Low Density Lipoproteins as Circulating Fast Temperature Sensors

Background: The potential physiological significance of the nanophase transition of neutral lipids in the core of low density lipoprotein (LDL) particles is dependent on whether the rate is fast enough to integrate small (62uC) temperature changes in the blood circulation. Methodology/Principal Findings: Using sub-second, time-resolved small-angle X-ray scattering technology with synchrotron radiation, we have monitored the dynamics of structural changes within LDL, which were triggered by temperature-jumps and-drops, respectively. Our findings reveal that the melting transition is complete within less than 10 milliseconds. The freezing transition proceeds slowly with a half-time of approximately two seconds. Thus, the time period over which LDL particles reside in cooler regions of the body readily facilitates structural reorientation of the apolar core lipids. Conclusions/Significance: Low density lipoproteins, the biological nanoparticles responsible for the transport of cholesterol in blood, are shown to act as intrinsic nano-thermometers, which can follow the periodic temperature changes during blood circulation. Our results demonstrate that the lipid core in LDL changes from a liquid crystalline to an oily state within fractions of seconds. This may, through the coupling to the protein structure of LDL, have important repercussions o

The glycerol backbone of phospholipids derives from noncarbohydrate precursors in starved lung cancer cells

Cancer cells are reprogrammed to consume large amounts of glucose to support anabolic biosynthetic pathways. However, blood perfusion and consequently the supply with glucose are frequently inadequate in solid cancers. PEPCK-M (PCK2), the mitochondrial isoform of phosphoenolpyruvate carboxykinase (PEPCK), has been shown by us and others to be functionally expressed and to mediate gluconeogenesis, the reverse pathway of glycolysis, in different cancer cells. Serine and ribose synthesis have been identified as downstream pathways fed by PEPCK in cancer cells. Here, we report that PEPCK-M-dependent glycerol phosphate formation from noncarbohydrate precursors (glyceroneogenesis) occurs in starved lung cancer cells and supports de novo glycerophospholipid synthesis. Using stable isotope-labeled glutamine and lactate, we show that PEPCK-M generates phosphoenolpyruvate and 3-phosphoglycerate, which are at least partially converted to glycerol phosphate and incorporated into glycerophospholipids (GPL) under glucose and serum starvation. This pathway is required to maintain levels of GPL, especially phosphatidylethanolamine (PE), as shown by stable shRNA-mediated silencing of PEPCK-M in H23 lung cancer cells. PEPCK-M shRNA led to reduced colony formation after starvation, and the effect was partially reversed by the addition of dioleyl-PE. Furthermore, PEPCK-M silencing abrogated cancer growth in a lung cancer cell xenograft model. In conclusion, glycerol phosphate formation for de novo GPL synthesis via glyceroneogenesis is a newly characterized anabolic pathway in cancer cells mediated by PEPCK-M under conditions of severe nutrient deprivation

Influence of ischemic core muscle fibers on surface depolarization potentials in superfused cardiac tissue preparations: a simulation study

Thin-walled cardiac tissue samples superfused with oxygenated solutions are widely used in experimental studies. However, due to decreased oxygen supply and insufficient wash out of waste products in the inner layers of such preparations, electrophysiological functions could be compromised. Although the cascade of events triggered by cutting off perfusion is well known, it remains unclear as to which degree electrophysiological function in viable surface layers is affected by pathological processes occurring in adjacent tissue. Using a 3D numerical bidomain model, we aim to quantify the impact of superfusion-induced heterogeneities occurring in the depth of the tissue on impulse propagation in superficial layers. Simulations demonstrated that both the pattern of activation as well as the distribution of extracellular potentials close to the surface remain essentially unchanged. This was true also for the electrophysiological properties of cells in the surface layer, where most relevant depolarization parameters varied by less than 5.5 %. The main observed effect on the surface was related to action potential duration that shortened noticeably by 53 % as hypoxia deteriorated. Despite the known limitations of such experimental methods, we conclude that superfusion is adequate for studying impulse propagation and depolarization whereas repolarization studies should consider the influence of pathological processes taking place at the core of tissue sample

Beveridge on idleness

Beveridge's wartime proposals to eliminate idleness relied on the precepts of Keynesian economics and substantial extensions in the powers of central government to regulate industry and labour. Using convention theory, this paper demonstrates how these stipulations proved politically untenable. With the disappearance of full employment in the 1980s, the labour market problems Beveridge encountered in his youth have re-emerged accompanied by old problems of working poverty. Established forms of labour market analysis are obsolescent and employment rights disappear. The paper suggests a more decentralized and variable analysis of relations between work and idleness may offer a way forward

Novel genetically encoded fluorescent probes enable real-time detection of potassium in vitro and in vivo

Changes in intra-and extracellular potassium ion (K+) concentrations control many important cellular processes and related biological functions. However, our current understanding of the spatiotemporal patterns of physiological and pathological K+ changes is severely limited by the lack of practicable detection methods. We developed K+-sensitive genetically encoded, Forster resonance energy transfer-(FRET) based probes, called GEPIIs, which enable quantitative real-time imaging of K+ dynamics. GEPIIs as purified biosensors are suitable to directly and precisely quantify K+ levels in different body fluids and cell growth media. GEPIIs expressed in cells enable time-lapse and real-time recordings of global and local intracellular K+ signals. Hitherto unknown Ca2+-triggered, organelle-specific K+ changes were detected in pancreatic beta cells. Recombinant GEPIIs also enabled visualization of extracellular K+ fluctuations in vivo with 2-photon microscopy. Therefore, GEPIIs are relevant for diverse K+ assays and open new avenues for live-cell K+ imaging

Viking, Laval and beyond /

"EU Law in the Member States is a new series dedicated to exploring the impact of landmark CJEU judgments and secondary legislation in legal systems across the European Union. Each book will be written by a team of generalist EU lawyers and experts in the relevant field, bringing together perspectives from a wide range of different member states in order to compare and analyse the effect of EU law on domestic legal systems and practice. The first volume focuses on the uneasy relationship between the economic freedoms enshrined in Articles 49 and 56 TFEU and workers' right to take collective action. This conflict has been at the forefront of EU Labour law since the CJEU's much-discussed decisions in C-438/05 Viking and C-341/04 Laval, as well as the Commission's more recent attempts at legislative reforms in the failed Monti II Regulation. Viking, Laval and Beyond explores judicial and legislative responses to these measures in ten member states, and finds that the impact on domestic legal systems has been much more varied than traditional accounts of EU law would suggest."--Bloomsbury Publishing