PubMed Health⌕ Search

Biomedical subjects

A M Sirek

Publications and source records attributed to A M Sirek.

7 recordsLinked to original sources
PubMed1977

Failure of ergotamine to alter the lipolytic effect of somatotropin in dogs.

Hypophysectomized dogs were injected intravenously with bovine somatotropin (GH), and plasma free fatty acid (FFA) concentrations were measured over a period of 2 h. The response consisted of an initial reduction in the concentration of plasma FFA followed by a rebound and a delayed rise above baseline values. When the animals were given a single intravenous injection of ergotamine tartrate 30 min prior to the administration of GH, the biphasic pattern with the sluggish rise in plasma FFA was retained. This finding is contrary to the results of identical experiments conducted by us with dihydroergotamine, which proved to be a potent amplifier of the lipolytic effect of GH. Since the only difference between these two compounds is the presence or absence of the double bond at C9 and C10 of the lysergic acid moiety, it appears that unless this bond is saturated the alkaloid is not capable of functioning as a biological amplifier.

Animals↗
PubMed1976

A new look at pituitary adenomas: structure elucidating function.

Cases of seven different types of surgically resected pituitary adenoma are described. Included are tumours secreting prolactin or growth hormone or both, and nonfunctioning tumours--undifferentiated and oncocytic tumours, and one tumour with cells of the adrenocorticotropin-melanocyte-stimulating hormone type. The final interpretation of a case of pituitary adenoma should include an assessment of thorough morphologic studies, using not only routine staining and light microscopy but also immunostaining and electron microscopy, to complement the biochemical, radiologic and clinical evaluation.

Acromegaly↗
PubMed1976

Localization of prolactin in chromophobe pituitary adenomas: study of human necropsy material by immunoperoxidase technique.

In order to identify prolactin-producing tumours in human pituitary glands, 45 chromophobe adenomas, obtained from unselected necropsies, have been studied by various staining procedures including the immunoperoxidase technique for the demonstration of prolactin. The presence of immunoreactive prolactin was revealed in the cytoplasm of the tumour cells in six cases (13%), indicating that the occurrence of prolactin-producing adenomas is not rare. No correlations were established between tumours and clinical history. Two adenomas were detected in female and four in male patients. The age of the patients at necropsy ranged from 28 to 75 years. Three adenomas were associated with disseminated carcinoma, two with fatal liver disease, and one with diabetes mellitus, atherosclerosis, and pyelonephritis. Manifest endocrine symptoms were not disclosed, and endocrine investigations, including measurements of blood prolactin levels, were not undertaken. Thus, direct evidence is lacking as to whether or not these tumours were actively secreting prolactin. In the non-tumorous parts of the anterior lobes the number of prolactin cells was decreased in two cases, suggesting that prolactin released from the adenoma cells suppressed prolactin production in the non-tumorous pituitary. However, the number of prolactin cells of the non-tumorous adenohypophysis seemed to be unchanged in two and increased in another two cases. The present findings conclusively proved the existence of the prolactin-producing adenomas as a distinct entity. These tumours do not stain with acid or basic dyes, they are PAS or thionin negative, and do not contain immunoreactive growth hormone. Thus, by conventional staining procedures they are indistinguishable from other chromophobe adenoma types. Herlant's erythrosin and Brookes' carmoisine methods, claimed spedifically to stain prolactin cells, failed to provide reliable results, hence their use cannot be recommended in tumour identification. Immunoperoxidase staining of prolactin is the only technique which conclusively reveals the presence of immunoreactive prolactin in the cytoplasm of the tumour cells and permits diagnosis. It is proposed that this technique be introduced in pituitary morphological studies. Its application may lead to a better understanding of problems related to prolactin-producing tumours and their secretory activity.

Adenoma, Chromophobe↗
PubMed1976

Effect of starvation on pituitary growth hormone cells and blood growth hormone and prolactin levels in the rat.

Growth hormone (GH) cells of rats were studied on days, 2, 4 and 7 of starvation. Immunoperoxidase staining for light microscopy confirmed the presence of GH in the pituitaries of all groups of animals. Electron microscopy revealed crinophagy in the cytoplasm of GH cells on days 4 and 7. By ultrastructural morphometry, volume density and the diameter of secretory granules in the cytoplasm of GH cells remained unchanged. Blood GH determinations showed a significant decrease on day 4 of the starvation period. On day 7 most of the values were in the range of the controls. Blood prolactin levels fell significantly on day 7. It appears that the pituitary is capable of secreting GH even in rats completely deprived of exogenous nutrients.

Animals↗
PubMed1976

Human mixed somatotrophic and lactotrophic pituitary adenomas.

Six patients with acromegaly at examination were found to have pituitary adenomas composed of cells that secreted GH and PRL. This was demonstrated by the elevated serum hormone concentrations, by immunoperoxidase staining of 5 specimens, and by electron microscopic examination of 4. Ultrastructural characteristics, described in detail, suggest that these adenomas were mixed adenomas consisting of 2 well-defined, distinct cell types, each secreting one hormone. By immunoperoxidase staining some cells were found to contain immunoreactive growth hormone, other cells immunoreactive prolactin. No cells were detected exhibiting immunostaining for both growth hormone and prolactin. Eelctron microscopy, consistent with the results of immunostaining, revealed the presence of two distinct cell types, distinguishable from each other by their characteristic fine structural features. No intermediate forms were noted. Thus there was no evidence to suggest that one cell type might transform to the other. Present findings seem to indicate that mixed adenomas secreting growth hormone as well as prolactin and consisting of somatotrophs as well as lactotrophs do occur in the human pituitary gland. Although all the results obtained so far suggest that these tumors are composed of two distinct cell types and thus can be interpreted as representing real mixed adenomas, further work is required to establish whether or not they derive from one common progenitor.

Acromegaly↗
PubMed1975

Pituitary chromophobe adenomas consisting of prolactin cells: a histologic, immunocytological and electron microscopic study.

Morphologic studies of pituitary neoplasms removed by srugery from 36 human patients revealed 8 chromophobe adenomas which differed clearly from the remaining tumors. The cytoplasm of the adenoma cells failed to stain with PAS, aniline blue, adehyde fuchsin, aldehyde thionin, orange G or light green, but positively stained granules were found by using erythrosine or carmosine. Immunoperoxidase technique disclosed the presence of prolactin in the cytoplasm of some adenoma cells. The adenoma cells exhibited distinct ultrastructural features such as well developed rough surfaced endoplasmic reticulum with Nebenkern formation, prominence of Golgi apparatus, presence of misplaced exocytosis as well as pleomorphism of secretory granules with a considerable variation of size ranging from 130 to 500 nm in diameter. Thus, by electron nicroscopy the adenoma cells showed a close resemblance to prolactin cells of the non-tumouous pituitary glands except for the reduced size and number of secretory granules. Thes chromophobe adenomas are regarded as representing a distinct pathological entity clearly distinguishable from other forms of pituitary neoplasms. In view of the morphologic findings and the elevation of blood prolactin level (measured in 3 patients) the term, "sparsely granulated prolactin producing pituitary adenoma", appears to be the most appropriate one to designate these tumors.

Adenoma, Chromophobe↗