Description
Bioassay- commonly used shorthand for biological assay
Bioassay
Bioassay (commonly used shorthand for biological assay), 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 pollutants. Both are procedures by which the potency (pharmacology) or the nature of a substance is estimated by studying its effects on living matter. "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." 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 precipitation. 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 deformity. 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. Purpose 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.
Types Bioassays are of two types:
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 dose not die. Here also no intermediate response is possible. This is also known as the "all or none" response assay. The quantal method though not accurate 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 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 1. 2. 3. 4. Matching Bioassay Interpolation Method Bracketing Method Multiple Point Bioassay (i.e.-Three-point, Four-point and Six Point 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. Bioassays Malaria Malaria is among the most life-threatening and widespread diseases in the world, causing 250-300 million cases and about 2 million deaths annually. The disease is caused by four Plasmodium species (i.e. P. falciparum, P. vivax, P. ovale and P. malariae) which are transmitted to humans during the bite of the female anopheles mosquito. The methodology to test our extract and pure compounds is efficient and accurate for the detection of anti-malarial agents based upon the intercalation of the fluorochrome PicoGreen® into Plasmodium DNA. PicoGreen® is an ultra sensitive fluorescent nucleic acid stain for measuring double-stranded DNA (dsDNA) in solution and enables the detection of quantities as low as 25 pg/mL of dsDNA with a moderately priced spectrofluorometer using fluorescein excitation and emission wavelengths. This non-radioactive DNA-based assay, using PicoGreen® with 485 nm excitation and 528 nm detection, was developed in Dr. Ortega-Barria's laboratory to measure the growth of Plasmodium falciparum (W2 strain), in erythrocytes. Parasite growth is measured after cells have been incubated with extracts at 50, 10, or 2 microg mL-1 for two days. Chloroquine is used as a positive control. This methodology has several advantages over the radioactive bioassay used commonly. -It is as sensitive as the radioactive method -It is less costly than the radioactive method -Does not require special waste disposal
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Bioassay for biological control of a plant pathogen
Begonias were grown in the greenhouse and inoculated with Botrytis cinerea under conditions optimal for the development of disease. Treatments differing in their efficacy are shown, from left to right: untreated (Un), CaCl2, chlorothalonil (Fung), and the biocontrol agent Trichoderma hamatum T382 inoculated into the potting mix (T382).
•
Bioassay for employing Cancer cell lines
Environmental bioassays 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 radioimmunoassay. 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. The classic historical example of a bioassay was the use of canaries by miners in past centuries. Because canaries are more sensitive than humans to noxious gases like methane, they reacted quickly to even small amounts of the gas. This would give the miners time to escape.
Conclusion Today's bioassays are more sophisticated than the canary. The ASTM (formerly known as the American Society for the Testing of Materials) has catalogued over 70 different bioassays. These are used to analyze soil, freshwater, and the sediment at the bottom of watercourses like streams and rivers, saltwater, and air. Plants can be used as indicators of the presence of toxic compounds in the soil. In this bioassay, seeds or the mature plant is introduced into the soil of a site that is suspected of being contaminated. Failure of the seeds to germinate, or failure of the mature plant to thrive, can be evidence of contamination. If the assay is done in a controlled manner with the use of standards to provide reference points, then the geographical area of contamination can be determined. Some species of plants can also be used to accomplish bioassays in the water. More commonly, however, the test organisms are single-celled organisms such as algae, water fleas (in particular a species called Daphnia magna or fish (in particular the fathead minnow).
doc_990008723.doc
Bioassay- commonly used shorthand for biological assay
Bioassay
Bioassay (commonly used shorthand for biological assay), 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 pollutants. Both are procedures by which the potency (pharmacology) or the nature of a substance is estimated by studying its effects on living matter. "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." 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 precipitation. 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 deformity. 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. Purpose 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.
Types Bioassays are of two types:
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 dose not die. Here also no intermediate response is possible. This is also known as the "all or none" response assay. The quantal method though not accurate 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 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 1. 2. 3. 4. Matching Bioassay Interpolation Method Bracketing Method Multiple Point Bioassay (i.e.-Three-point, Four-point and Six Point 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. Bioassays Malaria Malaria is among the most life-threatening and widespread diseases in the world, causing 250-300 million cases and about 2 million deaths annually. The disease is caused by four Plasmodium species (i.e. P. falciparum, P. vivax, P. ovale and P. malariae) which are transmitted to humans during the bite of the female anopheles mosquito. The methodology to test our extract and pure compounds is efficient and accurate for the detection of anti-malarial agents based upon the intercalation of the fluorochrome PicoGreen® into Plasmodium DNA. PicoGreen® is an ultra sensitive fluorescent nucleic acid stain for measuring double-stranded DNA (dsDNA) in solution and enables the detection of quantities as low as 25 pg/mL of dsDNA with a moderately priced spectrofluorometer using fluorescein excitation and emission wavelengths. This non-radioactive DNA-based assay, using PicoGreen® with 485 nm excitation and 528 nm detection, was developed in Dr. Ortega-Barria's laboratory to measure the growth of Plasmodium falciparum (W2 strain), in erythrocytes. Parasite growth is measured after cells have been incubated with extracts at 50, 10, or 2 microg mL-1 for two days. Chloroquine is used as a positive control. This methodology has several advantages over the radioactive bioassay used commonly. -It is as sensitive as the radioactive method -It is less costly than the radioactive method -Does not require special waste disposal
•
Bioassay for biological control of a plant pathogen
Begonias were grown in the greenhouse and inoculated with Botrytis cinerea under conditions optimal for the development of disease. Treatments differing in their efficacy are shown, from left to right: untreated (Un), CaCl2, chlorothalonil (Fung), and the biocontrol agent Trichoderma hamatum T382 inoculated into the potting mix (T382).
•
Bioassay for employing Cancer cell lines
Environmental bioassays 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 radioimmunoassay. 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. The classic historical example of a bioassay was the use of canaries by miners in past centuries. Because canaries are more sensitive than humans to noxious gases like methane, they reacted quickly to even small amounts of the gas. This would give the miners time to escape.
Conclusion Today's bioassays are more sophisticated than the canary. The ASTM (formerly known as the American Society for the Testing of Materials) has catalogued over 70 different bioassays. These are used to analyze soil, freshwater, and the sediment at the bottom of watercourses like streams and rivers, saltwater, and air. Plants can be used as indicators of the presence of toxic compounds in the soil. In this bioassay, seeds or the mature plant is introduced into the soil of a site that is suspected of being contaminated. Failure of the seeds to germinate, or failure of the mature plant to thrive, can be evidence of contamination. If the assay is done in a controlled manner with the use of standards to provide reference points, then the geographical area of contamination can be determined. Some species of plants can also be used to accomplish bioassays in the water. More commonly, however, the test organisms are single-celled organisms such as algae, water fleas (in particular a species called Daphnia magna or fish (in particular the fathead minnow).
doc_990008723.doc