bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of copolypeptides on amyloid fibrillation of hen egg‐white lysozyme
Authors: Wen Wen‐Sing , Lai Jun‐Kun , Lin Yu‐Jiun , Lai Chia‐Min , Huang Yun‐Chiao , Wang Steven S.‐S. , Jan Jeng‐Shiung 
Published: August 2011

AbstractThe fibrillation of hen egg‐white lysozyme (HEWL) in the absence and presence of simple, unstructured D,L‐lysine‐co‐glycine (D,L‐Lys‐co‐gly) and D,L‐lysine‐co‐L‐phenylalanine (D,L‐Lys‐co‐Phe) copolypeptides was studied by using a variety of analytical techniques. The attenuating and decelerating effects on fibrillation are significantly dependent on the polypeptide concentration and the composition ratios in the polypeptide chain. Interestingly, D,L‐Lys‐co‐gly and D,L‐Lys‐co‐Phe copolypeptides with the same composition ratio have comparable attenuating effects on fibrillation. The copolypeptide with highest molar fraction of glycine residue exhibits the strongest suppression of HEWL fibrillation. The copolypeptide has the highest hydrophobic interacting capacity due to the more molar ratio of apolar monomer in the polymer backbone. The major driving forces for the association of HEWL and copolypeptides are likely to be hydrogen bonding and hydrophobic interactions, and these interactions reduce the concentration of free protein in solution available to proceed to fibrillation, leading to the increase of lag time and attenuation of fibrillation. The results of this work may contribute to the understanding of the molecular factors affecting amyloid fibrillation and the molecular mechanism(s) of the interactions between the unstructured polypeptides and the amyloid proteins. © 2011 Wiley Periodicals, Inc. Biopolymers 97:107–116, 2012.
Polyethylene glycol behaves like weak organic solvent
Authors: Hirano Atsushi , Shiraki Kentaro , Arakawa Tsutomu 
Published: August 2011

AbstractEffect of polyethylene glycol (PEG) on protein solubility has been primarily ascribed to its large hydrodynamic size and thereby molecular crowding effect. However, PEG also shows characteristics of organic solvents. Here, we have examined the solubility of glycine and aliphatic and aromatic amino acids in PEG solutions. PEG400, PEG4000, and PEG20000 decreased the solubility of glycine, though to a much smaller magnitude than the level achieved by typical organic solvents, including ethanol and dimethyl sulfoxide. PEG4000 showed varying degree of interactions with amino acid side chains. The free energy of aliphatic side chains marginally increased by the addition of PEG4000, indicating their weak unfavorable interactions. However, it significantly decreased the free energy of the aromatic side chains and hence stabilized them. Thus, it was concluded that PEG behaves like weak organic solvents; namely PEG destabilized (interacted unfavorably with) polar and charged groups and stabilized (interacted favorably with) aromatic groups. Interestingly, the interaction of PEG20000, but neither PEG400 nor PEG4000, with glycine resulted in phase separation under the saturated concentration of glycine. © 2011 Wiley Periodicals, Inc. Biopolymers 97: 117–122, 2012.
Validation of long‐term primary neuronal cultures and network activity through the integration of reversibly bonded microbioreactors and MEA substrates
Authors: Biffi Emilia , Menegon Andrea , Piraino Francesco , Pedrocchi Alessandra , Fiore Gianfranco B. , Rasponi Marco 
Published: August 2011

AbstractIn vitro recording of neuronal electrical activity is a widely used technique to understand brain functions and to study the effect of drugs on the central nervous system. The integration of microfluidic devices with microelectrode arrays (MEAs) enables the recording of networks activity in a controlled microenvironment. In this work, an integrated microfluidic system for neuronal cultures was developed, reversibly coupling a PDMS microfluidic device with a commercial flat MEA through magnetic forces. Neurons from mouse embryos were cultured in a 100 µm channel and their activity was followed up to 18 days in vitro. The maturation of the networks and their morphological and functional characteristics were comparable with those of networks cultured in macro‐environments and described in literature. In this work, we successfully demonstrated the ability of long‐term culturing of primary neuronal cells in a reversible bonded microfluidic device (based on magnetism) that will be fundamental for neuropharmacological studies. Biotechnol. Bioeng. 2012;109: 166–175. © 2011 Wiley Periodicals, Inc.
Recent application of analytical methods to phase I and phase II drugs development: a review
Authors: Locatelli Marcello , Governatori Luciana , Carlucci Giuseppe , Genovese Salvatore , Mollica Adriano , Epifano Francesco 
Published: August 2011

ABSTRACTDrug development is a time‐consuming and costly process. It is usually divided into four phases, although it is not always possible to draw a sharp line between the various stages. In phase I and II there are many molecules investigate and it is necessary to analyze all of them in a short period of time, with lower costs, and with high‐throughput assay. During phase I relevant chemical–physical parameters like the acid dissociation constant, lipophilicity, solubility and stability must be analyzed. Classic techniques such as ‘shake‐flask’ can be used, but instrumental analytical methods such as HPLC may be helpful to improve and enhance the productivity and reproducibility of the results. During phase II the activity of a drug and factors that may have an influence on it, like metabolic profile and transformations, impurities and plasma biding proteins, must be considered. In this field, recent hyphenated analytical methods, such as LC‐MS/MS, GC‐MS/MS or more complex couplings, can provide more complete information. The aim of this review is to report the processes required for the validation of drug efficacy with reference to the description of ‘classic’ and modern techniques used. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis of indolizidines from optically pure α‐amino acids via stereocontrolled rhodium‐catalyzed hydroformylation of N‐allylpyrroles
Authors: Lazzaroni Raffaello , Settambolo Roberta 
Published: August 2011

AbstractIndolizidine alkaloids have attracted considerable attention because of their vast array of structural diversity and varied biological activity. This article relates the results that we obtained in the field of the total synthesis of indolizidines from α‐amino acids, based on the rhodium‐catalyzed hydroformylation of N‐allylpyrroles intermediates. The formed pyrrolylbutanals undergo an intramolecular cyclodehydration to 5,6‐dihydroindolizines, which are fully hydrogenated to indolizidines. All reaction sequences are stereocontrolled: indeed, the chiral center in the starting amino acid is transferred into 5,6‐dihydroindolizine moiety with complete stereochemical integrity and the new stereogenic center at C9 carbon atom in the final indolizidines is generated in only one configuration.Chirality, 2011. © 2011 Wiley‐Liss, Inc.
Adenosine A2A receptor in the monkey basal ganglia: Ultrastructural localization and colocalization with the metabotropic glutamate receptor 5 in the striatum
Authors: Bogenpohl James W. , Ritter Stefanie L. , Hall Randy A. , Smith Yoland 
Published: August 2011

AbstractThe adenosine A2A receptor (A2AR) is a potential drug target for the treatment of Parkinson's disease and other neurological disorders. In rodents, the therapeutic efficacy of A2AR modulation is improved by concomitant modulation of the metabotropic glutamate receptor 5 (mGluR5). To elucidate the anatomical substrate(s) through which these therapeutic benefits could be mediated, pre‐embedding electron microscopy immunohistochemistry was used to conduct a detailed, quantitative ultrastructural analysis of A2AR localization in the primate basal ganglia and to assess the degree of A2AR/mGluR5 colocalization in the striatum. A2AR immunoreactivity was found at the highest levels in the striatum and external globus pallidus (GPe). However, the monkey, but not the rat, substantia nigra pars reticulata (SNr) also harbored a significant level of neuropil A2AR immunoreactivity. At the electron microscopic level, striatal A2AR labeling was most commonly localized in postsynaptic elements (58% ± 3% of labeled elements), whereas, in the GPe and SNr, the labeling was mainly presynaptic (71% ± 5%) or glial (27% ± 6%). In both striatal and pallidal structures, putative inhibitory and excitatory terminals displayed A2AR immunoreactivity. Striatal A2AR/mGluR5 colocalization was commonly found; 60–70% of A2AR‐immunoreactive dendrites or spines in the monkey striatum coexpress mGluR5. These findings provide the first detailed account of the ultrastructural localization of A2AR in the primate basal ganglia and demonstrate that A2AR and mGluR5 are located to interact functionally in dendrites and spines of striatal neurons. Together, these data foster a deeper understanding of the substrates through which A2AR could regulate primate basal ganglia function and potentially mediate its therapeutic effects in parkinsonism. J. Comp. Neurol., 2012;520:570–589. © 2011 Wiley Periodicals, Inc.
Heterogeneity in dendritic morphology of moth antennal lobe projection neurons
Authors: Namiki Shigehiro , Kanzaki Ryohei 
Published: August 2011

AbstractA population of projection neurons (PNs) in the antennal lobe (AL) integrates sensory information from the antenna and is essential for processing odor information in the insect brain. We examined the anatomy of this neuronal population in the brain of the silkmoth Bombyx mori. Using intracellular dye injection, we labeled a total of 246 PNs and systematically analyzed their morphological features, including the soma position, antennocerebral tract, and number of innervating glomeruli. For example, we analyzed PNs that had somata in the different cell clusters, innervated overlapping but different groups of glomeruli, and ran through different pathways. We also identified glomeruli innervated by PNs using a previously established procedure that first classifies glomeruli into regional groups and then identifies individual glomeruli. We analyzed uniglomerular PNs (75.6% of the total) and found heterogeneity in the dendritic morphology of the PNs that was dependent on the regions and/or the innervating glomeruli. For example, most PNs innervating the macroglomerular complex did not have extraglomerular processes, whereas most PNs innervating ordinary glomeruli did. Moreover, PNs innervating the toroid glomerulus showed heterogeneity in their dendritic morphology. These PNs had dendritic arborization in different areas within the glomerulus. We found that, in some cases, the innervation pattern of the PN dendrite correlated with individual variation in the glomerular organization. These results indicate that PNs are not homogeneous populations, and in some cases morphological heterogeneity in PNs correlated with change in glomerular organization in the silkmoth AL. J. Comp. Neurol. 519:3367–3386, 2011. © 2011 Wiley‐Liss, Inc.
Sacral neural crest‐derived cells enter the aganglionic colon of Ednrb−/− mice along extrinsic nerve fibers
Authors: Erickson Christopher S. , Zaitoun Ismail , Haberman Kathryn M. , Gosain Ankush , Druckenbrod Noah R. , Epstein Miles L. 
Published: August 2011

AbstractBoth vagal and sacral neural crest cells contribute to the enteric nervous system in the hindgut. Because it is difficult to visualize sacral crest cells independently of vagal crest, the nature and extent of the sacral crest contribution to the enteric nervous system are not well established in rodents. To overcome this problem we generated mice in which only the fluorescent protein‐labeled sacral crest are present in the terminal colon. We found that sacral crest cells were associated with extrinsic nerve fibers. We investigated the source, time of appearance, and characteristics of the extrinsic nerve fibers found in the aganglionic colon. We observed that the pelvic ganglion neurons contributed a number of extrinsic fibers that travel within the hindgut between circular and longitudinal muscles and within the submucosa and serosa. Sacral crest‐derived cells along these fibers diminished in number from fetal to postnatal stages. A small number of sacral crest‐derived cells were found between the muscle layers and expressed the neuronal marker Hu. We conclude that sacral crest cells enter the hindgut by advancing on extrinsic fibers and, in aganglionic preparations, they form a small number of neurons at sites normally occupied by myenteric ganglia. We also examined the colons of ganglionated preparations and found sacral crest‐derived cells associated with both extrinsic nerve fibers and nascent ganglia. Extrinsic nerve fibers serve as a route of entry for both rodent and avian sacral crest into the hindgut. J. Comp. Neurol. 520:620–632, 2012. © 2011 Wiley Periodicals, Inc.
A methodology for real‐time self‐organized autonomous clustering in mobile ad hoc networks
Authors: Kakuda Yoshiaki , Ohta Tomoyuki , Oda Ryotaro 
Published: August 2011

SUMMARYIn order to realize hierarchical routings that should be executed in large‐scaled mobile ad hoc networks that vary their topologies considerably with time, we have developed autonomous clustering with high scalability and adaptability. In autonomous clustering, an entire network is divided into disjoint subnetworks (called clusters), and they are maintained by periodically sending messages within the clusters. This paper proposes real‐time self‐organizing autonomous clustering, in which interval and power for transmitting such messages are dynamically changed depending on variation of mobility and density of the clusters. Because their mobility and density can be estimated by local information obtained in the clusters, and according to their respective change the clusters are self‐organized in real‐time way, the proposed real‐time self‐organizing autonomous clustering can contribute to enhancement of its scalability and adaptability. Copyright © 2011 John Wiley & Sons, Ltd.
Context‐aware web search using dynamically weighted information fusion
Authors: Anderson Nicole 
Published: August 2011

SUMMARYWeb search has become a cornerstone tool for Internet users. The information one is able to retrieve quickly with commercial tools is awe inspiring, yet average users still remain frustrated with finding information that is truly relevant to them. In our research, we seek to show that if we utilize key pieces of information about a user and their current context, we can provide more accurate results. We do this by exploring context data, using query enhancement techniques, and appropriately fusing the results to provide the best ordering when presenting the results to the user. Context data includes a user's personal calendar, location, preferences, personal vocabulary, and peer recommendations. Query enhancement involves utilizing relevant contextual information to decorate a user's query text to produce a more focused query. Information fusion allows the query results to be compared and re‐ordered using contextual data by utilizing either a sum of products, a Bayesian technique, or a combination of the two. We find that by combining these methods, we are able to significantly enhance the search results. We have performed a case study and present the results here. Copyright © 2011 John Wiley & Sons, Ltd.
MR‐search: massively parallel heuristic search
Authors: Schütt Thorsten , Reinefeld Alexander , Maier Robert 
Published: August 2011

SUMMARYMR‐Search is a framework for massively parallel heuristic search. Based on the MapReduce paradigm, it efficiently utilizes all available resources: processors, memories, and disks. MR‐Search uses OpenMP on shared memory systems, Message Passing Interface on clusters with distributed memory, and a combination of both on clusters with multi‐core processors. Large graphs that do not fit into the main memory can be efficiently processed with an out‐of‐core variant. We implemented two node expansion strategies in MR‐Search: breadth‐first frontier search and breadth‐first iterative deepening A*. With breadth‐first frontier search, we computed large and powerful table‐driven heuristics, so‐called pattern databases that exceed the main memory capacity. These pattern databases were then used to solve random instances of the 24‐puzzle with breadth‐first iterative deepening A* on systems with up to 4093 processor cores. MR‐Search is conceptually simple. It takes care of data partitioning, process scheduling, out‐of‐core data merging, communication, and synchronization. Application developers benefit from the parallel computational capacity without having the burden of implementing parallel application code. Copyright © 2011 John Wiley & Sons, Ltd.
Hybrid Architectures from 3D Aligned Arrays of Multiwall Carbon Nanotubes and Nanoparticulate LiCoPO4: Synthesis, Properties and Evaluation of Their Electrochemical Performance as Cathode Materials in Lithium Ion Batteries
Authors: Schneider Jörg J. , Khanderi Jayaprakash , Popp Alexander , Engstler Jörg , Tempel Hermann , Sarapulova Angelina , Bramnik Natalia N. , Mikhailova Daria , Ehrenberg Helmut , Schmitt Ljubomira A. , Dimesso Lucangelo , Förster Christoph , Jaegermann Wolfram 
Published: August 2011

AbstractHybrid materials composed of LiMPO4 (M = Fe or Co) with multiwalled carbon nanotubes (MCNTs) were synthesized by tethering lithium phosphoolevins on isolated stochastically disordered MWCNTs as well as on ordered 3D MWCNT arrays via solution based impregnation routes. Ordered 3D arrays of MWCNT monoliths comprising MWCNTs with nominal tube diameters of 60 and 200 nm were synthesized by a catalyst free, template based method, with porous aluminum oxide (PAOX) acting as a template. Consecutive selectiveetching processes gave free standing aligned 3D carbon nanotube (CNT) architectures that were used as supporting cathode structures for electroactive LiCoPO4. LiCoPO4 nanoparticle suspensions derived from an ethanol based organic phosphate source turned out to be superior for the tethering of LiCoPO4 nanoparticles onto the 3D aligned CNT arrays compared to an aqueous based tethering route, thus giving hybrid materials with better electrochemical battery performance compared to materials generated by the latter method. Li ion extraction within the ordered 3D CNT/LiCoPO4 composites seems to be a two‐step process and the Li intercalation a one‐step process, highlighting the enhanced kinetics of the Li insertion process in the 3D CNT/LixCoPO4 composite in comparison to a particulate mixture of LixCoPO4 that is typically present in a conventional carbon/LiCoPO4 cathode composite system.
A Crystallographic and Mo K‐Edge XAS Study of Molybdenum Oxo Bis‐, Mono‐, and Non‐Dithiolene Complexes – First‐Sphere Coordination Geometry and Noninnocence of Ligands
Authors: Samuel Prinson P. , Horn Sebastian , Döring Alexander , Havelius Kajsa G. V. , Reschke Stefan , Leimkühler Silke , Haumann Michael , Schulzke Carola 
Published: August 2011

AbstractTen square‐based pyramidal molybdenum complexes with different sulfur donor ligands, that is, a variety of dithiolenes and sulfides, were prepared, which mimic coordination motifs of the molybdenum cofactors of molybdenum‐dependent oxidoreductases. The model compounds were investigated by Mo K‐edge X‐ray absorption spectroscopy (XAS) and (with one exception) their molecular structures were analyzed by X‐ray diffraction to derive detailed information on bond lengths and geometries of the first coordination shell of molybdenum. Only small variations in Mo=O and Mo–S bond lengths and their respective coordination angles were observed for all complexes including those containing Mo(CO)2 or Mo(μ‐S)2Mo motifs. XAS analysis (edge energy) revealed higher relative oxidation levels in the molybdenum ion in compounds with innocent sulfur‐based ligands relative to those in dithiolene complexes, which are known to exhibit noninnocence, that is, donation of substantial electron density from ligand to metal. In addition, longer average Mo–S and Mo=O bonds and consequently lower ν(Mo=O) stretching frequencies in the IR spectra were observed for complexes with dithiolene‐derived ligands. The results emphasize that the noninnocent character of the dithiolene ligand influences the electronic structure of the model compounds, but does not significantly affect their metal coordination geometry, which is largely determined by the Mo(IV) or (V) ion itself. The latter conclusion also holds for the molybdenum site geometries in the oxidized MoVI cofactor of DMSO reductase and the reduced MoIV cofactor of arsenite oxidase. The innocent behavior of the dithiolene molybdopterin ligands observed in the enzymes is likely to be related to cofactor–protein interactions.
A Family of Thiazolium Salt Derived N‐Heterocyclic Carbenes (NHCs) for Organocatalysis: Synthesis, Investigation and Application in Cross‐Benzoin Condensation
Authors: Piel Isabel , Pawelczyk Marius D. , Hirano Keiichi , Fröhlich Roland , Glorius Frank 
Published: August 2011

AbstractA family of thiazolium salt derived N‐heterocyclic carbenes (NHCs) bearing sterically demanding aryl substituents on the nitrogen and with varying backbone substitution patterns have been synthesized. Investigation of the catalytic activity of these NHCs in a number of benzoin‐type coupling reactions revealed markedly different levels of reactivity and selectivity. To elucidate the underlying factors leading to differences in reactivity, a study of the electronic and steric properties of these NHC catalysts was conducted. By using the best catalyst in this study, the intermolecular cross‐benzoin condensation reaction was explored in more detail.
A novel concept of dielectrophoretic engine oil filter
Authors: Shen Yueyang , Elele Ezinwa , Khusid Boris 
Published: August 2011

AbstractA novel concept of an alternating current (AC) dielectrophoretic filter with a three‐dimensional electrode array is presented. A filter is constructed by winding into layers around the core tube two sheets of woven metal wire‐mesh with several sheets of woven insulating wire‐mesh sandwiched in between. Contrary to conventional dielectrophoretic devices, the proposed design of electrodes generates a high‐gradient field over a large working volume by applying several hundred volts at a standard frequency of 60 Hz. The operating principle of filtration is based on our recently developed method of AC dielectrophoretic gating for microfluidics. The filtration efficiency is expressed in terms of two non‐dimensional parameters, which describe the combined influence of the particle polarizability and size, the oil viscosity and flow rate, and the field gradient on the particle captivity. The proof‐of‐concept is tested by measuring the single‐pass performance of two filters on positively polarized particles dispersed in engine oil: spherical glass beads, fused aluminum oxide powder, and silicon metal powder, all smaller than the mesh opening. The results obtained are used to consider the potential of using AC dielectrophoretic filtration and provide critical design guidelines for the development of a filter based on the retention capability of challenge particles.
Fluid streaming above interdigitated electrodes in dielectrophoresis experiments
Authors: Stanke Sandra , Bier Frank. F. , Hölzel Ralph 
Published: August 2011

AbstractFor the investigation of alternating current electrokinetic effects, a system is presented that allows for the simultaneous observation of fluid flow above and around microelectrodes in all three directions in space. Beside the usual microscopical view from top, lateral observation through the same objective is made possible by two small mirrors that are placed next to the electrodes. Fluid flow and movement of fluorescent nanoparticles above interdigitated electrodes are monitored by fluorescence microscopy and digital imaging and are further analysed by image processing. Field frequencies are varied from 10 Hz to 1 GHz at up to 10Vrms. Electrical conductivity of the fluid is monitored in situ in the actual measuring chamber.