991 resultados para Seasonal migration


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Recent literature suggests that the increasingly blurred relationship between paid employment and retirement facilitates a retirement transition period, a life course stage, which may involve a change of residence. The role of such pre-retirement age mobility in the repopulation of rural areas has, however, received relatively little academic scrutiny. This paper draws upon findings from a two-year study conducted in three UK case study areas. It examines the extent of pre-retirement age (aged 50–64) migration into remote rural communities and the impacts this type of movement has upon economic activity, social and community engagement and service provision. It is argued that while this under-researched cohort offers opportunities to support the social and economic sustainability of rural communities (at least in the short and medium term), there are notable challenges which are likely to emerge as it ages in situ. The findings are particularly relevant given national trends on population ageing.

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The topoisomerase I inhibitor irinotecan is used to treat advanced colorectal cancer and has been shown to have p53-independent anticancer activity. The aim of this study was to identify the p53-independent signaling mechanisms activated by irinotecan. Transcriptional profiling of isogenic HCT116 p53 wild-type and p53 null cells was carried out following treatment with the active metabolite of irinotecan, SN38. Unsupervised analysis methods showed that p53 status had a highly significant impact on gene expression changes in response to SN38. Pathway analysis indicated that pathways involved in cell motility [adherens junction, focal adhesion, mitogen-activated protein kinase (MAPK), and regulation of the actin cytoskeleton] were significantly activated in p53 null cells, but not p53 wild-type cells, following SN38 treatment. In functional assays, SN38 treatment increased the migratory potential of p53 null and p53-mutant colorectal cancer cell lines, but not p53 wild-type lines. Moreover, p53 null SN38-resistant cells were found to migrate at a faster rate than parental drug-sensitive p53 null cells, whereas p53 wild-type SN38-resistant cells failed to migrate. Notably, cotreatment with inhibitors of the MAPK pathway inhibited the increased migration observed following SN38 treatment in p53 null and p53-mutant cells. Thus, in the absence of wild-type p53, SN38 promotes migration of colorectal cancer cells, and inhibiting MAPK blocks this potentially prometastatic adaptive response to this anticancer drug.

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Objectives: To investigate seasonal variation in month of diagnosis in children with type 1 diabetes registered in EURODIAB centres during 1989-2008.
Methods: 23 population-based registers recorded date of diagnosis in new cases of clinically diagnosed type 1 diabetes in children aged under 15 years. Completeness of ascertainment was assessed through capture-recapture methodology and was high in most centres. A general test for seasonal variation (11df) and Edward's test for sinusoidal (sine wave) variation (2df) were employed. Time series methods were also used to investigate if meteorological data were predictive of monthly counts after taking account of seasonality and long term trends.
Results: Significant seasonal variation was apparent in all but two small centres, with an excess of cases apparent in the winter quarter. Significant sinusoidal pattern was also evident in all but two small centres with peaks in December (14 centres), January (5 centres) or February (2 centres). Relative amplitude varied from ±11% to ±39% (median ±18%). There was no relationship across the centres between relative amplitude and incidence level. However there was evidence of significant deviation from the sinusoidal pattern in the majority of centres. Pooling results over centres, there was significant seasonal variation in each age-group at diagnosis, but with significantly less variation in those aged under 5 years. Boys showed marginally greater seasonal variation than girls. There were no differences in seasonal pattern between four sub-periods of the 20 year period. In most centres monthly counts of cases were not associated with deviations from normal monthly average temperature or sunshine hours; short term meteorological variations do not explain numbers of cases diagnosed.
Conclusions: Seasonality with a winter excess is apparent in all age-groups and both sexes, but girls and the under 5s show less marked variation. The seasonal pattern changed little in the 20 year period.

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A series of shell middens and miscellaneous habitation sites, located in a dune
system in west County Galway, have been exposed and are slowly disappearing
through wind, wave and surface erosion. In 1992 a project was initiated to
record, sample and date some of these sites and the radiocarbon results
demonstrated that activity in the area spanned the Early Bronze Age through to
the Iron Age and into the early and post medieval periods. This preliminary
fieldwork was succeeded by the excavation of three of the better-preserved sites; a Bronze Age midden in 1994 and two early medieval sites (the subject of this paper), in 1997. The medieval sites dated to the late-seventh to ninth century adand were represented by a sub-circular stone hut with a hearth and the charred remains of a more ephemeral wooden tent-like structure. The discovery of a bronze penannular brooch of ninth/tenth century date at the latter site wouldsuggest that the settlements are not the remains of transient, impoverishedpeoples of the lower classes of society, eking out a living along the coast. The calcareous sands ensured good preservation of organic remains*fish and mammal bones, charred cereal grains, seeds and seaweed, and marine molluscs. Analyses of these indicated exploitation of marine resources but, otherwise, were comparable with the diet and economy represented by assemblages from established contemporary site types of the period. Unlike raths, cranno´gs and monastic settlements, however, the volume of material represented at the Galway sites was slight, despite the excellent preservation conditions. A range of seasonal indicators also suggested temporary habitation: probable latespring/summer occupation of the stone hut site and autumnal occupancy of the second, less substantial site. It is suggested that the machair plain, beside which the dunes are located, was most probably the attraction for settlers to the area and was exploited as an alternative pasture for the seasonal grazing of livestock.
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Connective tissue growth factor [CTGF]/CCN2 is a prototypic member of the CCN family of regulatory proteins. CTGF expression is up-regulated in a number of fibrotic diseases, including diabetic nephropathy, where it is believed to act as a downstream mediator of TGF-beta function; however, the exact mechanisms whereby CTGF mediates its effects remain unclear. Here, we describe the role of CTGF in cell migration and actin disassembly in human mesangial cells, a primary target in the development of renal glomerulosclerosis. The addition of CTGF to primary mesangial cells induced cell migration and cytoskeletal rearrangement but had no effect on cell proliferation. Cytoskeletal rearrangement was associated with a loss of focal adhesions, involving tyrosine dephosphorylation of focal adhesion kinase and paxillin, increased activity of the protein tyrosine phosphatase SHP-2, with a concomitant decrease in RhoA and Rac1 activity. Conversely, Cdc42 activity was increased by CTGF. These functional responses were associated with the phosphorylation and translocation of protein kinase C-zeta to the leading edge of migrating cells. Inhibition of CTGF-induced protein kinase C-zeta activity with a myristolated PKC-zeta inhibitor prevented cell migration. Moreover, transient transfection of human mesangial cells with a PKC-zeta kinase inactive mutant (dominant negative) expression vector also led to a decrease in CTGF-induced migration compared with wild-type. Furthermore, CTGF stimulated phosphorylation and activation of GSK-3beta. These data highlight for the first time an integrated mechanism whereby CTGF regulates cell migration through facilitative actin cytoskeleton disassembly, which is mediated by dephosphorylation of focal adhesion kinase and paxillin, loss of RhoA activity, activation of Cdc42, and phosphorylation of PKC-zeta and GSK-3beta. These changes indicate that the initial stages of CTGF mediated mesangial cell migration are similar to those involved in the process of cell polarization. These findings begin to shed mechanistic light on the renal diabetic milieu, where increased CTGF expression in the glomerulus contributes to cellular dysfunction.

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The relationship between migration and age has long been established, and most recently, there have been calls for the inclusion of a life course perspective to migration research. In this paper, we explore Northern Ireland’s internal migration patterns, and in particular, we test for the importance of urban to rural migration at different stages of the life course. Data from the Northern Ireland Longitudinal Study are used for the first time to analyse urban–rural migration patterns. The resulting modelling demonstrates unique aspects of urban to rural migration within Northern Ireland, which up until now have gone largely
unreported. Results from logistic regression modelling suggest that there is an age selectivity to urban– rural mobility but not necessarily at the life course stages predicted from a review of the life course migration literature. Individuals in younger age groups (at the household and family formation stages of the life course) are most likely to make an urban to rural move in Northern Ireland, with a decline in the likelihood of this move type with age. Possible explanations are offered linked to Northern Ireland’s settlement hierarchy, rural planning policy, and family farming traditions. The findings challenge researchers to pay due attention to how migration processes may play out differently in varying geographical, social, and planning contexts and emphasise the importance of structural factors to explain migration patterns.