Biological Assay, bioassay

Biological assay (bioassay) is the process by which the activity of a substance (identified or unidentified) is measured on living material e.g. contraction of bronchial, uterine or vascular muscle. It is used only when chemical or physical methods are not practicable as in the case of a mixture of active substances, or of an incompletely purified preparation, or where no chemical method has been developed. The activity of a preparation is expressed relative to that of a standard preparation of the same substance. Biological standardisation is a specialised form of bioassay. It involves matching of material of unknown potency with an International or National Standard with the objective of providing a preparation for use in therapeutics and research. The results are expressed as units of a substance rather than its weight, e.g. insulin, vaccines. 

A sensitive biological assay method for the assay of acetylcholine was used by Vapaatalo et al. [58]. Superfused hamster stomach strip was used in the bioassay of acetylcholine. The preparation proved very stable and had no spontaneous movement, and the sensitivity to acetylcholine was in the range of 10-12 g/mL. Satyanarayana et al. reported the use of a bioassay method for the analysis of acetylcholine using the arterial blood pressure of cats [59]. 

Di, L. and Kerns, E.H. 2006. Biological assay challenges from compound solubility strategies for bioassay optimization. Drug Disc. Today 11, 446M-51. 

Bioassay A biological assay, or bioassay, is an analytical procedure capable of measuring the biologic activity of a substance based on a specific functional, biologic... 

Immunoassays are physical rather than biological assays they possess the specificity and sensitivity of bioassays with the speed... 

The enhanced fluorescence detection capability of ZnO NR platforms is further assessed in relatively simple biological assays involving pure DNA and proteins. Unlike the previously described tests involving single layer adsorption of biomolecules, biological assays discussed from here on pertain to interactions between multilayered biomolecules. The following sections describe the results of fluorescence enhancement effect observed in these relatively simple but multilayered bioassays on ZnO NRs. 

Biological Assay. Prior to bioassay, the hot diet was cooled to 60°C, L-ascorbic acid or a related compound was added, and the mixture was thoroughly blended. Labile derivatives were applied to the surface of the gelled diet at room temperature. Neonate larvae were used in all tests and the growth of larvae on the control diet was compared with that of larvae on test diets. At 1-4-d intervals, up to 40 d, the mean weight of ten to twenty animals was determined. Fecal matter was removed at each observation. Test compounds were obtained or prepared as described previously (5). 

Principles of Cytokine Assays Bioassay and immunoassay are the analytical techniques of choice to measure cytokines. However, newer instrumental techniques are also beginning to be used to measure cytokines and CKs. These techniques are used to quantify their (1) concentration and activity in biological fluids, (2) production by whole blood cells,(3) concentration of receptors, and (4) intracellular levels. 

Several animal species have been used in the biological assay of calcium-lowering hormones. For reasons of size, the rat is most commonly used, although mice have been claimed to be more responsive to human thyrocalcitonin preparations (S2). For studies of the course of thyro-calcitonin action in which serial blood samples were required, both pigs (C5) and goats (F4) have been used. For assessment of the potency of hoimone preparations, bioassay in rats is in general satisfactory. 

In-house working reference material A material prepared similarly to the primary reference material that is established solely to assess and control subsequent lots for the individual attribute in question. It is always calibrated against the in-house primary reference material. Potency The measure of the biological activity using a suitably quantitative biological assay (also called potency assay or bioassay), based on the attribute of the product, which is linked to the relevant biological properties. 

The errors and uncertainties of bioassay are becoming a more serious obstacle to progress as work extends (S2). Until biological assay can be dispensed with, it is therefore necessary to refine it as much as possible. A... 

Biological assays are often noisy and laborious. With careful application of experimental design, cell culture bioassays can be made quite accurate and precise. The core information needed for validation can come from two experiments. One experiment studies accuracy and precision followed by a variance component analysis and a summary table that describes the expected performance of the system at various levels of replication. A second experiment uses a minimal fractional factorial design to study robustness, followed by a comparison of confidence intervals on effect sizes with a previously established indifference zone. 

To estimate water quality, bioluminescent biosensors have been devised and successfully used. They are characterized by rapidity and simplicity of use, high sensitivity, and accuracy. The Collection of Luminous Bacteria IBSO (http //www.bdt.org.brA3dt/msdn/ibso) is being used to develop bioassays for monitoring the environment, using lyophilized luminous bacteria and the luminescent system isolated from them. Bioluminescent assays have an advantage over other biological assays luminescence is easy to measure, the method is rapid, and the measurements can be automated. 

Since almost all peptides were identified initially on the basis of bioassays, their names reflect these biologically assayed junctions (e.g., thyrotropin-releasing hormone and vasoactive intestinal polypeptide). A parsimonious view is that each peptide has unique messenger roles at the cellular level that are used repeatedly in functionally similar pathways within functionally distinct systems. 

When sufficient correlation studies between physicochemical or in vitro bioassays and in vivo biological assays have been carried out showing that estimates based on in vitro tests are sufficiently precise and accurate, the requirement for an in vivo bioassay may be relaxed. 

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