Activation of coagulation after administration of tumor necrosis factor to normal subjects

Article Abstract:

Septicemia (bacteria in the bloodstream) is often accompanied by disturbances of blood clotting, leading in extreme cases to disseminated intravascular coagulation (widespread clotting). The reasons for this association are not known, but a substance called tumor necrosis factor appears to play a role in initiating sepsis. Tumor necrosis factor is secreted by certain white blood cells as part of the body's defense system against invasion, and produces coagulation when tested under laboratory conditions. The effects of tumor necrosis factor on blood coagulation were evaluated in six healthy male volunteers who received an injection of the substance. Extremely sensitive assays were used to detect proteins important in clotting. Blood samples were taken prior to injection and at several times thereafter, and assayed for the presence of blood clotting factors. Normal blood clotting proceeds in a cascade fashion, where inactive enzymes (proteins) are activated and, in their turn, activate other enzymes. Clotting factors must be present for enzyme activation. Results showed that tumor necrosis factor led to activation of clotting by increasing the levels of factor X activation peptide and, more slowly, increasing levels of prothrombin fragment F1+2, substances involved in the intrinsic pathway of blood coagulation. Subjects experienced headache, nausea, and vomiting, as well as elevated body temperatures. These reactions disappeared by the end of the experiment. The findings indicated that tumor necrosis factor can activate clotting and could therefore contribute to the clotting disorders associated with sepsis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Tumor necrosis factor, Blood clotting, Blood coagulation, Septicemia

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Vascular-bed-specific hemostasis and hypercoagulable states

Article Abstract:

Research continues to show that different blood vessels in the body have different pro-coagulant and anti-coagulant mechanisms to maintain proper blood flow. When a blood vessel is injured, pro-coagulant forces predominate to form a blood clot. However, anti-coagulant forces also exist to ensure that the blood clot does not form unless absolutely necessary. Different pro-coagulant and anti-coagulant mechanisms mediate this process, depending on whether the blood vessel is in the lung, heart, liver, or brain. In physiologic terms, the extrinsic pathway is involved in coagulation and the intrinsic pathway prevents coagulation.

Blood clotting disorders, Blood coagulation disorders, Hemostasis

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Redesigning heparin

Article Abstract:

Researchers have developed a pentasaccharide that contains the biologically active region of the anticoagulant heparin but does not interact with other proteins and cells as heparin does. This could make the penasaccharide superior to heparin in preventing abnormal blood clotting because it would not have the side effects of heparin.

Editorial, Research, Anticoagulants (Medicine), Anticoagulants

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