E-SCREEN

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... 

Metal-catalyzed cycloaddition reactions have been in intensive development in recent years and many aspects of the various types of reaction are covered in the many different books, reviews, and numerous research papers dealing with the topic. The focus of the work performed in the field of metal-catalyzed cycloaddition reactions has been devoted to the development of the reactions i.e. screening reaction conditions (e.g. different metals and ligands), substrates, and showing that the reaction developed might have a potential for the synthesis of products of general interests. 

Soto AM, Sonnenschein C, Chung KL, et al. 1995. The E-SCREEN assay as a tool to identify estrogens An update on estrogenic environmental pollutants. Environ Health Perspect 103 (Supp. 

Soto, A.M., Sonnenschein, C., and Chung, K.L. et al. (1995). The E-screen assay as a tool to identify estrogens—an update on estrogenic environmental-pollutants. Environmental Health Perspectives 103, 113-122. 

Dybendal X Guttormsen AB, Elsayed S, Askeland 48 B, Harboe T, Florvaag E Screening for mast cell tryptase and serum IgE antibodies in 18 patients with anaphylactic shock during general anaesthesia. 

Hayasaka, Y. and Asenstorfer, R.E., Screening for potential pigments derived from anthocyanins in red wine using nanoelectrospray tandem mass spectrometry, J. Agric. Food Chem., 50, 756, 2002. 

Fryman, Charles E. Screening Methodology for Assessing the Adequacy of Blast Protection for Control Rooms and Other Site Buildings A Workbook for BP Oil Refineries. Report No. 1993-221031. Sunbury BP International Limited, Manufacturing and Supply Technology Development Unit. July 1993. 

A major drawback of the PSAa is, however, the rather time-consuming calculation, particularly, the Monte Carlo conformational search, which makes PSAa inappropriate for computational screening (e-screening) of large virtual libraries. 

In view of latter developments (see Sections 16.4.9-16.4.11 for further details) the procedure, even with simplifications such as using a single CONCORD/ CORINA-derived 3D geometry instead of performing a Monte Carlo conformational search, is too computationally expensive to be applied to e-screening of virtual libraries. However, it may still be a useful alternative/complement for computing more detailed information about a compound, or to provide a more easily interpretable model to complement other models based on more rapidly computable parameters but which are difficult to interpret in terms of how to modify compounds in order for them to have better intestinal absorption characteristics. 

An example of a TIE approach is that described by Desbrow et al. [7]. In this work, the endocrine disrupting activity detected in effluents of seven UK WWTPs by means of a yeast-based screening assay [52] was mainly attributed to the presence of estradiol, estrone, and ethynylestradiol. However, to assess the estrogenic activity different bioassays may be used, e.g., the yeast-based recombinant estrogen receptor-reporter assay (YES), the MCF-7 cell proliferation (E-screen), and the estrogen receptor-mediated chemically activated... 

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

Finally, it is interesting to note that brominated derivatives of NP included in the present study, estrogenic in the E-Screen bioassay, were proposed to be fat-soluble [30], In fact, as non-ionic surfactants, these molecules have a hydrophilic and a hydrophobic part [31]. The presence of these brominated compounds in fat tissue of humans or animals has yet to be demonstrated. However, if they do bioaccumulate in adipose tissue, as their fat solubility suggests, they may account for the xenoestrogen burden alongside organohalogenated compounds. 

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. 

Estrogenicity of LAS, SPCs and other compounds in the E-Screen bioassay... 

Linear alcohols were studied using MCF7 cells in the proliferation assay and in the expression of estrogen-dependent genes (Table 7.3.4). The AS C12 i4, its ethoxylated derivative (ALFONIC 1214) and linear alcohols from nonanol to dodecanol increase cell proliferation in the E-Screen assay. This effect was seen at 10-100 xM concentrations and,... 

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. 

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