'Black skins-white masks': Postcolonial reflections on 'race', gender and second generation return migration to the Caribbean

This paper illustrates the opportunities afforded by the adoption of postcolonial discourse in development geography, drawing specifically on issues of transnationalism, hybridity and inbetweeness. The utility of such notions and associated approaches is illustrated by the authors' current research on the migration of young, second generation and foreign-born 'Bajan-Brits' to the small Caribbean island nation of Barbados, the homeland of their parents. Focussing on issues of 'race' and gender, the paper examines the experiences of return migration among this cohort from an interpretative perspective framed within postcolonial discourse. It argues that notwithstanding the considerable sociocultural problems of adjustment encountered, these Bajan-Brit 'returnees' may be seen as occupying positions of relative economic privilege. Theirs is a liminal space derived by virtue of having been born and/or raised in the UK and being of the black 'race'. Accordingly, they are demonstrated to be both advantaged and disadvantaged; both transnational and national; and black but, in some senses, symbolically white.

Quality of Life Issues and Second-Generation Migration: the Case of 'Bajan-Brit Returnees'

This paper forms part of research that is investigating the migration of young Bajan-Brits to Barbados. Specifically, it explores the role of quality of life issues in the decision-making processes of young Bajan-Brits as they negotiate their 'return' to Barbados. The research, based on 51 in-depth qualitative interviews conducted with an under-researched cohort of young Bajan-Brits living in Barbados, argues from a 'lure of home' conceptualisation that the return of young Bajan-Brits to Barbados can best be understood from the context of a search for a better quality of life in the face of social and economic disenfranchisement in the UK context. Subsequently, the paper examines the extent to which the quality of life factors which formed the basis of return to Barbados have in fact been realised on the part of young Bajan-Brits in their adjustment to life in Barbados. The paper ultimately argues that despite problems of adjustment, young Bajan-Brits have generally been successful in actualising a better quality of life in Barbados. Copyright (C) 2009 John Wiley & Sons, Ltd.

Poverty, migration and sex work: youth transitions in Ethiopia

Despite an emerging body of work on youth transitions, research has yet to explore the often unconventional routes to adulthood for young people marginalised through poverty. By drawing on interviews with 60 young commercial sex workers in Ethiopia, this paper explores the connections between poverty, migration and sex work and demonstrates that sex work provides a risky alternative, but often successful, path to independence for some rural-urban migrants. The paper concludes by offering recommendations for policies that seek to support young sex workers by enabling them to maintain their independence while seeking different employment.

Imagining migration: Placing children's understanding of 'moving house' in Malawi and Lesotho

Research pertaining to children's geographies has mainly focused on children's physical experiences of space, with their 'imagined geographies' receiving far less attention. The few studies of children's imagined geographies that exist tend to focus on children's national identities and their understanding of distant places. However, children's lives are not necessarily static and they often move between places. Research has not so far considered children's images of these transitional spaces or how such images are constructed. Through an examination of over 800 thematic drawings and stories, regarding 'moving house, produced by children aged 10-17 years in urban and rural communities of Lesotho and Malawi, this paper explores southern African children's representations of migration. The research considers how ideas of migration are culturally-constructed based on notions of family, home and kinship, particularly in relation to the fluid family structure characteristic of most southern African societies. The results suggest that most children imagine migration as a household rather than an individual process.. rarely including micro -migrations between extended family households in their drawings. Further, children's images of migration are place-rooted in everyday life experiences. Their representations concentrate on the reasons for migration, both negative and positive, which are specifically related to their local social and environmental situations and whether house moves take place locally or over longer distances. The paper concludes by exploring the implications of these conceptualisations of moving house for children's contemporary migration experiences, particularly in light of changing family structures due to the effects of the HIV/AIDS pandernic. (c) 2005 Elsevier Ltd. All rights reserved

Macrophage antioxidant protection within atherosclerotic plaques

Macrophage cells within inflammatory lesions are exposed to a wide range of degrading and cytotoxic molecules including reactive oxygen species. Unlike neutrophils, macrophages do not normally die in this environment but continue to generate oxidants, phagocytose cellular remains, and release a range of cytoactive agents which modulate the immune response. It is this potential of the macrophage cell to survive in an oxidative environment that allows the growth and complexity of advanced atherosclerotic plaques. This review will examine the oxidants encountered by macrophages within an atherosclerotic plaque and describe some of the potential antioxidant mechanisms which enable macrophages to function within inflammatory lesions. Ascorbate, alpha-tocopherol, and glutathione appear to be central to the protection of macrophages yet additional antioxidant mechanisms appear to be involved. gamma-Interferon causes macrophages to generate 7,8dihydroneopterin/neopterin and 3-hydroxyanthranilic acid both of which have antioxidant properties. Manganese superoxide dismutase is also upregulated in macrophages. The evidence that these antioxidants provide further protection, so allowing the macrophage cells to survive within sites of chronic inflammation such as atherosclerotic plaques, will be described.

Transcriptional profiling of the LPS induced NF-kappaB response in macrophages

BACKGROUND: Exposure of macrophages to bacterial products such as lipopolysaccharide (LPS) results in activation of the NF-kappaB transcription factor, which orchestrates a gene expression programme that underpins the macrophage-dependent immune response. These changes include the induction or repression of a wide range of genes that regulate inflammation, cell proliferation, migration and cell survival. This process is tightly regulated and loss of control is associated with conditions such as septic shock, inflammatory diseases and cancer. To study this response, it is important to have in vitro model systems that reflect the behaviour of cells in vivo. In addition, it is necessary to understand the natural differences that can occur between individuals. In this report, we have investigated and compared the LPS response in macrophage derived cell lines and peripheral blood mononuclear cell (PBMC) derived macrophages. RESULTS: Gene expression profiles were determined following LPS treatment of THP-1 cells for 1 and 4 hours. LPS significantly induced or repressed 72 out of 465 genes selected as being known or putative NF-kappaB target genes, which exhibited 4 temporal patterns of expression. Results for 34 of these genes, including several genes not previously identified as LPS target genes, were validated using real time PCR. A high correlation between microarray and real time PCR data was found. Significantly, the LPS induced expression profile of THP-1 cells, as determined using real time PCR, was found to be very similar to that of human PBMC derived macrophages. Interestingly, some differences were observed in the LPS response between the two donor PBMC macrophage populations. Surprisingly, we found that the LPS response in U937 cells was dramatically different to both THP-1 and PBMC derived macrophages. CONCLUSION: This study revealed a dynamic and diverse transcriptional response to LPS in macrophages, involving both the induction and repression of gene expression in a time dependent manner. Moreover, we demonstrated that the LPS induced transcriptional response in the THP-1 cell line is very similar to primary PBMC derived macrophages. Therefore, THP-1 cells represent a good model system for studying the mechanisms of LPS and NF-kappaB dependent gene expression.

Bayesian estimation of recent migration rates after a spatial expansion

Approximate Bayesian computation (ABC) is a highly flexible technique that allows the estimation of parameters under demographic models that are too complex to be handled by full-likelihood methods. We assess the utility of this method to estimate the parameters of range expansion in a two-dimensional stepping-stone model, using samples from either a single deme or multiple demes. A minor modification to the ABC procedure is introduced, which leads to an improvement in the accuracy of estimation. The method is then used to estimate the expansion time and migration rates for five natural common vole populations in Switzerland typed for a sex-linked marker and a nuclear marker. Estimates based on both markers suggest that expansion occurred < 10,000 years ago, after the most recent glaciation, and that migration rates are strongly male biased.

Class II phosphoinositide 3-kinase defines a novel signaling pathway in cell migration

The lipid products of phosphoinositide 3-kinase (PI3K) are involved in many cellular responses such as proliferation, migration, and survival. Disregulation of PI3K-activated pathways is implicated in different diseases including cancer and diabetes. Among the three classes of PI3Ks, class I is the best characterized, whereas class II has received increasing attention only recently and the precise role of these isoforms is unclear. Similarly, the role of phosphatidylinositol-3-phosphate (PtdIns-3-P) as an intracellular second messenger is only just beginning to be appreciated. Here, we show that lysophosphatidic acid (LPA) stimulates the production of PtdIns-3-P through activation of a class II PI3K (PI3K-C2β). Both PtdIns-3-P and PI3K-C2β are involved in LPA-mediated cell migration. This study is the first identification of PtdIns-3-P and PI3K-C2β as downstream effectors in LPA signaling and demonstration of an intracellular role for a class II PI3K. Defining this novel PI3K-C2β- PtdIns-3-P signaling pathway may help clarify the process of cell migration and may shed new light on PI3K-mediated intracellular events.

Triglyceride-rich lipoproteins inhibit cholesterol efflux to apolipoprotein (apo) A1 from human macrophage foam cells

High circulating levels of triglyceride-rich lipoproteins (TGRL) represent an independent risk factor for coronary artery disease. Here, we show that TGRL inhibit the efflux of cholesterol from 'foam cell' macrophages to lipid-poor apolipoprotein (apo) A1, and may thereby inhibit arterial reverse cholesterol transport and promote the formation of atherosclerotic lesions. Human (THP-1) monocyte-derived macrophages were pre-incubated (48h) with acetylated low-density lipoprotein (AcLDL) to provide a foam cell model of cholesterol efflux to apoA1. Pre-incubation of macrophage 'foam cells' with TGRL (0-200 mug/ml, 0-24 h) inhibited the efflux of exogenously radiolabelled ([H-3]), endogenously synthesised ([C-14]) and cellular cholesterol mass to lipid-poor apoA1, but not control medium, during a (subsequent) efflux period. This inhibition is dependent upon the length of prior exposure to, and concentration of, TGRL employed, but is independent of changes in intracellular triglyceride accumulation or turnover of the cholesteryl ester pool. Despite the negative impact of TGRL on cholesterol efflux, major proteins involved in this process-namely apoE, ABCA1, SR-B1 and caveolin-1-were unaffected by TGRL pre-incubation, suggesting that exposure to these lipoproteins inhibits an alternate, and possibly novel, anti-atherogenic pathway. (C) 2003 Elsevier Ireland Ltd. All rights reserved.