| FLA | fluorescent-labeled antibody; left frontoanterior [position of the fetus] [Lat. fronto-laeva anterio... |
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| fluor | fluorescence; fluorescent; fluorometry; fluoroscopy |
| FRA | fibrinogen-related antigen; fluorescent rabies antibody |
| FTA-ABS, | FTA-Abs fluorescent treponemal antibody, absorbed [test] |
| FTAT | fluorescent treponemal antibody test |
| radioimmunoprecipitation assay | Sensitive assay using radiolabelled antigens to detect specific antibodies in serum. The antigens are allowed to react with the serum and then precipitated using a special reagent such as protein a sepharose beads. The bound radiolabelled immunoprecipitate is then commonly analyzed by gel electrophoresis. Radioimmunoprecipitation assay (ripa) is often used as a confirmatory test for diagnosing the presence of HIV antibodies. (12 Dec 1998) |
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| radioligand assay | <radiobiology> Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labelled binding reagents (e.g., antibodies, intracellular receptors, plasma binders). (12 Dec 1998) |
| radioreceptor assay | A competitive binding assay in which the binder is a membrane or tissue receptor rather than an antibody. (05 Mar 2000) |
| Raji cell radioimmune assay | For immune complexes; a procedure by which immune complexes adsorbed from a test serum by a standard preparation of lymphoblastoid (Raji) cells are assayed by the capacity to bind 125I-labelled antibody to immunoglobulin. (05 Mar 2000) |
| gel retardation assay | A lab technique used to find out if there are proteins binding a fragment of DNA (in a DNA-protein complex) by watching how fast the DNA fragment moves through an electric field and seeing whether it moves slower when a particular protein is also present. (09 Oct 1997) |
| checkerboard assay | <procedure> Variant of the Boyden chamber assay for leucocyte chemotaxis introduced by Zigmond. By testing different concentrations of putative chemotactic factor in nongradient conditions, it is possible to calculate the enhancement of movement expected due simply to chemokinesis and to compare this with the distances moved in positive and negative gradients. Good experimental design thus allows chemotaxis to be distinguished from chemokinesis. (21 May 1997) |
| chloramphenicol acetyltransferase assay | <investigation> A lab technique used to determine whether a given fragment of DNA has a promoter on it to encourage transcription to occur, by attaching the gene (called the CAT gene) which codes for the CAT enzyme to it, and observing whether the CAT enzyme is produced. (05 Jan 1998) |
| Grunstein-Hogness assay | A procedure for identifying plasmid clones by colony hybridization. (05 Mar 2000) |
| christmas factor 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) |
| clonogenic assay | In vitro culturing of neoplastic cells to test their radiosensitivity or chemosensitivity, and probable clinical efficacy of a therapeutic agent. (05 Mar 2000) |
| colony-forming units assay | A cytologic technique for measuring the functional capacity of stem cells by assaying their activity. (12 Dec 1998) |
| competitive binding assay | General term for an assay in which a binder competes for labelled versus unlabelled ligand; following separation of free and bound ligand, the ligand (the analyte assayed) is quantitated by relating bound and unbound ratios to known standards. See: enzyme-linked immunosorbent assay, radioreceptor assay, immunoassay, enzyme-multiplied immunoassay technique, radioimmunoassay. Synonym: displacement analysis, saturation analysis. (05 Mar 2000) |
| complement binding assay | A test for the detection of immune complexes. (05 Mar 2000) |
| complement haemolytic activity assay | Usual screening assay for complement. Dilutions of the serum to be tested are added to antibody-coated erythrocytes and the percentage of lysis is measured. The values are expressed by ch50, haemolytic complement units per milliliter, which is the dilution of serum required to lyse 50 percent of the erythrocytes in the assay. (12 Dec 1998) |
| plaque assay | 1. <investigation> Assay for virus in which a dilute solution of the virus is applied to a culture dish containing a layer of the host cells, convective spread is prevented by making the medium very viscous. After incubation the plaques, areas in which cells have been killed (or transformed), can be recognised and the number of infective virus particles in the original suspension estimated. 2. Assay for cells producing antibody against erythrocytes or against antigen that has been bound to the erythrocytes. The cell is surrounded by a clear plaque of haemolysis. Basic principle behind the assay is the same as for the virus plaque assay. (18 Nov 1997) |