Estimation of the Carbohydrate Moiety of von Willebrand Factor in the Plasma of Patients with Subtypes 2a and 2b of von Willebrand Disease

1995 ◽  
Vol 74 (04) ◽  
pp. 1180-1184
Author(s):  
Christophe de Romeuf ◽  
Bruno Samor ◽  
Claudine Mazurier
Keyword(s):  
Sialic Acid ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Colorimetric Assay ◽  
Microtiter Plate ◽  
Von Willebrand Disease ◽  
Carbohydrate Moiety ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryVon Willebrand disease (vWD) results from quantitative (types 1 and 3) or qualitative (type 2) deficiency of von Willebrand factor (vWF). This glycoprotein present in plasma is involved in platelet adhesion at the site of vascular injury and serves as the carrier of antihaemophilic A factor (FVIII). Whereas recent studies have identified mutations in patients suffering from type 2 vWD, the integrity of the carbohydrate moiety of vWF in these patients is still matter of debate. In order to analyse in the plasma milieu the carbohydrate content of plasma vWF from various well-characterized type 2 vWD patients, we developed a colorimetric assay in microtiter plate based on the use of peroxidase- conjugated lectins specific for either α 2-6 sialic acid or β 1-4 galactose. Removal of sialic acid from purified plasma vWF induced significant changes in the reactivity of both lectins. The analysis of various normal plasmas showed no influence of the blood groups and allowed us to compare various vWD patients. The reactivity of lectins for plasma vWFs from two type 2A and six type 2B vWD patients harbouring different mutations was not statistically different from that of a pool of normal plasmas. We conclude that the α 2-6 sialic acid and β 1-4 galactose content of plasma vWF is not altered in these patients affected with types 2A and 2B vWD.

scholarly journals Evidence for the Misfolding of the A1 Domain within Multimeric von Willebrand Factor in Type 2 von Willebrand Disease

2020 ◽  
Vol 432 (2) ◽  
pp. 305-323 ◽  
Author(s):  
Alexander Tischer ◽  
Maria A. Brehm ◽  
Venkata R. Machha ◽  
Laurie Moon-Tasson ◽  
Linda M. Benson ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Von Willebrand Disease ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor

Toward Personalized Treatment for Patients with Low von Willebrand Factor and Quantitative von Willebrand Disease

2021 ◽  
Vol 47 (02) ◽  
pp. 192-200
Author(s):  
James S. O'Donnell
Keyword(s):  
Von Willebrand Factor ◽  
Bleeding Risk ◽  
Von Willebrand Disease ◽  
Personalized Treatment ◽  
Treatment Plans ◽  
Type 3 ◽  
Von Willebrand ◽  
Willebrand Factor

AbstractThe biological mechanisms involved in the pathogenesis of type 2 and type 3 von Willebrand disease (VWD) have been studied extensively. In contrast, although accounting for the majority of VWD cases, the pathobiology underlying partial quantitative VWD has remained somewhat elusive. However, important insights have been attained following several recent cohort studies that have investigated mechanisms in patients with type 1 VWD and low von Willebrand factor (VWF), respectively. These studies have demonstrated that reduced plasma VWF levels may result from either (1) decreased VWF biosynthesis and/or secretion in endothelial cells and (2) pathological increased VWF clearance. In addition, it has become clear that some patients with only mild to moderate reductions in plasma VWF levels in the 30 to 50 IU/dL range may have significant bleeding phenotypes. Importantly in these low VWF patients, bleeding risk fails to correlate with plasma VWF levels and inheritance is typically independent of the VWF gene. Although plasma VWF levels may increase to > 50 IU/dL with progressive aging or pregnancy in these subjects, emerging data suggest that this apparent normalization in VWF levels does not necessarily equate to a complete correction in bleeding phenotype in patients with partial quantitative VWD. In this review, these recent advances in our understanding of quantitative VWD pathogenesis are discussed. Furthermore, the translational implications of these emerging findings are considered, particularly with respect to designing personalized treatment plans for VWD patients undergoing elective procedures.

scholarly journals Platelet von Willebrand factor: evidence for its involvement in platelet adhesion to collagen

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1214-1217
Author(s):  
E Fressinaud ◽  
D Baruch ◽  
C Rothschild ◽  
HR Baumgartner ◽  
D Meyer
Keyword(s):  
Shear Rate ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Von Willebrand Disease ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Von Willebrand ◽  
Willebrand Factor

Although it is well established that plasma von Willebrand Factor (vWF) is essential to platelet adhesion to subendothelium at high shear rates, the role of platelet vWF is less clear. We studied the respective role of both plasma and platelet vWF in mediating platelet adhesion to fibrillar collagen in a parallel-plate perfusion chamber. Reconstituted blood containing RBCs, various mixtures of labeled washed platelets and plasma from controls or five patients with severe von Willebrand disease (vWD), was perfused through the chamber for five minutes at a shear rate of 1,600 s-1. Platelet-collagen interactions were estimated by counting the radioactivity in deposited platelets and by quantitative morphometry. When the perfusate consisted of normal platelets suspended in normal plasma, platelet deposition on the collagen was 24.7 +/- 3.6 X 10(6)/cm2 (mean +/- SEM, n = 6). Significantly less deposition (16 +/- 2.3) was observed when vWD platelets were substituted for normal platelets. In mixtures containing vWD plasma, significantly greater deposition (9 +/- 2.2) was obtained with normal than with vWD platelets (1 +/- 0.4) demonstrating a role for platelet vWF in mediating the deposition of platelets on collagen. Morphometric analysis confirmed these data. Our findings indicate that platelet, as well as plasma, vWF mediates platelet-collagen interactions at a high shear rate.

scholarly journals Adhesive properties of the carbohydrate-modified von Willebrand factor (CHO-vWF)

Blood ◽  
1988 ◽  
Vol 71 (4) ◽  
pp. 947-952 ◽  
Author(s):  
AB Federici ◽  
C De Romeuf ◽  
PG De Groot ◽  
B Samor ◽  
R Lombardi ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Von Willebrand Factor ◽  
Platelet Adhesion ◽  
Platelet Rich Plasma ◽  
Significant Loss ◽  
Total Carbohydrate ◽  
Adhesive Properties ◽  
Normal Platelet ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract In this cooperative study, we explored the role of the carbohydrate moiety (CHO) of von Willebrand factor (vWF) in supporting platelet adhesion. Because of previous discrepant results, all purification steps and CHO modifications by various enzymes were critically evaluated. Under our conditions, CHO-modified vWF preparations contained less than 5% of the initial sialic acid ([Neu]-ase-vWF) and less than 45% ([Neu-Gal]-ase-vWF) or 21% ([Neu-Gal-eF]-ase-vWF) of the D-galactose. These preparations usually showed increased electrophoretic mobility but no significant loss of high-mol-wt multimers when proteolysis had been prevented. Some degree of proteolysis was noted in some carbohydrate-modified vWFs, but the degree of degradation observed did not correlate with the removal of D- galactose. Platelet adhesion to various matrices increased after removal of the terminal sialic acid ([Neu]-ase-vWF) and approximately 45% of the D-galactose ([Neu-Gal]-ase-vWF), but returned to normal values when greater than 70% of the total carbohydrate had been removed by endoglycosidase F [Neu-Gal-ef]-ase-vWF). These changes in reactivity were also reflected in the spontaneous aggregation in normal platelet- rich plasma (PRP) after CHO removal.

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

Molecular Background of “Smeary” von Willebrand Factor Multimers.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2711-2711
Author(s):  
Reinhard Schneppenheim ◽  
Olivier Marggraf ◽  
Heike Eckert ◽  
Tobias Obser ◽  
Florian Oyen ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Disulfide Bonds ◽  
Von Willebrand Disease ◽  
Molecular Testing ◽  
Functional Deficits ◽  
Intermolecular Disulfide Bonds ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Background: Multimer analysis of von Willebrand factor (VWF) is a most important technique to classify patients with von Willebrand disease (VWD) type 2. Besides “classical” multimer patterns a “smeary” appearance of individual VWF oligomers is increasingly observed and has previously been regarded as a pre-analytical artifact. Objective: To phenotypically and genotypically assess the molecular background of “smeary” VWF multimers. Patients and methods: Samples of 8 VWD patients were analyzed in our reference lab (UB) for further classification and molecular testing. Multimer profiles were assessed by intermediate resolution gels. VWF:CB and VWF:GpIb binding were used as functional assays. VWF gene mutation analysis was performed in all index cases (IC). The causal relationship between genotype and phenotype was studied by analyzing recombinant mutants in comparison to wildtype VWF. Results: In all IC the phenotype correlated with particular mutations in the VWF D3 domain (G1172D), the A1 domain (R1315C, R1374S, R1374C, R1399C), the D4 domain (C2257R), the C1 domain (R2464C) and in the region close to the CK domain (C2671Y), respectively. The multimer patterns of recombinant mutant VWF was of a “smeary” appearance and closely resembled those of mutant plasma VWF. Mutations in the A1 domain additionally correlated with severe GpIb binding deficiency. Conclusions: Our data suggest a molecular cause of the “smeary” multimer structure rather than pre-analytical artifacts. Most of the mutations identified involved cysteine residues suggesting an influence on the VWF secondary structure which is determined by intra- and intermolecular disulfide bonds. This could explain the peculiar multimer appearance. The functional deficits, however, seem to depend on the location of the mutations with a significant impact on GpIb binding of mutants in the A1 domain.

scholarly journals Identification of two mutations (Arg611Cys and Arg611His) in the A1 loop of von Willebrand factor (vWF) responsible for type 2 von Willebrand disease with decreased platelet-dependent function of vWF [see comments]

Blood ◽  
1995 ◽  
Vol 86 (3) ◽  
pp. 1010-1018 ◽  
Author(s):  
L Hilbert ◽  
C Gaucher ◽  
C Mazurier
Keyword(s):  
Von Willebrand Factor ◽  
Functional Characterization ◽  
Von Willebrand Disease ◽  
Platelet Glycoprotein ◽  
In Vitro Mutagenesis ◽  
Nucleotide Substitutions ◽  
Dependent Function ◽  
Von Willebrand ◽  
Willebrand Factor

We report the identification of von Willebrand factor (vWF) gene mutations within exon 28 occurring in three unrelated families with an infrequent form of type 2 von Willebrand disease (vWD). A C-->T transition and a G-->A transition, both at the codon for arginine 611 of the mature vWF subunit, were found. They result in either a cysteine or an histidine substitution, respectively. Patients were found to be heterozygous for these substitutions and the vWD was transmitted dominantly. These substitutions have been reproduced by in vitro mutagenesis of full-length cDNA of vWF and transiently expressed in Cos- 7 cells. The corresponding recombinant vWFs (rvWF) exhibited decreased expression and a significant decrease in the high molecular weight multimeric forms. In addition, ristocetin- and botrocetin-induced binding of mutated rvWFs to platelets were markedly decreased as compared with that for the wild-type rvWFs. Thus, the structural and functional characterization of both mutated rvWFs confirmed that the two nucleotide substitutions identified at position 611 of the mature subunit of vWF are real mutations. Although they are located in the A1 loop containing most of the type 2B mutations inducing increased affinity of vWF for platelet glycoprotein Ib, they are responsible for abnormal vWF with decreased platelet-dependent function.

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

2008 ◽  
Vol 100 (09) ◽  
pp. 462-468 ◽  
Author(s):  
Huub H. D. M. van Vliet ◽  
Mies C. Kappers-Klunne ◽  
Jan J. Michiels ◽  
Frank W. G. Leebeek
Keyword(s):  
Von Willebrand Factor ◽  
Von Willebrand Disease ◽  
Response Relationship ◽  
Dose Response Relationship ◽  
Before And After ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryDose-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.

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