bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hoxc8 early enhancer of the Indonesian coelacanth, Latimeria menadoensis
Authors: Shashikant Cooduvalli , Bolanowski Stacey A. , Danke Joshua , Amemiya Chris T. 
Published: October 2004

AbstractHoxc8 early enhancer controls the initiation and establishment phase of Hoxc8 expression in the mouse. Comparative studies indicate the presence of Hoxc8 early enhancer sequences in different vertebrate clades including mammals, birds and fish. Previous studies have shown differences between teleost and mammalian Hoxc8 early enhancers with respect to sequence and organization of protein binding elements. This raises the question of when the Hoxc8 early enhancer arose and how it has become modified in different vertebrate lineages. Here, we describe Hoxc8 early enhancer from the Indonesian coelacanth, Latimeria menadoensis. Coelacanths are the only extant lobefinned fish whose genome is tractable to genome analysis. The Latimeria Hoxc8 early enhancer sequence more closely resembles that of the mouse than that of Fugu or zebrafish. When assayed for enhancer activity by reporter gene analysis in transgenic mouse embryos, Latimeria Hoxc8 early enhancer directs expression to the posterior neural tube and mesoderm similar to that of the mouse enhancer. These observations support a close relationship between coelacanths and tetrapods and place the origin of a common Hoxc8 early enhancer sequence within the sarcopterygian lineage. The divergence of teleost (actinopterygii) Hoxc8 early enhancer may reflect a case of relaxed selection or other forms of instability induced by genome duplication events. J. Exp. Zool. (Mol. Dev. Evol.) 302B:000000, 2004. © 2004 Wiley‐Liss, Inc.
Regulated expression of VP16CREB in neuroblastoma cells: Analysis of differentiation and apoptosis
Authors: Andreatta Cynthia P. , Nahreini Piruz , Hanson Amy J. , Prasad Kedar N. 
Published: October 2004

AbstractHighly malignant neuroblastoma tumors generally have defects in differentiation and apoptotic pathways. For a better understanding of these events, we use a murine neuroblastoma cell line (NBP2) that terminally differentiates into mature neurons in response to elevated levels of cAMP. Because one of the main downstream effectors of the cAMP signaling pathway is cAMP‐response element binding (CREB), we reasoned that it might affect the expression of genes associated with differentiation and apoptotic events in NBP2 cells. To investigate this, we established tetracycline‐regulated expression (TetOff) of VP16CREB, which constitutively transactivates promoters containing the CRE sequence motif. Using this system, we found that inducible expression of VP16CREB in NBP2 cells results in 1) morphological differentiation that is characterized by the formation of neurites and growth cones, 2) reversible cell differentiation unlike cAMP‐induced terminal differentiation, 3) cell cycle arrest at G1, 4) no apoptosis in the presence of partial inhibition of proteasome unlike an increase in cAMP levels, and 5) changes in the expression of many genes, including down‐regulation of N‐myc, cyclin B1, Dickkopf‐1, and Mad‐2 and up‐regulation of tyrosine hydroxylase, c‐fos, N10, and ICER genes. Although VP16CREB expression and activation of the cAMP pathway impart many similar effects in NBP2 cells, they also bear some distinct genetic and morphological differences. Our data suggest that increased levels of cAMP function through not only CREB but also other signaling pathways that account for the additional cAMP‐induced effects, including irreversible differentiation and onset of apoptosis during partial inhibition of proteasome in NBP2 cells. © 2004 Wiley‐Liss, Inc.
On‐line separation for the speciation of mercury in natural waters by flow injection‐cold vapour‐atomic absorption spectrometry
Authors: Sanz Jon , Raposo Juan Carlos , Larreta Joana , Martinez‐Arkarazo Irantzu , de Diego Alberto , Madariaga Juan Manuel 
Published: October 2004

AbstractInorganic mercury and methylmercury are determined in natural waters by injecting the filtered samples onto a low cost commercial flow injection system in which an anion exchange microcolumn is inserted after the injection loop (FIA‐IE). If hydrochloric acid is used as the carrier solution, the HgCl42– species (inorganic mercury) will be retained by the anion exchanger while the CH3HgCl species (methylmercury) will flow through the resin with negligible retention. Four anion exchangers and seven elution agents were checked, in a batch mode, to search for the best conditions for optimal separation and elution of both species. Dowex M‐41 and L‐cysteine were finally selected. Mercury detection was performed by cold vapour‐electrothermal atomic adsorption spectrometry (HG‐ETAAS). Both systems were coupled to perform the continuous on‐line separation/detection of both inorganic mercury and methylmercury species. Separation and detection conditions were optimized by two chemometric approaches: full factorial design and central composite design. A limit of detection of 0.4 μg L–1 was obtained for both mercury species (RSD < 3.0% for 20 μg L–1 inorganic and methylmercury solutions). The method was applied to mercury speciation in natural waters of the Nerbioi‐Ibaizabal estuary (Bilbao, North of Spain) and recoveries of more than 95% were obtained.
Wrapping of Single‐Walled Carbon Nanotubes with A‐B‐A Block Telomers
Authors: Kitano Hiromi , Tachimoto Kazutaka , Nakaji‐Hirabayashi Tadashi , Shinohara Hiroaki 
Published: October 2004

AbstractSummary: Single‐walled carbon nanotubes (SWNTs) mechanically dispersed in HEPES buffer were incubated with a dispersion of A‐B‐A block telomers, composed of 2‐methacryloyloxyethyl‐D‐glucopyranoside telomers (A block) and a styrene telomer (B block), which had been prepared by the macroinitiator technique. After the incubation, the polymer‐wrapped SWNT could be stably dispersed in the buffer without any precipitation for several months. The glucose residue above the SWNT was definitely recognized by lectin (Concanavalin A) as proven by the increase in turbidity. Using a similar procedure, a block telomer composed of N‐isopropylacrylamide telomers (A block) and a styrene telomer (B block) could easily be deposited onto the SWNT. A temperature‐responsive aggregation and the subsequent precipitation of the modified SWNT could clearly be observed. The usage of the block‐telomer examined here would be promising for the preparation of stable dispersions of SWNTs with various functions.
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Novel Possibilities by Cationic Ring‐Opening Polymerisation of Cyclodextrin Derivatives: Preparation of a Copolymer Bearing Block‐Like Sequences of Tri‐O‐methylglucosyl Units
Authors: Adden Roland , Bösch Andreas , Mischnick Petra 
Published: October 2004

AbstractSummary: Equimolar mixtures of O‐permethylated and O‐perdeuteromethylated cyclodextrins were submitted to cationic ring‐opening polymerisation (CROP) with Et3OPF6 or BF3 · Et2O as initiator in dichloromethane. Reaction started after an incubation time and yielded a polymeric product, which was partially degraded again during competing chain transfer reaction. Average block length was determined by ESI‐MS after partial methanolysis and was found to be close to the theoretical value of 14 for β‐cyclodextrin in the early stage of the reaction, but decreased to 2–5 during further chain transfer reactions accompanied by an equilibration of α‐ and β‐configurated glucosidic linkages to a ratio of 64:36. Molecular weight was estimated from end group analysis and GPC to reach about 29 000 as a maximum. From 31P NMR spectra of the initiator it was obvious that PF is partly hydrolysed to PO2F under participation of the glass surface.
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Front Cover: Macromol. Chem. Phys. 15/2004
Authors: Severn John R. , Chadwick John C. 
Published: October 2004

Front Cover: High and stable activity in ethylene polymerization has been achieved with a wide range of Ti‐based single‐site catalysts without the use of MAO or borate activators, using spherical supports of type MgCl2/AlRn(OEt)3–n obtained by reaction of AlR3 with adducts of MgCl2 and ethanol. Polyethylene having spherical particle morphology and narrow molecular weight distribution was obtained.Further details can be found in the Full Paper by J. R. Severn and J. C. Chadwick* on page 1987.
Back Cover: Macromol. Chem. Phys. 15/2004
Authors: Egbe Daniel Ayuk Mbi , Sell Stephan , Ulbricht Christoph , Birckner Eckhard , Grummt Ulrich‐Walter 
Published: October 2004

Back Cover: The Cover shows the absorption and emission spectra of alkyl‐ and alkoxy‐substituted dialdehydes, and their respective poly[(phenylene ethynylene)‐alt‐(phenylene vinylene)] hybrid polymers, obtained by the polycondensation of the dialdehydes with alkoxy‐substituted bisphosphonates. Photophysical investigations and quantum chemical calculations reveal remarkable differences between alkyl‐ and alkoxy‐substituted dialdehydes. On the contrary, their polymers exhibit similar photophysical properties, indicating an identical fluorophore system located around the lower energy phenylene‐vinylene segment of the polymers.Further details can be found in the Full Paper by D. A. M. Egbe,* S. Sell, C. Ulbricht, E. Birckner, and U.‐W. Grummt on page 2105.
Cigarette smoking and Parkinson's disease: A case–control study in a population characterized by a high prevalence of pesticide exposure
Authors: Galanaud Jean‐Philippe , Elbaz Alexis , Clavel Jacqueline , Vidal Jean‐Sébastien , Corrèze Jean‐René , Alpérovitch Annick , Tzourio Christophe 
Published: October 2004

AbstractEpidemiological studies have been consistent in showing that cigarette smoking is inversely associated with Parkinson's disease (PD), whereas pesticide use is positively associated with PD. However, the relationship between PD and cigarette smoking remains poorly understood. Our objective was to study the relationship between cigarette smoking and PD in a population characterized by a high prevalence of pesticide exposure. This case–control study was carried out among subjects enrolled in the Mutualité Sociale Agricole, the French health insurance organization for workers connected to the agricultural world. We included 247 cases and 676 controls matched on age, sex, and region of residency. Information on smoking was obtained through in‐person interviews. Pesticide exposure was assessed using a case‐by‐case expert evaluation procedure. We found an inverse relationship between ever cigarette smoking and PD (odds ratio [OR] = 0.6; 95% confidence interval [CI] = 0.4–0.9). The strength of this association increased with the number of pack‐years. This relationship was present even when smoking was considered as long as 40 years before PD onset. An inverse association was also present among subjects professionally exposed to pesticides (OR = 0.5; 95% CI = 0.3–0.8) and was independent of the duration of exposure among men. We confirm the inverse association between cigarette smoking and PD in a population characterized by a high prevalence of professional pesticide exposure. The relationship between PD and cigarette smoking was not significantly modified or confounded by exposure to pesticides. © 2004 Movement Disorder Society
A new method to measure caudal motor conduction time using magnetic stimulation
Authors: Han Tai Ryoon , Paik Nam Jong , Lee Seong Jae , Kwon Bum Sun 
Published: October 2004

AbstractAlthough central motor conduction time (CMCT) has been used for the diagnosis of lumbosacral spinal stenosis (LSSS), its diagnostic value is limited due to the short length of the involved segment compared to the long length of the total conduction distance. To overcome this, we introduce a new method to measure the caudal motor conduction time (caudal MCT) using magnetic stimulation. Magnetic stimulation was applied to the vertex and the T12 and S1 spinous processes for transcortical, thoracic, and sacral stimulation, respectively, and compound muscle action potentials were recorded simultaneously from the rectus abdominis (RA) and the right and left abductor hallucis (AH) muscles using three channels. CMCT was calculated by the latency difference in the AH response between transcortical and sacral stimulation, and between transcortical and thoracic stimulation for RA. Caudal MCT was calculated by subtracting CMCT for RA from that for AH. Caudal MCT was delayed in patients with LSSS compared to normal persons. We suggest that measuring caudal MCT may be useful for the diagnosis of LSSS, but its diagnostic sensitivity and specificity requires prospective study. Muscle Nerve, 2004
Anal sphincter electromyography: Editing of sampled motor unit action potentials
Authors: Gregory W. Thomas , Clark Amanda L. , Johnson Joshua , Willis Kimberly , Stuyvesant Amy , Lou Jau‐Shin 
Published: October 2004

AbstractDuring multi‐motor unit action potential (MUAP) analysis of the tonically contracted external anal sphincter (EAS), a mild interference pattern often obscures the baseline, affecting the algorithm's ability to determine accurate boundaries of detected MUAPs. To assess the equivalence of methods of editing and selecting candidate MUAPs from the EAS, 17 nulliparous women underwent concentric needle electromyography (EMG) of the EAS using multi‐MUAP software. The selected MUAPs either were accepted without question (“automated”), or a subset was deleted due to a noisy baseline (“manual‐deletion”) or manually marked (“manual‐mark”). A second examiner repeated the analysis. Each examiner found that the two editing methods were equivalent and yielded results that differed from those obtained by automated analysis of unedited data. However, there was a moderate difference in MUAP amplitude when the manual‐deletion method was compared between the two examiners. Editing of selected EAS MUAPs during multi‐MUAP analysis is required, and development of common protocols is essential to enable meaningful comparisons between similar studies. Muscle Nerve, 2005
Automated parallel investigations/optimizations of the reversible addition‐fragmentation chain transfer polymerization of methyl methacrylate
Authors: Fijten Martin W. M. , Meier Michael A. R. , Hoogenboom Richard , Schubert Ulrich S. 
Published: October 2004

AbstractPoly(methyl methacrylate)s were successfully synthesized in a controlled fashion via reversible addition‐fragmentation chain transfer polymerizations utilizing an automated synthesizer. Sixteen polymers were synthesized in a parallel way utilizing the Chemspeed Accelerator™ SLT100 to investigate the reproducibility and the control over the polymerizations. The obtained polymers were characterized by gel permeation chromatography (GPC) and automated MALDI TOFMS measurements, thereby proving the reproducibility and controllability of the investigated automated setup. Furthermore, temperature optimization reactions were performed utilizing an individually heatable reactor block. Moreover, to demonstrate the presence of active polymer chains in the reaction mixture, chain extension polymerizations were performed on the automated synthesizer. The results obtained from these chain extension experiments demonstrate the possibility to design well‐defined A‐b‐B block copolymers with different monomers as building units. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5775–5783, 2004
Preparation of methoxy poly(ethylene glycol)/polyester diblock copolymers and examination of the gel‐to‐sol transition
Authors: Kim Moon Suk , Seo Kwang Su , Khang Gilson , Cho Sun Hang , Lee Hai Bang 
Published: October 2004

AbstractDiblock copolymers consisting of methoxy poly(ethylene glycol) (MPEG) and poly(ϵ‐caprolactone) (PCL), poly(δ‐valerolactone) (PVL), poly(L‐lactic acid) (PLLA), or poly(lactic‐co‐glycolic acid) (PLGA) as biodegradable polyesters were prepared to examine the phase transition of diblock copolymer solutions. MPEG–PCL and MPEG–PVL diblock copolymers and MPEG–PLLA and MPEG–PLGA diblock copolymers were synthesized by the ring‐opening polymerization of ϵ‐caprolactone or δ‐valerolactone in the presence of HCl · Et2O as a monomer activator at room temperature and by the ring‐opening polymerization of L‐lactide or a mixture of L‐lactide and glycolide in the presence of stannous octoate at 130 °C, respectively. The synthesized diblock copolymers were characterized with 1H NMR, IR, and gel permeation chromatography. The phase transitions for diblock copolymer aqueous solutions of various concentrations were explored according to the temperature variation. The diblock copolymer solutions exhibited the phase transition from gel to sol with increasing temperature. As the polyester block length of the diblock copolymers increased, the gel‐to‐sol transition moved to a lower concentration region. The gel‐to‐sol transition showed a dependence on the length of the polyester block segment. According to X‐ray diffraction and differential scanning calorimetry thermal studies, the gel‐to‐sol transition of the diblock copolymer solutions depended on their degrees of crystallinity because water could easily diffuse into amorphous polymers in comparison with polymers with a crystalline structure. The crystallinity markedly depended on both the distinct character and composition of the block segment. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5784–5793, 2004
Block‐diagonalization problem for the common Hückel‐type Hamiltonian matrix of alternant hydrocarbons and its nonperturbative solution
Authors: Gineityte V. 
Published: October 2004

AbstractThe block‐diagonalization problem originating from the Brillouin theorem and determining the noncanonical molecular orbitals (NCMOs) has been formulated and solved for the common Hamiltonian matrix H of alternant hydrocarbons in the framework of the simple Hückel model. The well‐known way of partitioning of the total basis set of 2pz AOs of carbon atoms of these molecules into two subsets allowed the problem to be solved nonperturbatively in terms of entire subsets of atomic orbitals (AOs), and thereby of respective submatrices (blocks) of the matrix H, without specifying either the internal structures or dimensions of the latter. As a result, the NCMOs of alternant hydrocarbons proved to be characterized by common peculiarities, including uniform total extents of delocalization. A close relationship has been established between the block‐diagonalization problem under study and the commutation equation determining the respective one‐electron density matrix (DM) directly without invoking the canonical molecular orbitals (CMOs). In particular, the off‐diagonal blocks both of the NCMO representation matrix C and of the DM P were shown to follow from the same matrix condition originally suggested by G. G. Hall on the basis of structures of CMOs of alternant hydrocarbons. The relationship between the two fundamental noncanonical problems gave an additional insight into the origin of the observed similarity between constitutions of matrices C and P. It has been concluded on this basis that the common DM of alternant hydrocarbons (the charge‐bond order matrix) is among noncanonical (localized) ways of describing electronic structures whatever the actual method of its derivation. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Perturbative perspectives on the chemical reaction prediction problem
Authors: Ayers Paul W. , Anderson James S. M. , Bartolotti Libero J. 
Published: October 2004

AbstractWhen a molecule is in the presence of a chemical reagent, the external potential and the number of electrons in the molecule change. This leads to perturbative perspectives on chemical reactivity, wherein the response of a molecule to various “model perturbations” of the external potential and number of electrons is used to predict its reactivity. The perturbative perspective allows one to treat indices associated with conceptual density functional theory in a unified way. Here we concentrate on the implications of the perturbative perspective in describing regioselectivity and certain global properties of molecules, specifically, their electrophilicity, nucleofugality, and electrofugality. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
The basis set effect on the results of the minimization of the total energy bifunctional E[ρA,ρB]
Authors: Dulak Marcin , Wesolowski Tomasz A. 
Published: October 2004

AbstractThe basis set effect on the results of the minimization of the total energy bifunctional E[ρA, ρB] approximated at the local density approximation level is analyzed for several weak intermolecular complexes. The considered complexes formed by hydrocarbons at the equilibrium geometry were previously studied by means of the same formalism using large decontracted basis sets consisting of Gaussian‐type atomic orbitals limited to s‐, p‐, and d‐functions. In this work, we use our two new computer implementations of the formalism to analyze the basis set effects accompanying changing the basis sets from Gaussian‐type orbitals to Slater‐type orbitals and including f‐functions. We show that the interaction energies, their components, and the energies of the highest occupied molecular orbital converge within a range of 0.07 kcal/mol, 0.08 kcal/mol, and 0.06 eV, respectively. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Layer model approach to background correction in r.f.‐GDOES
Authors: Payling R. , Nelis T. , Aeberhard M. , Michler J. , Seris P. 
Published: October 2004

AbstractTwo methods are presented for dealing with variable background signals in radiofrequency glow discharge optical emission spectroscopy (r.f.‐GDOES). Their aim is to improve elemental analysis at trace levels, in bulk analysis or in compositional depth profiling, without having to measure background signals during the analysis. Each method uses background signals measured away from the analytical emission lines of interest during calibration only. The background signal is first determined during calibration for each material type of interest. During analysis in the first method the estimated background signal is varied according to the material type being analysed. In depth profiles this means identifying the various layers present as different material types, hence the name ‘layer model’. The second method is a more conventional approach, where part of the background signal is estimated as a spectral interference. Results are presented for the bulk analysis of a tool steel and for two depth profiles: TiO2 coating on silicon and TiN‐coated tool steel. The two methods give similar results in the depth profiles, both significantly better than with a constant background. Copyright © 2004 John Wiley & Sons, Ltd.
Monte‐Carlo simulation of spatial distribution of characteristic x‐rays in multi‐film targets: source size of Al Kα x‐rays in W/Al film targets
Authors: Yoshioka Akihiro , Yamaguchi Yoshikazu , Tamura Keiji , Shimizu Ryuichi 
Published: October 2004

AbstractA Monte‐Carlo simulation approach has been applied to describe the spatial distribution of characteristic x‐rays in W/Al film targets of different combinations of film thicknesses for the optimal design of a small‐sized x‐ray source having a high x‐ray intensity.The result has led to optimal combinations of W and Al film targets for 100 kV electrons, e.g. W(1 µm)/Al(20 µm), W(3 µm)/Al(15 µm) and W(5 µm)/Al(8 µm). These Al/W targets could be used as x‐ray sources for a medical instrument currently under development. Copyright © 2004 John Wiley & Sons, Ltd.