Lupus Coagulation Inhibitor: An antiphospholipid antibody found in association with systemic lupus erythematosus (LUPUS ERYTHEMATOSUS, SYSTEMIC;), ANTIPHOSPHOLIPID SYNDROME; and in a variety of other diseases as well as in healthy individuals. In vitro, the antibody interferes with the conversion of prothrombin to thrombin and prolongs the partial thromboplastin time. In vivo, it exerts a procoagulant effect resulting in thrombosis mainly in the larger veins and arteries. It further causes obstetrical complications, including fetal death and spontaneous abortion, as well as a variety of hematologic and neurologic complications.Blood Coagulation: The process of the interaction of BLOOD COAGULATION FACTORS that results in an insoluble FIBRIN clot.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.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.Blood Coagulation Factor Inhibitors: Substances, usually endogenous, that act as inhibitors of blood coagulation. They may affect one or multiple enzymes throughout the process. As a group, they also inhibit enzymes involved in processes other than blood coagulation, such as those from the complement system, fibrinolytic enzyme system, blood cells, and bacteria.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.Coagulation Protein Disorders: Hemorrhagic and thrombotic disorders resulting from abnormalities or deficiencies of coagulation proteins.Blood Coagulation Factors: Endogenous substances, usually proteins, that are involved in the blood coagulation process.Lupus Erythematosus, Systemic: A chronic, relapsing, inflammatory, and often febrile multisystemic disorder of connective tissue, characterized principally by involvement of the skin, joints, kidneys, and serosal membranes. It is of unknown etiology, but is thought to represent a failure of the regulatory mechanisms of the autoimmune system. The disease is marked by a wide range of system dysfunctions, an elevated erythrocyte sedimentation rate, and the formation of LE cells in the blood or bone marrow.Protein S: The vitamin K-dependent cofactor of activated PROTEIN C. Together with protein C, it inhibits the action of factors VIIIa and Va. A deficiency in protein S; (PROTEIN S DEFICIENCY); can lead to recurrent venous and arterial thrombosis.Factor VIIa: Activated form of factor VII. Factor VIIa activates factor X in the extrinsic pathway of blood coagulation.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: A disorder characterized by procoagulant substances entering the general circulation causing a systemic thrombotic process. The activation of the clotting mechanism may arise from any of a number of disorders. A majority of the patients manifest skin lesions, sometimes leading to PURPURA FULMINANS.Lupus Nephritis: Glomerulonephritis associated with autoimmune disease SYSTEMIC LUPUS ERYTHEMATOSUS. Lupus nephritis is histologically classified into 6 classes: class I - normal glomeruli, class II - pure mesangial alterations, class III - focal segmental glomerulonephritis, class IV - diffuse glomerulonephritis, class V - diffuse membranous glomerulonephritis, and class VI - advanced sclerosing glomerulonephritis (The World Health Organization classification 1982).Thrombin: An enzyme formed from PROTHROMBIN that converts FIBRINOGEN to FIBRIN.Blood Coagulation Tests: Laboratory tests for evaluating the individual's clotting mechanism.Blood Coagulation Disorders: Hemorrhagic and thrombotic disorders that occur as a consequence of abnormalities in blood coagulation due to a variety of factors such as COAGULATION PROTEIN DISORDERS; BLOOD PLATELET DISORDERS; BLOOD PROTEIN DISORDERS or nutritional conditions.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.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.Lupus Erythematosus, Discoid: A chronic form of cutaneous lupus erythematosus (LUPUS ERYTHEMATOSUS, CUTANEOUS) in which the skin lesions mimic those of the systemic form but in which systemic signs are rare. It is characterized by the presence of discoid skin plaques showing varying degrees of edema, erythema, scaliness, follicular plugging, and skin atrophy. Lesions are surrounded by an elevated erythematous border. The condition typically involves the face and scalp, but widespread dissemination may occur.Antibodies, Antinuclear: Autoantibodies directed against various nuclear antigens including DNA, RNA, histones, acidic nuclear proteins, or complexes of these molecular elements. Antinuclear antibodies are found in systemic autoimmune diseases including systemic lupus erythematosus, Sjogren's syndrome, scleroderma, polymyositis, and mixed connective tissue disease.Fibrinolysis: The natural enzymatic dissolution of FIBRIN.Argon Plasma Coagulation: A method of tissue ablation and bleeding control that uses ARGON plasma (ionized argon gas) to deliver a current of thermocoagulating energy to the area of tissue to be coagulated.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.Thrombelastography: Use of a thrombelastograph, which provides a continuous graphic record of the physical shape of a clot during fibrin formation and subsequent lysis.Whole Blood Coagulation Time: The time required by whole blood to produce a visible clot.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.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.Antithrombin III: A plasma alpha 2 glycoprotein that accounts for the major antithrombin activity of normal plasma and also inhibits several other enzymes. It is a member of the serpin superfamily.Fibrinogen: Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products.Fibrin Fibrinogen Degradation Products: Soluble protein fragments formed by the proteolytic action of plasmin on fibrin or fibrinogen. FDP and their complexes profoundly impair the hemostatic process and are a major cause of hemorrhage in intravascular coagulation and fibrinolysis.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 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).Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Protein C: A vitamin-K dependent zymogen present in the blood, which, upon activation by thrombin and thrombomodulin exerts anticoagulant properties by inactivating factors Va and VIIIa at the rate-limiting steps of thrombin formation.Factor V: Heat- and storage-labile plasma glycoprotein which accelerates the conversion of prothrombin to thrombin in blood coagulation. Factor V accomplishes this by forming a complex with factor Xa, phospholipid, and calcium (prothrombinase complex). Deficiency of factor V leads to Owren's disease.Factor XIII: A fibrin-stabilizing plasma enzyme (TRANSGLUTAMINASES) that is activated by THROMBIN and CALCIUM to form FACTOR XIIIA. It is important for stabilizing the formation of the fibrin polymer (clot) which culminates the coagulation cascade.Laser Coagulation: The use of green light-producing LASERS to stop bleeding. The green light is selectively absorbed by HEMOGLOBIN, thus triggering BLOOD COAGULATION.Fibrin: A protein derived from FIBRINOGEN in the presence of THROMBIN, which forms part of the blood clot.Blood Coagulation Disorders, Inherited: Hemorrhagic and thrombotic disorders that occur as a consequence of inherited abnormalities in blood coagulation.Electrocoagulation: Procedures using an electrically heated wire or scalpel to treat hemorrhage (e.g., bleeding ulcers) and to ablate tumors, mucosal lesions, and refractory arrhythmias. It is different from ELECTROSURGERY which is used more for cutting tissue than destroying and in which the patient is part of the electric circuit.Thrombosis: Formation and development of a thrombus or blood clot in the blood vessel.Anticoagulants: Agents that prevent clotting.Thrombin Time: Clotting time of PLASMA mixed with a THROMBIN solution. It is a measure of the conversion of FIBRINOGEN to FIBRIN, which is prolonged by AFIBRINOGENEMIA, abnormal fibrinogen, or the presence of inhibitory substances, e.g., fibrin-fibrinogen degradation products, or HEPARIN. BATROXOBIN, a thrombin-like enzyme unaffected by the presence of heparin, may be used in place of thrombin.Antithrombins: Endogenous factors and drugs that directly inhibit the action of THROMBIN, usually by blocking its enzymatic activity. They are distinguished from INDIRECT THROMBIN INHIBITORS, such as HEPARIN, which act by enhancing the inhibitory effects of antithrombins.Mice, Inbred NZBFactor XII: Stable blood coagulation factor activated by contact with the subendothelial surface of an injured vessel. Along with prekallikrein, it serves as the contact factor that initiates the intrinsic pathway of blood coagulation. Kallikrein activates factor XII to XIIa. Deficiency of factor XII, also called the Hageman trait, leads to increased incidence of thromboembolic disease. Mutations in the gene for factor XII that appear to increase factor XII amidolytic activity are associated with HEREDITARY ANGIOEDEMA TYPE III.Mice, Inbred MRL lpr: A mouse substrain that is genetically predisposed to the development of systemic lupus erythematosus-like syndrome, which has been found to be clinically similar to the human disease. It has been determined that this mouse strain carries a mutation in the fas gene. Also, the MRL/lpr is a useful model to study behavioral and cognitive deficits found in autoimmune diseases and the efficacy of immunosuppressive agents.Antiphospholipid Syndrome: The presence of antibodies directed against phospholipids (ANTIBODIES, ANTIPHOSPHOLIPID). The condition is associated with a variety of diseases, notably systemic lupus erythematosus and other connective tissue diseases, thrombopenia, and arterial or venous thromboses. In pregnancy it can cause abortion. Of the phospholipids, the cardiolipins show markedly elevated levels of anticardiolipin antibodies (ANTIBODIES, ANTICARDIOLIPIN). Present also are high levels of lupus anticoagulant (LUPUS COAGULATION INHIBITOR).Antibodies, Antiphospholipid: Autoantibodies directed against phospholipids. These antibodies are characteristically found in patients with systemic lupus erythematosus (LUPUS ERYTHEMATOSUS, SYSTEMIC;), ANTIPHOSPHOLIPID SYNDROME; related autoimmune diseases, some non-autoimmune diseases, and also in healthy individuals.Antibodies, Anticardiolipin: Antiphospholipid antibodies found in association with systemic lupus erythematosus (LUPUS ERYTHEMATOSUS, SYSTEMIC;), ANTIPHOSPHOLIPID SYNDROME; and in a variety of other diseases as well as in healthy individuals. The antibodies are detected by solid-phase IMMUNOASSAY employing the purified phospholipid antigen CARDIOLIPIN.beta 2-Glycoprotein I: A 44-kDa highly glycosylated plasma protein that binds phospholipids including CARDIOLIPIN; APOLIPOPROTEIN E RECEPTOR; membrane phospholipids, and other anionic phospholipid-containing moieties. It plays a role in coagulation and apoptotic processes. Formerly known as apolipoprotein H, it is an autoantigen in patients with ANTIPHOSPHOLIPID ANTIBODIES.Cardiolipins: Acidic phospholipids composed of two molecules of phosphatidic acid covalently linked to a molecule of glycerol. They occur primarily in mitochondrial inner membranes and in bacterial plasma membranes. They are the main antigenic components of the Wassermann-type antigen that is used in nontreponemal SYPHILIS SERODIAGNOSIS.