E-screen test

In the E-Screen bioassay, LAS was not effective in promoting cell proliferation (Table 7.3.3). This compound was tested at concentrations of up to 100 pM with no evidence of cellular toxicity. The antiestrogenic effect of this compound was also measured but all samples tested were negative. Because it has been suggested that surfactants of the alkylbenzene sulfonate type are readily degradable and transformed into sulfophenyl carboxylates or SPCs, an important number of SPCs were assayed in the E-Screen test. These SPCs did not induce cell proliferation of MCF7 cells. 

AG and APG were assayed in the E-Screen test for estrogenicity but were ineffective in inducing MCF7 cell proliferation. Table 7.3.3 shows the results of the proliferation test. 

After determination of the amitriptyline concentrations by GC/MS, the sensitivity of the exposm-e screening test was 93.3% and the specificity 100%. Numerous drugs may be screened in the same marmer. Such screening tests offer a large range of applications of considerable interest, including the study of past history of patients admitted to the intensive care unit (ICU) or psychiatry units who are unable (or unwilling) to answer questions. 

Breast cancer cell lines are known to proliferate in response to estrogen stimulation. Charcoal-dextran stripped human serum inhibits the proliferation of MCF-7 breast cancer cells in a dose-dependant fashion. Estrogens overcome this effect. The E-screen test exploits the estrogen-dependant proliferation of MCF-7 cells and has been used previously for the determination of the estrogenic potential of phenol red, estradiol, and tamoxifen among other compounds. Such assays can take 4-7 days. 

In addition to detection of toxicity in samples containing cyanobacteria and/or their toxins (i.e. screening), quantification and identification of the toxins present are necessary on occasions. Physicochemical methods of toxin analysis fulfil both these roles, often requiring a comparison of the test sample with purified... 

In the case of a large-scale development it may be desirable to combine several environmental services for a full environmental impact assessment (ElA). This is the process of examining, in a comprehensive, detailed and systematic manner, the existing environment (natural, built and social) and the development that it is proposed to place within it. By integrating the two, an objective estimate can then be made of the likely effects of the development upon the environment, including benefits and negative impacts. Special techniques may be employed to help identify or quantify these impacts (e.g. the use of interaction matrices, overlays, screening tests, checklists, etc.). 

The application of sacrificial anodes for the protection of structures requires the development of suitable anode materials for the exposure environment. Screening tests enable the rapid selection of materials which show potential as candidates for the given application. These tests may typically use a single parameter (e.g. operating potential at a defined constant current density) as a pass/fail criterion and are normally of short duration (usually hours) with test specimen weights of the order of hundreds of grams. The tests are not intended to simulate field conditions precisely. 

The first aim of a thermal stability screening test (e.g., DSC/DTA) is to obtain data on the potential for exothermic decomposition and on the enthalpy of decomposition (AHd). These data, together with the initial theoretical hazard evaluation, are used in reviewing the energetic properties of the substance (Box 4) and the detonation and deflagration hazards of the substance (Boxes 7 and 8). The screening tests also provide data on the thermal stability of the substance or mixture, on the runaway potential, on the oxidation properties, and to a lesser extent, on the kinetics of the reaction (Box 10). 

AP and brominated AP derivatives were tested in the E-Screen proliferation bioassay in a concentration range of 100 pM to 0.1 mM. 

However, if the gene has been cloned, but the required activity is not produced, then the functional test will fail to pick up the target gene. In this case, if some gene sequence information is available, then it may be possible to test for the presence of DNA with the expected sequence by hybridization with radio-labelled probe DNA or, more usually, by PCR. This sequence-based screening test could pick up positives which have been missed in the initial screen because the gene has been successfully cloned but the enzyme has not been produced in an active form (perhaps because expression has not occurred or because E. coli is a poor host to support production of active enzyme), or where there is no convenient function-based assay available. 

The reproductive/developmental toxicity screening test can provide initial information on possible effects on reproduction and/or development and may make it possible to identify a substance as being toxic to reproduction, i.e., the test gives a clear positive result. However, this test offers only limited means of detecting postnatal manifestations of prenatal exposure or effects that may be induced during postnatal exposure. In addition, because of the study design (e.g., relatively small numbers of animals per dose level, relatively short smdy duration), the test will not provide evidence for definite claims of no effects. 

---