bluuebunny/crossref_metadata_2025 huggingface dataset:
Porphyrin‐Based Switchable Molecular Turnstiles
Authors: Guenet Aurélie , Graf Ernest , Kyritsakas Nathalie , Hosseini Mir Wais
Published: April 2011

The design, synthesis and structural characterisation, in solution, of two new molecular turnstiles based on Sn–porphyrin derivatives are described. The system is composed of a stator (5‐(4‐pyridyl)‐10,15,20‐triphenylporphyrin), a hinge (SnIV) and a rotor (handle equipped with 2,6‐pyridinedicarboxamide as a tridentate coordinating site or its PdII complex). The presence of interaction sites, both on the stator and the rotor, offers the possibility of switching between an open state (free rotation of the handle around the porphyrin) and a closed state (blockage of the rotation) by either establishment of hydrogen bonds between the stator and the rotor or by the simultaneous binding of Pd by both coordinating groups.
Direct Arylation of Heteroaromatic Compounds with Congested, Functionalised Aryl Bromides at Low Palladium/Triphosphane Catalyst Loading
Authors: Roy David , Mom Sophal , Lucas Dominique , Cattey Hélène , Hierso Jean‐Cyrille , Doucet Henri
Published: April 2011

A new ferrocenyl triphosphane ligand associated to palladium was found to be an efficient catalyst for the direct coupling of highly congested, functionalised aryl bromides with a variety of heteroarenes. These coupling reactions can generally be performed by using a low‐loading (0.1–0.5 mol %) of the catalyst. The present protocol tolerates important and useful functional groups, which allows for further elaboration into more sophisticated heterocyclic molecules. The straightforward arylation of heteroaromatic compounds with congested ortho‐substituted aryl bromides may permit further convergent syntheses of diverse ligands, biologically active molecules and molecular materials in only a few steps.
Current Methods for Asymmetric Halogenation of Olefins
Authors: Castellanos Alejandro , Fletcher Stephen P.
Published: April 2011

This Minireview discusses the progress made in developing reactions where an olefin is subjected to an asymmetric halogenation. It aims to serve as a reference for the studies reported to date, including preliminary work and mechanistic studies. The current state of the art, scope, and limitations of these processes are discussed.
Contribution of Explicit Solvent Effects to the Binding Affinity of Small‐Molecule Inhibitors in Blood Coagulation Factor Serine Proteases
Authors: Abel Robert , Salam Noeris K. , Shelley John , Farid Ramy , Friesner Richard A. , Sherman Woody
Published: April 2011

The prevention of blood coagulation is important in treating thromboembolic disorders, and several serine proteases involved in the coagulation cascade have been classified as pharmaceutically relevant. Whereas structure‐based drug design has contributed to the development of some serine protease inhibitors, traditional computational methods have not been able to fully describe structure–activity relationships (SAR). Here, we study the SAR for a number of serine proteases by using a method that calculates the thermodynamic properties (enthalpy and entropy) of the water that solvates the active site. We show that the displacement of water from specific subpockets (such as S1–4 and the ester binding pocket) of the active site by the ligand can govern potency, especially for cases in which small chemical changes (i.e., a methyl group or halogen) result in a substantial increase in potency. Furthermore, we describe how relative binding free energies can be estimated by combining the water displacement energy with complementary terms from an implicit solvent molecular mechanics description binding.
Development of Novel Peptidomimetics Containing a Vinyl Sulfone Moiety as Proteasome Inhibitors
Authors: Ettari Roberta , Bonaccorso Cinzia , Micale Nicola , Heindl Cornelia , Schirmeister Tanja , Calabrò Maria Luisa , Grasso Silvana , Zappalà Maria
Published: April 2011

Proteasome inhibition is a topic of great interest in anticancer research. The proteolytic activity of this multicatalytic complex relies on three subunits, β1, β2 and β5, containing a caspase‐like, a trypsin‐like and a chymotrypsin‐like active site, respectively. Several studies have demonstrated that, of the three activities, the chymotrypsin‐like activity was the most necessary for cell viability and protein processing. Thus, most efforts towards the development of proteasome inhibitors have focused on the selective inhibition of the β5 subunit active site. Herein, we report the design and synthesis of a series of conformationally constrained tripeptidyl vinyl sulfones were determined to be good inhibitors of the chymotrypsin‐like activity of proteasome, with KI values in the sub‐micromolar to micromolar range. These compounds were also tested against bovine pancreatic α‐chymotrypsin and human cathepsin B and L, revealing a good selectivity for the target enzyme over these related enzymes.
Dissociative Electron Attachment to β‐Alanine
Authors: Vizcaino Violaine , Bartl Peter , Gschliesser David , Huber Stefan E. , Probst Michael , Märk Tilmann D. , Scheier Paul , Denifl Stephan
Published: April 2011

A detailed study on dissociative electron attachment (DEA) to β‐alanine (βA) in the gas phase is presented. Ion yields as a function of the incident electron energy from about 0 to 15 eV have been measured for most of the fragments. As for all α‐amino acids, the main reaction corresponds to the loss of a hydrogen atom, although many other fragments have been observed that involved more complex bond cleavages. Threshold energies have been calculated by using the G4(MP2) method for various decomposition reactions. Fragmentation pathways were also investigated to measure metastable decays of the intermediate fragment anion (βA−H)− by using the mass‐analyzed ion kinetic energy (MIKE) scan technique. Comparisons with α‐alanine and other amino acids are made when relevant.
Correlation between Luminescence and EPR Spectroscopy as Evidence of Ytterbium Pair Formation in Li6Ln(BO3)3:Yb3+ (Ln=Gd, Y) Borate Single Crystals
Authors: Jubera Véronique , Chavoutier Marie , Artemenko Alla , Veber Philippe , Velazquez Matias , Garcia Alain
Published: April 2011

Synthesized powders and grown single crystals of nominal compositions Li6Ln(BO3)3:Yb3+ (Ln=Y, Gd) were investigated by means of powder and single‐crystal X‐ray diffraction (XRD), as well as optical near‐IR spectroscopy in conjunction with electron paramagnetic resonance (EPR) spectroscopy. The appearance of two distinct zero‐phonon lines suggests the existence of two kinds of Yb3+ ions in the single crystals. The XRD results exclude the possibility of a phase transition occurring between room and low temperatures. EPR spectra of single crystals show the presence of both isolated ions and pairs of ytterbium ions substituted for Y3+. A strong temperature dependence of the intensity of Yb–Yb pairs resonance lines coincides with temperature dependence of emission peak at 978 nm, confirming a common origin of the defect giving rise to these spectra. Calculated from EPR spectra, the distance between pairs of Yb3+ is in good agreement with crystallographic ones: R=3.856 Å, Rcryst=3.849 Å.
Semiquinone Intermediates in the Two‐Electron Reduction of Quinones in Aqueous Media and their Exceptionally High Reactivity towards Oxygen Reduction
Authors: Li Qian , Batchelor‐McAuley Christopher , Lawrence Nathan S. , Hartshorne Robert S. , Compton Richard G.
Published: April 2011

We report the catalytic anthraquinone‐mediated reduction of oxygen at a boron‐doped diamond electrode. Scheme of squares modelling confirms the existence of and reveals the role of the semiquinone intermediates, which are shown to have an exceptional reactivity towards oxygen (as compared to the di‐reduced anthraquinone).
Design of Ru–Zeolites for Hydrogen‐Free Production of Conjugated Linoleic Acids
Authors: Philippaerts An , Goossens Steven , Vermandel Walter , Tromp Moniek , Turner Stuart , Geboers Jan , Van Tendeloo Gustaaf , Jacobs Pierre A. , Sels Bert F.
Published: April 2011

While conjugated vegetable oils are currently used as additives in the drying agents of oils and paints, they are also attractive molecules for making bio‐plastics. Moreover, conjugated oils will soon be accepted as nutritional additives for “functional food” products. While current manufacture of conjugated vegetable oils or conjugated linoleic acids (CLAs) uses a homogeneous base as isomerisation catalyst, a heterogeneous alternative is not available today. This contribution presents the direct production of CLAs over Ru supported on different zeolites, varying in topology (ZSM‐5, BETA, Y), Si/Al ratio and countercation (H+, Na+, Cs+). Ru/Cs‐USY, with a Si/Al ratio of 40, was identified as the most active and selective catalyst for isomerisation of methyl linoleate (cis‐9,cis‐12 (C18:2)) to CLA at 165 °C. Interestingly, no hydrogen pre‐treatment of the catalyst or addition of hydrogen donors is required to achieve industrially relevant isomerisation productivities, namely, 0.7 g of CLA per litre of solvent per minute. Moreover, the biologically most active CLA isomers, namely, cis‐9,trans‐11, trans‐10,cis‐12 and trans‐9,trans‐11, were the main products, especially at low catalyst concentrations. Ex situ physicochemical characterisation with CO chemisorption, extended X‐ray absorption fine structure measurements, transmission electron microscopy analysis, and temperature‐programmed oxidation reveals the presence of highly dispersed RuO2 species in Ru/Cs‐USY(40).
Power‐efficient analog design based on the class AB super source follower
Authors: Lopez‐Martin Antonio J. , Acosta Lucia , Garcia‐Alberdi Coro , Carvajal Ramon G. , Ramirez‐Angulo Jaime
Published: April 2011

A class AB version of the conventional super source follower (SSF) is described. The circuit greatly increases slew rate (SR) and current efficiency, maintaining the low distortion and low output resistance of the SSF. Class AB operation is achieved without extra power dissipation or supply requirements, and without bandwidth or noise degradation. The circuit can advantageously replace the SSF in a wide variety of analog systems, opening a new research line in analog design. To illustrate the widespread application of this cell, a class AB differential unity‐gain buffer, a class AB differential current mirror and two class AB differential transconductors are designed, fabricated in a 0.5µm CMOS technology and tested. Measurement results using a dual supply of ±1.65V show that the proposed class AB version of the SSF improves SR by a factor 21.5 and increases bandwidth by 10%, keeping noise level, input range, power consumption, and supply requirements unaltered. The fabricated class AB current mirror features a THD at 100 kHz of − 62dB for signal currents 20 times larger than the bias current. The fabricated transconductors feature an IM3 at 1 MHz of − 56.6dB for output currents more than 13 times larger than the bias currents. Copyright © 2011 John Wiley & Sons, Ltd.
The synaptic cytoskeleton in development and disease
Authors: Goellner Bernd , Aberle Hermann
Published: April 2011

The cytoskeleton forms the backbone of neuronal architecture, sustaining its form and size, subcellular compartments and cargo logistics. The synaptic cytoskeleton can be categorized in the microtubule‐based core cytoskeleton and the cortical membrane skeleton. While central microtubules form the fundamental basis for the construction of elaborate neuronal processes, including axons and synapses, cortical actin filaments are generally considered to function as mediators of synapse dynamics and plasticity. More recently, the submembranous network of spectrin and ankyrin molecules has been involved in the regulation of synaptic stability and maintenance. Disruption of the synaptic cytoskeleton primarily affects the stability and maturation of synapses but also secondarily disturbs neuronal communication. Consequently, a variety of inherited diseases are accompanied by cytoskeletal malfunctions, including spastic paraplegias, spinocerebellar ataxias, and mental retardation. Since the primary reasons for many of these diseases are still unknown model organisms with a conserved repertoire of cytoskeletal elements help to understand the underlying biological mechanisms. The astonishing technical as well as genetic accessibility of synapses in Drosophila has shown that loss of the cytoskeletal architecture leads to axonal transport defects, synaptic maturation deficits, and retraction of synaptic boutons, before synaptic terminals finally detach from their target cells, suggesting that similar processes could be involved in human neuronal diseases. © 2011 Wiley Periodicals, Inc. Develop Neurobiol 72: 111–125, 2012
3D expression patterns of cell cycle genes in the developing chick wing and comparison with expression patterns of genes implicated in digit specification
Authors: Welten Monique , Pavlovska Gordana , Chen Yu , Teruoka Yuko , Fisher Malcolm , Bangs Fiona , Towers Matthew , Tickle Cheryll
Published: April 2011

Sonic hedgehog (Shh) signalling controls integrated specification of digit pattern and growth in the chick wing but downstream gene networks remain to be unravelled. We analysed 3D expression patterns of genes encoding cell cycle regulators using Optical Projection Tomography. Hierarchical clustering of spatial matrices of gene expression revealed a dorsal layer of the wing bud, in which almost all genes were expressed, and that genes encoding positive cell cycle regulators had similar expression patterns while those of N‐myc and CyclinD2 were distinct but closely related. We compared these patterns computationally with those of genes implicated in digit specification and Ptch1, 50 genes in total. Nineteen genes have similar posterior expression to Ptch1, including Hoxd13, Sall1, Hoxd11, and Bmp2, all likely Gli targets in mouse limb, and cell cycle genes, N‐myc, CyclinD2. We suggest that these genes contribute to a network integrating digit specification and growth in response to Shh. Developmental Dynamics 240:1278–1288, 2011. © 2011 Wiley‐Liss, Inc.
Summary of ‘Lactulose versus polyethylene glycol for chronic constipation’
Authors: Canadian Editorial Office Evidence‐Based Child Health
Published: April 2011

This is a summary of a Cochrane review, published in this issue of EBCH, first published as: Lee‐Robichaud H, Thomas K, Morgan J, Nelson RL. Lactulose versus polyethylene glycol for chronic constipation. Cochrane Database of Systematic Reviews 2010, Issue 7. Art. No.: CD007570. DOI: 10.1002/14 651 858.CD007570.pub2. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Commentary on ‘Lactulose versus polyethylene glycol for chronic constipation’
Authors: Vandenplas Yvan , Greef Elisabeth De , Smeets Nathalie , Hauser Bruno
Published: April 2011

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Lee‐Robichaud H, Thomas K, Morgan J, Nelson RL. Lactulose versus polyethylene glycol for chronic constipation. Cochrane Database of Systematic Reviews 2010, Issue 7. Art. No.: CD007570. DOI: 10.1002/14 651 858.CD007570.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Commentaries on ‘One dose per day compared to multiple doses per day of gentamicin for treatment of suspected or proven sepsis in neonates’
Authors: Hoff David S. , Batra Maneesh , Darmstadt Gary L.
Published: April 2011

These are commentaries on a Cochrane review, published in this issue of EBCH, first published as: Rao SC, Srinivasjois R, Hagan R, Ahmed M. One dose per day compared to multiple doses per day of gentamicin for treatment of suspected or proven sepsis in neonates. Cochrane Database of Systematic Reviews 2006, Issue 1. Art.No.: CD005091. DOI: 10.1002/14 651 858.CD005091.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Commentary on ‘Polysaccharide vaccines for preventing serogroup A meningococcal meningitis’
Authors: LaForce F. Marc
Published: April 2011

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Patel M, Lee CK. Polysaccharide vaccines for preventing serogroup A meningococcal meningitis. Cochrane Database of Systematic Reviews 2005, Issue 1. Art. No.: CD001093. DOI: 10.1002/14 651 858.CD001093.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Summary of ‘Restricted versus liberal water intake for preventing morbidity and mortality in preterm infants’
Authors: Canadian Editorial Office Evidence‐Based Child Health
Published: April 2011

This is a summary of a Cochrane review, published in this issue of EBCH, first published as: Bell EF, Acarregui MJ. Restricted versus liberal water intake for preventing morbidity and mortality in preterm infants. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD000503. DOI: 10.1002/14 651 858.CD000503.pub2. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Commentary on ‘Restricted versus liberal water intake for preventing morbidity and mortality in preterm infants’
Authors: Bhatia Jatinder , Mathew Oommen P.
Published: April 2011

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Bell EF, Acarregui MJ. Restricted versus liberal water intake for preventing morbidity and mortality in preterm infants. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD000503. DOI: 10.1002/14 651 858.CD000503.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Summary of ‘Dietary marine fatty acids (fish oil) for asthma in adults and children’
Authors: Canadian Editorial Office Evidence‐Based Child Health
Published: April 2011

This is a summary of a Cochrane review, published in this issue of EBCH, first published as: Thien FCK, De Luca S, Woods RK, Abramson MJ. Dietary marine fatty acids (fish oil) for asthma in adults and children. Cochrane Database of Systematic Reviews 2002, Issue 2. Art. No.: CD001283. DOI: 10.1002/14 651 858. CD001283. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Commentary on ‘Dietary marine fatty acids (fish oil) for asthma in adults and children’
Authors: Reisman Joseph
Published: April 2011

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Thien FCK, De Luca S, Woods RK, Abramson MJ. Dietary marine fatty acids (fish oil) for asthma in adults and children. Cochrane Database of Systematic Reviews 2002, Issue 2. Art. No.: CD001283. DOI: 10.1002/14 651 858. CD001283.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2011 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Comparison of estimated and experimental subaqueous seed transport
Authors: Markwith Scott H. , Leigh David S.
Published: April 2011

We compare the estimates from the relative bed stability (RBS) equation that indicates incipient bed movement, and the inertial settling (‘Impact’) law and Wu and Wang (2006) settling velocity equations that indicate suspended particle movement, to flume and settling velocity observations to confirm the utility of the equations for subaqueous hydrochory analyses, and to calibrate our estimates by examining the method by which seed volume is obtained. Comparison of the observed measures with the estimates of the inertial settling (‘Impact’) law and RBS equations indicate that these two equations appear to provide reasonable approximations of the velocities required to achieve transport both in suspension and on the bed, respectively. The use of the water displacement method for volume measurement is a technologically simple method for improving the accuracy of the estimates. Copyright © 2011 John Wiley & Sons, Ltd.
Killing of Kaposi's sarcoma‐associated herpesvirus‐infected fibroblasts during latent infection by activated natural killer cells
Authors: Matthews Nick C. , Goodier Martin R. , Robey Rebecca C. , Bower Mark , Gotch Frances M.
Published: April 2011

Kaposi's sarcoma‐associated herpesvirus (KSHV) establishes life‐long infection by evading clearance by the host immune system. In de novo infection and lytic replication, KSHV escapes cytotoxic T cells and NK cells through downregulation of MHC class‐I and ICAM‐1 molecules and associated antigens involved in forming and sustaining the immunological synapse. However, the efficacy of such mechanisms in the context of the predominantly latent KSHV infection reported in Kaposi's sarcoma (KS) lesions is unclear. Using primary dermal fibroblasts in a novel in vitro model of chronic latent KSHV infection, we generated target cells with viral loads similar to those in spindle cells extracted from KS lesions. We show that latently KSHV‐infected fibroblasts had normal levels of MHC‐class I, ICAM‐1, HLA‐E and NKG2D ligand expression, were resistant to NK‐cell natural cytotoxicity and were highly susceptible to killing by cytokine‐activated immunocompetent NK cells. KSHV‐infected fibroblasts expressed normal levels of IFN‐γR1 and responded to exogenous IFN‐γ by upregulating MHC class I, ICAM‐1 and HLA‐E and resisting activated NK‐cell killing. These data demonstrate that physiologically relevant levels of latent KSHV infection in primary cells cause limited activation of resting NK cells and confer little specific resistance to control by activated NK cells.
Single‐cell dynamics of mast cell–CD4+CD25+ regulatory T cell interactions
Authors: Frossi Barbara , D'Incà Federica , Crivellato Enrico , Sibilano Riccardo , Gri Giorgia , Mongillo Marco , Danelli Luca , Maggi Laura , Pucillo Carlo E.
Published: April 2011

The biological behavior of immune cells is determined by their intrinsic properties and interactions with other cell populations within their microenvironment. Several studies have confirmed the existence of tight spatial interactions between mast cells (MCs) and Tregs in different settings. For instance, we have recently identified the functional cross‐talk between MCs and Tregs, through the OX40L–OX40 axis, as a new mechanism of reciprocal influence. However, there is scant information regarding the single‐cell dynamics of this process. In this study, time‐lapse video microscopy revealed direct interactions between Tregs and MCs in both murine and human cell co‐cultures, resulting in the inhibition of the MC degranulation response. MCs incubated with WT, but not OX40‐deficient, Tregs mediated numerous and long‐lasting interactions and displayed different morphological features lacking the classical signs of exocytosis. MC degranulation and Ca2+ mobilization upon activation were inhibited by Tregs on a single‐cell basis, without affecting overall cytokine secretion. Transmission electron microscopy showed ultrastructural evidence of vesicle‐mediated secretion reconcilable with the morphological pattern of piecemeal degranulation. Our results suggest that MC morphological and functional changes following MC–Treg interactions can be ascribed to cell–cell contact and represent a transversal, non‐species‐specific mechanism of immune response regulation. Further research, looking at the molecular composition of this interaction will broaden our understanding of its contribution to immunity.
Lack of IL‐2 in PPAR‐α‐deficient mice triggers allergic contact dermatitis by affecting regulatory T cells
Authors: Dubrac Sandrine , Elentner Andreas , Schoonjans Kristina , Auwerx Johan , Schmuth Matthias
Published: April 2011

The aim of the present work was to decipher the cellular basis of the immunoregulatory role of peroxisome proliferator‐activated receptor (PPAR)‐α in cutaneous hypersensitivity reactions. After challenge with a contact allergen, we observed augmented hypersensitivity reactions with increased numbers of activated T lymphocytes in the skin of PPAR‐α−/− mice. Furthermore, following antigen challenge, the percentages of Tregs in the blood, draining lymph nodes and skin were decreased in these mice. PPAR‐α deficiency impaired the production of IL‐2 in lymph nodes, whereas TGF‐β levels remained unchanged. Injection of IL‐2 into PPAR‐α−/− mice restored the Treg population in the skin‐draining lymph nodes of allergen‐challenged mice. In vivo induction of Tregs from WT CD4+CD25− T cells was impaired when adoptively transferred into PPAR‐α−/− mice as compared with transfer into WT mice, and reversed by injection of IL‐2 into PPAR‐α−/− mice. Furthermore, the suppressive capacity of PPAR‐α−/− Tregs was impaired when compared to WT Tregs in vitro and in co‐adoptive transfer experiments. Finally, injection of IL‐2 to PPAR‐α−/− mice decreased skin inflammation to a level similar to WT mice. In conclusion, the pro‐inflammatory skin phenotype of PPAR‐α−/− mice is due to lack of IL‐2‐mediated Treg induction in these mice.
Unprecedented B–H Activation Through Pd‐Catalysed B–Cvinyl Bond Coupling on Borane Systems
Authors: Farràs Pau , Olid‐Britos David , Viñas Clara , Teixidor Francesc
Published: April 2011

A Pd‐induced cascade B–Cvinyl coupling that produces multiple B–Cvinyl bonds starting from a single B–I bond has been demonstrated. The process is most probably stimulated by the geometrical disposition of the B–H bonds confronting the B–Pd sites, along with the hydride character of the B–H units. Two and one B–Cvinyl couplings on the metallacarborane substrate have been generally obtained, but formation up to six B–Cvinyl bonds has been observed. A theoretical reaction mechanism involving an unprecedented B–H activation is proposed to interpret the multisubstitution process.
Optimization of the Efficiency of Oxidation Catalysts Based on Iron Bispidine Complexes
Authors: Comba Peter , Wadepohl Hubert , Wiesner Sebastian
Published: April 2011

High‐valent bispidine iron‐oxo complexes are among the most efficient nonheme iron oxidation catalysts. Here, we report the synthesis and structural analysis of two derivatives of the known pentadentate bispidine ligand L1 {L1 = 2,4‐pyridyl‐7‐(pyridine‐2‐ylmethyl)‐3,7‐diazabicyclo[3.3.1]nonane}: L2 and L3 {L2 = 2,4‐pyridyl‐7‐[1‐(pyridine‐2‐yl)ethyl]‐3,7‐diazabicyclo[3.3.1]nonane; L3 = 2,4‐pyridyl‐7‐[phenyl(pyridine‐2‐yl)methyl]‐3,7‐diazabicyclo[3.3.1]nonane}, and of their FeII complexes. The yield of the catalytic epoxidation of cyclooctene and styrene with iodosylbenzene as oxidant increases from the L1‐ to the L2‐ to the L3‐based catalyst (e.g., the yield of styrene oxide, with MeCN as solvent, under anaerobic conditions, is 40 %, 90 %, 96 %, respectively), and this is correlated to the FeIII/II reduction potentials {[Fe(L1)(NCMe)]n+ (1.01 V), [Fe(L2)(NCMe)]n+ (1.13 V), and [Fe(L3)(NCMe)]n+ (1.19 V), in MeCN, vs. SCE}. Although this correlation is not unexpected, the interpretation is not entirely trivial, and this is discussed in detail. The rigidity of the bispidine ligands and their preference for relatively large metal ions (low oxidation states, high spin multiplicities) is believed to be responsible for the efficiency of the bispidine‐based catalyst systems, and the present results show possible approaches to further improve the performance of these catalysts.
Regioselectivity in Electrophilic Aromatic Substitution: Insights from Interaction Energy Decomposition Potentials
Authors: Fievez Tim , Pinter Balazs , Geerlings Paul , Bickelhaupt F. Matthias , De Proft Frank
Published: April 2011

The SEAr reaction was scrutinized using a quantitative, fragment‐based interaction energy decomposition analysis (EDA) as implemented in the ADF program. The interaction energy between monosubstituted benzene derivatives and a model electrophile at the onset of the reaction was studied and decomposed into Pauli repulsion, electrostatic interaction and orbital interaction terms for a plane parallel to the molecular plane. As such experimentally observed selectivity patterns arise in the orbital interaction, stressing again the role of both electrophile and benzene derivative in determining the regioselectivity. Using the HSAB principle and MO theory, the orientation mechanism of the SEAr is further explored.
L‐Phe‐D‐Oxd: A Privileged Scaffold for the Formation of Supramolecular Materials
Authors: Castellucci Nicola , Angelici Gaetano , Falini Giuseppe , Monari Magda , Tomasini Claudia
Published: April 2011

Some compounds containing the L‐Phe‐D‐Oxd [L‐Phe = L‐phenylalanine; D‐Oxd = (4R,5S)‐4‐carboxy‐5‐methyl oxazolidin‐2‐one] moiety have been prepared and their properties as supramolecular material have been determined. Some derivatives of the dipeptide L‐Phe‐L‐Phe (which usually forms nanotubes) and some long‐chain derivatives that behave as low‐molecular‐weight gelators have been prepared. We have also replaced the D‐Oxd moiety with a D‐Pro (D‐Pro = D‐proline) moiety to check if the presence of the Oxd moiety was essential for the existence of those materials. In contrast to the D‐Oxd‐containing compounds, no material was ever formed with any of the D‐Pro‐containing molecules. This outcome suggests that the L‐Phe‐D‐Oxd moiety may be defined as a “privileged scaffold” for the formation of supramolecular materials and it can be introduced into more complex structures to induce some selected properties in the solid state.
Biologically Active Macrocyclic Compounds – from Natural Products to Diversity‐Oriented Synthesis
Authors: Madsen Charlotte M. , Clausen Mads H.
Published: April 2011

Macrocyclic compounds are attractive targets when searching for molecules with biological activity. The interest in this compound class is increasing, which has led to a variety of methods for tackling the difficult macrocyclization step in their synthesis. This microreview highlights some recent developments in the synthesis of macrocycles, with an emphasis on chemistry developed to generate libraries of putative biologically active compounds.
Easy One‐Pot Synthesis of Fused Heterocycles from 1,2‐Diaza‐1,3‐dienes
Authors: Attanasi Orazio A. , Bianchi Luca , De Crescentini Lucia , Favi Gianfranco , Mantellini Fabio
Published: April 2011

A base‐promoted chemoselective synthesis of 6a‐hydroxy‐6,6a‐dihydro‐1H‐thieno[3,4‐b]pyrrole‐3,3a(4H)‐dicarboxylates, 5‐(2‐furylmethyl)‐6a‐hydroxy‐6‐oxo‐4,5,6,6a‐tetrahydropyrrolo[3,4‐b]pyrrole‐3,3a(1H)‐dicarboxylates, and 5‐benzyl‐7a‐hydroxy‐1,4,5,6,7,7a‐hexahydro‐3aH‐pyrrolo[3,2‐c]pyridine‐3,3a‐dicarboxylates starting from diazadienes and heterocycles containing an activated methine group has been developed. This transformations proceeds by Michael addition/5‐exo cyclization sequence.
Removal of monochlorobenzene and perchloroethene in wetland rhizosphere model systems
Authors: Braeckevelt Mareike , Kaestner Matthias , Kuschk Peter
Published: April 2011

Constructed wetlands are a promising technology to protect river flood plains against the impact of contaminated groundwater. They are suitable for the treatment of waters contaminated with monochlorobenzene and perchloroethene. However, the removal performance differs with the operation conditions, and generally, transferable performance data are not yet available. In this study, removal efficiencies were determined and the dominant removal processes for monochlorobenzene and perchloroethene were evaluated under various operation conditions in helophyte rhizosphere reactors. Monochlorobenzene removal was very efficient (>99%) under low carbon load (overall oxic) and moderate carbon load (overall reduced) conditions. Higher loads of easily degradable carbon (acetate, 300 mg/L) impaired the elimination of monochlorobenzene (removal of 72−96%). Microbial reductive dechlorination of perchloroethene was not detected in the rhizosphere under low carbon load, sulphate reduction, and high‐carbon load conditions. Nonetheless, considerable amounts of perchloroethene were eliminated (79−87%), presumably by plant uptake and phytovolatilisation. Under fluctuating moderate carbon load conditions, perchloroethene dechlorination was initiated, and trichloroethene and cis‐dichloroethene production showed that a minimum of 10% of the perchloroethene inflow load was dechlorinated. Sulphate reduction and the associated sulphide toxicity showed to constitute a hazard for constructed wetland treatment of sulphate containing groundwater contaminated with chlorinated volatile organic compounds, causing a decrease in removal efficiencies by 50 and 20% for monochlorobenzene and perchloroethene, respectively.
Persistent organic pollutants in blood plasma of satellite-tracked adult male loggerhead sea turtles (Caretta caretta)
Authors: Ragland Jared M , Arendt Michael D , Kucklick John R , Keller Jennifer M
Published: April 2011

Risks from persistent organic pollutants (POPs) remain largely a mystery for threatened loggerhead sea turtles (Caretta caretta). The present study examines regional-scale POP differences in blood plasma from adult male C. caretta based on movement patterns. Turtles were captured near Port Canaveral, Florida, USA, in April of 2006 and 2007 and fitted with satellite transmitters as part of a National Marine Fisheries Service–funded project. Residents (n = 9) remained near the capture site, whereas transients (n = 10) migrated northward, becoming established in areas largely from south of Pamlico Sound, North Carolina, to north of Cape May, New Jersey, USA. Blood was sampled from the dorsocervical sinus of each turtle and analyzed using gas chromatography–mass spectrometry for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and toxaphenes. Blood plasma concentrations of OCPs and total PBDEs were elevated in transients (p < 0.05) and in some cases were correlated with turtle size. Migratory adults showed an atypical PBDE congener profile relative to other published studies on wildlife, with PBDE 154 being the dominant congener. Additionally, PCB congener patterns differed between groups, with total PCBs slightly elevated in transients. This supports the idea that foraging location can influence exposure to, and patterns of, POPs in highly mobile species such as C. caretta. Understanding patterns of contamination informs wildlife managers about possible health risks to certain subpopulations. The present study is the first to examine POPs in the rarely studied adult male sea turtle and to couple contaminant measurements with satellite tracking. Environ. Toxicol. Chem. 2011; 30:1549–1556. © 2011 SETAC
Calcium and magnesium enhance arsenate rhizotoxicity and uptake in Triticum aestivum
Authors: Wang Peng , Zhou Dongmei , Weng Nanyan , Wang Dengjun , Peijnenburg Willie J.G.M
Published: April 2011

Cations such as calcium (Ca) and magnesium (Mg) alleviate toxicities of cationic toxicants and increase those of anionic toxicants such as arsenic (As) present as arsenate under aerobic conditions. Increasing evidence exists that these phenomena are related to the outer surface electrical potential (ψ 0o) of the root cell plasma membrane (PM). Short-term (48-h) nutrient culture experiments with wheat (Triticum aestivum L.) seedlings investigated Ca and Mg effects on arsenate rhizotoxicity and uptake. Increased Ca and Mg in solution from 0.2 to 3.5 mM equally reduced the negativity of ψ 0o from −45 to −15 mV. This increased arsenate activity at the PM surface from 0.3 to 0.9 µM at the same bulk concentration of 2.0 µM NaH2AsO4 consequently increased arsenate uptake and rhizotoxicity. However, increased Mg was more effective than Ca in enhancing As uptake by roots, especially with the activity of As in the range of 0.5 to 1.5 µM in the bulk medium. This was explained by a modified electrostatic uptake model which indicated a mechanism other than through an effect on ψ 0o. Subcellular fractionation of roots indicated that > 95% of As was associated with cellular debris and heat-stable protein (HSP). The results of the present study show that Ca and Mg reduce the negativity of ψ 0o, increasing arsenate uptake and rhizotoxicity, and suggest that Mg is more efficient than Ca in enhancing the uptake of As due, in large part, to inducing greater As binding by peptides in the HSP fraction. Environ. Toxicol. Chem. 2011; 30:1642–1648. © 2011 SETAC
Developmental and posthatch effects of in ovo exposure to 2,3,7,8-TCDD, 2,3,4,7,8-PECDF, and 2,3,7,8-TCDF in Japanese quail (Coturnix japonica), common pheasant (Phasianus colchicus), and white leghorn chicken (Gallus gallus domesticus) embryos
Authors: Cohen-Barnhouse Andrew M , Zwiernik Matthew J , Link Jane E , Fitzgerald Scott D , Kennedy Sean W , Giesy John P , Wiseman Steve , Jones Paul D , Newsted John L , Kay Denise , Bursian Steven J
Published: April 2011

An egg injection study was conducted to confirm a proposed model of relative sensitivity of three avian species to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like chemicals. It was previously reported that the order of species sensitivity to in ovo exposure to TCDD, 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or 2,3,7,8-tetrachlorodibenzofuran (TCDF) at doses ranging from 0.044 to 37 picomoles (pmol)/g egg was the chicken (Gallus gallus domesticus), common pheasant (Phasianus colchicus), and Japanese quail (Coturnix japonica) based on embryo mortality and hepatic enzyme induction. In the present study, the incidence of developmental deformities, changes in body and relative organ masses, and organ pathology of hatchlings as additional indicators of species sensitivity were assessed; in addition, embryo mortality in the three species was categorized by stage of development. Embryo mortality varied temporally with significant increases generally occurring after organogenesis and just prior to hatching. A significant increase in the percentage of developmental deformities was observed only in Japanese quail exposed to TCDF. Body and relative organ masses of quail, pheasants, and chickens dosed in ovo with TCDD, PeCDF, or TCDF were not consistently affected. Chemical-related pathology occurred only in livers of quail at the greatest doses of each compound. These results indicated that the incidence of developmental deformities, changes in body and relative organ masses and organ pathology could not be used as indicators of species sensitivity or chemical potency. Environ. Toxicol. Chem. 2011; 30:1659–1668. © 2011 SETAC
Geographical variation of persistent organic pollutants in eggs of threatened loggerhead sea turtles (Caretta caretta) from southeastern United States
Authors: Alava Juan José , Keller Jennifer M , Wyneken Jeanette , Crowder Larry , Scott Geoffrey , Kucklick John R
Published: April 2011

Persistent organic pollutants (POPs) are recognized manmade threats to sea turtle populations, but substantial uncertainty exists surrounding their exposure to contaminants and their sensitivity to toxic effects. This uncertainty creates difficulty for conservation managers to make informed decisions for the recovery of these threatened species. To provide baseline concentrations and spatial comparisons, we measured a large suite of POPs in loggerhead sea turtle (Caretta caretta) egg yolk samples collected from 44 nests in three distinct U.S. locations: North Carolina (NC), eastern Florida (E FL), and western Florida (W FL). The POPs included polychlorinated biphenyls (PCBs), organochlorine pesticides such as dichlorodiphenyltrichloroethanes (DDTs), chlordanes, mirex, dieldin, hexachlorocyclohexanes (HCHs), hexachlorobenzene, and toxaphene congeners, as well as polybrominated diphenyl ether congeners (PBDEs). Persistent organic pollutant concentrations were lowest in W FL, intermediate in E FL, and highest in NC egg samples, with several statistically significant spatial differences. This increasing gradient along the southeast coast around the Florida peninsula to North Carolina was explained partly by the foraging site selection of the nesting females. Data from previous tracking studies show that NC nesting females feed primarily along the U.S. eastern coast, whereas W FL nesting females forage in the Gulf of Mexico and Caribbean Sea. The E FL nesting females forage in areas that overlap these two. The foraging site selection also results in exposure to different patterns of POPs. An unusual PBDE pattern was seen in the NC samples, with nearly equal contributions of PBDE congeners 47, 100, and 154. These findings are important to managers assessing threats among different stocks or subpopulations of this threatened species. Environ. Toxicol. Chem. 2011; 30:1677–1688. © 2011 SETAC
Volatile and sensory characterization of Xarel.lo white wines
Authors: Muñoz‐González Carolina , Moreno‐Arribas M Victoria , Martín‐Álvarez Pedro J , Bartra‐Sebastian Enric , Puig‐Pujol Ana , García‐Cazorla Joan , Pozo‐Bayón Maria Ángeles
Published: April 2011

A comprehensive study based on the profiling and quantification of the volatile composition and the application of descriptive sensory analysis of 25 commercial monovarietal white wines (var. Xarel.lo) from different vintages and from representative wine cellars along the Penedés region (Catalonia, Spain) was performed in order to characterize representative wines that are being commercialized under the O.D. Penedés. In addition, relationships between the instrumental (volatile) and sensory variables were found through the application of partial least squares regression. The results showed great differences between younger wines and wines that underwent the crianza (or ageing) process. The first group of wines was characterized by a marked fruity and floral odour and fresh taste, while the second group was characterized by more complex sensory attributes such as toasted, spicy and compote odour attributes. These differences in sensory characteristics were related to a higher content of higher alcohol acetates and ethyl and methyl esters of fatty acids in wines included in the first group, while the second group was characterized by a lower concentration of esters, but higher concentration of compounds related to wine ageing, such as furfural, 5‐methylfurfural and vitispiranes. Copyright © 2011 John Wiley & Sons, Ltd.
The convenience yield implied in European natural gas hub trading
Authors: Hochradl Markus , Rammerstorfer Margarethe
Published: April 2011

In this study, we investigate the estimates of the convenience yield implied in European natural gas hub trading. In addition to the net convenience yield, we provide two option/based approaches, which connect to the economic idea of the convenience yield as being the benefits from holding the physical commodity. In particular, we approximate the convenience yield via lookback and Asian options. Our empirical results are consistent with the intuition conveyed by the theory of storage. We conclude that the choice of an adequate approximation method should depend on the market under investigation, in particular, on the existence of market frictions such as short/sale constraints or restricted storage access. © 2011 Wiley Periodicals, Inc. Jrl Fut Mark
Zircon U‐Pb/Lu‐Hf and monazite chemical dating of the Tirodi biotite gneiss: implication for latest Palaeoproterozoic to Early Mesoproterozoic orogenesis in the Central Indian Tectonic Zone
Authors: Bhowmik Santanu Kumar , Wilde Simon A. , Bhandari Anubha
Published: April 2011

In this investigation, we reconstruct the latest Palaeoproterozoic to Early Mesoproterozoic orogenic events along the southern margin of the Central Indian Tectonic Zone (CITZ), using sensitive high resolution ion microprobe (SHRIMP) U‐Pb zircon dating and Lu‐Hf isotope analyses of zircon and Th‐U‐Pb chemical dating of monazite from samples of the Tirodi biotite gneiss (TBG) unit in the Sausar Mobile Belt (SMB), the latter constituting the southernmost litho‐tectonic component of the CITZ. U‐Pb zircon dating of one migmatitic gneiss sample from the type locality of the Tirodi biotite gneiss in the northern domain of the SMB has yielded an age of 1618 ± 8 Ma, which is considered to be the time of magmatic crystallization of its protolith. Combined U‐Pb zircon and monazite chemical dating of two granite gneiss samples from the southern domain of the SMB broadly constrain magmatic crystallization between 1603 ± 23 Ma and 1584 ± 17 Ma and an overprinting metamorphic recrystallization event at 1572 ± 7 Ma. Monazites from the granite gneiss samples also record a terminal metamorphic event at 1415 ± 23 Ma. Lu‐Hf isotopic analyses of zircons reveal fundamentally different source rock reservoirs for the protoliths of these magmatic rocks across the SMB. While the type TBG from the northern domain was derived from an Early Palaeoproterozoic source T(Hf) from 2093 to 2523 Ma, with a mean value at 2379 Ma) of essentially juvenile material with minor crustal components (εHf(t) from −3.3 to + 3.7), the granite from the southern domain had a mature crustal source (εHf(t) from −12.5 to −21.9) of Palaeoarchaean age T(Hf) from 3051 to 3630 Ma, with a mean value at 3218 Ma). When integrated with metamorphic information previously obtained from the 1.6 Ga ultra‐high temperature granulite facies metamorphic event in the SMB, the discrete magmatic and metamorphic events between 1.62/1.60 Ga and 1.42 Ga can be correlated with the formation of an Early Mesoproterozoic accretionary orogen in the CITZ. Copyright © 2011 John Wiley & Sons, Ltd.
Should Medicare adopt the Veterans health administration formulary?
Authors: Frakt Austin B. , Pizer Steven D. , Feldman Roger
Published: April 2011

Since January 2006 all Medicare beneficiaries have been eligible to obtain outpatient prescription drug coverage through private stand‐alone drug plans (PDPs). We estimate a model of beneficiary demand for PDPs and use it to compute the loss of consumer surplus due to tightening PDP formularies to the level found in the Veterans Health Administration (VA). Under a generous assumption of cost savings attributed to increased bargaining leverage associated with exclusion of more drugs from formularies, we find the loss in consumer surplus to be smaller than the financial savings that could be shared between Medicare and beneficiaries. According to our estimates, Medicare beneficiaries could be compensated for the loss in consumer surplus associated with tighter PDP formularies with the savings generated by such formularies. Copyright © 2011 John Wiley & Sons, Ltd.
Customization in prescribing for bipolar disorder
Authors: Hodgkin Dominic , Volpe‐Vartanian Joanna , Merrick Elizabeth L. , Horgan Constance M. , Nierenberg Andrew A. , Frank Richard G. , Lee Sue
Published: April 2011

For many disorders, patient heterogeneity requires physicians to customize their treatment to each patient's needs. We test for the existence of customization in physicians' prescribing for bipolar disorder, using data from a naturalistic clinical effectiveness trial of bipolar disorder treatment (STEP‐BD), which did not constrain physician prescribing. Multinomial logit is used to model the physician's choice among five combinations of drug classes. We find that our observed measure of the patient's clinical status played only a limited role in the choice among drug class combinations, even for conditions such as mania that are expected to affect class choice. However, treatment of a patient with given characteristics differed widely depending on which physician was seen. The explanatory power of the model was low. There was variation within each physician's prescribing, but the results do not suggest a high degree of customization in physicians' prescribing, based on our measure of clinical status. Copyright © 2011 John Wiley & Sons, Ltd.