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Introduction: There are no published data on the status of endogenous activated protein C (APC) in pulmonary embolism (PE), and no data on the effect of drotrecogin alfa (activated) (DAA) given in addition to therapeutic dose enoxaparin., Methods: In this double-blind clinical trial, 47 patients with computed tomography (CT)-confirmed acute submassive PE treated with 1 mg/kg body weight of enoxaparin twice daily were randomized to groups receiving a 12-hour intravenous infusion of 6, 12, 18, or 24 μg/kg/hour of DAA or a placebo. Blood samples were drawn before starting DAA infusion, after 4, 8 and 12 hours (at the end of the infusion period), and on treatment days 2, 3, 4, 5 and 6., Results: Initial endogenous plasma activated protein C (APC) levels were 0.36 ± 0.48 ng/ml (<0.10 to 1.72 ng/ml) and remained in the same range in the placebo group. APC levels in patients treated with DAA were 13.67 ± 3.57 ng/ml, 32.71 ± 8.76 ng/ml, 36.13 ± 7.60 ng/ml, and 51.79 ± 15.84 ng/ml in patients treated with 6, 12, 18, and 24 μg/kg/hour DAA, respectively. In patients with a D-dimer level >4 mg/L indicating a high level of acute fibrin formation and dissolution, DAA infusion resulted in a more rapid drop in soluble fibrin, D-dimer, and fibrinogen/fibrin degradation products (FDP) levels, compared to enoxaparin alone. There was a parallel decline of soluble fibrin, D-dimer, FDP, and plasmin-plasmin inhibitor complex (PPIC) in response to treatment with enoxaparin ± DAA, with no evidence of a systemic profibrinolytic effect of the treatment., Conclusions: In patients with acute submassive PE endogenous APC levels are low. DAA infusion enhances the inhibition of fibrin formation., Trial Registration: ClinicalTrials.gov: NCT00191724.

Disseminated intravascular coagulation in sepsis is associated with microvascular thrombosis and organ dysfunction. It was expected that prothrombotic disposition such as factor V Leiden (FVL) mutation would worsen clinical outcome. Astonishingly, clinical trial and animal experimental data indicate that FVL can be associated with improved survival. This study investigated the effect of FVL on the response to endotoxin of the coagulation and fibrinolytic system in humans. Fourteen healthy male subjects without FVL and 15 healthy males with heterozygous FVL received an intravenous bolus dose of endotoxin, 2 ng/kg of body weight. Blood samples were drawn before and 1, 2, 4, 6, and 24 hours after administration of the endotoxin. Injection of endotoxin led to a more pronounced increase in soluble fibrin in patients with FVL than in controls. Patients with FVL displayed a more sustained increase in plasmin-plasmin inhibitor complex after 4, 6, and 24 hours. Patients with FVL mutation also displayed higher levels of D-dimer and fibrinogen-fibrin degradation products in plasma after 24 hours. Patients with FVL generate higher levels of soluble fibrin, which may serve as cofactor in tissue plasminogen activator-induced plasminogen activation, leading to a more sustained activation of fibrinolysis with production of more fibrinogen- and fibrin-degradation products.

Background: Low antithrombin levels may compromise the anticoagulant effect of heparin and heparin-related compounds, such as fondaparinux., Methods: We compared the anticoagulant effect of 10 concentrations of fondaparinux added to plasma samples with normal range (n = 25, antithrombin 95.4% +/- 9.2%) and low antithrombin (n = 22, antithrombin 45.5% +/- 13.2%) levels, using the Heptest coagulation assay., Results: Heptest clotting time was shorter at any given fondaparinux concentration in the antithrombin-deficient samples, indicating less anticoagulant effect than in the group with normal antithrombin levels. At a high fondaparinux concentration, a saturation effect is observed with no further increase in Heptest clotting time. Addition of antithrombin concentrates results in a shift of the dose-response curve. When antithrombin concentrate was added, Heptest clotting time increased up to a fondaparinux concentration of 10 microg/mL., Conclusions: In the conventional prophylactic and therapeutic dose range, not only treatment with antithrombin concentrates but also an increase in fondaparinux dose normalizes the anticoagulant effect. A saturation effect is observed at high fondaparinux concentrations. Higher levels of antithrombin lead to an exaggerated effect of fondaparinux on Heptest.

Fibrinogen concentration influences mechanical and functional properties of the clot. The purpose of the present study was to identify threshold concentrations of fibrinogen resulting in relevant changes in whole blood clot elastic modulus and platelet contractile force, as well as plasma prothrombin time and activated partial thromboplastin time. We measured clot elastic modulus, platelet contractile force, and other hemostasis parameters in whole blood samples from 552 patients admitted to a surgical intensive care unit. Platelet contractile force and clot elastic modulus were measured using the Hemodyne apparatus. Fibrinogen levels were between less than 0.10 and 9.44 g/l, with a mean of 2.41 g/l. Mean platelet count was 203 x 10(9) l(-1), with a range of 16 x 10(9) l(-1) to 682 x 10(9) l(-1). High levels of fibrinogen result in improved mechanical stability and improved interaction of platelets with the fibrin network. Clot elastic modulus and platelet contractile force are correlated positively with plasma fibrinogen concentration. However, there was no threshold concentration or ceiling effect concerning the mechanical properties of the clots. In contrast, clotting time assays such as prothrombin time, thrombin time, or activated partial thromboplastin time are influenced by the fibrinogen concentration only at levels below 1 g/l. In linear regression analysis, clot elastic modulus was mainly influenced by fibrinogen concentration (F = 185.4, P < 0.0001), whereas platelet contractile force was influenced by fibrinogen (F = 197.0, P < 0.0001) and platelet count (F = 104.7, P < 0.0001). The present data show that 1 g/l is a threshold fibrinogen concentration for an effect on coagulation assays such as prothrombin time, thrombin time, or activated partial thromboplastin time, but increasing fibrinogen concentrations above this level results in further continuous improvement of mechanical properties of the whole blood clot.

High intake of saturated fat is a predictor of coronary heart disease mortality. The phenomenon of postprandial angina pectoris has been described many years ago. Although earlier studies have demonstrated postprandial activation of coagulation factors VII and XII, platelets and monocytes, conclusive evidence for intravascular fibrin formation after a fat-rich meal has not been reported yet. The present study included 33 healthy physicians (7 females, 26 males) with a mean age of 42 years (range 27-62 years), and 27 coronary heart disease patients (8 females, 19 males) with a mean age of 63 years (range 47-81 years). Of the coronary heart disease patients, 26/27 were treated with acetylsalicylic acid and 25/27 with lipid-lowering drugs simvastatin or atorvastatin. Blood samples were drawn 30-60 min before and 30-60 min after a dinner consisting of rye bread with liversausage and black pudding as hors d'oeuvre, lettuce with smoked bacon in a lard dressing, stuffed fried goose with red cabbage, potato dumplings and sweet chestnuts, and white and brown mousse au chocolat. Average intake per person was 3760 kcal, with 125.9 g protein, 238.0 g fat and 268.9 g carbohydrate. We measured a significant postprandial increase in fibrinopeptide A (FpA) levels from 1.14+/-1.23 microg/l to 4.18+/-2.86 microg/l (p<0.0001) in healthy probands, and 4.66+/-13.61 microg/l to 12.80+/-15.04 microg/l (p<0.0001) in coronary heart disease patients. Triglycerides increased from 137.6+/-60.5 to 201.5+/-75.0 mg/dl in healthy probands and from 211.9+/-94.6 to 273.6+/-122.5 mg/dl in coronary heart disease patients. Fat-rich meals may cause procoagulant episodes, which may promote vascular complications such as myocardial infarction, transient ischemia attacks in susceptible persons.

D-dimer is an indicator for in vivo fibrin formation, reflecting the formation of fibrin crosslinked by factor XIIIa. D-dimer assays are frequently used in emergency situations, such as diagnosis of venous thrombosis and pulmonary embolism, or disseminated intravascular coagulation. In these conditions, short sample turnaround times are essential. The PATHFAST D-dimer assay allows rapid quantitative measurement of D-dimer in plasma and whole blood. The study shows an excellent correlation between whole blood and plasma measurement of D-dimer both in the high range, as well as in the normal range. Intra-assay and inter-assay coefficients of variation (CV) were below 10%. The upper limit of normal (ULN = mean value measured in 100 samples from healthy blood donors + 2 x S.D.) was approximately 1 microg/ml FEU, using the assay-specific calibration. The maximal value measured in 20 replicates of calibrator 1 containing no D-dimer antigen was 0.00052 microg/ml FEU, and this 10-fold lower than the declared detection limit of 0.005 microg/ml FEU. In conclusion, the PATHFAST D-dimer assay is the first automated fully quantitative D-dimer assay, which can use plasma and whole blood as sample materials in parallel.