Bromodeoxyuridine labelling as an alternative method to identify 6-thioguanine-resistant mutant lymphocytes in humans.

6-Thioguanine-resistant (TGR) mutant lymphocytes in human blood are usually enumerated by the cloning assay which allows the molecular characterisation of the HPRT mutations to be detected. A "short-term" alternative approach is provided by the anti-bromodeoxyuridine (anti-BrdU) technique in which TGR lymphocytes are identified immunocytochemically by their ability to synthesise DNA in the presence of 6-thioguanine (TG). We have evaluated the influence of various experimental factors that could affect the frequency of TGR lymphocytes.

The genetic and non-genetic toxicity of the fungicide Vinclozolin.

The mutagenic/cocarcinogenic potential of the fungicide Vinclozolin was assessed by a comprehensive examination of toxicity mechanisms at both the genetic and the metabolic level. Vinclozolin did not induce any significant increase in chromosomal aberrations in human pheripheral blood lymphocytes cultured in vitro, both in the presence and in the absence of metabolic activation. However, significant dose-related increases in micronucleated erythrocytes (up to 4-fold over the control) were found in the bone marrow cells of mice 24 h after treatment with the fungicide over a range of concentrations from 312.

Cytogenetic effects of Metalaxyl on human and animal chromosomes.

The purpose of this study was to assess the cytogenetic effects in vitro and in vivo of a commonly used fungicide, Metalaxyl. Chromosome damage in vitro, quantified by cultured human peripheral blood lymphocytes, demonstrated dose-related effects not associated with mitotic inhibition or cell death. Significant induction of chromosomal aberrations was observed with between 300 and 1000 micrograms/ml Metalaxyl in the absence of microsomal activation.

Genetic and non-genetic biomarkers related to carcinogenesis in evaluating toxicological risk from Fenarimol.

A multibiomarker approach based on the study of toxicity mechanisms at both genetic and metabolic levels has been applied to Fenarimol. With regard to genotoxicity, particular attention was given to assays for chromosomal aberration and micronuclei; clastogenic potential was assessed in human peripheral blood lymphocytes in vitro, while the induction of micronuclei was studied in male CD1 mouse bone marrow polychromatic erythrocytes (PCE). Fenarimol did not induce any significant dose-related increase in micronucleated PCEs, up to 4-fold above the control level at a single dose of 75 mg/kg b.

Comparison of separated erythrocyte preparations and manual smears of bone marrow in showing micronucleus induction by clastogens and aneuploidogens in mouse.

The removal of nucleated cells from bone marrow cell suspensions by cellulose column separation and further purification in a Percoll gradient, coupled with slide preparation by a cytocentrifuge, produces uniform preparations of pure well-spread erythrocytes. The use of separated erythrocytes has been a considerable improvement in the in vivo micronucleus (MN) assay, because the optimal cell morphology and the possibility of scoring a high number of polychromatic erythrocytes (PCEs) in a short time are factors contributing to the sensitivity of the assay. As the separation procedure may selectively retain cells containing MN, a study comparing the performance of the erythrocyte fractionation technique and standard manual smear preparation was conducted in male NMRI mice treated with a single injection of two clastogens (cyclophosphamide, 25 or 50 mg/kg, or methylmethane sulfonate, 40 or 80 mg/kg) or two aneuploidogens (colchicine, 0.