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Mutagenicity in cooked foods. Effect of cooking oils on the formation of mutagenicity in sauteed fish
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37 Muraoka, N., and S. Hisaoka, Sanyo Gakuen Junior College, Okayama 703 (Japan) Mutagenicity in cooked foods. Effect of cooking oils on the formation of mutagenicity in sauteed fish
We have previously determined the mutagenicity of meat (chicken, pork, beef) sauteed with oil or fat. The mutagenicity was enhanced most by cooking with lard, and sauteed chicken showed the highest mutagenic activity when it was pretreated with soy sauce-sake-sugar. In this paper, 10 different cooking oils or fats were tested for their effect on the formation of mutagens in sauteed fish. The mutagenicity was determined with the blue cotton method, coupled with the Ames test (TA98, + $9). Pampus argenteus was used as a typical fish with low lipid content. Its lipid content was only 2.9%. The mutagenic potency of sauteed fish pretreated with soy sauce-sake-sugar was not affected by the cooking oils or fats. In comparison with the previous study, it appeared that the highest mutagenicity was found in chicken sauteed with lard.
38 Nagae, Y. 1, T. Hayashi 1, y . Suzuki 2 and H. Shimizu 2, 1 Drug Safety Laboratory, Ciba-Geigy (Japan) Ltd., Takarazuka, Hyogo 665 and 2 Department of Public Health, Jikei University School of Medicine, Minato-ku, Tokyo 105 (Japan) The micronucleus test and erythropoiesis. Effects of estrogen on induction of micronuclei
We have reported previously that an acceleration of erythropoiesis increases the frequency of micronuclei in bone marrow. The aim of this experiment was to prove the effects of estrogen on the induction of micronuclei in mouse bone marrow. Four groups of 5 male ICR mice were administered 17]~-estradiol (E2) subcutaneously at doses of 0, 10, 100 and 1000 ~ g / k g b.w. once a day for 4 days. A single injection of mitomycin C (MMC) was given intraperitoneally 30 rain after the last injection of E 2. Then 24 h later the bone marrow smears were prepared by Schmid's method. An inhibition of micronucleated polychromatic
erythrocytes (MPCE) in the bone marrow treated with MMC was observed in order of concentration of E 2. In a time-course study, E 2 (1000 /~g/kg b.w.) was administered twice a day 0, 1, 2 or 3 days before injection of MMC. The number of MPCE in mouse bone marrow treated with MMC was inhibited significantly when E 2 was administered 0 or 1 day before injection of MMC. The most effective inhibition of micronuclei was shown after simultaneous treatment with E2 and MMC. Our present findings suggest that the estrogen might inhibit the inducibility of micronuclei by mutagens because of inhibiting effects of proliferation of erythroblasts in mouse bone marrow.
39 Nagao, M., K. Wakabayashi, K. Takayama, M. Ochiai, M. Hirose and T. Sugimura, Carcinogenesis Division, National Cancer Center Research Institute, 5-1-1, Tsukiji, Chuo-ku, Tokyo 104 (Japan) Human exposure level of heterocyclic amines and their risk assessment
We have been studying causes of human cancer, focusing on food mutagens/carcinogens, and have found the presence of various types of mutagens in various foods. Among them, heterocyclic amines (HAs), which are produced by heating proteinaceous foods, have been clearly proved to be carcinogenic in rodents. Levels of human exposure to HAs have been analyzed by measuring the amounts in foods and urine. Daily intake of HAs was estimated to be about 10 ~g. We also used the DNA-adduct level as a marker. We first analyzed the level of D N A adducts of various HAs in the liver of rats after gastric intubation, with the 32p_ postlabeling method. Levels of Trp-P-1-DNA adducts were the highest of those tested. Levels of MeIQx-DNA adducts were intermediate. When a diet containing 100 ppb MeIQx (1/4000 of the carcinogenic dose) was fed to rats for 1 week, adducts were detected. Adduct levels increased with increasing administration period. At present we are analyzing H A - D N A adducts in human liver specimens obtained from patients undergoing surgery for hepatocellular carcinomas.
37 Muraoka, N., and S. Hisaoka, Sanyo Gakuen Junior College, Okayama 703 (Japan) Mutagenicity in cooked foods. Effect of cooking oils on the formation of mutagenicity in sauteed fish
We have previously determined the mutagenicity of meat (chicken, pork, beef) sauteed with oil or fat. The mutagenicity was enhanced most by cooking with lard, and sauteed chicken showed the highest mutagenic activity when it was pretreated with soy sauce-sake-sugar. In this paper, 10 different cooking oils or fats were tested for their effect on the formation of mutagens in sauteed fish. The mutagenicity was determined with the blue cotton method, coupled with the Ames test (TA98, + $9). Pampus argenteus was used as a typical fish with low lipid content. Its lipid content was only 2.9%. The mutagenic potency of sauteed fish pretreated with soy sauce-sake-sugar was not affected by the cooking oils or fats. In comparison with the previous study, it appeared that the highest mutagenicity was found in chicken sauteed with lard.
38 Nagae, Y. 1, T. Hayashi 1, y . Suzuki 2 and H. Shimizu 2, 1 Drug Safety Laboratory, Ciba-Geigy (Japan) Ltd., Takarazuka, Hyogo 665 and 2 Department of Public Health, Jikei University School of Medicine, Minato-ku, Tokyo 105 (Japan) The micronucleus test and erythropoiesis. Effects of estrogen on induction of micronuclei
We have reported previously that an acceleration of erythropoiesis increases the frequency of micronuclei in bone marrow. The aim of this experiment was to prove the effects of estrogen on the induction of micronuclei in mouse bone marrow. Four groups of 5 male ICR mice were administered 17]~-estradiol (E2) subcutaneously at doses of 0, 10, 100 and 1000 ~ g / k g b.w. once a day for 4 days. A single injection of mitomycin C (MMC) was given intraperitoneally 30 rain after the last injection of E 2. Then 24 h later the bone marrow smears were prepared by Schmid's method. An inhibition of micronucleated polychromatic
erythrocytes (MPCE) in the bone marrow treated with MMC was observed in order of concentration of E 2. In a time-course study, E 2 (1000 /~g/kg b.w.) was administered twice a day 0, 1, 2 or 3 days before injection of MMC. The number of MPCE in mouse bone marrow treated with MMC was inhibited significantly when E 2 was administered 0 or 1 day before injection of MMC. The most effective inhibition of micronuclei was shown after simultaneous treatment with E2 and MMC. Our present findings suggest that the estrogen might inhibit the inducibility of micronuclei by mutagens because of inhibiting effects of proliferation of erythroblasts in mouse bone marrow.
39 Nagao, M., K. Wakabayashi, K. Takayama, M. Ochiai, M. Hirose and T. Sugimura, Carcinogenesis Division, National Cancer Center Research Institute, 5-1-1, Tsukiji, Chuo-ku, Tokyo 104 (Japan) Human exposure level of heterocyclic amines and their risk assessment
We have been studying causes of human cancer, focusing on food mutagens/carcinogens, and have found the presence of various types of mutagens in various foods. Among them, heterocyclic amines (HAs), which are produced by heating proteinaceous foods, have been clearly proved to be carcinogenic in rodents. Levels of human exposure to HAs have been analyzed by measuring the amounts in foods and urine. Daily intake of HAs was estimated to be about 10 ~g. We also used the DNA-adduct level as a marker. We first analyzed the level of D N A adducts of various HAs in the liver of rats after gastric intubation, with the 32p_ postlabeling method. Levels of Trp-P-1-DNA adducts were the highest of those tested. Levels of MeIQx-DNA adducts were intermediate. When a diet containing 100 ppb MeIQx (1/4000 of the carcinogenic dose) was fed to rats for 1 week, adducts were detected. Adduct levels increased with increasing administration period. At present we are analyzing H A - D N A adducts in human liver specimens obtained from patients undergoing surgery for hepatocellular carcinomas.