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Background: Chronic obstructive pulmonary disease (COPD) is associated with an increased risk for thromboembolic events. We investigated thrombin generation profiles in COPD patients and their dependence on plasma factor/inhibitor composition., Methods: Factors (f) (fII, fV, fVII, fVIII, fIX, fX), antithrombin, protein C (PC) and free tissue factor pathway inhibitor (fTFPI) from 60 COPD patients (aged 64.2 ± 10.1 years; a mean forced expiratory volume in 1 second [FEV(1)], 55.6 ± 15.8% of predicted values) were compared with those for 43 controls matched for age, sex, weight and smoking. Patients receiving anticoagulation were excluded. Using each individual's plasma coagulation protein composition, tissue factor-initiated thrombin generation was assessed computationally., Results: COPD patients had higher fII (115 ± 16 vs 102 ± 10%, p < 0.0001), fV (114 ± 19 vs 102 ± 12%, p = 0.0002), fVII (111 ± 15 vs 102 ± 17%, p = 0.002), fVIII (170 ± 34 vs 115 ± 27%, p < 0.0001), and fIX (119 ± 21 vs 107 ± 17%, p = 0.003), and lower fTFPI (17.7 ± 3.2 vs 18.9 ± 3.2 ng/ml, p = 0.047) compared with controls, while fX, antithrombin, and PC were similar in both groups. Computational thrombin generation profiles showed that compared with controls, COPD patients had higher maximum thrombin levels (+28.3%, p < 0.0001), rates of thrombin generation (+46.1%, p < 0.0001) and total thrombin formation (+14.4%, p < 0.001), together with shorter initiation phase of thrombin generation (p < 0.0001) and the time to maximum thrombin levels (p < 0.0001). Thrombin generation profiles in COPD patients can be normalized via correction of fII, fVIII , fIX and TFPI. The severity of COPD and inflammatory markers were not associated with thrombin generation profiles., Conclusions: Prothrombotic phenotype in COPD patients is largely driven by increased prothrombin, fVIII, fIX, and lower fTFPI., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Objective: Homocysteine (Hcy) is a risk factor for thrombosis. We investigated a hypothesis that the clot permeability and its resistance to fibrinolysis is associated with plasma total Hcy (tHcy) in human subjects., Methods and Results: We studied healthy men not taking any medication (n=76), male patients with advanced coronary artery disease (CAD) taking low-dose aspirin (n=33), men with diabetes mellitus diagnosed recently (median hemoglobin A(1c) 7.65%; n=16), and patients with isolated hypercholesterolemia (>7.0 mmol/L; n=15). We assessed clot permeability and turbidimetric lysis time as the determinants of fibrin clot structure. In a regression model, including age and fibrinogen, plasma tHcy was an independent predictor of clot permeation and fibrinolysis time in healthy subjects (R2=0.88, P<0.0001 and R2=0.54, P<0.0001, respectively). In CAD patients, tHcy and fibrinogen were stronger predictors of the permeation coefficient (R2=0.84; P<0.0001) than was fibrinogen alone (R2=0.66; P<0.0001), whereas tHcy was the only predictor of lysis time (R2=0.69; P<0.0001). Elevated tHcy levels observed after methionine load were not associated with any of the fibrin clot properties. In patients with diabetes or hypercholesterolemia, the influence of Hcy on permeation and, to a lesser extent, on the lysis time was obscured by dominant effects of glucose and cholesterol. In 20 asymptomatic men with hyperhomocysteinemia treated with folic acid, reduction in tHcy levels resulted in increased clot permeability (P=0.0002) and shorter lysis time (P<0.0001)., Conclusions: Our results indicate that plasma tHcy predicts clot permeation and susceptibility to fibrinolysis in healthy men and CAD patients. Our data are consistent with a mechanism of thrombosis in hyperhomocysteinemia, which involves modification of fibrinogen by Hcy-thiolactone.