Over-representation of construction-related occupations in male patients with systemic sclerosis.

AIMS: Based on preliminary observations, we tested the hypothesis that construction-related occupations are associated with systemic sclerosis (SSc). METHODS: The professional occupation of 91 patients with SSc (71 females and 20 males) was recorded. Categorisation into construction-related and other professions was performed. A double definition was used for construction-related occupations. The first (limited) definition was based upon categories of the Belgian National Institute of Statistics (NIS) occupational list. The following occupations were considered construction-related: electricians, joiners, masons and tilers, plumbers and pipefitters. The use of this list also allows us to compare the distribution of professions in these patients with that in the general population. As the NIS occupational list is limitative and leaves out some "real-life" construction-related occupations, a second and broader interpretation was given to the concept of construction-related occupations. RESULTS: The prevalence of construction-related professions in males with SSc, according to the limited definition, was 10-fold higher than in the general working population (50% vs 5%; p<0.001). Interestingly, most of the patients with construction-related occupations were electricians. In the broader interpretation, 75% of the men with SSc fell into the category of construction-related occupations. CONCLUSIONS: The data show an association between SSc and professional occupation.

Sampling times in micronucleus testing.

A series of micronucleus inducers were evaluated in the mouse bone marrow micronucleus test to determine if a 72-h sampling time enhances the sensitivity for detecting genotoxic agents. Male and female Swiss albino mice were dosed once with 7,12- dimethylbenz[a]anthracene, 6-mercaptopurine, benzo[a]pyrene, benzene, cyclophosphamide, 2-acetylaminofluorene, tubulazole, or mitomycin C. According to the EEC and OECD guidelines, the mice were killed at 24, 48 and 72 h after dosing. All test compounds induced an increase in the number of micronucleated polychromatic erythrocytes at 24 and/or 48 h. From the results obtained, it was evident that the 72-h sampling time does not enhance the sensitivity of the micronucleus test. The present data show that for screening purposes two sampling times at 24 and 48 h are sufficient to detect clastogens as well as aneugens. Although quantitative differences were found in sensitivity to micronucleus inducers between male and female mice, no qualitative differences were observed between the two sexes.

The micronucleus assay as a test for the detection of aneugenic activity.

The aim of this work was to determine the usefulness of the micronucleus assay for the detection of aneugenic potential. Chemicals affecting microtubule assembly, i.e., colchicine, vinblastine sulfate and tubulazole, and chemicals affecting targets other than microtubuli, i.e., mitomycin C, cyclophosphamide and miconazole, and the clastogens azathioprine and procarbazine were administered once orally or intraperitoneally to male and female mice. Bone marrow preparations were made at 24, 48 and 72 h after dosing. All the clastogens and aneugens, except miconazole, yielded positive results in the micronucleus test. Measurements of the area of the micronuclei and their distribution clearly showed that the chemicals affecting microtubule assembly produced larger micronuclei than did the clastogens. The pattern of area distribution of the micronuclei found with cyclophosphamide and mitomycin C was between those found for the tubulin inhibitors and the clastogens. These findings indicate that the micronucleus test not only detects chemicals affecting microtubule assembly, but also can discriminate them from clastogens by measurements of the area of the micronuclei.