Comparison of Acquired Activated Protein C Resistance, Using the CAT and ST-Genesia Analysers and Three Thrombin Generation Methods, in APS and SLE Patients.

Background: Acquired activated protein C resistance (APCr) has been identified in antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE).

Objective: To assess agreement between the ST-Genesia and CAT analysers in identifying APCr prevalence in APS/SLE patients, using three thrombin generation (TG) methods.

Methods: APCr was assessed with the ST-Genesia using STG-ThromboScreen and with the CAT using recombinant human activated protein C and Protac in 105 APS, 53 SLE patients and 36 thrombotic controls.

A performance evaluation of chemiluminescence enzyme immunoassays on the Sysmex CN-6500 haemostasis analyser.

Background: The Sysmex CN-6500 is a new haemostasis analyser with an integrated immunoassay module that performs chemiluminescence enzyme assay (CLEIA) in addition to coagulation, turbidimetric, chromogenic and platelet aggregation tests.

Aims: To evaluate the analytical performance of the CN-6500 against the predicate device (Sysmex HISCL-800) for soluble thrombomodulin (TM), thrombin-antithrombin (TAT), tissue plasminogen activator/plasminogen activator inhibitor 1 complex (tPAI-C) and plasmin α2 plasmin inhibitor complex (PIC) assays.

Methods: Imprecision was assessed by testing two levels of quality control plasmas 10 times on 5 separate days.

Anti-Platelet Aggregation and Anti-Cyclooxygenase Activities for a Range of Coffee Extracts ().

Coffee is rich in caffeine (CF), chlorogenic acid (CGA) and phenolics. Differing types of coffee beverages and brewing procedures may result in differences in total phenolic contents (TPC) and biological activities. Inflammation and increases of platelet activation and aggregation can lead to thrombosis.

A comparative evaluation of the CN-6000 haemostasis analyser using coagulation, amidolytic, immuno-turbidometric and light transmission aggregometry assays.

Background: The CN-6000 (Sysmex Corp.) is a new haemostasis analyser with blood coagulation, amidolytic, immuno-turbidometric and light transmission aggregometry (LTA) capabilities. Transmitted light is monitored at multiple wavelengths (340, 405, 575, 660, 800 nm), from an LED light source.

A practical method for reducing the interference due to lipaemia in coagulation tests.

Introduction: Plasma samples with gross lipaemia present a challenge for coagulation laboratories using optical analysers. High-speed centrifugation may be used to remove excess lipids but it has not established whether this affects haemostasis tests. The aims were to determine whether the removal of lipid by centrifugation affects PT, APTT, fibrinogen, D-dimer and von Willebrand factor activity measurements.

Comparison of real world and core laboratory lupus anticoagulant results from the Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) clinical database and repository.

Background: Variability remains a challenge in lupus anticoagulant (LA) testing.

Objective: To validate LA test performance between Antiphospholipid Syndrome Alliance for Clinical Trials and International Networking (APS ACTION) Core laboratories and examine agreement in LA status between Core and local/hospital laboratories contributing patients to this prospective registry.

Methods: Five Core laboratories used the same reagents, analyzer type, protocols, and characterized samples for LA validation.

Clinical and laboratory practice for lupus anticoagulant testing: An International Society of Thrombosis and Haemostasis Scientific and Standardization Committee survey.

Background: Current guidelines have contributed to more uniformity in the performance and interpretation of lupus anticoagulant (LA) testing. However, points to reconsider include testing for LA in patients on anticoagulation, cut-off values, and interpretation of results.

Objectives: The aim of this International Society of Thrombosis and Haemostasis Scientific and Standardization committee (ISTH SSC) questionnaire was to capture the spectrum of clinical and laboratory practice in LA detection, focusing on variability in practice, so that the responses could inform further ISTH SSC recommendations.

Direct Oral Anticoagulants Use in Antiphospholipid Syndrome: Are These Drugs an Effective and Safe Alternative to Warfarin? A Systematic Review of the Literature: Comment.

We respond to comments by Dufrost et al. about the RAPS trial, in particular, showing that the trial did achieve its target sample size; pointing out that thrombin potential is not synonymous with overall thrombin generation; confirming that overall, no increased thrombotic risk was evident comparing rivaroxaban with warfarin; and that high-risk patients (28% were triple positive, representative of patients with venous thromboembolism requiring standard-intensity anticoagulation) were included; and clarifying our rationale for using a laboratory surrogate primary outcome measure instead of a clinical one.

Plasma factor XIII level variations during menstrual cycle.

Factor XIII (FXIII) has an important role in the control of bleeding through fibrin cross-linking; however, its effect within the menstrual cycle is not fully understood. The aim of this study was to examine changes in FXIII activity during the normal menstrual cycle and correlate FXIII activity with menstrual blood loss. A total of 32 healthy normal women of reproductive age were recruited.

Rivaroxaban versus warfarin to treat patients with thrombotic antiphospholipid syndrome, with or without systemic lupus erythematosus (RAPS): a randomised, controlled, open-label, phase 2/3, non-inferiority trial.

Background: Rivaroxaban is established for the treatment and secondary prevention of venous thromboembolism, but whether it is useful in patients with antiphospholipid syndrome is uncertain.

Methods: This randomised, controlled, open-label, phase 2/3, non-inferiority trial, done in two UK hospitals, included patients with antiphospholipid syndrome who were taking warfarin for previous venous thromboembolism, with a target international normalised ratio of 2·5. Patients were randomly assigned 1:1 to continue with warfarin or receive 20 mg oral rivaroxaban daily.

Relationship between ADAMTS13 activity, von Willebrand factor antigen levels and platelet function in the early and late phases after TIA or ischaemic stroke.

Background: Reduced ADAMTS13 activity is seen in thrombotic thrombocytopenic purpura (TTP), and may lead to accumulation of prothrombotic ultra-large von Willebrand factor (ULVWF) multimers in vivo. ADAMTS13 activity and its relationship with VWF antigen (VWF:Ag) levels and platelet function in 'non-TTP related' TIA or ischaemic stroke has not been comprehensively studied.

Methods: In this prospective pilot observational analytical case-control study, ADAMTS13 activity and VWF:Ag levels were quantified in platelet poor plasma in 53 patients in the early phase (≤ 4 weeks) and 34 of these patients in the late phase (≥ 3 months) after TIA or ischaemic stroke on aspirin.

Diagnosis and management of non-criteria obstetric antiphospholipid syndrome.

Accurate diagnosis of obstetric antiphospholipid syndrome (APS) is a prerequisite for optimal clinical management. The international consensus (revised Sapporo) criteria for obstetric APS do not include low positive anticardiolipin (aCL) and anti β2 glycoprotein I (aβ2GPI) antibodies (< 99th centile) and/or certain clinical criteria such as two unexplained miscarriages, three non-consecutive miscarriages, late pre-eclampsia, placental abruption, late premature birth, or two or more unexplained in vitro fertilisation failures. In this review we examine the available evidence to address the question of whether patients who exhibit non-criteria clinical and/or laboratory manifestations should be included within the spectrum of obstetric APS.

Residual plasmatic activity of ADAMTS13 is correlated with phenotype severity in congenital thrombotic thrombocytopenic purpura.

The quantification of residual plasmatic ADAMTS13 activity in congenital thrombotic thrombocytopenic purpura (TTP) patients is constrained by limitations in sensitivity and reproducibility of commonly used assays at low levels of ADAMTS13 activity, blunting efforts to establish genotype-phenotype correlations. In the present study, the residual plasmatic activity of ADAMTS13 was measured centrally by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (limit of detection = 0.5%) in 29 congenital TTP patients.

Development and application of an automated chromogenic thrombin generation assay that is sensitive to defects in the protein C pathway.

Background: Activated protein C resistance (APCR) within a thrombin generation test (TGT) system is associated with an increased risk of venous thromboembolism (VTE). However, application of the TGT is restricted by the analytical platforms used to monitor thrombin generation. Using a routine coagulation analyser we have developed an automated chromogenic TGT that is sensitive to defects in the protein C pathway.

The effect of total hip/knee replacement surgery and prophylactic dabigatran on thrombin generation and coagulation parameters.

Introduction: Total hip/knee replacement surgery (THR/TKR respectively) is associated with an increased risk of venous thromboembolism. Dabigatran is recommended as a thromboprophylactic agent post orthopaedic surgery. The aim of this study was to assess the post-operative (Day-1 and Day-2) effect of prophylactic Dabigatran on: the thrombin generation (TG) assay; prothrombin fragment 1.

The impact of elective knee/hip replacement surgery and thromboprophylaxis with rivaroxaban or dalteparin on thrombin generation.

Total hip/knee replacement surgeries are associated with an increased risk of venous thromboembolism and post-operative thromboprophylaxis has become standard treatment. This study aimed to: (i) assess the impact of hip/knee replacement surgery on ex vivo thrombin generation (TG), prothrombin fragments 1 + 2 (F1 + 2), thrombin-antithrombin complexes (TAT) and D-dimer; (ii) compare the anticoagulant effects of dalteparin and rivaroxaban on TG 24 h after surgery. Haemostatic variables were assessed in plasma samples of 51 patients taken pre-operatively, peri-operatively, and 24 h post-operatively.

Point-of-care testing in haemostasis.

Point-of-care testing (POCT) in haematology has seen a significant increase in both the spectrum of tests available and the number of tests performed annually. POCT is frequently undertaken with the belief that this will reduce the turnaround time for results and so improve patient care. The most obvious example of POCT in haemostasis is the out-of-hospital monitoring of the International Normalized Ratio in patients receiving a vitamin K antagonist, such as warfarin.

Dual effect of Platelet Factor 4 on the activities of Factor Xa.

Platelet Factor 4 (PF4) prevents inhibition of blood coagulation proteases by heparin via formation of a putative enzyme-PF4 complex. To investigate the contribution of the latter, the activity of factor Xa (fXa) was determined in chromogenic assays measuring hydrolysis of a peptide substrate S2765 or cleavage of the macromolecular substrate prothrombin in the activating complex, prothrombinase. Upon preincubation with fXa and heparin, PF4 at about 250 nM decreased the k(cat) of S2765 hydrolysis about fivefold and that of prothrombin activation about 25-fold.

Performance evaluation of a new small-volume coagulation monitor: the SmartCheck INR system.

The SmartCheck INR (Unipath, Bedford, England) is a point-of-care device for professional and patient self-monitoring of oral anticoagulant therapy. It measures the international normalized ratio (INR) and assesses test strip integrity, temperature, and sample quality. No significant differences were found in SmartCheck INR results from 3 different instruments or in 3 test-strip lots.

Thrombin generation: a comparison of assays using platelet-poor and -rich plasma and whole blood samples from healthy controls and patients with a history of venous thromboembolism.

We have developed a whole blood thrombin generation (TG) assay whereby TG is initiated with a low-tissue factor concentration and monitored using a fluorogenic thrombin substrate. Significantly higher values were found in blood samples from 50 patients with a history of venous thromboembolism (VTE) compared with 31 healthy controls (HC), for peak height (P = 0.0034) and endogenous thrombin potential (ETP) (P = 0.

The role of endogenous kallikrein inhibition in perioperative transfusion and adverse outcome in cardiac surgical patients.

Objective: The goal of this study was to explore the relationship among endogenous plasma kallikrein inhibition (KI), perioperative bleeding, and adverse outcomes in cardiac surgery.

Design: A prospective, observational study.

Setting: University teaching hospitals.