| assay | <procedure> The determination of the amount of a particular constituent of a mixture or of the biological or pharmacological potency of a drug. (10 May 1997) |
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| bandshift assay | <investigation> An assay for proteins, such as transcription factors, that bind specific DNA sequences. A labelled oligonucleotide corresponding to the recognition sequence is incubated with an appropriate nuclear protein extract and run on a nondenaturing acrylamide gel. Oligonucleotides that have been bound by proteins are retarded relative to those that are unbound. (18 Nov 1997) |
| biological assay | <technique> Once a pharmaceutical protein is isolated from the cells in which it was grown, researchers perform tests to measure the protein's biological activity. It must maintain a certain minimal level of biological activity to be used for animal or clinical testing or, later, for market. Researchers also test to confirm that the isolated protein is identical to the desired protein. (21 Mar 1998) |
| 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) |
| 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) |