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T N Vlasik

Publications and source records attributed to T N Vlasik.

32 records · Page 2Linked to original sources
PubMed1993

[The use of monoclonal antibodies to lipid A for the correction of the hemodynamic disorders in endotoxemia].

Endotoxemia induced by gram-negative bacteria leads to endotoxic shock pathogenetically stemming from the integral component of the bacterial wall--lipid A. The study made to define the ability of lipid A monoclonal antibodies to correct hemodynamic disturbances due to endotoxemia in dog experiments showed the efficacy of the antibodies administration. ReLPS isolated from Salmonella Minnesota was used as an antigen. Administration of the complex monoclonal antibodies-endotoxin caused no hemodynamic impairment.

Animals↗
PubMed1993

Human very low density lipoprotein structure: interaction of the C apolipoproteins with apolipoprotein B-100.

Very low density lipoproteins (VLDL) are a heterogenous population of particles differing in size and composition. Heparin-Sepharose chromatography yields three VLDL subfractions. Two subfractions, VLDLNR-1 and VLDLNR-2, which are not retained by heparin, contain little or no detectable apolipoprotein (apo)E. According to negative stain electron microscopy, VLDLNR-1 is slightly larger than VLDLNR-2. The third fraction, VLDLR, is composed of smaller particles that are retained by the heparin-Sepharose and contain apoE. The C apolipoproteins of the respective VLDL subfractions transfer to 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC) single bilayer vesicles giving three subfractions designated VLDLNR-1-C, VLDLNR-2-C, and VLDLR-C. The protein, phospholipid, and cholesterol (free + esterified) contents decrease in the order VLDLR > VLDLNR-2 > VLDLNR-1. Triglyceride content decreases in the opposite order. POPC treatment of each VLDL subfraction increases the phospholipid and decreases the protein, triglyceride, and cholesteryl ester contents, while free cholesterol remains unchanged. According to immunological analysis of each subfraction with well-characterized monoclonal antibodies, the accessibility of some epitopes of apoB-100 on VLDL is changed by POPC treatment. Electron-microscopic analysis of POPC-treated VLDL subfraction reveals vacancies on the surfaces of each particle. VLDLNR-1, VLDLNR-2, and VLDLR are resistant to thrombin cleavage, whereas the lipoproteins lacking C apolipoproteins are not. Thrombin cleavage (8 h) of apoB-100 of VLDLNR-2-C and VLDLR-C gives two fragments, T1 and T2, that are converted to smaller fragments only after prolonged treatment. In contrast, apoB-100 of VLDLNR-1-C is converted into small fragments after 8 h thrombin treatment. These results suggest that removal of apoCs affects the accessibility and conformation of apoB-100 in the individual VLDL subfractions in the region near residue 3249, which is the primary thrombin cleavage site and the epitope of monoclonal antibody 4C11.

Apolipoprotein B-100↗
PubMed1991

A monoclonal antibody, VM64, reacts with a 130 kDa glycoprotein common to platelets and endothelial cells: heterogeneity in antibody binding to human aortic endothelial cells.

A new monoclonal antibody (mAb), VM64, reacts with a common antigen on the surface of human platelets and vascular endothelial cells (EC). Under nonreduced conditions it recognized in immunoblotting a protein of 130 kDa both in platelets and EC. VM64 precipitated the same 130 kDa protein from the lysate of surface radioiodinated platelets. Electrophoretic mobility of this protein was not altered by reduction and differed from the bands precipitated by reference mAb against platelet glycoproteins (GP) Ia-IIa, Ib, IIb-IIIa and GMP130. VM64 binding to platelets and EC was specific and saturable. The number of binding sites on platelets was 9.9 +/- 3.5 x 10(3) per platelet and on the surface of EC monolayer -2.40 +/- 0.32 x 10(6) per cell. VM64 also binds to platelets from Glanzmann's thrombasthenia patients which lack GPIIb-IIIa. VM64 did not affect platelet aggregation induced by ADP, collagen, thrombin and ristocetin. In the monolayers of EC from umbilical vein and human aorta, VM64 stained the area at the periphery of the cells adjacent to the cell-cell boundaries. In preconfluent cultures preferential staining was observed at the active leading margins of the cells. Unlike EC cultures from umbilical vein, where all cells were positively stained, in aortic EC cultures some unstained or poorly stained cells were constantly present, indicating a heterogeneity of EC population related to the expression of VM64 antigen. The biochemical characteristics of VM64 antigen, its presence both on platelets and EC and typical distribution on the surface of EC suggested that this antigen is identical to PECAM (CD31) protein.

Antibodies, Monoclonal↗
PubMed1991

Characterization of an antiglycoprotein Ib monoclonal antibody that specifically inhibits platelet-thrombin interaction.

Platelet glycoprotein Ib (GPIb) acts as a high-affinity thrombin binding site and as a receptor for von Willebrand Factor (vWF). A new anti-GPIb monoclonal antibody (mAB) VM16d was produced that specifically inhibited platelet-thrombin but not platelet-vWF interaction. The epitope for VM16d was located within the 45 kDa N-terminal region of the alpha-chain of GPIb. VM16d inhibited platelet aggregation induced by low dose thrombin (0.05 U/ml) but did not affect platelet aggregation induced by ristocetin, bovine vWF, ADP or collagen. The same inhibitory effects on thrombin-induced platelet aggregation were observed with the whole IgG molecule of VM16d and its F(ab')2 and F(ab') fragments. VM16d also inhibited 14C-serotonin secretion induced by low dose thrombin and binding of 125I-thrombin but not ristocetin-dependent binding of 125I-vWF to platelets. These data indicate that the high-affinity thrombin binding site is located on the N-terminal 45 kDa domain of GPIb and that it is topographically separated from the vWF binding site.

Adenosine Diphosphate↗
PubMed1991

[Inhibition of Fc-receptor dependent platelet aggregation by monoclonal antibodies against the glycoprotein IIb-IIIa complex].

A murine monoclonal antibody (MoAb) VM16a specifically binding to human platelets has been produced. Approximately 56,000 molecules of VM16a bound per platelet at saturation (Kd = 7.9 nM) but no binding to platelets from Glanzmann's thrombasthenia patients was detected. VM16a precipitated two proteins with molecular masses corresponding to those of glycoproteins (GP) IIb and IIIa from solubilized surface-labelled platelets. However, after dissociation of the GPIIb--IIIa complex with EDTA VM16a did not bind to platelets and precipitated nothing from their lysate, thus evidencing that its determinant is complex-dependent. VM16a had no effect on ADP-, thrombin- and ristocetin-induced platelet aggregation but inhibited the aggregation induced by collagen. This inhibitory effect was more pronounced in the presence of plasma. VM16a completely blocked the Fc-receptor-mediated aggregation induced by aggregated human IgG, aggregated murine IgG1 and the previously described MoAb VM58. F(ab')2 fragments of VM16a were also able to inhibit this aggregation by decreasing the rate of aggregation induced by aggregated IgG and by extending the lag phase of VM58-induced aggregation. These results suggest that the platelet Fc-receptor may be topographically associated with the GPIIb-IIIa complex.

Adenosine Diphosphate↗
PubMed1990

Visualization of apo B, fibrinogen/fibrin, and fibronectin in the intima of normal human aorta and large arteries and during atherosclerosis.

Apolipoprotein B (apo B), fibrinogen/fibrin, blood platelets, factor VIII-related antigen of the blood coagulation system, and smooth muscle cells (SMC) were identified in the intima of normal and atherosclerotic human aorta and large arteries by the indirect immunofluorescence technique. Fibrinogen/fibrin was revealed by a monoclonal antibody (monAb) against the C-terminal region of human fibrinogen A alpha-chain. Fibronectin was visualized by monAb to the cellular form and against an epitope shared by different fibronectin subunit variants. In normal intima, fatty streaks, small amounts of fibrinogen/fibrin together with large amounts of apo B were observed. Fibronectin detected by two types of monAb was not found in extracellular matrix (ECM), whereas cellular fibronectin encircled SMC. According to the data obtained, fibrinogen/fibrin accumulates in plaques as a result of intramural thrombus incorporation, blood insudation, intramural haemorrhage, and in or around cells, apparently macrophages.

Aged↗
PubMed1983

[Distribution of elongation factors EF-1 and EF-2 among components of rabbit reticulocyte lysate].

The distribution of activity of the elongation factors EF-1 and EF-2 among the components of rabbit reticulocyte lysate separated by sucrose density gradient centrifugation was studied. At low ionic strength (0.01 M KCl) about 30% of the EF-1 activity was found in polyribosomes. At moderate ionic strength (0.1 M KCl) the EF-1 activity was absent in the polyribosomes. An addition of RNA excess to the lysate prior to centrifugation at low ionic strength resulted in elimination of the EF-1 activity from the polyribosomes. This indicates that EF-1 is reversibly bound to the polyribosomes and that EF-1 may be retained on them due to interaction with RNA of polysomes mediated by its RNA-binding site. After dissociation of polyribosomes containing EF-1 in the presence of EDTA and subsequent fractionation of the dissociation products at low ionic strength (0.01 M KCl) the EF-1 activity was revealed in the ribosomal subparticles (predominantly in 60S). At 0.1 M KCl EF-1 mainly sedimented in the zone of distribution of polyribosomal informosomes. The elongation factor EF-2 was not revealed in polyribosomes during lysate centrifugation even at low ionic strength which corresponds to its lower affinity for RNA.

Animals↗
PubMedDate not supplied

[Expression patterns of the human and mouse IFGP family genes].

The IFGP family is a recently identified group of human and mouse genes structurally related to the genes of leukocyte Fc-receptors. In this study we compared expression patterns of six human and four mouse IFGP genes. With the exception of mouse IFGP2, the genes of the family were found to be predominantly expressed in haemopoietic cells. Expression of human IFGP1-IFGP5 and mouse IFGP3 was B cell-specific. Mouse IFGP1 transcripts were mainly found in B cells, but this gene may be either expressed by nonlymphoid cells. Expression of the human IFGP6 was detected in CD8+ T cells and NK cells. We further demonstrated that alternative splicing of human IFGP1 and IFGP6 mRNA may generate transcripts coding for the previously unknown isoforms. The novel IFGP1 isoform lacks transmembrane domain, whereas the IFGP6 isoform has altered cytoplasmic tail. The data obtained indicate that the receptors of family may contribute to the regulation of development and/or functions of three effector types of lymphocytes, namely B cells, CD8 T cells and NK cells.

Alternative Splicing↗