bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alkylation of complementary ribonucleotides by 1,2‐dodecyl‐epoxide in a micellar environment: a liquid chromatography—electrospray ionization—sequential mass spectrometry investigation
Authors: Losito I. , Angelico R. , Ceglie A. , Diomede S. , Palmisano F. 
Published: April 2009

AbstractAlkylation of a pair of complementary ribonucleotides, adenosine monophosphate (AMP) and uridine monophosphate (UMP), was accomplished by 1,2‐dodecyl‐epoxide (DE) in a oil‐in‐water microemulsion based on the cationic surfactant Cetyl‐trimethyl‐ammonium‐bromide, providing a suitable catalytic interface for the reagents. Several, often isomeric, alkylation products, bearing one or two hydroxy–dodecyl moieties on their structures, were identified in the reaction mixtures by high‐performance liquid chromatography coupled to electrospray ionization ion trap mass spectrometry. In particular, mass spectrometry (MS)/MS spectra, implemented by extracted ion chromatograms obtained for peculiar MS/MS product ions, indicated alkylation to occur on uracil and on uracil/phosphate OH groups in singly and doubly alkylated UMP, respectively. Adenine NH2 group and phosphate or ribose OH groups were found to be involved as such (single alkylation) or in combination, in the case of alkylated derivatives of AMP. The reaction of both endocyclic N and CO groups (tautomerized to COH groups) of uracil and the predominance of nucleophilic attack to the more accessible carbon of the DE epoxydic bridge (the only exception being the reaction by the NH2 group of adenine) were inferred from MS3 spectra with the help of extracted ion chromatograms for specific fragment ions, after their structural characterization. Interestingly, alkylation on one of the uracil CO groups and, partially, on the adenine NH2 group, both potentially involved in AMP/UMP base pairing in the micellar environment, were found to be hindered when both ribonucleotides were present in the reaction mixtures. Copyright © 2009 John Wiley & Sons, Ltd.
Pulsating fluid flow modulates gene expression of proteins involved in Wnt signaling pathways in osteocytes
Authors: Santos Ana , Bakker Astrid D. , Zandieh‐Doulabi Behrouz , Semeins Cornelis M. , Klein‐Nulend Jenneke 
Published: April 2009

AbstractStrain‐derived flow of interstitial fluid activates signal transduction pathways in osteocytes that regulate bone mechanical adaptation. Wnts are involved in this process, but whether mechanical loading modulates Wnt signaling in osteocytes is unclear. We assessed whether mechanical stimulation by pulsating fluid flow (PFF) leads to functional Wnt production, and whether nitric oxide (NO) is important for activation of the canonical Wnt signaling pathway in MLO‐Y4 osteocytes. MC3T3‐E1 osteoblasts were studied as a positive control for the MLO‐Y4 osteocyte response to mechanical loading. MLO‐Y4 osteocytes and MC3T3‐E1 osteoblasts were submitted to 1‐h PFF (0.7 ± 0.3 Pa, 5 Hz), and postincubated (PI) without PFF for 0.5–3 h. Gene expression of proteins related to the Wnt canonical and noncanonical pathways were studied using real‐time polymerase chain reaction (PCR). In MLO‐Y4 osteocytes, PFF upregulated gene expression of Wnt3a, c‐jun, connexin 43, and CD44 at 1–3‐h PI. In MC3T3‐E1 osteoblasts, PFF downregulated gene expression of Wnt5a and c‐jun at 0.5–3‐h PI. In MLO‐Y4 osteocytes, gene expression of PFF‐induced Wnt target genes was suppressed by the Wnt antagonist sFRP4, suggesting that loading activates the Wnt canonical pathway through functional Wnt production. The NO inhibitor L‐NAME suppressed the effect of PFF on gene expression of Wnt target genes, suggesting that NO might play a role in PFF‐induced Wnt production. The response to PFF differed in MC3T3‐E1 osteoblasts. Because Wnt signaling is important for bone mass regulation, osteocytes might orchestrate loading‐induced bone remodeling through, among others, Wnts. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1280–1287, 2009
The role of small‐scale fold and fault development in seismogenic zones: example of the western Huércal‐Overa Basin (eastern Betic Cordillera, Spain)
Authors: Pedrera Antonio , Galindo‐Zaldívar Jesús , Ruiz‐Bustos Antonio , Rodríguez‐Fernández José , Ruiz‐Constán Ana 
Published: April 2009

AbstractThe NW–SE shortening between the African and the Eurasian plates is accommodated in the eastern Betic Cordillera along a broad area that includes large N‐vergent folds and kilometric NE–SW sinistral faults with related seismicity. We have selected the best exposed small‐scale tectonic structures located in the western Huércal‐Overa Basin (Betic Cordillera) to discuss the seismotectonic implications of such structures usually developed in seismogenic zones. Subvertical ESE–WNW pure dextral faults and E–W to ENE–ESW dextral‐reverse faults and folds deform the Quaternary sediments. The La Molata structure is the most impressive example, including dextral ESE–WNW Neogene faults, active southward‐dipping reverse faults and associated ENE–WSW folds. A molar M1 assigned to Mimomys savini allows for precise dating of the folded sediments (0.95–0.83 Ma). Strain rates calculated across this structure give ∼0.006 mm a−1 horizontal shortening from the Middle Pleistocene up until now. The widespread active deformations on small‐scale structures contribute to elastic energy dissipation around the large seismogenic zones of the eastern Betics, decreasing the seismic hazard of major fault zones. Copyright © 2009 John Wiley & Sons, Ltd.
Assessing the economic value of a public birdwatching interpretative service using a contingent valuation method
Authors: Lee Choong‐Ki , Lee Jin‐Hyung , Mjelde James W. , Scott David , Kim Tae‐Kyun 
Published: April 2009

AbstractAlthough resource interpretative services are an essential conservation management tool that can add value to ecotourism experiences, there has been little empirical investigation on the ‘true’ economic value of such services. As such, this study's objective is to estimate the economic value of public interpretative services at a publicly supported Korean birdwatching festival, using a dichotomous choice contingent valuation method. Logit estimation results indicate that bid, age, income and birdwatching experience are important factors in explaining willingness‐to‐pay for interpretative services. The mean value of the publicly supported interpretative services is estimated to be 4,961 South Korean Won (approximately US$5) per person. Copyright © 2009 John Wiley & Sons, Ltd.
Structures, energetics, and dynamics of gas phase ions studied by FTICR and HPMS
Authors: Wu Ronghu , McMahon Terry B. 
Published: April 2009

AbstractBoth Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS) and high‐pressure mass spectrometry (HPMS) are very powerful tools in the field of gas phase ion chemistry. Many experimental method developments based on FTICR‐MS and HPMS are summarized, including the coupling of a high‐pressure external ion source to a FTICR mass spectrometer, blackbody infrared radiative dissociation (BIRD), coupling laser desorption ionization with HPMS, infrared multiple photon dissociation (IRMPD), radiative association and bimolecular routes to gas phase cluster ion formation. An abundance of thermochemical data, such as proton affinities, gas phase acidities, methyl cation affinities and metal cation affinities, have been obtained. Some of these data are the basis of the standard data listed in the NIST thermochemical databases. Ion–molecule interactions, energetics, reactivities, and structures of molecules have been extensively investigated using the methods developed based on HPMS and FTICR mass spectrometric techniques. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:546–585, 2009
A clinic‐based screening of mutations in exons 31, 34, 35, 41, and 48 of LRRK2 in Iranian Parkinson's disease patients
Authors: Shojaee Seyedmehdi , Sina Farzad , Farboodi Niloofar , Fazlali Zeinab , Ghazavi Farzaneh , Ghorashi Seyed Ali , Parsa Khosro , Sadeghi Homa , Shahidi Gholam‐Ali , Ronaghi Mostafa , Elahi Elahe 
Published: April 2009

AbstractWe present results of mutation screening of exons 31, 34, 35, 41, and 48 of LRRK2 in 205 Iranian Parkinson's disease patients. Sixteen percent of the cases were familial. Although age was not a factor in patient recruitment, the Iranian cohort was relatively young (average age at onset of disease: 48.9 years). A notably high male to female ratio (2.96:1) and earlier age at onset (by 2.9 years) in men were observed. A known disease‐associated variation, c.C4321T causing R1441C, and IVS31 + 3A > G, a variation that may be associated, were observed. Therefore, disregarding IVS31 + 3A > G, disease status in at least 0.5% of our young cohort and in 3.5% of the familial cases was associated with a mutation in the five exons of LRRK2 screened. Interestingly, the variation causing p.G2019S was not observed. © 2009 Movement Disorder Society
Cognitive impairment in Parkinson's disease: Tools for diagnosis and assessment
Authors: Kulisevsky Jaime , Pagonabarraga Javier 
Published: April 2009

AbstractCognitive impairment (CI) and dementia are frequent and debilitating features associated with Parkinson's disease (PD). Formal neuropsychological examination is required to ascertain the degree and pattern of CI over the course of the disease. The use of different tools may explain heterogeneous data obtained from studies to date. Normative data for extensively used scales [Mattis Dementia Rating Scale (MDRS), Mini‐Mental State Examination (MMSE)] is incomplete in PD populations. According to sample characteristics, statistical analyses, and methodological quality, 33 studies using scales not specific to PD (MDRS, MMSE, Cambridge Cognitive Assessment, FAB) or PD‐specific scales (Mini‐Mental Parkinson, Scales for Outcomes of Parkinson's disease—Cognition, Parkinson's Disease—Cognitive Rating Scale, and Parkinson Neuropsychometric Dementia Assessment) were eligible for the critical analysis of their appropriateness to assess cognition in PD. Of the four scales specifically designed for PD, the SCOPA‐COG and the PD‐CRS have undergone extensive and rigorous validation processes. While the SCOPA‐COG mainly assesses “frontal‐subcortical” cognitive defects, the PD‐CRS also assesses “instrumental‐cortical” functions, allowing better characterization of the different patterns of CI that may be present in PD from the earliest stages. The MMP and PANDA scales were designed as brief screening tests for CI and have not yet been subjected to extensive clinimetric evaluations. Further research on PD‐specific tools seems mandatory to help establish accurate cut‐off scores for the diagnosis of mild PDD, detect cognitive profiles more prone to the future development of dementia, and allow comparisons between different descriptive or interventional studies. © 2009 Movement Disorder Society
Estimation of k‐space trajectories in spiral MRI
Authors: Tan Hao , Meyer Craig H. 
Published: April 2009

AbstractFor non‐Cartesian data acquisition in MRI, k‐space trajectory infidelity due to eddy current effects and other hardware imperfections will blur and distort the reconstructed images. Even with the shielded gradients and eddy current compensation techniques of current scanners, the deviation between the actual k‐space trajectory and the requested trajectory remains a major reason for image artifacts in non‐Cartesian MRI. It is often not practical to measure the k‐space trajectory for each imaging slice. It has been reported that better image quality is achieved in radial scanning by correcting anisotropic delays on different physical gradient axes. In this article the delay model is applied in spiral k‐space trajectory estimation to reduce image artifacts. Then a novel estimation method combining the anisotropic delay model and a simple convolution eddy current model further reduces the artifact level in spiral image reconstruction. The root mean square error and peak error in both phantom and in vivo images reconstructed using the estimated trajectories are reduced substantially compared to the results achieved by only tuning delays. After a one‐time calibration, it is thus possible to get an accurate estimate of the spiral trajectory and a high‐quality image reconstruction for an arbitrary scan plane. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
B interferometry for the calibration of RF transmitter arrays
Authors: Brunner David O. , Pruessmann Klaas P. 
Published: April 2009

AbstractMultiple‐channel RF transmission holds great promise for MRI, especially for human applications at high fields. For calibration it requires mapping the effective RF magnetic fields, B, of the transmitter array. This is challenging to do accurately and fast due to the large dynamic range of B and tight SAR constraints. In the present work, this problem is revisited and solved by a novel mapping approach relying on an interference principle. The B fields of individual transmitter elements are measured indirectly by observing their interference with a SAR‐efficient baseline RF field. In this fashion even small RF fields can be observed in the B ‐sensitive large‐flip‐angle regime. Based on a set of such experiments B maps of the individual transmitter channels are obtained by solving a linear inverse problem. Confounding relaxation and off‐resonance effects are addressed by an extended signal model and nonlinear fitting. Using the novel approach, 2D mapping of an 8‐channel transmitter array was accomplished in less than a minute. For validation it is demonstrated that mapping results do not vary with T1 or parameters of the mapping sequence. In RF shimming experiments it is shown that the measured B maps accurately reflect the linearity of RF superposition. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Spatial normalization of the fiber orientation distribution based on high angular resolution diffusion imaging data
Authors: Hong Xin , Arlinghaus Lori R. , Anderson Adam W. 
Published: April 2009

AbstractComparison of high angular resolution diffusion imaging (HARDI) measurements between subjects or between timepoints for the same subject are facilitated by spatial normalization. In this work an algorithm was developed to transform the fiber orientation distribution (FOD) function, based on HARDI data, taking into account not only translation, but also rotation, scaling, and shearing effects of the spatial transformation. The algorithm was tested using simulated data and intrasubject and intersubject normalization of in vivo human data. All cases demonstrated reliable transformation of the FOD. This technique makes it possible to compare the intravoxel fiber distribution between subjects, between groups, or between timepoints for a single subject, which will be helpful in HARDI studies of white matter disease. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
HTGRAPPA: Real‐time B1‐weighted image domain TGRAPPA reconstruction
Authors: Saybasili Haris , Kellman Peter , Griswold Mark A. , Derbyshire J. Andrew , Guttman Michael A. 
Published: April 2009

AbstractThe temporal generalized autocalibrating partially parallel acquisitions (TGRAPPA) algorithm for parallel MRI was modified for real‐time low latency imaging in interventional procedures using image domain, B1‐weighted reconstruction. GRAPPA coefficients were calculated in k‐space, but applied in the image domain after appropriate transformation. Convolution‐like operations in k‐space were thus avoided, resulting in improved reconstruction speed. Image domain GRAPPA weights were combined into composite unmixing coefficients using adaptive B1‐map estimates and optimal noise weighting. Images were reconstructed by pixel‐by‐pixel multiplication in the image domain, rather than time‐consuming convolution operations in k‐space. Reconstruction and weight‐set calculation computations were parallelized and implemented on a general‐purpose multicore architecture. The weight calculation was performed asynchronously to the real‐time image reconstruction using a dedicated parallel processing thread. The weight‐set coefficients were computed in an adaptive manner with updates linked to changes in the imaging scan plane. In this implementation, reconstruction speed is not dependent on acceleration rate or GRAPPA kernel size. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Reproducibility of cerebral phenylalanine levels in patients with phenylketonuria determined by 1H‐MR spectroscopy
Authors: Kreis R. , Zwygart K. , Boesch C. , Nuoffer J‐M. 
Published: April 2009

AbstractThe reproducibility of metabolite content determined by MR spectroscopy (MRS) is usually at best a few percent for the prominent singlets. When studying low‐concentration metabolites, like phenylalanine (Phe), where tissue content can be <100 μmol/kg, better reproducibility is paramount—particularly in view of using MRS results for potential individual treatment advice. An optimized, targeted spectroscopy method was established at 1.5T and reproducibility was established in 21 patients with phenylketonuria (PKU) where three spectra were recorded in each of three independent sessions, two of which were in immediate succession to minimize physiologic variation. Intersession variation was found to be only 7 μmol/kg Phe for back‐to‐back repetition of sessions, in close agreement with the variation of 16 μmol/kg observed for single spectra within a session. Analysis of variance proved the individuality of the blood/brain Phe ratio—though this ratio seems to be influenced by physiologic factors that are not stable in time. The excellent reproducibility was achieved through optimization of various factors, including signal‐to‐noise ratio, repositioning, and prescan calibrations, but also by enforcing as much prior information as possible (e.g., lineshape and phase from reference scans, constant prior‐knowledge‐locked baseline). While the application of maximum general prior knowledge is a general method to reduce fluctuations, one should remember that it may introduce systematic errors. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Characterization and correction of system delays and eddy currents for MR imaging with ultrashort echo‐time and time‐varying gradients
Authors: Atkinson Ian C. , Lu Aiming , Thulborn Keith R. 
Published: April 2009

AbstractReconstruction of high‐quality MR images requires precise knowledge of the dynamic gradient magnetic fields used to perform spatial encoding. System delays and eddy currents can perturb the gradient fields in both time and space and significantly degrade the image quality for acquisitions with an ultrashort echo time or with rapidly varying readout gradient waveforms. A technique for simultaneously characterizing and correcting the system delay and linear‐ and zero‐order eddy currents of an MR system is proposed. A single set of calibration scans were used to compute a set of system constants that describe the effects of system delays and eddy currents to enable accurate reconstruction of data collected before uncorrected eddy currents have decayed. The ability of the proposed technique to reproducibly characterize small fixed delays (<50 μs) and short‐time constant (<1 ms) eddy currents is demonstrated. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Quantitative analysis of first‐pass contrast‐enhanced myocardial perfusion MRI using a patlak plot method and blood saturation correction
Authors: Ichihara Takashi , Ishida Masaki , Kitagawa Kakuya , Ichikawa Yasutaka , Natsume Takahiro , Yamaki Noriyasu , Maeda Hisato , Takeda Kan , Sakuma Hajime 
Published: April 2009

AbstractThe objectives of this study were to develop a method for quantifying myocardialK1and blood flow (MBF) with minimal operator interaction by using a Patlak plot method and to compare the MBF obtained by perfusion MRI with that from coronary sinus blood flow in the resting state. A method that can correct for the nonlinearity of the blood time–signal intensity curve on perfusion MR images was developed. Myocardial perfusion MR images were acquired with a saturation‐recovery balanced turbo field‐echo sequence in 10 patients. Coronary sinus blood flow was determined by phase‐contrast cine MRI, and the average MBF was calculated as coronary sinus blood flow divided by left ventricular (LV) mass obtained by cine MRI. Patlak plot analysis was performed using the saturation‐corrected blood time–signal intensity curve as an input function and the regional myocardial time–signal intensity curve as an output function. The mean MBF obtained by perfusion MRI was 86 ± 25 ml/min/100 g, showing good agreement with MBF calculated from coronary sinus blood flow (89 ± 30 ml/min/100 g,r= 0.74). The mean coefficient of variation for measuring regional MBF in 16 LV myocardial segments was 0.11. The current method using Patlak plot permits quantification of MBF with operator interaction limited to tracing the LV wall contours, registration, and time delays. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Vertical amplitude reduction of Rayleigh waves by a row of piles in a poroelastic half‐space
Authors: Cai Yuan‐Qiang , Ding Guang‐Ya , Xu Chang‐Jie , Wang Jun 
Published: April 2009

AbstractA row of rigid piles is addressed as the countermeasures for isolating Rayleigh waves in a poroelastic half‐space. The complex characteristic equations for Rayleigh waves are derived via Biot's theory and their existence conditions are given. The piles are modeled as Euler–Bernoulli beams with longitudinal displacements and the diffracted field by each pile is constructed only with Rayleigh waves. Six infinite linear systems of algebraic equations are obtained in terms of the equilibrium of forces and continuity of displacements at the pile–soil interfaces. The systems are subsequently solved in the complex least‐squares sense. The influence of certain pile and soil characteristics such as the permeability of poroelastic soil, spacing between the piles and length of the piles on the isolating performance of a pile barrier is investigated. Computed results show that the permeability of poroelastic soil displays a significant effect on the vertical amplitude reduction of Rayleigh waves. Copyright © 2009 John Wiley & Sons, Ltd.
Buckling of thin‐walled cylindrical shells under axial compression
Authors: Ullah Himayat 
Published: April 2009

AbstractLightweight thin‐walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. The buckling of an axially compressed shell is studied using analytical, numerical and semi‐empirical models. An analytical model is developed using the classical shell small deflection theory. A semi‐empirical model is obtained by employing experimental correction factors based on the available test data in the theoretical model. Numerical model is built using ANSYS finite element analysis code for the same shell. The comparison reveals that the analytical and numerical linear model results match closely with each other but are higher than the empirical values. To investigate this discrepancy, non‐linear buckling analyses with large deflection effect and geometric imperfections are carried out. These analyses show that the effects of non‐linearity and geometric imperfections are responsible for the mismatch between theoretical and experimental results. The effect of shell thickness, radius and length variation on buckling load and buckling mode has also been studied. Copyright © 2009 John Wiley & Sons, Ltd.