摘要:

The effect of a collagen-derived octapeptide on some properties of thrombin is presented. This peptide provoked a dose- and time-dependent prolongation of the thrombin-induced plasma and fibrinogen clotting time and inhibited the polymerization of fibrin generated from fibrinogen by thrombin. It did not affect the polymerization of fibrin monomers; it was also without effect on the coagulation of plasma or fibrinogen by reptilase. The prolongation of the fibrinogen clotting time depended on the duration of the incubation of thrombin and the octapeptide and not on the duration of the incubation of fibrinogen and the octapeptide. The inhibition was therefore ascribed to an interference with thrombin, rather than with fibrinogen. A preincubation of the octapeptide with thrombin resulted in an inhibition of the thrombin-induced platelet aggregation. The effect of the octapeptide on thrombin has been related to the presence of positively and negatively charged groups, because uncharged analogue sequences were without effect on these activities of thrombin.

ISSN:1424-8832    

DOI:10.1159/000215162

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Onto ‘activating’ surfaces, intact normal plasma deposits an overlapping sequence of proteins, each being desorbed by the next. Ultimately, high molecular weight kininogen (HMK) is deposited unless contact was too short, or space between 2 surfaces too narrow. Thus, injected between a glass slide and a convex lens, intact plasma will leave a disk of HMK with a center of fibrinogen. We describe here how the exchange of proteins on the surface can be demonstrated by staining the adsorbate with a metal oxide suspension. Subsequent flooding of the preparation with more normal plasma causes lift-off of the oxide where underlying fibrinogen is being displaced by the HMK of the newly applied plasma. Kininogen-deficient plasma fails to remove any oxide, while normal plasma can remove nearly all of the oxide and adsorbate, left on glass by HMK-deficient pla

ISSN:1424-8832    

DOI:10.1159/000215163

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Thromboplastins which were highly (Thrombotest®) and slightly (Normotest®) sensitive to the Pivka (protein induced by vitamin K absence) inhibitor were selected in this study. The influence of the Pivka inhibitor increased with increasing sample size and decreasing packed cell volume; however, a satisfactory correction for the Pivka inhibitor was possible. The inhibitor explained the different coagulation activities in the various assays and also interfered with the ratio method of standardizatio

ISSN:1424-8832    

DOI:10.1159/000215164

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

An analysis of the one-stage prothrombin time using thromboplastins highly (Thrombotest®) and slightly (Normotest®) sensitive to the Pivka (protein induced by vitamin K absence) inhibitor is presented. A one-tenth dilution of blood with 0.1 mol/l Na3 citrate was satisfactory even at an extreme packed cell volume (PCV). Whole blood and plasma were equally satisfactory as test materials; however, their accuracy and precision were greatly improved when a small sample size at a high coagulation activity and a large sample size at a low coagulation activity were used. The PCV correction method which corrected for the different Pivka inhibitor sensitivities of thromboplastins was preferabl

ISSN:1424-8832    

DOI:10.1159/000215165

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Differences in the coagulation patterns between humans and dogs and the lack of reagents in the veterinary field to control haemostasis require a modification of existing screening techniques. The adaptations which were applied and which are described in this paper consist of greater dilutions of the samples. Two modified screening techniques in blood and plasma are described. The normal values of the different clotting factors and thrombokinetics, (thrombokinetogram, T.K.G.®), using a normal beagle pool as a reference, are presented

ISSN:1424-8832    

DOI:10.1159/000215166

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

A new low molecular weight heparin (LMWH) and a conventional unfraction-ated heparin (H) were tested in rats for venous antithrombotic activity and bleeding tendency after intravenous administration. Both drugs showed antithrombotic activity, but LMWH at the low dosages tested (0.1 and 0.25 mg/kg) demonstrated significantly higher activity than H. In a rat bleeding time test (transection model) both heparins produced a prolonged bleeding time, but LMWH possessed significantly less potency than H at all the dosages tested. Ex vivo coagulation parameters (activated partial thromboplastin time and antiXa activity) were also evaluated: LMWH presented very low activity on the APTT test and a sustained antiXa activity, comparable to that of H.

ISSN:1424-8832    

DOI:10.1159/000215167

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Since 1979, malonyldialdehyde (MDA) is considered a sensitive index of platelet hyperactivity. Stimulators of phospholipase A2 are used in the procedure of MDA production in order to obtain the final quantity (MDAa) which corresponds to the total amount of arachi-donic acid present; without stimulation the production of MDA is minimal in non-activated platelets (MDA non-activated). Therefore, the more the MDA/MDAa ratio approaches unity, the more activated are the thrombocytes. We utilized for the first time this new index for the investigation of hyperactive platelets, and we studied 56 persons (17 patients with thrombotic or thrombophilic disease as group A, 17 normals as group B and 22 diabetics without ketoacidosis as group C). We proved that the new index (MDA/MDAa) can be used to detect persons with functionally hyperactive platelets because large differences are found between the mean values of normals and the values of patients with established thrombotic disease, at a high confidence limit (x ± 3 SD covering 99% of the samples). Comparing the sensitivity of this new index with the other three methods used for the detection of hyperactive platelets [ratio of circulating platelet aggregates (CPA), aggregation with ADP, spontaneous aggregation] in groups B and C we found that only the ratio MDA/MDAa was able to reveal that (a) the two groups B and C are not identical (a statistical conclusion after comparison with the other methods) and (b) there were 5 diabetics in group C who had more hyperactive platelets than the others (these patients were not detected by any other method)

ISSN:1424-8832    

DOI:10.1159/000215168

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

In vivo platelet reactivity, expressed by plasma concentration of β-thromboglobulin (βTG) and platelet factor 4 (PF4), was determined in 57 patients with bioprosthetic heart valves: 35 had well-functioning bioprostheses (WFBP), while 22 had documented malfunctioning bioprostheses (MFBP). βTG and PF4 values in patients with WFBP were not significantly different from controls, even when these determinations were repeated at monthly intervals, whereas βTG and PF4 concentration was significantly higher in patients with MFBP compared to both groups. There was a strong positive correlation between βTG and PF4 in all subjects studied. Serum lactic dehydrogenase, indirect bilirubin level and reticulocyte count were significantly higher in patients with MFBP than in those with WFBP, but no correlation was found between platelet reactivity and rate of intravascular hemolysis. Our results suggest that there is an increased platelet release in vivo of the platelet-specific proteins in patients with MFBP not related to mechanical damage, and that bioprostheses, at least in a degenerative state, may represent a potential thrombogenic f

ISSN:1424-8832    

DOI:10.1159/000215169

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Postoperative changes related to coagulation and fibrinolysis and their correlation with the incidence of deep venous thrombosis (DVT) were studied in 30 patients undergoing total hip replacement. Pre- and postoperative measurements of fibrinogen, factor Xa, VIIl·C, VIΠR:Ag and its electrophoretic mobility, antifactor Xa activity, antithrombin III (AT III) and its electrophoretic mobility in plasma and serum, fibrin monomers, euglobulin lysis time, fibrinogen degradation products (FDP), α2-antiplasmin and plasmin-antiplasmin complexes were determined. DVT was detected by 125I-fibrinogen leg scanning in 11 patients. There was a significant and progressive increase in fibrinogen, VIII:C, VIIIR:Ag, fibrin monomers, FDP and α2-antiplasmin levels after operation and likewise a prolongation of euglobulin lysis time. There were changes in electrophoretic mobility of AT III in plasma and serum in 12 patients. The presence of plasmin-antiplasmin complexes was demonstrated in 9 patients. No correlation between the changes in coagulation and fibrinolysis and the incidence of postoperative DVT was found. We conclude that important changes occur in several parameters of coagulation and fibrinolysis after total hip replacement. Such changes are not related to the development of postoperative

ISSN:1424-8832    

DOI:10.1159/000215170

出版商:S. Karger AG    

年代:1985

数据来源: Karger

摘要:

Platelet aggregation in the lungs is common following abdominal surgery and may contribute to postoperative hypoxaemia. The hypothesis that an anabolic steroid, stanozolol, by preventing fibrinolytic shutdown, would prevent postoperative hypoxaemia was tested. Fifty patients undergoing abdominal surgery were randomly allocated to receive either placebo or stanozolol. Despite preventing fibrinolytic shutdown in most patients, the use of stanozolol did not influence the extent of postoperative hypoxaemia or the incidence of postoperative pulmonary complications. These results suggest that fibrinolysis does not play a significant part in the pathogenesis of postoperative pulmonary dysfunction.

ISSN:1424-8832    

DOI:10.1159/000215171

出版商:S. Karger AG    

年代:1985

数据来源: Karger