Bioassay measurements

Indirect measurement (bioassay) Mouse bioassay Mouse bioassay Neuroblastoma assay (Truman et at, 2002) Mouse bioassay Protein-phosphatase inhibition assay (Mountfort et at, 2001) Mouse bioassay Cytotoxicity assay (Flanagan et at, 2001) Mouse bioassay Neuroblastoma assay (Matta et at, 2002)... 

Thind KS. 1987. A comparison of ICRP Publication 30 lung model-based predictions with measured bioassay data for airborne natural uranium dioxide exposure. Health Phys 53 59-66. 

A bioassay is a test designed to measure the effect of a chemical on a test population of organisms. The effect may be a physiological or biochemical parameter, such as growth rate, respiration, or enzyme activity. In the case of drilling fluids, bioassays lethality is the measured effect. 

Mancy, K.H. Allen, H.E. A Controlled Bioassay System for Measuring Toxicity of Heavy Metals. U.S. Environmental Protection Agency Washington D.C., 1977. 

Particular attention is given to the development of new mechanistic biomarker assays and bioassays that can be used as indices of the toxicity of mixtures. These biomarker assays are typically based on toxic mechanisms such as brain acetylcholinesterase inhibition, vitamin K antagonism, thyroxin antagonism, Ah-receptor-mediated toxicity, and interaction with the estrogenic receptor. They can give integrative measures of the toxicity of mixtures of compounds where the components of the mixture share the same mode of action. They can also give evidence of potentiation as well as additive toxicity. 

Matthiessen, P., Sheahan, D., and Harrison, R. et al. (1995). Use of a Gammarus pulex bioassay to measure the effects of transient carbofuran runoff from farmland. Ecotoxicology and Environmental Safety 30, 111-119. 

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. 

Until the recent development of appropriate HPLC techniques capable of detecting pmol amounts (see Flentge et al. 1997) ACh could only be measured chemically by relatively lengthy and expensive procedures (e.g. gas chromotography), which were not always very sensitive, or by bioassays. Although the latter, using muscle preparations that responded to ACh, such as the dorsal muscle of the leech, the rectus abdominus of the frog or certain clam hearts, were reasonably sensitive they were tiresome and not easily mastered. Thus studies on the release and turnover of ACh have not been as easy as for the monoamines. 

NCRP. 1987. Use of bioassay procedures for assessment of internal radionuclide deposition. National Council on Radiation Protection and Measurements. Bethesda, MD. Report No. 87. 

Additional research with Lemna species has indicated that parameters other than direct growth measurements may be more sensitive In this bioassay. Table VII compares growth and chlorophyll content of L. minor as affected by catechln. Final frond number was inhibited by 1000 pM catechln and stimulated at lower concentrations of 50 and 100 pM. Chlorophyll content on a per-frond basis, however, was consistently Inhibited by catechln and was concentration dependent to 100 pM. 

Root elongation bloassay of root exudates. Five ml aliquots of the root exudates were pipetted onto three layers of Anchor1 germination paper In a 10 by 10 by 1.5 cm plastic petri dish. Twenty five radish or tomato seeds were placed in a 5x5 array in each petri dish. Radish seeds were incubated at 20C for 96 hours tomato seeds were incubated at 20C for 168 hours, before the root length was measured. Experimental design was a completely randomized design with three replications (dishes) per treatment per bioassay seed species. The bioassay was repeated each week for 23 weeks. 

Bioassay of Extracts. Extracts tested for the presence of cyclohexi-mide were also bioassayed for phytotoxicity. The extracts were redis-sOlved in acetone, and 0.2 mg in 2 pi was applied to 6-cm-dia disks of filter paper. The extract was distributed on the paper with 0.2 ml of methanol. The disks were dried with warm air, placed in 1.5 x 6 cm petri dishes, and moistened with 1.5 ml distilled water. Ten cress seeds were placed on the paper, and after incubation for 3 d at 28 C radicle length of the seedlings was measured. 

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