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Biomedical subjects

S Werner

Publications and source records attributed to S Werner.

At least 307 records · Page 17Linked to original sources
PubMed1979

In vitro preservation of human pituitary tumours in organotypic differentiation.

Three types of human pituitary adenomas--growth hormone producing, prolactin producing, as well as endocrinologically inactive ('chromophobe') tumours--were explanted to an in vitro system for organ culture. After one month, surviving hypophyseal cells demonstrated preserved hormone activity and no dedifferentiation of cell characteristics. During the first weeks in culture, close similarity existed between in vivo and in vitro conditions with regard to cell survival/cell morphology and physiological function/hormone release.

Adenoma↗
PubMed1978

Isolation of precursors of cytochrome oxidase from Neurospora crassa: application of subunit-specific antibodies and protein A from Staphylococcus aureus.

A novel immunological procedure has been applied for the isolation of precursors of cytochrome oxidase. It involves antibodies to individual subunits of the oxidase and protein A from Staphylococcus aureus linked to a Sepharose support. Unassembled (free) 'subunits' as well as a labile complex containing five polypeptide components of the oxidase were isolated from mitochondrial extracts by this technique. The procedure is superior to the previously used double-immuno-precipitation method, because of its quantitative nature, its sensitivity, rapidity and versatility. Thus, sequential titrations of precursor proteins by addition of various subunit-specific immuno-globulins to an individual extract become feasible. Furthermore, the technique is suitable for the isolation of precursors on a large scale. To avoid contamination of the polypeptide preparations with immunoglobulin, the antibodies were covalently coupled to protein A, which had been previously linked to Sepharose. A radioactive preparation of unassembled subunit 1 of cytochrome oxidase was isolated by such a modified support and its cyanogen-bromide-cleavage products were compared to those of subunit 1 obtained from the assembled enzyme.

Animals↗
PubMed1978

Regulation of growth hormone secretion during normal conditions and in patients with acromegaly.

A present considered concept of growth hormone secretion is that the hormone is tonically inhibited by the hypothalamic tetradecapeptide somatostatin. The episodic fashion of GH secretion with 6-8 GH peaks per 24 hours and its modulation by light and sleep are probably governed by factors other than somatostain, one possibly being melatonin. Evidence for a GH-releasing factor also exists, causing a basal release pattern of GH in moderate hourly peaks. The regulotary peptides in their turn, and possibly the GH producing cell itself, are influenced by dopaminergic or noradrenergic neurons. GH secretion is also modulated in a not yet elucidated relation to serotonin activity. Furthermore, GH induced somatomedin may constitute a negative feed-back on the pituitary and/or hypothalamic level. In acromegaly and gigantism, conditions characterized by chronic hypersecretion of GH, the GH producing cells are less differentiated as indicated by their response with GH release to unphysiological stimuli as well as their cessation of GH release to stimuli that normally act as releasors of GH.

Acromegaly↗
PubMed1978

Bromocriptine therapy in patients with acromegaly: effects on growth hormone, somatomedin A and prolactin.

Six of ten patients were subjectively improved by bromocriptine treatment as illustrated by diminished sweating, reduction of soft tissue swelling and restoration of sexual potency and menstruations. These six patients had elevated or normal blood levels of prolactin, which could be stimulated by TRH and inhibited by bromocriptine. During medication two clinical responders normalized and one lowered plasma GH concentrations. Three clinical responders with initially increase somatomedin A levels normalized these levels during treatment, in one case despite lack of effect on GH levels. The four nonresponders had undetectable or notably depressed levels of prolactin, which could not be stimulated by TRH. It is suggested that the presence of prolactin, per se or as an indication of a certain dopaminergic situation, is a prerequisite for successful bromocriptine treatment of patients with acromegaly.

Acromegaly↗
PubMed1977

Preparation of polypeptide subunits of cytochrome oxidase from Neurospora crassa.

Cytochrome oxidase was purified from Neurospora crassa by ammonium sulfate fractionation in the presence of bile salts. The enzyme preparations contained 10-13 nmol of heme a per mg of protein; no other hemoproteins could be detected. Dodecylsulfate gel electrophoresis resolved the enzyme complex into seven major bands, representing seven polypeptide subunits. A procedure is described that allows the isolation of these enzyme subunits on a large scale starting from a single batch of oxidase preparation. It involves dissociation of the enzyme complex by dodecylsulfate and subsequent separation of the obtained polypeptides by chromatography in the presence of various dodecylsulfate concentrations. Purification of subunits 3, 4, 5, 6 and 7 was achieved by column chromatography using molecular sieves (Sephadex G-100, Bio Gel P-60) and hydroxylapatite. For the purification of subunits 1 and 2 an electrophoretic separation on a preparative polyacrylamide gel was required. The advantages and disadvantages of the separation procedure of the enzyme polypeptides are discussed. As a special point of interest, the conservation of antigenic determinants of the polypeptide chains during the dodecylsulfate treatment is considered.

Electron Transport Complex IV↗
PubMed1977

Circulatory and lipolytic effects of parathyroid hormone. An experimental study in dogs.

Parathyroid hormone (PTH) was given intravenously to anesthesized adult dogs. Blood flows were measured with electromagnetic probes in different vascular areas concomitant with analysis of glycerol, free fatty acid, calcium, glucose, sodium, potassium, albumin, carbon-dioxid and creatinine. PTH consistently caused an immediate increment in blood flow in the celiac vasculature and a following, less pronounced increase in the renal artery. These changes were effectuated by a vasodilatation. The degree and duration of the flow increments were dose dependent; The celiac artery was more sensitive to the effect of PTH than the renal artery. In celiac artery maximal increase above basal flow was 58 +/- 27% (Mean +/- S.D.), in renal artery 25 +/- 12%. A significant lipolytic action of PTH was consistently notable within minutes after the administration of PTH. The other parameters analysed in blood remained unchanged sixty to ninety minutes after the PTH injections. Then a hypercalcemic effect of PTH appeared. A lipolytic action of PTH could be demonstrated with PTH doses which did not induce hypercalcemia.

Animals↗
PubMed1975

Regulation of mitochondrial membrane assembly in Neurospora crassa. Transient expression of a respiratory mutant phenotype.

Cultures of mutant cni-1, a chromosomal mutant of Neurospora crassa, undergo a marked change in respiratory properties as the age of the culture increases. Early log phase cultures have a high level of respiration that is insensitive to inhibition by cyanide or antimycin A. Late log and stationary phase cultures have reduced rates of respiration. A high percentage of this respiration is inhibited by cyanide. Mitochondria from early log phase cni-1 have an excess of cytochrome c and little or no detectable cytochrome aa3. Mitochondria from late log and stationary phase cultures have levels of c-, b-, and a-type cytochromes that are not significantly different in concentration from those found in wild type cells. The cytochrome aa3 content and the cytochrome oxidase activity of cni-1 mitochondria increase 5- to 10-fold as the age of the culture increases. Mitochondria from early log phase cells of cni-1 synthesize only polypeptides of apparent molecular weights 7,000 to 10,000 and donot synthesize any of the mitochondrial components of cytochrome oxidase. Mitochondria from late log and stationary phase cells synthesize the normal complement of mitochondrial translation products including the mitochondrial components of cytochrome oxidase. The assembly of cytochrome oxidase is likely due to the availability of the mitochondrially synthesized components of the enzyme. The regulation of mitochondrial translation in the cni-1 mutant is independent of the nutrient content of the growth medium and is due to the accumulation or depletion of some component within the cell.

Cell Division↗