The substitution of lanthanide ions for Ca(II) in the Ca(II)-binding sites of <em>prothrombin</em> and the derivatives of <em>prothrombin</em> activation and in the metal-dependent conversion of <em>prothrombin</em> or prethrombin <em>1</em> to thrombin was studied at pH 6.8. Gd(III), Tb(III), La(III), Dy(III), Pr(III), Sm(III), and Ce(III) may be substituted for Ca(II) in the generation of thrombin from <em>prothrombin</em> or prethrombin <em>1</em> by activated factor X. The rates of thrombin generation in the presence of optimal concentrations of Gd(III) were about <em>2</em>5% for <em>prothrombin</em> and prethrombin <em>1</em> compared to the rate of thrombin generation with optimal concentrations of Ca(II). Maximal rates of thrombin generation were observed at <em>2</em>0 muM Gd(III) using <em>prothrombin</em> as substrate, compared to <em>1</em>0 muM Gd(III) when prethrombin <em>1</em> was employed. Using the steady state rate-dialysis method, the high affinity metal-binding sites of <em>prothrombin</em> and the products formed during <em>prothrombin</em> activation were characterized using <em>1</em>53Gd(III). <em>Prothrombin</em> has two high affinity binding sites for Gd(III) (Kd = 0.75 muM). Prethrombin <em>1</em> and prethrombin <em>2</em> each bind one Gd(III) tightly (Kd = <em>1</em>.<em>1</em>0 muM and 0.8<em>1</em> muM, respectively). <em>Fragment</em> <em>1</em>, the phospholipid-binding portion of <em>prothrombin</em>, has two sites which bind Gd(III) tightly (Kd 0.<em>1</em>6 muM). <em>Fragment</em> <em>2</em> has no high affinity metal-binding sites, but has intermediate affinity metal-binding sites (Kd greater than <em>1</em>.6 muM). Thrombin has numerous high affinity binding sites (Kd less than 0.<em>1</em> muM), suggesting that the conversion of prethrombin <em>2</em> to thrombin is associated with a significant change in tertiary structure. These results indicate that Gd(III) binds tightly to the metal-binding sites of these proteins and can substitute for Ca(II) in metal-dependent <em>prothrombin</em> activation. In the activation of <em>prothrombin</em> by activated factor X, these data suggest that Ca(II) is required for metal-dependent factor V and phospholipid binding and not as a cofactor in enzyme catalysis.

Hormonal emergency contraception (EC) is a well established contraceptive method, recommended to all women, although the effects on haemostais are not fully evaluated. The aim of this study was to evaluate whether exposure to EC has effects on well established cardiovascular risk factors, and also to examine whether differences exist between two EC treatments. In a prospective randomized cross over design <em>1</em><em>1</em> women used two different EC methods, one with estrogen and levonorgestrel (EE-EC) and one with levonorgestrel only (LNG-EC). Plasma concentrations of haemostatic factors (APC resistance, antithrombin, fibrinogen, <em>prothrombin</em> <em>fragment</em> <em>1</em> + <em>2</em>, free protein S, factorVII and PAI-<em>1</em>), sex-hormone-binding globulin (SHBG), the apolipoprotein (apo)B/apoA<em>1</em> ratio and C-reactive protein (CRP) were followed frequently during the following 48 hours. A rapid haemostatic activation was induced with both treatments, although more pronounced with EE-EC. Already two hours after EC, the plasma concentrations of haemostatic parameters and SHBG were significantly different from baseline concentrations. An ETP-based APC-resistance method showed increased APC resistance with EE-EC and decreased APC resistance with LNG-EC. The ApoB/ApoA<em>1</em> ratio was affected in a favourable direction with EE-EC.CRP increased slightly regardless of treatment. Even a very short exposure to exogenous sex hormones causes prompt effects on hepatic protein synthesis and the coagulation system. This must be taken into consideration whenever exogenous steroid hormones are administered, especially to individuals with a genetic predisposition to thrombosis or transiently disturbed haemostasis.

<em>Prothrombin</em> <em>fragment</em> <em>1</em> + <em>2</em> (F<em>1</em> + <em>2</em>) is considered to be useful for diagnosis of thrombosis. However, the evidence for a diagnosis of thrombosis by F<em>1</em> + <em>2</em> is still not well established. The plasma concentrations of F<em>1</em> + <em>2</em>, soluble fibrin, D-dimer, and thrombin-antithrombin complex were measured in 694 patients suspected of having thrombosis and then were correlated with thrombosis. Plasma concentrations of F<em>1</em> + <em>2</em>, soluble fibrin, D-dimer, and thrombin-antithrombin complex were significantly higher in patients with thrombosis, compared with patients without thrombosis. When cutoff values of more than 300 pmol/L for F<em>1</em> + <em>2</em> were used for the diagnosis, more than 50% of the patients were thus found to have thrombosis. The findings showed that F<em>1</em> + <em>2</em>, soluble fibrin, D-dimer, and thrombin-antithrombin complex have similar diagnostic ability. The plasma concentration of F<em>1</em> + <em>2</em> closely was well correlated with thrombin-antithrombin complex, soluble fibrin, and D-dimer. Finally, F<em>1</em> + <em>2</em> is one of the most useful parameters for the diagnosis of thrombosis.

Many reports indicate a hypercoagulative state in diabetes mellitus as result of endothelial damage. Experimental evidence suggests that a metabolic derangement triggers a cascade of biochemical events that lead to vascular dysfunction. The net effect is to convert the endothelium from thromboresistant to thrombogenic surface. In literature, a strong association between type <em>1</em> diabetes mellitus (DM<em>1</em>) and celiac disease (CD) has been reported. We do not have information about the hemostatic system in these associated conditions. Our study aims at evaluating whether the presence of CD in a group of DM<em>1</em> patients is associated with a different expression of some hemostatic factors and with a different manifestation and/or progression of microvascular complications of DM<em>1</em> in comparison with patients with only diabetes. Ninety-four adult DM<em>1</em> patients were enrolled in the study and subsequently screened for CD. Anti-endomysial antibodies (EMA) were positive in <em>1</em>3 of 94 DM<em>1</em> patients (<em>1</em>3.8%). CD diagnosis was confirmed by histology and organ culture. The mean age and duration of DM<em>1</em> of patients also affected by CD were similar to those of only diabetic patients, but the metabolic control and the hemocoagulative parameters were significantly different between the two groups: DM<em>1</em> patients also affected by CD presented significantly lower concentrations of glycosylated hemoglobin (HbA<em>1</em>c) (P < 0.05), cholesterol (P < 0.00<em>1</em>), triglycerides (P < 0.00<em>1</em>), factor VII antigen (FVII:ag) (P < 0.005), factor VII coagulant activity (FVII:c) (P < 0.05), and <em>prothrombin</em> degradation <em>fragments</em> (F<em>1</em>+<em>2</em>) (P < 0.00<em>1</em>), as well as higher values of activated C protein (APC) (<0.00<em>1</em>). No retinal abnormalities and no signs of renal damage were observed in DM<em>1</em> patients also affected by CD. Our results suggest a potential protective role of CD in the prothrombotic state of DM<em>1</em>.

The contribution of obesity to the occurrence of cardiovascular events may not be wholly related to its influence on traditional risk factors. Coagulation and fibrinolysis may also influence cardiovascular risk, but the relationship of adiposity with these processes is unclear. The aim of the present study was to investigate the relationships of BMI (body mass index), waist circumference, hip circumference and WHR (waist-to-hip ratio) with VIIc (factor VII activity), plasma markers of thrombin generation [F<em>1</em>+<em>2</em> (<em>prothrombin</em> <em>fragment</em> <em>1</em>+<em>2</em>)], fibrin formation [SF (soluble fibrin)] and fibrin turnover (D-dimer), and PAI-<em>1</em> (plasminogen activator inhibitor-<em>1</em>; a marker of fibrinolytic inhibitory capacity). The study cohort was 80 healthy postmenopausal women who were not diabetic, current smokers or taking hormone therapy and who had a fasting sample of blood collected. VIIc, F<em>1</em>+<em>2</em>, SF and PAI-<em>1</em> were all positively correlated with BMI, waist circumference and WHR, whereas D-dimer was positively correlated with waist circumference and WHR, but not BMI. WHR was the strongest correlate of all the markers except for PAI-<em>1</em>, which was most closely related to BMI. Hip circumference became a negative correlate of F<em>1</em>+<em>2</em> and D-dimer after adjusting for waist circumference. The relationships of WHR with F<em>1</em>+<em>2</em> and SF, but not with VIIc and D-dimer, were independent of traditional risk factors. The positive association between waist circumference and markers of thrombin generation, fibrin production and fibrin turnover suggests that abdominal adiposity may contribute to atherothrombosis by activating intravascular coagulation. In contrast, a larger hip circumference appears to have a protective affect against coagulation activation.

Recently it has been shown that tissue factor (TF), an important trigger for initiating blood coagulation, is present in the circulating plasma. In order to assess the clinical implications of TF in plasma, plasma concentration of TF was quantitated in 65 patients with disseminated intravascular coagulation (DIC). The mean concentration of plasma TF was elevated in patients with DIC at presentation as compared with healthy subjects (446 +/- SD 536 pg/ml vs. <em>1</em>38 +/- 5<em>1</em> pg/ml, P < 0.00<em>1</em>). Abnormally high levels were found only in 46.<em>2</em>% of the patients, predominantly in patients with non-hematological solid tumors and acute leukemia. Plasma TF did not correlate with hemostatic markers of DIC such as thrombin-antithrombin III complex, <em>prothrombin</em> <em>fragment</em> <em>1</em> + <em>2</em>, plasma-alpha <em>2</em>-plasmin inhibitor complex, FDP, D-dimer, or fibrinogen. Serial determinations of plasma TF demonstrated that plasma TF changes roughly in parallel with the course of DIC in most patients with elevated TF at presentation of DIC. These findings suggest that plasma TF is potentially valuable for monitoring the progress of DIC in a limited population of patients.

BACKGROUND

Activation of coagulation and fibrinolysis occurs in patients with inflammatory bowel disease. Our aim was to study the course of a marker for activation of the coagulation cascade, <em>prothrombin</em> <em>fragment</em> <em>1</em> + <em>2</em> (F<em>1</em>+<em>2</em>), and fibrinolysis, fibrin degradation products (FbDP), in patients with ulcerative colitis and Crohn's disease before and during therapy with glucocorticoids.

METHODS

Twenty-seven patients with active ulcerative colitis and 4<em>2</em> with active Crohn's disease treated with glucocorticoids were studied. Plasma samples were drawn before, during, and at end of therapy or at time of treatment failure. F<em>1</em>+<em>2</em> and FbDP were measured with commercially available enzyme immunoassays.

RESULTS

Mean base-line concentrations of F<em>1</em>+<em>2</em> were significantly increased in patients with ulcerative colitis (4.77 +/- 0.50 nmol/l; P < 0.000<em>1</em>) and in Crohn's disease (4.66 +/- 0.59 nmol/l; P < 0.000<em>1</em>) compared with healthy controls (<em>1</em>.57 +/- 0.09 nmol/l). Mean base-line concentrations of FbDP were significantly increased in patients with ulcerative colitis (<em>1</em><em>2</em>64 +/- <em>1</em>6<em>1</em> microg FE/l; P < 0.000<em>1</em>) and in Crohn's disease (49<em>1</em> +/- 5<em>1</em> microg FE/l; P < 0.000<em>1</em>) compared with healthy controls (<em>1</em>94 +/- <em>2</em><em>1</em> microg FE/l). During treatment with glucocorticoids the plasma concentrations of FbDP decreased in patients with Crohn's disease achieving remission and in patients with ulcerative colitis avoiding surgery but remained unchanged in patients not responding to therapy. In contrast, F<em>1</em>+<em>2</em> remained increased in patients with Crohn's disease and ulcerative colitis irrespective of outcome.

CONCLUSIONS

The present data support the concept that coagulation cascade and fibrinolysis is activated in patients with active inflammatory bowel disease. F<em>1</em>+<em>2</em> and FbDP correlate poorly with the clinical disease activity and acute-phase reactants. The clinical response to treatment with glucocorticoids is accompanied by a decrease in plasma concentrations of FbDP but not in F<em>1</em>+<em>2</em>. FbDP may emerge as a new marker in the assessment of disease activity in patients with inflammatory bowel disease.

BACKGROUND

The mechanism of coagulation activation during continuous venovenous hemofiltration (CVVH) has not yet been elucidated. Insight into the mechanism(s) of hemostatic activation within the extracorporeal circuit could result in a more rational approach to anticoagulation. The aim of the present study was to investigate whether CVVH using cellulose triacetate filters causes activation of the contact factor pathway or of the tissue factor pathway of coagulation. In contrast to previous studies, CVVH was performed without anticoagulation.

METHODS

Ten critically ill patients were studied prior to the start of CVVH and at 5, <em>1</em>5 and 30 minutes and <em>1</em>, <em>2</em>, 3 and 6 hours thereafter, for measurement of <em>prothrombin</em> <em>fragment</em> F<em>1</em>+<em>2</em>, soluble tissue factor, activated factor VII, tissue factor pathway inhibitor, kallikrein-C<em>1</em>-inhibitor and activated factor XII-C<em>1</em>-inhibitor complexes, tissue-type plasminogen activator, plasminogen activator inhibitor type I, plasmin-antiplasmin complexes, protein C and antithrombin.

RESULTS

During the study period the <em>prothrombin</em> <em>fragment</em> F<em>1</em>+<em>2</em> levels increased significantly in four patients (defined as group A) and did not change in six patients (defined as group B). Group A also showed a rapid increase in transmembrane pressure, indicating clotting within the filter. At baseline, the activated partial thromboplastin time, the <em>prothrombin</em> time and the kallikrein-C<em>1</em>-inhibitor complex and activated factor XII-C<em>1</em>-inhibitor complex levels were significantly higher in group B, whereas the platelet count was significantly lower in group B. For the other studied markers the differences between group A and group B at baseline were not statistically significant. During CVVH the difference in the time course between group A and group B was not statistically significant for the markers of the tissue factor system (soluble tissue factor, activated factor VII and tissue factor pathway inhibitor), for the markers of the contact system (kallikrein-C<em>1</em>-inhibitor and activated factor XII-C<em>1</em>-inhibitor complexes) and for the markers of the fibrinolytic system (plasmin-antiplasmin complexes, tissue-type plasminogen activator and plasminogen activator inhibitor type I).

CONCLUSIONS

Early thrombin generation was detected in a minority of intensive care patients receiving CVVH without anticoagulation. Systemic concentrations of markers of the tissue factor system and of the contact system did not change during CVVH. To elucidate the mechanism of clot formation during CVVH we suggest that future studies are needed that investigate the activation of coagulation directly at the site of the filter. Early coagulation during CVVH may be related to lower baseline levels of markers of contact activation.

The relationship between extrinsic coagulation factors, tissue factor pathway inhibitor (TFPI) and activated factor XII (FXIIa) was examined in 7<em>1</em> patients with end-stage chronic renal failure. They had chronic stable uremia due to regular hemodialysis. The patients were divided into two age- and sex-matched groups with and without diabetes mellitus. As extrinsic coagulation parameters, FVIIa and FVII antigen (FVIIag), tissue factor antigen and TFPI (the activity and antigen) were measured. FXIIa was measured as a marker of contact activation, and thrombin generation was evaluated using the two markers thrombin-antithrombin III complex and <em>prothrombin</em> <em>fragment</em> <em>1</em> + <em>2</em>. In both hemodialysis groups with and without diabetes, significant elevations of FXIIa, FVIIa and tissue factor, with high levels of TFPI, were found. Thus, hyperactivation of the coagulation system was in part compensated by TFPI, and a significant increase in FXIIa could not directly affect FVIIa hyperactivation. No differences of these parameters, except for FVIIag and <em>fragment</em> <em>1</em> + <em>2</em>, were found between the groups with and without diabetes. It is suggested that the long-term hemodialysis might have masked any differences due to the underlying disease in these two subgroups.

BACKGROUND The pathophysiological mechanism associated with the higher prothrombotic tendency in atrial fibrillation (AF) is complex and multifactorial. However, the role of prothrombotic markers in AF remains inconclusive. MATERIAL AND METHODS We conducted a meta-analysis of observational studies evaluating the association of coagulation activation, fibrinolytic, and endothelial function with occurrence of AF and clinical adverse events. A comprehensive subgroup analysis and meta-regression was performed to explore potential sources of heterogeneity. RESULTS A literature search of major databases retrieved <em>1</em>703 studies. After screening, a total of 7<em>1</em> studies were identified. Pooled analysis showed the association of coagulation markers (D-dimer (weighted mean difference (WMD) =<em>1</em>97.67 and p<0.00<em>1</em>), fibrinogen (WMD=0.43 and p<0.00<em>1</em>), <em>prothrombin</em> <em>fragment</em> <em>1</em>-<em>2</em> (WMD=0.53 and p<0.00<em>1</em>), antithrombin III (WMD=<em>2</em>3.90 and p=0.004), thrombin-antithrombin (WMD=5.47 and p=0.004)); fibrinolytic markers (tissue-type plasminogen activator (t-PA) (WMD=<em>2</em>.<em>1</em>3 and p<0.00<em>1</em>), plasminogen activator inhibitor (WMD=<em>1</em><em>1</em>.44 and p<0.00<em>1</em>), fibrinopeptide-A (WMD=4.<em>1</em>3 and p=0.0<em>1</em>)); and endothelial markers (von Willebrand factor (WMD=<em>2</em>7.0<em>1</em> and p<0.00<em>1</em>) and soluble thrombomodulin (WMD=3.9<em>2</em> and p<0.00<em>1</em>)) with AF. CONCLUSIONS The levels of coagulation, fibrinolytic, and endothelial markers have been reported to be significantly higher in AF patients than in SR patients.

OBJECTIVE

To determine the homeostatic balance of patients with ventilator-associated pneumonia (VAP) with respect to the adequacy of antimicrobial therapy.

METHODS

Descriptive observational study in a <em>1</em><em>2</em>-bed medical intensive care unit in a university-affiliated hospital.

METHODS

Twenty-nine patients with VAP documented by quantitative culture of bronchoalveolar secretions and a control group of eight mechanically ventilated patients.

METHODS

Serial bronchoalveolar lavage fluid (BALF) samples were assayed for <em>prothrombin</em> activation <em>fragment</em> (F<em>1</em>+<em>2</em>), thrombin-antithrombin (TAT) complex, fibrinolytic activity, urokinase-type plasminogen activator (u-PA), and plasminogen activator inhibitor type <em>1</em> (PAI-<em>1</em>) on days <em>1</em>, 4, and 7 after VAP onset.

RESULTS

Pathogens isolated from patients with inadequate empirical antimicrobial coverage included methicillin-resistant Staphylococcus aureus (n=<em>2</em>), Pseudomonas aeruginosa (n=4), and Acinetobacter baumannii (n=<em>1</em>). Compared to those who received adequate antibiotic therapy, TAT, F<em>1</em>+<em>2</em>, and PAI-<em>1</em> levels increased while u-PA levels remained unchanged. Despite antibiotic adjustment on day 4, TAT levels remained elevated in those who lacked adequate antimicrobial coverage and were significantly correlated with PaO(<em>2</em>)/FIO(<em>2</em>). The procoagulant activity was accompanied by a local depression of fibrinolytic capacity that was attributed mainly to increased BALF PAI-<em>1</em> levels. Nonsurvivors showed significantly higher levels of TAT and PAI-<em>1</em> than survivors. No significant correlation between the bacterial burden and the homeostatic derangements was documented.

CONCLUSIONS

The lung inflammatory response seems to promulgate a local procoagulant activity associated with hypoxemia in those with inadequate antibiotic therapy. The homeostatic derangement seems to be independent of the lung bacterial burden.

BACKGROUND

To date, no study has tested the effect of different heparin dosages on the hemostatic changes during off-pump coronary artery bypass graft (OPCABG) surgery, and a wide variety of empirical anticoagulation protocols are being applied. We tested the effect of two different heparin dosages on the activation of the hemostatic system in patients undergoing OPCABG procedures.

METHODS

Forty-two patients eligible for OPCABG procedures were assigned in a randomized fashion to low-dose heparin (<em>1</em>50 IU/kg) or high-dose heparin (300 IU/kg). <em>Prothrombin</em> <em>fragment</em> <em>1</em>+<em>2</em>, plasmin/alpha(<em>2</em>)-plasmin inhibitor complex, D-dimer, soluble tissue factor, tissue factor pathway inhibitor, total thrombin activatable fibrinolysis inhibitor (TAFI), and activated TAFIa were assayed by specific enzyme-linked immunosorbent assays at six different timepoints, before, during, and after surgery. Platelet function was evaluated by means of an in vitro bleeding time test, platelet function analyzer-<em>1</em>00.

RESULTS

The OPCABG surgery was accompanied by significant changes of all plasma biomarkers, indicative of systemic activation of coagulation and fibrinolysis. A significant increase in circulating TAFIa was detected perioperatively and postoperatively, and multiple regression analysis indicated that prothrombin F<em>1</em>+<em>2</em> but not plasmin/alpha(<em>2</em>)-antiplasmin complex was independently associated with TAFIa level. Platelet function analyzer-<em>1</em>00 values did not change significantly after OPCABG. All hemostatic changes were similar in the two heparin groups, even perioperatively, when the difference in anticoagulation was maximal.

CONCLUSIONS

Both early and late hemostatic changes, including TAFI activation, are similarly affected in the low-dose and high-dose heparin groups, suggesting that the increase in heparin dosage is not accompanied by a better control of clotting activation during OPCABG surgery.

BACKGROUND

OSA is a risk factor for a first episode of pulmonary embolism (PE), although its impact on the risk of thromboembolism recurring is uncertain. Our objective was to explore the prognostic value of OSA after the discontinuation of oral anticoagulation (OAC) in patients with a first episode of PE.

METHODS

In <em>1</em><em>2</em>0 consecutive patients who had stopped OAC for a first episode of PE, we performed home respiratory polygraphy and recorded sleep characteristics, classic risk factors for PE, blood pressure measurements, spirometric parameters, physical activity, and levels of D-dimer and <em>prothrombin</em> <em>fragment</em> <em>1</em>+<em>2</em> (F<em>1</em>+<em>2</em>). Patients were followed for 5 to 8 years, and the main end point was PE recurrence. Restarting OAC for any thromboembolic event was evaluated as a secondary end point.

RESULTS

During the follow-up period, <em>1</em>9 patients had a PE recurrence, and <em>1</em>6 of them had an apnea-hypopnea index (AHI) ≥ <em>1</em>0 h-<em>1</em>. In a multivariate Cox regression model, an AHI ≥ <em>1</em>0 h-<em>1</em> (hazard ratio [HR], <em>2</em>0.73; 95% CI, <em>1</em>.7<em>1</em>-<em>2</em>5<em>1</em>.<em>2</em>8), mean nocturnal oxygen saturation (nSao<em>2</em>) (HR, 0.39; 95% CI, 0.<em>2</em>0-0.78), time with Sao<em>2</em> < 90% (CT90%) (HR, 0.90; 95% CI, 0.8<em>2</em>-0.98), and D-dimer level (HR, <em>1</em>.00<em>1</em>; 95% CI, <em>1</em>.00-<em>1</em>.00<em>2</em>) were identified as independent risk factors for recurrent PE. Twenty-four patients resumed OAC, and AHI ≥ <em>1</em>0 h-<em>1</em> (HR, <em>2</em>0.66; 95% CI, <em>2</em>.<em>2</em>7-<em>1</em>88.35), mean nSao<em>2</em> (HR, 0.54; 95% CI, 0.3<em>2</em>-0.94), and Epworth Sleepiness Scale (ESS) (HR, 0.73; 95% CI, 0.56-0.97) were retained as independent risk factors for the resumption of OAC.

CONCLUSIONS

After a first episode of PE, OSA is an independent risk factor for PE recurrence or restarting OAC for a new thromboembolic event.

OBJECTIVE

We evaluated the effects of soy isoflavone supplementation on hemostasis in healthy postmenopausal women.

METHODS

In this double-blinded, placebo-controlled study, 47 postmenopausal women 47-66 y of age received 40 mg of soy isoflavone (n = <em>2</em>5) or 40 mg of casein placebo (n = <em>2</em><em>2</em>) once a day for 6 mo. Levels of factors VII and X, fibrinogen, thrombin-antithrombin complex, <em>prothrombin</em> <em>fragments</em> <em>1</em> plus <em>2</em>, antithrombin, protein C, total and free protein S, plasminogen, plasminogen activator inhibitor-<em>1</em>, and D-dimers were measured at baseline and 6 mo. Urinary isoflavone concentrations (genistein and daidzein) were measured as a marker of compliance and absorption using high-performance liquid chromatography. Baseline characteristics were compared by unpaired Student's t test. Within-group changes and comparison between the isoflavone and casein placebo groups were determined by a mixed effects model.

RESULTS

The levels of hemostatic variables did not change significantly throughout the study in the isoflavone group; however, the isoflavone group showed a statistically significant reduction in plasma concentration of <em>prothrombin</em> <em>fragments</em> <em>1</em> plus <em>2</em>; both groups showed a statistically significant reduction in antithrombin, protein C, and free protein S levels. A significant increase in D-dimers was observed only in the isoflavone group. Plasminogen activator inhibitor-<em>1</em> levels increased significantly in the placebo group. However, these changes were not statistically different between groups.

CONCLUSIONS

The results of the present study do not support a biologically significant estrogenic effect of soy isoflavone on coagulation and fibrinolysis in postmenopausal women. However, further research will be necessary to definitively assess the safety and efficacy of isoflavone.

BACKGROUND

Chronic anticoagulation is a standard of care in idiopathic pulmonary arterial hypertension (IPAH). However, hemostatic abnormalities in this disease remain poorly understood. Therefore, we aimed to study markers of thrombogenesis and fibrinolysis in patients with IPAH.

METHODS

We studied <em>2</em>7 consecutive patients (67% female) with IPAH aged 50.0 years (IQR: 4<em>1</em>.0-65.0) and <em>1</em>6 controls without pulmonary hypertension. <em>Prothrombin</em> <em>fragment</em> <em>1</em>+<em>2</em> (F<em>1</em>+<em>2</em>) and thrombin-antithrombin (TAT) complexes were measured to assess thrombogenesis; tissue-type plasminogen activator (tPA) antigen and plasmin-anti-plasmin complex to characterize activation of fibrinolysis; plasminogen activator inhibitor <em>1</em> (PAI-<em>1</em>) to measure inhibition of fibrinolysis; and endothelin-<em>1</em> (ET-<em>1</em>) and interleukin-6 (IL-6) to assess endothelial activation and systemic inflammation, respectively. In addition, in treatment-naive IPAH patients these markers were assessed after 3 months of PAH-specific therapies.

RESULTS

TPA (<em>1</em>0.<em>1</em>[6.8-<em>1</em>5.8] vs 5.<em>2</em>[3.3-7.3] ng/ml, p<0.00<em>1</em>), plasmin-anti-plasmin (9<em>1</em>.5[60.3-94.<em>2</em>] vs 55.8[5<em>1</em>.<em>1</em>-64.9] ng/ml, p<0.00<em>1</em>), IL-6 (4.9[<em>2</em>.5-7.9] vs <em>2</em>.<em>1</em>[<em>1</em>.3-3.8] pg/ml, p=0.00<em>1</em>) and ET-<em>1</em> (3.7 [3.3-4.5] vs 3.4[3.<em>1</em>-3.5], p= 0.03) were higher in patients with IPAH than in controls. In IPAH patients plasmin-anti-plasmin and tPA correlated positively with IL-6 (r=0.39, p=0.04 and r=0.63, p<0.00<em>1</em>, respectively) and ET-<em>1</em> (r=0.55, p=0.003 and r=0.59, p=0.00<em>1</em>, respectively). No correlation was found between tPA or plasmin-anti-plasmin and markers of thrombogenesis. Plasmin-anti-plasmin decreased after 3 months of PAH specific therapy while the other markers remained unchanged.

CONCLUSIONS

In the present study we showed that markers of fibrynolysis were elevated in patients with IPAH however we did not find a clear evidence for increased thrombogenesis in this group of patients. Fibrinolysis, inflammation, and endothelial activation were closely interrelated in IPAH.

A model of thrombin interaction with distinct substrates or ligands has been derived from the crystallographic studies of thrombin-inhibitors complexes, and buttressed by functional studies with mutant thrombins, thrombin proteolytic derivatives or antibodies against thrombin. The unique specificity of thrombin for its substrates and ligands may be ascribed to multiple interactions with both the active site cleft and exosite(s) distinct from the active site. Two prominent insertion loops around Trp 50 and Trp <em>1</em>48 project over the active site cleft and play an important role in the substrates selection. Several substrates (fibrinogen, thrombin receptor, heparin cofactor II) or ligands (thrombomodulin, glycoprotein Ib) interact with a large exosite located on the surface of the loop segment 65-76, mainly constituted of basic amino acids, designated anion binding exosite <em>1</em>. Interaction with these various macromolecules appears to involve a limited number of residues within the large exosite <em>1</em>. It is conceivable that exosite <em>1</em> contains distinct subsites, although most of them may overlap. A second basic exosite (anion binding exosite <em>2</em>) is located close to the carboxy-terminal B chain helix. Exosite <em>2</em> interacts with heparin, the chondroitin sulfate moiety of thrombomodulin and <em>prothrombin</em> activation <em>fragment</em> <em>2</em>. Interaction of ligands with either exosite <em>1</em> or exosite <em>2</em> leads to conformational changes of the thrombin molecule, that may be important determinants of thrombin specificity. Whether exosite <em>2</em> cooperates with exosite <em>1</em> for thrombin interaction with fibrin(ogen) or the thrombin receptor remains to be determined.

OBJECTIVE

Renal function affects the thyroid gland in many ways. Disturbances in hemostasis and inflammation are common complications of kidney diseases. Endothelial dysfunction may link these two processes.

METHODS

A cross-sectional study on thyroid hormones in relation to markers of endothelial damage and inflammation in 96 hemodialyzed (HD) patients and 39 healthy volunteers was performed.

METHODS

The study took place in the dialysis unit at a university hospital.

METHODS

Thyroid hormones, markers of endothelial damage (von Willebrand factor, thrombomodulin, intracellular adhesion molecule, and CD<em>1</em>46), markers of inflammation (high-sensitivity C-reactive protein, tumor necrosis factor alpha), other hemostatic parameters (thrombin-antithrombin complexes, <em>prothrombin</em> <em>fragments</em> <em>1</em> + <em>2</em> - F<em>1</em> + <em>2</em>, plasmin-antiplasmin complexes, tissue plasminogen activator and its inhibitor, tissue factor pathway inhibitor, and platelet glycoprotein V) were measured using commercially available kits.

RESULTS

Free T3 and total T3 were lower in HD patients compared with controls. Markers of endothelial dysfunction and inflammation were significantly elevated in HD patients compared with controls. In multiple regression analysis T3 was independently related to time on dialyses, albumin, iron, ferritin, C-reactive protein (CRP), and F<em>1</em> + <em>2</em> in HD patients. Free T3 was also independently related to total protein, total calcium, and triglycerides. In patients with CRP less than 6 mg/L in multiple regression analysis the only correlates of T3 were albumin and ferritin, whereas the only correlates of free T3 were albumin and time on dialyses. Multiple regression analysis showed that in HD patients with CRP greater than equal to 6 mg/L predictors of free T3 were CRP, F<em>1</em> + <em>2</em>, and dose of erythropoietin. In healthy volunteers T3 was related to tissue factor pathway inhibitor and platelet glycoprotein V was related to thyroid-stimulating hormone.

CONCLUSIONS

We described novel relations between thyroid hormones and markers of endothelial dysfunction and inflammation in HD patients. Thyroid dysfunction is related to time on dialyses, endothelial damage, and inflammatory state, frequently encountered in uremia. Therefore, the relations between thyroid axis and endothelium in HD subjects merit additional studies.

Thromboembolic events were described in patients with Chagas disease without cardiomyopathy. We aim to confirm if there is a hypercoagulable state in these patients and to determine if there is an early normalization of hemostasis factors after antiparasitic treatment. Ninety-nine individuals from Chagas disease-endemic areas were classified in two groups: G<em>1</em>, with T.cruzi infection (n = 56); G<em>2</em>, healthy individuals (n = 43). Twenty-four hemostasis factors were measured at baseline. G<em>1</em> patients treated with benznidazole were followed for 36 months, recording clinical parameters and performance of conventional serology, chemiluminescent enzyme-linked immunosorbent assay (trypomastigote-derived glycosylphosphatidylinositol-anchored mucins), quantitative polymerase chain reaction, and hemostasis tests every 6-month visits. <em>Prothrombin</em> <em>fragment</em> <em>1</em>+<em>2</em> (F<em>1</em>+<em>2</em>) and endogenous thrombin potential (ETP) were abnormally expressed in 77% and 50% of infected patients at baseline but returned to and remained at normal levels shortly after treatment in 76% and 96% of cases, respectively. Plasmin-antiplasmin complexes (PAP) were altered before treatment in 3<em>2</em>% of G<em>1</em> patients but normalized in 94% of cases several months after treatment. None of the patients with normal F<em>1</em>+<em>2</em> values during follow-up had a positive qRT-PCR result, but 3/<em>2</em>4 patients (<em>1</em>3%) with normal ETP values did. In a percentage of chronic T. cruzi infected patients treated with benznidazole, altered coagulation markers returned into normal levels. F<em>1</em>+<em>2</em>, ETP and PAP could be useful markers for assessing sustained response to benznidazole.

Neonatal respiratory distress syndrome (RDS) is associated with decreased plasma activity of antithrombin (AT) and increased formation of thrombin. We tested whether AT reduces thrombin formation, improves gas exchange, and decreases the duration of mechanical ventilation and supplemental oxygen. One hundred twenty-two infants were randomized to pasteurized AT concentrate or to placebo. Two ml/kg (equivalent to <em>1</em>00 IU AT/kg) were followed by <em>1</em> ml/kg (50 IU/kg) every 6 h for 48 h. Outcome measures included plasma AT activity, thrombin-AT (TAT) complex, <em>prothrombin</em> <em>fragment</em> (F<em>1</em>+<em>2</em>), the ratio of arterial to alveolar oxygen pressure [(a/A)PO<em>2</em>], and the ventilator efficiency index (VEI). In the AT group (n = 6<em>1</em>), mean (SD) birth weight was <em>1</em>,<em>1</em>98 (30<em>1</em>) g, mean (SD) gestational age (GA) was <em>2</em>8.3 (<em>2</em>.0) wk, 54% were male. In the placebo group (n = 6<em>1</em>), mean (SD) birth weight was <em>1</em>,<em>2</em>0<em>1</em> (3<em>1</em>5) g, mean (SD) GA was <em>2</em>8.8 (<em>2</em>. 3) wk, 5<em>1</em>% were male. In treated infants, AT activity was raised to means of <em>1</em>.69 and <em>2</em>.<em>2</em>5 U/ml at <em>2</em>4 and 48 h, respectively. Corresponding means in control infants were 0.37 and 0.44 U/ml (p < 0.000<em>1</em>). F<em>1</em>+<em>2</em>, but not TAT, was significantly reduced by AT (p = 0. 004). VEI and (a/A)PO<em>2</em> were similar in both groups throughout the first week of life. Median days receiving mechanical ventilation were 7.<em>1</em> (AT) versus 4.8 (placebo), p = 0.00<em>1</em>4. Median days receiving supplemental oxygen were 7.9 (AT) versus 5.5 (placebo), p < 0.000<em>1</em>. There were seven (<em>1</em><em>1</em>.5%) deaths in the AT group and three (4.9%) deaths in the placebo group. We conclude that treatment with AT cannot be recommended in premature infants with RDS.

Background Neutrophil extracellular traps, comprising chromatin and granule proteins, have been implicated in atherothrombosis. Design and methods We investigated whether the circulating neutrophil extracellular traps markers, double-stranded DNA and myeloperoxidase-DNA were associated with clinical outcome and hypercoagulability in patients with stable coronary artery disease. Patients with angiographically verified stable coronary artery disease ( n = <em>1</em>00<em>1</em>) were included. Follow-up was <em>2</em> years, recording <em>1</em>06 clinical endpoints (unstable angina, non-haemorrhagic stroke, myocardial infarction or death). Serum collected at baseline was used to determine double-stranded DNA and myeloperoxidase-DNA levels. Results The neutrophil extracellular traps markers were weakly intercorrelated ( r = 0.<em>1</em>03, P = 0.00<em>1</em>). Patients with the highest quartile of double-stranded DNA had weakly but significantly elevated hypercoagulability markers (<em>prothrombin</em> <em>fragment</em> <em>1</em>+<em>2</em>, D-dimer, free and total tissue factor pathway inhibitor ( P < 0.00<em>1</em> for all)). Men, smokers, patients with metabolic syndrome and patients with a previous myocardial infarction had significantly elevated double-stranded DNA levels ( P ≤ 0.00<em>2</em> for all). Significantly higher double-stranded DNA levels were observed in the group experiencing a clinical endpoint compared to the group without ( P = 0.0<em>1</em>9). When categorising double-stranded DNA into quartiles, a distinct cut-off between the lowest and upper three quartiles was observed. Adjusting for relevant covariates, patients in the upper three quartiles had an odds ratio of <em>2</em>.0<em>1</em> (95% confidence interval <em>1</em>.<em>1</em><em>2</em>, 3.58, P = 0.0<em>1</em>9) for experiencing a clinical endpoint. Myeloperoxidase-DNA was not significantly associated with clinical outcome or hypercoagulability. Conclusions Double-stranded DNA levels were significantly related to adverse clinical outcome after <em>2</em> years, but only weakly associated with hypercoagulability. These observations suggest that the detrimental effects of neutrophil extracellular traps in coronary artery disease might extend beyond those related to hypercoagulability.

Heart failure is associated with a hypercoagulable state. A single-center, randomized, double-blind, placebo-controlled trial was performed to test the hypothesis that warfarin will modify a hypercoagulable state in heart failure. This study included 76 patients with heart failure. At baseline, patients had evidence for a hypercoagulable state with elevated plasma levels of thrombin/antithrombin III (TAT) complexes (3.4 +/- <em>2</em>.0 ng/ml), <em>prothrombin</em> <em>fragment</em> F<em>1</em> + <em>2</em> (<em>1</em>.5 +/- 0.9 nmol/L), and D-dimers (630 +/- 40<em>1</em> ng/ml). Warfarin therapy (international normalized ratio [INR] <em>2</em>.7 +/- <em>1</em>.3) significantly decreased plasma levels of TAT complexes (p < 0.00<em>2</em>), F<em>1</em> + <em>2</em> (p < 0.00<em>1</em>), and D-dimers (p < 0.00<em>1</em>) when compared with baseline values at <em>1</em>, <em>2</em>, and 3 months of therapy. In contrast, patients receiving placebo had persistent elevation of TAT complexes (p = not significant [NS]), F<em>1</em> + <em>2</em> (p = NS), and D-dimers (p = NS) during follow-up at <em>1</em>, <em>2</em>, and 3 months. The two treatment groups followed different trends over time for all three markers (p < 0.00<em>1</em>). The effect of low-intensity warfarin (INR <em>1</em>.3 +/- 0.08) versus moderate-intensity warfarin (INR <em>2</em>.3 +/- <em>1</em>.<em>1</em> ) on markers of hypercoagulability was evaluated in <em>1</em>4 patients. When compared with baseline, low-intensity warfarin administration decreased plasma levels of TAT complexes (p = NS), F<em>1</em> + <em>2</em> (p = 0.05), and D-dimers (p = 0.04). In these patients F<em>1</em> + <em>2</em> was further reduced with moderate-intensity warfarin (p < 0.00<em>1</em>). Our findings suggest that a hypercoagulable state in heart failure can be modified by warfarin therapy.

To study the physiological significance of thrombin as an initiator of intrinsic blood coagulation, activated human platelets were compared with dextran sulfate as a surface for thrombin-catalyzed factor XI activation. Activated gel-filtered platelets promoted factor XI activation by thrombin at initial rates <em>2</em>-5-fold greater than dextran sulfate in the presence of high molecular weight kininogen (HK, 45 nM), ZnCl<em>2</em> (<em>2</em>5 microM), and CaCl<em>2</em> (<em>2</em> mM), conditions optimal for factor XI binding to platelets. Physiological concentrations of HK (636 nM) inhibited factor XI activation by thrombin in a concentration-dependent manner, and this inhibition was reversed by <em>prothrombin</em> (<em>1</em>-3 microM) and by <em>prothrombin</em> <em>fragment</em> <em>1</em>.<em>2</em> (PF<em>1</em>.<em>2</em>), but not by <em>prothrombin</em> <em>fragment</em> <em>1</em> (PF<em>1</em>). Since <em>prothrombin</em> and PF<em>1</em>.<em>2</em> (but not PF<em>1</em>) also displaced HK from its binding site on the Apple <em>1</em> domain of factor XI, we conclude that the Kringle II domain of <em>prothrombin</em> competes with HK for binding to the Apple <em>1</em> domain of factor XI. <em>Prothrombin</em> (<em>1</em>-3 microM) and PF<em>1</em>.<em>2</em> (but not PF<em>1</em>) in the presence of CaCl<em>2</em> (<em>2</em> mM) were able to replace HK (45 nM) in the presence of ZnCl<em>2</em> (<em>2</em>5 microM) as a cofactor for the specific, reversible, high-affinity (Kd approximately <em>2</em>5 nM) binding of factor XI to 947 +/- <em>1</em>50 sites per platelet. This binding is mediated by residues Asn <em>2</em>35-Arg <em>2</em>66 in the Apple 3 domain since a conformationally constrained, synthetic peptide analogue of this sequence inhibits both factor XI binding to activated platelets and platelet-mediated, thrombin-catalyzed factor XI activation in the presence of <em>prothrombin</em> and CaCl<em>2</em>. Finally, <em>prothrombin</em> (<em>1</em>.<em>2</em> microM) and CaCl<em>2</em> (<em>2</em> mM) could substitute for HK (45 nM) and ZnCl<em>2</em> (<em>2</em>5 microM) in promoting optimal rates of thrombin-catalyzed factor XI activation on the platelet surface, thereby initiating the intrinsic coagulation pathway by mechanisms completely independent of the contact phase proteins, factor XII, HK, and prekallikrein.

The coagulation cascade plays a critical role in the development of cardiovascular disease (CVD). Elevated plasma <em>prothrombin</em> <em>fragment</em> <em>1</em> + <em>2</em> (F<em>1</em> + <em>2</em>) and factor VIII antigen (FVIII:Ag) levels have been associated with a hypercoagulable state, enhancing the risk for vascular thrombotic events. Aerobic training is known to reduce CVD risk, and an improved coagulation profile may contribute to this reduction.

OBJECTIVE

To analyze the effect of 6 months of standardized aerobic exercise training on resting F<em>1</em> + <em>2</em> and FVIII:Ag levels in men and postmenopausal women aged 50-75 while accounting for several possibly confounding factors.

METHODS

Sedentary men (N=<em>1</em>6) and women (N=3<em>1</em>) underwent supervised aerobic training 3 d x wk(-<em>1</em>) for 6 months while maintaining the American Heart Association step <em>1</em> diet. Baseline and final testing included measurement of F<em>1</em> + <em>2</em>, FVIII:Ag, plasma lipoprotein-lipid levels, body composition, and VO<em>2</em>max.

RESULTS

When adjusted for baseline values and changes in diastolic blood pressure with training, F<em>1</em> + <em>2</em> was found to decrease significantly with exercise training from <em>1</em>.493 +/- 0.058 to <em>1</em>.4<em>2</em><em>2</em> +/- 0.059 nM (P=0.0<em>1</em>4). FVIII:Ag levels were found to increase significantly with training when adjusted for baseline values, from <em>1</em>5<em>2</em>.5 +/- 6.7% of standard at baseline to <em>1</em>56.0 +/- 6.<em>1</em>% of standard at final testing (P=0.005). Training-induced changes in coagulation markers were independent of changes in blood lipids, aerobic capacity, and body composition.

CONCLUSIONS

: These results indicate that endurance training has a significant impact on the coagulation cascade, reducing coagulation activity in the common pathway and thrombin formation at rest while increasing the activation potential of the intrinsic pathway.

OBJECTIVE

To assess the influence of a variety of HRT regimens on the haemostatic balance using markers of fibrin turnover and inhibitors of coagulation.

METHODS

An open randomised study allocating women to either a control group or five different HRT treatment groups.

METHODS

Gentofte Hospital, Hellerup, and Rigshospitalet, Copenhagen, Denmark.

METHODS

One hundred and forty-nine postmenopausal women without previous venous thromboembolic disease.

METHODS

<em>Prothrombin</em> <em>fragment</em> <em>1</em>+<em>2</em> (F(<em>1</em>+<em>2</em>)), fibrin degradation products, antithrombin, protein C, total protein S and activated protein C-normalised ratio were measured at baseline and after 6 and <em>1</em><em>2</em> months of HRT in six groups of healthy postmenopausal women: (A). no HRT (reference group), (B). continuous oestradiol valerate (E(<em>2</em>)V) plus cyproterone acetate, (C). cyclic E(<em>2</em>)V plus cyproterone acetate, (D). continuous combined oestrogen (E(<em>2</em>)) plus norethindrone acetate, (E). E(<em>2</em>) combined with local delivery of levonorgestrel and (F). E(<em>2</em>)V plus medroxyprogesterone. HRT-induced changes in the concentration of inhibitors of coagulation and markers of fibrin turnover during <em>1</em><em>2</em> months of treatment.

RESULTS

Significant decreases of antithrombin and protein S were found in all treatment groups, of protein C in Groups C, D, E and F and of activated protein C-normalised ratio in Groups E and F. Fibrin degradation products increased after three months of treatment, whereas F(<em>1</em>+<em>2</em>) was persistently increased after three months in Group F. The cumulative response of antithrombin was significantly lower in Groups D, E and F than in the reference group. The cumulative response of protein S and activated protein C-normalised ratio was lower, whereas that of F(<em>1</em>+<em>2</em>) was significantly higher in Group F than in the reference group.

CONCLUSIONS

HRT reduces the inhibitory potential of coagulation significantly. The effect is related to the type of E(<em>2</em>)/progestin combination administered, but seems to be oestrogen-derived as the most pronounced effect is found with only quarterly progestin intake. Such procoagulant activity of HRT may well translate into clinical manifestations in thrombosis-prone individuals.