bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐resolution 1H NMR and magic angle spinning NMR spectroscopic investigation of the biochemical effects of 2‐bromoethanamine in intact renal and hepatic tissue
Authors: Garrod S. , Humpher E. , Connor S.C. , Connelly J.C. , Spraul M. , Nicholson J.K. , Holmes E. 
Published: September 2002

AbstractThe metabolic consequences of xenobiotic‐induced toxicity were investigated using high‐resolution magic angle spinning (MAS) NMR spectroscopy of intact tissue. Renal papillary necrosis (RPN) was induced in Sprague‐Dawley rats (n = 12) via a single i.p. dose of 250 mg/kg 2‐bromoethanamine (BEA) hydrobromide. At 2, 4, 6, and 24 h after treatment with BEA, three animals were killed and tissue samples were obtained from liver, renal cortex, and renal medulla. Tissue samples were also removed at 2 and 24 h from matched controls (n = 6). 1H MAS NMR spectroscopic techniques were used to analyze samples of intact tissue (∼10 mg). Decreased levels of nonperturbing renal osmolytes (glycerophosphocholine, betaine, and myo‐inositol) were observed in the renal papilla of BEA‐treated animals at 6 and 24 h postdose (p.d.), concomitant with a relative increase in the tissue concentration of creatine. Increased levels of glutaric acid were found in all tissues studied in BEA‐treated animals at 4 and 6 h p.d., indicating the inhibition of mitochondrial fatty acyl CoA dehydrogenases and mitochondrial dysfunction. Increased levels of trimethylamine‐N‐oxide occurred in the renal cortex at 6 h p.d. Changes in the metabolite profile of liver included an increase in the relative concentrations of triglycerides, lysine, and leucine. The novel application of 1H MAS NMR to the biochemical analysis of intact tissues following a toxic insult highlights the potential of this technique as a toxicological probe in providing a direct link between urinary biomarkers of toxicity and histopathological evaluation of toxicological lesions. Magn Reson Med 45:781–790, 2001. © 2001 Wiley‐Liss, Inc.
Relative changes of cerebral arterial and venous blood volumes during increased cerebral blood flow: Implications for BOLD fMRI
Authors: Lee Sang‐Pil , Duong Timothy Q. , Yang Guang , Iadecola Costantino , Kim Seong‐Gi 
Published: September 2002

AbstractMeasurement of cerebral arterial and venous blood volumes during increased cerebral blood flow can provide important information regarding hemodynamic regulation under normal, pathological, and neuronally active conditions. In particular, the change in venous blood volume induced by neural activity is one critical component of the blood oxygenation level‐dependent (BOLD) signal because BOLD contrast is dependent only on venous blood, not arterial blood. Thus, relative venous and arterial blood volume (rCBV) and cerebral blood flow (rCBF) in α‐chlorolase‐anesthetized rats under hypercapnia were measured by novel diffusion‐weighted 19F NMR following an i.v. administration of intravascular tracer, perfluorocarbons, and continuous arterial spin labeling methods, respectively. The relationship between rCBF and total rCBV during hypercapnia was rCBV(total) = rCBF0.40, which is consistent with previous PET measurement in monkeys. This relationship can be linearized in a CBF range of 50–130 ml/100 g/min as ΔrCBV(total)/ ΔrCBF = 0.31 where ΔrCBV and ΔrCBF represent rCBV and rCBF changes. The average arterial volume fraction was 0.25 at a basal condition with CBF of ∼60 ml/100 g/min and increased up to 0.4 during hypercapnia. The change in venous rCBV was 2‐fold smaller than that of total rCBV (ΔrCBV(vein)/ΔrCBF = 0.15), while the arterial rCBV change was 2.5 times larger than that of total rCBV (ΔrCBV(artery)/ΔrCBF = 0.79). These NMR results were confirmed by vessel diameter measurements with in vivo videomicroscopy. The absolute venous blood volume change contributes up to 36% of the total blood volume change during hypercapnia. Our findings provide a quantitative physiological model of BOLD contrast. Magn Reson Med 45:791–800, 2001. © 2001 Wiley‐Liss, Inc.
Accurate phosphorus metabolite images of the human heart by 3D acquisition‐weighted CSI
Authors: Pohmann Rolf , von Kienlin Markus 
Published: September 2002

AbstractFourier imaging modalities suffer from significant signal contamination between adjacent voxels, especially when the spatial resolution is comparable to the size of the anatomical structures. This contamination can be positive or negative, depending on the spatial response function and the geometry of the object. Such a situation arises in human cardiac 31P chemical shift imaging (CSI). Acquisition‐weighted CSI reduces this contamination substantially, which is demonstrated by comparing conventional CSI to Hanning‐weighted 3D 31P‐CSI experiments in 13 healthy volunteers at 2 T. The nominal spatial resolution and the total number of scans were identical for both experiments. The improved spatial response function of the acquisition‐weighted experiment led to a significantly (P < 0.0001) higher myocardial PCr/ATP ratio (2.05 ± 0.31, mean ± SD, N = 33, corrected for saturation and blood contribution) compared to the conventional CSI experiment (1.60 ± 0.46). This is explained by the absence of negative contamination from skeletal muscle, which also resulted in an increase of the observed SNR (from 5.4 ± 1.4 to 7.2 ± 1.4 for ATP). With acquisition‐weighted CSI, metabolic images with a nominal resolution of 16 ml could be obtained in a measurement time of 30 min. After correction for the inhomogeneous B1 field of the surface coil, these images show uniform ATP distribution in the entire myocardium, including the posterior wall. Magn Reson Med 45:817–826, 2001. © 2001 Wiley‐Liss, Inc.
Direct reconstruction of non‐Cartesian k‐space data using a nonuniform fast Fourier transform
Authors: Sarty Gordon E. , Bennett Raoqiong , Cox Robert W. 
Published: September 2002

AbstractAn algorithm of Dutt and Rokhlin (SIAM J Sci Comput 1993;14:1368–1383) for the computation of a fast Fourier transform (FFT) of nonuniformly‐spaced data samples has been extended to two dimensions for application to MRI image reconstruction. The 2D nonuniform or generalized FFT (GFFT) was applied to the reconstruction of simulated MRI data collected on radially oriented sinusoidal excursions in k‐space (ROSE) and spiral k‐space trajectories. The GFFT was compared to conventional Kaiser‐Bessel kernel convolution regridding reconstruction in terms of image reconstruction quality and speed of computation. Images reconstructed with the GFFT were similar in quality to the Kaiser‐Bessel kernel reconstructions for 2562 pixel image reconstructions, and were more accurate for smaller 642 pixel image reconstructions. Close inspection of the GFFT reveals it to be equivalent to a convolution regridding method with a Gaussian kernel. The Gaussian kernel had been dismissed in earlier literature as nonoptimal compared to the Kaiser‐Bessel kernel, but a theorem for the GFFT, bounding the approximation error, and the results of the numerical experiments presented here show that this dismissal was based on a nonoptimal selection of Gaussian function. Magn Reson Med 45:908–915, 2001. © 2001 Wiley‐Liss, Inc.
Successful treatment of myasthenia gravis with tacrolimus
Authors: Evoli Amelia , Di Schino Chiara , Marsili Francesca , Punzi Chiara 
Published: September 2002

AbstractTacrolimus (FK‐506) is a calcium‐calcineurin inhibitor, successfully used in transplant recipients. We report the successful use of tacrolimus as a single immunosuppressant in a patient who had developed myasthenia gravis (MG) during interferon alpha treatment. In this case, the coexistence of hepatitis C and type 2 diabetes mellitus contraindicated the use of both steroids and azathioprine, and cyclosporine A, although effective, had induced renal failure. Tacrolimus proved to be effective in the treatment of MG, was not significantly hepatotoxic, and was less nephrotoxic than cyclosporine. © 2002 John Wiley & Sons, Inc. Muscle Nerve 25: 111–114, 2002
Neurogenic involvement in a case of oculopharyngeal muscular dystrophy
Authors: Boukriche Yassine , Maisonobe Thierry , Masson Catherine 
Published: September 2002

AbstractWe report the case of a 65‐year‐old man with a 15‐year history of oculopharyngeal muscular dystrophy (OPMD) harboring a (GCG)11 mutation of the poly(A)‐binding protein 2 (PABP2) gene. He developed, early in the course of the disease, a severe chronic axonal neuropathy. Although the primary myopathic origin of the disease appears to be established, a small number of cases of OPMD with neuropathic features have been described. This case raises the question of a possible neurogenic component to this disease and the role of the length of the mutation in phenotype severity. © 2002 John Wiley & Sons, Inc. Muscle Nerve 25: 98–101, 2002
The effects of microscopic tissue parameters on the diffusion weighted magnetic resonance imaging experiment
Authors: Norris David G. 
Published: September 2002

AbstractThis review examines the way in which microscopic tissue parameters can affect MR experiments which are sensitive to diffusion. The interaction between the intra‐ and extravascular as well as that between the intra‐ and extracellular spaces is examined. Susceptibility gradients due to the presence of deoxyhemoglobin can cause diffusion‐induced signal losses which are significant in functional magnetic resonance experiments, particularly at higher main magnetic field strengths. This is also true of the fast response that manifests itself as an early negative signal change in functional magnetic resonance experiments. The fields surrounding paramagnetic vessels are described and the way in which diffusion in these fields contributes to functional signal changes is examined. Flow in the capillary bed can be a confounding factor in experiments which aim to examine the diffusion characteristics of extravascular water. It is potentially also a method for assessing capillary perfusion. The intravoxel incoherent motion experiment is described in terms of how significantly this effect can influence diffusion attenuation curves from water. The major models for describing water diffusion in tissue are presented, as are the main experimental results that have contributed to an understanding of the mechanisms of diffusion contrast. The widely accepted view that changes in the diffusion characteristics are caused by a shift of water to the intracellular space and a concomitant change in extracellular tortuosity is examined critically. More recent experiments that indicate that a reduction in the intracellular diffusion may occur simultaneously with the cell swelling are described and their compatibility with existing models discussed. Copyright © 2001 John Wiley & Sons, Ltd.Abbreviations used:2FDG‐6Pfluor‐2‐deoxyglucose‐6‐phosphateADCapparent diffusion coefficientBOLDblood oxygen level dependentCNScentral nervous systemCSFcerebro spinal fluidDTIdiffusion tensor imagingDWIdiffusion weighted imagingfMRfunctional magnetic resonanceFRfast responseIVCMintravoxel coherent motionIVIMintravoxel incoherent motionMCAOmiddle cerebral artery occlusionMRImagnetic resonance imagingNMDAN‐methyl‐D‐aspartateNMRnuclear magnetic resonancePFGpulsed field gradientrBFregional blood flowSGPshort gradient pulseTEecho time.
Diffusion NMR spectroscopy
Authors: Nicolay Klaas , Braun Kees P. J. , Graaf Robin A. de , Dijkhuizen Rick M. , Kruiskamp Marijn J. 
Published: September 2002

AbstractMR offers unique tools for measuring molecular diffusion. This review focuses on the use of diffusion‐weighted MR spectroscopy (DW‐MRS) to non‐invasively quantitate the translational displacement of endogenous metabolites in intact mammalian tissues. Most of the metabolites that are observed by in vivo MRS are predominantly located in the intracellular compartment. DW‐MRS is of fundamental interest because it enables one to probe the in situ status of the intracellular space from the diffusion characteristics of the metabolites, while at the same time providing information on the intrinsic diffusion properties of the metabolites themselves. Alternative techniques require the introduction of exogenous probe molecules, which involves invasive procedures, and are also unable to measure molecular diffusion in and throughout intact tissues. The length scale of the process(es) probed by MR is in the micrometer range which is of the same order as the dimensions of many intracellular entities. DW‐MRS has been used to estimate the dimensions of the cellular elements that restrict intracellular metabolite diffusion in muscle and nerve tissue. In addition, it has been shown that DW‐MRS can provide novel information on the cellular response to pathophysiological changes in relation to a range of disorders, including ischemia and excitotoxicity of the brain and cancer. Copyright © 2001 John Wiley & Sons, Ltd.
Abbreviations used:

ADC

apparent diffusion coefficient

ADP

adenosine diphosphate

Cho

choline‐containing compounds

DW

diffusion‐weighted

2FDG‐6P

2‐fluoro‐2‐deoxyglucose‐6‐phosphate

geMQC

gradient‐enhanced, multiple‐quantum coherence

NAA

N‐acetylaspartate

PCr

phosphocreatine

PFG

pulsed field gradient

PRESS

point‐resolved spectroscopy

STEAM

stimulated‐echo acquisition mode

tCr

total creatine/phosphocreatine.
Wavelets and related time‐frequency techniques in magnetic resonance spectroscopy
Authors: Antoine J.‐P. , Chauvin C. , Coron A. 
Published: September 2002

AbstractWe survey the various applications in MRS of the wavelet transform and related time‐frequency methods. For the sake of completeness, we first quickly review the mathematical tools needed. Copyright © 2001 John Wiley & Sons, Ltd.
Abbreviations used:

CWT

continuous wavelet transform

DWT

discrete wavelet transform

FT

Fourier transform

WT

wavelet transform

WV

Wignes–Ville.
Dopamine and sensory tissue development in Drosophila melanogaster
Authors: Neckameyer Wendi , O'Donnell Janis , Huang Zhinong , Stark William 
Published: September 2002

AbstractDopamine is an important signaling molecule in the nervous system; it also plays a vital role in the development of diverse non‐neuronal tissues in the fruit fly Drosophila melanogaster. The current study demonstrates that males depleted of dopamine as third instar larvae (via inhibition of the biosynthetic enzyme tyrosine hydroxylase) demonstrated abnormalities in courtship behavior as adults. These defects were suggestive of abnormalities in sensory perception and/or processing. Electroretinograms (ERGs) of eyes from adults depleted of dopamine for 1 day as third instar larvae revealed diminished or absent on‐ and off‐transients. These sensory defects were rescued by the addition of L‐DOPA in conjunction with tyrosine hydroxylase inhibition during the larval stage. Depletion of dopamine in the first or second larval instar was lethal, but this was not due to a general inhibition of proliferative cells. To establish that dopamine was synthesized in tissues destined to become part of the adult sensory apparatus, transgenic lines were generated containing 1 or 4 kb of 5′ upstream sequences from the Drosophila tyrosine hydroxylase gene (DTH) fused to the E. coli β‐galactosidase reporter. The DTH promoters directed expression of the reporter gene in discrete and consistent patterns within the imaginal discs, in addition to the expected expression in gonadal, brain, and cuticular tissues. The β‐galactosidase expression colocalized with tyrosine hydroxylase protein. These results are consistent with a developmental requirement for dopamine in the normal physiology of adult sensory tissues. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 280–294, 2001
Preparation of the first tricoordinate silyl cation
Authors: Lambert Joseph B. , Zhao Yan , Zhang S. Mark 
Published: September 2002

AbstractThe preparation of the first tricoordinate silyl cation was made possible by a sequence of discoveries over a 20 year period. The extremely high electrophilicity of the material required protection from all manner of nucleophiles. Only arenes had sufficiently low nucleophilicity to serve as solvent. Tetrakis(pentafluorophenyl) borate provided the least nucleophilic anion. All manipulations had to be carried out in an inert atmosphere, primarily as protection from moisture. Sterically bulky substituents such as mesityl were needed to protect the cation even from the optimized solvent and anion. The trimesitylsilylium ion was produced from allyltrimesitylsilane by reaction of electrophiles with the allyl double bond and extrusion of the allyl adduct. Copyright © 2001 John Wiley & Sons, Ltd.
Syndiospecific polymerization of styrene catalyzed by CpTiCl2(OR) complexes
Authors: Ma Haiyan , Zhang Yue , Chen Bin , Huang Jiling , Qian Yanlong 
Published: September 2002

AbstractFive new CpTiCl2(OR) alkoxyl‐substituted half‐sandwich complexes, where R was methoxyethyl (1), methoxypropyl (2), methoxyisopropyl (3), o‐methoxyphenyl (4), or tetrahydrofurfuryl (5), were synthesized, characterized, and tested as catalyst precursors for the syndiospecific polymerization of styrene. These precursors were more active than (η5‐cyclopentadienyl)trichlorotitanium (CpTiCl3). The different structures of the alkoxyl ligands affected the activity slightly. When the polymerization was carried out in bulk, all the complexes (1–5) exhibited high activities, even at the low molar ratio of Al/Ti = 300. The syndiotactic polystyrene (s‐PS) percentage of the polymer produced by alkoxyl‐substituted complexes was much higher than that of CpTiCl3. The really active center might be described as [CpTiMe]+ · [MAOX]− · nMAO (where MAO is methylaluminoxane). The normal active species [CpTiMe]+ made up the core and the anion mass [MAOX]− · nMAO surrounded the core and constituted the outer shell circumstance. They activated the syndiospecific polymerization of styrene as a whole. For a high concentration of MAO, the function of the alkoxyl group was weak because of the limited proportion in the outer shell. For a low concentration of MAO, the proportion of alkoxyl ligands in the outer shell increased greatly, and their influence also became significant, as reflected in a higher s‐PS percentage of the obtained polymer. The existence of the additional oxygen atom in the alkoxyl ligand stabilized the active species more effectively; this was reflected in the higher temperature of the maximum activities. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1817–1824, 2001
Homopolymerization and [2 + 4]/[3 + 2] cycloaddition in the reaction of nitroethylene with vinyl ethers
Authors: Shin Won‐Suk , Padias Anne Buyle , Hall, H. K. 
Published: September 2002

AbstractThe reaction of nitroethylene with isobutyl vinyl ether was reinvestigated. In agreement with the report of Kushibiki, Irie, and Hayashi (J Polym Sci Polym Chem Ed 1975, 13, 77), cycloaddition accompanied the anionic homopolymerization of nitroethylene. However, the cycloadduct was not a cyclobutane but a bicyclic oxazolidine, in keeping with the more recent report by Denmark and Hurd (J Org Chem 1998, 63, 3045). Cycloaddition accompanied by the anionic homopolymerization of nitroethylene was general for a series of vinyl and silyl ethers. Mechanistically, the cycloadducts formed by a cis–syn concerted approach of the reactants, whereas a trans–anti approach gave a zwitterionic tetramethylene that initiated anionic homopolymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1886–1891, 2001
Active‐center equilibrium in Ziegler–Natta butadiene polymerization
Authors: Cass Peter , Pratt Kerry , Fairhall Kim , Laslett Bob , Rizzardo Ezio 
Published: September 2002

AbstractThe Ziegler–Natta‐catalyzed polymerization of 1,3‐butadiene was investigated at a low aluminum alkyl/cobalt (Al/Co) ratio using two different soluble catalyst systems: cobalt(II) octanoate/diethylaluminum chloride/water and cobalt(II) octanoate/methylaluminoxane/tert‐butyl chloride. When the active‐center concentration was determined by the number‐average molecular weight technique, it was found that the percentage of active cobalt depended on the Al/Co ratio. Subsequently, an equilibrium reaction was proposed to be Co + 2Al ⇌ CoAl2, where Co is cobalt(II) octanoate, Al is either of the aluminum alkyl‐activator species, and CoAl2 is the active catalyst. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2256–2261, 2001
Synthesis and properties of amorphous blue‐light‐emitting polymers with high glass‐transition temperatures
Authors: Deimede V. , Kallitsis J. K. , Pakula T. 
Published: September 2002

AbstractA series of soluble poly(arylene ether)s containing the phenylphosphine oxide moiety were synthesized by the polymerization of substituted oligophenylene diols with bis(fluorophenyl)phenylphosphine oxide. These amorphous polyethers had well‐defined structures and showed blue photoluminescence combined with good thermal stability, especially when phenyl or ethoxy side groups were used. The glass‐transition temperatures increased when the size of the oligophenylene segment increased from three to five rings or when the length of the alkoxy substituents decreased. Polymers with glass‐transition temperatures up to 270 °C were obtained. The absorption and photoluminescent spectra shifted to longer wavelengths with an increase in the oligophenylene block. A redshift was also observed on photoluminescent spectra in the transition from solution to the solid state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3168–3179, 2001
Helix formation of poly(phenylacetylene) derivatives bearing amino groups at the meta position induced by optically active carboxylic acids
Authors: Maeda Katsuhiro , Okada Seiji , Yashima Eiji , Okamoto Yoshio 
Published: September 2002

AbstractTwo novel phenylacetylene derivatives bearing diethylaminomethyl groups at the meta position on phenyl groups [3‐(N,N‐diethylaminomethyl)phenyl]acetylene (1) and [3,5‐bis(N,N‐diethylaminomethyl)phenyl]acetylene (2) were synthesized and polymerized with [Rh(nbd)Cl]2 (nbd: norbornadiene). Both monomers gave highly cis–transoidal stereoregular polymers that exhibited an induced circular dichroism (ICD) in the UV–visible region, probably because of a prevailing one‐handed helical conformation upon complexation with optically active carboxylic acids such as mandelic acid and lactic acid. The sign of the Cotton effects reflected the absolute configuration of the chiral acids. Therefore, these polymers can be used as a novel probe for determining the configuration of chiral acids. The polymers were stable in the presence of chiral acids in solution. The poly‐1 complexed with chiral acids exhibited a split‐type ICD, whereas the poly‐2 complexed with chiral acids showed a different, non‐split‐type ICD. The ICD pattern of the poly‐1/chiral acids complexes dramatically changed with an increase in the concentration of the chiral acids, thus showing a non‐split‐type ICD similar to those of the poly‐2/chiral acid complexes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3180–3189, 2001