assay

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assay

 [as´a]
determination of the purity of a substance or the amount of any particular constituent of a mixture.
biological assay bioassay; determination of the potency of a drug or other substance by comparing the effects it has on animals with those of a reference standard.
CH50 assay a test of total complement activity as the capacity of serum to lyse a standard preparation of sheep red blood cells coated with antisheep erythrocyte antibody. The reciprocal of the dilution of serum that lyses 50 per cent of the erythrocytes is the whole complement titer in CH50 units per milliliter of serum.
enzyme-linked immunosorbent assay (ELISA) any enzyme immunoassay using an enzyme-labeled immunoreactant (antigen or antibody) and an immunoadsorbent (antigen or antibody bound to a solid support). A variety of methods are used for measuring the unknown concentration, such as either competitive binding between the labeled reactant and unlabeled unknown or a sandwich technique in which the unknown antigen binds both the immunoadsorbent and labeled antibody. One of the uses of ELISA is to screen blood for antibody to the human immunodeficiency virus; a positive result indicates probable exposure to the virus and possibly that the virus is in the blood. Since false-positives can occur, a back-up test is used to confirm positive findings.
 ELISA: With antigen capture ELISA, the wells are coated with antibody to the virus. The sample containing virus (1) is added and, after washing several times, enzyme conjugated to an antibody to the virus is added (2). Finally, after a further cycle of washing, the enzyme's substrate (3) is added. A colored product is formed if the viral antigen is present in the sample (4). From Hart and Shears, 1997.
microhemagglutination assay–Treponema pallidum (MHA-TP) a Treponema pallidum hemagglutination assay using microtechniques; used in the detection of syphilis.
radioreceptor assay a radioligand assay in which a radiolabeled hormone is used to measure the concentration of specific cellular receptors for the hormone in tissue specimens, an example being radioassay of estrogen receptors in breast tissue.
thyroid-stimulating hormone assay thyroid-stimulating hormone test.
Treponema pallidum hemagglutination assay (TPHA) a treponemal antigen serologic test for syphilis using tanned sheep red blood cells coated with antigen from the Nichol's strain of Treponema pallidum and treated patient serum; it is similar in sensitivity and specificity to the FTA-ABS test. This test is not useful for individuals who have had syphilis in the past.

as·say

(as'sā, ă-sā'),
1. The quantitative or qualitative evaluation of a substance for impurities, toxicity, or other characteristics; the results of such an evaluation.
2. To examine; to subject to analysis.
3. Test of purity; trial.
[M.E., fr. O.Fr. essaier, fr. L.L. exagium, a weighing]

assay

A quantitative or qualitative procedure for detecting the presence, estimating the concentration, and/or determining the biological activity* of a macromolecule (e.g., an antibody or antigen, molecule, ion, cell, pathogen, etc.). Assays are based on measurable parameters that allow differentiation between sample and control. Biological assays (not to be confused with animal testing for drug efficacy and safety) are of historic interest, as they are cumbersome, difficult to quantify and rarely provide information that is not obtainable by other testing formats.

assay

Lab medicine The quantification of a substance of interest by a specific chemical, enzymatic, immunologic or radioimmune-mediated reaction

as·say

(as'ā)
1. To examine or analyze.
2. A test of the biologic potency of something (e.g., medicine).
[M.E., fr. O.Fr. essaier, fr. L.L. exagium, a weighing]

assay

Qualitative or quantitative analysis of a substance such as a drug.

Assay

An analysis of the chemical composition or strength of a substance.

as·say

(as'ā)
1. The quantitative or qualitative evaluation of a substance for impurities, toxicity, or other characteristics; the results of such an evaluation.
2. To examine; to subject to analysis.
3. Test of purity; trial.
[M.E., fr. O.Fr. essaier, fr. L.L. exagium, a weighing]
References in periodicals archive ?
The company stated the Panther Fusion Paraflu assay is a multiplexed assay that runs on the new Panther Fusion system.
Fractions were analyzed by the total-BNP and BNP1-32 Luminex assays.
The global multiple reaction monitoring assay market has been classified on the basis of assay type, usage, end user and geography.
Intra batch precision for the two assays was established by retesting a patient sample with low vWF and a healthy donor plasma with a normal level of vWF.
Of the 287 specimens tested, 109 (37.9%) were positive and 163 (56.8%) were negative by all three assays, giving a total agreement of 94.8% (272 of 287).
However, the mixing experiments indicated that the predominant mixtures of wild-type:resistant variant were 80:20, which is the lowest ratio of resistant variants that the assay can reliably detect (data not shown).
An assay that detects the RNA of HIV-1 has been approved by the Food and Drug Administration, making a gene-based test for the virus available to medical diagnostic laboratories for the first time.
Also in May, GE Healthcare Life Sciences and MDS Pharma Services introduced the in vitro micronucleus imaging assay for use with GE's IN Cell 1000 and 3000 cellular imaging systems.
Such alternative assays can be categorized as target organ/tissue assays [e.g., the bovine corneal opacity and permeability (BCOP) test, isolated rabbit eye (IRE) test, chicken enucleated eye test (CEET)]; organotypic models [e.g., the hen's egg test-chorioallantoic membrane (HET-CAM) assay, chorioallantoic membrane vascular assay (CAMVA), tissue equivalent assay]; cytotoxicity assays (e.g., neutral red assays, red blood cell lysis assay, fluorescein leakage assay); and chemical reaction assays (e.g., the Irritection Assay System).
Brunswick Laboratories has completed the development of its assays for COX-1 and COX-2 inhibition.