Bioassay
Encyclopedia
Bioassay or biological standardization is a type of scientific experiment
. 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 pollutant
s. Both are procedures by which the potency
or the nature of a substance is estimated by studying its effects on living matter.
. An example of a qualitative bioassay includes Arnold Adolph Berthold
's famous experiment on castrated chickens. This analysis found that by removing the testes 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
.
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)
A graded bioassay can be performed by employing any of the below-mentioned techniques. The choice of procedure depends on:
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 from of DRC.
. A toxicity identification evaluation is conducted to determine what the relevant toxicant
s 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 radioimmunoassay
s. 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.
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
. Bioassays are typically conducted to measure the effects of a substance on a living organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
and are essential in the development of new drugs
DRUGS
Destroy Rebuild Until God Shows are an American post-hardcore band formed in 2010. They released their debut self-titled album on February 22, 2011.- Formation :...
and in monitoring environmental pollutant
Pollutant
A pollutant is a waste material that pollutes air, water or soil, and is the cause of pollution.Three factors determine the severity of a pollutant: its chemical nature, its concentration and its persistence. Some pollutants are biodegradable and therefore will not persist in the environment in the...
s. Both are procedures by which the potency
Potency (pharmacology)
In the field of pharmacology, potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity. A highly potent drug evokes a larger response at low concentrations, while a drug of lower potency evokes a small response at low concentrations...
or the nature of a substance is estimated by studying its effects on living matter.
Use
Bioassays are procedures that can determine the concentration of purity or biological activity of a substance such as vitamin, hormone, and plant growth factor. While measuring the effect on an organism, tissue cells, enzymes or the receptor is preparing to be compared to a standard preparation. 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 abnormal development or deformityDeformity
A deformity, dysmorphism, or dysmorphic feature is a major difference in the shape of body part or organ compared to the average shape of that part.Deformity may arise from numerous causes:*A Genetic mutation*Damage to the fetus or uterus...
. An example of a qualitative bioassay includes Arnold Adolph Berthold
Arnold Adolph Berthold
Arnold Adolph Berthold or Arnold Adolf Berthold was a German physiologist and zoologist. He studied medicine in Göttingen in 1819 and wrote his thesis under the direction of Johann Friedrich Blumenbach . Berthold became a private lecturer in 1825 and began to teach physiology at the University of...
's famous experiment on castrated chickens. This analysis found that by removing the testes 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
Biostatistics
Biostatistics is the application of statistics to a wide range of topics in biology...
.
Definition
"The determination of the relative strength of a substance (as a drug) by comparing its effect on a test organism with that of a standard preparation."Purpose
- measurement of the pharmacologicalPharmacologyPharmacology is the branch of medicine and biology concerned with the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function...
activity of new or chemically undefined substances - investigation of the function of endogenous mediatorEndogenous mediatorEndogenous mediators are intracellular proteins that enhance and activate the functions of other proteins. This term is commonly used in molecular biology and cell biology to describe a specific protein complex that acts in transcription as a coactivator...
s - determination of the side-effect profileAdverse effect (medicine)In medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as surgery.An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. If it results from an unsuitable or incorrect dosage or...
, including the degree of drug toxicity - measurement of the concentration of known substances (alternatives to the use of whole animals have made this use obsolete)
- assessing the amount of pollutants being released by a particular source, such as wastewaterWastewaterWastewater is any water that has been adversely affected in quality by anthropogenic influence. It comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations...
or urbanUrban areaAn urban area is characterized by higher population density and vast human features in comparison to areas surrounding it. Urban areas may be cities, towns or conurbations, but the term is not commonly extended to rural settlements such as villages and hamlets.Urban areas are created and further...
runoffSurface runoffSurface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
.
Quantal
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
Effective dose
Effective dose may refer to:*Effective dose the dose of pharmacologic agent which will have a therapeutic effect in some fraction of the population receiving the drug...
(ED50) or median lethal dose (LD50)
Graded
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:
- the precision of the assay required
- the quantity of the sample substance available
- the availability of the experimental animals.
Techniques
- Matching Bioassay
- Interpolation Method
- Bracketing Method
- 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 from of DRC.
Environmental bioassays
Environmental bioassays are generally a broad-range survey of toxicityToxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
. A toxicity identification evaluation is conducted to determine what the relevant toxicant
Toxicant
A toxicant is a chemical compound that has an effect on organisms.A distinction can be drawn between "toxic" and toxin, with the latter being a subcategory of the former....
s 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 radioimmunoassay
Radioimmunoassay
Radioimmunoassay is a very sensitive in vitro assay technique used to measure concentrations of antigens by use of antibodies...
s. See bioindicator
Bioindicator
Biological indicators are species used to monitor the health of an environment or ecosystem. They are any biological species or group of species whose function, population, or status can be used to determine ecosystem or environmental integrity. An example of such a group are the copepods and other...
.
Water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
control requirements in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
require some industrial dischargers and municipal sewage treatment
Sewage treatment
Sewage treatment, or domestic wastewater treatment, is the process of removing contaminants from wastewater and household sewage, both runoff and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants...
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.
See also
- Dilution assayDilution assayThe term dilution assay is generally used to designate a special type of bioassay in which one or more preparations are administered to experimental units at different dose levels inducing a measurable biological response. The dose levels are prepared by dilution in a diluent that is inert in...
- Drug discoveryDrug discoveryIn the fields of medicine, biotechnology and pharmacology, drug discovery is the process by which drugs are discovered or designed.In the past most drugs have been discovered either by identifying the active ingredient from traditional remedies or by serendipitous discovery...
- PharmacodynamicsPharmacodynamicsPharmacodynamics is the study of the biochemical and physiological effects of drugs on the body or on microorganisms or parasites within or on the body and the mechanisms of drug action and the relationship between drug concentration and effect...
- PharmacokineticsPharmacokineticsPharmacokinetics, sometimes abbreviated as PK, is a branch of pharmacology dedicated to the determination of the fate of substances administered externally to a living organism...
- Water qualityWater qualityWater quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...
External links
- Whole Effluent Toxicity Basics (PowerPoint file) - New Jersey Department of Environmental Protection