Search results
Results From The WOW.Com Content Network
Thromboplastin is sometimes used as a synonym for the protein tissue factor (with its official name "Coagulation factor III [thromboplastin, tissue factor]"). Historically, thromboplastin was a lab reagent, usually derived from placental sources, used to assay prothrombin times (PT). [3] When manipulated in the laboratory, a derivative could be ...
Tissue factor, also called platelet tissue factor or Coagulation factor III, [5] is a protein present in subendothelial tissue and leukocytes which plays a major role in coagulation and, in humans, is encoded by F3 gene. Its role in the blood clotting is the initiation of thrombin formation from the zymogen prothrombin.
Factor XI (FXI) is produced by the liver and circulates as a homo-dimer in its inactive form. [9] The plasma half-life of FXI is approximately 52 hours. The zymogen factor is activated into factor XIa by factor XIIa (FXIIa), thrombin, and FXIa itself; due to its activation by FXIIa, FXI is a member of the "contact pathway" (which includes HMWK, prekallikrein, factor XII, factor XI, and factor IX).
An alternative name for the factor is plasma thromboplastin component, given by an independent group in California. [66] Hageman factor, now known as factor XII, was identified in 1955 in an asymptomatic patient with a prolonged bleeding time named of John Hageman. Factor X, or Stuart-Prower factor, followed, in 1956.
Factor Xa plays a key role in all three of these stages. [16] In stage 1, Factor VII binds to the transmembrane protein TF on the surface of cells and is converted to Factor VIIa. The result is a Factor VIIa/TF complex, which catalyzes the activation of Factor X and Factor IX.
Factors VII, IX, and X all play key roles in blood coagulation and also share a common domain architecture. [10] The factor IX protein is composed of four protein domains: the Gla domain, two tandem copies of the EGF domain and a C-terminal trypsin-like peptidase domain which carries out the catalytic cleavage.
Fresh normal plasma has all the blood coagulation factors with normal levels. If the problem is a simple factor deficiency, mixing the patient plasma 1:1 with plasma that contains 100% of the normal factor level results in a level ≥50% in the mixture (say the patient has an activity of 0%; the average of 100% + 0% = 50%). [3]
Factor XII deficiency is a rare disorder that is inherited in an autosomal recessive manner. [19] Unlike other clotting factor deficiencies, factor XII deficiency is totally asymptomatic and does not cause excess bleeding. [19] Mice lacking the gene for factor XII, however, are less susceptible to thrombosis. The protein seems to be involved in ...