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Biomedical subjects

G Rappay

Publications and source records attributed to G Rappay.

At least 55 records · Page 3Linked to original sources
PubMed1980

Rate of thymidine incorporation and incidence of parenchymal cell division in adult rat hypophyseal cell cultures. Effect of thyroliberin and somatostatin.

Cell suspensions derived from adult rat anterior pituitary glands were cultured for up to eight days. Prolactin immunoreactivity and/or tritiated thymidine incorporation into DNA of cell nuclei were demonstrated in cells with and without thyroliberin (TRH) and somatostatin (SRIF) treatment. It has been established that (a) TRH, which is effective in releasing both thyrotropin and prolactin, may stimulate cell proliferation in other than its target cells; that (b) SRIF has no effect on lactotropic cell proliferation and augments thymidine incorporation into DNA of unidentified cells; that (c) immunoreactive lactotropic cells with tritium-labelled nuclei are present in each culture, independent of hypothalamic hormone treatments.

Animals↗
PubMed1980

Rat intermediate lobe cell groups in suspension culture: morphological and functional characteristics.

Intermediate lobe cells mechanically isolated from adult rat hypophyses were maintained in histiotypic suspension culture. The cells survived as long as six weeks. The proliferation of the connective tissue cells was limited, they did not overgrow the glandular cells. The fine structure of the parenchymal cells in the epithelial spherules of the early cultures was practically identical to that in the intact tissue. The morphological sign of exocytosed secretory material could also be found. In older cultures, cells with light and dark cytoplasm were present. The former gradually degenerated and disappeared, while the latter, forming trabecules, retained their intact fine structure. Immunoactive and bioactive ACTH was detected in the culture medium.

Adrenocorticotropic Hormone↗
PubMed1979

ACTH radioimmunocytochemistry (RICH) on rat anterior pituitary cells.

Radioimmunocytochemistry (RICH) was applied to detect corticotrophs in adult rat pituitaries and 8-day-old anterior pituitary monolayers by incubating sections and cultures with 125I-ACTH-anti ACTH immune complexes. After incubations autoradiography was made. In comparison, "conventional" immunostaining was carried out on adjacent sections and parallel cultures. It has been established that RICH is suitable for detection of corticotrophs.

Adrenocorticotropic Hormone↗
PubMed1979

Major metabolic pathways and hormone production in unstimulated monolayer cultures of the rat anterior pituitary.

In cell cultures derived from anterior pituitary glands of rats, enzyme activities of cell homogenates and hormone (GH, PRL, LH, and FSH) content of the culture media were measured. Sex differences in enzyme activities representing major metabolic pathways (citrate cycles, pentose cycles, and glycolysis) were demonstrated both in freshly dispersed cells and in 8-day-old cultures; in cultures of both sexes enzyme activities increased during cultivation. In cultures derived from female rats, cell protein doubled by the 12th day and remained constant for up to the 24th day in culture, whereas enzyme activities showed changes suggesting that cell metabolism shifted to anaerobic glycolysis during cultivation. In the culture media the presence of four pituitary hormones was demonstrated for as long as 3 weeks of cultivation with variable secretion dynamics; the release of gonadotropic hormones diminished gradually whereas that of GH remained constant and PRL levels increased with time. These results indicate that under strictly defined culture conditions pituitary cells may function in spite of profound metabolic changes.

Acid Phosphatase↗
PubMed1979

Changes in corticotrophin releasing factor of the stalk median eminence in rats with various cuts around the medial basal hypothalamus.

The activity of corticotrophin releasing factor (CRF) in extracts of the stalk median eminence (SME) complex proper (average protein content, 30.6 micrograms) of male rats was assayed by monolayer cultures of anterior pituitary cells using the release of immunoreactive ACTH. Extracts which were equivalent to 0.025 SME of control rats usually had detectable CRF activity, while there was no detectable activity in extracts of 0.4 SME equiv. taken 8 days after complete surgical isolation of the medial basal hypothalamus (MBH). The activity of CRF in extracts from rats with an anterolateral cut around the MBH was at least ten times less than that in the control rats. One day after placing an anterolateral cut around the MBH the ACTH releasing activity of the SME was not significantly different from that of the control animals but activity decreased significantly 3 days after the operation and was at least ten times less than in the control animals on day 7 after the operation. It is suggested that most of the CRF activity of the SME is contained in nerve fibres entering the neurohaemal region from outside the MBH and that transection of these fibres produced the fall in CRF content of the SME in rats with partial or total surgical isolation of the MBH.

Animals↗
PubMed1978

Corticoliberin (CRF) activity of the rat neurohypophysis.

Corticoliberin (CRF) activity of the rat stalk-median eminence region (SME) and neural lobe of the pituitary (NL) was tested in vitro using cultured cells of anterior pituitary. The activity of NL was found to be more than 50% lower than that of SME. The parallelism of dose-response curves suggests that corticotropin releasing substances originating from NL and SME may be qualitatively identical. Thus, neurosecretory cells producing corticoliberin seem to form a continuous neurohemal system consisting of the median eminence, the stalk of the neural lobe.

Adrenocorticotropic Hormone↗
PubMed1978

Monolayer cultures of rat pituitary intermediate lobe: growth and fine structure of epithelial cells.

Rat hypophyseal intermediate lobe cells, partially dispersed by trypsin, were cultivated on an inert surface. The attaching capacity, the growth of the cultures and the fine structure of the epithelial cells developed during cultivation were studied. The majority of the cell groups attached to the inert surface within 72 h after explantation. Epithelial islands developed, with a layer consisting of fibroblast-like cells beginning to form at their periphery. By the end of the second week of cultivation the epithelial islets and fibroblast-like cells formed a monolayer. The epithelial cells survived for five weeks. The granular cytoplasm of the epithelial island cells could be well identified on the phase-contrast microcinematographic frames of the young cultures; both epithelial and fibroblast-like cells divided. The mitotic ability of both cell types could be confirmed by their tritiated-thymidine incorporation, too. In young cultures, the fine-structural features of epithelial cells were practically identical with those of the glandular cells in intact glands. In older cultures, the secretory granules in the epithelial cells were lower in number; the localization of the granules at the periphery was predominating.

Animals↗
PubMed1978

Identification of epithelial cells and fibroblasts in hypophysis intermediate lobe cultures by scanning electron microscopy.

Cell cultures of the rat pituitary intermediate lobe grown for eight days were studied in the scanning electron microscope. The epithelial cells and fibroblasts could be differentiated by the characteristic structures of the cell surface and the cell association features, The epithelial cells were characterized by blebs and rugae, microvilli, and occasionally by some cilia. The surface of the fibroblasts was smooth or bore microvilli. Scanning electron microscopy may provide special information for the characterization of endocrine cell cultures.

Animals↗
PubMed1977

DNA synthesis in immunreactive glandular cells in pituitary intermediate lobe cultures.

Cell suspensions were prepared from adult rat pituitary intermediate lobes and grown in medium TC 199 supplemented with foetal calf serum. 7 or 8 days old cultures were pulse labelled with tritiated thymidine and thereafter processed for immunostaining using an antiserum against a synthetic alpha-1-28-ACTH-analogue. Immunreactivity was mainly confined to epithelial cells, but some spindle-shaped cells were also immunopositive. Thymidine incorporation was observed in some immunpositive cells which shows that cells committed to hormone production may enter the mitotic cycle.

Animals↗
PubMed1976

Microspectrophotometry of mitochondrial cytochrome P-450 in single adrenal cells.

The cytochrome P-450 is known to be a key enzymic component in steroid hydroxylation. Biochemically it is localized in adrenal cells, both in the mitochondrial and in the microsomal fractions. Owing to its characteristic light absorptivity, attempts were made at its localization and measurement in a microspectrophotometric system. Specific difference spectra were obtained in the cytoplasm of some cells from an adrenal cell suspension before and after saturation with carbon monoxide. Scanning at 450 nm showed slender absorption maxima after CO saturation randomyl distributed in the cytoplasm. These may be attributed to mitochondria or larger cytoplasmic functional units including mitochondria.

Adrenal Glands↗
PubMed1975

Autoradiographic localization of 3H-gamma-aminobutyric acid in the medial hypothalamus.

Tritium labelled gamma-aminobutyric acid (3H-GABA) was infused into the third ventricle of rats with normal or deafferented hypothalamus and the distribution of the label was studied by light and electron microscopic autoradiography. In control as well as deafferented hypothalamus a few neurones accumulated radioactivity, while the majority was unlabelled. Characteristic clusters and rows of silver grains were observed in the neuropil of several regions probably indicating labelled cell processes and terminal axons. Electron microscopy showed that at least some of the clusters were over axon terminals with synaptic vesicles. 3H-GABA accumulated also in the ependyma and glial elements. The results suggest that in the medial hypothalamus there is a preferential uptake of GABA in some neurones and nerve fibers; at least some of these are hypothalamic interneurones. This supports the hypothesis that some hypothalamic neurones and nerve endings may use GABA as a transmitter.

Alanine↗