bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct activation of mTOR in B lymphocytes confers impairment in B‐cell maturation andloss of marginal zone B cells
Authors: Benhamron Sandrine , Tirosh Boaz 
Published: June 2011

AbstractThe tuberous sclerosis complex (TSC), composed of TSC1/TSC2 heterodimers, is inhibitory to the mammalian target of rapamycin (mTOR). Deletion of either TSC1 or TSC2 renders mTOR constitutively active. To directly explore the impact of mTOR activation on B‐cell development, we conditionally deleted TSC1 in murine B cells. This led to impairment in B‐cell maturation. Unexpectedly, and in contrast to Akt activation, marginal zone (MZ) B cells were significantly reduced. Administration of rapamycin partially corrected the MZ defect, indicating a direct role for mTOR in controlling MZ development. When challenged with a T‐cell‐dependent antigen, TSC1 KO mice responded less efficiently. Consistent with the MZ defects, TSC1 KO mice did not respond at all to T‐independent antigens. Because activation of Akt upstream of TSC and mTOR yields the reverse phenotype with respect to MZ development, we conclude that, physiologically, Akt simultaneously emits two opposing signals that counterbalance each other in the control of B‐cell differentiation.
Binuclear Carbonylheptalenechromium Complexes: Partition of Heptalene into a Complexed Heptafulvene Subunit and an Uncomplexed 1,3‐Diene Subunit for Coordination to a Multiply Bonded Pair of Chromium Atoms
Authors: Li Huidong , Feng Hao , Sun Weiguo , Fan Qunchao , Xie Yaoming , King R. Bruce 
Published: June 2011

AbstractThe possibility of extending carbonylchromium chemistry of the bicyclic non‐benzenoid aromatic hydrocarbon heptalene from the known mononuclear (η6‐C12H10)Cr(CO)3 to binuclear derivatives of the type C12H10Cr2(CO)n (n = 6, 5, 4, 3) is examined by density functional theory. The lowest energy C12H10Cr2(CO)6 structures have each heptalene ring bonded to an independent Cr(CO)3 unit as a hexahapto or heptahapto ligand with Cr···Cr distances too long (4.4 to 6.0 Å) for direct bonding. The lowest energy C12H10Cr2(CO)5 structure has an eight‐carbon heptafulvene subunit of the heptalene unit coordinated to a carbonyl‐bridged Cr2(CO)4(μ‐CO) unit as an octahapto ligand leaving an uncomplexed cis‐1,3‐diene subunit in the heptalene ligand. The short Cr≡Cr distance in this structure of ca. 2.36 Å suggests the formal triple bond required to give each chromium atom the favored 18‐electron configuration. A slightly higher energy C12H10Cr2(CO)5 structure by ca. 3 kcal/mol has all 12 heptalene carbon atoms bonded to an unbridged Cr2(CO)5 with a Cr–Cr distance of ca. 3.3 Å corresponding to the formal single bond required to give each chromium atom the favored 18‐electron configuration. The global minima for the more highly unsaturated C12H10Cr2(CO)n (n = 4, 3) complexes are predicted to have a four‐electron donor bridging η2‐μ‐CO group as indicated by short Cr–O distances consistent with a direct bond and a low ν(CO) frequency consistent with a low formal C–O formal bond order.
Syntheses, Structures, and Properties of Trinuclear Copper(I)/Titanium(IV) Thiolate Complexes
Authors: Andrushko Vasyl , Sommer Heino , Himmel Daniel , Fenske Dieter , Eichhöfer Andreas 
Published: June 2011

AbstractThe thiolato‐bridged copper(I)/titanium(IV) complexes [Li(15‐crown‐5)thf]2[Cu2Ti(SPh)8] (thf = tetrahydrofuran) and [Cu2Ti(SPh)6(PPh3)2] have both been prepared in yields of at least 83 % by reaction of CuCl and TiCl4·2thf with LiSPh in THF in the presence of 15‐crown‐5 or PPh3, respectively. The crystal structures of the trinuclear compounds were determined by X‐ray analysis of single crystals. The dark colored compounds display absorption bands over a wide energy range with absorption onsets lying in the near infrared region at approximately 1350 nm for [Li(15‐crown‐5)thf]2[Cu2Ti(SPh)8] and 1050 nm for [Cu2Ti(SPh)6(PPh3)2]. Density functional calculations reproduce and explain the energy difference of the lowest energy transitions. Thermal treatment of [Cu2Ti(SPh)6(PPh3)2] up to 500 °C resulted in the cleavage of SPh2 and PPh3 and the formation of a mixture of ternary copper titanium sulfides, namely Cu4TiS4 and the defect thiospinel Cu0.33TiS2. In contrast, reflections of the powder diffraction patterns of the residues from the thermal analysis of [Li(15‐crown‐5)thf]2[Cu2Ti(SPh)8] could only be assigned to the known phases Cu1.8S (Digenite) and Cu1.96S (Djurleit).
Proton Conductivity versus Acidic Strength of One‐Pot Synthesized Acid‐Functionalized SBA‐15 Mesoporous Silica
Authors: Bibent Nicolas , Mehdi Ahmad , Silly Gilles , Henn François , Devautour‐Vinot Sabine 
Published: June 2011

AbstractThis paper reports on the one‐pot synthesis and characterization of the functionalized mesoporous SBA‐15 silica, which contains two loadings of the different acid groups [CO2H, PO(OH)2 and SO3H]. The thermodynamic features of the water that was confined in these porous silicas was investigated by Differential Scanning Calorimetry (DSC). The results showed that the melting behaviour of the confined water was mainly governed by the pore diameter and, as a consequence, indicated that the chemical “decoration” of the porous surface did not play a key role in the water thermodynamics. On the contrary, the proton conductivity of the hydrated mesoporous materials, which was examined under a wide range of temperatures (–100 to 70 °C), was strongly dependent on both the physical state of the confined water and the acidity of the functional groups that were located at the porous surface. The proton conductivity was shown to be directly related to the pKa and the density of the functional groups attached to the mesopore surface. The high conductivity values that were obtained at a low temperature when the confined water is frozen, led us to postulate that the SO3H‐functionalized SBA‐15 sample could be a promising candidate for electrolyte solid applications in fuel cells.
Phenyl–Acetylene Bond Assembly: A Powerful Tool for the Construction of Nanoscale Architectures
Authors: Jenny Nicolas M. , Mayor Marcel , Eaton Thomas R. 
Published: June 2011

AbstractThis microreview summarises fundamental strategies and basic considerations for the design and synthesis of nanoscale architectures assembled through the formation of acetylene‐phenyl bonds. Since its first appearance in 1975 the Sonogashira–Hagihara reaction has allowed the formation of bonds between sp1 and sp2 carbon centres under mild conditions. This palladium‐catalysed cross‐coupling quickly found application in almost every area of synthetic organic chemistry. The biggest impact of this new method was probably observed in nanoscale architectures, giving rise to the new field of “acetylene scaffolding”. Here we present a summary of the underlying concepts and important strategies for the formation of acetylene‐phenyl bonds geared towards the assembly of nanoscale architectures illustrated with a few beautiful examples from the literature. It is not meant to be a comprehensive overview of the Sonogashira cross‐coupling reaction nor of the area of acetylene scaffolding but should serve as guide to the those new to the field. Starting with a short discussion of the reaction mechanism, appropriate choice of precursors is discussed. Introduction of chemoselectivity through the use of various leaving groups or by masking of their reactivity follows. The most common acetylene protection groups are summarised and compared in terms of their functional group tolerances and strategic concepts including orthogonality, sequential deprotection and in situ deprotection. Strategies for quick access to highly functionalised building blocks such as chemoselective halogenations and symmetry breaking are considered. Finally, the potential of the strategies discussed is documented with a few examples from the current literature.
Rapid and Efficient Radiosyntheses of meta‐Substituted [18F]Fluoroarenes from [18F]Fluoride Ion and Diaryliodonium ­Tosylates within a Microreactor
Authors: Chun Joong‐Hyun , Lu Shuiyu , Pike Victor W. 
Published: June 2011

AbstractEffective methods for the introduction of the short‐lived positron‐emitter fluorine‐18 (t1/2 = 109.7 min) at high specific radioactivity into fluoroarenes are valuable for the development of radiotracers for molecular imaging with positron emission tomography. We have explored the scope of the radiofluorination of diaryliodonium salts with no‐carrier‐added (NCA) [18F]fluoride ion for the preparation of otherwise difficult to access meta‐substituted [18F]fluoroarenes. A microfluidic reaction platform was used to establish optimal radiochemical yields. Rapid, high yielding and selective radiofluorinations were achieved in unsymmetrical diaryliodonium tosylates (ArI+Ar′TsO–), in which Ar carried either a meta electron‐withdrawing (CN, NO2, CF3) or electron‐donating (Me or MeO) group, and in which the partner aryl group (Ar′) was relatively electron‐rich, such as Ph, 3‐MeC6H4, 4‐MeOC6H4, 2‐thienyl, or 5‐Me‐2‐thienyl. The radiofluorination of appropriate diaryliodonium tosylates is therefore a generally useful method for the preparation of simple [18F]m‐fluoroarenes ([18F]ArF).
Voltammetric Determination of 4‐Nitrophenol and 5‐Nitrobenzimidazole Using Different Types of Silver Solid Amalgam Electrodes – A Comparative Study
Authors: Deýlová Dana , Yosypchuk Bogdan , Vyskočil Vlastimil , Barek Jiří 
Published: June 2011

AbstractThe voltammetric behavior of two genotoxic nitro compounds (4‐nitrophenol and 5‐nitrobenzimidazole) has been investigated using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) at a polished silver solid amalgam electrode (p‐AgSAE), a mercury meniscus modified silver solid amalgam electrode (m‐AgSAE), and a mercury film modified silver solid amalgam electrode (MF‐AgSAE). The optimum conditions have been evaluated for their determination in Britton‐Robinson buffer solutions. The limit of quantification (LQ) for 5‐nitrobenzimidazole at p‐AgSAE was 0.77 µmol L−1 (DCV) and 0.47 µmol L−1 (DPV), at m‐AgSAE it was 0.32 µmol L−1 (DCV) and 0.16 µmol L−1 (DPV), and at MF‐AgSAE it was 0.97 µmol L−1 (DCV) and 0.70 µmol L−1 (DPV). For 4‐nitrophenol at p‐AgSAE, LQ was 0.37 µmol L−1 (DCV) and 0.32 µmol L−1 (DPV), at m‐AgSAE it was 0.14 µmol L−1 (DCV) and 0.1 µmol L−1 (DPV), and at MF‐AgSAE, it was 0.87 µmol L−1 (DCV) and 0.37 µmol L−1 (DPV). Thorough comparative studies have shown that m‐AgSAE is the best sensor for voltammetric determination of the two model genotoxic compounds because it gives the lowest LQ, is easier to prepare, and its surface can be easily renewed both chemically (by new amalgamation) and/or electrochemically (by imposition of cleaning pulses). The practical applicability of the newly developed methods was verified on model samples of drinking water.
Effect of elevated temperatures on mechanical properties of high‐strength concrete containing varying proportions of hematite
Authors: Gencel Osman 
Published: June 2011

SUMMARYAggregates typically constitute 70 to 80 wt% of concrete, and therefore their type, size, and structure play an essential role in modifying the properties of concrete. When concrete is used for shielding nuclear applications, temperature is also a key factor. This study investigates the effects of elevated temperatures (25 °C, 200 °C, 400 °C, 600 °C, and 800 °C), heating durations (1, 2, and 3 h), and cooling regimes (air, and water cooling) on mechanical properties of concrete containing different proportions of hematite. A sample of plain concrete was produced for comparison purposes by using river sand, crushed sand, and crushed aggregates. Replacement ratios of 15%, 30%, 45%, and 60% were used for hematite aggregates. The cement content and water–cement ratio were 450 kg/m3 and 0.38, respectively. Slump values of fresh concretes as well as unit weight, compressive strength, flexural strength, splitting tensile strength, and elasticity modulus values of hardened concrete were determined. The addition of hematite into concrete seems to improve its mechanical properties, and hematite concretes have better thermal stability at elevated temperatures than plain concrete does. Copyright © 2011 John Wiley & Sons, Ltd.
β8 integrin is essential for neuroblast migration in the rostral migratory stream
Authors: Mobley Aaron K. , McCarty Joseph H. 
Published: June 2011

AbstractNeurogenesis in the post‐natal brain occurs in two primary locations: the subgranular layer of the hippocampal dentate gyrus and the subventricular zone (SVZ) of the lateral ventricles. Following differentiation, neuroblasts within the SVZ migrate several millimeters to the olfactory bulbs (OBs) via a distinct anatomic route, or rostral migratory stream (RMS). The genes that govern neuroblast directional migration, and particularly those encoding cell adhesion and signaling factors, remain largely uncharacterized. Here, we report that the extracellular matrix adhesion receptor, β8 integrin, is essential for proper neuroblast chain formation and directional navigation in the RMS. Primary neuroblasts isolated from the mouse brain express robust levels of β8 integrin protein, and selective ablation of β8 integrin gene expression in neuroblasts leads to aberrant chain migration and size‐reduced OBs. These integrin‐dependent defects can be recapitulated ex vivo using isolated neurospheres or SVZ explants. Collectively, these data identify essential cell‐intrinsic functions for β8 integrin in regulating neuroblast polarity and directional navigation in the mouse forebrain. © 2011 Wiley‐Liss, Inc.
Evidence for intact local connectivity but disrupted regional function in the occipital lobe in children and adolescents with schizophrenia
Authors: White Tonya , Moeller Steen , Schmidt Marcus , Pardo Jose V. , Olman Cheryl 
Published: June 2011

AbstractIt has long been known that specific visual frequencies result in greater blood flow to the striate cortex. These peaks are thought to reflect synchrony of local neuronal firing that is reflective of local cortical networks. Since disrupted neural connectivity is a possible etiology for schizophrenia, our goal was to investigate whether localized connectivity, as measured by aberrant synchrony, is abnormal in children and adolescents with schizophrenia. Subjects included 25 children and adolescents with schizophrenia and 39 controls matched for age and gender. Subjects were scanned on a Siemens 3 Tesla Trio scanner while observing flashing checkerboard presented at either 1, 4, 8, or 12 Hz. Image processing included both a standard GLM model and a Fourier transform analysis. Patients had significantly smaller volume of activation in the occipital lobe compared to controls. There were no differences in the integral or percent signal change of the hemodynamic response function for each of the four frequencies. Occipital activation was stable during development between childhood and late adolescence. Finally, both patients and controls demonstrated an increased response between 4 and 8 Hz consistent with synchrony or entrainment in the neuronal response. Children and adolescents with schizophrenia had a significantly lower volume of activation in the occipital lobe in response to the flashing checkerboard task. However, features of intact local connectivity in patients, such as the hemodynamic response function and maximal response at 8 Hz, were normal. These results are consistent with abnormalities in regional connectivity with preserved local connectivity in early‐onset schizophrenia. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc
Temporally remote destabilization of prediction after rare breaches of expectancy
Authors: Kühn Anne B. , Schubotz Ricarda I. 
Published: June 2011

AbstractWhile neural signatures of breaches of expectancy and their immediate effects have been investigated, thus far, temporally more remote effects have been neglected. The present fMRI study explored neural correlates of temporally remote destabilization of prediction following rare breaches of expectancy with a mean delay of 14 s. We hypothesized temporally remote destabilization to be reflected either in an attenuation of areas related to long‐term memory or in an increase of lateral fronto‐parietal loops related to the encoding of new stimuli. Monitoring a deterministic 24‐digit sequence, subjects were asked to indicate occasional sequential omissions by key press. Temporally remote destabilization of prediction was expected to be revealed by contrasting sequential events whose equivalent was omitted in the preceding sequential run n‐1 (destabilized events) with sequential events without such history (nondestabilized events). Temporally remote destabilization of prediction was reflected in an attenuation of activity in the dorsal frontomedian cortex (Brodmann Area (BA) 9) bilaterally. Moreover, activation of the left medial BA 9 was enhanced by contrasting nondestabilized events with breaches. The decrease of dorsal frontomedian activation in the case of destabilized events might be interpreted as a top‐down modulation on perception causing a less expectation‐restricted encoding of the current stimulus and hence enabling the adaptation of expectation and prediction in the long run. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc
The concentration index of a binary outcome revisited
Authors: Wagstaff Adam 
Published: June 2011

SUMMARYThe binary variable is one of the most common types of variables in the analysis of income‐related health inequalities. I argue that while the binary variable has some unusual properties, it shares many of the properties of the ratio–scale variable and hence lends itself to both relative and absolute inequality analyses, albeit with some qualifications. I argue that criticisms of the normalization I proposed in an earlier paper, and of the use of the binary variable for inequality analysis, stem from a misrepresentation of the properties of the binary variable, as well as a switch of focus away from relative inequality to absolute inequality. I concede that my normalization is not uncontentious, but, in a way, that has not previously been noted. Copyright © 2011 John Wiley & Sons, Ltd.
Novel Compounds with a Viologen Skeleton and N‐Heterocycles on the Peripheries: Electrochemical and Spectroscopic Properties
Authors: Asaftei Simona , Lepadatu Ana Maria , Ciobanu Marius 
Published: June 2011

AbstractThe present article deals with novel compounds comprising a redox‐active group as core and a nucleobase in the peripheries, linked covalently via a spacer. The new derivatives 1,1′,1″‐(benzene‐1,3,5‐triyltrimethanediyl)tris{1′‐[3‐(3,4‐dihydro‐5‐methyl‐2,4‐dioxopyrimidin‐1(2H)‐yl)propyl]‐4,4′‐bipyridinium} hexafluorophosphate (1), 1,1′,1″‐(benzene‐1,3,5‐triyltrimethanediyl)tris{1′‐[2‐(4‐chloro‐7H‐pyrrolo[2,3‐d]pyrimidine‐7‐yl)ethyl]‐4,4′‐bipyridinium} hexachloride (2a)The numbering of the pyrrolo[2,3‐d]pyrimidine system follows the IUPAC rules and is different from that of the purine ring system.
, and 1,1′,1″‐(benzene‐1,3,5‐triyltrimethanediyl)tris{1′‐[2‐(2‐amino‐4‐chloro‐7H‐pyrrolo[2,3‐d]pyrimidine‐7‐yl)ethyl]‐4,4′‐bipyridinium} hexabromide (2b)1) were synthesized by nucleobase‐anion alkylation and linked to the 4,4′‐bipyridinium core. UV and CV analyses of these compounds were performed and revealed significantly different properties.
Beilschmiedic Acids F and G, Further Endiandric Acid Derivatives from Beilschmiedia anacardioides
Authors: Chouna Jean Rodolphe , Alango Nkeng‐Efouet Pepin , Ndjakou Lenta Bruno , Duplex Wansi Jean , Neumann Beate , Stammler Hans‐Georg , Fon Kimbu Samuel , Sewald Norbert 
Published: June 2011

AbstractTwo new endiandric acid derivatives, beilschmiedic acid F (1) and beilschmiedic acid G (2), together with three known constituents, beilschmiedic acid A, beilschmiedic acid C, and sitosterol 3‐β‐D‐glucopyranoside, were isolated from the stem bark of Beilschmiedia anacardioides. Their structures were elucidated mainly by using a combination of 1D‐ and 2D‐NMR techniques. The structure and relative configuration of beilschmiedic acid G (2) was also confirmed by X‐ray crystallographic analysis.
Two New Megastigmane Glycosides and a New Iridoid Glycoside from Gelsemium elegans
Authors: Zhang Qiu‐Ping , Zhang Bin‐Feng , Chou Gui‐Xin , Wang Zheng‐Tao 
Published: June 2011

AbstractTwo new megastigmane glycosides, eleganosides A and B (1 and 3, resp.), and one new iridoid glycoside, gouwenoside A (4), together with two known compounds, foliasalacioside B1 (2) and loganin (5), were isolated from the aerial parts of Gelsemium elegans (Gardn. et Champ.) Benth. (Loganiaceae). Their structures were elucidated by spectroscopic methods including 1D‐ and 2D‐NMR techniques. The absolute configuration of 1 was determined by CD spectroscopy.
Oleanane‐Type Triterpenoids from the Endophytic Fungus Pestalotiopsis clavispora Isolated from the Chinese Mangrove Plant Bruguiera sexangula
Authors: Luo Du‐Qiang , Deng Hui‐Ying , Yang Xiao‐Long , Shi Bao‐Zhong , Zhang Jing‐Ze 
Published: June 2011

AbstractThree new triterpenoid derivatives, named (15α)‐15‐hydroxysoyasapogenol B (1), (7β,15α)‐7,15‐dihydroxysoyasapogenol B (2), and (7β)‐7,29‐dihydroxysoyasapogenol B (3), were isolated from cultures of the plant endophytic fungus Pestalotiopsis clavispora. Their structures and relative configurations were elucidated by extensive spectroscopic analysis and X‐ray crystallography.
One‐Pot Synthesis of 2‐Substituted 4‐Aryl‐4,5‐dihydro‐3,1‐benzoxazepines from 2‐(2‐Aminophenyl)‐1‐arylethanols via Dehydration of the Corresponding Amides
Authors: Fukamachi Shuhei , Konishi Hisatoshi , Kobayashi Kazuhiro 
Published: June 2011

AbstractAn efficient method for the preparation of 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepine derivatives under mild conditions has been developed. The reaction of 2‐(2‐aminophenyl)ethanols 1 with acid chlorides in the presence of excess Et3N in THF at room temperature gave the corresponding N‐acylated intermediates 2, which were dehydrated by treatment with POCl3 to give 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepines 3 in a one‐pot reaction.
Resveratrol‐induced apoptosis is enhanced in low pH environments associated with cancer
Authors: Shamim Uzma , Hanif Sarmad , Albanyan Abdulmajeed , Beck Frances W.J. , Bao Bin , Wang Zhiwei , Banerjee Sanjeev , Sarkar Fazlul H. , Mohammad Ramzi M. , Hadi Sheikh M. , Azmi Asfar S. 
Published: June 2011

AbstractMany critical factors such as hypoxia, nutrient deficiency, activation of glycolytic pathway/Warburg effect contribute to the observed low pH in tumors compared to normal tissue. Studies suggest that such tumor specific acidic environment can be exploited for the development of therapeutic strategies against cancer. Independent observations show reduction in pH of mammalian cells undergoing internucleosomal DNA fragmentation and apoptosis. As such, our group has extensively demonstrated that anticancer mechanisms of different plant polyphenols involve mobilization of endogenous copper and consequent internucleosomal DNA breakage. Copper is redox active metal, an essential component of chromatin and is sensitive to subtle pH changes in its microenvironment. Here we explored whether, acidic pH promotes growth inhibition, apoptosis, and DNA damaging capacity of chemopreventive agent resveratrol. Our results reveal that growth inhibition and internucleosomal DNA fragmentation induced apoptosis in Capan‐2 and Panc‐28 pancreatic cancer cell lines (and not in normal HPDE cells) by resveratrol is enhanced at lower pH. Using comet assay, we further demonstrate that DNA breakage by resveratrol is enhanced with acidification. Membrane permeable copper specific chelator neocuproine (and not iron chelator orthophenanthroline) abrogated growth inhibition and apoptosis by resveratrol. Western blot results show enhanced activation of DNA laddering marker H2.aX by resveratrol at acidic pH that was reversed by neocuproine and not by orthophenanthroline. Our findings provide irrevocable proof that low pH environment can be turned into tumor weakness and assist in eradication of cancer cells by resveratrol. J. Cell. Physiol. 227: 1493–1500, 2012. © 2011 Wiley Periodicals, Inc.