Search PubMed⌕ Search

Biomedical subjects

M Girard

Publications and source records attributed to M Girard.

At least 325 records · Page 18Linked to original sources
PubMed1976

In vitro synthesis of simian virus 40 DNA. I. Synthesis by a soluble extract from infected CV1 cells.

Simian Virus 40 (SV40) DNA replication was studied in vitro using cell free extracts prepared from SV40 infected CV1 cells. The cells were fractionated into a soluble cytoplasmic fraction and nuclei. The nuclei were lysed with high salt and used to prepare a soluble nuclear fraction. Both fractions displayed DNA polymerase activity as measured with activated calf thymus DNA. However, only the cytoplasmic fraction was active when SV40 DNA comonent I molecules were used as template. Under these conditions, the cytoplasmic extract was shown to catalyse the SV40 DNA dependent, in vitro incorporation of the four deoxyribonucleotides into DNA molecules which had, at both neutral and alkaline pH, the same sedimentation behavior as authentic SV40 DNA component I and component II molecules. Optimal Mg++ concentration was 5-8 mM. Incorporation of label into DNA component I molecules showed an initial lag of about 15 min., after which it was linear with time for up to 5 hrs at 32 degrees. Incorporation into DNA component II molecules proceeded without obvious lag and reached a plateau after approximately 2 hrs of incubation. It is concluded that the cytoplasmic extract supports the in vitro synthesis of SV40 DNA and that DNA component II molecules appear to be a precursor to DNA component I molecules in the reaction. Labeling of viral DNA molecules was highly dependent on ATP and on an ATP generating system. In the absence of ATP and of the energy generating system, incorporation occurred but both template and newly synthesized DNA molecules were extensively degraded.

Adenosine Triphosphate↗
PubMed1976

In vitro synthesis of simian virus 40 DNA. II. Evidence for a repair mechanism.

The technique of density labeling of DNA by BrdU was used to characterize the material synthesized in vitro by cytoplasmic extracts of SV40 infected cells incubated in the presence of simian virus 40 (SV40) DNA component I molecules (Girard et al, Biochimie, this volume). In a first experiment, the template was labeled beforehand in vivo using [14C]-BrdU, and the in vitro incubation was carried out in the presence of [3H]-dGTP and [3H]-dTTP. In a second experiment, the template was labeled in vivo with 32P, and the in vitro incubation was in the presence of [3H]-dGTP and BrdUTP. After digestion with the restriction endonuclease Hind II + III, the fragments from the end products of the reaction were analyzed by density gradient centrifugation, at pH 7 and pH 13. In both experiments the DNA product molecules had the same density as the resepctive DNA templates. Cellular enzymes seem to be responsible for this in vitro synthesis of DNA, since cytoplasmic extracts from uninfected cells were almost as active as those from SV40 infected cells. The system was proved efficient in the conversion of "open circular" molecules (component II DNA molecules) to covalently closed circular DNA molecules (relaxed component I molecules). The use of DNA complexed with histones did not impart viral specificity to the system. It is concluded that the cytoplasmic extract is only capable of supporting the repair synthesis of added viral DNA.

Bromodeoxyuridine↗
PubMed1976

[Clinical and anatomopathologic effect of Bisolvon in respiratory resuscitation].

N cyclohexyl-N-methyl-2 amino -3.5 dibromobenzyl, amine hydrochloride or Bisolvon is an alkaloid derived from vasicine whose fluidizing effects on bronchial secretions are well-known. This study which consisted in a randomization involved 40 patients that were being submitted to a respiratory reanimation, half of whom received Bisolvon intravenously. The patients were improved by the treatment with Bisolvon as can be seen from the following: - fewer bronchial aspirations; - less fluid secretions; - a decrease in alveolar cells; - an increase in bronchial cells; - a reduced increase in total mucus. These results evidence an original action ascribable to Bisolvon on the bronchial cell.

Bromhexine↗
PubMed1975

[Detection and determination of alpha-feto-protein in human serum. Use in hepato-gastroenterology].

The presence of alpha-foeto-protein (A.F.P.) was sought in the serum of 520 patients, suffering from various digestive disorders, using two methods: double immuno-diffusion and counter immuno-electrophoresis on cellogel--a more sensitive technique. A.F.P. was detected on 90 of the 520 patients. A.F.P. was measured by radial immunodiffusion or by electro-immunodiffusion on cellogel. Study of the values obtained in various kinds of hepatic disorders indicates that high levels (more than 10 mg/1) are seen almost solely in association with primary carcinoma of the liver, whilst lower levels (less than 10 mg/1) are found in the majority of hepatic disorders, without having any precise significance. The interest of the clinician should therefore be directed not towards the presence or absence of A.F.P. but to its level, which alone is significant.

Adenoma, Bile Duct↗
PubMed1975

[Coagglutination in continuous flow. Techniques and applications].

The principle of coagglutination, the specific agglutination of uncoated red cells by antibody coated ones was applied to the two conventional continuous flow agglutination systems (bromelin-methylcellulose and polybrene-Na-citrate). The technique was used to study a large number of allo- and auto-antibodies of various specificities as well as some drug related antibodies. The sensitivity of the technique proved not to be higher than that of similar systems using free antibodies. It was however shown to be still more economical and elegantly allowed to avoid manual absorption-elution steps prior to investigation of antibody or antigen specificity.

Antibody Specificity↗
PubMed1974

Viral DNA-RNA hybrids in cells infected with simian virus: the simian virus 40 transcriptional intermediates.

Brief labeling of cells infected with simian virus 40 with tritiated uridine resulted in the incorporation of part of the label into material that was soluble in 1 M NaCl and sensitive to KOH, with a buoyant density close to that of DNA. The properties of this material suggest that it represents single-stranded nascent molecules of messenger RNA of simian virus 40 hydrogen-bonded over a small portion of their length to viral DNA templates. The name "simian virus 40 transcriptional intermediate molecules" is suggested for these naturally occurring DNA.RNA hybrid molecules. The DNA in the hybrid seems to be in the form of replicative intermediate molecules.

Animals↗
PubMed1974

Mode of action of acid pH values on the development of vesicular stomatitis virus.

The effect of low pH's on the development of vesicular stomatitis virus (VSV) was studied. L cells infected with VSV were incubated at pH 6.6. A 99% inhibition in the yield of infectious particles was observed by comparison with the yield at pH 7.4. Such inhibition was not due to inhibition of viral RNA synthesis, since at pH 6.6 all the known species of VSV RNA molecules were synthesized. Furthermore, all the known species of VSV proteins were also synthesized. However, no viral particles nor nucleocapsids were detected. Raising the pH to 6.9 resulted in the appearance of nucleocapsids and viral particles, although the yield of infectious virus was still inhibited by 90%. The lack of infectivity of these pH 6.9 viral particles was correlated with their inability to promote primary transcription. The hypothesis that low pH's alter the correct positioning of the viral proteins into the cell membrane is presented.

Hydrogen-Ion Concentration↗
PubMed1973

Aspects of the encapsidation of simian virus 40 deoxyribonucleic acid.

Growing subcloned CV1-cells were infected with simian virus 40, and the time course of virus formation was determined. When infected cells were fractionated into cytoplasmic and nuclear fractions, most of the progeny virus particles were recovered in the cytoplasmic extract and not in the nuclei. This result was independent of the technique used for the preparation of nuclei and of the time after infection at which the extracts were prepared. Leakage of the virions from the nucleus occurred during the course of cell fractionation, suggesting that the nuclear membrane of the infected cells is damaged. Virions were found to accumulate in a nonlinear fashion, at the time when the number of viral deoxyribonucleic acid (DNA) molecules increases linearly with time after infection. This suggests that the size of the intracellular pool of capsid proteins increases constantly during the late phase of virus replication. Progeny viral DNA to become encapsidated is withdrawn at random from the pool of replicated DNA molecules.

Animals↗
PubMed1973

Replication of simian virus 40 deoxyribonucleic acid: analysis of the one-step growth cycle.

The time course of replication of simian virus 40 deoxyribonucleic acid (DNA) was investigated in growing monolayer cultures of subcloned CV1 cells. At multiplicities of infection of 30 to 60 plaque-forming units (PFU)/cell, first progeny DNA molecules (component 1) were detected by 10 hr after infection. During the following 10 to 12 hr, accumulation of virus DNA proceeded at ever increasing rates, albeit in a non-exponential fashion. The rate of synthesis then remained constant, until approximately the 40th hour postinfection, when DNA replication stopped. Under these conditions, the duration of the virus growth cycle was approximately 50 hr. The time needed for the synthesis of one DNA molecule was found to be approximately 15 min. At multiplicities of infection of 1 or less than 1 PFU/cell, the onset of the linear phase of DNA accumulation was delayed, but the final rate of DNA synthesis was the same, independent of the input multiplicity. This was taken as a proof that templates for the synthesis of viral DNA multiply in the cell during the early phase of replication. However, the probability for every replicated DNA molecule to become in turn replicative decreased constantly during that phase. This could be accounted for by assuming a limited number of replication sites in the infected cell.

Animals↗