INCREASED EXPRESSION OF ONE OF TWO ADENOSINE DEAMINASE ALLELES IN A HUMAN CHORIOCARCINOMA CELL LINE FOLLOWING SELECTION WITH ADENINE NUCLEOSIDES

The human choriocarcinoma cell line JEG-3 is heterozygous at the adenosine deaminase (ADA) gene locus. Both allelic genes are under strong but incomplete repression causing a very low level expression of the gene locus. Because cytotoxic adenosine analogues such as 9-(beta)-D arabinofuranosyladenine (ara-A) and 9-(beta)-D xylofuranosyladenine (xyl-A) can be specifically detoxified by the action of ADA, these analogues were used to select for JEG-3 derived cells which had increased ADA expression. When JEG-3 cells were subjected to a multi-step, successively increasing dosage of either ara-A or xyl-A, resistant cells with increased ADA expression were generated. This increased ADA expression in the resistant cells was unstable, so that when the selective pressure was removed, cellular ADA expression would decrease. Subclone analysis of xyl-A resistant cells revealed that compared to parental JEG-3 cells, individual resistant cells had either elevated ADA levels or decreased adenosine kinase (ADK) levels or both. This altered ADA and ADK expression in the resistant cells were found to be independent events. Because of high endogenous tissue conversion factor (TCF) expression in the JEG-3 cells, the allelic nature of the increased ADA expression in most of the resistant cells could not be determined. However, several resistant subcloned cells were found to have lost TCF expression. These TCF('-) cells expressed only the ADA*2 allelic gene product. Cell fusion experiments demonstrated that the ADA*1 allelic gene was intact and functional in the A3-1A7 cell line. Chromosomal analysis of the A3-1A7 cells showed that they had no double-minutes or homogeneously staining chromosomal regions, although a pair of new chromosomes were found in these cells. Segregation analysis of the hybrid cells indicated that an ADA*2 allelic gene was probably located on this new chromosome. The analysis of the A3-1A7 cell line suggested that the expression of only ADA 2 in these cells was the result of possibly a cis-deregulation of the ADA gene locus or more probably an amplification of the ADA*2 allelic gene. Two effective positive selection systems for ADA('+) cells were also developed and tested. These selection systems should eventually lead to the isolation of the ADA gene.^

Translating knowledge into action: Information needs of decision-makers in healthcare

Purpose: The purpose of this study was to assess the healthcare information needs of decision-makers in a local US healthcare setting in efforts to promote the translation of knowledge into action. The focus was on the perceptions and preferences of decision-makers regarding usable information in making decisions as to identify strategies to maximize the contribution of healthcare findings to policy and practice. Methods: This study utilized a qualitative data collection and analysis strategy. Data was collected via open-ended key-informant interviews from a sample of 37 public and private-sector healthcare decision-makers in the Houston/Harris County safety net. The sample was comprised of high-level decision-makers, including legislators, executive managers, service providers, and healthcare funders. Decision-makers were asked to identify the types of information, the level of collaboration with outside agencies, useful attributes of information, and the sources, formats/styles, and modes of information preferred in making important decisions and the basis for their preferences. Results: Decision-makers report acquiring information, categorizing information as usable knowledge, and selecting information for use based on the application of four cross-cutting thought processes or cognitive frameworks. In order of apparent preference, these are time orientation, followed by information seeking directionality, selection of validation processes, and centrality of credibility/reliability. In applying the frameworks, decision-makers are influenced by numerous factors associated with their perceptions of the utility of information and the importance of collaboration with outside agencies in making decisions as well as professional and organizational characteristics. Conclusion: An approach based on the elucidated cognitive framework may be valuable in identifying the reported contextual determinants of information use by decision-makers in US healthcare settings. Such an approach can facilitate active producer/user collaborations and promote the production of mutually valued, comprehensible, and usable findings leading to sustainable knowledge translation efforts long-term.^