bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inter‐laboratory comparison of elemental analysis and gas chromatography combustion isotope ratio mass spectrometry (GC‐C‐IRMS). Part I: δ13C measurements of selected compounds for the development of an isotopic Grob‐test
Authors: Serra F. , Janeiro A. , Calderone G. , Rojas J. M. Moreno , Rhodes C. , Gonthier L. A. , Martin F. , Lees M. , Mosandl A. , Sewenig S. , Hener U. , Henriques B. , Ramalho L. , Reniero F. , Teixeira A. J. , Guillou C. 
Published: January 2007

AbstractThis study was directed towards investigating suitable compounds to be used as stable isotope reference materials for gas chromatography combustion isotope ratio mass spectrometry (GC‐C‐IRMS) calibration. Several compounds were selected from those used in the ‘Grob‐test’ mixture. Oxygen‐ and nitrogen‐containing substances were added to these compounds to allow the mixture to be used as a possible multi‐isotopic calibration tool for 2H/1H, 13C/12C, 15N/14N and 18O/16O ratio determinations. In this paper we present the results of δ13C measurements performed by the consortium of the five laboratories taking part in this inter‐calibration exercise. All the compounds were individually assessed for homogeneity, short‐term stability and long‐term stability by means of EA‐IRMS, as required by the bureau communitaire de reference (BCR) Guide for Production of Certified Reference Materials. The results were compared then with the GC‐C‐IRMS measurements using both polar and non‐polar columns, and the final mixture of selected compounds underwent a further certification exercise assessing limits of accuracy and reproducibility under specified GC‐C‐IRMS conditions. Copyright © 2007 John Wiley & Sons, Ltd.
Conventional kinesin‐I motors participate in the anterograde axonal transport of neurotrophins in the visual system
Authors: Butowt Rafal , von Bartheld Christopher S. 
Published: January 2007

AbstractRetinal ganglion cells (RGCs) anterogradely transport neurotrophins to the midbrain tectum/superior colliculus with significant downstream effects. The molecular mechanism of this type of axonal transport of neurotrophins is not well characterized. We identified kinesin‐I proteins as a motor participating in the anterograde axonal movement of vesicular structures containing radiolabeled neurotrophins along the optic nerve. RT‐PCR analysis of purified murine RGCs showed that adult RGCs express all known members of the kinesin‐I family. After intraocular injection of 125I‐brain‐derived neurotrophic factor (BDNF) into the adult mouse or 125I‐neurotrophin‐3 (NT‐3) into the embryonic chicken eye, radioactivity was efficiently immunoprecipitated from the optic nerve lysates by anti‐kinesin heavy chain and anti‐kinesin light chain monoclonal antibodies (H2 and L1). Immunoreactivity for the BDNF receptor trkB is also present in the immunoprecipitates obtained by the anti‐kinesin‐I antibodies. The delivery of the H2 antibody in vivo into the mouse RGCs substantially reduced anterograde axonal transport of 125I‐BDNF. Anterograde transport of BDNF was not diminished in kinesin light chain 1 (KLC1) knockout mice. However, this may be due to redundancy in functions between two different isoforms of KLC present in the RGCs, as it was described previously for kinesin heavy chains (Kanai et al. [ 2000] J Neurosci 20:6374–6384). These data indicate that kinesin‐I is a protein motor that participates in the anterograde axonal transport of neurotrophins in the chicken and mouse visual pathways. © 2007 Wiley‐Liss, Inc.
VEGF‐overexpressing transgenic mice show enhanced post‐ischemic neurogenesis and neuromigration
Authors: Wang Yaoming , Jin Kunlin , Mao Xiao Ou , Xie Lin , Banwait Surita , Marti Hugo H. , Greenberg David A. 
Published: January 2007

AbstractNew neurons are generated continuously in the subventricular zone and dentate gyrus of the adult brain. Neuropathologic processes, including cerebral ischemia, can enhance neurogenesis, as can growth factors and other physiologic stimuli. Vascular endothelial growth factor (VEGF) is an angiogenic and neuroprotective growth factor that can promote neurogenesis, but it is unknown whether VEGF can enhance migration of newborn neurons toward sites of ischemic injury, where they might be able to replace neurons that undergo ischemic death. In the present study we produced permanent focal cerebral ischemia in transgenic (Tg) mice that overexpress VEGF. Cell proliferation and neurogenesis were assessed with bromodeoxyuridine (Brdu) labeling and immunostaining for cell type‐specific markers. In VEGF‐Tg mice, brains examined 7–28 days after cerebral ischemia showed markedly increased subventricular zone (SVZ) neurogenesis, chains of neuroblasts extending from the SVZ to the peri‐infarct cortex, and an increase in the number of newly generated cortical neurons at 14–28 days after ischemia. In concert with these effects, VEGF overexpression reduced infarct volume and improved postischemic motor function. These findings provide evidence that VEGF increases SVZ neurogenesis and neuromigration, consistent with a possible role in repair. Our data suggest that in addition to its neuroprotective effects, which are associated with improved outcome in the acute phase after cerebral ischemia, VEGF enhances postischemic neurogenesis, which could provide a therapeutic target for more chronic brain repair. © 2007 Wiley‐Liss, Inc.
Analyses of representative biomarkers of exposure and effect by chromatographic, mass spectrometric, and nuclear magnetic resonance techniques: Method development and application in life sciences
Authors: Orhan Hilmi 
Published: January 2007

AbstractBiomarkers are essential tools in monitoring studies, which include environmental monitoring, biological monitoring, biological effect monitoring, and health surveillance, as well as drug development processes. Their discovery, validation, and analysis require highly sensitive and selective analytical technologies. In this regard, gas and liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy have facilitated great achievements in all these areas. In addition and closely related to biomarkers, the ongoing developments in these techniques promise a better understanding of the nature and mechanisms of toxic effects originating from various chemical, biological, or physical sources. This Review compiles studies performed on selected biomarkers with respect to both method development and application. Section 1 summarizes the concept of biomarkers; their application in various industrial/occupational, agricultural, drug developmental, and medical/clinical platforms. This section also focuses on biotransformation studies in close relation to biomarker discovery and validation, and on major techniques utilized in this area. In Section 2, biotransformation of volatile anesthetics in humans with a focus on mercapturic acid derivatives as potential biomarkers of effect is reviewed. The use of GC‐ECD, GC/MS, and 19F‐NMR in these studies is described. Section 3 focuses on the analysis of aldehydic lipid peroxidation degradation products by GC‐ECD in mammalian cells in which oxidative stress induced chemically, and in humans after various challenges; anesthetic exposure, ischemia‐reperfusion, and controlled endurance exercise. In Section 4, method development for protein and DNA oxidation products by LC‐tandem MS and its application in mammalian cells and in humans are summarized. Possibilities, limitations, and future perspectives are discussed in Section 5.
Polyurethane Shape‐Memory Polymers Demonstrate Functional Biocompatibility In Vitro
Authors: Cabanlit Maricel , Maitland Duncan , Wilson Thomas , Simon Scott , Wun Theodore , Gershwin M. Eric , Van de Water Judy 
Published: January 2007

AbstractShape memory polymers (SMPs) are a class of polymeric materials used in various medical interventions such as vascular stents. In this work, two SMPs, thermoplastic (TP) and thermoset (TS), have been measured in vitro for the degree of cellular and protein adhesion, their ability to stimulate inflammatory cytokine production, as well as the effects of the SMPs on the haemostatic system. The stimulatory properties of SMPs on neutrophils have also been directly addressed. Based on the studies of SMP biocompatibility as defined by inflammation, thrombogenesis, and the activation of both platelets and neutrophils, the TS and TP SMP materials are unlikely to stimulate an inflammatory response in vivo.magnified image
Elucidating the Biosynthesis of Chitin Filaments and their Configuration with Specific Proteins and Electron Microscopy
Authors: Siemieniewicz Krzysztof W. , Kajla Mayur K. , Schrempf Hildgund 
Published: January 2007

AbstractTo deepen the knowledge of chitin synthesis, a yeast mutant has been used as a model. Purified chitin synthase I‐containing vesicles (chitosomes) with a diameter of 85 to 120 nm are identified by electron microscopy to eject tiny fibers upon addition of UDP‐N‐acetylglucosamine. The filigree of extruded filaments fused gradually into a large three‐dimensional network, which is degradable by a chitinase. The network is targeted and restructured by the Streptomyces chitin‐binding protein CHB1, which has a very high affinity only for α‐chitin. Within the chitosomes, filaments are found to be highly condensed within consecutive oval fibroids, which are specifically targeted by the α‐chitin‐binding protein. The presented data give new insights to the generation of chitin filaments with an antiparallel (α) configuration.magnified image
Preparation of Cross‐Linked Poly[(ε‐caprolactone)‐co‐lactide] and Biocompatibility Studies for Tissue Engineering Materials
Authors: Miyasako Hiroshi , Yamamoto Kazuya , Nakao Aiko , Aoyagi Takao 
Published: January 2007

AbstractIn this study, cross‐linked materials were prepared using the branched macromonomer with different CL/LA molar ratios, and feasibility studies for tissue engineering were carried out. The thermal and mechanical properties of these materials depended on the CL/LA compositions; however, there was no change in the wettability of each material. The HeLa cells adhesion and growth on the CL‐LA7030c were equal to that on the commercially available polystyrene dish. The protein absorption experiment using the FBS proteins revealed that the materials with well‐grown cells showed better adhesion of the proteins.magnified image
Hyperbranched Polymer/TiO2 Hybrid Nanoparticles Synthesized via an In Situ Sol‐Gel Process
Authors: Di Gianni Anna , Trabelsi Sondes , Rizza Giancarlo , Sangermano Marco , Althues Holger , Kaskel Stefan , Voit Brigitte 
Published: January 2007

AbstractTwo different kinds of HBPs were used in the preparation of nanocomposite materials based on TiO2 nanoparticles. One of the HBPs was characterized by the presence of free OH end groups in its structure, while the other one was obtained via a partial modification reaction which allowed to introduce some alkoxysilane functional groups. The TiO2 particles were prepared in situ in the polymer solution by means of a sol‐gel process starting from Ti(iOPr)4 as precursor. The polymer/TiO2 mixture, subsequently coated and cured in the presence of diisocyanate, gave rise to a hard coating. TiO2 was found to be dispersed on nanometer scale inside the final coatings obtained from both the polymers, and the TiO2 nanocomposite coatings were also characterized by improved thermal and hardness properties compared to TiO2 free systems. Still the two different kinds of HBPs showed a different interaction with the TiO2 particles, and it has been evidenced that the modification is required to achieve a better dispersion of the particles in the matrix and better properties for the final coating. Thus, by applying the modified HBP, TiO2 could be dispersed and stabilized in the polymer matrix as individual nanoparticles of only 6 nm in diameter.magnified image
Poly(propylene)‐Layered Silicate Nanocomposites: Gas Permeation Properties and Clay Exfoliation
Authors: Osman Maged A. , Mittal Vikas , Suter Ulrich W. 
Published: January 2007

AbstractTo monitor the mineral surface coverage and energy, the inorganic cations of two clays (montmorillonite) with different surface area/cation have been exchanged by alkylammonium ions, carrying alkyl chains of different number and length. The prepared OMs were free of unreacted organic ions. With increasing length and number of the alkyl chains, an increase in the basal‐plane spacing (d‐spacing) of the OM was observed. The d‐spacing also increased with increasing CEC of the clay (decreasing available area/cation). The OMs were compounded with PP and their effect on the crystallinity and gas‐barrier properties of the polymer was investigated. The OM had no influence on the degree of crystallinity of PP under the processing conditions used. Oxygen permeation through the composites decreased, depending on the cross‐sectional area of the exchanged organic cation and the CEC of the clay. These parameters control the mineral surface coverage (consequently the surface energy) as well as the tilt angle of the alkyl chains to the mineral surface, and hence the d‐spacing. Increasing the length of the alkyl chains and their number per cation enhanced the d‐spacing, clay exfoliation, and the gas‐barrier properties of the composites. A mixed morphology, consisting of delaminated aluminosilicate layers and OM tactoids of varying thickness was observed but no intercalation took place. The oxygen permeation coefficient of the nanocomposites was found to be a non‐linear function of the volume fraction of the inorganic part of the OM.magnified image
Synthesis via ATRP and Anchoring Properties of Ammonium‐Terminated Monofunctional or Telechelic Polystyrenes
Authors: Toquer Guillaume , Monge Sophie , Antonova Krassimira , Blanc Christophe , Nobili Maurizio , Robin Jean‐Jacques 
Published: January 2007

AbstractMono‐ and di‐(trimethylammonium)‐terminated polystyrenes with similar molar masses were synthesized. Bromopolystyrenes were first prepared by atom transfer radical polymerization (ATRP) using (N‐Boc‐propylamino)‐2‐bromoisobutyrate as initiator and Cu(I)Br/2,2′‐bipyridine as catalytic system in bulk at 110 °C. α,ω‐Telechelic polymer with double molecular weight with respect to the starting polystyrene was then obtained under atom transfer radical coupling process using 2,2′‐bipyridine and copper(0) mediated reductive conditions in anisole. Final (trimethylammonium)‐terminated polystyrenes were eventually obtained after removal of the tert‐butyloxycarbonyl group and permethylation reactions. Intermediate and final polymers were characterized by 1H NMR. The aligning properties of the obtained polymers for liquid crystals have been investigated. Pretilt and zenithal anchorings on ITO/glass substrates were measured. Finally, the possibility for the telechelic polystyrene to form a network in an inverted microemulsion was also considered.magnified image
Rheology and Physical Properties of Polyethylene/Polyethylene‐Ionomer Blends and their Clay Nanocomposites
Authors: Lee Jennifer A. , Kontopoulou Marianna , Parent J. Scott 
Published: January 2007

AbstractRheological and solid‐state physical properties of blends containing high‐density polyethylene (HDPE) and a polyampholyte derivative (PE‐g‐PA) are assessed along with their onium ion‐exchanged montmorillonite clay (NR‐MM) nanocomposites. Strong deviations from the log‐additivity rule of zero‐shear viscosity, combined with synergistic behavior in tensile moduli, are consistent with a multi‐phase blend morphology. While this affects clay dispersion in filled blends, PE‐g‐PA/HDPE based nanocomposites are shown to exhibit a favorable balance between material stiffness and ductility.magnified image
Laser‐Induced Crosslinking of Ultra‐Low‐ and High‐Density Polyethylene
Authors: Khan Ferdous , Kwek Diana , Kronfli Esam , Ahmad Sheikh Rafi 
Published: January 2007

AbstractThe use of laser radiation to initiate the crosslinking process in ultra low‐density polyethylene (ULDPE) and high‐density polyethylene (HDPE) was evaluated. The process was found to be most effective for pulsed laser irradiation when the polymer was traced with a photoinitiator: 4‐chlorobenzophenone (CBP). The gel content measurements proved that crosslinking took place in all the irradiated samples. The degree of crosslinking was measured for different values of irradiation energy, temperature, photoinitiator concentration and the nature and type of crosslinking agents. The effects of all these parameters on the degree of crosslinking and the consequent effects on mechanical properties of the polymers were analyzed. Also found in the present study is the fact that a better efficiency of crosslinking was achieved at longer laser irradiation wavelength. The ultimate tensile stress and elongation at fracture were measured for all cross‐linked samples and compared with those of the controlled ones.magnified image
A Novel Route to the Preparation of Poly(N‐isopropylacrylamide) Microgels by Using Inorganic Clay as a Cross‐Linker
Authors: Zhang Qingsong , Zha Liusheng , Ma Jinghong , Liang Borun 
Published: January 2007

AbstractAdopting inorganic clay (hectorite) and MBA as physical and chemical cross‐linking agents, respectively, PNIPAM microgels were synthesized by SFEP. The chemical structure and morphology of the microgels were confirmed by FTIR, WXRD, and SEM. The temperature‐sensitivity of the microgels was investigated by DLS and UV spectrophotometers. The results inferred that clay platelets dispersed in an aqueous medium were fully exfoliated and could act as a kind of multifunctional cross‐linking agent and significantly reduced the hydrodynamic diameters of the microgels. In fact, the hydrodynamic diameters of the PNIPAM microgels with clay as cross‐linker ranged from 154 to 322 nm which was much smaller than that using MBA as chemical cross‐linker, the later was in the range of 284–808 nm on heating from 5 to 50 °C.magnified image
Measurement of trace atmospheric species by chemical ionization mass spectrometry: Speciation of reactive nitrogen and future directions
Authors: Huey L. Gregory 
Published: January 2007

AbstractChemical ionization mass spectrometry (CIMS) has proven to be a powerful method for sensitive, fast time response (t∼1 sec) measurements of various atmospheric compounds with limits of detection (LOD) of the order of tens of pptv and lower. The rapid time response of CIMS is particularly well suited for airborne measurements and its application has largely grown out of airborne measurements in the stratosphere and upper troposphere. This work reviews some of the advances in CIMS technology that have occurred in the past decade. In particular, CIMS methods for selective measurement of reactive nitrogen species (e.g., HNO3, HO2NO2, PAN, and NH3) in the lower atmosphere (altitudes ∼0–8 km) are described. In addition, recent developments in CIMS technology for the selective measurement of gas‐phase hydroperoxides and aerosol chemical composition are briefly described. © 2007 Wiley Periodicals, Inc., Mass Spec Rev 26:166–184, 2007
Free‐Radical Dispersion Polymerization of Methyl Methacrylate in Supercritical Carbon Dioxide: A Parametric Analysis with Reaction Calorimetry
Authors: Mantelis Charalampos A. , Barbey Raphaël , Fortini Sophie , Meyer Thierry 
Published: January 2007

AbstractIn an attempt to reduce the emission of hazardous VOCs, SCFs have been intensively investigated as alternative solvents during the last two decades. In this study, the application of reaction calorimetry, an efficient tool to obtain kinetic and safety data, is presented on the free radical dispersion polymerization of MMA in scCO2. The effect of three major parameters with respect to the reaction evolution are studied, namely of stirrer type and stirring speed, the monomer and CO2 concentration and the stabilizer concentration. The effective formation of the dispersion as well as the balance between the polymer formed in the continuous phase or inside the particles are key features of this analysis.magnified image
Effects of Hydrogen for Different Stereospecific Active Sites on Ultra Low TiCl3 Loading Supported Catalyst
Authors: Kouzai Iku , Liu Boping , Wada Tooru , Terano Minoru 
Published: January 2007

AbstractThe relationship between the stereospecificity of active sites and hydrogen effects on propylene polymerization was investigated for MgCl2‐supported TiCl3 catalysts at ultra‐low Ti contents. Hydrogen had no effect on the catalyst activities for isospecific sites and for aspecific sites. The efficiency of hydrogen as a chain‐transfer agent was found to depend on the stereospecificity of the active sites. Hydrogen was effective for isospecific sites but was not effective for aspecific sites. From the viewpoint of hydrogen dissociation, isospecific sites should have hydrogen dissociation sites in their surroundings. Therefore, isospecific sites may be in the island to be affected by hydrogen and isolated sites may be aspecific or have low isospecificity.magnified image
An unusual myopathy: Speckled muscle fibers due to enlarged mitochondria
Authors: Jeffree Rosalind L. , Wills Edward J. , Harper Clive 
Published: January 2007

AbstractWe report a 52‐year‐old woman who presented with a 6‐month history of proximal muscle weakness, elevated serum creatine kinase, and myopathic pattern on electromyography (EMG). Histology of the muscle shows a speckled pattern due to clustering of enlarged mitochondria. The pathology resembles that of selenium deficiency. The patient was found to have borderline low serum selenium and also low vitamin D and thyroid‐stimulating hormone. The cause of this unusual myopathy is probably multifactorial. This case is important because the unusual pathological picture represents a potentially treatable myopathy. In addition, we hope that publication of the complex clinical and biochemical abnormalities of this case, in conjunction with other case reports, may facilitate future elucidation of muscle mitochondrial function and dysfunction. Muscle Nerve, 2007
Stress, optimism, and social support: Impact on immune responses in breast cancer
Authors: Ah Diane Von , Kang Duck‐Hee , Carpenter Janet S. 
Published: January 2007

AbstractThe purpose of this study was to examine the direct and stress‐buffering effect of optimism and satisfaction with social support on immune responses in women with breast cancer. Participants were 54 post‐operative (M = 19 days) breast cancer patients who completed questionnaires on stress, optimism, and satisfaction with social support and provided blood to measure natural killer cell activity (NKCA) and interferon‐gamma (IFN‐γ) from whole blood. Higher levels of stress were associated with decrements in NKCA and IFN‐γ. Optimism moderated the relationship of stress on NKCA but was not related to IFN‐γ. Satisfaction with social support was unrelated to immune responses. Results suggest that interventions aimed at reducing stress and enhancing optimism in women with breast cancer might promote optimal immune response. © 2007 Wiley Periodicals, Inc. Res Nurs Health 30: 72–83, 2007
The enduring and contextual effects of physical health and depression on care‐dyad mutuality
Authors: Lyons Karen S. , Sayer Aline G. , Archbold Patricia G. , Hornbrook Mark C. , Stewart Barbara J. 
Published: January 2007

AbstractMutuality is a protective factor in family care situations, but little is known about changes in care‐dyad mutuality. In this study, we examined mutuality in 103 care dyads over 20 months, and the enduring and contextual impact of older adult and family caregiver health on changes in mutuality. Care dyads consisted of frail older adults and their family caregiver. Older adults reported higher levels of mutuality than family caregivers, but their mutuality declined significantly faster over time. Although changes in physical health were more important than mean health for both older adults and family caregivers, mean depression was more important than changes in depression for older adults. This study shows the importance of examining time‐varying covariates in the care dyad. © 2007 Wiley Periodicals, Inc. Res Nurs Health 30: 84–98, 2007