bluuebunny/crossref_metadata_2025 huggingface dataset:
Poling Field Dependence of Longitudinal and Transverse Wave Velocities, Young's Modulus, and Poisson's Ratio in Piezoelectric Ceramics
Authors: Ogawa Toshio , Ishii Keisuke , Matsumoto Tsubasa , Nishina Takayuki
Published: September 2012

The longitudinal and transverse wave velocities in lead zirconate titanate (PZT), lead titanate, and lead-free ceramics vs DC poling fields were measured using an ultrasonic precision thickness gauge with high-frequency pulse oscillation to evaluate elastic constants, such as Young's modulus and Poisson's ratio. With the enhancement of domain alignment with the increase in poling field, the longitudinal wave velocity increased and the transverse wave velocity decreased independently of the ceramic composition. It was found that there was an important factor for obtaining a high piezoelectricity regarding Young's modulus and Poisson's ratio, that is, the low Young's modulus and high Poisson's ratio in the cases of PZT, alkali bismuth titanate, and alkali bismuth barium titanate with morphotropic phase boundaries (MPBs), and alkali niobate without MPBs. Furthermore, the increase in planar coupling factor corresponds to the increase in Poisson's ratio at all compositions including lead-containing and lead-free ceramic compositions. It was possible to divide the ceramics on the basis of longitudinal and transverse wave velocities into three groups, namely, PZT and lead titanate modified by 2.5 mol % lanthanum, alkali bismuth titanate and lead titanate modified by 10 mol % lanthanum, and alkali niobate.
Microstructure of BaTiO3–Bi(Mg1/2Ti1/2)O3–BiFeO3Piezoelectric Ceramics
Authors: Yabuta Hisato , Shimada Mikio , Watanabe Takayuki , Hayashi Jumpei , Kubota Makoto , Miura Kaoru , Fukui Tetsuro , Fujii Ichiro , Wada Satoshi
Published: September 2012

The dependence of the ferroelectric and piezoelectric properties of (1-x)(0.33BaTiO3–0.67BiFeO3)–xBi(Mg1/2Ti1/2)O3(x= 0, 0.05, 0.10, and 0.15) on Bi(Mg1/2Ti1/2)O3contentxassociated with microstructural changes is studied. From the behaviour of electric field-induced polarization and strain, polarization switching and depolarizing become easier as Bi(Mg1/2Ti1/2)O3contentxincreases. Remanent polarization and dielectric constant decrease, while polarization saturation field increases with increasingx. Microstructural observation reveals that Bi(Mg1/2Ti1/2)O3addition enhances the compositional fluctuation of BaTiO3/BiFeO3ratio, which probably creates a nanometre-sized domain region with slightly BaTiO3-rich composition. Since this nanometre-sized domain may cause relatively large responses of polarization and strain to the applied electric field, an appropriate amount of Bi(Mg1/2Ti1/2)O3enhances the electric field-induced strain, resulting in the largest piezoelectric response atx= 0.05. However, excessive Bi(Mg1/2Ti1/2)O3degrades polarization and strain characteristics, because a number of Ba(Fe1-xMgx/2Tix/2)12O19grains are created as a secondary phase and cause the segregation of excess bismuth oxide phases with low dielectric constant into the boundaries of the ferroelectric/piezoelectric grains.
Fabrication and Electrical Properties of Mn-Doped KNbO3 Ceramics Synthesized from KHCO3 as a Starting Material
Authors: Nagata Hajime , Yawata Nobutaka , Sato Shigeki , Takenaka Tadashi
Published: September 2012

Potassium niobate-based ceramics with 0.1 wt % MnCO3, K(1+x)NbO3+MnCO3 0.1 wt % (KN10000x+Mn, x = 0.0000–0.0010), were fabricated using KHCO3 powder as a starting material. The KN10000x+Mn ceramics were basically fabricated using a conventional ceramic fabrication process and MnCO3 powders were added at the milling stage after the calcination. High density ratios above 95% were prepared for the wide compositional range of excess K amount for KN10000x+Mn ceramics. From these results, Mn ions are thought to act as a sintering aid for KN ceramics. Mn-doped KN10000x ceramics also showed high resisitivities of approximately 1012 Ω cm for the wide variety of x (10000x=0–9). Moreover, the electromechanical coupling factors k
33 for KN10000x+Mn had constant values of higher than 0.50.
Field Effect on Displacive First-Order Transition in Relaxor Ferroelectrics
Authors: Matsushita Eiko , Sugiyama Kouichi , Nozawa Kazuki
Published: September 2012

As preliminaries of a microscopic theory for displacive phase transition, the first-order transition is investigated within a phenomenological study that provides a good explanation of experimental results on the electric field dependence and pressure effect in relaxor ferroelectrics. The morphotropic phase boundary (MPB) region in mixed perovskite oxides is described in the same phase diagram corresponding to individual perovskite oxides with successive phase transitions. On the basis of the calculated field-dependent phase transitions, the origin of the MPB is examined in comparison with that in the case of BaTiO3 with the first-order displacive transition.
Ferroelectric and Piezoelectric Properties of 0.72Pb(Zr0.47Ti0.53)O3–0.28Pb[(Zn0.45Ni0.55)1/3Nb2/3]O3Thick Films for Energy Harvesting Device Application
Authors: Jeong Young Hun , Kim Kyoung Bum , Lee Young-Jin , Cho Jeong-Ho , Kim Byoung-Ik , Paik Jong-Hoo , Nahm Sahn
Published: September 2012

The Ferroelectric and piezoelectric properties of 0.72Pb(Zr0.47Ti0.53)O3–0.28Pb[(Zn0.45Ni0.55)1/3Nb2/3]O3(PZT–PZNN) piezoelectric thick films were investigated for application to energy harvesting devices. The PZT–PZNN thick films were fabricated by a conventional tape casting process. The sintered PZT–PZNN thick film was highly dense and flat when the annealed temperature was 1100 °C. It exhibited substantial ferroelectric and piezoelectric properties ofPr= 20.6 µC/cm2,d33= 370 pC/N, εT33/ε0= 1185, andkp= 0.44. Moreover, itsd33·g33, which can characterize high energy density material, is as large as approximately 13050×10-15m2/N. Therefore, the PZT–PZNN thick film can be a potential piezoelectric material for application to energy harvesting devices.
Structural and Multiferroic Properties of Chemical-Solution-Deposited (Bi0.95La0.05)(Fe0.97Cr0.03)O3/NiFe2O4 Double-Layered Thin Film
Authors: Raghavan Chinnambedu Murugesan , Kim Hae Jin , Kim Jin Won , Kim Sang Su , Do Dalhyun , Lee Myang Hwan , Song Tae Kwon , Kim Myong Ho
Published: September 2012

The structural, electrical, and multiferroic properties of the double-layered (Bi0.95La0.05)(Fe0.97Cr0.03)O3/NiFe2O4 thin film deposited on a Pt(111)/Ti/SiO2/Si(100) substrate by a chemical solution deposition method are reported. The formation of the perovskite-based distorted rhombohedral and spinel phases was confirmed by X-ray diffraction analysis and Raman spectroscopy. The surface morphology and film thickness were analyzed by field emission scanning electron microscopy. The low leakage current density (5.83×10-7 A/cm2 at 100 kV/cm) was measured from the double-layered thin film. Potential multiferroic properties, such as a well-saturated ferroelectric hysteresis loop with large 2 P
r (61 µC/cm2) and 2 E
c (652 kV/cm) (at an applied electric field of 952 kV/cm), and a ferromagnetic hysteresis loop having 2 M
r (18.6 emu/cm3) with 2 H
c (0.943 kOe) (at an applied magnetic field of 20 kOe), were observed from the double-layered thin film.
Piezoelectric Properties of Li-Doped (K0.48Na0.52)NbO3 Ceramics Synthesized Using Hydrothermally-Derived KNbO3 and NaNbO3 Fine Powders
Authors: Maeda Takafumi , Hemsel Tobias , Morita Takeshi
Published: September 2012

[Li
x
(Na0.52K0.48)1-x
]NbO3 (0 ≤x ≤0.091) ceramics were synthesized using hydrothermal powders and the lithium doping content was controlled to optimize their piezoelectric properties. The raw KNbO3 and NaNbO3 powders were obtained separately by a hydrothermal method and LiNbO3 powders were prepared by milling a commercial LiNbO3 single crystal. These powders were mixed with ethanol at a molar ratio LiNbO3: (Na0.52K0.48)NbO3= x : 1-x. The synthesized powders were sintered at 1060–1120 °C for 2 h. We succeeded in obtaining highly dense [Li
x
(Na0.52K0.48)1-x
]NbO3 ceramics using hydrothermal powder. The X-ray diffraction patterns revealed that the crystal phase changed from orthorhombic to tetragonal at around x = 0.06. At this morphotropic phase boundary (MPB), the c/a ratio changed from 1.016 to 1.024 and the highest piezoelectric constant was obtained with the chemical component of [Li0.065(K0.48Na0.52)0.935]NbO3. The obtained piezoelectric properties were as follows: k
33 = 0.51, ε33
T/ε0 = 836, c
33
E = 46 GPa, d
33 = 203 pC/N, and T
c = 482 °C.
Research on Electrical Characteristics of Dielectric Barrier Discharge and Dielectric Barrier Corona Discharge
Authors: Sun Yanzhou , Zeng Mi , Cui Zhiyong
Published: September 2012

The dielectric barrier corona discharge (DBCD) in a wire-cylinder configuration and the dielectric barrier discharge (DBD) in a coaxial cylinder configuration are studied. The discharge current in DBD has higher pulse amplitude than in DBCD. The dissipated power and the gas gap voltage are calculated by analyzing the measured Lissajous figure. DBCD has lower gas gap breakdown voltage. The average electric field is about 10–20 kV/cm in gas gap during DBCD, and is 30–40 kV/cm during DBD. In the positive half cycle the DBCD appears as continuous discharge current mode and in negative half cycle it appears as Trichel pulse mode. Under some conditions DBCD can show homogeneous diffuse discharges mode.
Effect of Rain Drops on Corona Discharge in Alternating Current Transmission Lines with a Corona Cage
Authors: Chen Lan , Bian Xingming , Wang Lingming , Guan Zhicheng
Published: September 2012

The dielectric distributed around the surface of electrodes has a significant effect on the corona discharge. Corona discharge in power transmission lines in fine weather is different from that in rainy days as the surface condition is greatly changed. The surface of conductors is filled with the drops of rainwater; hence, the electric field around the conductors will be distorted. The use of a corona cage is an effective and economical means for duplicating corona progress in power transmission lines with lower voltage on the conductor in the cage. The practical conductor was utilized in this experiment under both fine and rainy conditions. The process of corona discharge was recorded and investigated. It was found that the corona discharge turned to be much more intense when rain drops were enlarged and more compressed around the conductor. The corona inception voltage, which is an important parameter of corona discharge, was also gained using an ultraviolet imager (UV imager). The corona inception voltage under the rainy condition was about 25% lower than that under the fine condition. The results of the comparison of audible noise and radio interference were analyzed.
Conductivity Variation Observed by Polarization and Depolarization Current Measurements of High-Voltage Equipment Insulation System
Authors: Jamail Nor Akmal Mohd , Piah Mohamed Afendi Mohamed , Muhamad Nor Asiah
Published: September 2012

Nondestructive and time domain dielectric measurement techniques such as polarization and depolarization current (PDC) measurements have recently been widely used as a potential tool for determining high-voltage insulation conditions by analyzing the insulation conductivity. The variation in the conductivity of an insulator was found to depend on several parameters: the difference between the polarization and depolarization currents, geometric capacitance, and the relative permittivity of the insulation material. In this paper the conductivities of different types of oil-paper insulation material are presented. The insulation conductivities of several types of electrical apparatus were simulated using MATLAB. Conductivity insulation was found to be high at high polarizations and at the lowest depolarization current. It was also found to increase with increasing relative permittivity as well as with decreasing geometric capacitance of the insulating material.
Color Stability of Blue Phosphorescent Organic Light-Emitting Diodes with Undoped Layer in Emissive Layer
Authors: Lee Chan-Jae , Maeng Chang-Jun , Ahn Jin-Ho , Lee Jeong-No , Kwak Min-Gi
Published: September 2012

We analyzed the color stability of blue phosphorescent organic light emitting diodes (phOLEDs) as device operation. In the blue phOLEDs, color stability is one of the most important factors during operation for commercialization. Therefore, we measure the electroluminance spectrum in the as-dep. state and after the lifetime test. The reference device with the whole emission layer doped shows a severe color change during the device operation owing to the degradation of the hole blocking property of the electron transport layer (ETL) and a shift of the emission region to ETL. After the lifetime test, the green peak increased and the width of the peak increased. The adoption of an undoped layer near the interface of ETL/emitting layer (EML) impeded the degradation of ETL thus so these devices show a stable color and a long lifetime. On the other hand, in the case of the undoped layer, the interface of hole transport layer (HTL)/EML shows an increased efficiency owing to the blocking of the movement of triplet energy from the doped layer to HTL, but does a color change that is similar to that of the reference device.
Solution-Processed White Light-Emitting Diode Utilizing Hybrid Polymer and Red–Green–Blue Quantum Dots
Authors: Kwon Byoung Wook , Son Dong Ick , Park Dong-Hee , Choi Heon-Jin , Choi Won-Kook
Published: September 2012

A hybrid polymer-quantum dots (QDs) white light-emitting diode (WLEDs) device with a multi-layer structure by all solution processing is simply fabricated by using a spin coating technique. From transmission electron microscopy (TEM) study, red–green–blue (RGB) CdSe/ZnS QDs are mainly distributed along with the circumference of poly(N-vinylcarbazole) (PVK) surfaces, resulting in core–shell hybrid polymer-QDs of [RGB CdSe/ZnS QDs]/PVK. The Al/Cs2CO3/[RGB CdSe/ZnS QDs+PVK]/poly[(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine)] (poly-TPD)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/indium–tin-oxide (ITO)/glass WLEDs shows electroluminescence (EL) centered at around 474, 544, and 629 nm with CIE coordinates, (0.44,0.32) at the forward bias +11 V, which clearly reveals that CdSe/ZnS QDs existing at the interface between PVK plays as a recombination center of exciton.
Carrier Transport Mechanism at the Interface between Metals and p-Type III–Nitrides Having Different Surface Electronic Structures
Authors: Jang Seon-Ho , Jang Ja-Soon
Published: September 2012

We have investigated the carrier transport mechanism for nonalloyed Ni/Au ohmic contacts to p-In0.15Ga0.85N/GaN superlattices (SLs) and Mg delta (δ)-doped GaN using current–voltage–temperature (I–V–T) and specific contact resistance–temperature (Rsc–T) data. The p-SL and Mg δ-doped GaN contacts show a linearI–Vbehavior, indicating that the Mg δ doping in the GaN matrix as well as p-SL is very effective in improving the electrical properties of p-ohmic contacts. From theRsc–TandI–V–Tmeasurements, the p-SL and Mg delta-doped GaN contacts show slight temperature-dependence characteristics at the temperatures of ≥293 K. These different behaviors can be described in terms of a reduced energy band-bending, an increased hole carrier density, and a reduced Schottky barrier height.
Hotspot Location Shift in the High-Power Phosphor-Converted White Light-Emitting Diode Packages
Authors: Hu Run , Luo Xiaobing , Zheng Huai
Published: September 2012

Thermal management of high-power light-emitting diodes (LEDs) plays an important role in determining their optical properties, reliability, and lifetime. In this paper, we present a method to study the temperature field of phosphor-converted LED packages by combining the Monte Carlo optical simulation and finite element simulation together. The temperature field, including the heat generation in both LED chip and phosphor layer, are presented and analyzed. It was found that temperature increased with the increase in phosphor concentration and the hotspot location in remote phosphor-coating packages shifted with the changes in phosphor concentration, while there was no shift in direct phosphor-coating packages. It was concluded that the hotspot location in the high-power phosphor-converted white LED packages depended on phosphor concentrations as well as packaging methods.
Thermal Conductivity of Al2O3/Poly(vinyl butyral) Composites
Authors: Ju Han Sae , Im Dong Hyeok , Park Sung Dae , Lee Hyeung Gyu , Kim Eung Soo
Published: September 2012

In this study, the effects of orientation of Al2O3 on the thermal conductivity of poly(vinyl butyral) (PVB) composites filled with platelet-shaped Al2O3 ceramics were investigated as function of Al2O3 content. On increasing the ceramic content, it was observed that the thermal conductivity of the composites increased because of the higher thermal conductivity of Al2O3 compared with that of the PVB. The thermal conductivity of the composites was affected by the orientation of ceramics. The measured thermal conductivity of the composites was compared with the effective thermal conductivity calculated by various theoretical models. The thermal diffusivity and specific heat capacity of the composites were also discussed.
Nodal recovery, dual pathway physiology, and concealed conduction determine complex AV dynamics in human atrial tachyarrhythmias
Authors: Masè Michela , Glass Leon , Disertori Marcello , Ravelli Flavia
Published: September 2012

The genesis of complex ventricular rhythms during atrial tachyarrhythmias in humans is not fully understood. To clarify the dynamics of atrioventricular (AV) conduction in response to a regular high-rate atrial activation, 29 episodes of spontaneous or pacing-induced atrial flutter (AFL), covering a wide range of atrial rates (cycle lengths from 145 to 270 ms), were analyzed in 10 patients. AV patterns were identified by applying firing sequence and surrogate data analysis to atrial and ventricular activation series, whereas modular simulation with a difference-equation AV node model was used to correlate the patterns with specific nodal properties. AV node response at high atrial rate was characterized by 1) AV patterns of decreasing conduction ratios at the shortening of atrial cycle length (from 236.3 ± 32.4 to 172.6 ± 17.8 ms) according to a Farey sequence ordering (conduction ratio from 0.34 ± 0.12 to 0.23 ± 0.06; P < 0.01); 2) the appearance of high-order alternating Wenckebach rhythms, such as 6:2, 10:2, and 12:2, associated with ventricular interval oscillations of large amplitude (407.7 ± 150.4 ms); and 3) the deterioration of pattern stability at advanced levels of block, with the percentage of stable patterns decreasing from 64.3 ± 35.2% to 28.3 ± 34.5% ( P < 0.01). Simulations suggested these patterns to originate from the combined effect of nodal recovery, dual pathway physiology, and concealed conduction. These results indicate that intrinsic nodal properties may account for the wide spectrum of AV block patterns occurring during regular atrial tachyarrhythmias. The characterization of AV nodal function during different AFL forms constitutes an intermediate step toward the understanding of complex ventricular rhythms during atrial fibrillation.
Histamine induces activation of protein kinase D that mediates tissue factor expression and activity in human aortic smooth muscle cells
Authors: Hao Feng , Wu Daniel Dongwei , Xu Xuemin , Cui Mei-Zhen
Published: September 2012

Histamine, an inflammatory mediator, has been shown to influence the pathogenesis of vascular wall cells. However, the molecular basis of its influence is not well understood. Our data reveal that histamine markedly induces protein kinase D (PKD) activation in human aortic smooth muscle cells. PKD belongs to a family of serine/threonine protein kinases, and its function in vascular disease is largely unknown. Our data show that histamine-induced PKD phosphorylation is dependent on the activation of histamine receptor 1 and protein kinase C (PKC). To determine the role of PKD in the histamine pathway, we employed a small-interfering RNA approach to downregulate PKD expression and found that PKD1 and PKD2 are key mediators for expression of tissue factor (TF), which is the key initiator of blood coagulation and is important for thrombosis. Our results show that PKD2 predominantly mediates histamine-induced TF expression via the p38 mitogen-activated protein kinase (MAPK) pathway, whereas PKD1 mediates histamine-induced TF expression through a p38 MAPK-independent pathway. We demonstrate that histamine induces TF expression via the PKC-dependent PKD activation. Our data provide the first evidence that PKD is a new component in histamine signaling in live cells and that PKD has a novel function in the histamine signaling pathway leading to gene expression, as evidenced by TF expression. Importantly, our data reveal a regulatory link from histamine to PKD and TF, providing new insights into the mechanisms of coagulation and the development of atherothrombosis.
Hypoxia-induced endothelial CX3CL1 triggers lung smooth muscle cell phenotypic switching and proliferative expansion
Authors: Zhang Jianliang , Hu Hanbo , Palma Nadia L. , Harrison Jeffrey K. , Mubarak Kamal K. , Carrie Robin D. , Alnuaimat Hassan , Shen Xiaoqiang , Luo Defang , Patel Jawaharlal M.
Published: September 2012

Distal arterioles with limited smooth muscles help maintain the high blood flow and low pressure in the lung circulation. Chronic hypoxia induces lung distal vessel muscularization. However, the molecular events that trigger alveolar hypoxia-induced peripheral endothelium modulation of vessel wall smooth muscle cell (SMC) proliferation and filling of nonmuscular areas are unclear. Here, we investigated the role of CX3CL1/CX3CR1 system in endothelial-SMC cross talk in response to hypoxia. Human lung microvascular endothelial cells responded to alveolar oxygen deficiency by overproduction of the chemokine CX3CL1. The CX3CL1 receptor CX3CR1 is expressed by SMCs that are adjacent to the distal endothelium. Hypoxic release of endothelial CX3CL1 induced SMC phenotypic switching from the contractile to the proliferative state. Inhibition of CX3CR1 prevented CX3CL1 stimulation of SMC proliferation and monolayer expansion. Furthermore, CX3CR1 deficiency attenuated spiral muscle expansion, distal vessel muscularization, and pressure elevation in response to hypoxia. Our findings indicate that the capillary endothelium relies on the CX3CL1-CX3CR1 axis to sense alveolar hypoxia and promote peripheral vessel muscularization. These results have clinical significance in the development of novel therapeutics that target mechanisms of distal arterial remodeling associated with pulmonary hypertension induced by oxygen deficiency that is present in people living at high altitudes and patients with obstructive lung diseases.
Estrogen effects on human airway smooth muscle involve cAMP and protein kinase A
Authors: Townsend Elizabeth A. , Sathish Venkatachalem , Thompson Michael A. , Pabelick Christina M. , Prakash Y. S.
Published: September 2012

Clinically observed differences in airway reactivity and asthma exacerbations in women at different life stages suggest a role for sex steroids in modulating airway function although their targets and mechanisms of action are still being explored. We have previously shown that clinically relevant concentrations of exogenous estrogen acutely decrease intracellular calcium ([Ca2+]i) in human airway smooth muscle (ASM), thereby facilitating bronchodilation. In this study, we hypothesized that estrogens modulate cyclic nucleotide regulation, resulting in decreased [Ca2+]iin human ASM. In Fura-2-loaded human ASM cells, 1 nM 17β-estradiol (E2) potentiated the inhibitory effect of the β-adrenoceptor (β-AR) agonist isoproterenol (ISO; 100 nM) on histamine-mediated Ca2+entry. Inhibition of protein kinase A (PKA) activity (KT5720; 100 nM) attenuated E2effects on [Ca2+]i. Acute treatment with E2increased cAMP levels in ASM cells comparable to that of ISO (100 pM). In acetylcholine-contracted airways from female guinea pigs or female humans, E2potentiated ISO-induced relaxation. These novel data suggest that, in human ASM, physiologically relevant concentrations of estrogens act via estrogen receptors (ERs) and the cAMP pathway to nongenomically reduce [Ca2+]i, thus promoting bronchodilation. Activation of ERs may be a novel adjunct therapeutic avenue in reactive airway diseases in combination with established cAMP-activating therapies such as β2-agonists.
Rho-kinase inhibition attenuates airway responsiveness, inflammation, matrix remodeling, and oxidative stress activation induced by chronic inflammation
Authors: Possa Samantha Souza , Charafeddine Homar Toledo , Righetti Renato Fraga , da Silva Patricia Angeli , Almeida-Reis Rafael , Saraiva-Romanholo Beatriz Mangueira , Perini Adenir , Prado Carla Máximo , Leick-Maldonado Edna Aparecida , Martins Milton A. , Tibério Iolanda de Fátima Lopes Calvo
Published: September 2012

Several studies have demonstrated the importance of Rho-kinase in the modulation of smooth muscle contraction, airway hyperresponsiveness, and inflammation. However, the effects of repeated treatment with a specific inhibitor of this pathway have not been previously investigated. We evaluated the effects of repeated treatment with Y-27632, a highly selective Rho-kinase inhibitor, on airway hyperresponsiveness, oxidative stress activation, extracellular matrix remodeling, eosinophilic inflammation, and cytokine expression in an animal model of chronic airway inflammation. Guinea pigs were subjected to seven ovalbumin or saline exposures. The treatment with Y-27632 (1 mM) started at the fifth inhalation. Seventy-two hours after the seventh inhalation, the animals′ pulmonary mechanics were evaluated, and exhaled nitric oxide (ENO) was collected. The lungs were removed, and histological analysis was performed using morphometry. Treatment with Y-27632 in sensitized animals reduced ENO concentrations, maximal responses of resistance, elastance of the respiratory system, eosinophil counts, collagen and elastic fiber contents, the numbers of cells positive for IL-2, IL-4, IL-5, IL-13, inducible nitric oxide synthase, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, transforming growth factor-β, NF-κB, IFN-γ, and 8-iso-prostaglandin F2α contents compared with the untreated group ( P < 0.05). We observed positive correlations among the functional responses and inflammation, remodeling, and oxidative stress pathway activation markers evaluated. In conclusion, Rho-kinase pathway activation contributes to the potentiation of the hyperresponsiveness, inflammation, the extracellular matrix remodeling process, and oxidative stress activation. These results suggest that Rho-kinase inhibitors represent potential pharmacological tools for the control of asthma.
New methods for monitoring dynamic airway tissue oxygenation and perfusion in experimental and clinical transplantation
Authors: Khan Mohammad A. , Dhillon Gundeep , Jiang Xinguo , Lin Yu-Chun , Nicolls Mark R.
Published: September 2012

A dual circulation, supplied by bronchial and pulmonary artery-derived vessels, normally perfuses the airways from the trachea to the terminal bronchioles. This vascular system has been highly conserved through mammalian evolution and is disrupted at the time of lung transplantation. In most transplant centers, this circulation is not restored. The Papworth Hospital Autopsy study has revealed that an additional attrition of periairway vessels is associated with the development of chronic rejection, otherwise known as the bronchiolitis obliterans syndrome (BOS). Experimental studies subsequently demonstrated that airway vessels are subject to alloimmune injury and that the loss of a functional microvascular system identifies allografts that cannot be rescued with immunosuppressive therapy. Therefore, surgical and medical strategies, which preserve the functionality of the existent vasculature in lung transplant patients, may conceivably limit the incidence of BOS. Given these unique anatomic and physiological considerations, there is an emerging rationale to better understand the perfusion and oxygenation status of airways in transplanted lungs. This article describes novel methodologies, some newly developed by our group, for assessing airway tissue oxygenation and perfusion in experimental and clinical transplantation.
Transcription of the Tumor Suppressor Genesp53andRBin Lymphocytes from Patients with Chronic Kidney Disease: Evidence of Molecular Senescence?
Authors: Kordinas Vasileios , Nicolaou Chryssoula , Tsirpanlis George , Ioannidis Anastasios , Bersimis Sotiris , Sabanis Nikos , Fragou Eleni , Tsiolaki Konstantina , Chatzipanagiotou Stylianos
Published: September 2012

Patients suffering from renal failure exhibit an impaired immune system function. We wanted to investigate the transcription of the tumor suppressor genesp53andRBto record, if these cells could be stimulatedin vitroin order to divide, after the addition of antigenic and inflammatory factors. This expression was measured by real-time PCR in peripheral blood mononuclear cells (PBMCs) from three different groups: ten healthy individuals, ten patients with chronic kidney disease (CKD), and ten dialysis patients with end stage renal disease (ESRD). The transcription rate of these genes was also measured after the cultivation of PBMCs under four different conditions: just with the culture medium, with lipopolysaccharide (LPS), with C-reactive protein (CRP), and with lipoxin A4(LXA4)-LPS. Our results show that in most cases after the cultivation with additives, the transcription levels were higher in dialysis patients compared to those of the other two groups. Our findings serve as indications of cellular senescence on a molecular level, while it seems that these cells are less easily stimulatedin vitroin order to duplicate.
EGFR: A Master Piece in G1/S Phase Transition of Liver Regeneration
Authors: Collin de l'Hortet Alexandra , Gilgenkrantz Hélène , Guidotti Jacques-Emmanuel
Published: September 2012

Unraveling the molecular clues of liver proliferation has become conceivable thanks to the model of two-third hepatectomy. The synchronicity and the well-scheduled aspect of this process allow scientists to slowly decipher this mystery. During this phenomenon, quiescent hepatocytes of the remnant lobes are able to reenter into the cell cycle initiating the G1-S progression synchronously before completing the cell cycle. The major role played by this step of the cell cycle has been emphasized by loss-of-function studies showing a delay or a lack of coordination in the hepatocytes G1-S progression. Two growth factor receptors, c-Met and EGFR, tightly drive this transition. Due to the level of complexity surrounding EGFR signaling, involving numerous ligands, highly controlled regulations and multiple downstream pathways, we chose to focus on the EGFR pathway for this paper. We will first describe the EGFR pathway in its integrity and then address its essential role in the G1/S phase transition for hepatocyte proliferation. Recently, other levels of control have been discovered to monitor this pathway, which will lead us to discuss regulations of the EGFR pathway and highlight the potential effect of misregulations in pathologies.
Chemotherapeutic Sensitivity of Testicular Germ Cell Tumors Under Hypoxic Conditions Is Negatively Regulated by SENP1-Controlled Sumoylation of OCT4
Authors: Wu Yu-Chih , Ling Thai-Yen , Lu Shing-Hwa , Kuo Hung-Chih , Ho Hong-Nerng , Yeh Shauh-Der , Shen Chia-Ning , Huang Yen-Hua
Published: September 2012

Testicular germ cell tumors (TGCT) generally respond well to chemotherapy, but tumors that express low levels of the transcription factor OCT4 are associated with chemoresistance and poor prognosis. Hypoxia is known to induce drug resistance in TGCTs; however, the mechanistic basis for reduced expression of OCT4 and drug resistance is unclear. Here we show that hypoxia reduces OCT4 levels and increases the resistance of embryonal carcinoma (EC) cells to cisplatin and bleomycin. Furthermore, we show that the loss of OCT4 expression under hypoxia can be triggered by sumoylation, which was regulated by SUMO1 and the SUMO1 peptidase SENP1. Under hypoxic conditions, overexpression of SUMO1gg (the active form of SUMO1) not only increased the level of sumoylated OCT4 (Su-OCT4), but also decreased the stability of OCT4 protein. In addition, overexpression of SENP1 reduced the Su-OCT4 level induced by SUMO1gg overexpression, thereby maintaining OCT4 levels and enhancing chemosensitivity. Mechanistic investigations revealed that OCT4 sumoylation occurred at K123, as overexpression of an OCT4-K123R mutant effectively reduced the level of Su-OCT4 under hypoxic conditions. Taken together, our results showed that hypoxia reduces OCT4 expression levels in ECs to increase drug resistance and that these effects could be countered to ablate the suppressive effects of hypoxia on chemosensitivity. Our findings also highlight SENP1 as a potential therapeutic target for drug resistant TGCTs. Cancer Res; 72(19); 4963–73. ©2012 AACR.
Anti–IL-20 Monoclonal Antibody Alleviates Inflammation in Oral Cancer and Suppresses Tumor Growth
Authors: Hsu Yu-Hsiang , Wei Chi-Chen , Shieh Dar-Bin , Chan Chien-Hui , Chang Ming-Shi
Published: September 2012

Interleukin-20 (IL-20) is a proinflammatory cytokine involved in rheumatoid arthritis, atherosclerosis, and osteoporosis. However, little is known about the role of IL-20 in oral cancer. We explored the function of IL-20 in the tumor progression of oral cancer. IL-20 expression levels in tumorous and nontumorous oral tissue specimens from 40 patients with four different stages oral cancer were analyzed with immunohistochemistry (IHC) staining and quantitative real-time PCR (qRT-PCR). Expression of IL-20 and its receptor subunits was higher in clinical oral tumor tissue than in nontumorous oral tissue. The role of IL-20 was examined in two oral cancer cell lines (OC-3 and OEC-M1). In vitro, IL-20 promoted TNF-α, IL-1β, MCP-1, CCR4, and CXCR4 and increased proliferation, migration, reactive oxygen species (ROS) production, and colony formation of oral cancer cells via activated STAT3 and AKT/JNK/ERK signals. To evaluate the therapeutic potential of anti–IL-20 monoclonal antibody 7E for treating oral cancer, an ex vivo tumor growth model was used. In vivo, 7E reduced tumor growth and inflammation in oral cancer cells. In conclusion, IL-20 promoted oral tumor growth, migration, and tumor-associated inflammation. Therefore, IL-20 may be a novel target for treating oral cancer, and anti–IL-20 monoclonal antibody 7E may be a feasible therapeutic. Mol Cancer Res; 10(11); 1430–9. ©2012 AACR.
Impact of National Income and Inequality on Sugar and Caries Relationship
Authors: Masood M. , Masood Y. , Newton T.
Published: September 2012

Objective: The aim of this study was to examine the impact that national income and income inequality in high and low income countries have on the relationship between dental caries and sugar consumption. Methods: An ecological study design was used in this study of 73 countries. The mean decayed, missing, or filled permanent teeth (DMFT) for 12-year-old children were obtained from the WHO Oral Health Country/Area Profile Programme. United Nations Food and Agricultural Organization data were used for per capita sugar consumption. Gross national incomes per capita based on purchasing power parity and the Gini coefficient were obtained from World Bank data. Bivariate and multivariate linear regression analysis was performed to estimate the associations between mean DMFT and per capita sugar consumption in different income and income inequality countries. Results: Bivariate and multivariate regression analysis showed that countries with a high national income and low income inequality have a strong negative association between sugar consumption and caries (B = –2.80, R2 = 0.17), whereas countries with a low income and high income inequality have a strong positive relationship between DMFT and per capita sugar consumption (B = –0.89, R2 = 0.20). Conclusion: The relationship between per capita consumption of sugar and dental caries is modified by the absolute level of income of the country, but not by the level of income inequality within a country.
The Effect of Daily Fluoride Mouth Rinsing on Enamel Erosive/Abrasive Wear in situ
Authors: Stenhagen K.R. , Hove L.H. , Holme B. , Tveit A.B.
Published: September 2012

It is not known whether application of fluoride agents on enamel results in lasting resistance to erosive/abrasive wear. We investigated if one daily mouth rinse with sodium fluoride (NaF), stannous fluoride (SnF2) or titanium tetrafluoride (TiF4) solutions protected enamel against erosive/abrasive wear in situ (a paired, randomised and blind study). Sixteen molars were cut into 4 specimens, each with one amalgam filling (measurement reference surface). Two teeth (2 × 4 specimens) were mounted bilaterally (buccal aspects) on acrylic mandibular appliances and worn for 9 days by 8 volunteers. Every morning, the specimens were brushed manually with water (30 s) extra-orally. Then fluoride solutions (0.4% SnF2 pH 2.5; 0.15% TiF4 pH 2.1; 0.2% NaF pH 6.5, all 0.05 m F) were applied (2 min). Three of the specimens from each tooth got different treatment, and the fourth served as control. At midday, the specimens were etched for 2 min in 300 ml fresh 0.01 m hydrochloric acid and rinsed in tap water. This etch procedure was repeated in the afternoon. Topographic measurements were performed by a white-light interferometer. Mean surface loss (±SD) for 16 teeth after 9 days was: SnF2 1.8 ± 1.9 µm, TiF4 3.1 ± 4.8 µm, NaF 26.3 ± 4.7 µm, control 32.3 ± 4.4 µm. Daily rinse with SnF2, TiF4 and NaF resulted in 94, 90 and 18% reduction in enamel erosive/abrasive wear, respectively, compared with control (p < 0.05). The superior protective effect of daily rinse with either stannous or titanium tetrafluoride solutions on erosive/abrasive enamel wear is promising.
TLR 2 Induces Vascular Smooth Muscle Cell Migration Through cAMP Response Element−Binding Protein−Mediated Interleukin-6 Production
Authors: Lee Guan-Lin , Chang Ya-Wei , Wu Jing-Yiing , Wu Meng-Ling , Wu Kenneth K. , Yet Shaw-Fang , Kuo Cheng-Chin
Published: September 2012

Objective—

Migration of vascular smooth muscle cells (VSMCs) from the media into intima contributes to the development of atherosclerosis. Gene deletion experiments implicate a role for toll-like receptor 2 (TLR2) in atherogenesis. However, the underlying mechanisms remain unclear. We postulate that TLR2 promotes VSMC migration by enhancing interleukin (IL)-6 production.

Methods and Results—

Migration assays revealed that TLR2 agonists promoted VSMC migration but not cell proliferation or viability. TLR2 deficiency or inhibition of TLR2 signaling with anti-TLR2 antibody suppressed TLR2 agonist–induced VSMC migration and IL-6 production, which was mediated via p38 mitogen-associated protein kinase and extracellular signal–regulated kinase 1/2 signaling pathways. Neutralizing anti−IL-6 antibodies impaired TLR2-mediated VSMC migration and formation of filamentous actin fiber and lamellipodia. Blockade of p38 mitogen-associated protein kinase or extracellular signal–regulated kinase 1/2 activation inhibited TLR2 agonist pam3CSK4-induced phosphorylation of cAMP response element−binding protein, which regulates IL-6 promoter activity through the cAMP response element site. Moreover, cAMP response element−binding protein small interfering RNA inhibited pam3CSK4-induced IL-6 production and VSMC migration. Additionally, Rac1 small interfering RNA inhibited pam3CSK4-induced VSMC migration but not IL-6 production.

Conclusion—

Our results suggest that on ligand binding, TLR2 activates p38 mitogen-associated protein kinase and extracellular signal–regulated kinase 1/2 signaling in VSMCs. These signaling pathways act in concert to activate cAMP response element−binding protein and subsequent IL-6 production, which in turn promotes VSMC migration via Rac1-mediated actin cytoskeletal reorganization.
Analysis of Procedural Effects of Percutaneous Edge-to-Edge Mitral Valve Repair by 2D and 3D Echocardiography
Authors: Altiok Ertunc , Hamada Sandra , Brehmer Kathrin , Kuhr Kathrin , Reith Sebastian , Becker Michael , Schröder Jörg , Almalla Mohammad , Lehmacher Walter , Marx Nikolaus , Hoffmann Rainer
Published: September 2012

Background—

Analysis of procedural effects in patients undergoing percutaneous mitral valve repair (PMVR) using the edge-to-edge technique is complex, and common methods to define mitral regurgitation severity based on 2-dimensional (2D) echocardiography are not validated for postprocedural double-orifice mitral valve. This study used 3D transesophageal echocardiography (TEE) to determine the functional and morphological effects of PMVR.

Methods and Results—

In 39 high-risk surgical patients with moderate to severe functional mitral valve regurgitation, 3D TEE with and without color Doppler as well as 2D transthoracic and TEE was performed before and after PMVR (MitraClip device). Mitral valve regurgitant volume by color Doppler 3D TEE was determined as the product of vena contracta areas defined by direct planimetry and velocity time integral using continuous-wave Doppler. Regurgitant volume was reduced from 84.1±38.3 mL preintervention to 35.6±25.6 mL postintervention. Patients in whom vena contracta area could be reduced >50% had a smaller preprocedural mitral annulus area compared with patients with ≤50% reduction (11.9±3.9 versus 16.1±8.5 cm
2
, respectively;

P

=0.036) and tended to have a smaller mitral annulus circumference (13.0±2.0 versus 14.8±4.1 cm, respectively;

P

=0.112). At 6 months follow-up, left atrial and left ventricular end-diastolic volumes were significantly more reduced in patients in whom regurgitant vena contracta area was reduced by >50% compared with those with less reduction (−11.4±5.2 versus −4.8±7.7%;

P

=0.005, and −11.0±7.2 versus −4.5±9.3%;

P

=0.028). The maximum diastolic mitral valve area decreased from 6.0±2.0 to 2.9±0.9 cm
2
(

P

<0.0001).

Conclusions—

Three dimensional TEE demonstrates significant reduction of regurgitant volume after PMVR. The unique visualization of the mitral valve by 3D TEE allows improved understanding of the morphological and functional changes induced by PMVR.
Cardiac Allograft Function During the First Year after Transplantation in Rejection-Free Children and Young Adults
Authors: Lunze Fatima I. , Colan Steven D. , Gauvreau Kimberlee , Chen Ming Hui , Perez-Atayde Antonio R. , Blume Elizabeth D. , Singh Tajinder P.
Published: September 2012

Background—

Allograft dysfunction is a common finding early after heart transplant (HT). We sought to assess the recovery of left (LV) and right ventricular (RV) function during the first year after HT in children and young adults using pulsed-wave tissue Doppler imaging.

Methods and Results—

We analyzed serially performed echocardiography in 44 pediatric HT recipients (median age: 7.3 years at HT) who remained rejection-free during the first year post-transplant. Age-based normative values for systolic (
S
′), early-diastolic (
E
′), and late-diastolic (
A
′) velocities obtained using pulsed-wave tissue Doppler imaging in 380 healthy children were used to transform patient data into
z
scores. Pulsed-wave tissue Doppler imaging studies ≤10 days post-HT demonstrated biventricular systolic and diastolic dysfunction with most prominent impairment in RV systolic function (
S
′
z
score −2.7±0.8), RV early-diastolic filling (
E
′
z
score −2.3±1.1), and LV early-diastolic filling (
E
′
z
score −2.3±1.1). LV systolic function (
S
′
z
score) and late-diastolic filling (
A
′
z
score) improved to normal in 11 to 30 days, LV early-diastolic filling (
E
′
z
score) in 4 to 6 months, and RV early-diastolic filling in 6 to 9 months (
P
<0.001 for all on longitudinal analysis). However, RV systolic function (RV
S
′
z
score −1.2±1.1) remained impaired 1-year post-transplant. Analysis of serial cardiac catheterization studies showed that RV and LV filling pressures were elevated early post-HT and declined gradually during the first year post-transplant.

Conclusions—

Pediatric HT recipients have biventricular dysfunction using pulsed-wave tissue Doppler imaging early after HT with most significant impairment in RV systolic function and RV and LV early-diastolic filling. Although other aspects of LV and RV function normalize in 6 to 9 months, RV systolic function remains abnormal 1 year-post-transplant.
Quality Improvement in Coronary Care: Analysis of Sustainability and Impact on Adjacent Clinical Measures After a Swedish Controlled, Multicenter Quality Improvement Collaborative
Authors: Carlhed Rickard , Bellman Christina , Bojestig Mats , Bojö Leif , Peterson Anette , Lindahl Bertil ,   the Quality Improvement in Coronary Care (QUICC) Study Group
Published: September 2012

Background

Quality Improvement in Coronary Care, a Swedish multicenter, controlled quality‐improvement (
QI
) collaborative, has shown significant improvements in adherence to national guidelines for acute myocardial infarction, as well as improved clinical outcome. The objectives of this report were to describe the sustainability of the improvements after withdrawal of study support and a consolidation period of 3 months and to report whether improvements were disseminated to treatments and diagnostic procedures other than those primarily targeted.

Methods and Results

Multidisciplinary teams from 19 Swedish hospitals were educated in basic
QI
methodologies. Another 19 matched hospitals were included as blinded controls. All evaluations were made on the hospital level, and data were obtained from a national quality registry, Swedish Register of Information and Knowledge About Swedish Heart Intensive Care Admissions (RIKS‐HIA). Sustainability indicators consisted of use of angiotensin‐converting enzyme inhibitors, lipid‐lowering therapy, clopidogrel, low‐molecular weight heparin, and coronary angiography. Dissemination indicators were use of echocardiography, stress tests, and reperfusion therapy; time delays; and length of stay. At the reevaluation period of 6 months, the improvements at the
QI
intervention hospitals were sustained in all indicators but 1 (angiotensin‐converting enzyme inhibitor). Between the 2 measurements, the control group improved significantly in all but 1 indicator (angiotensin‐converting enzyme inhibitor). However, at the second measurement, the absolute adherence rates of the intervention hospitals were still numerically higher in all 5 indicators, and significantly so in 1 (clopidogrel). No significant changes were observed for the dissemination indicators.

Conclusions

The combination of a systematic
QI
collaborative with a national, interactive quality registry might lead to substantial and sustained improvements in the quality of acute myocardial infarction care. However, to achieve disseminated improvements in adjacent clinical measures, those adjacent measures probably should be made explicit before any
QI
intervention.