The bleeding time in normal subjects is mainly determined by platelet von Willebrand factor and is independent from blood group

1992 ◽  
Vol 65 (4-5) ◽  
pp. 605-615 ◽  
Author(s):  
Francesco Rodeghiero ◽  
Giancarlo Castaman ◽  
Marco Ruggeri ◽  
Alberto Tosetto
Keyword(s):  
Blood Group ◽  
Von Willebrand Factor ◽  
Bleeding Time ◽  
Normal Subjects ◽  
Von Willebrand ◽  
Willebrand Factor

BLEEDING TIME IN NORMAL SUBJECTS: ITS RELATIONSHIP WITH SEX, AGE, BLOOD GROUP, HEMATOCRIT, PLATELET COUNT AND PLASMA VON WILLEBRAND FACTOR LEVEL

1987 ◽  
Author(s):  
F Rodeghiero ◽  
G Castaman ◽  
E Di Bona ◽  
M Ruggeri
Keyword(s):  
Platelet Count ◽  
Blood Group ◽  
Von Willebrand Factor ◽  
Bleeding Time ◽  
Physiological Parameters ◽  
Factor Level ◽  
Significant Difference ◽  
Von Willebrand ◽  
Willebrand Factor

Bleeding time (BT) is the most important test for in "vivo" Vevaluation of primary hemostasis. Several physiological parameters namely sex, age, blood group, hematocrit, platelet count and von Willebrand factor level could exert a significant influenceIn this study, the relationships between BT (Simplate II,General Diagnostics)and these physiological parameters havebeen examined in 58 subjects aging 17-71 (32 males and 26 females; 26 of 0 and 32 of non-0 group). In all the subjects bleedingdiathesis was excluded by interview. They were not taking anvmedicament for at least 10 days and showed normal platelet aggregation by ADP and ArachidonateMean BT value (seconds) was 318± 65 (range 195-A95)Statistical analysis failed to show any significant difference realated to sex and blood group. There was no significant relationship with hematocrit (0.01), platelet count (−0.2A), age (−0.28) and von Willebrand factor level, mesured as ristocetin cofactor (−0.2A). In particular, our data indicate that higher von Willebrand factor levels found in non-0 group in comparison with O-group (113.3 vs 83.5, P < 0:001) do not exert any apparent influence on bleeding time

Association Between Bleeding Time and Platelet Adherence to Artery Subendothelium

1984 ◽  
Vol 52 (02) ◽  
pp. 144-147 ◽  
Author(s):  
K S Sakariassen ◽  
P A Bolhuis ◽  
Margaretha Blombäck ◽  
L Thorell ◽  
Birger Blombäck ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Bleeding Time ◽  
Blood Platelets ◽  
Normal Subjects ◽  
Commercial Preparation ◽  
Normal Platelet ◽  
Platelet Adherence ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryThe efficacy of five different factor VUI-von Willebrand factor (FVIII-VWF) preparations in mediating adherence of blood platelets to damaged vessel walls was tested in an annular perfusion chamber utilizing human arteries and reconstituted blood.FVIII-VWF-purified by Sepharose CL-4B chromatography and von Willebrand factor prepared from this preparation by dissociation with 0.25 M CaCl2 followed by Sepharose CL-6B chromatography were equally effective in mediating platelet adherence as FVIII-VWF in cryoprecipitate and in plasma from normal subjects. A commercial concentrate of FVIII-VWF (Hemofil, Hyland) used for the treatment of haemophiliacs did not mediate platelet adherence at normal levels of FVIII-VWF related properties. A recently developed high-purity FVIII-VWF preparation (Concentrate II) containing multimers of high molecular weight normalized the platelet adherence. Platelet adherence in plasma obtained from two patients with von Willebrand’s disease (VWD) was impaired, but plasma samples obtained following treatment with Concentrate II mediated normal platelet adherence. The normalization of platelet adherence paralleled the normalization of the bleeding time.This platelet adherence assay offers an inexpensive and efficient in vitro tool to test the efficacy of FVIII-VWF preparations designed for VWD patients. Preparations such as cryoprecipitate and Concentrate II mediated the platelet adherence and normalized the bleeding time. The commercial preparation did not mediate platelet adherence and had no effect on the bleeding time.

scholarly journals Influence of blood group, von Willebrand factor levels, and age on factor VIII levels in non‐severe haemophilia A

2020 ◽  
Vol 18 (5) ◽  
pp. 1081-1086
Author(s):  
Judit Rejtő ◽  
Oliver Königsbrügge ◽  
Ella Grilz ◽  
Stefanie Hofer ◽  
Lisa‐Marie Mauracher ◽  
...  
Keyword(s):  
Factor Viii ◽  
Blood Group ◽  
Von Willebrand Factor ◽  
Haemophilia A ◽  
Severe Haemophilia ◽  
Von Willebrand ◽  
Willebrand Factor

scholarly journals New Method for Assessment of Plasma Von Willebrand Factor

1977 ◽  
Author(s):  
T. Sano ◽  
T. Motomiya ◽  
N. Mashimo ◽  
H. Yamazaki
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Platelet Rich Plasma ◽  
Normal Subjects ◽  
Induce Platelet Aggregation ◽  
Platelet Suspension ◽  
Maximal Plasma ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Diabetes Melitus

As much interests have been focused on von Willebrand factor (vWF) in diabetes melitus and atherosclerosis, request to determine vWF has been increasing recently. Two methods for assessment of plasma vWF level, without platelet aggregometer, were devised. 1) Platelet-rich plasma (PRP) sensitivity to ristocetin-induced platelet aggregation (RIPA): PRP was separated without centrifugation from citrated blood. Serially two-fold diluted restocetin (16 to 16x2-10 mg/ml) was prepared in a Cooke Microtiter tray and PRP (25 μl each) was added to each concentration of ristocetin. Then the ristocetin-PRP mixture was agitated for 15 seconds using a Kowa Kizai Micromixer and the minimum effective final concentration of ristocetin to give platelet aggregation was obtained microscopically and this was defined as PRP sensitivity to RIPA. This method is convenient for screening test. 2) vWF assay:Serially two-fold diluted plasma (2 to 1024 times, in Tris-salin pH 7.2 containing 12 mg/ml bovine serum albumin), fixed and washed platelet suspension (6x105 /μl, Macfarlane et al.1975) and 3 mg/ml ristocetin were mixed (25 μl each) in a microtiter tray and agitated for 15 seconds. The maximal plasma dilution to induce platelet aggregation was obtained microscopically and defined as the titer of plasma vWF. In normal subjects, minimum effective ristocetin concentration (PRP sensitivity to RIPA) was around 1 to 0.5 mg/ml and maximal plasma dilution to give platelet aggregation (vWF titer) was around 16 to 32 times. The present methods have a good reproducibility and are performed easily without aggregometer and thought to be useful clinically.

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