Bioassay tests

Other regulations apply in different offshore drilling areas in the United States and around the world. AH have had a profound effect on drilling fluid technology (169,170). Very few instances of water-base muds failing the mysid bioassay test exist in the 1990s. Operators and service companies have eliminated use of the mote toxic additives, reformulated old mud systems, and developed new ones to ensure acceptable environmental performance based on pertinent regulations. 

The mysid shrimp, Mysidopsis bahia, is the test organism for the liquid and suspended particulate phases. This species has been shown to be exceptionally sensitive to toxic substances and is considered to be a representative marine organism for bioassay testing by EPA. An LCj, is determined the suspended particulate phase (SPP) bioassay tests. 

Table 8. Industrial Wastewater Toxicity Bioassay Test Results Concentration in Wastewater ...

Field Applicability Testing (FAT) Workshop. In March 1982, the EPA Office of Research and Development convened a workshop with the specific objectives to (1) assess the state of knowledge on determining the field applicability of laboratory bioassay tests, toxicity studies, microcosm studies, and mathematical chemical exposure models (i.e., the extent to which these methods have been tested/compared with field data), and (2) recommend research objectives and priorities to advance the current level of field testing. Workshop attendees included representatives from EPA research laboratories, universities, and private industry. 

Principle Phytotoxic effects of the aqueous leachate of an allelopathic plant can be tested in vitro bioassays. Test or target plants are placed in contact with 0.5 % aqueous leachate from the allelopathic plant. Germination and radicle growth can be monitored during time-course experiments (i.e. after 24,48 and 72 h of treatment), but in this chapter we will include only the results obtained after 72 h of treatment. 

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. 

The following sections describe several commonly used bioassay tests that have been successfully used in conjunction with SPMDs. However, no attempt was made to cover all of the in vitro assays used for SPMD extracts. 

Neurotoxicity. No clinical signs of central nervous system toxicity or histological alterations of nervous system organs and tissues were observed in rats or mice in the NCI (1978) chronic oral bioassay. Tests for neurotoxicity in animals may be appropriate if there is clinical evidence of neurological dysfunction in general oral or dermal toxicity studies of I 2-diphenylhydrazine. 

Zimpro, Inc. CIBA-GEIGY meeting tough bioassay test. Reactor 1986, June, 13-14. 

Zimpro, Inc. CIBA-GEIGY Meeting Tough Bioassay Test. Reactor, June 1986 13-14. 

FSIS has developed a series of overnight, inexpensive, easy to perform swab bioassay tests for screening tissues, body fluids, or feed extracts for antibiotic residues. The swab tests are used on the farm, in the slaughter plant, or in the laboratory for their designated purpose. Swab test results indicate whether antimicrobial activity is present in the sample at or above allowable levels or absent. Further testing with more sophisticated tests is required to identify and quantify the antibiotics producing the antimicrobial activity. These are usually done in a laboratory as required. 

On the other hand, some pufferfishes which have not been eaten before, are sometimes marketed in Japan. In our mouse bioassay test a high toxicity was detected in the tissues from Tetraodon alboreti-culatus, one of such pufferfishes 2870 MU/g ovary and 31 MU/g liver ( 5). Thus, re-examination seems to be necessary for toxic potency of the pufferfishes landed from Japanese and adjacent waters. 

Dihydropyrenophorin, from Drechslera avenae, is a leaf pathogen of both wild and cultivated oats. It causes reddish brown lesions with a necrotic sunken center. At least one compound isolated from broth cultures of this fungus caused comparable lesions on oats and a variety of other plants at 3.2 x 10" M (15). The phytotoxin was characterized by spectrometric analyses and chemical conversion as (-)-dihydropyrenophorin (Vl), an important di lactone macrolide (15). However, the major product obtained in our extraction procedure used to isolate (-)-dihydropyrenophorin was the diol VII (j 6), which was not active in our bioassay tests. 

Furthermore, many bioassay procedures can be affected synergis-tically or antagonistically by artifacts. In current practice, chemists use various solvents to clean the resin as completely as possible, run a resin blank, and chromatographically analyze the blank sample. Rarely are the artifacts identified. This procedure does not help the biologist who requires a blank that does not show a positive response in the bioassay test of the blank. Biologists usually clean the resin as the chemists do and complete a blank for the bioassay. Artifacts should be identified to assure that the bioassay results are in response to the compounds under study and not the artifacts in combination with the sample. 

Effects on Aquatic Organisms (Refs 31 44). An LD50 of 3.6mg/J2 was found in 96-hr static bioassay tests of RDX on bluegill sunfish (Lepomis macrochirus) at pH 6 and 35mg/G water hardness, and represents the lowest LC50 found for any aquatic species. The chronic and acute levels are very close in aquatic organisms. Thus, the lowest observable chronic effect, decreased length of fathead minnow (Pimphales promelas) fry,occurred at 3.0mg/6 of RDX this effect was not seen at 1.2mg/fi. RDX shows extremely little bioconcn... 

Table 2. Bioassay testing conditions and reference methods for the selected species. 

Figure 2 represented a log-probit plot of the observed inhibition of purified bovine erythrocyte acetylcholinesterase as a function of concentration for several of the transformation products of aminocarb. The observation that these inhibition curves are parallel suggests a similar mechanism of interaction for the various derivatives. The parameter I5f. (the concentration of inhibitor required to achieve 50% inhibition oi the enzyme activity) for each of the inhibitors were calculated and are recorded in Table 1. These values are reported relative to the parent compound aminocarb = 1. Also included in Table 1 are the relative toxicities of several of these products to house crickets (Acheta domesticus). It had been our intention to develop bioassay tests using the target insect itself, the eastern spruce budworm (Choristoneura fumiferana). However, spray tower results were quite variable and it was considered that genetic variability of the stock culture made the production of uniform test batches difficult to achieve. Using the house crickets, an LD q of 130-155 ppm for aminocarb standard was observed over the course of more than 25 bioassays. Also included in Table 1 are observations by Abdel-Wahab and Casida (19) using human plasma or house fly head cholinesterases. 

Assessments of environmental impacts from herbicides are usually done at the single-species level. These assessments use toxicological data from laboratory bioassay tests and estimates of exposure from laboratory or field studies of environmental chemistry. Few tests have assessed the impacts of herbicides on organisms in the field and few, if any, at the ecosystem level. There are two main reasons why there have been so few field or ecosystem tests They are exceedingly difficult and costly, and the current philosophies of risk assessment have evolved from classical toxicology and the federal regulatory framework that covers pharmaceuticals, food additives, and pesticides. 

Metal speciation procedures, which have been verified under controlled laboratory conditions and evaluated by means of bioassays, will require further verification in order to determine their ecological effects. For example, how does the response of the bioassay test species to a toxic metal fraction relate to the toxicity to larger organisms such as fish in the natural environment Bioaccumulation of metals in populations has been very difficult to relate to metal speciation measurements. There is a challenge for analytical chemists to develop metal speciation procedures that are relevant to ecotoxicology (Morrison and Wei, 1991). 

Gart JJ, Chu KC, Tarone RE (1979) Statistical issues in interpretation of chronic bioassay tests for carcinogenicity. J Natl Cancer Inst 62 957-974... 

Searching Prodrug Substances from Natural Resources by Supercritical Carbon Dioxide Extraction and Bioassay Tests... 

Supercritical fluid extraction(SFE) combined with five types of bioassay tests is extensively applied to explore some bioactive substances from thirty types of natural resources available in Korean peninsula. To evaluate comparatively the economic viability of the SFE, organic liquid solvent extraction(LSE) with n-hexane, chloroform and methanol was also performed. To characterize the extracts, GC and HPLC are employed. Also, the column chromatography is used to isolate some target compounds from the total extracts. For all the samples, the optimum SFE condition for each sample which gives maximum yield and cytotoxicity were discussed. 

In summary, we examined extensively the SFE for the alternative replacement of the traditional LSE in pharmaceutical industry. We found that for many sample resources, the SFE is found to be advantageous over the LSE. Furthermore, by cooperating column chromatography with several types of bioassay tests, we demonstrated a sufficient economic feasibility of the implementation of the SFE for the selective separation of the total extracts and subsquently the high-purity prodrug substances from the natural medicinal products. 

Table I. Bioassay Test Results from Extraction Fractions of Alchornea triplinervia...

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