Exploring the biophysical evidence that mammalian two pore channels are NAADP-activated calcium-permeable channels

Nicotinic acid adenine dinucleotide phosphate (NAADP) potently releases Ca2+ from acidic intracellular endo-lysosomal Ca2+-stores. It is widely accepted that two types of two pore channels, termed TPC1 and TPC2, are responsible for the NAADP-mediated Ca2+-release but the underlying mechanisms regulating their gating appear to be different. For example, although both TPC1 and TPC2 are activated by NAADP, TPC1 appears to be additionally regulated by cytosolic Ca2+. Ion conduction and permeability also differ markedly. TPC1 and TPC2 are permeable to a range of cations although biophysical experiments suggest that TPC2 is slightly more selective for Ca2+ over K+ than TPC1 and hence capable of releasing greater quantities of Ca2+ from acidic stores. TPC1 is also permeable to H+ and therefore may play a role in regulating lysosomal and cytosolic pH, possibly creating localised acidic domains. The significantly different gating and ion conducting properties of TPC1 and TPC2 suggest that these two ion channels may play complementary physiological roles as Ca2+ release channels of the endo-lysosomal system.PostprintPeer reviewe

Process of discovery: A fourth-year translational science course

The Liaison Committee on Medical Education notes the importance of educating medical students on clinical and translational research principles.To describe a fourth-year course, “Process of discovery,” which addresses teaching these principles, and to discuss students’ perceptions of the course.Core components and pedagogical methods of this course are presented. Course assessment was performed with specific pre- and post-course assessments.During academic years 2004 to 2009, 562 students were enrolled, with assessment response rate of 94% pre-course and 85% post-course. The students’ self-assessment of their current understanding of clinical and translation research significantly increased, as well as their understanding of how clinical advances will take place over the next decade.A fourth-year course teaching clinical and translational research is successful, is seen as a positive experience and can meet the requirements for including clinical and translational research in the medical school curriculum

Growth-in-place deployment of in-plane silicon nanowires

International audienceUp-scaling silicon nanowire (SiNW)-based functionalities requires a reliable strategy to precisely position and integrate individual nanowires. We here propose an all-in-situ approach to fabricate self-positioned/aligned SiNW, via an in-plane solid-liquid-solid growth mode. Prototype field effect transistors, fabricated out of in-plane SiNWs using a simple bottom-gate configuration, demonstrate a hole mobility of 228 cm2/V s and on/off ratio >103. Further insight into the intrinsic doping and structural properties of these structures was obtained by laser-assisted 3 dimensional atom probe tomography and high resolution transmission electron microscopy characterizations. The results could provide a solid basis to deploy the SiNW functionalities in a cost-effective way

Dysregulated Zn2+ homeostasis impairs cardiac type-2 ryanodine receptor and mitsugumin 23 functions, leading to sarcoplasmic reticulum Ca2+ leakage

SJP is supported by a Royal Society of Edinburgh Biomedical Fellowship. Benedict Reilly-O’Donnell is supported by a University of St Andrews 600th Anniversary Scholarship. This work was supported by the British Heart Foundation (grant no: FS/14/69/31001 to SJP) and the Japan Society for the Promotion of Science (Core-to-Core Program awarded to HT).Aberrant Zn2+ homeostasis is associated with dysregulated intracellular Ca2+ release, resulting in chronic heart failure. In the failing heart a small population of cardiac ryanodine receptors (RyR2) displays sub-conductance-state gating leading to Ca2+ leakage from sarcoplasmic reticulum (SR) stores, which impairs cardiac contractility. Previous evidence suggests contribution of RyR2-independent Ca2+ leakage through an uncharacterized mechanism. We sought to examine the role of Zn2+ in shaping intracellular Ca2+ release in cardiac muscle. Cardiac SR vesicles prepared from sheep or mouse ventricular tissue were incorporated into phospholipid bilayers under voltage-clamp conditions, and the direct action of Zn2+ on RyR2 channel function was examined. Under diastolic conditions, the addition of pathophysiological concentrations of Zn2+ (≥2 nm) caused dysregulated RyR2-channel openings. Our data also revealed that RyR2 channels are not the only SR Ca2+-permeable channels regulated by Zn2+. Elevating the cytosolic Zn2+ concentration to 1 nm increased the activity of the transmembrane protein mitsugumin 23 (MG23). The current amplitude of the MG23 full-open state was consistent with that previously reported for RyR2 sub-conductance gating, suggesting that in heart failure in which Zn2+ levels are elevated, RyR2 channels do not gate in a sub-conductance state, but rather MG23-gating becomes more apparent. We also show that in H9C2 cells exposed to ischemic conditions, intracellular Zn2+ levels are elevated, coinciding with increased MG23 expression. In conclusion, these data suggest that dysregulated Zn2+ homeostasis alters the function of both RyR2 and MG23 and that both ion channels play a key role in diastolic SR Ca2+ leakage.Publisher PDFPeer reviewe

Population genomics of the Asian tiger mosquito, Aedes albopictus. Insights into the recent worldwide invasion

Aedes albopictus, the “Asian tiger mosquito,” is an aggressive biting mosquito native to Asia that has colonized all continents except Antarctica during the last ~30–40 years. The species is of great public health concern as it can transmit at least 26 arboviruses, including dengue, chikungunya, and Zika viruses. In this study, using double- digest Restriction site-Associated DNA (ddRAD) sequencing, we developed a panel of ~58,000 single nucleotide polymorphisms (SNPs) based on 20 worldwide Ae. albopic-tus populations representing both the invasive and the native range. We used this genomic- based approach to study the genetic structure and the differentiation of Ae. albopictus populations and to understand origin(s) and dynamics of the recent inva-sions. Our analyses indicated the existence of two major genetically differentiated population clusters, each one including both native and invasive populations. The de-tection of additional genetic structure within each major cluster supports that these SNPs can detect differentiation at a global and local scale, while the similar levels of genomic diversity between native and invasive range populations support the scenario of multiple invasions or colonization by a large number of propagules. Finally, our re-sults revealed the possible source(s) of the recent invasion in Americas, Europe, and Africa, a finding with important implications for vector- control strategies

La croissance plasma de nanofils de silicium catalysée par l'étain et l'indium et applications dans les cellules solaires à jonctions radiales.

In this thesis, disordered arrays of vertical silicon nanowires are used to trap light in PECVD-deposited silicon solar cells. The abrupt surface which they present can absorb light efficiently and be manufactured in the same vacuum run as the other layers of the cell, offering the prospect of dispensing with the additional fabrication steps conventionally required to texture the substrates of thin-film photovoltaics. Drops of liquid tin and indium, designed to catalyze the growth of silicon nanowires, were deposited and rearranged on transparent conducting oxide substrates under vacuum to obtain metal drop configurations with diameters and densities spanning several orders of magnitude. In discussing the suitability of different metals to catalyze the growth of silicon nanowires, we have highlighted distinctions between the behavior of transition and non-transition metals for vapor-liquid-solid growth and studied in particular the case of silicon nanowires catalyzed by tin. Nanowires doped P-type with the appropriate morphology were covered in conformal layers of intrinsic and N-type hydrogenated amorphous silicon, and an indium-tin-oxide electrical contact to produce networks of 107 radial PIN junctions connected over areas of 3.1 mm². Optimizing the fabrication process of these devices has led to open-circuit voltages of 0.8 V and short-circuit currents of 13 mA/cm². The cells are deposited over untextured substrates using techniques which are compatible with a single pump-down process. Their ability to trap light rivals that of established texturing techniques and their performance comes close to that of planar PIN structures.Cette thèse présente des cellules solaires en silicium deposées par plasma dans lesquelles la lumière est piégée par un réseau désorganisé de nanofils de silicium. Le dépôt sous vide des nanofils permet de contourner les étapes de texturation de substrat typiquement requises pour augmenter le parcours moyen des photons dans les cellules solaires en couches minces classiques. Des gouttes d'étain et d'indium servant à catalyser la croissance de ces nanofils ont été déposées et disposées sous vide sur des substrats d'oxide trasparent conducteur. Des agencements de gouttes métalliques aux diamètres et densités couvrant plusieurs ordres de grandeur ont été obtenus en optimisant les matériaux et les conditions de dépôt utilisés. En comparant l'aptitude de différents métaux à catalyser la croissance de nanofils de silicium, des distinctions majeures ont été établies entre les métaux de transition et Sn, In, Bi, Ga, Pb et Al. Le cas des nanofils de silicium catalysés par des gouttes d'étain a été étudié en profondeur. Des réseaux désorganisés de nanofils dopés de type P ont été recouverts de couches de silicium amorphe hydrogéné intrinsèque et dopés N, ainsi que d'une couche d'oxide d'ITO pour former des réseaux de 107 jonctions PIN radiales couvrant des surfaces de 3,1 mm². Ces cellules présentent des tensions à circuit ouvert de 0,8 V et des courants de court-circuit de 13 mA/cm² bien qu'elles soient entièrement déposées par des étapes sous vide sur des substrats non texturés

Investigating the role of Zn²⁺ in regulating the function of intracellular Ca²⁺-release channels

The tightly regulated openings of the cardiac ryanodine receptor (RyR2) help to ensure that intracellular Ca²⁺- release from the sarcoplasmic reticulum (SR) can only occur when heart contractions are required. Usually this process is self-regulatory, where Ca²⁺ both activates and inhibits release of further Ca²⁺ from the SR. In the progression of heart failure some of this control is lost and in rest periods Ca²⁺ can leak from the SR into the cytosol. Recent evidence has suggested that Zn²⁺- dyshomeostasis may contribute to SR Ca²⁺- leak but the underlying mechanism is unclear. Using single channel electrophysiological studies in combination with live cell imaging of HEK 293 and fibroblasts, this study reveals that Zn²⁺, along with Ca²⁺ and the inhibitor Mg²⁺, plays a physiological role in the grading of Ca²⁺- release via RyR2. Importantly the data reveal that pathophysiological concentrations of Zn²⁺ (> 100pM) within the cytosol remove the requirement of Ca²⁺ to activate RyR2, resulting in irregular channel activity even in the presence of Mg²⁺. This increase in channel open probability due to Zn²⁺ is known to be associated with increased Ca²⁺- release events such as Ca²⁺ sparks suggesting that Zn²⁺ is a regulator of the SR Ca²⁺-leak current. A potential source of releasable Zn²⁺, which could modulate RyR2 activity in cardiomyocytes, are the acidic organelles (endosomes and lysosomes). This study provides key evidence that the two pore channels (TPCs), which are expressed on the surface of these organelles, are candidate channels for ligand-gated release of Zn²⁺. Importantly this research demonstrates that dysregulated Zn²⁺ homeostasis, resulting in elevated Zn²⁺ within the lysosome, has severe consequences upon cellular Ca²⁺- release from fibroblasts, which is primarily the result of Zn²⁺ acting as a pore blocker of TPC2. Together these data reveal a key role of Zn²⁺ as a second messenger which can regulate intracellular Ca²⁺- release in both health and disease

La croissance plasma de nanofils de silicium catalysée par l'étain et l'indium et applications dans les cellules solaires à jonctions radiales

Cette thèse présente des cellules solaires en silicium deposées par plasma dans lesquelles la lumière est piégée par un réseau désorganisé de nanofils de silicium. Le dépôt sous vide des nanofils permet de contourner les étapes de texturation de substrat typiquement requises pour augmenter le parcours moyen des photons dans les cellules solaires en couches minces classiques. Des gouttes d'étain et d'indium servant à catalyser la croissance de ces nanofils ont été déposées et disposées sous vide sur des substrats d'oxide trasparent conducteur. Des agencements de gouttes métalliques aux diamètres et densités couvrant plusieurs ordres de grandeur ont été obtenus en optimisant les matériaux et les conditions de dépôt utilisés. En comparant l'aptitude de différents métaux à catalyser la croissance de nanofils de silicium, des distinctions majeures ont été établies entre les métaux de transition et Sn, In, Bi, Ga, Pb et Al. Le cas des nanofils de silicium catalysés par des gouttes d'étain a été étudié en profondeur. Des réseaux désorganisés de nanofils dopés de type P ont été recouverts de couches de silicium amorphe hydrogéné intrinsèque et dopés N, ainsi que d'une couche d'oxide d'ITO pour former des réseaux de 107 jonctions PIN radiales couvrant des surfaces de 3,1 mm . Ces cellules présentent des tensions à circuit ouvert de 0,8 V et des courants de court-circuit de 13 mA/cm bien qu'elles soient entièrement déposées par des étapes sous vide sur des substrats non texturésIn this thesis, disordered arrays of vertical silicon nanowires are used to trap light in PECVD-deposited silicon solar cells. The abrupt surface which they present can absorb light efficiently and be manufactured in the same vacuum run as the other layers of the cell, offering the prospect of dispensing with the additional fabrication steps conventionally required to texture the substrates of thin-film photovoltaics. Drops of liquid tin and indium, designed to catalyze the growth of silicon nanowires, were deposited and rearranged on transparent conducting oxide substrates under vacuum to obtain metal drop configurations with diameters and densities spanning several orders of magnitude. In discussing the suitability of different metals to catalyze the growth of silicon nanowires, we have highlighted distinctions between the behavior of transition and non-transition metals for vapor-liquid-solid growth and studied in particular the case of silicon nanowires catalyzed by tin. Nanowires doped P-type with the appropriate morphology were covered in conformal layers of intrinsic and N-type hydrogenated amorphous silicon, and an indium-tin-oxide electrical contact to produce networks of 107 radial PIN junctions connected over areas of 3.1 mm . Optimizing the fabrication process of these devices has led to open-circuit voltages of 0.8 V and short-circuit currents of 13 mA/cm . The cells are deposited over untextured substrates using techniques which are compatible with a single pump-down process. Their ability to trap light rivals that of established texturing techniques and their performance comes close to that of planar PIN structuresPALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

Children's "Euthanasia" in Nazi Germany

Children with disabilities were killed during the Nazi era, often by nurses. Some nurses killed children, saying that they were under orders. Propaganda about the need for "racial purity" was all pervasive and influenced much of the population, including nurses. The German people accepted the "mercy" killing of children with disabilities. We describe the children's "euthanasia" program, explore the influence of propaganda, ask why it was acceptable to kill children, and provide historical context demonstrating "slippery slopes" which can lead to abrogation of ethical principles. Discussion of such history is essential as the ethical principles which were breached are still the cornerstone of nursing practice today. Only by openly discussing past wrongs can we attempt to ensure that they do not happen again. Archival documents from Germany and Israel, including trial depositions and transcripts, provided material, supplemented by secondary classic sources