|Budget Amount *help
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
Nitroso compounds form easily under Physiological conditions, but are not so carcinogenic as might be expected from the amount formed. Based on the assumption that a factor must exist that modifies the carcinogenicity of these compounds, this study was made.
Through this study , TA1535 , the most sensitive strain of the model compound MNNG, not requiring metabolic activation, was found; the detection density threshold of 1 ug/p was determined.
This study produced a new finding; in the presence of toxic elements such as cadmium and mercury, or even non-toxic elements such as calcium and magnesium, the mutagenicity of MNNG is multiplied at a density level equal to or below the threshold value.
A micro-nucleus test was established as a system allowing continuous tracing of in vivo mutagenicity in the same animal.
Then a study was made using DMN (dimethylnitrosanine) model compounds Food-derived amine and nitrite, dimethylamine and nitrite, vitamin C, NaCl, and DMN-pasitive control, and normal food-control were administered to mice for 90 days ; changes in body weight, compound intake level, water intake volume, and feed intake level were measured every week. After autopsy , body organ weight ratio, blood free radical density, and blood peroxide density were measured. In vivo mutagenicity was continually traced by micro-nucleus testing of peripheral blood at 30-day intervals, but due to the great intraclass variation, analysis was difficult.
Nitroso reaction of intestinal flora is necessary for nitrosamines to be formed under neutral or weak alkaline conditions like those in the intestines. Little is known about the role of intestinal flora. It will be necessary to clarify that role, while at the same time analyzing the degree of intervention of nitrosamines in colon cancer, breast cancer, and other human cancer.