28 research outputs found
In vitro pancreatic carcinogenesis
Studies in our laboratories have indicated that pancreatic cancer originates not only from pancreatic ductal/ductular cells but also from within the Langerhans' islets, probably from reserve (precursor, stem) cells. To identify, enrich and characterize these cells, we established a long-term hamster islet culture and studied their growth, differentiation and response to the pancreatic carcinogen, N-nitrosobis(2-oxopropyl)amine (BOP). One group of cultured islets was treated in vitro with BOP (KL5B group) and the other group of islets served as an untreated control (KL5N group). During the early culture days, in both groups all cultured islets showed a progressive loss of endocrine cells and replacement by ductular, acinar and intermediary cells. However, all these cells disappeared after 35 days in culture and gave room to undifferentiated cells, which we believe represent stem cells. No differences were found between KL5N and KL5B cells with regard to cell growth and differentiation until day 35, when the growth of the KL5B cells accelerated and the cells underwent increasing pleomorphism and atypia. At day 133, KL5B cells but not KL5N cells showed colony formation in soft agar and formed invasive, poorly differentiated adenocarcinomas of the ductal type when transplanted into hamsters. All of these tumors showed mutation of the K-ras gene and extensive chromosomal damage. We concluded that like ductal/ductular cells, certain cell populations within islets are responsive to the carcinogenic effect of BOP. We could not ascertain whether these cells present a preexisting (stem, reserve) cell population within the islets or transdifferentiated islet cell
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Treatment of experimental ovarian carcinoma with monthly injection of the agonist D-Trp-6-LH-RH: A preliminary report
Hormones, particularly gonadotropins, have been implicated in the development of ovarian cancer. Chronic administration of agonistic analogs of luteinizing-hormone releasing-hormone (LH-RH) induces an inhibition of the pituitary-gonadal axis. The blockade of the release of luteinizing-hormone and follicle-stimulating hormone (FSH) may exert a possible therapeutic effect on ovarian cancer. We examined the results of prolonged administration of D-Trp-6-LH-RH, an agonistic analog of LH-RH in experimental ovarian cancer. We used the recently developed ovarian cancer model in rats, which is produced by treatment of pregnant rats with
N-nitrosobis(2-oxopropyl)amine (BOP), following which a high incidence of ovarian tumors are induced in the offspring. In morphologic aspects the induced tumor resembles human ovarian neoplasms. Once a month administration of a delayed release preparation of microcapsules of D-Trp-6-LH-RH prolonged the survival and decreased tumor growth and the incidence of metastases. Additional experimental and clinical studies are needed to determine the efficacy of the treatment with LH-RH analogs in ovarian cancer
Modelisation de la mise en forme par calandrage de plaques de qualite optique en polymethylmetacrylate
CNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc