What question did this study set out to answer?

Determine the extent to which heparin enhances the inactivation rate of activated factor XII species by antithrombin III in purified systems and human plasma.

July 1, 1985BloodOpen Access

Effect of heparin on the inactivation rate of human activated factor XII by antithrombin III

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Authors

RPRA PixleyTemple University MSM SchapiraUniversity of Lausanne RCRW ColmanUniversity of Minnesota

Discussion

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Overview

In vitro study demonstrates minimal heparin-induced acceleration of activated factor XII inhibition by antithrombin III in human plasma, suggesting negligible clinical impact on contact activation.

Key Points

Determine the extent to which heparin enhances the inactivation rate of activated factor XII species by antithrombin III in purified systems and human plasma.
Measured inactivation rates of purified factor XIIa and factor XIIf by antithrombin III in the presence of varying heparin concentrations ranging from 0.7 to 57.2 U/mL.
Assayed the inhibitory kinetics of factor XIIa and factor XIIf in factor XII-deficient and prekallikrein-deficient plasmas with and without therapeutic concentrations of heparin (1.4 to 1.5 U/mL).
In purified assays, therapeutic heparin (0.7 U/mL) increased factor XIIa inhibition by antithrombin III only fourfold (implying a 6% contribution to plasma inhibition), and heparin (1.5 U/mL) produced no detectable enhancement of factor XIIa inhibition in reconstituted factor XII-deficient plasma.
Heparin increased the inactivation rate constant of purified factor XIIf by 1.6- to 14.0-fold at concentrations of 3.6 to 57.2 U/mL, but 1.4 U/mL heparin did not modify factor XIIf inactivation in prekallikrein-deficient plasma, where C1 inhibitor remained the primary inhibitor.

Cite This Study

Pixley et al. (1985) studied this question.

synapsesocial.com/papers/6a72b58e75498292b70baedb https://doi.org/10.1182/blood.v66.1.198.198

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July 1, 1985BloodOpen Access

Effect of heparin on the inactivation rate of human activated factor XII by antithrombin III

View Full Paper

Ask AI

Bookmark

Authors

RPRA PixleyTemple University MSM SchapiraUniversity of Lausanne RCRW ColmanUniversity of Minnesota

Discussion

Member takes

Overview

In vitro study demonstrates minimal heparin-induced acceleration of activated factor XII inhibition by antithrombin III in human plasma, suggesting negligible clinical impact on contact activation.

Key Points

Determine the extent to which heparin enhances the inactivation rate of activated factor XII species by antithrombin III in purified systems and human plasma.
Measured inactivation rates of purified factor XIIa and factor XIIf by antithrombin III in the presence of varying heparin concentrations ranging from 0.7 to 57.2 U/mL.
Assayed the inhibitory kinetics of factor XIIa and factor XIIf in factor XII-deficient and prekallikrein-deficient plasmas with and without therapeutic concentrations of heparin (1.4 to 1.5 U/mL).
In purified assays, therapeutic heparin (0.7 U/mL) increased factor XIIa inhibition by antithrombin III only fourfold (implying a 6% contribution to plasma inhibition), and heparin (1.5 U/mL) produced no detectable enhancement of factor XIIa inhibition in reconstituted factor XII-deficient plasma.
Heparin increased the inactivation rate constant of purified factor XIIf by 1.6- to 14.0-fold at concentrations of 3.6 to 57.2 U/mL, but 1.4 U/mL heparin did not modify factor XIIf inactivation in prekallikrein-deficient plasma, where C1 inhibitor remained the primary inhibitor.

Cite This Study

Pixley et al. (1985) studied this question.

synapsesocial.com/papers/6a72b58e75498292b70baedb https://doi.org/10.1182/blood.v66.1.198.198

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