bluuebunny/crossref_metadata_2025_split huggingface dataset:
Successful thrombolysis of a partially obstructed bileaflet prosthetic heart valve in the mitral position
Authors: Barbetseas John , Vitalis Michael , Vyssoulis Gregory , Lambrou Spyros , Aggeli Constantina , Marinakis Nicholas , Toutouzas Pavlos 
Published: December 2003

AbstractWe describe the case of a woman who presented with dyspnea of abrupt onset and who had recently undergone replacement of the mitral valve with a bileaflet mechanical prosthesis. Transthoracic echocardiographic examination with spectral Doppler recording of transvalvular blood flow revealed a velocity spectrum consistent with obstruction. Transesophageal echocardiography demonstrated partial obstruction of the prosthetic valve due to immobilization of 1 hemidisc in the closed position. This immobilization was apparently caused by a small mass whose appearance was consistent with that of a thrombus. The patient was successfully treated by intravenous administration of a thrombolytic agent. This case demonstrates the value of transesophageal echocardiography in the selection of candidates for thrombolytic treatment in cases of thrombosis of a left‐sided valve prosthesis. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 32:42–46, 2004
Doppler sonographic indices in diagnosing the nutcracker phenomenon in a hematuric adolescent
Authors: Kavukcu Salih , Kasap Belde , Göktay Yiğit , Seçil Mustafa 
Published: December 2003

AbstractCompression of the left renal vein between the aorta and the superior mesenteric artery, known as the nutcracker phenomenon, may cause gross or microscopic hematuria, pain in the flank, proteinuria, or a combination of these symptoms. We report the case of a hematuric adolescent diagnosed with a high index of suspicion by noninvasive Doppler sonography using the diagnostic indices of Doppler sonography established for adults with hematuria. Compression of the patient's left renal vein at the aortomesenteric portion and dilatation at the hilar portion were visualized by magnetic resonance angiography, which verified the diagnosis. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 32:37–41, 2004
Remnants of the U.S. Civil War and modern consumer behavior
Authors: Shimp Terence A. , Dunn Tracy H. , Klein Jill G. 
Published: December 2003

AbstractThis research introduces a construct termed regional animosity. Regional animosity represents individuals' preference for their own (ingroup) geographic region and incorporates elements of animosity toward people from an outgroup region. The construct emanates from an investigation of the historical divide between the northern and southern regions of the United States. The interrelated theories of social identity, stereotype activation, and consumer animosity provide theoretical rationale for the existence of regional animosity and its role in affecting consumers' evaluative judgments and price sensitivity. Data from three studies demonstrate that research respondents showed strong preference for products/services that originate in their home region. Results further reveal that scores on a scale measuring regional animosity correlated with the extent to which consumers chose products/services from their own region and the degree to which they were willing to pay premium prices to obtain these items. These findings support prior theory in a novel context and implicate a potentially important line of inquiry for future research. © 2004 Wiley Periodicals, Inc.
KATP channel openers: Structure‐activity relationships and therapeutic potential
Authors: Mannhold Raimund 
Published: December 2003

AbstractATP‐sensitive potassium channels (KATP channels) are heteromeric complexes of pore‐forming inwardly rectifying potassium channel subunits and regulatory sulfonylurea receptor subunits. KATP channels were identified in a variety of tissues including muscle cells, pancreatic β‐cells, and various neurons. They are regulated by the intracellular ATP/ADP ratio; ATP induces channel inhibition and MgADP induces channel opening. Functionally, KATP channels provide a means of linking the electrical activity of a cell to its metabolic state. Shortening of the cardiac action potential, smooth muscle relaxation, inhibition of both insulin secretion, and neurotransmitter release are mediated via KATP channels. Given their many physiological functions, KATP channels represent promising drug targets. Sulfonylureas like glibenclamide block KATP channels; they are used in the therapy of type 2 diabetes. Openers of KATP channels (KCOs), for example, relax smooth muscle and induce hypotension. KCOs are chemically heterogeneous and include as different classes as the benzopyrans, cyanoguanidines, thioformamides, thiadiazines, and pyridyl nitrates. Examples for new chemical entities more recently developed as KCOs include cyclobutenediones, dihydropyridine related structures, and tertiary carbinols. © 2003 Wiley Periodicals, Inc. Med Res Rev, 24, No. 2, 213–266, 2004
Multiple acquisitions with global inversion cycling (MAGIC): A multislice technique for vascular‐space‐occupancy dependent fMRI
Authors: Lu Hanzhang , van Zijl Peter C.M. , Hendrikse Jeroen , Golay Xavier 
Published: December 2003

AbstractRecently, a new fMRI technique, termed vascular‐space‐occupancy (VASO), was introduced that uses T1‐based blood nulling to detect cerebral blood volume (CBV) changes during brain activity. However, similar to other T1‐preparation methods, this technique is hampered by the fact that there is only one zero‐crossing on the relaxation curve, presently limiting its application to single‐slice studies. A multislice VASO‐fMRI method is presented that employs a series of nonselective 180° pulses to periodically invert the magnetization and maintain it around zero, while acquiring slices in between. The effects of magnetization transfer and signal contamination by stimulated echoes are discussed. Solutions to reduce the effect of T1‐signal decay as a function of slice number are provided. Phantom data show excellent agreement between experiments and numerical simulations. Multislice VASO‐fMRI images of visual stimulation show effective blood nulling in all slices and appropriate functional activations in all volunteers (n = 4). Magn Reson Med 51:9–15, 2004. © 2003 Wiley‐Liss, Inc.
Extended coverage first‐pass perfusion imaging using slice‐interleaved TSENSE
Authors: Kellman P. , Derbyshire J.A. , Agyeman K.O. , McVeigh E.R. , Arai A.E. 
Published: December 2003

AbstractParallel imaging applied to first‐pass, contrast‐enhanced cardiac MR can yield greater spatial coverage for a fixed temporal resolution. The method combines rate R = 2 acceleration using TSENSE with shot‐to‐shot interleaving of two slices. The √R SNR loss is largely compensated for by a longer effective repetition time (TR) and increased flip angle associated with slice interleaving. In this manner, increased spatial coverage is achieved while comparable or better image quality is maintained. Single‐heartbeat temporal resolution was accomplished with spatial coverage of eight slices at heart rates up to 71 bpm, six slices up to 95 bpm, and four slices up to 143 bpm. Experiments in normal subjects (N = 6) were performed to assess signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) values. Magn Reson Med 51:200–204, 2004. Published 2003 Wiley‐Liss, Inc.
Self‐gated cardiac cine MRI
Authors: Larson Andrew C. , White Richard D. , Laub Gerhard , McVeigh Elliot R. , Li Debiao , Simonetti Orlando P. 
Published: December 2003

AbstractThe need for ECG gating presents many difficulties in cardiac magnetic resonance imaging (CMRI). Real‐time imaging techniques eliminate the need for ECG gating in cine CMRI, but they cannot offer the spatial and temporal resolution provided by segmented acquisition techniques. Previous MR signal‐based techniques have demonstrated an ability to provide cardiac gating information; however, these techniques result in decreased imaging efficiency. The purpose of this work was to develop a new “self‐gated” (SG) acquisition technique that eliminates these efficiency deficits by extracting the motion synchronization signal directly from the same MR signals used for image reconstruction. Three separate strategies are proposed for deriving the SG signal from data acquired using radial k‐space sampling: echo peak magnitude, kymogram, and 2D correlation. The SG techniques were performed on seven normal volunteers. A comparison of the results showed that they provided cine image series with no significant differences in image quality compared to that obtained with conventional ECG gating techniques. SG techniques represent an important practical advance in clinical MRI because they enable the acquisition of high temporal and spatial resolution cardiac cine images without the need for ECG gating and with no loss in imaging efficiency. Magn Reson Med 51:93–102, 2004. © 2003 Wiley‐Liss, Inc.
Frame‐by‐frame PRESS 1H‐MRS of the brain at 3 T: The effects of physiological motion
Authors: Katz‐Brull Rachel , Lenkinski Robert E. 
Published: December 2003

Abstract1H‐MRS at high field has been increasingly utilized to study brain metabolism in healthy and pathological states. The aim of this work was to determine the effects of physiological motion on the results of this exam in the presence of the increased susceptibility differences at high field. Single voxel spectra of various regions in the human brain were acquired using frame‐by‐frame PRESS 1H‐MRS at a 0.5 Hz sampling rate. The frame‐by‐frame variations of the FID phase and the frequency and fractional amplitude variations of the residual water‐signal were analyzed. In the human brain the standard deviations of these variations were 3.9 ± 0.5°, 0.83 ± 0.32 Hz, and 0.028 ± 0.013 of the mean amplitude (n = 15). In a motionless phantom, smaller phase and frequency variations were detected in water‐suppressed acquisitions. However, the end effects of physiological motion on PRESS 1H‐MRS of the brain at 3 T were negligible. Magn Reson Med 51:184–187, 2004. © 2003 Wiley‐Liss, Inc.
Visualization and analysis of white matter structural asymmetry in diffusion tensor MRI data
Authors: Zhang Song , Bastin Mark E. , Laidlaw David H. , Sinha Saurabh , Armitage Paul A. , Deisboeck Thomas S. 
Published: December 2003

AbstractThis work presents a method that permits the characterization, quantification, and 3D visualization of white matter structural information contained within diffusion tensor MR imaging (DT‐MRI) data. In this method, regions within the brain are defined as possessing linear, planar, or spherical diffusion. Visualization of this diffusion metric data is realized by generating streamtube and streamsurface models to represent regions of linear and planar diffusion. Quantification of differences in diffusion anisotropy between different regions of interest (ROIs) is then achieved by analyzing 2D barycentric histograms created from the complete distribution of diffusion metric values measured in each region. In four healthy volunteers, there was only a small degree of asymmetry (ε) in the number of linear, planar, or spherical diffusion voxels between the right and left hemispheres (ε ≃ ± 2%). However, in a patient with a metastatic brain lesion there was marked asymmetry in both linear (ε ≃ −10%) and planar (ε ≃ 5%) diffusion between comparable ipsilateral and contralateral regions, with a significant reduction in the number of linear diffusion voxels and an increase in the number of planar diffusion voxels in the tumor‐bearing hemisphere. These results demonstrate the potential of this approach to characterize brain structure in both healthy and diseased subjects. Magn Reson Med 51:140–147, 2004. © 2003 Wiley‐Liss, Inc.
Increase in left ventricular torsion‐to‐shortening ratio in children with valvular aortic stenosis
Authors: Delhaas Tammo , Kotte Jiska , van der Toorn Annet , Snoep Gabriël , Prinzen Frits W. , Arts Theo 
Published: December 2003

AbstractPerfusion of left ventricular (LV) subendocardium in valvular aortic stenosis (AS) patients is impaired. It was expected that this may lead to a reduction of subendocardial fiber contraction and, consequently, to an increase of LV torsion per amount of ejection. Using MR tagging (MRT), it was investigated whether the torsion‐to‐shortening ratio (TSR) is elevated in valvular AS patients. Six asymptomatic children with valvular AS were investigated using echo Doppler, ECG, exercise test, and MRT. LV torsion and natural strain of the inner diameter were determined from measured tag displacements in two short‐axis slices of the LV. In all AS patients TSR was ∼40% increased (0.62 ± 0.04 rad; mean ± SD) as compared to pediatric (0.44 ± 0.08 rad; n = 5) and adult controls (0.46 ± 0.08 rad; n = 9), indicating subendocardial contractile dysfunction. With other techniques hitherto used this type of dysfunction could not be detected. Magn Reson Med 51:135–139, 2004. © 2003 Wiley‐Liss, Inc.
Simultaneous acquisition of gradient‐echo and asymmetric spin‐echo for single‐shot z‐shim: Z‐SAGA
Authors: Heberlein Keith Arron , Hu Xiaoping 
Published: December 2003

AbstractThis article describes the Z‐SAGA pulse sequence, a technique for recovering susceptibility losses in EPI images for neuroimaging applications. The pulse sequence is based on an asymmetric spin echo EPI sequence and acquires a gradient echo image and an asymmetric spin echo image in a single shot. For one of the images, a z‐shim gradient pulse is applied to compensate for susceptibility‐related field distortions. The two images are combined to form an image with reduced signal loss. This sequence is simple to implement and experimentally demonstrated to be effective for BOLD imaging. Magn Reson Med 51:212–216, 2004. © 2003 Wiley‐Liss, Inc.
Removal of phase artifacts from fMRI data using a Stockwell transform filter improves brain activity detection
Authors: Goodyear Bradley G. , Zhu Hongmei , Brown Robert A. , Mitchell J. Ross 
Published: December 2003

AbstractA novel and automated technique is described for removing fMRI image artifacts resulting from motion outside of the imaging field of view. The technique is based on the Stockwell transform (ST), a mathematical operation that provides the frequency content at each time point within a time‐varying signal. Using this technique, 1D Fourier transforms (FTs) are performed on raw image data to obtain phase profiles. The time series of phase magnitude for each and every point in the phase profile is then subjected to the ST to obtain a time‐frequency spectrum. The temporal location of an artifact is identified based on the magnitude of a frequency component relative to the median magnitude of that frequency's occurrence over all time points. After each artifact frequency is removed by replacing its magnitude with the median magnitude, an inverse ST is applied to regain the MR signal. Brain activity detection within fMRI datasets is improved by significantly reducing image artifacts that overlap anatomical regions of interest. The major advantage of ST‐filtering is that artifact frequencies may be removed within a narrow time‐window, while preserving the frequency information at all other time points. Magn Reson Med 51:16–21, 2004. © 2003 Wiley‐Liss, Inc.
Scalable multichannel MRI data acquisition system
Authors: Bodurka Jerzy , Ledden Patrick J. , van Gelderen Peter , Chu Renxin , de Zwart Jacco A. , Morris Doug , Duyn Jeff H. 
Published: December 2003

AbstractA scalable multichannel digital MRI receiver system was designed to achieve high bandwidth echo‐planar imaging (EPI) acquisitions for applications such as BOLD‐fMRI. The modular system design allows for easy extension to an arbitrary number of channels. A 16‐channel receiver was developed and integrated with a General Electric (GE) Signa 3T VH/3 clinical scanner. Receiver performance was evaluated on phantoms and human volunteers using a custom‐built 16‐element receive‐only brain surface coil array. At an output bandwidth of 1 MHz, a 100% acquisition duty cycle was achieved. Overall system noise figure and dynamic range were better than 0.85 dB and 84 dB, respectively. During repetitive EPI scanning on phantoms, the relative temporal standard deviation of the image intensity time‐course was below 0.2%. As compared to the product birdcage head coil, 16‐channel reception with the custom array yielded a nearly 6‐fold SNR gain in the cerebral cortex and a 1.8‐fold SNR gain in the center of the brain. The excellent system stability combined with the increased sensitivity and SENSE capabilities of 16‐channel coils are expected to significantly benefit and enhance fMRI applications. Magn Reson Med 51:165–171, 2004. Published 2003 Wiley‐Liss, Inc.
Stimuli‐responsive polymers. VII. Photomodulated chiroptical switches: Periodic copolyaramides containing azobenzene, phenylene, and chiral binaphthylene main‐chain linkages
Authors: Jaycox Gary D. 
Published: December 2003

AbstractConformationally restricted copolyaramides containing a combination of 4,4′‐azobenzene, 1,4‐phenylene, and chiral 2,2′‐binaphthylene main‐chain segments exhibit photoresponsive chiroptical behavior stemming from multiple trans‐cis‐isomerization reactions triggered within their polymer backbones. In contrast to their more randomly constructed counterparts, copolymer variants endowed with periodic backbone structures undergo reversible, wavelength‐dependent inversions in their optical rotations in response to multiple ultraviolet‐light/visible‐light illumination cycles. Similar behavior is also observed for a smaller oligomer fitted with a periodic arrangement of its monomer units. In their present forms, the periodic constructs constitute a new class of solution‐based, photomodulated chiroptical switches that may be suitable for applications in a number of emerging technological areas. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 566–577, 2004
Influence of a cationic polyelectrolyte on the inverse micellar region of the ternary system sulfobetaine/water/alcohol
Authors: Koetz J. , Bahnemann J. , Kosmella S. 
Published: December 2003

AbstractThe influence of the cationic polyelectrolyte poly(diallyldimethylammonium chloride) on structure formation in the inverse micellar region (L2 phase) of the ternary system 3 (N,N‐dimethyldodecylammonio)propanesulfonate/alcohol/water has been investigated. Up to a polymer concentration in the aqueous phase of 10 wt %, an isotropic phase still exists. As the chain length of the alcohol component increases, the isotropic phase region is reduced and shifted in direction to the water corner. The isotropic polyelectrolyte‐modified L2 phase of the heptanol‐based microemulsion has been studied in much more detail by means of conductometric, rheological, and differential scanning calorimetry measurements. The polyelectrolyte‐modified microemulsion phase shows a characteristic low shear viscosity and Newtonian flow behavior. The characteristic features of the nonpercolated microemulsion droplets are the low conductivity and the disappearance of bulk water. One can conclude from the experimental data that the individual nonpercolated polyelectrolyte‐stuffed microemulsion droplets are approximately uniform in size. In addition, the area of the polyelectrolyte‐modified inverse microemulsion phase with heptanol and octanol depends on the temperature. This means that the area of the L2 region can be increased by the temperature being increased from room temperature to 40 °C. This behavior can be explained by a change in the bending elasticity of the surface film induced by Coulombic interactions between the functional groups of the polyelectrolyte and the surfactant head groups. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 742–751, 2004
Uniform polymer in synthetic polymer chemistry
Authors: Hatada Koichi , Kitayama Tatsuki , Ute Koichi , Nishiura Takafumi 
Published: December 2003

AbstractThe preparation of uniform polymers and their use in fundamental polymer chemistry are reviewed. A typical method of preparation is a combination of living polymerization and supercritical fluid chromatography separation. Synthetic uniform polymers allow us to solve ambiguous problems in polymer chemistry due to molecular weight distribution and are of significant importance for studies on structure–property relationships. A close inspection of an isotactic uniform chloral oligomer with a symmetrical chemical structure reveals that oligomers are the first examples of stable atropisomers of aldehyde oligomers and that their chiroptical properties are due only to their helical geometries. A molecular‐level understanding of the mechanism and stoichiometry of the association process of polymer molecules is possible only with uniform polymers, and stereocomplex formation between isotactic and syndiotactic poly(methyl methacrylate)s in acetone has vigorously been studied by size exclusion chromatography (SEC) and NMR. End‐functionalized uniform polymers have enabled us to prepare uniform polymer architectures, such as block, graft, comb, and star polymers. A uniform stereoblock poly(methyl methacrylate) with an isotactic (methyl methacrylate)46‐syndiotactic (methyl methacrylate)46 structure shows a single SEC peak in chloroform but three peaks in acetone, which are ascribable to intermolecularly and intramolecularly associated complexes and nonassociated molecules. A three‐arm star polymer with one isotactic chain and two syndiotactic chains shows a peculiar SEC behavior in acetone due to a braid type of intramolecular stereocomplex formation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 416–431, 2004
Modified poly(ϵ‐caprolactone)s and their use for drug‐encapsulating nanoparticles
Authors: Iojoiu Cristina , Hamaide Thierry , Harabagiu Valeria , Simionescu Bogdan C. 
Published: December 2003

AbstractPoly(ϵ‐caprolactone) (PCL)‐polydimethylsiloxane diblock and triblock copolymers and poly(ϵ‐caprolactone‐co‐4‐ethylcaprolactone) random copolymers were prepared through the homogeneously catalyzed coordination anionic polymerization of ϵ‐caprolactone (CL) and the copolymerization of CL with 4‐ethyl‐ϵ‐caprolactone (EtCL) in the presence of hydroxy‐terminated polysiloxanes or allyl alcohol as chain‐transfer agents, respectively. Polysiloxane precursors with hydroxypropyl or hydroxyethyl propyl ether end groups were obtained by the hydrosilation of the appropriate unsaturated alcohol with monofunctional or difunctional hydro‐terminated polysiloxanes of different molecular weights. As proven by differential scanning calorimetry analysis, the presence of siloxane blocks and EtCL units determined the diminished copolymer crystallinity, which was shown by the reduced melting temperatures and enthalpy of fusion with respect to those of pure PCL. Both types of copolymers were found to form, in the presence of a poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) emulsifier, monodisperse and stable nanoparticles able to encapsulate different types of bioactive compounds (Vitamin E and indomethacin). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 689–700, 2004
The discovery of isotactic polypropylene and its impact on pure and applied science
Authors: Corradini Paolo 
Published: December 2003

AbstractThis article recalls some aspects of the fascinating history of the discovery by Giulio Natta and his research group of the stereoselective polymerization of propylene and the understanding of the relationships between structure and properties of semicrystalline polymers. The impact of the discovery of isotactic polypropylene and stereoregular polymers on pure and applied science is briefly outlined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 391–395, 2004