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M Müller

Publications and source records attributed to M Müller.

At least 811 records · Page 45Linked to original sources
PubMed1995

Mechanism of the tumor necrosis factor alpha-mediated induction of endothelial tissue factor.

This study examines the regulation of the human tissue factor (TF) promotor in vitro and in vivo. Transient transfections were performed in bovine aortic endothelial cells to investigate the role of two fundamentally different AP-1 sites and a closely located NF-kappa B site in the human TF promoter. The NF-kappa B site is functionally active, since overexpression of NF-kappa B(p65) resulted in induction of TF mRNA and activity. Promoter analysis showed that NF-kappa B induction was dependent on the integrity of the region from base pair -188 to -181. Over-expression of Jun/Fos resulted in TF induction of transcription and protein/activity. Functional studies revealed that the proximal AP-1 site, but not the distal, was inducible by Jun/Fos heterodimers. The distal AP-1 site, which has a G-->A switch at position 4, was inductible by Jun homodimers. Electrophoretic mobility shift assays, using extracts of tumor necrosis factor alpha (TNF alpha)-stimulated bovine aortic endothelial cells, demonstrated TNF alpha-inducible binding to the proximal AP-1 site, comprising JunD/Fos heterodimers. At the distal AP-1 site, only minor induction of binding activity, characterized as proteins of the Jun and ATF family, was observed. Consistently, this site only marginally participates in TNF alpha induction. Functional studies with TF promotor plasmids confirmed that deletion of the proximal AP-1 or the NF-kappa B site decreased TNF alpha-mediated TF induction to a higher extend than loss of the distal AP-1 site. However, integrity of both AP-1 sites and the NF-kappa B site was required for optimal TNF alpha stimulation. The relevance of these in vitro data was confirmed in vivo in a mouse tumor model. Expression plasmids for a dominant negative Jun mutant or I-kappa B were packaged in liposomes. When either mutated Jun or I-kappa B were injected intravenously 48 h before TNF alpha, a reduction in TNF alpha-mediated TF expression in the tumor endothelial cells was observed. Simultaneously, fibrin/fibrinogen deposition decreased and free blood flow could be restored. Thus, TNF alpha-induced up-regulation of endothelial cell TF depends on a concerted action of members of the bZIP and NF-kappa B family.

Animals↗
PubMed1995

The functional integration of a polytopic membrane protein of Escherichia coli is dependent on the bacterial signal-recognition particle.

In eukaryotes, the cotranslational targeting of proteins to the endoplasmic reticular membrane is initially mediated by the signal-recognition particle (SRP), a ribonucleoprotein complex consisting of the 7SL RNA and six protein subunits. Since the discovery of sequence homology between (a) the Escherichia coli 4.5S RNA (Ffs) and 7SL RNA, and (b) the E. coli P48 (Ffh) and SRP 54-kDa subunit, more evidence has been obtained that E. coli also possesses an SRP-type pathway that acts in the translocation of secreted proteins. Such a pathway could possibly be involved in the cotranslational integration of hydrophobic membrane proteins that cannot be effectively targeted post-translationally due to folding and aggregation. In this study, we report that disruption of the E. coli SRP complex with a dominant lethal 4.5S RNA mutant in vivo prevents functional membrane integration of the E. coli lactose permease (LacY). Likewise, depletion of the P48 (Ffh) protein also results in a decrease in the amount of functional LacY inserted into the E. coli plasma membrane. In direct contrast, inhibition of SecA function does not affect LacY integration. These results suggest a major function of the bacterial SRP in the targeting and subsequent integration of hydrophobic membrane proteins as opposed to SecA mediating the post-translational targeting of secretory proteins.

Escherichia coli↗
PubMed1995

[Treatment of constipation in pregnant women. A multicenter study in a gynecological practice].

Constipation is a common problem during pregnancy. It is essential to relieve the condition without putting the developing child at risk or further stressing the mother. The fact that lactulose is not absorbed in the small intestine is of great significance when treating constipation during pregnancy, as it presents no threat to the foetus. Lactulose also does not appear in breast milk so that the treatment can also be continued during nursing. The present study was an open base-line controlled study to show the efficacy, safety and acceptability of dry lactulose (Duphalac Dry) in pregnant women suffering from chronic or occasional constipation. It was a multi-center study in 12 gynecological practices. 62 women aged between 19 and 40 years were treated during 4 weeks with lactulose. 34% had chronic constipation and the remaining 66% constipation due to the pregnancy. The main criteria for efficacy were frequency of defecation and consistency of stools. There was overall judgement of the efficacy by patients and doctors. Safety was assessed by the number of reported side-effects and compared to the reported concomitant symptoms before treatment. Here also, the patients and their doctors gave a global impression. In addition, patients rated the product flavor and administration methods. The frequency of defecation was significantly increased after 1 week (4.0 vs. 2.5 [median per week], p < 0.001) and normalized after 2 weeks (6 stools per week). Also, the consistency of the stools was normalized during the treatment. The global assessment of efficacy by the treating physicians was good or very good in 84% of the cases and by the patients in 81%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[(Alkylamino)methyl]acrylophenones: potent and selective inhibitors of the epidermal growth factor receptor protein tyrosine kinase.

[(Alkylamino)methyl]acrylophenones and (alkylamino)propiophenones, bearing a spacer moiety such as the benzyloxy or (benzoylsulfonyl)oxy group in the 4-position, represent a novel class of inhibitors of the epidermal growth factor (EGF) receptor protein tyrosine kinase with a high degree of selectivity versus other tyrosine and serine/threonine kinases. The most active compounds inhibited the EGF receptor protein tyrosine kinase from A431 cell membranes with IC50 values of < 0.5 microM. Derivatives with a benzyloxy substituent in the 4-position of the aromatic ring inhibited both the EGF receptor kinase and the proliferation of an EGF-dependent mouse epidermal keratinocyte cell line (BALB/MK) but were only marginally active in the inhibition of the cellular EGF-dependent tyrosine phosphorylation. Compound 18 inhibited ligand-induced tyrosine phosphorylation and BALB/MK cell proliferation with IC50 values of approximately 100 and 1.21 microM, respectively, and showed antitumor activity in vivo in a nude mouse model. However, the discrepancy between the IC50 values for antiproliferative activity and cellular tyrosine phosphorylation as well as the relatively low tolerability in animals suggests a second site of action of this class of inhibitors. Nevertheless, [(alkylamino)methyl]acrylophenones and (alkylamino)propiophenones may prove to be interesting tools for studying the action of tyrosine kinases.

Animals↗
PubMed1995

Oligogalacturonide defense signals in plants: large fragments interact with the plasma membrane in vitro.

Oligogalacturonides are plant cell wall-derived regulatory molecules which stimulate defense gene expression during pathogenesis. In vitro, these compounds enhance the phosphorylation of an approximately 34-kDa protein (pp34) in purified plasma membranes from potato and tomato leaves. We now show that polygalacturonate-enhanced phosphorylation of pp34 occurs in plasma membranes purified from tomato roots, hypocotyls, and stems and from undifferentiated potato cells. Furthermore, a similar phosphorylation is detected in leaf plasma membranes from soybean, a plant distantly related to tomato. Purified oligogalacturonides 13 to at least 26 residues long stimulate pp34 thiophosphorylation in vitro. This stimulation pattern differs from the induction of many known defense responses in vivo, where a narrower range of smaller fragments, between approximately 10 and 15 residues long, are active. On the basis of these differences we suggest that observed effects of applied exogenous oligogalacturonides on defense responses may not necessarily reflect the situation during pathogenesis. The cell wall could act as a barrier to many exogenous oligo- and polygalacturonides as well as other large regulatory ligands.

Journal Article↗
PubMed1995

Selective inhibition of the platelet-derived growth factor signal transduction pathway by a protein-tyrosine kinase inhibitor of the 2-phenylaminopyrimidine class.

The platelet-derived growth factor (PDGF) receptor is a member of the transmembrane growth factor receptor protein family with intrinsic protein-tyrosine kinase activity. We describe a potent protein-tyrosine kinase inhibitor (CGP 53716) that shows selectivity for the PDGF receptor in vitro and in the cell. The compound shows selectivity for inhibition of PDGF-mediated events such as PDGF receptor autophosphorylation, cellular tyrosine phosphorylation, and c-fos mRNA induction in response to PDGF stimulation of intact cells. In contrast, ligand-induced autophosphorylation of the epidermal growth factor (EGF) receptor, insulin receptor, and the insulin-like growth factor I receptor, as well as c-fos mRNA expression induced by EGF, fibroblast growth factor, and phorbol ester, was insensitive to inhibition by CGP 53716. In antiproliferative assays, the compound was approximately 30-fold more potent in inhibiting PDGF-mediated growth of v-sis-transformed BALB/c 3T3 cells relative to inhibition of EGF-dependent BALB/Mk cells, interleukin-3-dependent FDC-P1 cells, and the T24 bladder carcinoma line. When tested in vivo using highly tumorigenic v-sis- and human c-sis-transformed BALB/c 3T3 cells, CGP 53716 showed antitumor activity at well-tolerated doses. In contrast, CGP 53716 did not show antitumor activity against xenografts of the A431 tumor, which overexpresses the EGF receptor. These findings suggest that CGP 53716 may have therapeutic potential for the treatment of diseases involving abnormal cellular proliferation induced by PDGF receptor activation.

3T3 Cells↗
PubMed1995

A cell-free protein translocation system prepared entirely from a gram-positive organism.

A cell-free protein translocation system derived exclusively from a Gram-positive bacterium is described here for the first time. Highly efficient in vitro synthesis of plasmid encoded preprolipase of Staphylococcus hyicus is accomplished by coupled transcription/translation using either a cytosolic extract of S. carnosus alone or in combination with T7-RNA-polymerase. Addition of inside-out cytoplasmic membrane vesicles of S. carnosus leads to the partial conversion (processing) of preprolipase to prolipase. In addition, as shown in a protease protection assay, a significant part of preprolipase plus prolipase is translocated in vitro into the lumen of the vesicles. Translocation of preprolipase into the membrane vesicles requires the proton-motive force and the S. carnosus SecA protein.

Adenosine Triphosphatases↗
PubMed1995

Plasma concentration of tissue factor and factor VII in patients after abdominal surgery.

Tissue injury following trauma and surgery may induce alterations in blood coagulation and fibrinolysis. Hypercoagulable state after surgery can be associated with the risk of postoperative thromboembolic complications. The contact of coagulation factors with TF after injury of vessel wall and organ tissues may contribute to the development of thrombosis after surgery (1). TF, the cell surface receptor and cofactor of factor VII/VIIa is normally not expressed by cells within the vasculature. Only monocytes and endothelial cells can be stimulated to express TF transiently by a variety of inflammatory and immunological reactions (for review see 2,3). Also surgical treatment was reported to induce TF synthesis in monocytes (4,5,6). TF is present in many extravascular tissues as vascular adventitia, organ capsules, epidermis, colonic mucosal epithelium, liver stroma, pancreas stroma and also on tumor cells (7-12). In this study, we investigated, whether we can detect the release of TF from the traumatized tissues and from activated monocytes into the circulation following abdominal surgery. To test the dependence of the extension of tissue injury during surgery we segregated the patients into group A with major abdominal operations and group B consisting of patients with appendectomy and cholecystectomy. No relationship could be established between changes of TF and postoperative thromboembolic complications.

Abdomen↗
PubMed1995

Increased immunostaining for L-ornithine decarboxylase occurs in neocortical neurons of Alzheimer's disease patients.

We investigated the distribution of L-ornithine decarboxylase (ODC), an enzyme known to be involved in several developmental and restorative processes, in neocortical brain areas of Alzheimer's disease (AD) and normal patients by means of immunohistochemistry. While ODC immunoreactive material was only scarcely distributed in neocortical neurons of control brains, neocortical specimens from AD brains stood out by intense immunostaining for ODC. Dendrites and, to a lesser extent, axons of neurons from AD brains showed a strong immunoreaction to the enzyme, whereas neurons from non-affected brains displayed only a weak circumnuclear reaction pattern. Our results support the idea that neurorestorative processes take place in AD brains and that the ODC/polyamine system might be actively involved in this process.

Aged↗
PubMed1995

Primary sequence of a putative pyrophosphate-linked phosphofructokinase gene of Giardia lamblia.

Based on sequence information from a cosmid library, we obtained a genomic clone that encodes a putative inorganic pyrophosphate (PPi)-linked phosphofructokinase of Giardia lamblia. The open reading frame specified a protein of 59.8 kDa homologous to PPi- and ATP-linked phosphofructokinases. The greatest similarity (over 50% positional identity) was noted to the beta-subunits of both the Solanum tuberosum (potato) and Ricinus communis (castor bean) PPi-phosphofructokinases.

Amino Acid Sequence↗
PubMed1995

Subtle differences in antibody responses and hypermutation of lambda light chains in mice with a disrupted chi constant region.

Analysis of lambda light chain use in normal mice is made difficult by the dominant chi light chain repertoire. We produced mice rendered deficient in chi light chain expression by gene targeting and focused on questions concerned with the generation of lambda light chain diversity. Whilst these mice compensate the chi deficiency with increased lambda liters, and their Ig level is therefore not significantly reduced, they show major differences in immunization titers, germinal center (GC) development and somatic hypermutation. After immunization, using antigens that elicit a restricted IgL response in normal mice, we obtained in the chi-/- mice elevated primary antibody titers but a subsequent lack in titer increase after repeated antigen challenge. Analysis of the Peyer's patches (PP) revealed a dramatically reduced cell content with rather small but highly active GC. Flow cytometric analysis showed different cell populations in the PP with enriched peanut agglutinin (PNA)hi/CD45R(B220)+ B cells, implying that the apparent compensation for the lack of lambda light chain expression involves the GC microenvironment in cell selection, the initiation of hypermutation and high affinity expansion. The three V lambda genes, V1, V2 and Vx, are mutated in the GC B cells, but show no junctional diversity. In contrast, a reduced rate of V lambda hypermutation is found in the hybridoma antibodies, which appears to reflect a selection bias rather than structural constraints. However, mechanisms of somatic mutation and specificity selection can operate with equal efficiency on the few V lambda genes.

Amino Acid Sequence↗
PubMed1995

In vitro and in vivo effects of pentoxifylline on macrophages and lymphocytes derived from autoimmune MRL-lpr/lpr mice.

MRL-lpr/lpr mice develop an autoimmune disease similar to human systemic lupus erythematosus (SLE). The main characteristics of this disease are increasing autoantibody formation, elevated plasma levels of immune complexes, a massive lymphoproliferation, a rising proteinuria, and arthritic symptoms. Finally, the mice die at an age of about 6 months due to a fatal immune complex glomerulonephritis. Macrophages are involved in the development of SLE due to their functions as antigen-presenting as well as cytokine-producing cells. T and B cells are involved in the disease by secreting cytokines and producing antibodies. Pentoxifylline (PTX), a xanthine derivative, is known to exert different effects on functions of leukocytes and erythrocytes and has been used in clinical studies, e.g., in septic shock syndrome. In our studies we first investigated the in vitro effect of PTX on macrophages and lymphocytes derived from MRL-lpr mice. Our investigations concerning production of superoxide anion and TNF-alpha by LPS and/or IFN-gamma activated bone marrow and peritoneal macrophages, MHC class II expression on these cells, and the proliferative capacity and Il-2 production of mitogen activated lymphocytes, revealed that PTX reduces the activation and the inflammatory response of these cells. Based on these results, we further investigated the effect of in vivo treatment with PTX. MRL-lpr mice treated with PTX showed diminished proteinuria, reduced titer of dsDNA-autoantibodies in the plasma and an increased survival rate. Our data clearly demonstrate that PTX is able to diminish the severity of the disease and to prolong the life of MRL-lpr/lpr mice.

Animals↗
PubMed1995

Theophylline kinetics in peripheral tissues in vivo in humans.

Several biochemical and cellular effects have been described for methylxanthines under in vitro conditions. However, it is unknown, whether threshold concentrations required to exert these effects are attained in target tissues in vivo. We therefore employed the microdialysis technique for measuring theophylline concentrations in peripheral tissues under in vivo conditions. Following in vitro and in vivo calibration, microdialysis probes were inserted into the medial vastus muscle and into the periumbilical subcutaneous adipose layer of healthy volunteers. Following single oral dose administration of 300 mg or i.v. infusion of 240 mg theophylline, in vivo time courses of theophylline concentrations were monitored in tissues and plasma. Major pharmacokinetic parameters (cmax, tmax, AUC) were calculated for plasma and tissue time courses. The mean AUCtissue/AUCplasma-ratio was 0.56 (p.o.) and 0.55 (i.v.) for muscle and 0.55 (p.o.) and 0.72 (i.v.) for subcutaneous adipose tissue. We conclude that microdialysis provides important information on the distribution and the tissue pharmacokinetics of theophylline.

Adult↗
PubMed1995

Investigations into the oral lead exposure of adults in the former German Democratic Republic.

The lead content of a representative assortment of foodstuffs and drinking water as well as the lead intake of adults were systematically investigated in 1988 in order to judge the oral lead exposure of the inhabitants of the former German Democratic Republic (GDR). The foodstuffs as well as the drinking water contained normal lead concentrations. Levels exceeding the limits set by the Federal Office of Health and the Decree on Drinking Water were not obtained. The lead intake was 34 micrograms/day in adult men and 25 micrograms/day in adult women according to the results of the basket study, amounting to 11-13% of the PTWI provisional tolerable weekly intake value of lead. An oral lead exposure of the adult population in the former GDR can be excluded.

Adult↗
PubMed1995

Distribution of E-cadherin and Ep-CAM in the human lung during development and after injury.

Paraffin sections were obtained of human fetal, adult, and pathological lung (pulmonary fibrosis after radiotherapy or chemotherapy). The localization of epithelial adhesion molecules E-cadherin and Ep-CAM (former epithelial surface 40 kDa glycoprotein) was investigated by immunoperoxidase and/or immunofluorescence techniques with monoclonal antibodies. During development, the epithelia of the primary pulmonary primordium, the secondary bronchi and the adult bronchial epithelium retained immunoreactivity for E-cadherin and Ep-CAM with lateral immunostaining of cell membranes. In normal adult lungs, Ep-CAM was detected in type I and II alveolar epithelial cells, whereas E-cadherin was confined to the basolateral domain of type II cells. In pulmonary fibrosis, Ep-CAM could be further detected on the cell surface of epithelial remnants. In contrast, E-cadherin expression was characterized by a change of the membrane localization to a spotty, cytoplasmic pattern in the alveolar epithelium, possibly indicating functional inactivation of the protein during fibrogenesis.

Adult↗
PubMed1995

Immunocytochemical distribution of E-cadherin in normal and injured lung tissue of the rat.

Affinity purified rabbit anti-mouse E-cadherin antibodies, reacting with diverse rat epithelia, were used to characterize epithelial changes in a radiation-induced fibrosis model of rat lung by immunoblotting techniques, immunoperoxidase and immunofluorescence microscopy. Immunostaining of normal rat lung tissues revealed a predominant staining of type II pneumocytes. Immunoelectron microscopy confirmed the immunohistochemical data of normal lung tissue obtained at the light microscopic level. In severely injured rat lung, we found enhanced immunoreactivity for E-cadherin at the surface of type I alveolar epithelial cells. The results suggest that E-cadherin is an adhesion molecule that is modulated after pathological alteration of the alveolar epithelium and that the antiserum may be useful for the characterization of normal and diseased rat epithelia.

Animals↗
PubMed1995

Immunohistochemical evidence for loss of ICAM-1 by alveolar epithelial cells in pulmonary fibrosis.

ICAM-1 is an intercellular adhesion molecule of the immunoglobulin supergene family involved in adherence of leukocytes to the endothelium and in leukocytic accumulation in pulmonary injury. In the current study, the antigen retrieval technique was used to detect ICAM-1 immunohistochemically in paraffin sections of lungs from human, mouse and rat as well as in bleomycin- or radiation-induced fibrotic lungs from rat and human. In normal lung tissue, the expression of ICAM-1 on alveolar type I epithelial cells is stronger than on alveolar macrophages and on endothelial cells. Preembedding immunoelectron microscopy of normal rat, mouse and human lung samples revealed selective ICAM-1 expression on the surface of type I alveolar epithelial cells and, to a lesser extent, on the pulmonary capillary endothelium and on alveolar macrophages. In fibrotic specimens, both focal lack and strengthening of immunostaining on the surface of type I cells was found. Alveolar macrophages were found focally lacking ICAM-1 immunoreactivity. In some cases, rat type II pneumocytes exhibited positive immunoreactions for ICAM-1. Immunoelectron microscopy with preembedded rat lungs (bleomycin-exposed cases) confirmed the altered ICAM-1 distribution at the alveolar epithelial surface. In the alveolar fluid of fibrotic rat lungs, in contrast to that from untreated controls, soluble ICAM-1 was detected by western blot analysis.

Animals↗