Analytical bioassay

Dual Analytical-Bioassay. Many of the reports of polymer applications include dual analytical and bioassay features because these integrated studies help to focus attention on those compound classes and individual compounds that have the highest biological activity. These dual-purpose reports were counted in both categories to arrive at an application distribution of 85 analytical and 15 bioassay. The results given in these two report groups are discussed separately in the following sections. 

One unit of bacitracin USP is defined as the activity given by 26 micrograms of the dried FDA master standard. The USP requirement for commercial bacitracin is a potency of at least 40 units per milligram in a bioassay with Micrococcusflavus or Sarcina lutea. Pure bacitracin A has a potency of about 100 units per milligram. Standards for animal feed grades of bacitracin are available (71,81,82) as are analytical methods (67). 

Not all cyanobacterial blooms and scums contain detectable levels of toxins. Indeed, the incidence of toxicity detection by mouse bioassay, and toxin detection by HPLC among environmental samples, ranges from about 40% to However, in view of this high occurrence, it is the policy of regulatory authorities and water supply operators in some countries to assume that blooms of cyanobacteria are toxic until tested and found to be otherwise. In the absence of available analytical facilities or expertise or for logistical reasons, this precautionary principle should be regarded as sensible and prudent. 

So far, we have reviewed the various ways in which complex dose-response curves in intact-tissue bioassays can be the result, the pharmacological resultant, of two or more interacting activities. Now, if all that these bioassays achieved was to blur and obscure the underlying activities, they would have to give way to the newer, analytically simpler assays based on chemistry and biochemistry. However, the beauty of intact-tissue bioassays is that they are analytically tractable by using families of dose-response curves and appropriate mathematical models, the complexity of intact hormone-receptor systems can, indeed, be interpreted. Bioassay allows them to be studied as systems in ways denied to simple biochemical assays. 

In recent decades, the development of chemical, biochemical, and biological techniques has allowed the creation of analytical tools which can be used to facilitate the identification of the mechanisms involved in neoplastic transformation. Animal models remain, however, the most widely used approach of investigation. Cancer bioassays are usually conducted in rodents (rats and mice) and the experimental protocol takes 18-24 months and it is followed by extensive histopathological and statistical analysis. The procedure is time and... 

Osaka, T., Matsunaga, T., Nakanishi, T., Arakaki, A., Niwa, D. and Iida, H. (2006) Synthesis of magnetic nanopartides and their application to bioassays. Analytical and Bioanalytical Chemistry, 384 (3), 593-600. 

Horwitz claims that irrespective of the complexity found within various analytical methods the limits of analytical variability can be expressed or summarized by plotting the calculated mean coefficient of variation (CV), expressed as powers of two [ordinate], against the analyte level measured, expressed as powers of 10 [abscissa]. In an analysis of 150 independent Association of Official Analytical Chemists (AOAC) interlaboratory collaborative studies covering numerous methods, such as chromatography, atomic absorption, molecular absorption spectroscopy, spectrophotometry, and bioassay, it appears that the relationship describing the CV of an analytical method and the absolute analyte concentration is independent of the analyte type or the method used for detection. 

Brugmann [784] discussed different approaches to trace metal speciation (bioassays, computer modelling, analytical methods). The electrochemical techniques include conventional polarography, ASV, and potentiometry. ASV diagnosis of seawater was useful for investigating the properties of metal complexes in seawater. Differences in the lead and copper values yielded for Baltic seawater by methods based on differential pulse ASV or AAS are discussed with respect to speciation. 

Only one analytical method has been widely applied to the measurement of vitamins in seawater. The method, bioassay, is not really within the realm of the analytical chemist, since it requires the maintenance of cultures of test organisms. The tests also usually require a minimum of four days before results are available. 

There are many uncertainties in the use of bioassay methods, not the least of these being the genetic stability of the assay organisms. Stock cultures cannot be treated like chemical reagents, to be put back on the shelf and forgotten between analytical runs. This is an area of analysis best left to the microbiologists if the information is absolutely necessary, the maintenance of cultures and the actual assay should not be left solely in the hands analytical chemists. 

Additional examples of the analytical applications of BL bacterial bioassays are listed in Table 6. 

During the 1970 s and early 1980 s a large number of test methods were developed to measure the toxic potency of the smoke produced from burning materials. The ones most widely used are in refs. 29-32. These tests differ in several respects the conditions under which the material is burnt, the characteristics of the air flow (i.e. static or dynamic), the type of method used to evaluate smoke toxicity (i.e. analytical or bioassay), the animal model used for bioassay tests, and the end point determined. As a consequence of all these differences the tests result in a tremendous variation of ranking for the smoke of various materials. A case in point was made in a study of the toxic potency of 14 materials by two methods [33]. It showed (Table I) that the material ranked most toxic by one of the protocols used was ranked least toxic by the other protocol Although neither of these protocols is in common use in the late 1980 s, it illustrates some of the shortcomings associated with small scale toxic potency of smoke tests. 

A prerequisite to pharmacokinetic/pharmacodynamic studies is the availability of a sufficiently selective and sensitive assay. The assay must be capable of detecting and accurately quantifying the therapeutic protein in the presence of a complex soup of contaminant molecules characteristic of tissue extracts/body fluids. As described in Chapter 7, specific proteins are usually detected and quantified either via immunoassay or bioassay. Additional analytical approaches occasionally used include liquid chromatography (e.g. HPLC) or the use of radioactively labelled protein. 

Tumanov, A. and Krestyaninov, P. 2002. Current status and prospects of bioassay. Journal of Analytical Chemistry 57, 372-387. 

For standardised instrumental analytical methods, i.e. biomarkers, biosensors and bioassays, there are well-established standard protocols on the national level, e.g. under Association Francaise de Normalisation (AFNOR), British Standard Institute (BSI), DIN (German Organisation for Standardisation), etc., and all those standards are formed by ISO-Working Groups and by validation studies into ISO - and CEN - Standards. Normal accredited and well-qualified laboratories should be able to perform the monitoring. 

The protocols of analytical methods and bioassays include the sampling and preparation steps of the test matrix before the test procedures. The sampling should be conducted in accordance with ISO 5667-16. There are already available harmonised protocols according to Hansen et al. [49]. The statistics of the ecotoxicity data should be conducted in accordance with ISO/CD 20281. 

Abstract A relatively small number of mammalian pheromones has been identified, in contrast to a plethora of known insect pheromones, but two remarkable Asian elephant/insect pheromonal linkages have been elucidated, namely, (Z)-7-dodecen-1-yl acetate and frontalin. In addition, behavioral bioassays have demonstrated the presence of a chemical signal in the urine of female African elephants around the time of ovulation. Our search for possible ovulatory pheromones in the headspace over female African elephant urine has revealed for the first time the presence of a number of known insect pheromones. This search has been facilitated by the use of a powerful new analytical technique, automated solid phase dynamic extraction (SPDE)/GC-MS, as well as by novel macros for enhanced and rapid comparison of multiple mass spectral data files from Agilent ChemStation . This chapter will focus on our methodologies and results, as well as on a comparison of SPDE and the more established techniques of solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE). 

Luoma, S. N. (1995). Prediction of metal toxicity in nature from bioassays. In Metal Speciation and Bioavailability in Aquatic Systems, eds. Tessier, A. and Turner, D. R., Vol. 3, IUPAC Series on Analytical and Physical Chemistry of Environmental Systems. Series eds. Buffle J. and van Leeuwen H. P., John Wiley Sons, Ltd, Chichester, pp. 609-659. 

At one end of the analytical spectrum is the bioassay, which can demonstrate what biological activity the biopharmaceutical molecule may possess, regardless of molecular structure. At the other end are structural methods that elucidate the molecular structure of the molecule, regardless of biological activity. Somewhere in the middle of the spectrum is the ELISA. 

---