bluuebunny/crossref_metadata_2025_split huggingface dataset:
Focal adhesion kinase is required for endothelin‐induced cell cycle progression of cultured astrocytes
Authors: Koyama Yutaka , Yoshioka Yasuhiro , Matsuda Toshio , Baba Akemichi 
Published: June 2003

AbstractWhen the brain is damaged, astrocytes often cause hyperplasia resulting in glial scar formation at the injured sites. Endothelins (ETs) have been shown to be involved in the pathophysiologic responses of astrocytes, including proliferation. In this study, we examined the mechanisms underlying the ET‐induced astrocytic G1/S‐phase cell cycle transition by focusing on focal adhesion kinase (FAK). A transient transfection with wild‐type FAK was followed by an increase in bromodeoxyuridine (BrdU) incorporation into cultured rat astrocytes. The increases in BrdU incorporation induced by 100 nM ET‐1 were not found in astrocytes transfected with dominant‐negative FAK mutants (FRNK and dC14‐FAK). The increases in BrdU incorporation induced by 10 nM phorbol 12‐myristate 13‐acetate (PMA) were not affected by the FAK mutants. Wild‐type FAK did not induce stress fiber formation in cultured astrocytes. The dominant negative FAK mutant dC14‐FAK did not prevent ET‐induced astrocytic stress fiber formation. These results suggest that FAK mediated the astrocytic G1/S cell cycle transition induced by ET‐1 downstream of the cytoskeletal actin reorganization. © 2003 Wiley‐Liss, Inc.
Blockade of A2A adenosine receptors prevents basic fibroblast growth factor‐induced reactive astrogliosis in rat striatal primary astrocytes
Authors: Brambilla Roberta , Cottini Lorenzo , Fumagalli Marta , Ceruti Stefania , Abbracchio Maria P. 
Published: June 2003

AbstractPrevious literature data show that blockade of A2A adenosine receptors via selective antagonists induces protection in various models of neurodegenerative diseases. The mechanisms underlying this effect are still largely unknown. Since it is known that excessive reactive astrogliosis is a factor contributing to cell death in diseases characterized by neurodegenerative events, the present study has been aimed at determining whether selective A2A receptor antagonists can counteract the formation of reactive astrocytes induced in vitro by basic fibroblast growth factor (bFGF), a typical trigger of this reaction. Exposure of primary rat striatal astrocytes to the selective A2A antagonist SCH58261 resulted in concentration‐dependent abolition of bFGF induction of astrogliosis in vitro. This effect could also be reproduced with the chemically unrelated A2A antagonist KW‐6002. The direct activation of A2A adenosine receptors by selective receptor agonists was not sufficient per se to induce astrogliosis, suggesting that the A2A receptor needs to act in concert with other bFGF‐induced genes to trigger the formation of reactive astrocytes. These results provide a mechanism at the basis of the neuroprotection induced by A2A receptor antagonists in models of brain damage and highlight this adenosine receptor subtype as a novel target for the pharmacological modulation of the gliotic reaction. © 2003 Wiley‐Liss, Inc.
Protective role of glucose‐6‐phosphate dehydrogenase activity in the metabolic response of C6 rat glioma cells to polyunsaturated fatty acid exposure
Authors: Ramos Karina Lawrence , Colquhoun Alison 
Published: June 2003

AbstractPolyunsaturated fatty acids (PUFAs) can influence tumor growth and migration, both in vitro and in vivo. The PUFA gamma‐linolenic acid (GLA) has been reported to improve the poor prognosis associated with human gliomas, although its effects at sublethal concentrations on residual cells postsurgery are poorly understood. The study investigated the effects sublethal PUFA doses (90 or 150 μM) may have on rat C6 glioma cell energy metabolism, since an adequate energy supply is essential for cell proliferation, migration, and apoptosis. Of note was the identification of mitochondrial heterogeneity in relation to the mitochondrial membrane potential (MMP), which has been suggested but unproven in previous studies. GLA and eicosapentaenoic acid (EPA) caused significant changes in cellular fatty acid composition and increased the percentage of cells with a low MMP after a 96‐h exposure period. The presence of PUFAs inhibited C6 cell proliferation and migration, although apoptosis was not induced. The protein expression and activity of glucose‐6‐phosphate dehydrogenase was increased after 96‐h incubation with 90 μM GLA and EPA and would allow redox regulation through increased NADPH production, permitting the maintenance of adequate intracellular reduced glutathione concentrations and limiting rates of lipid peroxidation and reactive oxygen species generation. Neither NADP+‐isocitrate dehydrogenase nor NADP+‐malate dehydrogenase activity responded to PUFAs, suggesting it is glucose‐6‐phosphate dehydrogenase that is the principal source of NADPH in C6 cells. These data compliment studies showing that higher concentrations of GLA induced glioma cell death and tumor regression and suggest that GLA treatment could be useful for the inhibition of residual cell proliferation and migration after surgical removal of the tumor mass. © 2003 Wiley‐Liss, Inc.
Service Academies of the United States: Issues of Context, Curriculum, and Assessment
Authors: Forest James JF 
Published: June 2003

AbstractAn overview of the U.S. service academies is followed by a discussion of contextual dimensions that provide a useful framework for understanding the success of West Point's recent curricular and assessment initiatives. Some challenges for the service academies in the twenty‐first century are noted, and suggestions are offered for further research on these unique institutions.
Chemical alteration of tephra in the depositional environment: theoretical stability modelling
Authors: Pollard A. M. , Blockley S. P. E. , Ward K. R. 
Published: June 2003

AbstractThe study of the chemical stability of vitreous material in aqueous media is well‐established. There has to date been little consideration of the implications of variations in the chemical durability of tephra in Quaternary tephrochronology. Chemical alteration can take the form of cationic leaching from the matrix, or complete destruction of the silica network, either of which could constrain the ability to chemically identify distal tephra. Here we apply established models of vitreous durability to the published chemical analyses of a large number of Icelandic tephras in order to predict their relative durabilities under equivalent conditions. This suggests that some important tephras have relatively poor chemical stability, and that rhyolitic tephras are, in general, more stable than basaltic. We conclude that tephras should be expected to show predictable differential chemical stability in the post‐depositional environment. Copyright © 2003 John Wiley & Sons, Ltd.
High‐energy sedimentation, Creag Aoil, Spean Bridge, Scotland: implications for meltwater movement and storage during Loch Lomond Stadial (Younger Dryas) ice retreat
Authors: Russell Andrew J. , Tweed Fiona S. , Harris Tim 
Published: June 2003

AbstractThis paper examines the origin and significance of Loch Lomond Stadial (Younger Dryas) gravel deposits at Creag Aoil, Spean Bridge, Scotland. Sedimentation into ice‐dammed lakes in Glen Roy and Glen Spean associated with shorelines at 260 m, 325 m and 350 m is well‐documented, yet little is known about later, lower level lakes near Spean Bridge. Excavations on the northern flanks of the Lundy Channel revealed exposures into a 35–40 m thickness of sand and gravel. These sediments reflect deposition in a subaqueous environment experiencing repeated short‐lived periods of high‐energy subaerial deposition. Deformation structures within subaqueous deposits are associated with at least two ice‐push events. This study presents new evidence for the existence of ice‐dammed lakes at elevations between 260 m and 113 m and for periodic jökulhlaups draining southwest via the Lundy Channel. Active glacier ice associated with the deposits flowed northwest to southeast, driving meltwater across the Great Glen to the Lundy Channel. Glacier retreat was punctuated by periodic minor readvances. Progressive ice retreat was accompanied by ice thinning, and changes in ice‐flow direction and subglacial meltwater routing. These findings add to knowledge of Loch Lomond Stadial deglaciation around Spean Bridge and have implications for our understanding of lacustrine glacier margins during deglaciation. Copyright © 2003 John Wiley & Sons, Ltd.
Time perspectives on glacial landscape formation—glacial flow chronology at Lac aux Goélands, northeastern Québec, Canada
Authors: Clarhäll Anders , Jansson Krister N. 
Published: June 2003

AbstractWe used mapping from aerial photographs and field investigations around Lac Aux Goélands (Whitegull Lake), northeastern Québec, to establish a glacial flow chronology that involves three different glacial landform systems. We interpret the youngest of these systems as related to the late Wisconsinan deglaciation. This system has an up‐glacier discontinuity that marks a temporal shift from warm‐based subglacial conditions to non‐erosive cold‐based subglacial conditions, whereby older glacial landscapes are preserved in the interior of Québec–Labrador. Furthermore, our results support theories suggesting a northward migrating ice divide to a final position south of Ungava Bay during the final deglaciation. The recognition that a glacial landscape is fragmented and consists of smaller, temporally unrelated units is of considerable significance in understanding ice‐sheet dynamics and patterns of subglacial preservation and destruction. This is because a fragmented landscape implies a fragmented formation history, where formation of subglacial landforms occurred in restricted subglacial zones during restricted time periods. Periods of formation must have been separated by periods of preservation and inhibited subglacial reshaping. Based on estimates of the ice margin retreat velocity and the velocity of the warm‐based inward migrating zone, we suggest that periods of preservation were orders of magnitude longer than periods of subglacial landform formation. Copyright © 2003 John Wiley & Sons, Ltd.
Relict rock glaciers as indicators of Mediterranean palaeoclimate during the Last Glacial Maximum (Late Würmian) in northwest Greece
Authors: Hughes P. D. , Gibbard P. L. , Woodward J. C. 
Published: June 2003

AbstractRelict rock glaciers have been identified and mapped in the high cirques of Mount Tymphi, in the Pindus mountains of northwest Greece. They are periglacial forms and represent the most recent cold‐stage landforms in an area that displays widespread evidence of Pleistocene glaciation. It is likely that these features formed during the Last Glacial Maximum (Late Würmian) as talus rock glaciers, and beneath small cirque glaciers as debris rock glaciers. Comparisons with modern rock glacier–climate relationships suggests mean annual temperatures of ca. 8–9°C lower than present at their time of formation. This temperature reconstruction is in good agreement with recent palaeoclimatic reconstructions for the northern Mediterranean based on a general circulation model. Moreover, as rock glaciers are typical of cold and relatively dry mountain regions, their presence is consistent with palaeobotanical and lake‐level data suggesting a cold and relatively dry climate for the Last Glacial Maximum in Greece. However, the presence of small cirque glaciers above some rock glaciers suggests that although precipitation must have been low enough to preclude glacier extension down to lower altitudes, it was not so low as to inhibit glacier formation entirely. Copyright © 2003 John Wiley & Sons, Ltd.
Observing artificially induced strain: implications for subglacial deformation
Authors: Hiemstra John F. , Rijsdijk Kenneth F. 
Published: June 2003

AbstractBy analysing a series of four successive thin‐sections from a ceramic clay that was subjected to uniaxial compression, we were able to monitor the development of microstructures in a fine‐grained sediment. The artificially induced microstructures, such as unidirectional clay reorientations and linear and circular grain arrangements, are identical to features that have been observed in thin‐sections of subglacially deformed tills, and therefore may be used as representative analogues. We argue that the structures, reflecting slip, planar shear displacements as well as rotational movements, can be explained by assuming a Coulomb‐plastic response to imposed shear. We conclude that sediments subjected to subglacial deformation behave as Coulomb materials, at least during the final stages of the deformation. The present study bridges the gap between field studies, experimental studies and theoretical modelling. The microscopic observations assist in visualising inferred subglacial processes and facilitate up‐ and downscaling between diverse methodological approaches. Copyright © 2003 John Wiley & Sons, Ltd.
Structural phase transitions in [C6H5NH3]2SiF6: differential scanning calorimetry and Raman studies
Authors: Jeghnou H. , Ouasri A. , Rhandour A. , Dhamelincourt M.‐C. , Dhamelincourt P. , Mazzah A. 
Published: July 2003

AbstractPhenylammonium hexafluorosilicate, [C6H5NH3]2SiF6, crystallizes at room temperature in the orthorhombic system with probable space group Pmmm. Two structural phase transitions were detected at 226 and 280 K by means of differential scanning calorimetry and basic thermodynamic data were determined for these transitions. The internal vibrational modes of [C6H5NH3]2SiF6 were studied at room temperature and through the phase transitions by using Raman spectroscopy. These studies indicate that the vibrational state of the phenyl cations is weakly changed during these two phase transitions. Copyright © 2003 John Wiley & Sons, Ltd.
Raman spectroscopy and multivariate curve resolution of concentrated Al2O3–Na2O–H2O solutions
Authors: Schoonover Jon R. , Zhang Shuliang L. , Johnston Cliff T. 
Published: July 2003

AbstractMultivariate curve resolution was applied to a series of Raman spectra for samples representing highly concentrated alkaline aluminate slurries. Factors are extracted that represent the behavior of the dominant chemical species present, including aluminate monomer, aluminate oligomers, water and hydroxide. The analysis is particularly useful in unraveling the numerous overlapping contributions in the ν(OH) region of the spectrum. These extracted factors were further examined by comparing their scores with measured physiochemical properties such as density, relative humidity and molar concentrations of components, weight fractions and water activity. Published in 2003 by John Wiley & Sons, Ltd..
Density functional and vibrational spectroscopic analysis of β‐carotene
Authors: Schlücker S. , Szeghalmi A. , Schmitt M. , Popp J. , Kiefer W. 
Published: July 2003

AbstractWe report a computational study on the structural, energetic and vibrational spectroscopic characteristics of β‐carotene employing density functional theory (DFT). The optimized geometry and the complete vibrational spectrum calculated at the BPW91/6–31G* level, including infrared (IR) intensities and Raman activities, are presented. The centrosymmetric structure of β‐carotene is verified both theoretically and experimentally, by identifying a stable calculated structure with Ci symmetry and the mutually exclusive occurrence of bands in the experimental Fourier transform IR and Raman spectrum, respectively. The calculated vibrational spectra reflect the major characteristic features observed experimentally. Differences in the calculated IR intensities and Raman activities for a few dominant modes of two β‐carotene configuration isomers, the all‐trans and the natural abundant (C6–C7) s‐cis form, are explained qualitatively by the corresponding eigenvectors. At the level of theory employed, s‐cis‐β‐carotene was found to be 8.8 kJ mol−1 more stable than the all‐trans form. Calculations on β‐carotene model systems were performed to separate electronic from steric contributions. The higher stability of s‐cis‐β‐carotene is explained by an energetically favored β‐ionone ring conformation, compensating for its shorter conjugation length in comparison with the all‐trans form. Copyright © 2003 John Wiley & Sons, Ltd.
Lapis lazuli as unexpected blue pigment in Iranian Lâjvardina ceramics
Authors: Colomban Philippe 
Published: July 2003

AbstractRaman analysis of an ancient ewer (Iran, 13th century) belonging to the Lâjvardina blue glazed ceramics shows that the ultramarine colour results from the unexpected deposit of a lazurite‐rich slip at the interface between the body and a cobalt‐containing lime‐rich glaze. This confirms the use of Lâjvard (lapis lazuli) as reported in an old alchemist's treatise (Abû'l Qâsim Kâshâni, 14th century). Copyright © 2003 John Wiley & Sons, Ltd.
Raman measurements in water using a high‐power light‐emitting diode
Authors: Žukauskas A. , Novičkovas A. , Vitta P. , Shur M. S. , Gaska R. 
Published: July 2003

AbstractA low‐noise Raman signal of water at 3300 cm−1 was detected using a blue (465 nm) light‐emitting diode (LED) with an output power of 0.5 W. The linewidth of the LED emission spectrum (800 cm−1) was larger than the intrinsic width of the detected Raman feature (400 cm−1). Nevertheless, the comparison of the Raman spectra from distilled and potable water demonstrated that this novel technique is applicable to the normalization of fluorescence signals in water and water‐based solutions. Copyright © 2003 John Wiley & Sons, Ltd.
Hydration of glutaraldehyde‐fixed pericardium tissue: Raman spectroscopic study
Authors: Jastrzebska Maria , Wrzalik Roman , Kocot Antoni , Zalewska‐Rejdak Justyna , Cwalina Beata 
Published: July 2003

AbstractRaman spectroscopy was applied to investigate changes in the hydration state of chemically modified porcine pericardium tissue. Chemically modified tissues are used in construction of bioprostheses for replacement surgery including dermis, heart valves and blood vessels. The hydration state is a very important factor influencing specific mechanical and immunogenic properties of tissue derived materials. We analysed OH vibrational bands in the Raman spectra measured in the range 3000–3800 cm−1 for native and glutaraldehyde (GA) cross‐linked porcine pericardium tissue. For deuterated samples Raman spectra were measured in the broadened wavenumber range 2100–3800 cm−1. All spectra were deconvoluted using the minimum required three‐Gaussian fit. Peak position, integrated intensity, separation between two main peaks d1–2, integrated Gaussian OH component intensity ratio K = I1/I2 and the integrated intensity fraction R = I/Itotal were determined to analyse changes in Raman OH and OD bands of the collagenous pericardium tissue upon GA treatment. It was found that the formation of collagen–GA cross‐links causes an increase in the total water content of the tissue and an increase in the interaxial distance between collagen triple helices and introduces changes in the hydration shell surrounding the triple helix. Changes in the hydration shell are postulated to consist mainly of more sufficient formation of hexagonal than pentagonal water clusters in the space between two neighbouring triple helices. The OD and OH Raman bands measured for deuterated tissues revealed the changes in the distribution of water molecules in different subunits of collagen fibrils in the cross‐linked pericardium tissue. Copyright © 2003 John Wiley & Sons, Ltd.
Vibrational studies of alkali metal hexatungstates
Authors: Mączka M. , Hanuza J. , Waśkowska A. 
Published: July 2003

AbstractRaman and IR studies of potassium, rubidium and cesium hexatungstate single crystals were performed. Assignments of the observed bands are proposed. These studies confirm that the crystal structure of hexatungstates is related to the hexagonal bronze structure but it contains a large number of W atom vacancies. The vibrational properties of these compounds are similar to those of valence‐balanced hexagonal tungsten bronzes obtained by partial substitution of W atoms by atoms with a lower valence. Copyright © 2003 John Wiley & Sons, Ltd.
Protonation, sol formation and precipitation of poly‐ and oligoanilines
Authors: Gruger A. , El Khalki A. , Colomban Ph. 
Published: July 2003

AbstractRaman spectrometry, UV–visible–near IR and attenuated total reflection IR absorptions are used to analyze the protonation of the emeraldine form of the phenyl/—NH2 end‐capped BQBBa tetramer and of the phenyl/—NH2 end‐capped (BQBB)4a hexadecamere in strong (H2SO4 or HCl), intermediate (CH3COOH) and weak (CH3OH) acids. Evolution of the pristine solution with aqueous dilution and time is analyzed in order to understand the formation of a sol of nanofilaments, which agglomerate and finally precipitate. Water in an acidic solution favors the precipitation of the corresponding emeraldine salt material, i.e. increases the degree of aggregation of the oligomeric species and the aromatic behavior of the rings. The secondary doping effect consists in intercalation of water molecules in the highly aggregated (paramagnetic) species, strongly bound to the oligomeric units and whose removal is always accompanied by elimination of the protonating agent (primary doping). The role of interchain interactions in charge carrier mobility appears more important than that of intrachain behavior. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of a series of sodium molybdate structures by two‐dimensional Raman correlation analysis
Authors: Chae Boknam , Jung Young Mee , Wu Xianglan , Kim Seung Bin 
Published: July 2003

AbstractThis paper demonstrates the use of two‐dimensional (2D) correlation spectroscopy in the characterization of the sodium molybdate structures that include and are intermediate between the hexagonal and orthorhombic forms; this series of sodium molybdates is produced by varying the preparation conditions, particularly the acid concentration and the heat‐treatment temperature. In order to verify the assignments of the vibrational modes of hexagonal sodium molybdate, 2D correlation analysis was applied to the acid concentration‐dependent Raman spectra. We can confirm from 2D Raman correlation analysis that this series of preparation conditions results in a series of sodium molybdates including and intermediate between the hexagonal and orthorhombic forms. Furthermore, 2D Raman correlation analysis elucidates the sequence of the structural transformation of hexagonal sodium molybdate into the orthorhombic form. With progression within the series from the hexagonal to the orthorhombic structures, the intensities of the oxygen–molybdenum stretching bands in sodium molybdate change in the following sequence: 973 cm−1 (terminal OMo in the hexagonal structure, decrease in intensity) → 996 cm−1 (terminal OMo in the orthorhombic structure, increase in intensity) → (897, 881) cm−1 (corner OMo2 in the hexagonal structure, decrease in intensity) → 664 cm−1 (edge OMo3 in the orthorhombic structure, increase in intensity) → 820 cm−1 (corner OMo2 in the orthorhombic structure, increase in intensity) → 692 cm−1 (edge OMo3 in the hexagonal structure, decrease in intensity). This sequence implies that the changes in the corner OMo2 and edge OMo3 structures along the series of sodium molybdates are strongly correlated. Copyright © 2003 John Wiley & Sons, Ltd.