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Biological Assay definition: A method of measuring the effects of a biologically active substance using an intermediate in vivo or in vitro tissue or cell model under controlled conditions. It includes virulence studies in animal fetuses in utero, mouse convulsion bioassay of insulin, quantitation of tumor-initiator systems in mouse skin, calculation of potentiating effects of a hormonal factor in an isolated strip of contracting stomach muscle, etc.
bioassay definition: a method of measuring the effects of a biologically active substance using an intermediate in vivo or in vitro tissue or cell model under controlled conditions.
Bioassay definition: A laboratory test or analysis of the biological activity of a substance performed by studying its effect on an organism or in a test tube under controlled conditions.
Bioassay definition: Bioassay
Colony Count, Microbial definition: Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. Each colony (i.e., microbial colony-forming unit) represents the progeny of a single cell in the original inoculum. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.
Colony-Forming Units Assay definition: A cytologic technique for measuring the functional capacity of stem cells by assaying their activity.
Complement Hemolytic Activity Assay definition: A screening assay for circulating COMPLEMENT PROTEINS. Diluted SERUM samples are added to antibody-coated ERYTHROCYTES and the percentage of cell lysis is measured. The values are expressed by the so called CH50, in HEMOLYTIC COMPLEMENT units per milliliter, which is the dilution of serum required to lyse 50 percent of the erythrocytes in the assay.
Complement Hemolytic Activity Assay definition: A screening assay for circulating complement proteins in which diluted serum samples are added to antibody-coated erythrocytes and the percentage of cell lysis is measured. The values are expressed in hemolytic complement units per milliliter (CH50), the dilution of serum required to lyse 50 percent of the erythrocytes in the assay.
Drug Screening Assays, Antitumor definition: Methods of investigating the effectiveness of anticancer cytotoxic drugs and biologic inhibitors. These include in vitro cell-kill models and cytostatic dye exclusion tests as well as in vivo measurement of tumor growth parameters in laboratory animals.
Enzyme-Linked Immunosorbent Assay definition: An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed.
enzyme linked immunosorbent assay definition: immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase; while either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye; many variations of the method have been developed.
ELISA definition: A highly sensitive technique for detecting and measuring antigens or antibodies in a solution; the solution is run over a surface to which immobilized antibodies specific to the substance have been attached, and if the substance is present, it will bind to the antibody layer, and its presence is verified and visualized with an application of antibodies that have been tagged in some way. (BioTech Life Science Dictionary)
ELISA definition: ELISA
Fluoroimmunoassay definition: The use of fluorescence spectrometry to obtain quantitative results for the FLUORESCENT ANTIBODY TECHNIQUE. One advantage over the other methods (e.g., radioimmunoassay) is its extreme sensitivity, with a detection limit on the order of tenths of microgram/liter.
Immunoradiometric Assay definition: Form of radioimmunoassay in which excess specific labeled antibody is added directly to the test antigen being measured.
Immunoradiometric assay (IRMA) definition: Immunoassay, Immunoradiometric Assay
Cell Migration Assays, Leukocyte definition: Assays that measure the rate of migration of LEUKOCYTES. They may involve a variety of techniques such as measuring the movement of leukocytes through substrates such as AGAROSE gels or the rate of exit of cells from a glass capillary.
Micronucleus Tests definition: Induction and quantitative measurement of chromosomal damage leading to the formation of micronuclei (MICRONUCLEI, CHROMOSOME-DEFECTIVE) in cells which have been exposed to genotoxic agents or IONIZING RADIATION.
Plaque Assay definition: Method for measuring viral infectivity and multiplication in cultured cells. Clear lysed areas or plaques develop as the viral particles are released from the infected cells during incubation. With some viruses, the cells are killed by a cytopathic effect; with others, the infected cells are not killed but can be detected by their hemadsorptive ability. Sometimes the plaque cells contain viral antigens which can be measured by immunofluorescence.
plaque assay definition: method for measuring viral infectivity and multiplication in cultured cells; clear lysed areas or plaques develop as the viral particles are released from the infected cells during incubation; with some viruses, the cells are killed by a cytopathic effect; with others, the infected cells are not killed but can be detected by their hemadsorptive ability; sometimes the plaque cells contain viral antigens which can be measured by immunofluorescence.
Radioallergosorbent Test definition: An in vitro allergen radioimmunoassay in which allergens are coupled to an immunosorbent. The coupled allergens bind the IgE in the sera of patients which in turn binds radioisotope-labeled anti-IMMUNOGLOBULIN E antibodies.
Radioallergosorbent Test definition: A type of blood test used to test for allergies.
Radioimmunoprecipitation Assay definition: Sensitive assay using radiolabeled ANTIGENS to detect specific ANTIBODIES in SERUM. The antigens are allowed to react with the serum and then precipitated using a special reagent such as PROTEIN A sepharose beads. The bound radiolabeled immunoprecipitate is then commonly analyzed by gel electrophoresis. Radioimmunoprecipitation assay (RIPA) is often used as a confirmatory test for diagnosing the presence of HIV ANTIBODIES.
Radioligand Assay definition: Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).
Subrenal Capsule Assay definition: In vivo method of screening investigative anticancer drugs and biologic response modifiers for individual cancer patients. Fresh tumor tissue is implanted under the kidney capsule of immunocompetent mice or rats; gross and histological assessments follow several days after tumor treatment in situ.
Chemiluminescent Measurements definition: Measurement of light resulting from PHYSICAL CHEMILUMINESCENCE such as from LUMINESCENT PROTEINS and LUMINESCENT AGENTS.
Fluorescent Antibody Technique, Indirect definition: A form of fluorescent antibody technique commonly used to detect serum antibodies and immune complexes in tissues and microorganisms in specimens from patients with infectious diseases. The technique involves formation of an antigen-antibody complex which is labeled with fluorescein-conjugated anti-immunoglobulin antibody. (From Bennington, Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)
Fluorescent Antibody Technique, Direct definition: A form of fluorescent antibody technique utilizing a fluorochrome conjugated to an antibody, which is added directly to a tissue or cell suspension for the detection of a specific antigen. (Bennington, Saunders Dictionary & Encyclopedia of Laboratory Medicine and Technology, 1984)
Comet Assay definition: A genotoxicological technique for measuring DNA damage in an individual cell using single-cell gel electrophoresis. Cell DNA fragments assume a "comet with tail" formation on electrophoresis and are detected with an image analysis system. Alkaline assay conditions facilitate sensitive detection of single-strand damage.
Two-Hybrid System Techniques definition: Screening techniques first developed in yeast to identify genes encoding interacting proteins. Variations are used to evaluate interplay between proteins and other molecules. Two-hybrid techniques refer to analysis for protein-protein interactions, one-hybrid for DNA-protein interactions, three-hybrid interactions for RNA-protein interactions or ligand-based interactions. Reverse n-hybrid techniques refer to analysis for mutations or other small molecules that dissociate known interactions.
Branched DNA Signal Amplification Assay definition: A molecular probe technique that utilizes branched DNA (bDNA) as a means to amplify the hybridization signal. One end of the bDNA molecule is designed to bind a specific target, while the other end of the bDNA molecule contains many branches of DNA that are designed to bind a probe used for signal detection.
Nuclease Protection Assays definition: Techniques for measuring specific nucleic acid interaction with another nucleic acid or with a protein by digestion of the non-interacting nucleic acid by various nucleases. After all non-interacting regions are eliminated by nuclease digestion, the protected nucleic acid that remains is analyzed. DNA FOOTPRINTING utilizes this technique to analyze the DNA contact sites of DNA-BINDING PROTEINS.
Xenograft Model Antitumor Assays definition: In vivo methods of screening investigative anticancer drugs, biologic response modifiers or radiotherapies. Human tumor tissue or cells are transplanted into mice or rats followed by tumor treatment regimens. A variety of outcomes are monitored to assess antitumor effectiveness.
Electrophoretic Mobility Shift Assay definition: An electrophoretic technique for assaying the binding of one compound to another. Typically one compound is labeled to follow its mobility during electrophoresis. If the labeled compound is bound by the other compound, then the mobility of the labeled compound through the electrophoretic medium will be retarded.
Electrophoretic Mobility Shift Assay definition: A molecular biology technique used to detect the interaction of a DNA binding protein with its cognate binding sequence. Labeled DNAs were reacted with crude cell extracts and the complexes are run through a non-denaturing polyacrylamide gel. The migration of the labeled DNA through the gel will be slower by being bound. This shift in electrophoretic mobility indicates functional binding between the protein and the DNA.
Protein Array Analysis definition: Ligand-binding assays that measure protein-protein, protein-small molecule, or protein-nucleic acid interactions using a very large set of capturing molecules, i.e., those attached separately on a solid support, to measure the presence or interaction of target molecules in the sample.
Luminescent Measurements definition: Techniques using light resulting from PHYSICAL LUMINESCENCE emitted by LUMINESCENT PROTEINS and LUMINESCENT AGENTS.
Cell Migration Assays definition: Specific assays that measure the migration of cells. They are commonly used to measure the migration of immune cells in response to stimuli and the inhibition of immune cell migration by immunosuppressive factors.
Migration Assay definition: An in vitro assay in which cultured cells are monitored and analyzed for their ability to move into an acellular area of a culture material.
Run-On Assays definition: A method to determine the constellation of sequences being actively transcribed at a given moment. Cell nuclei are harvested, and then supplied with a pulse of radioactive nucleotides. Transcription is allowed to proceed to an end, but additional initiations are inhibited. RNAs are then extracted and separated by gel electrophoresis.
Cell Migration Assays, Macrophage definition: Assays that measure the rate of migration of MACROPHAGES. They may involve the use hollow plastic chamber, sealed at one end with a porous membrane and suspended over a larger well which may contain CHEMOTACTIC FACTORS. The migration of cell through the pores to the other side of the membrane is measured.
yeast two hybrid system definition: two hybrid proteins interact to transcriptionally activate a reporter gene in vivo.
Enzyme Assays definition: Methods used to measure the relative activity of a specific enzyme or its concentration in solution. Typically an enzyme substrate is added to a buffer solution containing enzyme and the rate of conversion of substrate to product is measured under controlled conditions. Many classical enzymatic assay methods involve the use of synthetic colorimetric substrates and measuring the reaction rates using a spectrophotometer.
Indirect Enzyme Assays definition: Sensitive detection methods using enzymes to indirectly measure substances that would normally be difficult to quantitate.