bluuebunny/crossref_metadata_2025_split huggingface dataset:
Positive chemical ionization triple‐quadrupole mass spectrometry and ab initio computational studies of the multi‐pathway fragmentation of phthalates
Authors: Jeilani Yassin A. , Cardelino Beatriz H. , Ibeanusi Victor M. 
Published: May 2010

AbstractWe report the first positive chemical ionization (PCI) fragmentation mechanisms of phthalates using triple‐quadrupole mass spectrometry and ab initio computational studies using density functional theories (DFT). Methane PCI spectra showed abundant [M + H]+, together with [M + C2H5]+ and [M + C3H5]+. Fragmentation of [M + H]+, [M + C2H5]+ and [M + C3H5]+ involved characteristic ions at m/z 149, 177 and 189, assigned as protonated phthalic anhydride and an adduct of phthalic anhydride with C2H5+ and C3H5+, respectively. Fragmentation of these ions provided more structural information from the PCI spectra. A multi‐pathway fragmentation was proposed for these ions leading to the protonated phthalic anhydride. DFT methods were used to calculate relative free energies and to determine structures of intermediate ions for these pathways. The first step of the fragmentation of [M + C2H5]+ and [M + C3H5]+ is the elimination of [RH] from an ester group. The second ester group undergoes either a McLafferty rearrangement route or a neutral loss elimination of ROH. DFT calculations (B3LYP, B3PW91 and BPW91) using 6‐311G(d,p) basis sets showed that McLafferty rearrangement of dibutyl, di(‐n‐octyl) and di(2‐ethyl‐n‐hexyl) phthalates is an energetically more favorable pathway than loss of an alcohol moiety. Prominent ions in these pathways were confirmed with deuterium labeled phthalates. Copyright © 2010 John Wiley & Sons, Ltd.
Predictors of poor sleep quality among head and neck cancer patients
Authors: Shuman Andrew G. , Duffy Sonia A. , Ronis David L. , Garetz Susan L. , McLean Scott A. , Fowler Karen E. , Terrell Jeffrey E. 
Published: May 2010

AbstractObjectives/Hypothesis:The objective of this study was to determine the predictors of sleep quality among head and neck cancer patients 1 year after diagnosis.Study Design:This was a prospective, multisite cohort study of head and neck cancer patients (N = 457).Methods:Patients were surveyed at baseline and 1 year after diagnosis. Chart audits were also conducted. The dependent variable was a self‐assessed sleep score 1 year after diagnosis. The independent variables were a 1 year pain score, xerostomia, treatment received (radiation, chemotherapy, and/or surgery), presence of a feeding tube and/or tracheotomy, tumor site and stage, comorbidities, depression, smoking, problem drinking, age, and sex.Results:Both baseline (67.1) and 1‐year postdiagnosis (69.3) sleep scores were slightly lower than population means (72). Multivariate analyses showed that pain, xerostomia, depression, presence of a tracheotomy tube, comorbidities, and younger age were statistically significant predictors of poor sleep 1 year after diagnosis of head and neck cancer (P < .05). Smoking, problem drinking, and female sex were marginally significant (P < .09). Type of treatment (surgery, radiation and/or chemotherapy), primary tumor site, and cancer stage were not significantly associated with 1‐year sleep scores.Conclusions:Many factors adversely affecting sleep in head and neck cancer patients are potentially modifiable and appear to contribute to decreased quality of life. Strategies to reduce pain, xerostomia, depression, smoking, and problem drinking may be warranted, not only for their own inherent value, but also for improvement of sleep and the enhancement of quality of life. Laryngoscope, 2010
Analytical Ultracentrifugation of Model Nanoparticles: Comparison of Different Analysis Methods
Authors: Mittal Vikas , Völkel Antje , Cölfen Helmut 
Published: May 2010

AbstractSedimentation analysis of nanoparticle (ZrO2 and SiO2) suspensions of different particle sizes in various solvents as nanoparticle model systems was carried out using interference optics in the analytical ultracentrifuge. The particles differed in their morphology: SiO2 particles were spherical, whereas ZrO2 particles were in one case spherical and in the second case non‐spherical and spherical. Different analysis programs, based on different principles of data analysis, were used for the evaluation of the size distributions of these particles, viz. SEDFIT [ls–g*(s), c(s)], UltraScan (vHW, 2DSA‐MC), SedAnal (dcdt) and VelXLAI (GFL) method and SedAnal, in order to ascertain the benefits and limitations of these analysis methods in characterising the examined nanoparticles.magnified image
Randomization of Amyloid‐β‐Peptide(1‐42) Conformation by Sulfonated and Sulfated Nanoparticles Reduces Aggregation and Cytotoxicity
Authors: Saraiva Ana M. , Cardoso Isabel , Saraiva Maria João , Tauer Klaus , Pereira M. Carmo , Coelho Manuel A. N. , Möhwald Helmuth , Brezesinski Gerald 
Published: May 2010

AbstractThe amyloid‐β peptide (Aβ) plays a central role in the mechanism of Alzheimer's disease, being the main constituent of the plaque deposits found in AD brains. Aβ amyloid formation and deposition are due to a conformational switching to a β‐enriched secondary structure. Our strategy to inhibit Aβ aggregation involves the re‐conversion of Aβ conformation by adsorption to nanoparticles. NPs were synthesized by sulfonation and sulfation of polystyrene, leading to microgels and latexes. Both polymeric nanostructures affect the conformation of Aβ inducing an unordered state. Oligomerization was delayed and cytotoxicity reduced. The proper balance between hydrophilic moieties and hydrophobic chains seems to be an essential feature of effective NPs.magnified image
Developments in the US‐SOMO Bead Modeling Suite: New Features in the Direct Residue‐to‐Bead Method, Improved Grid Routines, and Influence of Accessible Surface Area Screening
Authors: Brookes Emre , Demeler Borries , Rocco Mattia 
Published: May 2010

AbstractThe US‐SOMO suite provides a flexible interface for accurately computing solution parameters from 3D structures of biomacromolecules through bead‐modeling approaches. We present an extended analysis of the influence of accessible surface area screening, overlap reduction routines, and approximations for non‐coded residues and missing atoms on the computed parameters for models built by the residue‐to‐bead direct correspondence and the cubic grid methods. Importantly, by taking the theoretical hydration into account at the atomic level, the performance of the grid‐type models becomes comparable or exceeds that of the corresponding hydrated residue‐to‐bead models.magnified image
Fabrication of Aromatic‐Aliphatic Aminoketone Polymers with Terminal Fluorine Groups
Authors: Anders Susann , Schrepp Wolfgang , Kaßner Lysann , Pohlers Andreas , Hoyer Walter , Spange Stefan 
Published: May 2010

AbstractA procedure for synthesis aromatic‐aliphatic PAK, completely functionalized withp‐fluorophenyl terminal groups, is presented. This synthesis uses the nucleophilic aromatic substitution of DFB with various secondary aliphatic diamines [CH3NH(CH2)mNHCH3] (m = 3, 6, and 8) and cesium fluoride as the base catalyst in the melt. The linearity and the complete functionalization of the PAK compounds withp‐fluorophenyl terminal groups are demonstrated with the aid of MALDI TOF mass spectrometry. PAK compounds are semi‐crystalline as shown by WAXS and DSC measurements. The degree of crystallinity ranges between 2 and 25%. Nucleophilic aromatic substitution reactions in the fluorine end groups are demonstrated by reaction of PAK (m = 6) with the strongS‐nucleophile mercaptoacetic acid.magnified image
Determination of Gel Point of Epoxy Thermosets via Electric Resistance Measurements
Authors: Wasikiewicz Jaroslaw M. , Yeates Stephen G. 
Published: May 2010

AbstractA new, nickel‐coated graphite resistance‐change‐based method for gel‐point determination for epoxy‐based thermoset resins is presented and compared with DSC and rheological methods. Gelation times determined by this new method are in very good agreement with conventional techniques; this new method is potentially simpler and less time consuming than existing ones.magnified image
Natural Fiber Welding
Authors: Haverhals Luke M. , Reichert W. Matthew , De Long Hugh C. , Trulove Paul C. 
Published: May 2010

AbstractA process we term “natural fiber welding” is demonstrated by which loose fibers are transformed to create a congealed network using an IL solvent. Several examples are discussed that include cellulosic and protein‐based materials. SEM shows the fusion of fibers upon treatment. XRD and FT‐IR spectroscopy of cellulosic materials show that significant amounts of the native polymer structure are retained after the process is completed. Data suggest that material at the fiber exterior is preferentially transformed while material in the fiber core is left in the native state. Data also demonstrate that the amount of material modified can be tailored by control of variables such as the IL solvent concentration, the process temperature, and the processing time.magnified image
One‐Step Immobilization of Protein‐Encapsulated Core/Shell Particles onto Nanofibers
Authors: Park Chul Ho , Lee Jonghwi 
Published: May 2010

AbstractA novel method is described to functionalize nanofibers to form a nanocomposite with core/shell particles in order to control protein release. The nanocomposite is produced by electrically neutralizing negatively charged poly(lactic acid) nanofibers with positively charged poly[(lactic acid)‐co‐(glycolic acid)] particles via a one‐step electrohydrodynamic jetting process. The protein‐encapsulated core/shell particles exhibited no significant initial burst release or denaturation. The protein release profile was controlled by porosity and protein/polymer interactions. The method may be promising to engineer intelligent scaffolds that can fulfill the needs of biomimetic materials.magnified image
Synthesis of Guanidinium‐Modified Hyaluronic Acid Hydrogel
Authors: Varghese Oommen P. , Kisiel Marta , Martínez‐Sanz Elena , Ossipov Dmitri A. , Hilborn Jöns 
Published: May 2010

AbstractIn this report, a new guanidinylating reagent is presented, which was developed without any protection/deprotection strategy and was successfully employed for linking to hyaluronan in aqueous solution. The dually functionalised HA biopolymer bearing guanidinium and hydrazide groups was synthesised to form hydrogel in less than a minute when mixed with aldehyde‐modified HA. This hydrogel exhibited higher storage modulus with enhanced stability in PBS when compared to the non‐guanidine‐containing gel. The gel shift assay showed that this biopolymer formed a stable complex with DNA as well as efficient gene transfection to cells that express HA‐receptor CD44. The toxicity studies of this polymer with fibroblast cells revealed that the cells were almost 80% viable after 4 d of incubation at high HA concentration (2.5 × 10−3 M).magnified image
Tandem gait performance in essential tremor: Clinical correlates and association with midline tremors
Authors: Louis Elan D. , Rios Eileen , Rao Ashwini K. 
Published: May 2010

AbstractGait difficulty has been reported in essential tremor (ET) although it has been the subject of a limited number of studies. We broadly assessed these clinical correlates, including the association of gait difficulty with a variety of midline tremors (jaw, voice, neck). Tandem gait (10 steps) was assessed in 122 ET cases. Cranial tremor score (0–3) was the number of locations (neck, jaw, voice) in which tremor was present. Number of tandem mis‐steps positively correlated with age (P < 0.001), age of tremor onset (P = 0.001), and presence of neck (P < 0.001), jaw (P = 0.001), and voice tremors (P = 0.047). Number of tandem mis‐steps increased markedly with cranial tremor score: 0 (0.8 ± 1.2), 1 (1.1 ± 1.6), 2 (2.3 ± 3.0), 3 (3.7 ± 1.6) (P < 0.001). It was not correlated with severity of arm or leg tremors. ET patients with cranial tremors (neck, jaw, voice), those with older age of onset, and those of current older age are more likely to manifest tandem gait difficulty. Tandem gait difficulty was not correlated with severity of limb tremors. Tandem gait difficulty and cranial tremors in ET may both be symptomatic of the same underlying pathophysiology, a disturbance of cerebellar regulation of the midline, which is distinct from its regulation of the limbs. © 2010 Movement Disorder Society
Probabilistic Modeling of Conformational Space for 3D Machine Learning Approaches
Authors: Jahn Andreas , Hinselmann Georg , Fechner Nikolas , Henneges Carsten , Zell Andreas 
Published: May 2010

AbstractWe present a new probabilistic encoding of the conformational space of a molecule that allows for the integration into common similarity calculations. The method uses distance profiles of flexible atom‐pairs and computes generative models that describe the distance distribution in the conformational space. The generative models permit the use of probabilistic kernel functions and, therefore, our approach can be used to extend existing 3D molecular kernel functions, as applied in support vector machines, to build QSAR models. The resulting kernels are valid 4D kernel functions and reduce the dependency of the model quality on suitable conformations of the molecules. We showed in several experiments the robust performance of the 4D kernel function, which was extended by our approach, in comparison to the original 3D‐based kernel function. The new method compares the conformational space of two molecules within one kernel evaluation. Hence, the number of kernel evaluations is significantly reduced in comparison to common kernel‐based conformational space averaging techniques. Additionally, the performance gain of the extended model correlates with the flexibility of the data set and enables an a priori estimation of the model improvement.
In vitro derivation of germ cells from embryonic stem cells in mammals
Authors: Zhou Guang‐Bin , Meng Qing‐Gang , Li Ning 
Published: May 2010

AbstractPrevious reports have shown that embryonic stem (ES) cells, derived from the inner cell mass of mouse or human blastocysts, could differentiate in vitro into female and male germ cells as well as into the cell types of all three germ layers. While in one case, the ES cell‐derived germ cells have been reported to give birth to live offspring in the mouse, these cells differ in fertilization capacity from the sperm and oocytes produced in vivo as they cannot complete meiosis under in vitro conditions. The efficiency of functional germ cell isolation from ES cells is also low. According to published reports, factors such as the proper selection of feeder cells, including ovarian granulosa cells and those which could secrete bone morphogenic protein‐4 (BMP4), and the addition of retinoic acid into culture medium, could to some extent establish and improve the microenvironment ES cells rely on for differentiation into germ cells. This review briefly describes the progress of deriving germ cells from ES cells and discusses possible factors that could improve in vitro gamete production. Mol. Reprod. Dev. 77: 586–594, 2010. © 2010 Wiley‐Liss, Inc.
Epidermal growth factor (EGF) induces motility and upregulates MMP‐9 and TIMP‐1 in bovine trophoblast cells
Authors: Dilly M. , Hambruch N. , Haeger J.‐D. , Pfarrer C. 
Published: May 2010

AbstractDifferentiation and restricted invasion/migration of trophoblast cells are crucial for feto‐maternal communication in the synepitheliochorial placenta of cattle. EGF is expressed in the bovine placenta and likely regulates these cell properties. As cell migration and motility rely on the degradation of extracellular matrix we hypothesize that EGF is involved in the regulation of the MMP‐9/TIMP‐1 balance and thus could influence trophoblast migration, tissue remodeling, and the release of the fetal membranes after parturition. The aim of this in vitro study was to examine EGF‐mediated effects on cell motility, proliferation, and MMP‐9 and TIMP‐1 expression in cultured bovine trophoblast cells. We used a trophoblast cell line (F3) derived from bovine placentomes to examine the influence of EGF on MMP‐9 and TIMP‐1 expression by semiquantitative RT‐PCR and MMP activity by zymography. Migration assays were performed using a Boyden chamber and cell motility was measured by time‐lapse analyses. To identify the involved signaling cascades, phosphorylation of mitogen‐activated protein kinase (MAPK) 42/44 and Akt was detected by Western blot. EGF treatment increased both the abundance of MMP‐9 and TIMP‐1 mRNAs and the proteolytic activity of MMP‐9. Furthermore, EGF stimulated proliferation and migration of F3 cells. Addition of specific inhibitors of MAPK (PD98059) and/or PI3K (LY294002) activation abolished or reduced EGF‐induced effects in all experiments. In conclusion, EGF‐mediated effects stimulate migration and proliferation of bovine trophoblast cells and may be involved in bovine placental tissue remodeling and postpartum release of fetal membranes. Mol. Reprod. Dev. 77: 622–629, 2010. © 2010 Wiley‐Liss, Inc.
Real‐time adaptive sequential design for optimal acquisition of arterial spin labeling MRI data
Authors: Xie Jingyi , Clare Stuart , Gallichan Daniel , Gunn Roger N. , Jezzard Peter 
Published: May 2010

AbstractAn optimal sampling schedule strategy based on the Fisher information matrix and the D‐optimality criterion has previously been proposed as a formal framework for optimizing inversion time scheduling for multi‐inversion‐time arterial spin labeling experiments. Optimal sampling schedule possesses the primary advantage of improving parameter estimation precision but requires a priori estimation of plausible parameter distributions that may not be available in all situations. An adaptive sequential design approach addresses this issue by incorporating the optimal sampling schedule strategy into an adaptive process that iteratively updates the parameter estimates and adjusts the optimal sampling schedule accordingly as data are acquired. In this study, the adaptive sequential design method was experimentally implemented with a real‐time feedback scheme on a clinical MRI scanner and was tested in six normal volunteers. Adapted schedules were found to accommodate the intrinsically prolonged arterial transit times in the occipital lobe of the brain. Simulation of applying the adaptive sequential design approach on subjects with pathologically reduced perfusion was also implemented. Simulation results show that the adaptive sequential design approach is capable of incorporating pathologic parameter information into an optimal arterial spin labeling scheduling design within a clinically useful experimental time. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
In vivo MR evaluation of the effect of the CCR2 antagonist on macrophage migration
Authors: Lee Yedaun , Ryu Je‐Won , Chang Hyeujin , Sohn Jin Young , Lee Kyung Won , Woo Chul Woong , Kang Hee Jung , Jeong Seong‐Yun , Choi Eun Kyung , Lee Jin Seong 
Published: May 2010

AbstractThe CCR2 antagonist is a receptor antagonist for monocyte chemoattractant protein‐1 and is known to be a potential anti‐inflammatory therapeutic agent. Recently used optimized labeling techniques for superparamagnetic iron oxide, macrophage homing, and recruitment toward the infection site can be observed on in vivo MRI. This study details the effect of the CCR2 antagonist on the macrophage migration and the feasibility of in vivo MRI for assessing the inhibition of chemotactic activity by the CCR2 antagonist. On binding assay, the CCR2 antagonist inhibits the binding affinity of monocyte chemoattractant protein‐1 to CCR2. Increased expression of messenger ribonucleic acid (mRNA) and expression of CCR2 and CD11b on the cellular surface, as induced by monocyte chemoattractant protein‐1, was shown, and the effect of monocyte chemoattractant protein‐1 on CCR2 and CD11b was restricted by the CCR2 antagonist. In a migration test using the transwell system, macrophages treated with the CCR2 antagonist showed significantly decreased chemotactic migration compared to that of wild‐type macrophages. MR images of infected left calf muscles in 12 mice were obtained 24 h after administration of macrophages labeled with superparamagnetic iron oxide. MRI successfully demonstrated the effect of the CCR2 antagonist on the directional migration of macrophages. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
A high‐throughput eight‐channel probe head for murine MRI at 9.4 T
Authors: Lanz Titus , Müller Matthias , Barnes Hannah , Neubauer Stefan , Schneider Jürgen E. 
Published: May 2010

AbstractMurine MRI studies are conducted on dedicated MR systems, typically equipped with ultra‐high‐field magnets (≥4.7 T; bore size: ∼12–25 cm), using a single transmit‐receive coil (volume or surface coil in linear or quadrature mode) or a transmit‐receive coil combination. Here, we report on the design and characterization of an eight‐channel volume receive‐coil array for murine MRI at 400 MHz. The array was combined with a volume‐transmit coil and integrated into one probe head. Therefore, the animal handling is fully decoupled from the radiofrequency setup. Furthermore, fixed tune and match of the coils and a reduced number of connectors minimized the setup time. Optimized preamplifier design was essential for minimizing the noise coupling between the elements. A comprehensive characterization of transmit volume resonator and receive coil array is provided. The performance of the coil array is compared to a quadrature‐driven birdcage coil with identical sensitive volume. It is shown that the miniature size of the elements resulted in coil noise domination and therefore reduced signal‐to‐noise‐ratio performance in the center compared to the quadrature birdcage. However, it allowed for 3‐fold accelerated imaging of mice in vivo, reducing scan time requirements and thus increasing the number of mice that can be scanned per unit of time. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Reduction of fast spin echo cusp artifact using a slice‐tilting gradient
Authors: Rangwala Novena , Zhou Xiaohong Joe 
Published: May 2010

AbstractA “featherlike” artifact, termed a cusp artifact, is sometimes seen along the phase‐encoding direction in sagittal or coronal fast spin echo images. This artifact arises from the spins, at a location distant from the magnet isocenter, that are excited and aliased to the field of view because their precession frequency is similar to those at the isocenter. Such a situation is created due to a combination of excessive gradient nonlinearity and rapid change of the main magnetic field near the edge of the magnet where the artifact‐producing spins are located. A novel technique is proposed to reduce this artifact, in which a fast spin echo pulse sequence is modified to slightly tilt the slice selected by the radiofrequency excitation pulse away from the slice selected by the radiofrequency refocusing pulses. At the edge of the field of view, the incomplete overlap between the slices selected by the excitation and refocusing pulses effectively reduces the signals from the artifact‐prone region. In contrast, the slices overlap substantially within the field of view so that the signals are largely retained. This slice‐tilting technique has been implemented on two commercial MRI scanners operating at 3.0 T and 1.5 T, respectively, and evaluated on phantoms and human spine and extremities using clinical protocols. Both phantom and human results showed that the technique decreased the strength of the cusp artifact by at least 65% and substantially limited the spatial extent of the artifact. This technique, which can be further enhanced by a simple postprocessing step, offers significant advantages over a number of other techniques for reducing the fast spin echo cusp artifact. It can be implemented on virtually any scanner without hardware modification, complicated calibration, sophisticated image reconstruction, or patient‐handling alteration. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.