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

/as·say/ (as´a) determination of the amount of a particular constituent of a mixture, or of the potency of a drug.
biological assay  bioassay.
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  see ELISA.
microbiological assay  assay by the use of microorganisms.
microcytotoxicity assay  one using the pattern of lysis of peripheral blood lymphocytes in the presence of complement and typing sera to type serologically defined HLA antigens (HLA-A, -B, and -C antigens).
radioimmunoprecipitation assay  (RIPA) immunoprecipitation conducted with radiolabeled antibody or antigen.
radioligand assay  any assay procedure that uses radioisotopic labeling and biologically specific binding of reagents.
stem cell assay  a measurement of the potency of antineoplastic drugs, based on their ability to retard the growth of cultures of human tumor cells.

assay

[asā′, as′ā]
Etymology: Fr, essayer, to try
the analysis of the purity, effectiveness, or concentration of drugs and other biological substances, including laboratory and clinical observations.

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]

assay

determination of the purity of a substance or the amount or activity 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 in a biological system with those of a reference standard.
References in periodicals archive ?
the hen's egg test-chorioallantoic membrane (HET-CAM) assay, chorioallantoic membrane vascular assay (CAMVA), tissue equivalent assay]; cytotoxicity assays (e.
The new offering developed by QIAGEN provides a very broad range of optimized and validated RNAi-based gene silencing solutions and, in addition, also links such RNAi solutions with the corresponding gene expression assay used in the subsequent qPCR-based knockdown validation.
The aim of this study was to establish a neutralizing antibody assay using murine leukemia virus (MLV) pseudotypes bearing the SARS-CoV S envelope, MLV(SARS), and to profile neutralizing antibody responses to SARS-CoV natural infection during a relatively long period in a cohort of Hong Kong patients who had recovered from the disease.
The protein assay kit consists of a protein extraction solution, test strips, reagent solutions for developing protein spot on the test strips, a card for estimating protein concentration by measuring the protein spot diameter and a simple-to-follow protocol.
While the Ames test still comes out ahead, he says, a battery of tests can now offer somewhat better discrimination of hazard risk than any one assay alone.
com announces that a new market research report is available in its catalogue: Assay Development Services], Application (Drug Discovery, ADMET), End-user (Pharmaceutical, CRO) - Global Forecast to 2018 very-ADMET-End-user-Pharmaceutical-CRO Global-Forecast-to-2018.
The combination of nuchal translucency and assay of maternal serum free hCGB and PAPP-A improves the detection of affected fetuses.
When the high similarity between the orthopoxviruses is considered, this rapid assay that uses vaccinia antigens could identify recently exposures.
In this study we examined estrogenic activity of styrene oligomers after metabolic activation by rat liver microsomes, trans-1,2-Diphenylcyclobutane (TCB), cis-1,2-diphenylcyclobutane (CCB), 1,3-diphenylpropane, 2,4-diphenyl-1-butene, 2,4,6-triphenyl-1-hexene, and 1[alpha]-phenyl-4[beta]-(1'-phenylethyl)tetralin were negative in the yeast estrogen screening assay and estrogen reporter assay using estrogen-responsive human breast cancer cell line MCF-7.
We developed a competitive enzyme-linked immunosorbent assay (ELISA) to analyze brevetoxins, using goat anti-brevetoxin antibodies obtained after immunization with keyhole limpet hemo-cyanin-brevetoxin conjugates, in combination with a three-step signal amplification process.
Moreover, unlike imaging assays, a fast and simple, single-addition protocol is used, which provides broad assay window and robust z'.