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A great deal of effort has been devoted to developing new in vitro and in vivo methods to identify and classify endocrine disrupting chemicals that have been identified in environmental samples. In this study an in vitro test based on recombinant yeast strains transfected with genes for the human estrogen receptor α was adapted to examine the presence of estrogenic and antiestrogenic substances in six Swedish landfill leachates. Antiestrogenic effects were measured as inhibition of the estradiol induced response with the human estrogen receptor α, and quantified by comparison with the corresponding inhibitory effects of a known antiestrogen, hydroxytamoxifen. The estrogenicity was within the range of that determined in domestic sewage effluents, from below the limit of detection to 29 ng estradiol units L. Antiestrogenicity was detected in some of the investigated landfill leachates, ranging between <38 and 3800 μg hydroxytamoxifen equivalents L. There was no apparent relation between the type of waste deposited on the landfills and the antiestrogenic effect. Fractionation of a landfill leachate showed that estrogenic compounds were located in two dominant fractions. Three estrogenic compounds were found that accounted for the estrogenic activity in extracts of leachates: bisphenol A, estradiol, and ethinylestradiol. The bisphenol may have been released from decomposing plastic waste and the estrogenic steroids from earlier deposits of municipal sewage sludge and pharmaceutical waste. Fractionation of leachates from three parts of a landfill showed that the antiestrogenic activity was distributed in at least four fractions and somewhat different in different flows of leachate. This indicated a heterogeneous mixture of antiestrogenic substances. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2011. [ABSTRACT FROM AUTHOR]

Estrogenicity in the bile of juvenile rainbow trout exposed to effluents from municipal sewage treatment plants and various industries was assayed by using a recombinant yeast strain containing the human estrogen receptor a gene. Estrogenicity in bile also was measured after deconjugation of steroids to provide an estimate of the exposure and as an endpoint for potential effects on the organism. In unexposed fish or fish exposed for three weeks at control localities, 0.5 to 9 ng of estradiol equivalents (EEq) were found per gram of bile (ng EEq/g bile). Fish exposed for three weeks in cages placed in the receiving waters near outlets of municipal effluent had an average activity of 26 ng EEq/g bile. Fish exposed to undiluted sewage water in aquaria had a bile estrogenicity of 51 to 87,000 ng EEq/g bile. Unconjugated estrogens contributed only 8% or less to the estrogenicity in bile of fish exposed to municipal effluents. Municipal sewage effluents were more estrogenic than the industrial effluents that were investigated. Estrogenicity in bile was compared to that in extracts of wastewater by using the same receptor assay, and to vitellogenin induction in the plasma of the same fish. Bile estrogenicity proved to be a useful and sensitive (internal) measure of exposure and indicated its potential for the display of biological effects as a complement or replacement of more laborious assays. [ABSTRACT FROM AUTHOR]

The kinetics of refolding of completely reduced human serum albumin has been studied by various methods including immunological techniques. The decrease in thiol content is very rapid in the beginning of the reoxidation process and rather slow in the later stages. Polyacrylamide gel electrophoresis studies show that, in the earlier stages of refolding, the main part of the albumin is present as various oligomers and that a slow conversion to monomer occurs as reoxidation proceeds. Rocket immunoelectrophoresis shows that the completely reduced protein is devoid of native albumin antigenic determinants but that a rapid regain of immunoprecipitability is obtained upon reoxidation. A new 'consumption' rocket immunoelectrophoretic method has been used to estimate the total regain of antigenicity. The data obtained indicate that there is a preferential rapid folding to native structure in certain parts of the molecule but that areas with wrong or incomplete foldings exist a considerable time after the initial refolding period. [ABSTRACT FROM AUTHOR]

In order to reduce the content of nitrogen in treated wastewater, microbial processes conducting nitrification of nitrogenous compounds and denitrification to gaseous nitrogen are included in the sewage wastewater treatment process. A set of compounds has been found inhibitory to these microorganisms. A procedure is presented for identification of nitrification inhibitors in wastewaters. This includes fractionation of the wastewater sample and location of the inhibitory effect using a nitrification inhibition assay where pure cultures of Nitrobacter are used. A series of unsaturated fatty acids and two monoterpenes were found to constitute the inhibitory effect in a wastewater sample from a plant for drying wood-derived fuel. [ABSTRACT FROM AUTHOR]