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Updated: Aug 10, 2026

Endotoxin Activity Assay for the Detection of Whole Blood Endotoxemia in Critically Ill Patients
Published on: June 24, 2019
Bacterial endotoxin as inhibitor of the enzymatic activity of human thrombin
Robert Bucki1, Jennifer J Pastore
1Department of Physiology and the Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA. buckirob@mail.upenn.edu
Abstract:
Endotoxemia caused by bacterial lipopolysaccharides (LPS) deleteriously affects many aspects of hemostasis. Much of this effect is well characterized as being secondary to the LPS-mediated inflammatory response, but direct effects of LPS on coagulation factors may also contribute to disregulation of the hemostatic process. Spectrophotometric assays were used to investigate the effects of LPS from different bacteria on thrombin and plasmin activities. We found that enzymatic activity of purified thrombin, but not plasmin, decreases in the presence of endotoxin. LPS-mediated inhibition of thrombin activity can be reversed by plasma gelsolin and recombinant endotoxin-neutralizing protein. Preincubation of thrombin with LPS before platelet activation results in inhibition of aggregation and secretion. Additionally, a decrease of elastic shear moduli of fibrin gels was observed when their formation was induced with thrombin preincubated with LPS or when LPS was present in fibrinogen solutions during fibrin gel formation. When added to platelet-rich plasma, after activation with collagen, LPS-inhibited thrombin activity. LPS-mediated inhibition of thrombin activity may contribute to the hemostasis dysfunctions observed during endotoxemia.
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