Publications by authors named "Minoru Omura"

Prenatal or early postnatal exposure to some synthetic chemicals may affect the later reproductive system of the offspring. There may also be unique responses observed due to exposure to combinations of chemicals that are not observed when the chemicals are present individually. 1,1-Dichloro-2,2 bis (p-chlorophenyl) ethylene (p,p'-DDE) is a persistent metabolite of DDT and tributyltin (TBT) compounds are used primarily as antifouling agents, as they exert biocidal actions.

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Prenatal or early postnatal exposure to some synthetic chemicals may affect the later reproductive system of the offspring, and there may also be unique responses observed due to exposure to combinations of chemicals that are not observed when the chemicals are present individually. Organochlorine compounds are ubiquitously distributed in the environment. p,p'-DDE (1,1-dichloro-2,2 bis (p-chlorophenyl) ethylene) is a persistent metabolite of DDT and 1,4-dichlorobenzene (DCB) is used as an air freshener or a moth repellent.

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Tributyltin and 1, 1-dichloro-2, 2 bis (p-chlorophenyl) ethylene (p,p'-DDE) have been ubiquitously distributed over the world. In Japan, p,p'-DDE and tributyltin are ingested through marine products, in which these substances are accumulated through bio-concentration and the food chain. However, the consequence of potential combined hazards of these substances remains unknown.

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In animal studies using oral dosing for short periods, di (2-ethylhexyl) phthalate (DEHP) is well known for its reproductive toxicity, especially for its testicular toxicity. However, extending the period of DEHP exposure in prepubertal rats resulted in significant increases in testosterone. This suggests that the reproductive effect of DEHP might be associated with the timing and the term of exposure.

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Assessments of the reproductive toxicity of organophosphorus insecticides are important public health issues. This study aimed at defining the testicular toxicity of dichlorvos (DDVP) since this toxicity was suspected by our previous survey on pesticide sprayers and in some earlier publications during the 1970s. Ten-week-old Wistar rats were divided into four groups (n=8 or 9) and were injected subcutaneously with DDVP (0, 1, 2 or 4 mg/kg) 6 days a week for 9 weeks.

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The distribution of tributyltin (TBT) and its metabolites, dibutyltin (DBT) and monobutyltin (MBT), was examined in the liver, brain and fat tissues in a two-generation reproductive toxicity study of tributyltin chloride (TBTCl) in rats using dietary supplementation at concentrations of 5, 25 and 125 ppm. In the liver, irrespective of TBTCl dietary concentration, gender or generation, the highest concentration of metabolite was consistently MBT, followed by DBT, and then TBT. In contrast, TBT was consistently present at the highest concentration in the brain, nearly always followed by DBT and MBT.

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Fat-containing variant of a solitary fibrous tumor is a recently recognized benign soft-tissue tumor that usually affects the thigh and retroperitoneum. We report a 51-year-old woman with a fat-containing variant of a solitary fibrous tumor that is the first reported case involving a visceral organ. The tumor was well delineated and seemed to arise from the renal capsule, radiographically and macroscopically.

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p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene; DDE] and tributyltin (TBT) are ubiquitous in the environment and in Japan were shown to bioaccumulate in marine products. Thus these chemicals serve as a source of contaminant in the mammalian food chain. Fetuses and neonates through maternal ingestion may be exposed to DDE and TBT.

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Systemic effects of p, p'-DDE (1, 1-dichloro-2, 2 bis (p-chlorophenyl) ethylene; DDE) on immature male rats were investigated in pubertal Wistar rats after oral administration of DDE. Special rat chow containing 125 ppm DDE (approximately 10 mg/kg DDE) had been administered daily for 42 d since 6 wk of age and its effects had been observed until 12 wk of age. The administration of DDE did not produce any overt signs of toxicity.

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p,p(')-DDE (DDE) and tributyltin (TBT) occur globally and in Japan were shown to bioaccumulate in marine products, thus serving as a source of contamination in the mammalian food chain. Consequently, fetuses and neonates, through maternal ingestion, may be exposed to DDE and TBT. Therefore, the effects of combined DDE and TBT were investigated in female Wistar rat offspring of dams ingesting these two contaminants.

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Systemic toxicity of p,p'-DDE (DDE) in aged male rats was investigated in Wistar rats by oral administration of DDE. About 10 mg/kg DDE had been daily administered for 28 days from 48 weeks to 52 weeks of age and its effects were observed subsequently. The administration of DDE did not give rise to any overt signs of toxicity.

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There is an endocrinological concern that environmental endocrine disrupters (EEDs) may influence sexual differentiation. Bisphenol A (BPA), one of EEDs, is released from polycarbonate plastics, and has been detected in the human umbilical cord. In this study, we examined the effect of BPA on the sexual differentiation of open-field behavior and the sexually dimorphic nuclei in the brain in the offspring of rats exposed to BPA during the fetal and suckling periods at a dosage below the human tolerable daily intake (TDI) level.

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Objectives: Testicular toxicities of antimony compounds were evaluated in rats and mice. The slightly water-soluble antimony compound antimony trioxide (ATO) and the highly water-soluble antimony compound antimony potassium tartrate (APT) were examined.

Methods: Daily doses of the compounds were 27.

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