| double antibody sandwich assay | For antigen; an application of the ELISA method in which material being tested for antigen is added to wells coated with known antibody; the presence of antigen fixed to the antibody coat can be determined either directly, by adding human antibody linked to the enzyme of the indicator system, or indirectly, by first adding unlabelled known antibody, the attachment of which to the antigen can be demonstrated by addition of immunoglobulin-specific antibody linked to the enzyme. (05 Mar 2000) |
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| immunochemical assay | <investigation> A process that measures and identifies a specific biological substance such as an antigen. (09 Oct 1997) |
| immunocytochemical assay | Involves the computerised assessment of microscopic fields following direct fluorescent antibody, indirect fluorescent antibody or indirect or direct immunoperoxidase analysis of biopsy tissue from the patient. In addition to improved specificity with the removal of operator subjectivity, the quantifiability of results through computer data analysis of colour, intensity and concentration has only begun to be realised. (05 Mar 2000) |
| immunoradiometric assay | <immunology> A test that measures the concentration of antigens in a specimen throughserological analysis that involves mixing radioactive antibodies with the antigen in question. (09 Oct 1997) |
| indirect assay | For antibody; an application of the ELISA method in which serum being tested for antibody is added to wells coated with known antigen; presence of antibody bound to the antigen coat can be determined by addition of immunoglobulin-specific antibody to which is linked the enzyme of the indicator system, followed by addition of substrate to the washed aggregate. (05 Mar 2000) |
| Ouchterlony assay | <investigation> Immunological test for antigen antibody reactions in which diffusion of soluble antigen and antibody in a gel leads to precipitation of an antigen-antibody complex, visible usually as a whitish band. The system has the advantage that, because of radial diffusion of the reagents, a very wide range of ratios of antigen to antibody concentration develop, thus it is likely that precipitation will occur somewhere in the gel even when no care is taken with quantitation of the system. (18 Nov 1997) |
| EAC rosette assay | <haematology> Rosettes formed from erythrocytes (E) coated with antibody (A) and complement (C). A test for C3b or C3bi receptors (CR1 or CR3). The rosettes form more easily then E or EA rosettes. See: E rosettes. (16 Mar 2000) |
| enzyme-linked immunoabsorbent assay | <investigation> The enzyme-linked immunoabsorbent assay is serologic test used as a general screening tool for the detection of antibodies to the HIV virus. Reported as positive or negative. Since false positive tests due occur (for example recent flu shot), positives will require further evaluation using the western blot. ELISA technology links an a measurable enzyme to either an antigen or antibody. In this way, it can then measure the presence of an antibody or an antigen in the bloodstream. Acronym: ELISA (27 Sep 1997) |
| enzyme-linked immunosorbent assay | An immunoassay utilizing an antibody labelled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. (12 Dec 1998) |
| tumour stem cell assay | <investigation> A cytologic technique for measuring the functional capacity of tumour stem cells by assaying their activity. It is used primarily for the in vitro testing of antineoplastic agent. (12 Dec 1998) |
| factor II assay | A test used to measure the activity of a blood clotting factor (thrombin). This test may be used to evaluate excessive bleeding. Abnormally low factor II assays may be seen in the following conditions: congenital deficiency of factor II, fat malabsorption, heparin administration, cirrhosis, vitamin K deficiency and warfarin administration. (27 Sep 1997) |
| factor ix assay | A test used to measure the activity of a blood clotting factor IX (Christmas factor). This test may be used to evaluate excessive bleeding. Abnormally low factor IX assays may be seen in the following conditions: congenital deficiency of factor IX, fat malabsorption, heparin administration, cirrhosis, vitamin K deficiency and warfarin administration. (27 Sep 1997) |
| factor v assay | A test used to measure the activity of a blood clotting factor V. This test may be used to evaluate excessive bleeding. Abnormally low factor V assays may be seen in the following conditions: congenital deficiency of factor V, DIC, heparin administration, cirrhosis and primary fibrinolysis. (27 Sep 1997) |
| factor vii assay | A test used to measure the activity of a blood clotting factor VII. This test may be used to evaluate excessive bleeding. Abnormally low factor VII assays may be seen in the following conditions: congenital deficiency of factor VII, fat malabsorption, heparin administration, cirrhosis, vitamin K deficiency and warfarin administration. (27 Sep 1997) |
| factor viii assay | A test used to measure the activity of a blood clotting factor VIII (Von Willebrand factor). This test is usually used to monitor treatment of haemophilia. Abnormally low factor VIII assays may be seen in the following conditions: congenital deficiency of factor VIII (haemophilia), DIC and secondary fibrinolysis. This test may also be performed in the evaluation of Von Willebrand's disease. (27 Sep 1997) |