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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).


(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.
References in periodicals archive ?
The database also includes pharmaceutical companies, biotech companies, CROs, hospitals, government labs and other organisations active in the Biological Assay research field.
Although biological assays have been the cornerstone of endocrinologic measurements, the development of the radioimmunoassay (RIA) completely changed the field of endocrinology (1).
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.
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.
Both parties will concentrate on screening ChromaDex's natural product libraries against certain biological assays and tumour models with the intent of identifying high value, potentially patentable natural products for specific therapeutic indications.
The assay answers the question of bioavailability at the cellular level, and was specifically developed to assist the transition of analytical chemistry testing of natural products into biological assays in vitro and in vivo.
Such interaction could not be discovered by the assays available at the start of the studies but development of new biological assays has revealed a stability issue related to certain containers.
Microfluidic Systems was founded in 2001 and is focused on the development of microfluidic systems for automated preparation of biological assays.
We screened the varieties again with the biological assays.
The ISB researchers have applied microfluidics--the study of how fluids behave at the nano level--to successfully conduct biological assays on single cells.

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