bluuebunny/crossref_metadata_2025 huggingface dataset:
TOUGHNESS AND REINFORCEMENT OF LINEAR UNSATURATED POLYESTER RESINS BY UNSATURATED HYPERBRANCHED POLYMER AND MECHANISM ANALYSIS
Authors: ZHANG DAOHONG , CHENG XINJIAN , ZHANG AIQING , JIA DEMIN
Published: March 2012

Unsaturated hyperbranched polyester resin (UHPR) prepared by ourselves shows best comprehensive performance in linear unsaturated polyester resin (UP-191) curing system and is considered as a kind of toughness and reinforcement additive. The effect of molecular weight and content of the UHPR on the performance of the UHPR/UP-191 hybrid materials are discussed in detail, and their performance has maximum with the increase of content and molecular weight of UHPR. The impact strength of the hybrid materials containing 10–15 wt% UHPR-2 is 1.86 kJ/m2, and which almost is 1.69 times of UP-191 performance, furthermore, the tensile and flexural strength can also be enhanced about 45.71% and 23.66%, respectively. The fracture surface micrograph of hybrid materials show non micro-phase separation of the UHPR/UP-191 blends which facilitates an enhanced interaction to achieve excellent toughness and strength of the cured systems by SEM and the results also are explained by a novel situ reinforcing and toughening mechanism.
OPTICALLY-OPERATED ELASTOOPTICAL EFFECTS IN POLYMER MATRICES WITH NANOCRYSTALLITES
Authors: KITYK I. V. , ALZAYED N. , RESHAK A. H. , PLUCINSKI K. J. , BERDOWSKI J. , FUKS-JANCZAREK I. , MIEDZINSKI R. , TYLCZYNSKI Z.
Published: March 2012

We have found that the optical treatment by bicolor two laser beams at 1064 and 532 nm, at energy densities 80–120 mJ/cm2 originating from the same 10 ns Nd3+ garnett lasers causes the occurrence of the piezooptical effect in 50–80 nm γ-glicyne polymer nanocomposites at nanoparticle content about 6.5% in weighting unit. We propose to use this effect for optical triggers.
SUPPORT EFFECT ON THE COMPLETE OXIDATION OF ETHYL ACETATE OVER Pt CATALYSTS
Authors: YASUDA KEISUKE , MASUI TOSHIYUKI , IMANAKA NOBUHITO
Published: March 2012

Complete oxidation of ethyl acetate over Pt / CeO 2– ZrO 2– Bi 2 O 3 catalysts prepared by a wet impregnation method was investigated. The Pt / CeO 2– ZrO 2– Bi 2 O 3 catalysts completely oxidized ethyl acetate into CO 2 and H 2 O at low temperatures without the formation of byproducts such as ethanol and acetaldehyde. The ethyl acetate oxidation activity correlates with the reducibility of the support such that a high reducibility gives high activity. By optimization of the composition and the Pt amount, complete oxidation of ethyl acetate was realized at a temperature as low as 190°C on a 10 wt.% Pt / Ce 0.63 Zr 0.17 Bi 0.20 O 1.90 catalyst.
Evaluation and Control of Break-Even Time of Nonvolatile Static Random Access Memory Based on Spin-Transistor Architecture with Spin-Transfer-Torque Magnetic Tunnel Junctions
Authors: Shuto Yusuke , Yamamoto Shuu'ichirou , Sugahara Satoshi
Published: March 2012

The energy performance of a nonvolatile static random access memory (NV-SRAM) cell for power gating applications was quantitatively analyzed for the first time using the performance index of break-even time (BET). The NV-SRAM cell is based on spin-transistor architecture using ordinary metal–oxide–semiconductor field-effect transistors (MOSFETs) and spin-transfer-torque magnetic tunnel junctions (STT-MTJs), whose circuit representation of spin-transistor is referred to as a pseudo-spin-MOSFET (PS-MOSFET). The cell is configured with a standard six-transistor SRAM cell and two PS-MOSFETs. The NV-SRAM cell basically has a short BET of submicroseconds. Although the write (store) operation to the STT-MTJs causes an increase in the BET, it can be successfully reduced by the proposed power-aware bias-control for the PS-MOSFETs.
Dielectric Properties of Y2O3 and Nb2O5 Co-Doped Barium Titanate Ceramics
Authors: Cao Wan Q. , Li Fang L. , Ismail Mukhlis M. , Xiong Gang
Published: March 2012

Conventional solid-state route method was used to prepare barium titanate ceramics doped with Y2O3 and Nb2O5, Ba(Y0.5Nb0.5)
x
Ti(1-x)O3 (x = 0.02, 0.04, 0.06, 0.08). The X-ray diffraction results confirmed that Y3+ and Nb5+ both substitute for Ti4+ at the B-site of ABO3 perovskite type structure, and second phase appeared for x = 0.04 and 0.06. With the increases of Y3+ and Nb5+ concentrations, peak of dielectric constant of Ba(Y0.5Nb0.5)
x
Ti(1-x)O3 ceramics shifts to lower temperature more rapidly than that of BaZr
x
Ti1-x
O3 ceramics as the same x content. It was found that Ba(Y0.5Nb0.5)0.06Ti0.94O3 ceramics has compact structure, better temperature stability of dielectric constant, larger dielectric tunability under DC electric field. The results showed that, the Y2O3 and Nb2O5 doping improved the figure of merit for the BaTiO3 ceramics.
Effect of Seed Layer on Room Temperature Tunnel Magnetoresistance of MgO Barriers Formed by Radical Oxidation in IrMn-Based Magnetic Tunnel Junctions
Authors: Dahmani Faiz
Published: March 2012

NiFe-seeded magnetic tunnel junctions (MTJs) of IrMn/CoFe/MgO/CoFeB were successfully formed by radically oxidizing a thin Mg layer. Room temperature (RT) tunnel magnetoresistance (TMR) of up to 211±10% was obtained and found to be strongly dependent on the thickness of the NiFe seed layer. High resolution transmission microscopy (HRTEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and magneto-optic Kerr effect (MOKE) analyses performed on NiFe/IrMn bilayer systems revealed that the IrMn(111)-fcc texture, grain size, surface roughness (rms), and exchange-biasing field (Hex) were strongly affected by the thickness of the NiFe seed layer. A critical NiFe thickness (tc≈12 Å) was found: FortNiFe≤tc, the IrMn showed a very poor (111)-fcc texture with reduced grain size, very smooth surface, and reducedHex. FortNiFe>tc, the IrMn showed a complete opposite behavior: much enhanced (111)-fcc texture with larger grain size, rougher surface, and largerHex. For MTJ-based IrMn systems, a striking behavior is reported: larger TMRs and lower tunnel junction resistance (RA) products are obtained fortNiFe≤tcwhile lower TMRs and largerRAs are obtained fortNiFe>tc.
Analysis of the Influence of Sputtering Damage to Polymer Gate Insulators in Amorphous InGaZnO4 Thin-Film Transistors
Authors: Nakata Mitsuru , Sato Hiroto , Nakajima Yoshiki , Tsuji Hiroshi , Fujisaki Yoshihide , Takei Tatsuya , Yamamoto Toshihiro , Fujikake Hideo
Published: March 2012

We have fabricated InGaZnO4 (IGZO) thin-film transistors (TFTs) with olefin-type polymer gate insulators formed at 130 °C and compared the transfer characteristics of top- and bottom-gate structures. We have investigated the mechanism behind the differences in the characteristics, focusing on the influence of IGZO sputtering damage to the polymer insulators. Bottom-gate IGZO-TFTs showed significant threshold voltage decreases attributable to positive fixed charges in the polymer gate insulators. These charges were generated by diffused metal ions during IGZO sputtering. Contrastingly, there was no sputtering damage to the polymer gate insulators in top-gate IGZO-TFTs, and these showed good switching performance.
Characterization of Interfaces between HfO2 Thin Film and Metal Electrode with Pre–Post Treatments
Authors: Kim Young-Nam
Published: March 2012

We investigated the effects of post O3 feeding treatment and pre–post O2 plasma treatment on HfO2 dielectric films in the metal/insulator/metal (MIM) structure TiN/HfO2/TiN. The carbon contents of the HfO2 films decreases with increasing O3 feeding time, which leads to the improvement in leakage current. The O2 plasma and O3 feeding treatments produce Hf–Hf bonds in the bulk HfO2 film and a Ti oxide layer at the film/bottom electrode and HfO2/TiN interface, which prevent the out diffusion of nitrogen into the HfO2 layer. In addition, these treatments also create the local crystallization of HfO2 at the interface. In the case of rapid thermal annealing of an actual dynamic random access memory (DRAM) structure, TiN/HfO2/Al2O3/HfO2/TiN, a local crystallization is also observed in the HfO2 layer, which enhances leakage current.
Mean Transverse Energy Measurement of Negative Electron Affinity GaAs-Based Photocathode
Authors: Matsuba Shunya , Honda Yosuke , Jin Xiuguang , Miyajima Tsukasa , Yamamoto Masahiro , Uchiyama Takashi , Kuwahara Makoto , Takeda Yoshikazu
Published: March 2012

A negative electron affinity GaAs photocathode electron source is characterized by high brightness, high quantum efficiency, and a moderate temporal response. The initial emittance depends on the mean transverse energy (MTE) of the electrons on the cathode surface. We evaluated the MTE based on emittance measurements obtained using the waist scan method with three types of cathodes: bulk GaAs, thickness-controlled samples with active-layer thicknesses of 100 and 1000 nm, and a GaAs/GaAsP superlattice sample. The dependence of the cathode quantum efficiency, the laser wavelength, and the thickness of the GaAs cathode active layer on the MTE are described. In the case of the bulk GaAs and the thickness-controlled samples, it was determined that the thickness and cathode quantum efficiency do not affect the MTE within the measurement error. The laser wavelength, on the other hand, affects the MTE of all cathodes.
Nanoimprint Mold for 2.5 Tbit/in.2 Directed Self-Assembly Bit Patterned Media with Phase Servo Pattern
Authors: Yamamoto Ryousuke , Yuzawa Akiko , Shimada Takuya , Ootera Yasuaki , Kamata Yoshiyuki , Kihara Naoko , Kikitsu Akira
Published: March 2012

We demonstrate the mold fabrication and replication process for the production of 0.8 and 2.5 Tbit/in.2 directed self-assembly bit patterned media (DSA-BPM). These devices are fabricated with 33 and 17 nm dot pitch patterns using the microphase segregation structure of polystyrene–poly(dimethylsiloxane) as an etching mask template. The self-assembled dot arrays are simultaneously ordered on both the circular tracks for the data area and the arbitrary marks for the servo area by DSA using groove guides. We fabricated the Si mold with dot pillars of 19.3 nm height for the 2.5 Tbit/in.2 DSA-BPM from the poly(dimethylsiloxane) dot mask. We also demonstrated the nickel mold replication of the 0.8 Tbit/in.2 DSA-BPM by electroforming from the Si mold.
Activation of rat intestinal mucosal mast cells by fat absorption
Authors: Ji Yong , Sakata Yasuhisa , Yang Qing , Li Xiaoming , Xu Min , Yoder Stephanie , Langhans Wolfgang , Tso Patrick
Published: March 2012

Previous studies have linked certain types of gut mucosal immune cells with fat intake. We determined whether fat absorption activates intestinal mucosal mast cells (MMC), a key component of the gut mucosal immune system. Conscious intestinal lymph fistula rats were used. The mesenteric lymph ducts were cannulated, and the intraduodenal (i.d.) tubes were installed for the infusion of Liposyn II 20% (an intralipid emulsion). Lymphatic concentrations of histamine, rat MMC protease II (RMCPII), a specific marker of rat intestinal MMC degranulation, and prostaglandin D2(PGD2) were measured by ELISA. Intestinal MMC degranulation was visualized by immunofluorescent microscopy of jejunum sections taken at 1 h after Liposyn II gavage. Intraduodenal bolus infusion of Liposyn II 20% (4.4 kcal/3 ml) induced approximately a onefold increase in lymphatic histamine and PGD2, ∼20-fold increase in lymphatic RMCPII, but only onefold increase in peripheral serum RMCPII concentrations. Release of RMCPII into lymph increased dose dependently with the amount of lipid fed. In addition, i.d. infusion of long-chain triacylglycerol trilinolein (C18:2 n-6, the major composite in Liposyn II) significantly increased the lymphatic RMCPII concentration, whereas medium-chain triacylglycerol tricaprylin (C8:0) did not alter lymph RMCPII secretion. Immunohistochemistry image revealed the degranulation of MMC into lamina propria after lipid feeding. These novel findings indicate that intestinal MMC are activated and degranulate to release MMC mediators to the circulation during fat absorption. This action of fatty acid is dose and chain length dependent.
A nomenclature for intestinal in vitro cultures
Authors: Stelzner Matthias , Helmrath Michael , Dunn James C. Y. , Henning Susan J. , Houchen Courtney W. , Kuo Calvin , Lynch John , Li Linheng , Magness Scott T. , Martin Martin G. , Wong Melissa H. , Yu Jian
Published: March 2012

Many advances have been reported in the long-term culture of intestinal mucosal cells in recent years. A significant number of publications have described new culture media, cell formations, and growth patterns. Furthermore, it is now possible to study, e.g., the capabilities of isolated stem cells or the interactions between stem cells and mesenchyme. However, at the moment there is significant variation in the way these structures are described and named. A standardized nomenclature would benefit the ability to communicate and compare findings from different laboratories using the different culture systems. To address this issue, members of the NIH Intestinal Stem Cell Consortium herein propose a systematic nomenclature for in vitro cultures of the small and large intestine. We begin by describing the structures that are generated by preparative steps. We then define and describe structures produced in vitro, specifically: enterosphere, enteroid, reconstituted intestinal organoid, induced intestinal organoid, colonosphere, colonoid, and colonic organoid.
PDGF-α stimulates intestinal epithelial cell turnover after massive small bowel resection in a rat
Authors: Sukhotnik Igor , Mogilner Jorge G. , Pollak Yulia , Blumenfeld Shiri , Bejar Jacob , Coran Arnold G.
Published: March 2012

Numerous cytokines have been shown to affect epithelial cell differentiation and proliferation through epithelial-mesenchymal interaction. Growing evidence suggests that platelet-derived growth factor (PDGF) signaling is an important mediator of these interactions. The purpose of this study was to evaluate the effect of PDGF-α on enterocyte turnover in a rat model of short bowel syndrome (SBS). Male rats were divided into four groups: Sham rats underwent bowel transection, Sham-PDGF-α rats underwent bowel transection and were treated with PDGF-α, SBS rats underwent a 75% bowel resection, and SBS-PDGF-α rats underwent bowel resection and were treated with PDGF-α. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined at euthanasia. Illumina's Digital Gene Expression analysis was used to determine PDGF-related gene expression profiling. PDGF-α and PDGF-α receptor (PDGFR-α) expression was determined by real-time PCR. Western blotting was used to determine p-ERK, Akt1/2/3, bax, and bcl-2 protein levels. SBS rats demonstrated a significant increase in PDGF-α and PDGFR-α expression in jejunum and ileum compared with sham animals. SBS-PDGF-α rats demonstrated a significant increase in bowel and mucosal weight, villus height, and crypt depth in jejunum and ileum compared with SBS animals. PDGF-α receptor expression in crypts increased in SBS rats (vs. sham) and was accompanied by an increased cell proliferation following PDGF-α administration. A significant decrease in cell apoptosis in this group was correlated with lower bax protein levels. In conclusion, in a rat model of SBS, PDGF-α stimulates enterocyte turnover, which is correlated with upregulated PDGF-α receptor expression in the remaining small intestine.
Interaction with CREB binding protein modulates the activities of Nrf2 and NF-κB in cystic fibrosis airway epithelial cells
Authors: Ziady Assem G. , Sokolow Andrew , Shank Samuel , Corey Deborah , Myers Ross , Plafker Scott , Kelley Thomas J.
Published: March 2012

Cystic fibrosis (CF) is characterized by inflammatory lung disease that significantly contributes to morbidity and mortality. Airway epithelial cells play a role in the inflammatory signaling in CF and have been reported to exhibit a number of dysfunctions in signaling cascades that modulate inflammation. Previously, we reported that the activity of nuclear factor erythroid-derived-like 2 (Nrf2), a transcription factor that regulates antioxidant and cytoprotective protein expression, is diminished in CF epithelia ( 7 ). In this report, we examined the mechanism of Nrf2 dysregulation in vitro in human airway epithelial cell lines and primary cells and in vivo in nasal epithelia excised from ΔF508 CF mutant mice. We found that cAMP-mediated signaling markedly reduces Nrf2 activity in CF vs. non-CF cells. Rp-cAMPS, a cAMP competitor, significantly corrected Nrf2 activity in CF cells, predominantly by increasing the nuclear accumulation of the transcription factor. Furthermore, we found that Rp-cAMPS significantly decreased NF-κB activation following inflammatory stimulation of CF cells. Further investigation revealed that Nrf2 and NF-κB compete for the transcriptional coactivator cAMP responsive element-binding protein (CREB) binding protein (CBP) and that Rp-cAMPS shifts CBP association in favor of Nrf2. Thus our findings provide a link between feedback to CF transmembrane regulator dysfunction and dysregulation of an inflammatory signaling pathway that modulates the coordinated activities of Nrf2 and NF-κB. Furthermore, our studies suggest that strategies that shift CBP association away from NF-κB and toward Nrf2 could have potential therapeutic efficacy for reducing inflammation in patients with CF.
Inspiratory muscle fatigue increases sympathetic vasomotor outflow and blood pressure during submaximal exercise
Authors: Katayama Keisho , Iwamoto Erika , Ishida Koji , Koike Teruhiko , Saito Mitsuru
Published: March 2012

The purpose of this study was to elucidate the influence of inspiratory muscle fatigue on muscle sympathetic nerve activity (MSNA) and blood pressure (BP) response during submaximal exercise. We hypothesized that inspiratory muscle fatigue would elicit increases in sympathetic vasoconstrictor outflow and BP during dynamic leg exercise. The subjects carried out four submaximal exercise tests: two were maximal inspiratory pressure (PImax) tests and two were MSNA tests. In the PImax tests, the subjects performed two 10-min exercises at 40% peak oxygen uptake using a cycle ergometer in a semirecumbent position [spontaneous breathing for 5 min and with or without inspiratory resistive breathing for 5 min (breathing frequency: 60 breaths/min, inspiratory and expiratory times were each set at 0.5 s)]. Before and immediately after exercise, PImax was estimated. In MSNA tests, the subjects performed two 15-min exercises (spontaneous breathing for 5 min, with or without inspiratory resistive breathing for 5 min, and spontaneous breathing for 5 min). MSNA was recorded via microneurography of the right median nerve at the elbow. PImax decreased following exercise with resistive breathing, whereas no change was found without resistance. The time-dependent increase in MSNA burst frequency (BF) appeared during exercise with inspiratory resistive breathing, accompanied by an augmentation of diastolic BP (DBP) (with resistance: MSNA, BF +83.4%; DBP, +23.8%; without resistance: MSNA BF, +19.2%; DBP, −0.4%, from spontaneous breathing during exercise). These results suggest that inspiratory muscle fatigue induces increases in muscle sympathetic vasomotor outflow and BP during dynamic leg exercise at mild intensity.
Enzymatic processing of angiotensin peptides by human glomerular endothelial cells
Authors: Velez Juan Carlos Q. , Ierardi Jessalyn L. , Bland Alison M. , Morinelli Thomas A. , Arthur John M. , Raymond John R. , Janech Michael G.
Published: March 2012

The intraglomerular renin-angiotensin system (RAS) is linked to the pathogenesis of progressive glomerular diseases. Glomerular podocytes and mesangial cells play distinct roles in the metabolism of angiotensin (ANG) peptides. However, our understanding of the RAS enzymatic capacity of glomerular endothelial cells (GEnCs) remains incomplete. We explored the mechanisms of endogenous cleavage of ANG substrates in cultured human GEnCs (hGEnCs) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and isotope-labeled peptide quantification. Overall, hGEnCs metabolized ANG II at a significantly slower rate compared with podocytes, whereas the ANG I processing rate was comparable between glomerular cell types. ANG II was the most abundant fragment of ANG I, with lesser amount of ANG-(1–7) detected. Formation of ANG II from ANG I was largely abolished by an ANG-converting enzyme (ACE) inhibitor, whereas ANG-(1–7) formation was decreased by a prolylendopeptidase (PEP) inhibitor, but not by a neprilysin inhibitor. Cleavage of ANG II resulted in partial conversion to ANG-(1–7), a process that was attenuated by an ACE2 inhibitor, as well as by an inhibitor of PEP and prolylcarboxypeptidase. Further fragmentation of ANG-(1–7) to ANG-(1–5) was mediated by ACE. In addition, evidence of aminopeptidase N activity (APN) was demonstrated by detecting amelioration of conversion of ANG III to ANG IV by an APN inhibitor. While we failed to find expression or activity of aminopeptidase A, a modest activity attributable to aspartyl aminopeptidase was detected. Messenger RNA and gene expression of the implicated enzymes were confirmed. These results indicate that hGEnCs possess prominent ACE activity, but modest ANG II-metabolizing activity compared with that of podocytes. PEP, ACE2, prolylcarboxypeptidase, APN, and aspartyl aminopeptidase are also enzymes contained in hGEnCs that participate in membrane-bound ANG peptide cleavage. Injury to specific cell types within the glomeruli may alter the intrarenal RAS balance.
Effects of dehydration on cerebrovascular control during standing after heavy resistance exercise
Authors: Moralez Gilbert , Romero Steven A. , Rickards Caroline A. , Ryan Kathy L. , Convertino Victor A. , Cooke William H.
Published: March 2012

We tested the hypothesis that dehydration exacerbates reductions of middle cerebral artery blood velocity (MCAv) and alters cerebrovascular control during standing after heavy resistance exercise. Ten males participated in two trials under 1) euhydration (EUH) and 2) dehydration (DEH; fluid restriction + 40 mg furosemide). We recorded finger photoplethysmographic arterial pressure and MCAv (transcranial Doppler) during 10 min of standing immediately after high-intensity leg press exercise. Symptoms (e.g., lightheadedness) were ranked by subjects during standing (1–5 scale). Low-frequency (LF) oscillations of mean arterial pressure (MAP) and mean MCAv were calculated as indicators of cerebrovascular control. DEH reduced plasma volume by 11% ( P = 0.002; calculated from hemoglobin and hematocrit). During the first 30 s of standing after exercise, subjects reported greater symptoms during DEH vs. EUH ( P = 0.05), but these were mild and resolved at 60 s. While MAP decreased similarly between conditions immediately after standing, MCAv decreased more with DEH than EUH ( P = 0.02). With prolonged standing under DEH, mean MCAv remained below baseline ( P ≤ 0.01), and below EUH values ( P ≤ 0.05). LF oscillations of MAP were higher for DEH at baseline and during the entire 10 min of stand after exercise ( P ≤ 0.057), while LF oscillations in mean MCAv were distinguishable only at baseline and 5 min following stand ( P = 0.05 ). Our results suggest that mean MCAv falls below a “symptomatic threshold” in the acute phase of standing after exercise during DEH, although symptoms were mild and transient. During the prolonged phase of standing, increases in LF MAP and mean MCAv oscillations with DEH may help to maintain cerebral perfusion despite absolute MCAv remaining below the symptomatic threshold.
Effects of eccentric exercise on toll-like receptor 4 signaling pathway in peripheral blood mononuclear cells
Authors: Fernandez-Gonzalo Rodrigo , De Paz José A. , Rodriguez-Miguelez Paula , Cuevas María J. , González-Gallego Javier
Published: March 2012

This study aimed to investigate the response of the toll-like receptor 4 (TLR4) signaling pathway to an acute bout of eccentric exercise, and to assess whether eccentric training attenuated the effects induced by acute eccentric exercise. Twenty men (22.4 ± 0.5 yr) were divided into a control group (CG, n = 8) and a training group (TG, n = 12). Both groups performed two acute eccentric bouts on a squat machine in a 9-wk interval. During this time, TG followed a 6-wk eccentric training program (3 session/wk; 3–5 sets of 10 repetitions with loads ranging between the 40 and 50% of maximal isometric voluntary contraction). CD14, TLR4, and TNF-α mRNA levels, and CD14, TLR4, myeloid differentiation factor 88, tumor necrosis factor receptor-associated factor 6, TIR-domain-containing adapter-inducing interferon-β, phospho-IκB kinases, phospho-IκB, phospho-ERK-1/2, and TNF-α protein concentration were measured in peripheral blood mononuclear cells, before, immediately, and 2 h after each eccentric bout. The first acute eccentric bout triggered a proinflammatory response mediated by an upregulation of all of the factors measured within the TLR4 signaling pathway. Following the training period and after the second acute bout, CG showed a similar proinflammatory response than that seen after the first bout. However, the eccentric training intervention decreased significantly the protein concentration of all factors analyzed in TG compared with results obtained after the first bout. These results suggest that the TLR4-signaling pathway plays a critical role in the proinflammatory response seen after acute eccentric exercise. This response was attenuated after an eccentric training program through myeloid differentiation factor 88-dependent and -independent pathways.
Frequency-dependent effects of electrical stimulation in the globus pallidus of dystonia patients
Authors: Liu Liu D. , Prescott Ian A. , Dostrovsky Jonathan O. , Hodaie Mojgan , Lozano Andres M. , Hutchison William D.
Published: March 2012

Deep brain stimulation (DBS) in the globus pallidus internus (GPi) has been shown to improve dystonia, a movement disorder of repetitive twisting movements and postures. DBS at frequencies above 60 Hz improves dystonia, but the mechanisms underlying this frequency dependence are unclear. In patients undergoing dual-microelectrode mapping of the GPi, microstimulation has been shown to reduce neuronal firing, presumably due to synaptic GABA release. This study examined the effects of different microstimulation frequencies (1–100 Hz) and train length (0.5–20 s), with and without prior high-frequency stimulation (HFS) on neuronal firing and evoked field potentials (fEPs) in 13 dystonia patients. Pre-HFS, the average firing decreased as stimulation frequency increased and was silenced above 50 Hz. The average fEP amplitudes increased up to frequencies of 20–30 Hz but then declined and at 50 Hz, were only at 75% of baseline. In some cases, short latency fiber volleys and antidromic-like spikes were observed and followed high frequencies. Post-HFS, overall firing was reduced compared with pre-HFS, and the fEP amplitudes were enhanced at low frequencies, providing evidence of inhibitory synaptic plasticity in the GPi. In a patient with DBS electrodes already implanted in the GPi, recordings from four neurons in the subthalamic nucleus showed almost complete inhibition of firing with clinically effective but not clinically ineffective stimulation parameters. These data provide additional support for the hypothesis of stimulation-evoked GABA release from afferent synaptic terminals and reduction of neuronal firing during DBS and additionally, implicate excitation of GPi axon fibers and neurons and enhancement of inhibitory synaptic transmission by high-frequency GPi DBS as additional putative mechanisms underlying the clinical benefits of DBS in dystonia.
Macaque V1 representations in natural and reduced visual contexts: spatial and temporal properties and influence of saccadic eye movements
Authors: Ruiz Octavio , Paradiso Michael A.
Published: March 2012

Vision in natural situations is different from the paradigms generally used to study vision in the laboratory. In natural vision, stimuli usually appear in a receptive field as the result of saccadic eye movements rather than suddenly flashing into view. The stimuli themselves are rich with meaningful and recognizable objects rather than simple abstract patterns. In this study we examined the sensitivity of neurons in macaque area V1 to saccades and to complex background contexts. Using a variety of visual conditions, we find that natural visual response patterns are unique. Compared with standard laboratory situations, in more natural vision V1 responses have longer latency, slower time course, delayed orientation selectivity, higher peak selectivity, and lower amplitude. Furthermore, the influences of saccades and background type (complex picture vs. uniform gray) interact to give a distinctive, and presumably more natural, response pattern. While in most of the experiments natural images were used as background, we find that similar synthetic unnatural background stimuli produce nearly identical responses (i.e., complexity matters more than “naturalness”). These findings have important implications for our understanding of vision in more natural situations. They suggest that with the saccades used to explore complex images, visual context (“surround effects”) would have a far greater effect on perception than in standard experiments with stimuli flashed on a uniform background. Perceptual thresholds for contrast and orientation should also be significantly different in more natural situations.
Second-order receptive fields reveal multidigit interactions in area 3b of the macaque monkey
Authors: Thakur Pramodsingh H. , Fitzgerald Paul J. , Hsiao Steven S.
Published: March 2012

Linear receptive field (RF) models of area 3b neurons reveal a three-component structure: a central excitatory region flanked by two inhibitory regions that are spatially and temporally nonoverlapping with the excitation. Previous studies also report that there is an “infield” inhibitory region throughout the neuronal RF, which is a nonlinear interactive (second order) effect whereby stimuli lagging an input to the excitatory region are suppressed. Thus linear models may be inaccurate approximations of the neurons' true RFs. In this study, we characterize the RFs of area 3b neurons, using a second-order quadratic model. Data were collected from 80 neurons of two awake, behaving macaque monkeys while a random dot pattern was scanned simultaneously across the distal pads of digits D2, 3, and 4. We used an iterative method derived from matching pursuit to identify a set of linear and nonlinear terms with significant effects on the neuronal response. For most neurons (65/80), the linear component of the quadratic RF was characterized by a single excitatory region on the dominant digit. Interactions within the dominant digit were characterized by two quadratic filters that capture the spatial aspects of the interactive infield inhibition. Interactions between the dominant (most responsive) digit and its adjacent digit(s) formed the largest class of cross-digit interactions. The results demonstrate that a significant part of area 3b responses is due to nonlinear mechanisms, and furthermore, the data support the notion that area 3b neurons have “nonclassical RF”-like input from adjacent fingers, indicating that area 3b plays a role in integrating shape inputs across digits.
Activation of Ras/PI3K/ERK Pathway Induces c-Myc Stabilization to Upregulate Argininosuccinate Synthetase, Leading to Arginine Deiminase Resistance in Melanoma Cells
Authors: Tsai Wen-Bin , Aiba Isamu , Long Yan , Lin Hui-Kuan , Feun Lynn , Savaraj Niramol , Kuo Macus Tien
Published: March 2012

Melanomas and other cancers that do not express argininosuccinate synthetase (AS), the rate-limiting enzyme for arginine biosynthesis, are sensitive to arginine depletion with pegylated arginine deiminase (ADI-PEG20). However, ADI resistance eventually develops in tumors because of AS upregulation. Although it has been shown that AS upregulation involves c-Myc, the underlying mechanisms remain unknown. Here we show that ADI-PEG20 activates Ras signaling and the effector extracellular signal–regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/AKT/GSK-3β kinase cascades, resulting in phosphorylation and stabilization of c-Myc by attenuation of its ubiquitin-mediated protein degradation mechanism. Inhibition of the induced cell signaling pathways using PI3K/AKT inhibitors suppressed c-Myc induction and enhanced ADI-mediated cell killing. Notably, in an animal model of AS-negative melanoma, combination therapy using a PI3K inhibitor plus ADI-PEG20 yielded additive antitumor effects as compared with either agent alone. Taken together, our findings offer mechanistic insight into arginine deprivation metabolism and ADI resistance, and they illustrate how combining inhibitors of the Ras/ERK and PI3K/AKT signaling pathways may improve ADI-PEG20 anticancer responses. Cancer Res; 72(10); 2622–33. ©2012 AACR.
Molecular Profiling of Pancreatic Neuroendocrine Tumors in Sporadic and Von Hippel-Lindau Patients
Authors: Speisky Daniela , Duces Aurélie , Bièche Ivan , Rebours Vinciane , Hammel Pascal , Sauvanet Alain , Richard Stéphane , Bedossa Pierre , Vidaud Michel , Murat Arnaud , Niccoli Patricia , Scoazec Jean-Yves , Ruszniewski Philippe , Couvelard Anne
Published: March 2012

Purpose: Von Hippel-Lindau (VHL) disease is an inherited syndrome caused by germline mutations in the VHL tumor suppressor gene, predisposing to a variety of neoplasms including pancreatic neuroendocrine tumors (PanNET). In VHL disease, PanNET probably progress according to a specific pathway of carcinogenesis. Our aim was to characterize by molecular quantitative analysis a panel of molecules implicated in the VHL pathway and in tumor progression in the PanNET of patients with VHL.

Experimental Design: The expression of 52 genes was studied by quantitative reverse transcriptase PCR in 18 patients with VHL operated on for PanNET and compared with 16 non-VHL PanNET. The VHL and non-VHL tumors were matched according to their size and cell proliferation. For some genes, we looked for differences in the protein expression in VHL PanNET (n = 31), microadenomas (n = 22), and non-VHL PanNET (n = 16), included in tissue microarray blocks.

Results: Nineteen (36%) genes were significantly upregulated and three (6%) downregulated in VHL PanNET. The upregulated genes were related to (i) hypoxia-inducible factor (HIF) molecules (CA9, HIF2A, and GLUT1), (ii) angiogenesis (CDH5, VEGFR1, EDNRA, ANGPT2, CD34, VEGFR2, VEGFA, and ANGPT1), (iii) the processes of epithelial–mesenchymal transition (VIM) and/or metastasis (LAMA4 and CXCR4), (iv) growth factors and receptors (PDGFB, IRS1, and ERBB1), or (v) cell cycle (CCND1 and CDKN2A). The downregulated genes were related to (i) EMT (OCLN) and (ii) signaling pathways (RPS6KB1 and GADD45B).

Conclusion: This study shows that the progression of PanNET in patients with VHL tumors follows a specific pathway and supports that targeting molecules specifically involved may be of therapeutic importance. Clin Cancer Res; 18(10); 2838–49. ©2012 AACR.
Determinants of Residual Risk in Secondary Prevention Patients Treated With High- Versus Low-Dose Statin Therapy
Authors: Mora Samia , Wenger Nanette K. , DeMicco David A. , Breazna Andrei , Boekholdt S. Matthijs , Arsenault Benoit J. , Deedwania Prakash , Kastelein John J.P. , Waters David D.
Published: March 2012

Background—

Cardiovascular events occur among statin-treated patients, albeit at lower rates. Risk factors for this “residual risk” have not been studied comprehensively. We aimed to identify determinants of this risk above and beyond lipid-related risk factors.

Methods and Results—

A total of 9251 coronary patients with low-density lipoprotein cholesterol <130 mg/dL randomized to double-blind atorvastatin 10 or 80 mg/d in the Treating to New Targets (TNT) study had complete on-treatment 1-year lipid data. Median follow-up was 4.9 years. The primary end point was major cardiovascular events (n=729): coronary death, nonfatal myocardial infarction, resuscitation after cardiac arrest, or fatal or nonfatal stroke. Multivariable determinants of increased risk were older age (adjusted hazard ratio [aHR], 1.13 per 1 SD [8.8 years]; 95% confidence interval [CI], 1.04–1.23), increased body mass index (aHR, 1.09; 95% CI, 1.02–1.17 per 4.5 kg/m
2
), male sex (aHR, 1.33; 95% CI, 1.07–1.65), hypertension (aHR, 1.38; 95% CI, 1.17–1.63), diabetes mellitus (aHR, 1.33; 95% CI, 1.11–1.60), baseline apolipoprotein B (aHR, 1.19; 95% CI, 1.11–1.28 per 19 mg/dL), and blood urea nitrogen (aHR, 1.10; 95% CI, 1.03–1.17 per 4.9 mg/dL), in addition to current smoking, prior cardiovascular disease, and calcium channel blocker use. Determinants of decreased risk were high-dose statin (aHR, 0.82; 95% CI, 0.70–0.94), aspirin use (aHR, 0.67; 95% CI, 0.56–0.81), and baseline apolipoprotein A-I (aHR, 0.91; 95% CI, 0.84–0.99 per 25 mg/dL). On-treatment 1-year lipids or apolipoproteins were not additionally associated with risk in multivariable models. Known baseline variables performed moderately well in discriminating future cases from noncases (Harrell c index=0.679).

Conclusions—

Determinants of residual risk in statin-treated secondary prevention patients included lipid-related and nonlipid factors such as baseline apolipoproteins, increased body mass index, smoking, hypertension, and diabetes mellitus. A multifaceted prevention approach should be underscored to address this risk.

Clinical Trial Registration—

URL:
http://clinicaltrials.gov
. Unique identifier: NCT00327691.
Pharmacological Induction of Heme Oxygenase-1 by a Triterpenoid Protects Neurons Against Ischemic Injury
Authors: Zhang Feng , Wang Suping , Zhang Meijuan , Weng Zhongfang , Li Peiying , Gan Yu , Zhang Lili , Cao Guodong , Gao Yanqin , Leak Rehana K. , Sporn Michael B. , Chen Jun
Published: March 2012

Background and Purpose—

Heme oxygenase-1 (HO-1) is an inducible Phase 2 enzyme that degrades toxic heme; its role in cerebral ischemia is not fully understood. We hypothesize that chemically induced HO-1 upregulation with the novel triterpenoid CDDO-Im (2-cyano-3,12 dioxooleana-1,9 dien-28-oyl imidazoline), a robust inducer of Phase 2 genes, protects neurons against ischemic injury.

Methods—

Using 3 different models of ischemia, including oxygen–glucose deprivation in neuronal cultures, global ischemia in rats, and focal ischemia in mice, we determined (1) whether CDDO-Im induces HO-1 expression and protects against ischemic injury; and (2) whether HO-1 inhibition disrupts the neuroprotective effect of CDDO-Im.

Results—

CDDO-Im treatment (50–300 nmol/L) resulted in 8-fold HO-1 upregulation in cultured neurons and protected against oxygen–glucose deprivation. The protection was abolished when the cultures were transfected with nuclear factor (erythroid-derived 2) like-2–shRNA or coincubated with tin protoporphyrin IX, a specific HO-1 inhibitor. In the rat model of global ischemia, intracerebroventricular infusion of CDDO-Im (0.5–1.5 μg) augmented HO-1 expression in hippocampal neurons and resulted in significant increases in CA1 neuronal survival after global ischemia. To further strengthen the clinical relevance of the CDDO-Im treatment, we tested its effects in the mouse model of temporary focal ischemia (60 minutes). Postischemic intraperitoneal injection of CDDO-Im (10–100 μg) enhanced HO-1 expression and significantly reduced neurological dysfunction and infarct volume. Intracerebroventricular infusion of tin protoporphyrin IX reduced the neuroprotective effect of CDDO-Im against global and focal ischemia.

Conclusions—

CDDO-Im confers neuroprotection against ischemic injury by upregulating HO-1, suggesting that enhance of HO-1 expression may be a legitimate strategy for therapeutic intervention of stroke.
A Nonoscillatory Discontinuous Galerkin Transport Scheme on the Cubed Sphere
Authors: Zhang Yifan , Nair Ramachandran D.
Published: March 2012

The discontinuous Galerkin (DG) method is high order, conservative, and offers excellent parallel efficiency. However, when there are discontinuities in the solution, the DG transport scheme generates spurious oscillations that reduce the quality of the numerical solution. For applications such as the atmospheric tracer transport modeling, a nonoscillatory, positivity-preserving solution is a basic requirement. To suppress the oscillations in the DG solution, a limiter based on the Hermite-Weighted Essentially Nonoscillatory (H-WENO) method has been implemented for a third-order DG transport scheme. However, the H-WENO limiter can still produce wiggles with small amplitudes in the solutions, but this issue has been addressed by combining the limiter with a bound-preserving (BP) filter. The BP filter is local and easy to implement and can be used for making the solution strictly positivity preserving. The DG scheme combined with the limiter and filter preserves the accuracy of the numerical solution in the smooth regions while effectively eliminating overshoots and undershoots. The resulting nonoscillatory DG scheme is third-order accurate (P2-DG) and based on the modal discretization. The 2D Cartesian scheme is further extended to the cubed-sphere geometry, which employs nonorthogonal, curvilinear coordinates. The accuracy and effectiveness of the limiter and filter are demonstrated with several benchmark tests on both the Cartesian and spherical geometries.
Why Some Immigrant Neighborhoods Are Safer than Others
Authors: Kubrin Charis E. , Ishizawa Hiromi
Published: March 2012

Contrary to popular opinion, scholarly research has documented that immigrant communities are some of the safest places around. Studies repeatedly find that immigrant concentration is either negatively associated with neighborhood crime rates or not related to crime at all. But are immigrant neighborhoods always safer places? How does the larger community context within which immigrant neighborhoods are situated condition the immigration-crime relationship? Building on the existing literature, this study examines the relationship between immigrant concentration and violent crime across neighborhoods in Los Angeles and Chicago—two cities with significant and diverse immigrant populations. Of particular interest is whether neighborhoods with high levels of immigrant concentration that are situated within larger immigrant communities are especially likely to enjoy reduced crime rates. This was found to be the case in Chicago but not in Los Angeles, where neighborhoods with greater levels of immigrant concentration experienced higher, not lower, violent crime rates when located within larger immigrant communities. We speculate on the various factors that may account for the divergent findings.
Are Immigrant Youth Less Violent? Specifying the Reasons and Mechanisms
Authors: MacDonald John , Saunders Jessica
Published: March 2012

In this article, the authors present an overview of the relationship between immigrant households and crime and violence, drawing on sociological and public health literature. They present a critique of popular culture perspectives on immigrant families and youth violence, showing that crime and violence outcomes are if anything better for youth in immigrant families than one would expect given the social disadvantages that many immigrant households find themselves living in. They examine the extent to which exposure to violence among immigrant youth is comparably lower than among nonimmigrants living in similar social contexts and the extent to which social control and social learning frameworks can account for the apparent lower prevalence of violence exposure among immigrant youth. Their analyses show a persistent lower rate of violence exposure for immigrant youth compared to similarly situated nonimmigrant youth—and that these differences are not meaningfully understood by observed social control or social learning mechanisms. The authors focus then on the apparent paradox of why youth living in immigrant households in relative disadvantage have lower violence exposure compared to nonimmigrants living in similar social contexts. The answers, they argue, can be viewed from an examination of the effects that living in poverty and underclass neighborhoods for generations has on nonimmigrants in American cities.
Extending Immigration and Crime Studies
Authors: Martinez Ramiro , Stowell Jacob I.
Published: March 2012

One of American society’s enduring debates centers on the immigration and violent crime relationship. This classic debate is revisited using data for individual homicide incidents and census-tract-level homicides in Miami, Florida, and San Antonio, Texas, in the 1980s and 1990s, respectively. The article starts with these two comparative cases because they mirror the immigration influx, Latino growth, and homicide decline seen throughout the country since 1980. These findings are also replicated in an analysis of the immigration and crime influx across the nation using U.S. counties in 2000. In sum, results from comparative cases, different time points, homicide motivations, and individual/community/national levels—and even controlling for Latino regional concentration—are reported. The findings were clear and unequivocal: more immigrants did not mean more homicide, and that outcome held across time and place.
Strain dependency in wrinkling performance of butanetetracarboxylic acid and lubricant-treated cotton fabric
Authors: Asvadi Sima , Janner Anna-Maria , Hultermans Edo , Mavinkurve Amar , Ormandy Kevin , Southey-Davis Hannah , Jarvis Paula , Griffith Llyr
Published: March 2012

The role of strain level in the assessment of wrinkling performance of 100% cotton fabric treated with various in-wear wrinkle-resistant (IWWR) additives was investigated. Two additives, a cross-linking agent and a fabric lubricant were both separately and in combination applied to cotton fabric samples. In this investigation multiple laboratory tests were used, including fabric bending hysteresis and stress relaxation under medium to high curvatures, fabric shear, controlled laboratory fabric wrinkling (wrinkle tester) as well as crease recovery angle measurements. The results were analyzed, with reference to the viscoelastic and frictional model of fabric wrinkling, in order to evaluate the IWWR performance of the treated and untreated fabric samples objectively and quantitatively. The correlation between these results and the subjective evaluation of wrinkle recovery performance of shirts in an in-wear panel test was evaluated.
Callous-Unemotional Traits and Their Implication for Understanding and Treating Aggressive and Violent Youths
Authors: Muñoz Luna C. , Frick Paul J.
Published: March 2012

This article reviews the current research literature on the development of aggression and callous-unemotional traits. Research suggests there are two functions to aggression, reactive and instrumental, and each has concomitant cognitive and emotional factors associated. Furthermore, callous-unemotional (CU) traits (i.e., an absence of empathy and guilt) have been shown to be associated with the instrumental type of aggression. Research on CU traits suggests that there are distinct developmental mechanisms operating in the development of aggressive and violent behavior for youths with and without these traits. These distinct developmental mechanisms have important implications for the assessment and treatment of aggressive and violent youths.
Social Network Research in Organizational Contexts
Authors: Carpenter Mason A. , Li Mingxiang , Jiang Han
Published: March 2012

A large body of research has examined social networks in organizational contexts. While this work has enhanced scholars’ understanding of the antecedents and consequences of networks, missing from this literature is a comprehensive framework that simplifies and clarifies this complex body of work. In response, the authors develop a framework that classifies network research into four major categories, with the purpose of guiding scholars’ choices among the various theories, constructs, measures, research designs, and analytic strategies inherent in the social network literature. The authors also provide recommendations for future work aimed at advancing the state of network research in organizational contexts.