bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation between Al3+‐induced thermal stability and inhibition of fibrillation of N‐terminal domain of the hydrogenase maturation factor
Authors: Sutariya Nimesh M. , Prasad Shivcharan , Athavale Dipti A. , Bhavsar Rupen D. , Roy Ipsita 
Published: July 2013

AbstractFibrillation can be induced in proteins by altering solvent conditions. Stabilization of the protofibrillar structure arrests formation of longer fibers. Thermal stability and fibrillation of N‐terminal domain of the hydrogenase maturation factor (HypF‐N) were studied in the presence of a series of metal ions. Only Al3+ was able to reverse the thermal denaturation of HypF‐N upon heating. On being exposed to denaturing conditions, the native protein formed fibrillar structure under moderately denaturing conditions, whereas in the presence of Al3+, the protein was found to retain its native conformation. Under strongly denaturing conditions, only Al3+ was able to stabilize the protein in the fibrillar state. Spectrofluorimetric analysis revealed that Al3+ alone was able to stabilize the partially unfolded intermediate state of HypF‐N. Based on the similarity in observations, we propose a link between reversal of thermal instability of HypF‐N and its ability to form an intermediate structure in the presence of Al3+. Al3+ stabilizes the partially unfolded state in the N↔I↔U equilibrium so that upon heating, the three‐dimensional structure of the protein is not lost completely. Kinetic analysis confirmed that Al3+ interacts with an early structure on the aggregation landscape and delays fibrillation. Under mildly denaturing state, HypF‐N is able to recover its native conformation in the presence of Al3+ and under strongly denaturing conditions, the protein does not acquire a completely disordered structure. Instead, it forms an ordered β‐sheet‐rich structure. © 2013 BioFactors, 39(6):597–607, 2013
Synthesis and conformational analysis of macrocyclic peptides consisting of both α‐helix and polyproline helix segments
Authors: Choi Sung-ju , Kwon Soo hyun , Kim Tae‐Hyun , Lim Yong-beom 
Published: July 2013

ABSTRACTMacrocycles are interesting molecules because their topological features and constrained properties significantly affect their chemical, physical, biological, and self‐assembling properties. In this report, we synthesized unique macrocyclic peptides composed of both an α‐helix and a polyproline segment and analyzed their conformational properties. We found that the molecular stiffness of the rod‐like polyproline segment and the relative orientation of the two different helical segments strongly affect the efficiency of the macrocyclization reaction. Conformational analyses showed that both the α‐helix and the polyproline II helix coexisted within the macrocyclic peptides and that the polyproline segment exerts significant effect on the overall helical stability and conformation of the α‐helical segment. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 279–286, 2014.
Mortality in high-risk emergency general surgical admissions
Authors: Symons N R A , Moorthy K , Almoudaris A M , Bottle A , Aylin P , Vincent C A , Faiz O D 
Published: July 2013

Abstract

Background
There is increasing evidence of variable standards of care for patients undergoing emergency general surgery in the National Health Service (NHS). The aim of this study was to quantify and explore variability in mortality amongst high-risk emergency general surgery admissions to English NHS hospital Trusts.

Methods
The Hospital Episode Statistics (HES) database was used to identify high-risk emergency general surgery diagnoses (greater than 5 per cent national 30-day mortality rate). Adults admitted to English NHS Trusts with these diagnoses between 2000 and 2009 were included in the study. Thirty-day in-hospital mortality was adjusted for patient and hospital factors. Trusts were grouped into high- and low-mortality outliers, and resource availability was compared between high- and low-mortality outlier institutions.

Results
Some 367 796 patients admitted to 145 hospital Trusts were included in the study; the 30-day mortality rate was 15·6 per cent (institutional range 9·2–18·2 per cent). Fourteen and 24 hospital Trusts were identified as high- and low-mortality outlier institutions respectively. Intensive care and high-dependency bed resources, as well as greater institutional use of computed tomography (CT), were independent predictors of reduced mortality (P &lt; 0·001). Low-mortality outlying Trusts had significantly more intensive care beds per 1000 hospital beds (20·8 versus 14·0; P = 0·017) and made significantly greater use of CT (24·6 versus 17·2 scans per bed per year; P &lt; 0·001) and ultrasonography (42·5 versus 30·2 scans per bed per year; P &lt; 0·001).

Conclusion
There is significant variability in mortality risk between hospital Trusts treating high-risk emergency general surgery patients. Equitable access to essential hospital resources may reduce variability in outcomes.
Protein purification by aminosquarylium cyanine dye‐affinity chromatography
Authors: Silva M. S. , Graça V. C. , Reis L. V. , Santos P. F. , Almeida P. , Queiroz J. A. , Sousa F. 
Published: July 2013

ABSTRACTThe most selective purification method for proteins and other biomolecules is affinity chromatography. This method is based on the unique biological‐based specificity of the biomolecule–ligand interaction and commonly uses biological ligands. However, these ligands may present some drawbacks, mainly because of their cost and lability. Dye‐affinity chromatography overcomes the limitations of biological ligands and is widely used owing to the low cost of synthetic dyes and to their resistance to biological and chemical degradation. In this work, immobilized aminosquarylium cyanine dyes are used in order to exploit affinity interactions with standard proteins such as lysozyme, α‐chymotrypsin and trypsin. These studies evaluate the affinity interactions occurring between the immobilized ligand and the different proteins, as a reflection of the sum of several molecular interactions, namely ionic, hydrophobic and van der Waals, spread throughout the structure, in a defined spatial manner. The results show the possibility of using an aminosquarylium cyanine dye bearing a N‐hexyl pendant chain, with a ligand density of 1.8 × 10−2 mmol of dye/g of chromatographic support, to isolate lysozyme, α‐chymotrypsin and trypsin from a mixture. The application of a decreasing ammonium sulfate gradient resulted in the recovery of lysozyme in the flowthrough. On the other hand, α‐chymotrypsin and trypsin were retained, involving different interactions with the ligand. In conclusion, this study demonstrates the potential applicability of ligands such as aminosquarylium cyanine dyes for the separation and purification of proteins by affinity chromatography. Copyright © 2013 John Wiley & Sons, Ltd.
Development of HPLC/fluorescence detection method for chiral resolution of dansylated benzimidazoles derivatives
Authors: Lipka Emmanuelle , Charton Julie , Vaccher Claude 
Published: July 2013

ABSTRACTThe development of high performance liquid chromatography method on amylose‐based stationary phase (Chiralpak AD) with n‐hexane–2‐propanol (90:10, v/v) as mobile phase allowed the enantioseparation of non‐dansylated and dansylated benzimidazole derivatives, prepared from potent‐AMPK activators, to be achieved. Using both fluorescence and ultraviolet detection, limits of detection and quantification were determined. Fluorescence detection seems to be the most appropriate technique since the first enantiomer of dansylated benzimidazole 8 eluted with a limit of quantification of 2.25 nm. The quantification limit was improved 10‐fold by fluorescence detection compared with a previous report describing mass spectrometry detection. Linearity and repeatability parameters were validated. These lower limits obtained by fluorescence detection, associated with good resolution observed for the dansylated derivatives, make this chiral methodology convenient for the use of these fluorescent potent‐AMPK activators as probes to elucidate their cellular localization and their mechanism of action. Copyright © 2013 John Wiley & Sons, Ltd.
Asymmetric facial expressions: revealing richer emotions for embodied conversational agents
Authors: Ahn Junghyun , Gobron Stephane , Thalmann Daniel , Boulic Ronan 
Published: July 2013

ABSTRACTIn this paper, we propose a method to achieve effective facial emotional expressivity for embodied conversational agents by considering two types of asymmetry when exploiting the valence–arousal–dominance representation of emotions. Indeed, the asymmetry of facial expressions helps to convey complex emotional feelings such as conflicting and/or hidden emotions due to social conventions. To achieve such a higher degree of facial expression in a generic way, we propose a new model for mapping the valence–arousal–dominance emotion model onto a set of 12 scalar facial part actions built mostly by combining pairs of antagonist action units from the Facial Action Coding System. The proposed linear model can automatically drive a large number of autonomous virtual humans or support the interactive design of complex facial expressions over time. By design, our approach produces symmetric facial expressions, as expected for most of the emotional spectrum. However, more complex ambivalent feelings can be produced when differing emotions are applied on the left and right sides of the face. We conducted an experiment on static images produced by our approach to compare the expressive power of symmetric and asymmetric facial expressions for a set of eight basic and complex emotions. Results confirm both the pertinence of our general mapping for expressing basic emotions and the significant improvement brought by asymmetry for expressing ambivalent feelings. Copyright © 2013 John Wiley & Sons, Ltd.
AA‐FVDM: An accident‐avoidance full velocity difference model for animating realistic street‐level traffic in rural scenes
Authors: Lu Xuequan , Chen Wenzhi , Xu Mingliang , Wang Zonghui , Deng Zhigang , Ye Yangdong 
Published: July 2013

ABSTRACTMost of existing traffic simulation efforts focus on urban regions with a coarse two‐dimensional representation; relatively few studies have been conducted to simulate realistic three‐dimensional traffic flows on a large, complex road web in rural scenes. In this paper, we present a novel agent‐based approach called accident‐avoidance full velocity difference model (abbreviated as AA‐FVDM) to simulate realistic street‐level rural traffics, on top of the existing FVDM. The main distinction between FVDM and AA‐FVDM is that FVDM cannot handle a critical real‐world traffic problem while AA‐FVDM settles this problem and retains the essence of FVDM. We also design a novel scheme to animate the lane‐changing maneuvering process (in particular, the execution course). Through numerous simulations, we demonstrate that besides addressing a previously unaddressed real‐world traffic problem, our AA‐FVDM method efficiently (in real time) simulates large‐scale traffic flows (tens of thousands of vehicles) with realistic, smooth effects. Furthermore, we validate our method using real‐world traffic data, and the validation results show that our method measurably outperforms state‐of‐the‐art traffic simulation methods.Copyright © 2013 John Wiley & Sons, Ltd.
The Effect of Substituents in PNPNH Ligands on Activity and Selectivity of a Chromium‐Based Catalyst System for Highly Selective Ethylene Trimerization
Authors: Heinig Stefan , Wöhl Anina , Müller Wolfgang , Al‐Hazmi Mohammed H. , Müller Bernd H. , Peulecke Normen , Rosenthal Uwe 
Published: July 2013

AbstractThe influence of ligand substituents on a highly selective homogeneous catalyst system for the trimerization of ethylene to 1‐hexene consisting of chromium(III) acetylacetonate, a ligand with a PNPNH backbone, tetraphenylphosphonium chloride as chlorine source, and triethyl aluminum as activator was investigated. These N‐modified and P‐modified ligands, which differ strongly in their electronic and steric properties of the substituents, were tested in the ethylene trimerization at three temperatures (50, 70, and 90 °C). Interestingly, the substituents at the N atoms of the PNPNH‐backbone had only little effect on the catalytic activity, on 1‐hexene selectivity, and on thermal stability of the catalyst system, whereas the substituents at the P atoms significantly influenced the efficiency of the system. This is even more surprising as the PNP ligand from SASOL for ethylene tetramerization is much more sensitive against substituent variation at its N atom.
A Rapid and Efficient Way to Dynamic Creation of Cross‐Reactive Sensor Arrays Based on Ionic Liquids
Authors: Zhu Wei , Li Weina , Yang Haowei , Jiang Yin , Wang Chen , Chen Yu , Li Guangtao 
Published: July 2013

AbstractBased on the simple counterion exchange of ionic liquids, a rapid, facile, and efficient strategy to create a cross‐reactive sensor array with a dynamic tunable feature was developed, and exemplified by the construction of a sensor array for the identification and classification of nitroaromatics and explosives mimics. To achieve a good sensing system with fast response, good sensitivity, and low detection limit, the synthesized ionic liquid receptors were tethered onto a silica matrix with a macro‐mesoporous hierarchical structure. Through the facile anion exchange approach, abundant ionic‐liquid‐based individual receptors with diversiform properties, such as different micro‐environments, diverse molecular interactions, and distinctive physico‐chemical properties, were easily and quickly synthesized to generate a distinct fingerprint of explosives for pattern recognition. The reversible anion exchange ability further endowed the sensor array with a dynamic tunable feature as well as good controllability and practicality for real‐world application. With the assistance of statistical analysis, such as principal component analysis (PCA) and linear discrimination analysis (LDA), an optimized‐size array with a good resolution was rationally established from a large number of IL‐based receptors. The performed experiments suggested that the ionic‐liquid‐based sensing protocol is a general and powerful strategy for creating a cross‐reactive sensor array that could find a wide range of applications for sensing various analytes or complex mixtures.
Can Conventional Bases and Unsaturated Hydrocarbons Be Converted into Gas‐Phase Superacids That Are Stronger than Most of the Known Oxyacids? The Role of Beryllium Bonds
Authors: Yáñez Manuel , Mó Otilia , Alkorta Ibon , Elguero José 
Published: July 2013

AbstractThe association of BeX2(X: H, F, Cl) derivatives with azoles leads to a dramatic increase of their intrinsic acidity. Hence, whereas 1H‐tetrazole can be considered as a typical N base in the gas phase, the complex 1H‐tetrazole–BeCl2is predicted to be, through the use of high‐level G4 ab initio calculations, a nitrogen acid stronger than perchloric acid. This acidity enhancement is due to a more favorable stabilization of the deprotonated species after the beryllium bond is formed, because the deprotonated anion is a much better electron donor than the neutral species. Consequently, this is a general phenomenon that should be observed for any Lewis base, including those in which the basic site is a hydroxy group, an amino group, a carbonyl group, an aromatic N atom, a second‐row atom, or the π system of unsaturated hydrocarbons. The consequence is that typical bases like aniline or formamide lead to BeX2complexes that are stronger acids than phosphoric or chloric acids. Similarly, water, methanol, and SH2become stronger acids than sulfuric acid, pyridine becomes a C acid almost as strong as acetic acid, and unsaturated hydrocarbons such as ethylene and acetylene become acids as strong as nitric and sulfuric acids, respectively.
Cobalt‐catalyzed Selective CF Bond Activation and Alkylation of Polyfluoroaryl Imines
Authors: Lu Faguan , Sun Hongjian , Li Xiaoyan 
Published: July 2013

AbstractIn this paper the CF bond activation of polyfluoroaryl imines is explored at cobalt(0) center with an imine‐N atom as an anchoring group. The reaction of F5C6‐CHN‐(2′‐ClC6H4) (2) and F5C6‐CHN‐C6H5 (3) with Co(PMe3)4 afforded the CF bond activation products (ortho‐F4C6‐CHN‐(2′‐ClC6H4))Co(I)(PMe3)3 (5) and (ortho‐F4C6‐CHN‐C6H5)Co(II)(F)(PMe3)2 (6), while only π‐(CN) coordinated cobalt(0) complex (2,4,5‐F3C6H2‐CHN‐(4′‐ClC6H4))Co(0)(PMe3)3 (4) was obtained from 2,4,5‐F3C6H2‐CHN‐(4′‐ClC6H4) (1) without CF bond activation. Complexes 4–6 were characterized through X‐ray single crystal diffraction. It was also found that dialkylation of N‐(perfluorobenzylidene)benzenamine with organozinc reagents could be catalyzed by Co(PMe3)4 via C,C‐coupling reaction under mild conditions.
Palladium‐Catalyzed Cross‐Coupling of Fluorinated Vinyl Chlorides with Terminal Alkynes: A General Protocol to Fluorinated Enynes
Authors: Chen Sheng , Xu Chunfa , Lu Long , Shen Qilong 
Published: July 2013

AbstractAn efficient and cost‐effective method for the preparation of fluorinated conjugated enynes was described. The method was compatible with a variety of functional groups such as chloride, amine, cyano and ester group. The method could also be extended to the coupling of (R,Z)‐3‐(2‐chloro‐1,2‐difluorovinyl)‐4‐alkyloxazolidin‐2‐one (3) with moderate yields.
L‐Lysine/imidazole‐catalyzed Multicomponent Cascade Reaction: Facile Synthesis of C5‐substituted 3‐Methylcyclohex‐2‐enones
Authors: Xiang Ziwei , Liu Zhiqiang , Liang Yiru , Wu Qi , Lin Xianfu 
Published: July 2013

AbstractA facile and simple route for the direct preparation of substituted 3‐methylcyclohex‐2‐enone via Aldol‐Robinson cascade reaction of aldehydes and acetones catalyzed by the new catalytic system of L‐lysine/imidazole in n‐heptane with 0.5% water was reported. A variety of substrates can participate in the process efficiently. The merits of this method included inexpensive and easily available starting materials and catalyst, the good yield of products and the straightforward work‐up.
Probing the S1′ Site for the Identification of Non‐Zinc‐Binding MMP‐2 Inhibitors
Authors: Di Pizio Antonella , Laghezza Antonio , Tortorella Paolo , Agamennone Mariangela 
Published: July 2013

AbstractMatrix metalloproteinases (MMPs) are zinc‐dependent enzymes involved in several pathological states. Among them, MMP‐2 is a relevant therapeutic target because of its role in cancer development and progression. Many MMP inhibitors (MMPIs) have been discovered over the last 30 years, and the majority of them contain a functional group that binds the zinc ion (zinc‐binding group; ZBG). Unfortunately, no MMPIs have reached the market yet, owing to toxic effects due to unselective interactions of the ZBG. The new generation of MMPIs that do not bind the zinc ion could overcome problems of selectivity and toxicity, but have so far been developed only for MMP‐8, ‐12, and ‐13. In this work, a virtual screening protocol was established by combining ligand‐ and structure‐based methods to identify non‐zinc‐binding MMP‐2 inhibitors using a new‐generation MMP‐8 inhibitor as a probe to find unexplored interactions in the MMP‐2 S1′ site. The screening allowed the identification of micromolar MMP‐2 inhibitors that putatively avoid binding the zinc ion, as demonstrated by docking calculations. The LIA model, built to correlate predicted and experimental binding energies of the identified non‐zinc‐binding MMP‐2 hits, underpins the reliability of the predicted docking poses.
Thiuram Disulfides as Pseudo‐irreversible Inhibitors of Lymphoid Tyrosine Phosphatase
Authors: Kulkarni Rhushikesh A. , Stanford Stephanie M. , Vellore Nadeem A. , Krishnamurthy Divya , Bliss Matthew R. , Baron Riccardo , Bottini Nunzio , Barrios Amy M. 
Published: July 2013

AbstractWe screened a small library of thiuram disulfides for inhibition of lymphoid tyrosine phosphatase (LYP) activity. The parent thiuram disulfide, disulfiram, inhibited LYP activity in vitro and in Jurkat T cells, whereas diethyldithiocarbamate failed to inhibit LYP at the concentrations tested. Compound 13, an N‐(2‐thioxothiazolidin‐4‐one) analogue, was found to be the most potent LYP inhibitor in this series, with an IC50 value of 3 μM. Compound 13 inhibits LYP pseudo‐irreversibly, as evidenced by the time‐dependence of inhibition, with a Ki value of 1.1 μM and a kinact value of 0.004 s−1. The inhibition of LYP by compound 13 could not be reversed significantly by incubation with glutathione or by prolonged dialysis, but could be partially reversed by incubation with dithiothreitol. Compound 13 also inhibited LYP activity in Jurkat T cells.
Collaborating across multiple health care institutions in an urban colorectal cancer screening program
Authors: Villanueva Robert , Gugel Donna , Dwyer Diane M. 
Published: July 2013

BACKGROUNDMaryland, excluding Baltimore City, began public health screening for colorectal cancer in 2000. Initiating colorectal cancer screening in Baltimore City was an objective in the Maryland Comprehensive Cancer Control Plan. The Centers for Disease Control and Prevention's (CDC's) funding announcement for the “Colorectal Cancer Screening Demonstration Program” (CRCSDP) was seen as a potential opportunity for Maryland to begin screening in Baltimore City.METHODSThe Maryland Department of Health and Mental Hygiene (DHMH), the American Cancer Society, and five Baltimore City Hospitals collaborated to develop the funding application and model for the Baltimore City CRCSDP. After receipt of funding, between 2005 and September 2009, screening sites collaborated with the DHMH to implement the multi‐site colorectal cancer screening program in Baltimore City.RESULTSClose collaboration across organizational boundaries enabled the funding, formation, and implementation of the CRCSDP in Baltimore City. The Baltimore City CRCSDP illustrates the complexity of establishing a functional public health screening program. The program overcame expected and unexpected fiscal, programmatic, and clinical challenges to successfully perform 709 colonoscopies screening cycles among 696 people and detect three cancers during the 38 months of screening.CONCLUSIONSPartnerships among the state and local health department, the American Cancer Society, and hospitals in Baltimore City enabled the implementation of this successful program. Lessons learned from the collaborative planning process and the program implementation may facilitate similar collaborations in other geographic areas. Cancer 2013;119(15 suppl):2905–13. © 2013 American Cancer Society.