Factor VIIa
Activated form of factor VII. Factor VIIa activates factor X in the extrinsic pathway of blood coagulation.
Thromboplastin
Constituent composed of protein and phospholipid that is widely distributed in many tissues. It serves as a cofactor with factor VIIa to activate factor X in the extrinsic pathway of blood coagulation.
Factor VII
Heat- and storage-stable plasma protein that is activated by tissue thromboplastin to form factor VIIa in the extrinsic pathway of blood coagulation. The activated form then catalyzes the activation of factor X to factor Xa.
Factor X
Storage-stable glycoprotein blood coagulation factor that can be activated to factor Xa by both the intrinsic and extrinsic pathways. A deficiency of factor X, sometimes called Stuart-Prower factor deficiency, may lead to a systemic coagulation disorder.
Factor Xa
Activated form of factor X that participates in both the intrinsic and extrinsic pathways of blood coagulation. It catalyzes the conversion of prothrombin to thrombin in conjunction with other cofactors.
Blood Coagulation
The process of the interaction of BLOOD COAGULATION FACTORS that results in an insoluble FIBRIN clot.
Hemophilia A
The classic hemophilia resulting from a deficiency of factor VIII. It is an inherited disorder of blood coagulation characterized by a permanent tendency to hemorrhage.
Off-Label Use
Hemostatics
Agents acting to arrest the flow of blood. Absorbable hemostatics arrest bleeding either by the formation of an artificial clot or by providing a mechanical matrix that facilitates clotting when applied directly to the bleeding surface. These agents function more at the capillary level and are not effective at stemming arterial or venous bleeding under any significant intravascular pressure.
Factor IX
Storage-stable blood coagulation factor acting in the intrinsic pathway. Its activated form, IXa, forms a complex with factor VIII and calcium on platelet factor 3 to activate factor X to Xa. Deficiency of factor IX results in HEMOPHILIA B (Christmas Disease).
Antithrombin III
1-Carboxyglutamic Acid
Found in various tissues, particularly in four blood-clotting proteins including prothrombin, in kidney protein, in bone protein, and in the protein present in various ectopic calcifications.
Terbium
Prothrombin Time
Clotting time of PLASMA recalcified in the presence of excess TISSUE THROMBOPLASTIN. Factors measured are FIBRINOGEN; PROTHROMBIN; FACTOR V; FACTOR VII; and FACTOR X. It is used for monitoring anticoagulant therapy with COUMARINS.
Hemostasis
The process which spontaneously arrests the flow of BLOOD from vessels carrying blood under pressure. It is accomplished by contraction of the vessels, adhesion and aggregation of formed blood elements (eg. ERYTHROCYTE AGGREGATION), and the process of BLOOD COAGULATION.
Hemophilia B
A deficiency of blood coagulation factor IX inherited as an X-linked disorder. (Also known as Christmas Disease, after the first patient studied in detail, not the holy day.) Historical and clinical features resemble those in classic hemophilia (HEMOPHILIA A), but patients present with fewer symptoms. Severity of bleeding is usually similar in members of a single family. Many patients are asymptomatic until the hemostatic system is stressed by surgery or trauma. Treatment is similar to that for hemophilia A. (From Cecil Textbook of Medicine, 19th ed, p1008)
Thrombin
Postoperative Hemorrhage
Blood Coagulation Factors
Endogenous substances, usually proteins, that are involved in the blood coagulation process.
Partial Thromboplastin Time
The time required for the appearance of FIBRIN strands following the mixing of PLASMA with phospholipid platelet substitute (e.g., crude cephalins, soybean phosphatides). It is a test of the intrinsic pathway (factors VIII, IX, XI, and XII) and the common pathway (fibrinogen, prothrombin, factors V and X) of BLOOD COAGULATION. It is used as a screening test and to monitor HEPARIN therapy.
Benzamidines
Factor XIa
Activated form of factor XI. In the intrinsic pathway, Factor XI is activated to XIa by factor XIIa in the presence of cofactor HMWK; (HIGH MOLECULAR WEIGHT KININOGEN). Factor XIa then activates factor IX to factor IXa in the presence of calcium.
Factor IXa
Activated form of factor IX. This activation can take place via the intrinsic pathway by the action of factor XIa and calcium, or via the extrinsic pathway by the action of factor VIIa, thromboplastin, and calcium. Factor IXa serves to activate factor X to Xa by cleaving the arginyl-leucine peptide bond in factor X.
Lipoproteins
Lipid-protein complexes involved in the transportation and metabolism of lipids in the body. They are spherical particles consisting of a hydrophobic core of TRIGLYCERIDES and CHOLESTEROL ESTERS surrounded by a layer of hydrophilic free CHOLESTEROL; PHOSPHOLIPIDS; and APOLIPOPROTEINS. Lipoproteins are classified by their varying buoyant density and sizes.
Disseminated Intravascular Coagulation
Prothrombin
A plasma protein that is the inactive precursor of thrombin. It is converted to thrombin by a prothrombin activator complex consisting of factor Xa, factor V, phospholipid, and calcium ions. Deficiency of prothrombin leads to hypoprothrombinemia.
Binding Sites
Factor VIII
Blood-coagulation factor VIII. Antihemophilic factor that is part of the factor VIII/von Willebrand factor complex. Factor VIII is produced in the liver and acts in the intrinsic pathway of blood coagulation. It serves as a cofactor in factor X activation and this action is markedly enhanced by small amounts of thrombin.
Factor VII Deficiency
An autosomal recessive characteristic or a coagulation disorder acquired in association with VITAMIN K DEFICIENCY. FACTOR VII is a Vitamin K dependent glycoprotein essential to the extrinsic pathway of coagulation.
Embolism, Amniotic Fluid
Fibrin
A protein derived from FIBRINOGEN in the presence of THROMBIN, which forms part of the blood clot.
Chromogenic Compounds
Colorless, endogenous or exogenous pigment precursors that may be transformed by biological mechanisms into colored compounds; used in biochemical assays and in diagnosis as indicators, especially in the form of enzyme substrates. Synonym: chromogens (not to be confused with pigment-synthesizing bacteria also called chromogens).
Receptor, PAR-2
A G-protein-coupled, proteinase-activated receptor that is expressed in a variety of tissues including ENDOTHELIUM; LEUKOCYTES; and the GASTROINTESTINAL TRACT. The receptor is activated by TRYPSIN, which cleaves off the N-terminal peptide from the receptor. The new N-terminal peptide is a cryptic ligand for the receptor. The uncleaved receptor can also be activated by the N-terminal peptide present on the activated THROMBIN RECEPTOR and by small synthetic peptides that contain the unmasked N-terminal sequence.