摘要:

Procoagulant activity of the endothelium and of monocytes was induced by an intravenous administration of a low dose of endotoxin in the rabbit. Venous thrombosis induced by a 45-min stasis of the jugular vein was dramatically increased after the administration of endotoxin. Endotoxin enhanced venous thrombosis in a dose-dependent manner which was the highest after the administration of 1 µg/kg. This effect increased with time but was optimal when endotoxin was injected 4 h before stasis induction. Leukocytes appear to play a key role in this process since mechlorethamine-induced leukopenia totally inhibited thrombus formation. Hirudin and heparin, administered intravenously 5 min before stasis, were both potent inhibitors of endotoxin-induced venous thrombosis exhibiting ED50 values of 3.8 ± 1.0 and 2.3 ± 1.1 µg/kg, respectiv

ISSN:1424-8832    

DOI:10.1159/000217104

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

We have developed an automated image analysis method which provides en face morphometric evaluation of platelet interactions with coverslips coated with extracellular matrices. This procedure gives also additional information on the intensity of platelet-surface interactions in the same specimens. To standardize the method, anticoagulated human blood was flowed at 800 s-1 during 10 min at 37°C through a parallel perfusion chamber in which extracellular matrix (ECM)-coated coverslips were placed. The sensitivity of the new method was tested in similar studies performed in patients with von Willebrand disease or treated with aspirin (500 mg/ day). The extent of platelet deposition on the ECMs was evaluated by both standard and new morphometric procedures. Coverslips were successively embedded in resin and processed for cross-sectional analysis and results were compared with those provided by the new automated procedure. A good correlation was found between results of covered surface obtained by both methods (r = 0.86; p < 0.005). Results from perfusions performed with blood from patients with platelet defects confirmed the correspondence of grey levels in the digitized images with the heights of groups of interacting platelets calculated from cross sections. The new automated method, in only one stage, allows a reliable evaluation of the global interaction of platelets with the ECM and effectively detected qualitative modifications in platelet-platelet interactions in patients with known platelet defects. The method described could be applied to the evaluation of the interactions of platelets with purified components of the subendothelium

ISSN:1424-8832    

DOI:10.1159/000217105

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Storage of single-donor platelet concentrates is currently limited to 5 days. During this period, however, numerous morphologic and biochemical changes have been observed. These changes result in functional impairment of stored platelets. The present study describes increased binding of a monoclonal antibody against GMP 140 on the surface of stored single-donor platelets revealing an activation process. In contrast, binding of monoclonal antibodies directed against glycoprotein complex (GP) IIb-IIIa and ligand-induced binding site (LIBS1) is slightly diminished during storage. When platelets are stimulated with ADP GMP 140, GP IIb-IIIa, and LIBS1 are expressed to a higher extent than on the surface on non-stimulated platelets. The quantity exposed, however, depends upon the storage time. It is significantly reduced when platelets are stored for longer than 1-2 days. The present data indicate that storage of single-donor platelet concentrates affects fibrinogen binding, cell to cell cohesion, and release reaction. The results are in good agreement with conventional aggregation and in vitro bleeding time measurements.

ISSN:1424-8832    

DOI:10.1159/000217106

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

The effects of water immersion restraint stress on collagen-induced platelet aggregation in whole blood, and on the fibrinolytic and serotonergic systems in rats have been studied. One hour long stress caused a release of tissue plasminogen activator (tPA) into the blood and a shortening of euglobulin clot lysis time (ECLT), whereas restraint of longer duration was responsible for a reduction in platelet aggregation, an elevation in the activity of plasminogen activator inhibitor with a concomitant fall in tPA and a prolongation of ECLT relative to controls. Whole-blood and plasma serotonin and its metabolite 5-hydroxyindoleacetic acid were also higher in the stressed rats and whole-blood serotonin level showed a negative correlation with tPA in the stressed rats. Either stress and/ or its duration are responsible for changes in both fibrinolytic and serotonergic systems.

ISSN:1424-8832    

DOI:10.1159/000217107

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Patients with ischaemic heart disease have high levels of plasminogen activator inhibitor type 1 (PAI-1). These levels can constitute an independent thrombotic risk factor. In addition, PAI-1 synthesis is greater in the atherosclerotic vessels than in the normal vessels and this can also constitute an atherogenic risk factor. There is a good correlation between insulinaemia and PAI-1, but it has not been demonstrated that the circulating level of PAI-1 depends exclusively on insulinaemia. The increased levels of PAI-1 correlate with other coronary risk factors, especially hypertriglyceridaemia, but high PAI-1 levels are also found in normolipaemic patients. Vascular synthesis of PAI-1 can be promoted by high levels of circulating lipoprotein a. Finally, an exercise programme can increase the fibrinolytic activity of heart disease patients towards normal.

ISSN:1424-8832    

DOI:10.1159/000217108

出版商:S. Karger AG    

年代:1994

数据来源: Karger

摘要:

Several parameters of fibrinolytic and protein C pathways were evaluated in three groups of patients with high (HR), moderate (MR) and low (LR) postoperative thrombotic risk undergoing major gynaecological surgery. The HR and MR groups were subjected to low molecular weight heparin (LMW) prophylaxis. A significant increase in plasminogen activator inhibitor type 1 (PAI-1) antigen and activity levels was observed in the HR patient group in comparison with the MR and LR groups in the preoperative and early postoperative period. In all the groups studied, the maximum increase in the levels of PAI-1 was seen on day 1 after surgery. However, the D-dimeric levels reached the highest level on day 7. A significant increase in activated protein C:α1antitrypsin (APC:α1AT) complex levels was observed in the HR group in comparison with the LR group, and a strong decrease in protein C inhibitor in the early postoperative period was detected in all the groups. In spite of heparin prophylaxis, 2 HR patients were diagnosed as deep vein thrombosis (DVT) during the postoperative period. Both patients showed pre-operative levels of PAI-1 antigen or activity and APC:α1AT complexes above the mean + 1 SD of the pre-operative levels in the HR group. In conclusion, in HR patients a hypofibrinolytic and hypercoagulable state was detected in the pre-operative and early postoperative periods. The prophylactic LMW heparin dose used in the present report (20 mg/day × 7) was insufficient to prevent DVT in the HR group. At present our HR patients are given higher doses of LMW heparin (40 mg/day

ISSN:1424-8832    

DOI:10.1159/000217109

出版商:S. Karger AG    

年代:1994

数据来源: Karger