bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biexponential transverse relaxation (T2) of the proton MRS creatine resonance in human brain
Authors: Ke Y. , Cohen B.M. , Lowen S. , Hirashima F. , Nassar L. , Renshaw P.F. 
Published: August 2002

AbstractDifferences in proton MRS T2 values for phosphocreatine (PCr) and creatine (Cr) methyl groups (3.0 ppm) were investigated in studies of phantoms and human brain. Results from phantom studies revealed that T2 of PCr in solution is significantly shorter than T2 of Cr. Curve‐fitting results indicated that the amplitude‐TE curves of the total Cr resonance at 3.0 ppm in human brain (N = 26) fit a biexponential decay model significantly better than a monoexponential decay model (P < 0.006), yielding mean T2 values of 117 ± 21 ms and 309 ± 21 ms. Using a localized, long‐TE (272 ms) point‐resolved spectroscopy (PRESS) proton MRS during 2 min of photic stimulation (PS), an increase of 12.1% ± 3.5% in the mean intensity of the total Cr resonance in primary visual cortex (VI) was observed at the end of stimulation (P < 0.021). This increase is consistent with the conversion of 26% of PCr in VI to Cr, which is concordant with 31P MRS findings reported by other investigators. These results suggest a significantly shorter T2 for PCr than for Cr in vivo. This difference possibly could be exploited to quantify regional activation in functional spectroscopy studies, and could also lead to inaccuracies in some circumstances when the Cr resonance is used as an internal standard for 1H MRS studies in vivo. Magn Reson Med 47:232–238, 2002. © 2002 Wiley‐Liss, Inc.
Image‐based EPI ghost correction using an algorithm based on projection onto convex sets (POCS)
Authors: Lee K.J. , Barber D.C. , Paley M.N. , Wilkinson I.D. , Papadakis N.G. , Griffiths P.D. 
Published: August 2002

AbstractThis work describes the use of a method, based on the projection onto convex sets (POCS) algorithm, for reduction of the N/2 ghost in echo‐planar imaging (EPI). In this method, ghosts outside the parent image are set to zero and a model k‐space is obtained from the Fourier transform (FT) of the resulting image. The zeroth‐ and first‐order phase corrections for each line of the original k‐space are estimated by comparison with the corresponding line in the model k‐space. To overcome problems of phase wrapping, the first‐order phase corrections for the lines of the original k‐space are estimated by registration with the corresponding lines in the model k‐space. It is shown that applying these corrections will result in a reduction of the ghost, and that iterating the process will result in a convergence towards an image in which the ghost is minimized. The method is tested on spin‐echo EPI data. The results show that the method is robust and remarkably effective, reducing the N/2 ghost to a level nearly comparable to that achieved with reference scans. Magn Reson Med 47:812–817, 2002. © 2002 Wiley‐Liss, Inc.
Pulsed Z‐spectroscopic imaging of cross‐relaxation parameters in tissues for human MRI: Theory and clinical applications
Authors: Yarnykh Vasily L. 
Published: August 2002

AbstractA new method of pulsed Z‐spectroscopic imaging is proposed for in vivo visualization and quantification of the parameters describing cross‐relaxation between protons with liquid‐like and solid‐like relaxation properties in tissues. The method is based on analysis of the magnetization transfer (MT) effect as a function of the offset frequency and amplitude of a pulsed off‐ resonance saturation incorporated in a spoiled gradient‐echo MRI pulse sequence. The theoretical concept of the method relies on an approximated analytical model of pulsed MT that provides a simple three‐parameter equation for a pulsed steady‐state Z‐spectrum taken far from resonance. Using this model, the parametric images of cross‐relaxation rate constant, content, and T2 of the semisolid proton fraction can be reconstructed from a series of MT‐weighted images and a coregistered T1 map. The method was implemented on a 0.5 T clinical MRI scanner, and it provided high‐quality 3D parametric maps within an acceptable scanning time. The estimates of cross‐relaxation parameters in brain tissues were shown to be quantitatively consistent with the literature data. Clinical examples of the parametric images of human brain pathologies (multiple sclerosis and glioma) demonstrated high tissue contrast and clear visualization of the lesions. Magn Reson Med 47:929–939, 2002. © 2002 Wiley‐Liss, Inc.
Imaging brain function in humans at 7 Tesla
Authors: Yacoub Essa , Shmuel Amir , Pfeuffer Josef , Van De Moortele Pierre‐Francois , Adriany Gregor , Andersen Peter , Vaughan J. Thomas , Merkle Hellmut , Ugurbil Kamil , Hu Xiaoping 
Published: August 2002

AbstractThis article describes experimental studies performed to demonstrate the feasibility of BOLD fMRI using echo‐planar imaging (EPI) at 7 T and to characterize the BOLD response in humans at this ultrahigh magnetic field. Visual stimulation studies were performed in normal subjects using high‐resolution multishot EPI sequences. Changes in R arising from visual stimulation were experimentally determined using fMRI measurements obtained at multiple echo times. The results obtained at 7 T were compared to those at 4 T. Experimental data indicate that fMRI can be reliably performed at 7 T and that at this field strength both the sensitivity and spatial specificity of the BOLD response are increased. This study suggests that ultrahigh field MR systems are advantageous for functional mapping in humans. Magn Reson Med 45:588–594, 2001. © 2001 Wiley‐Liss, Inc.
Imaging longitudinal cardiac strain on short‐axis images using strain‐encoded MRI
Authors: Osman Nael F. , Sampath Smita , Atalar Ergin , Prince Jerry L. 
Published: August 2002

AbstractThis article presents a new method for measuring longitudinal strain in a short‐axis section of the heart using harmonic phase magnetic resonance imaging (HARP‐MRI). The heart is tagged using 1‐1 SPAMM at end‐diastole with tag surfaces parallel to a short‐axis imaging plane. Two or more images are acquired such that the images have different phase encodings in a direction orthogonal to the image plane. A dense map of the longitudinal strain can be computed from these images using a simple, fast computation. Simulations are conducted to study the effect of noise and the choice of out‐of‐plane phase encoding values. Longitudinal strains acquired from a normal human male are shown. Magn Reson Med 46:324‐334, 20001. © 2001 Wiley‐Liss, Inc.
MR‐derived cerebral blood volume maps: Issues regarding histological validation and assessment of tumor angiogenesis
Authors: Pathak Arvind P. , Schmainda Kathleen M. , Ward B. Douglas , Linderman J.R. , Rebro Kelly J. , Greene Andrew S. 
Published: August 2002

AbstractIn an effort to develop MRI methods for the evaluation of tumor angiogenesis (new blood vessel formation), MRI‐derived cerebral blood volume (CBV) information has been compared to histologic measures of microvessel density (MVD). Although MVD is a standard marker of angiogenesis, it is not a direct correlate of the volume measurements made with MRI, and therefore inappropriate for the development and validation of the MR techniques. Therefore, the goal of this study was to develop an approach by which MR measurements of CBV can be directly correlated. To this end, dynamic susceptibility contrast (DSC) MRI experiments were performed in six Fisher rats implanted with 9L gliosarcoma brain tumors. Subsequently, the circulation was perfused with a latex compound (Microfil®), after which 50‐μm tissue sections were analyzed for vessel count, diameter, and the fraction of area comprised of vessels. The results demonstrate that while fractional area (FA) does not provide a good measure of CBV, FA corrected for section thickness effects does. Whereas the FA in normal brain was found to be 13.03 ± 1.83% the corrected FA, or fractional volume (FV), was 1.89 ± 0.39%, a value in agreement with those reported in the literature for normal brain. Furthermore, while no significant difference was found between normal brain and tumor FA (P = 0.55), the difference was significant for FV (P = 0.036), as would be expected. And only with FV does a correlation with the MRI‐derived CBV become apparent (rS = 0.74). There was strong correlation (rs = 0.886) between the tumor / normal blood volume ratios as estimated by each technique, although the MR‐ratio (1.56 ± 0.29) underestimated the histologic‐ratio (2.35 ± 0.75). Thus, the correlation of MRI CBV methods requires a measurement of fractional vessel area and correction of this area for section thickness effects. This new independent correlative measure should enable efficient and accurate progress in the development of MRI methods to evaluate tumor angiogenesis. Magn Reson Med 46:735–747, 2001. © 2001 Wiley‐Liss, Inc.
Localized bioimpedance analysis in the evaluation of neuromuscular disease
Authors: Rutkove Seward B. , Aaron Ronald , Shiffman Carl A. 
Published: August 2002

AbstractLocalized bioimpedance analysis is a novel, noninvasive technique with potential application to neuromuscular disease. In this procedure, high‐frequency alternating current is passed through muscle, and parameters related to the consequent voltage pattern are evaluated. Currents flowing perpendicular to muscle fibers encounter many more cell membranes than do currents flowing parallel to them, producing surface voltage patterns that are altered by disease. Using this technique, 45 normal subjects and 25 patients with various neuromuscular diseases were studied, including 4 with amyotrophic lateral sclerosis, 4 with inflammatory myopathy, and 11 with inclusion‐body myositis. Two parameters, the spatially averaged phase and the effective longitudinal resistivity, were altered in patients with neuromuscular disease. Reductions in phase correlated to disease progression, whereas normalization of phase correlated with disease remission. In patients with inclusion‐body myositis, a unique pattern of reduced phase and elevated resistivity was identified. These findings suggest that localized bioimpedance analysis has the potential of playing a substantial role in the diagnostic and therapeutic evaluation of neuromuscular disease. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Rhabdomyolysis: A review
Authors: Warren Jason D. , Blumbergs Peter C. , Thompson Philip D. 
Published: August 2002

AbstractRhabdomyolysis, a syndrome of skeletal muscle breakdown with leakage of muscle contents, is frequently accompanied by myoglobinuria, and if sufficiently severe, acute renal failure with potentially life‐threatening metabolic derangements may ensue. A diverse spectrum of inherited and acquired disorders affecting muscle membranes, membrane ion channels, and muscle energy supply causes rhabdomyolysis. Common final pathophysiological mechanisms among these causes of rhabdomyolysis include an uncontrolled rise in free intracellular calcium and activation of calcium‐dependent proteases, which lead to destruction of myofibrils and lysosomal digestion of muscle fiber contents. Recent advances in molecular genetics and muscle enzyme histochemistry may enable a specific metabolic diagnosis in many patients with idiopathic recurrent rhabdomyolysis. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
Human muscle protein degradation in vitro by eosinophil cationic protein (ECP)
Authors: Sugihara Rie , Kumamoto Toshihide , Ito Tomoko , Ueyama Hidetsugu , Toyoshima Itaru , Tsuda Tomiyasu 
Published: August 2002

AbstractTo clarify the role of tissue eosinophils in and around inflammatory foci, we purified eosinophil cationic protein (ECP) and examined its effect on muscle protein degradation in vitro. Eosinophil cationic protein was purified from the buffy coat of blood from healthy volunteers. Myofibrillar, soluble sarcoplasmic, and membrane‐associated cytoskeletal proteins were fractionated from latissimus dorsi muscle obtained by orthopedic procedures done on a patient with no neurologic abnormalities. After incubation of these fractions with purified ECP, sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) and immunoblotting were performed. Eosinophil cationic protein degraded the myofibrillar proteins, especially the myosin heavy chain (MHC) and α‐actinin. It also degraded membrane‐associated cytoskeletal proteins dystrophin and spectrin, whereas soluble sarcoplasmic proteins did not undergo proteolysis. Quantitative analysis of the MHC degradation showed that the ECP reaction was dose‐dependent and that the optimal pH was 7.0. Protein degradation was not inhibited by heparin or the protease inhibitors leupeptin, E‐64, and pepstatin A. Our results suggest that ECP functions in the degradation of myofibrillar and membrane‐associated cytoskeletal proteins, indicating that tissue eosinophils have a specific role in muscle fiber degradation in some myopathies associated with numerous tissue eosinophils, such as eosinophilic myositis, eosinophilic myalgia syndrome, and eosinophilic endocardial disease. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1627–1634, 2001
A fully coupled hydro‐thermo‐poro‐mechanical model for black oil reservoir simulation
Authors: Pao W. K. S. , Lewis R. W. , Masters I. 
Published: August 2002

AbstractA fully coupled formulation of a hydro‐thermo‐poro‐mechanical model for a three‐phaseblack oilreservoir model is presented. The model is based upon the approach proposed by one of the authors which fully couples geomechanical effects to multiphase flow. Their work is extended here to include non‐isothermal effects. The gas phase contribution to the energy equation has been neglected based on a set of assumptions. The coupled formulation given herein differs in several ways when compared to the earlier work and an attempt is made to link the flow based formulation and mixture theory. The Finite Element Method is employed for the numerical treatment and essential algorithmic implementation is discussed. Numerical examples are presented to provide further understanding of the current methodology. Copyright © 2001 John Wiley & Sons, Ltd.
Structural features and mechanical behaviour of a pyroclastic weak rock
Authors: Cecconi Manuela , Viggiani Giulia MB 
Published: August 2002

AbstractThe results of an extensive programme of laboratory testing on intact and reconstituted samples of a pyroclastic weak rock from the volcanic complex of the Colli Albani (Central Italy) are presented. The deposit is known asPozzolana Neraand may be assimilated to a bonded coarse grained material. The nature of bonds and the micro‐structural features were examined by means of diffractometry, optical and electron microscopy. As bonds are made of the same constituents of grains and aggregates of grains, bond deterioration and particles breakage upon loading are indistinguishable features of the mechanical behaviour. The testing programme consisted mainly of one‐dimensional and drained and undrained triaxial compression tests in a wide range of confining pressures up to 58 MPa. As confining stress increases, the mechanical behaviour of the material changes from brittle and dilatant to ductile and contractant; for both brittle and ductile behaviour failure is associated with the formation of shear surfaces separating the sample in several parts at the end of test. The experimental stress–dilatancy relationships are compared with the classical stress–dilatancy theories for a purely frictional material and for a material with friction and cohesion between particles. The analysis of the data indicates that peak strength results from the interplay between degradation of inter‐particle bonds, increasing friction between particles and increasing rate of dilation. Copyright © 2001 John Wiley & Son, Ltd.
Urinary incontinence symptom scores and urodynamic diagnoses
Authors: FitzGerald Mary P. , Brubaker Linda 
Published: August 2002

AbstractThe aim of this study was to determine whether scores on two validated urinary incontinence symptom scales predicted eventual urodynamic diagnoses. Two hundred ninety‐three patients undergoing multi‐channel urodynamic testing rated their symptoms of urinary incontinence and/or pelvic organ prolapse (POP), using the Incontinence Impact Questionnaire, the Urogenital Distress Inventory, and an obstructive symptom subscale from the long form of the Incontinence Impact Questionnaire. Among the 202 (69%) patients without advance‐stage POP, increasing scores on scale items related to stress and urge incontinence predicted increasing frequency of the diagnoses of genuine stress incontinence (GSI) and detrusor instability, respectively. Among the 91 (31%) patients with advance‐stage POP, there was no association. Among all patients with GSI, the presence of intrinsic sphincter deficiency could not be predicted by responses to the symptom scales. Scores on the symptom scales were inadequate predictors of eventual urodynamic diagnoses, especially among women with advance‐stage POP. Neurourol. Urodynam. 21:30–35, 2002. © 2002 Wiley‐Liss, Inc.
Senile plaques do not induce susceptibility effects in T2*‐weighted MR microscopic images
Authors: Dhenain Marc , Privat Nicolas , Duyckaerts Charles , Jacobs Russell E. 
Published: August 2002

AbstractSenile plaques are the hallmarks of Alzheimer's disease. They typically range from 16 to 150 µm in size with most less than 25 µm. Mechanisms by which they might affect MR contrast and thus be made visible in this imaging modality are still unknown. Plausibility studies suggested that they might have a different magnetic susceptibility than surrounding tissue. A large difference would cause the plaque and a relatively large volume of adjacent tissue to be hypo‐intense in T2*‐weighted MRI scans, thus causing them to appear larger than their actual sizes and perhaps visible even when their size is below the nominal resolution limit of the imaging experiment. To evaluate this hypothesis, formalin‐fixed superior temporal gyrus samples obtained from two Alzheimer's disease and two control subjects were imaged using magnetic resonance microscopy at 11.7 T. Three dimensional T2*‐weighted gradient echo images were recorded with an isotropic resolution of 23.4 µm. The imaging protocol was especially sensitive to susceptibility effects. Samples were then stained for amyloid and/or iron deposits. Hypo‐ and hyper‐intense structures were clearly visible in MR images from all samples. Hyper‐intense structures reflected fixative penetration within the vascular system. Almost all the hypo‐intense structures were blood vessels. Their hypo‐intense profile was probably caused by iron deposits associated with the cell aggregates that they contained. Only one hypo‐intense spot could be matched with a plaque and this was one of the largest plaques in our samples. The remainder of the several hundred plaques were not visible in MR images. In histological slices the senile plaques were often larger than small blood vessels that were visible in the MR images. This suggests that susceptibility effects are not associated with senile plaques and do not provide a mechanism to differentiate them from surrounding tissue. Copyright © 2002 John Wiley & Sons, Ltd.
Electronic voting in a large‐scale distributed system
Authors: Dini Gianluca 
Published: August 2002

AbstractIn this paper, we propose a practical and secure electronic voting scheme suitable for large‐scale distributed systems such as the Internet. As in most of the voting systems in the literature, the proposed voting scheme allows only eligible voters to vote once, protects the voters' privacy, and ensures the accuracy of the tally. In addition, the proposed scheme satisfies further important criteria, namely, it tolerates abstention and does not require voters to control whether their votes have been correctly processed. If a subset of voters does not vote, the elections cannot be disrupted. Furthermore, anyone, including an external observer, can easily be convinced that the election is fair, that is, that the published final tally is fairly computed from the ballots that were correctly cast. It follows that the proposed voting scheme strengthens the security properties of the electronic voting procedure, simplifies the interaction of voters with the electronic voting system, and contributes to increased voter confidence in the degree of security of the electronic voting procedure. © 2001 John Wiley & Sons, Inc.
A catalog of Hanan grid problems
Authors: Zachariasen Martin 
Published: August 2002

AbstractWe present a general rectilinear Steiner tree problem in the plane and prove that it is solvable on the Hanan grid of the input points. This result is then used to show that several variants of the ordinary rectilinear Steiner tree problem are solvable on the Hanan grid, including—but not limited to—Steiner trees for rectilinear (or isothetic) polygons, obstacle‐avoiding Steiner trees, group Steiner trees, and prize‐collecting Steiner trees. Also, the weighted region Steiner tree problem is shown to be solvable on the Hanan grid; this problem has natural applications in VLSI design routing. Finally, we give similar results for other rectilinear problems. © 2001 John Wiley & Sons, Inc.
Long‐term culture of mouse cortical neurons as a model for neuronal development, aging, and death
Authors: Lesuisse Christian , Martin Lee J. 
Published: August 2002

AbstractA long‐term cell culture system was used to study maturation, aging, and death of cortical neurons. Mouse cortical neurons were maintained in culture in serum‐free medium (Neurobasal supplemented with B27) for 60 days in vitro (DIV). The levels of several proteins were evaluated by immunoblotting to demonstrate that these neurons matured by developing dendrites and synapses and remained continuously healthy for 60 DIV. During their maturation, cortical neurons showed increased or stable protein expression of glycolytic enzyme, synaptophysin, synapsin IIa, α and β synucleins, and glutamate receptors. Synaptogenesis was prominent during the first 15 days and then synaptic markers remained stable through DIV60. Very early during dendritic development at DIV3, β‐synuclein (but not α‐synuclein) was localized at the base of dendritic growth cones identified by MAP2 and α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole (AMPA) receptor GluR1. In mature neurons, α and β synucleins colocalized in presynaptic axon terminals. Expression of N‐methyl‐D‐aspartate (NMDA) and AMPA receptors preceded the formation of synapses. Glutamate receptors continued to be expressed strongly through DIV60. Cortical neurons aging in vitro displayed a complex profile of protein damage as identified by protein nitration. During cortical neuron aging, some proteins showed increased nitration, while other proteins showed decreased nitration. After exposure to DNA damaging agent, young (DIV5) and old (DIV60) cortical neurons activated apoptosis mechanisms, including caspase‐3 cleavage and poly(ADP)‐ribose polymerase inactivation. We show that cultured mouse cortical neurons can be maintained for long term. Cortical neurons display compartmental changes in the localization of synucleins during maturation in vitro. These neurons sustain protein nitration during aging and exhibit age‐related variations in the biochemistry of neuronal apoptosis. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 9–23, 2002