biological 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.

biological assay

See bioassay.

bioassay

Lab medicine
Any quantification procedure to detect:
(1) The activity or potency—functional or effective—amount of a substance—e.g., antibiotic, chemical, drug, hormone, metabolit, vitamin, etc.—in a biological fluid;
(2) Toxicity of a substance (e.g., a pollutant) or organism (e.g., a pathogen) of interest in an in vivo system, i.e., in a cell or animal; in bioassays, the effect is tested on living cells or organisms.
 
Molecular biology
An assay that uses a living system, such as an intact cell, to measure an effect or a molecule of interest.
 
Radiation physics
A determination of the quantity of radioactive material in the human body, either by direct measurement—in vivo counting—or by analysis of excreta.

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 database currently tags 158,000 individuals working with Biological Assays.
Early estimates of CCK-like activity in blood were based on biological assays such as pancreatic secretion or gallbladder contraction.
Chromagen will develop biological assays and screen CombiChem compounds, while receiving research support and a percentage of future payments received by CombiChem upon outlicensing of drug candidates.
Bruce Evans and Martin Reaney carried out the biological assays in Larry Gusta's laboratory at the University of Saskatchewan.
A diverse and large set of data ranging from chemistry leads to biological assays and protein sequencing will now be managed and analysed through the Dotmatics Platform.
Version 14 deepens compound qualification from biological assays by providing compound-centric overviews and results across experiments, sub-experiments, assay groups, and panels.
This partnership will focus on screening ChromaDex's natural product libraries against certain biological assays and tumor models, with the intent of identifying high value, potentially patentable natural products for specific therapeutic indications.
Compared to currently available antibody technology on the market, such as mouse hybridomas, Epitomics' technology can generate antibodies with superior binding affinity and bioactivity in a wide variety of biological assays.
Lack of biological assays to measure many of these contaminants in tissue specimens, the high cost of using these assays in large epidemiologic studies when they were available, and challenges related to the interpretation of the results when exposures were measured after the adverse reproductive event occurred limit the conclusions that can be drawn from these investigations.
This will be accomplished through the use of TIM-2 (the company's in vitro model of the large intestine), in vivo studies, in vitro biological assays and pattern-recognition.
These modified AFM tips allow rapid and reliable screening of samples for targeted molecular interactions of material, chemical, or biological assays.
Meso Scale Discovery, a division of Meso Scale Diagnostics, LLC (MSD[R]) develops and markets solutions for multiplex biological assays, including assays for biomarkers, cytokines and phosphoproteins.

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