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Biomedical subjects

D C Herbert

Publications and source records attributed to D C Herbert.

At least 109 records · Page 6Linked to original sources
PubMed1979

Intercellular junctions in the rhesus monkey pars distalis.

Four rhesus monkey pituitary glands were examined by transmission electron microscopy. Three types of intercellular junctions, desmosomes, hemidesmosomes and zonula adherens-type junctions, were observed between adjacent granular cells, folliculo-stellate cells, and joining a folliculo-stellate cell with a granular cell. Demosomes were most commonly observed between granular cells while the zonula adherens-type junctions were generally found between the folliculo-stellate cells.

Animals↗
PubMed1979

Evidence for the autoregulation of hormone secretion by prolactin.

The cells from the 2B8 clonal strain of pituitary cells which previously have been reported to produce only PRL were incubated with varying amounts of ovine PRL (oPRL) ranging from 0.01--1000 ng/ml. After 1 h, significantly less PRL was measured in culture media from cells incubated with all doses of oPRL employed. This inhibition was dose related. The cells were rinsed five times with Hank's balanced salt solution and subsequently placed into PRL-free media for an additional hour. Hypersecretion of hormone occurred from those cells previously exposed to 1--1000 ng/ml oPRL. The PRL in the media from cells previously exposed to 0.01--0.1 ng/ml was similar to that in the control culture. In some experiments, the cellular concentration of PRL was determined at the end of each of the two 1-h incubation periods. After the initial exposure to oPRL, an increase in intracellular hormone was observed only in those groups incubated with 1--1000 ng/ml oPRL. In contrast, after the cells were rinsed and placed into PRL-free medium, the cellular concentration of PRL was unchanged in all groups except the group previously exposed to 100 ng/ml oPRL. These data indicate that PRL can inhibit its own secretion through direct action on the lactotrophs of the anterior pituitary gland.

Animals↗
PubMed1978

Immunocytological localization of LH, FSH, TSH and their subunits in the pituitary of normal and anencephalic human fetuses.

Immunostaining with antisera to oLH, hCG, hLH, pLHbeta, hFSH, hFSHbeta, hTSHalpha and bTSH was used to delineate the gonadotropic and thyrotropic cells of the human fetal anterior pituitary. Hypophyses from 29 normal fetuses, 3 newborn infants, and 5 totally ancencephalic fetuses were used. Several controls to check for the specificty of the immunocytological reaction were made. In normal fetuses, observations showed that: 1) the alpha subunit was detected from the eighth week and throughout gestation without sex differences; 2) intact LH was detected during the third month, however, age and sex differences were observed during the fourth and fifth months; 3) intact FSH was detected in female fetuses from the beginning of the fourth month, a sex difference was observed; 4) LH and FSH were detected in the same cells; 5) the thyrotropic cells were detectable from 15 weeks of gestation and their number increased during gestation without sex difference; 6) at birth the gonadotropic cells were scarce and were located in the ventromedian zone of the anterior pituitary, while the thyrotopic cells remained numerous and were located in the dorsomedian zone. In amencephalic fetuses: 1) the alpha subunit existed at each stage studies; 2) the reaction induced by anti-pLHbeta and anti-hFSHbeta sera was alwys very weak regardless of sex or age; 3) the thyrotropic cells were more numerous in comparison to the gonadotropic cells. These data are discussed in terms of the relationship of the hypophysiotropic hypothalamic factors to the appearance and evolution of the glycoprotein hormones and their subunits.

Anencephaly↗
PubMed1978

Identification of the LH and TSH-secreting cells in the pituitary gland of the rhesus monkey.

Pituitary glands from juvenile (pre-pubertal) and adult male and female rhesus monkeys were examined following immunocytochemical staining with antisera to the beta subunits of ovine luteinizing hormone (LHbeta) and of human thyroid stimulating hormone (TSHbeta). The LHbeta antiserum reacts with a cell that is PAS-positive, occurs singly and is randomly distributed throughout the pars distalis. The diameter of these cells is approximately 11.5 micrometer. They do not seem to vary in number in either juveniles (pre-pubertals) or adults, or in males or females. There appears to be fewer LH cells in the pituitary glands of pregnant and lactating females. In addition to staining cells in the pars distalis, the antiserum also reacts with a population of cells located in the pars tuberalis. The cells that stain with the anti-TSHbeta serum are confined primarily to the pars distalis. They are approximately 15.8 micrometer in diameter and are generally found in groups or clusters located in the anterior and medical regions of the gland. The TSH cells vary in number from one animal to another; however, this variability is unrelated to the age or the sex of the animals. No demonstrable changes occur in the number of TSH cells during pregnancy or lactation.

Animals↗
PubMed1978

A subcutaneous pedicled cheek flap for reconstruction of alar defects.

The anatomy of the blood supply around the alar region was studied and showed that a large flap of nasolabial skin would survive on a narrow subcutaneous pedicle containing sufficient arteries and veins to justify the term "axial patterned flap". The secondary defect is closed with another nasolabial flap. In many cases a definitive single stage repair may be achieved. In others, some secondary revision has been required.

Adult↗
PubMed1978

Coated vesicles in the rat anterior pituitary gland.

Ultrastructural documentation of the formation of coated vesicles in prolactin cells of the rat anterior pituitary gland is presented. Coated vesicles were observed forming from the secretory granular membrane in the Golgi area and between the Golgi complex and the plasmalemma. They were also found budding off the membrane lining the exocytotic pocket. Following peroxidase reaction product could be seen forming from the membrane of the exocytotic pocket and adjacent to it. These vesicles were found in transit towards the Golgi area or within lysosomes. It is proposed that these coated vesicles are important for membrane conservation and that this is occurring in developing secretory granules near the Golgi complex, in more mature secretory granules and at the level of the plasmalemma during exocytosis.

Animals↗
PubMed1978

Serum estradiol, testosterone and dihydrotestosterone in male monkeys treated with testosterone propionate.

Serum estradiol (E2), testosterone (T) and dihydrotestosterone (DHT) were measured in juvenile (pre-pubertal) male rhesus monkeys injected with either 8 mg or 80 mg of testosterone propionate (TP). After one week, the three steroids were elevated and remained essentially unchanged for the duration of the study. There was little difference in serum E2 or DHT when comparing the two groups of steroid-treated monkeys. In contrast, T levels were consistently greater in the animals given the high dosage of TP.

Animals↗
PubMed1978

Elevation of serum prolactin levels after the inhibition of serotonin uptake.

Although earlier investigators showed that serotonin produced an elevation in serum PRL, recent studies indicate that serotonergic mechanisms are not of importance, at least in older adult animals, in the tonic regulation of serum PRL levels. As the activity of neuronal pathways may vary in activity at different chronological ages, the present study was undertaken to further evaluate the role of serotonergic pathways in the regulation of serum PRL levels. During the course of the study, animals in two different weight ranges were studied. In the initial studies, young male rats in the 120- to 170-g range were studied, while in later studies male rats in the 250-340-g weight range were utilized. In rats weighing 120-170 g, the administration of fluoxetine (Lilly 110140), an inhibitor of serotonin uptake, produced a significant elevation of serum PRL which persisted for at least 8 h. At the same time, diencephalon 5-hydroxyindoleacetic acid levels were decreased, providing evidence of the effectiveness of the drug treatment. Methysergide completely blocked the effect of fluoxetine and markedly suppressed serum PRL concentration. In agreement with the results of others, fluoxetine did not produce an increase in serum PRL in older male rats (250-340 g). However, fluoxetine seemed to suppress the circadian elevation of serum PRL in these older rats. These data provide evidence that serotonergic pathways may be of more importance in the tonic regulation of serum PRL in young male Sprague-Dawley rats. The specific pathways involved cannot be determined from these studies.

Aging↗
PubMed1978

Casein and alpha-lactalbumin detection in breast cancer cells by immunocytochemistry.

Casein and alpha-lactalbumin are characteristic proteins produced by normal mammary cells under hormonal stimulation. Specific antisera were used to immunochemically stain for these two proteins in the unstimulated R3230AC transplantable rat mammary tumor as well as in normal lactating rat mammary tissue. Specific staining was observed in the lactating rat alveolar epithelial cells and in the cells lining the intraalveolar ducts with both antisera. In the R3230AC tumor some cells were shown to contain casein or alpha-lactalbumin; the majority of the tumor cells were unstained. These findings indicate that normal mammary cells as well as a small population of cells within the R3230AC tumor are actively synthesizing casein or alpha-lactalbumin. Furthermore, the results suggest that immunocytochemistry may be used to determine the functional heterogeneity of mammary tumors directly.

Animals↗
PubMed1977

Effect of cyproterone acetate on prolactin secretion in the female Rhesus monkey.

Adult female rhesus monkeys were given cyproterone acetate orally in doses of 0.04, 0.4, 4 and 40 mg per kg per day for 12 weeks. Its effects were assessed on serum prolactin (PRL) concentration, the morphology of the PRL cells, and the development of the mammary glands. Serum PRL was relatively unchanged in the control animals from the fourth through the twelfth weeks of the study. In contrast, PRL was significantly elevated in each group of drug-treated animals during the same time periods. There was no development of the mammary glands nor was there any evidence of milk secretion in the control animals; however, in the monkeys given cyproterone acetate the mammary glands had extensive lobuloalveolar growth and milk-like secretion that could be expressed as early as the fourth or fifth week of the study. By immunocytochemistry and differential light microscopic staining techniques, the PRL cells in the pituitary glands of the experimental animals were found to be more numerous and much larger than those present in the controls. They displayed a well developed Golgi complex and had an abundance of cytoplasmic RNA. These data suggest that PRL secretion is markedly enhanced by cyproterone acetate.

Animals↗
PubMed1977

Morphological changes in prolactin cells of male rats after testosterone administration.

Intact and castrated 25- and 60-day-old male rats were given 200 mug of testosterone propionate (TP) daily for 15 consecutive days. The morphology of the prolactin (PRL) cells was examined by electron microscopy and analyzed by the point counting method of Weibel and Bolender (23). The PRL cells in the controls had long cytoplasmic processes that coursed between adjacent parenchymal cells. The Golgi complex was relatively small in these cells and the area occupied by the secretory granules was, in general, less than in the TP-treated animals. After TP administration, the cells became more ovoid and the Golgi complex enlarged, displaying dilated cisternae and many immature secretory granules. In addition, the diameter of the secretory granules was greater in the animals given the steroid. When the morphology of the PRL cells in the sexually immature control rats was compared to that observed in the older, sexually mature rats, relatively few differences were observed indicating that the response to TP was essentially the same in animals of both age groups. The concentration of PRL was measured in the serum and pituitary gland by radioimmunoassay. There was a significant elevation in PRL in both the serum and pituitary glands of all animals given TP. In contrast, castration led to a fall in PRL levels. From these observations and from the morphological data it can be concluded that TP is capable of stimulating the rate of PRL synthesis and release, and that testosterone may have a regulatory role in PRL biosynthesis and turnover in the male rat.

Aging↗