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Biomedical subjects

K Takemoto

Publications and source records attributed to K Takemoto.

At least 109 records · Page 6Linked to original sources
PubMed1986

Effects of chronic inhalation exposure to diesel exhaust on the development of lung tumors in di-isopropanol-nitrosamine-treated F344 rats and newborn C57BL and ICR mice.

Long-term exposure to diesel exhaust from a small diesel engine was carried out in order to elucidate the effects of exhaust on the development of lung tumors in F344 rats and newborn ICR and C57BL mice. The deposition of inhaled particles progressed in accordance with duration of exposure in both sets of the animals. No evidence of lung tumor formation was detected following exposure to diesel exhaust alone in rats. However, the combined treatment with DIPN and diesel exhaust led to an overadditive effect in the development of lung tumors. There was a tendency for the diesel-exposed mice to have higher incidences of lung tumors compared with non-exposed mice. The results obtained in the present study suggest that diesel exhaust may act as a factor relating to human respiratory carcinogenesis.

Adenocarcinoma↗
PubMed1986

Separation of purine derivatives by polymer-bound nucleic acid bases.

Separation of a variety of purine bases, which include 7-methyl derivatives, was studied by using polyethyleneimine-coated silicagel which bound hypoxanthine, cytosine or guanine moieties. The separation behavior seems to be related to the interaction of imidazole part of purine derivatives with the resins through hydrogen bonding.

Chromatography, Affinity↗
PubMed1986

Carcinogenic effects of a mixture of nitropyrenes in F344 rats following its repeated oral administrations.

The carcinogenic effects of a mixture of 1-nitropyrene and three dinitropyrenes (1,3-, 1,6- and 1,8-dinitropyrene) were investigated in rats. Female F344/Jcl rats were given one of three doses (5, 10 and 20 mg/kg body weight) of the mixture by repeated intragastric instillations twice a week for 55 weeks, and then autopsied 49 weeks later. Mammary adenocarcinomas were induced in rats of all the three experimental groups dose-dependently, while no adenocarcinoma was induced in the control rats which were given only vehicle. Clitoral gland tumors, most of which were diagnosed as squamous cell carcinomas, were also commonly observed in the NP-treated rats in a dose-dependent way. In addition, high incidences of mononuclear cell leukemias were noted in the NP-treated rats. Other tumors were frequently induced in the uterus and endocrine organs, such as the pituitary, adrenal, and thyroid glands. However, the incidences of these tumors were almost equal in both the control and NP-treated groups. The results of the present study indicated the potential carcinogenic activities of nitropyrene compounds in female rats when they were treated by oral route, and suggest that the oral intake of nitropyrene compounds might be related to the incidence of cancer in humans.

Administration, Oral↗
PubMed1985

The origin of prespore vacuoles in Dictyostelium discoideum cells as analysed by electron-microscopic immunocytochemistry and radioautography.

Prespore vacuoles (PSVs) are specifically formed in prespore cells of the cellular slime moulds and contain spore-specific antigens. We have examined the processes of PSV formation in Dictyostelium discoideum, using both the methods of immunoelectron microscopy with antispore serum and electron-microscopic radioautography with [3H]fucose, which is specifically incorporated into prespore cells. When prespore cells begin to differentiate at the late aggregation stages the Golgi apparatus, consisting of stacked cisternae and numerous vesicles, becomes conspicuous. Vesicles and flat sacs containing fibrous and membranous materials, respectively, are derived from Golgi cisternae. Spore antigens are found in these structures as well as in immature and mature PSVs. Fucose is incorporated into the same structures. When prespore differentiation is completed, the Golgi cisternae almost disappear and both antigens and fucose are localized in mature PSVs. The Golgi apparatus is scarcely observable in prestalk cells. Moreover, a similar pattern of changes in the Golgi apparatus and related structures occurs during the re-differentiation of prespore cells within prestalk isolates. It is concluded from these findings that PSVs are derived from the Golgi apparatus, the development of which is closely related to the differentiation of prespore cells.

Autoradiography↗
PubMed1985

Synthesis of poly-L-glutamates containing 5-substituted uracil moieties.

The polymer reaction of cyclic derivatives of uracil and 5-bromouracil with polyacrylic and polymethacrylic acids, and poly-L-glutamic acid was studied in dimethylformamide solution. A similar reaction of cyclic derivatives of uridine with the polymeric acids was also made. Alkaline hydrolysis was further carried out on the polymers obtained.

Indicators and Reagents↗
PubMed1985

Lung cancer in chromate workers--analysis of 11 cases.

We have experienced 11 cases of lung carcinoma in workers at a chromate factory during the past 14 years. All patients were males. The age of onset ranged from 41 to 68 years. Ten of the 11 were heavy smokers. The time of exposure to chromate was from 17 to 29 years and the average was 23.9 years. Seven patients had perforation of their nasal septa. The primary sites of the cancers were from the lobar to the subsegmental bronchi. There were nine squamous cell carcinomas and three small cell carcinomas. Four squamous cell carcinomas were hilar type early stage cancers and two of them were found in one patient at the same time. The chromium content of the lung tissue in the seven patients tested was from 13.9 to 2,368.4 micrograms/g of dry tissue and was higher than that of lung cancer or non-lung cancer cases without chromate exposure. There was no severe dysplasia of the bronchial epithelium in these 11 patients.

Adult↗