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At least 685 records · Page 38Linked to original sources
PubMed1993

Promotive effects of diethylstilbestrol, its metabolite (Z,Z-dienestrol) and a stereoisomer of the metabolite (E,E-dienestrol) in tumorigenesis of rat mammary glands pregnancy-dependently initiated with radiation.

Wistar-MS rats received whole body irradiation with 260 cGy gamma-rays at day 20 of pregnancy and then were treated with diethylstilbestrol (DES), E,E-dienestrol (E,E-DIES) or Z,Z-dienestrol (Z,Z-DIES) for 1 year. DES administration caused the highest incidence of mammary tumors with a concomitant reduction of gain in body weight. When E,E-DIES or Z,Z-DIES in pellet form was implanted, the incidence of tumors was significantly lower than that observed in rats treated with DES. To clarify the increased susceptibility to mammary tumorigenesis after DES administration we measured hormone levels in the serum of rats implanted with pellets containing derivatives of the synthetic estrogens. The serum prolactin concentration was significantly increased by DES administration. When E,E-DIES or Z,Z-DIES pellets were implanted the prolactin level was markedly reduced to 4.5% and 0.7% of that observed in DES-treated rats, respectively. In addition, the serum concentrations of estradiol-17 beta and progesterone in rats with Z,Z-DIES pellets were higher than those of rats with DES or E,E-DIES pellets. A large number of DES-induced mammary tumors were positive for both estrogen and progesterone receptors, but no tumors negative for both receptors were obtained. The findings suggest that DES acts directly on radiation-initiated mammary cells via binding with estrogen receptors and/or stimulates the secretion of prolactin from the pituitary glands.

Adenocarcinoma↗
PubMed1987

Recurrence of Cushing's disease in childhood after radiotherapy-induced remission.

A 16-year-old female patient with recurrent Cushing's disease (CD) underwent successful treatment with pituitary irradiation. Within one year after radiotherapy, cortisol levels had returned to normal (but with continued absence of diurnal variation), growth velocity improved, and puberty ensued. Five years after treatment, the patient developed clinical and biochemical evidence of recurrent CD. The high baseline evening corticotropin level (9 pmol/L [40 pg/mL]) was unresponsive (maximum level, 10 pmol/L [46 pg/mL]) to stimulation with ovine corticotropin-releasing hormone (CRF). In patients with CD treated with radiotherapy, the corticotropin response to CRF stimulation may not be reliably compared with that of normal control values. After pituitary adenomectomy, the corticotropin concentration was still unresponsive to CRF. We suggest that the pituitary tumor was secondary to abnormal hypothalamic CRF regulation not corrected by pituitary irradiation; therefore, CD may recur despite pituitary irradiation.

Adenoma↗
PubMed2000

Radiation-induced mammary tumors in virgin and parous rats administered contraceptive steroids, 17alpha-ethinylestradiol and norethisterone.

Oral contraceptives are used among women worldwide, and radiation is being used increasingly for diagnosis or therapy. We have investigated the effects of contraceptive steroids on the risk of mammary tumors initiated by radiation. Virgin rats received whole-body irradiation with 2.6 Gy gamma-rays 1 month after the administration of low- or high-dose pellets of contraceptive steroids, such as 17alpha-ethinylestradiol (EE(2)) combined with 19-norethisterone (NET). The high-dose pellet was removed 1 month after irradiation, but administration of the low-dose pellet was continued for up to 1 year. The incidence (33.3%) of mammary tumors initiated with radiation was not modified by the long-term administration of the low-dose pellets. However, the incidence (58. 3%) was increased significantly by the irradiation during administration of the high-dose pellets, but no significant difference in the proportion of adenocarcinoma and fibroadenoma was observed. Meanwhile, parous rats were irradiated with 2.6 Gy gamma-rays at weaning, a period of greater susceptibility to radiation, and then were implanted with the low-dose pellets 1 month later. The highest incidence (90%) of mammary tumors was detected in the parous rats. The proportion of adenocarcinomas in the parous irradiated rats increased significantly on treatment with the low-dose pellets. The results suggest that administration of the high-dose pellets of EE(2)-NET, but not of the low-dose pellets, enhances susceptibility to the initiation by gamma-rays of mammary tumors in virgin rats, and that the low-dose pellets act as a tumor promoter in the mammary glands of parous rats irradiated at weaning.

Animals↗
PubMed1989

Cushing's syndrome: analysis of 188 cases.

From January 1962 through April 1988, 188 patients with Cushing's syndrome were hospitalized at the Veterans General Hospital. Iatrogenic Cushing's syndrome was found in 123 (65.4%) of the patients. The other 43 patients (22.9%) had excess secretion of adrenocorticotropin (ACTH) and 22 patients (11.7%) had benign or malignant adrenocortical tumors. The clinical features and the functional reserve of the adrenal glands in those patients with iatrogenic Cushing's syndrome were evaluated. A retrospective analysis of the diagnostic rate of the various endocrine evaluations and the radiological examinations was also carried out. Four approaches were used in the management of Cushing's syndrome: (1) pituitary surgery, (2) pituitary irradiation, (3) adrenal surgery, and (4) drug therapy. Both the clinical and hormonal responses to these four management types were evaluated. The endocrinological, radiological, surgical and pathological experiences of 25 patients with Cushing's disease treated with pituitary surgery are presented. Five patients (20%) had an atypical endocrine pattern (20% false-negative). Twenty-four patients received a pituitary CT scan and 16 patients (66.7%) had positive CT findings. Of these 25 patients, 19 had pathology-proven microadenomas (less than 1cm), one had macroadenoma (greater than 1cm) and 5 had no evidence of adenomatous tissue. Among the 22 patients with adrenal Cushing's syndrome, 4 (18%) were suffering from adrenocortical carcinoma and 18 (82%) with benign adrenal tumors. The incidence of left adrenal adenoma was approximately twice that of right adrenal adenoma. The cure rate of adrenocortical adenoma by surgical treatment with unilateral adrenalectomy was excellent, but for adrenocortical carcinoma was poor.

Adolescent↗
PubMed1988

Thyroid and pituitary function following allogeneic bone marrow transplantation.

Thyroid function was evaluated in 13 consecutive patients with chronic myelogenous leukemia to verify in allogeneic bone marrow transplantation if the fractionated irradiation protocol with low dose rate, previously applied to reduce the damage to various organs, also prevents the 43% incidence of primary hypothyroidism that occurs after the administration of single dose with higher dose rate. Following bone marrow transplantation, decreased plasma levels of total thyroxine and triiodothyronine and impaired response of thyrotropic cells to thyrotropin-releasing hormone were observed. These alterations reverted to normal in nine months and none of the patients was hypothyroid at the end of follow-up. The damage to thyrotropic cells appears to be selective because the secretion of prolactin was not impaired and that of gonadotropins even increased, as a consequence of gonadal failure. Longer follow-up is needed to determine if this irradiation protocol, which prevents the complication of permanent primary hypothyroidism and does not cause any destruction of thyroid cells, may increase the risk of irradiation-related thyroid tumors.

Adolescent↗