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Biomedical subjects

M Kopeć

Publications and source records attributed to M Kopeć.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effect of proteolysis on quantitation of plasma fibronectin concentration by two immunoassays (electroimmunoassay and immunoturbidimetric technique).

Quantitation of fibronectin (FN) concentration is strongly influenced by FN fragmentation with trypsin, kallikrein and plasmin. Digestion by trypsin and kallikrein leads to a progressive decline in FN detectability by the immunoturbidimetric technique to zero values but is associated with an increase in the height of rockets in the Laurell's electroimmunoassay. Plasmin mediated FN fragmentation induces a strong overestimation of the FN content by the electroimmunoassay and, at very high enzyme concentrations, provokes an underestimation of FN by the immunoturbidimetric technique. The decline in FN reactivity in the immunoturbidimetric assay coincides with the disappearance of heavy fractions migrating only slightly faster than native FN in SDS-PAGE. The increase in the height of rockets in the electroimmunoassay is the highest when fractions of intermediate rate of migration prevail in the SDS-PAGE pattern. Concomitant use of these two immunoassays can distinguish native FN from its degraded form and may possibly provide a partial explanation for discrepancies in published studies on the concentration of circulating FN in various pathological states.

Antibodies↗
PubMed1985

Alterations of blood platelet function induced by neutral proteases from human leukocytes.

Washed human platelets are damaged by two neutral proteases from human leukocytes (elastase-like protease, ELP and chymotrypsin-like protease, CLP). The damage is manifested as inhibited aggregation by ristocetin and collagen, and enhanced aggregation by ADP in the presence of fibrinogen. Similarly to alpha-chymotrypsin (alpha-CT), CLP also increases binding of 125I-fibrinogen to platelets and renders platelets aggregable by human fibrinogen. ELP is less effective in this respect possibly due to damage to platelet receptors for fibrinogen. In the plasma medium platelets are not sensitive to leukocytic proteases added at concentrations that provoke some prolongation of the time of plasma clotting by thrombin.

Adenosine Diphosphate↗
PubMed1985

On the retraction of collagen and fibrin induced by normal, defective and modified platelets.

Fibrin clot retraction (FCR) and collagen gel retraction (CGR) were studied in patients with inherited platelet defects, i.e. in Glanzmann's thrombasthenia, Hermansky-Pudlak syndrome, May-Hegglin anomaly, giant platelet syndrome, as well as in patients with von Willebrand disease and factor XIII deficiency. FCR was abnormal only in thrombasthenia, while CGR was found to be reduced in 2 patients with Hermansky-Pudlak syndrome and in 4 out of 5 cases with von Willebrand disease. Both FCR and CGR were normal in May-Hegglin anomaly, giant platelet syndrome and severe factor XIII deficiency. In none of the examined bleeding disorders was a concomitant FCR and CGR reduction detected. Natural polyamines and anti-fibronectin antibodies did not affect platelet potency in FCR or CGR. Peroxidation of platelet membrane components by sodium periodate abolished the platelet-induced FCR and CGR. This effect was reversed by subsequent reduction by sodium borohydride.

Adolescent↗
PubMed1985

Suppression of cell-mediated immune reactivity by peptides cleaved from human fibrinogen.

Peptides derived from fibrinogen, known from earlier studies to inhibit the stimulation of lymphocytes in vitro and to suppress the humoral immune response in vivo, were investigated for their effect on cell-mediated immune reactivity in mice. An unfractioned mixture of peptides with molecular weights under 3,500 injected intraperitoneally at repeated intervals suppressed the contact hypersensitivity to oxazolone but did not influence the skin inflammatory reaction to croton oil. Local injections of peptides had a stronger effect on contact hypersensitivity. Four 200 micrograms local injections of peptides prior to sensitization abolished the increase in lymph node weight and the uptake of 125I-iododeoxyuridine in the draining lymph node after sensitization. Three previously isolated peptides with vasoactive effects inhibited Con A-stimulated incorporation of 3H-thymidine into spleen cells. The first, a pentapeptide (Ala-Arg-Pro-Ala-Lys), and the second, an undecapeptide (Ser-Glu-Leu-Gln-Lys-Val-Pro-Pro-Glu-Trp-Lys) both with an enhancing effect on microvascular permeability, were more potent than the third, a pentapeptide with slight vasoconstrictive properties (Thr-Ser-Glu-Val-Lys). Cell viability was not altered, as measured by trypan blue exclusion and the release of 86Rb. Accumulating evidence indicates that peptides derived from fibrin may be of importance as modulators of cellular immunoreactivity in a number of clinical conditions.

Animals↗
PubMed1984

Effects of neutral proteases from human leukocytes on plasma fibronectin.

Human plasma fibronectin (FN) is not susceptible to collagenase and gelatinase from human blood leukocytes. Leukocytic elastolytic protease (ELP) and cathepsin G (chymotrypsin-like protease, CLP) degrade FN to similar fragments. Among products of proteolysis by ELP and CLP fragments have been identified which bind to gelatin-fragment 40 kd, to fibrin-fragments 55 kd and 30 kd, and to heparin-fragment 30 kd.

Endopeptidases↗
PubMed1983

Effect of neutral proteases from blood leukocytes on human platelets.

Two highly purified neutral proteases from human leukocytes i.e. elastase-like protease (ELP) and chymotrypsin-like protease (CLP) do not destroy human platelets since no difference was found in 51Cr liberation from control and enzyme-treated platelets. As with pancreatic chymotrypsin (alpha-CT) ELP does not induce the release of 3H-serotonin while CLP provokes 3H-serotonin secretion, in an enzyme concentration and time dependent fashion. The rate and degree of 3H-serotonin release by CLP is similar to that produced by thrombin. Incubation of platelets at 37 degrees C for 30 min with alpha-CT or ELP renders them resistant to thrombin-releasing activity. Thrombin did not liberate any additional label from platelets which lost over 60% of serotonin during the preceding incubation with CLP. alpha-CT and ELP do not aggregate platelets either in the presence or absence of apyrase. CLP does aggregate platelets suspended in Tyrode buffer without apyrase but not in the presence of apyrase (100 mg/l). The action of alpha-CT, ELP and CLP on washed platelets induces a progressive prolongation of lag phase and a decrease in changes of light transmission during aggregation by thrombin. Similarly to alpha-CT-treated platelets, those subjected to CLP action aggregate in the presence of human fibrinogen. It is concluded that: (1) neutral proteases possibly contribute to development of defects in platelet function in pathological states associated with liberation of leukocyte content into the circulation, (2) CLP similarly to alpha-CT, exposes fibrinogen receptors but in contrast to alpha-CT, CLP aggregates platelets and stimulates serotonin secretion.

Blood Platelets↗
PubMed1983

Platelet-mediated collagen and fibrin retraction: effect of prostaglandins, cyclic AMP, calcium antagonists and N-ethylmaleimide.

Collagen gel retraction (CGR) and thrombin-induced fibrin clot retraction (FCR) could be abolished by EGTA and EDTA, trifluoperazine - a calmodulin inhibitor - and by NEM. Both processes appeared insensitive to hydrocortisone (up to 100 microM), indomethacin (up to 60 microM), PGI2 and its stable analogue 6-keto-PGE1 alpha (10 microM). A slight inhibitory effect on both CGR and FCR was provoked by dibutyryl-cAMP and PGD2. PGE1 1 microM strongly inhibited CGR and FCR. Possible interference of the inhibitors with anchorage of collagen and fibrin on platelet surface and with platelet contractile system is discussed.

Blood Platelets↗
PubMed1983

Effects of peptides cleaved from human fibrinogen by plasmin on rabbit kidney cells in culture.

Low molecular weight fibrinogen degradation products (LMW-FDP) containing a mixture of dialysable peptides cleaved from human fibrinogen by plasmin are cytotoxic to an established line of rabbit kidney cells and to primary cultures of rabbit kidney cells. The presence of LMW-FDP in a concentration of 50 micrograms/ml during the cell cultivation caused a considerable release of 51Cr from prelabelled cells and inhibited 3H-thymidine and 86Rb uptake. Among three isolated peptides of established primary structure only one, 6D: Ser-Gln-Leu-Gln-Lys-Val-Pro-Pro-Glu-Trp-Lys, induced a significant effect, i.e. it enhanced 3H-thymidine incorporation. Two others, 6A: Ala-Arg-Pro-Ala-Lys and 6E: Thr-Ser-Glu-Val-Lys, did not influence the examined parameters. Hence other components of LMW-FDP must be assumed to be responsible for the cytotoxic effect on kidney cell cultures.

Animals↗
PubMed1980

Blood platelets cause retraction of collagen gel.

Human blood platelets cause the collagen gel retraction (CGR) with concomitant exclusion of fluid. CGR is positively related to the number of incorporated platelets and inversely to collagen concentration. Disruption of platelets, EDTA and cytochalasin B inhibit CGR. Platelets from patients with Glanzmann's thrombasthenia are active in CGR. The similarities and differences of CGR and fibrin retraction are discussed.

Adult↗
PubMed1980

The comparative ability of plasma and tissue transglutaminases to use collagen as a substrate.

Heat denatured type I and type III calf skin collagen were found to be substrates for guinea pig liver transglutaminase (R-glutaminyl-peptide:amine gamma-glutamyl-yltransferase, EC 2.3.2.13) but not for active plasma factor XIII (factor XIIIa). Liver transglutaminase was shown to catalyse incorporation of 14C-putrescine into subunits of denatured collagen of both types, cross-linking of the latter into high molecular weight polymers and their co-cross-linking to fibrin and fibrinogen. Factor XIIIa is inactive in these respects. None of these reactions was catalysed by liver transglutaminase and plasma factor XIIIa when nondenatured collagens both soluble or in the forms of reconstituted fibrils served as substrates. Some cross-linking of cleavage products of collagen type I (obtained by treatment with collagenase from human neutrophiles) was induced by liver transglutaminase and factor XIIIa. The results indicate that although appropriate glutamine and lysine residues for a epsilon-(gamma-glutamine) lysine cross-linked formation are present in collagen, the native conformation of collagen prevents the action of liver transglutaminase and factor XIIIa.

Animals↗
PubMed1980

Effects of neutral proteases from human leukocytes on structure and biological properties of human factor VIII.

Human factor VIII was purified from cryoprecipitate and incubated for up to 24 hours with four neutral proteases of human blood leukocytes, namely, with elastase-like protease (ELP), chymotrypsin-like protease (CLP), collagenase and gelatinase. Electrophoretic patterns showed a reproducible sequence of degradation of factor VIII and of its 230,000 molecular weight subunit by ELP and CLP. Intermediate products were similar but those resulting from exhaustive proteolysis by ELP and CLP differed distinctly from each other. Procoagulant activity of factor VIII was rapidly and completely destroyed by ELP and CLP before visible electrophoretic changes would be detected. No increase in this activity was observed prior to its destruction. Von Willebrand factor (ristocetin cofactor) activity was considerably more resistant to ELP and CLP and declined in rough relation to degradation of highly aggregated forms of factor VIII. ELP and CLP produced a pronounced progressive increase in the Laurell reaction antigen. Normal human plasma showed a high potency to inhibit ELP and CLP. Large doses of these enzymes (300 microgram per ml) produced in the plasma medium only a moderate fall in factor VIII procoagulant activity. Collagenase and gelatinase did neither degrade factor VIII nor change its biological properties.

Electrophoresis, Polyacrylamide Gel↗
PubMed1978

[Fibrin deposits and fibrinolysis in pre and early stages of arteriosclerosis].

Already in the early stages of atherosclerosis still before the appearance of coarsely visible changes subendothelially fibrin-like material is found in the places of predilection known, which reveals electron-microscopically the typical periodicity. Lesions of the endothelium with increase of permeability, release of coagulation factors and mitogenic substances which stimulate the proliferation of smooth muscle cells always precede. There are several mechanisms for the penetration of fibrinogen or fibrin into the vascular wall, the proportion of which changes with the progressing of the atherosclerosis. They are discussed in detail. Mechanisms of fibrinolysis, in which plasmin or activators of plasmin occupy a key position, effect against this process. By histochemical estimation of this activator the fibrinolytical potential of the vascular system can be investigated under various clinical conditions. For this a series of instances is cited.

Arteriosclerosis↗