Evidence for bystander signalling between human trophoblast cells and human embryonic stem cells

Maternal exposure during pregnancy to toxins can occasionally lead to miscarriage and malformation. It is currently thought that toxins pass through the placental barrier, albeit bilayered in the first trimester, and damage the fetus directly, albeit at low concentration. Here we examined the responses of human embryonic stem (hES) cells in tissue culture to two metals at low concentration. We compared direct exposures with indirect exposures across a bi-layered model of the placenta cell barrier. Direct exposure caused increased DNA damage without apoptosis or a loss of cell number but with some evidence of altered differentiation. Indirect exposure caused increased DNA damage and apoptosis but without loss of pluripotency. This was not caused by metal ions passing through the barrier. Instead the hES cells responded to signalling molecules (including TNF-α) secreted by the barrier cells. This mechanism was dependent on connexin 43 mediated intercellular ‘bystander signalling’ both within and between the trophoblast barrier and the hES colonies. These results highlight key differences between direct and indirect exposure of hES cells across a trophoblast barrier to metal toxins. It offers a theoretical possibility that an indirectly mediated toxicity of hES cells might have biological relevance to fetal development

Closed circuits : kinship, neighborhood and incarceration in urban Portugal

The notion that prisons are a ‘world apart’, with their walls severing prisoners from their external relationships, and incarceration an interruption, ‘time away’ spent in a separate social universe, has provided an adequate framework for understanding the social realities of imprisonment in the past. But it has also created an analytical dead angle that prevents us from identifying the ramifying social effects of concentrated incarceration upon both the prison and heavily penalized lower-class neighborhoods. This article addresses these effects with data from an ethnographic revisit of a major women’s prison in Portugal, where the recomposition of the inmate population that has accompanied the rapid inflation of the country’s carceral population is especially pronounced and entails the activation of wide-ranging carceralized networks bringing kinship and neighborhood into the prison as well as the prison into the domestic world. The analysis focuses on the ways whereby these constellations have transformed the experience of confinement and the texture of correctional life, calling for a reconsideration of the theoretical status of the prison as a ‘total institution’ and for exploring anew the boundary that separates it (or not) from outside worlds.Wenner-Gren Foundation for Anthropological Research

Exchange Rate Policy And The Management Of Official And Private Capital Flows In Africa

During the 1990s a number of African central banks succeeded in bringing inflation to relatively low levels while maintaining a market-determined exchange rate. These central banks were generally reluctant to fully subordinate exchange rate targets to monetary targets, however, particularly in the face of large external shocks. We focus on the management of highly persistent shocks to aid flows, including PRSP-related increases in net flows, in the presence of currency substitution by the domestic private sector. Such shocks have beneficent long-run effects, but when currency substitution is high they can produce dramatic. macroeconomic management problems in the short run. What is the appropriate mix of money and exchange rate targeting in such cases, and the role of temporary sterilization? We analyze these and related issues in an intertemporal optimizing model that allows a portion of aid to be devoted to reducing the government\u27s seigniorage requirement. This creates a strong link between official aid flows and private capital flows, giving rise to trade-offs reminiscent of the literature on private capital inflows in emerging markets. When the credibility of policymakers\u27 commitment to low inflation is firm, some degree of dirty floating, with little or no sterilization of increases in the monetary base, is the most attractive approach