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Biomedical subjects

M Arnaud

Publications and source records attributed to M Arnaud.

At least 91 records · Page 5Linked to original sources
PubMed1983

Effects of 5'deoxy-5'-methylthioadenosine on the metabolism of S-adenosyl methionine.

The treatment of transformed rat cells with micromolar amounts of 5'deoxy 5'methyl thioadenosine induces rapid effects on the rate of methylation of DNA concomitantly with alterations of intracellular pools of S-adenosyl methionine and S-adenosyl homocysteine. Pulse chase labelling experiments indicate that 5'deoxy 5'methylthioadenosine does not inhibit the degradation of S-adenosyl homocysteine but inhibits the consumption of S-adenosyl methionine. In vitro transmethylation assays performed with heterologous DNA show that low doses of the thioethernucleoside do not significantly affect the DNA methyltransferase activity of cellular extracts. The biological role of 5'deoxy 5'methylthioadenosine, a natural molecule formed during the synthesis of polyamines is discussed.

Adenosine↗
PubMed1983

[Yersinia enterocolitica and pseudotuberculosis reactive arthritis with antinuclear antibodies. 4 cases].

Antinuclear antibodies (ANA) were demonstrated in four patients (2 male, 2 female) with reactive arthritis (RA) due to Yersinia enterocolitica (YE) and Yersinia pseudotuberculosis (YPT). Changes in ANA titres and serologic tests were not correlated. The two patients are HLA B27 positive. Polysaccharides could be partly responsible for Yersinia antigenicity. The presence of ANA in chronic forms of RA due to Yersinia warrants discussion.

Antibodies, Antinuclear↗
PubMed1982

In vitro and in vivo cytotoxicity of 6 amino-5-formyl-methylamino-1,3-dimethyl uracil, a uracilic metabolite of caffeine.

The in vitro cytotoxicity of 6 amino-5 formylmethylamino-1,3 dimethyluracil (ADMU) a major metabolite of caffeine in rats was studied by cell counts or [3H]thymidine incorporation in the murine Lewis lung carcinoma (3LL) and L929 fibroblast cells and in the human E cell line derived from an ovarian carcinoma. Unlike 5-fluorouracil (5FU) which was markedly cytotoxic, ADMU concentrations up to 60 micrograms/ml were devoid appreciable cytocidal action. Similarly, 1-10 micrograms 5FU markedly inhibited the blastogenic response of rat lymphocytes to PHA, whereas lymphoproliferation was not affected at ADMU concentrations up to 100 micrograms/ml. In vivo administration of ADMU (40 mg/kg, twice a day on day 1 to 3) to L1210 leukaemia-bearing mice caused a transient short-lasting reduction of tumour cell numbers only on day 6 after leukaemia inoculation.U

Animals↗
PubMed1978

Bacillus subtilis 168 genetic transformation mediated by outgrowing spores: necessity for cell contact.

Transforming activity released in sequential genetic order during the first synchronous cycle of DNA replication during outgrowth of spores of Bacillus subtilis 168 was investigated. A transformation assay was used consisting of outgrowing spores as DNA donors and multiply marked competent cells as recipients. DNA synthesis inhibitors known to stop DNA release were used during and subsequent to DNA transfer to recipient cells. The released DNA sedimented with the outgrowing cells after low-speed centrifugation, and it was discovered that markers released both early and late were resistant to up to 500 microgram of deoxyribonuclease per ml under conditions in which the transforming capacity of purified DNA was eliminated by 5 microgram of the nuclease per ml. Inaccessibility to deoxyribonuclease was increased and maintained during the transformation event while detergents and proteolytic attack did not expose the released chromosome to nuclease action. The results indicate that tight physical contact between outgrowing spores and competent cells is required for transformation in this system.

Bacillus subtilis↗
PubMed1970

Conditional mutants of meiosis in yeast.

Three temperature-sensitive mutants, spo1-1, spo2-1, and spo3-1, were characterized with respect to their behavior in sporulation medium at a restrictive temperature. The time of expression of the functions defective in the mutants was determined by temperature-shift experiments during the sporulation process. In addition, each mutant was examined for the following: (i) its ability to undergo the nuclear divisions of meiosis; (ii) deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein synthesis; (iii) protein turnover; and (iv) colony-forming ability after exposure to sporulation medium. Mutant spo1-1 is defective in a function which confers a temperature-sensitive period which extends over 32% of the sporulation cycle. The temperature-sensitive period of mutant spo2-1 occupies 34% of the cycle, whereas the temperature-sensitive period of mutant spo3-1 extends over 2% of the sporulation cycle. Cytological evidence indicates that all three mutants initiate but do not complete the meiotic nuclear divisions. The DNA content of sporulation cultures of mutants spo1-1 and spo3-1 did not increase to the wild-type level; DNA synthesis in spo2-1 was normal. All three strains exhibit a loss of colony-forming ability during incubation in sporulation medium at the restrictive temperature. RNA and protein synthesis and protein turnover occur in the mutants.

Adenine↗