The activated seven lupus anticoagulant assay detects clinically significant antibodies.

Lupus anticoagulants are a heterogeneous group of autoantibodies detected by their effects on phospholipid-dependent coagulation assays. Persistent lupus anticoagulants are associated with thrombotic disease, but not all are clinically significant. Antibody heterogeneity and reagent and test variability dictate that at least 2 tests, of different types, should be used to screen lupus anticoagulants.

Characterisation of five factor XI mutations.

A large scale factor XI (FXI) mutation screening program identified a number of novel candidate mutations and previously reported mutations and polymorphisms. Five potential missense mutations were selected for further study; these included two novel missense mutations - Met-18Ile (p.Met1Ile) and Met102Thr (p.

The dilution effect of equal volume mixing studies compromises confirmation of inhibition by lupus anticoagulants even when mixture specific reference ranges are applied.

Introduction: One of the recommended criteria for the laboratory diagnosis of lupus anticoagulants (LA) is demonstration of inhibitory activity. This is confirmed by performing mixing tests with normal plasma, usually in a 1:1 ratio, and demonstrating persistence of an abnormal clotting time in the screening test with significant confirmatory test reduction. However, the mixing with normal plasma can dilute the antibodies to undetectable levels and generate apparent negative results.

The significance of published polymorphisms in 14 cases of mild factor VII deficiency.

Factor VII (FVII) plays a critical role in the initiation of blood coagulation, and patients with dysfunctional or reduced levels of this protein are susceptible to mucosal bleeding. There is poor correlation between the clinical presentation and the phenotypic data; and in cases of a mild bleeding tendency, mild to moderate reductions in both FVII antigen and activity may be overlooked. The prevalence of FVII deficiency may therefore be underestimated.

Determination of the urinary aglycone metabolites of vitamin K by HPLC with redox-mode electrochemical detection.

We describe a method for the determination of the two major urinary metabolites of vitamin K as the methyl esters of their aglycone structures, 2-methyl-3-(3'-3'-carboxymethylpropyl)-1,4-naphthoquinone (5C-aglycone) and 2-methyl-3-(5'-carboxy-3'-methyl-2'-pentenyl)-1,4-naphthoquinone (7C-aglycone), by HPLC with electrochemical detection (ECD) in the redox mode. Urinary salts were removed by reversed-phase (C18) solid-phase extraction (SPE), and the predominantly conjugated vitamin K metabolites were hydrolyzed with methanolic HCl. The resulting carboxylic acid aglycones were quantitatively methylated with diazomethane and fractionated by normal-phase (silica) SPE.

Germline mosaicism resulting in the transmission of severe hemophilia B from a grandfather with a mild deficiency.

We report a family in which the normal pattern of X-linked inheritance of hemophilia B (Factor IX deficiency) is complicated by mosaicism in the proband's maternal grandfather. The proband, an infant with severe Factor IX deficiency, was initially thought to be a sporadic case. Testing of other family members identified his mother as a carrier of the disorder, and his asymptomatic maternal grandfather as having very mild FIX deficiency.

Heterogeneity of Russell's viper venom affects the sensitivity of the dilute Russell's viper venom time to lupus anticoagulants.

A number of studies have shown that commercial dilute Russell's viper venom time (DRVVT) reagents vary in their sensitivity for lupus anticoagulant (LA) detection. The differences in performance are considered to be predominantly due to antibody heterogeneity and a wide variation in phospholipid content, and also the techniques and clot detection methods employed. The present study compared the LA detection rates of five different Russell's viper venom (RVV) preparations using identical phospholipid reagents to assess the contribution of venom heterogeneity to LA detection by DRVVT.

Tinzaparin sodium for thrombosis treatment and prevention during pregnancy.

Objective: This study was undertaken to assess the pharmacodynamic profile, safety, and efficacy of tinzaparin during pregnancy.

Study Design: Fifty-four pregnant women, 12 for treatment of thrombosis and 42 for thromboprophylaxis, received tinzaparin by once daily injection. Four-hour postdose anti-Xa results were analyzed by use of repeated measures statistical methods.

Prevalence of hyperhomocysteinemia and the MTHFR C677T polymorphism in patients with arterial and venous thrombosis from North Western Russia.

Conflicting data from Western European and USA population studies led us to investigate hyperhomocysteinemia (HHcy), the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms and thrombotic disease in North Western Russia. Plasma total homocysteine (tHcy) levels, MTHFR C677T genotype, selected life style determinants and haemostatic factor activity were determined in patients with arterial (n = 33), venous (n = 40), arterial + venous (n = 11) thrombosis and healthy controls (n = 30). We found raised median tHcy levels in all patient groups vs.

Hyperhomocysteinemia and B-vitamin status after discontinuation of oral anticoagulation therapy in patients with a history of venous thromboembolism.

Although hyperhomocysteinemia is an established risk factor for venous thromboembolism there is no consensus for routine determination of circulating homocysteine in the UK, either at the beginning or end of oral anticoagulation therapy. The purpose of this study was to evaluate the prevalence of hyperhomocysteinemia and its relationship to folate and vitamin B12 status in subjects with venous thromboembolism 4 weeks after discontinuation of warfarin therapy. In 78 consecutively recruited patients, plasma homocysteine was significantly higher (p < 0.

Glanzmann's thrombasthenia proposed optimal management during surgery and delivery.

Glanzmann's thrombasthenia (GT) is an autosomal recessive disorder of platelet function. Conventional management is by platelet transfusion, given before invasive interventions. Alloimmunization resulting in platelet refractoriness and an unpredictable response to platelet infusion have provided particular management difficulties in the past.

Genetic variations observed in arterial and venous thromboembolism--relevance for therapy, risk prevention and prognosis.

We undertook genetic and biochemical assays in patients with arterial (n = 146) and venous (n = 199) thromboembolism and survivors of pulmonary embolism (n = 58) to study causation and gene-life style interactions. In the clinical material from North Western Russia, factor V Leiden was found to be a risk factor in venous thrombosis (OR = 3.6), while the methylenetetrahydrofolate reductase (MTHFR) C677T mutation was a significant variable in both venous (p = 0.

The Ecarin time is an improved confirmatory test for the Taipan snake venom time in warfarinized patients with lupus anticoagulants.

The Taipan snake venom time using dilute phospholipid as a screening test with a platelet neutralization procedure as a confirmatory test has been shown to be a sensitive and specific approach to detection of lupus anticoagulants. Taipan venom is largely insensitive to the effects of ongoing warfarin anticoagulation and this can be useful in detection of lupus anticoagulants in patients receiving this treatment. This study compared the use of the platelet neutralization procedure with the Ecarin time as confirmatory tests for the Taipan snake venom time, the Ecarin venom fraction being insensitive to both lupus anticoagulants and the effects of oral anticoagulants.

A prospective study of recombinant activated factor VII administered by continuous infusion to inhibitor patients undergoing elective major orthopaedic surgery: a pharmacokinetic and efficacy evaluation.

After surgery in haemophilia, haemostasis is difficult to maintain in the presence of an antifactor VIII antibody. This study assessed the pharmacokinetics of recombinant activated factor VII (rFVIIa) and its efficacy in securing post-operative haemostasis in haemophiliacs with inhibitors. Continuous infusion of rFVIIa was evaluated for elective major orthopaedic surgery in nine patients with neutralizing antibodies to FVIII and at high risk of bleeding.

Novel vascular endothelial growth factor binding domains of fibronectin enhance vascular endothelial growth factor biological activity.

Interactions between integrins and growth factor receptors play a critical role in the development and healing of the vasculature. This study mapped two binding domains on fibronectin (FN) that modulate the activity of the angiogenic factor, vascular endothelial growth factor (VEGF). Using solid-phase assays and surface plasmon resonance analysis, we identified two novel VEGF binding domains within the N- and C-terminus of the FN molecule.

The uptake of lipoprotein-borne phylloquinone (vitamin K1) by osteoblasts and osteoblast-like cells: role of heparan sulfate proteoglycans and apolipoprotein E.

Vitamin K is essential for the gamma-carboxylation of Gla-containing bone proteins such as osteocalcin and a suboptimal vitamin K status has been linked to osteoporosis but nothing is known of how the lipoprotein-borne vitamin accesses the bone matrix. We have studied the mechanism of transport of lipoproteins labeled with [3H]-phylloquinone (vitamin K1 [K1]) into osteoblasts using both tumor-derived cell lines and normal osteoblast-rich cell populations. We also investigated the effect of heparin in this model since long-term heparin treatment causes osteopenia and the anticoagulant is known to impair normal lipoprotein metabolism.