Composite blood component made of protein and phospholipids
Thromboplastin (TPL) is derived from cell membranes and is a mixture of both phospholipids and tissue factor, neither of which are enzymes. Thromboplastin acts on and accelerates the activity of Factor Xa, also known as thrombokinase,[1] aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin. Thromboplastin is found in brain, lung, and other tissues and especially in blood platelets.[2]
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 created called partial thromboplastin. Partial thromboplastin was used to measure the intrinsic pathway. This test is called the aPTT, or activated partial thromboplastin time. It was not until much later that the subcomponents of thromboplastin and partial thromboplastin were identified. Thromboplastin is the combination of both phospholipids and tissue factor, both of which are needed in the activation of the extrinsic pathway. However, partial thromboplastin is just phospholipids, and not tissue factor. Therefore, although the coagulation cascade can be triggered in vitro through the intrinsic pathway only, in vivo coagulation is triggered by the extrinsic pathway. However, the model better describing how coagulation works is the so-called cell-based model, a more integrated picture of the whole process, in which phospholipid surfaces, such as those provided by platelets, are a key component.
Currently, recombinant tissue factor is available and used in some PT assays.[further explanation needed] Placental derivatives are still available and are used in some laboratories. Phospholipid is available as an independent reagent or in combination with tissue factor as thromboplastin. Complete thromboplastin consists of tissue factor, phospholipids (since platelets were removed from blood sample being tested), and CaCl2 to reintroduce calcium ions which were chelated by sodium citrate originally used to prevent coagulation of the sample blood during transportation and/or storage.
^Milstone, J H (1964). "Thrombokinase as prime activator of prothrombin: historical perspectives and current status". Federation Proceedings. 23 (2): 742–748. doi:10.1085/jgp.47.2.315. PMC 2195336. PMID 14080818.
^Carlsen E, Stinessen MB, Prydz H (November 1987). "Differential effect of alpha-interferon and gamma-interferon on thromboplastin response in monocytes and endothelial cells". Clin. Exp. Immunol. 70 (2): 471–8. PMC 1542100. PMID 3123108.
^van den Besselaar AM, Chantarangkul V, Tripodi A (July 2010). "Thromboplastin standards". Biologicals. 38 (4): 430–6. doi:10.1016/j.biologicals.2010.02.012. PMID 20338779.
Thromboplastin (TPL) is derived from cell membranes and is a mixture of both phospholipids and tissue factor, neither of which are enzymes. Thromboplastin...
The partial thromboplastin time (PTT), also known as the activated partial thromboplastin time (aPTT or APTT), is a blood test that characterizes coagulation...
the initiation of thrombin formation from the zymogen prothrombin. Thromboplastin defines the cascade that leads to the activation of factor X—the tissue...
factor). PT is often used in conjunction with the activated partial thromboplastin time (aPTT) which measures the intrinsic pathway and common pathway...
determine the cause of prolongation of Prothrombin Time (PT), Partial Thromboplastin Time, or sometimes of thrombin time (TT). Mixing studies take advantage...
Factor XI, or plasma thromboplastin antecedent, is the zymogen form of factor XIa, one of the enzymes involved in coagulation. Like many other coagulation...
initiated by glass, the intrinsic pathway; or clotting was initiated by thromboplastin (a mix of tissue factor and phospholipids), the extrinsic pathway.[citation...
referring to tests such as the prothrombin time (PT), activated partial thromboplastin time (aPTT or PTT), activated clotting time (ACT), thrombin time (TT)...
does not contain any clotting factors such as fibrinogen, prothrombin, thromboplastin and many others. Serum includes all proteins not used in coagulation...
Haemophilia C (also known as plasma thromboplastin antecedent (PTA) deficiency or Rosenthal syndrome) is a mild form of haemophilia affecting both sexes...
significant changes in the platelet count, prothrombin and activated partial thromboplastin time in any of the meloxicam and indomethacin groups. Other crossover...
hemophilia, hemorrhage, and sickle-cell anemia. Prothrombin time and partial thromboplastin time blood tests are useful to investigate the reason behind the excessive...
coagulation disorders[citation needed] Condition Prothrombin time Partial thromboplastin time Bleeding time Platelet count Vitamin K deficiency or warfarin Prolonged...
coagulation times in laboratory tests such as the activated partial thromboplastin time (aPTT). Investigators speculate that the antibodies interfere with...
results when tested. Coagulation cascade Partial thromboplastin time (PTT), or activated partial thromboplastin time (aPTT or APTT) Prothrombin time (PT) David...
liver. These tests include prothrombin time (PT/INR), activated partial thromboplastin time (aPTT), albumin, bilirubin (direct and indirect), and others. The...
tests of blood coagulation include prothrombin time (PT) and partial thromboplastin time (aPTT) which measure coagulation factor function, but TEG also...
with heparin and warfarin therapy can be measured with the partial thromboplastin time (PTT) and prothrombin time (PT), respectively. Once clots have...
prothrombin time/international normalized ratio, and activated partial thromboplastin time as part of their initial workup. These tests help with screening...
therapy. APC resistance can be measured using either an activated partial thromboplastin time (aPTT)-based test or an endogenous thrombin potential (ETP)-based...
intravascular coagulation (DIC) such as a prolonged prothrombin time, partial thromboplastin time, and bleeding time. Filovirions such as EBOV may be identified...
screening will typically have been found to have a prolonged partial thromboplastin time (PTT) that does not correct in an 80:20 mixture with normal human...
normal prothrombin time, normal thrombin time, but prolonged partial thromboplastin time. Internal bleeding is common in people with severe haemophilia...
by the partial thromboplastin time (aPTT), one of the measures of the time it takes the blood plasma to clot. Partial thromboplastin time should not...
chelator/anticoagulant) Coagulation tests such as prothrombin time (PT) and partial thromboplastin time (PTT) and thrombin time (TT). Tube must be filled 100%. Plain red...
mg protamine sulfate IV for every 100 IU of active heparin. Partial thromboplastin time (PTT) should be monitored at 5 to 15 minutes after dose then in...
antiphospholipid antibody syndrome include a paradoxical prolonged partial thromboplastin time (which usually occurs in hemorrhagic disorders) and a positive...
operative ways to treat this disease. Blood tests: Prothrombin time Partial thromboplastin time "hemostasis". Merriam-Webster.com Dictionary. Retrieved 2016-01-21...
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