384

manipulate the gene to produce a deletion in the chromosomal GSH1 gene. If the cells are viable they provide an elegant system to investigate the phenotypic effects of complete GSH deficiency.

In vitro cytotoxicity and genotoxicity of gallium arsenide

Husgafvel-Pursiainen, K., T. Suitiala, H. J~irven- taus, K. Linnainmaa and H. Vainio, Institute of Occupational Health, Helsinki (Finland)

Gallium arsenide (GaAs) is a crystalline inter- metallic compound. It is used as a semiconductor in the electronics industry, where exposure to airborne particulates of GaAs is a potential health hazard. We studied both cytotoxicity and geno- toxicity of GaAs in Chinese hamster ovary (CHO) cells in vitro. Cytotoxic effects of GaAs were assayed by Trypan blue exclusion after 24-h ex- posure of exponentially growing cells to milled GaAs particles or to dissolved GaAs in filtrated incubation solution. To evaluate the genotoxicity of GaAs particles, both sister-chromatid ex- changes (SCEs) and chromosome aberrations (CAs) were studied using 4-h pulse treatment both in the presence and in the absence of a metabolic activation system ($9 mix). The in vitro solubility of the compound under the culture conditions was determined by the amount of dissolved arsenic. The concentrations studied varied between 0.3 and 20.0 mg/ml (0.06-4.00 mg/cmZ). At a GaAs concentration of 5 mg/ml, the average amount of arsenic dissolved in the culture medium was 20.3 /~g/ml. The TCs0 concentration of GaAs particles on CHO cells in culture was 0.5 mg/ml (0.13 mg/cm2). The treatment of cells with GaAs did not significantly induce either CAs or SCEs when tested at concentrations of 2.5-40 mg/ml (0.5-8.0 mg/cm2). The TCs0 concentration of GaAs par- ticles on CHO cells in culture was 0.5 mg/ml (0.13 mg/cm2).

Biological and occupational aspects of lung cancer

Husgafvel-Pursiainen, K., S. Anttila, P.L. Kal- liom~iki, P. Hackman, M. Ridanp~Ri, L. Heikkila

and H. Vainio, Institute of Occupational Health, Helsinki (Finland)

The present collaborative study was undertaken to characterize histopathological, biological and occupational factors related to lung cancer with special emphasis on asbestos exposure. Peroper- ational fresh lung tissue samples have so far been obtained from 30 lung cancer patients from Helsinki University Hospital. The patients have been personally interviewed for detailed informa- tion on occupational and medical history as well as life-style. According to histopathological diag- nosis, 15 of the patients had squamous cell carcinoma, 10 adenocarcinoma, 4 small cell carcinoma; 1 carcinoid tumor was also seen. The majority of these tumors (20) were of bronchial origin, and 8 of the patients were diagnosed as having asbestosis as well. As one of the various biological endpoints included in the study, we have an ongoing project to analyze mutational activation of the K-ras oncogene both in tumor tissue and in peripheral blood cell DNA. We have amplified the purified genomic DNA by the poly- merase chain reaction. Two different approaches are then being applied to detect point mutations in the K-ras oncogene. We use first the oligonu- cleotide hybridization technique and then the de- naturing gradient gel electrophoresis method for detection of these mutations in the same samples. The ultimate goal of this work is to try to correlate biological marker effects with smoking and oc- cupational exposure in Finnish lung cancer pa- tients.

Mutagenicity of deethylatrazine and its influence on $9 fraction activity

Franeki6, J., G. Hulina, J. Kniewald and M. AlaEevi6, Faculty of Food Technology and Bio- technology, University of Zagreb, Zagreb (Yugo- slavia)

Deethylatrazine, an N-dealkylated metabolite of atrazine, was isolated from the brain and kid- ney of male rats pretreated with atrazine (Knie- wald et al. (1985) Iugoslav. Physiol. Pharmacol. Acta, 21, 171-172). Deethylatrazine induced