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A method for the quantitation of the effects on a biological system by its exposure to a substance, as well as the quantitation of the concentration of a substance by some observable effect on a biological system. The biological material in which the effect is measured can range from subcellular components and microorganisms to groups of animals. The substance can be stimulatory, such as an ion increasing taxis behavior in certain protozoans, or inhibitory, such as an antibiotic for bacterial growth. Bioassays are most frequently used when there is a number of steps, usually poorly understood, between the substance and the behavior observed, or when the substance is a complex mixture of materials and it is not clear what the active components are. Bioassays can be replaced, in time, by either a more direct measure of concentration of the active principle, such as an analytical method (for example, mass spectrometry, high-pressure liquid chromatography, radioimmunoassay), or a more direct measurement of the effect, such as binding to a surface receptor in the case of many drugs, as the substance or its mechanism of action is better characterized.

Assays to quantitate the effects of an exposure model the effect of a substance in the real world. Complex biological responses can be estimated by laboratory culture tests, which use, for example, bacteria or cells cultured in a petri dish (usually to model an effect either on the organism of interest, such as bacteria, or on some basic cellular function); by tissue or organ culture, which isolates pieces of tissue or whole organs in a petri dish (usually to model organ function); or in whole animals (usually to model complex organismic relationships).

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


(analytical chemistry)
A method for quantitatively determining the concentration of a substance by its effect on the growth of a suitable animal, plant, or microorganism under controlled conditions.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
To address these challenges, Biotest is utilizing Schreiner MediPharm's Late Stage Customization service.
It also provides Biotest with the benefits of greater flexibility and the ability to respond to market requirements with requisite agility.
Despite the requirement to cover the traditional three trophic levels with biotest species, the aquatic tests battery for waste testing and hazard classification does not include fish (bioluminescent bacteria, algae and crustacean tests are proposed).
Biotest (UK) has relocated from its current base in Solihull to take occupation of the 3,797 sq ft office.
The difference in the swimming speeds under control conditions is explained by some differences in the size of Daphnia taken for biotest (2.4 mm for [K.sub.2]Cr2[O.sub.7] and 2.1 mm for ZnS[O.sub.4] x 7[H.sub.2]O).
Biotest said it is registering encouraging growth despite the delayed approval of its Bivigam and the debt crisis in Greece.
ImmunoGen's collaborative partners include Amgen, Bayer HealthCare Pharmaceuticals, Biotest, Lilly, Novartis, Roche, and Sanofi.
The contamination was discovered after ferrets were injected with the vaccine, according to BioTest s.r.o., a biotechnology company based in Konarovice that was working with the immunization in the Czech Republic.
"Biotest Diagnostics is consolidating and relocating from its previous location in Denville and will use 400 Commons Way as its United States headquarters.