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Biomedical subjects

L Muszbek

Publications and source records attributed to L Muszbek.

At least 73 records · Page 4Linked to original sources
PubMed1987

Association of vinculin to the platelet cytoskeleton during thrombin-induced aggregation.

Vinculin is a protein generally believed to be involved in membrane-cytoskeleton interaction, and its presence in platelets has been verified earlier. Here we show that in resting bovine platelets, vinculin is not associated with the Triton-insoluble cytoskeletal fraction but becomes incorporated into it during the thrombin-induced activation process. The incorporation starts around the same time as the release reaction and only after the shape change and the first phase of aggregation have taken place. Its time course parallels the cytoskeletal association of actin and certain other contractile proteins. Vinculin is a minor component of platelet cytoskeleton and only about 10% of the total platelet vinculin becomes incorporated into the Triton X-100 residue.

Animals↗
PubMed1987

Identification of smooth muscle-derived foam cells in the atherosclerotic plaque of human aorta with monoclonal antibody IIG10.

We have developed a monoclonal antibody that specifically interacts with a surface antigen of human fibroblasts and smooth muscle cells. The antibody (antibody IIG10) recognizes a polypeptide of molecular mass 330,000, revealed by immunoblotting in fibroblast and smooth muscle cell extract, but not in vascular endothelial cells, peritoneal macrophages, peripheral blood lymphocytes nor hepatocytes. In tissue sections the antibody stained smooth muscle cells of myometrium, aorta and smaller blood vessels, and fibroblasts of connective tissue. Specificity of the antibody was further confirmed by double staining of aorta sections. Antibody IIG10 was used to identify smooth muscle-derived foam cells in the atherosclerotic plaque of human aorta.

Antibodies, Monoclonal↗
PubMed1987

Characterization of factor XIII containing-macrophages in lymph nodes with Hodgkin's disease.

A large number of cells containing subunit a of blood coagulation Factor XIII (FXIII) was detected by immunoperoxidase staining in lymph nodes with Hodgkin's disease. These relatively large, multipolar, mononuclear cells were often found in the immediate vicinity of malignant Hodgkin's cells. Intensive characterization of these cells carried out by immunofluorescent and enzymecytochemical techniques in double- and triple-labelling systems on the same sections clearly demonstrated that they represent tumour-associated macrophages (TAMs). FXIII containing-cells showed alpha-naphtyl acetate esterase (ANAE) positivity, and were labelled by monoclonal anti-Leu M3 antibody, a monocyte/macrophage marker, but not at all or only very weakly by anti-HLA-DR. Neither alkaline phosphatase (ALP) nor adenosine triphosphatase (ATPase) activity could be detected in these cells and surprisingly, they were consistently negative for acid phosphatase (AcP) as well. The presence of FXIII subunit a in tumour-associated macrophages suggests that this cell type might have an important role in the stabilization of fibrin deposits around tumour cells.

Factor XIII↗
PubMed1987

Factor XIII: a marker of mono- and megakaryocytopoiesis.

Previous studies have shown that human platelets, megakaryocytes and peripheral blood monocytes contain the subunit a of plasma factor XIII (FXIII) which plays a key role in fibrin stabilization. To study the expression of FXIII subunit a during differentiation of the mono- and megakaryocytic cell lines, bone marrow smears were examined by immunomorphological methods. In addition to megakaryocytes, FXIII was detected in a large number of cells by a highly sensitive immunoperoxidase staining. Characterization of these cells was carried out by double immunofluorescent labelling in which the detection of FXIII subunit a was combined by the labelling of either Leu M3 monocyte/macrophage surface antigen or platelet factor 4 (PF4) a marker for megakaryocytic cells. On the course of differentiation from early precursors to mature megakaryocytes all phenotypic form of the megakaryocytic cell line expressed FXIII subunit a though there were considerable changes in its subcellular distribution pattern. Leu M3 positive cells of monocytopoiesis, i.e. monocytes and promonocytes and in all probability monoblasts as well, were also labelled for FXIII. On this basis FXIII subunit a could be considered as a common marker of megakaryo- and monocytopoiesis and its immunomorphological detection might provide a useful diagnostic tool for identifying normal and perhaps also malignant differentiation forms of these cell lines.

Bone Marrow Cells↗
PubMed1986

Transglutaminase-sensitive glutamine residues of human plasma fibronectin revealed by studying its proteolytic fragments.

The sites of transglutamination of fibronectin and fibronectin fragments, by coagulation factor XIIIa and tissue transglutaminase, were studied. It was shown that the intact fibronectin molecule has two sites sensitive to coagulation factor XIIIa and four sites sensitive to tissue transglutaminase: 180--190-kDa gelatin/heparin-binding fragments, 2 and 5--6 sites; 29-kDa heparin-I/fibrin-I-binding N-terminal fragments, 1 and 2 sites; 70-kDa gelatin-binding fragments, 0 and 1 site; 60-kDa cell-binding central fragments, 1 and 3--4 sites; 60-kDa, 45-kDa, 30-kDa heparin-II-binding C-terminal fragments, 1 and 2 sites. Thus, we have found a new coagulation-factor-XIIIa-sensitive site localized in the cell-binding central fragment, inaccessible to enzyme in the intact fibronectin molecule. Tissue transglutaminase appeared to interact with all of the three coagulation-factor-XIIIa-sensitive sites and, in addition, some others which are either available on the intact molecule or can be revealed only in proteolytic fragments of the fibronectin. We suggest that interdomain and intersubunit interactions in the intact fibronectin molecule account for the masking of glutamine residues potentially accessible to transglutaminases.

Binding Sites↗
PubMed1986

Identification of histiocytic reticulum cells by the immunohistochemical demonstration of factor XIII (F-XIIIa) in human lymph nodes.

Morphologically and enzyme histochemically distinguishable tissue macrophages and stromal cells of human reactive lymph nodes were characterized by the cytoplasmic presence of the subunit A of factor XIII and by the expression of surface antigenic determinants reacting with monoclonal antibodies directed against monocyte/macrophage populations (Mo 1, Leu M3) and HLA-DR antigens. The distribution of F-XIIIa positive cells was studied on formaldehyde-fixed paraffin-embedded sections with immunoperoxidase techniques. established on cryostat section with double immunofluorescence. Alpha-Naphthyl acetate esterase (ANAE) reaction was The immunophenotype was established on cryostat sections with double immunofluorescence. Alpha-Naphthyl acetate esterase (ANAE) reaction was carried out on these cryostat sections to identify tissue macrophages. The antibody against F-XIIIa detected histiocytes in both intra- and extra-sinusoidal locations which were ANAE+, Mo 1+, Leu M3+ and HLA-DR-. F-XIIIa was also present in fibroblast-like mesenchymal cells with the following phenotypic characteristics: ANAE-, Mo 1+, Leu M3+ and HLA-DR+. The anti F-XIIIa antibody did not stain lymphoid cells, granulocytes, epithelial cells, endothelial cells and mast cells. The immunohistochemical detection of F-XIIIa works on formaldehyde-fixed paraffin-embedded sections. The most promising application seems to be the identification of histiocytes in lymphoid and histiocytic proliferations.

Antigens, Surface↗
PubMed1985

Factor XIII of blood coagulation in human monocytes.

The presence of Factor XIII subunit a was demonstrated in human monocytes by immunoperoxidase staining using specific antisera against Factor XIII and its subunits. This finding was verified by immunobiochemical techniques, as well. In an immunoblotting system after SDS polyacrylamide gel electrophoresis of denatured monocyte homogenate a protein band comigrating with Factor XIII subunit a showed positive reaction with antibodies against this subunit or whole Factor XIII. In contrast, no subunit b of Factor XIII could be detected by either of these methods in monocytes. Activity measurements were carried out by the dansylcadaverine incorporation assay in the absence and presence of anti-Factor XIII antibody with and without thrombin activation. The expression of transglutaminase activity required thrombin and was completely abolished in presence of anti- Factor XIII antibody, which clearly indicate that practically all the transglutaminase activity measured in monocytes comes from Factor XIII. Factor XIII of monocytes and macrophages might have a role in formation of focal fibrin thrombi as well as in organization of stable, fibrinolysis resistant fibrin clot at the site of inflammation or around tumor cells.

Acyltransferases↗
PubMed1985

Kinetic determination of blood coagulation Factor XIII in plasma.

We have designed a new kinetic assay for estimating Factor XIII in plasma. Plasma fibrinogen is removed by treatment with bentonite (colloidal aluminum silicate) before measurement. During the lag phase, Factor XIII is transformed by thrombin and Ca2+ into active transglutaminase (EC 2.3.2.13), which attaches the substrate ethylamine to a glutamine residue in acetylated, dephosphorylated beta-casein. During the reaction, ammonia is released, which can be continuously monitored in an NADPH-dependent indicator reaction catalyzed by glutamate dehydrogenase (EC 1.4.1.4). We determined the optimal concentrations of substrate and activator and found that, to eliminate the clottable fibrinogen from the plasma samples, bentonite treatment was more advantageous than the traditional heat treatment. Results by the method correlate well with those by the most widely used amine incorporation and immunoinhibition assays for Factor XIII. We established a reference interval of 12.1-22.7 U/L; at optimal conditions, the variance of the method was less than 3% within this range. The method has several theoretical and practical advantages over traditional determinations of Factor XIII.

Ammonia↗
PubMed1984

Identification and isolation of vinculin from platelets.

A vinculin-like protein was identified in chicken as well as in bovine platelets by ELISA competitive binding assay using antibodies against vinculin from chicken gizzard. By a modified procedure (J. Biol. Chem. (1980) 255, 1194-1199) we succeeded in isolating bovine platelet vinculin to apparent homogeneity. The structural identity of platelet and chicken gizzard vinculin was demonstrated by circular dichroism analysis. It was also shown that platelet vinculin induces a significant decrease in the low shear viscosity of F-actin. Vinculin, in all probability, plays an important role in the organization of actin filaments in platelets, especially in the linkages of microfilaments to the membrane.

Actins↗
PubMed1981

Effect of prostaglandin I2 on platelet adhesion.

The adherence of platelets to collagen fibrils was not affected by prostaglandin I2 (PGI2) applied in a wide concentration range (0.1-100 ng/ml). The retention of platelets on glass beads which includes adhesion as well as subsequent clumping of platelets was, however, greatly reduced at PGI2 concentrations higher than 0.5 ng/ml. The results suggest that PGI2 even at high concentration does not interfere with the primary process of platelet adhesion, i.e., with the formation of a monocellular platelet layer on collagen fibrils and artificial surfaces, but it inhibits clumping of further platelets to this layer and prevents subsequent platelet thrombus formation.

Collagen↗
PubMed1980

Inhibition of platelet factor 3 availability by prostacyclin.

Preincubation of human platelet rich plasma with PGI2 in a concentration preventing collagen induced platelet aggregation abolished also platelet factor 3 availability brought about by collagen. Following PGI2 pretreatment no second wave aggregation could be elicited by ristocetin. However, primary aggregation as well as platelet factor 3 activity were only partially inhibited in this case and the inhibitory action of PGI2 was not increased by raising its concentration. Similarly, marked but not complete inhibition of platelet factor 3 availability was obtained when kaolin was used as activating agent.

Blood Coagulation Factors↗
PubMed1979

Fragmentation of actin by thrombin-like snake venom proteases.

The effect of thrombin-like snake venom proteases (Ancrod of Agkistrodon rhodostoma and Batroxobins of Bothrops moojeni and Bothrops marajoensis) on skeletal muscle actin was studied and compared to the thrombic cleavage of this protein. Only EDTA-pretreated G- and F-actin were split by thrombin and Ancrod, while Batroxobins hydrolyzed native G-actin, too. The time course of digestion was followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. A split product of 37 500 daltons appeared first which was cleaved further resulting in three lower molecular weight fragments. The sodium dodecyl sulfate gel pattern of thrombic fragmentation was well distinguishable from those caused by Ancrod and Batroxobins. The first split products of Batroxobin digestion--a smaller peptide and the 37 500 dalton fragment--were isolated and by estimating their N-, and C-terminal end groups and amino acid compositions the peptide bond hydrolyzed first was located in the primary structure of actin. It was established that while thrombin split off two actino-peptides (at Arg(28)-Ala(29) and Arg(39)-His(40) from the N-terminal end of the molecule only Arg(39)-His(40) was cleaved by Batroxobins.

Actins↗