| Co-Investigator(Kenkyū-buntansha) |
HIRATA Miyuki KYUSHU UNIVERSITY, MEDICINE, RESEARCH ASSOCIATE, 医学部, 助手 (30156674)
TANAKA Akiyo KYUSHU UNIVERSITY, MEDICINE, RESEARCH ASSOCIATE, 医学部, 助手 (10136484)
HISANAGA Akira KYUSHU UNIVERSITY, MEDICINE, ASSISTANT PROFESSOR, 医学部, 講師 (20128078)
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| Research Abstract |
Immuno toxicity of inorganic metal compounds was studied in male Syrian golden hamsters given intermittent intratracheal instillations.
In first experiment, the tumorigenicity or interaction effect of metal nickel(Ni), as a positive control, metal manganese(Mn) and arsenic selenide(As2Se3) was studied in male Syrian golden hamsters which received each metal compounds containing a total dose of 7.5 mg Ni, Mn or As by means of intratracheal instillations once a week for 15 weeks. As a controls, some hamsters were treated with only the vehicle, phosphate buffer solution. All hamsters were observed during their entire life span. The materials treated by intratracheal instillations did not significantly effect the cumulative body-weight gain of the hamsters. The lower survival rate was observed in the Ni group compared with that of the Ni+Mn group, and the difference in the survival rates between Ni and Ni+Mn group was statistically significant. During the animal's total life span, one lung
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adenoma was seen in the 23 hamsters in the control group. But no tumors were observed in the respiratory tracts in any group except the control group. Besides lung tumor formation, columnar or cuboidal epithelial hyperplasia with or without squamous metaplasia or deposition of metal particles in the alveolar space or alveolar septa were observed in the Ni, Ni+Mn and As_2Se_3 group and the incidence rates of these lesions were significantly different from that in the control group. The total tumor incidence rates including the respiratory tracts were 8.7% in the control group, 4.0% in the Ni group, 26.9% in the Ni+Mn group and 10.3% in the As_2Se_3. The incidences of total tumors in the groups given Ni, Ni+Mn and As_2Se_3 were not significantly greater than that in the control group according the chi-square test. In the scanning electron microscopic findings, the main lesions observed in the alveolar region were the deposition of each metal particles, the accumulations of macrophages in the alveoli and the thickening the alveolar walls, which lesions were more frequently observed in the alveolar region than in the bronchiolar region.
In second experiment, comparative chronic toxicity, including tumorigenicity, of arsenic trioxide(As_2O_3), gallium arsenide(GaAs), chromium trioxide(Cr_2O_3), nickel oxide(NiO) and benzo(a)pyrene(B(a)P), as a positive control, were studied using male Syrian golden hamsters given intermittent intratracheal instillations. GaAs particles were likely to produce relatively severe lung damage and the survival of the hamsters was shortened significantly compared with a control group. The total tumor incidence including the respiratory tracts was 3.3 % in the As_2o_3 group, 3.3% in the GaAs group, 0% in the Cr_2O_3, 3.3% in the NiO group, 6.8 % in the B(a)P group and 3.3% in the control group, and no significant difference between the each metal or B(a)P treatedgroup and the control group was found.
From these study, the tumorigenicity of inorganic metal compounds were not ascertained in the respiratory tracts or other organs of hamsters. But it seems that Mn particles enhance the shortened survival period induced by Ni treated. Less
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