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Effect of oxygen concentration in culture on the frequency of sister-chromatid exchanges in human lymphocytes and CHL cells
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(treatment times: 24 h and 48 h) and by the metabolic activation method at 0.25-1.0 mg/ml (treatment time: 6 h, recovery time: 18 h). The sister-chromatid exchange tests were performed with the metabolic activation method only. The CHL cells incorporated with BrdU for 15 h (first division cycle) were treated with o-dianisidine for 3 h at concentrations of 0.25-1.0 mg/ml, then were rinsed once and treated with BrdU for 15 h (second division cycle) again. The micronucleus tests using acridine orange staining were evaluated by intraperitoneal injection (i.p.) and oral administration (p.o.) to CD-1 mice. Mice were treated at doses of 113-450 mg/kg i.p. and 150600 mg/kg p.o. The frequency of induction of sister-chromatid exchange and structural chromosomal aberrations in vitro increased dose-dependently and significantly (p < 0.01). In the micronucleus test in vivo, the increased induction of micronucleated polychromatic erythrocytes (MNPCEs) in bone marrow was observed after p.o. administration, but not after the i.p. injections. The maximum response on induction of MNPCEs occurred at the highest dose level (600 mg/kg) at the 48 h sampling time, which is significant compared with control group (p < 0.01). In this report, it was found that o-dianisidine has the ability to induce chromosomal aberration in CHL cells with metabolic activation in vitro and in CD-1 mice by p.o. administration in vivo. Thus o-dianisidine is not only mutagenic but also clastogenic. 16 Hayashi, M., S. Honda, Y. Shinagawa, S. Sato a, Y. Naruse b and S. Kagamimori b, Toyama Institute of Health, Kosugi-machi, Toyama 939-03, ~' Kobe Univ. School Med., Kobe 650 and b Faculty Med., Toyama Med. and Pharm. Univ., Toyama 930-01, Japan Effect of oxygen concentration in culture on the frequency of sister-chromatid exchanges in human lymphocytes and CHL cells
The effect of the oxygen concentration in the culture atmosphere on the frequency of induced sister-chromatid exchanges (SCEs) was investi-
gated in human lymphocytes and CHL cells. For human lymphocyte cultures, peripheral blood samples were obtained from 8 healthy females aged 22-49 years. Whole blood cultures were set up with 20 ~ g / m l of BrdU under 5, 20, 40 and 80% 0 2 in a 5% CO2/N2-balanced air atmosphere at 37°C for 72 h. As compared with normoxic cultures (20% 02, 6.7 + 2.8 SCEs/cell), hypoxic cultures (5% 0 2) showed a significant decrease (5.8 _+ 2.4) and hyperoxic cultures (40% 0 2) showed a significant increase (8.3 + 2.6) in the SCE frequency, while no metaphase could be observed in 80% 0 2 cultures. Treatment with mitomycin C (1 x 10 -8 M) or diethylstilbestrol (2 x 10 -5 M) enhanced SCE levels both in 5% and in 20% 0 2. CHL cells were cultured with 10 /~g/ml of BrdU under 5, 20 and 40% O: in a 5% CO2/N2-balanced air atmosphere at 37°C for 32 h. As compared with normoxic cultures (20% 0 2, 10.8 _+4.4 SCEs/cell), hypoxic cultures (5% 0 2) showed a significant decrease (6.9 + 2.9) and hyperoxic cultures (40% 0 2) showed a significant increase (12.1 + 2.7) in the SCE frequency. Thus, when SCEs are to be investigated in culture, the concentration of oxygen should be carefully controlled. 17 Hayashi, M., T. Suzuki, Y. Kodama ", M. Honma, M. Hakura b and T. Sofuni, Division of Genetics and Mutagenesis, a Division of Toxicology, National Institute of Hygienic Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158 and b Department of Drug Safety Research, Eizai Co., Ltd., 1-3 Tokodai 5-chome, Tsuba-shi, Ibaraki 300-26, Japan The effect of combinations of clastogens in the mouse micronucleus assay
Safety evaluation of chemicals has been made on individual chemicals, but if we consider the manner of human exposure to chemicals, it is important to assess the effect of the combination of two or more different chemicals. In the present study, we evaluated the effect of combinations of model chemicals in the mouse peripheral reticulocyte micronucleus assay using the acridine orange supravital staining method, which has been
(treatment times: 24 h and 48 h) and by the metabolic activation method at 0.25-1.0 mg/ml (treatment time: 6 h, recovery time: 18 h). The sister-chromatid exchange tests were performed with the metabolic activation method only. The CHL cells incorporated with BrdU for 15 h (first division cycle) were treated with o-dianisidine for 3 h at concentrations of 0.25-1.0 mg/ml, then were rinsed once and treated with BrdU for 15 h (second division cycle) again. The micronucleus tests using acridine orange staining were evaluated by intraperitoneal injection (i.p.) and oral administration (p.o.) to CD-1 mice. Mice were treated at doses of 113-450 mg/kg i.p. and 150600 mg/kg p.o. The frequency of induction of sister-chromatid exchange and structural chromosomal aberrations in vitro increased dose-dependently and significantly (p < 0.01). In the micronucleus test in vivo, the increased induction of micronucleated polychromatic erythrocytes (MNPCEs) in bone marrow was observed after p.o. administration, but not after the i.p. injections. The maximum response on induction of MNPCEs occurred at the highest dose level (600 mg/kg) at the 48 h sampling time, which is significant compared with control group (p < 0.01). In this report, it was found that o-dianisidine has the ability to induce chromosomal aberration in CHL cells with metabolic activation in vitro and in CD-1 mice by p.o. administration in vivo. Thus o-dianisidine is not only mutagenic but also clastogenic. 16 Hayashi, M., S. Honda, Y. Shinagawa, S. Sato a, Y. Naruse b and S. Kagamimori b, Toyama Institute of Health, Kosugi-machi, Toyama 939-03, ~' Kobe Univ. School Med., Kobe 650 and b Faculty Med., Toyama Med. and Pharm. Univ., Toyama 930-01, Japan Effect of oxygen concentration in culture on the frequency of sister-chromatid exchanges in human lymphocytes and CHL cells
The effect of the oxygen concentration in the culture atmosphere on the frequency of induced sister-chromatid exchanges (SCEs) was investi-
gated in human lymphocytes and CHL cells. For human lymphocyte cultures, peripheral blood samples were obtained from 8 healthy females aged 22-49 years. Whole blood cultures were set up with 20 ~ g / m l of BrdU under 5, 20, 40 and 80% 0 2 in a 5% CO2/N2-balanced air atmosphere at 37°C for 72 h. As compared with normoxic cultures (20% 02, 6.7 + 2.8 SCEs/cell), hypoxic cultures (5% 0 2) showed a significant decrease (5.8 _+ 2.4) and hyperoxic cultures (40% 0 2) showed a significant increase (8.3 + 2.6) in the SCE frequency, while no metaphase could be observed in 80% 0 2 cultures. Treatment with mitomycin C (1 x 10 -8 M) or diethylstilbestrol (2 x 10 -5 M) enhanced SCE levels both in 5% and in 20% 0 2. CHL cells were cultured with 10 /~g/ml of BrdU under 5, 20 and 40% O: in a 5% CO2/N2-balanced air atmosphere at 37°C for 32 h. As compared with normoxic cultures (20% 0 2, 10.8 _+4.4 SCEs/cell), hypoxic cultures (5% 0 2) showed a significant decrease (6.9 + 2.9) and hyperoxic cultures (40% 0 2) showed a significant increase (12.1 + 2.7) in the SCE frequency. Thus, when SCEs are to be investigated in culture, the concentration of oxygen should be carefully controlled. 17 Hayashi, M., T. Suzuki, Y. Kodama ", M. Honma, M. Hakura b and T. Sofuni, Division of Genetics and Mutagenesis, a Division of Toxicology, National Institute of Hygienic Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158 and b Department of Drug Safety Research, Eizai Co., Ltd., 1-3 Tokodai 5-chome, Tsuba-shi, Ibaraki 300-26, Japan The effect of combinations of clastogens in the mouse micronucleus assay
Safety evaluation of chemicals has been made on individual chemicals, but if we consider the manner of human exposure to chemicals, it is important to assess the effect of the combination of two or more different chemicals. In the present study, we evaluated the effect of combinations of model chemicals in the mouse peripheral reticulocyte micronucleus assay using the acridine orange supravital staining method, which has been