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Biomedical subjects

W Schulze

Publications and source records attributed to W Schulze.

At least 19 recordsLinked to original sources
PubMed1995

Human seminal fluid contains significant quantities of prorenin: its correlation with the sperm density.

The relevance of the tissue prorenin-renin-angiotensin system (PRAS) to male reproduction has been suggested by several investigators in the past. Although the presence of angiotensin converting enzyme in semen has been demonstrated, unequivocal evidence for the presence of prorenin and renin in the semen is not yet available. We have used a specific immunoradiometric assay based on an antibody directed against the pro-segment of the prorenin molecule to demonstrate that significant quantities of prorenin are present in human semen samples. Although semen is a rich source of proteases and protease inhibitors, the assay used by us, unlike the usual enzymatic renin assay, is not affected by such proteases, and their inhibitors. Furthermore, Western blotting data clearly demonstrated that prorenin is present in semen as a 48 kDa protein. In a majority of semen samples, the prorenin content was found to be several fold greater than that measured in EDTA-plasma samples. Interestingly, the level of prorenin was found to be directly proportional to the sperm density in semen samples. Our results suggest that seminal prorenin is produced locally within the male reproductive system, although its exact origin is yet to be defined, that a complete prorenin-renin-angiotensin system exists in human semen and that this system may be relevant to sperm function.

Adult↗
PubMed1995

Functional epitope analysis of the second extracellular loop of the human heart muscarinic acetylcholine receptor.

Two synthetic peptides corresponding to amino acids 172-181 and 169-193 of the second extracellular loop of the human M2 muscarinic receptor respectively were used to raise antibodies in rabbits. Affinity-purified antibodies were able not only to recognize a major band with a molecular weight of about 80 kDa on the electrotransferred membrane proteins of rat ventricular membranes but also to localize the muscarinic receptors on the sarcolemma and t-tubules of rat cardiomyocytes. Antibodies were also able to mimic muscarinic agonist stimulation as demonstrated by a negative chronotropic effect on cultured neonatal cardiomyocytes. In contrast with the antibodies raised against the peptide 169-193, the antibodies against the peptide 172-181 were unable to inhibit muscarinic ligand binding. These results suggest that the decapeptide 172-181 contains the B-cell epitope responsible for the functional effect of antibodies directed against the second extracellular loop of the receptor. Coupling this peptide by cystein 177 blocks the induction of antibodies with pharmacological effects but induces antibodies which are able to recognize the denatured receptor protein and to exert a negative chronotropic effect.

Amino Acid Sequence↗
PubMed1995

[Triplet pregnancy after intracytoplasmic sperm injections].

Morphology of the spermatozoa is one of the major criteria in severe male subfertility. We report on a case of severe Oligoasthenoteratozoospermia in which a triplet pregnancy could be achieved after intracytoplasmic sperm injection (ICSI). After treatment with GnRH-analogues/HMG/HCG seven oocytes of metaphase II could be retrieved and injected. Three of them fertilised and were transferred as four-cell stage embryos after two days. Seven weeks later an intact triplet pregnancy could be detected by ultrasonography. The severe sperm defects in this case were evaluated with the technique of electron microscopy. Ultramorphology of spermatozoa appears to have an important predictive value for fertilisation and pregnancy in classical IVF. Its value for the assisted procreation techniques such as ICSI remains to be investigated.

Adult↗
PubMed1995

[Immobilization damage].

Prolonged immobilization can threaten the surgical result. The reduction of the muscle diameter is reported to be between 10 and 60% after four weeks of immobilization depending on the different muscle groups. Particularly the oxidative type-1 fibers, the "slow twitch fibers" are concerned. However, the sequelae of immobilization of muscle are reversible, which is in contrast to the detrimental effects immobilization has on the bone. Inactivity osteoporosis is occurring in three stages with bone loss as much as five to twenty times that of other calcipenic disorders. The physiological coupling of bone resorption and bone remodeling is lost. Immobilization leads to arthrosis changing the cartilage matrix composition quantitatively and qualitatively as well as cartilage morphology histologically and electron-microscopically. The result of immobilization is shortening of all fibrous tissues. The loss of the ligament-specific orientation of fibrils leads to significant reduction in tensile strength. The sequelae of immobilization emphasize the importance of early functional therapy. Continuous passive motion speeds up wound healing, and the tissue-structure is improved.

Animals↗
PubMed1995

Dietary medium-chain triglycerides can prevent changes in myosin and SR due to CPT-1 inhibition by etomoxir.

To define determinants of subcellular structures of heart, Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were treated for 5 wk with 15 mg.kg-1.day-1 etomoxir [reduces mitochondrial carnitine palmitoyltransferase-1 (CPT-1) activity and fatty acid synthesis]. To bypass CPT-1 inhibition, etomoxir-treated rats were fed a medium-chain fatty acid (MCFA) diet. Etomoxir induced a proportionate growth of heart, which could partially (WKY, P < 0.05) or completely (SHR, P < 0.05) be prevented by the MCFA diet. Also the etomoxir-induced increase in myosin V1 was partially prevented (P < 0.05). Etomoxir increased (P < 0.05) rate of sarcoplasmic reticulum (SR) Ca2+ uptake of WKY and SHR ventricular homogenates in the presence or absence of the SR Ca2+ release inhibitor ruthenium red. The MCFA diet resulted in SR Ca2+ uptake rates that were in between those of etomoxir-treated and untreated rats. The in vitro 32P incorporation into phospholamban and troponin I did not differ significantly in WKY. Etomoxir induced, however, an increase (P < 0.05) in the phosphorylated intermediate of the Ca2+ adenosinetriphosphatase in WKY that was prevented by the MCFA diet. In SHR, etomoxir increased the in vitro phospholamban phosphorylation, which was reduced compared with WKY. The data show that myosin and SR are affected by a chronically altered substrate utilization of heart.

Animals↗
PubMed1992

Fluorenone-azomethines, a novel class of microtubule inhibitors that specifically affect cell proliferation.

The effects of various azomethine derivatives on microtubule (MT) assembly in vitro as well as on cell proliferation, cell shape, and the cytoskeleton of some cultured murine cell lines were studied. 3 of them, the alpha-diphenylene-N-(p-[bis-(beta-hydroxyethyl)-amino]-phenyl)-nit rone (DHPN), alpha-diphenylene-N-(p-[N-(hydroxyethyl)-N-(gamma-hydroxypropyl)- amino]-phenyl)-nitrone, and alpha-diphenylene-N-(p-diethylaminophenyl)-nitrone, strongly inhibit the assembly of microtubules (MTs) in vitro (50% inhibition at 4 to 7 mumol/l). The same compounds are also able to disrupt preformed microtubules. Moreover, they were found to inhibit proliferation of leukaemia L 1210, melanoma B16 K, fibroblast L 929, and embryo fibroblast cells down to 1 to 10 mumol/l, completely. Immunofluorescence microscopy revealed that DHPN, used as a representative of the active azomethines, causes a reversible destruction of the microtubule part of the cytoskeleton. Apparently resulting from microtubule disruption, the intermediate filament system collapsed whereas the microfilament system remained unaffected. The results indicate that the antiproliferative action of the azomethines is based, at least partially, on their ability to attack microtubules.

Animals↗
PubMed1992

Limited selectivity of a synthetic erbstatin derivative for tyrosine kinase and cell growth inhibition.

The natural tyrosine kinase inhibitor erbstatin and a synthetic analog (1302) were co0pared for their inhibitory activity on EGF receptor kinase, PDGF receptor kinase and a src-type kinase from bovine brain. Erbstatin inhibited both growth factor receptor kinases equally well and had little effect on the src kinase. The analog exhibited similar potency for inhibition of purified EGF receptor tyrosine kinase as erbstatin, however, was clearly less effective for inhibition of purified PDGF receptor kinase as well as the src-type kinase. The selectivity was, however, not seen when the derivative was assayed with respect to inhibition of autophosphorylation of both growth factor receptors in Swiss 3T3 cell membranes. The latter finding might explain a lack of selectivity of the compound for inhibition of DNA synthesis in 3T3 cells when the cells were stimulated comparatively with EGF, insulin, EGF plus insulin or PDGF. The results suggest that the environment of growth factor receptors in the cell membrane can remarkably modify their susceptibility to tyrosine kinase inhibitors.

3T3 Cells↗
PubMed1992

[Vasovasostomy after vasectomy. The surgical results 1986-1989].

The frequency of vasovasostomy has increased dramatically in recent years. A significant percentage of men who have previously undergone vasectomy are now seeking restoration of their fertility. The most common reason for requesting a reversal is remarriage. There were 90 bilateral vasovasostomies performed in 90 patients between 1986 and 1989. The procedure was done according to the technique described by Howards, in a single layer with 7 x 0 prolene and under fourfold magnification. The success rate was 87% for presence of spermatozoa in the ejaculate, 48% for pregnancy. The fertility rate decreases slowly with increasing interval between vasectomy and reanastomosis. These results are statistically significant. In cases of good anatomical and andrological conditions, the chance of restoration of fertility is good. The experience of the urologist is often more important than the details of the technique.

Adult↗
PubMed1991

Synergistic cytotoxicity of human recombinant tumour necrosis factor alpha combined with microtubule effectors.

Combinations of human recombinant tumour necrosis factor alpha (rhTNF alpha) with each of four different agents disturbing the microtubule system of the cellular cytoskeleton were tested for synergistic cytotoxic action against murine melanoma B16K and L-M(S) cells. In addition to the known microtubule effectors colchicine, vincristine, and taxol, the influence of the fluorenone-azo-methine derivative alpha-diphenylene-N-(p-[bis-(beta-hydroxyethyl-amino]-phenyl)- nitrone (DHPN) on the rhTNF alpha cytotoxicity was studied. Applying a novel computer-based isobole method [Suehnel J (1990) Antiviral Res 13:23-40] concentration ranges of synergistic, zero, and antagonistic interaction were found after in vitro combination of rhTNF alpha with each of the drugs tested in a 72-h cytotoxicity assay. In contrast, a 24-h exposure of B16K cells to these combinations still did not inhibit in vitro colony formation to a greater extent than either drug alone. A preliminary in vivo experiment revealed an increased antitumour effect after treatment of established subcutaneous melanoma B16 tumours with a combination of rhTNF alpha and DHPN.

Animals↗
PubMed1991

Immunocytochemical localization of G-proteins (alpha subunits) in rat heart tissue.

The subcellular localization of peptide antibodies against G-protein alpha subunits was studied by the indirect immunogold technique with Lowicryl K4M embedded rat cardiac tissue. Two antibodies were used. The alpha common peptide antibody recognizes the alpha subunits of Gs, Gi and Go. The alpha i common peptide antibodies recognize the alpha subunits of all Gi alpha subtypes (G1-3). Immunoreactivity against alpha common and alpha i common antibodies was found along the cell surface of cardiomyocytes and endothelial cells. No immunoreactivity was seen on sarcoplasmic reticulum membranes. T-tubule membranes showed a little reactivity. Distribution patterns obtained with alpha common and alpha i common antibodies were identical. Immunogold was seen in cardiocytes from both atria and ventricles. In light-microscopical studies with peroxidase-conjugated secondary antibodies, heavy immunostaining was seen in SA and AV nodes.

Adenylyl Cyclases↗
PubMed1991

G protein function in the ischaemic myocardium.

The activity of adenylyl cyclase (AC) is controlled by its interaction with receptor-regulated G proteins. The efficiency to form cyclic AMP is strongly influenced by the amount, the subspecies and function of these regulatory proteins. An impairment of AC function has been shown to occur in sarcolemmal preparations (SL) of hearts exposed to either local or global ischaemia. To examine the contribution of G protein function to this phenomenon, cholera toxin (CT)-catalysed ADP-ribosylation of Gs and pertussis toxin (PT)-catalysed ADP-ribosylation of G proteins have been investigated in SL of porcine hearts exposed to global ischaemia for 15-45 min. ADP-ribosylation by CT of an approximately 45 kDa polypeptide was 0.46 +/- 0.06 and ADP-ribosylation by PT of three 39-41 kDa polypeptides was 4.77 +/- 0.77 pmol mg-1 protein in SL of non-ischaemic myocardium. Whereas no change was observed in CT-catalyzed ribosylation after 30 min of ischaemia, there was a reduction in PT-catalyzed ADP-ribosylation to 3.7 +/- 0.35 pmol mg-1 protein after 30 min of ischaemia. Prolongation of ischaemia to 45 min did not reduce further ADP-ribosylation capacity. Quantitative immunoblotting of PT-sensitive G proteins suggests that the diminution of ADP-ribosylation occurred because of a loss of alpha-subunits of G0, Gi-1, and Gi-2 from sarcolemmal membranes.

Adenosine Diphosphate Ribose↗
PubMed1991

Tachykinin (substance-P) gene expression in Leydig cells of the human and mouse testis.

Specific substance-P immunoreactivity can be detected in the Leydig cells, particularly of human testes, and to a lesser degree in mouse Leydig cells, but not in the rat. Using a modified polymerase chain reaction (PCR) assay, preprotachykinin-A (substance-P) mRNA could be detected in extracts of human, mouse, and bovine testes, but not in rat or boar testes or in bovine thyroid or corpus luteum used as negative controls. This assay is able to discriminate among the alpha, beta, and gamma transcripts of the gene and shows that only the beta and gamma transcripts are present in the testes. Sequencing analysis of the PCR products from bovine hypothalamus, mouse brain, and human testis confirmed the structure of these transcripts, which encode both substance-P and neurokinin-A (substance-K) neuropeptide hormones. Using a variant of this assay it was possible to identify tachykinin transcripts in as few as 500 freshly prepared purified mouse Leydig cells. In parallel studies PCR analysis was also able to confirm the presence of mRNA for both substance-P and neurokinin-A receptors in human testes. Thus, the tachykinins substance-P and neurokinin-A must now be added to the list of potentially paracrine substances regulating intratesticular function.

Aged↗
PubMed1991

[Histochemical investigations of the intracellular localization of adenylate cyclase activity after mitogenic or beta-adrenergic stimulation of T-lymphocytes of the mouse].

The role of AC at the beginning of an immune response is not fully understood until now. Using the specific substrate AMP-PNP we could show AC-activity in ConA-stimulated murine spleen lymphocytes histochemically. In contrast to beta-adrenergic stimulation (by Isoproterenol) ConA-induced AC-activity was found not only at the cell membrane and the nuclear membrane but also at some structures of the Golgi apparatus of the cells. The difference in AC-activity after beta-adrenergic or mitogenic stimulation is discussed.

Adenylyl Cyclases↗
PubMed1990

Synergistic cytotoxic effect of human recombinant tumor necrosis factor alpha combined with dihydroambazone.

Dihydroambazone (DHA) is a water-soluble derivative of the experimental anticancer drug ambazone. In vitro, a combination of DHA and human recombinant tumor necrosis factor alpha (TNF) exerted a strong synergism of cytotoxicity against both mouse melanoma B16K cells and the TNF-sensitive mouse fibroblast line L-M (S). Furthermore, in a colony-forming assay with B16K cells a combination of TNF and DHA inhibited colony-formation much more severely than either drug alone. An increased antiproliferative efficiency was also confirmed in vivo against established subcutaneous melanoma B16 tumors of C57BL/6 mice.

Animals↗
PubMed1990

A comparative study in twelve mammalian species of volume densities, volumes, and numerical densities of selected testis components, emphasizing those related to the Sertoli cell.

Morphometric studies were performed on 12 mammalian species (degu, dog, guinea pig, hamster, human, monkey, mouse, opossum, rabbit, rat, stallion, and woodchuck) to determine volume density percentage (Vv%), volume (V), and numerical density (Nv) of seminiferous tubule components, especially those related to the Sertoli cell, and to make species comparisons. For most species, measurements were taken both from stages where elongate spermatids were deeply embedded within the Sertoli cell and from stages near sperm release where elongate spermatids were in shallow crypts within the Sertoli cell. Montages, prepared from electron micrographs, were used to determine Vv% of Sertoli cell components in seminiferous tubules. Excluding the tubular lumen, the Sertoli cell occupied from a high of 43.1% (woodchuck) to a low of 14.0% (mouse) of the tubular epithelium. There was a strong negative correlation (r = -0.83; P less than 0.005) of volume occupancy of Sertoli cells with sperm production. Nuclear volume, as determined by serial reconstruction using serial thick sections, ranged from a high of 848.4 microns 3 (opossum) to a low of 273.8 microns 3 (degu). There was no correlation (r = 0.02) of nuclear volume with volume occupancy (Vv%) in the tubule. Sertoli cell volume was determined by point-counting morphometry at the electron-microscope level as the product of the nuclear size and points determined over the entire cell divided by points over the nucleus. Sertoli cell V ranged from 2,035.3 microns 3 (degu) to 7,011.6 microns 3 (opossum) and was highly correlated (r = 0.85; P less than 0.001) with nuclear size. However, there was no significant correlation between the Sertoli cell size (V) and volume occupancy (Vv%; r = 0.13) or sperm production (r = -0.21). Stereological estimates of the numerical density (Nv) of Sertoli cells ranged from a high of 101.9 x 10(6) (monkey) to a low of 24.9 x 10(6) (rabbit) cells per cm3 of testicular tissue. There was no correlation of numerical density of Sertoli cells with sperm production (r = 0.002). A negative correlation was, however, observed between the numerical density of the Sertoli cells and the Sertoli cell size (r = -0.79; P less than 0.002). Data from the present study are compared with those previously published. This is the first study to compare Sertoli cell morphological measurements using unbiased sampling techniques. Morphometric data are provided which will serve as a basis for other morphometric studies.

Animals↗
PubMed1990

Combination of the peroxidase anti-peroxidase (PAP)- and avidin-biotin-peroxidase complex (ABC)-techniques: an amplification alternative in immunocytochemical staining.

A combination of the PAP- and ABC-techniques was developed to enhance the intensity of the immunocytochemical staining with monoclonal antibodies at light and electron microscopical levels. This amplification technique could be performed in 4 (single PAP + ABC) or 6 (double PAP + ABC) sequential steps depending on the quality of the primary antibodies used and the processing of the tissue before the immunocytochemical reaction: First step--Incubation of the tissue sections with the monoclonal primary antibodies; Second step--biotinylated anti-rat or anti-mouse IgG; Third step--monoclonal PAP complex; Fourth step--ABC complex which binds to the biotinylated secondary antibody. If stronger enhancement of the immunostaining has required the steps 2 and 3 could be repeated followed by the 6th step--the ABC complex. Choline acetyltransferase-like immunoreactivity of the rat hypoglossal nucleus and desmin- and vimentin-like immunoreactivity of human testis were studied. After the 4- and more pronounced the 6-step reaction a significant increase of the staining intensity was observed for all the reactions under study. ChAT-like immunoreactivity was observed to longer distances of the nerve cell dendrites after their emerging from the perikarya and within a greater number of structures in the neuropil as compared to the standard techniques. At electron microscopical level the technique permits longer fixation of the tissue which is important for the better preservation of the ultrastructure as well as for the easier recognition of the reaction product even in the smallest dendrite branches and the axons of the nerve cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Collagen as a carrier for heart cell cultures].

Extracellular collagen from rat tail (types 1 and 3) is a suitable matrix for isolated neonatal heart cell cultivation. The fine structure and the physiological response to isoproterenol for instance is similar for neonatal cardiomyocytes cultured in the medium Sm 20-1 with or without collagen matrix. For electron microscopical routine preparation it is easier to use matrix-grown cardiomyocytes because additional preparation steps (centrifugation) are unnecessary.

Animals↗