Assays toxicity determinations

Some Chemical Considerations Relevant to the Mouse Bioassay. Net toxicity, determined by mouse bioassay, has served as a traditional measure of toxin quantity and, despite the development of HPLC and other detection methods for the saxi-toxins, continues to be used. In this assay, as in most others, the molar specific potencies of the various saxitoxins differ, thus, net toxicity of a toxin sample with an undefined mixture of the saxitoxins can provide only a rough approximation of the net molar concentration. Still, to the extent that limits can be placed on variation in toxin composition, the mouse assay can in principle provide useful data on trends in net toxin concentration. However, the somewhat protean chemistry of the saxitoxins makes it difficult to define conditions under which the composition of a mixture of toxins will remain constant thus, attaining a reproducible level of mouse bioassay toxicity is difficult. It is therefore useful to review briefly some of the chemical factors that should be considered when employing the mouse bioassay for the saxitoxins or when interpreting results. Similar concepts will apply to other assays. 

Argese, E., C. Bettiol, A.V. Ghirardini, M. Fasolo, G. Giurin, and P.F. Ghetti. 1998. Comparison of in vitro submitochondrial particle and Microtox assays for determining the toxicity of organotin compounds. Environ. Toxicol. Chem. 17 1005-1012. 

Preference is obviously for a simple chemical assay for PSP. Unfortunately the more specific the chemical test, the narrower is the window of compounds it can assay. The Paralytic Shellfish Poison is not just Saxitoxin (STX) as originally believed, but is a mixture of compounds closely related to STX Q) and the mix varies widely with location and with time ( ). It would seem, therefore that a chemical assay should determine at least the ratios of the several compounds, and that the relative toxicity of each of the compounds must be known. An effective assay must evaluate the actual biological toxicity of the shellfish being tested. For the chemical assay this requires the summated toxicity of all the... 

Most experiments requiring assessment of growth or toxicity involve comparison of experimental treated cultures with control untreated cultures. If such comparisons are to give an accurate measurement of growth stimulation or inhibition, then control and experimental wells should still be in exponential growth phase at the time of assay endpoint determination. Also, the cell number in all wells should be in the linear position of the graph of optical density versus cell number per well. To ensure that these conditions apply, each assay method should be characterized for ... 

Toxicity. Initial assessment of the toxicity of these aryl dye molecules using a modification of the agar disk diffusion antibiotic sensitivity was inconclusive because of the limited diffusion of the compound and its intense binding to the cellulose disks. Liquid cultures supplemented with 1 mg of aryl dye dissolved in 1 ml of DMF were used to assay toxicity. Comparison of the growth of Candida lipolvtica (GSU 37-1) and Candida maltosa (GSU R-42) was made by observing the optical density at 595 nm in a Turner spectrophotometer model 380. Determination of the absorption by compound was made for uninoculated GYNB. The increase in absorbance in cultures with and without analogue was compared. 

Bulich, A.A., Greene, M.W., and Isenberg, D.L., Reliability of the Bacterial Luminescence Assay for Determination of the Toxicity of Pure Compounds and Complex Effluents , in Aquatic Toxicology and Hazard Assessment 4th Conference, Branson, D.R. and Dickson, K.L. (Eds.), ASTM STP 737, American Society for Testing and Materials, Philadelphia, 1988, pp. 338-347. 

Part 2 [124] Guidance for bio assays to determine the acute inhalation toxicity of the effluents (basic principles, criteria, and methodology)... 

Tombelli S, Mascini M, Sacco C, Turner APF (2000) A DNA piezoelectric biosensor assay coupled with a polymerase chain reaction for bacterial toxicity determination in environmental samples. Anal Chim Acta 418(1) 1-9... 

Biological activity may be evaluated using in vitro assays to determine which effects of the product may be related to chnical activity. The use of cell lines and/or primary cell cultures can be useful to examine the direct effects on cellular phenotype and proliferation. Due to the species specificity of many biotechnology-derived pharmaceuticals, it is important to select relevant animal species for toxicity testing. In vitro cell Hnes derived from mammalian cells can be used to predict specific aspects of in vivo activity and to... 

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