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.

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.
References in periodicals archive ?
The CAP-e assay provides data that enables more complex biological assays to be more correctly interpreted.
They address methods for synthesizing new materials, dynamic cellular imaging, and biological assays. There is a deliberate emphasis on the use of nanoparticles, as one of the fundamental enabling nanoscale components for nanobiotechnology.
One of the emerging challenges for the NTP and the NIEHS is to use the best science to create, validate, and implement in environmental health research novel, robust, and efficient biological assays that will more effectively predict the risk of human disease and protect the health of our public.
"These screening assays are alternatives to biological assays used by regulatory agencies," Schneider says.
Aclara is a leading provider of biological assays used in drag discovery and development.
biological assays, enabling its LabChip(TM) platform to
It includes information on all aspects of drug research and development, from drug discovery to biological assays, pharmacokinetics, clinical trials, and post-market surveillance.
The Canadian team of organic chemists and enzymologists developed drug design motifs, and pursued preparative chemistry, enzymology, molecular biology, and tissue culture studies that were interfaced with biological assays and pharmacokinetic studies carried out in Syntex, Palo Alto, CA.
In the past, biological assays of acid rain's effects on lakes have focused largely on sport fish.
The insight gained from our detailed structural studies combined with biophysical characterization of protein-ligand interaction and cell biological assays will be used to design new ligands with superior chemical and biological properties.
Gold NanoSpheres are suitable as imaging contrast agents in a variety of applications including: photoacoustics, Raman spectroscopy, microscopy, biological assays, molecular imaging, and molecular therapy development.
PositiveID develops biological detection and diagnostics systems, specializing in the development of microfluidic systems for the automated preparation of and performance of biological assays.

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