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Biomedical subjects

Y Miyata

Publications and source records attributed to Y Miyata.

At least 343 records · Page 19Linked to original sources
PubMed1979

Enhancing effect of inducers of liver microsomal enzymes on induction of hyperplastic liver nodules by N-2-fluorenylacetamide in rats.

The effects of inducers of liver microsomal enzymes on the induction of hyperplastic liver nodules by N-2-fluorenylacetamide (2-FAA) were studied in male F344 rats. The rats were fed a diet containing 200 ppm 2-FAA for 2 weeks and then given test chemicals for the following 8 weeks. Partial hepatectomies were performed at the end of the third week of the experiment. The compounds were tested, and their concentrations (in ppm) in the diet were as follows: 1,000 polychlorinated biphenyls (PCB), 500 PCB, 500 PCB plus 70 3-methylcholanthrene (MCA); 500 PCB plus 500 phenobarbital, 70 MCA, 500 phenobarbital, 500 phenobarbital plus 500 beta-naphthoflavone, and 2,500 3-(3,5-dichlorophenyl)-5,5-dimethyloxazoline-dione-2,4 (DDOD). All experimental groups developed significantly greater numbers and total areas of hyperplastic nodules than did the controls. In groups treated similarly with the test chemicals but without partial hepatectomy, the numbers and total areas of hyperplastic nodules were significantly less than those in the experimental groups with partial hepatectomy. Administration of test chemicals except 2-FAA to partially hepatectomized rats did not induce hyperplastic nodules. The present results showed the early detection of the enhancing effect on induction of hyperplastic liver nodules by a system consisting of the following three procedures: 1) 2-FAA feeding; 2) administration of test chemicals, and 3) partial hepatectomy during administration of test chemicals. In this system DDOD enhanced the induction of hyperplastic nodules of the liver.

2-Acetylaminofluorene↗
PubMed1979

Long-term experiment of maximal non-carcinogenic dose of dimethylnitrosamine for carcinogenesis in rats.

Studies were made on the maximal non-carcinogenic dose of dimethylnitrosamine (DMN) in rats. Groups of Wistar strain rats of both sexes, 6 weeks old, were given standard diet without DMN (group 1), or containing 0.1 ppm DMN (group 2), 1.0 ppm DMN (group 3), or 10 ppm DMN (group 4) for 96 weeks and then sacrificed for hematological, serum-biochemical, and histopathological examinations. After 96 weeks, the weights of the body and main organs in the different groups were not significantly different. The leucocyte count and blood urea-nitrogen (BUN) in group 4 were slightly increased, but other serum findings were not significantly different in different groups. Hepatocellular carcinomas were found in group 3 (1 male and 3 females), but not in group 2. Hemangioendotheliomas of the liver, adrenal adenomas, pituitary adenomas, interstitial cell tumors of the testis, ovarian tumors, and leukemia were also found. Pyelonephritis was found in both experimental and control animals, but no kidney tumors developed with these dose levels of DMN. These results show that on long-term oral administration to rats, 1.0 ppm DMN is the minimum carcinogenic dose, while a level of about 0.1 ppm DMN is non-carcinogenic.

Animals↗
PubMed1979

Sequential quantitative studies on hyperplastic nodules in the liver of rats treated with carcinogenic chemicals.

Sequential quantitative analyses were made of hyperplastic liver nodules induced by treating male Fischer rats first with diethylnitrosamine (DEN) and then with N-(2-fluorenyl)acetamide (2-FAA), alpha-isomer of 1,2-3,4,5,6-hexachlorocyclohexane (alpha-BHC), or phenobarbital. The test rats were injected ip with 200 mg/kg body weight of DEN, given basal diet containing 2-FAA, alpha-BHC, or phenobarbital from week 2 to 12, and subjected to partial hepatectomy at the end of week 3. From week 6, significantly higher percentage areas of hyperplastic nodules per unit area of liver were found in all experimental groups than in the control group. From week 8, significantly more hyperplastic nodules were found in all experimental groups than in the control group. Continuous administration of alpha-BHC or phenobarbital for 12 weeks with partial hepatectomy did not induce hyperplastic nodules. Continuous administration of 2-FAA did induce hyperplastic nodules, but the percentage areas and number of these nodules were significantly lower than in rats injected with DEN and then given 2-FAA orally, with partial hepatectomy.

2-Acetylaminofluorene↗
PubMed1978

Dose and dose rate in 192Ir interstitial irradiation for carcinoma of the tongue.

Seventy-three patients with carcinoma of the tongue were treated with 192Ir implantation. The total dose for control of the primary lesion without late radiation injury could be fixed to about 70 Gy with a variation of the dose rate between 0.25 and 1 Gy per hour. Additional external irradiation, without reduction of the dose from the interstitial irradiation, involves a high risk of local necrosis.

Adult↗