Nck adaptor proteins link nephrin to the actin cytoskeleton of kidney podocytes

The glomerular filtration barrier in the kidney is formed in part by a specialized intercellular junction known as the slit diaphragm, which connects adjacent actin-based foot processes of kidney epithelial cells (podocytes). Mutations affecting a number of slit diaphragm proteins, including nephrin (encoded by NPHS1), lead to renal disease owing to disruption of the filtration barrier and rearrangement of the actin cytoskeleton, although the molecular basis for this is unclear. Here we show that nephrin selectively binds the Src homology 2 (SH2)/SH3 domain-containing Nck adaptor proteins, which in turn control the podocyte cytoskeleton in vivo. The cytoplasmic tail of nephrin has multiple YDxV sites that form preferred binding motifs for the Nck SH2 domain once phosphorylated by Src-family kinases. We show that this Nck-nephrin interaction is required for nephrin-dependent actin reorganization. Selective deletion of Nck from podocytes of transgenic mice results in defects in the formation of foot processes and in congenital nephrotic syndrome. Together, these findings identify a physiological signalling pathway in which nephrin is linked through phosphotyrosine-based interactions to Nck adaptors, and thus to the underlying actin cytoskeleton in podocytes. Simple and widely expressed SH2/SH3 adaptor proteins can therefore direct the formation of a specialized cellular morphology in vivo.     

Rhetorics and Realities in Public Service Organizations: Systemic Practice and Organizational Learning as Critically Reflexive Action Research (CRAR)

This article sets out to develop an argument and theory-in-practice related to organizational learning and systemic practice as critically reflexive action research (CRAR). It explores principles and concepts associated with CRAR, in the context of different emphases in understandings of and approaches to managing or working with change. The notion of epistemologies of practice is developed, as the basis for introducing on-site and off-site CRAR as interweaving cycles of managerial and organizational learning. A multilayered illustration of an improvisational CRAR environment, using principles of dialectical enquiry and critical learning theater, is offered. A diagrammatic analysis provides the framework for describing and reflecting critically on key CRAR processes. This is expanded with a consideration of possibilities for documentation that can assist with the validation of quality in CRAR processes and outcomes. This has relevance in the context of postpositivist action research at postgraduate levels or within project-based CRAR partnerships. This leads to a further discussion of principles and concepts, in the context of other literature and pressures on public services.     

Improved estimates of upper-ocean warming and multi-decadal sea-level rise

Changes in the climate system's energy budget are predominantly revealed in ocean temperatures and the associated thermal expansion contribution to sea-level rise. Climate models, however, do not reproduce the large decadal variability in globally averaged ocean heat content inferred from the sparse observational database, even when volcanic and other variable climate forcings are included. The sum of the observed contributions has also not adequately explained the overall multi-decadal rise. Here we report improved estimates of near-global ocean heat content and thermal expansion for the upper 300 m and 700 m of the ocean for 1950-2003, using statistical techniques that allow for sparse data coverage and applying recent corrections to reduce systematic biases in the most common ocean temperature observations. Our ocean warming and thermal expansion trends for 1961-2003 are about 50 per cent larger than earlier estimates but about 40 per cent smaller for 1993-2003, which is consistent with the recognition that previously estimated rates for the 1990s had a positive bias as a result of instrumental errors. On average, the decadal variability of the climate models with volcanic forcing now agrees approximately with the observations, but the modelled multi-decadal trends are smaller than observed. We add our observational estimate of upper-ocean thermal expansion to other contributions to sea-level rise and find that the sum of contributions from 1961 to 2003 is about 1.5 +/- 0.4 mm yr(-1), in good agreement with our updated estimate of near-global mean sea-level rise (using techniques established in earlier studies) of 1.6 +/- 0.2 mm yr(-1).     

Construction and expression of retroviruses encoding dual drug resistance genes in human umbilical cord blood CD34+ cells

A series of retro viral vectors encoding humanmdr1 gene alone as wetl as in combination with either humanmgmt gene or human mutantSer ³¹-dhfr gene are engineered. The resultant retroviruses are used to transduce human umbilical cord blood CD34⁺ cetls. It has been shown that expression of dual drug resistance genes in transduced cetls confers a broad range of resistance to both kinds of corresponding drugs. These data suggest a rationale for the use of such double chemoresistance gene constructs in anin vivo model in which transduced hematopoietic cetls will acquire multiple protection against the cytotoxic side effects of combination chemotherapy and may have future application in chemoprotection of normal tissues, thus killing tumor cetls more effectivety.     

Levels ofβ-trace protein and lysozyme in human amniotic fluids

Summary The levels of -trace protein and lysozyme were estimated in amniotic fluids from normal fetuses and from fetuses with neuraltube defects. The values of these proteins in normal amniotic fluids were found to be similar to those detected in fetuses with anencephaly and spina bifida. The levels of lysozyme were shown to be correlated with gestational age.