Endogenous Fibrinolysis Research Articles

Blood coagulation, fibrinolytic activity and lipid profile in subclinical thyroid disease: subclinical hyperthyroidism increases plasma factor X activity

Various abnormalities of coagulation and fibrinolysis occur in patients with thyroid diseases, and may range from subclinical laboratory abnormalities to clinically significant disorders of coagulation and, rarely, major haemorrhage or thromboembolism. The influence of subclinical hypothyroidism (SHypo) on haemostasis is controversial, both hypercoagulable and hypocoagulable states have been reported. A hypercoagulable state might be a risk factor for thromboembolic disease in SHypo. On the other hand, subclinical hyperthyroidism (SCHyper) is associated with enhanced cardiovascular risk. In the English literature, there are no studies on changes in coagulation and fibriolytic status in subjects with SCHyper. Therefore, the aim of the present study was to investigate the markers of endogenous coagulation and fibrinolysis, and to evaluate the relationships between serum lipid profile and thyroid hormones and these haemostatic parameters in subclinical thyroid patients. Various haemostatic parameters were investigated in 30 patients with SHypo and 20 patients with SCHyper and compared to 20 euthyroid controls. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, factors V, VII, VIII, IX and X activities, vWF, antithrombin III (AT III), protein C, protein S, tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor-1 (PAI-1), as well as common lipid variables, were measured. The relationships between serum thyroid hormones and these haemostatic parameters were examined. Compared with the control subjects, only FX activity was significantly increased in patients with SCHyper (P < 0.01). Total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were significantly higher in patients with SHypo compared with the control group (P < 0.001 and P < 0.01, respectively). TC levels were significantly higher in patients with SCHyper than in controls (P < 0.05). No differences could be found in coagulation/fibrinolysis parameters between subclinical hypothyroid patients and control subjects. In patients with SCHyper, serum TSH level was positively correlated with FX activity (r: 0.58, P < 0.01) and inversely correlated with PAI-1 (r: -0.55. P < 0.05). Serum TG levels were inversely correlated with plasma activities of factors V, VII, VIII, IX, X and vWF (r: -0.83, P < 0.001; r: -0.68, P < 0.05; r: -0.61, P < 0.05; r: -0.77, P < 0.01; r: -0.63, P < 0.05; r: -0.60, P < 0.05, respectively). Serum TC levels were positively correlated with plasma fibrinogen levels (r: 0.72, P < 0.05). Serum HDL-C levels were positively correlated with protein S activity (r: 0.68, P < 0.05) and negatively correlated with F VII activity (r: -0.69, P < 0.05). Also, in patients with SHypo, serum TG levels were positively correlated with serum TSH levels (r: 0.42, P < 0.05), plasma activities of factors V, VII and X (r: 0.42, P < 0.05; r: 0.54, P < 0.01; r: 0.57, P < 0.01, respectively) and negatively correlated with plasma fibrinogen levels (r: -0.41, P < 0.05). Serum TC levels were positively correlated with factors V and X (r: 0.42, P < 0.05; r: 0.58, P < 0.01, respectively) and negatively correlated with t-PA Ag levels (r: -0.44, P < 0.05). Serum HDL-C levels were inversely correlated with F VII activity (r: -0.48, P < 0.05). Some differences were found in the haemostatic parameters and lipid profile between the subclinical thyroid patients and healthy controls. Increased factor X activity in patients with subclinical hyperthyroidism represent a potential hypercoagulable state, which might augment the already existing risk for atheroscleroic complications. Also, subclinical hypothyroid patients exhibit a more atherogenic lipid profile compared with healthy individuals. Therefore, subclinical hypothyroidism is also associated with an increased risk of cardiovascular disease. However, thyroid hormones may play a role at different levels of the complex haemostatic system in subclinical thyroid disease.

Diesel Exhaust Inhalation Causes Vascular Dysfunction and Impaired Endogenous Fibrinolysis

Although the mechanisms are unknown, it has been suggested that transient exposure to traffic-derived air pollution may be a trigger for acute myocardial infarction. The study aim was to investigate the effects of diesel exhaust inhalation on vascular and endothelial function in humans. In a double-blind, randomized, cross-over study, 30 healthy men were exposed to diluted diesel exhaust (300 microg/m3 particulate concentration) or air for 1 hour during intermittent exercise. Bilateral forearm blood flow and inflammatory factors were measured before and during unilateral intrabrachial bradykinin (100 to 1000 pmol/min), acetylcholine (5 to 20 microg/min), sodium nitroprusside (2 to 8 microg/min), and verapamil (10 to 100 microg/min) infusions 2 and 6 hours after exposure. There were no differences in resting forearm blood flow or inflammatory markers after exposure to diesel exhaust or air. Although there was a dose-dependent increase in blood flow with each vasodilator (P<0.0001 for all), this response was attenuated with bradykinin (P<0.05), acetylcholine (P<0.05), and sodium nitroprusside (P<0.001) infusions 2 hours after exposure to diesel exhaust, which persisted at 6 hours. Bradykinin caused a dose-dependent increase in plasma tissue plasminogen activator (P<0.0001) that was suppressed 6 hours after exposure to diesel (P<0.001; area under the curve decreased by 34%). At levels encountered in an urban environment, inhalation of dilute diesel exhaust impairs 2 important and complementary aspects of vascular function in humans: the regulation of vascular tone and endogenous fibrinolysis. These important findings provide a potential mechanism that links air pollution to the pathogenesis of atherothrombosis and acute myocardial infarction.

Double-blind randomized trial of perioperative fibrinolytic enhancement for femoropopliteal bypass

Patients with rest pain or acute peripheral arterial thrombosis are known to have impaired endogenous fibrinolysis, which is associated with an increased risk of early vascular graft thrombosis. This risk is exacerbated by the fibrinolytic shutdown which is known to occur after major surgery. Stanozolol, which has been demonstrated to enhance endogenous fibrinolysis, was therefore used in an attempt to prevent this perioperative fibrinolytic shutdown and so enhance graft patency. Twenty-seven patients were randomized to receive either 50 mg stanozolol or placebo intramuscularly 24 h before operation, followed by a 6 week course of either 5 mg stanozolol or placebo orally, twice daily. On the second day after operation, 10-11 MBq of autologous 111indium-labelled platelets were injected, with scanning over the graft on the 3 following days. Despite using a large depot of stanozolol, significant effects, such as raised plasminogen (P less than 0.001), reduced fibrinogen (P less than 0.001) and reduced euglobulin lysis time (P less than 0.001), were not seen until the seventh day after operation, with maximum benefit at 6 weeks. This was reflected in the 111indium-labelled platelet deposition studies. The placebo group had a progressive increase in platelet deposition on all 3 days. In contrast, those receiving stanozolol showed a lower, static picture of deposition. However, these changes did not attain statistical significance. Three patients experienced early graft thrombosis, two in the placebo group and one in the stanozolol group. Only an incomplete inhibition of the perioperative fibrinolytic shutdown was achieved. Much longer preoperative courses are thus required to allow the maximum effect to be present at the most crucial time. At present, perioperative fibrinolytic enhancement does not appear to be a practical proposition, and we must await the development of new safer and more potent agents.

Association between early postoperative coagulation activation and peri‐operative myocardial ischaemia in patients undergoing vascular surgery

We investigated the association of peri-operative myocardial ischaemia with activation of coagulation and endogenous fibrinolysis in patients undergoing vascular surgery. In 50 patients, continuous Holter monitoring was performed to assess peri-operative myocardial ischaemia and 12-lead electrocardiography was recorded preoperatively and 72 h postoperatively to assess myocardial infarction. Serial blood samples were drawn peri-operatively to determine the concentrations of fibrin monomers (for activation of coagulation), D-dimer (for endogenous fibrinolysis) and cardiac troponin T and I. Patients with myocardial ischaemia showed higher concentrations of fibrin monomers at 48 h, and higher concentrations of d-dimer preoperatively and at 24 and 48 h postoperatively. In patients with peri-operative myocardial ischaemia, strong positive correlations were observed between fibrin monomer and D-dimer concentrations at 15 min and 4 h postoperatively, and cardiac troponins at 15 min and at 4, 24, 48 and 72 h postoperatively. Early postoperative activation of coagulation and fibrinolysis is associated with peri-operative myocardial cell damage among patients who are at risk for, or have a history of, coronary artery disease plus peri-operative myocardial ischaemia.

Human gender differences in fibrinolytic responses to exercise training and their determinants

Endurance exercise training improves fibrinolysis, but this training-induced adaptation may differ somewhat between men and women. We sought to determine whether the potential gender differences in training-induced changes in selected fibrinolysis measures were related to changes in adiposity and/or plasma lipoprotein lipid levels. Seventeen men and 28 women, 50-75 years old, who were generally overweight to obese, were assessed for plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (t-PA) activity, t-PA antigen and plasma lipoprotein-lipid levels, and body composition before and after 6 months of endurance exercise training while on a low-fat diet. At baseline, there were no differences in fibrinolytic measures between the men and women. Baseline levels of these fibrinolytic markers in both men and women were primarily related to other fibrinolytic measures and body composition, with a smaller contribution from plasma high-density lipoprotein cholesterol (HDL-C) levels. Exercise training reduced t-PA antigen levels in both men and women, but the reduction was significantly greater in men (-1.6 +/- 0.3 versus -0.5 +/- 0.2 ng ml(-1), P = 0.007). Exercise training decreased PAI-1 activity more in men than in women (-2.6 +/- 1.4 versus +0.9 +/- 0.9 IU ml(-1), P = 0.03). Men and women both showed increased t-PA activity with exercise training to the same extent (+0.38 +/- 0.12 versus +0.36 +/- 0.24 U ml(-1)). The changes in fibrinolytic measures with exercise training in men and women were correlated with changes in other fibrinolytic measures, although in men abdominal fat changes were a strong predictor of fibrinolytic changes with training. These findings suggest that training-induced improvements in endogenous fibrinolysis markers are somewhat greater in men compared to women and may be more strongly associated with abdominal obesity in men.

Stimulated Tissue Plasminogen Activator Release as a Marker of Endothelial Function in Humans

The initiation, modulation, and resolution of thrombus associated with eroded or unstable coronary plaques are critically dependent on the efficacy of endogenous fibrinolysis. This is dependent on the cellular function of the surrounding endothelium and vascular wall. In particular, the acute release of tissue plasminogen activator from the endothelium makes an important contribution to the defense against intravascular thrombosis. Here, we describe the rationale and methodology for, and clinical relevance of, assessing acute endothelial tissue plasminogen activator release in humans. The investigation of endothelial fibrinolytic function has the potential to provide major new insights into the pathophysiology of cardiovascular disease, and to shape future therapeutic interventions.

Demonstration of enhanced endogenous fibrinolysis in thrombin activatable fibrinolysis inhibitor-deficient mice

To investigate the importance of thrombin activatable fibrinolysis inhibitor (TAFI) in the stabilization of plasma clots, we have compared fibrinolysis in TAFI-deficient (KO) and wild-type (WT) littermate mice. TAFI-deficient mice were previously generated by targeted gene disruption. The level of TAFI activity generated in plasma from WT mice in the presence of added thrombin and thrombomodulin (activatable TAFI) is twice that of plasma from TAFI heterozygous mice (HET); no activatable TAFI is detected in TAFI KO plasma. In vitro, TAFI KO plasma clots lysed faster than WT plasma clots, and HET plasma clots lysed at an intermediate rate. The rate of clot lysis for KO mice is not changed in the presence of potato carboxypeptidase inhibitor, a specific inhibitor of TAFIa, whereas the WT and HET clot lysis rates are increased in the presence of potato carboxypeptidase inhibitor. C-terminal lysine residues are preserved on partially degraded clots from KO mice, but are absent from partially degraded WT clots. In vivo, in a batroxobin-induced pulmonary embolism model, KO mice displayed a lower retention of fibrin in the lungs than did WT mice. These results are the first demonstration of enhanced endogenous fibrinolysis in an in vivo model without the addition of exogenous thrombolytic.

Isocapnic hyperoxia impairs endogenous fibrinolysis in healthy men

Department of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom

Disseminated intravascular coagulation

Summary Disseminated intravascular coagulation (DIC), a syndrome characterized by systemic intravascular activation of coagulation with widespread fibrin deposition in the circulation, causes a hypercoagulable state, haemorrhagic symptoms and multiple organ failure. It is associated with a variety of clinical conditions. Recent studies have identified several pathogenic pathways involving thrombin generation, diminished physiological anticoagulant systems, increased endogenous fibrinolysis and endothelial dysfunction. A more accurate diagnosis of DIC can be made by the use of a scoring system based on the clinical background of the patient combined with a number of simple laboratory tests. The cornerstone of the management of a patient with DIC is the specific and aggressive treatment of the underlying disease. Novel therapeutic approaches aimed at inhibition of tissue factor mediated activation of coagulation and restoration of physiological anticoagulant pathways need further evaluation. An improved understanding and earlier diagnosis could lead to targeted treatment and improved prognosis.

Resolution of Budd???Chiari syndrome due to activation of endogenous fibrinolysis that may be induced by weight reduction

We describe a 45-year-old female with polycythemia vera and Leiden factor V mutation, who suffered the subacute form of Budd-Chiari syndrome and was treated with anticoagulants and diuretics. Surprisingly, after 3 months clinical signs of Budd-Chiari syndrome resolved; venography disclosed the resolution of thrombosis in the vena cava inferior and hepatic veins. This was associated with considerable increase of endogenous fibrinolytic activity, documented by a substantial change in the euglobulin clot lysis time, and a decrease of plasminogen activator inhibitor antigen and activity. During the disease the patient followed a diet and significantly reduced her body weight. Putting all data together it could be speculated that weight reduction (along with anticoagulants) considerably activated endogenous fibrinolysis, resulting in spontaneous resolution of Budd-Chiari syndrome. The validity of this explanation should be explored in a larger clinical study.

Plasma Fibrinolysis Inhibitor Levels in Acute Stroke Patients with Thrombolysis Failure

Background and PurposeThrombolytics-induced recanalization fails in a significant portion of patients with ischemic stroke, which is partly due to the resistance of clots to lysis by thrombolytic agents. The pretreatment level of endogenous fibrinolysis inhibitors may affect such thrombolysis failure.MethodsWe studied 43 stroke patients whose arterial recanalization had been evaluated by angiography, and whose blood had been obtained prior to the administration of thrombolytic agents. Plasma samples from 34 healthy volunteers were used as normal controls. Plasminogen activator inhibitor type 1 (PAI-1) and thrombin-activatable fibrinolysis inhibitor (TAFI) levels were quantified using an enzyme-linked immunosorbent assay.ResultsArteries were recanalized [Thrombolysis in Myocardial Infarction (TIMI) grade 2 or 3] in 30 patients, but not (TIMI grade 0 or 1) in the other 13. The plasma PAI-1 level was significantly higher in patients without recanalization (nonrecanalization) than in those with recanalization and in normal controls. The TAFI levels did not differ among the groups.ConclusionsThe pretreatment PAI-1 levels are increased in acute stroke patients with thrombolysis failure.

An increase of C-reactive protein is associated with enhanced activation of endogenous fibrinolysis at baseline but an impaired endothelial fibrinolytic response after venous occlusion

The goal of this study was to determine whether chronic inflammation of the vascular wall may be associated with an impaired activation of the fibrinolytic system. Inflammation plays an important role in the initiation and progression of atherosclerosis, and the fibrinolytic system may prevent local thrombus formation. We included 50 patients six months after their first myocardial infarction. Plasma levels of the inflammatory marker C-reactive protein (CRP) were determined at basal conditions, and the fibrinolytic parameters tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) were measured at basal conditions and after a standardized venous occlusion (VO) of the forearm. Patients with high CRP levels (> or =3 mg/l) showed a significantly higher t-PA activity at baseline compared with patients with medium (1 to 2.9 mg/l) and low (<1 mg/l) CRP levels (p <0.005). In contrast, patients with low CRP levels showed a higher increase of t-PA activity (p <0.05) and a higher reduction of PAI-1 activity during VO (p <0.05) compared with patients with medium and high CRP levels. A multivariate analysis that included cardiovascular risk factors and medical treatment showed that CRP is an independent predictor of the t-PA response after a standardized VO. Chronic low-grade inflammation is associated with enhanced activation of endogenous fibrinolysis at baseline but a reduced fibrinolytic response to VO. This impaired endogenous fibrinolytic capacity might be an important contributor to the increased coronary event rate associated with elevated CRP levels.

Comparison of Effects of Different Heparins on Thrombin Activatable Fibrinolysis Inhibitor in Hemodialyzed Patients

Background: Thrombin activatable fibrinolysis inhibitor (TAFI) is a regulator of endogenous fibrinolysis. Heparin is used routinely during dialysis sessions to prevent clot formation in the extracorporeal circuit; therefore the aim of the study was to assess whether unfractionated heparin or low-molecular-weight heparins affect TAFI concentration and activity in hemodialyzed patients. Methods: Dalteparin (n = 16) or enoxaparin (n = 25) were administered before the second hemodialysis session in the week in a single dose, whereas unfractionated heparin (n = 18) was given first as a bolus, then in a pump. We also evaluated thrombin activity (thrombin-antithrombin complexes, prothrombin fragments 1 + 2), TAFI activator, thrombomodulin, a catalyzer of TAFI activation and a marker of endothelial cell injury, and the degree of plasmin generation (plasmin-antiplasmin complexes). Results: TAFI concentration, activity and markers of ongoing coagulation, i.e. prothrombin fragments 1 + 2 and thrombin-antithrombin complexes, were significantly higher in patients anticoagulated with unfractionated heparin when compared to both enoxaparin and dalteparin groups. Thrombin-antithrombin complexes, plasmin-antiplasmin complexes, prothrombin fragments 1 + 2, and thrombomodulin did not differ between patients anticoagulated with dalteparin and enoxaparin. Conclusions: Our results suggest that low-molecular-weight heparins influence TAFI and other hemostatic parameters in hemodialyzed patients to a lesser degree than unfractionated heparin. Increased TAFI is possibly due to thrombin appearance during hemodialysis with unfractionated heparin.

Exercise training enhances endogenous fibrinolysis in peripheral arterial disease

Acute clinical events resulting from atherosclerosis (myocardial infarction, stroke) are associated with impaired endogenous fibrinolysis, the system by which the body lyses inappropriately formed thrombus. Endurance exercise training improves fibrinolysis in normal subjects and those with coronary artery disease. The hypothesis of this study was that exercise training would improve fibrinolysis in subjects with peripheral arterial disease (PAD). Twenty-one men with intermittent claudication (IC-EX) underwent treadmill exercise training for 6 months. Twenty age-matched male subjects with IC were followed for the same period (IC-NONEX). Fibrinolytic activity was measured prior to entry into exercise or "usual care," and at the completion of the study period. Fibrinolysis was quantified by measurement of the activity levels of tissue plasminogen activator (tPA, the activator of fibrinolysis) and its inhibitor plasminogen activator inhibitor-1 (PAI-1), using an amidolytic method. Fibrinolysis, quantified as increased PAI-1 activity, was reduced in both claudicant groups relative to healthy controls at baseline. After 6 months of exercise, subjects in the IC-EX group experienced significant improvements in fibrinolytic activity, manifested as a 23% decrease in PAI-1 activity and a 28% increase in tPA activity. No changes occurred in the IC-NONEX group. In the IC-EX group, subjects with the highest initial PAI-1 values experienced the greatest decreases in PAI-1 activity and thus the greatest benefit from exercise. Patients with PAD have impaired fibrinolytic activity, manifested primarily as increases in the inhibitor of fibrinolysis, PAI-1. Six months of exercise training reduced these impairments, and may serve as an intervention to reduce cardiovascular mortality and morbidity in these patients.

Admission fibrinolytic profile is associated with symptomatic hemorrhagic transformation in stroke patients treated with tissue plasminogen activator.

Symptomatic intracranial hemorrhage (SICH) is the most feared complication after tissue plasminogen activator (tPA) stroke treatment. Endogenous fibrinolysis inhibitors play an essential role in the coagulation/fibrinolysis balance and may be involved in the bleeding process. We aim to determine the predictive value of pretreatment levels of fibrinolysis inhibitors (PAI-1, lipoprotein(a), TAFI, and homocysteine) on SICH. Consecutive tPA-treated stroke patients with middle cerebral artery occlusion were studied. Baseline blood samples were obtained just before tPA administration and fibrinolysis inhibitors were determined. A second computed tomography (CT) scan was obtained at 24 hours or when a neurological worsening occurred to rule out SICH. Seventy-seven patients (40% women, age 75 years) were studied. Median admission National Institutes of Health Stroke Scale was 17 (range, 7 to 22) and mean time to treatment was 160 minutes. Six patients (7.9%) presented with a SICH. In analyses based on clinical and CT variables, no relation could be found with SICH. When laboratory data were analyzed, patients who experienced SICH showed lower baseline PAI-1 (21.7+/-3.5 ng/mL versus 31.8+/-12.1 ng/mL; P<0.01) and higher TAFI (216.7+/-78.4% versus 162.1+/-54.2%; P=0.03). Homocysteine and lipoprotein(a) were not related to SICH. The only factors associated with SICH were TAFI >180% (OR, 12.9; CI, 1.41 to 118.8; P=0.02) and PAI-1 <21.4 ng/mL (OR, 12.75; CI, 1.17 to 139.2; P=0.04). The combination of admission PAI-1 <21.4 ng/mL and TAFI >180% had a sensibility of 75% and a specificity of 97.6% (P<0.01) predicting SICH, with a positive predictive value of 75% and negative predictive value of 97.6%. Baseline PAI-1 and TAFI levels predict SICH after stroke tPA therapy. In the future, these biomarkers could be used to improve thrombolysis safety.

Established and emerging plasma biomarkers in the prediction of first atherothrombotic events.

In the current Adult Treatment Panel guidelines for cardiovascular risk detection,1 the plasma-based markers recommended for use in global risk assessment or in the definition of the metabolic syndrome are low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol, and triglycerides. It is widely recognized, however, that more than half of all future vascular events occur in individuals without overt hyperlipidemia. For example, in a recent large-scale analysis of >27 000 healthy American women, 77% of all future events occurred in those with LDL-C levels <4.14 mmol/L (<160 mg/dL) and 45% of all events occurred in those with LDL-C values <3.36 mmol/L (<130 mg/dL).2 Although risk-scoring systems that additionally evaluate traditional risk factors such as smoking, hypertension, and diabetes greatly improve risk prediction, multiple studies demonstrate that 20% to 25% of all future events occur in individuals with only 1 of these factors.3 Moreover, the prevalence of traditional risk factors is almost as high in those without disease as in affected individuals.4 As our understanding of the pathobiology of atherothrombosis has improved, researchers have attempted to evaluate the activities of these biological processes by measuring markers in plasma or urine (ie, biomarkers). Indeed, a series of candidate biomarkers reflecting inflammation, hemostasis, thrombosis, and oxidative stress have been evaluated as potential clinical tools in an effort to improve risk prediction. To be useful in a clinical setting, the biomarker of interest must be shown in multiple prospective studies to predict future cardiovascular events. Retrospective studies are of limited value because they are prone to bias and cannot exclude the possibility that the particular biomarker is elevated as a result of, rather than a cause of, disease. To be used widely, the proposed biomarker should provide independent information on risk or prognosis beyond that available from global assessment algorithms such …

Effects of nicorandil on endogenous fibrinolytic capacity in patients with coronary artery disease.

Nicorandil is a hybrid-type anti-anginal drug that combines a K(ATP) channel opener and a nitric oxide donor. Recently the IONA study reported that nicorandil improves the prognosis of patients with stable angina pectoris. To examine the effects of nicorandil on endogenous fibrinolysis, plasma concentrations of tissue-type plasminogen activator (t-PA) antigen, type-1 plasminogen activator inhibitor (PAI-1) antigen and PAI activity were measured in consecutive 11 patients (7 men and 4 women, mean age 63 years, ranges 41-84 years) with coronary artery disease. Nicorandil (15 mg/day) was administered orally to each patient for 2 weeks. Venous blood samples were obtained from each patient before and after the administration of the drug in the early morning before eating. There were no significant changes in the plasma concentrations of t-PA (12.4+/-1.9 to 9.8+/-1.5) or PAI-1 (26.3+/-3.9 to 21.5+/-4.9) antigens (ng/ml, mean +/- SEM) before and after nicorandil administration. On the other hand, the plasma activity of PAI (IU/ml, mean +/- SEM) decreased significantly after the treatment (12.9+/-3.2 to 5.6+/-1.9, p=0.039). It is well known that PAI activity determines the whole fibrinolytic capacity and oral administration of nicorandil decreased PAI activity in patients with coronary artery disease. This finding suggests that nicorandil improves the fibrinolytic capacity and may reduce the risk of coronary thrombus formation in such patients.

Enhancement of endogenous fibrinolysis does not reduce local fibrin deposition, but modulates inflammation upon intestinal ischemia and reperfusion.

This study investigated the contribution of endogenous suppression of fibrinolysis and increased fibrin deposition to intestinal dysfunction and injury in a rat model of intestinal ischemia/reperfusion (I/R), as fibrinolytic inhibition may lead to thrombotic obstructions that compromise microcirculation and promote intestinal injury. Circulatory fibrinolysis was enhanced by intravenous administration of recombinant tissue plasminogen activator (rt-PA) or by inhibition of PAI-I by administration of MA-33H1F7. Coagulation and fibrinolysis parameters obtained from portal blood were correlated to fibrin deposition (determined by anti-rat fibrin antibody staining), intestinal function (glucose/water clearance) and intestinal injury (histological evaluation by Park/Chiu score). Enhanced circulatory fibrinolytic activity, as evidenced by increased portal plasma plasminogen activator activity, elevated fibrin degradation products and decreased levels of PAI-I, did not reduce mucosal fibrin deposition and microthrombosis in postischemic intestinal tissue. Furthermore, rt-PA or anti-PAI-I antibody administration did not attenuate I/R-induced intestinal injury or dysfunction, as demonstrated by intestinal histopathology scores of 4.8+/-0.2 and 4.7+/-0.3 (control I/R group 4.7+/-0.2) and glucose clearances of 47+/-6 and 46+/-9 micro L/min g (control I/R group 30+/-8 micro L/min. g) after 40 minutes of intestinal ischemia and 3 hours of reperfusion, respectively. However, both interventions resulted in decreased levels of interleukin-6, which may indicate fibrin-induced modulation of inflammation. Attempts to enhance the fibrinolytic activity (either by rt-PA or by anti-PAI-I administration), indicated by increased portal plasma levels of released FDP, failed to decrease mucosal fibrin deposition and to attenuate intestinal I/R injury. Based on our observations and previous reports, the contribution of suppressed endogenous fibrinolysis to microcirculatory fibrin deposition and I/R-injury may be of limited importance.

The role of d-dimer as first marker of thrombophilia in women affected by sterility: implications in pathophysiology and diagnosis of thrombophilia induced sterility

BackgroundD-dimer is considered a marker of hypercoagulable state and of endogenous fibrinolysis, so increased d-dimer is detectable in patients affected by thrombosis. Yet, several studies showed that also infertility, in particular secondary infertility due to recurrent fetal losses, has been often related to thrombotic events, in particular in women carrying thrombotic risk factors such as inherited thrombophilia (MTHFRC677T, PTHRA20210G, Factor V Leiden polimorphisms and/or inhAfter this screening we selected 39erited protein C, protein S, AT III deficiency) or acquired thrombophilia (primary antiphospholipid syndrome, acquired protein C, protein S, AT III deficiency, drugs induced thrombophilia). However, because its high predictive negative value in case of suspected thrombosis, increased d-dimer has been often associated to subclinical thrombophilia. The aim of this study is to investigate the role of d-dimer as first marker of thrombophilia in women affected by unexplained infertility and subsequently to search the cause of increased d-dimer, such as inherited and/or acquired thrombophilia.Patients and MethodsWe selected 79 patients with unexplained primary or secondary infertility. We excluded 40 patients affected by hydrosalpinx, uterine fibroids, uterine malformations, endocrinological and immunological diseases, luteal insufficiency, cytogenetical alterations. All remaining 39 patients were tested for d-dimer and divided in two groups: the patients of group A (25 patients) showed increased plasma d-dimer, in group B were included 14 patients with normal plasma level of d-dimer. After this step all 39 patients were screened for MTHFRC677T, PTHRA20210G, Factor V Leiden polimorphisms, protein C, protein S, AT III, anticardiolipin IgM and IgG, lupus anticoagulant. In the control group were included 15 age matched women without sterility problems referred to our outpatient's section of vascular medicine for suspected deep venous thrombosis.Statistical analysis was based on χ2 test, differences were considered to be significant if p < 0.05.ResultsD-dimer was increased in 25/39 and 20/25 showed inherited/acquired thrombophilia while patients with normal d-dimer showed inherited/acquired thrombophilia in 7/14 (p: < 0.05, s).DiscussionD-dimer is a well known marker of hypercoagulable state, in particular its high predictive negative value in case of suspected thrombosis has been recognised by several reports. Yet, increased d-dimer has been identified also for subclinical thrombophilia besides for vascular thrombosis. Our data, in fact, for the first time suggest an interesting role of d-dimer to identify women affected by unexplained primary or secondary infertility and thrombophilia. So, probably there is a role for d-dimer in these subjects for its predictive positive value. Of course, further data on large based population are needed to confirm our results, because these findings may speed up a diagnostic screening in these patients also for a good cost/effectiveness of this test.

Blood coagulation and fibrinolysis after long-duration treadmill exercise controlled by individual anaerobic threshold.

For rehabilitation training it is recommended that the intensity of exercise should be clearly below the individual anaerobic threshold (IAT). We investigated blood coagulation, particularly endogenous thrombin potential (ETP) and fibrinolysis following a standardized treadmill (TR) ergometer test at 90% IAT for 60-120 min. Sixteen healthy male non-smokers underwent the TR test. Blood samples were taken after a 30-min rest, immediately after exercise, and 2 h after exercise completion. Extrinsic and intrinsic total (TTP(ex+in)) and endogenous (ETP(ex+in)) thrombin potential, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex (TAT), plasmin-alpha2-antiplasmin complex (PAP), D-dimer, tissue plasminogen activator antigen and activity (tPA-AG and tPA-ACT) and plasminogen activator inhibitor type 1 antigen and activity (PAI-1-AG and PAI-1-ACT) were measured. Immediately after TR, F1+2, TAT and TTP(ex+in) were increased ( P<0.05) while ETP(ex+in) remained unchanged. In contrast, PAP, D-dimer, tPA-AG, tPA-ACT ( P<0.05) were distinctly enhanced while PAI-1-ACT was decreased ( P<0.05) immediately after exercise. The changes in tPA-AG, tPA-ACT, and PAI-1-ACT were reversed to nearly baseline while the enhancement in PAP and D-dimer was prolonged by more than 2 h after exercise. Long-duration exercise between 60 and 120 min controlled by IAT (90%) on a TR ergometer only implicates a small increase in thrombin generation markers and total (free and alpha(2)-macroglubulin-bound thrombin), but not in endogenous (free) thrombin potential alone. In contrast, fibrinolysis is distinctly increased after this type of exercise. Endurance exercise with an intensity below 90% IAT and a duration below 2 h generates a more favourable condition for fibrinolysis than for blood coagulation in healthy young subjects. Data are given as mean (SD).