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Biomedical subjects

B C Zook

Publications and source records attributed to B C Zook.

At least 55 records · Page 3Linked to original sources
PubMed1970

Demyelinating encephalomyelopathy associated with lead poisoning in nonhuman primates.

Lead poisoning was diagnosed in four primates by the finding of toxic amounts of lead in tissues. Abnormalities in the brain and spinal cord were characterized by vascular lesions and demyelination. These findings suggest a new animal model for the study of demyelination and strengthen the supposition that lead may be a factor in some idiopathic demyelinating diseases.

Animals↗
PubMedDate not supplied

The development and regression of deciduosarcomas and other lesions caused by estrogens and progestins in rabbits.

A series of experiments were conducted to study the histopathological effects of a combination of exogenous estrogens and progestins in mature rabbits. Estradiol (14-45 microg/day) and levonorgestrel (30-233 microg/day) were administered by intravaginal or subdermal Silastic devices for various time intervals to study the development of lesions with time and to determine if lesions regressed following withdrawal of the steroids. The origin of splenic decidual tumors (primary or metastasis from the uterus) was determined by administering the same steroid combination to castrated male rabbits. It was determined that uterine decidualization is present after 7 days of steroid treatment and that neoplasms of decidual cells may appear in the uterus after only 30 days of steroid administration. Decidual changes were observed frequently in uterine arteries, often concurrent with infarct-like areas of necrosis of the uterine wall. Withdrawal of contraceptive steroids for 14-120 days after 60 days' administration resulted in atrophy and disappearance of decidual cells and decidual tumors. Decidual neoplasms developed in the spleen of all castrated male rabbits given subdermal steroids, demonstrating that these tumors can arise as primary neoplasms of the spleen. The foregoing lesions appear to be peculiar to the rabbit and, together with previous data, suggest the rabbit to be a poor model for evaluating the effects of contraceptive steroids in other species.

Animals↗
PubMedDate not supplied

The roles of estrogen and progestin in producing deciduosarcoma and other lesions in the rabbit.

The interactions of estrogens and progestins in producing decidualization, deciduosarcoma. and other lesions in the rabbit were explored. Steroids were delivered by silicone elastomer implants placed subdermally except for oral dosing in 1 experiment. Varying doses of levonorgestrel (LNG) were given with and without estradiol (E2) and varying doses of E2 with and without LNG. LNG alone delivered at an estimated mean dose of 233 microg/day did not result in endometrial decidualization or deciduosarcoma. Both conditions occurred when E2 was added to the regimen and increased as the dose of E2 was increased. Sixty microg of E2 per day produced endometrial decidualization in all test animals in a 2-month exposure, but deciduosarcoma occurred only when LNG was also supplied and increased as the LNG dose was increased. Progesterone given with E2 resulted in deciduosarcoma in most rabbits. Ethynylestradiol alone at 30 microg/day delivered by implants produced splenic and ovarian deciduosarcomas in 1 of 5 test animals. Adding LNG resulted in more numerous and widespread deciduosarcomas. These experiments indicate that exogenous estrogen is necessary for decidualization of the endometrium and to production of deciduosarcoma in the nonpregnant rabbit. Exogenous progestin promotes the process. Necrosis of the uterine wall tended to increase with increasing dose of estrogens.

Administration, Oral↗