bluuebunny/crossref_metadata_2025_split huggingface dataset:
Butyrate‐treated colonic Caco‐2 cells exhibit defective integrin‐mediated signaling together with increased apoptosis and differentiation
Authors: Lévy Peggy , Robin Hélène , Bertrand France , Kornprobst Michel , Capeau Jacqueline 
Published: October 2003

AbstractWe previously reported that the enterocytic differentiation of human colonic Caco‐2 cells correlated with alterations in integrin signaling. We now investigated whether differentiation and apoptosis of Caco‐2 cells induced by the short‐chain fatty acid butyrate (NaBT) was associated with alterations in the integrin‐mediated signaling pathway with special interest in the expression and activity of focal adhesion kinase (FAK), of the downstream phosphatidylinositol 3′‐kinase (PI 3‐kinase)–Akt pathway and in the role of the nuclear factor κB (NF‐κB). NaBT increased the level of sucrase. It induced apoptosis as shown by: (1) decreased Bcl‐2 and Bcl‐XL proteins and increased Bax protein; (2) activation of caspase‐3; and (3) increased shedding of apoptotic cells in the medium. This effect was associated with defective integrin‐mediated signaling as shown by: (1) down‐regulation of β1 integrin expression; 2) decreased FAK expression and tyrosine phosphorylation; (3) concerted alterations in cytoskeletal and structural focal adhesions proteins (talin, ezrin); and (4) decreased FAK ability to associate with PI 3‐kinase. However, in Caco‐2 cells, β1‐mediated signaling failed to be activated downstream of FAK and PI 3‐kinase at the level of Akt. Transfection studies show that NaBT treatment of Caco‐2 cells promoted a significant activation of the NF‐κB which was probably involved in the NaBT‐induced apoptosis. Our results indicate that the prodifferentiating agent NaBT induced apoptosis of Caco‐2 cells probably through NF‐κB activation together with a defective β1 integrin‐FAK‐PI 3‐kinase pathways signaling. J. Cell. Physiol. 197: 336–347, 2003© 2003 Wiley‐Liss, Inc.
Role of Rho in rabbit parietal cell
Authors: Tashiro Keiichiro , Nagao Taku , Kurose Hitoshi , Ichijo Hidenori , Urushidani Tetsuro 
Published: October 2003

AbstractRho is known as an important regulator of actin microfilament formation. We were led to study it because a dynamic rearrangement of actin filaments occurs during activation of gastric acid secretion. In order to use specific probes, the rabbit gastric gland culture system was employed and the various genes were expressed using adenovirus vector. When the constitutive active mutant of Rho (RhoAV14) was expressed, histamine‐ or carbachol‐stimulated acid secretion monitored by 14C‐aminopyrine accumulation was inhibited. Conversely, expression of C3 toxin, the specific inhibitor of Rho, and expression of G12/13‐specific regulator of G‐protein signaling domain, the specific inhibitor of G12/13 which is considered to be an upstream mediator of Rho, both potentiated acid secretion stimulated by the agonists. F‐actin staining of parietal cell expressing RhoAV14 revealed that the microfilament supporting the intracellular canaliculi (not on the basolateral membrane) almost disappeared. No clear changes in the intracellular localization of Rho were observed during stimulation of parietal cell. In resting glands, the endogenous active form of Rho was relatively high, and it decreased during histamine stimulation. The finding that any treatment which inhibit Rho augment acid secretion whereas those that activate Rho inhibit secretion strongly suggests that the Rho‐pathway conducts a negatively regulating signal in parietal cell activation, possibly via site‐specific regulation of actin microfilaments. J. Cell. Physiol. 197: 409–417, 2003© 2003 Wiley‐Liss, Inc.
JS‐K, a novel non‐ionic diazeniumdiolate derivative, inhibits Hep 3B hepatoma cell growth and induces c‐Jun phosphorylation via multiple MAP kinase pathways
Authors: Ren Zhenggang , Kar Siddhartha , Wang Ziqiu , Wang Meifang , Saavedra Joseph E. , Carr Brian I. 
Published: October 2003

AbstractJS‐K, a non‐ionic diazeniumdiolate derivative, is capable of arylating nucleophiles and spontaneously generating nitric oxide (NO) at physiological pH. This recently synthesized low molecular weight compound is shown here to be an inhibitor of cell growth with concomitant activation of mitogen‐activated protein kinase (MAPK) members ERK, JNK, and p38 and their downstream effectors c‐Jun and AP‐1. Inhibitors of these MAPK pathways abrogated the growth inhibitory actions of JS‐K. In addition to the well‐described actions of JNK as a kinase for c‐Jun, we show that c‐Jun is also an ERK target. Furthermore, JS‐K generated NO in culture and NO inhibitors antagonized both MAPK induction and the growth inhibitory effects of JS‐K. These results suggest two possible mechanisms for the mediation of JS‐K growth inhibitory actions, namely NO‐induction of MAPK pathway constituents as well as possible arylation reactions. The data support the idea that prolonged MAPK activation by JS‐K action is important in mediating its growth‐inhibitory actions. JS‐K thus represents a promising platform for novel growth inhibitory analog synthesis. J. Cell. Physiol. 197: 426–434, 2003© 2003 Wiley‐Liss, Inc.
Water storage, surface, and structural properties of sandy forest humus horizons
Authors: Hajnos Mieczyslaw , Jozefaciuk Grzegorz , Sokołowska Zofia , Greiffenhagen Andreas , Wessolek Gerd 
Published: October 2003

AbstractIn this paper, we tried to find interrelations between water retention properties, surface characteristics, and structural features of sandy soils rich in organic matter. Raw humic, epihumic, and endohumic horizons of four acidic sandy forest soils were selected for this study. Specific areas and water adsorption energies were estimated from water vapor adsorption isotherms, micropore (nanometer range) parameters from desorption isotherms, mesopore (micrometer range) parameters from mercury intrusion porosimetry, and macropore (millimeter range) parameters from water retention curves measured using combined suction plate and pressure chamber methods. In the studied soils, pore volumes in all pore ranges were proportional to soil organic matter content. Thin column wicking technique was used to determine migration velocity vs. time dependence in the samples beds for a range of liquids of various surface tensions. From these dependencies the surface free energy and its components were estimated that were used for calculation of water contact angles and forces of interparticle interaction via a water meniscus. The dominant interactions in the studied soils were dispersive Lifshitz‐Van der Waals forces. In the two upper horizons polar acid‐base interactions were absent, however in the deepest horizons, high input of polar interactions occurred, due practically to electron‐donor component of the surface free energy. The electron‐acceptor contribution was low. The wettability of the soils was low in upper horizons as indicated by high water contact angles.
Raman spectroscopic study of the vivianite arsenate minerals
Authors: Frost Ray L. , Martens Wayde , Williams Peter A. , Kloprogge J. Theo 
Published: October 2003

AbstractThe molecular structures of the vivianite‐type arsenate minerals were studied using a combination of Raman and infrared spectroscopy. The Raman spectra of the hydroxyl‐stretching regions are complex with overlapping bands at 3419, 3209, 3185 and 3010 cm−1. This complexity is reflected in the water HOH bending modes with strong infrared bands in the 1660–1685 cm−1 region indicating strong hydrogen bonding to arsenate anions in adjacent layers. The Raman arsenate AsO stretching region shows strong similarity between the vivianite arsenate minerals. In the infrared spectra complexity exists with multiple antisymmetric stretching vibrations observed, indicating a reduction of symmetry. Strong infrared bands around 700 and 560 cm−1 are attributed to librational modes of water. Vibrational spectra enable the structure of the minerals to be determined and, whilst similarities exist in the spectral patterns, sufficient differences exist to determine the identification of the minerals. In particular, Raman spectroscopy assists in the identification of the complex isomorphous substitution in these vivianite arsenate minerals. Copyright © 2003 John Wiley & Sons, Ltd.
Raman spectroscopy of natural oxalates at 298 and 77 K
Authors: Frost Ray L. , Weier Matt L. 
Published: October 2003

AbstractA comparative study of a suite of natural oxalates including weddellite, whewellite, moolooite, humboldtine, glushinskite, natroxalate and oxammite was undertaken using Raman spectroscopy at 298 and 77 K. Oxalates are found as films on host rocks as a result of heavy metal expulsion by primitive plants such as lichens and fungi. The minerals are characterized by the Raman position of the CO stretching vibration, which is cation sensitive. The band is observed at 1468 cm−1 for weddellite, 1464 cm−1 for whewellite, 1489 cm−1 for moolooite, 1489 cm−1 for humboldtine, 1471 cm−1 for glushinskite, 1456 cm−1 for natroxalate and 1473 cm−1 for oxammite. Except for oxammite, the infrared and Raman spectra are mutually exclusive, indicating that the minerals are bidentate and planar. Significant differences are observed in the CC stretching region and in the OCO bending region centred upon 910 and 860 cm−1, respectively. The significance of this work rests with the ability of Raman spectroscopy to identify oxalates which often occur as a film on a host rock. As such, Raman spectroscopy has the potential to identify the existence or pre‐existence of life forms on planets such as Mars. Copyright © 2003 John Wiley & Sons, Ltd.
Pressure effect at room temperature on the low‐energy Raman spectra of nitromethane‐h3 and ‐d3 up to 45 GPa
Authors: Pinan‐Lucarré J.‐P. , Ouillon R. , Canny B. , Pruzan Ph. , Ranson P. 
Published: October 2003

AbstractThe effect of pressure on the lattice dynamics in solid nitromethane, a prototype energetic material, was studied at room temperature using Raman scattering. Experiments were performed on the hydrogenated and perdeuterated compounds in a diamond anvil cell. An assignment of the main peaks of the low‐energy Raman bandshape into groups of modes is proposed. Apart from the splitting of some groups of lattice modes above 7 Gpa, no relevant effects indicating the occurrence of phase transformations were observed. In other words, the solid phase maintains the orthorhombic P212121 symmetry in the pressure range of its chemical stability at room temperature (0.3–30 GPa in nitromethane‐h3 and 0.3–45 GPa in nitromethane‐d3). In contrast with earlier interpretation, the present work suggests that the modifications that were observed on the vibron Raman bandshapes in similar conditions result only from different molecular conformations, without involving a change in the space group symmetry. These conclusions are consistent with recent theoretical simulations of the effects of a uniform or uniaxial strain on solid nitromethane. Copyright © 2003 John Wiley & Sons, Ltd.
Metal dusting of ferritic Fe‐Al‐M‐C (M = Ti, V, Nb, Ta) alloys in CO‐H2‐H2O gas mixtures at 650 °C
Authors: Schneider A. , Zhang J. 
Published: October 2003

AbstractIron aluminides are known for their resistance to high temperature oxidation and sulphidation. Only little information is available about carburisation and metal dusting of Fe‐Al alloys. Metal dusting experiments with Fe‐15Al and Fe‐15Al‐2M‐1C alloys (in at.%) with M = Ti, V, Nb, or Ta were conducted at 650°C in CO‐H2‐H2O gas mixtures with the carbon activity ac = 28. The kinetics of the carbon transfer was measured using thermogravimetric analysis (TGA). It is shown that the mass gain kinetics decreases by adding the alloying elements Nb, Ta, V, or Ti with C. Alloying with titanium and carbon leads to the most significant decreasing effect. The metallographic cross section observation showed a general metal wastage for Fe‐15Al, but local pitting for the Fe‐15Al‐2Nb‐1C and Fe‐15Al‐2Ta‐1C alloys. For the Fe‐15Al‐2V‐1C and Fe‐15Al‐2Ti‐1C alloys no significant attack was observed. Needle‐ or plate‐like Fe3AlCx precipitates were detected in the carburised samples. The existence of this ternary carbide with perovskite structure was predicted by thermodynamic calculations using the software Thermo‐Calc. The morphology of graphite on the surface was analysed by scanning electron microscopy (SEM). Mainly fine filaments with iron containing particles were detected. Cementite was detected in the coke layer by X‐ray diffraction analysis (XRD).
Synthesis of Conjugated Carbazole Trimers and Pentamers by Suzuki Coupling
Authors: Paliulis Osvaldas , Ostrauskaite Jolita , Gaidelis Valentas , Jankauskas Vygintas , Strohriegl Peter 
Published: October 2003

AbstractA series of N‐alkylcarbazol‐3,6‐diyl trimers and pentamers has been synthesized by stepwise Suzuki coupling. The trimers with isopropyl and longer alkyl substituents at the nitrogen atom and all the pentamers form stable glasses with glass transition temperatures varying from 30 to 148 °C for the trimers and 65 to 104 °C for the pentamers. The ionization potential of the N‐alkylcarbazol‐3,6‐diyl trimers is 5.25 eV and 5.20 eV for the pentamers. N‐alkylcarbazol‐3,6‐diyl compounds typically exhibit hole‐drift mobilities in the range of 10−4–10−6 cm2 · V−1 · s−1. The highest hole‐drift mobility observed in an amorphous film of N‐octylcarbazol‐3,6‐diyl pentamer reached 10−3 cm2 · V−1 · s−1 at an applied electric field of 8.1 × 105 V · cm−1.
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Analysis of Crosslinked Styrene‐Butadiene Rubbers by Liquid Chromatography and FT‐IR Spectroscopy, 1
Authors: Pasch Harald , Siewing Anja , Heinz Lars‐Christian 
Published: October 2003

AbstractCrosslinked styrene‐butadiene and butadiene rubbers can efficiently be analyzed by liquid chromatography and FT‐IR spectroscopy. In a first step the vulcanizate is pyrolyzed under mild conditions. The resulting high molar mass fragments are extracted from the bulk material and analyzed by size exclusion chromatography. The molar masses of the extractables are in the range of 3 000 to 25 000 g/mol. The chemical composition as a function of molar mass is visualized by coupled SEC‐FT‐IR spectroscopy. By quantitative analysis of the FT‐IR spectra the concentrations of the different structural units, including styrene, 1,4‐trans‐butadiene, 1,2‐vinylbutadiene, and 1,4‐cis‐butadiene, are determined. It is shown that the chemical composition of the original non‐crosslinked rubbers and the chemical composition of the extractables are rather identical. Therefore, this technique can be used to obtain structural information on rubber formulations even in the case when the material is already vulcanized.SEC chromatograms of SBR 1712 and the extractables after pyrolysis, stationary phase: SDV linear, mobile phase: THF, detector: ELSD.magnified imageSEC chromatograms of SBR 1712 and the extractables after pyrolysis, stationary phase: SDV linear, mobile phase: THF, detector: ELSD.
Dynamic Mechanical and Thermal Properties of Modified Poly(propylene) Wood Fiber Composites
Authors: Hristov Velichko , Vasileva Stefanka 
Published: October 2003

AbstractDynamic mechanical and thermal properties of poly(propylene) (PP)/wood fiber composites have been studied using Dynamic Mechanical Analysis (DMA). In order to modify the PP matrix maleated poly(propylene) (PPMA) and poly(butadiene‐styrene) rubber were used as compatibilizer and impact modifier, respectively. tan δ peak temperature of the compatibilized systems was found to increase in comparison to that of composites without coupling agent, indicating improved adhesion and interaction between PP matrix and wood fibers. The storage modulus (E′)‐temperature (T) relationship of all composites is characterized by two transition points. The E′ of compatibilized composites exhibits higher values than those of the uncompatibilized ones at low temperatures (up to the β‐relaxation). In the temperature interval from β‐transition to 60 °C, the composites containing PPMA have lower modulus, and above 60 °C the E′‐T curves tend to converge. DSC indicates that the wood fibers act as nucleating agent for PP. Maleated poly(propylene) slightly retards the crystallization rate, resulting in a composite structure, composed mainly of large spherulites, with a higher crystallinity index. Fourier Transform Infrared (FT‐IR) microscopy was also applied to explore the interface between wood fibers and PP matrix. The strong absorption band at 1 738 cm−1 in the IR spectrum scanned at the interfacial region between the fiber and matrix indicated that PPMA had probably reacted either by formation of ester bonds or hydrogen bonding with hydroxyl groups from cellulose.Optical micrograph of PPWF composite in polarized light.magnified imageOptical micrograph of PPWF composite in polarized light.
Biodegradations of block copolymers composed of L‐ or D,L‐lactide and six‐membered cyclic carbonates prepared with organolanthanide initiators
Authors: Tsutsumi Chikara , Yamamoto Katsuhiro , Ichimaru Akiko , Nodono Mitsufumi , Nakagawa Katsuhiko , Yasuda Hajime 
Published: October 2003

AbstractDiblock copolymerizations of L‐ or D,L‐lactide (LA) with trimethylene carbonate (TMC) or 2,2‐dimethyltrimethylene carbonate (2,2‐DTMC) with SmMe(C5Me5)2‐(tetrahydrofuran) as an initiator and triblock copolymerizations of L‐ or D,L‐LA/cyclic carbonates/L‐ or D,L‐LA with [Sm(C5Me5)2]2(PhCCCCPh) as an initiator generated the desired block copolymers. This article describes the comparison of biodegradabilities by proteinase K and a compost and mechanical properties between the resulting di‐ or triblock copolymers and random copolymers composed of L‐ or D,L‐LA and cyclic carbonates. The scanning electron microscopic profiles of resulting polymers were measured to understand the morphological change during biodegradation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3572–3588, 2003
Amino alcohol additives for the fast living radical polymerization of methyl methacrylate with RuCl2(PPh3)3
Authors: Ando Tsuyoshi , Sawauchi Chie , Ouchi Makoto , Kamigaito Masami , Sawamoto Mitsuo 
Published: October 2003

AbstractA series of amino alcohols [e.g., R2N(CH2)nOH (R = Me, Et, etc.; n = 2, 3, or 4)] were examined as additives for rate enhancement and finer reaction control in the living radical polymerization of methyl methacrylate with RuCl2(PPh3)3. In general, these additives were more effective in acceleration than the corresponding amines as well as mixtures of an amine and a nonsubstituted alcohol, diamines, or diols. For example, 2‐(diethylamino)ethanol significantly accelerated the polymerization (23 h, 91% at 60 °C) and gave polymers with narrower molecular weight distributions [weight‐average molecular weight/number‐average molecular weight (Mw/Mn) = 1.23], with respect to the system without the additive (550 h, 95%, Mw/Mn ∼ 2.0 at 80 °C; no polymerization at 60 °C). 1H NMR analysis showed the interaction between the amino alcohols and RuCl2(PPh3)3, which apparently formed a more active catalyst. Amino alcohols were also effective in Ru(Ind)Cl(PPh3)2‐catalyzed systems (96% in 8 h at 80 °C). High‐molecular‐weight poly(methyl methacrylate) (Mn ∼ 1.1 × 105) was synthesized with the RuCl2(PPh3)3/2‐(diethylamino)ethanol system, in which the polymerization reached 97% conversion in 4 h. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3597–3605, 2003
Reversible catenation of coordination rings with Pd(II) and/or Pt(II) metal centers: Chirality induction through catenation
Authors: Hori Akiko , Kataoka Hisashi , Akasaka Akihiko , Okano Takashi , Fujita Makoto 
Published: October 2003

AbstractA Pd(II)‐linked coordination ring is reversibly transformed into its catenanted dimer at room temperature through the efficient organic stacking of the component rings. An analogous Pt(II)‐linked ring is also catenated only at high temperature (100 °C), but not at room temperature because of the kinetic inertness of Pt(II)‐ligand interaction. Interestingly, the combination of the Pd(II)‐ and the Pt(II)‐linked coordination rings selectively gives a Pd(II)/Pt(II) cross‐catenane, because the kinetically inert Pt(II) ring can be catenated only via the dissociation of the kinetically labile Pd(II) ring. Planer conformation of the monomer rings is twisted upon catenation, inducing helical chirality in the catenated structure. Thus, induced circular dichroism (ICD) is observed in the catenation when chiral‐1,2‐cyclohexandiamine is attached as a chiral auxiliary on the metal centers. The ICD decreases with increasing temperature due to less effective chiral aromatic stacking at higher temperature. The Pd(II) ring shows higher ICD than the Pt(II) ring, probably due to the more flexible conformation of the Pd(II) ring that can adopt chiral orientation easily. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3478–3485, 2003
Rod–coil block copolymers: An iterative synthetic approach via living free‐radical procedures
Authors: Gopalan Padma , Li Xuefa , Li Mingqi , Ober Christopher K. , Gonzales Chad P. , Hawker Craig J. 
Published: October 2003

AbstractA modular approach has been developed for the synthesis of rod–coil block copolymers involving the initial preparation of a macroinitiator based on the rod block followed by the growth of the coil segment with living free‐radical procedures. The key feature of this strategy is the utilization of an alkoxyamine group from the beginning of the synthesis, which serves as a solubilizing group and ensures that each rod block contains a single initiating fragment. Using this approach permits block copolymers based on insoluble biphenyl ester oligomers to be conveniently prepared with coil segments that range from styrenes to acrylates to 1,3‐dienes. The tendency of the rod segments to crystallize is strongly dependent on the weight fraction of the rod segment and the chemical nature of the coil segment. Rod–coil molecules containing at least 25–35 wt % polystyrene or poly(n‐butyl acrylate) coil segments show a two‐dimensional hexagonal arrangement of rod aggregates, as characterized by transmission electron microscopy and small‐angle X‐ray scattering. Polyisoprene block copolymers exhibit a lamellar microstructure with short rigid domains in which the rod units lie in an interdigitated smectic C arrangement. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3640–3656, 2003
Nucleobase‐induced supramolecular polymerization in the solid state
Authors: Rowan Stuart J. , Suwanmala Phiriyatorn , Sivakova Sona 
Published: October 2003

AbstractSupramolecular polymerization, that is, the self‐assembly of polymer‐like materials through the utilization of the noncovalent bond, has been a developing area of research over the last decade. In this article, we report the synthesis of nucleobase‐terminated (N6‐anisoyl‐adenine and thymine) low‐molecular‐weight poly(tetrahydrofuran) macromonomers (<2000 g mol−1). The adenine‐derived supramolecular telechelic polymer self‐assembled in the solid state to yield materials with film‐ and fiber‐forming capabilities. This material was thermally reversible and exhibited a ceiling temperature, above which a drop in viscosity was observed and fibers could no longer be obtained. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3589–3596, 2003