Standardisation of Factor VIII – V. Calibration of the 2nd International Standard for Factor VIII and von Willebrand Factor Activities in Plasma

1992 ◽  
Vol 68 (02) ◽  
pp. 155-159 ◽  
Author(s):  
A B Heath ◽  
T W Barrowcliffe
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Expert Committee ◽  
International Standard ◽  
Significant Difference ◽  
Factor Viii Antigen ◽  
Assay Methods ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThe proposed 2nd International Standard for Factor VIII and von Willebrand Factor activities in plasma, NIBSC code 87/718, was assayed against the 1st IRP, 80/511, and against fresh normal plasma, in 21 laboratories. There were no significant differences between the various assay methods for factor VIII antigen, von Willebrand factor antigen, and von Willebrand factor ristocetin co-factor activity. For factor VIII clotting activity there was a significant difference between the results of one-stage and two-stage assays. Plasma 87/718 has now been established by the WHO Expert Committee on Biological Standardisation as the 2nd IS for factor VIII and vWF in plasma with the following potencies: VIII:C 0.60 IU/ampoule; VIII:Ag 0.91 IU/ampoule; vWF:Ag 0.91 IU/ampoule; vWF/RCo 0.84 IU/ampoule.

Standardisation of von Willebrand Factor in Therapeutic Concentrates: Calibration of the 1st International Standard for von Willebrand Factor Concentrate (00/514)

2002 ◽  
Vol 88 (09) ◽  
pp. 380-386 ◽  
Author(s):  
Dawn Sands ◽  
Andrew Chang ◽  
Claudine Mazurier ◽  
Anthony Hubbard
Keyword(s):  
Von Willebrand Factor ◽  
International Study ◽  
Expert Committee ◽  
International Standard ◽  
A Value ◽  
Significant Difference ◽  
Factor Concentrate ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Good Agreement

SummaryAn international study involving 26 laboratories assayed two candidate von Willebrand Factor (VWF) concentrates (B and C) for VWF:Antigen (VWF:Ag), VWF:Ristocetin Cofactor (VWF:RCo) and VWF:Collagen binding (VWF:CB) relative to the 4th International Standard Factor VIII/VWF Plasma (4th IS Plasma) (97/586). Estimates of VWF:Ag showed good agreement between different methods, for both candidates, and the overall combined means were 11.01 IU/ml with inter-laboratory variability (GCV) of 10.9% for candidate B and 14.01 IU/ml (GCV 11.8%) for candidate C. Estimates of VWF:RCo showed no significant difference between methods for both candidates and gave overall means of 9.38 IU/ml (GCV 23.7%) for candidate B and 10.19 IU/ml (GCV 24.4%) for candidate C. Prior to the calibration of the candidates for VWF:CB it was necessary to calibrate the 4th IS Plasma relative to local frozen normal plasma pools; there was good agreement between different collagen reagents and an overall mean of 0.83 IU per ampoule (GCV 11.8%) was assigned. In contrast, estimates of VWF:CB in both candidates showed large differences between collagen reagents with inter-laboratory GCV’s of 40%. Candidate B (00/514) was established as the 1st International Standard von Willebrand Factor Concentrate by the WHO Expert Committee on Biological Standardisation in November 2001 with assigned values for VWF:Ag (11.0 IU/ampoule) and VWF:RCo (9.4 IU/ampoule). Large inter-laboratory variability of estimates precluded the assignment of a value for VWF:CB.

Comparative Study of Intranasal, Subcutaneous and Intravenous Administration of Desamino-D-Arginine Vasopressin (DDAVP)

1986 ◽  
Vol 55 (01) ◽  
pp. 108-111 ◽  
Author(s):  
M Köhler ◽  
P Hellstern ◽  
C Miyashita ◽  
G von Blohn ◽  
E Wenzel
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Factor Xii ◽  
Additional Advantage ◽  
Mean Values ◽  
Routes Of Administration ◽  
The Mean ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThis study was performed to evaluate the influence of different routes of administration on the efficacy of DDAVP treatment. Ten healthy volunteers received DDAVP intranasally (i.n.), subcutaneously (s.c.) and intravenously (i.v.) in a randomized cross-over trial. Factor XII and high molecular weight (HMW)-kininogen levels increased only slightly after DDAVP administration. The mean increase of factor VIII: C was 3.1 (i. v.), 2.3 (s. c.), and 1.3 (i.n.) - fold over baseline. Ristocetin cofactor (von Willebrand factor antigen) increased 3.1 (2.5), 2.0 (2.3) and 1.2 (1.2) - fold over baseline mean values after i.v., s.c. and i.n. DDAVP, respectively. The half-disappearance time of factor VIII and von Willebrand factor (vWF) after DDAVP ranged from five (factor VIII: C) to eight hours (vWF). The mean increase of fibrinolytic activity was more pronounced after i.v. DDAVP. The antidiuretic effect was moderate with no apparent differences between the routes of application. This study provides further evidence that both i.v. and s.c. DDAVP administration result in an appropriate and reliable stimulation of haemostasis. An additional advantage of s. c. administration is its suitability for home treatment.

scholarly journals High factor VIII antigen levels increase the risk of venous thrombosis but are not associated with polymorphisms in the von Willebrand factor and factor VIII gene

2001 ◽  
Vol 115 (1) ◽  
pp. 156-158 ◽  
Author(s):  
Pieter W. Kamphuisen ◽  
Jeroen C. J. Eikenboom ◽  
Frits R. Rosendaal ◽  
Ted Koster ◽  
Andrew D. Blann ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Factor Viii Gene ◽  
Factor Viii Antigen ◽  
Von Willebrand ◽  
Willebrand Factor

scholarly journals Fluctuations in Factor VIII Procoagulant, Antigen and Von Willebrand Factor in Normal Individuals

1977 ◽  
Author(s):  
H.C. Yang ◽  
C. Vaudreuil
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Normal Male ◽  
Normal Individuals ◽  
Factor Viii Antigen ◽  
The Mean ◽  
Von Willebrand ◽  
The Relationship ◽  
Willebrand Factor ◽  
Ristocetin Cofactor

Fluctuations in the relationship among factor VIII procoagulant (VIIIC), factor VIII antigen (VIIIAG) and von Willebrand factor (vWf, ristocetin cofactor) were studied in two normal females (A&B) and one normal male (C). Biweekly fasting morning plasma samples were obtained over a three week period and assayed on 2 different days. The mean VIIIC/VIIIAG, VIIIC/vWf and VIIIAG/vWf ratios were not significantly different from each other (p>.05) in each of the subjects. However, there were marked day-to-day changes in the three ratios as indicated by the ranges.The results demonstrate that although the ratios among factor VIII procoagulant, factor VIII antigen and von Willebrand factor are relatively fixed, there are significant day-to-day fluctuations.

Stabilization of the Antihemophilic Factor (VIII :AHF) by the Von Willebrand Factor (VIII :VWF): A Possible Model for Von Willebrand’s Disease

1977 ◽  
Author(s):  
H. J. Weiss ◽  
I. I. Sussman ◽  
L. W. Hoyer
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Von Willebrand's Disease ◽  
Von Willebrand’S Disease ◽  
Crossed Immunoelectrophoresis ◽  
Factor Viii Antigen ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Antihemophilic Factor

When compared with VIII:AHF in normal citrated plasmas, VIII:AHF activity showed increased lability at 37°C in the ‘late’ post-transfusion plasmas (VIII:AHF≫VIII:VWF) of a patient with von Willebrand’s disease, but not in the ‘early’ post-transfusion plasmas in which VIII:AHF~VIII:VWF. VIII:AHF was also labile in the baseline plasmas of 3 patients with von Willebrand’s disease in whom VIII:AHF≫VIII:VWF. In two of these patients the mobility of Factor VIII antigen (on crossed Immunoelectrophoresis) was increased. (VIII:AHF was not excessively labile in 4 other patients in whom VIII :AHF~VIII:VWF). In all of the above cases, VIII:AHF was stabilized by the addition of either purified von Willebrand factor or plasmas of patients with hemophilia, but not by plasmas of patients with severe von Willebrand’s disease. Thus, VIII:VWF may serve to stabilize VIII:AHF and this might explain the post-transfusion findings in von Willebrand’s disease.

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