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Biomedical subjects

G Renault

Publications and source records attributed to G Renault.

46 records · Page 3Linked to original sources
PubMed1980

The effect of the tumour promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) on UV- and MNNG-induced sister chromatid exchanges in mammalian cells.

The induction of sister chromatid exchanges (SCE) by the tumour promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA) has been studied in V79 Chinese hamster cells comparing control untreated cells with either UV-irradiation or MNNG-treated cells. In untreated cells TPA induced SCE at a very low concentration. An increase of approximately 50% over the level of spontaneous SCE formation was observed. In UV-irradiated cells, TPA, when present after the UV-irradiation, significantly enhanced UV-induced SCE formation, more SCE being induced than the expected sum of SCE formed by the separate treatments. TPA also enhanced MNNG-induced SCE but only when it was present for 28 h before, and not after, the MNNG-treatment. The protease inhibitor antipain fully inhibited TPA-induced SCE but did not inhibit UV-induced SCE. When UV-irradiated cells were treated with both TPA and antipain the enhanced UV-induced SCE induction was only partly inhibited by antipain, showing that TPA is responsible for two independent effects, both leading to SCE formation. These results are discussed in relation to the hypothesis that tumour promotion by TPA may depend on the enhancement of mitotic recombination leading to the segregation of a mutational event.

Animals↗
PubMed1978

[Induction of sister chromatid exchanges in vivo in bone marrow cells of AKR mice].

Induction of sister chromatid exchanges (SCEs) in bone-marrow cells of AKR Mice receiving in vivo four drugs well-known for their mutagenesis activity has been tested. A decreasing activity in SCE was shown by the drugs tested in the order cyclophosphamide, procarbazine, methylmethane sulfonate and diethylnitrosamine. This technique presents an encouraging method for testing the effect of chemical agents in vivo.

Alkylating Agents↗
PubMed1975

[Immunologic changes and infections in alcoholic cirrhosis].

The authors explored humoral and cellular immunity in 50 cases of alcoholic cirrhosis. The levels of the three serum immunoglobulins were greater than normal. IgM was significantly higher. The levels of antipolio antibodies (types I, II and III) were significantly higher in cirrhosis than in controls. The antistreptolysin and antistaphylolysin titers showed that the differences between levels found in cirrhosis and in controls were not significant. After taking the Sabin polio vaccine, variations in antipolio antibodies remained within normal limits, considering the high levels noted before taking the vaccine. Total serum complement was normal in 90% of the estimtions carried out. The results of the intradermal reactions were dissociated. Tuberculin skin tests were negative in 35% of cases of cirrhosis and in 14.3% of controls. In skin tests for candida and streptococcal antigen, differences between cirrhotics and controls were not significant. The absolute figure for blood lymphocytes per mm-3 was, in half the cases, less than normal.

Alcoholism↗
PubMedDate not supplied

SV40-based shuttle viruses.

We summarize in this paper the advantages of the shuttle virus system. These SV40-based vectors exhibit the unique properties of being packaged as SV40 pseudo-virions and of being able to infect host cells. Using these transient vectors, we show that their replication can be regulated in some monkey cell lines, in such a way that either low or very high amounts of plasmid DNA can be obtained. The stability of these infectious shuttle vectors in different conditions is analyzed by rescuing them in E. coli, using various gene mutation targets. Moreover, we describe a new series of vectors which can be produced as single-stranded DNA in bacteria. They allow the transfection of a plasmid genome into mammalian cells, as either single-stranded or double-stranded DNA.

Animals↗
PubMedDate not supplied

From simian virus 40 to transient shuttle vectors in mutagenesis studies.

Exogenous DNA probes are frequently used to study mutagenesis in mammalian cells. Experimental protocols utilizing simian virus 40 (SV40) and transient shuttle vectors able to replicate in mammalian cells as well as in bacteria are described. The main interests and the limits of the 2 genetic assays are discussed from results obtained with both systems. Despite some minor discrepancies, results obtained are very similar using either method. The complementarity of the 2 assays will allow a better comprehension of the mechanisms by which mutations may arise in mammalian cells.

Genetic Vectors↗
PubMedDate not supplied

Distribution of ultraviolet-induced lesions in simian virus 40 DNA.

In order to analyze the molecular mechanisms of mutagenesis in mammalian cells, we devised an analytical assay using Simian Virus 40 as biological probe. To study the possible correlations between the distribution of the lesions on the treated DNA and the distribution of mutations, we have located and quantified the lesions induced by ultraviolet light (254 nm) on a SV40 DNA fragment. At a fluence of 2,000 J/m2, our results show that the formation frequency of thymine-thymine dimers (TT) is three to four times higher than the formation frequency of the other types of dimers (TC, CT, CC). On the other hand, the formation frequency of a dimer is influenced by the adjacent sequence. In particular, a pyrimidine in the 5' position of a thymine-thymine dimer enhances its formation frequency. At the dose used the formation frequency of the pyrimidine (6-4) pyrimidone photoproducts is twenty times less than the formation frequency of pyrimidine dimers. This paper shows the distribution of the major lesions induced by UV-light on a defined fragment of SV40 genome after UV irradiation. This work is necessary to get an insight into the molecular mechanisms of UV-mutagenesis.

Base Sequence↗