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 ?
On the basis on the end users/applications, this report focuses on the status and outlook for major applications/end users, sales volume, market share and growth rate of Plant Physiology Assay Kit for each application, including-
Specifically, the Panther Fusion module adds the capacity to run PCR (polymerase chain reaction) assays in addition to tests based on TMA (transcription-mediated amplification), the proprietary Hologic chemistry that powers its Aptima brand.
Once all three Panther Fusion assays are cleared, they will offer a modular approach to syndromic respiratory testing via the ability to run one, two or all three assays from a single patient specimen.
It states: "This consultation seeks to understand whether stakeholders would wish articles of precious metals which are hallmarked by UK Assay Offices in their overseas suboffices should carry a hallmark which is different from the hallmark applied in the UK.
After a subsequent wash step, the beads were resuspended in 100 [micro]L assay buffer before reading the plate on the Luminex 200 system.
Based on assay type, the global multiple reaction monitoring assay market is divided into following:
Impact of GeneXpert MTB/ RIF Assay on triage of respiratory isolation rooms for inpatients with presumed tuberculosis: a hypothetical trial.
The performance of the direct MODS assay and the direct TTC assay was compared with the indirect LJ PM and results were interpreted in terms of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).
An aliquot of the specimen from the freezer was subsequently sent to a reference laboratory (Trihealth Laboratories; Cincinnati, Ohio) for the tissue cell culture cytotoxin assay.
These 19 papers describe and evaluate a range of assay methods and associated topics, including endothelial cell biology, proliferation and migration assays, assays of tubule formation, models of the effects of the hemodynamic environment, whole or partial vessel outgrowth assays, endothelial-mural cell interactions, membrane and intracellular signaling events, implantation of sponges and polymers, assays in the chick, corneal assays, dorsal air sac models, chamber assays, tumor models, imagable models and vascular imaging, biological and clinical impact of the use of stem cells, a novel trial design of novel monitoring methods and future directions.