The functional role of the autolysis loop in the regulation of Factor X upon hemostatic response

SummaryWe measured total and free protein S (PS), protein C (PC) and factor X (FX) in 393 healthy blood donors to assess differences in relation to sex, hormonal state and age. All measured proteins were lower in women as compared to men, as were levels in premenopausal women as compared to postmenopausal women. Multiple regression analysis showed that both age and subgroup (men, pre- and postmenopausal women) were of significance for the levels of total and free PS and PC, the subgroup effect being caused by the differences between the premenopausal women and the other groups. This indicates a role of sex-hormones, most likely estrogens, in the regulation of levels of pro- and anticoagulant factors under physiologic conditions. These differences should be taken into account in daily clinical practice and may necessitate different normal ranges for men, pre- and postmenopausal women.

Download Full-text

The Activation of Human Factor X in Sodium Citrate: the Role of Factor VII

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648014 ◽

1976 ◽

Vol 36 (01) ◽

pp. 104-114 ◽

Cited By ~ 3

Author(s):

D. L Aronson ◽

A. J Mustafa

Keyword(s):

Sodium Citrate ◽

Human Factor ◽

Deae Cellulose ◽

Factor Ix ◽

Factor Vii ◽

Factor X

SummaryHuman factor X was purified by several different procedures yielding products which had varying amounts of factor VII and factor IX. Treatment with CHC13 during the fractionation of the factor X removed 95% of the factor VII and factor IX activity and the resulting factor X activated more slowly when incubated in 25% sodium citrate. Removal of residual factor VII by DEAE cellulose chromatography yielded a factor X which activated still more slowly and less completely. When the factor VII, removed by chromatography, was added to the chromatographed factor X, the ability to be activated in 25% sodium citrate was restored. Confirmatory evidence for the role of factor VII in this reaction was the inhibition of the conversion of the factor X by both DFP and SBTI.

Download Full-text

The Formation of Intermediate Product I in a Purified System The Role of Factor IX or of its Precursor and of a Hageman Factor-PTA Fraction

Thrombosis and Haemostasis ◽

10.1055/s-0038-1654555 ◽

1961 ◽

Vol 6 (02) ◽

pp. 224-234 ◽

Cited By ~ 4

Author(s):

E. T Yin ◽

F Duckert

Keyword(s):

Intermediate Product ◽

Factor Ix ◽

Assay Method ◽

Lag Phase ◽

Factor X ◽

Haemophilia B ◽

Hageman Factor ◽

One Stage ◽

The One

Summary1. The role of two clot promoting fractions isolated from either plasma or serum is studied in a purified system for the generation of intermediate product I in which the serum is replaced by factor X and the investigated fractions.2. Optimal generation of intermediate product I is possible in the purified system utilizing fractions devoid of factor IX one-stage activity. Prothrombin and thrombin are not necessary in this system.3. The fraction containing factor IX or its precursor, no measurable activity by the one-stage assay method, controls the yield of intermediate product I. No similar fraction can be isolated from haemophilia B plasma or serum.4. The Hageman factor — PTA fraction shortens the lag phase of intermediate product I formation and has no influence on the yield. This fraction can also be prepared from haemophilia B plasma or serum.

Download Full-text