bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibitors of the α‐ketoglutarate dehydrogenase complex alter [1‐13C]glucose and [U‐13C]glutamate metabolism in cerebellar granule neurons
Authors: Santos Sónia Sá , Gibson Gary E. , Cooper Arthur J.L. , Denton Travis T. , Thompson Charles M. , Bunik Victoria I. , Alves Paula M. , Sonnewald Ursula 
Published: January 2006

AbstractDiminished activity of the α‐ketoglutarate dehydrogenase complex (KGDHC), an important component of the tricarboxylic acid (TCA) cycle, occurs in several neurological diseases. The effect of specific KGDHC inhibitors [phosphonoethyl ester of succinyl phosphonate (PESP) and the carboxy ethyl ester of succinyl phosphonate (CESP)] on [1‐13C]glucose and [U‐13C]glutamate metabolism in intact cerebellar granule neurons was investigated. Both inhibitors decreased formation of [4‐13C]glutamate from [1‐13C]glucose, a reduction in label in glutamate derived from [1‐13C]glucose/[U‐13C]glutamate through a second turn of the TCA cycle and a decline in the amounts of γ‐aminobutyric acid (GABA), aspartate, and alanine. PESP decreased formation of [U‐13C]aspartate and total glutathione, whereas CESP decreased concentrations of valine and leucine. The findings are consistent with decreased KGDHC activity; increased α‐ketoglutarate formation; increased transamination of α‐ketoglutarate with valine, leucine, and GABA; and new equilibrium position of the aspartate aminotransferase reaction. Overall, the findings also suggest that some carbon derived from α‐ketoglutarate may bypass the block in the TCA cycle at KGDHC by means of the GABA shunt and/or conversion of valine to succinate. The results suggest the potential of succinyl phosphonate esters for modeling the biochemical and pathophysiological consequences of reduced KGDHC activity in brain diseases. © 2006 Wiley‐Liss, Inc.
Optimization of chronic stress paradigms using anxiety‐ and depression‐like behavioral parameters
Authors: Kim Kyoung‐Shim , Han Pyung‐Lim 
Published: January 2006

AbstractChronic stress is a risk factor for psychiatric illnesses, such as anxiety and depression disorders. To understand the underlying mechanism regarding how chronic stress triggers such psychiatric dysfunctions, restraint‐based chronic stress models have been attempted in the past. However, total durations of repeated restraint stress and the evaluation time points used after the last restraint application vary from experiment to experiment. One reason for these methodological heterogeneities is related to considerable ambiguity concerning the definition of chronic stress, particularly in animal models. In the present study, we used behavioral traits, anxiety and depression, as stress‐assessment parameters that meet operationally useful requirements for the definition of the chronic stress state. We demonstrate that restraint treatment for 2 or 8 hr daily for 14 days is enough to produce anxiety‐ and depression‐like behaviors, whereas a 2 hr‐10 days restraint was marginally effective. cDNA microarray analysis identified 34 genes in the hippocampus and 72 genes in the amygdala with expression levels that were up‐ or down‐regulated by >2.0‐fold. Among the wide range of genes identified in this analysis, genes required for energy metabolism, signal transduction, transcription, synaptic plasticity, and remodeling of the brain architecture were notable. Our results suggest that the psychiatric criteria of anxiety and depression can be used as chronic stress‐assessment parameters and that a restraint stress paradigm consisting of restraint treatment for 2 or 8 hr daily for 14 days could be used as a prototype paradigm for chronic stress studies. © 2006 Wiley‐Liss, Inc.
Pigment identification of colored drawings from Wuying Hall of the Imperial Palace by micro‐Raman spectroscopy and energy dispersive X‐ray spectroscopy
Authors: Shen Ai Guo , Wang Xiao Hua , Xie Wei , Shen Jing , Li Hua Yuan , Liu Zhen An , Hu Ji Ming 
Published: January 2006

AbstractFour ancient colored drawings (CDs), namely in black, blue, white and green, of Wuying Hall in the Imperial Palace, China, were analyzed by micro‐Raman spectroscopy (MRS) in combination with energy dispersive X‐ray spectroscopy (EDX) in order to identify the pigments in each case. The pigments lampblack (a pigment based on amorphous carbon), ultramarine blue/lapis lazuli (Na8[Al6Si6O24]Sn), dolomite (CaMg(CO3)2), emerald green (Cu(C2H3O2)2·3Cu(AsO2)2), gypsum (CaSO4·2H2O) were detected in the CDs, and these will be useful with regard to the restoration of the paintings at Wuying Hall. Furthermore, it is important to take into account the dating of some rare pigments, i.e., ultramarine blue and emerald green, in order to validate that there was a fire that destroyed more than 30 houses of Wuying Hall in 1869 (Tong‐Zhi, 8th year of Qing Dynasty). The results demonstrate that micro‐Raman spectroscopy can provide valuable information for the characterization, restoration and preservation of the cultural relic. Copyright © 2006 John Wiley & Sons, Ltd.
Dependence of the Raman spectra of drug substances upon laser excitation wavelength
Authors: Thorley Fiona C. , Baldwin Kurt J. , Lee David C. , Batchelder David N. 
Published: January 2006

AbstractThe laser excitation wavelength is an important parameter in obtaining definitive Raman spectra from pharmaceutical drug substances. This paper investigates the effect of changing wavelength on the Raman spectra of four different drug substances: paracetamol, paroxetine and ranitidine (polymorphic forms I and II). Excitation wavelengths in the range 244 nm to 785 nm have been used. The fluorescence intensities in the Raman spectra were found to be negligible at the two extreme laser wavelengths but tended to interfere in the visible range. Resonance Raman enhancement was observed with 244 nm excitation but there was evidence for sample degradation. Furthermore, the site selective nature of the resonance enhancement reduced the differences between the Raman spectra of the two ranitidine polymorphs. Copyright © 2006 John Wiley & Sons, Ltd.
Vibrational and EPR spectroscopic investigation of heavy‐metal‐oxide glasses and vitroceramics containing manganese
Authors: Simon S. , Baia L. , Radu A. 
Published: January 2006

AbstractHeavy‐metal‐oxide (HMO) glasses and vitroceramics of [3Bi2O3·2PbO] and 20MnO·80[3Bi2O3·2PbO] compositions were investigated by Raman, infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies. Changes in the local structure of the heavy‐metal host glass induced by manganese addition, and those determined by partial crystallisation of samples are seen.Raman and IR spectroscopies have been employed in order to obtain information on the role of Bi2O3 and PbO in the local structure of the investigated samples and on the effect of MnO on the bismuth and lead environments. EPR results have evidenced the influence of the vitreous 3Bi2O3·2PbO network on Mn2+ ions' environment and the changes in structural relaxation and magnetic interactions caused by sample crystallisation. Copyright © 2006 John Wiley & Sons, Ltd.
Critical Conditions and Limiting Conditions in Liquid Chromatography of Synthetic Polymers
Authors: Berek Dušan 
Published: January 2006

AbstractDistinctions between liquid chromatography of synthetic polymers under critical conditions (LC CC) and liquid chromatography under limiting conditions (LC LC) are elucidated. Surface adsorption retention mechanism of macromolecules is employed in the chromatographic systems composed of 10 and 30 nm pore diameter bare silica gels, poly (methyl methacrylate)s of different molar masses, and mixed eluents acetonitrile/dichloromethane of different compositions, and at different temperatures. Increased robustness of the LC LC methods compared to LC CC is confirmed: the LC LC elution behavior is much less sensitive to eluent composition changes compared to LC CC. Still, the LC CC system under study is, surprisingly robust in terms of temperature variations. LC LC methods produce narrow, focused polymer peaks while a peak broadening is observed in LC CC. The results demonstrate importance of sample solvent applied in the isocratic coupled polymer HPLC methods.
Painless legs moving toes in a patient with Wilson's disease
Authors: Papapetropoulos Spiridon , Singer Carlos 
Published: January 2006

AbstractWe describe and present a video of a 20‐year‐old woman with Wilson's disease (WD) who developed the painless variant of painful legs and moving toes (PLMT) syndrome. The symptoms appeared during a subsequent minor exacerbation of her extrapyramidal symptomatology, only to gradually disappear 3 to 4 months later. We suggest that, in our case, a structural central nervous system lesion caused by WD may have been associated with the development of PLMT. © 2006 Movement Disorder Society
In vivo detection of single cells by MRI
Authors: Shapiro Erik M. , Sharer Kathryn , Skrtic Stanko , Koretsky Alan P. 
Published: January 2006

AbstractThe use of high‐relaxivity, intracellular contrast agents has enabled MRI monitoring of cell migration through and homing to various tissues, such as brain, spinal cord, heart, and muscle. Here it is shown that MRI can detect single cells in vivo, homing to tissue, following cell labeling and transplantation. Primary mouse hepatocytes were double‐labeled with green fluorescent 1.63‐μm iron oxide particles and red fluorescent endosomal labeling dye, and injected into the spleens of recipient mice. This is a common hepatocyte transplantation paradigm in rodents whereby hepatocytes migrate from the spleen to the liver as single cells. One month later the animals underwent in vivo MRI and punctuated, dark contrast regions were detected scattered through the livers. MRI of perfused, fixed samples and labeled hepatocyte phantoms in combination with histological evaluation confirmed the presence of dispersed single hepatocytes grafted into the livers. Appropriate controls were used to determine whether the observed contrast could have been due to dead cells or free particles, and the results confirmed that the contrast was due to disperse, single cells. Detecting single cells in vivo opens the door to a number of experiments, such as monitoring rare cellular events, assessing the kinetics of stem cell homing, and achieving early detection of metastases. Magn Reson Med, 2006. Published 2006 Wiley‐Liss, Inc.
Influence of SENSE on image properties in high‐resolution single‐shot echo‐planar DTI
Authors: Jaermann T. , Pruessmann K.P. , Valavanis A. , Kollias S. , Boesiger P. 
Published: January 2006

AbstractLimited spatial resolution is a key obstacle to the study of brain white matter structure with diffusion tensor imaging (DTI). In its frequent implementation with single‐excitation spin‐echo echo‐planar sequences, DTI's ability to resolve small structures is strongly restricted by T2 and T decay, B0 inhomogeneity, and limited signal‐to‐noise ratio (SNR). In this work the influence of sensitivity encoding (SENSE) on diffusion‐weighted (DW) image properties is investigated. Computer simulations showed that the PSF becomes narrower with increasing SENSE reduction factors, R, enhancing the intrinsic resolution. After a brief theoretical discussion, we describe the estimation of SNR on a pixel‐by‐pixel basis as a function of R. The mean image SNR behavior is manifold: SENSE is capable of increasing SNR efficiency by reducing the echo time (TE). Each SNR(R) curve reveals a maximum that depends on the amount of partial Fourier encoding used. The overall best SNR efficiency for an eight‐element head coil array and a b‐factor of 1000 s/mm2 is achieved at R = 2.1 and partial Fourier encoding of 60%. In vivo tensor maps of volunteers and a patient, with an in‐plane resolution of 0.78 × 0.78 mm2, are also presented to demonstrate the practical implementation of the parallel approach. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
2D axial moving table acquisitions with dynamic slice adaptation
Authors: Ludwig Ute , Sommer Gregor , Zaitsev Maxim , Ghanem Nadir , Hennig Jürgen , Fautz Hans‐Peter 
Published: January 2006

AbstractA method for axial multi‐slice imaging during continuous table motion has been developed and implemented on a clinical scanner. Multiple axial slice packages are acquired consecutively and combined to cover an extended longitudinal FOV. To account for the table motion during the acquisition, the RF pulse frequencies are continuously updated according to the actual table velocity and slice position. Different strategies for the spatial‐temporal acquisition sequence with extended FOV are proposed. They cover different regimes of scan requirements regarding table velocity, used scan range, and slice resolution. The method is easy to implement and compatible with most kinds of sequences. The robustness of the proposed approach has been tested in phantom studies and healthy volunteers using T1‐, T2‐, and STIR‐weighted multi‐slice techniques that are based on gradient and turbo spin echo sequences and compared to a stationary approach usually used in clinical routine. The method provides artifact free gradient echo based images during continuous table motion, while for turbo spin echo sequences limitations in choosing table translations occur due to gradient non‐linearity effects. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Model‐free arterial spin labeling quantification approach for perfusion MRI
Authors: Petersen Esben Thade , Lim Tchoyoson , Golay Xavier 
Published: January 2006

AbstractIn this work a model‐free arterial spin labeling (ASL) quantification approach for measuring cerebral blood flow (CBF) and arterial blood volume (aBV) is proposed. The method is based on the acquisition of a train of multiple images following the labeling scheme. Perfusion is obtained using deconvolution in a manner similar to that of dynamic susceptibility contrast (DSC) MRI. Local arterial input functions (AIFs) can be estimated by subtracting two perfusion‐weighted images acquired with and without crusher gradients, respectively. Furthermore, by knowing the duration of the bolus of tagged arterial blood, one can estimate the aBV on a voxel‐by‐voxel basis. The maximum of the residue function obtained from the deconvolution of the tissue curve by the AIF is a measure of CBF after scaling by the locally estimated aBV. This method provides averaged gray matter (GM) perfusion values of 38 ± 2 ml/min/100 g and aBV of 0.93% ± 0.06%. The average CBF value is 10% smaller than that obtained on the same data set using the standard general kinetic model (42 ± 2 ml/min/100 g). Monte Carlo simulations were performed to compare this new methodology with parametric fitting by the conventional model. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Balanced alternating steady‐state elastography
Authors: Bieri O. , Maderwald S. , Ladd M.E. , Scheffler K. 
Published: January 2006

AbstractA conventional balanced steady‐state free precession (b‐SSFP) sequence scheme was modified such that the dynamic equilibrium becomes very sensitive to small cyclic displacements, generating two distinct and alternating steady states. This novel technique is proposed for the visualization of propagating transverse acoustic shear waves, as used in MR elastography (MRE) to determine the mechanical properties of materials or in vivo soft tissue. Experiments with tissue‐like agarose gel phantoms and simulations demonstrate that the novel sequence offers an increase in phase sensitivity by about one order in magnitude compared to standard motion‐encoding methods. In addition, the new method benefits from the very short acquisition times achieved by b‐SSFP protocols. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Quantification of prostate MRSI data by model‐based time domain fitting and frequency domain analysis
Authors: Pels Pieter , Ozturk‐Isik Esin , Swanson Mark G. , Vanhamme Leentje , Kurhanewicz John , Nelson Sarah J. , Huffel Sabine Van 
Published: January 2006

AbstractThis paper compares two spectral processing methods for obtaining quantitative measures from in vivo prostate spectra, evaluates their effectiveness, and discusses the necessary modifications for accurate results. A frequency domain analysis (FDA) method based on peak integration was compared with a time domain fitting (TDF) method, a model‐based nonlinear least squares fitting algorithm. The accuracy of both methods at estimating the choline + creatine + polyamines to citrate ratio (CCP:C) was tested using Monte Carlo simulations, empirical phantom MRSI data and in vivo MRSI data. The paper discusses the different approaches employed to achieve the quantification of the overlapping choline, creatine and polyamine resonances. Monte Carlo simulations showed induced biases on the estimated CCP:C ratios. Both methods were successful in identifying tumor tissue, provided that the CCP:C ratio was greater than a given (normal) threshold. Both methods predicted the same voxel condition in 94% of the in vivo voxels (68 out of 72). Both TDF and FDA methods had the ability to identify malignant voxels in an artifact‐free case study using the estimated CCP:C ratio. Comparing the ratios estimated by the TDF and the FDA, the methods predicted the same spectrum type in 17 out of 18 voxels of the in vivo case study (94.4%). Copyright © 2006 John Wiley & Sons, Ltd.
Shape optimization of flow guides in three‐dimensional extrusion processes by an approximation scheme based on state variable linearization
Authors: Lee S. R. , Yang D. Y. 
Published: January 2006

AbstractA new scheme of shape optimization is applied to the design of a flow guide in flat‐die extrusion processes. In general, tremendous time is inevitably required for the optimization of large‐scale three‐dimensional extrusion processes. This is because the finite element analysis requires large computation time owing to the complexity of the die geometry and flow behaviour. The proposed scheme effectively reduces the computation time for the optimization process by approximating the objective function. This is achieved by introducing a transformed equation of the state variables. The scheme is then applied to the practical extrusion processes to produce ‘l’, ‘H’ and ‘L’ sections. The objective of the optimization is to make a balanced flow of the material in the exit region. Control points of a Bezier curve describing the outline of the flow guide are regarded as the design variables. Through application to large‐scale problems, the effectiveness and usefulness of the proposed scheme is demonstrated. Copyright © 2005 John Wiley & Sons, Ltd.
Derivation of 3D masonry properties using numerical homogenization technique
Authors: Wu Chengqing , Hao Hong 
Published: January 2006

AbstractLots of research work has been conducted on homogenization technique, which derives global homogenized properties of masonry from the behaviour of the constitutive materials (brick and mortar). Such a technique mainly focused on two‐dimensional media in the previous studies with the out‐of‐plane properties of masonry material neglected. In this paper, homogenization technique and damage mechanics theory are used to model a three‐dimensional masonry basic cell to numerically derive the equivalent elastic properties, strength envelope, and failure characteristics of masonry material. The basic cell is modelled with distinctive consideration of non‐linear material properties of mortar and brick. Various displacement boundaries are applied on the basic cell surfaces in the numerical simulation. The detailed material properties of mortar and brick are modelled in a finite element program in the numerical analysis. The stress–strain relations of masonry material under various conditions are obtained from the simulation. The homogenized elastic properties and failure characteristics of masonry material are derived from the simulation results. The homogenized 3D model is then utilized to analyse the response of a masonry panel to airblast loads. The same panel is also analysed with distinctive material modelling. The efficiency and accuracy of the homogenized model are demonstrated. The homogenized material properties and failure model can be used to model large‐scale masonry structure response. Copyright © 2006 John Wiley & Sons, Ltd.
Algorithms by design with illustrations to solid and structural mechanics/dynamics
Authors: Zhou X. , Tamma K. K. 
Published: January 2006

AbstractA novel procedure, concepts, and new ideas to tailor and design time operators under the notion of algorithms by design is formulated in this exposition with emphasis on applications to the broad area of computational mechanics, but with focus on solid and structural mechanics/dynamics as an illustration. The algorithms by design concepts capitalize upon: (i) the recently developed unified theory underlying computational algorithms (Int. J. Numer. Meth. Engng 2004; 59:597–668), and (ii) newly established design spaces and algorithmic measures for evaluating the quality of computational algorithms (Int. J. Numer. Meth. Engng 2005; 64:1841–1870). As a step in the forward direction, in this exposition we embark upon some challenging tasks with the objective to advance, tailor, and foster the design of computational algorithms for time‐dependent problems with desired and/or improved algorithmic attributes in the sense of accuracy, stability and other characteristics including algorithmic complexity in a well educated manner. The design process for computational algorithms is explained in the sense of the algorithms by design concepts via selected numerical illustrations of practical scenarios encountered in solid and structural mechanics/dynamics applications. Copyright © 2006 John Wiley & Sons, Ltd.
Discrete crack modelling of ductile fracture driven by non‐local softening plasticity
Authors: Mediavilla J. , Peerlings R. H. J. , Geers M. G. D. 
Published: January 2006

AbstractA combined approach towards ductile damage and fracture is presented, in the sense that a continuous material degradation is coupled with a discrete crack description for large deformations. Material degradation is modelled by a gradient enhanced damage‐hyperelastoplasticity model. It is assumed that failure occurs solely due to plastic straining, which is particularly relevant for shear dominated problems, where the effect of the hydrostatic stress in triggering failure is less important. The gradient enhancement eliminates pathological localization effects which would normally result from the damage influence. Discrete cracks appear in the final stage of local material failure, when the damage has become critical. The rate and the direction of crack propagation depend on the evolution of the damage field variable, which in turn depends on the type of loading. In a large strain finite element framework, remeshing allows to incorporate the changing crack geometry and prevents severe element distortion. Attention is focused on the robustness of the computations, where the transfer of variables, which is needed after each remeshing, plays a crucial role. Numerical examples are shown and comparisons are made with published experimental results. Copyright © 2005 John Wiley & Sons, Ltd.