bluuebunny/crossref_metadata_2025_split huggingface dataset:
Syntheses, Receptor Bindings, in vitro and in vivo Stabilities and Biodistributions of DOTA‐Neurotensin(8–13) Derivatives Containing β‐Amino Acid Residues – A Lesson about the Importance of Animal Experiments
Authors: Sparr Christof , Purkayastha Nirupam , Yoshinari Tomohiro , Seebach Dieter , Maschauer Simone , Prante Olaf , Hübner Harald , Gmeiner Peter , Kolesinska Beata , Cescato Renzo , Waser Beatrice , Reubi Jean Claude 
Published: December 2013

AbstractNeurotensin(8–13) (NTS(8–13)) analogs with C‐ and/or N‐terminal β‐amino acid residues and three DOTA derivatives thereof have been synthesized (i.e., 1–6). A virtual docking experiment showed almost perfect fit of one of the 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) derivatives, 6a, into a crystallographically identified receptor NTSR1 (Fig. 1). The affinities for the receptors of the NTS analogs and derivatives are low, when determined with cell‐membrane homogenates, while, with NTSR1‐exhibiting cancer tissues, affinities in the single‐digit nanomolar range can be observed (Table 2). Most of the β‐amino acid‐containing NTS(8–13) analogs (Table 1 and Fig. 2), including the 68Ga complexes of the DOTA‐substituted ones (6; Figs. 2 and 5), are stable for ca. 1 h in human serum and plasma, and in murine plasma. The biodistributions of two 68Ga complexes (of 6a and 6b) in HT29 tumor‐bearing nude mice, in the absence and in the presence of a blocking compound, after 10, 30, and 60 min (Figs. 3 and 4) lead to the conclusion that the amount of specifically bound radioligand is rather low. This was confirmed by PET‐imaging experiments with the tumor‐bearing mice (Fig. 6). Comparison of the in vitro plasma stability (after 1 h) with the ex vivo blood content (after 10–15 min) of the two 68Ga complexes shows that they are rapidly cleaved in the animals (Fig. 5).
Structural and Mutational Studies on the Unusual Substrate Specificity of meso‐Diaminopimelate Dehydrogenase from Symbiobacterium thermophilum
Authors: Liu Weidong , Li Zhe , Huang Chun‐Hsiang , Guo Rey‐Ting , Zhao Leiming , Zhang Dalong , Chen Xi , Wu Qiaqing , Zhu Dunming 
Published: December 2013

AbstractWild‐type meso‐diaminopimelate dehydrogenase (DAPDH) is usually specific to the native substrate, meso‐2,6‐diaminopimelate. Recently, a DAPDH from Symbiobacterium thermophilum (StDAPDH) was found to exhibit expanded substrate specificity. As such, its crystal structures in apo form and in complex with NADP+ and both NADPH and meso‐DAP were investigated to reveal the structural basis of its unique catalytic properties. Structural analysis results show that StDAPDH should prefer an ordered kinetic catalytic mechanism. A second substrate entrance tunnel with Met152 at its bottleneck was found, through which pyruvate/D‐alanine might bind and enter the catalytic cavity, providing some structural insights into its high activity toward pyruvate. The side chain of Met152 might interact with Asp92 and Asn253, thus affecting the domain motion and catalysis. These results offer useful information for understanding the unique catalytic properties of StDAPDH and guiding further engineering of this enzyme.
Percutaneous balloon dilation of severe pulmonary valve stenosis in patients with cyanosis and congestive heart failure
Authors: Tefera Endale , Qureshi Shakeel A. , Bermudez‐Cañete Ramón , Rubio Lola 
Published: December 2013

ObjectivesThis article reports outcomes of percutaneous balloon dilation in patients with severe pulmonary valve stenosis, in particular in those treated late with cyanosis, congestive heart failure, and pericardial effusion.BackgroundPercutaneous balloon dilation is the treatment of choice for pulmonary valve stenosis. Although earlier intervention may produce better results, patients may present late with congestive heart failure and cyanosis.MethodsFifty‐five patients who underwent pulmonary valve balloon dilation, were grouped into two groups, based on the presence or absence of congestive right heart failure and/or central cyanosis. Group I included 33 patients with severe pulmonary valve stenosis, but without clinical evidence of congestive right heart failure in the form of liver enlargement, raised jugular venous pressure, and peripheral edema and/or central cyanosis and group II included 22 patients with severe pulmonary valve stenosis and congestive right heart failure and/or central cyanosis. Their outcomes were compared.ResultsDoppler measured transvalvar pressure gradient decreased from 110.2 ± 34.0 mm Hg before to 52.5 ± 28.7 mm Hg in group I after dilation (P < 0.001), and from 138.4 ± 32.3 mm Hg to 53.9 ± 19.3 mm Hg in group II, (P < 0.001). Complications included ventricular tachycardia/fibrillation in three patients and severe bradycardia in one patient in group II. Twelve patients in group II developed clinical and radiologic evidence of reperfusion injury/pulmonary edema within the first 24 hr of intervention and needed ventilation for 2–9 days. Three of these patients died from intractable pulmonary edema. On follow up, clinical and echocardiographic improvement parameters were similar in the two groups.ConclusionThose patients with severe pulmonary valve stenosis with congestive right heart failure, especially those with pericardial effusion, ascites and cyanosis, represent an important technical and clinical challenge. They are a high‐risk group with or without treatment. If they survive the procedure, they may still remain at a high risk in the first few days afterward. Maintaining their ventilator and inotropic support after balloon dilation may increase survival. However, excellent results can be obtained. © 2013 Wiley Periodicals, Inc.
Safety of percutaneous left atrial appendage closure with the amplatzer cardiac plug in patients with atrial fibrillation and contraindications to anticoagulation
Authors: Wiebe Jens , Bertog Stefan , Franke Jennifer , Wettstein Olga , Lehn Katharina , Hofmann Ilona , Vaskelyte Laura , Sievert Horst 
Published: December 2013

ObjectiveTo evaluate the safety of percutaneous left atrial appendage (LAA) closure with the Amplatzer Cardiac Plug (ACP) in patients with nonvalvular atrial fibrillation (AF) who are not eligible for oral anticoagulation with warfarin.BackgroundAnticoagulation is the treatment of choice for prevention of strokes in patients with AF, but some patients have contraindications to anticoagulation.MethodsA total of 60 patients with a CHA2DS2‐VASc score of at least 1 and contraindications to warfarin who underwent percutaneous LAA closure with the ACP were included. Stroke risk assessment was performed with the CHADS2 and CHA2DS2‐VASc score and the bleeding risk was calculated with the HAS‐BLED‐score. Follow‐up included office visits, telephone inquiries, and mail contact.ResultsMean CHADS2‐, CHA2DS2‐VASc‐, and HAS‐BLED scores were 2.6 (± 1.4), 4.3 (± 1.7), and 3.3 (± 1.0), respectively. Twenty‐five percent had a history of previous bleeding without oral anticoagulation and 63.3% while receiving oral anticoagulation. In 36.7% other contraindications to warfarin were present. Procedural success was achieved in 95%. Mean follow‐up time was 1.8 (1.0–2.8) years. The estimated annual stroke risk based on the CHADS2‐score was 5.8%. The estimated annual bleeding risk on warfarin based on the HAS‐BLED score was 3.7%. During follow‐up, the annual incidence of stroke was 0%. Major bleeding complications occurred in 1.9% annually.ConclusionsPercutaneous LAA closure with the ACP in patients with contraindications to oral anticoagulation is safe. The stroke and bleeding risk after percutaneous LAA closure is lower than predicted by conventional risk scores. © 2013 Wiley Periodicals, Inc.
Stepwise Solid‐Phase Synthesis and Solid‐State Electrochemistry of Redox‐Active Viologen Core/Shell‐Structured Modified Silica Materials
Authors: Passon Monika , Ruff Adrian , Schuler Paul , Speiser Bernd , Dreiling Ines 
Published: December 2013

AbstractCore/shell‐structured viologen‐modified Stöber silica particles with diameters of approximately 235 nm are prepared in a stepwise, solid‐phase synthesis. The nonporous and spherical silica base particles are obtained through a sol–gel process from tetraethoxysilane followed by a post‐synthetic calcination step and characterized by means of scanning electron microscopy, nitrogen adsorption/desorption experiments, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, Gay‐Lussac pycnometry in water, and dynamic light scattering. Coating with triethoxysilane yields SiH‐terminated particles, which are further reacted with the linker, 11‐bromo‐1‐undecene, in a thermally induced hydrosilylation. The resulting kinetically inert and thermodynamically stable SiC bond ensures strong attachment to the silica surface. The viologen units are generated by alkylation with 1‐methyl[4,4′]bipyridinium iodide directly on the particle surface. The successful attachment is confirmed by diffuse reflectance UV/Vis, DRIFT, and 13C cross‐polarization/magic‐angle spinning nuclear magnetic resonance spectroscopy. The viologen shell of the particles is electrochemically addressable. In cyclic voltammetry experiments, under three‐phase junction conditions with modified gold and paraffin‐impregnated graphite electrodes, the immobilized viologen units are reduced to the neutral state in two consecutive electron‐transfer reactions via a mono radical cation species. The in situ electrolysis of suspended particles leads to a material with a diamagnetic core (silica) and a paramagnetic shell (viologen mono radical cations). Electron paramagnetic resonance experiments demonstrate that the radical cations are strongly attached to the particle surface. The material and electrochemical properties of the particles are compared to amorphous silica and to a viologen‐modified Stöber material based on a well‐established immobilization strategy (condensation of alkoxysilane to surface silanol groups).
Transalkylation of Higher Trifluoromethylated Fullerenes with C70: A Pathway to New Addition Patterns of C70(CF3)8
Authors: Belov Nikita M. , Apenova Marina G. , Rybalchenko Alexey V. , Borkovskaya Eugenia V. , Lukonina Natalia S. , Goryunkov Alexey A. , Ioffe Ilya N. , Troyanov Sergey I. , Sidorov Lev N. 
Published: December 2013

AbstractWe report three new isomers of C70(CF3)8, structurally related to p7mp‐C70(CF3)10, that are inaccessible by direct trifluoromethylation, but can be easily identified among the products of the transalkylation of higher trifluoromethylfullerenes with C70. The reported compounds are characterized by UV/Vis, 1 D and 2 D COSY 19F NMR spectroscopy, and DFT calculations. A rather unusual addition pattern is observed in p6,i‐C70(CF3)8 in which one addend is attached remotely from the others; polarization of the adjacent unsaturated bonds by the addend makes the molecule readily oxidizable.
Self‐Assembly of a Highly Organized, Hexameric Supramolecular Architecture: Formation, Structure and Properties
Authors: Schaeffer Gaël , Fuhr Olaf , Fenske Dieter , Lehn Jean‐Marie 
Published: December 2013

AbstractTwo derivatives, 3L and 9L, of a ditopic, multiply hydrogen‐bonding molecule, known for more than a decade, have been found, in the solid state as well as in solvents of low polarity at room temperature, to exist not as monomers, but to undergo a remarkable self‐assembly into a complex supramolecular species. The solid‐state molecular structure of 3L, determined by single‐crystal X‐ray crystallography, revealed that it forms a highly organized hexameric entity 3L6 with a capsular shape, resulting from the interlocking of two sets of three monomolecular components, linked through hydrogen‐bonding interactions. The complicated 1H NMR spectra observed in o‐dichlorobenzene (o‐DCB) for 3L and 9L are consistent with the presence of a hexamer of D3 symmetry in both cases. DOSY measurements confirm the hexameric constitution in solution. In contrast, in a hydrogen‐bond‐disrupting solvent, such as DMSO, the 1H NMR spectra are very simple and consistent with the presence of isolated monomers only. Extensive temperature‐dependent 1H NMR studies in o‐DCB showed that the L6 species dissociated progressively into the monomeric unit on increasing th temperature, up to complete dissociation at about 90 °C. The coexistence of the hexamer and the monomer indicated that exchange was slow on the NMR timescale. Remarkably, no species other than hexamer and monomer were detected in the equilibrating mixtures. The relative amounts of each entity showed a reversible sigmoidal variation with temperature, indicating that the assembly proceeded with positive cooperativity. A full thermodynamic analysis has been applied to the data.
Gold Nanocage Assemblies for Selective Second Harmonic Generation Imaging of Cancer Cell
Authors: Demeritte Teresa , Fan Zhen , Sinha Sudarson Sekhar , Duan Jinsong , Pachter Ruth , Ray Paresh C. 
Published: December 2013

AbstractSecond harmonic generation (SHG) imaging using near infrared laser light is the key to improving penetration depths, leading to biological understanding. Unfortunately, currently SHG imaging techniques have limited capability due to the poor signal‐to‐noise ratio, resulting from the low SHG efficiency of available dyes. Targeted tumor imaging over nontargeted tissues is also a challenge that needs to be overcome. Driven by this need, in this study, the development of two‐photon SHG imaging of live cancer cell lines selectively by enhancement of the nonlinear optical response of gold nanocage assemblies is reported. Experimental results show that two‐photon scattering intensity can be increased by few orders of magnitude by just developing nanoparticle self‐assembly. Theoretical modeling indicates that the field enhancement values for the nanocage assemblies can explain, in part, the enhanced nonlinear optical properties. Our experimental data also show that A9 RNA aptamer conjugated gold nanocage assemblies can be used for targeted SHG imaging of the LNCaP prostate cancer cell line. Experimental results with the HaCaT normal skin cell lines show that bioconjugated nanocage‐based assemblies demonstrate SHG imaging that is highly selective and will be able to distinguish targeted cancer cell lines from other nontargeted cell types. After optimization, this reported SHG imaging assay could have considerable application for biology.
Antimicrobial Activity of Water‐Soluble Triazole Phenazine Clickamers against E. coli
Authors: Hayden Steven C. , Bryant Jonathan J. , Mackey Megan A. , Höfer Katharina , Lindner Benjamin D. , Nguyen Vanessa P. , Jäschke Andres , Bunz Uwe H. F. 
Published: December 2013

AbstractThe antimicrobial potency of phenazine derivatives is attenuated by their inherently hydrophobic nature, complicating their use as antibiotic drugs. We have analyzed the cytotoxicity and mode of action of water‐soluble bis‐triazolyl phenazines against E. coli and a human epithelial (HaCat) cell line. We observed complete inhibition of bacterial growth over concentration ranges that do not affect the viability of human epithelial cells. Confocal fluorescence microscopy revealed a high degree of interaction between the phenazine compounds and E. coli, as well as evidence of membrane damage in phenazine‐treated E. coli. Additional data suggests that the potency of these particular water‐soluble phenazine compounds does not result from the production of reactive oxygen species, but rather from cytotoxic interference with metabolic electron‐transfer cascades.
Composite PET Membrane with Nanostructured Ag/AgTCNQ Schottky Junctions: Electrochemical Nanofabrication and Charge‐Transfer Properties
Authors: Huang Li , Chen Yong , Bian Shujuan , Huang Yi‐Fan , Tian Zhong‐Qun , Zhan Dongping 
Published: December 2013

AbstractLarge‐area nanostructured Ag/Ag‐tetracyanoquinodimethane (TCNQ) Schottky junctions are fabricated electrochemically on a mesoporous polyethylene terephthalate (PET) membrane‐supported water/1, 2‐dichloroethane (DCE) interface. When the interface is polarized, Ag+ ions transfer across the PET membrane from the aqueous phase and are reduced to form metallic Ag on the PET membrane, which reacts further with tetracyanoquinodimethane (TCNQ) in the DCE phase to form nanostructured Ag/AgTCNQ Schottky junctions. Once the mesoporous membrane is blocked by metallic Ag, a bipolar mechanism is proposed to explain the successive growth of AgTCNQ nanorods and Ag film on each side of the PET membrane. Due to the well‐formed nanostructure of Ag/AgTCNQ Schottky junctions, the direct electrochemical behavior is observed, which is essential to explain the physicochemical mechanism of its electric performance. Moreover, the composite PET membrane with nanostructured Ag/AgTCNQ Schottky junctions is tailorable and can be assembled directly into electric devices without any pretreatment.
Enantioselective Aziridination of Cyclic Enals Facilitated by the Fluorine‐Iminium Ion Gauche Effect
Authors: Molnár István Gábor , Tanzer Eva‐Maria , Daniliuc Constantin , Gilmour Ryan 
Published: December 2013

AbstractThe enantioselective, organocatalytic aziridination of small, medium and macro‐cyclic enals is reported using (S)‐2‐(fluorodiphenyl methyl)‐pyrrolidine. Central to the reaction design is the reversible formation of a β‐fluoroiminium ion intermediate, which is pre‐organised on account of the fluorine‐iminium ion gauche effect. This conformational effect positions the fluorine substituent synclinal‐endo to the electropositive nitrogen centre thus benefiting from favourable stereoelectronic and electrostatic interactions (σC−H→σC−F*; Fδ−…︁N+). Consequently, one of the shielding groups on the fluorine‐bearing carbon atom is positioned above the π‐system, forming the basis of an enantioinduction strategy. Treatment of this intermediate with a “nitrene” source furnished a series of novel, optically active aziridines (e.r. up to 99.5:0.5). Further derivatisation of the product aziridines gives facile access to various amino acid derivatives, including β‐fluoroamino acids. Crystallographic analyses of both the aziridines and their derivatives are disclosed.
Fluorescent Probes Based on Nucleophilic Substitution–Cyclization for Hydrogen Sulfide Detection and Bioimaging
Authors: Peng Bo , Chen Wei , Liu Chunrong , Rosser Ethan W. , Pacheco Armando , Zhao Yu , Aguilar Hector C. , Xian Ming 
Published: December 2013

AbstractThe design, synthesis, properties, and cell imaging applications of a series of 2‐pyridyl disulfide based fluorescent probes (WSP1, WSP2, WSP3, WSP4 and WSP5) for hydrogen sulfide detection are reported. The strategy is based on the dual‐nucleophilicity of hydrogen sulfide. A hydrogen sulfide mediated tandem nucleophilic substitution‐cyclization reaction is used to release the fluorophores and turn on the fluorescence. The probes showed high sensitivity and selectivity for hydrogen sulfide over other reactive sulfur species, including cysteine and glutathione.
Achieving a Rare Breathing Behavior in a Polycatenated 2 D to 3 D Net through a Pillar‐Ligand Extension Strategy
Authors: Zhao Xiaoliang , Liu Fuling , Zhang Liangliang , Sun Di , Wang Rongming , Ju Zhangfeng , Yuan Daqiang , Sun Daofeng 
Published: December 2013

AbstractThrough a pillar‐ligand extension strategy, a rare breathing behavior in polycatenated 2D→3D nets has been achieved. Three variants exhibit interesting sorption properties that range from non‐breathing to breathing behaviors, which is influenced by the angles between the pillars and the single honeycomb layers. The increase in pillar length does not lead to an increase in polycatenation multiplicity, which is controlled by the length of intralayer tripodal carboxylate. It also does not induce obviously expanded interlayer separations but occupies much more the free voids, and as a consequence, a smaller pore volume is obtained. This suggests that in 2D→3D polycatenated bilayer metal–organic frameworks, the porosity is not always enhanced by increasing the length of the interlayer pillars with the intralayer linker remaining unchanged.
Studies on Enantioselective Liquid–Liquid Extraction of Amino‐(4‐nitro‐phenyl)‐acetic Acid Enantiomers: Modeling and Optimization
Authors: Zhang Panliang , Liu Chang , Tang Kewen , Liu Jiajia , Zhou Congshan , Yang Changan 
Published: December 2013

ABSTRACTBINAP‐metal complexes were prepared as extractant for enantioselective liquid–liquid extraction (ELLE) of amino‐(4‐nitro‐phenyl)‐acetic acid (NPA) enantiomers. The influence of process variables, including types of organic solvents and metal precursor, concentration of ligand, pH, and temperature on the efficiency of the extraction, were investigated experimentally. An interfacial reaction model was established for insightful understanding of the chiral extraction process. Important parameters required for the model were determined. The experimental data were compared with model predictions to verify the model prediction, It was found that the interfacial reaction model predicted the experimental results accurately. By modeling and experiment, an optimal extraction condition with pH of 7 and host (extractant) concentration of 1 mmol/L was obtained and high enantioselectivity (αop) of 3.86 and performance factor (pf) of 0.1949 were achieved. Chirality 26:79–87, 2014. © 2013 Wiley Periodicals, Inc.
Diastereoselective Synthesis of Functionalized Tetrahydropyrimidin‐2‐thiones via ZnCl2 Promoted One‐pot Reactions
Authors: Liu Zhenming , Zhang Lili , Sun Jing , Yan Chaoguo 
Published: December 2013

AbstractIn the presence of zinc chloride, the in situ generated β‐enamino ester from the reaction of morpholine, piperidine and pyrrolidine with methyl propiolate reacted, with aromatic aldehydes and thiourea in ethanol resulting in the functionalized tetrahydropyrimidin‐2‐thiones in satisfactory yields and with good diastereoselectivity. When aromatic aldehydes bearing electron‐withdrawing group were used in the reaction, the 4‐hydroxytetrahydropyrimidin‐2‐thione derivatives were obtained as the main product.
A Photo‐responsive Catalytic Vesicle with GPx Activity
Authors: Xiao Ruiqing , Zhou Lipeng , Dong Zeyuan , Gao Yuzhou , Liu Junqiu 
Published: December 2013

AbstractGlutathione peroxidase (GPx) is a vital antioxidant enzyme involved in the reduction of reactive oxygen species and protects cells from oxidative damage. Consequently enormous efforts have been devoted to developing artificial catalysts with GPx function. Besides the research on enhancing the catalytic activity of GPx mimics, the design and construction of smart GPx models has also inspired great interest. Herein, a novel photo‐responsive selenium‐containing vesicular GPx model was successfully constructed by supramolecular self‐assembly of the cationic surfactant PyC10AzoC10Py with benzeneseleninic acid (PhSeO2H) through hydrophobic and electrostatic interactions in aqueous media. This selenium‐containing vesicular catalyst showed remarkable GPx‐like activity, which is 692 times more effective than PhSeO2H for the reduction of cumene hydroperoxide (CUOOH) by 4‐nitrobenzenethiol (NBT). Interestingly, when an equimolar amount of α‐CD was added, the GPx‐like activity of the catalytic vesicle declines remarkably due to the vesicle disaggregation in the presence of α‐CD. Whereas the biomimetic system was irradiated by UV light at 365 nm, the catalytic vesicle was formed again and the GPx‐like activity recovered.
Deposition of SnO2 on the Anatase TiO2 {105} Facets with High Photocatalytic Performance
Authors: Jiang Haibo , Xing Jun , Wang Chongwu , Yang Huagui 
Published: December 2013

AbstractAnatase TiO2 as a promising photocatalyst has been widely employed in the decontamination treatment of polluted water, air purification and water splitting. Coupling TiO2 with other semiconductor materials could further enhance the photocatalytic activity. Here, we successfully synthesized the SnO2/TiO2 catalyst by depositing SnO2 particles on the anatase TiO2 {105} facets through a gas phase oxidation process. The SnO2/TiO2 catalyst shows higher photocatalytic activity for decomposition of MB than that of the pure TiO2 catalyst. The enhanced photocatalytic activity can be attributed to the efficient charge separation since TiO2 and SnO2 catalyst have staggered energy level.