A novel assay for studying the involvement of blood cells in whole blood thrombin generation.

Background: Fluorogenic thrombin generation (TG) assays are commonly used to determine global coagulation phenotype in plasma. Whole blood (WB)-TG assays reach one step closer to physiology by involving the intrinsic blood cells, but erythrocytes cause variable quenching of the fluorescence signals, hampering its routine application.

Objective: To develop a new assay for continuous WB-TG measurement.

Thrombin dynamics in children with liver disease or extrahepatic portal vein obstruction or shunt.

Introduction: Changes in the coagulation profile in children with liver disease and extrahepatic portal vein obstruction or shunt result in both bleeding and thrombosis. Routine coagulation tests do not accurately predict bleeding risk, as they are not sensitive to changes in anticoagulant factors. The thrombin generation assay could be suitable for describing the overall balance of coagulation in children with liver disease.

The anticoagulant effect of dabigatran is reflected in the lag time and time-to-peak, but not in the endogenous thrombin potential or peak, of thrombin generation.

Introduction: Calibrated automated thrombinography (CAT) is a sensitive method to assess coagulation. Dabigatran inhibits both free thrombin and the αmacroglobulin (αM)-thrombin complex, which results in an erroneously increased peak and endogenous thrombin potential (ETP) without affecting lag time and time-to-peak. The aim of this study was to elucidate the artefacts in CAT when dabigatran is present.

Increased blood levels of cellular fibronectin in asthma: Relation to the asthma severity, inflammation, and prothrombotic blood alterations.

Background: Recently, we have reported that asthma is characterized by prothrombotic blood alterations, which were related to the low-grade inflammatory state. Inflammation, however, may also lead to vascular dysfunction. The aim of this study was to evaluate plasma levels of cellular fibronectin (cFN), a marker of vascular injury in asthmatics, and to analyze their impact on described previously prothrombotic blood alterations.

Prothrombin conversion is accelerated in the antiphospholipid syndrome and insensitive to thrombomodulin.

Antiphospholipid syndrome (APS) is a condition in which the presence of antibodies against phospholipid-binding proteins is associated with thrombophilia and/or pregnancy morbidity. Although antiphospholipid antibodies have anticoagulant characteristics in vitro, they are associated with thromboembolic complications. Thrombin generation (TG) is a sensitive global test of coagulation, and elevated TG is associated with thrombosis.

Impaired fibrinolysis and lower levels of plasma α-macroglobulin are associated with an increased risk of severe asthma exacerbations.

Recently we have reported that asthma is associated with enhanced plasma thrombin formation, impaired fibrinolysis and platelet activation. In the present study we investigated whether described prothrombotic blood alterations might predispose to thromboembolic events or asthma exacerbations. In 164 adult asthmatics we assessed clinical events during 3-year follow-up and analyzed their associations with measured at baseline prothrombotic blood parameters.

Interindividual Variability and Normal Ranges of Whole Blood and Plasma Thrombin Generation.

Background: Assays measuring thrombin generation (TG) in plasma increasingly gained attention in the field of thrombosis and hemostasis. Adaptation of the method enabled the measurement of TG in whole blood (WB). Despite their potential, TG assays did not reach the stage of universal clinical application, partly because of the absence of normal ranges.

Decreased prothrombin conversion and reduced thrombin inactivation explain rebalanced thrombin generation in liver cirrhosis.

Impaired coagulation factor synthesis in cirrhosis causes a reduction of most pro- and anticoagulant factors. Cirrhosis patients show no clear bleeding or thrombotic phenotype, although they are at risk for both types of hemostatic event. Thrombin generation (TG) is a global coagulation test and its outcome depends on underlying pro- and anticoagulant processes (prothrombin conversion and thrombin inactivation).

Prothrombotic State in Asthma Is Related to Increased Levels of Inflammatory Cytokines, IL-6 and TNFα, in Peripheral Blood.

Recently, we have reported that asthma is associated with enhanced plasma thrombin formation and impaired fibrinolysis. The mechanisms underlying the prothrombotic state in this disease are unknown. Our aim was to investigate whether prothrombotic alterations in asthmatics are associated with inflammation.

A reduction of prothrombin conversion by cardiac surgery with cardiopulmonary bypass shifts the haemostatic balance towards bleeding.

Cardiac surgery with cardiopulmonary bypass (CPB) is associated with blood loss and post-surgery thrombotic complications. The process of thrombin generation is disturbed during surgery with CPB because of haemodilution, coagulation factor consumption and heparin administration. We aimed to investigate the changes in thrombin generation during cardiac surgery and its underlying pro- and anticoagulant processes, and to explore the clinical consequences of these changes using in silico experimentation.

Asthma is associated with enhanced thrombin formation and impaired fibrinolysis.

Background: There is evidence that altered blood coagulation and fibrinolysis are involved in the pathogenesis of asthma. Increased thromboembolic risk has been reported in asthmatics.

Objective: To investigate whether enhanced thrombin generation and impaired fibrinolysis occur in asthmatics.

Strenuous exercise induces a hyperreactive rebalanced haemostatic state that is more pronounced in men.

Physical exercise is recommended for a healthy lifestyle. Strenuous exercise, however, may trigger the haemostatic system, increasing the risk of vascular thrombotic events and the incidence of primary cardiac arrest. Our goal was to study the effects of strenuous exercise on risk factors of cardiovascular disease.

Low paediatric thrombin generation is caused by an attenuation of prothrombin conversion.

Thrombin generation (TG) is decreased in children. TG is determined by two underlying processes: the conversion of prothrombin to thrombin and the inactivation of thrombin. Therefore, lower TG capacity in children can either be caused by a reduction of prothrombin conversion, an increase of thrombin inactivation, or both.

Differences in the mechanism of blood clot formation and nanostructure in infants and children compared with adults.

Introduction: Infants and children have a lower incidence of thrombosis compared with adults. Yet, the mechanism of blood clot formation and structure in infants and children, as the end product of coagulation, has not been studied. This study aimed to establish differences in the mechanism of thrombin generation, fibrin clot formation and response to thrombolysis in infants and children compared with adults.

Thrombin Generating Capacity and Phenotypic Association in ABO Blood Groups.

Individuals with blood group O have a higher bleeding risk than non-O blood groups. This could be explained by the lower levels of FVIII and von Willebrand Factor (VWF) levels in O individuals. We investigated the relationship between blood groups, thrombin generation (TG), prothrombin activation and thrombin inactivation.

Platelet-Associated Matrix Metalloproteinases Regulate Thrombus Formation and Exert Local Collagenolytic Activity.

Objective: Platelets are increasingly implicated in processes beyond hemostasis and thrombosis, such as vascular remodeling. Members of the matrix metalloproteinase (MMP) family not only remodel the extracellular matrix but also modulate platelet function. Here, we made a systematic comparison of the roles of MMP family members in acute thrombus formation under flow conditions and assessed platelet-dependent collagenolytic activity over time.

The balance of pro- and anticoagulant processes underlying thrombin generation.

Background: The generation of thrombin in time is the combined effect of the processes of prothrombin conversion and thrombin inactivation. Measurement of prothrombin consumption used to provide valuable information on hemostatic disorders, but is no longer used, due to its elaborate nature.

Objectives: Because thrombin generation (TG) curves are easily obtained with modern techniques, we developed a method to extract the prothrombin conversion curve from the TG curve, using a computational model for thrombin inactivation.

The effect of fibrin(ogen) on thrombin generation and decay.

Defibrination causes a ~30% decrease of thrombin generation (TG) which can be restored by adding native fibrinogen in its original concentration (3 mg/ml). The fibrinogen variant γA/γ', which binds thrombin with high affinity, is over four times more efficient in this respect than the more common γA/γA form. By using high tissue factor concentrations we accelerated prothrombin conversion so as to obtain a descending part of the TG curve that was governed by thrombin decay only.

Data management in thrombin generation.

To obtain a thrombin generation (TG) curve from the conversion of added fluorogenic substrate, thrombin concentrations are to be derived from the observed velocity of increase of fluorescence (dF/dt). The relation between velocity and thrombin concentration varies during the experiment because substrate is consumed and because fluorescence is not linear with the concentration of product. Here we review the techniques that we developed to:

Study of ion beam extraction and transport from an electron cyclotron resonance ion source.

We have started an experimental and theoretical program to better understand the extraction and transport of intense multiply charged ion beams from an electron cyclotron resonance ion source (ECRIS). In this paper we present the first results of this program concerning a simple, monocomponent He(+) beam extracted from an ECRIS. We have calculated the ion trajectories starting from the ECRIS plasma electrode up to the image plane of the analyzing magnet taking into account space-charge effects and fringe fields.