Takeo Inamasu

Tumorigenicity of arsenic trioxide to the lung in Syrian golden hamsters by intermittent instillations

The tumorigenicity of arsenic trioxide was investigated in female Syrian golden hamsters which were given a total of 5.25 mg or 3.75 mg as arsenic by intratracheal instillations once a week. As controls, hamsters were treated with the vehicle, phosphate buffer solution. During the total life span, 3 lung adenomas were manifested in 10 hamsters or 2 lung adenomas in another 20 hamsters after 15 instillations of arsenic, while no lung tumor was detected among 35 hamsters in 2 control groups. The results show that arsenic trioxide is tumorigenic to the lung of Syrian golden hamsters.

Ingestion of parsley inhibits the mutagenicity of male human urine following consumption of fried salmon

The urinary mutagenicity of 3 nonsmoking, healthy men was investigated after strictly defined meals by means of the Ames Salmonella/microsome test. When the subjects ate 150 g of fried salmon at one meal, a potent mutagenicity of almost 5000 revertants of TA98 strain was present in all 6-h urine samples. On the other hand, less than 2500 revertants was present in the urine when the subjects simultaneously consumed 70 g of parsley and 150 g of fried salmon. Thus, the protection against mutagenicity affected by parsley warrants further attention.

Mutagenicity of human urine after the consumption of fried salted salmon

Mutagenicity in the urine of four non-smoking individuals who had eaten salted salmon cooked at home for both lunch and supper was monitored by means of Salmonella/microsome mutagenicity tests. Extracts from fresh and salted salmon had the same level of mutagenicity after being cooked for 10 min at 200 degrees C, but no activity was detected before cooking. Salmonella strains TA98 and TA1538 were equally sensitive to the mutagens and required metabolic activation. No mutagenicity was shown with TA100 and TA1535. Urine samples were tested using a concentrate prepared by means of an XAD-2 resin column. Mutagenicity was detected mainly in urine excreted during 4-5 hr after the ingestion of cooked salmon, but only weak mutagenicity, or none at all, was detected in the urine after the ingestion of vegetables. The levels of urinary mutagenicity due to salmon consumption were not affected when cabbage was eaten simultaneously. The excretion of mutagenic substances was completed within about 20 hr, and there were almost no mutagens in the urine 24 hr after the ingestion of cooked salmon.

Evaluation of Four Methods for Concentrating Mutagens in Ames Salmonella/Microsome Assays on Leachate Collected from a Municipal Solid Waste Landfill.

Four concentration methods ; XAD resin adsorption, CSP/CHPA resin adsorption, dichloromethane solvent extraction, and blue rayon adsorption were compared for their abilities to concentrate mutagens from leachate samples obtained from a municipal solid waste landfill. The Ames Salmonella/microsome assay was used to evaluate the four methods. The XAD resin adsorption, the CSP/CHPA resin adsorption, and the solvent extraction well recovered mutagens from leachate samples, while the blue rayon adsorption could scarcely recover mutagens, suggesting that polyaromatic hydrocarbons having 3 or more fused aromatic rings in their structures less contribute to the mutagenic activity of landfill leachate. Mutagens were well recovered only after leachate samples were acidified. Therefore, it is likely that predominant mutagens in landfill leachate are acidic compounds. TA98 detected mutagenicity of concentrates better than TA100 and the addition of S9 did not increase the number of revertants.Judging from these results, the XAD resin adsorption, the CSP/CHPA resin adsorption, and the solvent extraction are suitable for concentrating mutagens from landfill leachate.

A comparison of the carcinogenicity of N-nitrosodiethylamine and N-nitrosodimethylamine after intratracheal instillation into Syrian golden hamsters

N-Nitrosodiethylamine (NDEA) and N-nitrosodimethylamine (NDMA) were instilled intratracheally into male Syrian golden hamsters once a week for 15 wk. The total dosages were 1.5 mg and 7.5 mg of NDEA and 0.75 mg and 1.5 mg of NDMA. A control group simultaneously received phosphate buffer vehicle. Tumours related to instillation appeared principally in the respiratory tract and the liver. Over the entire lifespan of the animals tumour incidence rates in the respiratory tract were 100% in both the NDEA groups, 6% in both NDMA groups and 8% in the control group. The total incidences of liver tumours were 6% in the 0.75 mg NDMA group, 19% in the 1.5 mg NDMA group, zero in the NDEA groups, and 4% in the control group. These results indicate that, when administered by this route, NDEA is a much more potent carcinogen in the respiratory tract than is NDMA but NDMA alone seems to be carcinogenic to the liver, at a total dosage of 1.5 mg.