bluuebunny/crossref_metadata_2025_split huggingface dataset:
The safety of obstetrical ultrasound: a review
Authors: Houston Laura E. , Odibo Anthony O. , Macones George A. 
Published: November 2009

AbstractUltrasound is a commonly employed imaging modality in obstetrics and is generally regarded as safe to the fetus. Current ultrasound technology, however, has significantly higher output potential than older machines used in most clinical studies, and the safety profile for the increasing use of Doppler, 3‐dimensional (D) and 4‐D ultrasound with modern machines is unknown. This article reviews the current status of ultrasound safety within obstetrics, including proposed mechanisms of harm, existing scientific and clinical evidence regarding those mechanisms, and considerations of safety for the clinical user. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and properties of new photosensitive and chiral poly(amide‐imide)s based on bicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic diimide and dibenzalacetone moieties in the main chain
Authors: Faghihi Khalil , Hajibeygi Mohsen , Shabanian Meisam 
Published: November 2009

AbstractAromatic poly(amide‐imide)s (PAIs) are high‐performance materials with a good compromise between thermal stability and processability when compared with polyamides or polyimides of analogous structures. In addition, the incorporation of photosensitive functional groups and chiral segments into the polymer backbone can lead to interesting polymers for various applications. In this work, six new photosensitive and chiral PAIs were synthesized from the direct polycondensation reaction of novel N,N′‐(bicyclo[2,2,2]oct‐7‐ene‐tetracarboxylic)‐bis‐L‐amino acids with 2,5‐bis(4‐aminobenzylidene)cyclopentanone as dibenzalacetone moiety using two different methods. The polymerization reactions produced a series of photosensitive and optically active PAIs in high yields and with good inherent viscosities. The resulting polymers were characterized using Fourier transform infrared and 1H NMR spectroscopy, elemental analysis, inherent viscosity, specific rotation, solubility tests and UV‐visible spectroscopy. The thermal properties of the PAIs were investigated using thermogravimetric analysis. Due to the presence of the dibenzalacetone moiety in the polymer chain, the PAIs have photosensitive properties. Also, these PAIs are optically active and soluble in various organic solvents. These resulting new polymers have the potential to be used in column chromatography for the separation of enantiomeric mixtures. Copyright © 2009 Society of Chemical Industry
Synthesis, characterization, in vitro degradation and cytotoxicity of polyphosphazenes containing N‐ethoxypyrrolidone side groups
Authors: Bi Yunmei , Yin Yuefan , Huang Rong , Li Yanmei 
Published: November 2009

AbstractA new biodegradable polyphosphazene (PYRMP) containing N‐ethoxypyrrolidone and methoxyethoxyethoxy side groups was synthesized via a route of macromolecular substitution. The synthetic method of poly{bis[2‐(2‐oxo‐1‐pyrrolidinyl)ethoxy]phosphazene} (PYRP) was improved. The thermal properties of the polymers were investigated using differential scanning calorimetry. Degradation studies were carried out in vitro with varying pH conditions. The in vitro cytotoxicity of PYRMP and its hydrolysis products was evaluated using the methyl tetrazolium (MTT) cytotoxicity test in HepG2 cell culture. PYRMP and PYRP have low glass transition temperatures of −68.8 and −59.6 °C, respectively. The polymers show a higher degradation rate at pH = 5.0 than at both pH = 7.4 and 8.0. The degradation process of PYRMP in different buffer solutions is discussed. The MTT test reveals that PYRMP at concentrations below 800 µg mL−1 and its hydrolysis products are non‐toxic to HepG2 cells. Moreover, the hydrolysis products diluted 10 times are able to promote cell proliferation. This study shows that polyphosphazene containing N‐ethoxypyrrolidone subsituents provides interesting perspectives for various biomedical applications. Copyright © 2009 Society of Chemical Industry
Lysophosphatidic acid receptor activation affects the C13NJ microglia cell line proteome leading to alterations in glycolysis, motility, and cytoskeletal architecture
Authors: Bernhart Eva , Kollroser Manfred , Rechberger Gerald , Reicher Helga , Heinemann Akos , Schratl Petra , Hallström Seth , Wintersperger Andrea , Nusshold Christoph , DeVaney Trevor , Zorn‐Pauly Klaus , Malli Roland , Graier Wolfgang , Malle Ernst , Sattler Wolfgang 
Published: November 2009

AbstractMicroglia, the immunocompetent cells of the CNS, are rapidly activated in response to injury and microglia migration towards and homing at damaged tissue plays a key role in CNS regeneration. Lysophosphatidic acid (LPA) is involved in signaling events evoking microglia responses through cognate G protein‐coupled receptors. Here we show that human immortalized C13NJ microglia express LPA receptor subtypes LPA1, LPA2, and LPA3 on mRNA and protein level. LPA activation of C13NJ cells induced Rho and extracellular signal‐regulated kinase activation and enhanced cellular ATP production. In addition, LPA induced process retraction, cell spreading, led to pronounced changes of the actin cytoskeleton and reduced cell motility, which could be reversed by inhibition of Rho activity. To get an indication about LPA‐induced global alterations in protein expression patterns a 2‐D DIGE/LC‐ESI‐MS proteomic approach was applied. On the proteome level the most prominent changes in response to LPA were observed for glycolytic enzymes and proteins regulating cell motility and/or cytoskeletal dynamics. The present findings suggest that naturally occurring LPA is a potent regulator of microglia biology. This might be of particular relevance in the pathophysiological context of neurodegenerative disorders where LPA concentrations can be significantly elevated in the CNS.
Analysis of protein glycation using phenylboronate acrylamide gel electrophoresis
Authors: Pereira Morais Marta P. , Mackay Julia D. , Bhamra Savroop K. , Buchanan J. Grant , James Tony D. , Fossey John S. , van den Elsen Jean M. H. 
Published: November 2009

AbstractThe incorporation of the specialized carbohydrate affinity ligand methacrylamido phenylboronic acid in polyacrylamide gels for SDS‐PAGE analysis has been successful for the separation of carbohydrates and has here been adapted for the analysis of post‐translationally modified proteins. While conventional SDS‐PAGE analysis cannot distinguish between glycated and unglycated proteins, methacrylamido phenylboronate acrylamide gel electrophoresis (mP‐AGE) in low loading shows dramatic retention of δ‐gluconolactone modified proteins, while the mobility of the unmodified proteins remains unchanged. With gels containing 1% methacrylamido phenylboronate, mP‐AGE analysis of gluconoylated recombinant protein Sbi results in the retention of the modified protein at a position expected for a protein that has quadrupled its expected molecular size. Subsequently, mP‐AGE was tested on HSA, a protein that is known to undergo glycation under physiological conditions. mP‐AGE could distinguish between various carbohydrate‐protein adducts, using in vitro glycated HSA, and discriminate early from late glycation states of the protein. Enzymatically glycosylated proteins show no altered retention in the phenylboronate‐incorporated gels, rendering this method highly selective for glycated proteins. We reveal that a trident interaction between phenylboronate and the Amadori cis 1,2 diol and amine group provides the molecular basis of this specificity. These results epitomize mP‐AGE as an important new proteomics tool for the detection, separation, visualization and identification of protein glycation. This method will aid the design of inhibitors of unwanted carbohydrate modifications in recombinant protein production, ageing, diabetes, cardiovascular diseases and Alzheimer's disease.
The effect of interfering ions on search algorithm performance for electron‐transfer dissociation data
Authors: Good David M. , Wenger Craig D. , Coon Joshua J. 
Published: November 2009

AbstractCollision‐activated dissociation and electron‐transfer dissociation (ETD) each produce spectra containing unique features. Though several database search algorithms (e.g. SEQUEST, MASCOT, and Open Mass Spectrometry Search Algorithm) have been modified to search ETD data, this consists chiefly of the ability to search for c‐ and z•‐ions; additional ETD‐specific features are often unaccounted for and may hinder identification. Removal of these features via spectral processing increased total search sensitivity by ∼20% for both human and yeast data sets; unique peptide identifications increased by ∼17% for the yeast data sets and ∼16% for the human data set.
A paradigm for the mechanisms and products of spontaneous polymerizations
Authors: Hall H. K. , Padias Anne Buyle 
Published: November 2009

AbstractIn spontaneous vinyl and ring‐opening copolymerizations, polar and resonance effects on the intermediates from bond‐forming initiation offer a continuous spectrum of reactivities and polymer structures. In bond‐forming initiation, an electron‐rich donor monomer forms a bond to an acceptor monomer. The donor monomer may be a vinyl monomer with O, N, or aryl substituent or it may be an aza‐ or oxacycle. The acceptor monomer may be a vinyl monomer carrying CN, COOR, or SO2R substituent or it may be a cyclic anhydride or maleimide. Beyond this, the donor may have a π‐like strained single bond, whereas the acceptor may be an electrophilic quinodimethane. Lewis acids may be used to enhance the electrophilicity of acceptor monomers. Reaction rates and polymer composition are determined by systematically varying the stability of the first intermediate, designated P (for polymethylene). The nature of the intermediate will vary from a highly reactive trans biradical, which initiates chain alternating copolymerization, to a cis/gauche zwitterion, which can initiate chain ionic homopolymerization, to an extremely stabilized zwitterion, which cannot add monomer, but builds up in concentration and terminates by combination, forming alternating copolymer. This model embraces the existing literature for a wide variety of monomers and possesses predictive power. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009
Synthesis, self‐assembly and drug‐loading capacity of well‐defined drug‐conjugated amphiphilic A2B2 type miktoarm star copolymers based on poly(ε‐caprolactone) and poly(ethylene glycol)
Authors: Gou Peng‐Fei , Zhu Wei‐Pu , Xu Ning , Shen Zhi‐Quan 
Published: November 2009

AbstractWell‐defined drug‐conjugated amphiphilic A2B2 miktoarm star copolymers [(PCL)2‐(PEG)2‐D] were prepared by the combination of controlled ring‐opening polymerization (CROP) and “click” reaction strategy. First, bromide functionalized poly(ε‐caprolactone) (PCL‐Br) with double hydroxyl end groups was synthesized by the CROP of ε‐caprolactone using 2,2‐bis(bromomethyl)propane‐1,3‐diol as a difunctional initiator in the presence of Sn(Oct)2 at 110 °C. Next, the bromide groups of PCL‐Br were quantitatively converted to azide form by NaN3 to give PCL‐N3. Subsequently, the end hydroxyl groups of PCL‐N3 were capped with ibuprofen as a model drug at room temperature. Finally, copper(I)‐catalyzed cycloaddition reaction between ibuprofen‐conjugated PCL‐N3 and slightly excess alkyne‐terminated poly(ethylene glycol) (A‐PEG) led to ibuprofen‐conjugated A2B2 miktoarm star copolymer [(PCL)2‐(PEG)2‐D]. The excess A‐PEG was removed by dialysis. 1H NMR, FTIR and SEC analyzes confirmed the expected miktoarm star architecture. These amphiphilic miktoarm star copolymers could self‐assemble into multimorphological aggregates in aqueous solution, which were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). In addition, the drug‐loading capacity of these drug‐conjugated miktoarm star copolymers as well as their nondrug‐conjugated analogs were also investigated in detail. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009
Kinetic studies of surface‐initiated atom transfer radical polymerization in the synthesis of magnetic fluids
Authors: Kaiser Andreas , Dutz Silvio , Schmidt Annette M. 
Published: November 2009

AbstractWe present results from kinetic studies on the surface‐initiated atom transfer radical polymerization in the preparation of polymer brush‐coated magnetic particles from a heterogeneous system. It is shown that a controlled reaction behavior and a reproducible surface functionalization with end‐tethered polymers are achieved, although the reaction advances gradually from a biphasic solid–liquid mixture to a stable colloidal dispersion of the nanoobjects. Although the initiator‐functional magnetite nanoparticles initially form a precipitate, the formation of a polymer layer on the particle surface in the course of the reaction contributes to a sterical stabilization in dispersion. We thoroughly investigated the development of the initial heterogeneous system with time and in various concentration regimes by simultaneously monitoring the monomer conversion, molar mass, the hydrodynamic diameter of the nanoobjects, and the magnetite content of the dispersions at different reaction times. The results indicate first‐order chain growth kinetics with respect to the monomer and narrow molar mass distributions, demonstrating good control on the particle architecture. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009
LCST‐type liquid–liquid and liquid–solid phase transition behaviors of hyperbranched polyglycerol bearing imidazolium salt
Authors: Tamaki Masaki , Taguchi Tsukasa , Kitajyo Yoshikazu , Takahashi Kenji , Sakai Ryosuke , Kakuchi Toyoji , Satoh Toshifumi 
Published: November 2009

AbstractA hyperbranched polyglycerol bearing imidazolium tosylate units (ITHB) was synthesized through the imidazolium salt‐modification of hyperbranched polyglycerol (HB). ITHB was found to possess novel reversible lower critical solution temperature (LCST)‐type liquid–liquid and liquid–solid phase transition behaviors in a methanol/chloroform mixed solution. The phase transition temperatures of the liquid–liquid phase transition (PTT1to2) and liquid–solid phase transition (PTT2toSus) increased with increasing the ratio of methanol in the mixed solution and decreasing the concentration of ITHB. Additionally, increasing the molecular weight of ITHB decreased the PTT values. The liquid–liquid phase transition was caused by the aggregation of ITHB, which was proved by dynamic light scattering measurement. In contrast, the liquid–solid phase transition was caused by the solvation cleavage between the imidazolium rings and solvents, which was proved by 1H NMR measurement. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009
Synthesis of twin‐tail tadpole‐shaped hydrophilic copolymers and their thermo‐responsive behavior
Authors: Li Li‐Ying , He Wei‐Dong , Li Jian , Han Shou‐Chen , Sun Xiao‐Li , Zhang Bo‐Yu 
Published: November 2009

AbstractTwin‐tail tadpole‐shaped hydrophillic copolymers composed of cyclic poly(ethylene gycol) (PEG) and two linear poly(N‐isopropylacrylamide) (PNIPAM) chains have been successfully synthesized by the combination of single‐electron‐transfer living radical polymerization and click chemistry under high concentration. Click cycloaddition reaction occurred between linear PNIPAM‐b‐PEG‐b‐PNIPAM with two azide groups at block junctions and dipropargyl oxalylate with high yield and efficiency. The resulting intermediates and the targeted polymers were characterized by proton nuclear magnetic resonance, fourier transform infrared spectroscopy, and gel permeation chromatography. The thermal phase transition behaviors of twin‐tail tadpole‐shaped polymers and their linear precursors were investigated by temperature‐dependent turbidity measurements, micro differential scanning calorimetry, and laser light scattering. The twin‐tail tadpole‐shaped polymers possess higher critical solution temperature (LCST) and smaller average aggregate size compared with their linear precursors with the same molecular weight. The above differences in the thermal phase transition behaviors should be due to the repulsive forces caused by the ring topology, which prohibited the intermolecular association. © 2009 Wiley Periodicals, © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009
Crystallographic and mass spectrometric analyses of a tandem GNAT protein from the clavulanic acid biosynthesis pathway
Authors: Iqbal Aman , Arunlanantham Haren , Brown Tom , Chowdhury Rasheduzzaman , Clifton Ian J. , Kershaw Nadia J. , Hewitson Kirsty S. , McDonough Michael A. , Schofield Christopher J. 
Published: November 2009

Abstract(3R,5R)‐Clavulanic acid (CA) is a clinically important inhibitor of Class A β‐lactamases. Sequence comparisons suggest that orf14 of the clavulanic acid biosynthesis gene cluster encodes for an acetyl transferase (CBG). Crystallographic studies reveal CBG to be a member of the emerging structural subfamily of tandem Gcn5‐related acetyl transferase (GNAT) proteins. Two crystal forms (C2 and P21 space groups) of CBG were obtained; in both forms one molecule of acetyl‐CoA (AcCoA) was bound to the N‐terminal GNAT domain, with the C‐terminal domain being unoccupied by a ligand. Mass spectrometric analyzes on CBG demonstrate that, in addition to one strongly bound AcCoA molecule, a second acyl‐CoA molecule can bind to CBG. Succinyl‐CoA and myristoyl‐CoA displayed the strongest binding to the “second” CoA binding site, which is likely in the C‐terminal GNAT domain. Analysis of the CBG structures, together with those of other tandem GNAT proteins, suggest that the AcCoA in the N‐terminal GNAT domain plays a structural role whereas the C‐terminal domain is more likely to be directly involved in acetyl transfer. The available crystallographic and mass spectrometric evidence suggests that binding of the second acyl‐CoA occurs preferentially to monomeric rather than dimeric CBG. The N‐terminal AcCoA binding site and the proposed C‐terminal acyl‐CoA binding site of CBG are compared with acyl‐CoA binding sites of other tandem and single domain GNAT proteins. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Ultraviolet photodissociation at 266 nm of phosphorylated peptide cations
Authors: Park Soojin , Ahn Wha‐Keun , Lee Sunyoung , Han Sang Yun , Rhee Bum Ku , Oh Han Bin 
Published: November 2009

AbstractUltraviolet (UV) photodissociation (PD) experiments using 266 nm light were performed for a series of phosphopeptide cations in a Fourier transform mass spectrometer. The objective of the experiments was to determine whether 266 nm UV irradiation on the phosphopeptide cations would induce unique peptide backbone dissociation. In addition, the general behavior of the phosphate loss (−80 or −98 Da) was monitored, particularly for those phosphopeptides with a phosphotyrosine residue that itself is a UV chromophore. For phosphopeptides with a UV chromophore, their photodissociation behavior was very similar to that of low‐energy sustained off‐resonance irradiation collisionally activated dissociation (SORI‐CAD), with a few exceptions. For example, b‐ and y‐type peptide backbone fragments were prevalent, and their dephosphorylation behavior was consistent with that of the SORI‐CAD results. For phosphoserine peptides, the loss of a phosphate group was always observed. On the other hand, for phosphotyrosine peptides, the phosphate loss was found to be dependent on the presence of a basic amino group in the sequence and the charge state of the precursor ions, in agreement with the CAD results in the literature. However, hydrogen atom loss or aromatic side chain loss, which is known to be the excited state specific fragmentation pathway, was rarely observed in our 266 nm UV PD experiments, in contrast to the previous UV PD literature (particularly at 220 nm). The mechanism for these observations is described in terms of dominant internal conversion followed by intramolecular vibrational energy redistribution (IVR). Copyright © 2009 John Wiley & Sons, Ltd.
Differences in the stable isotope signatures of seabird egg membrane and albumen – implications for non‐invasive studies
Authors: Quillfeldt Petra , McGill Rona A. R. , Masello Juan F. , Poisbleau Maud , van Noordwijk Hendrika , Demongin Laurent , Furness Robert W. 
Published: November 2009

AbstractIn many bird species, egg membranes can be obtained non‐invasively after the chicks have hatched, and stable isotope analysis of egg membranes can be used to study the diet and foraging distribution of these birds during egg formation. It has been suggested that the enrichment factors of albumen and egg membranes differ for 13C, but are similar for 15N. In this study, we compared carbon and nitrogen stable isotopes of the membranes and albumen of individual eggs of three wild seabird species, the Southern Rockhopper penguin Eudyptes chrysocome, the Imperial shag Phalacrocorax atriceps albiventer, and the Thin‐billed prion Pachyptila belcheri. We also included chicken eggs for comparison. Egg membranes were generally enriched in 13C, compared with albumen. The difference varied between species, with 2.1‰ in Rockhopper penguins, 1.6‰ in Imperial shags, but only 0.5‰ in Thin‐billed prions and 0.4‰ in chicken eggs. Egg membranes were slightly enriched in 15N in Imperial shags (0.9‰) and chickens (0.5‰), compared with albumen, while there was no difference for Thin‐billed prions and Rockhopper penguins. The isotopic values of carbon and nitrogen were correlated between albumen and egg membranes of individual eggs, suggesting that egg membranes can be used reliably to investigate trophic differences between individuals, seasons or colonies. Species‐specific mathematical corrections could be used to compare results across studies that use different egg components. Copyright © 2009 John Wiley & Sons, Ltd.
Simultaneous quantitation of testosterone, estradiol, ethinyl estradiol, and 11‐ketotestosterone in fathead minnow fish plasma by liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry
Authors: Zhang Fagen , Bartels Michael J. , Geter David R. , Carr Melissa S. , McClymount Lynn E. , Marino Troy A. , Klecka Gary M. 
Published: November 2009

AbstractIn the present work, for the first time, a rapid and sensitive liquid chromatography/positive atmospheric pressure photoionization tandem mass spectrometry (LC/APPI‐MS/MS) method has been developed and validated for the simultaneous quantitation of testosterone, estradiol, ethinyl estradiol, and 11‐ketotestosterone in fathead minnow fish plasma using no more than 10 µL of plasma. Compounds present in plasma were directly derivatized with dansyl chloride and 25 µL of the derivatized mixture was injected into the LC/APPI‐MS/MS system. The gradient chromatographic elution was achieved on an Agilent Zorbax SB‐C18 analytical column (2.1 mm × 50 mm, 1.8 µm particle size) with mobile phases consisting of acetonitrile, water and acetic acid. The flow rate was 0.5 to 0.7 mL/min and the total run time was 11.5 min. The lower limits of quantitation for testosterone, estradiol, ethinyl estradiol, and 11‐ketotestosterone and were 1, 1, 1, and 2.5 ng/mL, respectively. Intra‐batch precision was less than 19.4% and inter‐batch precision was less than 11.7% for all four analytes. Accuracy was within 83.5–115.4% of nominal concentrations. This method is used for quantitation of sex steroid levels in fathead minnow tested in endocrine disruptor screening experiments. Copyright © 2009 John Wiley & Sons, Ltd.