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1.
BACKGROUND: Treatment with hyperbaric oxygen (HBO2) is controversial when treating disorders other than decompression sickness. Still, HBO2 is a treatment modality that has gained recognition in certain situations of ischaemia reperfusion. However, not much is known about its effect on the endothelial cells. Based on earlier studies, the hypothesis was that HBO2 treatment stimulates the release of fibrinolytic factors. The aim of the study was to investigate the effect of HBO2 treatment on cultured endothelial cells in a simulated ischaemia-reperfusion model. METHODS: To mimic the clinical situation during ischaemia reperfusion, endothelial cells were subjected to anoxia for 8 h, followed by reperfusion with either HBO2 or normobaric air for 1.5 h, and compared with an untreated control that was not exposed to anoxia. Components investigated were the fibrinolytic stimulator tissue plasminogen activator (t-PA), urokinase plasminogen activator (uPA) and the antagonist. plasminogen activator inhibitor type one (PAI-1). RESULTS: Immediately after 8 h of total anoxia and reoxygenation with HBO2 (for 1.5 h), the mean (SEM) concentrations of t-PA, PAI-1 and uPA were significantly increased compared to the other groups. The difference between the normobaric and control groups, measured at 1.5 h, 6 h and 24 h post-anoxia, persisted throughout the experiment. CONCLUSION: In this ischaemia-reperfusion model. HBO2 stimulates the release of fibrinolytic factors. These observations might be relevant in trauma care in preventing thromboses and/or microembolization following ischaemia-reperfusion.  相似文献   

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Summary.  Background:  Pre-eclampsia (PET) and/or fetal growth restriction (FGR) remain a major cause of maternal and fetal morbidity and mortality. In pregnancy, fibrinolysis is controlled by the maternal endothelium and placenta, both of which are central to the pathogenesis of PET/FGR. Clinically, uterine artery Doppler screening at 23 weeks is used to predict PET/FGR. An abnormal uterine artery Doppler finding is defined as early diastolic bilateral uterine artery notching (BN) in the waveform. However, about 50% of mothers with BN do not develop PET/FGR. Objectives:  We investigated fibrinolytic changes and uterine artery Doppler findings in the second trimester, and related them to pregnancy outcome; in particular assessing whether fibrinolytic markers could discriminate between normal and abnormal outcome in mothers with BN. Patients/methods:  Plasma levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), plasminogen activator inhibitor-2 (PAI-2), plasmin-α2 antiplasmin (PAP), D-dimers and markers of endothelial dysfunction were measured with Doppler ultrasound at 23 weeks. Results:  Those with BN had decreased PAP and D-dimer levels, and raised PAI-1 and thrombomodulin levels. Mothers with BN and PET/FGR had significantly increased t-PA levels and reduced PAI-2 levels. Conclusions:  BN at 23 weeks of gestation is associated with increased PAI-1 levels. Within the BN group, mothers who developed PET/FGR had increased t-PA levels and decreased PAI-2 levels, although there was no net change in fibrinolysis as measured by D-dimer levels. No single fibrinolytic marker is helpful in determining pregnancy outcome in those with BN, but t-PA and PAI-2 are worthy of study in a multifactorial algorithm.  相似文献   

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Elevated plasma t-PA (tissue plasminogen activator) and serum CRP (C-reactive protein) concentrations are associated with an adverse cardiovascular risk. In the present study, we investigated whether acute local inflammation causes vascular dysfunction and influences t-PA release in patients with stable coronary heart disease. Serum CRP, plasma t-PA and PAI-1 (plasminogen activator inhibitor type 1) concentrations were determined in 95 patients with stable coronary heart disease. A representative subpopulation of 12 male patients received an intra-brachial infusion of TNF-alpha (tumour necrosis factor-alpha) and saline placebo using a randomized double-blind cross-over study design. Forearm blood flow and plasma fibrinolytic and inflammatory variables were measured. Serum CRP concentrations correlated with plasma t-PA concentrations (r=0.37, P<0.001) and t-PA/PAI-1 ratio (r=-0.21, P<0.05). Intra-arterial TNF-alpha caused a rise in t-PA concentrations (P<0.001) without affecting blood flow or PAI-1 concentrations. TNF-alpha pretreatment impaired acetylcholine- and sodium nitroprusside-induced vasodilatation (P<0.001 for both) whilst doubling bradykinin-induced t-PA release (P=0.006). In patients with stable coronary heart disease, plasma fibrinolytic factors correlate with a systemic inflammatory marker and local vascular inflammation directly impairs vasomotor function whilst enhancing endothelial t-PA release. We suggest that the adverse prognosis associated with elevated plasma t-PA concentrations relates to the underlying causative association with vascular inflammation and injury.  相似文献   

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BACKGROUND: The development of global tests for the fibrinolytic capacity in blood is hampered by the low base-line fibrinolytic activity in blood, by the involvement of both plasmatic components and blood cells in the fibrinolytic system and by the loss of fibrinolytic activity as a result of the action of plasminogen activator inhibitor-1 (PAI-1). OBJECTIVE: To develop a new test for the global fibrinolytic capacity (GFC) of whole blood samples. METHODS AND RESULTS: Collection of blood in thrombin increased the subsequent generation of fibrin degradation products. This was ascribed to rapid clot formation and concomitant reduction of in vitro neutralization of tissue-type plasminogen activator (tPA) by PAI-1. On the basis of this observation, the following test was designed: blood samples were collected in thrombin with and without aprotinin and clots were incubated for 3 h at 37 degrees C. The GFC was assessed from the difference between the fibrin degradation products in the two sera. The assay was applied to blood samples from patients and healthy subjects. Other hemostasis parameters were determined in plasma samples taken simultaneously. The GFC varied considerably (normal range 0.13-13.6 microg mL(-1)); physical exercise strongly increased the GFC. Statistically significant correlations were found with tPA activity, PAI-1 activity and fibrinogen level. A mixture of antibodies against tPA and urokinase-type plasminogen activator (uPA) completely inhibited the GFC. An inhibitor of activated thrombin-activatable fibrinolysis inhibitor (TAFI) accelerated fibrinolysis 8-fold. CONCLUSION: The new test represents a global assessment of the main fibrinolytic factors in plasma and potentially those associated with blood cells.  相似文献   

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Endothelial cells impart thromboresistance to the blood vessel wall. As modulators of fibrinolytic activity, these cells synthesize and secrete tissue plasminogen activator (t-PA) as well as its physiologic inhibitor, plasminogen activator inhibitor-1. In addition, endothelial cells support membrane-associated assembly of plasminogen and tissue plasminogen activator. Recently, an M(r) approximately 40,000 protein expressed on endothelial cells has been shown to interact noncompetitively through disparate mechanisms with both t-PA and plasminogen, suggesting trimolecular assembly of enzyme, substrate, and receptor (Hajjar, K. A. 1991. J. Biol. Chem. 266:21962-21970). In the present study, treatment of cultured endothelial cells with DL-homocysteine was specifically associated with a selective reduction in cellular binding sites for t-PA. This 65% decrease in binding was associated with a 60% decrease in cell-associated t-PA activity. No change in affinity for t-PA or plasminogen or in the maximal number of binding sites for plasminogen was observed. Matrix-associated t-PA binding sites were not affected. These data suggest a new mechanism whereby homocysteine may perturb endothelial cell function, thus promoting a prothrombotic state at the surface of the blood vessel wall.  相似文献   

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Plasminogen activation is catalyzed both by tissue-type-(t-PA) and by urokinase-type plasminogen activator (u-PA). This reaction is controlled by plasminogen activator inhibitor type 1 (PAI-1) that is either present in plasma or bound to fibrin, present in a thrombus. We studied the mechanism of in vitro inhibition of both t-PA and u-PA activity by PAI-1 bound to fibrin. It is shown that activation of latent PAI-1 unmasks a specific fibrin-binding site that is distinct from its reactive site. This reactive site of activated PAI-1 bound to fibrin is fully exposed to form complexes with t-PA and u-PA, that are unable to activate plasminogen. Upon complex formation with either one of the plasminogen activators, PAI-1 apparently undergoes a conformational change and loses its affinity for fibrin. Consequently, complexes of u-PA and PAI-1 dissociate from the fibrin matrix and are encountered in the fluid phase. In contrast, t-PA/PAI-1 complexes remain bound to fibrin. By employing recombinant t-PA deletion-mutant proteins, that precisely lack domains involved in fibrin binding, we demonstrate that binding of t-PA/PAI-1 complexes is mediated by both the "finger" (F) and the "kringle-2" (K2) domain of t-PA. A model is proposed that explains inhibition of the fibrinolytic process, at the level of plasminogen activation by t-PA, directed by PAI-1 bound to fibrin. An implication of the proposed model is that t-PA/PAI-1 complexes and free t-PA compete for the same binding sites on fibrin.  相似文献   

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目的 :探讨血浆组织型纤溶酶原激活物 (t -PA)及其抑制物 (PAI -1)、血栓调节蛋白 (TM )和血小板α颗粒膜蛋白 -14 0 (GMP -14 0 )在急性脑梗死发病中的意义。方法 :对 5 7例急性脑梗死患者进行血浆t -PA、PAI -1、TM及GMP -14 0的检测 ,并与对照组进行比较。结果 :急性脑梗死患者较正常对照组t -PA水平明显降低 ,PAI -1、TM及GMP -14 0水平明显升高 (P <0 0 1)。结论 :急性期脑梗死患者内皮细胞损伤、血小板活化及纤溶活性的变化可能参与了疾病的发生发展过程 ,为脑梗死的治疗提供了理论依据  相似文献   

11.
陈世德  陶新智  伍伟锋 《临床荟萃》2004,19(13):724-726
目的 研究慢性心力衰竭 (CHF)患者血浆组织型纤溶酶原激活物 (t PA)和纤溶酶原激活物抑制物 1(PAI 1)含量的变化及其临床意义。方法 用酶联免疫吸附法 (ELISA)检测 6 0例CHF患者 (CHF组 )和 2 0例健康体检者 (正常对照组 )血浆t PA及PAI 1抗原含量。结果 CHF组血浆t PA和PAI 1平均含量都明显高于对照组 (P<0 .0 1)。CHF患者血浆PAI 1含量增高随心功能恶化而愈加明显。结论 CHF患者纤溶功能明显下降 ,可用血浆t PA、PAI 1含量作为判断病情的参考指标之一。  相似文献   

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BACKGROUND AND OBJECTIVES: Tissue plasminogen activator (t-PA) improves the outcome of ischemic stroke by recanalization of occluded vessels, but has neurotoxic side effects in experimental stroke models. Here, the effect of plasminogen activator inhibitor-1 (PAI-1), an endogenous inhibitor of t-PA, on ischemic infarct volume was studied. METHODS: After either permanent ligation or thrombotic occlusion of the middle cerebral artery (MCA), infarct volume, spontaneous reperfusion of thrombosed MCA, t-PA/PAI-1 complex level, and blood-brain barrier (BBB) permeability in the ischemic region was studied in transgenic mice with overexpression of PAI-1 and wild-type littermate controls and in mice with intracerebroventricular injection of human PAI-1. RESULTS: Infarct volume was smaller in PAI-1 transgenic mice (2.9 +/- 3.7 mm3, mean +/- SD) than in controls (8.9 +/- 5.0 mm3, P < 0.05) after permanent MCA ligation (plasma PAI-1 level 39 +/- 23 ng mL(-1) in transgenic mice vs. 1.5 +/- 0.6 ng mL(-1) in controls), whereas after MCA thrombosis it was larger in transgenics (13.1 +/- 3.1 mm3) than in controls (8.0 +/- 3.2 mm3, P < 0.05). Spontaneous reperfusion of the thrombosed MCA was significantly delayed in transgenic vs. control mice. In the ligation model, t-PA/PAI-1 complex levels were higher and BBB disruption was more pronounced in the ischemic region. Human PAI-1 injection reduced infarct volume by about 50% in wild-type mice but not in t-PA gene deficient mice. CONCLUSIONS: High PAI-1 levels reduced infarct volume in the permanent MCA ligation model, but enhanced it in the MCA thrombosis model.  相似文献   

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OBJECTIVE: Hyaluronan (HA) is an important extracellular matrix component and is involved in fluid homeostasis, tissue repair, and response to infections. Previous studies have shown that supplementation of dialysis fluid with high molecular weight HA may have a positive impact on peritoneal solute and fluid transport characteristics. In the present study, we investigated the impact of HA on the synthesis of tissue-type plasminogen activator (t-PA) and its inhibitor, plasminogen activator inhibitor type 1 (PAI-1) in cultured human peritoneal mesothelial cells (MC). METHODS: Cultured human peritoneal MC isolated from omental tissue were used for the experiments. Concentrations of t-PA and PAI-1 antigens were measured in conditioned media of confluent MC using ELISA. Northern blot analysis was performed to investigate mRNA expression of t-PA, PAI-1, and low-density lipoprotein receptor-related protein. RESULTS: Hyaluronan in a concentration as suggested for supplementation of dialysis fluid (10 mg/dL) did not have a significant impact on the synthesis of t-PA or PAI-1 in human MC. However, incubation of MC with higher concentrations of HA (30-1000 mg/dL) resulted in a concentration- and time- (8- 48 hours) dependent decrease in t-PA antigen release and mRNA expression. In contrast, PAI-1 antigen secretion was distinctly but not significantly increased in the presence of HA. CONCLUSION: The expression of t-PA and PAI-1 in MC was not affected by low concentrations of HA. Therefore, it is reasonable to assume that supplementation of dialysis fluid with HA (10 mg/dL) will not decrease mesothelial fibrinolytic activity. Only high concentrations (> 50 mg/dL) may disturb the balance between intraperitoneal generation and degradation of fibrin by decreasing t-PA synthesis.  相似文献   

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目的:研究急性脑血栓形成患者血浆及脑脊液组织型纤溶酶原激活物(t-PA)及其抑制物(PAI-1)和D-二聚体含量的变化及其临床意义。方法:采用双抗体夹心固相酶联免疫吸附法(ELISA)检测35例急性脑血栓形成患者(血栓组)的血浆和其中3l例的脑脊液t—PA、PAI-l和D-二聚体的抗原含量,与35例无心脑、肝肾及血液疾病患者(对照组)血浆和其中20例脑脊液进行比较。结果:血栓组血浆及脑脊液中t-PA、PAI-1和D-二聚体含量均高于对照组;脑脊液中t-PA、PAI-l和D-二聚体的含量分别与血浆中含量呈正相关。结论:急性脑血栓形成患者纤溶活性明显下降,t-PA及PAI-l参与了脑血栓形成的病理过程。  相似文献   

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BACKGROUND: Menorrhagia is known to be associated with uterine fibroids, adenomyosis, pelvic infections, endometrial polyps and clotting defects. A viable alternative therapy to hysterectomy should alleviate heavy menstrual blood flow and consequently improve the quality-of-life measures in women presenting with menorrhagia. The levonorgestrel-releasing intrauterine system (LNG-IUS) ranks higher than medical treatments in terms of efficacy, comparable improvements in quality of life and psychological well-being. OBJECTIVE: The purpose of the study was to determine the effects of 6 months of LNG-IUS use on menstrual blood loss and the hemostatic, fibrinolytic/inhibitor systems in blood and the endometrium in women with menorrhagia with known pathologic causes. PATIENTS AND METHODS: Samples from 41 women were analyzed. Hemoglobin, hematocrit, thrombelastography, tissue-type plasminogen activator (t-PA), urokinase plasminogen activator (u-PA), u-PA receptor (u-PAR), plasminogen activator inhibitor-1/2 (PAI-1/2), D-dimer and von Willebrand factor (VWF) were determined, and t-PA, u-PA and PAI-1/2 were also determined in endometrial tissue extracts. Results: Menorrhagia was reduced in 89% of women by 3 months; by 6 months all women had no menorrhagia, and 39% of women had become amenorrhoeic. Hemoglobin and hematocrit levels showed improvement, and reached normal reference levels by 6 months. There were no systemic changes in the fibrinolytic/inhibitor systems and VWF, except for a decreased u-PAR level. However, in the endometrium, significant elevations in PAI-1/2 together with u-PAR levels were seen at 6 months. CONCLUSIONS: The slow levonorgestrel-release intrauterine device use results in high expression of fibrinolytic inhibitors (PAI-1/2) and upregulated u-PAR expression in the endometrium. Systemic hemostasis was not significantly altered. The study demonstrated that LNG-IUS is highly effective in the treatment of menorrhagia with known pathologic causes.  相似文献   

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Summary.  Background : The mechanisms by which postmenopausal hormone replacement therapy (HRT) may influence risk of cardiovascular disease are still unclear. Impaired fibrinolytic function is associated with an enhanced risk of cardiovascular disease and therefore the effect of HRT on fibrinolysis may be of importance. Objectives : To investigate the prolonged effect of HRT on the fibrinolytic system and to determine whether two common polymorphisms in the plasminogen activator inhibitor-1 (PAI-1) and tissue-type plasminogen activator (t-PA) genes modulate this effect. Methods : Healthy postmenopausal women ( n  = 248) were randomized to HRT ( n  = 122) or no substitution ( n  = 126) 5 years prior to investigation. Results : Significantly higher values of t-PA activity and lower values of PAI-1 activity and PAI-1 antigen were found in the HRT group compared with the control group. This effect was independent of smoking and without influence from the two common polymorphisms PAI-1 −675(4G/5G) and t-PA intron8ins311. Furthermore, no difference between opposed estrogen (with norethisterone acetate as the gestagen component) and unopposed estrogen therapy was found. Both an intention-to-treat and a per-protocol analysis were performed and similar results were obtained. Conclusions : Long-term treatment with HRT in healthy postmenopausal women was found to be associated with a beneficial fibrinolytic profile. This effect was found independent of smoking status, opposed and unopposed estrogen therapy had equal effect, and no influence of the two common polymorphisms PAI-1–675(4G/5G) and t-PA intron8ins311 was found. This effect of HRT on fibrinolytic capacity may be one of the beneficial effects of HRT in relation to cardiovascular diseases.  相似文献   

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We investigated the relationship between plasma levels of metabolic and fibrinolytic variables in 163 fasted patients attending a lipid clinic. Of these patients, 118 had hypertriglyceridaemia (HTG) and 45 had normotriglyceridaemia (NTG). In HTG, basal fibrinolytic activity, ie tissue plasminogen activator (t-PA) activity, was impaired as a result of high plasminogen activator inhibitor type 1 (PAI-1) antigen and activity. Multiple stepwise regression analysis identified insulin and triglyceride levels as independent determinants of plasma PAI-1 levels (R2 = 0.18; P = 0.0001). When the patients were stratified into tertiles according to their levels of triglyceride and insulin, PAI-1 antigen levels were found to increase with rising levels of triglyceride in each insulin tertile. In contrast, the increase of PAI-1 with rising insulin levels was evident in the highest triglyceride tertile. In addition, subjects in the lowest tertile of both triglyceride and insulin had the lowest PAI-1 antigen levels, and subjects in the highest tertile of both triglyceride and insulin had the highest levels of PAI-1. Both basal and stimulated levels of t-PA antigen were significantly higher in HTG than in NTG. Multiple stepwise regression analysis identified triglyceride level as the sole major determinant of t-PA antigen levels (R2 = 0.13; P = 0.00003). The observation that both insulin and triglycerides correlate with PAI-1, whereas triglycerides were involved only in the increased secretion of t-PA, suggests that these two proteins are regulated by different mechanisms.  相似文献   

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BACKGROUND: The plasmin activation system is involved in the development of restenosis after percutaneous coronary interventions (PCI). Conflicting data exist concerning the role of plasminogen activator inhibitor-1 (PAI-1) and its predictive value for restenosis. OBJECTIVES: To evaluate the fibrinolytic response to injury after PCI with or without stent implantation on different antithrombotic medications and its relation to late restenosis. PATIENTS AND METHODS: Eighty consecutive patients with successful PCI without (balloon only; n = 37) or with stent implantation (stent; n = 43) on different antithrombotic regimes (balloon only, aspirin; stent, aspirin/coumadin/dipyridamole vs. aspirin/ticlopidine). Blood samples were taken at baseline and up to 7 days after PCI and PAI-1 active antigen and tissue plasminogen activator (t-PA) antigen were determined. Restenosis was angiographically determined after 6 months. RESULTS: PCI increased both t-PA and PAI-1 levels (P < 0.001), with a significant prolonged and pronounced increase in stent vs. balloon-only patients (P < 0.05). Restenosis (stent 26%; balloon 38%) was significantly correlated to an attenuated PAI-1 increase after 24 h in the ticlopidine group (P = 0.007; restenosis, relative Delta PAI-1 + 50 +/- 28%; non-restenosis, + 139 +/- 50%), but not in the coumadin group. In the balloon-only group late restenosis (ISR) was associated with a trend for an augmented PAI-1 increase after 24 h. CONCLUSIONS: Coronary stent implantation significantly increases t-PA and PAI-1 plasma levels up to 1 week compared with balloon angioplasty alone. ISR in ticlopidine-treated patients was associated with an attenuated early PAI-1 active antigen increase. A less than 50% increase 24 h after stent implantation under ticlopidine treatment may identify patients at risk for the development of ISR.  相似文献   

19.
Recombinant adenoviral vectors expressing u-PA, t-PA, PAI-1 and PAI-2 were employed to correlate the expression of components of the fibrinolytic system with the invasiveness of HT 1080 tumor cells. Migration through Transwell inserts in vitro in the presence of plasminogen was increased up to 22% by overexpression of u-PA, whereas t-PA had no effect. Gene transfer of PAI-1 or PAI-2 both reduced migration in a dose-dependent manner by up to 43% with PAI-1 and 29% with PAI-2. Two routes of gene transfer were used to alter metastasis of subcutaneously implanted HT 1080 cells expressing firefly luciferase in nude mice. Infection of cultured tumor cells with adenovirus expressing either PAI-1 or PAI-2 before implantation significantly reduced the incidence of lung metastasis by 60% compared with control virus. However, only PAI-2 reduced the incidence of lung and brain metastasis following liver gene transfer. Although PAI gene transfer by either route reduced primary tumor size, it had little effect on tumor vascularization or host survival. The migratory and metastatic phenotype of HT 1080 tumor cells is thus directly dependent on u-PA expression levels and can be altered by gene transfer of u-PA or plasminogen activator inhibitors.  相似文献   

20.
The urokinase plasminogen activator (uPA) system consists of the serine protease uPA, the glycolipid-anchored receptor, uPAR, and the 2 serpin inhibitors, plasminogen activator inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2). Recent findings suggest that uPA, uPAR and PAI-1 play a critical role in cancer invasion and metastasis. Consistent with their role in cancer dissemination, high levels of uPA, PAI-1 and uPAR in multiple cancer types correlate with adverse patient outcome. The prognostic value of uPA/PAI-1 in axillary node-negative breast cancer patients was recently validated using both a prospective randomised trial and a pooled analysis. Assay of uPA and PAI-1 may thus help identify low-risk node-negative patients for whom adjuvant chemotherapy is unnecessary. Finally, emerging data suggest that high levels of uPA and PAI-1 in breast cancer are associated with a preferential response to adjuvant chemotherapy but relative resistance to hormone therapy. The measurement of uPA components, especially in breast cancer, thus has the potential to help with individualised patient management.  相似文献   

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