A novel flow cytometry single tube bead assay for quantitation of von Willebrand factor antigen and collagen-binding.

Deficiency of or defects in the plasma protein von Willebrand factor (VWF) lead to bleeding and von Willebrand disease (VWD), which may be congenital or acquired. VWD is considered the most common inherited bleeding disorder and laboratory testing for VWF level and activity is critical for appropriate diagnosis and management. We have designed and established a novel Flow Cytometry (FC) based method for measuring VWF antigen (VWF:Ag) and collagen binding (VWF:CB), together in the same tube and at the same time.

Relationship between short activated partial thromboplastin times, thrombin generation, procoagulant factors and procoagulant phospholipid activity.

Short activated partial thromboplastin times (APTTs) are associated with thrombosis. However, what short APTTs actually represent in terms of possible mechanistic pathways is not well characterized. We have assessed thrombin generation as compared with levels of procoagulant factor (fibrinogen, V, VIII, IX, XI and XII) activities, von Willebrand factor level and activity using collagen binding, as well as procoagulant phospholipid activity, in 113 consecutive samples exhibiting a short APTT compared with an equal number of age-matched and sex-matched samples yielding a normal APTT.

Diagnosis and management of von Willebrand disease in Australia.

Von Willebrand disease (VWD) is the most common inherited bleeding disorder and arises from deficiencies and/or defects in the plasma protein Von Willebrand factor (VWF). VWD is classified into six different types, with type 1 identifying a (partial) quantitative deficiency of VWF, type 3 defining a (virtual) total deficiency of VWF, and type 2 identifying four separate types (2A, 2B, 2M, and 2N) characterized by qualitative defects. The classification is based on phenotypic assays including factor VIII coagulant, VWF antigen, and VWF activity, primarily by ristocetin cofactor and collagen binding, as supplemented by additional testing.

Laboratory testing of anticoagulants: the present and the future.

This review provides an update on laboratory testing and monitoring for existing and emerging anticoagulants, starting with an overview of haemostasis and the routine coagulation tests currently employed within most haemostasis laboratories, including the prothrombin time (PT)/international normalised ratio (INR) and the activated partial thromboplastin time (APTT). Current anticoagulant therapy and laboratory monitoring is then discussed in terms of benefits and limitations, followed by a similar brief discussion of the new and emerging anticoagulants. The main focus, however, is laboratory testing related to vitamin K antagonists, heparin, lepirudin and the new agents dabigatran etexilate and rivaroxaban.

A robust method for testing urinary iodine using a microtitre robotic system.

Project: Iodine deficiency disorders are due to inadequate thyroid hormone production and 2 billion individuals worldwide are estimated to have insufficient iodine intake. Laboratory assessment methods include urinary iodine (UI) concentration, blood FT3, FT4, TSH and Thyroglobulin. The aim of this study was to set up a robust method for testing urinary iodine using a microtitre robotic system.

A laboratory evaluation into the short activated partial thromboplastin time.

Although short activated partial thromboplastin times (APTTs) are generally considered to be laboratory artefacts of problematic blood collections, there is mounting evidence that in some cases a short APTT may reflect a hypercoagulable state, potentially associated with increased thrombotic risk and adverse cardiovascular events. We prospectively evaluated the phenomenon of short APTTs in 113 consecutive samples compared with an equal number of age and sex-matched normal APTT samples. We found a significant difference in various test parameters including prothrombin time (PT), Factor (F) V, FVIII, FXI, FXII, von Willebrand factor (VWF) antigen and collagen-binding activity, and in the level of procoagulant phospholipids, as assessed using a novel assay procedure (XACT).

Identification and prevalence of von Willebrand disease type 2N (Normandy) in Australia.

We report an investigation of type 2N von Willebrand disease (VWD), covering the past 7 years and evaluating 1031 plasma samples from over 500 patients. Samples included specific requests for investigation of possible type 2N VWD (including family studies) and samples from 'hemophilia' or nonspecified VWD investigations that could unknowingly be type 2N VWD. In total, 13 new patients with type 2N VWD were identified, four of whom initially presented with normal levels of factor VIII and only three of whom (i.

Potential supplementary utility of combined PFA-100 and functional von Willebrand factor testing for the laboratory assessment of desmopressin and factor concentrate therapy in von Willebrand disease.

We performed a retrospective audit of cross-laboratory testing of desmopressin and factor concentrate therapy to assess the potential utility of supplementary testing using the PFA-100 with functional von Willebrand factor (VWF) activity testing. Data were evaluated for a large number of patients with von Willebrand disease of type 1, type 2A or type 2M, as well as a comparative subset of individuals with haemophilia or carriers of haemophilia. Laboratory testing comprised pre and postdesmopressin, or pre and postconcentrate, evaluation of factor VIII, VWF antigen (VWF:Ag) and VWF ristocetin cofactor activity as traditionally performed, supplemented with collagen-binding (VWF:CB) testing and PFA-100 closure times.

Desmopressin therapy to assist the functional identification and characterisation of von Willebrand disease: differential utility from combining two (VWF:CB and VWF:RCo) von Willebrand factor activity assays?

We performed a retrospective audit of desmopressin (DDAVP) usage to assist in the functional characterisation of von Willebrand disease (VWD). Data was evaluated for 208 patients, comprising those with VWD (Type 1 [n=160], Type 2A [n=19], Type 2M [n=10]), plus 19 individuals with haemophilia or carriers of haemophilia. Laboratory testing comprised pre- and post-DDAVP evaluation of factor VIII (FVIII:C), von Willebrand factor (VWF) antigen (VWF:Ag), VWF ristocetin cofactor (VWF:RCo) activity, VWF collagen binding (VWF:CB) activity, and in one laboratory an alternate VWF activity assay.

A practical approach to instrument selection, evaluation, basic financial management and implementation in pathology and research.

In response to increasingly complex demands in terms of productivity and budgets, there is a critical need to avoid mistakes during instrument selection that will be financially costly, and adversely affect customers, staff, productivity and test turnaround time. As there is no "one size fits all", guidelines must be appropriate to permit informed decision making. A Medline search was conducted to assess background knowledge in this area, using the terms "laboratory instrument selection" and "laboratory instrument evaluation".

The diagnostic dilemma: dual presentations of clinical mucosal bleeding and venous thrombosis associated with the presence of thrombophilia markers and mild reduction in von Willebrand factor.

A prothrombotic and hemorrhagic state can separately manifest in one patient and can potentially cause several diagnostic problems. We report an intriguing case as an example of a potential hemostasis-based diagnostic dilemma. A 29-year-old female patient presented with a personal history of menorrhagia and other mucosal bleeding and renal ovarian thrombosis.

Hemostatic dysfunction associated with endocrine disorders as a major risk factor and cause of human morbidity and mortality: a comprehensive meta-review.

We review the association between disorders of endocrine function and hemostasis. The content of more than 570 review articles were appraised to provide the core of 81 key articles referenced in this chapter. The search method used MEDLINE and EMBASE electronic databases and the key words e NDOCRINE DYSFUNCTION, DIABETES, GRAVES' DISEASE, HYPOTHYROIDISM, HYPERTHYROIDISM, THYROTOXICOSIS, VON WILLEBRAND DISEASE, VON WILLEBRAND FACTOR, BLEEDING DISORDERS, PLATELETS DYSFUNCTION, HEMOSTASIS DYSFUNCTION, and REVIEW.

A short history of diagnostic tests for von Willebrand disease: in memory of Barry Firkin (1930 to 2001) and Ted Zimmerman (1937 to 1988).

By the end of the 1960s, von Willebrand disease (vWD) was accepted as a combined deficiency of factor (F) VIII coagulation and a plasma factor responsible for normal platelet adhesion. Just how these two functions related to each other was unclear, and the diagnostic tests available at the time were poorly reproducible, cumbersome, and unreliable. As a consequence, the condition was poorly delineated from other coagulation and platelet disorders.

A randomized trial of high-versus conventional-dose cytarabine in consolidation chemotherapy for adult de novo acute myeloid leukemia in first remission after induction therapy containing high-dose cytarabine.

The value of administering sequential courses of chemotherapy containing high-dose cytarabine in both induction and consolidation therapy for acute myeloid leukemia (AML) has not been assessed in a prospective randomized trial. Two hundred ninety-two AML patients aged 15 to 60 years were enrolled in the Australasian Leukaemia and Lymphoma Group (ALLG) AML trial number 7 (M7) protocol to evaluate this question. All received induction therapy with the ICE protocol (idarubicin 9 mg/m2 x 3; cytarabine 3 g/m2 twice a day on days 1, 3, 5, 7; etoposide 75 mg/m2 x 7).