Pitfalls when examining gap junction hemichannels: interference from volume-regulated anion channels

Human HeLa cells transfected with mouse connexin45 were used to explore the experimental conditions suitable to measure currents carried by gap junction hemichannels. Experiments were performed with a voltage-clamp technique and whole-cell recording. Lowering [Ca2+]o from 2mM to 20nM evoked an extra current, I m, putatively carried by Cx45 hemichannels. However, the variability of I m (size, voltage sensitivity, kinetics) suggested the involvement of other channels. The finding that growth medium in the incubator increased the osmolarity with time implied that volume-regulated anion channels (VRAC) may participate. This assumption was reinforced by the following observations. On the one hand, keeping [Ca2+]o normal while the osmolarity of the extracellular solution was reduced from 310 to 290mOsm yielded a current characteristic of VRAC; I VRAC activated/deactivated at negative/positive voltage, giving rise to the conductance functions g VRAC,inst=f(V m) (inst: instantaneous; V m: membrane potential) and g VRAC,ss=f(V m) (ss: steady state). Moreover, it was reversibly inhibited by mibefradil, a Cl-channel blocker (binding constant K d=38μM, Hill coefficient n=12), but not by the gap junction channel blocker 18α-glycyrrhetinic acid. On the other hand, minimizing the osmotic imbalance while [Ca2+]o was reduced led to a current typical for Cx45 hemichannels; I hc activated/deactivated at positive/negative voltage. Furthermore, it was reversibly inhibited by 18α-glycyrrhetinic acid or palmitoleic acid, but not by mibefradil. Computations based on g VRAC,ss=f(V m) and g hc,ss=f(V m) indicated that the concomitant operation of both currents results in a bell-shaped conductance-voltage relationship. The functional implications of the data presented are discussed. Conceivably, VRAC and hemichannels are involved in a common signaling pathwa

Regulation of Cx45 hemichannels mediated by extracellular and intracellular calcium

Connexin45 (Cx45) hemichannels (HCs) open in the absence of Ca2+ and close in its presence. To elucidate the underlying mechanisms, we examined the role of extra- and intracellular Ca2+ on the electrical properties of HCs. Experiments were performed on HeLa cells expressing Cx45 using electrical (voltage clamp) and optical (Ca2+ imaging) methods. HCs exhibit a time- and voltage-dependent current (I hc), activating with depolarization and inactivating with hyperpolarization. Elevation of [Ca2+]o from 20nM to 2μM reversibly decreases I hc, decelerates its rate of activation, and accelerates its deactivation. Our data suggest that [Ca2+]o modifies the channel properties by adhering to anionic sites in the channel lumen and/or its outer vestibule. In this way, it blocks the channel pore and reversibly lowers I hc and modifies its kinetics. Rapid lowering of [Ca2+]o from 2mM to 20nM, achieved early during a depolarizing pulse, led to an outward I hc that developed with virtually no delay and grew exponentially in time paralleled by unaffected [Ca2+]i. A step increase of [Ca2+]i evoked by photorelease of Ca2+ early during a depolarizing pulse led to a transient decrease of I hc superimposed on a growing outward I hc; a step decrease of [Ca2+]i elicited by photoactivation of a Ca2+ scavenger provoked a transient increase in I hc. Hence, it is tempting to assume that Ca2+ exerts a direct effect on Cx45 hemichannel

Synthesis and Characterization of Poly(hydrogen halide) Halogenates (–I)

Herein, we report the synthesis and characterization of a variety of novel poly(hydrogen halide) halogenates (−I). The bifluoride ion, which is known to have the highest hydrogen bond energy of ≈160 kJ mol−1, is the most famous among many examples of [X(HX)n]− anions (X=F, Cl) known in the literature. In contrast, little is known about poly(hydrogen halide) halogenates containing two different halogens, ([X(HY)n]−). In this work we present the synthesis of anions of the type [X(HY)n]− (X=Br, I, ClO4; Y=Cl, Br, CN) stabilized by the [PPh4]+ and [PPN]+ cation. The obtained compounds have been characterized by single‐crystal X‐ray diffraction, Raman spectroscopy and quantum‐chemical calculations. In addition, the behavior of halide ions in hydrogen fluoride was investigated by using experimental and quantum‐chemical methods in order to gain knowledge on the acidity of hydrogen halides in HF

Public support for worktime reductions in Switzerland in the context of a transition to a post-growth society

Work time reductions (WTRs) may contribute to a transition to a post-growth society. We analysed Swiss stakeholders’ perceptions of the effects of WTRs and their support for measures to implement them. It is assumed that public support will play a significant role in putting WTRs into practice. There is some scientific evidence that work time reductions (WTRs) have beneficial ecological, social, and economic effects that could contribute to a transition to a post-growth society. However, little research has been conducted on whether the occurrence of such desired effects is acknowledged: Do they form part of the public debate and is there any public support for WTRs? We conducted a two-round survey among Swiss stakeholder groups (N = 51/28) to identify what effects they believe WTRs have, and what measures to implement WTRs they would be most likely to support. Stakeholders perceived WTRs to have several beneficial social and economic effects, including effects that are relevant for a transition to a post-growth society. However, they did not assume that ecological effects occur. Measures voluntarily implemented on an organisational level by businesses were more popular than those implemented on a national policy or social partnership level. Certain incremental measures and/or those that are merely conducive to WTRs were uncontested. Other more direct and extensive measures were predominantly supported, but not uncontested

Projected Heat-Related Mortality in the U.S. Urban Northeast

Increased heat-related mortality is projected to be among the major impacts of climate change on human health, and the United States urban Northeast region is likely to be particularly vulnerable. In support of regional adaptation planning, quantitative information is needed on potential future health responses at the urban and regional scales. Here, we present future projections of heat-related mortality in Boston, New York and Philadelphia utilizing downscaled next-generation climate models and Representative Concentration Pathways (RCPs) developed in support of the Intergovernmental Panel on Climate Change (IPCC)’s Fifth Assessment Report (AR5). Our analyses reveal that heat-related mortality rates per 100,000 of population during the baseline period between 1985 and 2006 were highest in Philadelphia followed by New York City and Boston. However, projected heat-related mortality rates in the 2020s, 2050s and 2080s were highest in New York City followed by Philadelphia and Boston. This study may be of value in developing strategies for reducing the future impacts of heat and building climate change resilience in the urban Northeast region

Weather and Climate Change Impacts on Human Mortality in Bangladesh

Weather and climate profoundly affect human health. Several studies have demonstrated a U-, V-, or J-shaped temperature-mortality relationship with increasing death rates at the lower and particularly upper end of the temperature distribution. The objectives of this study were (1) to analyze the relationship between temperature and mortality in Bangladesh for different subpopulations and (2) to project future heat-related mortality under climate change scenarios. We used (non-)parametric Generalized Additive Models adjusted for trend, season and day of the month to analyze the effect of temperature on daily mortality. We found a decrease in mortality with increasing temperature over a wide range of values; between the 90th and 95th percentile an abrupt increase in mortality was observed which was particularly pronounced for the elderly above the age of 65 years, for males, as well as in urban areas and in areas with a high socio-economic status. Daily historical and future temperature values were obtained from the NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset. This dataset is comprised of downscaled climate scenarios for the globe that are derived from the General Circulation Model (GCM) runs conducted under the Coupled Model Intercomparison Project Phase 5 (CMIP5). The derived dose-response functions were used to estimate the number of heat-related deaths occurring during the 1990s (1980-2005), the 2020s (2011-2040) and the 2050s (2041-2070). We estimated that excess deaths due to heat will triple from the 1990s to the 2050s, with an annual number of 0.5 million excess deaths in 1990 to and expected number of 1.5 millions in 2050

Experimental and Computational Analysis of a Large Protein Network That Controls Fat Storage Reveals the Design Principles of a Signaling Network

An approach combining genetic, proteomic, computational, and physiological analysis was used to define a protein network that regulates fat storage in budding yeast (Saccharomyces cerevisiae). A computational analysis of this network shows that it is not scale-free, and is best approximated by the Watts-Strogatz model, which generates “small-world” networks with high clustering and short path lengths. The network is also modular, containing energy level sensing proteins that connect to four output processes: autophagy, fatty acid synthesis, mRNA processing, and MAP kinase signaling. The importance of each protein to network function is dependent on its Katz centrality score, which is related both to the protein’s position within a module and to the module’s relationship to the network as a whole. The network is also divisible into subnetworks that span modular boundaries and regulate different aspects of fat metabolism. We used a combination of genetics and pharmacology to simultaneously block output from multiple network nodes. The phenotypic results of this blockage define patterns of communication among distant network nodes, and these patterns are consistent with the Watts-Strogatz model

Severe Toxic Epidermal Necrolysis and Drug Reaction with Eosinophilia and Systemic Symptoms Overlap Syndrome Treated with Benralizumab: A Case Report

TEN/DRESS overlap syndrome can be difficult to diagnose, especially if it is masked by comorbidities in critically ill patients in intensive care units. The existing therapy for the two conditions is also a major challenge for the treating team. A possible alternative, especially for refractory cases, is benralizumab as an IL-5-receptor alpha-chain-specific humanized monoclonal antibody (IgG1k). We are able to show a successful treatment in this case report

Hilbert-space partitioning of the molecular one-electron density matrix with orthogonal projectors

A double-atom partitioning of the molecular one-electron density matrix is used to describe atoms and bonds. All calculations are performed in Hilbert space. The concept of atomic weight functions (familiar from Hirshfeld analysis of the electron density) is extended to atomic weight matrices. These are constructed to be orthogonal projection operators on atomic subspaces, which has significant advantages in the interpretation of the bond contributions. In close analogy to the iterative Hirshfeld procedure, self-consistency is built in at the level of atomic charges and occupancies. The method is applied to a test set of about 67 molecules, representing various types of chemical binding. A close correlation is observed between the atomic charges and the Hirshfeld-I atomic charges.Comment: 10 pages, 3 figures, preprint, communicatio