Search PubMed⌕ Search

Biomedical subjects

C Hamelin

Publications and source records attributed to C Hamelin.

At least 55 records · Page 3Linked to original sources
PubMed1983

Efficient transfection of mammalian cells with viral DNA in optimal culture conditions.

Standard or newly developed DNA transfection procedures were compared for both innocuity and efficiency using simian virus 40 (SV40) DNA and monkey kidney (Vero) cells as an indicator system. Optimal results have been obtained by treating the delicate cell monolayers with a solution of glycerol before infection with DNA-calcium phosphate complexes.

Animals↗
PubMed1983

Unambiguous typing of canine adenovirus isolates by deoxyribonucleic acid restriction-endonuclease analysis.

Viral deoxyribonucleic acid extracted from a limited number of cells infected with canine adenovirus type 1 or type 2 was cleaved with several restriction endonucleases. Agarose gel electrophoresis of the limit digests showed stable differences between the canine adenovirus type 1 and type 2 cleavage patterns. Rapid and accurate typing of large numbers of clinical isolates may thus be done by deoxyribonucleic acid restriction-endonuclease analysis.

Adenoviridae↗
PubMed1982

Mammalian cells contain a DNA-recombining activity that can be dissociated from topoisomerase activity.

The role of the topoisomerase enzyme in DNA recombination was investigated by extracting chromosomal deoxyribonucleoproteins from a variety of cultured mammalian cells and assaying for the formation of recombinant DNA structures. Although each of the crude deoxyribonucleoprotein preparations contained topoisomerase activity, they did not all contain DNA-recombining activity. A distinct, perhaps novel, enzyme may therefore promote DNA recombination in these cell-free systems.

Animals↗
PubMed1982

[Isolation and characterization of E. coli B mutants sensitive or resistant to ozone].

Escherichia coli B strains, either more sensitive or resistant to ozone than wild-type (OZs or OZr), were obtained after mutagenesis. OZs strains carrying a mutation in ozrA or orzB, two genes located on both sides of malB, appeared as phenotypically different with regards to radiosensitivity and cellular filamentation. OZr strains, on the other hand, probably carry an allele of ozrA but were radioresistant and divided normally even with induction. A single gene (ozrA) thus seems to determine three levels of sensitivity to ozone, sensitivity to radiation and cellular filamentation in this organism. The possible involvement of a specific endonuclease in the repair of ozone-induced DNA lesions is considered.

Chromosome Mapping↗
PubMed1979

Nicking-closing enzyme is associated with SV40 DNA in vivo as a sodium dodecyl sulfate-resistant complex.

A fraction of the cellular nicking-closing (NC) enzyme cosediments with SV40 chromatin isolated after Triton X-100 treatment of infected cells nuclei. Extraction of viral DNA according to the Hirt procedure by treatment of infected cells with sodium dodecyl sulfate (SDS) followed by sedimentation in sucrose gradient to separate the DNA from the bulk of detergent also revealed NC activity associated with DNA. Reconstitution experiments showed that only prebinding of the NC enzyme to DNA protects it against irreversible inactivation by SDS. These results suggest that a fraction of the cellular NC activity is indeed associated with the viral chromosome in vivo.

Chromatin↗
PubMed1979

Concentration of human cytomegalovirus from large volumes of tissue culture fluids.

Three methods of pelleting, ultracentrifugation (95000 g for 60 min), precipitation with polyethylene glycol 6000 (5% v/v), and with ammonium sulphate (38% w/v), were used to concentrate human cytomegalovirus (CMV) from tissue culture fluids. Maximum recovery of infectious virus particles was obtained with the polyethylene glycol (PEG) method. The precipitating activity of PEG 6000 and PEG 20000 was then compared at different concentrations. The best results were obtained with PEG 6000 at a final concentration of 5% (v/v). Changes in pH or salt concentration, treatment of the concentrates with Pronase and long periods of time at 4 degrees C significantly reduced the number of biologically active CMV particles recovered by PEG precipitation.

Ammonium Sulfate↗
PubMed1978

Induction of deoxyribonucleic acid degradation in Escherichia coli by ozone.

Cell survival and deoxyribonucleic acid (DNA) degradation wave measured for wild-type Escherichia coli B251 cells after exposure to different concentrations of ozone. The results show that extensive breakdown of DNA occurs after ozonation and that the extent of ozone-induced DNA degradation generally correlates with the colony-forming ability of the cells.

DNA, Bacterial↗
PubMed1976

Rapid test for assay of ozone sensitivity in Escherichia coli.

A rapid test devised for assay of ozone sensitivity in Escherichia coli is described. The detection of new mutants, either more resistant or more sensitive than wild type strain to ozone, and the genetic analysis of ozone recombinants are now possible. Results confirm that ozone resistance is probably involved with DNA repair mechanism; and show that ozone and ultraviolet light inhibit the cell division capacity of lon mutant in a similar way.

Bacteriological Techniques↗
PubMed1976

Role of deoxyribonucleic acid polymerase III in the repair of single-strand breaks produced in Escherichia coli deoxyribonucleic acid by gamma radiation.

Cell survival, deoxyribonucleic acid (DNA) degradation, and the repair of DNA single-strand breaks were measured for Escherichia coli K-12 pol+, polA1, polC1026(ts), and polA1 polC1026(ts) cells after 137Cs gamma irradiation. The results indicate that DNA polymerase III is required for growth medium-dependent (type III) repair in polA+ or polA cells. In pol+ or polC cells, DNA polymerase I performs type II repair efficiently. The relative deficiencies of each of these strains in DNA repair generally correlate with their relative sensitivities to cell killing and with the extent of DNA degradation observed.

DNA Nucleotidyltransferases↗