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Biomedical subjects

H Iwasawa

Publications and source records attributed to H Iwasawa.

69 records · Page 4Linked to original sources
PubMed1982

Spontaneous occurrence of atypical hyperplasia and adenocarcinoma of the uterus in androgen-sterilized SD rats.

In SD female rats sterilized by a single injection of testosterone propionate at 2 days after birth, the spontaneous occurrence of atypical hyperplasia and adenocarcinoma of the uterus was observed for a fairly long period (greater than 2 yr). Two atypical hyperplasias and 2 adenocarcinomas were detected in 25 androgen-sterilized rats (ASR) after 500 days of age; in contrast, in 111 normal control rats no abnormal uterine proliferation was detected during a 750-day observation period. These results indicate that a persistence of both hormone imbalances and dysfunctional uteri in ASR induces abnormal uterine proliferation at a late age.

Adenocarcinoma↗
PubMed1982

[Experimental studies on spontaneous occurrence of uterine adenocarcinoma (author's transl)].

Abnormal uterine proliferation was not detected in all 111 control normal rats (NR) during 750 days' observation period. In androgen sterile rats (ASR), 4 squamous metaplasias were detected in 25 ASR at 70-100 days of age. Thereafter, 9 squamous metaplasias and 2 non-atypical hyperplasias were detected in 20 ASR at 200-360 days of age. At 500-750 days of age, 12 squamous metaplasias, one non-atypical hyperplasia, 2 atypical hyperplasias and 2 adenocarcinomas were detected. Histological examination revealed that one of adenocarcinoma was composed of well differentiated type, poorly differentiated type and squamous metaplasia. Another case was composed of poorly differentiated adenocarcinoma, squamous cell carcinoma and squamous metaplasia. Hormonal environment of ASR with adenocarcinoma was characterized by an increase in estrogen/progesterone ratio, as compared to NR. After 500 days of age, 2 pituitary, 6 mammary and 3 adrenal tumors were detected in 33 NR, whereas 2 pituitary and 2 mammary tumors were detected in 25 ASR.

Adenocarcinoma↗
PubMed1981

[Experimental teratoma by fetectomy in the rats : influence of ovariectomy (author's transl)].

Forty-six female Sprague-Dawley rats were used. Twelve days after mating, all the fetuses were removed and fetal membrane with yolk sac were left outside of the uterus following the method reported by Sorbis and Vandeputte (1974). About the half of the rats were ovariectomized at the laparotomy. The rats were killed at 20 and 40 weeks after treatment and examined. No difference was observed in tumor incidence between fetectomy alone and fetectomy plus ovariectomy at both 20 and 40 weeks and it was about 70%. The size of tumor varied from 2 to 35 mm in diameter. The size of tumors tended to be greater in fetectomy plus ovariectomy compared with fetectomy alone at 20 weeks, but no significant difference was observed at 40 weeks between the two groups. Histologically the tumors were characterized by the presence of a variety of differentiated tissues. Metastases to the visceral part were detected in 2 rats of fetectomy alone and the tumors were diagnosed as yolk sac tumor. These results indicate that sex steroids might influence the teratocarcinogenesis.

Animals↗
PubMed1979

In vivo and in vitro studies of experimental ovarian adenocarcinoma in rats.

When 7,12-dimethylbenz[a]anthracene-impregnated sutures were directly applied to the ovarian parenchyma of 8-week-old Sprague-Dawley rats (the clipping method), adenocarcinomas developed in 29 (39%) of the 75 rats during the 50-week observation period. When 20-methylcholanthrene was used, adenocarcinomas developed only in 1 (3%) of the 31 rats. Thus, the clipping method using 7,12-dimethylbenz[a]anthracene is satisfactory as an animal model of ovarian adenocarcinoma which comprises 85 to 90% of human malignant ovarian tumors. On the other hand, attempts were made to isolate cloned cell lines from these experimental ovarian adenocarcinomas in vitro, and two cloned cell lines were obtained. They were epithelioid and produced undifferentiated adenocarcinomas by back-transplantation into isologous newborn rats.

9,10-Dimethyl-1,2-benzanthracene↗