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Chen Et Al. (chen + et_al)
Selected AbstractsCommentary on Chen et al. (2009): Gene-environment interactions in nicotine dependenceADDICTION, Issue 10 2009JAAKKO KAPRIO No abstract is available for this article. [source] Differential sensitivity of sodium channels from the central and peripheral nervous system to the scorpion toxins Lqh-2 and Lqh-3EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2002Haijun Chen Abstract The scorpion ,-toxins Lqh-2 and Lqh-3, isolated from the venom of the Israeli yellow scorpion Leiurus quinquestriatus hebraeus, were previously shown to be very potent in removing fast inactivation of rat skeletal muscle sodium channels (Chen et al., 2000). Here, we show that tetrodotoxin-sensitive neuronal channels NaV1.2 and NaV1.7, which are mainly expressed in mammalian central and peripheral nervous systems, respectively, are differentially sensitive to these two toxins. rNaV1.2 and hNaV1.7 channels were studied with patch-clamp methods upon expression in mammalian cells. While Lqh-3 was about 100-times more potent in removing inactivation in hNaV1.7 channels compared with rNaV1.2, Lqh-2 was about 20-times more active in the other direction. Site-directed mutagenesis showed that the differences in the putative binding sites for these toxins, the S3-4 linkers of domain 4, are of major importance for Lqh-3, but not for Lqh-2. [source] Waveguide Sensors: Use of Reversal Nanoimprinting of Nanoparticles to Prepare Flexible Waveguide Sensors Exhibiting Enhanced Scattering of the Surface Plasmon Resonance (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Mater. The image displays a flexible surface plasmon resonance (SPR)-based waveguide sensor prepared by directly imprinting metal nanoparticles onto flexible plates, as presented by H.-L. Chen et al. on page 1742. The metal nanoparticles could scatter the evanescent wave and the guiding mode waves from the SPR-based waveguide simultaneously. The scattering signal underwent a distinguishable red-shift when the target molecules bound to the particles. [source] Dynamic response of soft poroelastic bed to linear water waves,a boundary layer correction approachINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2001Ping-Cheng Hsieh Abstract According to Chen et al. (Journal of Engineering Mechanics, ASCE 1997; 123(10):1041,1049.) a boundary layer exists within the porous bed and near the homogeneous-water/porous-bed interface when oscillatory water waves propagate over a soft poroelastic bed. This boundary layer makes the evaluation of the second kind of longitudinal wave inside the soft poroelastic bed very inaccurate. In this study, the boundary layer correction approach for the poroelastic bed is applied to the boundary value problem of linear oscillatory water waves propagating over a soft poroelastic bed. After the analyses of length scale and order of magnitude of physical variables are done, a perturbation expansion for the boundary layer correction approach based on two small parameters is proposed and solved. The solutions are carried out for the first and third kind of waves throughout the entire domain. The second kind of wave which disappears outside the boundary layer is solved systematically inside the boundary layer. The results are compared with the linear wave solutions of Huang and Song (Journal of Engineering Mechanics, ASCE 1993; 119:1003,1020.) to confirm the validity. Moreover, a simplified boundary layer correction formulation which is expected to be very useful in numerical computation is also proposed. Copyright © 2001 John Wiley & Sons, Ltd. [source] A 3D graphical representation of DNA sequence based on numerical coding methodINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2010Zhi Cao Abstract Recently, we introduced a sort of numerical coding method of DNA sequences (Chen et al., MATCH Commun Math Comput Chem, 2008, 60, 291). On the basis of the result of our coding method, we present a 3D graphical representation of DNA sequences. The 3D graphical representation also avoids loss of information accompanying alternative 2D and 3D representation in which the curve standing for DNA overlaps and intersects itself. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] On the self-weighted alternating trilinear decomposition algorithm,the property of being insensitive to excess factors used in calculationJOURNAL OF CHEMOMETRICS, Issue 5 2001Zeng-Ping Chen Abstract PARAFAC is well known as an iterative trilinear decomposition method. In practice, an accurate estimation of the number of underlying factors is required; otherwise it is difficult to guarantee the chemical meaning of the results obtained. The absence of a versatile chemometric method for factor estimation has often caused problems for analysts. With the advent of ATLD followed by SWATLD, the above relatively strict constraint can be relaxed. Experiments have shown that the profiles of the underlying factors can be extracted by ATLD (Wu et al., J. Chemometrics 1998; 12: 1) and SWATLD (Chen et al., Chemometrics Intell. Lab. Syst. 2000; 52: 75) as long as the number of factors used in calculation is no less than the number of actual factors. In other words, an overestimation of the number of factors will not affect the obtainment of chemically meaningful results by SWATLD and ATLD. In this paper the authors provide some simple mathematical explanations of this valuable property of SWATLD. Along with these explanations, some other properties of SWATLD as well as some guidelines for designing new trilinear decomposition methods are also discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source] A role for the Werner syndrome protein in epigenetic inactivation of the pluripotency factor Oct4AGING CELL, Issue 4 2010Johanna A. Smith Summary Werner syndrome (WS) is an autosomal recessive disorder, the hallmarks of which are premature aging and early onset of neoplastic diseases (Orren, 2006; Bohr, 2008). The gene, whose mutation underlies the WS phenotype, is called WRN. The protein encoded by the WRN gene, WRNp, has DNA helicase activity (Gray et al., 1997; Orren, 2006; Bohr, 2008; Opresko, 2008). Extensive evidence suggests that WRNp plays a role in DNA replication and DNA repair (Chen et al., 2003; Hickson, 2003; Orren, 2006; Turaga et al., 2007; Bohr, 2008). However, WRNp function is not yet fully understood. In this study, we show that WRNp is involved in de novo DNA methylation of the promoter of the Oct4 gene, which encodes a crucial stem cell transcription factor. We demonstrate that WRNp localizes to the Oct4 promoter during retinoic acid-induced differentiation of human pluripotent cells and associates with the de novo methyltransferase Dnmt3b in the chromatin of differentiating pluripotent cells. Depletion of WRNp does not affect demethylation of lysine 4 of the histone H3 at the Oct4 promoter, nor methylation of lysine 9 of H3, but it blocks the recruitment of Dnmt3b to the promoter and results in the reduced methylation of CpG sites within the Oct4 promoter. The lack of DNA methylation was associated with continued, albeit greatly reduced, Oct4 expression in WRN-deficient, retinoic acid-treated cells, which resulted in attenuated differentiation. The presented results reveal a novel function of WRNp and demonstrate that WRNp controls a key step in pluripotent stem cell differentiation. [source] Integrated estimation of measurement error with empirical process modeling,A hierarchical Bayes approachAICHE JOURNAL, Issue 11 2009Hongshu Chen Abstract Advanced empirical process modeling methods such as those used for process monitoring and data reconciliation rely on information about the nature of noise in the measured variables. Because this likelihood information is often unavailable for many practical problems, approaches based on repeated measurements or process constraints have been developed for their estimation. Such approaches are limited by data availability and often lack theoretical rigor. In this article, a novel Bayesian approach is proposed to tackle this problem. Uncertainty about the error variances is incorporated in the Bayesian framework by setting noninformative priors for the noise variances. This general strategy is used to modify the Sampling-based Bayesian Latent Variable Regression (Chen et al., J Chemom., 2007) approach, to make it more robust to inaccurate information about the likelihood functions. Different noninformative priors for the noise variables are discussed and unified in this work. The benefits of this new approach are illustrated via several case studies. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Mitogen-activated protein kinase pathway mediates N -(4-hydroxyphenyl)retinamide-induced neuronal differentiation in the ARPE-19 human retinal pigment epithelial cell lineJOURNAL OF NEUROCHEMISTRY, Issue 2 2008William Samuel Abstract We have shown previously that N -(4-hydroxyphenyl)retinamide (4HPR, fenretinide), a retinoic acid derivative, induces neuronal differentiation in cultured human retinal pigment epithelial (RPE) cells [Chen et al., J. Neurochem., 84 (2003), 972]. We asked the question whether the mitogen-activated protein kinase (MAPK) pathway is involved in the regulation of the 4HPR-induced neuronal differentiation of RPE (ARPE-19) cells. When we treated ARPE-19 cells with 4HPR, c-Raf and MEK1/2 kinase were activated resulting in activation of the downstream effector ERK1/2 and of SAPK/JNK. By blocking the upstream kinase MEK1/2 with specific inhibitor U0126 we abrogated the 4HPR-induced phosphorylation of ERK1/2 and SAPK/JNK, indicating that the neuronal differentiation occurs through a positive cross-talk between the ERK and the SAPK/JNK pathways. Both U0126 and the suppression of ERK1/2 expression with small interfering RNA effectively blocked the 4HPR-induced neuronal differentiation of RPE cells and the expression of calretinin. The activated ERK1/2 then induced a sequential activation of p90RSK, and increase in phosphorylation of transcription factors c- fos and c- jun leading to transcriptional activation of AP-1. Taken together, our results clearly demonstrate that c-Raf/MEK1/2 signaling cascade involving ERK1/2 plays a central role in mediating the 4HPR-induced neuronal differentiation and calretinin expression in the human ARPE-19 retinal pigment epithelial cell line. [source] Editorial regarding use of modified femoral vein approach as method for implanting a totally implantable access port in patients with synchrounous bilateral mastectomes (Chen et al.)JOURNAL OF SURGICAL ONCOLOGY, Issue 3 2008Harold J. Wanebo MD No abstract is available for this article. [source] Homes for the orphans: utilization of multiple substrate-binding proteins by ABC transportersMOLECULAR MICROBIOLOGY, Issue 1 2010Gavin H. Thomas Summary Acquiring nutrients from the environment is essential for all microbes, and the ATP-binding cassette (ABC) transporters are one of the major routes by which bacteria achieve it. In this issue of Molecular Microbiology, Chen et al. describe their characterization of what appeared at first glance a simple ABC transporter for acquisition of quaternary ammonium compounds (QACs) in Pseudomonas sp., but their persistence in fully determining the properties of this system led to the experimental demonstration that QAC uptake utilizes three different substrate-binding proteins (SBPs), two of which are encoded at remote locations on the genome as ,orphan' SBPs that are each able to function with a single core ABC transporter. Building on the unusual nature of this system, in which multiple SBPs with non-overlapping substrate specificities compete for the same transporter binding site, they designed elegant in vivo experiments that suggest that only substrate-bound SBPs are able to form functional complexes with the membrane domains. This new finding provides an important piece of in vivo data leading to further insight into how this ubiquitous family of transporters operates. [source] | ||||||||||||||||