摘要:

The historical development of in-vitro bleeding time tests, using solely shear forces to initiate haemostatic plug formation, in the absence of the vessel wall or its components, is described. Techniques that have no potential for routine use in clinical practice, such as flow chambers and cone-and-plate viscometers, are excluded. The problems related to the use of citrated blood in platelet function tests are discussed. In light of the pivotal role of thrombin and platelet-dependent thrombin generation in haemostasis/thrombosis, the advantage and clinical benefits of testing unadulterated native blood is discussed.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Low molecular weight heparins are widely used in the prophylaxis and treatment of thrombotic disorders. The effect of low molecular weight heparins on coagulation was examined ultrastructurally in an animal model. A test and a control group was formed, each consisting of five rabbits. Nadroparine (225 Institute of Chaoy Unit/kg twice daily) was applied to the test group for 10 days. The control group received 1 ml saline solution subcutaneously. Blood and vascular tissue samples collected at the end of the 10th day were evaluated under a JEM 100 B electron microscope. Platelet degranulation and agglutination was observed in the control group. Fibrin materials were detected in the cytoplasms and surroundings of degranulated platelets. Erythrocyte accumulation was remarkable on the vascular endothelium with intact coagulation periods. In the test group, outer membranes of platelets, hyalomere, and granular structures in the granulomeres were detected to be nearly intact. There were rare erythrocytes in the large vascular lumens. The aggregation phase had occurred but no agglutination was detected. Nadroparine seems to preserve consistency of lipoprotein membranes of platelets and granular structures containing enzymes, which contribute to the coagulation mechanisms.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Atherothrombosis can be regarded as a ‘life-style related disease’ of which diet is one of the important risk factors. The prophylactic effect of partially defatted flaxseed meal (PDFM) on atherothrombosis has not yet been studied. The aim of this study was to assess the effect of PDFM and a lignan from flaxseed, secoisolariciresinol diglucoside (SDG), on thrombosis and atherogenesis. An earlier developed test, the quantitative assessment of laser-induced thrombus formation in the carotid artery of apolipoprotein E and low-density lipoprotein receptor deficient mice was used in this study. Thrombotic and atherosclerotic status was assessed in mice kept on a high-fat diet for 8 weeks (40% in energy). The diet contained 0.05% cholesterol alone (control) or the same cholesterol with added PDFM (5% w/w; 8.3 g/kg body weight per day) or SDG (0.06% w/w; 100 mg/kg body weight per day). PDFM showed antithrombotic (P<0.01) and anti-atherogenic effect (P<0.01). SDG did not affect either atherogenesis or thrombosis. This study suggests that dietary intake of PDFM can be beneficial in reducing the risk of high-fat-induced atherothrombosis.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

To describe the use of recombinant activated factor VII (rFVIIa) in patients with life-threatening haemorrhage. We report a case series of Australian patients with life-threatening haemorrhage who were treated with rFVIIa prior to August 2002 namely 21 patients, median age 45 years (range 22–79 years), 33% (seven of 21) female. The major causes for bleeding were multi-trauma, cardiac or vascular surgery, or orthoptic liver transplantation. In the 24 h prior to the administration of rFVIIa, the median blood usage was 22 U packed cells (range 3–66 U), the median International Normalized Ratio was 1.6 (range 1.4–3.6) and the median activated partial thromboplastin time was 55 s (range 31–180 s). During the 24 h after administration of rFVIIa, the median blood usage was 2 U packed cells (range 0–16 U), the median International Normalized Ratio was 1.0 (range 0.9–1.2) and the median activated partial thromboplastin time was 40 s (range 30–94 s); P<0.001 for each comparison. Sixteen of the 21 patients were discharged from hospital or were alive at 30 days. There were no thrombotic complications following the administration of rFVIIa. These uncontrolled data suggest a role for rFVIIa as an adjunctive haemostatic measure in surgical patients with life-threatening haemorrhage for whom conventional measures to achieve haemostasis have failed.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Platelet-derived microparticles that are produced during platelet activation bind to traumatized endothelium. Such endothelial injury occurs during percutaneous transluminal coronary angioplasty. Approximately 20% of these patients subsequently develop restenosis, although this is improved by treatment with the anti-platelet glycoprotein IIb/IIIa receptor drug abciximab. As platelet activation occurs during angioplasty, it is likely that platelet-derived microparticles may be produced and hence contribute to restenosis. This study population consisted of 113 angioplasty patients, of whom 38 received abciximab. Paired peripheral arterial blood samples were obtained following heparinization and subsequent to all vessel manipulation. Platelet-derived microparticles were identified using an anti-CD61 (glycoprotein IIIa) fluorescence-conjugated antibody and flow cytometry. Baseline clinical characteristics between patient groups were similar. The level of platelet-derived microparticles increased significantly following angioplasty in the group without abciximab (pairedttest,P= 0.019). However, there was no significant change in the level of platelet-derived microparticles following angioplasty in patients who received abciximab, despite requiring more complex angioplasty procedures. In this study, we have demonstrated that the level of platelet-derived microparticles increased during percutaneous transluminal coronary angioplasty, with no such increase with abciximab treatment. The increased platelet-derived microparticles may adhere to traumatized endothelium, contributing to re-occlusion of the arteries, but this remains to be determined.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

To reduce the risk of intracerebral hemorrhage during thrombolytic therapy, a lower dose of tissue plasminogen activator (t-PA) or urokinase is used for acute peripheral arterial thrombi versus coronary thrombi. We hypothesized that elevated plasminogen activator inhibitor-1 (PAI-1) activity could neutralize infused t-PA or urokinase, resulting in lysis failure. Active PAI-1, active t-PA and total t-PA antigen were measured in 20 patients receiving t-PA, and active PAI-1 was measured in four patients receiving urokinase for acute peripheral arterial thrombosis. The 18 patients that successfully lysed their thrombi all had low active PAI-1 levels (10 ± 19 pmol/l) during infusion of thrombolytic therapy, while six patients that failed to lyse their thrombi had high active PAI-1 levels (1533 ± 1384 pmol/l,P= 0.00007) during infusion. Active t-PA levels during t-PA infusion were higher in the group that lysed their thrombi (536 ± 423 pmol/l versus 42 ± 45 pmol/l,P= 0.04) even though total t-PA levels were lower (1240 ± 493 pmol/l versus 1956 ± 709 pmol/l,P= 0.03). In the patients that failed to lysed their thrombi,>95% of infused t-PA was neutralized by PAI-1. We conclude that elevated PAI-1 during acute peripheral arterial thrombolysis is associated with an increased risk of lysis failure due to reduced levels of circulating active t-PA or urokinase.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

The comparatively high rate of complications, both to the mother and foetus, of warfarin and unfractionated heparin have led to an increased use of low molecular weight heparins (LMWH) in pregnant women at risk of thrombosis. However, despite reliable pharmacokinetics of LMWH, current practice is that anti-activated factor X levels are monitored in this group of patients. We report the use of unmonitored dalteparin in 27 pregnancies of 25 women who had previous thrombotic events. All women had normal renal function and weighed less than 85 kg prior to conceiving. The regimen consisted of 5000 IU dalteparin once daily started at the time of a positive pregnancy test, and increased to twice daily at 16–20 weeks gestation. In this cohort of patients there was a low complication rate. None of the women developed recurrent venous thromboses during these pregnancies but two women with known cerebral antiphospholipid syndrome developed recurrent cerebral ischaemia, which responded to an increase in dose.In our small group of patients, we have found that the use of intermediate-dose LMWH in pregnant women does not need to be monitored, and that it is safe and probably effective in preventing recurrent venous but not arterial thromboembolic events in high-risk pregnancies.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

A 49-year-old male with alcoholic cirrhosis suffered several spontaneous, life-threatening, deep muscle bleeding episodes. Laboratory evaluation indicated excessive fibrinolysis with low plasminogen, low α2-antiplasmin, undetectable plasminogen activator inhibitor type 1 (PAI-1) activity, high tissue plasminogen activator (t-PA) activity and high t-PA antigen. Treatment with oral anti-fibrinolytic agents prevented further bleeding episodes. Decompensated cirrhosis eventually necessitated orthotopic liver transplantation. Post-operatively, the patient did not require oral anti-fibrinolytic agents, and there were no significant bleeding events. Circulating PAI-1 activity, t-PA activity and antigen normalized by 3 months post transplant. In short, the profound bleeding diathesis, as well as the imbalance in t-PA and PAI-1 levels, corrected after liver transplantation. Recognition of such patients is important, because the bleeding diathesis is an indication rather than a contraindication for orthotopic liver transplantation.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Previous research has shown a link between infectious inflammatory processes and hemostatic abnormalities. No data exist, however, on whether coagulation markers correlate with the severity of community-acquired pneumonia (CAP) at admission. We conducted a prospective, observational study in an Emergency Medicine Department of a primary care hospital. Sixty-eight patients admitted with CAP were included. Blood samples were collected at admission and assayed for D-dimer levels. D-dimers were correlated with the Pneumonia Patient Outcome Research Team (PORT) score and Acute Physiology and Chronic Health Evaluation II score on admission, with length of hospital stay, number of organ failures, time to defervescence and hospital mortality. D-dimer levels were positively correlated with the Acute Physiology and Chronic Health Evaluation II score (r= 0.44,P= 0.0002), the PORT score (r= 0.36,P= 0.002) and the length of hospital stay (r= 0.24,P= 0.046). Mean D-dimer levels of patients for whom hospitalization is recommended, according to PORT guidelines, were significantly higher than D-dimer levels of patients for whom hospitalization is not recommended (1.47 ± 1.05 μg/ml and 0.71 ± 0.79 μg/ml respectively;P= 0.006). The correlation between D-dimer levels and time to defervescence, development of organ system failure and outcome was not statistically significant. We conclude that D-dimer levels at admission may predict the severity of CAP.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Platelet membrane glycoprotein IIb/IIIa plays an important role in platelet aggregation. A polymorphism of the gene encoding the IIIa subunit, with the two allele forms PLA1 and PLA2, has been identified. Some, but not all, studies suggest that the PLA2 allele confers an increased risk of suffering a myocardial infarction. Conversely, a recent study suggests that the PLA1 allele may contribute to early atherosclerosis and more rapid progression of stable coronary artery disease. To test whether these associations could be reproduced in a well-characterized sample of survivors of premature myocardial infarction, we examined 369 patients admitted to coronary care units in the Stockholm area who suffered a first myocardial infarction before the age of 60 years. There were no significant differences in extent of coronary artery disease according to PLA genotype group (based on quantitative coronary angiography). In addition, the frequencies of PLA1 and PLA2 alleles did not differ from those of 388 well-matched control subjects without coronary artery disease. These results suggest that the PLA1/PLA2 polymorphism of the platelet glycoprotein IIIa gene does not substantially contribute to the development of coronary atherosclerosis or the genetic susceptibility to premature myocardial infarction.

ISSN:0957-5235    

出版商:OVID    

年代:2003

数据来源: OVID