bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self‐Aggregation of Synthetic Zinc Chlorins Possessing a 13‐Ester‐Carbonyl Group as Chlorosomal Chlorophyll Models
Authors: Kunieda Michio , Tamiaki Hitoshi 
Published: March 2006

AbstractWe have synthesized zinc 31‐hydroxychlorins 1–4 possessing a methoxycarbonyl group at the 13‐position by modifying naturally occurring chlorophyll‐a. Synthetic zinc chlorins 1–4 have three specific substituents, namely 31‐OH, central Zn and 13‐C=O moieties, along the Qy axis, and 1–3 self‐aggregate in an aqueous medium containing Triton X‐100, as do natural bacteriochlorophylls in the main light‐harvesting antennas (chlorosome) of green photosynthetic bacteria. The 13‐methoxycarbonyl group in 1–3 is a prerequisite for such self‐aggregation, while the other methoxycarbonyl groups at the 151‐ and/or 172‐positions are not. This indicates that such a linear situation of these substituents is significant for chlorosomal self‐aggregation of chlorophyllous pigments and also that the 13‐methoxycarbonyl group is an alternative to the 13‐keto‐carbonyl group in natural pigments. Furthermore, the resulting oligomers of 1–3 have fluorescence emission peaks at less than 700 nm, which are considerably more blue‐shifted than previously prepared self‐aggregates of chlorins possessing the 13‐keto‐carbonyl group fixed onto an exo five‐membered ring, and are a new class of artificial light‐harvesting systems. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
CuI/DABCO‐Catalyzed Cross‐Coupling Reactions of Aryl Halides with Arylboronic Acids
Authors: Li Jin‐Heng , Wang De‐Ping 
Published: March 2006

AbstractCuI combined with DABCO (1,4‐diaza‐bicyclo[2.2.2]octane) was developed as an inexpensive and efficient catalytic system for the Suzuki–Miyaura cross‐coupling of aryl halides with arylboronic acids. The couplings between aryl iodides and arylboronic acids catalyzed by catalytic amounts of CuI and DABCO proceeded smoothly in moderate to excellent yields. However, the CuI/DABCO system was less efficient in the reactions of aryl bromides, and a higher reaction temperature was required to improve the yield. For the less activated aryl bromides, a stoichiometric amount of CuI together with TBAB was necessary to obtain satisfactory yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Comparison of GMRES and ORTHOMIN for the black oil model on unstructured grids
Authors: Li Wenjun , Chen Zhangxin , Huan Guanren , Sun Xiuzhen 
Published: March 2006

AbstractThis paper addresses an application of ORTHOMIN and GMRES to petroleum reservoir simulation using the black oil model on unstructured grids. Comparisons between these two algorithms are presented in terms of storage and total flops per restart step. Numerical results indicate that GMRES is faster than ORTHOMIN for all tested petroleum reservoir problems, particularly for large scale problems. The control volume function approximation method is utilized in the discretization of the governing equations of the black oil model. This method can accurately approximate both the pressure and velocity in the simulation of multiphase flow in porous media, effectively reduce grid orientation effects, and be easily applied to arbitrarily shaped control volumes. It is particularly suitable for hybrid grid reservoir simulation. Copyright © 2006 John Wiley & Sons, Ltd.
Possible involvement of increase in spinal fibronectin following peripheral nerve injury in upregulation of microglial P2X4, a key molecule for mechanical allodynia
Authors: Nasu‐Tada Kaoru , Koizumi Schuichi , Tsuda Makoto , Kunifusa Emiko , Inoue Kazuhide 
Published: March 2006

AbstractWe have recently demonstrated that the P2X4receptor, an ATP‐gated cation channel, in spinal microglia is a key molecule that mediates the mechanical allodynia induced by peripheral nerve injury. Although microglial P2X4receptor expression is increased after peripheral nerve injury, the molecular mechanism(s) underlying its upregulation remains largely unknown. Fibronectin is a member of the extracellular matrix molecules and is actively produced in response to injury and diseases in the CNS. Here, we describe the influence of fibronectin on P2X4receptor expression in microglia and the upregulation of fibronectin after peripheral nerve injury. Microglia that were cultured on fibronectin‐coated dishes showed a marked increase in P2X4receptor expression, both at the mRNA and protein levels, as compared to those cultured on control dishes. Fibronectin also enhanced the microglial Ca2+responses mediated by P2X4receptors. Moreover, Western blot examination of the spinal cord from a rat with spinal nerve injury indicated that fibronectin was upregulated on the ipsilateral side. Interestingly, intrathecal injection of ATP‐stimulated microglia to the rat lumber spinal cord revealed that microglia cultured on fibronectin‐coated dishes was more effective in the induction of allodynia than microglia cultured on control dishes. Taken together, our results suggest that spinal fibronectin is elevated after the peripheral nerve injury and it may be involved in the upregulation of the P2X4receptor in microglia, which leads to the induction of neuropathic pain. © 2006 Wiley‐Liss, Inc.
Computational study of ground‐state chiral induction in small peptides: Comparison of the relative stability of selected amino acid dimers and oligomers in homochiral and heterochiral combinations
Authors: Zhou Yu , Oostenbrink Chris , Jongejan Aldo , Van Gunsteren Wilfred F. , Hagen Wilfred R. , De Leeuw Simon W. , Jongejan Jaap A. 
Published: March 2006

AbstractThe relative stabilities of homochiral and heterochiral forms of selected dipeptides, AA, AS, AC, AV, AF, AD, AK, tripeptides, AAA, AVA, and an acetylpentapeptide, AcGLSFA, have been calculated using thermodynamic integration protocols and the GROMOS 53A6 force field. Integration pathways have been designed that produce minimal disturbance to the system, including the use of soft atoms, low‐energy intermediates, and chiral inversion of the smaller amino acid in the peptide. Comparison of the results obtained by thermodynamic integration between the diastereomeric forms (in explicit water, at 300 K) and from exhaustive global minimum‐energy searches for the individual dipeptides (implicit water, ε = 78, 0 K) suggests that entropic contributions to the relative stability of the chiral forms are important. This conclusion is supported by the results of explicit calculation of the effect of temperature on the relative stability of alanylvalylalanine diastereomers. The Gibbs free energy calculations predict that at ambient temperature and pressure homochiral dipeptides with small side chains or polar groups in the vicinity of the peptide backbone, AA, AS, and AD, are more stable than their heterochiral counterparts by fractions of a kJ/mol. For bigger side chains, AC, AV, AF, and AK, the heterochiral diastereomers appear to be more stable. Predicted relative stabilities are in line with observations reported in the literature for AE and YY. Excellent agreement is found for the calculated and experimentally determined relative stabilities of the diastereomers of the dipeptide AA and of all‐L AcGLSFA and its diastereomer containing D‐serine in the central position. Addition of counterions to the solvent box has no significant effects on charged and neutral forms. From the present findings it would appear unlikely that the intrinsic stability difference between homo‐ and heterochiral dipeptides has been a driving force in a primordial selection process leading to the incorporation of amino acids with a single enantiomeric configuration in natural proteins. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 857–867, 2006
Immune responses to AAV in a phase I study for Canavan disease
Authors: McPhee S. W. J. , Janson C. G. , Li C. , Samulski R. J. , Camp A. S. , Francis J. , Shera D. , Lioutermann L. , Feely M. , Freese A. , Leone P. 
Published: March 2006

AbstractBackgroundCanavan disease is a rare leukodystrophy with no current treatment. rAAV‐ASPA has been developed for gene delivery to the central nervous system (CNS) for Canavan disease. This study represents the first use of a viral vector in an attempt to ameliorate a neurodegenerative disorder.MethodsSubjects received intracranial infusions via six cranial burr holes. Adeno‐associated virus, serotype 2 (AAV2), mediated intraparenchymal delivery of the human aspartoacylase cDNA at a maximum dose of 1 × 1012 vector genomes per subject. The immune response and safety profiles were monitored in the follow‐up of ten subjects.ResultsFollowing rAAV2 administration, we found no evidence of AAV2 neutralizing antibody titers in serum for the majority of subjects tested (7/10). In a subset (3/10) of subjects, low to moderately high levels of AAV2 neutralizing antibody with respect to baseline were detected. In all subjects, there were minimal systemic signs of inflammation or immune stimulation. In subjects with catheter access to the brain lateral ventricle, cerebrospinal fluid was examined and there was a complete absence of neutralizing antibody titers with no overt signs of brain inflammation.ConclusionsrAAV2 vector administration to the human CNS appears well tolerated. The low levels of immune response to AAV2 detected in 3/10 subjects in this study suggest at this dose and with intraparenchymal administration this approach is relatively safe. Long‐term monitoring of subjects and expansion to phase II/III will be necessary in order to make definitive statements on safety and efficacy. Copyright © 2006 John Wiley & Sons, Ltd.
Simultaneous determination of spironolactone and its active metabolite canrenone in human plasma by HPLC‐APCI‐MS
Authors: Dong Haijuan , Xu Fengguo , Zhang Zunjian , Tian Yuan , Chen Yun 
Published: March 2006

AbstractA sensitive and specific liquid chromatography‐atmospheric pressure chemical ionization‐mass spectrometry (LC‐APCI‐MS) method for the simultaneous determination of spironolactone and its active metabolite canrenone in human plasma has been developed and validated. After the addition of estazolam as the internal standard (IS), plasma samples were extracted with methylene chloride : ethyl acetate mixture (20 : 80, v/v) and separated by high‐performance liquid chromatography (HPLC) on a reversed‐phase C18 column with a mobile phase of methanol–water (57 : 43, v/v). Analytes were determined in a single quadrupole mass spectrometer using an atmospheric pressure chemical ionization (APCI) source. LC‐APCI‐MS was performed in the selected‐ion monitoring (SIM) mode using target ions at m/z 341.25 for spironolactone and canrenone, m/z 295.05 for estazolam. The method was proved to be sensitive and specific by testing six different plasma batches. Calibration curves of spironolactone and canrenone were linear over the range 2–300 ng/ml. The within‐ and between‐batch precisions (relative standard deviation (RSD)%) were lower than 10% and the accuracy ranged from 85 to 115%. The lower limit of quantification (LLOQ) was identifiable and reproducible at 2 ng/ml. The proposed method was successfully applied to study the pharmacokinetics of spironolactone and its major metabolite in healthy male Chinese volunteers. Copyright © 2006 John Wiley & Sons, Ltd.
Derivatisation of arginine residues with malondialdehyde for the analysis of peptides and protein digests by LC‐ESI‐MS/MS
Authors: Foettinger Alexandra , Leitner Alexander , Lindner Wolfgang 
Published: March 2006

AbstractIn this study a selective tagging strategy for the derivatisation of arginine residues in peptides is presented. It is based on the reaction of the guanidine group of the arginine side‐chain with malondialdehyde (MDA) under strongly acidic conditions, in which a stable pyrimidine ring is formed. The reaction conditions have been optimised so that quantitative modification can be achieved for a variety of peptides.The label has a strong influence on the polarity and basicity of the arginine side‐chain and thus on the chromatographic and mass spectrometric properties of arginine‐containing peptides. For example, retention, particularly of small and polar peptides as well as arginine‐rich peptides, is significantly increased by derivatisation, and therefore sensitivity is also enhanced in liquid chromatography‐mass spectrometry (LC‐MS). The arginine side‐chain also has a strong impact on the fragmentation behaviour of peptides in tandem mass spectrometry. This has been investigated for standard peptides for which, in some cases, significantly more fragment ions were formed after derivatisation. Finally, the method was tested for tryptic digests of standard proteins to demonstrate how the tagging strategy can give improved or complementary information for protein identification. Copyright © 2006 John Wiley & Sons, Ltd.
Absolute quantification of Atlantic salmon and rainbow trout vitellogenin by the ‘signature peptide’ approach using electrospray ionization QqToF tandem mass spectrometry
Authors: Cohen Alejandro M. , Mansour Atef A. H. , Banoub Joseph H. 
Published: March 2006

AbstractIn this work, we present a simple method for absolute quantification of plasma vitellogenin from both rainbow trout and Atlantic salmon. Plasma samples obtained from control and β‐estradiol induced fish were digested with trypsin. A characteristic ‘signature peptide’ was selected and analyzed by high performance liquid chromatography (HPLC) coupled to an electrospray quadrupole‐time‐of‐flight tandem mass spectrometer, using a deuterated homolog peptide as an internal standard. The hybrid tandem mass spectrometer was operated in a ‘pseudo’ selected reaction‐monitoring mode in which three diagnostic product ions were monitored for identification and quantification purposes. The reproducibility (coefficient of variation ∼5%) and sensitivity (limit of quantification (LOQ) of 0.009 mg/ml) achieved by this simple assay allow it to be considered as an alternative to immunological assays. Copyright © 2006 John Wiley & Sons, Ltd.
Toll‐like receptors in central nervous system glial inflammation and homeostasis
Authors: Kielian Tammy 
Published: March 2006

AbstractToll‐like receptors (TLRs) are a family of pattern‐recognition receptors expressed on cells of the innate immune system that allow for the recognition of conserved structural motifs on a wide array of pathogens, referred to as pathogen‐associated molecular patterns, as well as some endogenous molecules. The recent emergence of studies examining TLRs in the central nervous system (CNS) indicates that these receptors not only play a role in innate immunity in response to infectious diseases but may also participate in CNS autoimmunity, neurodegeneration, and tissue injury. This review summarizes the experimental evidence demonstrating a role for TLRs in the context of CNS inflammation in both infectious and noninfectious conditions. © 2006 Wiley‐Liss, Inc.
Comprehensive two‐dimensional HPLC to study the interaction of multiple components in Rheum palmatum L. with HSA by coupling a silica‐bonded HSA column to a silica monolithic ODS column
Authors: Hu Lianghai , Li Xin , Feng Shun , Kong Liang , Su Xingye , Chen Xueguo , Qin Feng , Ye Mingliang , Zou Hanfa 
Published: March 2006

AbstractA mode of comprehensive 2‐D LC was developed by coupling a silica‐bonded HSA column to a silica monolithic ODS column. This system combined the affinity property of the HSA column and the high‐speed separation ability of the monolithic ODS column. The affinity chromatography with HSA‐immobilized stationary phase was applied to study the interaction of multiple components in traditional Chinese medicines (TCMs) with HSA according to their affinity to protein in the first dimension. Then the unresolved components retained on the HSA column were further separated on the silica monolithic ODS column in the second dimension. By hyphenating the 2‐D separation system to diode array detector and MS detectors, the UV and molecular weight information of the separated compounds can also be obtained. The developed separation system was applied to analysis of the extract of Rheum palmatum L., a number of low‐abundant components can be separated on a single peak from the HSA column after normalization of peak heights. Six compounds were preliminarily identified according to their UV and MS spectra. It showed that this system was very useful for biological fingerprinting analysis of the components in TCMs and natural products.
Random and Sequential Copolypeptides Containing O‐Phospho‐L‐Threonine and L‐Aspartic Acid; Roles in CaCO3 Biomineralization
Authors: Hayashi Shinya , Ohkawa Kousaku , Yamamoto Hiroyuki 
Published: March 2006

AbstractSummary: The present study describes the synthesis of novel polypeptides containing O‐phospho‐L‐threonine [Thr(PO3H2)] and L‐aspartic acid. Random copolypeptides copoly[Thr(PO3H2)XAspY] (X:Y = 25:75, 50:50, 75:25), were conventionally prepared by copolymerization of Thr(PO3Ph2) N‐carboxyanhydride (NCA) and Asp(OBzl) NCA followed by deprotection of the phenyl and benzyl groups by catalytic hydrogenolysis over PtO2. Polycondensation of the protected peptide p‐nitrophenyl esters [Thr(PO3Ph2)]Z‐Asp(OBzl)‐ONp and subsequent deprotection yielded the sequential polypeptides poly[Thr(PO3H2)Z‐Asp] (Z = 1–4). By using the synthetic polypeptides, their effects on the growth of CaCO3 crystals were examined. In the poly[Thr(PO3H2)Z‐Asp]/CaCO3 systems, brushlike calcite and spherical vaterite were formed, with the former being found at [Ca2+]/[Res] ratios of ≥180, ≥140, ≥120, and ≥100 for Z = 1, 2, 3, and 4, respectively. These results indicate that an increase of Thr(PO3H2) residues in the repetitive unit induces the characteristic brushlike calcite, a fact indicating that Thr(PO3H2) residues can modify the CaCO3 crystal morphology.
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Synthesis of Highly Hydrophilic Polyaniline Nanowires and Sub‐Micro/Nanostructured Dendrites on Poly(propylene) Film Surfaces
Authors: Zhong Wenbin , Chen Xianhong , Liu Shoumei , Wang Yongxin , Yang Wantai 
Published: March 2006

AbstractSummary: Polyaniline (PANI) nanowires and sub‐micro/nanostructured dendrites are synthesized and immobilized on PP‐g‐PAA film surfaces via routine oxidative polymerization of aniline under different conditions, where grafting poly(acrylic acid) (PAA) served as a template and dopant, and SDS as a surfactant. The immobilized PANI enhances the surface hydrophilicity of the poly(propylene) (PP) films, and a superhydrophilic surface is obtained in this way. The mechanism of forming different morphologies of PANI and of correspondingly obtaining a superhydrophilic surface are briefly discussed.FESEM image shows the PANI sub‐micro/nanostructured dendrites immobilized on the surfaces of PP films. The modified surface is highly hydrophilic with a water contact angle of 3°.magnified imageFESEM image shows the PANI sub‐micro/nanostructured dendrites immobilized on the surfaces of PP films. The modified surface is highly hydrophilic with a water contact angle of 3°.
Computational Studies of RAFT Polymerization–Mechanistic Insights and Practical Applications
Authors: Coote Michelle L. , Krenske Elizabeth H. , Izgorodina Ekaterina I. 
Published: March 2006

AbstractSummary: Computational chemistry is a valuable complement to experiments in the study of polymerization processes. This article reviews the contribution of computational chemistry to understanding the kinetics and mechanism of reversible addition fragmentation chain transfer (RAFT) polymerization. Current computational techniques are appraised, showing that barriers and enthalpies can now be calculated with kcal accuracy. The utility of computational data is then demonstrated by showing how the calculated barriers and enthalpies enable appropriate kinetic models to be chosen for RAFT. Further insights are provided by a systematic analysis of structure‐reactivity trends. The development of the first computer‐designed RAFT agent illustrates the practical utility of these investigations.
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Patterning Layered Polymeric Multilayer Films by Room‐Temperature Nanoimprint Lithography
Authors: Lu Yingxi , Hu Wei , Ma Ying , Zhang Lianbin , Sun Junqi , Lu Nan , Shen Jiacong 
Published: March 2006

AbstractSummary: Polyelectrolyte multilayer films of poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) and PAH/poly(sodium 4‐styrenesulfonate) (PSS) based on electrostatic interactions as a driving force are patterned by room‐temperature nanoimprint lithography (RT‐NIL). Under an imprinting pressure of 40 bar for 8 min, well‐defined pattern structures with a line width of ≈330 nm and a separation of ≈413 nm are achieved. Meanwhile, hydrogen‐bonding‐directed multilayer films of poly(vinyl pyrrolidone) (PVPON)/poly(methyl acrylic acid) (PMAA) and poly(4‐vinylpyridine)/PAA can also be patterned in a similar way by RT‐NIL. The successful imprinting of these films originates from the high compressibility and fluidity of the layered polymeric films under high pressure.SEM image of an imprinted (PAH/PAA)*20 film on silicon wafer.magnified imageSEM image of an imprinted (PAH/PAA)*20 film on silicon wafer.
Nanofibrous Membranes Containing Carbon Nanotubes: Electrospun for Redox Enzyme Immobilization
Authors: Wang Zhen‐Gang , Xu Zhi‐Kang , Wan Ling‐Shu , Wu Jian , Innocent Christophe , Seta Patrick 
Published: March 2006

AbstractSummary: Nanofibrous membranes that possess reactive groups are fabricated by the electrospinning process from PANCAA solutions that contain MWCNTs. Field emission scanning electron microscopy is used to evaluate the morphology and diameter of the nanofibers. Potentials for applying these nanofibrous membranes to immobilize redox enzymes by covalent bonding are explored. It is envisaged that the electrospun nanofibrous membranes could provide a large specific area and the MWCNTs could donate/accept electrons for the immobilized redox enzymes. Results indicate that, after blending with MWCNTs, the diameter of the PANCAA nanofiber increases slightly. The PANCAA/MWCNT nanofibrous membranes immobilize more enzymes than that without MWCNTs. Moreover, as the concentration of the MWCNTs increases, the activity of the immobilized catalase is enhanced by about 42%, which is mainly attributed to the promoted electron transfer through charge‐transfer complexes and the π system of MWCNTs.The covalent immobilization of redox enzymes, such as catalase, on a PANCAA/MWCNTs nanofiber.magnified imageThe covalent immobilization of redox enzymes, such as catalase, on a PANCAA/MWCNTs nanofiber.
Field Effect Devices Based on SrTiO3 Gate Dielectrics for the Investigation of Charge Carrier Mobility in Macromolecular Films
Authors: Cassinese Antonio , Barra Mario , Biasiucci Mariano , D'Angelo Pasquale 
Published: March 2006

AbstractField effect devices (FET) allow an exhaustive investigation of the electronic transport properties of innovative semiconductors of interest for new applications in modern electronics. In this contribution, we report on the fabrication and characterization of FET devices where SrTiO3 (STO) single crystals and organic macromolecular compounds, such as doped and undoped polythiophenes, or poly(N‐vinylcarbazole) (PVK), are used as insulating and semiconducting layers, respectively. STO, with εr of about 300, offers the possibility to strongly modulate the charge carrier density in the organic films, thus overcoming the limitations related to the use of more conventional oxides.