign agents to different places in the division of labor; in particular, it is a matter of seeing how the dominated groups, defined by these 2 cleavages, are used to fulfill the lower functions of the work hierarchy. The use of complex models of the linear log type makes it possible to distinguish, on the 1 hand, crude effects relating the reality experienced by sexual and ethnic groups in the labor force, and, on the other hand, the net effects corresponding to the more or less permanent, but less evident, rules which govern these groups' access to the various jobs.

Americas↗
PubMed1983

Genomic organization of the genes coding for the six main histones of the chicken: complete sequence of the H5 gene.

The organization of the genes coding for histones in the chicken has been examined, with special reference to that coding for the tissue-specific, developmentally regulated histone H5. Two recombinant phages containing sequences complementary to cloned H5 cDNA have been isolated from a genomic chicken library. The clones have been characterized by heteroduplex formation, restriction nuclease analysis, hybridization to cloned homologous histone gene probes, and DNA sequencing. Hybridization to genomic DNA has shown that there is only one copy of the H5 gene per haploid genome, whereas there are six to 11 copies of the genes for the other histones. Examination of 29 X 10(3) base-pairs of DNA sequences flanking the H5 gene has revealed the absence of any other histone genes which, although not tandemly reiterated, for the most part appear to reside in loosely organized clusters. The complete DNA sequence of the H5 gene and flanking regions, as well as the mapping of the 5'-end of its messenger RNA by primer extension with AMV reverse transcriptase, has shown that the gene has no introns and little homology to other histone genes, including those for H1.

Animals↗
PubMed1983

Histone synthesis by lymphocytes in G0 and G1.

Peripheral blood lymphocytes are a naturally occurring population of G0 cells which can be activated in vitro to grow and divide. Upon activation with phytohemagglutinin (PHA), they enter G1 and, after a 24-h lag, begin DNA replication (S phase). Using radioisotope labeling and gel electrophoresis of acid-soluble chromatin proteins, we investigated histone synthesis in G0, G1, and S phase cultures of human and pig lymphocytes. In G0 and G1 cultures, which have less than 0.1% S phase cells, all five histones are synthesized and are incorporated into chromatin in equimolar amounts. In G0 lymphocytes histone synthesis accounts for at least 6% of nuclear protein radioactivity, and the rate of synthesis is about 2-3% of that of S phase lymphocytes. In contrast to histone synthesis by S phase cultures, G0 and G1 histone synthesis was completely resistant to treatment with hydroxyurea.

Animals↗
PubMed1980

[Arterial complications of inguinal surgery: value of vein replacement in situ (author's transl)].

Two cases of arterial complications after inguinal hernia repair were revealed by a post-operative septic hemorragia and in the other case by a late intermittent claudication complicated by a distal emboly. Both were cured by replacement of the damaged artery with an autologous saphena. Twenty-three similar cases were found in literature. They were discovered either during operation, or post-operatively, or after recovery. In post-operative course, a late diagnosis in some cases lead to amputations or death. Actual treatment is arterial replacement by autologous vena because the length of arterial damagement and good resistance of vena in septic area. Prevention during inguinal hernia repair needs a correct exposure, the use of small needles and widening of the exposure in case of hemorragia.

Aged↗
PubMed1979

Biologically related iron-sulfur clusters as reaction centers. Reduction of acetylene to ethylene in systems based on [Fe4S4(SR)4]3-.

The possibility that clusters containing the Fe4S4 core unit found in a wide variety of proteins can effect reductive transformations of Fe-S enzyme substrates has been investigated using the reduced synthetic clusters [Fe4S4(SPh)4]3- and acetylene, an alternate nitrogenase substrate. The system [Fe4S4(SPh)4]3-/acetic acid/acetic anhydride in N-methylpyrollidinone at approximately 25 degrees was found to reduce acetylene homogeneously to ethylene, and in the presence of a deuterium source to afford as the principal stereochemical product cis-1,2-C2H2D2. No appreciable reduction was found using the oxidized cluster [Fe4S4(SPh)4]2-. The system is not catalytic and departs from the strict stoichiometry of the reaction, 2[Fe4S4(SPh)4]3- + C2H2 + 2H+ leads to 2 [Fe4S4(SPh)4]2- + C2H4, primarily because of a competing cluster oxidation reaction which could not be eliminated. Based on this reaction ca. 60% conversion of acetylene to ethylene was achieved. A reaction sequence based on absorption and 1H nmr spectral observations and product stereo-chemistry is suggested. The results demonstrate that biologically related, reduced Fe4S4 clusters can effect reduction of at least one Fe-S enzyme substrate, and raise the general possibility of substrate transformation with such clusters as reaction sites in biological systems.

Acetylene↗
PubMed1976

Messenger RNA induction of fast sodium ion channels in cultured cardiac myoblasts.

Incubation with adult heart messenger RNA caused the appearance of fast sodium ion channels in young myocardial cells whose development has been arrested in vitro. The induction was blocked by cycloheximide, indicating dependence on protein synthesis. Thus, cardiac myoblasts can be made to differentiate in vitro, and membrane properties can be altered by exogenous RNA.

Action Potentials↗
PubMed1976

Carcino-embryonic antigen activity in urine of patients with bladder carcinoma. Clinical evaluation of carcino-embryonic antigen. II.

This paper deals with the study of CEA levels in urine from healthy control subjects, of patients with bladder carcinoma or previous bladder carcinoma, and other groups of patients. In 53% of the patients with bladder carcinoma and without urinary infection, urinary CEA was increased. There were no false positive results. It is concluded that urinary CEA is a valuable aid in the detection of malignant tumour growth in the bladder. The results are compared with several tumour parameters, e.g. tumour size, stage of disease and histological parameters. Evidence is presented that CEA in infected urine is not produced by bacteria and that, like soluble vaginal excretory products, this substance has antigenic groupings in common with CEA from bladder tumours.

Adult↗
PubMed1976

Clinical significance of urinary carcino-embryonic antigen estimations during the follow-up of patients with bladder carcinoma or previous bladder carcinoma. Clinical evaluation of carcino-embryonic antigen, III.

Urinary carcino-embryonic antigen (CEA) was measured in a follow-up study of 101 bladder carcinoma patients. Urinary CEA estimation during follow-up appears to be of clinical value. Negative results can be interpreted only in relation to previously increased values. Positive results are of value in retrospect when combined with negative data, e.g. in evaluation of suspicious bladder changes and as an early indication of renewed tumour growth. Increased CEA levels in urines from patients with urinary infection rapidly decline once the infection is cured.

Adult↗