Ristocetin–Willebrand factor activity in dog plasma

1980 ◽  
Vol 58 (9) ◽  
pp. 1128-1134 ◽  
Author(s):  
I. B. Johnstone ◽  
F. Lotz
Keyword(s):  
Initial Velocity ◽  
Hemophilia A ◽  
Severe Hemophilia ◽  
Factor Activity ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Dog Plasma ◽  
Reproducible Method ◽  
Canine Plasma ◽  
Willebrand Factor

A sensitive and reproducible method for the quantitation of ristocetin–Willebrand factor activity in canine plasma is described. This assay measures the initial velocity of aggregation of suspensions of canine washed platelets in the presence of ristocetin and ristocetin–Willebrand factor. The washed platelets are stable for 4 h and when prepared from the same donor vary little in their day-to-day response to ristocetin.The calculated mean plasma ristocetin–Willebrand factor activity in 37 normal dogs using this method is 98 ± 26% (mean ± SD). Ristocetin–Willebrand activity is 106 ± 25% in dogs with severe hemophilia A and 45 ± 13% in dogs with moderate forms of von Willebrand's disease.

Current Knowledge of the AHF-Like Antigen

1975 ◽  
Author(s):  
Dominique Meyer
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Hemophilia A ◽  
Factor Activity ◽  
Factor Viii Activity ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Von Willebrand ◽  
Willebrand Factor

Factor VIII and von Willebrand Factor activities are associated with a high molecular weight protein which can be isolated from plasma and may be studied by immunological methods. Homologous antibodies to Factor VIII are directed towards the active site of the Factor VIII molecule; they do not neutralize Willebrand Factor activity and do not precipitate with normal plasma. The use of such antibodies has allowed the distinction between Hemophilia A+ and A-. Specific precipitation of Factor VIII antibodies using polyethylene glycol will be reported, allowing typing of heavy and light chains of purified antibodies. Heterologous antisera prepared in rabbits against purified human Factor VIII complex neutralize Factor VIII and von Willebrand Factor activities and precipitate with AHF-like antigen. Estimation of this antigen in plasma has allowed (1) the differenciation of the molecular abnormalities in Hemophilia A and classical von Willebrand’s disease; (2) the comparison between normal and Hemophilic AHF-like antigen; (3) the detection of carriers of Hemophilia A; (4) the study of variants of von Willebrand’s disease; (5) the demonstration of this antigen in platelets and in endothelial cells. Factor VIII activity and AHF-like antigen are probably separate entities, circulating as a complex in normal plasma, as suggested by the following experiments: transfusion studies in von Willebrand’s disease; immuno-adsorption studies; comparison of Factor VIII complex in cryoprecipitate and supernatant; and dissociation in high salt buffer, demonstrating that Factor VIII includes two biologically linked but distinct fragments, of high (HMW) and low (LMW) molecular weight. The non functional HMW subunit, controlled by an autosomal locus, is identified by the presence of AHF-like antigen and Willebrand Factor activity. The LMW subunit, product of an X-chromosome locus, does not contain AHF-like antigen, but it carries Factor VIII activity, as demonstrated by the following facts: inactivation by both human and rabbit antibodies to Factor VIII; transient activation by thrombin; obtention of antisera which specifically inactivate Factor VIII.

WILLEBRAND-FACTOR ACTIVITY AND ANTIGEN IN VON WILLEBRAND'S DISEASE

The Lancet ◽  
1974 ◽  
Vol 303 (7856) ◽  
pp. 512-513 ◽  
Author(s):  
Dominique Meyer ◽  
C.S.P. Jenkins ◽  
Marie Dreyfus ◽  
Marie-José Larrieu
Keyword(s):  
Factor Activity ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Willebrand Factor

scholarly journals Factor VIII coagulant antigen in hemophilic plasma: a comparison of five alloantibodies

Blood ◽  
1980 ◽  
Vol 56 (4) ◽  
pp. 615-619 ◽  
Author(s):  
HM Reisner ◽  
WA Price ◽  
PM Blatt ◽  
ES Barrow ◽  
JB Graham
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
In Utero ◽  
Severe Hemophilia ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Very High

Abstract Five independent alloantibodies directed to factor VIII coagulant antigen (VIII:CAg) were assessed against normal, von Willebrand's disease, and severe hemophilia A plasmas. Immunoradiometric assays (IRMAs) were developed for each antibody, one of which had arisen “spontaneously” and four in transfused hemophiliacs. The correlations between assays were very high for normal, vWd, and both CRM+ and CRM- hemophiliacs. This suggests that IRMAs maybe developed from almost any reasonably high titered alloantibody and used with confidence in diagnosing CRM- hemophilia A in utero by fetoscopy.

scholarly journals Reduced Polymerization of Willebrand Factor in a Family of Pigs with a Variant of von Willebrand’s Disease

1977 ◽  
Author(s):  
D. N. Fass ◽  
E. J. W. Bowie
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Sodium Dodecyl ◽  
Factor Activity ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Severe Reduction ◽  
Genetically Determined ◽  
Willebrand Factor ◽  
Very High

Sodium dodecyl sulfate electrophoresis on 2% agarose allows the separation of porcine Willebrand factor into multiple macromolecular complexes from 1.5 million to 21 million, molecular weight. In non-denaturing buffers these forms are resistant to alteration by 10-4M mercaptoethanol, reduced glutathione, or cysteine. At sulfhydryl concentrations of 10-4M both dithiothreitol (DTT) and dithioerythritol (DTE) seem to catalyze disulfide interchange evidence by the appearance of very high molecular weight polymers. Both DTT and DTE in the absence of detergent or other denaturants lowered the average complex size at sulfhydryl concentration of 10-3M. Concomitant with the reduction in average polymer size there was a loss of ristocetin-Willebrand factor activity. A severe reduction of average molecular weight was found to be a characteristic of the Willebrand factor found in a genetically determined variant of the porcine model of von Willebrand’s disease. These observations provide a molecular basis for a qualitative version of the porcine disease in contrast to all previously described affected pigs which suffer a quantitative defieiency of Willebrand factor activity and antigen.

scholarly journals Factor VIII coagulant antigen in hemophilic plasma: a comparison of five alloantibodies

Blood ◽  
1980 ◽  
Vol 56 (4) ◽  
pp. 615-619
Author(s):  
HM Reisner ◽  
WA Price ◽  
PM Blatt ◽  
ES Barrow ◽  
JB Graham
Keyword(s):  
Factor Viii ◽  
Hemophilia A ◽  
In Utero ◽  
Severe Hemophilia ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Very High

Five independent alloantibodies directed to factor VIII coagulant antigen (VIII:CAg) were assessed against normal, von Willebrand's disease, and severe hemophilia A plasmas. Immunoradiometric assays (IRMAs) were developed for each antibody, one of which had arisen “spontaneously” and four in transfused hemophiliacs. The correlations between assays were very high for normal, vWd, and both CRM+ and CRM- hemophiliacs. This suggests that IRMAs maybe developed from almost any reasonably high titered alloantibody and used with confidence in diagnosing CRM- hemophilia A in utero by fetoscopy.

Further Studies on Aggregation of Platelet-Type von Willebrand’s Disease Platelets by Human von Willebrand Factor

1986 ◽  
Vol 55 (03) ◽  
pp. 338-341 ◽  
Author(s):  
H Takahashi ◽  
W Tatewaki ◽  
M Hanano ◽  
R Nagayama ◽  
A Shibata
Keyword(s):  
Von Willebrand Factor ◽  
Ricinus Communis ◽  
Divalent Cations ◽  
Peanut Agglutinin ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Ricinus Communis Agglutinin ◽  
Von Willebrand ◽  
Induced Aggregation ◽  
Willebrand Factor

SummaryPlatelet-type von Willebrand’s disease (vWD) is a bleeding disorder characterized by a heightened interaction between platelets and von Willebrand factor (vWF) as the result of an intrinsic platelet abnormality (probably in GPIb). Platelet aggregability was nearly normal in response to thrombin, wheat germ agglutinin and Ricinus communis agglutinin in this disorder. Unmodified platelets showed no aggregation upon the addition of peanut agglutinin. Partially purified human vWF induced little aggregation of washed patient platelets, but the aggregation was greatly enhanced in the presence of plasma devoid of vWF. Monoclonal antibodies directed against GPIb and GPIIb/IIIa as well as EDTA completely inhibited vWF-induced aggregation. These results indicate that human vWF induces aggregation of platelet-type vWD platelets in the presence of divalent cations and some plasma cofactor(s), and that both GPIb and GPIIb/IIIa are involved in this aggregation.

A Simple Enzyme-Immunoassay (EIA) Test for Factor VIII-Related Antigen (VIIIAGN)

1979 ◽  
Vol 42 (03) ◽  
pp. 848-854 ◽  
Author(s):  
Paul M Ness ◽  
Herbert A Perkins
Keyword(s):  
Factor Viii ◽  
Enzyme Immunoassay ◽  
Hemophilia A ◽  
Single Sample ◽  
Healthy Controls ◽  
Von Willebrand's Disease ◽  
Factor Viii Related Antigen ◽  
Von Willebrand’S Disease ◽  
Increased Sensitivity

SummaryAn enzyme immunoassay (EIA) system has been developed to measure factor VIII- related antigen (VIIIAGN). This assay gives similar results to the commonly used Laurell electroimmunodiffusion (EID) assay for VIIIAGN as shown by comparison of both techniques with samples from healthy controls, patients with hemophilia A, and patients with von Willebrand’s disease. The assay also has a greater precision than the EID technique as demonstrated by multiple assays of aliquots of a single sample. The use of this EIA test for VIIIAGN is simple and employs inexpensive reagents and equipment. The use of expensive antisera is minimized. EIA for VIIIAGN has the advantage of increased sensitivity compared to Laurell EIA.

scholarly journals Studies of the pathophysiology of acquired von Willebrand's disease in seven patients with lymphoproliferative disorders or benign monoclonal gammopathies

Blood ◽  
1984 ◽  
Vol 64 (3) ◽  
pp. 614-621 ◽  
Author(s):  
PM Mannucci ◽  
R Lombardi ◽  
R Bader ◽  
MH Horellou ◽  
G Finazzi ◽  
...  
Keyword(s):  
Lymphoproliferative Disorders ◽  
Type I ◽  
Agarose Gel Electrophoresis ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Monoclonal Gammopathies ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen ◽  
Ristocetin Cofactor

Abstract In seven patients with acquired von Willebrand's disease (AvWD) associated with lymphoproliferative disorders or benign monoclonal gammopathies, the platelet contents of von Willebrand factor antigen and ristocetin cofactor (vWF:Ag and vWF:RiCof, respectively) were normal. All the multimers of vWF:Ag could be seen in the 1.6% SDS- agarose gel electrophoresis patterns of plasma and platelet lysates. Infusion of 1-deamino-8-D-arginine vasopressin (DDAVP) augmented plasma levels of vWF:Ag and vWF:RiCof of all patients and corrected prolonged bleeding times (BT). However, compared with patients with congenital vWD type I and comparable degrees of baseline abnormalities treated in the same way, vWF:Ag and vWF:RiCof were increased less and cleared more rapidly from plasma and the BT remained normal for a shorter period of time. These studies provide evidence that these AvWD patients have qualitatively normal vWF in plasma, but at lower concentrations, that vWF in platelets is normal both qualitatively and quantitatively, and that cellular vWF can be rapidly released into plasma by DDAVP to correct the hemostatic abnormalities. However, vWF is removed rapidly from plasma, making the correction more transient than in congenital vWD type I.

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