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Biomedical subjects

G Müller-Berghaus

Publications and source records attributed to G Müller-Berghaus.

At least 19 recordsLinked to original sources
PubMed1992

Application of an automated plasma filtration device and a blood monitoring system for LDL apheresis.

This study describes the adaptation of a filtration separation device (AK 10 from Gambro, München, FRG) and a blood monitor system (BTS 100 from Diamed, Köln, FRG) to the automated adsorption/desorption device for LDL apheresis. Plasma separation by filtration was performed by a hollow-fiber filter (OP5, Asahi Corp., Japan). In order to evaluate the quality of the plasma obtained by filtration, the platelet contamination, the activity of factors V and VIII and the concentration of the immunoglobulins IgG and IgM were determined. The following results were found: Platelet contamination of the plasma was 2,740/microliters. As compared to the patient's pretreatment values, activity of factor V was 94%, activity of factor VIII was 104%, concentration of IgG was 96%, concentration of IgM was 94%. Ten LDL aphereses were evaluated: red cell counts, platelet counts, hemoglobin concentration and hematocrit were not changed significantly. Thus, this new combination system represents an improved alternative to previously performed centrifugation methods.

Blood Cell Count↗
PubMed1992

Bedside monitoring of anti-coagulation under LDL apheresis by means of aPTT testing with a coagulation monitor.

Optimally adjusted anticoagulation under LDL apheresis is essential for successful treatment: Excessive anticoagulation exposes the outpatient to the risk of uncontrolled hemorrhage, insufficient anticoagulation may shorten the duration of utilization of the immune-adsorption columns. A new device (coagulation monitor 512, Ciba Corning) allows individual adaptation of dosage and timing of heparin application by modifying the standard schedule (5,000 IU intravenously before treatment, 2,000 IU/h continuously). APTT was measured before and after application of heparin and then at 30-min intervals both by the coagulation monitor and by conventional laboratory methods; the respective heparin concentration was determined in addition. The correlation coefficient between the heparin concentration and both the monitor-derived and the laboratory-derived aPTT was 0.811 and 0.590, respectively. An explanation for this finding might be that the monitor avoids the influences induced by subsequent collection and testing of samples associated with laboratory procedures.

Cholesterol, LDL↗
PubMed1992

[Preoperative autologous blood donation in heart surgery patients: laboratory parameters with oral iron substitution].

In this study we analyzed some hematologic parameters of 228 autologous blood donors at a cardiosurgic clinic. The standard schedule of drawing autologous blood at our clinic is 4 units whole blood (450 ml) and 1 unit plasma (750 ml) for a time of 5 weeks under iron substitution (equivalent to 240 mg Fe). In younger women this kind of drawing blood leads to an unacceptable decrease of hemoglobin concentration. The preoperative autologous blood donation results in an increase of erythropoiesis on the day of clinical admittance. The best parameters to supervise the hematologic situation of the outpatient autologous blood donors are the hemoglobin concentration and the hematocrit.

Adult↗
PubMed1992

[Decreased fibrinolytic capacity in coronary patients by increased plasminogen activator inhibitor activity].

The fibrinolytic capacity of the blood mainly depends on the amount of tissue-plasminogen activator (t-PA) antigen and plasminogen activator inhibitor (PAI). In this study the fibrinolytic response to a venous occlusion test (VOT) was measured in 109 patients with angiographically documented coronary artery disease (CAD) and in 20 healthy volunteers at comparable age (controls). CAD-patients had higher plasma plasminogen activator inhibitor capacity before (24.4 +/- 11.0 vs. 15.4 +/- 5.2 arbitrary units [AU/ml]; p less than 0.0002) and after VOT (19.6 +/- 13.2 vs. 10.9 +/- 5.3 AU/ml; p less than 0.0001) compared with controls. Furthermore they showed significant lower plasma t-PA activity after VOT (3.0 +/- 6.8 vs. 6.6 +/- 10.6 AU/ml; p less than 0.0001). However there were no difference between both groups in plasma t-PA antigen levels after VOT (17.3 +/- 12.1 vs. 18.7 +/- 14.4 ng/ml). In 10% of patients the decrease in fibrinolytic activity resulted from a lower t-PA release ("lower" was defined as mean minus one standard deviation of the control group). 40% showed elevated plasma PAI capacity before VOT ("elevated" was defined as mean plus two standard deviations of the control group). Both caused significantly reduced post occlusion plasma t-PA activity and prolonged Euglobulin clot lysis time (p less than 0.003). A positive correlation was found between PAI capacity and serum triglyceride levels. Reduced fibrinolytic activity in 109 patients with coronary heart disease based either on a decrease in t-PA antigen release or a increased in PAI capacity in comparison with healthy controls. The mechanism of these findings is not yet well-known.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Different glycoforms of human thrombomodulin. Their glycosaminoglycan-dependent modulatory effects on thrombin inactivation by heparin cofactor II and antithrombin III.

The relationship between thrombomodulin-associated O-linked glycosammoglycans (GAGs) and the exogenous GAGs heparin or dermatan sulfate was studied in the inhibition of thrombin by antithrombin III (AT III) or heparin cofactor II (HC II). Both rabbit thrombomodulin (TM) and two glycoforms (a high-Mr form containing GAGs and a low-Mr form lacking the majority of O-linked GAGs) of a recombinant human TM deletion mutant (rec-TM) were used. The rapid inactivation of thrombin by HC II in the presence of dermatan sulfate was prevented by both the high-Mr rec-TM and the rabbit TM. In contrast, both rabbit TM treated with chondroitin ABC lyase to remove O-linked GAGs and the low-Mr form of rec-TM had only weak protecting effects. In the absence of exogeneous dermatan sulfate, thrombin inhibition by a high concentration of HC II was slightly accelerated by the high-Mr form of rec-TM but protected by rabbit TM. When thrombin inhibition by AT III in the presence of heparin was studied, both high-Mr rec-TM and rabbit TM again invoked a similar reduction of inactivation rates, whereas in the absence of exogenous heparin, both high-Mr forms accelerated thrombin inhibition by AT III. The diverse reactivities of various forms of TM towards HC II and AT III were also observed during protein C activation by the thrombin-TM complex. These results suggest that thrombin activity at the vessel wall or in fluid phase may undergo major kinetic modulations depending on the type of protease inhibitor, the presence or absence of exogenous GAGs and the glycosylation phenotype of TM. The dependence of TM anticoagulant function on the presence of an intrinsic GAG moiety suggests that variant glycoforms of this endothelial cell cofactor may be expressed differently in a species-, organ-, or tissue-specific manner as a means to regulate TM function in diverse vasculatures.

Animals↗
PubMed1991

Relationship between post-translational glycosylation and anticoagulant function of secretable recombinant mutants of human thrombomodulin.

Two glycoforms of a soluble mutant of recombinant human thrombomodulin (rec.TM) were used to identify critical N- and O-linked glycans of the endothelial cell thrombin receptor. While N-linked glycans were not found to be involved in any function of rec.TM, an acidic chondroitin sulphate-like glycosaminoglycan (CSGAG) was found to be critical for all the direct anticoagulant functions of rec.TM, including inhibition of thrombin-mediated platelet aggregation. A glycoform of rec.TM lacking CSGAG had very poor anticoagulant activity. Furthermore, the glycoform of rec.TM possessing CSGAG showed strong inhibition by and had high affinity for poly-cationic basic proteins, whereas the CSGAG-deficient rec.TM did not. Monoclonal antibody binding as well as lectin mapping of rec.TM with agglutinins identified sialic acid containing O-linked glycans in both glycoforms additional to the CSGAG in high molecular weight rec.TM These findings define important molecular interactions modulating the anticoagulant function of TM, which appear to be critically regulated by CSGAG, and also showed that the overall post-translational glycosylation pattern of the two glycoforms was very similar except for the presence of CSGAG. The possibility exists that differently expressed glycoforms of TM may be crucial for the expression of endothelial cell-related anticoagulant potential in different vascular beds.

Antibodies, Monoclonal↗
PubMed1991

[Autologous hemotherapy in heart transplantation: a case report].

The use of autologous blood in patients with organ transplantations is feasible only when the blood is stored in the frozen state, since the timing of the operation is not predictable. A 53 year-old patient with dilatative cardiomyopathy was selected for transplantation. By preoperative donation, four erythrocyte concentrates were prepared and frozen by high-glycerol low-temperature technique. The frozen blood was thawed, manually washed and made available for transfusion as required. The increment of hemoglobin after transfusion was 0.9 g/dl per unit. Quality control of the prepared erythrocyte concentrates was performed: Resistance to osmotic fragility of the erythrocytes was in the normal range, beginning hemolysis was found at 0.40 +/- 0.02% NaCl, complete hemolysis was found at 0.30 +/- 0.02% NaCl. The osmolarity of the supernatant fluid of the final washing was 0.314 +/- 0.116 mosmol/l. This case report stresses the feasibility to prepare and store autologous blood even if the time when the blood is needed cannot be determined.

Blood Component Transfusion↗
PubMed1990

Heparin stimulates fibrinolysis in mesothelial cells by selective induction of tissue-plasminogen activator but not plasminogen activator inhibitor-1 synthesis.

The regulation of tissue-plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) synthesis was studied in cultured human mesothelial cells derived from omentum (HOMC). Heparin (100 U/ml) as well as pentosan polysulfate (300 micrograms/ml) stimulated tPA synthesis by HOMC 2.9-4.5-fold. Heparin-induced tPA production was dose- and time-dependent and was inhibited by cycloheximide. tPA production by HOMC was also stimulated by phorbol 12-myristate 13-acetate (2.6-fold), fibrin clots (1.9-fold), or batroxobin (1.9-fold). Heparin and pentosan polysulfate did not stimulate PAI-1 production by HOMC, while phorbol 12-myristate 13-acetate (100 nM) increased the concentration of PAI-1 in the conditioned medium by 2.6-fold over 24 h. The interaction of heparin with HOMC was studied by direct binding experiments. Dose-dependent specific binding of biotinylated heparin to HOMC was saturable at about 10 micrograms/ml, the KD was estimated to about 0.15 microM. Biotinylated heparin bound rapidly to HOMC and reached a plateau within 60 min. Unlabeled heparin as well as pentosan polysulfate inhibited binding of biotinylated heparin in a dose-dependent fashion. These data demonstrate that heparin interacts with HOMC, and increases the fibrinolytic capacity in these cells by selectively increasing the production of tPA.

Biotin↗
PubMed1990

Structural requirements for the extracellular interaction of plasminogen activator inhibitor 1 with endothelial cell matrix-associated vitronectin.

The interaction of plasminogen activator inhibitor-1 (PAI-1) with its binding protein vitronectin (VN) (Declerck, P. J., De Mol, M., Alessi, M.-C., Baudner, S., Paques, E.-P., Preissner, K. T., Müller-Berghaus, G., and Collen, D. (1988) J. Biol. Chem. 263, 15454-15461) in the extracellular matrix (ECM) of cultured human endothelial cells (HUVEC) was studied. Like PAI-1, VN was found associated with the ECM as evidenced by direct antibody binding, by Western blot analysis as well as by diffuse immunofluorescence staining in permeabilized HUVEC. The specific interaction of VN with confluent monolayers of HUVEC was found to be saturable within 2-4 h at 37 degrees C only with respect to binding to the cells, while no saturable binding to the underlying ECM was observed, indicating that the majority if not all ECM-associated VN was derived from the culture medium. In contrast to PAI-1, ECM-associated VN was resistant toward glycine (pH 2.3), guanidine or urokinase treatment, suggesting that VN was tightly associated with the ECM network. Binding of recombinant PAI-1 (rPAI-1) was largely blocked by anti-VN IgG and only partly by anti-collagen IgG but not by antibodies against other ECM components, indicating that VN constitutes the primary binding protein for ECM-associated PAI-1. This contention was supported by ligand blotting experiments in which rPAI-1 was reacted with nitrocellulose replicas of electrophoretically separated ECM components. Protein band(s) (Mr = 63,000-67,000), comigrating with bovine VN (i.e. medium-derived VN) rather than with human VN were identified as major binding component(s). Moreover, binding studies with purified components revealed that PAI-1 did not show any affinity for collagen (type I/III) alone, whereas VN collagen coating was a much better template for PAI-1 binding than VN alone and that conformationally extended VN provides maximal PAI-1 binding capacity. Binding of rPAI-1 to surface-coated VN was saturable and revealed that (unlike urokinase) heparin or the synthetic peptide Gly-Arg-Gly-Asp-Ser did not inhibit PAI-1 binding. Ligand binding of rPAI-1 to nitrocellulose replicas from sodium dodecyl sulfate-polyacrylamide gels containing electrophoretically separated peptides from VN digests documented the association of PAI-1 with Mr = 10,000-20,000 fragments originating from the heparin-binding domain of VN. These results indicate that the exposure of the glycosaminoglycan-binding domain in VN may allow the concomitant binding of PAI-1 and heparin-like molecules to this region of the VN molecule.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1990

Domain structure of the endothelial cell receptor thrombomodulin as deduced from modulation of its anticoagulant functions. Evidence for a glycosaminoglycan-dependent secondary binding site for thrombin.

Rabbit thrombomodulin (TM) influences blood coagulation by serving as a cofactor for thrombin-induced protein C activation (activity a), by directly affecting the procoagulant activity of thrombin (activity b) and by accelerating the inhibition of thrombin by antithrombin III (AT III) (activity c). Although high molecular weight cationic compounds, such as poly-L-lysine and the ionophore-releasate from human platelets, only partly affected activity a in a concentration-dependent manner, activities b and c, however, were almost totally inhibited by these cationic compounds. Likewise, a heparin- and dermatan sulfate-binding peptide which represents a portion of the glycosaminoglycan-binding domain of vitronectin (VN) selectively inhibited activities b and c, indicating the presence of clustered acidic domain(s) in TM responsible for these activities. While heparinase or heparitinase did not affect rabbit TM function at all, digestion of rabbit TM with chondroitin ABC-lyase abolished activities b and c, whereas activity a remained unaffected. Modification of rabbit TM with chondroitin ABC-lyase was associated with a decrease in molecular mass of the receptor by about 10 kDa and a 2- to 3-fold decrease in affinity to thrombin as deduced from direct binding studies. These results suggest that at least two acidic thrombin binding domains are present in rabbit TM, whereby a dermatan sulfate-like glycosaminoglycan moiety constitutes the secondary binding domain for thrombin, eliciting both the direct as well as the AT III-dependent anticoagulant function of rabbit TM (activities b and c) but not protein C activation (activity a). In contrast to rabbit TM, human TM isolated from placenta only showed weak activities b and c. These differences in reactivity of TM from different sources appeared to be due to the masking (or absence) of the proposed secondary thrombin binding site in human TM, since VN could be identified as a major contamination in the human TM preparation as revealed by enzyme-linked immunosorbent assay and Western blot analysis. In addition, the major part of human TM could be immunoprecipitated by monospecific antibodies to VN. These findings indicate a possible modulatory function for VN in the human thrombin-TM system.

Amino Acid Sequence↗
PubMed1990

Regulation of endothelial tissue plasminogen activator and plasminogen activator inhibitor type 1 synthesis by diacylglycerol, phorbol ester, and thrombin.

The influence of diacylglycerols, which are physiological activators of protein kinase C, on the production of tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor type 1 (PAI-1) by human umbilical vein endothelial cells (HUVEC) was studied in order to gain insight into the regulation of fibrinolysis by these cells. 1,2-dioctanoyl-sn-glycerol (diC8) stimulated tPA production in a dose- and time-dependent manner. The tPA antigen in cell supernatants increased from 0.9 ng/10(6) cells in unstimulated cells to 12.4 ng (10(6) cells after incubation with 400 microM diC8 for 24 hours. In contrast, PAI-1 production was not influenced by diC8, whereas phorbol 12-myristate 13-acetate (PMA) or thrombin stimulated both, tPA and PAI-1 production by HUVEC. Staurosporine and H7, which are inhibitors of protein kinase C, inhibited tPA synthesis by HUVEC. The degree of inhibition was dependent on the agonist used. While diC8-induced tPA production was inhibited to more than 80% by H7 (10 microM) and staurosporine (10 nM), higher doses of inhibitors were required to inhibit thrombin- and PMA-induced tPA production. Thrombin-induced PAI-1 production was inhibited to more than 80% by H7 (10 microM) and to about 50% by staurosporine, whereas PMA-induced PAI-1 production was not inhibited by staurosporine, and only to about 50% by higher doses of H7 (30 microM). These data suggest that activation of protein kinase C is a common intracellular trigger mechanism for the induction of tPA synthesis by HUVEC. Protein kinase C is most likely also involved in the regulation of PAI-1 synthesis by HUVEC.

Diglycerides↗
PubMed1990

Identification of endothelial and mesothelial cells in human omental tissue and in omentum-derived cultured cells by specific cell markers.

Human omental tissue has been used as a source for the isolation and cultivation of microvascular endothelial cells, but also for mesothelial cells. Since both cell types have several morphologic and functional features in common, concerns were raised whether endothelial cells can be separated from mesothelial cells by the methods described for the isolation of microvascular endothelial cells. In the present study, endothelial cells were identified in the capillaries of native human omentum by several endothelial-cell specific markers. von Willebrand factor was demonstrated by polyclonal and monoclonal antibodies, a lectin-specific ligand by Ulex europaeus I, and an endothelial-cell specific surface epitope by the monoclonal antibody, PAL-E. These markers were not found positive with mesothelial cells of native omentum. Mesothelial cells were identified by monoclonal antibodies against the intermediate filaments, cytokeratin and vimentin. After having demonstrated the specificity of the methods for the distinction between endothelial and mesothelial cells within native omentum, these methods were applied to omentum-derived cells previously claimed to be microvascular endothelial cells. These cultured cells proved to be negative for von Willebrand factor, Ulex europaeus I ligand and PAL-E epitope. In contrast to this, the cultivated cells stained positive to cytokeratin and vimentin. Furthermore, it was shown by immunoprecipitation studies that omentum-derived cells did not synthesize and secrete vWF, indicating the nonendothelial nature of these cells. Finally, electron microscopy demonstrated microvilli on the surface of cultivated omentum-derived cells indicative for the mesothelial origin of these cells. The data presented demonstrate that the cells obtained using the previously published methods for the isolation and cultivation of "microvascular endothelial cells" from omental tissue are of mesothelial and not of endothelial origin. Thus, a great number of data obtained with this type of omentum-derived cells thought to be microvascular endothelial cells need re-evaluation.

Antibodies, Monoclonal↗
PubMed1990

[Procedure for producing a resuspended erythrocyte concentrate during technical plasmapheresis: infrequent donation with the same erythrocyte concentrate quality].

This procedure enables gaining an additional red cell concentrate (RCC) during a plasmapheresis (Autopheresis C, Baxter) by using a 3-blood-bag system and the additive solution Sag-M. The quality of the RCC and the fresh frozen plasma (FFP) is equivalent to those prepared from whole blood. This method is adapted to the ambulatory autologous blood donation in cases when more FFP than RCC is needed.

Blood Coagulation Factors↗
PubMed1989

Identification of and partial characterization of platelet vitronectin: evidence for complex formation with platelet-derived plasminogen activator inhibitor-1.

Vitronectin (VN; = complement S-protein), a plasma glycoprotein that is also associated with extracellular sites, was identified in washed human platelets contaminated with less than 0.05% of plasma VN. A specific enzyme-linked immunosorbent assay (ELISA) for VN has been developed and was used to detect and to quantitate VN in detergent extracts of washed platelets with 8.1 +/- 4.6 micrograms/10(9) platelets (n = 10), representing about 0.8% of the plasma VN pool. Platelet and plasma VN were similar by immunochemical criteria using Western-blot analysis, although platelet VN was mainly found as partially proteolyzed polypeptide. Total release of platelet VN occurred at optimal doses of Ca-ionophore 23187 or thrombin, whereas no VN was released by platelet treatment with digitonin or Staphylococcus alpha-toxin. During stimulation of washed platelets with various concentrations of thrombin, the nearly concomitant release of VN and plasminogen activator inhibitor-1 (PAI-1) together with platelet factor 4 indicated the association of VN with inner-platelet storage granules. Furthermore, platelet VN and PAI-1 in Ca-ionophore releasates comigrated during ultracentrifugation in high mol wt fractions of sucrose density gradients, indicating a possible association of both components. Complex formation of platelet VN and PAI-1 was verified by a sensitive enzyme-linked immunosorbent assay (ELISA) and accounts at least in part for a high molecular form of platelet VN. The identification of platelet VN and its binding to platelet PAI-1 raises the possibility that VN, in contrast to other adhesive proteins, may participate in localized regulatory functions of blood coagulation and fibrinolysis in platelet-matrix interactions and the protection of the matrix against proteolysis.

Bacterial Toxins↗
PubMed1989

A novel beta-endorphin binding protein. Complement S protein (= vitronectin) exhibits specific non-opioid binding sites for beta-endorphin upon interaction with heparin or surfaces.

Human beta-endorphin (1-31) (beta H-endorphin) was found to specifically interact with purified complement S protein from human plasma. As found by chemical cross-linking beta H-endorphin bound to both, the 65- and 75-kDa molecular mass forms of S protein. The interaction of S protein with heparin as well as the adsorption of S protein to surfaces led to an almost 10-fold increase of specific binding which was due to the exposure of further beta H-endorphin-binding sites. The interaction of beta H-endorphin with S protein bore characteristics of a ligand-receptor interaction, such as time dependence, reversibility, high affinity, saturability, and structural specificity and was mediated through the non-opioid COOH terminus of the beta H-endorphin molecule. beta H-Endorphin binding to S protein was observed at physiological pH or cation concentrations, indicating that the interaction may well occur in vivo. Our results provide conclusive evidence that interactions of S protein with very different effectors led to similar conformational changes which uniformly resulted in exposure of a highly specific beta H-endorphin binding domain on S protein. With S protein as major beta H-endorphin-binding protein in the periphery, the molecular basis of a widespread system of humoral target sites of the neuroendocrine effector appears to be established. In view of S protein involvement in processes of inflammation and wound repair and beta-endorphin effects on immunocompetent cells, the demonstrated S protein-beta H-endorphin interaction appears to be of considerable functional significance.

Binding Sites↗
PubMed1989

Increased tissue-plasminogen activator (t-PA) levels in patients under oral anticoagulant therapy.

The fibrinolytic system was investigated in 30 patients under oral anticoagulant therapy, and in 23 control patients not receiving oral anticoagulants. Patients under oral anticoagulant therapy had significantly higher tissue-plasminogen activator (t-PA) antigen levels than patients in the control group. Mean t-PA levels before venous occlusion were 18.4 ng/ml in the anticoagulated patients vs. 7.9 ng/ml in the control patients (p less than 0.001). After venous occlusion for 10 minutes, t-PA levels were 45.0 ng/ml in the anticoagulated patients and 24.2 ng/ml in the control patients (p less than 0.01). Plasminogen activator inhibitor (PAI) capacity was not significantly different in the two groups before venous occlusion (VO) but differed slightly (p less than 0.05) after VO. The net decrease in euglobulin lysis time (ELT) after venous occlusion (= ELT before VO - ELT after VO), indicating the relative potency of the fibrinolytic activity in blood, was also significantly higher in the anticoagulated patients (median 240 min vs. 125 min, p less than 0.001). These data indicate that oral anticoagulant therapy increases the fibrinolytic activity in blood, and thus may have an additional therapeutic effect in addition to anticoagulation.

4-Hydroxycoumarins↗