[Studies on the action of 8-hydroxyquinoline sulfate on human chromosomes in vitro]

Strukturelle Chromosomenaberrationen in den Lymphozyten gesunder Probanden unter dem Einfluss verschiedener Kulturbedingungen

The frequency of structural chromosomal aberrations has been examined in peripheral blood lymphocyte cultures from 18 normal individuals. A mean rate of aberrations was observed of 7.38%, and a mean breakage/metaphase index of 0.036. Individual values ranged, for the aberration index, from 4% to 15%; and, for the breakage/metaphase index, from 0.00 to 0.08. Only gaps and breakage were observed. The translocation cross and chromatid-ring observed derive from a series of experiments on homologous plasma cultures. As for the influence of different cultural environments, it has been observed that the rate of spontaneous aberrations behaved independently from the age of the blood sample, from the addition of penicillin in the culture, and from the concentration of phytohemoagglutinin. Using veal's fetal serum, the rate of aberrations failed to show any variation, even with a time of culture prolonged up to 96 hours; while, using homologous plasma, the time of culture having been prolonged, structural aberrations have shown a considerable increase. The study of the mitotic index in the different cultural conditions has indicated the possibility of favoring the growth of leucocyte cultures.

Induction of chromosomal aberrations and sister chromatid exchange in vivo and in vitro by the insecticide cypermethrin

The induction of chromosomal aberrations and sister chromatid exchange in vivo in mouse spleen and bone marrow as well as in vitro in cultured mouse spleen cells by the insecticide 'Cypermethrin' (cis-trans 1:1) was investigated. The percentage of chromosomal aberrations in the spleen and in the bone marrow as almost the same and reached its maximum 6 h following i.p. injection. The aberrations induced were chromatid and chromosome gaps, fragments and tetraploidy. The insecticide caused a significant and dose-dependent increase in the frequency of sister chromatid exchanges (SCEs) in mouse bone-marrow cells: it reached 11.12 +/- 0.05 per cell after treatment with Cypermethrin at 300 mg kg-1 body wt. compared with 3.7 +/- 0.14 per cell and 4.4 +/- 0.26 per cell in the solvent and control, respectively. The percentage of viable cells in mouse spleen cell cultures reached 87.4% and 99.9% relative to the control after treatment of the cell cultures with 10(-3) and 10(-7) Cypermethrin, respectively. All the tested concentrations of Cypermethrin (0.25-400 micrograms ml-1) induced a high percentage of metaphases with chromosomal aberrations after 4 h of treatment. The mean frequency of SCEs per cell reached 15.1 +/- 0.05 after treatment with Cypermethrin at 4.00 micrograms ml-1 compared with 8.6 +/- 0.23 and 5.9 +/- 0.39 in the solvent and control, respectively. The results indicate that Cypermethrin is genotoxic in mouse spleen and bone marrow as well as in cultured mouse spleen cells.

Mutagenicity of quinolines in Salmonella typhimurium TA100. A QSAR study based on hydrophobicity and molecular orbital determinants

The mutagenicity of 33 quinolines in the Salmonella test using TA98 and TA100 cells has been reported. Significant activity was found only with TA100 cells. Quantitative structure-activity relationships (QSAR) could be formulated using molecular orbital parameters or Hammett constants and hydrophobic parameters for those compounds with substituents in the 6, 7 and 8 positions. The QSAR points to the 2-position on the quinoline ring as being the site for activation by S9 oxidation.

Sister chromatid exchange (SCE) and structural chromosome aberration in mutagenicity testing

Data from previous studies published on the induction by mutagens of sister chromatid exchanges (SCEs) and structural chromosome damage were compared qualitatively and quantitatively. Although a good correlation between the incidence of both cytogenetic phenomena has been pointed out in many previous publications, about 30% of the agents for which comparable data were available yielded non-corresponding qualitative results concerning both indicator effects. However, even in groups with good qualitative agreement distinct quantitative differences indicated different molecular mechanisms of the formation of SCEs and breaks. Additional information supporting the importance of these differences for the validity of both indicator systems has been derived from the results obtained using strong clastogens exhibiting a low or no SCE-inducing activity and vice versa, from special observations on chromosomal breakage syndromes, and from studies on the action of known co- and anti-clastogens on SCE-induction by chemical mutagens. As a result, it has been suggested that the SCE-technique should be considered as a valuable additional method for cytogenetic mutagenicity testing, which, however, is not adequate to replace the classical methods of analysis of structural chromosome damage.

The action of three anticlastogens on the induction of sister chromatid exchange by trenimon and 8-hydroxyquinoline sulfate in human lymphocyte cultures

The influence of the anticlastogens beta-aminoethylisothiouronium (AET), d,l-homocysteinethiolactone (HCT), and 1-cysteine (CYS) on the frequency of sister chromatid exchanges (SCEs) induced by the chromosome damaging chemicals Trenimon and 8-hydroxyquinoline sulfate (8-HQS), was investigated in human lymphocyte cultures. None of the anticlastogens significantly influenced the SCE rate, whereas in the same or previous experiments the chromosome-breaking effect of these clastogens was distinctly reduced by the anticlastogens. These results suggest that the sites of anticlastogenic activity do not coincide with the sites of SCE formation. SCE analysis, although it yields interesting and important information about the action of chemicals on genetic material, cannot replace classical aberration analysis, because the two parameters apparently reflect different patterns of molecular and cytogenetic activity of mutagens.

Human lymphocytes as target cells in a metabolizing test system in vitro for detecting potential mutagens

A metabolizing test system is presented that comprises mouse liver microsomes for metabolic activation of the test compound, NADPH as co-factors, dimethylnitrosamine (DMN) as model mutagen and human peripheral lymphocytes as target cells. Lymphocytes were cultured in RPMI 1640 medium in the presence of phytohemagglutinin for 48 h before being used in the system. Incubation of the lymphocytes for 45 min in the metabolically active system reduced thymidine incorporation by 50%, whereas in the metabolically inactive system without NADPH thymidine incorporation was reduced by 15%. The latter reduction was due to the cytotoxic effects of the mouse liver microsomes and of DMN. When the lymphocytes were cultured for another 24 h after exposure to the metabolizing system and DMN, significant increased formation of chromosomal aberrations such as gaps were observed, cross-overs and breaks being less frequent.

In vivo cytogenetic activity of sulphonylurea drugs in man

A cytogenetic investigation of diabetic patients undergoing treatment with sulphonylurea drugs, particularly chlorpropamide, shows that significantly more chromatid aberrations and chromosome exchange aberrations are present in the lymphocytes of these patients compared with controls. This is taken as evidence of possible mutagenic activity by these drugs, although the possibility cannot be ruled out that the diabetic state itself is a contributory factor.