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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.
Early estimates of CCK-like activity in blood were based on biological assays such as pancreatic secretion or gallbladder contraction.
Delivery Conditions: Ddp (According to Incoterms 2000) For: - Equipment and Furniture Specifically for the Chemical Analysis of Drinking Water for - 9 Laboratories - Equipment and Furniture for Biological Assays Specific for Drinking Water - One Laboratory; the Standstill Clause - Award Procedure Is Initiated Under the Provisions of This Clause Suspensive, Meaning That the Contract of Public Procurement Is Subject to Completion of the Financing Contract with the Ministry of Environment and Climate Change Direction Sop Environment (European Funds), Signing Being Made Compliance with the Provisions of Art.
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.
Microfluidic Systems was founded in 2001 and is focused on the development of microfluidic systems for automated preparation of 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.
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.
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.
validated commercial molecular biological assays for the NI, UK and ROI processors across the Agri-food sector.
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.
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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