Search

Nanophotonics is becoming invaluable for an expanding range of applications, from controlling the spontaneous emission rate and the directionality of quantum emitters, to reducing material requirements of solar cells by an order of magnitude. These effects are highly dependent on the near field of the nanostructure, which constitutes the evanescent fields from propagating and resonant localized modes. Although the interactions between quantum emitters and nanophotonic structures are increasingly well understood theoretically, directly imaging these interactions experimentally remains challenging. Here we demonstrate a photoactivated localization microscopy-based technique to image emitter-nanostructure interactions. For a 75 nm diameter silicon nanowire, we directly observe a confluence of emission rate enhancement, directivity modification and guided mode excitation, with strong interaction at scales up to 13 times the nanowire diameter. Furthermore, through analytical modelling we distinguish the relative contribution of these effects, as well as their dependence on emitter orientation.

Nanophotonic engineering shows great potential for photovoltaics: the record conversion efficiencies of nanowire solar cells are increasing rapidly and the record open-circuit voltages are becoming comparable to the records for planar equivalents. Furthermore, it has been suggested that certain nanophotonic effects can reduce costs and increase efficiencies with respect to planar solar cells. These effects are particularly pronounced in single-nanowire devices, where two out of the three dimensions are subwavelength. Single-nanowire devices thus provide an ideal platform to study how nanophotonics affects photovoltaics. However, for these devices the standard definition of power conversion efficiency no longer applies, because the nanowire can absorb light from an area much larger than its own size. Additionally, the thermodynamic limit on the photovoltage is unknown a priori and may be very different from that of a planar solar cell. This complicates the characterization and optimization of these devices. Here, we analyse an InP single-nanowire solar cell using intrinsic metrics to place its performance on an absolute thermodynamic scale and pinpoint performance loss mechanisms. To determine these metrics we have developed an integrating sphere microscopy set-up that enables simultaneous and spatially resolved quantitative absorption, internal quantum efficiency (IQE) and photoluminescence quantum yield (PLQY) measurements. For our record single-nanowire solar cell, we measure a photocurrent collection efficiency of >90% and an open-circuit voltage of 850 mV, which is 73% of the thermodynamic limit (1.16 V).

Apheresis was first performed as a therapeutic procedure in the 1950s. The first national therapeutic apheresis (TA) registry was established in Canada in 1981 and other national registries followed, including two attempts at establishing an international TA registry. There is no national registry in the United States. Our large, academic, tertiary hospital has a very active TA service. We created a TA database to track all procedures performed by the apheresis service by transferring data from paper appointment logs and the electronic medical records into a Microsoft Access database. Retrospective data from each TA procedure performed at UAB from January 1, 2003 through December 31, 2012 were entered, including the type of procedure, indication, date, and patient demographics. Microsoft Excel was used for data analysis. During the 10-year period, our TA service treated 1,060 patients and performed 11,718 procedures. Of these patients, 70% received therapeutic plasma exchange (TPE), 21% received extracorporeal photopheresis (ECP), 4.5% received red cell exchange (RCE), 4.2% received leukocytapheresis, and 0.6% underwent platelet depletion. Among the procedures, 54% were TPEs, 44% were ECPs, 1.3% were RCEs, 0.5% were leukocytaphereses, and 0.1% were platelet depletions. According to the current literature, national and international TA use is underreported. We believe that the UAB TA registry provides useful information about TA practices in our region and can serve as a model for other institutions. Furthermore, data from multiple institutional registries can be used for clinical research to increase the available evidence for the role of TA in various conditions. J. Clin. Apheresis 31:516-522, 2016. © 2015 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Background: Hydroxyethyl starch (HES) is reportedly associated with an increased risk of renal failure and death when used for fluid resuscitation in critically ill patients. HES can be used during therapeutic leukocytapheresis (TL) procedures to enhance cell separation. The purpose of this study was to evaluate the occurrence of adverse events associated with HES during TL procedures., Study Design and Methods: We performed a retrospective review of patients who underwent TL with and without HES in the period 2009 to 2013 at six academic medical institutions., Results: A difference-in-difference regression analysis was used to estimate the mean change before and after TL in selected outcomes in the HES group relative to the average change in the non-HES group. Selected outcomes included serum creatinine, estimated glomerular filtration rate (eGFR), and white blood cell (WBC) count. A total of 195 patients who underwent 278 TL procedures were studied. We found no significant differences in serum creatinine levels and eGFR on Days 1 and 7 after TL procedure between patients who received and those who did not receive HES. The rate of adverse events and overall and early mortality were similar in both groups. Patients with acute myeloid leukemia who received HES had greater WBC reduction when HES was used. Additionally, patients who received HES had improvement in pulmonary leukostasis symptoms., Conclusion: HES, used at low doses during TL procedures, was not associated with adverse events previously ascribed to its use as a volume expander., (© 2016 AABB.)

In-silico models of human cardiac electrophysiology are now being considered for prediction of cardiotoxicity as part of the preclinical assessment phase of all new drugs. We ask the question whether any of the available models are actually fit for this purpose. We tested three models of the human ventricular action potential, the O'hara-Rudy (ORD11), the Grandi-Bers (GB10) and the Ten Tusscher (TT06) models. We extracted clinical QT data for LQTS1 and LQTS2 patients with nonsense mutations that would be predicted to cause 50% loss of function in I Ks and I Kr respectively. We also obtained clinical QT data for LQTS3 patients. We then used a global optimization approach to improve the existing in silico models so that they reproduced all three clinical data sets more closely. We also examined the effects of adrenergic stimulation in the different LQTS subsets. All models, in their original form, produce markedly different and unrealistic predictions of QT prolongation for LQTS1, 2 and 3. After global optimization of the maximum conductances for membrane channels, all models have similar current densities during the action potential, despite differences in kinetic properties of the channels in the different models, and more closely reproduce the prolongation of repolarization seen in all LQTS subtypes. In-silico models of cardiac electrophysiology have the potential to be tremendously useful in complementing traditional preclinical drug testing studies. However, our results demonstrate they should be carefully validated and optimized to clinical data before they can be used for this purpose., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Approaching the theoretically limiting open circuit voltage (V oc ) of solar cells is crucial to optimize their photovoltaic performance. Here, we demonstrate experimentally that nanostructured layers can achieve a fundamentally larger Fermi level splitting, and thus a larger V oc , than planar layers. By etching tapered nanowires from planar indium phosphide (InP), we directly compare planar and nanophotonic geometries with the exact same material quality. We show that the external radiative efficiency of the nanostructured layer at 1 sun is increased by a factor 14 compared to the planar layer, leading to a 70 mV enhancement in V oc . The higher voltage arises from both the enhanced outcoupling of photons, which promotes radiative recombination, and the lower active material volume, which reduces bulk recombination. These effects are generic and promise to enhance the efficiency of current record planar solar cells made from other materials as well.

Nanophotonic engineering holds great promise for photovoltaics, with several recently proposed approaches that have enabled efficiencies close to the Shockley-Queisser limit. Here, we theoretically demonstrate that suitably designed nanophotonic structures may be able to surpass the 1 sun Shockley-Queisser limit by utilizing tailored directivity of the scattering response of nanoparticles. We show that large absorption cross sections do not play a significant role in the efficiency enhancement, and on the contrary, directivity enhancement constitutes the nanoscale equivalent to concentration in macroscopic photovoltaic systems. Based on this principle, we discuss fundamental limits to the efficiency based on directivity bounds and a number of approaches to get close to these limits. We also highlight that, in practice, achieving efficiencies above the Shockley-Queisser limit is strongly hindered by whether high short-circuit currents can be maintained. Finally, we discuss how our results are affected by the presence of significant nonradiative recombination, in which case both directivity and photon escape probability should be increased to achieve voltage enhancement.

Key Points: Most missense long QT syndrome type 2 (LQTS2) mutations result in Kv11.1 channels that show reduced levels of membrane expression. Pharmacological chaperones that rescue mutant channel expression could have therapeutic potential to reduce the risk of LQTS2-associated arrhythmias and sudden cardiac death, but only if the mutant Kv11.1 channels function normally (i.e. like WT channels) after membrane expression is restored. Fewer than half of mutant channels exhibit relatively normal function after rescue by low temperature. The remaining rescued missense mutant Kv11.1 channels have perturbed gating and/or ion selectivity characteristics. Co-expression of WT subunits with gating defective missense mutations ameliorates but does not eliminate the functional abnormalities observed for most mutant channels. For patients with mutations that affect gating in addition to expression, it may be necessary to use a combination therapy to restore both normal function and normal expression of the channel protein., Abstract: In the heart, Kv11.1 channels pass the rapid delayed rectifier current (IKr ) which plays critical roles in repolarization of the cardiac action potential and in the suppression of arrhythmias caused by premature stimuli. Over 500 inherited mutations in Kv11.1 are known to cause long QT syndrome type 2 (LQTS2), a cardiac electrical disorder associated with an increased risk of life threatening arrhythmias. Most missense mutations in Kv11.1 reduce the amount of channel protein expressed at the membrane and, as a consequence, there has been considerable interest in developing pharmacological agents to rescue the expression of these channels. However, pharmacological chaperones will only have clinical utility if the mutant Kv11.1 channels function normally after membrane expression is restored. The aim of this study was to characterize the gating phenotype for a subset of LQTS2 mutations to assess what proportion of mutations may be suitable for rescue. As an initial screen we used reduced temperature to rescue expression defects of mutant channels expressed in Xenopus laevis oocytes. Over half (∼56%) of Kv11.1 mutants exhibited functional gating defects that either dramatically reduced the amount of current contributing to cardiac action potential repolarization and/or reduced the amount of protective current elicited in response to premature depolarizations. Our data demonstrate that if pharmacological rescue of protein expression defects is going to have clinical utility in the treatment of LQTS2 then it will be important to assess the gating phenotype of LQTS2 mutations before attempting rescue., (© 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.)

Drug block of voltage-gated potassium channel subtype 11.1 human ether-a-go-go related gene (Kv11.1) (hERG) channels, encoded by the KCNH2 gene, is associated with reduced repolarization of the cardiac action potential and is the predominant cause of acquired long QT syndrome that can lead to fatal cardiac arrhythmias. Current safety guidelines require that potency of KV11.1 block is assessed in the preclinical phase of drug development. However, not all drugs that block KV11.1 are proarrhythmic, meaning that screening on the basis of equilibrium measures of block can result in high attrition of potentially low-risk drugs. The basis of the next generation of drug-screening approaches is set to be in silico risk prediction, informed by in vitro mechanistic descriptions of drug binding, including measures of the kinetics of block. A critical issue in this regard is characterizing the temperature dependence of drug binding. Specifically, it is important to address whether kinetics relevant to physiologic temperatures can be inferred or extrapolated from in vitro data gathered at room temperature in high-throughout systems. Here we present the first complete study of the temperature-dependent kinetics of block and unblock of a proarrhythmic drug, cisapride, to KV11.1. Our data highlight a complexity to binding that manifests at higher temperatures and can be explained by accumulation of an intermediate, non-blocking encounter-complex. These results suggest that for cisapride, physiologically relevant kinetic parameters cannot be simply extrapolated from those measured at lower temperatures; rather, data gathered at physiologic temperatures should be used to constrain in silico models that may be used for proarrhythmic risk prediction., (Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.)

The Kv11.1 or hERG potassium channel is responsible for one of the major repolarising currents (IKr) in cardiac myocytes. Drug binding to hERG can result in reduction in IKr, action potential prolongation, acquired long QT syndrome and fatal cardiac arrhythmias. The current guidelines for pre-clinical assessment of drugs in development is based on the measurement of the drug concentration that causes 50% current block, i.e., IC50. However, drugs with the same apparent IC50 may have very different kinetics of binding and unbinding, as well as different affinities for the open and inactivated states of Kv11.1. Therefore, IC50 measurements may not reflect the true risk of drug induced arrhythmias. Here we have used an in silico approach to test the hypothesis that drug binding kinetics and differences in state-dependent affinity will influence the extent of cardiac action potential prolongation independent of apparent IC50 values. We found, in general that drugs with faster overall kinetics and drugs with higher affinity for the open state relative to the inactivated state cause more action potential prolongation. These characteristics of drug-hERG interaction are likely to be more arrhythmogenic but cannot be predicted by IC50 measurement alone. Our results suggest that the pre-clinical assessment of Kv11.1-drug interactions should include descriptions of the kinetics and state dependence of drug binding. Further, incorporation of this information into sophisticated in silico models should be able to better predict arrhythmia risk and therefore more accurately assess safety of new drugs in development., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objective: Antipsychotic drugs target dopamine and serotonin receptors as well as Kv11.1 potassium channels encoded by KCNH2. Variable patient responses and a wide range of side effects, however, limit their efficacy. Slow metabolizer status and gene variants in KCNH2 associated with increased expression of Kv11.1-3.1, an alternatively spliced isoform of Kv11.1, are correlated with improved responses to antipsychotic medications. Here, the authors test the hypothesis that these effects may be influenced by differential drug binding to Kv11.1 channel isoforms., Method: Drug block of Kv11.1 isoforms was tested in cellular electrophysiology assays. The effects of drug metabolism and KCNH2 genotypes on clinical responses were assessed in patients enrolled in the multicenter Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE)., Results: Risperidone caused greater in vitro block of the alternatively spliced Kv11.1-3.1 isoform than full-length Kv11.1-1A channels, whereas its metabolite paliperidone and other atypical antipsychotics have similar potencies for the two isoforms. In the CATIE study (N=362), patients with genotypes associated with increased Kv11.1-3.1 expression (N=52) showed a better treatment response to risperidone compared with other drugs, but this association was dependent on metabolism status. Patients with KCNH2 risk genotypes and slow metabolizer status (approximately 7% of patients) showed marked improvement in symptoms when treated with risperidone compared with patients with fast metabolizer status or without the KCNH2 risk genotypes., Conclusions: These data support the hypothesis that Kv11.1 channels play a role in the therapeutic action of antipsychotic drugs, particularly risperidone, and further highlight the promise of optimizing response with genotype-guided therapy for schizophrenia patients.

We demonstrate coherent control over the optical response of a coupled plasmonic resonator by high-energy electron beam excitation. We spatially control the position of an electron beam on a gold dolmen and record the cathodoluminescence and electron energy loss spectra. By selective coherent excitation of the dolmen elements in the near field, we are able to manipulate modal amplitudes of bonding and antibonding eigenmodes. We employ a combination of CL and EELS to gain detailed insight in the power dissipation of these modes at the nanoscale as CL selectively probes the radiative response and EELS probes the combined effect of Ohmic dissipation and radiation.

We present an approach to spectrum splitting for photovoltaics that utilizes the resonant optical properties of nanostructures for simultaneous voltage enhancement and spatial separation of different colors of light. Using metal-insulator-metal resonators commonly used in broadband metamaterial absorbers we show theoretically that output voltages can be enhanced significantly compared to single-junction devices. However, the approach is general and works for any type of resonator with a large absorption cross section. Due to its resonant nature, the spectrum splitting occurs within only a fraction of the wavelength, as opposed to traditional spectrum splitting methods, where many wavelengths are required. Combining nanophotonic spectrum splitting with other nanophotonic approaches to voltage enhancements, such as angle restriction and concentration, may lead to highly efficient but deeply subwavelength photovoltaic devices.

Potassium ion channels encoded by the human ether-a-go-go related gene (hERG) form the ion-conducting subunit of the rapid delayed rectifier potassium current (IKr ). Although hERG channels exhibit a widespread tissue distribution they play a particularly important role in the heart. There has been considerable interest in hERG K(+) channels for three main reasons. First, they have very unusual gating kinetics, most notably rapid and voltage-dependent inactivation coupled to slow deactivation, which has led to the suggestion that they may play a specific role in the suppression of arrhythmias. Second, mutations in hERG are the cause of 30-40% of cases of congenital long QT syndrome (LQTS), the commonest inherited primary arrhythmia syndrome. Third, hERG is the molecular target for the vast majority of drugs that cause drug-induced LQTS, the commonest cause of drug-induced arrhythmias and cardiac death. Drug-induced LQTS has now been reported for a large range of both cardiac and non-cardiac drugs, in which this side effect is entirely undesired. In recent years there have been comprehensive reviews published on hERG K(+) channels (Vandenberg et al. 2012) and we will not re-cover this ground. Rather, we focus on more recent work on the structural basis and dynamics of hERG gating with an emphasis on how the latest developments may facilitate translational research in the area of stratifying risk of arrhythmias., (© 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.)

The aim of this prospective study was to investigate whether spinal cord stimulation (SCS) significantly reduces pain intensity for up to 18-month follow-up in patients with chronic neuropathic pain. Forty-eight patients were recruited. Patients rated their pain using a Visual analog scale (VAS) and pain-related disability using the Oswestry Disability Index (ODI) at baseline (1 week prior to SCS surgery) and at 6-, 12-, and 18-month follow-up. Pain intensity significantly decreased from baseline to all 3 time points [F (3,135) = 16.264, p < 0.001]. The greatest difference in the reduction of pain intensity was observed between baseline (M = 7.20, SD = 1.34) and 6-month follow-up (M = 4.60, SD = 2.20), [t(47) = 6.741, p < 0.001]. However, when looking at differences between the 6-month follow-up and subsequent assessments, statistically significant increases in pain intensity from the 6-month to the 12-month follow-up [t(47) = -2.788, p = 0.008], and from the 6-month to the 18-month follow-up [t(47) = -3.339, p = 0.002] could be observed. Statistically significant changes were also observed for clinical changes in pain scores [F (2,94) = 4.972, p = 0.009. There was a significant decrease in the percentage of clinical change obtained from the 6-month (M = 33.19, SD = 35.63) to the 12-month follow-up (M = 23.76, SD = 33.62), [t(47) = 2.347, p = 0.025], and from the 6-month to the 18-month follow-up (M = 18.34, SD = 33.51), [t(47) = 3.072, p = 0.004]. A number of patients also reported higher levels of pain intensity at the 12-and 18-month follow-up than at baseline. Pain-related disability scores significantly decreased from baseline (M = 55.04, SD = 16.43) to the 6-month follow up (M = 46.98, SD = 19.05), [t(47) = 3.464, p = 0.001] and from baseline to the 12-month follow up (M = 48.49, SD = 20.94), [t(47) = 2.918, p = 0.005], but not during the 18-month follow up (M = 51.75, SD = 20.92), [t(47) = 1.330, p = .190]. There was a significant increase in pain-related disability between the 6- and the 18-month follow up [t(47) = -2.188. p = 0.034]. These findings suggest that the beneficial effect of SCS on pain intensity may diminish over time, and that the 6-month follow-up scores may reflect a placebo effect.

The epitaxial growth of monocrystalline semiconductors on metal nanostructures is interesting from both fundamental and applied perspectives. The realization of nanostructures with excellent interfaces and material properties that also have controlled optical resonances can be very challenging. Here we report the synthesis and characterization of metal-semiconductor core-shell nanowires. We demonstrate a solution-phase route to obtain stable core-shell metal-Cu2O nanowires with outstanding control over the resulting structure, in which the noble metal nanowire is used as the nucleation site for epitaxial growth of quasi-monocrystalline Cu2O shells at room temperature in aqueous solution. We use X-ray and electron diffraction, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, photoluminescence spectroscopy, and absorption spectroscopy, as well as density functional theory calculations, to characterize the core-shell nanowires and verify their structure. Metal-semiconductor core-shell nanowires offer several potential advantages over thin film and traditional nanowire architectures as building blocks for photovoltaics, including efficient carrier collection in radial nanowire junctions and strong optical resonances that can be tuned to maximize absorption.

The heart rhythm disorder long QT syndrome (LQTS) can result in sudden death in the young or remain asymptomatic into adulthood. The features of the surface electrocardiogram (ECG), a measure of the electrical activity of the heart, can be equally variable in LQTS patients, posing well-described diagnostic dilemmas. Here we report a correlation between QT interval prolongation and T-wave notching in LQTS2 patients and use a novel computational framework to investigate how individual ionic currents, as well as cellular and tissue level factors, contribute to notched T waves. Furthermore, we show that variable expressivity of ECG features observed in LQTS2 patients can be explained by as little as 20% variation in the levels of ionic conductances that contribute to repolarization reserve. This has significant implications for interpretation of whole-genome sequencing data and underlies the importance of interpreting the entire molecular signature of disease in any given individual.

The Kv11.1 potassium channel is the molecular target for the majority of drugs implicated in acquired long QT syndrome, the most common cause of drug-induced sudden cardiac death, and a common reason for drug restriction or withdrawal from the market. While the IC50 for block of Kv11.1 is commonly used to estimate the risk of acquired long QT syndrome, this approach is crude, and it is widely accepted that the kinetics of drug interactions with the channel are a critical component in understanding their mechanism of action and risk profiles. In this study we report the first directly measured kinetics of block and unblock of Kv11.1 by a QT prolonging drug: the antipsychotic clozapine. Our data show that clozapine binding to Kv11.1 is complex. There are at least two kinetically distinct components to both block and unblock, while the kinetics of unblock are dependent on the dose or duration of drug application. Based on these observations, we have proposed a model incorporating kinetically distinct binding to the open and inactivated states of Kv11.1 that can describe the observed kinetic features of clozapine block and correctly predict the overall affinity and apparent nonstate-dependent interaction of clozapine with Kv11.1. Mechanistic insights into drug block of Kv11.1 gained though detailed kinetic analyses such as this have a potential role in development of drugs targeted to specific channel states to reduce unwanted side effects, as well as in the design of better high-throughput preclinical tests for assessing the proarrhythmic effects of QT prolonging drugs.

The two-pore domain potassium channel, K2P3.1 (TASK-1) modulates background conductance in isolated human atrial cardiomyocytes and has been proposed as a potential drug target for atrial fibrillation (AF). TASK-1 knockout mice have a predominantly ventricular phenotype however, and effects of TASK-1 inactivation on atrial structure and function have yet to be demonstrated in vivo. The extent to which genetic variation in KCNK3, that encodes TASK-1, might be a determinant of susceptibility to AF is also unknown. To address these questions, we first evaluated the effects of transient knockdown of the zebrafish kcnk3a and kcnk3b genes and cardiac phenotypes were evaluated using videomicroscopy. Combined kcnk3a and kcnk3b knockdown in 72 hour post fertilization embryos resulted in lower heart rate (p<0.001), marked increase in atrial diameter (p<0.001), and mild increase in end-diastolic ventricular diameter (p=0.01) when compared with control-injected embryos. We next performed genetic screening of KCNK3 in two independent AF cohorts (373 subjects) and identified three novel KCNK3 variants. Two of these variants, present in one proband with familial AF, were located at adjacent nucleotides in the Kozak sequence and reduced expression of an engineered reporter. A third missense variant, V123L, in a patient with lone AF, reduced resting membrane potential and altered pH sensitivity in patch-clamp experiments, with structural modeling predicting instability in the vicinity of the TASK-1 pore. These in vitro data suggest that the double Kozak variants and V123L will have loss-of-function effects on ITASK. Cardiac action potential modeling predicted that reduced ITASK prolongs atrial action potential duration, and that this is potentiated by reciprocal changes in activity of other ion channel currents. Our findings demonstrate the functional importance of ITASK in the atrium and suggest that inactivation of TASK-1 may have diverse effects on atrial size and electrophysiological properties that can contribute to an arrhythmogenic substrate., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Altered function of ion channels in the heart can increase the risk of sudden arrhythmic death. Hundreds of genetic variants exist in these cardiac ion channel genes. The challenge is how to interpret the effects of multiple conductance perturbations on the complex multi-variable cardiac electrical system? In theory, sensitivity analysis can address this question. However, to date this approach has been restricted by computational overheads to analysis of isolated cells, which has limited extrapolation to physiologically relevant scales. The goal of this study was to extend existing sensitivity analyses to electrocardiogram (ECG) signals derived from multicellular systems and quantify the contribution of ionic conductances to emergent properties of the ECG. To achieve this, we have developed a highly parallelised simulation environment using unconventional high performance computing architectures to analyse the emergent electrical properties of a multicellular system. This has permitted the first systematic analysis of the molecular basis of the T wave amplitude, revealing important but distinct roles for delayed rectifier and inward rectifier K(+) currents. In addition to quantifying how interactions between multiple ion channels influence ECG parameters we show that these sensitivities are dynamic functions of heart rate. This study provides a significant advance in our understanding both of how individual ion conductances define ECG signals and of epistatic modification of cardiac electrical phenotypes. The parallelised simulation environment we have developed removes the computational roadblock that has limited this approach and so provides the framework for future analysis of more complex tissue and whole organ systems.

Loss of Kv11.1 potassium channel function is the underlying cause of pathology in long-QT syndrome type 2, one of the commonest causes of sudden cardiac death in the young. Previous studies have identified the cytosolic PAS (Per/Arnt/Sim) domain as a hotspot for mutations that cause Kv11.1 trafficking defects. To investigate the underlying basis of this observation, we have quantified the effect of mutants on domain folding as well as interactions between the PAS domain and the remainder of the channel. Apart from R56Q, all mutants impaired the thermostability of the isolated PAS domain. Six mutants, located in the vicinity of a hydrophobic patch on the PAS domain surface, also affected binding of the isolated PAS domain to an N-terminal truncated hERG (human ether-a-go-go-related gene) channel. Conversely, four other surface mutants (C64Y, T65P, A78P and I96T) and one buried mutant (L86R) did not prevent the isolated PAS domain binding to the truncated channels. Our results highlight a critical role for interactions between the PAS domain and the remainder of the channel in the hERG assembly and that mutants that affect PAS domain interactions with the remainder of the channel have a more severe trafficking defect than that caused by domain unfolding alone.

The recent exponential increase in human genetic studies due to the advances of next generation sequencing has generated unprecedented numbers of new gene variants. Determining which of these are causative of human disease is a major challenge. In-vitro studies and murine models have been used to study inherited cardiac arrhythmias but have several limitations. Zebrafish models provide an attractive alternative for modeling human heart disease due to similarities in cardiac electrophysiology and contraction, together with ease of genetic manipulation, external development and optical transparency. Although zebrafish cardiac mutants and morphants have been widely used to study loss and knockdown of zebrafish gene function, the phenotypic effects of human dominant-negative gene mutations expressed in transgenic zebrafish have not been evaluated. The aim of this study was to generate and characterize a transgenic zebrafish arrhythmia model harboring the pathogenic human cardiac sodium channel mutation SCN5A-D1275N, that has been robustly associated with a range of cardiac phenotypes, including conduction disease, sinus node dysfunction, atrial and ventricular arrhythmias, and dilated cardiomyopathy in humans and in mice. Stable transgenic fish with cardiac expression of human SCN5A were generated using Tol2-mediated transgenesis and cardiac phenotypes were analyzed using video microscopy and ECG. Here we show that transgenic zebrafish expressing the SCN5A-D1275N mutation, but not wild-type SCN5A, exhibit bradycardia, conduction-system abnormalities and premature death. We furthermore show that SCN5A-WT, and to a lesser degree SCN5A-D1275N, are able to compensate the loss of endogenous zebrafish cardiac sodium channels, indicating that the basic pathways, through which SCN5A acts, are conserved in teleosts. This proof-of-principle study suggests that zebrafish may be highly useful in vivo models to differentiate functional from benign human genetic variants in cardiac ion channel genes in a time- and cost-efficient manner. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes"., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Metallic and dielectric nanostructures have highly tunable resonances that have been used to increase light absorption in a variety of photovoltaic materials and device structures. Metal nanowires have also emerged as a promising candidate for high-performance transparent electrodes for local contacts. In this Letter we propose combining these electrical and optical functions. As a first step, we use rigorous solutions to Maxwell's equations to demonstrate theoretically extreme absorption in semiconductor thin films wrapped around metal nanowires. We show that there are two key principles underlying this extraordinary light trapping effect: (1) maximizing the absorption of each individual resonance by ensuring it is critically coupled and (2) increasing the total number of degenerate resonances. Inserting a metal core into a semiconductor nanowire creates such a degeneracy: polarization-dependent Mie resonances are transformed into polarization-independent Fabry-Pérot-like resonances. We demonstrate that, by reducing the polarization sensitivity and increasing the number of critically coupled modes, this hybrid coaxial nanowire geometry substantially outperforms solid semiconducting nanowires, even though the semiconductor volume is significantly reduced. These results suggest that metal nanowires with semiconductor shells might be ideal building blocks for photovoltaic and solar fuel applications.

Objectives: The goal of this study was to characterize a variant in the SCN5A gene that encodes the alpha-subunit of the cardiac sodium channel, Nav1.5, which was identified in 1 large kindred with dilated cardiomyopathy (DCM) and multiple arrhythmias, including premature ventricular complexes (PVCs)., Background: Treatment guidelines for familial DCM are based on conventional heart failure therapies, and no gene-based interventions have been established., Methods: Family members underwent clinical evaluation and screening of the SCN5A and LMNA genes. Cellular electrophysiology and computational modeling were used to determine the functional consequences of the mutant Nav1.5 protein., Results: An R222Q missense variant located in a Nav1.5 voltage-sensing domain was identified in affected family members. Patch-clamp studies showed that R222Q Nav1.5 did not alter sodium channel current density, but did left shift steady-state parameters of activation and inactivation. Using a voltage ramp protocol, normalized current responses of R222Q channels were of earlier onset and greater magnitude than wild-type channels. Action potential modeling using Purkinje fiber and ventricular cell models suggested that rate-dependent ectopy of Purkinje fiber origin is the predominant ventricular effect of the R222Q variant and a potential cause of DCM. In R222Q carriers, there were only modest responses to heart failure therapies, but PVCs and DCM were substantially reduced by amiodarone or flecainide, which are drugs that have sodium channel-blocking properties., Conclusions: The R222Q SCN5A variant has an activating effect on sodium channel function and is associated with reversible ventricular ectopy and DCM. Elucidation of the genetic basis of familial DCM can enable effective gene-targeted therapy to be implemented., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Rationale: Cystic fibrosis (CF) lung disease is characterized by structural changes and remodeling in airway architecture and lung parenchyma. Neutrophilic inflammation and infection lead to injury and breakdown of airway matrix constituents, including elastin. The non-invasive measurement of urinary desmosine (UDes), a breakdown product of elastin, may be reflective of ongoing lung injury and may serve as a biomarker of active short-term damage during pulmonary exacerbation. Our objectives were to measure desmosine in the urine of CF patients hospitalized for treatment of a pulmonary exacerbation and to explore the correlation between desmosine concentration and other markers of clinical improvement, including lung function and inflammatory mediators., Methods: Urine and blood samples plus lung function measurements were collected at up to three points during hospitalization for treatment of a CF pulmonary exacerbation. We used a repeated measures model, adjusted for age and time between measurements, to compare log transformed urine desmosine concentrations across multiple time points and to correlate those concentrations with related clinical variables. Change in UDes concentration was investigated using a statistical model that incorporated normalization factors to account for variations in urinary concentration., Results: Desmosine was measured by radioimmunoassay (RIA) in 155 spot urine samples from 53 CF patients hospitalized for 63 pulmonary exacerbations (range of results: 0-235 pmol Des/ml). Specific gravity (SG) adjusted UDes concentration decreased significantly during admission for CF pulmonary exacerbation, P < 0.01 (average length of stay = 11 days). No correlation was observed between UDes concentration and lung function or inflammatory markers., Conclusions: UDes decreased significantly following treatment for an acute pulmonary exacerbation and may be a useful biomarker of short-term injury to the CF lung. Further investigation is needed to evaluate the utility of UDes concentration in the long-term progression of CF lung disease., (Copyright © 2012 Wiley Periodicals, Inc.)

The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the rapid component of the delayed rectifier K(+) channel, Kv11.1, which are expressed in the heart, various brain regions, smooth muscle cells, endocrine cells, and a wide range of tumor cell lines. However, it is the role that Kv11.1 channels play in the heart that has been best characterized, for two main reasons. First, it is the gene product involved in chromosome 7-associated long QT syndrome (LQTS), an inherited disorder associated with a markedly increased risk of ventricular arrhythmias and sudden cardiac death. Second, blockade of Kv11.1, by a wide range of prescription medications, causes drug-induced QT prolongation with an increase in risk of sudden cardiac arrest. In the first part of this review, the properties of Kv11.1 channels, including biogenesis, trafficking, gating, and pharmacology are discussed, while the second part focuses on the pathophysiology of Kv11.1 channels.

Objectives: The aim of this study was to evaluate the role of cardiac K(+) channel gene variants in families with atrial fibrillation (AF)., Background: The K(+) channels play a major role in atrial repolarization but single mutations in cardiac K(+) channel genes are infrequently present in AF families. The collective effect of background K(+) channel variants of varying prevalence and effect size on the atrial substrate for AF is largely unexplored., Methods: Genes encoding the major cardiac K(+) channels were resequenced in 80 AF probands. Nonsynonymous coding sequence variants identified in AF probands were evaluated in 240 control subjects. Novel variants were characterized using patch-clamp techniques and in silico modeling was performed using the Courtemanche atrial cell model., Results: Nineteen nonsynonymous variants in 9 genes were found, including 11 rare variants. Rare variants were more frequent in AF probands (18.8% vs. 4.2%, p < 0.001), and the mean number of variants was greater (0.21 vs. 0.04, p < 0.001). The majority of K(+) channel variants individually had modest functional effects. Modeling simulations to evaluate combinations of K(+) channel variants of varying population frequency indicated that simultaneous small perturbations of multiple current densities had nonlinear interactions and could result in substantial (>30 ms) shortening or lengthening of action potential duration as well as increased dispersion of repolarization., Conclusions: Families with AF show an excess of rare functional K(+) channel gene variants of varying phenotypic effect size that may contribute to an atrial arrhythmogenic substrate. Atrial cell modeling is a useful tool to assess epistatic interactions between multiple variants., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Aberrant inactivation of tumor suppressor genes by promoter hypermethylation has been recognized as a crucial step of tumor development and is related to aggressiveness and therapy resistance. To identify potential novel treatment strategies, we evaluated pharmacological genome demethylation for the increase of irradiation treatment effectiveness in head and neck squamous cell carcinoma (HNSCC) in this in vitro study. HNSCC cells were cultured with 2 different concentrations of 5-azacytidine (5-Aza) for 72 h, followed by a single fraction irradiation with 4 or 50 Gy, respectively. To show successful genome demethylation, the methylation status of the tumor suppressor gene hic1 (hypermethylated in cancer) promoter was analyzed by methylation specific PCR (MSP) as well as hic1 transcription by quantitative RT-PCR. Survival, apoptosis, viability, and migration of the tumor cells were analyzed as functional parameters of combined treatment response. After 5-Aza treatment the hic1 promoter was demethylated and gene transcription restored demonstrating genome demethylation. 5-Aza treated cells tended to be less viable and showed decreased survival indicated by lower colony numbers. Apoptosis and migration were not affected. The combined application of irradiation and 5-Aza significantly reduced survival compared to the single treatments. Accordingly, apoptosis was strongly increased after combined 4 Gy/5-Aza treatment. Viability was not additionally affected by combined treatment. Migration was affected weakly by combined high dosage irradiation/5‑Aza treatment. Our data show that the combined application of 5-Aza and irradiation is effective in vitro. A demethylating concept prior to irradiation should be further evaluated for its potential to reduce irradiation resistance.

Recent genome wide association studies identified a brain and primate specific isoform of a voltage-gated potassium channel, referred to as Kv11.1-3.1, which is significantly associated with schizophrenia. The 3.1 isoform replaces the first 102 amino acids of the most abundant isoform (referred to as Kv11.1-1A) with six unique amino acids. Here we show that the Kv11.1-3.1 isoform has faster rates of channel deactivation but a slowing of the rates of inactivation compared to the Kv11.1-1A isoform. The Kv11.1-3.1 isoform also has a significant depolarizing shift in the voltage-dependence of steady-state inactivation. The consequence of the altered gating kinetics is that there is lower current accumulation for Kv11.1-3.1 expressing cells during repetitive action potential firing compared to Kv11.1-1A expressing cells, which in turn will result in longer lasting trains of action potentials. Increased expression of Kv11.1-3.1 channels in the brain of schizophrenia patients might therefore contribute to disorganized neuronal firing.

Using Mie theory and Rigorous Coupled Wave Analysis (RCWA) we compare the properties of dielectric particle and void resonators. We show that void resonators-low refractive index inclusions within a high index embedding medium-exhibit larger bandwidth resonances, reduced peak scattering intensity, different polarization anisotropies, and enhanced forward scattering when compared to their particle (high index inclusions in a low index medium) counterparts. We evaluate amorphous silicon solar cell textures comprising either arrays of voids or particles. Both designs support substantial absorption enhancements (up to 45%) relative to a flat cell with anti-reflection coating, over a large range of cell thicknesses. By leveraging void-based textures 90% of above-bandgap photons are absorbed in cells with maximal vertical dimension of 100 nm.

Objective: The purpose of this study was to investigate the relationship between T2 relaxation values (T2 RVs) within the superficial zone of articular cartilage and different types of meniscal degeneration/tear., Materials and Methods: A review of 310 consecutive knee MRIs which included an 8 echo T2 relaxation sequence, in patients referred for standard clinical indications, was performed independently and in blinded fashion by 2 observers. The posterior horns of the medial and lateral menisci were each evaluated and divided into 4 subgroups: Normal (control), Grade I/II meniscal signal, Grade III meniscal signal-simple tear (Grade III-S), and Grade III meniscal signal-complex tear (Grade III-C). After exclusion criteria were applied, the medial meniscal group consisted of 65 controls and 133 patients, while the lateral meniscal group consisted of 143 controls and 55 patients. T2 RVs were measured by an observer blinded to the clinical history and MRI grading. Measurements were obtained over the superficial zone of femoral and tibial articular cartilage adjacent to the center of the posterior horn of each meniscus to ensure consistency between measurements. Analysis of covariance adjusting for age and gender was used to compare T2 RVs between patients and controls., Results: T2 RVs were significantly increased in patients with Grade III-C meniscal tears compared to controls over the medial tibial plateau (MTP; p=0.0001) and lateral tibial plateau (LTP; p=0.0008). T2 RVs were not increased in patients with Grade III-C meniscal tears over the medial femoral condyle (MFC; p=0.11) or lateral femoral condyle (LFC; p=0.99). Grade I/II meniscal signal was not associated with elevated T2 RVs over the MFC (p=0.15), LFC (p=0.69), MTP (p=0.42), or LTP (p=0.50). Grade III-S meniscal signal was not associated with elevated T2 RVs over the MFC (p=0.54), LFC (p=0.43), MTP (p=0.30), or LTP (p=0.38)., Conclusion: Grade III-C meniscal tears are associated with elevated T2 RVs in adjacent tibial articular cartilage. The results may have an impact on prognostication and treatment in order to delay or prevent the onset of osteoarthritis., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Traumatic lateral spondyloptosis is mostly a lateral shearing injury that must be tremendous enough to completely disrupt the strong musculoligamentous and bony structures. This injury has only been described at single levels in the lumbar spine. Lateral expulsion of a vertebral body from the spinal column due to 2-level adjacent spondyloptosis has not been previously reported. This 16-year-old girl was referred to our center for the management of an extremely unusual L2-5 fracture-dislocation. Motor deficits were incomplete and sacral sensation was spared. Three-dimensional reconstructed CT scans revealed a fracture involving the superior L-4 vertebral body and endplate. There was also complete disruption of the L4-5 disc space. The majority of the L-4 vertebral body was expelled to the right of the spinal column, with the collapse of L-3 and a small remnant of the L-4 superior endplate onto L-5. Surgical management involved decompression, reduction, reconstruction of L-4 with a cage, and L1-ilium stabilization and fusion. Only a few attachments of the psoas muscles had to be divided to roll the L-4 vertebral body out posterolaterally, similar to the method of complete en bloc spondylectomy used in oncology. Neurological recovery has thus far included the resumption of normal bladder and bowel function, as well as ambulation with the use of a right leg brace. Perhaps this type of fracture has not been previously described because many patients would be expected to succumb to vascular or visceral injury. The authors believe this is the first case report of double lateral spondyloptosis at adjacent levels, resulting in expulsion of the vertebral body from the spinal column.

The potassium channel selectivity filter both discriminates between K(+) and sodium ions and contributes to gating of ion flow. Static structures of conducting (open) and nonconducting (inactivated) conformations of this filter are known; however, the sequence of protein rearrangements that connect these two states is not. We show that closure of the selectivity filter gate in the human K(v)11.1 K(+) channel (also known as hERG, for ether-a-go-go-related gene), a key regulator of the rhythm of the heartbeat, is initiated by K(+) exit, followed in sequence by conformational rearrangements of the pore domain outer helix, extracellular turret region, voltage sensor domain, intracellular domains and pore domain inner helix. In contrast to the simple wave-like sequence of events proposed for opening of ligand-gated ion channels, a complex spatial and temporal sequence of widespread domain motions connect the open and inactivated states of the K(v)11.1 K(+) channel.

Objective: The maintenance of post-operative lordosis has been shown to be a key factor in decreasing adjacent level disc stress. Previous studies of the PEEK (polyether ketone) cage have used intervertebral bony fusion as the primary measure of surgical success; however, little is known about its effects on spinal curvature. Our objective was to compare the PEEK cage to the cervical plate with respect to the maintenance of cervical lordosis at one year. Secondary outcomes included fusion and complication rates., Methods: We performed a retrospective study of patients who underwent ACDF (anterior cervical discectomy and fusion) by two different methods; 13 patients were treated with the PEEK cage, and 22 with allograft and plating., Results: Patient and treatment characteristics were similar in both groups. Average global lordotic curvature (C2-C7) was increased by 1.7 degrees for the PEEK cage and decreased by 1.6 degrees for the plate after an average follow-up of 12.46 and 14.95 months, respectively. Regional lordosis for the PEEK cage and plate was decreased by 2.5 and 2.1 degrees, respectively for the same time period. These differences did not achieve statistical significance. Bony fusion was observed in all patients. One patient in each group developed persistent mild dysphagia., Conclusions: The PEEK cage is comparable to the anterior cervical plate in the maintenance of post-operative cervical lordosis.

Promoter hypermethylation of tumor suppressor genes is a common feature of primary cancer cells. However, at date the somatic epigenetic events that occur in head and neck squamous cell carcinoma (HNSCC) tumorigenesis are not yet been well defined. In the present study we analysed the methylation status of the gene hypermethylated in cancer-1 (hic1), a gene located on chromosome 17p13.3, a region frequently lost in HNSCC. We analysed 22 HNSCC samples and three cell lines using methylation specific PCR (MSP). We found hic1 methylated in 21 out of 22 samples and in all three cell lines. Treatment of the cell lines with the demethylating agent 5-Azacytidin (5-Aza) resulted in the demethylation of the hic1 promoter and reactivation of hic1 expression as determined by MSP, qPCR and Western blot. Functional analyses revealed decreased proliferative activity and colony forming ability of treated cells. In summary, we found in HNSCC hic1 regulated by promoter methylation. 5-Aza application resulted in the reexpression of hic1 and was followed by decreased aggressiveness of the cancer cells. Our data indicate that hic1 might be a player in HNSCC development and suggest further evaluation of 5-Aza for HNSCC treatment., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Background: Recognition of biological patterns holds promise for improved identification of patients at risk for myocardial infarction (MI) and death. We hypothesized that identifying high- and low-risk patterns from a broad spectrum of hematologic phenotypic data related to leukocyte peroxidase-, erythrocyte- and platelet-related parameters may better predict future cardiovascular risk in stable cardiac patients than traditional risk factors alone., Methods and Results: Stable patients (n=7369) undergoing elective cardiac evaluation at a tertiary care center were enrolled. A model (PEROX) that predicts incident 1-year death and MI was derived from standard clinical data combined with information captured by a high-throughput peroxidase-based hematology analyzer during performance of a complete blood count with differential. The PEROX model was developed using a random sampling of subjects in a derivation cohort (n=5895) and then independently validated in a nonoverlapping validation cohort (n=1474). Twenty-three high-risk (observed in > or =10% of subjects with events) and 24 low-risk (observed in > or =10% of subjects without events) patterns were identified in the derivation cohort. Erythrocyte- and leukocyte (peroxidase)-derived parameters dominated the variables predicting risk of death, whereas variables in MI risk patterns included traditional cardiac risk factors and elements from all blood cell lineages. Within the validation cohort, the PEROX model demonstrated superior prognostic accuracy (78%) for 1-year risk of death or MI compared with traditional risk factors alone (67%). Furthermore, the PEROX model reclassified 23.5% (P<0.001) of patients to different risk categories for death/MI when added to traditional risk factors., Conclusions: Comprehensive pattern recognition of high- and low-risk clusters of clinical, biochemical, and hematologic parameters provided incremental prognostic value in stable patients having elective diagnostic cardiac catheterization for 1-year risks of death and MI.

Background: Cystic fibrosis (CF) lung disease is characterized by structural changes in the airways and parenchyma. No sputum biomarker exists to measure the degree of active structural destruction during pulmonary exacerbation in patients with CF. The noninvasive measurement of desmosine, a breakdown product of elastin, may reflect ongoing lung injury and serve as a biomarker of short-term damage. Our objectives were to measure desmosine in the sputum of patients with CF hospitalized for treatment of a pulmonary exacerbation and to explore the correlation between desmosine levels and other markers of clinical improvement, including lung function and inflammatory mediators, following hospitalization., Methods: Sputum and blood samples collected and lung function measurements were made at multiple time points during hospitalization. We used a repeated measures model, adjusted for age and time between measurements, to compare log-transformed sputum desmosine levels across multiple time points and to correlate those levels with related variables., Results: Desmosine levels were measured by radioimmunoassay in 71 expectorated sputum samples from 19 patients with CF hospitalized for 26 pulmonary exacerbations (range of results, 0 to 200 pmol/L desmosine/mL). Sputum desmosine levels decreased significantly during the first week of hospitalization (p = 0.04). Desmosine levels were positively associated with plasma C-reactive protein (rho = 0.59; p = 0.03), sputum interleukin-8 (rho = 0.86; p < 0.01), and sputum neutrophil elastase (rho = 0.78; p < 0.01)., Conclusions: Sputum desmosine, a novel measure of acute structural lung injury, may serve as a marker of structural lung damage occurring during exacerbations of lung disease in CF.

Objectives: Interpretation of ventricular volume on computed tomography scans of hydrocephalus patients is usually subjective. The objective of this study was to determine whether radiological assessment of interval change correlates better with an objective calculated volume change or with other objective 2-dimensional estimates of ventricle volume change., Methods/sample: Ventricular volume, Evans ratio, and frontal and occipital Horn ratio were retrospectively assessed on 95 pairs of scans from patients with a ventriculoperitoneal shunt. To determine ventricle volume, all voxels of cerebrospinal fluid density were isolated on a 3-dimensional reconstructed computed tomography scan. Voxels of fluid density contiguous with one another in the ventricular system were isolated. Radiological assessments of interval change were divided into 5 groups based on reported findings in the radiology report. The 95% mean confidence intervals were developed for changes in the measured parameters, given a particular radiological assessment. Multinomial regression was subsequently performed to determine which parameter was most closely correlated with the radiological assessment., Results: Significant overlap was found in the confidence intervals for objectively calculated volume change between the different categories of radiological assessment. The frontal and occipital Horn ratio had the most consistent correlation with the radiological assessment, followed by the Evans ratio. Objectively calculated volume change correlated poorly with radiological assessment., Conclusions: Radiological interpretation does not correlate well with objectively calculated volume changes, but correlates better with other parameters that approximate volume and are likely used to visually evaluate interval change. We recommend that ventricle volume be objectively measured to increase consistency between radiological interpretation and actual interval changes.

Background: Periventricular leukomalacia (PVL) is a frequent complication of preterm delivery. Proinflammatory cytokines, such as interferon-gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) released from astrocytes and microglia activated by infection or ischemia have previously been shown to impair survival and maturation of oligodendrocyte progenitors and could thus be considered as potential factors contributing to the generation of this disease. The first goal of the present study was to investigate whether exposure of oligodendrocyte precursors to these cytokines arrests the maturation of ion currents in parallel to its effects on myelin proteins and morphological maturation. Secondly, in the search for agents, that can protect differentiating oligodendrocyte precursor cells from cytokine-induced damage we investigated effects of coapplications of corticosteroids with proinflammatory cytokines on the subsequent survival and differentiation of oligodendrocyte progenitor cells., Methods: To exclude influences from factors released from other cell types purified cultures of oligodendrocyte precursors were exposed to cytokines and/or steroids and allowed to differentiate for further 6 days in culture. Changes in membrane surface were investigated with capacitance recordings and Scanning Ion Conductance Microscopy. Na+- and K+- currents were investigated using whole cell patch clamp recordings. The expression of myelin specific proteins was investigated using western blots and the precursor cells were identified using immunostaining with A2B5 antibodies., Results: Surviving IFN-gamma and TNF-alpha treated cells continued to maintain voltage-activated Na+- and K+ currents characteristic for the immature cells after 6 days in differentiation medium. Corticosterone, dihydrocorticosterone and, most prominently dexamethasone, counteracted the deleterious effects of IFN-gamma and TNF-alpha on cell survival, A2B5-immunostaining and expression of myelin basic protein. The most potent corticosteroid tested, dexamethasone, was shown to counteract cytokine effects on membrane surface extension and capacitance. Furthermore, coapplication of dexamethasone blocked the cytokine-induced downregulation of the inwardly rectifying potassium current in 80% of the precursor cells and restored the cytokine-blocked down-regulation of the voltage activated Na+- and K+ currents during subsequent differentiation., Conclusion: Our results show that treatment of oligodendrocyte precursors with the inflammatory cytokines TNF-alpha and IFN-gamma block the differentiation of oligodendrocyte precursors at the level of the differentiation of the voltage-gated ion currents. Co-treatment with corticosteroids at the time of cytokine application restores to a considerable extent survival and differentiation of oligodendrocytes at the level of morphological, myelin protein as well as ion current maturation suggesting the option for a functional restoration of cytokine-damaged immature oligodendrocytes.

In two experiments, we tested the hypotheses that (a) the difference between liars and truth tellers will be greater when interviewees report their stories in reverse order than in chronological order, and (b) instructing interviewees to recall their stories in reverse order will facilitate detecting deception. In Experiment 1, 80 mock suspects told the truth or lied about a staged event and did or did not report their stories in reverse order. The reverse order interviews contained many more cues to deceit than the control interviews. In Experiment 2, 55 police officers watched a selection of the videotaped interviews of Experiment 1 and made veracity judgements. Requesting suspects to convey their stories in reverse order improved police observers' ability to detect deception and did not result in a response bias.

The poor differentiation and survival of dopaminergic neurones are practical constraints in their therapeutic applications. Here we explored the role of neuronally activated Ras in ventral mesencephalon-derived neurospheres generated from synRas mouse embryos. The expression of Val12 Ha-Ras transgene and enhanced Ras activity was evident after differentiation of the neurospheres with a corresponding activating phosphorylation of mitogen-activated protein kinase. Phosphorylation of Akt/PKB, the target kinase of phosphoinositide 3-kinase, along with phosphorylation of Bad and CREB were enhanced in synRas-derived differentiated neurosphere cultures. Furthermore, increased Nurr1 expression was associated with elevated numbers of dopaminergic neurones in synRas-derived cultures compared with the wild-type. Correspondingly, tyrosine hydroxylase promoter assays revealed enhanced transcriptional activation of the promoter in synRas-derived cultures. synRas-derived dopaminergic neurones were greatly resistant to degeneration induced by various noxious stimuli. Consistently, the transgenic expression of activated Ras attenuated the adverse 6-hydroxydopamine effects on dopaminergic neurones. Dopaminergic neurones derived from both wild-type and synRas cultures expressed voltage-gated potassium and sodium currents, fired action potentials and exhibited electrical network activity. Thus, expression of the transgene promotes survival and enhances differentiation towards a dopaminergic cell fate without altering their basic electrical properties. Our results suggest that intracellular cell therapy mimicking trophic signalling may offer potential benefit in models of human disease associated with dopamine neurone dysfunction.

We have previously described a pulse-mode scanning ion conductance microscope to investigate membrane surfaces and volume changes of individual cells in culture. We have now developed a miniaturized scanning headstage that enables us to select individual cells for recording under phase contrast optics, considerably improving the selection of individual cells for scanning as well as the positioning of the scanning frames with respect to the position of the cell somata. We show an application in which surfaces and volumes of somata and processes of cultured cells from the central nervous system were quantified separately.

Here we describe the use of pulse-mode scanning ion conductance microscopy (SICM) to observe volume changes and cell membrane movements during the locomotion of cultured cells in the range of minutes to several hours. The microscope is based on the pulse-mode SICM previously developed for stable imaging of single cells in culture. Our instrument uses current pulses to control the distance between cell surface and electrode tip as well as a back-step mode to prevent contact of tip and membrane during lateral movements of the probe. We performed repeated scans of cell surfaces using feedback-controlled piezoactors to position the electrode. Using patch-clamp-type electrode tips the height of cells could reproducibly be measured with a standard deviation of 50 nm. To quantify and separate changes in cell position and volume occurring between consecutive scans, a program was written to subtract images and calculate volume changes. Examples of repeated scans show that membrane movements in the range of 30 min to a few hours can be quantitatively monitored with a lateral resolution of 500 nm using difference images and that faster movements in the range of minutes can be recorded at defined cell sections using the line scan mode. Difference images indicate that volume changes can affect cell surfaces inhomogeneously, emphasizing the role of the cytoskeleton in the stabilization of cell shape.

Scanning ion conductance microscopy (SICM) takes advantage of the increase in the resistance which occurs if a glass microelectrode is closely approached to a poorly conducting membrane (Science 243 (1989) 641) and has been shown to be a promising technique to study membranes of living cells (Biophys J 73 (1997a) 653; J Microsc 188 (1997b) 17). Based on a newly designed set-up on top of an inverted light microscope in combination with a speed optimized low noise intracellular amplifier, a novel mode for control of the distance between the probe and surface has been developed. By application of current pulses, the change in the resistance is monitored independently from electrode drift and parasitic DC currents. We demonstrate the applicability by showing first high-resolution images of neural cells produced with the pulse-mode operated SICM.

In 1991, the Intensive Care Unit (ICU) at Middlemore Hospital manually costed the treatment and care of asthmatic patients. This was long-winded and labour-intensive, but provided hard data to support anecdotal beliefs that intensive care patients are more expensive than was currently believed or accepted. It is a known problem that funder and provider organizations see a huge disparity on the funding issue. With additional accurate information on the actual cost of individual patients, which can be grouped into disease categories, funding applications can be backed with accurate, up-to-date quantitative data. After a long preparation time, we are now costing individual patient stays in the ICU. Each individual resource was established, costed and entered into an MS ACCESS computerized database. Schedules have been prepared for updating prices, as these change. The final report available gives a detailed list of resource use within certain categories. Some items proved to be impractical to cost on an individual patient basis, and these have been grouped together, costed, and divided by the number of patient days for the last year, and assigned to each individual patient as an hourly unit cost. Believed to be a world-first, this information now forms the basis for variance reporting and pricing.

Respect is central to the process of teaching writing, especially the respect that flows from asking students to write about their own personal experiences. The author offers suggestions on how to help students overcome their dislike of writing, address some of their writing deficits, and ultimately begin to enjoy writing.