bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic contrast‐enhanced MRI in clinical oncology: Current status and future directions
Authors: Padhani Anwar R. 
Published: October 2002

AbstractDynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) is performed after the administration of intravenous contrast medium to noninvasively access tumor vascular characteristics. DCE‐MRI techniques utilizing low‐molecular‐weight contrast media have successfully made the transition from methodological development to preclinical and clinical validation and are now rapidly becoming mainstream clinical tools. DCE‐MRI using macromolecular contrast medium (MMCM) can also assay microvascular characteristics of human tumor xenografts. MMCM approval for human use will occur soon. The success of both techniques depends on their ability to demonstrate quantitative differences of contrast medium behavior in a variety of tissues. Evidence is mounting that kinetic parameters correlate with immunohistochemical surrogates of tumor angiogenesis, including microvessel density, and with pathologic tumor grade. DCE‐MRI is being applied to monitor the clinical effectiveness of a variety of treatments, including antiangiogenic drugs. Kinetic parameter changes following treatment have correlated with histopathological outcome and patient survival. This article reviews the current clinical status of low‐molecular‐weight DCE‐MRI and reviews the potential of MMCM techniques for evaluating human tumors. Ongoing challenges faced by DCE‐MRI as clinical and research tools will be explored. J. Magn. Reson. Imaging 2002;16:407–422. © 2002 Wiley‐Liss, Inc.
MRI of the tumor microenvironment
Authors: Gillies Robert J. , Raghunand Natarajan , Karczmar Gregory S. , Bhujwalla Zaver M. 
Published: October 2002

AbstractThe microenvironment within tumors is significantly different from that in normal tissues. A major difference is seen in the chaotic vasculature of tumors, which results in unbalanced blood supply and significant perfusion heterogeneities. As a consequence, many regions within tumors are transiently or chronically hypoxic. This exacerbates tumor cells' natural tendency to overproduce acids, resulting in very acidic pH values. The hypoxia and acidity of tumors have important consequences for antitumor therapy and can contribute to the progression of tumors to a more aggressive metastatic phenotype. Over the past decade, techniques have emerged that allow the interrogation of the tumor microenvironment with high resolution and molecularly specific probes. Techniques are available to interrogate perfusion, vascular distribution, pH, and pO2 nondestructively in living tissues with relatively high precision. Studies employing these methods have provided new insights into the causes and consequences of the hostile tumor microenvironment. Furthermore, it is quite exciting that there are emerging techniques that generate tumor image contrast via ill‐defined mechanisms. Elucidation of these mechanisms will yield further insights into the tumor microenvironment. This review attempts to identify techniques and their application to tumor biology, with an emphasis on nuclear magnetic resonance (NMR) approaches. Examples are also discussed using electron MR, optical, and radionuclear imaging techniques. J. Magn. Reson. Imaging 2002;16:430–450. © 2002 Wiley‐Liss, Inc.
In vivo molecular imaging for planning radiation therapy of gliomas: An application of 1H MRSI
Authors: Nelson Sarah J. , Graves Edward , Pirzkall Andrea , Li Xiaojuan , Antiniw Chan Antionette , Vigneron Daniel B. , McKnight Tracy R. 
Published: October 2002

AbstractGliomas are infiltrative lesions that typically have poorly defined margins on conventional magnetic resonance (MR) and computed tomography (CT) images. This presents a considerable challenge for planning radiation and other forms of focal therapy, and introduces the possibility of both under‐treating macroscopic tumor, and over‐treating regions of normal brain tissue. New therapy systems are able to deliver radiation more precisely and accurately to irregular three‐dimensional target volumes, and have placed a premium on definition of the spatial extent of the lesion. Proton MR spectroscopic imaging (H‐MRSI) has been proposed as an in vivo molecular imaging technique that assists in targeting and predicts response to radiation therapy for patients with gliomas. The evidence that supports the use of H‐MRSI for planning radiation treatment is reviewed, together with the technical requirements for implementing data acquisition and analysis procedures in a clinical setting. Although there is room for improvement in the spatial resolution and chemical specificity obtained at the conventional field strength of 1.5 T, there are clear benefits to integrating H‐MRSI into treatment planning and follow‐up examinations. Further work is required to integrate the results of the H‐MRSI examination into the treatment planning workstation, and to improve the quality of the data using more sensitive phased array coils and higher field strength magnets. J. Magn. Reson. Imaging 2002;16:464–476. © 2002 Wiley‐Liss, Inc.
Determination of misoprostol free acid in human breast milk and serum by gas chromatography/negative ion chemical ionization tandem mass spectrometry
Authors: Watzer Bernhard , Seyberth Hannsjörg W. , Schweer Horst 
Published: October 2002

AbstractTo study an expected transition of misoprostol from human blood into breast milk, a novel method for the determination of its active metabolite misoprostol acid (MPA) was developed. MPA was determined in serum and breast milk samples by an isotope dilution assay using gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI‐MS/MS). After addition of (15S)‐15‐methylprostaglandin E2 (15‐methyl‐PGE2) as an internal standard, MPA was extracted from both matrices using a reversed‐phase cartridge. The prostanoids were derivatized with O‐2,3,4,5,6‐pentafluorobenzylhydroxylamine hydrochloride (PFBHA) and 2,3,4,5,6‐pentafluorobenzyl bromide (PFBB) to the pentafluorobenzyl oxime (PFBO)‐pentafluorobenzyl ester (PFB) derivatives. The sample was subjected to thin‐layer chromatography with ethyl acetate–hexane (1 : 1 (v/v)) as the developing solvent. The corresponding zone was extracted. After derivatization to the trimethylsilyl ether, MPA was determined by GC/NICI‐MS/MS using the [molecule (M) − pentafluorobenzyl (PFB)]− ([P]−) ions as precursor in the negative ion chemical ionization mode. The product ions used for quantification were [P − 2TMSOH − C6F5CH2OH]− (MPA) and [P − 2TMSOH − C6F5CH2OH − CO2]−(15‐methyl‐PGE2), respectively. The limit of quantification for MPA was ∼1 pg ml−1 in breast milk and serum samples. The correlation coefficients of the calibration curves for MPA were r > 0.997 in the 0.5–2000 pg ml−1 range for both tested matrices. Copyright © 2002 John Wiley & Sons, Ltd.
Fast time‐domain characterization of finite size microstrip structures
Authors: Aygün K. , Shanker B. , Michielssen E. 
Published: October 2002

AbstractA new fast integral‐equation‐based scheme for analysing electromagnetic transients on finite size microstrip structures is described. The scheme permits the analysis of structures comprised of perfect electrically conducting surfaces and wires along with lossless but potentially inhomogeneous dielectric regions. For typical microstrip structures, the computational complexity of the proposed analysis tool grows asO(NtNsvlog2Nsv), whereNtdenotes the number of time steps in the analysis,Nsv=Ns+Nv, andNsandNvrepresent the number of spatial unknowns that model currents on conducting surfaces/wires/junctions and in penetrable volumes, respectively. This complexity estimate is in stark contrast with that for classical marching‐on‐in‐time solvers, which requireO(NtNsv2) CPU resources. Copyright © 2002 John Wiley & Sons, Ltd.
Neuroprotective effect of estradiol and phytoestrogens on MPP+‐induced cytotoxicity in neuronal PC12 cells
Authors: Gélinas Sylvie , Martinoli Maria‐Grazia 
Published: October 2002

AbstractA large body of experimental evidence supports a role for oxidative stress as a mediator of nerve cell death in Parkinson's disease. To better understand the cellular insult of oxidative stress on dopaminergic neurons, we studied the cytotoxic effect of the 1‐Methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) metabolite, 1‐methyl‐4‐phenyl pyridium (MPP+), on several parameters of cell distress using neuronal PC12 cells. We also measured the level of protein expression for the dopamine transporter and the estrogen receptors α and β. Since estrogens have been reported to prevent neuronal degeneration caused by increased oxidative burden, we investigated the ability of 17β‐estradiol, the stereoisomer 17α‐estradiol, and several phytoestrogens to rescue neuronal PC12 cells submitted to MPP+‐induced cytotoxicity. Our results consistently show a protective effect of 17α‐estradiol, 17β‐estradiol and certain phytoestrogens such as quercetin and resveratrol, in neuronal PC12 cells treated with MPP+. In our cellular paradigm, phytoestrogens coumestrol, genistein, and kaempferol did not revert MPP+‐induced cellular death. By Western blot, we demonstrated that administration of MPP+ alone decrease dopamine transporter expression, while treatments with MPP+ together with 17α‐estradiol, 17β‐estradiol, quercetin, or resveratrol could restore dopamine transporter protein expression to control levels. Moreover, the same treatments did not modulate α estrogen receptor or β estrogen receptor expression. By these studies, we aim to provide more evidence for the involvement of phytoestrogens in the process of neuroprotection and to test our hypothesis that some of these compounds may act as neuroprotective molecules and have a lesser hormonal effect than estrogens. © 2002 Wiley‐Liss, Inc.
Role of reactive oxygen species in hippocampal long‐term potentiation: Contributory or inhibitory?
Authors: Knapp Lauren T. , Klann Eric 
Published: October 2002

AbstractReactive oxygen species (ROS) typically are characterized as molecules involved in neurotoxicity and neurodegeneration. However, recent evidence from both neuronal and nonneuronal cells suggests that ROS also function as small messenger molecules that are normal components of signal transduction cascades during physiological processes. Consistent with this idea, ROS have been shown to be critical for hippocampal long‐term potentiation (LTP), a form of synaptic plasticity widely studied as a cellular substrate for learning and memory. On the other hand, ROS also have been shown to be involved in aging‐related impairment of LTP. This review discusses the evidence supporting the notion that ROS both contribute to normal LTP and are involved in age‐related impairment of LTP. We also discuss possible sources that might be responsible for the production of ROS after the induction of LTP. Finally, we propose a functional ROS continuum to help explain this dichotomy of ROS function in hippocampal LTP. © 2002 Wiley‐Liss, Inc.
ATP‐evoked calcium responses of radial glial (Müller) cells in the postnatal rabbit retina
Authors: Uckermann Ortrud , Grosche Jens , Reichenbach Andreas , Bringmann Andreas 
Published: October 2002

AbstractHere we show that rabbit Müller cell differentiation from radial glial progenitor cells is accompanied by a decreasing capability to respond to specific stimuli (depolarization and extracellular adenosine 5′‐triphosphate [ATP]) with an elevation of intracellular calcium. Intracellular free calcium was recorded in retinal wholemounts from young (postnatal days [P] 2 to 31) and adult rabbits. Images were taken from the nerve fiber/ganglion cell layers where the endfeet of radial glial/ Müller cells can be identified after selective uptake of calcium‐sensitive dyes. The area of responding endfeet was determinded as the percentage of the total area occupied by Müller cell endfeet, as an estimate of the percentage of responding cells. In response to depolarization (50 mM potassium), an increase of intracellular free calcium occurred in 19% of cells from young postnatal retinae (P2–31) but only in 2% from adults. This depolarization‐induced calcium rise was caused both by a calcium influx from extracellular space and by an intracellular calcium release. The latter response was inhibited by the P2 receptor blocker pyridoxal phosphate 6‐azophenyl‐2′,4′‐disulfonic acid (PPADS), indicating that extracellular calcium‐independent ATP release into the extracellular space occurs during retinal depolarization. When extracellular ATP (200 μM) was applied, calcium responses were recorded in 83% of cells from young postnatal retinae (P2–6); in the course of further development, both the percentage of responding cells (7% in retinae from adult rabbits) and the amplitude of the calcium responses decreased. It is concluded that during the differentiation of immature radial glia into mature Müller cells, stimulus‐evoked intracellular calcium signaling mechanisms change. © 2002 Wiley‐Liss, Inc.
Assignments and hydrogen bond sensitivities of UV resonance Raman bands of the C8‐deuterated guanine ring
Authors: Toyama Akira , Fujimoto Naoko , Hanada Naoki , Ono Junko , Yoshimitsu Emiko , Matsubuchi Akiko , Takeuchi Hideo 
Published: October 2002

AbstractIsotope‐edited Raman spectroscopy, a combination of site‐selective isotopic labeling and Raman difference spectroscopy, is a useful method for studying the structure and interaction of individual nucleic acid residues in oligonucleotides. To obtain basic data for applying isotope‐edited Raman spectroscopy to guanine residues, we studied the vibrational modes of UV resonance Raman bands of the C8‐deuterated guanine ring by examining the wavenumber shifts upon seven isotopic substitutions (2‐13C, 2‐15N, 6‐18O, 7‐15N, 8‐13C, 9‐15N and 1′‐13C). The hydrogen bond sensitivities of the Raman bands were also investigated by comparing the Raman spectra recorded in several solvents of different hydrogen bonding properties. Some of the Raman bands were found to be markers of hydrogen bonding at specific donor or acceptor sites on the guanine ring. The Raman bands, which shift on C8‐deuteration, remain in the difference spectrum between the unlabeled and C8‐deuterated guanine rings. Among them, a negative peak around 1525 cm−1 and a strong positive/negative peak pair around 1485/1465 cm−1 serve as markers of hydrogen bonding at N7 and C6O, respectively. Another weak positive/negative peak pair around 1025/1040 cm−1 is sensitive to hydrogen bonding at the proton donor sites (N1—H and N2—H2). The applicability of the hydrogen bond markers has been tested by using a 22‐mer oligonucleotide duplex containing eight guanine residues and its analog in which a single guanine residue is C8‐deuterated. The difference spectrum shows that the hydrogen bonding state of the guanine residue at the labeled position is consistent with the Watson–Crick base pair structure of DNA. Isotope‐edited Raman spectroscopy is a useful tool for studying the hydrogen bonding state of selected guanine residues in oligonucleotides. Copyright © 2002 John Wiley & Sons, Ltd.
Structural phase transitions in [(C2H5)4N]2SiF6: differential scanning calorimetry and Raman studies
Authors: Ouasri A. , Rhandour A. , Dhamelincourt M.‐C. , Dhamelincourt P. , Mazzah A. , Taibi M. 
Published: October 2002

AbstractThree structural phase transitions were observed for a new tetraethylammonium compound, [(C2H5)4N]2SiF6, by means of differential scanning calorimetry. The internal vibrational modes of the [(C2H5)4N]2SiF6 compound were studied at ambient temperature and through the phase transitions with the use of Raman spectroscopy. It was concluded that the observed phase transitions are associated with the dynamics of the system and are of the order–disorder type. Copyright © 2002 John Wiley & Sons, Ltd.
Raman investigation of the low‐temperature phase transition in a liquid crystalline system: terephthalidine‐bis‐heptylaniline (TB7A)
Authors: Singh Ranjan K. , Schluecker S. , Asthana B. P. , Kiefer W. 
Published: October 2002

AbstractRaman spectra of terephthalidine‐bis‐heptylaniline (TB7A) were recorded in the region 1125–1225 cm−1 from room temperature to 10 K at 18 different temperatures. The splitting of the ∼1165 cm−1 band, and the variation of the ratio of integrated intensities of the original band at ∼1165 cm−1 to the new component at 1170/1171 cm−1 reveals a solid modification. The analysis of the temperature dependence of the linewidth was made using Rakov's relation. A logarithmic plot as a function of 1/T gives two straight lines with an abrupt discontinuity, which clearly exhibits a phase transition at about 210 K. The temperature dependence of the linewidth of the ∼1165 cm−1 band was used to characterize this transition. A relatively large variation (∼3 cm−1) of the linewidth on going from 250 to 10 K in TB7A having an odd (n = 7) number of carbon atoms in the alkyl tail compared with those observed (∼1 cm−1) in other homologues having an even (n = 2 or 10) number of carbon atoms in the alkyl tail is a clear demonstration of the even–odd effect. Copyright © 2002 John Wiley & Sons, Ltd.
An extensive non‐destructive and micro‐spectroscopic study of two post‐Byzantine overpainted icons of the 16th century
Authors: Daniilia Sister , Bikiaris Dimitris , Burgio Lucia , Gavala Paulina , Clark Robin J. H. , Chryssoulakis Yannis 
Published: October 2002

AbstractThis work is an extensive study of two post‐Byzantine icons, ‘Our Lady, the Life‐giving Spring’ and ‘Saint Athanasios the Athonite,’ both painted during the 16th century and now kept at Saint Modestos's Church in Kalamitsi, Chalkidiki, Greece. The icons were examined using non‐destructive and microanalytical techniques, namely fluorescence photography under UV light, x‐radiography and optical microscopy, in addition to micro‐Raman and micro‐Fourier transform IR spectroscopy. This study allowed the assessment of the current state of preservation of these icons, revealed prior damage and identified in detail the pigments and materials used in the original paintings and overpaintings. Moreover, it confirmed the usefulness of this approach to the detailed evaluation of icons in general and provided significant structural data on representative portable icons of Cretan‐style religious painting. The palette for the original paintings of the two icons consists of the natural pigments caput mortuum, yellow ochre, carbon black, azurite, green earth, cinnabar, white lead, red lake and copper resinate; egg yolk was used as the binder. By contrast, the rather elementary overpaintings are of low tonality, consisting predominantly of mixtures of minium and carbon black, and also the synthetic pigments ultramarine blue, “chrome green” (Prussian blue + lead chromate), chrome yellow and lithopone. A blend of linseed oil and egg provided the binder for the pigments used. The same artist is understood from art historians to have overpainted both icons at the beginning of the 20th century. Copyright © 2002 John Wiley & Sons, Ltd.
Development of a combined confocal and scanning near‐field Raman microscope for deep UV laser excitation
Authors: Sands H. S. , Demangeot F. , Bonera E. , Webster S. , Bennett R. , Hayward I. P. , Marchi F. , Smith D. A. , Batchelder D. N. 
Published: October 2002

AbstractWe describe the development of a combined confocal and scanning near‐field Raman microscope for operation at deep UV wavelengths. This instrument is based upon a commercially available Raman microscope and enables far‐field and near‐field Raman spectra to be acquired from the same location on a sample. The application of the confocal and scanning near‐field microscopes was demonstrated by studies of CVD diamond films. Copyright © 2002 John Wiley & Sons, Ltd.
Raman and infrared study of (PbO)x(P2O5)(1−x) glasses
Authors: Le Saoût Gwenn , Simon Patrick , Fayon Franck , Blin Annie , Vaills Yann 
Published: October 2002

AbstractThe structure of binary (PbO)x(P2O5)(1−x) glasses was investigated using Raman scattering and infrared spectroscopy, over the compositional range x = 0.5–0.68. The distribution of the phosphate groups (PO2)−, (PO3)2−, (P2O7)4− and (PO4)3−, determined from the simulation of Raman spectra in the 800–1500 cm−1 wavenumber range, indicates a significant disproportionation reaction near the pyrophosphate composition and shows a phosphorus connectivity scheme in the glass structure in agreement with 31P magic angle spinning NMR results. The low‐wavenumber Raman spectra of glasses are discussed in the light of the spectra of crystals. The mode laying in the far‐infrared region and due to lead–oxygen vibrations exhibits a composition‐dependent wavenumber that correlates with bulk glass properties such as glass transition temperature. Copyright © 2002 John Wiley & Sons, Ltd.
Raman spectroscopy of the polyanionic copper(II) minerals buttgenbachite and connellite: implications for studies of ancient copper objects and bronzes
Authors: Frost Ray L. , Williams Peter A. , Martens Wayde , Kloprogge J. Theo 
Published: October 2002

AbstractThe minerals connellite and buttgenbachite, complex hydroxy sulfate and nitrate, respectively, of Cu(II), are rare products formed during the corrosion of bronze and brass objects. Infrared and Raman spectra of buttgenbachite and connellite were obtained at 298 and 77 K using a Raman microprobe in combination with a thermal stage. The Raman spectra show the presence of nitrate, sulfate and chloride in the mineral. Spectra of the hydroxyl‐stretching region are complex with multiple bands being observed. These observations are in agreement with the structure of the minerals in that the nitrate ion occupies two different sites and that six hydroxyl groups are crystallographically independent. Various OH stretching bands are attributed to independent hydroxyl units in the crystal structure and zeolitic water OH stretching modes. Raman spectroscopy is an excellent technique for the identification of these complex minerals and for the determination of the distribution of anions in their structure. Copyright © 2002 John Wiley & Sons, Ltd.
Raman imaging of stress‐induced phase transformation in transparent ZnSe ceramic and sapphire single crystals
Authors: Colomban Philippe , Havel Mickael 
Published: October 2002

AbstractIt is known that the polishing of a material can cause pressure‐induced phase transformation and modify its surface properties. Indentation was used to apply controlled perturbation on optically clear ZnSe ceramics and on α‐alumina single‐crystal wafers. New Raman bands are observed at the periphery and/or the centre of the indented area. Confocal Raman and Rayleigh imaging of the peak intensity, bandwidth and wavenumber shift show complex transformations of the indented area. Peak intensity can be used to map the surface geometry with approximately micrometre resolution. For ZnSe, the new bands (ca 235 and 248 cm−1) are assigned to the phases obtained above 5 and 34 GPa under hydrostatic pressure. Comparison is made with zirconia and corundum crystals. Stress‐induced modifications are observed on the α‐alumina wafer. They seem to be due to an unknown disordered phase rather than to a high remnant stress. The relationship between the Raman parameters and the applied stress is discussed. Copyright © 2002 John Wiley & Sons, Ltd.