Previous results in experimental systems have suggested that hydroxylated PCBs may decrease thyroid hormone levels through associative interaction with transthyretin. In the present paper it was investigated whether this property was also shared by various industrial chemicals, mainly pesticides. In total, 65 compounds from 12 chemical groups were analyzed for direct interference with the T4 binding site of transthyretin using a competitive binding assay. Sixty per cent of the compounds were competitive at a concentration level of 100 M. Relatively strong interactions were observed by several chlorophenols, chlorophenoxy acids and nitrophenols, as well as by individual compounds such as hexachlorobenzene, dicofol, bromoxynil and tetrachlorohydroquinone. Examples from these chemical groups, e.g. pentachlorophenol, 2,4-dichlorophenoxybutyric acid, dinoseb and bromoxynil, also reduced plasma TT4 levels in rats. In addition, bromoxynil decreased plasma TT3 levels. The results suggest the existence of a number of halogenated industrial chemicals with a potential for lowering plasma thyroid hormone levels through interference with hormone transport carriers. 相似文献
The mutagenic activity of waste material originating from an aluminum products factory was determined by the Salmonella/microsome assay, using the bacterial strains TA100, TA98 and YG1024. The material was obtained by sweeping the factory floor at the end of the work shift. Organic compounds were extracted by ultrasound for 30 min in dichloromethane or 70% ethanol. After evaporation of solvent, these extracts were dissolved in dimethylsulfoxide, and tested for the mutagenic activity at varying concentrations. All the extracts from the factory had mutagenic activity, especially in the YG1024 strain, suggesting the presence of aromatic amines, later confirmed by chemical analysis. The TA98 strain also showed mutagenic activity, though it did not exhibit the highest mutagenicity index observed with the YG1024 strain. In TA100, mutagenic activity was not observed. This study should serve as an alert to management and those who are occupationally exposed, and as a warning that this type of waste should not be discarded in the environment without any control. 相似文献
Summative content analysis was used to define methods and heuristics from each case study. The review process was in two parts: (1) A literature review to identify conventional research methods and (2) a summative content analysis of published case studies, based on the identified methods and heuristics to suggest an order and priority of where and when were used. Over 200 research and design methods and design heuristics were identified. From the review of the 20 case studies 42 were identified as being applied. The majority of methods and heuristics were applied in phase two, market choice. There appeared a disparity between the limited numbers of methods frequently used, under 10 within the 20 case studies, when hundreds were available.
Implications for Rehabilitation
The communication highlights a number of issues that have implication for those involved in assistive technology new product development:
?The study defined over 200 well-established research and design methods and design heuristics that are available for use by those who specify and design assistive technology products, which provide a comprehensive reference list for practitioners in the field;
?The review within the study suggests only a limited number of research and design methods are regularly used by industrial design focused assistive technology new product developers; and,
?Debate is required within the practitioners working in this field to reflect on how a wider range of potentially more effective methods and heuristics may be incorporated into daily working practice.