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Biomedical subjects

G Abel

Publications and source records attributed to G Abel.

At least 73 records · Page 4Linked to original sources
PubMed1983

Induction of structural chromosome aberrations and sister chromatid exchanges in human lymphocytes in vitro by aristolochic acid.

The medicinal use of Aristolochia clematitis has been known for some time. The main active agent of this medicinal plant is aristolochic acid, a nitrophenanthrenecarbonic acid. Very recently, however, the Federal Health Office withdrew the licence for all drugs containing aristolochic acid, because of the well-founded suspicion that aristolochic acid may be a very potent carcinogen. We investigated the induction of structural chromosome aberrations and sister chromatid exchanges (SCEs) by aristolochic acid in human lymphocytes in vitro. Cells were treated with the agent tested throughout culture time and during the G0 phase of the cell cycle. We tested concentrations over a range of 1 to 20 micrograms/ml. Both treatment conditions resulted in an increased aberration frequency. The induction of gaps and breaks as well as the induction of SCEs showed a dose-dependent increase. The number of SCEs per metaphase was enhanced by a factor of 2 to 3. If conventional cytogenetic methods had been applied in time, one would have recognized the mutagenic risk of aristolochic acid earlier.

Aristolochic Acids↗
PubMed1981

Mutagenicity and toxicity of furocoumarins: comparative investigations in 2 test systems.

The phototoxicity and the photomutagenicity of the 2 linear furocoumarins 8-methoxypsoralen (8-MOP) and 8-isoamylenoxypsoralen (8-IOP) and of the angular derivative 5'-methylangelicin (5'-MA) were studied in 2 different test systems. In human lymphocytes, sister-chromatid exchange analysis (SCE analysis) was carried out. We found an increase in SCE frequency after treatment with 8-MOP and 5'-MA, but no enhancement was caused by 8-IOP. In the algal system Chlamydomonas reinhardii, 8-MOP and 5'-MA showed a similarly strong influence with regard to phototoxicity; 8-IOP exhibited a weaker effect within the same irradiation time. For photomutagenicity in Chlamydomonas, 8-MOP proved to be the strongest derivative; 8-IOP, however, was capable of inducing about the same numbers of revertants, but only under certain conditions. The angular 5'-MA showed a weak mutagenic activity in contrast to the psoralens. The influence of the structure of the derivatives and of the experimental conditions on the effects obtained are discussed with regard to the therapeutic risk of monofunctional and bifunctional furocoumarins.

Cells, Cultured↗
PubMed1980

In vitro cytotoxicity of the methylmelamines.

Hexamethylmelamine (HMM) and a number of its derivatives are toxic to PC6 plasmacytoma cells in vitro. However, there is no correlation between in vitro cytotoxicity and activity against this tumour in vivo. N-Methylolmelamines are significantly more toxic than HMM itself. These compounds break down to release formaldehyde which is itself a highly cytotoxic agent. Pentamethylmonomethylolmelamine rapidly inhibits the growth of PC6 cells in culture, whereas HMM and pentamethylmelamine (PMM) require prolonged contact with the cells in order to exert a cytotoxic effect. HMM and its metabolites are also toxic to a number of other cell lines. The toxicity of the N-methylols to cultured L1210 leukaemia and Walker 256 ascites cells appears to be due entirely to formaldehyde release, whereas in PC6 cells the methylols appear to be acting more selectively.

Altretamine↗
PubMed1979

The quantitative measurement of the opacity of aesthetic dental filling materials.

A method is described for measuring the opacity of anesthetic dental filling materials using a goniophotometer. Procedures are given for converting measured opacity values to those referred to a 70% reflectance background (C0.7 values) as required by existing specifications. The conversion is involved, and, since most available white surfaces have reflectance of about 80%, it is recommended that in future specifications opacity be recorded as C0.8 values. Opacity values for 28 materials are reported. It was found that the opacity of dental cement decreases for several days following preparation and that powder/liquid ratio has little effect, while pigmentation has a marked effect on opacity.

Acrylic Resins↗