bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of caffeic acid phenethyl ester against doxorubicin‐induced neuronal oxidant injury
Authors: Fadillioglu Ersin , Erdogan Hasan , Iraz Mustafa , Yagmurca Murat 
Published: October 2003

AbstractOxygen‐derived free radicals have been implicated in the pathogenesis of doxorubicin‐induced toxicities. The aim of this study was to investigate the effects of caffeic acid phenethyl ester (CAPE), an antioxidant agent, on doxorubicin‐induced neuronal oxidative injury in rats. The rats were treated with CAPE (10μmol/kg/day i.p.) or saline starting 2 days before a single dose of doxorubicin (20 mg/kg i.p.) or saline. Ten days after the first experiments, the brain was excised to analyze the activities of antioxidant enzymes and levels of malondialdehyde (MDA) and nitric oxide (NO). Doxorubicin alone resulted in higher MDA level in brain tissue than the other groups. The activity of catalase was higher in doxorubicin plus CAPE group than doxorubicin group. There were no significant differences in NO level, glutathione peroxidase (GSH‐Px) and superoxide dismutase activities between the groups. There were negative correlations between GSG‐Px activity and MDA level in both doxorubicin and doxorubicin plus CAPE groups. It can be concluded that doxorubicin induced oxidant injury can be prevented by CAPE treatment through its antioxidant properties in rat brain.
Comparative neurochemistry of the avian forebrain and striatum: a microdialysis study
Authors: Karakuyu Dilek , Diekamp Bettina , Güntürkün Onur 
Published: October 2003

AbstractThe mammalian and avian striatum are homologous structures, while the mammalian prefrontal cortex (PFC) and the avian neostriatum caudolaterale (NCL) represent functionally equivalent, possibly homoplastic structures. We used brain microdialysis to study basal levels and release mechanisms of dopamine (DA) and serotonin (5‐HT) in the pigeons' forebrain to be able to compare the biochemical characteristics between these structures and different species. Basal DA levels in the pigeons' NCL were different from those in the rats' PFC, but were similar in the striatum. This was converse for 5‐HT. As in mammals, perfusion with artificial cerebrospinal fluid (aCSF) with elevated potassium significantly increased DA levels, whereas calcium‐free aCSF decreased the DA efflux. In summary, the avian and mammalian forebrains show a complex pattern of neurochemical similarities and differences. These data suggest that absolute and relative concentrations of modulatory systems may change considerably over evolutionary time, while basic biochemical mechanismsm stay unaltered.
Novel N‐methylbenzothiazolium salts as hardeners for epoxy and acrylate monomers
Authors: Takahashi Eiji , Sanda Fumio , Yamamoto Takakazu , Endo Takeshi 
Published: October 2003

AbstractNovel N‐methylbenzothiazolium salts [N‐methyl‐2‐benzylthiobenzothiazolium, N‐methyl‐2‐(4‐nitrobenzylthio)benzothiazolium, N‐methyl‐2‐(1‐ethoxycarbonylethylthio)benzothiazolium, and N‐methyl‐2‐methylthiobenzothiazolium hexafluoroantimonates] were synthesized by the reaction of the corresponding 2‐substituted benzothiazole with dimethylsulfate, followed by anion exchange with KSbF6. These benzothiazolium salts cationically polymerized an epoxy monomer by photoirradiation. They also polymerized an acrylate monomer via a photoradical process. The use of aromatic compounds such as 2‐ethyl‐9,10‐dimethoxyanthracene as photosensitizers was effective in enhancing the polymerization. These benzothiazolium salts also served as thermal cationic initiators. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3828–3837, 2003
Macrocycles. XXVIII. Cyclic poly(benzonitrile ether)s derived from bisphenol A
Authors: Kricheldorf Hans R. , Garaleh Mazen , Schwarz Gert 
Published: October 2003

AbstractBisphenol A was polycondensed with 2,6‐dichlorobenzonitrile, 2,6‐difluorobenzonitrile, 2,4‐difluorobenzonitrile, and 3,5‐difluorobenzonitrile in sulfolane. With 2,6‐and 2,4‐difluorobenzonitrile, quantitative conversions were achieved, and matrix‐assisted laser desorption/time‐of‐flight mass spectra revealed a nearly quantitative formation of cyclic oligoethers and polyethers. Furthermore, O,O′‐bistrimethylsilyl bisphenol A was polycondensed with the aforementioned dihalobenzonitriles in dry N‐methylpyrrolidone (promoted by potassium carbonate). Both the temperature and time were optimized. Only with 2,6‐difluorobenzonitrile were nearly quantitative conversions achieved, and this resulted in high molecular weights and high cycle contents. Size exclusion chromatography elution curves exhibited a tendency toward a bimodal character when larger fractions of cycles were present. Calibration with polystyrene standards indicated number‐average molecular weights of up to 105 Da and weight‐average molecular weights of up to 2.3 × 105 Da. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3838–3846, 2003
Synthesis and characterization of hyperbranched aromatic poly(ether imide)s with terminal amino groups
Authors: Chang Yao‐Te , Shu Ching‐Fong , Leu Chyi‐Ming , Wei Kung‐Hwa 
Published: October 2003

AbstractWe synthesized an AB2‐type monomer, 4‐{4‐[di(4‐aminophenyl)methyl]phenoxy}phthalic acid, which contained one phthalic acid group and two aminophenyl functionalities. The direct self‐polycondensation of the AB2‐type monomer in the presence of triphenylphosphite as an activator afforded a hyperbranched poly(ether imide) with a large number of terminal amino groups. This polymer was characterized with 1H NMR and IR spectroscopy. The degree of branching of the hyperbranched poly(ether imide) was approximately 56%, as determined by a combination of model compound studies and an analysis of 1H NMR spectroscopy integration data. The terminal amino groups underwent functionalization readily. The solubility and thermal properties of the resulting polymers depended on the nature of the chain end groups. In addition, the hyperbranched poly(ether imide) was grafted with polyhedral oligomeric silsesquioxane (POSS). Transmission electron microscopy analysis revealed that the grafted POSS molecules aggregated to form a nanocomposite material. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3726–3735, 2003
Synthesis and characterization of poly[phenyl(fluoroalkyloxaalkane)silanediyl]s
Authors: Zuev Vjacheslav V. , Skvortsov Nikolai K. 
Published: October 2003

AbstractMonomeric fluoroalkoxyalkyl(phenyl)dichlorosilanes were synthesized with quantitative yields by hydrosilylation of allyl ethers of fluoroalcohols with phenyldichlorosilane with Pt(Ph3Sb)2Cl2 complex as a catalyst. Starting from these monomers, corresponding polysilanes with weight‐average molecular weights of 2–3 × 104 were obtained by the Wurtz reaction. Increasing the CF2 groups containing two to six monomer units caused the char yields to increase from 3 to 48% at 800 °C in air. The emission characteristics of these polysilanes in a chloroform solution were examined. They had a narrow peak at 344 nm with a small Stokes shift (≈20 nm). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3761–3767, 2003
Crosslinked poly(ester anhydride)s based on poly(ε‐caprolactone) and polylactide oligomers
Authors: Helminen Antti O. , Korhonen Harri , Seppälä Jukka V. 
Published: October 2003

AbstractResorbable poly(ester anhydride) networks based on ε‐caprolactone, L‐lactide, and D,L‐lactide oligomers were synthesized. The ring‐opening polymerization of the monomers yielded hydroxyl telechelic oligomers, which were end‐functionalized with succinic anhydride and reacted with methacrylic anhydride to yield dimethacrylated oligomers containing anhydride bonds. The degree of substitution, determined by 13C NMR, was over 85% for acid functionalization and over 90% for methacrylation. The crosslinking of the oligomers was carried out thermally with dibenzoyl peroxide at 120 °C, leading to polymer networks with glass‐transition temperatures about 10 °C higher than those of the constituent oligomers. In vitro degradation tests, in a phosphate buffer solution (pH 7.0) at 37 °C, revealed a rapid degradation of the networks. Crosslinked polymers based on lactides exhibited high water absorption and complete mass loss in 4 days. In ε‐caprolactone‐based networks, the length of the constituent oligomer determined the degradation: PCL5‐AH, formed from longer poly(ε‐caprolactone) (PCL) blocks, lost only 40% of its mass in 2 weeks, whereas PCL10‐AH, composed of shorter PCL blocks, completely degraded in 2 days. The degradation of PCL10‐AH showed characteristics of surface erosion, as the dimensions of the specimens decreased steadily and, according to Fourier transform infrared, labile anhydride bonds were still present after 90% mass loss. © 2003 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3788–3797, 2003
Dendrimers and other dendritic macromolecules: From building blocks to functional assemblies in nanoscience and nanotechnology
Authors: Fréchet Jean M. J. 
Published: October 2003

AbstractGiven their size, in the single‐digit nanometer range, and the versatility of their functionality, dendrimers and other dendritic macromolecules are poised to make a significant contribution to the rapidly expanding fields of nanoscience and nanotechnology. This highlight focuses on nascent applications of dendrimers that take advantage of their structural features and polyvalent character. In particular, the concept of dendritic encapsulation of function, borrowed from Nature, can be applied to the design of a varied array of energy‐harvesting, light‐emitting, or catalytic macromolecules. Similarly, the compact size and hierarchical ordering of components within dendrimers make them ideal for exploring the limits of nanolithography. Finally, the presence of differentiated functionalities and the polyvalent character of dendrons and dendrimers constitute strong assets for their use in polymer therapeutics. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3713–3725, 2003
Dispersion polymerization of styrene in carbon dioxide stabilized by copolymers of poly(propylene glycol) methacrylate and 2‐(perfluorooctyl)ethyl methacrylate
Authors: Ding Lunhan , Olesik Susan V. 
Published: October 2003

AbstractThe dispersion polymerization of styrene in carbon dioxide with a series of copolymers of poly(propylene glycol) methacrylate (PPGMA) and 2‐(perfluorooctyl)ethyl methacrylate (FOEMA) as the polymerization dispersants was examined. It was demonstrated that PPGMA and FOEMA copolymers and polymers containing 52–100% FOEMA could be used as effective dispersants for the polymerization, and the composition of the copolymeric dispersant had a dramatic effect on both the polymerization yield and the morphology of the resulting polystyrene. The effects of the concentrations of the copolymeric dispersants, the concentrations of the monomer, and the reaction pressure were also investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3804–3815, 2003
Hyperbranched polymers as scaffolds for multifunctional reversible addition–fragmentation chain‐transfer agents: A route to polystyrene‐core‐polyesters and polystyrene‐block‐poly(butyl acrylate)‐core‐polyesters
Authors: Jesberger Martin , Barner Leonie , Stenzel Martina H. , Malmström Eva , Davis Thomas P. , Barner‐Kowollik Christopher 
Published: October 2003

AbstractPolydisperse hyperbranched polyesters were modified for use as novel multifunctional reversible addition–fragmentation chain‐transfer (RAFT) agents. The polyester‐core‐based RAFT agents were subsequently employed to synthesize star polymers of n‐butyl acrylate and styrene with low polydispersity (polydispersity index < 1.3) in a living free‐radical process. Although the polyester‐core‐based RAFT agent mediated polymerization of n‐butyl acrylate displayed a linear evolution of the number‐average molecular weight (Mn) up to high monomer conversions (>70%) and molecular weights [Mn > 140,000 g mol−1, linear poly(methyl methacrylate) equivalents)], the corresponding styrene‐based system reached a maximum molecular weight at low conversions (≈30%, Mn = 45,500 g mol−1, linear polystyrene equivalents). The resulting star polymers were subsequently used as platforms for the preparation of star block copolymers of styrene and n‐butyl acrylate with a polyester core with low polydispersities (polydispersity index < 1.25). The generated polystyrene‐based star polymers were successfully cast into highly regular honeycomb‐structured microarrays. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3847–3861, 2003
Fragmentation pathways of sulphonamides under electrospray tandem mass spectrometric conditions
Authors: Klagkou Katerina , Pullen Frank , Harrison Mark , Organ Andy , Firth Alistair , Langley G. John 
Published: October 2003

AbstractSulphonamides are antibacterial compounds used extensively in farming and veterinary practice. Residues are commonly found in meat and milk. The growing concern about antibiotic resistance of bacteria led to a lowering of the legal concentration limits of sulphonamides in food. A range of analytical methods, employing tandem mass spectrometry (MS/MS) and selected reaction monitoring (SRM), have been developed to allow screening at the limit of detection (LOD) levels. Interest was drawn to the fragment ions produced by the sulphonamides, some involving complex rearrangements that have not previously been looked at. Here we report an investigation into the fragmentation pattern of sulphonamides under electrospray (ES) MS/MS conditions using ion trap and Fourier transform ion cyclotron resonance (FTICR) mass spectrometers. Structures are proposed for the main fragment ions observed for a range of sulphonamides, the effects of the functional groups in the dissociation pathway of the compounds are investigated, and the mechanisms leading to the main fragment ions are explored. Copyright © 2003 John Wiley & Sons, Ltd.
Comparing differentiation of xylene isomers by electronic ionization, chemical ionization and self‐ion/molecule reactions and the first observation of methyne addition ions for xylene isomers in self‐ion/molecule reactions for non‐nitrogenated compounds
Authors: Wu Hui‐Fen , Wu Wen‐Feng 
Published: October 2003

AbstractThis study presents the self‐ion/molecule reaction (SIMR) spectra of three xylene isomers, and proposes an approach to differentiating them based on observed differences in relative abundances of ions formed by SIMR in an internal source ion trap instrument. It also demonstrates the applicability of SIMR for isomer discrimination, which is better than electron ionization (EI) and dimethyl ether chemical ionization (DME CI) in an ion trap mass spectrometer (ITMS) since no CI reagent, metal ions or internal standards are required to perform SIMR. The merits of the new method for distinguishing isomers are that it is simple, rapid and economic. To date, methyne addition products ([M+13]+ ions) have been observed for several nitrogenated compounds including aza‐crown ethers, aniline and dopamine from SIMR in the ITMS. The xylene isomers are, however, the first three non‐nitrogenated compounds that have been shown to produce the methyne addition ions in SIMR. Copyright © 2003 John Wiley & Sons, Ltd.
A new deuterated alkylating agent for quantitative proteomics
Authors: Sebastiano Roberto , Citterio Attilio , Lapadula Marta , Righetti Pier Giorgio 
Published: October 2003

AbstractWeakly basic molecules containing a double bond, such as 2‐ and 4‐vinylpyridine, are able to react and selectively alkylate –SH groups in proteins, thus preventing their re‐oxidation to disulphide bridges. In contrast to conventional alkylating agents such as iodoacetamide and non‐charged acrylamide derivatives, such molecules achieve 100% alkylation of all –SH residues, even in complex proteins, without reacting with other functional groups. Their use is particularly effective in proteome analysis and more generally for analyzing proteins in which the –SH groups should be blocked. Additionally, the use of vinylpyridines, partially or totally deuterated and thus with a mass difference compared with their non‐deuterated counterparts of 4–7 Da, allows studies of induction/repression of protein synthesis (quantitative proteomics). Copyright © 2003 John Wiley & Sons, Ltd.
Use of different proteases working in acidic conditions to improve sequence coverage and resolution in hydrogen/deuterium exchange of large proteins
Authors: Cravello Laetitia , Lascoux David , Forest Eric 
Published: October 2003

AbstractThe combination of hydrogen exchange and mass spectrometry has been widely used in structural biology, providing views on protein structure and protein dynamics. One of the constraints is to use proteases working at low pH and low temperature to limit back‐exchange during proteolysis. Although pepsin works in these conditions and is currently used in such experiments, sequence coverage is not always complete especially for large proteins, and the spatial resolution of the exchange rate is limited by the size of the resulting peptides. In this study we tried two other proteases, protease type XIII from Aspergillus saitoi and protease type XVIII from Rhizhopus species. The penicillin‐binding protein X (PBP‐2X*), a 77‐kDa protein, was selected as a model. Like pepsin, neither of these proteases is really specific, but we found very good reproducibility in the digestion pattern. Compared with using pepsin alone, combining the results of the three independent proteolyses increased the coverage for the peptide mapping, thus avoiding missing some potentially interesting regions of the protein. Furthermore, we obtained a better spatial resolution for deuterium incorporation data, specifying accurately the deuterated regions. Copyright © 2003 John Wiley & Sons, Ltd.
Atmospheric pressure photoionization mechanisms. 2. The case of benzene and toluene
Authors: Tubaro Michela , Marotta Ester , Seraglia Roberta , Traldi Pietro 
Published: October 2003

AbstractBenzene and toluene have been proposed previously as dopants in atmospheric pressure photoionization (APPI) experiments on compounds exhibiting ionization energies higher than the energy of photons used for irradiation. Their low ionization energies lead to their easy photoionization and the ions so formed lead to the ionization of analytes through charge exchange. However, some measurements have shown that some protonation reactions also take place, and a series of experiments was undertaken to investigate this unexpected behavior. It was shown that, when benzene is irradiated in the APPI source, the odd‐electron molecular ions of phenol, diphenyl ether and phenoxyphenol are produced in high yield, together with protonated diphenyl ether and protonated phenoxyphenol. These results have been confirmed by deuterium labelling and MSn experiments. A possible mechanism is proposed, based on a radical attack by benzene molecular ions on oxygen molecules present inside the APPI source, analogous to that proposed in the literature for phenyl radicals. Similar results have been obtained with toluene, proving that APPI is able to activate a series of reactions leading to highly reactive species which are highly effective in promoting ionization of molecules with ionization energies higher than the photon energy. Copyright © 2003 John Wiley & Sons, Ltd.
Increasing sensitivity and decreasing spot size using an inexpensive, removable hydrophobic coating for matrix‐assisted laser desorption/ionisation plates
Authors: Owen Stacey J. , Meier Felix S. , Brombacher Stephan , Volmer Dietrich A. 
Published: October 2003

AbstractSpot size reduction and increased detection sensitivity in matrix‐assisted laser desorption/ionisation (MALDI) of small molecules are accomplished by using an inexpensive and removable hydrophobic coating for MALDI targets, based on 3M Scotch Gard™ surface treatment. Several variations in sample preparation were explored, such as surface coating technique, identity of the matrix, solvent composition, and the type of metal support plate used. These were investigated on both uncoated and coated surfaces and their impact on spot size, crystal coverage, and sensitivity is presented here. Additionally, crystallisation behaviour obtained on coated plates is compared with that on uncoated plates using scanning electron microscope analysis. To demonstrate the potential of the new coating technique, erythromycin A and valinomycin are studied to determine the increase in detection sensitivity of coated plates in comparison to uncoated plates, and to reveal the suitability of the plates for application in combined high‐performance liquid chromatography/MALDI (HPLC/MALDI), where widely varying solvent compositions and droplet volumes are observed. It is shown that enhancements in detection sensitivities correlate very well with the achieved spot size reduction. The versatility of the coated plates is also exhibited by the ease of removing the surface layer, after which the plates can be rigorously cleaned without worry about damaging the hydrophobic surface, followed by a quick reapplication of new hydrophobic coating material. This makes the non‐polar coating superior to more expensive commercial hydrophobic‐coated targets, which are much more delicate to clean. Furthermore, cleaning and reapplication eliminate potential carry‐over effects and the easy application procedure also makes the fabrication of inexpensive, disposable MALDI targets readily possible. Copyright © 2003 John Wiley & Sons, Ltd.
Detection of peonidin and pelargonidin glycosides in black carrots (Daucus carota ssp. sativus var. atrorubens Alef.) by high‐performance liquid chromatography/electrospray ionization mass spectrometry
Authors: Kammerer Dietmar , Carle Reinhold , Schieber Andreas 
Published: October 2003

AbstractAnthocyanins of black carrots (Daucus carota ssp. sativus var. atrorubens Alef.) were investigated by high‐performance liquid chromatography/electrospray ionization mass spectrometry. Besides the main compounds which have already been characterized in detail as cyanidin glycosides, six anthocyanins with m/z 757, 565, 595, 903, 933 and 903 were detected and unambiguously characterized as peonidin and pelargonidin glycosides, based on their fragmentation patterns. Peonidin and pelargonidin were identified after acid hydrolysis by comparison of the fragmentation patterns and retention times of the released aglycones with those of standard compounds. To the best of our knowledge this is the first report on anthocyanins in black carrots consisting of aglycones other than cyanidin. Copyright © 2003 John Wiley & Sons, Ltd.
Collection of selected reaction monitoring and full scan data on a time scale suitable for target compound quantitative analysis by liquid chromatography/tandem mass spectrometry
Authors: King Richard C. , Gundersdorf Richard , Fernández‐Metzler Carmen L. 
Published: October 2003

AbstractA hybrid linear ion trap/triple quadrupole mass spectrometer was used to demonstrate the value of collecting full scan qualitative data during quantitative analysis of target compounds. We present examples of the additional information that can be obtained from plasma samples analyzed primarily for target compound concentrations. This information includes detection of circulating metabolites, dosing vehicle, interfering matrix components, and potential interfering drug conjugates. Additionally, the quantitative results from selected reaction monitoring (SRM) analysis and from combined full scan and SRM analysis (SRM/EMS) were compared. The quantitative data in both scan modes are acceptable in terms of sensitivity, accuracy and precision. One can conclude from this work that the hybrid linear ion trap/triple quadrupole mass analyzer can provide in a single analysis both useful qualitative data, and accurate and precise quantitative data from the samples routinely prepared and analyzed for target drug concentrations. Copyright © 2003 John Wiley & Sons, Ltd.