Impaired Fibrinolytic Activity Research Articles

Exploring the Therapeutic Potential of Apigenin in Obesity-Associated Fibrinolytic Dysfunction: Insights From an Animal Study.

Obesity (Obe) is a chronic metabolic disorder usually complicated by impaired fibrinolytic activity. Apigenin (Api) is one of the flavonoids that have anti-adiposity effects. This study aimed to explore the therapeutic potential of Api in high-fat diet (HFD)-induced obese rats. Twenty-four Wistar adult male rats were randomly allocated into control group, supplemented with a normal pellet diet (NPD); Api group, supplemented with Api (10 mg/kg) for eight weeks; Obe group, obesity was induced byfeeding HFD for eight weeks; and Obe/Api group, obese rats supplemented with Api for eight weeks. Body mass index (BMI), homeostatic model assessment of insulin resistance (HOMA-IR), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), total superoxide dismutase(t-SOD) activity, and plasminogen activator inhibitor-1 (PAI-1) were measured. Compared to the control group, Obe group exhibited a significant increase in BMI, HOMA-IR, TNF-α, MDA, and PAI-1. These results were also associated with a significant decrease in serum t-SOD activity. Supplementation of Api alleviated the measured deteriorated parameters and ameliorated visceral adiposity in obese rats. This study provides compelling evidence regarding a promising role for Api in ameliorating the impairment of fibrinolytic activity in an Obe animal model. The observed effects are likely mediated through Api's anti-obesity properties, as well as its indirect modulation of PAI-1, oxidative stress, and inflammation. Future clinical studies are recommended that may make benefit of the preclinical therapeutic use of apigenin in obesity-associated fibrinolytic dysfunctions.

OP0059 PROFOUND ANTICOAGULANT EFFECTS OF INITIAL ANTIRHEUMATIC TREATMENTS IN EARLY RHEUMATOID ARTHRITIS PATIENTS: A NORD-STAR SPIN-OFF STUDY

BackgroundPatients with rheumatoid arthritis (RA) are at an increased risk of venous thromboembolism. Thus far, there have not been any comparative studies investigating the effects of initial antirheumatic treatments in (very) early RA patients.ObjectivesTo assess the effects of different initial treatments on hemostatic parameters in patients with early RA.MethodsNORD-STAR is an international, multicentre, open-label, assessor-blinded, phase 4 study where patients with newly diagnosed RA started methotrexate (MTX) and were randomised 1:1:1:1 to a) conventional treatment (either prednisolone tapered to 5mg/day, or sulfasalazine combined with hydroxychloroquine and intra-articular corticosteroids), b) certolizumab pegol, c) abatacept, d) tocilizumab1. This study is a spin-off from the main NORD-STAR study extensively investigating hemostatic system in 24 per protocol consecutive Dutch participants at baseline, 12 weeks and 24 weeks after the start of the treatment. Statistical analysis was done using paired samples t-test in SPSS version 28.ResultsThe mean age of investigated patients was 51.8 (± 12.7) years and 58.3% were female. At baseline patients had an average DAS28 score of 4.6 (± 0.9) and had elevated levels of investigated coagulation biomarkers: Factor 1 + 2, fibrinogen, D-dimer and parameters of the two global hemostatic assays, i.e. endogenous thrombin potential (ETP) and overall hemostasis potential (OHP). These biomarkers decreased significantly at 12 and 24 weeks in patients in all groups (Table 1). Overall fibrinolytic potential (OFP) was decreased and clot lysis time (CLT) was prolonged at baseline, demonstrating impaired fibrinolytic activity in early RA. The reduction of coagulation parameters was significantly higher in biological treatment arms in comparison to the standard MTX treatment arm. In addition, tocilizumab was more effective compared to certolizumab and abatacept, (Figure 1), which was expected considering the direct inhibitory effect of this drug on the IL-6 synthesis and consequently the coagulation activation as well. After 24 weeks of treatment with methotrexate and tocilizumab, the average fibrinogen of patients was reduced by 63% vs 31% and 36% in the certolizumab and abatacept groups, respectively. The changes in DAS-28 and the changes in fibrinogen had a correlation of 0.385 which did not reach statistical significance.Table 1.Measurements are marked with * if p<0.05, ** if p<0.01 and *** if p<0.001BaselineW12W24Factor 1 + 2 (pmol/L)270.25 (149.4)190.36 (108.6)**179.52 (85.3)***Fibrinogen (g/L)4.64 (1.5)3.61 (1.6)**2.63 (1.2)***D-dimer (mg/L)2.17 (3.0)0.33 (0.23)**0.29 (0.2)**OHP (Abs-sum)157.38 (64.9)120.62 (68.7)*100.49 (53.8)***OCP (Abs-sum)369.52 (58.8)305.04 (101.7)*275.91 (83.1)***OFP (%)57.97 (13.1)63.20 (12.7)*65.25 (11.4)***Lag time (s)304.5 (71.1)306.8 (71.8)312.7 (65.4)Slope0.07 (0.02)0.066 (0.03)0.094 (0.12)Max Abs1.17 (0.3)1.00 (0.4)*0.91 (0.3)**CLT (s)1405 (356)1317 (377)1231 (320)**ETP (nM*min)1480 (471)1395 (395)*1337 (429)*Peak (nM)231 (78)223 (68)223 (74)Lagtime (min)4.06 (2.1)3.28 (1.2)**2.87 (1.0)***ttPeak (min)7.40 (2.2)6.61 (1.5)*6.13 (1.4)**Figure 1.ConclusionOur results indicate an enhanced coagulation and fibrinolytic impairment in newly diagnosed RA patients. Effective antirheumatic treatments reduce this hemostatic imbalance, with significantly more pronounced effects of biologic drugs compared to conventional (MTX+glucocorticoids) treatment.

Association between the triglyceride-glucose index and a procoagulant state in coronary artery disease

Abstract Background Metabolic risk factors and a procoagulant state represent major drivers of atherothrombosis. In terms of metabolic risk factors, the triglyceride-glucose (TyG) index has recently emerged as a marker of metabolic syndrome and an independent predictor of cardiovascular outcomes in patients with coronary artery disease (CAD). In terms of a procoagulant state, previous research suggests that CAD is associated with increased coagulation and impaired fibrinolytic activity, which may contribute to atherothrombotic events. We hypothesized that metabolic risk, as determined by TyG index, may be an important driver of hemostatic derangements in patients with CAD. Purpose We sought to establish a possible association between the overall hemostatic, coagulation and fibrinolytic potentials (OHP, OCP and OFP), and the TyG Index in patients with CAD. Methods Consecutive patients after a recent myocardial infarction (within 90 days from inclusion) had fasting blood samples withdrawn. OHP, OCP and OFP were determined with a previously validated method, using thrombin and recombinant tissue-type plasminogen activator, by absorbance measurements at 405 nm in 1 minute intervals for 40 minutes. Areas under the curve were constructed for OHP and OCP with the obtained measurements, OFP was calculated as the difference between the two aforementioned areas: OFP = [(OHP – OCP) / OCP] x 100 (%). Baseline data, cardiovascular risk factor profile and standard laboratory tests were collected. TyG index was calculated using the previously validated formula: TyG index = ln [triglyceride (mg/dL) x glucose (mg/dL) / 2]. Proportions were compared using the chi-squared test, linear regression models were constructed for the multivariate analysis. Results We included 117 patients (mean age 56±10 years, 20% women). Arterial hypertension was present in 86 (73.5%), diabetes mellitus in 10 (8.5%), dyslipidemia in 75 (64.1%), family history in 46 (39.3%) patients; 54 (46.2%) were active smokers (within 2 years). Median OHP was 8.0 (interquartile range [IQR] 2.9), OCP was 22.6 (IQR 6.2), OFP was 66.0 (IQR 11)%. The TyG index was a strong univariate predictor of OCP (Beta 2.26 [0.282–4.242] p=0.026), and retained its statistical significance after multivariate adjustment for sex, age and traditional risk factors (R2 0.23; ANOVA for regression p<0.001; Beta 1.98 [0.13–3.84], p=0.036). Conclusion The TyG index, a marker of metabolic syndrome, is an independent predictor of a procoagulant state in CAD, as determined by the OCP. Our findings suggests that the metabolic syndrome may be an important driver of atherothrombotic risk in patients with CAD. Funding Acknowledgement Type of funding sources: None. Correlation between TyG index and OCP

Severe SARS-CoV-2 Infection Inhibits Fibrinolysis Leading to Changes in Viscoelastic Properties of Blood Clot: A Descriptive Study of Fibrinolysis in COVID-19.

Accumulating evidence indicates toward an association between severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and procoagulatory state in blood. Thromboelastographic investigations are useful point-of-care devices to assess coagulation and fibrinolysis. We investigated the hypothesis that the procoagulatory state in COVID-19 patients is associated with impaired fibrinolysis system. Altogether, 29 COVID-19 patients admitted to normal wards or to the intensive care unit (ICU) were included in this descriptive study. Whole blood samples were investigated by thromboelastography to assess coagulation and fibrinolysis. Additionally, standard routine coagulation testing and immunoassays for factors of fibrinolysis as plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), plasminogen activity and α2-antiplasmin (A2AP) were performed. A significantly increased lysis resistance and a significantly longer time of lysis after adding tissue plasminogen activator were observed in blood samples from ICU COVID-19 patients compared with healthy controls (maximal lysis: 3.25 ± 0.56 vs. 6.20 ± 0.89%, p = 0.0127; lysis time: 365.7 ± 44.6 vs. 193.2 ± 16.3 seconds, p = 0.0014). PAI-1 activity was significantly higher in plasma samples of ICU COVID-19 patients (PAI-1: 4.92 ± 0.91 vs. 1.28 ± 0.33 U/mL, p = 0.001). A positive correlation between the activity of PAI-1 and lysis time of the formed clot (r = 0.70, p = 0.0006) was observed. Our data suggest that severe SARS-CoV-2 infection is associated with impaired fibrinolytic activity in blood, where fibrinolytic inhibitors are elevated leading to an increased resistance to clot lysis. Thromboelastography could offer a tool to investigate the contribution of the fibrinolytic status to the procoagulatory condition in COVID-19.

Glycated hemoglobin and subsequent risk of microvascular and macrovascular complications

Diabetes mellitus (DM) is a global health problem and its prevalence is constantly increasing over the past several decades. Measurement of glycated hemoglobin (HbA1c) is widely accepted as indicator of long-term glycemic exposure and used as tool for the diagnosis and management of DM. Patients with DM are at heightened risk of both microvascular and macrovascular complications which affect the several organs including skin, heart, brain, eyes, and kidneys. There is a common etiology between hyperglycemia and vascular diseases. The mechanism of pathogenesis starts with formation and accumulation of advanced glycation end product, impaired vasodilatory response, smooth muscle cell dysfunction, overproduction of endothelial growth factors, chronic inflammation, hemodynamic dysregulation, impaired fibrinolytic activity, and enhanced platelet aggregation. These events decrease the diameter of the vessel and initiate the lesion of the vessel wall followed by local ischemia and tissue damage.

Main Features of Impaired Fibronolytic and Protolytic Activity of Blood Plasma in Patients with Osteoarthritis Depending on Comorbidity

The objective of the research was to study the features of impaired fibrinolytic and proteolytic activity of blood plasma in patients with osteoarthritis (OA), depending on the age levels of comorbidity.Material and methods. The age features of comorbid processes prevalence in 120 patients with OA were clinically studied, fibrinolytic and proteolytic activity of blood, levels of fibrinogen and C-reactive protein were also studied using biochemical methods.Results. Comorbidity in patients with OA at the age under 50 was established low. The level of comorbidity increases to at the age of 51-60, after 60 years the phenomenon of comorbidity is more significant by frequency and severity. The diseases of the cardiovascular system dominated, including metabolic syndrome, diseases of the digestive tract and kidneys were less frequent. Cardiovascular risk (CVR) levels were high after the age of 50, gastrointestinal risk was less frequent. Fibrinolysis minor disorders were observed in patients with low comorbidity, namely fibrinolytic and proteolytic activity of blood as a part of high CVR progressively deteriorated and the level of fibrinogen and C-reactive protein increased in the patients at the age after 50 (especially 60) on the background of high comorbidity levels. Conclusions. The level of comorbidity and CVR increased in patients with OA with age, increase in disease severity and duration. These phenomena were accompanied by progressive disorders in fibrinolytic and proteolytic activity of the blood, increased levels of fibrinogen and C-reactive protein as one of the components of CVR.

Thrombophilia and Thrombotic Disorders in Newborns

incidence in children is estimated at about 0.7 cases of venous thrombosis per 100,000 population, 1.0 of stroke and 0.1 of myocardial infarction, while in adults the incidence reported is 74.2, 45.4 and 175.6 cases respectively. The lower incidence of venous thromboembolic disease (VTE) in children compared to adults is mainly due to the integrity of the vessels and the enhanced anticoagulant activity of the endothelium, and additionally to the reduced capacity of thrombin generation, inactivation of thrombin by a2-macroglobulin, the increased concentration of which, counterbalances the physiological deficiency of antithrombin and protein C / S, to the decreased levels of tissue factor in cord blood and concentration of eicosanoids and proteoglycans, depending on age [2,3]. The incidence of thromboembolic events (VTE) is higher in infants than in older children. About 10% of VTE occur in the first four weeks of life, frequently in critically ill neonates (2.4 symptomatic VTE cases per 1000 admissions in Neonatal Intensive Care Units-NICU). The incidence of symptomatic venous thrombosis (VTE) in newborns is 5.1/100,000 live births [4]. Although it is considered that the thromboembolic events are under diagnosed, newborns are nearly 40 times more likely to suffer a VTE than during the entire childhood, but certainly the above probability is significantly less than that referred in adults [5,6]. The hemostatic system both in preterm and full-term newborns differs significantly from that of older children and much more than that of adults, however, normally in newborns there is a balance in between bleeding or thrombosis diathesis. The increased incidence of VTE in critically ill infants is attributed to the derangement of equilibrium of the hemostatic mechanism, because of the lower concentrations of natural inhibitors and impaired fibrinolytic activity and also due to elevated levels of factor von Willebrand [7]. The combination of the above with both the high viscosity of blood due to the high hematocrit and the small vascular diameter of newborns results in low capillary flow, especially on coexistence of dehydration or hypercoagulable state because of infection or prematurity. Furthermore, the use of venous or arterial catheters is one of the major risk factors for thrombosis in neonatal period. Nowadays, 15% of infants in NICU and at least 50% of preterm infants of birth weight 90% of cases) or congenital risk factors. For the manifestation of VTE in neonates, several coincidental risk factors (variety of underlying diseases or triggering events of the child or maternal) are required. Studies so far, have not revealed thrombophilic factors contributing to the occurrence of asymptomatic or symptomatic VTE [8]. Genetic factors are related to the risk of VTE in children and newborns but no causal relationship is established for most of them [9]. The frequency of presence of thrombophilic factors in children with VTE is reported 13-79% in several studies. The huge discrepancy is attributed mainly to variation in the design of the trials, the difficulty in the definition of related prothrombotic disorders, and also to the small number and different patient populations. Regarding thromboembolic events of central venous system (CNS) [10], and although the high frequency of idiopathic arterial ischemic events (AIS) [11], the prevalence of thrombophilic factors varies in different studies from 20 to 50%, while increased appears the possibility of the presence of congenital thrombophilia in neonates with renal, hepatic or portal vein thrombosis [12]. Furthermore, maternal thrombophilia has been associated with the occurrence of perinatal AIS, venous sinus thrombosis or renal vein thrombosis [13]. However, in neonates there is scepticism about the interpretation of results of the various studies due to the complexity of the mechanism of hemostasis and the interaction of several acquired factors. Thrombosis in neonates is generally a multifactorial process [14]. Future studies may clarify both causative background and therapeutic choices in this group of patients.

Urinary albumin excretion and progression of renal disease with impaired fibrinolytic activity in type 2 diabetes mellitus

Diabetic nephropathy is one of the major causes of end-stage renal disease. As impaired fibrinolysis can increase renal fibrosis, we investigated the relationship of impaired fibrinolysis, as assessed by the ratio of plasminogen activator inhibitor-1 ( PAI-1) to tissue-type plasminogen activator (t-PA) with urinary albumin excretion ( UAE) and renal disease progression in type 2 diabetes. A total of 50 patients with type 2 diabetes and 10 healthy control individuals were included in the study. Participants were subdivided according to UAE. Group 1 (G1) represented control individuals. Group 2 (G2) included patients without albuminuria. Group 3 (G3) included patients with microalbuminuria. Group 4 (G4) included patients with macroalbuminuria. Creatinine clearance and UAE were calculated. PAI-1 and t-PA were measured using an enzyme-linked immunosorbent assay kit, and the PAI-1/t-PA ratio was calculated as an index of impaired fibrinolysis. PAI-1 was highly elevated significantly in G4 when compared with the other groups, with a mean of 87.40 ± 17.03 IU/ml against 28.00 ± 6.98 IU/ml in G1, 46.4 ± 7.99 IU/ml in G2, and 64.10 ± 18.26 IU/ml in G3 (P < 0.001). Also, the serum level of t-PA in G4 was highly elevated significantly when compared with G1 and G2 with means of 16.85 ± 5.63 IU/ml against 7.95 ± 1.91 IU/ml and 10.45 ± 2.63 IU/ml, respectively (P < 0.001). The ratio of PAI-1/t-PA in G4 was significantly higher when compared with G1 (mean of 5.94 ± 2.81 against 3.54 ± 0.43; P = 0.01). PAI-1 and t-PA showed a significant positive correlation with UAE. Receiver operating characteristics curve analysis revealed that only PAI-1 and t-PA were significant discriminated factors for microalbuminuria and macroalbuminuria (P < 0.001). Serum levels of PAI-1 and t-PA and the PAI-1/t-PA ratio were significantly increased in diabetic patients with higher UAE. Impaired fibrinolysis and increased UAE were associated with renal disease progression.

Decreased Insulin Sensitivity and Impaired Fibrinolytic Activity in Type 2 Diabetes Patients and Nondiabetics with Ischemic Stroke.

We analyzed (a) insulin sensitivity (IS), (b) plasma insulin (PI), and (c) plasminogen activator inhibitor-1 (PAI-1) in type 2 diabetes (T2D) patients with (group A) and without (group B) atherothrombotic ischemic stroke (ATIS), nondiabetics with ATIS (group C), and healthy controls (group D). IS was determined by minimal model (Si). Si was lower in A versus B (1.18 ± 0.67 versus 2.82 ± 0.61 min−1/mU/L × 104; P < 0.001) and in C versus D (3.18 ± 0.93 versus 6.13 ± 1.69 min−1/mU/L × 104; P < 0.001). PI and PAI-1 were higher in A versus B (PI: 19.61 ± 4.08 versus 14.91 ± 1.66 mU/L; P < 0.001, PAI-1: 7.75 ± 1.04 versus 4.57 ± 0.72 mU/L; P < 0.001) and in C versus D (PI: 15.14 ± 2.20 versus 7.58 ± 2.05 mU/L; P < 0.001, PAI-1: 4.78 ± 0.98 versus 3.49 ± 1.04 mU/L; P < 0.001). Si correlated with PAI-1 in T2D patients and nondiabetics, albeit stronger in T2D. Binary logistic regression identified insulin, PAI-1, and Si as independent predictors for ATIS in T2D patients and nondiabetics. The results imply that insulin resistance and fasting hyperinsulinemia might exert their atherogenic impact through the impaired fibrinolysis.

Polymorphisms in the fibrinolytic pathway genes and the risk of recurrent spontaneous abortion

Impaired fibrinolytic activity is implicated in the pathogenesis of recurrent spontaneous abortion (RSA). This case-control study assessed the prevalence of polymorphisms in fibrinolytic system genes in RSA. Cases comprised 202 Sinhalese women who had experienced at least two first-trimester spontaneous abortions and had no living children; controls were 202 women with no history of spontaneous abortion and two or more living children. The groups were matched for age and ethnicity. DNA was genotyped using the Sequenom MassARRAY system. The PLAUR rs4251923 A (OR 95% CI 2.3 [1.3 to 4.0]), SERBP2 rs6098 A (OR 95% CI 1.4 [1.1 to 1.9]) and SERBP2 rs6103 C alleles (OR 95% CI 1.4 [1.1 to 1.9]) were increased in the RSA group compared with controls. The prevalence of PLAUR rs4251923/ SERBP2 rs6098/ SERBP2 rs6103 GG/AA/CC (OR 95% CI 2.4 [1.2 to 4.9], GA/GA/GC(OR 95% CI 3.9 [1.3 to 11.2]), GA/AA/CC (OR 95% CI 2.9 [1.0 to 8.6] and GA/GG/GG (OR 95% CI 21.3 [1.1 to 410.3]) genotypes were also increased in cases. Polymorphisms in the fibrinolytic system genes are associated with RSA in Sinhalese women. These likely impair implantation.

C0481: Active Plasminogen Activator Inhibitor-1 (PAI-1) Concentrations are Increased in Patients with a Venous Thromboembolism (VTE)

Background: Impaired fibrinolytic activity is associated with an increased risk for venous thromboembolism (VTE). Both activated thrombin activatable fibrinolysis inhibitor (TAFI) and active plasminogen activator inhibitor-1 (PAI-1) attenuate fibrinolysis. Activated TAFI cleaves C-terminal lysine residues of fibrin thereby hampering plasmin generation whereas active PAI-1 inhibits plasminogen activator through complex formation. Aim: Analyze the role of fibrinolysis in patients diagnosed with VTE by comparing TAFI and PAI-1 plasma levels with healthy controls (HC). Methods: Plasma of 102 patients diagnosed with VTE was collected after the VTE event in a time range of 10 to 2868 days with a median of 163 days. Plasma parameters (intact TAFI, activation peptide of TAFI (AP, marker for the extent of TAFI activation), total PAI-1 and active PAI-1) of VTE patients were measured using in-house developed ELISAs and compared with plasma parameters of 113 HC. VTE patients had either a deep vein thrombosis (DVT), a pulmonary embolism (PE) or both (DVT+PE). Results: Median [interquartile range] active PAI-1 and AP concentrations were significantly increased in VTE patients compared to HC (20.8 ng/ml [9.6–37.8] vs. 6.2 ng/ml [3.6–9.7], p vs. 314ng/ml [257–376], p = 0.0027, respectively). The type of VTE (PE, DVT or PE+DVT) had no impact on PAI-1 and/or TAFI levels. Neither did the days between diagnosis of the VTE and plasma sampling. ROC analyses revealed that active PAI-1 was the best parameter to discriminate VTE patients from healthy controls (Area Under Curve (AUC) = 0.84, 95% confidence interval 0.79 to 0.90). Conclusions: Preliminary data show thatactive PAI-1 may function as a good biomarker to distinguish VTE patients from healthy subjects. In a next step the association of other cardiovascular risk factors such as recurrent VTE, age, body mass index, immobilization, contraceptive use, . . . , with PAI-1 and TAFI levels will be analyzed using multivariate analyses.

C0535: Coagulation Factor XII Protease Domain Crystal Structure Reveals a Novel Zymogen Triad

Background: Impaired fibrinolytic activity is associated with an increased risk for venous thromboembolism (VTE). Both activated thrombin activatable fibrinolysis inhibitor (TAFI) and active plasminogen activator inhibitor-1 (PAI-1) attenuate fibrinolysis. Activated TAFI cleaves C-terminal lysine residues of fibrin thereby hampering plasmin generation whereas active PAI-1 inhibits plasminogen activator through complex formation. Aim: Analyze the role of fibrinolysis in patients diagnosed with VTE by comparing TAFI and PAI-1 plasma levels with healthy controls (HC). Methods: Plasma of 102 patients diagnosed with VTE was collected after the VTE event in a time range of 10 to 2868 days with a median of 163 days. Plasma parameters (intact TAFI, activation peptide of TAFI (AP, marker for the extent of TAFI activation), total PAI-1 and active PAI-1) of VTE patients were measured using in-house developed ELISAs and compared with plasma parameters of 113 HC. VTE patients had either a deep vein thrombosis (DVT), a pulmonary embolism (PE) or both (DVT+PE). Results: Median [interquartile range] active PAI-1 and AP concentrations were significantly increased in VTE patients compared to HC (20.8 ng/ml [9.6–37.8] vs. 6.2 ng/ml [3.6–9.7], p vs. 314ng/ml [257–376], p = 0.0027, respectively). The type of VTE (PE, DVT or PE+DVT) had no impact on PAI-1 and/or TAFI levels. Neither did the days between diagnosis of the VTE and plasma sampling. ROC analyses revealed that active PAI-1 was the best parameter to discriminate VTE patients from healthy controls (Area Under Curve (AUC) = 0.84, 95% confidence interval 0.79 to 0.90). Conclusions: Preliminary data show thatactive PAI-1 may function as a good biomarker to distinguish VTE patients from healthy subjects. In a next step the association of other cardiovascular risk factors such as recurrent VTE, age, body mass index, immobilization, contraceptive use, . . . , with PAI-1 and TAFI levels will be analyzed using multivariate analyses.

Increased thrombotic and impaired fibrinolytic response to acute exercise in patients with essential hypertension: The effect of treatment with an angiotensin II receptor blocker

Essential hypertension (EH) is characterised by increased thrombotic tendency and impaired fibrinolytic activity. However, exercise-induced changes in coagulation and fibrinolysis have not yet been clarified. We aimed at determining thrombotic and fibrinolytic activity during exercise in patients with EH pre and post treatment with an Angiotensin II receptor blocker. Study 1 consisted of 30 untreated hypertensive (UH) and 15 normotensive (NT) individuals. The UH individuals who received treatment were included in study 2 and were followed up after a 3-month treatment period with valsartan. Thrombin-antithrombin (TAT) complexes and human plasminogen activator inhibitor-1 (PAI-1) were measured as markers of coagulation and fibrinolysis, respectively, at baseline, immediately after a treadmill exercise test and 30 min later. In UH, TAT and PAI-1 levels were significantly increased immediately after peak exercise and decreased 30 min later, as compared with baseline levels. At all time points, UH exhibited significantly higher TAT and PAI-1 levels compared with NT. No significant changes of TAT and PAI-1 levels were observed in NT and in patients post treatment. Acute high-intensity exercise results in impaired thrombotic and fibrinolytic response in untreated patients with EH. Angiotensin II receptor blockade with adequate blood pressure control greatly improves exercise-induced changes in coagulation and fibrinolysis in EH.

Hyperhomocysteinemia in patients with pulmonary embolism is associated with impaired plasma fibrinolytic capacity

Hyperhomocysteinemia (HHcy) affects haemostasis and shifts its balance in favour of thrombosis. In vitro and in vivo studies suggested that HHcy may impair fibrinolysis either by influencing the plasma levels of fibrinolytic factors or by altering the fibrinogen structure. We investigated the influence of mild HHcy levels on plasma fibrinolytic potential by using clot lysis time (CLT) and fibrin susceptibility to plasmin-induced lysis in 94 patients with previous pulmonary embolism and no pulmonary hypertension. CLT was measured as lysis time of tissue factor induced clots exposed to exogenous tissue plasminogen activator (t-PA). The rate of in vitro plasmin-mediated cleavage of fibrin β-chain was assessed over a 6-h period on fibrin clots, which were obtained by exposition to thrombin of purified fibrinogen. Homocysteine plasma levels were measured by Abbott Imx immunoassay and we considered as altered the values above 15 μmol/L according to the literature. In 68 patients homocysteine levels were below 15 μmol/L (NHcy) and in 26 they were above (HHcy). Significant differences were observed between the two groups regarding plasma fibrinolytic potential (p = 0.016), TAFIact (expressed as clot lysis ratio) (p = 0.02), t-PA (0.008) and PLG (0.037), but not for the other assessed components. The HHcy-patients had a threefold higher risk to have an impaired fibrinolysis. Instead, a multivariate logistic regression analysis adjusted for significances of univariate showed that HHcy (OR 5.2 95% CI 1.7-15.9; p = 0.003) and BMI (OR 5.0 95% CI 1.6-15.9; p = 0.006) resulted independently associated with impaired fibrinolytic activity. HHcy affects TAFI-mediated hypofibrinolysis but not fibrin(ogen) structure or function as documented by fibrin degradation analysis.

Plasma thrombomodulin activity, tissue factor activity and high levels of circulating procoagulant phospholipid as prognostic factors for acute myocardial infarction

Several studies have indicated an association between haemostatic markers and acute myocardial infarction, but few or no studies refer to their activity. We studied plasma levels of 10 coagulation factors (fibrinogen, protein C, protein S, von Willebrand factor, D-dimers, factor VIIa, free tissue factor pathway inhibitor, tissue-type plasminogen activator, plasminogen activator inhibitor-1, thrombomodulin) and using new specific assays analysed the activity of plasma tissue factor (TFa), thrombomodulin (TMa), and procoagulant phospholipid in 46 consecutive patients with acute myocardial infarction at the time of hospital admission, and compared them with 34 healthy normal volunteers. Plasma levels of TFa, TMa, and procoagulant phospholipid were significantly higher in cases than in control patients (P < 0.001). In addition the ratio of TFa/free tissue factor pathway inhibitor was higher in patients than in controls, whereas the tissue-type plasminogen activator (t-PA)/plasminogen activator inhibitor-1 ratio was lower in patients. Interestingly, patients with an unfavourable outcome during a 2-month follow-up had higher levels of TFa, TMa, procoagulant phospholipid, a higher ratio of TFa/free tissue factor pathway inhibitor and a lower ratio of t-PA/plasminogen activator inhibitor-1 than patients who recovered. The combination of these different parameters reveals an increase in procoagulant activity as well as impaired fibrinolytic activity during the acute phase of an acute myocardial infarction. The association of the level of the activity of these three factors may provide a new tool to assess the prognosis of acute myocardial infarction. Further studies are needed to support our findings and to elucidate the clinical interest of measuring these factors.

Is topical tissue plasminogen activator application effective on prevention of post-laminectomy epidural fibrosis? An experimental study

Objective: Impaired fibrinolytic activity has been shown to be associated with poor outcome after lumbar disc surgery. The purpose of this study was to determine the efficacy of topical tissue plasminogen activator (t-PA) in preventing epidural fibrosis in rats.Methods: L4–L5 laminectomy was performed under surgical microscope in 40 rats. Animals received either normal saline (control; n=20) or 0.5 mg/kg t-PA (n=20), topically to the operative sites. All animals were killed 1, 2, 4 and 6 weeks after surgery. Fibrosis, inflammation, necrosis and abscess formation were evaluated histopathologically.Results: The results showed that 6 weeks after surgery, inhibition in formation of epidural fibrosis was noted in both control and treatment animals. We found no significant differences in inflammation, tissue necrosis and abscess formation between groups.Conclusion: A meticulous microsurgical technique with careful hemostasis seems to be an effective and adequate method for prevention of epidural fibrosis.

Role of fibrinolysis in obesity and thrombosis

Obesity is a common disorder and a known risk factor for thrombotic complications. Development of obesity is associated with extensive modifications in adipose tissue involving adipogenesis, angiogenesis and extracellular matrix proteolysis. The fibrinolytic (plasminogen/plasmin) system plays an important role in these processes. Studies using a nutritionally induced obesity model in transgenic mice support a role of the fibrinolytic system in adipogenesis and obesity. Studies using venous or arterial thrombosis models in obese mice, with impaired fibrinolytic activity, confirm a prothrombotic risk associated with obesity.

Microthrombosis after Aneurysmal Subarachnoid Hemorrhage: An Additional Explanation for Delayed Cerebral Ischemia

Patients with aneurysmal subarachnoid hemorrhage (SAH) who experience delayed cerebral ischemia (DCI) have an increased risk of poor outcome. Delayed cerebral ischemia is considered to be caused by vasospasm. However, not all patients with DCI have vasospasm. Inversely, not all patients with vasospasm develop clinical symptoms and signs of DCI. In the past, treatments aiming at vasospasm were not successful in preventing ischemia. The purpose of this review is to give an overview of clinical data showing that DCI cannot always be attributed to vasospasm, and to present an in-depth analysis of clinical and autopsy studies on the role of microthrombosis in the pathogenesis of DCI. Clinical studies show that DCI is associated with an activation of the coagulation cascade within a few days after SAH, preceding the time window during which vasospasm occurs. Furthermore, impaired fibrinolytic activity, and inflammatory and endothelium-related processes, lead to the formation of microthrombi, which ultimately result in DCI. The presence of microthrombi is confirmed by autopsy studies. Insight in the pathophysiology of DCI is crucial for the development of effective therapies against this complication. Because multiple pathways are involved, future research should focus on drugs with pleiotropic effects.

Tissue-Type Plasminogen Activator Release in Healthy Subjects and Hypertensive Patients

The relationship between adrenergic stimuli and NO in modulating tissue-type plasminogen activator (t-PA) release from endothelial cells was investigated in normotensive subjects and essential hypertensive patients. Sympathetic activation, a well-known stimulus for endogenous fibrinolysis, is also involved in the determination of cardiovascular risk in essential hypertension. However, the existence of cross-talk between adrenergic stimuli and NO availability in modulating t-PA release is not well established yet. We assessed the release of t-PA in the forearm microcirculation of 58 normotensive subjects (mean age: 47+/-9 years) and 44 essential hypertensive patients (mean age: 48+/-11 years) under specific intra-arterial adrenergic stimuli. Intrabrachial infusion of epinephrine (0.1 to 0.3 microg/100 mL per minute) induced greater t-PA release in normotensive subjects as compared with essential hypertensive patients (P<0.05). However, inhibition of NO synthase with N(G)-monomethyl-L-arginine (100 microg/100 mL per minute) infusion blunted epinephrine-induced t-PA release in normotensive subjects (P<0.05) but not in essential hypertensive patients. In normotensive subjects, t-PA release by epinephrine was not affected by phentolamine (8 microg/100 mL per minute) coinfusion and was abolished in the presence of propanolol (10 microg/100 mL per minute). Intrabrachial isoproterenol (0.03 microg/100 mL per minute) induced a significant increase in t-PA release (P<0.01), an effect blunted by N(G)-monomethyl-L-arginine (P<0.05). In essential hypertensive patients, the response to isoproterenol was impaired as compared with normotensive subjects and was unaffected by N(G)-monomethyl-L-arginine coinfusion. In conclusion, the results of the present study demonstrate that adrenergic-induced t-PA release is mediated by beta-adrenoreceptors via a mechanism involving the NO pathway. Our results show an impaired adrenergic-stimulated t-PA release among essential hypertensive patients, probably mediated via a reduced NO availability. This impaired fibrinolytic activity might contribute to the increased cardiovascular risk associated with hypertension.

D-dimer testing: advantages and limitations in emergency medicine for managing acute venous thromboembolism

Patients with suspected deep vein thrombosis (DVT) or pulmonary embolism (PE) are frequently admitted to an Emergency Department (ED) for initial evaluation. However, management of patients with suspicion of acute venous thromboembolism (VTE) in this clinical setting can be difficult; in fact symptoms and signs of DVT are non-specific and can be found in a broad spectrum of non-thrombotic disorders. An accurate and timely objective diagnosis is necessary for immediate and correct identification of patients with acute VTE, while avoiding the bleeding risk associated with unnecessary anticoagulant therapy in patients where DVT or PE have been ruled out. The diagnostic approach to patients with suspected VTE includes clinical evaluation, diagnostic imaging and D-dimer testing [1, 2]. In a recent issue of Internal and Emergency Medicine, Siragusa [3] exhaustively discussed the currently used assays, clinical indications and limitations of D-dimer testing for managing acute VTE in emergency medicine. Measurement of D-dimer values, a degradation product of cross-linked fibrin, is a simple laboratory test, and has been extensively studied in numerous prospective cohort studies in cases of suspected DVT or PE, showing a high negative predictive value. The author [3] shows that D-dimer testing has sufficient diagnostic accuracy for ruling out acute VTE if used in combination with standardised clinical judgement. The review is important for at least three reasons. First, many physiological and pathological conditions can increase plasma D-dimer levels (pregnancy, age, trauma, cancer, inflammation and several other clinical conditions); on the other hand D-dimer levels may fail to increase in patients with acute VTE for multiple reasons (impaired fibrinolytic activity, use of heparin or oral anticoagulants, onset of symptoms more than two weeks before blood sampling). For these reasons, D-dimer testing has a high sensitivity but a low specificity in the diagnosis of acute VTE; in clinical practice it may be associated with frequent “false positive” results, but also more rarely with “false negative” findings. However, its use should always be associated with a careful clinical assessment to rule out the presence of acute VTE only in symptomatic patients. Overuse or misuse of the D-dimer screen for VTE may have negative consequences, in terms of a burden both for patients and for healthcare costs; in fact, despite clinical guidelines, inappropriate and unnecessary measurement of D-dimer is a significant clinical problem [4]. Second, commercially available assays are very differ