In vivo chromosome-damaging effect of cyclohexylamine in the chinese hamster

Toxicological aspects of cyclamate and cyclohexylamine

In the late 1960s the artificial sweetener cyclamate was implicated as a bladder carcinogen in rats. This finding and other concerns about its safety ultimately led to a ban on cyclamate in the U.S. and restrictions on its use in many other countries. Since that time, the carcinogenic potential of cyclamate and cyclohexylamine, its principal metabolite, has been reevaluated in a group of well-controlled, well-designed bioassays that have failed to substantiate the earlier findings. This review of the published and unpublished literature on cyclamate attempts to evaluate the carcinogenicity question and other important aspects of the toxicity of cyclamate and cyclohexylamine, including their effects on various organ systems, their genotoxic potential, and their effects on reproduction. In addition, the physiological disposition of cyclamate is reviewed, with particular attention directed toward the site and extent of its conversion to cyclohexylamine.

Aneuploidy in mammalian somatic cells in vivo

Aneuploidy is an important potential source of human disease and of reproductive failure. Nevertheless, the ability of chemical agents to induce aneuploidy has been investigated only sporadically in intact (whole-animal) mammalian systems. A search of the available literature from the EMCT Aneuploidy File (for years 1970-1983) provided 112 papers that dealt with aneuploidy in mammalian somatic cells in vivo. 59 of these papers did not meet minimal criteria for analysis and were rejected from subsequent review. Of the remaining 53 papers that dealt with aneuploidy induction by chemical agents in mammalian somatic cells in vivo, only 3 (6%) contained data that were considered to be supported conclusively by adequate study designs, execution, and reporting. These 3 papers dealt with 2 chemicals, one of which, mercury, was negative for aneuploidy induction in humans, and the other, pyrimethamine, was positive in an experimental rodent study. The majority of papers (94%) were considered inconclusive for a variety of reasons. The most common reasons for calling a study inconclusive were (a) combining data on hyperploidy with those on hypoploidy and/or polyploidy, (b) an inadequate or unspecified number of animals and/or cells per animal scored per treatment group, and (c) poor data presentation such that animal-to-animal variability could not be assessed. Suggestions for protocol development are made, and the future directions of research into aneuploidy induction are discussed.

Investigation into the mutagenic activity of azathioprine (Imuran) in different test systems

The chromosome-damaging effect of azathioprine (Imuran) was investigated in the micronucleus test with mice and rats, in the pertussis-stimulated lymphocyte metaphase test with rabbits, and in children on azathioprine therapy. In the micronucleus test, there was a dose-dependent increase in the number of cells with micronuclei. The dose was given twice in 24 h, i.p., 25, 50 and 100 mg/kg body weight for mice, and 50, 100 and 200 mg/kg for rats. In the lymphocyte test, a dose of 5 and 20 mg azathioprine per kg body weight was given orally to rabbits on three successive days after pertussis injection. Compared with treatment in the control group these treatments induced a significantly increased number of cells with chromosomal abnormalities. These results were confirmed in lymphocyte cultures of children on long-term azathioprine therapy after kidney transplantation, where an increase in the number of structural chromosomal abnormalities was observed.

Bone marrow and lymphocyte cytogenetics of rhesus monkeys (Macaca mulatta) treated with the clastogen Mitomycin C

Rhesus monkeys (Macaca mulatta) were used to determine their effectiveness as experimental animals for different cytogenetic tests with mitomycin C (MC). The micronucleus test (MNT and/or chromosome analysis of blood and bone marrow were made before and/or after the treatment with mitomycin C. Thus, the controls data and treated data were obtained from the same animals. With the employed methology, the micronucleus test could not be performed on living animals. Less chromosomal damage was detected in the micronucleus test of post-mortem samples than in the chromosome analysis of bone marrow. No influence by the mutagen could be observed in lymphocyte chromosomes at any of the different times of analysis. In contrast to this, bone-marrow chromosomes seemed to be highly affected by mitomycin C at day 1, 2 and 3 after injection. However, before treatment and at day 14, 16 and 17 after treatment there was no visible increase in chromosomal aberration in bone marrow.