Multicenter Comparison of von Willebrand Factor Multimer Sizing Techniques

1985 ◽  
Vol 54 (04) ◽  
pp. 873-876 ◽  
Author(s):  
P M Mannucci ◽  
C F Abildgaard ◽  
H R Gralnick ◽  
F G H Hill ◽  
L W Hoyer ◽  
...  
Keyword(s):  
Differential Diagnosis ◽  
Von Willebrand Factor ◽  
Healthy Subjects ◽  
Type I ◽  
Type Ii ◽  
Plasma Samples ◽  
Low Resolution ◽  
Electrophoretic Techniques ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryA multicenter study of various types of von Willebrand’s disease (vWD) was conducted in order to compare the different electrophoretic techniques used to evaluate von Willebrand factor multimers in plasma. Seven laboratories participated in the blind study of eight plasma samples from two healthy subjects and six vWD types and subtypes (la, lb, IIA, IIB, IIC and IID). From the results of the multimeric analysis of these samples, it appears that the differential diagnosis of vWD types and subtypes should be first approached by using a low-resolution electrophoretic technique, where each vWF multimer appears as a single band. Low-resolution techniques differentiate type I from type II, subtype la from lb and also subtype IIA from other type II subtypes. When type II subtypes other than IIA are identified with these techniques, samples should be rerun using high resolution techniques that resolve each of the fastest migrating multimers in at least three subbands, and permit the differentiation of subtypes IIB, IIC and IID.

DIABETICS DEMONSTRATE A BLUNTED VON WILLEBRAND FACTOR RESPONSE TO DESMOPRESSIN INFUSION

1987 ◽  
Author(s):  
M B Grant ◽  
T Daniels ◽  
D Claire ◽  
R Lottenberg
Keyword(s):  
Von Willebrand Factor ◽  
Microvascular Complications ◽  
Feedback Mechanism ◽  
Proliferative Retinopathy ◽  
Type I ◽  
Type Ii ◽  
Negative Feedback Mechanism ◽  
Background Retinopathy ◽  
Von Willebrand ◽  
Willebrand Factor

The increase in von Willebrand factor (vWF) following desmopressin (DDAVP) (1-desamino-8-D-arginine vasopressin) infusion was markedly blunted in severe hemophiliacs who had high vWF levels after treatment with vWF rich plasma concentrates. Diabetics with microangiopathy appear to have disease-induced elevation of vWF. In the current study, the vWF response to DDAVP infusion was measured in 30 diabetics (12 type I, 18 type II) and 16 controls, matched for age, sex and weight. Extent of nephropathy, macroangiopathy, and neuropathy was evaluated. Diabetic retinopathy was assessed by indirect ophthalmoscopy and fluorescein angiography (n=8 proliferative retinopathy, n=6 background retinopathy, n=16 no retinopathy). Plasma samples were collected in the supine, overnight-fasted state. DDAVP (0.3 μg/kg) was infused over 30 min and samples obtained at 0-60 min. vWF antigen was assayed by Laurell rocket electrophoresis. Tissue plasminogen activator (t-PA) activity was measured by a coupled chromogenic substrate assay. Results; Basal vWF levels for type I diabetics (124±16%, MeantSEM) and type II (178±14%) were increased as compared to controls (94±6%), p<.05 and p<.005, respectively. vWF levels for diabetics with proliferative retinopathy (194±29%) were significantly higher than for diabetics with background retinopathy (106±13%) p<.01. Diabetics with elevated basal levels of vWF (>150%) showed less of an increase in vWF following DDAVP infusion than diabetics with normal basal levels (p<.01). The percent increase in vWF following DDAVP administration inversely correlated with basal vWF levels (type I, r=.51; p<.01 and type II, r=.46; p<.01). The basal vWF level was the significant determinant of DDAVP response, not the presence or absence of diabetic complications. Peak t-PA levels showed no difference in controls or diabetics. In contrast to the vWF response, a normal t-PA response to DDAVP infusion was observed in diabetics. Conclusion: Diabetics with microvascular complications and high circulating levels of vWF demonstrate a blunted vWF response to DDAVP. This supports the existence of a negative feedback mechanism as previously reported for the transfused hemophiliacs.

ADAMTS-13 Activity and Antigen in Commercial Von Willebrand Factor Concentrates.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4027-4027
Author(s):  
Inge Scharrer ◽  
Martina Böhm
Keyword(s):  
Von Willebrand Factor ◽  
Peptide Bond ◽  
Type I ◽  
Plasma Samples ◽  
Normal Plasma ◽  
Hemostatic Activity ◽  
Cofactor Activity ◽  
A Disintegrin And Metalloproteinase ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract The plasma metalloprotease ADAMTS-13 (a disintegrin and metalloproteinase with thrombospondin type I motif - 13) cleaves the Von Willebrand factor (VWF) at the peptide bond Tyr1605-Met1606 and thereby controls the hemostatic activity of the VWF. We tested three commercial VWF concentrates with respect to their ADAMTS-13 activity and antigen contents. ADAMTS-13 activity in the VWF concentrates was tested by measuring the capacity of the concentrates for auto-proteolysis both in the presence and in the absence of neutralising ADAMTS-13 auto-antibodies. To achieve this, the concentrates were reconstituted to a final VWF concentration of 100 I.E. U VWF:Ristocetin Cofactor activity (VWF:RCo). The VWF solutions were diluted with 5 mol/l urea and then incubated for 14–16h at 37°C in low ionic TRIS buffer containing BaCl2 and different plasma samples or Imidazole buffer as plasma replacement.The residual VWF:RCo was subsequently measured using the BC von Willebrand Reagent from Dade Behring (Marburg, Germany). The residual VWF:RCo in the presence of plasma from a patient with acquired TTP (ADAMTS-13 activity: &lt;6.25% due to high levels of neutralising ADAMTS-13 auto-antibodies) was then compared to the residual VWF:RCo in the mixtures containing normal plasma, Imidazole buffer or plasma from a patient with congenital TTP (ADAMTS-13 activity: &lt;6.25% due to mutations in the ADAMTS-13 gene). ADAMTS-13 antigen was measured by a commercial ADAMTS-13 ELISA from American Diagnostica (Stamfort, USA). Residual VWF:RCo after proteolysis of VWF concentrates in the presence of Normal plasma, Imidazole buffer and plasma from patients with congenital and acquired TTP, respectively VWF concentrate Normal plasma Imidazole buffer Congenital TTP Acquired TTP A 7% 106% 111% 138% B 10% 11% 16% 104% C 10% 32% 36% 63% ADAMTS-13-Antigen in VWF concentrates given as ng ADAMTS-13 Antigen per I.E. Units VWF:RCo VWF concentrate ADAMTS-13 Antigen [ng/I.E. U VWF:RCo] A not detectable B 6.7 C 0.8 The loss in VWF:RCo in the samples containing either Imidazole buffer or congenital TTP plasma compared to the loss in the samples containing acquired TTP plasma hints at auto-proteolysis due to specific action of ADAMTS-13. All concentrates seem to contain some ADAMTS-13 activity, but ADAMTS-13 activity in the solutions of 100 I.E. U/ml VWF:RCo used here is always lower than the activity in normal plasma (which contain per definition 1U/ml ADAMTS-13 activity). The ratio of ADAMTS-13 activity/VWF:RCo is thus always lower than 1:100 in all the investigated concentrates. However, concentrate B seems to show the highest ADAMTS-13 activity as well as the largest amount of ADAMTS-13 antigen. Concentrate B is followed by concentrate C. Concentrate A only shows traces of ADAMTS-13 activity and non detectable levels of ADAMTS-13 antigen. The results demonstrate that concentrates B and C should not be used as VWF substrates in ADAMTS-13 activity assays. The ADAMTS-13 content in the various VWF concentrates may influence stability, recovery and half-lives of the concentrates.

Interventional Thermal Injury of the Arterial Wall: Unfolding of von Willebrand Factor and Its Increased Binding to Collagen after 55° C Heating

1996 ◽  
Vol 75 (03) ◽  
pp. 515-519 ◽  
Author(s):  
Mark J Post ◽  
Anke N de Graaf-Bos ◽  
George Posthuma ◽  
Philip G de Groot ◽  
Jan J Sixma ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Conformational Changes ◽  
Arterial Wall ◽  
Platelet Adhesion ◽  
Type I ◽  
Temperature Dependent ◽  
Collagen Types ◽  
Electron Microscopic ◽  
Von Willebrand ◽  
Willebrand Factor

Summary Purpose. Thermal angioplasty alters the thrombogenicity of the arterial wall. In previous studies, platelet adhesion was found to increase after heating human subendothelium to 55° C and decrease after heating to 90° C. In the present electron microscopic study, the mechanism of this temperature-dependent platelet adhesion to the heated arterial wall is elucidated by investigating temperature-dependent conformational changes of von Willebrand factor (vWF) and collagen types I and III and the binding of vWF to heated collagen. Methods. Purified vWF and/or collagen was applied to electron microscopic grids and heated by floating on a salt-solution of 37° C, 55° C or 90° C for 15 s. After incubation with a polyclonal antibody against vWF and incubation with protein A/gold, the grids were examined by electron microscopy. Results. At 37° C, vWF was coiled. At 55° C, vWF unfolded, whereas heating at 90° C caused a reduction in antigenicity. Collagen fibers heated to 37° C were 60.3 ± 3.1 nm wide. Heating to 55° C resulted in the unwinding of the fibers, increasing the width to 87.5 ± 8.2 nm (p < 0.01). Heating to 90° C resulted in denatured fibers with an enlarged width of 85.1 ± 6.1 nm (p < 0.05). Heating of collagen to 55° C resulted in an increased vWF binding as compared to collagen heated to 37° C or to 90° C. Incubation of collagen with vWF, prior to heating, resulted in a vWF binding after heating to 55° C that was similar to the 37° C binding and a decreased binding after 90° C. Conclusions. After 55° C heating, the von Willebrand factor molecule unfolds and collagen types I and III exhibit an increased adhesiveness for von Willebrand factor. Heating to 90° C denatures von Willebrand factor and collagen. The conformation changes of von Willebrand factor and its altered binding to collagen type I and III may explain the increased and decreased platelet adhesion to subendothelium after 55° C and 90° C heating, respectively.

The Genetic Defect of Type I von Willebrand Disease “Vicenza” Is Linked to the von Willebrand Factor Gene

1993 ◽  
Vol 69 (02) ◽  
pp. 173-176 ◽  
Author(s):  
Anna M Randi ◽  
Elisabetta Sacchi ◽  
Gian Carlo Castaman ◽  
Francesco Rodeghiero ◽  
Pier Mannuccio Mannucci
Keyword(s):  
Von Willebrand Factor ◽  
Autosomal Dominant ◽  
Genetic Defect ◽  
Von Willebrand Disease ◽  
Type I ◽  
Bleeding Tendency ◽  
Factor Gene ◽  
Low Levels ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryType I von Willebrand disease (vWD) Vicenza is a rare variant with autosomal dominant transmission, characterized by the presence of supranormal von Willebrand factor (vWF) multimers in plasma, similar to those normally found in endothelial cells and megakaryocytes. The patients have very low levels of plasma vWF contrasting with a mild bleeding tendency. The pathophysiology of this subtype is still unknown. The presence of supranormal multimers in the patients’ plasma could be due to a mutation in the vWF molecule which affects post-translational processing, or to a defect in the cells’ processing machinery, independent of the vWF molecule. In order to determne if type I vWD Vicenza is linked to the vWF gene, we studied six polymorphic systems identified within the vWF gene in two apparently unrelated families with type I vWD Vicenza. The results of this study indicate a linkage between vWF gene and the type I vWD Vicenza trait. This strongly suggests that type I vWD Vicenza is due to a mutation in one of the vWF alleles, which results in an abnormal vWF molecule that is processed to a lesser extent than normal vWF.

PRIMARY BINDING SITE OF VON WILLEBRAND FACTOR IN THE SUBENDOTHELIUM WHICH MEDIATES PLATELET ADHESION IS NOT COLLAGEN

1987 ◽  
Author(s):  
Philip G de Groot ◽  
Jan A van Mourik ◽  
Jan J Sixma
Keyword(s):  
Monoclonal Antibody ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Collagen Type ◽  
Collagen Type I ◽  
Extracellular Matrices ◽  
Type I ◽  
Type Iii ◽  
Von Willebrand ◽  
Willebrand Factor

We have studies the binding of von Willebrand factor (vWF) to extracellular matrices of endothelial cells and smooth muscle cells and to the vessel wall of human umbilical arteries in relation to its function in supporting platelet adhesion at high shear rates. CLB-RAg 38, a monoclonal antibody directed against vWF inhibits the binding of 125I-vWF extracellular matrices completely. The binding of 125I-vWF to subendothelium is not inhibited, because there are many different binding sites. CLB-RAg 38 inhibits platelet adhesion to extracellular matrices and subendothelium, in sofar as it is dependent on plasma vWF. CLB-RAg 38 has no effect on adhesion depending on vWF already bound to the matrix or subendothelium. CLB-RAg 38 does not inhibit binding of vWF to collagen type I and type III. Another monoclonal antibody against vWF, CLB-RAg 201, completely inhibits binding of vWF to collagen type I and type III. CLB-RAg 201 does not inhibit binding of 125I-vWF ot the extracellular matrices. CLB-RAg 201 partly inhibits platelet adhesion but this inhibition is also present when the adhesion depends on vWF already present in matrix or subendothelium, indicating that CLB-RAg 201 also inhibits the adhesion of platelets directly, this in contrast to CLB-RAg 38. The epitopes for CLB-RAg 201 and 38 were found on different tryptic fragments of vWF. These data indicate that vWF binds to subendothelium and to matrices of cultured cells by mechanism that is different from binding to collagen.

The role of platelet von Willebrand factor in platelet adhesion and thrombus formation: a study of 34 patients with various subtypes of type I von Willebrand disease

1994 ◽  
Vol 86 (2) ◽  
pp. 327-332 ◽  
Author(s):  
Edith Fressinaud ◽  
Augusto B. Federici ◽  
Giancarlo Castaman ◽  
Chantal Rothschild ◽  
Francesco Rodeghiero ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Von Willebrand Disease ◽  
Type I ◽  
Von Willebrand ◽  
Willebrand Factor

scholarly journals Multimeric composition of factor VIII/von Willebrand factor following administration of DDAVP: implications for pathophysiology and therapy of von Willebrand's disease subtypes

Blood ◽  
1982 ◽  
Vol 59 (6) ◽  
pp. 1272-1278 ◽  
Author(s):  
ZM Ruggeri ◽  
PM Mannucci ◽  
R Lombardi ◽  
AB Federici ◽  
TS Zimmerman
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Resting State ◽  
Bleeding Time ◽  
Type I ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Plasma Factor ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract We have studied the modifications in the multimeric composition of plasma factor VIII/von Willebrand factor and the bleeding time response following administration of 1-Deamino-[8-D-arginine]-Vasopressin (DDAVP) to patients with different subtypes of von Willebrand's disease. In type I, all multimers were present in plasma in the resting state, though they were decreased in concentration. Administration of DDAVP resulted in an increased concentration of these forms as well as the appearance of larger forms than were previously present. There was concomitant correction of the bleeding time. In type IIA, large multimers were absent in the resting state, and although DDAVP induced an average threefold increase in the plasma concentration of factor VIII/von Willebrand factor, the larger multimers did not appear and the bleeding time, although shortened, was not corrected. In contrast, the larger multimers that were also absent from type IIB plasma in the resting state rapidly appeared following DDAVP administration. However, their appearance was transitory and the bleeding time, as in IIA patients, was shortened but not corrected. The characteristic multimeric composition of platelet factor VIII/von Willebrand factor in given subtypes predicted the alteration in plasma factor VIII/von Willebrand factor induced by DDAVP. These studies provide evidence that the different subtypes of von Willebrand's disease represent distinct abnormalities of factor VIII/von Willebrand factor. They also suggest that complete hemostatic correction following DDAVP can be routinely expected only in type I von Willebrand's disease, and only if factor VIII/von Willebrand factor can be raised to normal levels.

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