bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impaired Coenzyme A metabolism affects histone and tubulin acetylation in Drosophila and human cell models of pantothenate kinase associated neurodegeneration
Authors: Siudeja Katarzyna , Srinivasan Balaji , Xu Lanjun , Rana Anil , de Jong Jannie , Nollen Ellen A. A. , Jackowski Suzanne , Sanford Lynn , Hayflick Susan , Sibon Ody C. M. 
Published: October 2011

AbstractPantothenate kinase‐associated neurodegeneration (PKAN is a neurodegenerative disease with unresolved pathophysiology. Previously, we observed reduced Coenzyme A levels in a Drosophila model for PKAN. Coenzyme A is required for acetyl‐Coenzyme A synthesis and acyl groups from the latter are transferred to lysine residues of proteins, in a reaction regulated by acetyltransferases. The tight balance between acetyltransferases and their antagonistic counterparts histone deacetylases is a well‐known determining factor for the acetylation status of proteins. However, the influence of Coenzyme A levels on protein acetylation is unknown. Here we investigate whether decreased levels of the central metabolite Coenzyme A induce alterations in protein acetylation and whether this correlates with specific phenotypes of PKAN models. We show that in various organisms proper Coenzyme A metabolism is required for maintenance of histone‐ and tubulin acetylation, and decreased acetylation of these proteins is associated with an impaired DNA damage response, decreased locomotor function and decreased survival. Decreased protein acetylation and the concurrent phenotypes are partly rescued by pantethine and HDAC inhibitors, suggesting possible directions for future PKAN therapy development.
The many faces of preparatory control in task switching: Reviewing a decade of fMRI research
Authors: Ruge Hannes , Jamadar Sharna , Zimmermann Uta , Karayanidis Frini 
Published: October 2011

AbstractA large body of behavioural research has used the cued task‐switching paradigm to characterize the nature of trial‐by‐trial preparatory adjustments that enable fluent task implementation when demands on cognitive flexibility are high. This work reviews the growing number of fMRI studies on the same topic, mostly focusing on the central hypothesis that preparatory adjustments should be indicated by enhanced prefrontal and parietal BOLD activation in task switch when compared with task repeat trials under conditions that enable advance task preparation. The evaluation of this straight‐forward hypothesis reveals surprisingly heterogeneous results regarding both the precise localization and the very existence of switch‐related preparatory activation. Explanations for these inconsistencies are considered on two levels. First, we discuss methodological issues regarding (i) the possible impact of different fMRI‐specific experimental design modifications and (ii) statistical uncertainty in the context of massively multivariate imaging data. Second, we discuss explanations related to the multidimensional nature of task preparation itself. Specifically, the precise localization and the size of switch‐related preparatory activation might depend on the differential interplay of hierarchical control via abstract task goals and attentional versus action‐directed preparatory processes. We argue that different preparatory modes can be adopted relying either on advance goal activation alone or on the advance resolution of competition within action sets or attentional sets. Importantly, while either mode can result in a reduction of behavioral switch cost, only the latter two are supposed to be associated with enhanced switch versus repeat BOLD activation in prepared trial conditions. Hum Brain Mapp, 2013. © 2011 Wiley Periodicals, Inc.
Implication of Cognitive Style in Designing Computer‐Based Procedure Interface
Authors: Su Kuo‐Wei , Chen Chiu‐Jung , Shue Li‐Yen 
Published: October 2011

AbstractDifferent people have different models of mental perception, which form the bases of human reactions. The design of human‐computer interfaces should consider these differences in the cognitive models of users to achieve maximum benefits. The Myers‐Briggs Type Indicator (MBTI) is an accepted tool for measuring four dimensions of an individual's cognitive model. This research investigated the effects of two interface designs based on the characteristics of the Sensing/iNtuitive (S/N) and Thinking/Feeling (T/F) categories. These interfaces were designed for the visual information displays of computer‐based procedures at a nuclear power plant. Because of the nature of this industry, quicker reaction times are required and fewer mistakes are tolerated. A group of subjects were selected, and the subjects were assigned to either the ST or NT group before the experiment. The results, when compared with earlier statistics for a single design for all users, indicate that reaction times were reduced in some critical situations and the number of mistakes was reduced. © 2011 Wiley Periodicals, Inc.
Ocular movements under taskload manipulations: Influence of geometry on saccades in air traffic control simulated tasks
Authors: Marchitto Mauro , Di Stasi Leandro Luigi , Cañas José Juan 
Published: October 2011

AbstractTraffic geometry is a factor that contributes to cognitive complexity in air traffic control. In conflict‐detection tasks, geometry can affect the attentional effort necessary to correctly perceive and interpret the situation; online measures of situational workload are therefore highly desirable. In this study, we explored whether saccadic movements vary with changes in geometry. We created simple scenarios with two aircraft and simulated a conflict detection task. Independent variables were the conflict angle and the distance to convergence point. We hypothesized lower saccadic peak velocity (and longer duration) for increasing complexity, that is, for increasing conflict angles and for different distances to convergence point. Response times varied accordingly with task complexity. Concerning saccades, there was a decrease of peak velocity (and a related increase of duration) for increased geometry complexity for large saccades (>15°). The data therefore suggest that geometry is able to influence “reaching” saccades and not “fixation” saccades. © 2011 Wiley Periodicals, Inc.
The roles of extracellular signal‐regulated kinase 1/2 pathway in regulating osteogenic differentiation of murine preosteoblasts MC3T3‐E1 cells on roughened titanium surfaces
Authors: Zhuang Long‐Fei , Jiang Huan‐Huan , Qiao Shi‐Chong , Appert Christoph , Si Mi‐si , Gu Ying‐Xin , Lai Hong‐Chang 
Published: October 2011

AbstractSurface roughness of titanium‐based implants may enhance osteogenic differentiation of cells in vitro and bone‐to‐implant contact in vivo. Nevertheless, how surface roughness regulates the signaling pathway of osteoblasts is little understood. The study intended to investigate specifically the roles of extracellular signal‐regulated kinase 1/2 (ERK1/2) pathway in regulating osteogenic differentiation of MC3T3‐E1 murine preosteoblast cells on Ti surfaces. Substrates applied were two groups of titanium disks: (1) sand‐blasted and acid‐etched rough surfaces (SLA) and (2) smooth pretreated Ti surfaces (PT). Surface morphology of the two groups was examined by scanning electron microscope, and cell morphology cultured on Ti disks was observed by confocal microscope. The levels of alkaline phosphatase (ALP) activity and calcium deposition were measured and compared between the two groups. Real‐time polymerase chain reaction was applied to detect the expression levels of osteogenic genes including runt related protein 2 (Runx2), osterix (OSX), osteocalcin (OCN) and osteoprotegerin (OPN) of the cells cultured on the two groups of substrates and on SLA surfaces treated with ERK1/2 inhibitor, PD98095. ERK1/2 activities in MC3T3‐T1 cells were measured by Western‐blotting on the two surfaces with or without PD98095. Cells cultured on rougher SLA surfaces displayed a more differentiated morphology. ALP activities at 7 days and 14 days and the calcium deposition at 28 days were significantly higher on SLA surfaces. The expression levels of Runx2, OSX, OPN and OCN were upregulated by the effect of surface roughness and PD98095 further upregulated the expression levels of these osteogenic genes on SLA surfaces. ERK1/2 phosphorylation was continuously inhibited by surface roughness at 2 days, 4 days and 6 days. In contrast, no marked alterations in ERK1/2 phosphorylation on PT surfaces were observed. PT surfaces treated with PD98095 (50 μM) and SLA surfaces without PD98095 both demonstrated reduced ERK1/2 phosphorylation of the cells, and the inhibitive effect of SLA surfaces was milder than that of PD98095. In conclusion, ERK1/2 pathway may be a negative regulator of cell differentiation in a dosage‐dependent manner, and the enhancing effect of surface roughness on osteoblastic differentiation may be mediated through inhibiting ERK1/2 pathway. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Alignment of human vascular smooth muscle cells on parallel electrospun synthetic elastin fibers
Authors: Nivison‐Smith Lisa , Weiss Anthony S. 
Published: October 2011

AbstractWe generated parallel elastic fibers from synthetic elastin (SE) as a model of the arterial media and assessed the alignment of smooth muscle cells (SMCs). SE utilized crosslinked electrospun human tropoelastin to form aligned fibers that mimicked the topography and elastin‐rich content of the medial extracellular matrix. Bundled parallel fibers were anisotropically more elastic than randomly arranged scaffolds (111 ± 25 kPa vs. 265 ± 17 kPa) in the direction of the fibers. Aligned and random fiber scaffolds each supported SMC growth. Following attachment, SMCs proliferated longitudinally on the parallel fibers and expressed native α‐smooth muscle actin. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Molecular dynamics simulation of hydrated DPPC monolayers using charge equilibration force fields
Authors: Lucas Timothy R. , Bauer Brad A. , Davis Joseph E. , Patel Sandeep 
Published: October 2011

AbstractWe present results of molecular dynamics simulations of a model DPPC‐water monolayer using charge equilibration (CHEQ) force fields, which explicitly account for electronic polarization in a classical treatment of intermolecular interactions. The surface pressure, determined as the difference between the monolayer and pure water surface tensions at 323 K, is predicted to be 22.92 ±1.29dyne/cm, just slightly below the broad range of experimental values reported for this system. The surface tension for the DPPC‐water monolayer is predicted to be 42.35 ±1.16dyne/cm, in close agreement with the experimentally determined value of 40.9 dyne/cm. This surface tension is also consistent with the value obtained from DPPC monolayer simulations using state‐of‐the‐art nonpolarizable force fields. The current results of simulations predict a monolayer‐water potential difference relative to the pure water‐air interface of 0.64 ±0.02 Volts, an improved prediction compared to the fixed‐charge CHARMM27 force field, yet still overestimating the experimental range of 0.3 to 0.45 Volts. As the charge equilibration model is a purely charge‐based model for polarization, the current results suggest that explicitly modeled polarization effects can offer improvements in describing interfacial electrostatics in such systems. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Variable bright‐darkfield‐contrast, a new illumination technique for improved visualizations of complex structured transparent specimens
Authors: Piper Timm , Piper Jörg 
Published: October 2011

AbstractVariable bright‐darkfield contrast (VBDC) is a new technique in light microscopy which promises significant improvements in imaging of transparent colorless specimens especially when characterized by a high regional thickness and a complex three‐dimensional architecture. By a particular light pathway, two brightfield‐ and darkfield‐like partial images are simultaneously superimposed so that the brightfield‐like absorption image based on the principal zeroth order maximum interferes with the darkfield‐like reflection image which is based on the secondary maxima. The background brightness and character of the resulting image can be continuously modulated from a brightfield‐dominated to a darkfield‐dominated appearance. When the weighting of the dark‐ and brightfield components is balanced, medium background brightness will result showing the specimen in a phase‐ or interference contrast‐like manner. Specimens can either be illuminated axially/concentrically or obliquely/eccentrically. In oblique illumination, the angle of incidence and grade of eccentricity can be continuously changed. The condenser aperture diaphragm can be used for improvements of the image quality in the same manner as usual in standard brightfield illumination. By this means, the illumination can be optimally adjusted to the specific properties of the specimen. In VBDC, the image contrast is higher than in normal brightfield illumination, blooming and scattering are lower than in standard darkfield examinations, and any haloing is significantly reduced or absent. Although axial resolution and depth of field are higher than in concurrent standard techniques, the lateral resolution is not visibly reduced. Three dimensional structures, reliefs and fine textures can be perceived in superior clarity. Microsc. Res. Tech. 2011. © 2011 Wiley‐Liss, Inc.
Novel boundary conditions for strain localization analyses in microstructural volume elements
Authors: Coenen E.W.C. , Kouznetsova V.G. , Geers M.G.D. 
Published: October 2011

SUMMARYMulti‐scale modeling frequently relies on microstructural representative volume elements (RVEs) on which macroscopic deformation is imposed through kinematical boundary conditions. A particular choice of these boundary conditions may influence the obtained effective properties. For strain localization and damage analyses, the RVE is pushed beyond the limits of its representative character, and the applied boundary conditions have a significant impact on the onset and the type of macroscopic material instability to be predicted.In this article, we propose a new type of boundary conditions for microstructural volume elements, called percolation‐path‐aligned boundary conditions. Intrinsically, these boundary conditions capture the constraining effect of the material surrounding the RVE upon developing localization bands. The alignment with evolving localization bands allows the highly strained band to cross the RVE and fully develop with minimal interference of the applied boundary conditions. For an illustration of the performance of the newly proposed boundary conditions, macroscopic deformation has been imposed on a voided elasto‐plastic RVE using different types of boundary conditions. It is observed that the new RVE boundary conditions provide a good estimate for the effective stiffness, are not susceptible to spurious localization, and permit the development of a full strain localization band up to failure. Copyright © 2011 John Wiley & Sons, Ltd.
Effect of annealing on the microstructure and mechanical properties of polypropylene with oriented shish‐kebab structure
Authors: Bai Hongwei , Deng Hua , Zhang Qin , Wang Ke , Fu Qiang , Zhang Zhijie , Men Yongfeng 
Published: October 2011

AbstractAnnealing is thought to be an effective method to promote chain rearrangement in semicrystalline polymers and improve their physical properties. However, little attention has been paid to the annealing of flow‐oriented semicrystalline polymers despite its importance in polymer processing. In this work, the microstructural evolution of injection‐moulded polypropylene with an oriented shish‐kebab structure upon annealing has been explored with differential scanning calorimetry, small‐angle X‐ray scattering and scanning electron microscopy, Fourier transform infrared spectroscopy and dynamic mechanical analysis. The results show that annealing gives rise to a chain rearrangement in both the crystalline and amorphous phases. Accompanied by the growth and perfecting of the kebabs, relaxation of the initially oriented chains in the amorphous phase is observed. Then, the relationship between the structure and the resulting mechanical properties is established. Copyright © 2011 Society of Chemical Industry
Rheological properties of homogeneous and heterogeneous poly(2‐hydroxyethyl methacrylate) hydrogels
Authors: Karpushkin Evgeny , Dušková‐Smrčková Miroslava , Remmler Torsten , Lapčíková Monika , Dušek Karel 
Published: October 2011

AbstractThe swelling and rheological behaviour of hydrogels of morphology varying from non‐porous to highly porous was investigated. The hydrogels were prepared by redox free radical copolymerization of 2‐hydroxyethyl methacrylate with 0.1 to 5 mol% of di(ethylene glycol) dimethacrylate in the presence of water varying from 40 to 80 wt%. Various compositions led to clear, turbid or macroporous gels. The morphology of the gels was characterized using optical microscopy and cryoscan electron microscopy. The oscillatory shear and creep of swollen gels revealed that there was a pronounced difference between homogeneous or microheterogeneous and macroporous gels with communicating pores. The achievement of optimum conditions for the correct determination of shear modulus was also analysed. Copyright © 2011 Society of Chemical Industry
Short range correlations of misfit dislocations in the X‐ray diffraction peaks
Authors: Kaganer Vladimir M. , Sabelfeld Karl K. 
Published: October 2011

AbstractThe X‐ray diffraction peak profiles due to misfit dislocations are studied for the dislocations correlated on distances much smaller than the film thickness. Simple analytical expressions for the correlation parameter are obtained when the dislocations are generated as a Markov chain. Monte Carlo calculations show the peak profile evolution as order in the dislocation positions increases.
Exactly solvable schrödinger equation for a class of multiparameter exponential‐type potentials
Authors: García‐Martínez J. , García‐Ravelo J. , Morales J. , Peña J. J. 
Published: October 2011

AbstractThe solution to a spectral problem involving the Schrödinger equation for a particular class of multiparameter exponential‐type potentials is presented. The proposal is based on the canonical transformation method applied to a general second‐order differential equation, multiplied by a functiong(x), to convert it into a Schrödinger‐like equation. The treatment of multiparameter exponential‐type potentials comes from the application of the transformed results to the hypergeometric equation under the assumption of a specificg(x). Besides presenting the explicit solutions and their spectral values, it is shown that the problem considered in this article unifies and generalizes several former studies. That is, the proposed exactly solvable multiparameter exponential‐type potential can be straightforwardly applied to particular exponential potentials depending on the choice of the involved parameters as exemplified for the Hulthén potential and their isospectral partner. Moreover, depending on the functiong(x), the proposal can be extended to find different exactly solvable potentials as well as to generate new potentials that could be useful in quantum chemical calculations. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Structure and reactivity of the mixed‐valence CaMn4O5(H2O)4 and CaMn4O4(OH)(H2O)4 clusters at oxygen evolution complex of photosystem II. Hybrid DFT (UB3LYP and UBHandHLYP) calculations
Authors: Yamanaka S. , Saito T. , Kanda K. , Isobe H. , Umena Y. , Kawakami K. , Shen J.‐R. , Kamiya N. , Okumura M. , Nakamura H. , Yamaguchi K. 
Published: October 2011

AbstractVery recently Umena et al. have determined the X‐ray diffraction (XRD) structure of the CaMn4O5 cluster in the oxygen evolution complex (OEC) of photosystem II (PSII) refined to 1.9 Å resolution. We have performed theoretical attempts to elucidate possible electronic and spin states of their new XRD structure of the CaMn4O5 cluster. For the purpose, hybrid density functional theory (UB3LYP and UBHandHLYP) calculations have been performed for the mixed‐valence (MV) CaMn(III)4‐ω(IV)ωO5(H2O)4 (1) and CaMn(III)4‐ω(IV)ωO4(OH)(H2O)4 (2) clusters as active catalytic site for water splitting reaction in OEC of PSII. Full geometry optimizations of 1a (ω = 2) and 2a (ω = 2) have been performed to elucidate scope and limitation of the cluster models. Both charge and spin fluctuated structures (48 UB3LYP solutions) have been considered for the MV 1a (ω = 2). Total energies obtained by these calculations have elucidated quasi‐degenerated electronic and spin states that are characterized by charge and spin density populations. The energy levels revealed by hybrid DFT are analyzed on the basis of the Heisenberg spin Hamiltonian model, providing the effective exchange integrals between manganese ions at a uniform or MV structure. The spin projections for hybrid DFT solutions are performed using the effective exchange integrals. The charge fluctuation model is introduced to analyze relative stabilities among MV structures of 1a and 2a. These computational results for 1a and 2a have explored several characteristic electronic properties of the species that are used for theoretical elucidation of possible mechanisms of water splitting reaction. Orbital and spin correlation diagrams are derived for the OO bond formation and oxygen evolution in the reaction. Implications of the computational results are also discussed in relation to available experiments and theoretical results by other groups. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
The Exocytosis of Fluorescent Nanodiamond and Its Use as a Long‐Term Cell Tracker
Authors: Fang Chia‐Yi , Vaijayanthimala V. , Cheng Chi‐An , Yeh Shih‐Hua , Chang Ching‐Fang , Li Chung‐Leung , Chang Huan‐Cheng 
Published: October 2011

AbstractFluorescent nanodiamond (FND) has excellent biocompatibility and photostability, making it well suited for long‐term labeling and tracking of cancer and stem cells. To prove the concept, the exocytosis of FND particles (size ≈100 nm) from three cell lines—HeLa cervical cancer cells, 3T3‐L1 pre‐adipocytes, and 489‐2.1 multipotent stromal cells—is studied in detail. FND labeling is performed by incubating the cells in a serum‐free medium containing 80 μg mL−1 FND for 4 h. No significant alteration in growth or proliferation of the FND‐labeled cells, including the multipotent stromal cells, is observed for up to 8 days. Flow cytometric analysis, in combination with parallel cell doubling‐time measurements, indicates that there is little (≈15% or less) excretion of the endocytosed FND particles after 6 days of labeling for both HeLa and 489‐2.1 cells, but exocytosis occurs more readily (up to 30%) for 3T3‐L1 preadipocytes. A comparative experiment with FND and the widely used dye, carboxyfluorescein diacetate succinimidyl ester, demonstrates that the nanoparticle platform is a promising alternate probe for long‐term cell labeling and tracking applications.