Vliet, H.H.D.M. van

Laboratory diagnosis and molecular basis of mild von willebrand disease type 1 (Article)

2009-06-01T00:00:00Z

Mild type 1 von Willebrand disease (VWD) is characterized by low to variable penetrance of bleeding, a high (increased) prevalence of blood group O, von Willebrand factor (VWF) values around and above 30% with normal ratios of VWF:ristocetin cofactor activity (RCo)/VWF:antigen (Ag), VWF:collagen binding (CB)/VWF:Ag and factor VIII (FVIII):coagulant activity (C)/VWF:Ag. Within this group of patients, the combination of the C1584 mutation and blood group O is rather frequent. Patients with mild VWD type 1 present good/normal responses of FVIII:C and VWF parameters to desmopressin (DDAVP). With the exclusion of dominant VWD type Vicenza, type 1/2E, recessive 2N and dominant 2M, missense mutations in patients with mild VWD type 1 with normal multimers are mainly located in the regulatory sequence region, the D1/D2 propeptide region, the D′ VWF-FVIII binding site region and the D4, B1-B3 and C1-C2 domains but rarely in the D3, A1 or A2 domain. A new category of either dominant or recessive mild VWD type 1 due to mutations in the D4, B1-B3 and C1-C2 domains of the VWF gene consists of two groups: one group with mild VWD with normal VWF multimers and a second group with mild/moderate VWD with smeary multimer pattern.

Dominant von willebrand disease type 2A groups i and ii due to missense mutations in the A2 domain of the von willebrand factor gene: Diagnosis and management (Article)

2009-06-01T00:00:00Z

Pertinent findings in patients with von Willebrand disease (VWD) type 2A include prolonged bleeding time (BT), consistently low von Willebrand factor (VWF):ristocetin cofactor activity (RCo)/antigen concentration (Ag) and VWF:collagen binding (CB)/Ag ratios, absence of high, and (depending on severity) intermediate and large VWF multimers, the presence of pronounced triplet structure of individual bands and increased VWF degradation products due to increased proteolysis caused by mutations in the A2 domain of VWF. Two categories of VWD type 2A can be distinguished: group I with severe and group II with mild VWD. A minority of VWD type 2A have mild VWD characterized by near normal to prolonged BT, normal factor VIII coagulant activity and VWF:Ag, low VWF:RCo and VWF:CB, a normal ristocetin-induced platelet aggregation and complete but transient correction of BT and functional VWF parameters to normal levels for only a few hours due to short half-lives for VWF:RCo and CWF:CB. Such transient complete responses to desmopressin (DDAVP) lasting only a few hours may facilitate treatment and prophylaxis of minor bleedings, but may not be able to prevent bleeding during minor and major surgery. Most VWD type 2A patients have pronounced VWD with very low VWF:RCo, prolonged BT, PFA-100 closure times >250 s, and response to DDAVP is only transient, minor, poor or absent, with no correction of the BT despite some increase in VWF:RCo, thus being candidates for factor VIII-VWF concentrate substitution for the acute and prophylactic treatment of bleeding symptoms.

Managing patients with von willebrand disease type 1, 2 and 3 with desmopressin and von willebrand factor-factor VIII concentrate in surgical settings (Article)

2009-06-01T00:00:00Z

Guidelines and recommendations for the acute and prophylactic treatment of bleeding in von Willebrand disease (VWD) patients with von Willebrand factor (VWF)/factor VIII (FVIII) concentrates should be based on the analysis of the content of VWF/FVIII concentrates and on pharmacokinetic studies in patients with different severity of VWD (type 1, type 2 or type 3). The VW/FVIII concentrates should be assessed using the parameters FVIII:coagulant activity (C), VWF:ristocetin cofactor activity (RCo), VWF:collagen binding and VWF multimeric patterns for the presence of large multimers to determine their predicted efficacy and safety in prospective management studies. As the bleeding tendency is moderate in VWD type 2 and severe in type 3 and because the FVIII:C levels are subnormal in type 2 but very low in type 3 VWD patients, new guidelines using VWF:RCo unit dosing for the acute and prophylactic treatment of bleeding episodes are proposed. Such guidelines should be stratified for the severity of bleeding, the type of surgery (minor or major) and also for the bleeding score in either VWD type 1, 2 or 3.

ADAMTS-13 and Von Willebrand factor in relation to platelet response during plasma exchange in thrombotic thrombocytopenic purpura: A clue for disease mechanism? (Article)

2009-02-12T00:00:00Z

PFA-100 monitoring of von Willebrand factor (VWF) responses to desmopressin (DDAVP) and factor VIII/VWF concentrate substitution in von Willebrand disease type 1 and 2 (Article)

2008-09-01T00:00:00Z

Dose-response relationship was studied between PFA-100 closure times (PFA CTs) and factor (F)VIII-von Willebrand factor (VWF) parameters in patients with von Willebrand disease (VWD) type 1 and type 2 before and after treatment with DDAVP (n=84) or FVIII/VWF concentrate (n=38). DDAVP treatment of patients with VWD type 1 normalised the PFA CTs by increasing VWF levels to normal. Of the 14 patients with VWD type 2, PFA CTs did not normalize in eight. Haemate-P substitution in patients with VWD type 1 induced a less favourable response as compared to DDAVP, because PFA CTs did not correct in all patients. Of 12 patients with VWD type 2 treated with Haemate-P, six showed a correction of PFA CTs (<250 sec), which correlated with the normalisation of the VWF CB/Ag ratio. In-vitro studies were performed by using whole blood of patients with VWD and adding various amounts of FVIII/VWF concentrate. Addition of Haemate-P induced an increase of the VWF CB/Ag ratio from 0.30 to 0.70 in blood of patients with VWD type 2 with correction of the PFA CTs. Immunate did not result in an increase of VWF CB/Ag ratio in blood of VWD type 2 patients, and the PFA CTs remained prolonged. We conclude that PFA-100 might be an adequate instrument not only for diagnosis but also for monitoring of DDAVP responses and FVIII/VWF substitution of patients with VWD type 1 and 2, but this is dependent upon the type of VWD and the concentrate used.

Evaluation of the AutoDimer D-dimer assay for the exclusion of pulmonary embolism [3] (Article)

2007-02-01T00:00:00Z

Intravenous DDAVP and factor VIII-von Willebrand factor concentrate for the treatment and prophylaxis of bleedings in patients with von Willebrand disease type 1, 2 and 3 (Article)

2007-01-01T00:00:00Z

The current standard set of von Willebrand factor (VWF) parameters used to differentiate type 1 from type 2 VWD include bleeding times (BTs), factor VIII coagulant activity (FVIII:C), VWF antigen (VWF:Ag), VWF ristocetine cofactor activity (VWF:RCo), VWF collagen binding activity (VWF:CB), ristocetine induced platelet aggregation (RIPA), and analysis of VWF multimers in low and high resolution agarose gels and the response to DDAVP. The BTs and RIPA are normal in asymptomatic carriers of a mutant VWF allele, in dominant type 1, and in recessive type 2N VWD, and this category has a normal response of VWF parameters to DDAVP. The response of FVIII:C is compromised in type 2N VWD. The BTs and RIPA are usually normal in type Vicenza and mild type 2A VWD, and these two VWD variants show a transiently good response of BT and VWF parameters followed by short in vivo half life times of VWF parameters. The BTS are strongly prolonged and RIPA typically absent in recessive severe type 1 and 3 VWD, in dominant type 2A and in recessive type 2C (very likely also 2D) VWD and consequently associated with low or absent platelet VWF, and no or poor response of VWF parameters to DDAVP. The BTs are prolonged and RIPA increased in dominant type 2B VWD, that is featured by normal platelet VWF and a poor response of BT and functional VWF to DDAVP. The BTs are prolonged and RIPA decreased in dominant type 2A and 2U, that all have low VWF platelet, very low VWF:RCo values as compared to VWF:Ag, and a poor response of functional VWF to DDAVP. VWD type 2M is featured by the presence of all VWF multimers in a low resolution agarose gel, normal or slightly prolonged BT, decreased RIPA, a poor response of VWF:RCo and a good response of FVIII and VWF:CB to DDAVP and therefore clearly in between dominant type 1 and 2U. The existing recommendations for prophylaxis and treatment of bleedings in type 2 VWD patients with FVIII/VWF concentrates are mainly derived from pharmocokinetic studies in type 3 VWD patients. FVIII/VWF concentrates should be characterised by labelling with FVIII:C, VWF:RCo, VWF:CB and VWF multimeric pattern to determine their safety and efficacy in prospective management studies. As the bleeding tendency is moderate in type 2 and severe in type 3 VWD and the FVIII:C levels are near normal in type 2 and very low in type 3 VWD patients. Proper recommendations of FVIII/VWF concentrates using VWF:RCo unit dosing for the prophylaxis and treatment of bleeding episodes are proposed and has to be stratified for the severity of bleeding, the type of surgery either minor or major and for type 2 and type 3 VWD as well.

Fibrinolysis during liver transplantation is enhanced by using solvent/detergent virus-inactivated plasma (ESDEP) (Article)

2002-01-01T00:00:00Z

After the introduction of solvent/detergent-treated plasma (ESDEP) in our hospital, an increased incidence of hyperfibrinolysis was observed (75% vs 29%; P = 0.005) compared with the use of fresh frozen plasma for liver transplantation. To clarify this increased incidence, intraoperative plasma samples of patients treated with fresh frozen plasma or ESDEP were analyzed in a retrospective observational study. During the anhepatic phase, plasma levels of D-dimer (6.58 vs 1.53 microg/mL; P = 0.02) and fibrinogen degradation products (60 vs 23 mg/L; P = 0.018) were significantly higher in patients treated with ESDEP. After reperfusion, differences increased to 23.5 vs 4.7 microg/mL (D-dimer, P = 0.002) and 161 vs 57 mg/L (fibrinogen degradation products, P = 0.001). The amount of plasma received per packed red blood cell concentrate, clotting tests, and levels of individual clotting factors did not show significant differences between the groups. alpha(2)-Antiplasmin levels, however, were significantly lower in patients receiving ESDEP during the anhepatic phase (0.37 vs 0.65 IU/mL; P < 0.001) and after reperfusion (0.27 vs 0.58 IU/mL; P = 0.001). Analysis of alpha(2)-antiplasmin levels in ESDEP alone showed a reduction to 0.28 IU/mL (normal >0.95 IU/mL) because of the solvent/detergent process. Therapeutic consequences for the use of ESDEP in orthotopic liver transplantation are discussed in view of an increased incidence of hyperfibrinolysis caused by reduced levels of alpha(2)-antiplasmin in the solvent/detergent-treated plasma. IMPLICATIONS: The use of solvent/detergent virus-inactivated plasma is of increasing importance in the prevention of human immunodeficiency virus and hepatitis C virus transmission. Since the use of this plasma during orthotopic liver transplantation has increased, the incidence of hyperfibrinolysis was observed. Clotting analysis of the patients revealed small alpha(2)-antiplasmin concentrations because of the solvent/detergent process.

Acute effect of cigarette smoking on cardiac prostaglandin synthesis and platelet behavior in patients with coronary heart disease (In Book)

1983-01-01T00:00:00Z