Protection against Nitric Oxide-Induced Apoptosis in Rat Mesangial Cells Demands Mitogen-Activated Protein Kinases and Reduced Glutathione

ABSTRACT Inflammatory diseases such as proliferative glomerulonephritis are associated with the production of nitric oxide (NO), which can initiate apoptotic/necrotic cell death. We studied the role of the p42/44 mitogen-activated protein kinases (MAPKs) and c-Jun N-terminal kinases1/2 (JNK1/2) in NO-evoked cytotoxicity in rat mesangial cells (MC). The NO donor S-nitrosoglutathione time-and concentration-dependently promoted apoptotic cell death as detected by JNK1/2 and caspase-3 activation as well as DNA fragmentation. By using Ro 318220, a JNK1/2 activator, we established a correlation between apoptosis and JNK1/2 activation. Apoptosis is antagonized by the addition of fetal calf serum or the simultaneous generation of NO and superoxide (O 2 Ϫ ), another biological inflammatory mediator. Fetal calf serum-induced protection required p42/44 MAPK activation as inhibition of the p42/44 MAPK pathway by the MAPK kinase-1 inhibitor PD 98059 attenuated MC protection. In contrast, cytoprotection by NO/O 2 Ϫ cogeneration demanded reduced glutathione but was p42/44 MAPK unrelated. Depletion of glutathione reversed NO/O 2 Ϫ -evoked survival to cell destruction and reinstalled JNK1/2 activity. In conclusion, different signal transduction pathways facilitate protection against NO-induced JNK1/2 activation and apoptosis in rat MC

Nitric oxide and hypoxia stimulate erythropoietin receptor via MAPK kinase in endothelial cells

Erythropoietin receptor (EPOR) expression level determines the extent of erythropoietin (EPO) response. Previously we showed that EPOR expression in endothelial cells is increased at low oxygen tension and that EPO stimulation of endothelial cells during hypoxia can increase endothelial nitric oxide (NO) synthase (eNOS) expression and activation as well as NO production. We now observe that while EPO can stimulate NO production, NO in turn can regulate EPOR expression. Human umbilical vein endothelial cells (HUVEC) treated with 10-50 pM of NO donor diethylenetriamine NONOate (DETANO) for 24 h showed significant induction of EPOR gene expression at 5% and 2% of oxygen. Also human bone marrow microvascular endothelial cell line (TrHBMEC) cultured at 21 and 2% oxygen with 50 uM DETANO demonstrated a time and oxygen dependent induction of EPOR mRNA expression after 24 and 48 h, particularly at low oxygen tension. EPOR protein was also induced by DETANO at 2% oxygen in TrHBMEC and HUVEC. The activation of signaling pathways by NO donor stimulation appeared to be distinct from EPO stimulation. In reporter gene assays, DETANO treatment of HeLa cells at 2% oxygen increased EPOR promoter activity indicated by a 48% increase in luciferase activity with a 2 kb EPOR promoter fragment and a 71% increase in activity with a minimal EPOR promoter fragment containing 0.2 kb 5'. We found that DETANO activated MAPK kinase in TrHBMEC both in normoxia and hypoxia, while MAPK kinase inhibition showed significant reduction of EPOR mRNA gene expression at low oxygen tension, suggesting MAPK involvement in NO mediated induction of EPOR Furthermore, DETANO stimulated Ala anti-apoptotic activity after 30 min in normoxia, whereas it inhibited Akt phosphorylation in hypoxia. In contrast, EPO did not significantly increase MAPK activity while EPO stimulated Akt phosphorylation in TrHBMEC in normoxia and hypoxia. These observations provide a new effect of NO on EPOR expression to enhance EPO response in endothelial cells, particularly at low oxygen tensions

Nitric Oxide Induces Cell Death by Regulating Anti-Apoptotic BCL-2 Family Members

Nitric oxide (NO) activates the intrinsic apoptotic pathway to induce cell death. However, the mechanism by which this pathway is activated in cells exposed to NO is not known. Here we report that BAX and BAK are activated by NO and that cytochrome c is released from the mitochondria. Cells deficient in Bax and Bak or Caspase-9 are completely protected from NO-induced cell death. The individual loss of the BH3-only proteins, Bim, Bid, Puma, Bad or Noxa, or Bid knockdown in Bim−/−/Puma−/− MEFs, does not prevent NO-induced cell death. Our data show that the anti-apoptotic protein MCL-1 undergoes ASK1-JNK1 mediated degradation upon exposure to NO, and that cells deficient in either Ask1 or Jnk1 are protected against NO-induced cell death. NO can inhibit the mitochondrial electron transport chain resulting in an increase in superoxide generation and peroxynitrite formation. However, scavengers of ROS or peroxynitrite do not prevent NO-induced cell death. Collectively, these data indicate that NO degrades MCL-1 through the ASK1-JNK1 axis to induce BAX/BAK-dependent cell death

Home-making: Architects, users and the 'prefab'

It seems a fact that modern architecture still has not reached people at home, within their own four walls. I was therefore seeking for an instrument which bears the potential of bringing architects and users into closer contact, and found it with the prefabricated house. Making use of prefabrication for domestic architecture involves a third partner, the building industry. Consequentially, I have explored ways of forming fruitful collaborations between architects, users and the building industry, for a "trialectic"1 design of a home. My report is structured into two parts: in PART I, I investigate the peculiar reputation of the pre fabricated house, being historically split into a modernist, "architectural" and a commercial, "non- architectural" development. The first represents the architectural profession, the latter the building industry, which succeeded where modernism failed—in reaching the wider public. This leads to two different points of view looking at the 'prefab': the architect's and the housing industry's view, representing the mass of homebuilders. For understanding these, I shed light onto the characteristics of architectural practice, the particular meaning of 'home' and the demands and needs of the user, resulting in contrary under standings of the 'design' of a home. Concerning the last point, the field of participation in architecture demonstrates how architect and user can be united into a—very particular—building project. Complementing the first part—the theory, PART II illustrates the thoughts and ideas with the help of built examples—the practice. I therefore present a collection of recent projects in prefabricated housing, as a 'catalogue' of the recent state of affairs. The precondition for selecting a model was that each had to include elements of modern architecture, participation and prefabrication—enabling a trialectic design. Since there are very different attempts to use prefabrication, I divided the case studies into five categories and set up an overall tabular list for evaluation. This enables the reader a quick overview and an easy comparison of all models and evokes questions regarding social, political, economical, architectural and urban issues. Form and contents of my report express that there are various elements with potential for an application for a contemporary home. If I regarded the built environment as a 'catalogue', it would be possible to extract valuable elements for a particular home, setting the elements together in the required way. This does not mean to take a window here and a roof there, but adopting and transforming existing ideas how to tackle current questions related to a quality modern home, which is equally created by architect and user

60 GHz Pulsradar zur Detektion von Hochspannungsleitungen Schlussbericht

With 39 figs.SIGLEDEGerman

Structural investigations of silicon nanostructures grown by self-organized island formation for photovoltaic applications

The self-organized growth of crystalline silicon nanodots and their structural characteristics are investigated. For the nanodot synthesis, thin amorphous silicon (a-Si) layers with different thicknesses have been deposited onto the ultrathin (2 nm) oxidized (111) surface of Si wafers by electron beam evaporation under ultrahigh vacuum conditions. The solid phase crystallization of the initial layer is induced by a subsequent in situ annealing step at 700°C, which leads to the dewetting of the initial a-Si layer. This process results in the self-organized formation of highly crystalline Si nanodot islands. Scanning electron microscopy confirms that size, shape, and planar distribution of the nanodots depend on the thickness of the initial a-Si layer. Cross-sectional investigations reveal a single-crystalline structure of the nanodots. This characteristic is observed as long as the thickness of the initial a-Si layer remains under a certain threshold triggering coalescence. The underlying ultra-thin oxide is not structurally affected by the dewetting process. Furthermore, a method for the fabrication of close-packed stacks of nanodots is presented, in which each nanodot is covered by a 2 nm thick SiO 2 shell. The chemical composition of these ensembles exhibits an abrupt Si/SiO 2 interface with a low amount of suboxides. A minority charge carrier lifetime of 18 μs inside of the nanodots is determined. © 2012 Springer-Verlag

Abstracting Interaction Patterns: A Programming Paradigm for Open Distributed Systems

This paper discusses mechanisms addressing the complexity of building and maintaining Open Distributed Systems. It is argued that a new programming paradigm based on modular specification of interaction patterns is required to address the complexity of such systems. Our research is based on developing abstraction mechanisms to simplify the task of developing and maintaining open systems. We define actors as a model of concurrency for open systems. We then review a number of programming abstractions that are useful in modular specification an..