| AHA | acetohydroxamic acid; acquired hemolytic anemia; acute hemolytic anemia; American Heart Association;... |
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| AIA | allylisopropylacetamide; amylase inhibitor activity; anti-immunoglobulin antibody; anti-insulin anti... |
| ANA | acetylneuraminic acid; American Narcolepsy Association; American Neurological Association; American ... |
| APA | action potential amplitude; aldosterone-producing adenoma; Ambulatory Pediatric Association; America... |
| ATA | alimentary toxic aleukia; American Thyroid Association; aminotriazole; antithymic activity; antithyr... |
| anti-idiotype antibody | <immunology> An antibody directed against the antigen specific part of the sequence of an antibody or T-cell receptor and thus recognise the binding sites of other antibodies. In principle an anti-idiotype antibody should inhibit a specific immune response and they are important to the regulation of the immune system. (13 Nov 1997) |
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| anti-insulin antibody | A serologic blood test that is used to detect antibodies to insulin. This test is performed in insulin dependent diabetics who exhibit insulin resistance. The presence of antibodies denotes a positive result. (27 Sep 1997) |
| antinuclear antibody | <immunology> Antinuclear antibody is an antibody that react against components of the cell nucleus such as DNA, RNA, histone or non-histone proteins. These antibodies are present in a variety of immunologic or autoimmune diseases including systemic lupus erythematosus, systemic sclerosis, scleroderma, Sjogren's syndrome, rheumatoid arthritis, polymyositis, dermatomyositis and in persons taking hydralazine, procainamide or isoniazid. A serologic measurement for antinuclear antibodies can aid in the diagnosis of unexplained arthritis, rashes or chest pains. Acronym: ANA (12 Jan 1998) |
| anti-P antibody | <haematology, investigation> A serologic blood test used to detect the Donath-landsteiner antibody in serum. This test is performed in cases of suspected paroxysmal cold haemoglobinuria. A normal result is indicated by an absence of antibodies. The antibody is directed toward the P-antigen complex which is located on the surface of red blood cells. In some way, cold temperatures trigger the antibody to bind to this site. (13 Jan 1998) |
| antiparietal cell antibody | <immunology> A serologic blood test which measures the presence of antibodies to gastric parietal cells. Less than 2% of the general population will be antibody positive although this can be higher in the elderly. Approximately 90% of individuals with pernicious anaemia will be antibody positive. A positive result may also be seen in atrophic gastritis, gastric ulcer, thyroid disease, iron deficiency anaemia and diabetes. (13 Jan 1998) |
| antiphospholipid antibody | <immunology, syndrome> An uncommon disorder that is characterised by hypercoagulability due to the presence of antibodies against phospholipids. These patients exhibit a tendency for recurrent and life-threatening thrombosis and embolic events (for example stroke). Individuals with antiphospholipid syndrome also have an increased tendency toward deep venous thrombosis, myocardial infarction and spontaneous abortions in females. Antiphospholipid syndrome may be seen by itself or in association with other autoimmune illnesses (for example lupus) or with some infections. Treatment includes long-term heparin and warfarin. (13 Jan 1998) |
| antiphospholipid antibody syndrome | <syndrome> An immune disorder characterised by the presence of abnormal antibodies in the blood associated with certain medical conditions including abnormal blood clotting, migraine headaches, premature miscarriage, and low blood platelet counts (thrombocytopenia). (12 Dec 1998) |
| antithyroglobulin antibody | <endocrinology, immunology> A serologic blood test which measures the antithyroglobulin antibodies in the blood. Thyroglobulin is a protein found in thyroid tissue. It is the source of thyroid hormones in the body. The presence of antibodies to this protein can result in decreased thyroid gland function. A negative assay is considered normal. Conditions where the assay may be positive include: lupus, rheumatoid arthritis, Hashimoto's thyroiditis, thyrotoxicosis, hypothyroidism, thyroid cancer, myxoedema, Sjogren's syndrome and autoimmune haemolytic anaemia. (13 Jan 1998) |
| avidity antibody | The sum total of the functional binding strength between a polyvariant and its antibody. The total binding strength represents the sum strength of all the affinity bonds. (05 Mar 2000) |
| binding sites, antibody | Local surface sites on antibodies which react with antigen determinant sites on antigens. They are formed from parts of the variable regions of the fab fragment of the immunoglobulin. (12 Dec 1998) |
| bivalent antibody | Antibody that causes a visible reaction with specific antigen as in agglutination, precipitation, and so on; so-called because according to the "lattice theory" aggregation occurs when the antibody molecule has two or more binding sites that can crosslink one antigen particle to another; probably a characteristic of the class of immunoglobulin. (05 Mar 2000) |
| blocking antibody | An antibody used in a reaction to prevent some other reaction taking place, for example one antibody competing with another for a cell surface receptor. See: desensitisation. (18 Nov 1997) |
| reaginic antibody | <immunology> A type of antibody which is able to attach itself to the surfaces of cells without needing specific combining sites. A homocytotropic antibody will only bind to cells which are from the same species as itself. (09 Oct 1997) |
| maternal antibody | Any antibody transferred from a mammalian mother transplacentally into the foetus. See under immunoglobulin for details of the classes of Ig that are transferred to the foetus. (18 Nov 1997) |
| catalytic antibody | <chemistry> Antibody raised against a transition state analogue (e.g. A phosphate analogue of a carboxylic acid ester transition state) that can then catalyse the analogous chemical reaction, though not as effectively as a true enzyme. (16 Mar 1998) |