PubMed Health⌕ Search

Biomedical subjects

J Schechter

Publications and source records attributed to J Schechter.

At least 73 records · Page 4Linked to original sources
PubMed1985

Hormonal and morphologic effects of bromocriptine on normal rat pituitary and GH3 tumor cells.

Bromocriptine in concentrations up to 5 X 10(-4) mol/L was studied for any deleterious effects upon normal rat pituitary cells, as well as on the rat GH3 cell line. Normal rat pituitary glands were obtained by decapitation from 50-day-old female Wistar rats and dispersed with 0.25% trypsin. The cells (10(5) per plate) were then incubated in 60 by 15 mm plates (Falcon) that contained 3 ml of Dulbecco's modified Eagle's medium with 10% fetal calf serum. GH3 cells were plated in a similar fashion. Bromocriptine was added in concentrations of 5 X 10(-4) to 5 X 10(-9) mol/L, and aliquots of medium were obtained at 6, 24, and 48 hours for the determination of growth hormone and prolactin. Cell counts were performed at 24 and 48 hours. A significant reduction in concentrations of growth hormone and prolactin was observed with concentrations of bromocriptine of 5 X 10(-5) and 5 X 10(-4) mol/L at 24 and 48 hours (p less than 001). Although no significant changes in cell counts were observed in the normal rat pituitary cells, the GH3 cells showed complete disruption at 48 hours only in the plates that contained the highest concentrations of bromocriptine. Electron microscopy of normal rat cells and GH3 demonstrated selective cytotoxic effects only on the GH3 cells. In conclusion, bromocriptine has been demonstrated to have a direct effect on hormone release and on the morphologic characteristics of tumor cells but not normal pituitary cells.

Animals↗
PubMed1985

Growth and pubertal development in patients with congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency.

To evaluate growth and pubertal development in patients with congenital adrenal hyperplasia due to 11-beta-hydroxylase deficiency, data were collected retrospectively from the charts of 24 patients, 15 girls and nine boys. Growth before diagnosis was characterized by a rapid acceleration in the second half of the first year of life, with rapid advancement of bone age. Final height was severely compromised in all the patients, regardless of age at diagnosis and quality of therapeutic control. Onset of puberty was precocious in male patients and normal in female patients. In this respect, treatment with hydrocortisone acetate proved to be superior to cortisone acetate or prednisone.

Adolescent↗
PubMed1985

Mesenchymal influences on the development of the adenohypophysis in the rat.

Comparative studies have been made of development of the adenohypophysis using the Rathke's pouch (RP)-derived model system. Rathke's pouch with associated mesenchyme and ventral hypothalamus, was microsurgically isolated from 15-day fetal rats and placed in mild trypsin solution. Three variations of donor tissue were isolated and transplanted beneath the kidney capsule of adult hosts: A) pure pouch epithelium; B) pouch epithelium plus mesenchyme; and C) pouch epithelium with mesenchyme and ventral hypothalamus. After 30 days the grafts were isolated and processed for light and electron microscopy. Cell types were characterized by immunostaining as well as by morphological criteria. In group A well differentiated mammotrophs dominated the grafts, many of which were hypertrophied with widely dilated endoplasmic reticulum and Golgi saccules. Mammotrophs, frequently with mitotic figures, were distributed evenly throughout the grafts. Somatotrophs and gonadotrophs were neither abundant nor well differentiated in group A, but were both abundant and more extensively differentiated in groups B and C. Both somatotrophs and gonadotrophs were typically localized at margins of the graft adjacent to connective tissue spaces. Well differentiated mammotrophs were present in groups B and C although there were fewer hypertrophied mammotrophs than in group A; and immunoreaction to prolactin was weaker than in group A. Tumor-like features found in all three groups included some loss of tissue integrity and large, vascular lakes unlined by endothelium. These findings suggest that differentiation of mammotrophs may be inhibited in part by mesenchyme associated with Rathke's pouch, since in the absence thereof these cells become hyperplastic. Conversely, differentiation of somatotrophs and gonadotrophs appears more dependent on these mesenchymal elements for normal development.

Animals↗
PubMed1985

Cutaneous malignant lymphoma: a clinical and pathological study of 13 cases.

Thirteen cases of malignant lymphoma, exclusive of mycosis fungoides, with initial involvement of the skin, were selected from 391 consecutive patients with non-Hodgkin's lymphoma. Their clinical course was correlated to histological subtype. All patients (5/5) with 'favourable' histology had single indurated plaques without extracutaneous involvement, and remained in complete remission for at least 5 years after local radiation therapy. In contrast, all those with 'unfavourable' histology not lost to follow-up (7/7) suffered relapse or died within a 2-year period. They generally had multiple skin lesions and extracutaneous involvement at diagnosis or shortly afterwards. We conclude that histological subtype is an important variable in predicting clinical course in those with cutaneous malignant lymphoma.

Adult↗
PubMed1984

The development of mammotroph adenomas in pituitaries of aging female C57BL/6J mice.

The development of pituitary adenomas in female C57BL/6J mice was studied over the lifespan. Mammotrophs and somatotrophs, identified by immunocytochemical staining, appeared normal in 3-4 month old animals, with the exception of an occasional hypertrophic mammotroph and, in one gland, a nest of such cells. At 15 months, hypertrophic mammotrophs, somatotrophs and unstained cells occurred singly or in areas of hyperplasia; a mammotrophic adenoma was present in one gland. At 22 months, pituitaries contained mammotroph adenomas or adenomalike mammotroph clusters within hypertrophic, hyperplastic areas as seen in 15 month old glands. Pituitaries from all 28-30 month old mice contained mammotroph adenomas; nests of hypertrophic cells were present in 5 of 8 glands studied. These results suggest that mammotrophic adenomas may arise from hypertrophic mammotrophs, which are often found in nests with other hypertrophic pituitary cell types. However, this study does not exclude the possibility that mammotroph adenomas and hypertrophic mammotrophs occur independently.

Adenoma↗
PubMed1984

Isolated growth hormone deficiency: immunocytochemistry.

Light and electron microscopic immunocytochemistry of the pituitary gland of a patient with documented isolated GH deficiency revealed parenchyma rich in GH positive cells. Immunoprecipitate was localized consistently over membrane-enclosed secretory granules whose features were characteristic of those in normal somatotrophs. No profiles of exocytosis of the contents of the secretory granules were observed. These observations demonstrate that the type I recessive form of isolated GH deficiency may be associated with apparently normal appearing somatotrophs which contain immunoreactive GH.

Aged↗
PubMed1982

Comparison of gonadotroph, thyrotroph and mammotroph development in situ, in transplants and in organ culture.

This study was conducted to examine the role of the hypothalamus in development of gonadotrophs, thyrotrophs, and mammotrophs up to the time of birth in the rat. The development of the in situ newborn pituitary (22 days post-coitus; dpc) was compared with the development of 12 and 15 dpc pituitary anlagen grown under the kidney capsule of an adult host or in organ culture for a time period equivalent to 22 days of gestation. Morphological development was evaluated by light microscopic histology and gonadotrophin immunocytochemistry. Functional development was analyzed by radioimmunoassay determination of luteinizing hormone, thyrotrophin, and prolactin content of the in situ, kidney capsule grafted, and organ-cultured pituitary. The results provide evidence that factors, perhaps blood-borne, play a significant role in pituitary development but that direct hypothalamic influences are of minimal importance in the development of gonadotrophs and mammotrophs. The fetal hypothalamus may play a significant role in stimulating high storage levels of thyrotrophin in the prenatal pituitary.

Animals↗
PubMed1980

Calcium and the secretory cycle of prolactin cells: a cytochemical and ultrastructural study of dopamine inhibition and monobutyryl cyclic AMP-stimulation of prolactin secretion.

To identify intracellular calcium pools that may be involved in the secretory process in prolactin (PRL) cells, hemi pituitaries were incubated in medium containing 10(-6) M dopamine, 5 mM cyclic cAMP (experimentals), or in medium alone (controls) and then processed for electron microscopy using potassium pyroantimonate to localize intracellular calcium. PRL in the medium was measured by radioimmunoassay. The concentration of antimonate associated with mitochondria, Golgi saccules, and secretory granules was estimated. Dopamine inhibition of PRL secretion (> 80% at 1, 2, 3 h) resulted in accumulation of secretory granules in all stages of maturation and dilation of Golgi saccules at 2 and 3 h, accompanied by increased mitochondria antimonate and increased Golgi-associated antimonate. Cyclic AMP stimulation of secretion (635% at 5 min., declining to 34% at 1 h) resulted in marked exocytosis at 5 and 15 min., declining after 30 min. Mitochondrial antimonate decreased after 30 min. Stimulated cells exhibited numerous coated membrane structures at or near exocytotic pits and an amassing of microvesicles at the margin of the Golgi apparatus. Although some secretory granules consistently exhibited reactivity to antimonate (unchanged by inhibition or stimulation), plasma membrane, and granule membrane translocated to the plasma membrane during exocytosis, were not reactive.

Animals↗