PubMed Health⌕ Search

Biomedical subjects

H Repke

Publications and source records attributed to H Repke.

32 records · Page 2Linked to original sources
PubMed1987

Prevention of stress-induced involution of the thymus in rats by substance P (SP1-11) and its N-terminal fragment SP1-4.

Selye found that in response to different stressors the body reacts with a characteristic stress syndrome: adrenal enlargement, gastrointestinal ulcera, and thymicolymphatic involution. In this paper we demonstrate that i.p. injected Substance P (SP) can prevent stress-induced involution of thymus in Wistar rats. This protecting effect on the immune system of SP, in addition to the "normalizing" effects of this peptide on stress-induced disorders in vegetative and central functions first described by Oehme and co-workers and Hecht and co-workers is a new hint to the function of SP as an "anti-stress" agent. The mode of action of the anti-stress effect of SP in adrenals as well as in the thymus is discussed. It is suggested that the anti-stress effect of SP1-11 and its N-terminal fragment SP1-4 is mediated by specific receptors in adrenals and/or thymus which are different from the so called SP-P and SP-E receptors.

Adrenal Glands↗
PubMed1987

Histamine release induced by Arg-Pro-Lys-Pro(CH2)11CH3 from rat peritoneal mast cells.

The substance Arg-Pro-Lys-Pro-(CH2)11CH3 [SP1-4C12] was synthesized by forming a peptide bond between Arg-Pro-Lys-Pro, the N-terminal sequence of substance P and dodecylamine. The aim was to examine the roles of the N- and C-terminal sequences of substance P in stimulating histamine release from mast cells of the rat peritoneal cavity. SP1-4 C12 induces concentration-dependent histamine release in the range 8 to 200 nM. SP1-4C12 was 50 times more potent than substance P and 300 times more potent than dodecylamine. Unlike dodecylamine itself, SP1-4C12 induced noncytolytic histamine release which was inhibited by benzalkonium chloride and by the substance P antagonist [D-Pro4,D-Trp7,9,10]SP4-11. Histamine release induced by SP1-4C12 was inhibited at temperatures below 16 degrees C and did not require the presence of extracellular calcium ions. It is suggested that substance P and some other basic histamine liberators initiate histamine secretion by a mechanism that involves the insertion of a hydrophobic region into the membrane lipid which is necessary to present positively charged moieties to a receptor site involved in activating the secretory mechanism.

Animals↗
PubMed1986

[Histamine receptor-bearing lymphocytes. VII. Antibody formation and graft-vs-host reaction from spleen cells after separation on histamine affinity columns].

Histamine-ovalbumin conjugates were characterized in respect to the relative amount of histamine residues which are accessible to membrane receptors. These conjugates were bound to a protein carrier. Spleen cells exhibited an enhanced reactivity in the adoptive antibody production as well as the graft versus host reaction after filtration through affinity columns with a low density of histamine residues. Contrary to that, the use of affinity columns with high histamine density led to a reduced immunoreactivity of the nonadherent cells. Consequently, controversial literature data concerning this problem seem to be based on methodological differences. The results support the hypothesis, that suppressor cells carry more histamine receptors than other immunoreactive cells.

Animals↗
PubMed1986

Histamine as endogenous immunomodulator.

Histamine induces the T-cell dependent production of both suppressive and enhancing factor via its interaction with H2-receptors. This could be shown by the transfer of cells or crude lymphokine preparations after in vitro histamine treatment into recipient mice, which were characterized with respect to their humoral immune response. The effective histamine concentrations differed remarkably among different mouse strains which indicates a complex regulatory network. The combined in vitro/in vivo approach as performed in these experiments leads to the conclusion that histamine may act as a suppressive as well as an enhancing immunomodulator on the humoral immune response in vivo.

Animals↗
PubMed1986

Monoclonal antibodies against rat mast cells.

Four hybridomas have been isolated which secrete monoclonal antibodies against surface determinants of rat peritoneal mast cells. This could be demonstrated by an indirect immunofluorescence assay. The monoclonal antibodies did also react with a portion of mononuclear phagocytes from the peritoneal cavity but not with other lymphatic cells.

Animals↗
PubMed1984

[Studies in experimental animal models of the effect of ultraviolet radiation (UVC) on blood and isolated cell populations].

The cellular and molecular basis of the therapeutically used effect of reinjected ultraviolet ( UVC ) irradiated blood is unknown. First approaches to that problem were made in this study by aid of model experiments. Neither the spontaneous degranulation nor the antigen-induced histamine release from rat connective tissue mast cells (in vivo) was influenced by the injection (i.v.) of ultraviolet irradiated blood or blood lymphocytes. By comparison of the effect of ultraviolet light on blood lymphocytes (number of dead cells, strength of chemoluminescence) after irradiation of the isolated cells and the unfractionated blood respectively, we could show that the strong light absorption within the blood sample prevents damage or functional alterations of the blood lymphocytes. The compound 48/80-induced histamine release from rat peritoneal mast cells can be completely inhibited by ultraviolet irradiation (0.6 mJ/cm2) without increasing the spontaneous histamine release.

Animals↗
PubMed1982

Muscarinic acetylcholine receptors on culture glia cells.

Muscarinic acetylcholine receptors (76 fmol/mg protein) were detected on cultured glia cells (astroblasts) from embryonic chicken brain by specific [3H]quinuclidinylbenzilate (QNB) binding at physiological conditions. The QNB binding (Kd = 9.5 x 10(-11)) to the intact cells seems to be cooperative (nH = 1.98) as shown by graphical methods.

Animals↗
PubMed1980

Incorporation of brain membrane proteins into planar bilayer lipid membranes.

Am method is presented which enables the incorporation of solubilized brain membrane proteins into bilayer lipid membranes (BLM) from brain lipids. The digitonin solubilized proteins are first incorporated into liposomes which undergo fusion with the BLM in a second step. The incorporation results in a large increase in membrane conductivity which maintains at a stable level for hours. Identical electrical phenomena were observed after incorporation of the membrane fragments which were used as starting material of protein extraction. The method can be used to reconstitute membrane proteins to the their natural lipid environment in a planar BLM. Our results argue against the essential role of Ca2+ and osmotic gradients during fusion of bilayer structures.

Animals↗
PubMed1978

Detection of a cell surface antigen common to a mouse myeloma and a population of mouse thymocytes.

A new antigen termed PTA (plasmocytoma thymus antigen) is described which occurs on 70--80% of mouse thymocytes of all mouse strains tested and on an IgG 2b producing BALB/c plasma cell tumor. PTA is detectable on mouse spleen and lymph node cells. It is absent from liver, brain, bone marrow, and antibody plaque forming cells. PTA is not related to theta antigen and is not detectable on rat thymocytes.

Animals↗
PubMed1978

A common differentiation antigen on plaque forming cells and a subpopulation of thymus cells in mice and rats.

A non species specific lymphocyte differentiation antigen is described which can be detected on plaque forming cells and a small fraction of thymocytes of mice and rats. The antigen is absent from a BALB/c plasma cell tumor and is not detectable on Dexamethasone-resistant thymocytes. On the basis of its occurrence the term TPCA (thymus plasma cell antigen) is proposed for the antigen. A monospecific anti TPCA serum could be prepared which enables the detection of the antigen on about 10% of rat thymocytes.

Animals↗
PubMedDate not supplied

Substance P and Arg-Pro-Lys-Pro-NH-C12-H25-induced mediator release from different mast cell subtypes of rat and guinea-pig.

Histamine was released from mast cells in isolated perfused heart and kidney of the rat, but not from mast cells in guinea-pig tissues, by a substance P (SP) analogue (SP(1-4)-NH-C12H25), SP(1-4)-C12 for abbreviation. This peptide also released histamine from peritoneal mast cells and basophil leucocytes of the rat. Substance P itself was compared with SP(1-4)-C12 and some structurally related peptides and showed weaker activity. SP(1-4)-C12 also released leukotrienes C4, D4, E4 and thromboxane B2 from rat heart. However, there was little effect on heart rate and force of contraction and no effect on perfusion pressure (vascular resistance) of either rat heart or kidney. The findings demonstrate the structural requirements for histamine release by SP (a possible mediator of 'neurogenic' inflammation), the metabolic energy-dependence of the release process and the functional heterogeneity and interspecies differences in mast cell populations.

Animals↗
PubMedDate not supplied

Biochemical characterization of solubilized muscarinic acetylcholine receptors.

Several in part new methods (salt extraction, phospholipase treatment, transfer to serumlipoproteins, nonionic detergent mixtures) have been extensively examined in order to obtain a solubilized muscarinic acetylcholine receptor with properties suitable for further purification. An optimal mixture of digitonin and gitonin has been found which forms a tightly bound detergent wall around the receptor protein as indicated by ion exchange and monolayer studies and which allows to solubilize the receptor from enriched synaptosomal membranes with a high yield and stability. The specific 3H-QNB binding of this preparation is nearly unchanged between pH 7.5 and 10. The isoelectric point of the muscarinic acetylcholine receptor has been determined by isoelectric focusing to be between pH 4.5 and 4.6.

Acetylcholine↗