Last Round (last + round)

Distribution by Scientific Domains

Selected Abstracts

Differentiation-dependent sensitivity to cell death induced in the developing retina by inhibitors of the ubiquitin-proteasome proteolytic pathway

D. D. C. Neves
Abstract The effects of inhibitors of proteasome function were studied in the retina of developing rats. Explants from the retina of neonatal rats at postnatal day (P) 3 or P6 were incubated with various combinations of the proteasome inhibitor carbobenzoxyl-leucinyl-leucinyl-leucinal (MG132), the protein synthesis inhibitor anisomycin, or the adenylyl cyclase activator forskolin. MG132 induced cell death in a subset of cells within the neuroblastic (proliferative) layer of the retinal tissue. The cells sensitive to degeneration induced by either MG132 or anisomycin, were birthdated by bromodeoxyuridine injections. This showed that the MG132-sensitive population includes both proliferating cells most likely in their last round of cell division, and postmitotic undifferentiated cells, at a slightly earlier stage than the population, sensitive to anisomycin-induced cell death. The results show that sensitivity to cell death induced by proteasome inhibitors defines a window of development in the transition from the cell cycle to the differentiated state in retinal cells. [source]

Downsizing and reorganization: demands, challenges and ambiguity for registered nurses

Anna Hertting MD
Background., The 1990s were characterized by substantial financial cuts, and related staff redundancies and reorganizations in the Swedish health care sector. A large hospital in Sweden was selected for the study, in which downsizing had occurred between 1995 and 1997. The number of staff in the hospital was reduced by an average of 20%, and 10% were relocated to other departments. Objective., The aims of this study were to explore registered nurses' experiences of psychosocial ,stressors' and ,motivators', and how they handled their work situations, following a period of personnel reductions and ongoing reorganization. Method., Interviews were undertaken with 14 nurses working in one Swedish hospital. Nurses were interviewed in 1997 about the recent and last round of redundancies, and were followed up 1 year later in 1998 and again in 2001. Interviews were audiotaped, transcribed and analysed for thematic content. Results., Five themes emerged in relation to nurses' perceived stressors, motivators, and coping options: ,distrust towards the employer', ,concurrent demands and challenges', ,professional ambiguity, ,a wish for collaboration', and ,efforts to gain control'. A common feature was duality and ambiguity in nurses' descriptions of the phenomena studied, meaning that identified themes had underlying sub-themes with both negative and positive dimensions. Conclusions., The concurrence of ,ever-growing job demands' and ,work going unrewarded' contributed to a feeling of being taken advantage of by the employer. The ,waste of human resources' and ,competence drain' that followed redundancies provoked anger. Unfulfilled collaboration with doctors was a major stress producer, which related to both the downsized work organization, and the complex ,deference-dominance' doctor,nurse relationship. The well-being of nurses depends on being an equal/parallel health professional in a comprehensive team that shares knowledge and improves collaborative care of patients. A consciously formulated nursing philosophy emerged as a health-promoting resource. This study demonstrates the importance of analysing feelings relating to professional ambiguity and gaining influence in a gender-related, hierarchical environment, and the need to support professional assertiveness in relation to superiors and doctors. It is also important to stress considerations that relate to differences in the age, care philosophy, and psychosocial health conditions of nurses. [source]

Patterns of recurrent evolution and geographic parthenogenesis within apomictic polyploid Easter daises (Townsendia hookeri)

Abstract Geographic patterns of parthenogenesis and the number of transitions from sexual diploidy to asexual (apomictic) autopolyploidy were examined for 40 populations of the Easter daisy, Townsendia hookeri. Analyses of pollen diameter and stainability characterized 15 sexual diploid and 25 apomictic polyploid populations from throughout the plant's western North American range. Sexual diploids were restricted to two Wisconsin refugia: Colorado/Wyoming, south of the ice sheets, and northern Yukon/Beringia. Chloroplast DNA sequencing uncovered 17 polymorphisms within the ndhF gene and trnK intron, yielding 10 haplotypes. Phylogenetic analyses indicated that five exclusively polyploid haplotypes were derived from four haplotypes that are shared among ploidies, conservatively inferring a minimum of four origins of apomictic polyploidy. Three of these apomictic polyploid origins were derived from southern sexual diploids, while the fourth origin was derived from northern sexual diploids. Analyses of regional diversity were suggestive of a formerly broad distribution for sexual diploids that has become subsequently fragmented, possibly due to the last round of glaciation. As sexual diploids were exclusively found north and south of the glacial maximum, while formerly glaciated areas were exclusively inhabited by asexual polyploids derived from both northern and southern sexual lineages, it is more likely that patterns of glaciation, as opposed to a particular latitudinal trend, played a causal role in the establishment of the observed pattern of geographic parthenogenesis in Easter daisies. [source]

The compactness of federal electoral districts in Canada in the 1980s and 1990s: an exploratory analysis

Considerations of the compactness and aesthetics of electoral districts have loomed large in the litigation surrounding the last round of US redistricting. For a variety of reasons, we expect that there will be increasing pressure on Canadian electoral cartographers to provide opportunities for protected minorities to be represented in the country's federal legislature. As a result, we expect that future electoral maps may well embody a tradeoff between compactness and other representational and cartographic desiderata. We look for evidence of this in an exploratory analysis of the last two federal electoral maps (adopted in 1987 and 1996) and in so doing we offer the first country-wide assessment of the compactness of Canadian federal electoral districts (FEDs). The results demonstrate the importance of natural boundaries in the achievement of district compactness. Strong evidence of a decline in the compactness of FEDs between the two maps is not forthcoming, however. Thus there is relatively little sign that Canadian electoral districts will be open to the kind of aesthetically-based legal challenges that American Congressional Districts faced in the 1990s. However, the analyses we report establish an important baseline against which the next electoral map, to be produced following the 2001 census, can be compared. [source]