bluuebunny/crossref_metadata_2025_split huggingface dataset:
Competition STD NMR for the detection of high‐affinity ligands and NMR‐based screening
Authors: Wang Yu‐Sen , Liu Dingjiang , Wyss Daniel F. 
Published: March 2004

AbstractThe reported competition STD NMR method combines saturation transfer difference (STD) NMR with competition binding experiments to allow the detection of high‐affinity ligands that undergo slow chemical exchange on the NMR time‐scale. With this technique, the presence of a competing high‐affinity ligand in the compound mixture can be detected by the disappearance or reduction of the STD signals of a low‐affinity indicator ligand. This is demonstrated on a BACE1 (β‐site amyloid precursor protein cleaving enzyme 1) protein–inhibitor system. This method can also be used to derive an approximate value, or a lower limit, for the dissociation constant of the potential ligand based on the reduction of the signal intensity of the STD indicator, which is illustrated on an HSA (human serum albumin) model system. This leads to important applications of the competition STD NMR method for lead discovery: it can be used (i) for compound library screening against a broad range of drug targets to identify both high‐ and low‐affinity ligands and (ii) to rank order analogs rapidly and derive structure–activity relationships, which are used to optimize these NMR hits into viable drug leads. Copyright © 2004 John Wiley & Sons, Ltd.
Dynamic NMR spectroscopy of hyperpolarized 129Xe in human brain analyzed by an uptake model
Authors: Kilian Wolfgang , Seifert Frank , Rinneberg Herbert 
Published: March 2004

AbstractHyperpolarized 129Xe (HpXe) NMR not only holds promise for functional lung imaging, but for measurements of tissue perfusion as well. To investigate human brain perfusion, several time‐series of 129Xe MR spectra were recorded from one healthy volunteer after HpXe inhalation. The time‐dependent amplitudes of the MR spectra were analyzed by using a compartment model for xenon uptake modified to account for the loss of 129Xe polarization due to RF‐excitation and for the breathhold technique used in the experiments. This analysis suggests that the resonances detected at 196.5 ± 1 ppm and 193 ± 1 ppm originate from HpXe dissolved in gray and white matter, respectively, and that T1 relaxation times of HpXe are different in gray and white matter (T1g > T1w). Magn Reson Med 51:843–847, 2004. © 2004 Wiley‐Liss, Inc.
Complementary displacement‐encoded MRI for contrast‐enhanced infarct detection and quantification of myocardial function in mice
Authors: Gilson Wesley D. , Yang Zequan , French Brent A. , Epstein Frederick H. 
Published: March 2004

AbstractMRI is emerging as an important modality for assessing myocardial function in transgenic and knockout mouse models of cardiovascular disease, including myocardial infarction (MI). Displacement encoding with stimulated echoes (DENSE) measures myocardial motion at high spatial resolution using phase‐reconstructed images. The current DENSE technique uses inversion recovery (IR) to suppress T1‐relaxation artifacts; however, IR is ill‐suited for contrast‐enhanced infarct imaging in the heart, where multiple T1 values are observed. We have developed a modified DENSE method employing complementary acquisitions for T1‐independent artifact suppression. With this technique, displacement and strain are measured in phase‐reconstructed images, and contrast‐enhanced regions of infarction are depicted in perfectly coregistered magnitude‐reconstructed images. The displacement measurements and T1‐weighted image contrast were validated with the use of a rotating phantom. Modified DENSE was performed in mice (N = 9) before and after MI. Circumferential (Ecc) and radial (Err) strain were measured, and contrast‐enhanced infarcted myocardium was detected by DENSE. At baseline, Ecc was −0.16 ± 0.01 and Err was 0.39 ± 0.07. After MI, Ecc was 0.04 ± 0.02 and Err was 0.03 ± 0.04 in infarcted regions, whereas Ecc was −0.12 ± 0.02 and Err was 0.38 ± 0.09 in noninfarcted regions. In vivo Ecc as determined by DENSE correlated well with Ecc obtained by conventional tag analysis (R = 0.90). Magn Reson Med 51:744–752, 2004. © 2004 Wiley‐Liss, Inc.
Evaluation of a pneumatically driven tactile stimulator device for vision substitution during fMRI studies
Authors: Zappe Anne‐Catherin , Maucher Thorsten , Meier Karlheinz , Scheiber Christian 
Published: March 2004

AbstractFunctional magnetic resonance imaging (fMRI) experiments on tactile perception are difficult to perform because the special characteristics of an MRI environment restrict the experimental setup. Although recently developed actuators have made it possible to apply vibrotactile stimuli to the skin during an fMRI experiment, the projection of spatially extended patterns is still precluded. In order to examine the processing of tactile perception, a new pneumatically‐driven tactile device (PTD) has been built. This device is capable of stimulating the skin, using arbitrary time sequences that consist of 2D tactile images up to 64 pixels. It is shown how the device is implemented in a 2 T fMRI environment, and show that it operates without generating artifacts. Dedicated software allows the generation of complex paradigms and provides a user‐friendly interface to other brain mapping systems, as well as automated operation. This paper describes the PTD elucidates its features, and demonstrate its reliability by reporting results from an fMRI study based on an event‐related protocol involving six subjects. Magn Reson Med 51:828–834, 2004. © 2004 Wiley‐Liss, Inc.
Normal cerebral perfusion measurements using arterial spin labeling: Reproducibility, stability, and age and gender effects
Authors: Parkes Laura M. , Rashid Waqar , Chard Declan T. , Tofts Paul S. 
Published: March 2004

AbstractBefore meaningful conclusions can be drawn from clinical measures of cerebral blood perfusion, the precision of the measurement must be determined and set in the context of inter‐ and intrasubject sources of variability. This work establishes the reproducibility of perfusion measurements using the noninvasive MRI technique of continuous arterial spin labeling (CASL). Perfusion was measured in 34 healthy normal subjects. Intersubject variability was assessed, and age and gender contributions were estimated. Intersubject variation was found to be large, with up to 100% perfusion difference for subjects of the same age and gender. Repeated measurements in one subject showed that perfusion remains remarkably stable in the short term when compared with intersubject variation and the large capacity for perfusion change in the brain. A significant decrease in the ratio of gray‐matter to white‐matter perfusion was found with increasing age (0.79% per year (P < 0.0005)). This appears to be due mainly to a reduction in gray‐matter perfusion, which was found to decrease by 0.45% per year (P = 0.04). Regional analysis suggested that the gray‐matter age‐related changes were predominantly localized in the frontal cortex. Whole‐brain perfusion was 13% higher (P = 0.02) in females compared to males. Magn Reson Med 51:736–743, 2004. © 2004 Wiley‐Liss, Inc.
Inflow correction of hepatic perfusion measurements using T1‐weighted, fast gradient‐echo, contrast‐enhanced MRI
Authors: Peeters Frank , Annet Laurence , Hermoye Laurent , Van Beers Bernard E. 
Published: March 2004

AbstractInflow effects were studied for T1‐weighted, fast gradient‐echo, contrast‐enhanced MRI. This was done on the basis of realistic simulations (e.g., taking slice profiles into account) for unsteady flow. The area under the point spread function (PSF) was used to estimate the flow‐related enhancement. A simple analytical model that accurately describes the inflow effects was derived and validated. This model was used to correct the experimental perfusion calibration curves (signal intensity vs. relaxation rate) for inflow effects. Hepatic perfusion measurements, performed on patients, were analyzed in terms of a dual‐input, first‐order linear model. It was shown that inflow causes incorrect perfusion input functions. The resulting estimated perfusion parameters displayed a systematic error of typically 30–40%. By performing two extra time‐resolved flow measurements during the examination, one can correct the input functions. Magn Reson Med 51:710–717, 2004. © 2004 Wiley‐Liss, Inc.
Reduced field of view and undersampled PR combined for interventional imaging of a fully dynamic field of view
Authors: Peters Dana C. , Guttman Michael A. , Dick Alexander J. , Raman Venkatesh K. , Lederman Robert J. , McVeigh Elliot R. 
Published: March 2004

AbstractActive catheter imaging was investigated using real‐time undersampled projection reconstruction (PR) combined with the temporal filtering technique of reduced field of view (rFOV). Real‐time rFOV processing was interactively enabled during highly undersampled catheter imaging, resulting in improved artifact suppression with better temporal resolution than that obtained by view‐sharing. Imaging with 64 to 32 projections provided a resolution of 2 × 2 × 8 mm, and four to eight true frames per second. Image artifacts were reduced when rFOV processing was applied to the undersampled images. A comparison with Cartesian rFOV showed that PR image quality is less susceptible to aliasing that results from rFOV imaging with a wholly dynamic outer FOV. Simulations and MRI experiments demonstrated that PR rFOV provides significant artifact suppression, even for a fully dynamic FOV. The near doubling of temporal resolution that is possible with PR rFOV permits accurate monitoring of highly dynamic events, such as catheter movements, and arrhythmias, such as ventricular ectopy. Magn Reson Med 51:761–767, 2004. © 2004 Wiley‐Liss, Inc.
Glucose production pathways by 2H and 13C NMR in patients with HIV‐associated lipoatrophy
Authors: Weis Brian C. , Margolis David , Burgess Shawn C. , Merritt Matthew E. , Wise Holly , Sherry A. Dean , Malloy Craig R. 
Published: March 2004

AbstractPatients with HIV taking protease inhibitors were selected for the presence (five subjects) or absence (five subjects) of lipoatrophy. Following an overnight fast, subjects were given oral 2H2O in divided doses (5 mL/kg body water), [U‐13C3] propionate (10 mg/kg), and acetaminophen (1000 mg). Glucose (from plasma) or acetaminophen glucuronide (from urine) were converted to monoacetone glucose for 2H NMR and 13C NMR analysis. The fraction of plasma glucose derived from gluconeogenesis was not significantly different between groups. However, flux from glycerol into gluconeogenesis relative to glucose production was increased from 0.20 ± 0.13 among subjects without lipoatrophy to 0.42 ± 0.12 (P < 0.05) among subjects with lipoatrophy, and the TCA cycle contribution was reduced. Lipoatrophy was associated with an abnormal profile of glucose production as assessed by 13C and 2H NMR of plasma and urine. Magn Reson Med 51:649–654, 2004. Published 2004 Wiley‐Liss, Inc.
Improved accuracy for the Helmholtz equation in unbounded domains
Authors: Turkel Eli , Farhat Charbel , Hetmaniuk Ulrich 
Published: March 2004

AbstractBased on properties of the Helmholtz equation, we derive a new equation for an auxiliary variable. This reduces much of the oscillations of the solution leading to more accurate numerical approximations to the original unknown. Computations confirm the improved accuracy of the new models in both two and three dimensions. This also improves the accuracy when one wants the solution at neighbouring wavenumbers by using an expansion in k. We examine the accuracy for both waveguide and scattering problems as a function of k, h and the forcing mode l. The use of local absorbing boundary conditions is also examined as well as the location of the outer surface as functions of k. Connections with parabolic approximations are analysed. Copyright © 2004 John Wiley & Sons, Ltd.
A recipe to detect the error in discretization schemes
Authors: Lapenta Giovanni 
Published: March 2004

AbstractThe necessity for a reliable measure of the discretization error arises in adaptive mesh refinement and in moving mesh adaptation. The present work discusses a detector of the discretization error based on the interpolation reconstruction of the operators. The technique presented here is named operator recovery error source detector (ORESD). Its main features are: First, the technique is based on the operators being discretized and does not require any user intervention or any a priori knowledge of the solution or its properties. Second, the ORESD is an a posteriori error indicator, but it is shown to be consistent with the a priori error provided by the modified equation approach. Third, the technique is based on the operators being solved and is tailored to the specific problem at hand. Four, the technique is simple and is based on a small stencil, resulting in a very inexpensive error detection.In the present work, the ORESD is derived and applied to two tutorial examples: divergence and gradient. With the aid of the two examples and using the general derivation, the ORESD is then applied to the gas dynamics equations. Two benchmarks are used to test the performance. First, a shock tube problem is solved (Sod's benchmark) in a Lagrangian and in a Eulerian frame. Second, the Colella's wedge problem is solved using CLAWPACK. Finally, the ORESD is applied to the 2D Poisson equation on a uniform and on a non‐uniform grid to test the application to elliptic problems. In all examples the operator recovery error source detector succeeds in detecting the real sources of error. Copyright © 2004 John Wiley & Sons, Ltd.
Removal of proteins from natural rubber with urea
Authors: Kawahara Seiichi , Klinklai Warunee , Kuroda Hirofumi , Isono Yoshinobu 
Published: March 2004

AbstractRemoval of proteins from natural rubber was achieved by incubation of the rubber latex with urea in the presence of a surfactant to prevent the latex‐allergy caused with thin film products. Temperature, pH and time for the incubation were investigated to remove the proteins effectively, in which nitrogen content of the rubber was reduced to 0.02 from 0.38 wt% under the optimum condition. To remove further the proteins, deproteinization of natural rubber was made by incubation of the latex with proteolytic enzyme in the presence of a surfactant followed by incubation with urea. Amount of allergen decreased through the procedure to less than 0.7 μg/ml, which is a small amount of allergen compared to that for the commercial, deproteinized natural rubber. Copyright © 2004 John Wiley & Sons, Ltd.
Theoretical analysis of fiber motion and loads during flow
Authors: Hernandez J. P. , Raush T. , Rios A. , Strauss S. , Osswald T. A. 
Published: March 2004

AbstractA pseudo‐analytical model for the forces exerted on fibers during flow that lead to fiber damage is proposed and solved. The fundamental derivations for the forces on fibers moving in suspensions developed by Burgers (1938) were used as a comparison. The cases of the motion of a fiber along its axis and perpendicular to its axis and in shear flow at a −45 degree‐angle were investigated for aspect ratios between 10 and 300. The values for the overall forces on the fiber were in good agreement with the results found earlier by Burgers and others. However, the force distribution along the fiber was found to be significantly different from the constant distribution assumed by Burgers. Because of the higher forces on the fiber from the exact solution, the criterion for the onset of buckling in shear flow was revised. The pseudo‐analytical solution was also compared to numerical results done with the boundary element method (BEM); the results were in good agreement.
Mechanical properties of polypropylene matrix composites reinforced with natural fibers: A statistical approach
Authors: Biagiotti J. , Fiori S. , Torre L. , López‐Manchado M. A. , Kenny J. M. 
Published: March 2004

AbstractThis work presents a systematic and statistical approach to evaluate and predict the properties of random discontinuous natural fiber reinforced composites. Different composites based on polypropylene and reinforced with natural fibers were produced and their mechanical properties are measured together with the distribution of the fiber size and the fiber diameter. The values obtained were related to the theoretical predictions, using a combination of the Griffith theory for the effective properties of the natural fibers and the Halpin‐Tsai equation for the elastic modulus of the composites. The relationships between experimental results and theoretical predictions were statistically analyzed using a probability density function estimation approach based on neural networks. The results show a more accurate expected value with respect to the traditional statistical function estimation approach. In order to point out the particular features of natural fibers, the same proposed method is also applied to PP–glass fiber composites.
Damage behavior in multi‐stage fatigue testing of glass‐fiber‐reinforced polyamide 66
Authors: Katoh Atsushi , Handa Kouichi , Narisawa Ikuo 
Published: March 2004

AbstractWith plastics being increasingly applied to moving parts today, predictions of continuous fatigue life under identical conditions (ambient temperature, frequency and load stress) are not sufficient. Rather, there is an urgent need to develop a method of predicting fatigue life under multi‐stage loading involving intermittently changing conditions.In this study, by applying a temperature‐ and frequency‐superposition method to fatigue life prediction of plastics, it was found that an exponential type of cumulative damage law could be applied to a two‐stage fatigue process. Specifically, when fatigue conditions (interval time, ambient temperature, frequency and load stress) are changed between several stages, the resulting damage behavior follows an exponential law representing the ratio of the number of cycles in each stage to the continuous fatigue life under those conditions. It is shown here that the exponent m has a single value and consists of the product of the independent functions of the factors of the fatigue conditions. It is also shown that the use of this exponential law reproduces very well the damage behavior in a two‐stage fatigue test in which each fatigue condition is changed and in three‐ and four‐stage fatigue tests in which the interval time is varied.
Practical diabetes international: past, present and future
Authors: Connor H 
Published: March 2004

AbstractThe 20th Anniversary of Practical Diabetes International is an opportunity to review the content of the journal over two decades. During this time there has been a marked change in emphasis from papers on type 1 diabetes, microvascular complications and devices for insulin injection and home blood glucose monitoring in the earlier issues, towards articles on type 2 diabetes, macrovascular disease and hypertension in more recent numbers. There has also been a change in emphasis from papers on education towards articles on quality and audit. Although the journal has a wide circulation among representatives of all of the professions who provide diabetes care, the non‐medical professions (nursing, dietetic and podiatric) and patients remain under‐represented as contributors. Copyright © 2004 John Wiley & Sons, Ltd.
An overview of diabetes education in the United Kingdom: past, present and future
Authors: Lucas S , Walker R 
Published: March 2004

AbstractThis paper examines the evolution of diabetes education from a time when it was viewed as an ad hoc event or even as an optional extra to one when it is now accepted as essential and central to successful self‐management. During the last 20 years there has been a transition from didactic teaching practices towards problem‐solving models which are based on modern principles of adult learning, and from one‐to‐one teaching towards group learning. The evolving role of the diabetes nurse specialist over the last two decades has been crucial in enabling these changes. The evidence base for different educational models needs further strengthening, but structured programmes for life‐long learning are now being developed. Important decisions are still needed on the provision and content of the training programmes for educators and on the mechanisms for the provision of quality assurance. Copyright © 2004 John Wiley & Sons, Ltd.
Diabetic dyslipidaemia: past, present and future
Authors: Betteridge DJ 
Published: March 2004

AbstractPrevention of cardiovascular disease (CVD) in diabetes remains a major challenge for both physicians and patients. Diabetic dyslipidaemia is a major risk factor for CVD and is open to therapeutic intervention. Information now available from randomised, controlled, clinical trials (principally with statins) confirms highly significant benefits in terms of CVD reduction for diabetic patients with and without symptomatic CVD. This evidence base has moved treatment of dyslipidaemia to centre stage in CVD prevention. Important European and American guidelines point to the high CVD risk in type 2 diabetes and type 1 diabetes with albuminuria and advocate aggressive lipid management for primary as well as secondary CVD prevention. Currently there is evidence of sub‐optimal uptake of appropriate lipid‐lowering therapy and guidelines need to be fully implemented in clinical practice for the benefit of individual patients. In the future it is likely that more combination therapy will be used to treat diabetic dyslipidaemia in order to achieve better overall lipid control. Copyright © 2004 John Wiley & Sons, Ltd.
Polyaniline/carbon nanotube composite Schottky contacts
Authors: Ramamurthy Praveen C. , Harrell William R. , Gregory Richard V. , Sadanadan Bindu , Rao Apparao M. 
Published: March 2004

AbstractSchottky contacts were fabricated on composites of high molecular weight polyaniline and pristine multiwalled carbon nanotubes. Physical and electrical characteristics of these organic composite materials were studied by using atomic force microscopy (AFM), scanning electron microscopy (SEM), and electrical measurements. The RMS surface roughness of the composite films was found to be 4 nm. From the IV characteristics of these composite devices, it appears that the current follows Ohm's law at lower voltages and Child's law at higher voltages, indicating a space‐charge‐limited emission mechanism in the presence of a distribution of shallow traps.
Mechanical properties, water swelling behavior, and morphology of swellable rubber compatibilized by PVA‐g‐PBA
Authors: Zhang Zhihao , Zhang Guo , Zhang Yue , Wang Zhigang , Yu Donghong , Hu Xiangqing , Hu Chaoquan , Tang Xinyi 
Published: March 2004

AbstractA novel water swellable rubber (WSR) was prepared by blending chlorohydrin rubber (CHR) with crosslinked polyacrylate (CPA), poly(vinyl alcohol)‐g‐poly(butyl acrylate) (PVA‐g‐PBA), precipitated silica (PSA), and poly(ethylene glycol) (PEG). The amphiphilic graft copolymer PVA‐g‐PBA was incorporated as the compatibilizer between CHR and CPA. Water swellable‐rubber with different grafting percentages and contents of PVA‐g‐PBA was investigated by SEM, mechanical measurement, and water‐swelling tests. The results prove that PVA‐g‐PBA increased interfacial cohesion between CHR and CPA before and after water swelling, decreased percentage loss by weight, and improved water‐swelling behavior. Mechanical properties of WSR were significantly improved by PVA‐g‐PBA, especially for the blends of 5 phr PVA‐g‐PBA with G% = 151.7% before water swelling and that with G% = 340.4% after water swelling.