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Bioassay (commonly used shorthand for biological assay or assessment), or biological standardization is a type of scientific experiment. A bioassay involves the use of live animal or plant (in vivo) or tissue or cell (in vitro) to determine the biological activity of a substance, such as a hormone or drug. Bioassays are typically conducted to measure the effects of a substance on a living organism and are essential in the development of new drugs and in monitoring environmental pollutants. Both are procedures by which the potency or the nature of a substance is estimated by studying its effects on living matter. A bioassay can also be used to determine the concentration of a particular constitution of a mixture that may cause harmful effects on organisms or the environment.

Use[edit]

Bioassays are procedures that can determine the concentration or purity or biological activity of a substance such as vitamin, hormone or plant growth factor by measuring the effect on an organism, tissue, cells, enzyme or receptor. Bioassays may be qualitative or quantitative. Qualitative bioassays are used for assessing the physical effects of a substance that may not be quantified, such as seeds fail to germinate or develop abnormally deformity. An example of a qualitative bioassay includes Arnold Adolph Berthold's famous experiment on castrated chickens. This analysis found that by removing the testicles of a chicken, it would not develop into a rooster because the endocrine signals necessary for this process were not available. Quantitative bioassays involve estimation of the concentration or potency of a substance by measurement of the biological response that it produces. Quantitative bioassays are typically analyzed using the methods of biostatistics.

Definition[edit]

"The determination of the relative strength of a substance (e.g., a drug or hormone or toxicant) by comparing its effect on a test organism with that of a standard preparation." is called bioassay. ....

Purpose[edit]

  1. Measurement of the pharmacological activity of new or chemically undefined substances
  2. Investigation of the function of endogenous mediators
  3. Determination of the side-effect profile, including the degree of drug toxicity
  4. Measurement of the concentration of known substances (alternatives to the use of whole animals have made this use obsolete)
  5. Assessing the amount of pollutants being released by a particular source, such as wastewater or urban runoff.
  6. Determining the specificity of certain enzymes to certain substrates.

Types[edit]

Bioassays are of two types:

Quantal[edit]

A quantal assay involves an "all or none response". For example: Insulin induced hypoglycemic convulsive reaction or the cardiac arrest caused by digitalis. The response is either +ve or -ve, there is no intermediate response e.g.—either convulsion occurs or doesn't occur; similarly is with cardiac arrest.


In case of toxicity studies, the animal receiving a dose of drug either dies or does not die. Also, no intermediate response is possible. This is also known as the "all or none" response assay. The quantal method though not precise is employed for bioassay of substance in the following ways:
(a) Comparison of threshold response or
(b) Comparison of effective dose (ED50) or median lethal dose (LD50)

Graded[edit]

Graded assays are based on the observation that there is a proportionate increase in the observed response following an increase in the concentration or dose. The parameters employed in such bioassays are based on the nature of the effect the substance is expected to produce. For example: contraction of smooth muscle preparation for assaying histamine or the study of blood pressure response in case of adrenaline.

A graded bioassay can be performed by employing any of the below-mentioned techniques. The choice of procedure depends on:

  1. the precision of the assay required
  2. the quantity of the sample substance available
  3. the availability of the experimental animals.

Techniques[edit]

  1. Matching Bioassay
  2. Interpolation Method
  3. Bracketing Method
  4. Multiple Point Bioassay (i.e.-Three-point, Four-point and Six Point Bioassay)

Matching Bioassay: It is the simplest type of the bioassay. In this type of bioassay, response of the test substance taken first and the observed response is tried to match with the standard response. Several responses of the standard drug are recorded till a close matching point to that of the test substance is observed. A corresponding concentration is thus calculated. This assay is applied when the sample size is too small. Since the assay does not involve the recording of concentration response curve, the sensitivity of the preparation is not taken into consideration. Therefore, precision and reliability is not very good.

Interpolation bioassay: Bioassays are conducted by determining the amount of preparation of unknown potency required to produce a definite effect on suitable test animals or organs or tissue under standard conditions. This effect is compared with that of a standard. Thus the amount of the test substance required to produce the same biological effect as a given quantity the unit of a standard preparation is compared and the potency of the unknown is expressed as a % of that of the standard by employing a simple formula.


Many times, a reliable result cannot be obtained using this calculation. Therefore it may be necessary to adopt more precise methods of calculating potency based upon observations of relative, but not necessarily equal effects, likewise, statistical methods may also be employed. The data (obtained from either of assay techniques used) on which bioassay are based may be classified as quantal or graded response. Both these depend ultimately on plotting or making assumption concerning the form of DRC.

Environmental bioassays[edit]

Environmental bioassays are generally a broad-range survey of toxicity. A toxicity identification evaluation is conducted to determine what the relevant toxicants are. Although bioassays are beneficial in determining the biological activity within an organism, they can often be time-consuming and laborious. Organism-specific factors may result in data that is not applicable to others in that species. For these reasons, other biological techniques are often employed, including radioimmunoassays. See bioindicator.

Water pollution control requirements in the United States require some industrial dischargers and municipal sewage treatment plants to conduct bioassays. These procedures, called whole effluent toxicity tests, include acute toxicity tests as well as chronic test methods. The methods involve exposing living aquatic organisms to samples of wastewater.[1][2] For example the bioassay ECOTOX uses the microalgae Euglena gracilis to test the toxicity of water samples. [3] (See Bioindicator#Microalgae as bioindicators and water quality)

See also[edit]

References[edit]

  1. ^ United States Environmental Protection Agency (EPA). Washington, DC. "Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms." October 2002. Document No. EPA-821-R-02-012.
  2. ^ US EPA. "Whole Effluent Toxicity / Clean Water Act Analytical Methods." Accessed December 16, 2008.
  3. ^ Tahedl, Harald; Hader, Donat-Peter (1999). "Fast examination of water quality using the automatic biotest ECOTOX based on the movement behavior of a freshwater flagellate". Water Research 33 (2): 426–432. 

External links[edit]


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Bioassay — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.

46 news items

 
Genetic Engineering & Biotechnology News (blog)
Thu, 30 Oct 2014 06:07:30 -0700

IBC's 2014 Bioassay Conference emphasized not only the importance of verifying that assays are operating at full potency, but also the proper handling of potentially meaningful data outliers. CHI's Biomarkers and Diagnostics World Congress showcased ...
 
7thSpace Interactive (press release)
Wed, 01 Oct 2014 17:54:55 -0700

Experimental hut and bioassay evaluation of the residual activity of a polymer-enhanced suspension concentrate (SC-PE) formulation of deltamethrin for IRS use in the control of Anopheles arabiensis ...
 
AZoNano.com
Wed, 29 Oct 2014 02:56:15 -0700

The custom technologies arm of Molecular Devices, a leader in bioanalytical systems for drug discovery, life science research, and bioassay development, has partnered with the Discovery Technologies team at the Roche Innovation Center Basel of Pharma ...
 
Capital press
Mon, 29 Sep 2014 11:22:30 -0700

Equipment used in fields determined to have no viable cysts in bioassay must be pressure washed, though a steam-cleaning requirement is lifted, and the fields must remain PCN-free in full-field surveys following three potato crops before they can be ...
 
MarketWatch
Mon, 27 Oct 2014 13:07:33 -0700

The Company's xMAP system is an open-architecture, multi-analyte technology platform that delivers fast, accurate and cost-effective bioassay results to markets as diverse as pharmaceutical drug discovery, clinical diagnostics and biomedical research, ...
 
PR Web (press release)
Mon, 27 Oct 2014 10:03:45 -0700

Thyroid uptake studies, manual MCA program, wipe tests, bioassay, and other user-defined tasks are accomplished with speed and precision using this fully integrated computer-controlled instrument and its comprehensive selection of application software.
 
PR Newswire (press release)
Tue, 28 Oct 2014 04:03:45 -0700

SUNNYVALE, Calif., Oct. 28, 2014 /PRNewswire/ -- The custom technologies arm of Molecular Devices, a leader in bioanalytical systems for drug discovery, life science research, and bioassay development, has partnered with the Discovery Technologies ...
 
Smithsonian
Mon, 20 Oct 2014 08:35:48 -0700

Then, he or she places drops of the extracted sample into 96 wells on a prepared plate, known as a bioassay. Each well on the plate is pre-treated with its own bio-chemical mix that's designed to react with a specific type of microRNA. The tech then ...
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