Migration and development : the case of Puerto Rico /

Cover title.

The impact of IRCA on the migration patterns of a community in Los Altos, Jalisco, Mexico /

"June 1990."

Equine laminitis: cleavage of laminin 5 associated with basement membrane dysadhesion

Reasons for performing study: The key lesion of laminitis is separation at the hoof lamellar dermal-epidermal interface. For this to happen the structural and adhesion proteins of the basement membrane zone must be altered. Which proteins and how damage to them leads to the lamellar separation of laminitis is unknown. Objectives: To investigate lamellar hemidesmosome and cytoskeleton damage and basement membrane dysadhesion using light microscopy (LM) and immunofluorescence microscopy (IFM). Methods: Cryostat sections of lamellar tissues from 2 control and 6 Standardbred horses with oligofructose induced laminitis were studied using LM and IFM. Plectin, integrin alpha(6) and BP230 antibody was used to label hemidesmosome intracellular plaque proteins and anti-BP180 and anti-laminin 5 (L5) was used to label anchoring filament (AF) proteins. Cytoskeleton intermediate filaments were labelled using anti-cytokeratin 14. The primary antibodies of selected sections were double labelled to show protein co-localisation. Results: Laminitis caused reduction of transmembrane integrin alpha(6), the AF proteins BP180 and L5,and failure of co-localisation of BP180 and L5. Proteins of the inner hemidesmosomal plaque, plectin and BP230, were unaffected. Conclusions: Loss of co-localisation of L5 and BP180 suggests that, during the acute phase of laminitis, L5 is cleaved and therefore, the AFs connecting the epidermis to the dermis, fail. Without a full complement of AFs separation at the lamellar dermo-epidermal junction occurs. Potential relevance: Suppressing or inhibiting metalloproteinase activity may prevent L5 cleavage and therefore the lamellar dermo-epidermal separation of laminitis.

A mathematical model of integrin-mediated haptotactic cell migration

Haptotactic cell migration, a directed response to gradients of cell—extracellular matrix adhesion, is an important process in a number of biological phenomena such as wound healing and tumour cell invasion. Previously, mathematical models of haptotaxis have been developed on the premise that cells migrate in response to gradients in the density of the extracellular matrix. In this paper, we develop a novel mathematical model of haptotaxis which includes the adhesion receptors known as integrins and a description of their functional activation, local recruitment and protrusion as part of lamellipodia. Through the inclusion of integrins, the modelled cell matter is able to respond to a true gradient of cell–matrix adhesion, represented by functionally active integrins. We also show that previous matrix-mediated models are in fact a subset of the novel integrin-mediated models, characterised by specific choices of diffusion and haptotaxis coefficients in their model equations. Numerical solutions suggest the existence of travelling waves of cell migration that are confirmed via a phase plane analysis of a simplified model.

The role of migration in urban transition : studies of the relationship between migration and modernisation for Brisbane and Stockholm

Wilbur Zelinsky formulated a Hypothesis of Mobility Transition in 1971,in which he tried to relate all aspects of mobility to the Demographic Transition and modernisation. This dissertation applies the theoretical framework, proposed by Zelinsky and extended to encompass a family of transitions, to understand migration patterns of city regions. The two city regions, Brisbane and Stockholm, are selected as case studies, representing important city regions of similar size, but drawn from contrasting historical settings. A comparison of the case studies with the theoretical framework aims to determine how the relative contributions of net migration, the source areas of migrants, and the migration intensity change with modernisation. In addition, the research also aims to identify aspects of modernisation affecting migration. These aspects of migration are analysed with a "historical approach" and a "multivariate approach". An extensive investigation into the city regions' historical background provides the source, from which evidence for a relationship between migration and modernisation is extracted. With this historical approach, similarities and differences in migration patterns are identified. The other research approach analyse multivariate data, from the last two decades, on migration flows and modernisation. Correlations between migration and key aspects of modernisation are tested with multivariate regression, based on an alternative version of a spatial interaction model. The project demonstrates that the changing functions of cities and the structural modernisation are influential on migration. Similar patterns are found, regarding the relative contributions of net migration and natural increase to population growth. The research finds links between these changes in the relative contribution of net migration and demographic modernisation. The findings on variations in urban and rural source areas of migrants to city regions do not contradict the expected pattern, but data limitations prevent definite conclusion to be drawn. The assessment of variations in migration intensity resulted in the expected pattern not being supported. Based on Swedish data, the hypothesised increase in migration intensity is rejected. Interactional migration data also show patterns different from those derived from the theoretical framework. The findings, from both research approaches, suggested that structural modernisation affected migration flows more than demographic modernisation. The findings lead to a formulation of hypothesised patterns for migration to city regions. The study provides an important research contribution by applying the two research approaches to city regions. It also combines the study of internal and international migration to address the research objectives within a framework of transitional change.

Multiple roles of angiopoietins in atherogenesis

Purpose of review: The roles of angiopoietin-1 (Ang-1) and angiopoietin-2 (Ang-2) during vascular development have been extensively investigated, as has been their role in controlling the responsiveness of the endothelium to exogenous cytokines. However, very little is known about the role of these vascular morphogenic molecules in the pathogenesis of atherosclerosis. Here, we summarize the recent research into angiopoietins in atherosclerosis. Recent findings: Angiopoietin-2 is a context-dependent agonist that protects against the development of arteriosclerosis in rat cardiac allograft. A recent study showed, contrary to expectations, that a single systemic administration of adenoviral Ang-2 to apoE-/- mice, fed a Western diet, reduced atherosclerotic lesion size and LDL oxidation in a nitric oxide synthase dependent manner. In contrast, overexpression of Ang-1 fails to protect from rat cardiac allograft due to smooth muscle cell activation. The potential proatherogenic effect of Ang-1 is further supported by the induction of chemotaxis of monocytes by Ang-1 in a manner that is independent of Tie-2 and integrin binding. These studies highlight the need for extensive research to better understand the role of angiopoietins in the cardiovascular setting. Summary: Ang-2 inhibits atherosclerosis by limiting LDL oxidation via stimulation of nitric oxide production. In contrast, Ang-1 can promote monocyte and neutrophil migration. The angiopoietin–Tie-2 system provides an important new target for modulating vascular function.

Importance of tissue transglutaminasenitrosylation in fibroblasts migration and MMPregulation

As an extracellular second messenger, nitric oxide (NO) mediates the modification of proteins through nitrosylation of cysteine andtyrosine residues. Tissue Transglutaminase (TG2) is a Ca2+ activated, sulfhydryl rich protein with 18 free cysteine residues, which catalyzes ε-(γ glutamyl)lysine crosslink between extracellular and intracellular proteins. NO can nitrosylate up to 15 of the cysteine residues in TG2, leading to the irreversible inactivation of the enzyme activity. The interplay between these two agents was revealed for the first time by our study showing that NO inhibited the TG2-induced transcriptional activation of TGFb1and extracellular matrix (ECM) protein synthesis by nitrosylating TG2 in an inactive confirmation with inert catalytic activity. However, nitrosylated TG2 was still able to serve as a novel cell adhesion protein. In the light of our previous findings, in this study we aim to elucidate the NO modified function of TG2 in cell migration using an in vitro model mimicking the tissue matrix remodeling phases of wound healing. Using transfected fibroblasts expressing TG2 under the control of the tetracycline-off promoter, we demonstrate that upregulation of TG2 expression and activity inhibited the cell migration through the activation of TGFβ1. Increased TG2 activity led to arise in the biosynthesis and activity of the gelatinases, MMP-2 andMMP-9, while decreasing the biosynthesis and activity of the col-lagenases MMP-1a and MMP-13. NO donor S-Nitroso-N-acetyl-penicillamine (SNAP) treatment relieved the TG2 obstructed-cellmigration by blocking the TG2 enzyme activity. In addition,decrease in TG2 activity due to nitrosylation led to an inhibition of TGFβ1, which in turn affected the pattern of MMP activation. Recent evidence suggests that, once in complex with fibronectin in the ECM, TG2 can interact with syndecan-4 or integrinβ-1and regulate the cell adhesion. In the other part of this study, the possible role of nitrosylated TG2 on the regulation of cell migration during wound healing was investigated with respect to its interactions with integrin β1 (ITGβ1) and syndecan-4 (SDC4). Treatment with TG2 inhibitor Z-DON resulted in a 50% decrease in the TG2 interaction with ITGB1 and SDC4, while increasing concentrations of SNAP firstly led to a substantial decrease and then completely abolished the TG2/ITGβ1 and TG2/SDC4 complex formation on the cell surface. Taken together, data obtained from this study suggests that nitrosylation of TG2 leads to a change not only in the binding partners of TG2 on cell surface but also in TGFβ1-dependent MMP activation, which give rise to an increase in the migration potential of fibroblasts.

Failure mechanism of the all-polyethylene glenoid implant

Fixation failure of glenoid components is the main cause of unsuccessful total shoulder arthroplasties. The characteristics of these failures are still not well understood, hence, attempts at improving the implant fixation are somewhat blind and the failure rate remains high. This lack of understanding is largely due to the fundamental problem that direct observations of failure are impossible as the fixation is inherently embedded within the bone. Twenty custom made implants, reflecting various common fixation designs, and a specimen set-up was prepared to enable direct observation of failure when the specimens were exposed to cyclic superior loads during laboratory experiments. Finite element analyses of the laboratory tests were also carried out to explain the observed failure scenarios. All implants, irrespective of the particular fixation design, failed at the implant-cement interface and failure initiated at the inferior part of the component fixation. Finite element analyses indicated that this failure scenario was caused by a weak and brittle implant-cement interface and tensile stresses in the inferior region possibly worsened by a stress raiser effect at the inferior rim. The results of this study indicate that glenoid failure can be delayed or prevented by improving the implant/cement interface strength. Also any design features that reduce the geometrical stress raiser and the inferior tensile stresses in general should delay implant loosening.

Donde esten mis hijos alli que me entierren. the migration history of Aura Lila Callejas

"Adonde esten mis hijos alli que me entierren," presents the migration history of my great-aunt Aura Lila Callejas. This work utilizes the oral history method to examine one woman's migration experience in an attempt to identify various theoretical issues. Aura Lila's immigration experience sheds light on a number of different issues, including the reasons why people migrate and how they adapt to an entirely new and often frightening set of circumstances in the country of arrival. The oral history method has proven useful in presenting some of the ways in which structural factors combine with personal motivations to provide the impetus for Aura Lila's journey of international migration. My work with Aura Lila has also served to highlight some of the existing gaps in the current literature regarding Nicaraguans in the United States and the importance of the family within the overall process of migration. Finally, this work explores the nature of the relationship between the researcher and subject within the ethnographic process. While much of Aura Lila's story remains unique and specific to her family's history, her narrative can be related to the growing body of literature focusing on women's life histories.

Role of Vinculin in Regulating Force-Sensitive Dynamics of Adherens Junctions During Collective Cell Migration

Dynamic processes such as morphogenesis and tissue patterning require the precise control of many cellular processes, especially cell migration. Historically, these processes are thought to be mediated by genetic and biochemical signaling pathways. However, recent advances have unraveled a previously unappreciated role of mechanical forces in regulating these homeostatic processes in of multicellular systems. In multicellular systems cells adhere to both deformable extracellular matrix (ECM) and other cells, which are sources of applied forces and means of mechanical support. Cells detect and respond to these mechanical signals through a poorly understood process called mechanotransduction, which can have profound effects on processes such as cell migration. These effects are largely mediated by the sub cellular structures that link cells to the ECM, called focal adhesions (FAs), or cells to other cells, termed adherens junctions (AJs).

Overall this thesis is comprised of my work on identifying a novel force dependent function of vinculin, a protein which resides in both FAs and AJs - in dynamic process of collective migration. Using a collective migration assay as a model for collective cell behavior and a fluorescence resonance energy transfer (FRET) based molecular tension sensor for vinculin I demonstrated a spatial gradient of tension across vinculin in the direction of migration. To define this novel force-dependent role of vinculin in collective migration I took advantage of previously established shRNA based vinculin knock down Marin-Darby Canine Kidney (MDCK) epithelial cells.

The first part of my thesis comprises of my work demonstrating the mechanosensitive role of vinculin at AJ’s in collectively migrating cells. Using vinculin knockdown cells and vinculin mutants, which specifically disrupt vinculin’s ability to bind actin (VinI997A) or disrupt its ability to localize to AJs without affecting its localization at FAs (VinY822F), I establish a role of force across vinculin in E-cadherin internalization and clipping. Furthermore by measuring E-cadherin dynamics using fluorescence recovery after bleaching (FRAP) analysis I show that vinculin inhibition affects the turnover of E-cadherin at AJs. Together these data reveal a novel mechanosensitive role of vinculin in E-cadherin internalization and turnover in a migrating cell layer, which is contrary to the previously identified role of vinculin in potentiating E-cadherin junctions in a static monolayer.

For the last part of my thesis I designed a novel tension sensor to probe tension across N-cadherin (NTS). N-cadherin plays a critical role in cardiomyocytes, vascular smooth muscle cells, neurons and neural crest cells. Similar to E-cadherin, N-cadherin is also believed to bear tension and play a role in mechanotransduction pathways. To identify the role of tension across N-cadherin I designed a novel FRET-based molecular tension sensor for N-cadherin. I tested the ability of NTS to sense molecular tension in vascular smooth muscle cells, cardiomyocytes and cancer cells. Finally in collaboration with the Horwitz lab we have been able to show a role of tension across N-cadherin in synaptogenesis of neurons.

Understandings of transnational families in debates on Migration and development

International migration sets in motion a range of significant transnational processes that connect countries and people. How migration interacts with development and how policies might promote and enhance such interactions have, since the turn of the millennium, gained attention on the international agenda. The recognition that transnational practices connect migrants and their families across sending and receiving societies forms part of this debate. The ways in which policy debate employs and understands transnational family ties nevertheless remain underexplored. This article sets out to discern the understandings of the family in two (often intermingled) debates concerned with transnational interactions: The largely state and policydriven discourse on the potential benefits of migration on economic development, and the largely academic transnational family literature focusing on issues of care and the micro-politics of gender and generation. Emphasizing the relation between diverse migration-development dynamics and specific family positions, we ask whether an analytical point of departure in respective transnational motherhood, fatherhood or childhood is linked to emphasizing certain outcomes. We conclude by sketching important strands of inclusions and exclusions of family matters in policy discourse and suggest ways to better integrate a transnational family perspective in global migration-development policy.

Perspectives on gender, migration and transnational work: joint work of social reproduction and care in Southern Europe

This paper presents the "state of the art" and some of the main issues discussed in relation to the topic of transnational migration and reproductive work in southern Europe. We start doing a genealogy of the complex theoretical development leading to the consolidation of the research program, linking consideration of gender with transnational migration and transformation of work and ways of survival, thus making the production aspects as reproductive, in a context of globalization. The analysis of the process of multiscale reconfiguration of social reproduction and care, with particular attention to its present global dimension is presented, pointing to the turning point of this line of research that would have taken place with the beginning of this century, with the rise notions such as "global care chains" (Hochschild, 2001), or "care drain" (Ehrenreich and Hochschild, 2013). Also, the role of this new agency, now composed in many cases women who migrate to other countries or continents, precisely to address these reproductive activities, is recognized. Finally, reference is made to some of the new conceptual and theoretical developments in this area.

The Challenge of Migration and the Global Security Strategy of the European Union

This article discusses the challenges of irregular migration for the security of the EU. They are analyzed starting with the European Security Strategy 2003, and the Report on its Implementation, 2008, and notes many failures: The EU Members did not follow the directives adopted in Brussels, the mismanagement of migration and asylum policies, and numerous actions that can be characterized or described as improvised, scattered or irresponsible. The 2016 Global Strategy recognizes these failures and call attention to the European leaders to reconsider how the EU functions and operates, suggesting the need for greater unity and cooperation to achieve a more effective migration policy. However, the article points out that practically all of the sections of the new Strategy dealing with migration were already embodied in previous Strategies, and stress that in parallel with the publication of the 2016 Global Strategy, actions are already undertaken, such as the EU readmission agreements signed with several important third countries of origin.

Back to the failure: an analytic narrative of the De Lorean debacle

There has been a recent identification of a need for a New Business History. This discussion connects with the analytic narrative approach. By following this approach, the study of business history provides important implications for the conduct and institutional design of contemporary industrial policy. The approach also allows us to solve historical puzzles. The failure of the De Lorean Motor Company Limited (DMCL) is one specific puzzle. Journalistic accounts that focus on John De Lorean's alleged personality defects as an explanation for this failure miss the crucial institutional component. Moreover, distortions in the rewards associated with industrial policy, and the fact that the objectives of the institutions implementing the policy were not solely efficiency-based, led to increased opportunities for rent-seeking. Political economy solves the specific puzzle; by considering institutional dimensions, we can also solve the more general puzzle of why activist industrial policy was relatively unsuccessful in Northern Ireland.

Territoriality and Migration in a Divided Society: Lay Theories of Citizenship and Place in Northern Ireland

The study of citizenship has increasingly focused on the ways in which spatialized understandings of the concept can be used to marginalise and exclude social groups: exclusive constructions of national boundaries, local neighbourhoods and public spaces can deny marginalised groups their social and political rights. Less attention has been paid to how constructions of place can accommodate different groups’ rights and promote peaceful coexistence. This is particularly important in locations where migration disrupts existing understandings (‘lay theories’) of the relationship between residency, identity and collective rights. The present research examines how spatialized understandings of citizenship shape perceptions of intergroup mixing in previously segregated areas of a post-conflict society. Critical Discursive Social Psychological (CDSP) analysis of 30 interviews with long-term residents and recent migrants to increasingly mixed areas of Belfast shows that, while all pa
rticipants acknowledged Northern Ireland’s territorialisation, different lay theories of citizenship underpin the possibility and desirability of intergroup coexistence. Long-term residents drew upon understandings of the negative citizenry of the outgroup to argue against the possibility of peaceful coexistence within their locale, while recent incomers gave evidence of their own experiences of good citizenship within the shared spaces of neighbourhood to demonstrate that this could and should be achieved. The implications of lay theories of citizenship for the study of residential migration and mixing are discussed