bluuebunny/crossref_metadata_2025 huggingface dataset:
The incidence of concussion in youth sports: a systematic review and meta-analysis
Authors: Pfister Ted , Pfister Ken , Hagel Brent , Ghali William A , Ronksley Paul E
Published: December 2015

Objective

To conduct a comprehensive systematic review and meta-analysis of studies assessing the incidence of concussion in youth athletes. Specifically, we estimate the overall risk of concussion in youth sports and compare sport-specific estimates of concussion risk.

Design

Systemic review and meta-analysis.

Data sources

A search of Medline, Embase (1980 through September 2014), and SportDiscus (1985 through September 2014) supplemented by manual searches of bibliographies and conference proceedings.

Inclusion criteria

We included studies if they met the inclusion criteria of study design (prospective cohort study), relevant sports identified from the literature (eg, American football, rugby, hockey, lacrosse, soccer/football, basketball, baseball, softball, wrestling, field hockey, track, taekwondo, volleyball and cheerleading), population (males and females ≤18 years old), and outcome (concussion).

Results

Of the 698 studies reviewed for eligibility, 23 articles were accepted for systematic review and 13 of which were included in a meta-analysis. Random effects models were used to pool overall and sport-specific concussion incidence rates per 1000 athlete exposures (AEs). The overall risk of concussion was estimated at 0.23 (95% CI 0.19 to 0.28). The three sports with the highest incidence rates were rugby, hockey and American football at 4.18, 1.20 and 0.53, respectively. Lowest incidence rates per 1000 AEs occurred in volleyball, baseball and cheerleading at 0.03, 0.06 and 0.07, respectively. Quality of the included studies varied, with the majority of studies not reporting age and gender-specific incidence rates or an operational definition for concussion.

Conclusions

There are striking differences in the rates of incident youth concussion across 12 sports. This systematic review and meta-analysis can serve as the current sport-specific baseline risk of concussion among youth athletes.
Professional Rugby Union players have a 60% greater risk of time loss injury after concussion: a 2-season prospective study of clinical outcomes
Authors: Cross Matthew , Kemp Simon , Smith Andrew , Trewartha Grant , Stokes Keith
Published: December 2015

Aim

To investigate incidence of concussion, clinical outcomes and subsequent injury risk following concussion.

Methods

In a two-season (2012/2013, 2013/2014) prospective cohort study, incidence of diagnosed match concussions (injuries/1000 h), median time interval to subsequent injury of any type (survival time) and time spent at each stage of the graduated return to play pathway were determined in 810 professional Rugby Union players (1176 player seasons).

Results

Match concussion incidence was 8.9/1000 h with over 50% occurring in the tackle. Subsequent incidence of any injury for players who returned to play in the same season following a diagnosed concussion (122/1000 h, 95% CI 106 to 141) was 60% higher (IRR 1.6, 95% CI 1.4 to 1.8) than for those who did not sustain a concussion (76/1000 h, 95% CI 72 to 80). Median time to next injury following return to play was shorter following concussion (53 days, 95% CI 41 to 64) than following non-concussive injuries (114 days, 95% CI 85 to 143). 38% of players reported recurrence of symptoms or failed to match their baseline neurocognitive test during the graduated return to play protocol.

Summary and conclusions

Players who returned to play in the same season after a diagnosed concussion had a 60% greater risk of time-loss injury than players without concussion. A substantial proportion of players reported recurrence of symptoms or failed to match baseline neurocognitive test scores during graduated return to play. These data pave the way for trials of more conservative and comprehensive graduated return to play protocols, with a greater focus on active rehabilitation.
Great Britain Rowing Team Guideline for diagnosis and management of rib stress injury: Part 1
Authors: Evans Guy , Redgrave Ann
Published: December 2015

Background

Rib stress injury (RSI) is the development of pain due to bone oedema caused by overload along the rib shaft and is commonly seen in rowers. Often clinicians who manage this injury are experienced with the condition at the elite level. There may, however, be a lack of confidence in diagnosing and managing this condition by clinicians who are not regularly exposed to this injury. As a result, an evidence-based guideline has been developed to aid diagnosis and management of RSI.

Methods

A detailed literature search was conducted reviewing the diagnosis and management of RSI. Detailed discussions were held by the Great Britain Rowing Medical Team to identify key issues in diagnosis and management of RSI. An up-to-date, evidence-based approach to managing RSI was created using both expert knowledge and current literature to formulate a functional guideline outlining best practice in management of RSI in rowers.

Results

A clinical guideline has been created incorporating 5 key areas: diagnosis, severity grading, investigation, management and associated risk factors for RSI. Important indicators for each key area are incorporated within the guideline using relevant literature where possible alongside expert opinion. The guideline has deliberately been kept concise and tailored for use in the clinical setting.

Conclusions

A new clinical guideline for management of RSIs has been developed to facilitate clinicians in identifying RSI, aiding accurate diagnosis and providing effective management. This guideline is to be disseminated to clinicians, rowing coaches and clubs throughout the UK.
Leadership and followership in the healthcare workplace: exploring medical trainees’ experiences through narrative inquiry
Authors: Gordon Lisi J , Rees Charlotte E , Ker Jean S , Cleland Jennifer
Published: December 2015

Objectives

To explore medical trainees’ experiences of leadership and followership in the interprofessional healthcare workplace.

Design

A qualitative approach using narrative interviewing techniques in 11 group and 19 individual interviews with UK medical trainees.

Setting

Multisite study across four UK health boards.

Participants

Through maximum variation sampling, 65 medical trainees were recruited from a range of specialties and at various stages of training. Participants shared stories about their experiences of leadership and followership in the healthcare workplace.

Methods

Data were analysed using thematic and narrative analysis.

Results

We identified 171 personal incident narratives about leadership and followership. Participants most often narrated experiences from the position of follower. Their narratives illustrated many factors that facilitate or inhibit developing leadership identities; that traditional medical and interprofessional hierarchies persist within the healthcare workplace; and that wider healthcare systems can act as barriers to distributed leadership practices.

Conclusions

This paper provides new understandings of the multiple ways in which leadership and followership is experienced in the healthcare workplace and sets out recommendations for future leadership educational practices and research.
Study protocol for a phase III multicentre, randomised, open-label, blinded-end point trial to evaluate the efficacy and safety of immunoglobulin plus cyclosporin A in patients with severe Kawasaki disease (KAICA Trial)
Authors: Aoyagi Reiko , Hamada Hiromichi , Sato Yasunori , Suzuki Hiroyuki , Onouchi Yoshihiro , Ebata Ryota , Nagashima Kengo , Terauchi Moe , Terai Masaru , Hanaoka Hideki , Hata Akira
Published: December 2015

Introduction

Kawasaki disease (KD) is an acute, self-limited vasculitis of unknown aetiology that predominantly affects infants and young children. We hypothesise that cyclosporin A (CsA) may be effective in treating KD by regulating the Ca2+/NFAT signalling pathway. This trial compares the current standard therapy of intravenous immunoglobulin (IVIG) and the combined IVIG+CsA therapy in paediatric patients with severe KD.

Methods and analysis

This trial is a phase III, multicentre, randomised, open-label, blinded-end point trial that evaluates the efficacy and safety of IVIG+CsA therapy. Patients with severe KD who satisfy the eligibility criteria are randomised (1:1) to receive either CsA (5 mg/kg/day for 5 days; Neoral) plus high-dose IVIG (2 g/kg for 24 h and aspirin 30 mg/kg/day), or high-dose IVIG alone (2 g/kg for 24 h and aspirin 30 mg/kg/day). The primary end point is the frequency of occurrence of coronary artery abnormalities during the trial period. An independent end point review committee will be in charge of the trial assessment.

Ethics and dissemination

The protocol was approved by the Institutional Review Board of each institution. The trial was notified and registered at the Pharmaceutical and Medical Devices Agency, in Japan. The trial is currently on-going and is scheduled to finish in April 2017. The findings will be disseminated through peer-reviewed publications and conference presentations.

Trial registration number

JMA-IIA00174; Pre-results.
Physiological and biochemical variables in captive tigers (Panthera tigris) immobilised with dexmedetomidine and ketamine or dexmedetomidine, midazolam and ketamine
Authors: Clark‐Price S. C. , Lascola K. M. , Schaeffer D. J.
Published: December 2015

Physiological and biochemical variables in captive tigers (Panthera tigris) immobilised with dexmedetomidine and ketamine or dexmedetomidine, midazolam and ketamine were evaluated. Thirty tigers received either dexmedetomidine (0.025 mg/kg) and ketamine (3 mg/kg) (group DK) or dexmedetomidine (0.0125 mg/kg), midazolam (0.1 mg/kg) and ketamine (3 mg/kg) (group DMK). Heart rate, SPO2and blood pressure were measured at five‐minute intervals. Arterial pH, PO2, PCO2, glucose, K+and arterial and venous lactate were measured at 15 and 45 minutes after immobilisation. A generalised linear mixed model was used for statistical comparison. There was no difference within or between groups at any time point for any measured variable. Measured PO2was 73.2±17.5 mm Hg and SPO2was 88.9±10.8 per cent. Systolic, mean and diastolic blood pressures were 170.5±48.4, 138.9±41.8 and 121.8±37.2 mm Hg, respectively. Venous lactate was higher than arterial lactate within groups at each time point. Seizure‐like behaviour was observed in 25 per cent of tigers in group DK but not in group DMK. The addition of midazolam into a protocol for immobilisation of tigers did not result in a difference in any of the measured variables but may have prevented the development of seizure‐like behaviour.
Optimizing the selection of sustainability measures to minimize life-cycle cost of existing buildings
Authors: Abdallah Moatassem , El-Rayes Khaled , Liu Liang
Published: December 2015

Buildings have significant impacts on the environment and economy as they were reported by the World Business Council for Sustainable Development in 2009 to account for 40% of the global energy consumption. Building owners are increasingly seeking to integrate sustainability and green measures in their buildings to minimize energy and water consumption as well as life-cycle cost. Due to the large number of feasiblecombinations of sustainability measures, decision makers are often faced with a challenging task that requires them to identify an optimal set of upgrade measures to minimize the building life-cycle cost. This paper presents a model for optimizing the selection of building upgrade measures to minimize the life-cycle cost of existing buildings while complying with owner-specified requirements for building operational performance and budget constraints. The optimization model accounts for initial upgrade cost, operational cost and saving, escalation in utility costs, maintenance cost, replacement cost, and salvage value of building fixtures and equipment, and renewable energy systems. A case study of a rest area building in the state of Illinois in the United States was analyzed to illustrate the unique capabilities of the developed optimization model. The main findings of this analysis illustrate the capabilities of the model in identifying optimal building upgrade measures to achieve the highest savings of building life-cycle cost within a user-specified upgrade budget; and generating practical and detailed recommendations on replacing building fixtures and equipment and installing renewable energy systems.
Appearance–disappearance relation in 3 + Ns short-baseline neutrino oscillations
Authors: Giunti C. , Zavanin E. M.
Published: December 2015

We derive the relation between the amplitudes of short-baseline appearance and disappearance oscillations in [Formula: see text] neutrino mixing schemes which is the origin of the appearance–disappearance tension that is found from the analysis of the existing data in any [Formula: see text] neutrino mixing scheme. We illustrate the power of the relation to reveal the appearance–disappearance tension in the cases of [Formula: see text] and [Formula: see text] mixing using the results of global fits of short-baseline neutrino oscillation data.
Study on Cycle Life of Lithium-Ion Batteries Using in Situ
7Li Solid-State Nuclear Magnetic Resonance
Authors: Arai Juichi , Nakahigashi Rie , Sugiyama Teruyasu
Published: December 2015

The capacity fade of lithium ion battery (LIB) was investigated using 7Li solid-state nuclear magnetic resonance (NMR). The LIB cells composed of graphite (Gr) or hard carbon (HC) and LiCoO2 (LCO) were used. The peak intensity for stored Li in carbon (Gr and HC) showed good proportionality to the cell capacity. The proportional constants for every after 100 cycles did not change largely, while the section of the peak intensity vs. cell capacity plot changed with cycle. This change in the section explained well the cell capacity fade, showing that “slippage” was related to the capacity loss in lower stages due to voltage profile of carbons. The peak analysis also found “captured” Li loss as another cause of capacity fade. The NMR measurement also found new storage peak and change in solid electrolyte interface (SEI) related peak after long cycle test.
Conductivity Enhancement and Thin-Film Processing of Li4Ti5O12(LTO) Spinel for Li Battery Applications
Authors: Tsai Shu-Yi , Fung Kuan-Zong , Ni Chung-Ta
Published: December 2015

Spinel Li4Ti5O12 has been considered as one of the most prospective anode materials for Li-ion microbatteries. Homogeneous and crack-free Li4Ti5O12 film with thickness around 200 nm have been deposited on Pt/Ti/SiO2/Si(100) substrate by r.f. magnetron sputtering. The influence of the post-annealing treatment on the phase composition, structure and electrochemical behavior was studied. The Li/Ti molar ratio in the films decreased with an increasing oxygen fraction. The amount of Li4Ti5O12 phase increases with the annealing temperature increasing from 500°C to 700°C. Electrochemical characterization of samples treated at 600°C presents a redox reaction around 1.55 V indicating that the film contains Li4Ti5O12 spinel. Larger capacity and good reversibility in the sample post-annealing treatment at 600 °C can be attributed to high crystallinity of Li4Ti5O12 and amorphous TiO2 phase.
Electrochemical Stability of PEDOT:PSS As Cathodic Binder for Li-Ion Batteries
Authors: Das Pratik Ranjan , Komsiyska Lidiya , Osters Oliver , Wittstock Gunther
Published: December 2015

The electrodes in Li-ion batteries consist of multiple components such as active materials, conductive additives and polymeric binder. The polymeric binder influences significantly the properties and stability of the composite electrode and the overall battery performance. We proposed the application of poly-3,4-ethylendioxythiophen: polystyrene sulfonic acid (PEDOT:PSS) poly-ion complex as a conductive binder material for cathodes in lithium ion battery. In this paper we report the electrochemical behavior and stability of PEDOT:PSS in battery electrolyte in terms of cyclic voltammetry and electrochemical impedance spectroscopy. The impedance behavior of PEDOT:PSS has been studied at different ambient temperatures and the ionic and electronic conductivities of PEDOT:PSS has been evaluated using a modified transmission line model. PEDOT:PSS shows stable behavior during multiple cycling in the operated potential range up to 4.2 V and no change in the impedance was visible after 200 cycles.
Method for Dimensioning Battery and Thermal Management Systems for Heavy-Duty Vehicle Applications Using Aged Battery Experimental Data and Advanced Modelling Techniques
Authors: Kukkonen Samu , Erkkila Ville , Manninen Aino , Haavisto Jari , Pihlatie Mikko
Published: December 2015

During the life of a Li-Ion battery, capacity and power capability fade. Despite this degradation, an electric vehicle battery needs to deliver designed power performance until battery end-of-life. Comprehension of battery performance degradation is required to design sufficient margin for power capability and thermal management. This paper proposes battery laboratory testing combined with advanced modelling techniques to obtain design parameters based on aged batteries. Laboratory cell aging and characterization tests are performed to parametrise models, which are used to verify electric city bus battery performance at various lifetime levels. The modelling gives an indication on the level of margin that needs to be designed for power capability and thermal management. The results obtained indicate that from performance point of view, the battery that was studied can be utilized well beyond 80% capacity point while still retaining power capability and low cell level power losses.
Investigation of the Graphene Supported Platinum-Tungsten Catalysts Prepared by Microwave Synthesis as Electrocatalysts for Borohydride Oxidation
Authors: Kilmonis Teofilius , Tamasauskaite-Tamasiunaite Loreta , Balciunaite Aldona , Vaiciuniene Jurate , Norkus Eugenijus
Published: December 2015

In this study a rapid microwave heating method was used to prepare the graphene supported platinum-tungsten catalysts with the different Pt:W molar ratios. The prepared catalysts were characterized by means of Transmission Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy. The electrocatalytic properties of the PtW/GR catalysts towards the oxidation of borohydride in an alkaline medium were investigated by means of cyclic voltammetry and chrono-techniques. It was found that the graphene supported platinum-tungsten catalysts with the Pt:W molar ratios equal to 1.6:1, 2.4:1 and 7.1:1 were prepared. The synthesized PtW/GR catalysts with the different Pt:W molar ratios show an enhanced electrocatalytic activity towards the oxidation of H2 generated by catalytic hydrolysis of BH4
– and direct oxidation of BH4
– comparing with the graphene supported bare W catalyst.
Evaluation of Activity of Platinum-Ruthenium-Cobalt/Graphene Catalysts towards Methanol Oxidation
Authors: Semasko Miroslav , Tamasauskaite-Tamasiunaite Loreta , Kepeniene Virginija , Balciunaite Aldona , Vaiciuniene Jurate , Drabavicius Audrius , Norkus Eugenijus
Published: December 2015

In this study a series of PtRuCo/GR with the different molar ratios were prepared by microwave-assisted heating of the reaction mixture consisting of H2PtCl6, RuCl3, CoCl2 and ethylene glycol. The Transmission Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy were employed to characterize the synthesized PtRuCo/GR catalysts. The electrocatalytic activity of the synthesized catalysts towards the oxidation of methanol was investigated by means of cyclic voltammetry and chronoamperometry. It was found that the PtRuCo/GR catalysts with the Pt:Ru:Co molar ratios equal to 1:2:2, 1:1.7:5.6 and 3.5:1:23 were prepared. The PtRuCo/GR catalyst with the Pt:Ru:Co molar ratio equal to 3.5:1:23 has a higher electrocatalytic activity towards the oxidation of methanol in acidic medium as compared with that of other synthesized catalysts.
SIPN Systems Used as Membranes for Fuel Cell
Authors: Loureiro Felipe Augusto Moro , Rocco Ana Maria
Published: December 2015

Membranes must show chemical, electrochemical and dimensional stability and proton conductivity for application as a Polymer Electrolyte Membrane in Fuel Cells. The Semi-interpenetrating polymer network membranes (SIPN) obtained in this work were synthesized from polyethyleneimine and diglycidyl ether of bisphenol A with curing agent 4,4' diaminodiphenyl-sulphone. The membranes were studied while immersed in H3PO4 and after sulfonation. The samples were characterized by FTIR, TGA, DSC and electrochemical Impedance Spectroscopy (EIS). The SIPN membranes show high thermal stability above 270oC, which is sufficient for their application in PEMFC for intermediate temperature operation. The membrane doped with 20% H3PO4 shows higher conductivity value, 0,08 S.cm-1, than the sulfonated samples,10-2 Scm-1.
Characterization of Carbon Fiber Electrode for Vanadium-Based Redox Flow Batteries
Authors: Narita Ayumi , Kaneko Yuji , Sato Yukari , Negishi Akira , Nozaki Ken , Kato Tohru
Published: December 2015

Electrochemical properties for two kinds of carbon felt electrodes were evaluated using single filament electrodes. Results of cyclic voltammogram (CV) measurements for both carbon fiber electrodes showed wide potential windows (-1.0 ~ +1.9 V vs. Ag/AgCl). In the case of felt sample 1 (thin electrode), which was actually used in the vanadium-based RFB, dispersion of oxidation and reduction peaks was smaller than that of sample 2 (thick electrode, general carbon felt electrode). Redox responses were also measured in the vanadium electrolyte. Sample 1 electrode showed low dispersion in redox responses and had suitable electrochemical property for vanadium-based RFBs.
The Effect of PFSA Membrane Compression on the Predicted Performance of a High Pressure PEM Electrolysis Cell
Authors: Olesen Anders Christian , Kær Soren Knudsen
Published: December 2015

In this work, a non-equilibrium formulation of a compression dependent water uptake model has been implemented in a two-dimensional, two-phase, multi-component and non-isothermal high pressure PEM electrolysis model. The non-equilibrium formulation of the water uptake model was chosen in order to account for interfacial transport kinetics between each fluid phase and the perfluorinated sulfonic acid membrane. Besides modeling water uptake, the devised membrane model accounts for water transport through diffusion and electro-osmotic drag in the electrolyte phase, and hydraulic permeation in the liquid phase. Charge transport and electrochemistry are likewise included. The obtained model is validated against experimental measurements. In order to investigate the effect of membrane compression, a parametric study is carried. Results underline that the predicted water uptake and cell voltage are highly dependent on the applied water uptake model depending on operation conditions like temperature and the specific surface area of the ionomer in the catalyst layer.
An Electrochemical Impedance Spectroscopy Study and Two Phase Flow Analysis of the Anode of Polymer Electrolyte Membrane Water Electrolyser
Authors: Dedigama Ishanka , Brett Daniel J.L , Mason Thomas J. , Millichamp Jason , Shearing Paul R. , Ayers Katherine E
Published: December 2015

The effect of water flow rate on the performance of a polymer electrolyte membrane water electrolyser (PEMWE) was studied using an unpressurised lab-scale (25 cm2) cell. The linear polarisation curves obtained showed a voltage increase at higher current densities that increased with water flow rate. Electrochemical impedance spectroscopy (EIS) showed that while lower water flow rates lead to higher cell temperatures and reduced membrane resistance, mass transport losses dominate at high current density. As the water flow is exclusively in the bubbly regime, increase in mass transport limitation is attributed to bubble formation dynamics and reduced gas void fraction at higher water flow rates.
New Low to Medium Temperature Electrolyte Separation Method and System for Alkaline Water Electrolysis
Authors: Hartvigsen Jeremy , Smith Joseph , Dogan Fatih
Published: December 2015

A new electrolysis method of maintaining product gas separation by using fluid flow perpendicularly through porous electrodes rather than using a gas impermeable membrane has been developed. This eliminates the need for any type of membrane. Eliminating the need for a membrane in alkaline electrolysis allows the device to operate at temperatures above 120 °C, where most ion conducting membranes would degrade and fail. Operating at higher temperatures reduces the anode and cathode overpotentials substantially. The reduction in overpotentials allows non-platinum group metals to be used, while increasing the electrical efficiency at comparable current densities.
Evaluation of Oxygen Reduction Activity of Non-Ideal Pt Based Catalyst Thin Films
Authors: Jovanovič Primoz , Pavlišič Andraz , Bele Marjan , Hočevar Stanko , Hodnik Nejc , Gaberšček Miran
Published: December 2015

It is demonstrated that, using thin film electrochemical rotating disc electrode (TF-RDE), oxygen reduction reaction (ORR) activity can be reliably evaluated even from non-ideal (non-uniform) thin platinum-based high-surface area catalyst films. Namely, the classical evaluation (kinetic current density at fixed potential of 0.9 V vs. RHE) is only possible if the catalyst film is close to ideal (uniform and of appropriate thickness), which is sometimes difficult or even impossible to obtain. We propose an alternative way of activity evaluation, which is based on determination of potential at the fixed kinetic current density of 0.1 mAcm-2
Pt. Performing a case study on ideal and purposely flawed (non-ideal) PtCu/C catalyst films we prove the reliability of the proposed method and a systematically lower error compared to the the conventional fixed-voltage method. We show that Pt-alloy nanoparticles ORR activities can vary from 0.2 to as high as 6.4 mAcm-2 by varying the amount of less nobel metal content and by increasing the amount of ordered crystalline PtX3 phase. In addition, we provide a direct correlation between the two activities.
Density Functional Theory Study of CO2 Adsorption and Reduction on Stoichiometric and Doped Ceria
Authors: Kumari Neetu , Haider M Ali , Sinha Nishant , Basu Suddhasatwa
Published: December 2015

Periodic density functional theory (DFT) calculations were performed to estimate the adsorption energies of the reactant, product and intermediates for CO2 reduction to methanol on stoichiometric and doped CeO2 (110) surface. A planar structure of CO2 was considered to adsorb on stoichiometric ceria surface with a binding energy of -23.4 kJ/mol. The planar structure is likely to participate in CO2 hydrogenation reactions via the formation of formate (HCOO) or carboxyl (COOH) intermediate. Between the two intermediates, the carboxyl mediated route shows all the way exothermic steps and is likely to produce methanol. Ceria based materials have been suggested to possess high catalytic and electrocatalytic activity for CO2 reduction which can be further improved by aliovalent metal dopants. Surface of ceria was doped with aliovalent dopants such as Gd, Pr and Sm. The calculated adsorption energies of CO2 on doped ceria were comparable to stoichiometric ceria. Electronic structure calculations plotted in the form of projected density of states showed reduced band gaps for Gd doped ceria as compared to bulk ceria, suggesting towards higher electronic conductivities of the doped ceria materials.
Modelling and Validation of Water Hydration of PEM Fuel Cell Membrane in Dynamic Operations
Authors: Liso Vincenzo , Nielsen Mads Pagh
Published: December 2015

Fuel cells convert chemical energy of hydrogen and oxygen directly in to electricity. High efficiency and zero emission have made them a prime candidate for powering the next generation of electric vehicles. PEM fuel cells require good hydration in order to deliver high performance and ensure long life operation. Water is essential for membrane proton conductivity which increases by nearly six orders of magnitude from dry to fully hydrated. Adequate water management in PEM fuel cell is crucial in order to avoid an imbalance between water production and water removal from the fuel cell. In the present study, a novel mathematical zero-dimensional model has been formulated for the water mass balance and hydration of a polymer electrolyte membrane. This model incorporates all the essential fundamental physical and electrochemical processes occurring in the membrane electrolyte and considers the water adsorption/desorption phenomena in the membrane. The effect of diffusivity model, surface roughness and water content driving force is considered. The model is validated against experimental data. Many studies have considered fuel cell membrane in equilibrium condition disregarding non-ficknian behavior of the cell membrane. The present model consider absorption/desorption mechanism typical of dynamic process and for this reason it becomes useful when studying PEM fuel cell system in dynamic conditions.
CFTR silencing in pancreatic β-cells reveals a functional impact on glucose-stimulated insulin secretion and oxidative stress response
Authors: Ntimbane Thierry , Mailhot Geneviève , Spahis Schohraya , Rabasa-Lhoret Remi , Kleme Marie-Laure , Melloul Danielle , Brochiero Emmanuelle , Berthiaume Yves , Levy Emile
Published: December 2015

Cystic fibrosis (CF)-related diabetes (CFRD) has become a critical complication that seriously affects the clinical outcomes of CF patients. Although CFRD has emerged as the most common nonpulmonary complication of CF, little is known about its etiopathogenesis. Additionally, whether oxidative stress (OxS), a common feature of CF and diabetes, influences CFRD pathophysiology requires clarification. The main objective of this study was to shed light on the role of the cystic fibrosis transmembrane conductance regulator (CFTR) in combination with OxS in insulin secretion from pancreatic β-cells. CFTR silencing was accomplished in MIN6 cells by stable expression of small hairpin RNAs (shRNA), and glucose-induced insulin secretion was evaluated in the presence and absence of the valuable prooxidant system iron/ascorbate (Fe/Asc; 0.075/0.75 mM) along with or without the antioxidant Trolox (1 mM). Insulin output from CFTR-silenced MIN6 cells was significantly reduced (∼70%) at basal and at different glucose concentrations compared with control Mock cells. Furthermore, CFTR silencing rendered MIN6 cells more sensitive to OxS as evidenced by both increased lipid peroxides and weakened antioxidant defense, especially following incubation with Fe/Asc. The decreased insulin secretion in CFTR-silenced MIN6 cells was associated with high levels of NF-κB (the major participant in inflammatory responses), raised apoptosis, and diminished ATP production in response to the Fe/Asc challenge. However, these defects were alleviated by the addition of Trolox, thereby pointing out the role of OxS in aggravating the effects of CFTR deficiency. Our findings indicate that CFTR deficiency in combination with OxS may contribute to endocrine cell dysfunction and insulin secretion, which at least in part may explain the development of CFRD.
CX3CL1—a macrophage chemoattractant induced by a single bout of exercise in human skeletal muscle
Authors: Strömberg Anna , Olsson Karl , Dijksterhuis Jacomijn P. , Rullman Eric , Schulte Gunnar , Gustafsson Thomas
Published: December 2015

Monocytes/macrophages (MOs/MΦs) are suggested to be crucial for skeletal muscle repair and remodeling. This has been attributed to their proangiogenic potential, secretion of growth factors, and clearance of tissue debris. Skeletal muscle injury increases the number of MΦs in the tissue, and their importance for muscle regeneration has been supported by studies demonstrating that depletion of MOs/MΦs greatly impairs repair after muscle injury. Whether noninjurious exercise leads to induced expression of chemoattractants for MOs/MΦs is poorly investigated. To this end, we analyzed the expression of CX3CL1 (fractalkine), CCL2 (MCP-1), and CCL22 (MDC) in human skeletal muscle after a bout of exercise, all of which are established MO/MΦ chemotactic factors that are expressed by human myoblasts. Muscle biopsies from the musculus vastus lateralis were obtained up to 24 h after 1 h of cycle exercise in healthy individuals and in age-matched nonexercised controls. CX3CL1 increased at both the mRNA and protein level in human skeletal muscle after one bout of exercise. It was not possible to distinguish changes in CCL2 or CCL22 mRNA levels between biopsy vs. exercise effects, and the expression of CCL22 was very low. CX3CL1 mainly localized to the skeletal muscle endothelium, and it increased in human umbilical vein endothelial cells stimulated with tissue fluid from exercised muscle. CX3CL1 increased the expression of proinflammatory and proangiogenic factors in THP-1 monocytes (a human acute monocytic leukemia cell line) and in human primary myoblasts and myotubes. Altogether, this suggests that CX3CL1 participates in cross-talk mechanisms between endothelium and other muscle tissue cells and may promote a shift in the microenvironment toward a more regenerative milieu.
Maternal protein restriction compromises myocardial contractility in the young adult rat by changing proteins involved in calcium handling
Authors: de Belchior Aucelia C. S. , Freire David D. , da Costa Carlos P. , Vassallo Dalton V. , Padilha Alessandra S. , dos Santos Leonardo
Published: December 2015

Maternal protein restriction (MPR) during pregnancy is associated with increased cardiovascular risk in the offspring in adulthood. In this study we evaluated the cardiac function of young male rats born from mothers subjected to MPR during pregnancy, focusing on the myocardial mechanics and calcium-handling proteins. After weaning, rats received normal diet until 3 mo old, when the following parameters were assessed: arterial and left ventricular hemodynamics and in vitro cardiac contractility in isolated papillary muscles. The body weight was lower and arterial pressure higher in the MPR group compared with young adult offspring of female rats that received standard diet (controls); and left ventricle time derivatives increased in the MPR group. The force developed by the cardiac muscle was similar; but time to peak and relaxation time were longer, and the derivatives of force were depressed in the MPR. In addition, MPR group exhibited decreased post-pause potentiation of force, suggesting reduced reuptake function of the sarcoplasmic reticulum. Corroborating, the myocardial content of SERCA-2a and phosphorylated PLB-Ser16/total PLB ratio was decreased and sodium-calcium exchanger was increased in the MPR group. The contraction dependent on transsarcolemmal influx of calcium was higher in MPR if compared with the control group. In summary, young rats born from mothers subjected to protein restriction during pregnancy exhibit changes in the myocardial mechanics with altered expression of calcium-handling proteins, reinforcing the hypothesis that maternal malnutrition is related to increased cardiovascular risk in the offspring, not only for hypertension, but also cardiac dysfunction.
Interindividual variability in the dose-specific effect of dopamine on carotid chemoreceptor sensitivity to hypoxia
Authors: Limberg Jacqueline K. , Johnson Blair D. , Holbein Walter W. , Ranadive Sushant M. , Mozer Michael T. , Joyner Michael J.
Published: December 2015

Human studies use varying levels of low-dose (1-4 μg·kg−1·min−1) dopamine to examine peripheral chemosensitivity, based on its known ability to blunt carotid body responsiveness to hypoxia. However, the effect of dopamine on the ventilatory responses to hypoxia is highly variable between individuals. Thus we sought to determine 1) the dose response relationship between dopamine and peripheral chemosensitivity as assessed by the ventilatory response to hypoxia in a cohort of healthy adults, and 2) potential confounding cardiovascular responses at variable low doses of dopamine. Young, healthy adults ( n = 30, age = 32 ± 1, 24 male/6 female) were given intravenous (iv) saline and a range of iv dopamine doses (1–4 μg·kg−1·min−1) prior to and throughout five hypoxic ventilatory response (HVR) tests. Subjects initially received iv saline, and after each HVR the dopamine infusion rate was increased by 1 μg·kg−1·min−1. Tidal volume, respiratory rate, heart rate, blood pressure, and oxygen saturation were continuously measured. Dopamine significantly reduced HVR at all doses ( P < 0.05). When subjects were divided into high ( n = 13) and low ( n = 17) baseline chemosensitivity, dopamine infusion (when assessed by dose) reduced HVR in the high group only ( P < 0.01), with no effect of dopamine on HVR in the low group ( P > 0.05). Dopamine infusion also resulted in a reduction in blood pressure (3 μg·kg−1·min−1) and total peripheral resistance (1–4 μg·kg−1·min−1), driven primarily by subjects with low baseline chemosensitivity. In conclusion, we did not find a single dose of dopamine that elicited a nadir HVR in all subjects. Additionally, potential confounding cardiovascular responses occur with dopamine infusion, which may limit its usage.
Effects of carbon monoxide-releasing molecules on pulmonary vasoreactivity in isolated perfused lungs
Authors: Pak Oleg , Bakr Adel G. , Gierhardt Mareike , Albus Julia , Strielkov Ievgen , Kroschel Florian , Hoeres Timm , Hecker Matthias , Ghofrani Hossein A. , Seeger Werner , Weissmann Norbert , Sommer Natascha
Published: December 2015

In addition to its renowned poisonous effects, carbon monoxide (CO) is being recognized for its beneficial actions on inflammatory and vasoregulatory pathways, particularly when applied at low concentrations via CO-releasing molecules (CO-RMs). In the lung, CO gas and CO-RMs are suggested to decrease pulmonary vascular tone and hypoxic pulmonary vasoconstriction (HPV). However, the direct effect of CO-RMs on the pulmonary vasoreactivity in isolated lungs has not yet been investigated. We assessed the effect of CORM-2 and CORM-3 on the pulmonary vasculature during normoxia and acute hypoxia (1% oxygen for 10 min) in isolated ventilated and perfused mouse lungs. The effects were compared with those of inhaled CO gas (10%). The interaction of CORM-2 or CO with cytochrome P-450 (CYP) was measured simultaneously by tissue spectrophotometry. Inhaled CO decreased HPV and vasoconstriction induced by the thromboxane mimetic U-46619 but did not alter KCl-induced vasoconstriction. In contrast, concentrations of CORM-2 and CORM-3 used to elicit beneficial effects on the systemic circulation did not affect pulmonary vascular tone. High concentration of CO-RMs or long-term application induced a continuous increase in normoxic pressure. Inhaled CO showed spectral alterations correlating with the inhibition of CYP. In contrast, during application of CORM-2 spectrophotometric signs of interaction with CYP could not be detected. Application of CO-RMs in therapeutic doses in isolated lungs neither decreases pulmonary vascular tone and HPV nor does it induce spectral alterations that are characteristic of CO-inhibited CYP. High doses, however, may cause pulmonary vasoconstriction.
A method to test contractility of the supraspinatus muscle in mouse, rat, and rabbit
Authors: Valencia Ana P. , Iyer Shama R. , Pratt Stephen J. P. , Gilotra Mohit N. , Lovering Richard M.
Published: December 2015

The rotator cuff (RTC) muscles not only generate movement but also provide important shoulder joint stability. RTC tears, particularly in the supraspinatus muscle, are a common clinical problem. Despite some biological healing after RTC repair, persistent problems include poor functional outcomes with high retear rates after surgical repair. Animal models allow further exploration of the sequela of RTC injury such as fibrosis, inflammation, and fatty infiltration, but there are few options regarding contractility for mouse, rat, and rabbit. Histological findings can provide a “direct measure” of damage, but the most comprehensive measure of the overall health of the muscle is contractile force. However, information regarding normal supraspinatus size and contractile function is scarce. Animal models provide the means to compare muscle histology, imaging, and contractility within individual muscles in various models of injury and disease, but to date, most testing of animal contractile force has been limited primarily to hindlimb muscles. Here, we describe an in vivo method to assess contractility of the supraspinatus muscle and describe differences in methods and representative outcomes for mouse, rat, and rabbit.
Transfer of tactile perceptual learning to untrained neighboring fingers reflects natural use relationships
Authors: Dempsey-Jones Harriet , Harrar Vanessa , Oliver Jonathan , Johansen-Berg Heidi , Spence Charles , Makin Tamar R.
Published: December 2015

Tactile learning transfers from trained to untrained fingers in a pattern that reflects overlap between the representations of fingers in the somatosensory system (e.g., neurons with multifinger receptive fields). While physical proximity on the body is known to determine the topography of somatosensory representations, tactile coactivation is also an established organizing principle of somatosensory topography. In this study we investigated whether tactile coactivation, induced by habitual inter-finger cooperative use (use pattern), shapes inter-finger overlap. To this end, we used psychophysics to compare the transfer of tactile learning from the middle finger to its adjacent fingers. This allowed us to compare transfer to two fingers that are both physically and cortically adjacent to the middle finger but have differing use patterns. Specifically, the middle finger is used more frequently with the ring than with the index finger. We predicted this should lead to greater representational overlap between the former than the latter pair. Furthermore, this difference in overlap should be reflected in differential learning transfer from the middle to index vs. ring fingers. Subsequently, we predicted temporary learning-related changes in the middle finger's representation (e.g., cortical magnification) would cause transient interference in perceptual thresholds of the ring, but not the index, finger. Supporting this, longitudinal analysis revealed a divergence where learning transfer was fast to the index finger but relatively delayed to the ring finger. Our results support the theory that tactile coactivation patterns between digits affect their topographic relationships. Our findings emphasize how action shapes perception and somatosensory organization.
Early postnatal switch in GABAA receptor α-subunits in the reticular thalamic nucleus
Authors: Pangratz-Fuehrer Susanne , Sieghart Werner , Rudolph Uwe , Parada Isabel , Huguenard John R.
Published: December 2015

The GABAergic neurons of the thalamic reticular nucleus (nRt) provide the primary source of inhibition within the thalamus. Using physiology, pharmacology, and immunohistochemistry in mice, we characterized postsynaptic developmental changes in these inhibitory projection neurons. First, at postnatal days 3–5 (P3-5), inhibitory postsynaptic currents (IPSCs) decayed very slowly, followed by a biphasic developmental progression, becoming faster at P6-8 and then slower again at P9-11 before stabilizing in a mature form around P12. Second, the pharmacological profile of GABAA receptor (GABAAR)-mediated IPSCs differed between neonatal and mature nRt neurons, and this was accompanied by reciprocal changes in α3 (late) and α5 (early) subunit expression in nRt. Zolpidem, selective for α1- and α3-containing GABAARs, augmented only mature IPSCs, whereas clonazepam enhanced IPSCs at all stages. This effect was blocked by the α5-specific inverse agonist L-655,708, but only in immature neurons. In α3(H126R) mice, in which α3-subunits were mutated to become benzodiazepine insensitive, IPSCs were enhanced compared with those in wild-type animals in early development. Third, tonic GABAAR activation in nRt is age dependent and more prominent in immature neurons, which correlates with early expression of α5-containing GABAARs. Thus neonatal nRt neurons show relatively high expression of α5-subunits, which contributes to both slow synaptic and tonic extrasynaptic inhibition. The postnatal switch in GABAAR subunits from α5 to α3 could facilitate spontaneous network activity in nRt that occurs at this developmental time point and which is proposed to play a role in early circuit development.
Optogenetic spatial and temporal control of cortical circuits on a columnar scale
Authors: Roy Arani , Osik Jason J. , Ritter Neil J. , Wang Shen , Shaw James T. , Fiser József , Van Hooser Stephen D.
Published: December 2015

Many circuits in the mammalian brain are organized in a topographic or columnar manner. These circuits could be activated—in ways that reveal circuit function or restore function after disease—by an artificial stimulation system that is capable of independently driving local groups of neurons. Here we present a simple custom microscope called ProjectorScope 1 that incorporates off-the-shelf parts and a liquid crystal display (LCD) projector to stimulate surface brain regions that express channelrhodopsin-2 (ChR2). In principle, local optogenetic stimulation of the brain surface with optical projection systems might not produce local activation of a highly interconnected network like the cortex, because of potential stimulation of axons of passage or extended dendritic trees. However, here we demonstrate that the combination of virally mediated ChR2 expression levels and the light intensity of ProjectorScope 1 is capable of producing local spatial activation with a resolution of ∼200–300 μm. We use the system to examine the role of cortical activity in the experience-dependent emergence of motion selectivity in immature ferret visual cortex. We find that optogenetic cortical activation alone—without visual stimulation—is sufficient to produce increases in motion selectivity, suggesting the presence of a sharpening mechanism that does not require precise spatiotemporal activation of the visual system. These results demonstrate that optogenetic stimulation can sculpt the developing brain.
Lipopolysaccharide Increases Immune Activation and Alters T Cell Homeostasis in SHIVB’WHUChronically Infected Chinese Rhesus Macaque
Authors: Zhang Gao-Hong , Wu Run-Dong , Zheng Hong-Yi , Zhang Xiao-Liang , Zhang Ming-Xu , Tian Ren-Rong , Liu Guang-Ming , Pang Wei , Zheng Yong-Tang
Published: December 2015

Immune activation plays a significant role in the disease progression of HIV. Microbial products, especially bacterial lipopolysaccharide (LPS), contribute to immune activation. Increasing evidence indicates that T lymphocyte homeostasis disruptions are associated with immune activation. However, the mechanism by which LPS affects disruption of immune response is still not fully understood. Chronically SHIVB’WHU-infected Chinese rhesus macaques received 50 μg/kg body weight LPS in this study. LPS administration affected the virus/host equilibrium by elevating the levels of viral replication and activating T lymphocytes. LPS induced upregulation of CD8+naïve T cells and downregulated the number of CD4+and CD8+T effector memory cells. The downregulated effector memory cells are associated with a lower frequency of monofunctional and polyfunctional cells, and an upregulated programmed cell death-1 (PD-1) expression on CD4+and CD8+T cells was observed in monkeys after LPS stimulation. Our data provide new insights into the function of LPS in the immune activation in SHIV/HIV infection.