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Biomedical subjects

L Schweigerer

Publications and source records attributed to L Schweigerer.

62 records · Page 4Linked to original sources
PubMed1985

beta-Endorphin: surface binding and internalization in thymoma cells.

The opioid peptide beta-endorphin binds to specific nonopioid binding sites (Mr 72,000) that are present on the surface of thymoma cells. beta-Endorphin is then internalized, apparently via the Mr 72,000 species, and is subsequently found within intracellular, vesicular structures. This process is accompanied by the down-regulation of the Mr 72,000 binding sites. Our findings suggest that beta-endorphin may modulate cellular functions, such as T-lymphocyte proliferation, at intracellular rather than cell surface sites.

Animals↗
PubMed1983

Interaction of human beta-endorphin with nonopiate binding sites on the terminal SC5b-9 complex of human complement. Significance of COOH-terminal beta H-endorphin fragments.

We have characterized the binding of 125I-labeled human beta-endorphin (125I-beta H-endorphin) to sites present on the terminal fluid-phase complex of human complement, consisting of complement components C5b, C6, C7, C8, C9, and the S-protein (SC5b-9 complex). Specific binding exhibited saturability, reversibility, structural specificity, temperature dependence, and absence of negative cooperative effects. Binding was maximal at 4 degrees C and pH 7.0; it was diminished by monovalent and divalent cations as well as by increasing concentrations of urea and Triton X-100 and apparently required intact disulfide groups. Binding was not inhibited by a number of opioid peptides sharing common sequences with the NH2 terminus of beta H-endorphin. In contrast, binding was inhibited by beta H-endorphin, N-acetyl-beta H-endorphin, and a series of COOH-terminal beta H-endorphin fragments, where of the COOH-terminal dipeptide Gly-Glu represented the minimal effective structure. Stepwise extension towards the NH2 terminus led to an increased binding affinity of the respective fragment. Computer resolution of competition curves yielded one binding component for several shorter COOH-terminal beta H-endorphin fragments and for beta H-endorphin (1-5) + (16-31), whereas two distinct binding components were obtained when beta H-endorphin (27-31), beta H-endorphin (6-31), N-acetyl-beta H-endorphin or beta H-endorphin were used as inhibitors. This study presents detailed data on the binding of COOH-terminal beta H-endorphin fragments to specific nonopiate binding sites present on the terminal SC5b-9 complex of human complement. We suggest that through this interaction, beta H-endorphin may modulate certain functions within the immune system.

Binding Sites↗
PubMed1983

Endotoxin-induced formation of specific beta-endorphin binding sites in human serum.

Specific binding of human beta-endorphin is demonstrated to sites that are present in endotoxin-treated, but not in native, human serum. Binding is saturable and reversible and is mediated by a nonopioid segment of beta H-endorphin to sites that are located on the terminal SC5b-9 complement complex. Since endotoxemia causes both the secretion of beta-endorphin into blood (1) and the formation of specific beta-endorphin binding sites therein, both effects might be elements of a common physiological process.

Chemical Phenomena↗
PubMedDate not supplied

Interaction of human beta-endorphin with the terminal SC5b-9 and "preterminal" SC5b-7 and SC5b-8 complexes of human complement.

Human beta-endorphin (beta H-EP) is demonstrated to bind to the "preterminal" SC5b-7 and SC5b-8 complexes and to the terminal SC5b-9 complex of human complement. Detailed binding studies revealed saturability, reversibility and structural specificity of the beta H-EP interaction with high or low affinity non-opiate binding sites on SC5b-7 and SC5b-9 complexes. The high affinity binding sites seem to be located predominantly on C5b, C6 or C7 subunits of the complexes.

Alpha-Globulins↗
PubMedDate not supplied

Capillary endothelial cells express basic fibroblast growth factor, a mitogen that promotes their own growth.

Angiogenesis, the formation of new capillaries, which is observed in embryonic and injured tissue and is particularly prominent in the vicinity of solid tumours, involves the migration and proliferation of capillary endothelial cells. It is probably triggered by agents, such as basic fibroblast growth factor (bFGF), thought to be released from tissues adjacent to proliferating capillaries. As well as being a potent inducer of cell division in capillary endothelial cells in vitro, bFGF can act as an angiogenic agent in vivo. It is present in a wide variety of richly vascularized tissues including brain, pituitary, retina, adrenal gland, kidney, corpus luteum, placenta and various tumours. So far, however, the normal bFGF-producing cell species in these tissues have not been identified. We report here that capillary endothelial cells express the bFGF gene, that they produce and release bFGF and that bFGF derived from them can stimulate the proliferation of capillary endothelial cells. We conclude that bFGF can act as a self-stimulating growth factor for capillary endothelial cells, and that it is possible that the formation of new capillaries is induced by capillary endothelial cells themselves.

Animals↗
PubMedDate not supplied

[Increased expression of the MYCN oncogene in human neuroblastoma cells and possible, new therapeutic approaches].

Human neuroblastomas of advanced stages often display amplification with a consecutive enhanced expression of the MYCN oncogene. Enhanced MYCN expression is thought to contribute in a causative manner to the progression of neuroblastomas, but the mechanisms by which this may occur have remained unclear. By transfecting human neuroblastoma cells that display a normal MYCN expression with the human MYCN oncogene, we have generated a cell line with enhanced MYCN expression and thereby were able to compare the biological and biochemical properties of the transfected and non-transfected cells. We have demonstrated autocrine growth factors in the MYCN-transfected, but not the non-transfected, neuroblastoma cells. Identification of the primary structures of these factors may help to develop specific antagonists in order to improve the therapy of advanced neuroblastomas. Currently, this could be done by application of genistein or tumor necrosis factor. As we could demonstrate for the first time, the dietary constituent genistein is able to inhibit the proliferation of neuroblastoma cells with enhanced and normal MYCN expression, but also that of cells derived from other solid pediatric tumors. In contrast, tumor necrosis factor is able to inhibit selectively the proliferation of neuroblastoma cells with enhanced MYCN expression. We suggest that tumor necrosis factor might improve the therapy of advanced human neuroblastomas.

Animals↗
PubMedDate not supplied

Clinical perspectives of tumor angiogenesis in pediatric oncology.

Angiogenesis, the formation of new capillaries from existing blood vessels, is necessary for embryonic growth and development. It is also seen later during the female cycle and wound healing, but is virtually absent otherwise in the healthy adult organism. Angiogenesis is again observed under pathological conditions, like for example in solid pediatric malignancies. Once grown to a diameter of several millimeters, the latter depend on angiogenesis in order to further grow and to metastasize. Recent experimental and clinical evidence suggests 1) that the extent of tumor angiogenesis could serve to predict clinical outcome and 2) that the inhibition of angiogenesis could be a means to improve the conventional therapy of solid pediatric malignancies.

Adult↗