Background The stability of parathyroid hormone (PTH) in blood ex vivo is a significant practical problem for laboratories and clinicians. Several studies have suggested that PTH is more stable in blood collected into a potassium edetate (EDTA) preservative.

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Breast cancer remains a major cause of death in postmenopausal women. Concentrations of the biologically active oestrogen, oestradiol, are increased in breast tumours and there is now good evidence that cytokines which are present in tumours can stimulate tumour oestrogen synthesis. In this study we have examined the ability of interleukin-6 (IL-6) or tumour necrosis factor \g=a\(TNF\g=a\),either alone or in combination, to stimulate aromatase, oestradiol dehydrogenase (reductive) or oestrone sulphatase activities in cultured breast cancer cells. Both IL-6 and TNF\g=a\were able to stimulate the activities of these enzymes but in combination acted synergistically to markedly enhance enzyme activity. The possibility that \g=a\2-macroglobulin might also interact with IL-6 to enhance oestradiol dehydrogenase activity was also examined but no evidence for any synergistic interaction between these two factors was obtained. Cytokines, such as IL-6 and TNF\g=a\, are emerging as having a central role in regulating breast tumour oestrogen synthesis. Understanding the role that cytokines have in regulating oestrogen synthesis in breast tumours should lead to the development of novel therapeutic agents for use in the treatment of women with breast cancer.

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In order to develop an understanding of the interaction that takes place between teacher and learner in the literacy classroom, this article draws on perspectives from sociocultural theory and the writings of L.S Vygotsky, M . M Bakhtin, and J. Habermas. Through discussion of a learner's written text, a descriptive framework of 'communicative action' is developed to assist dialogues of development and dynamic assessment between teachers and learners. Specific attention is paid to the problem of developing ongoing pedagogic relationships in the normal circumstance of one teacher attempting to meet the literacy needs of many learners.