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Dilute Russell's Viper Venom Time
Dilute Russell's viper venom time (dRVVT) is a laboratory test often used for detection of lupus anticoagulant (LA). History Russell's viper venom (RVV) was known to clot blood many years ago. It was widely used as a styptic to clot minor wounds when razor blades were more commonly used for shaving (e.g. “Stypven”, Burroughs-Wellcome Pharma). RVV came to be useful in laboratory tests for blood clotting factors V, X, prothrombin and phospholipid. It was first used in clotting tests for lupus anticoagulant (LA) in an individual case in 1975. The “dilute Russells Viper Venom time (dRVVT)” test was then applied in 1985 to diagnose LA in a large number of patients and it became more widely used for this purpose. This multi-step method involved adding individual solutions of dilute phospholipid, RVV and calcium chloride to a test plasma and then measuring how long it took for the mixture to clot. In 1989, researchers at Westmead Hospital developed a simpler assay by combining ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daboia Head
''Daboia'' is a genus of venomous snake, venomous Viperinae, vipers.. Species The following four species are recognized as being valid: *''Daboia mauritanica'' – Moorish viper *''Daboia palaestinae'' – Palestine viper *''Daboia russelii'' – Russell's viper *''Daboia siamensis'' – eastern Russell's viper In the future, more species may be added to ''Daboia''. Obst (1983) reviewed the genus and suggested that it be extended to include ''Macrovipera lebetina'', ''Daboia palaestinae'', and ''Montivipera xanthina, M. xanthina''. Groombridge (1980, 1986) united ''V. palaestinae'' and ''Daboia'' as a clade based on a number of shared apomorphy, apomorphies, including snout shape and head color pattern. Lenk et al. (2001) found support for this idea based on molecular evidence, suggesting that ''Daboia'' not only include ''V. palaestinae'', but also ''Daboia mauritanica, D. mauritanica'' and ''Macrovipera deserti, M. deserti''.Mallow D, Ludwig D, Nilson G (2003). ''True Vipe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor VIII
Factor VIII (FVIII) is an essential blood-clotting protein, also known as anti-hemophilic factor (AHF). In humans, factor VIII is encoded by the ''F8'' gene. Defects in this gene result in hemophilia A, a recessive X-linked coagulation disorder. Factor VIII is produced in liver sinusoidal cells and endothelial cells outside the liver throughout the body. This protein circulates in the bloodstream in an inactive form, bound to another molecule called von Willebrand factor, until an injury that damages blood vessels occurs. In response to injury, coagulation factor VIII is activated and separates from von Willebrand factor. The active protein (sometimes written as coagulation factor VIIIa) interacts with another coagulation factor called factor IX. This interaction sets off a chain of additional chemical reactions that form a blood clot. Factor VIII participates in blood coagulation; it is a cofactor for factor IXa, which, in the presence of Ca2+ and phospholipids, forms a complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antiphospholipid Syndrome
Antiphospholipid syndrome, or antiphospholipid antibody syndrome (APS or APLS), is an autoimmune, hypercoagulable state caused by antiphospholipid antibodies. APS provokes blood clots (thrombosis) in both arteries and veins as well as pregnancy-related complications such as miscarriage, stillbirth, preterm delivery, and severe preeclampsia. Although the exact etiology of APS is still not clear, genetics is believed to play a key role in the development of the disease. The diagnostic criteria require one clinical event (i.e. thrombosis or pregnancy complication) and two positive blood test results spaced at least three months apart that detect lupus anticoagulant, anti-apolipoprotein antibodies, or anti-cardiolipin antibodies. Antiphospholipid syndrome can be primary or secondary. Primary antiphospholipid syndrome occurs in the absence of any other related disease. Secondary antiphospholipid syndrome occurs with other autoimmune diseases, such as systemic lupus erythematosu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ELISA
The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the protein to be measured. ELISA has been used as a diagnostic tool in medicine, plant pathology, and biotechnology, as well as a quality control check in various industries. In the most simple form of an ELISA, antigens from the sample to be tested are attached to a surface. Then, a matching antibody is applied over the surface so it can bind the antigen. This antibody is linked to an enzyme and then any unbound antibodies are removed. In the final step, a substance containing the enzyme's substrate is added. If there was binding, the subsequent reaction produces a detectable signal, most commonly a color change. Performing an ELISA involves at least ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-β2 Glycoprotein-I Antibodies
In autoimmune disease, anti-apolipoprotein H (AAHA) antibodies, also called anti-β2 glycoprotein I antibodies, comprise a subset of anti-cardiolipin antibodies and lupus anticoagulant. These antibodies are involved in sclerosis and are strongly associated with thrombotic forms of lupus. As a result AAHA are strongly implicated in autoimmune deep vein thrombosis. Also, it was proposed that AAHA is responsible for lupus anticoagulant. However, antiphospholipid antibodies bind phospholipids at sites similar to sites bound by anti-coagulants such as PAP1 sites and augment anti-coagulation activity. This contrasts with the major, specific, activity of AAHA, defining a subset of anti-cardiolipin antibodies that specifically interacts with Apo-H. AHAA only inhibits the anti-coagulation activity in the presence of Apo-H and the AAHA component of ACLA correlates with a history of frequent thrombosis. This can be contrasted with lupus anticoagulant which inhibits agglutination in the prese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anticardiolipin Antibodies
Anti-cardiolipin antibodies (ACA) are antibodies often directed against cardiolipin and found in several diseases, including syphilis, antiphospholipid syndrome, livedoid vasculitis, vertebrobasilar insufficiency, Behçet's syndrome, idiopathic spontaneous abortion, and systemic lupus erythematosus (SLE). They are a form of anti-mitochondrial antibody. In SLE, anti-DNA antibodies and anti-cardiolipin antibodies may be present individually or together; the two types of antibodies act independently. This is in contrast to rheumatoid arthritis with systemic sclerosis (scleroderma) because anti-cardiolipin antibodies are present in both conditions, and therefore may tie the two conditions together. Anti-cardiolipin antibodies can be classified in two ways: * As IgM, IgG or IgA * As β2-glycoprotein dependent or independent ** In autoimmune disease, ACA are beta-2 glycoprotein dependent ** In syphilis, ACA are beta-2 glycoprotein independent and can be assayed using the Venereal Dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serological
Serology is the scientific study of serum and other body fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum. Such antibodies are typically formed in response to an infection (against a given microorganism), against other foreign proteins (in response, for example, to a mismatched blood transfusion), or to one's own proteins (in instances of autoimmune disease). In either case, the procedure is simple. Serological tests Serological tests are diagnostic methods that are used to identify antibodies and antigens in a patient's sample. Serological tests may be performed to diagnose infections and autoimmune illnesses, to check if a person has immunity to certain diseases, and in many other situations, such as determining an individual's blood type. Serological tests may also be used in forensic serology to investigate crime scene evidence. Several methods can be used to detect antibodies and antigens, including ELISA, agglutinati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antiphospholipid Syndrome
Antiphospholipid syndrome, or antiphospholipid antibody syndrome (APS or APLS), is an autoimmune, hypercoagulable state caused by antiphospholipid antibodies. APS provokes blood clots (thrombosis) in both arteries and veins as well as pregnancy-related complications such as miscarriage, stillbirth, preterm delivery, and severe preeclampsia. Although the exact etiology of APS is still not clear, genetics is believed to play a key role in the development of the disease. The diagnostic criteria require one clinical event (i.e. thrombosis or pregnancy complication) and two positive blood test results spaced at least three months apart that detect lupus anticoagulant, anti-apolipoprotein antibodies, or anti-cardiolipin antibodies. Antiphospholipid syndrome can be primary or secondary. Primary antiphospholipid syndrome occurs in the absence of any other related disease. Secondary antiphospholipid syndrome occurs with other autoimmune diseases, such as systemic lupus erythematosu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor XI
Factor XI or plasma thromboplastin antecedent is the zymogen form of factor XIa, one of the enzymes of the coagulation cascade. Like many other coagulation factors, it is a serine protease. In humans, Factor XI is encoded by the ''F11'' gene. Function Factor XI (FXI) is produced by the liver and circulates as a homo-dimer in its inactive form. 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). Factor XIa activates factor IX by selectively cleaving arg-ala and arg- val peptide bonds. Factor IXa, in turn, forms a complex with Factor VIIIa (FIXa-FVIIIa) and activates factor X. Physiological inhibitors of factor XIa include protein Z-dependent protease inhibitor (ZPI, a member of the serine protease inhibitor/serpin class ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor IX
Factor IX (or Christmas factor) () is one of the serine proteases of the coagulation system; it belongs to peptidase family S1. Deficiency of this protein causes haemophilia B. It was discovered in 1952 after a young boy named Stephen Christmas was found to be lacking this exact factor, leading to haemophilia. Coagulation factor IX is on the World Health Organization's List of Essential Medicines. Physiology Factor IX is produced as a zymogen, an inactive precursor. It is processed to remove the signal peptide, glycosylated and then cleaved by factor XIa (of the contact pathway) or factor VIIa (of the tissue factor pathway) to produce a two-chain form, where the chains are linked by a disulfide bridge. When activated into factor IXa, in the presence of Ca2+, membrane phospholipids, and a Factor VIII cofactor, it hydrolyses one arginine-isoleucine bond in factor X to form factor Xa. Factor IX is inhibited by antithrombin. Factor IX expression increases with age in humans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
APTT
The partial thromboplastin time (PTT), also known as the activated partial thromboplastin time (aPTT or APTT), is a blood test that characterizes coagulation of the blood. A historical name for this measure is the kaolin-cephalin clotting time (KCCT), reflecting kaolin and cephalin as materials historically used in the test. Apart from detecting abnormalities in blood clotting, partial thromboplastin time is also used to monitor the treatment effect of heparin, a widely prescribed drug that reduces blood's tendency to clot. The PTT measures the overall speed at which blood clots form by means of two consecutive series of biochemical reactions known as the ''intrinsic'' pathway and common pathway of coagulation. The PTT indirectly measures action of the following coagulation factors: I (fibrinogen), II (prothrombin), V (proaccelerin), VIII (anti-hemophilic factor), X (Stuart–Prower factor), XI (plasma thromboplastin antecedent), and XII (Hageman factor). The PTT is of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lupus Anticoagulant
Lupus anticoagulant is an immunoglobulin that binds to phospholipids and proteins associated with the cell membrane. Its name is a partial misnomer, as it is actually a prothrombotic antibody ''in vivo''. Lupus anticoagulant in living systems causes a decrease in clotting time. The name derives from their properties ''in vitro'', as these antibodies increase coagulation times in laboratory tests such as the activated partial thromboplastin time (aPTT). Investigators speculate that the antibodies interfere with phospholipids used to induce in vitro coagulation. In vivo, the antibodies are thought to interact with platelet membrane phospholipids, increasing adhesion and aggregation of platelets, which accounts for the in vivo prothrombotic characteristics. The condition was first described by hematologist C. Lockard Conley in 1952. Terminology Both words in the term "lupus anticoagulant" can be misleading: * Most patients with a lupus anticoagulant do not actually have lupus erythem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
