bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization and Delocalization of Spin Density in Mixed‐Valence (VIV/VV) [(V2O3)2(PhPO3)4⊂F]–n (n = 1, 2): Theoretical and Experimental Studies
Authors: Thong Nguyen Huu , Jabor Jabor K. , Stößer Reinhard , Meisel Manfred , Ziemer Burkhard
Published: June 2007

Based on XRD and optimized structures of the cage compound [(V2O3)2(PhPO3)4⊂F]–n in singlet (n = 1) and doublet (n = 2) states DFT calculations were carried out to determine the energies and spin density distribution for the symmetries D2d, C2v, and Cs. It turned out, that the cage with Cs symmetry not only represents the energetically more stable doublet system (with respect to D2d and C2v‐symmetries) but also corresponds to the real compound under study. The SOMO of the S = 1/2 cage represents an antibonding state and the volume of the cage in this state is larger than that in the S = 0 state. The calculated ESR hyperfine coupling constants are in acceptable agreement with those determined by ESR. Experimentally the localization/delocalization of spin density was determined via ESR as a function of temperature and adsorption of the cage on Al2O3, respectively. A proposal is given for the localization/delocalization of spin density based on thermally driven changes of the cage symmetry in combination with the hopping of the unpaired electron inside the cage.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
C–H···NiII Interaction‐Driven Homochiral M and P Helices of Neutral (R,R)‐ and (S,S)‐Bis(pyrrol‐2‐ylmethyleneamino)cyclohexane NiII Complexes
Authors: Shan Xu‐Feng , Wu Li‐Zhu , Liu Xian‐Yu , Zhang Li‐Ping , Tung Chen‐Ho
Published: June 2007

Reaction of (R,R)‐ and (S,S)‐bis(pyrrol‐2‐ylmethyleneamino)cyclohexane with NiII(OAc)2·4H2O afforded enantiomeric nickel(II) Schiff‐base complexes (R,R)‐1 and (S,S)‐1, respectively. Rare C–H···NiII interactions were found to be responsible for the facile formation of homochiral M and P helices of the neutral, chiral, mononuclear complexes in crystal lattices. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Crystallographic Characterisation of the Heterodimetallic Complex [(Dibenzo‐18‐crown‐6)K(μ‐Cl)3Ru(η6‐p‐cymene)]
Authors: Vock Carsten A. , Scopelliti Rosario , Dyson Paul J.
Published: June 2007

The triple‐chlorido‐bridged heterodimetallic dinuclear complex [(dibenzo‐18‐crown‐6)K(μ‐Cl)3Ru(η6‐p‐cymene)] containing an (η6‐arene)RuII fragment and a Group 1 metal crown ether fragment was synthesized and characterized by spectroscopy and X‐ray crystallography. The solid‐state structure clearly reveals the presence of the triple‐chlorido‐bridged dinuclear complex, whereas NMR investigations in different deuteriated solvents reveal the presence of an essentially 1:1 mixture of 1 and starting materials, indicating the presence of a dynamic equilibrium. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Reactions of Polynuclear Polyhydrido Rare Earth Metal Complexes Containing “(C5Me4SiMe3)LnH2” Units: A New Frontier in Rare Earth Metal Hydride Chemistry
Authors: Hou Zhaomin , Nishiura Masayoshi , Shima Takanori
Published: June 2007

The back cover picture shows the Ln4H8 core structure of the tetranuclear, rare earth metal, octahydride complexes [(C5Me4SiMe3)4Ln4H8(THF)n] (Ln = Sc, Y, Gd, Dy, Ho, Er, Tm, Lu; n = 0, 1, or 2). These hydride clusters exhibit extremely high and unique reactivity towards a variety of unsaturated substrates, which leads to the formation of a new family of polynuclear compounds. Details are discussed in the article by Z. Hou et al. on p. 2535 ff.
Transesterification of the crude Jatropha curcas L. oil catalyzed by micro‐NaOH in supercritical and subcritical methanol
Authors: Tang Zhiyong , Wang Lianyuan , Yang Jichu
Published: June 2007

Transesterification of the crude Jatropha curcas L. oil catalyzed by micro‐NaOH in supercritical/subcritical methanol was studied. The effects of various reaction variables such as the catalyst content, reaction temperature, reaction pressure and the molar ratio of methanol to oil on the conversion of crude Jatropha curcas L. oil to biodiesel were investigated. The results showed that even micro‐NaOH could noticeably improve this reaction. When NaOH was added from 0.2 to 0.5 to 0.8 wt‐‰ of triacylglycerols, the transesterification rate increased sharply; when the catalyst content was further increased, the reaction rate was just poorly improved. It was observed that increasing the reaction temperature had a favorable influence on the methyl ester yield. For the molar ratio ranging from 18 to 36, the higher the molar ratio of methanol to oil was charged, the faster the transesterification rate seemed. At the fixed stirring rate of 400 rpm, when the catalyst content, reaction temperature, reaction pressure and the molar ratio of methanol to oil were developed at 0.8 wt‐‰ NaOH, 523 K, 7.0 MPa and 24 : 1, respectively, the methyl ester yield could reach 90.5% within 28 min. Further, the kinetics of this reaction was involved and the results showed that it was a pseudo‐first‐order reaction whose apparent activation energy was 84.1 kJ/mol, and the pre‐exponential factor was 2.21×105.
Cascade Reactions of Me3Si‐Substituted Imidazolidine‐1,3‐Diols with PbO2, Including Oxidation of the Corresponding Diol and Subsequent Elimination of the Trimethylsilyl Fragment
Authors: Tretyakov Eugene , Romanenko Galina , Ikorskii Vladimir , Stass Dmitry , Vasiliev Vladimir , Demina Maria , Mareev Alexander , Medvedeva Alevtina , Gorelik Elena , Ovcharenko Victor
Published: June 2007

It was found that reactions of 2‐Me3Si‐R‐substituted (Si–Csp or Si–C) imidazolidine‐1,3‐diols with PbO2 in MeOH are cascade reactions, which involve the oxidation of imidazolidine‐1,3‐diols into nitronyl nitroxide (NN–R–SiMe3) and further elimination of the Me3Si group to give NN–R–H. The efficiency of a one‐pot approach in the synthesis of nitronyl nitroxides is demonstrated by reference to syntheses of2‐ethynyl‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (2), 2‐(4‐ethynylphenyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (8), (E)‐4,4,5,5‐tetramethyl‐2‐[2‐(pyrrolidin‐1‐yl)vinyl]‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (3a), (E)‐2‐[2‐(diisopropylamino)vinyl]‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (3b), and 4,4,5,5‐tetramethyl‐2‐(1H‐1,2,3‐triazol‐5‐yl)‐4,5‐dihydro‐1H‐imidazole‐3‐oxide‐1‐oxyl (H11). Interaction of 2 with secondary amines formed only trans isomers 3a and 3b. X‐ray investigation of 3a and 3b confirmed that the reaction is regiospecific. Static magnetochemical measurements detected weak exchange interactions between the odd electrons of the paramagnetic centers in the solid nitronyl nitroxide products, including H11 whose crystals consist of helices formed by numerous intermolecular H bonds. The ESR spectra of 3a, 3b, and H11 show substantial delocalization of spin density to the substituent. Modeling reproducibly gave equal hyperfine coupling constants (HFC) for the imidazoline nitrogen atoms of 3b and different HFC for the nitrogen atoms of 3a and H11, indicating that rotation of the two cyclic substituents is hindered. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Development of Ketoside‐Type Analogues of Trehalose by Using α‐Stereoselective O‐Glycosidation of Ketose
Authors: Namme Rie , Mitsugi Takashi , Takahashi Hideyo , Ikegami Shiro
Published: June 2007

The stereoselective synthesis of ketoside‐type analogues of trehalose is described. O‐Glycosidation of hept‐2‐ulopyranose with trimethylsilyl α‐pyranoside promoted by trimethylsilyl trifluoromethanesulfonate afforded α‐ketopyranosyl α‐aldopyranosides exclusively. α‐Ketopyranosyl β‐aldooyranosides and α‐ketopyranosyl α‐ketopyranosides were also synthesized in a similar manner. The benzyl protecting groups of the hydroxy moieties were removed by hydrogenolysis to afford fully deprotected trehalose analogues.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Practical Syntheses of Enantiomerically Pure N‐Acetylbenzhydrylamines
Authors: Castagnolo Daniele , Giorgi Gianluca , Spinosa Raffaella , Corelli Federico , Botta Maurizio
Published: June 2007

Two practical routes for the synthesis of benzhydrylamine derivatives in enantiomerically pure form have been developed. N‐Acetylbenzhydrylamines can be synthesised in few steps and good yields starting from 1‐aryl‐1‐propargylamines. The key steps are represented by the alkene‐alkyne cross metathesis reaction and alkyne–diene methylene‐free tandem‐metathesis reaction; these reactions have been performed under microwave irradiation in a few minutes and high yields. N‐Acetylbenzhydrylamines have been also converted in both enantiomers of the antifungal agent bifonazole, emphasizing the importance of these compounds as scaffolds for the synthesis of biologically active compounds in enatiopure form.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Convenient Synthesis of a [1‐14C]Diazirinylbenzoic Acid as a Photoaffinity Label for Binding Studies of V‐ATPase Inhibitors
Authors: Bender Tobias , Huss Markus , Wieczorek Helmut , Grond Stephanie , von Zezschwitz Paultheo
Published: June 2007

Diazirine‐tagged systems are considered reliable compounds for photoaffinity labeling (PAL) in biochemical studies as they enable investigation and understanding of biological mechanisms through covalent bonding to the target and subsequent detection. 14C‐labeled 4‐(3‐trifluoromethyl‐3H‐diazirin‐3‐yl)benzoic acid (11) was prepared by a lithium‐bromide exchange on the bis‐silylated 4‐bromophenyldiaziridine 19 with subsequent transformations with electrophiles as key steps of the synthesis. Using 14CO2, which was generated from rather inexpensive Ba14CO3, the desired diaziridinylbenzoic acid 21 was obtained in 78 % yield based on the employed radioactive material. Oxidation under mild conditions then yielded diazirine 11 in a 100 mg scale. This versatile photoaffinity label was selectively attached to the tetrahydropyrane ring of bafilomycin A1 (2) and concanamycin A‐derived 3, which both specifically inhibit the V‐ATPases. Inhibition assays were performed and revealed that the inhibitory capacities of the labeled derivatives are suitable for PAL studies on this important group of enzymes to elucidate the as yet unknown binding sites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Use of New Substituted 1,3,5‐Hexatrienes in Studying Thermally Induced 6π‐Electrocyclizations
Authors: Sünnemann Hans Wolf , Banwell Martin G. , de Meijere Armin
Published: June 2007

An acyclic, two heterocyclic, and two bicyclic alkenylstannanes, 3, 4a, 4b, 8 and 11, respectively, were synthesized in yields ranging from 43 to 97 %, and each was subjected to a sequence of Stille and Heck couplings with 2‐bromocyclohexenyl triflate (13) and alkyl (tert‐butyl and methyl) acrylate to furnish seven new 1,3,5‐hexatrienes 19, 20, 21, 22‐tBu, 22‐Me, 23 and 43, respectively, in 58–84 % yields. For the alkenylstannanes 4a,b, 8 and 11, customized combinations of catalysts had to be used. The Stille–Heck sequence involving 13, 3 and tert‐butyl acrylate could be performed in a one‐pot mode and proceeded in 75 % yield. The hexatrienes were heated in decalin solutions so as to effect 6π‐electrocyclization. Temperatures and reaction times were optimized individually. The hexatrienes 29, 31 and 36 gave the bi‐ and tricyclic cyclohexadienes 28, 30 and 34, incorporating allylic alcohol and allyl ether termini, by 6π‐electrocyclization and subsequent [1,5]‐hydrogen shift, as single products in good yields (85–93 %). In contrast, the hexatrienes 19, 20, 21 and 39 furnished mixtures of the initial electrocyclization products 26, 32, 37 and 40 as well as the products of a subsequent [1,5]‐hydrogen shift 27, 33, 38 and 41, respectively. The tricyclic hexatrienes 22‐tBu, 22‐Me and 23 bearing alkyl (tert‐butyl, methyl) acrylate termini also selectively gave the tetracyclic dienes 48‐tBu, 48‐Me and 50 in 71–77 % yields by electrocyclizations and subsequent hydrogen shifts.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Bromination and Iodination of 6H,12H‐5,11‐Methanodibenzo[b,f][1,5]diazocine: A Convenient Entry to Unsymmetrical Analogs of Tröger's Base
Authors: Didier Delphine , Sergeyev Sergey
Published: June 2007

6H,12H‐5,11‐Methanodibenzo[b,f][1,5]diazocine can easily be prepared from aniline and paraformaldehyde. Its reactions with either N‐bromosuccinimide (NBS) or with iodine monochloride (ICl) in the presence of a suitable activator smoothly afford 2‐bromo‐ and 2‐iodo‐ derivatives, respectively. The combination of these halogenation methods provides access to the 8‐bromo‐2‐iodo derivative, which is an interesting and otherwise inaccessible intermediate for the synthesis of unsymmetrical analogs of Tröger's base. The reported halogenations represent the first examples of electrophilic substitution in 6H,12H‐5,11‐methanodibenzo[b,f][1,5]diazocine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Hexaalkylguanidinium Trifluoromethanesulfonates – A General Synthesis from Tetraalkylureas and Triflic Anhydride, and Properties as Ionic Liquids
Authors: Kunkel Helene , Maas Gerhard
Published: June 2007

More than thirty hexaalkylguanidinium trifluoromethanesulfonates 12 were prepared from N,N‐diethyl‐N′,N′‐dimethylurea, N,N‐dibutyl‐N′,N′‐diethylurea, or tetrabutylurea, triflic anhydride, and a dialkylamine or cyclic sec‐amine in two steps. The combination of the urea and triflic anhydride first yields a bis(tetraalkylamidinio)ether bis(triflate) 10, which is then converted into a salt 12 by reaction with the amine component. The reaction sequence can also be carried out as a one‐pot procedure. Eighteen of the prepared guanidinium triflates 12 constitute room‐temperature ionic liquids, which were characterized for their melting point, glass transition temperature, viscosity, and refractive index. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Selective Synthesis of Unnatural α‐, β‐ and γ‐Amino Esters
Authors: Nugent Thomas C. , Ghosh Abhijit K.
Published: June 2007

Reductive amination of keto esters 1 with α‐methylbenzylamine (α‐MBA) in the presence of hydrogen and Raney‐Ni allows direct access to diastereomeric amino esters 2 in good to high de (72–94 %). For the α‐keto ester 1d and the β‐keto esters 1a, 1b and 1c the reaction is optimally performed in the presence of AcOH, while the γ‐keto ester 1h requires Ti(OiPr)4. The reductive amination product of 1d is an advanced homophenylalanine building block for Angiotensin Converting Enzyme (ACE) inhibitor drugs. The reductive amination product of 1h is converted in two additional steps to a protected chiral 2‐methylpyrrolidine 4h, which is an advanced amine intermediate for pharmaceutical drugs, e.g. ABT‐239. The strategy presented here obviates the need for preforming enamine or imine intermediates for amino ester synthesis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Cover Picture: Procedures for and Possible Mechanisms of Pd‐Catalyzed Allylations of Primary and Secondary Amines with Allylic Alcohols (Eur. J. Org. Chem. 19/2007)
Authors: Muzart Jacques
Published: June 2007

The cover picture shows the palladium‐catalyzed intermolecular reaction of allylic alcohols with amines. The advantages of this process are the easily available substrates, the high atom economy, and the formation of only water as the by‐product. Details of this reaction are presented in the Microreview by J. Muzart on p. 3077 f. The slides that form the frame of the scheme, with the French flag in the background, show the Champagne area and highlight the well‐known sparkling product of the region and the Reims cathedral. Emilie Thiery and Dr. Jean Le Bras are acknowledged for preparing the artwork for the cover picture.
Micellar Effects on the Reduction of 4‐Nitroimidazole Derivative: Detection and Quantification of the Nitroradical Anion
Authors: Jara‐Ulloa P. , Núñez‐Vergara L. J. , Squella J. A.
Published: June 2007

The reductive electrochemistry of 1‐methyl‐4‐nitro‐2‐hydroxymethylimidazole, a 4‐nitroimidazole derivative, was examined in the presence of surfactants anionic as sodium dodecyl sulfate (SDS), nonionic, Triton‐X, Cationic, Hyamine and Cetyl Trimethyl Ammonium Bromide (CTAB). The reductive mechanism of the nitroimidazole derivative was found to be dependent of both, nature and concentration of the surfactants.
The NADH Electrochemical Detection Performed at Carbon Nanofibers Modified Glassy Carbon Electrode
Authors: Arvinte Adina , Valentini Federica , Radoi Antonio , Arduini Fabiana , Tamburri E. , Rotariu Lucian , Palleschi Giuseppe , Bala Camelia
Published: June 2007

In this work, the capability of carbon nanofibers to be used for the design of catalytic electrochemical biosensors is demonstrated. The direct electrochemistry of NADH was studied at a glassy carbon electrode modified using carbon nanofibers. A decrease of the oxidation potential of NADH by more than 300 mV is observed in the case of the assembled carbon nanofiber‐glassy carbon electrode comparing with a bare glassy carbon electrode. The carbon nanofiber‐modified electrode exhibited a wide linear response range of 3×10−5 to 2.1×10−3 mol L−1 with a correlation coefficient of 0.997 for the detection of NADH, a high specific sensitivity of 3637.65 (μA/M cm2), a low detection of limit (LOD=3σ) of 11 μM, and a fast response time (3 s). These results have confirmed the fact that the carbon nanofibers represent a promising material to assemble electrochemical sensors and biosensors.
Microstructures by Selective Desorption of Self‐Assembled Monolayer from Polycrystalline Gold Electrodes
Authors: Strutwolf Jörg , O'Sullivan Ciara K.
Published: June 2007

Potential‐controlled partial reductive desorption of a self‐assembled monolayer of mercaptopropionic acid (MPA) formed on polycrystalline gold electrodes is used to expose subdomains of bare gold to the electrolyte solution. Two sets of cathodic waves are observed in the reduction scan with MPA self‐assembled on a polycrystalline gold electrode. The origin of the two waves is ambiguous but there are indications that the waves are correlated with reductive desorption from the (111) and then simultaneously (100) and (110) index faces of a polycrystalline gold electrode. Consecutive reduction scans with reversing the potential direction after the first peak (but before the onset of the second wave) results in disappearance of the first wave. The exposed domains are then blocked by an assembling process of longer chain alkanethiols to create a mixed self‐assembled monolayer on polycrystalline gold electrodes. Desorption of the remaining MPA creates a partially blocked electrode and the blocking behavior towards hexacyanoferrate(III) is analyzed using the theory of partially blocked electrodes and indicates an array of interacting centers. The approach of partial reductive desorption may be exploited for use in biosensing applications where the exposed gold domains could be used for anchoring of DNA probes.
Determination of Diclofenac in Urine Samples by Molecularly‐Imprinted Solid‐Phase Extraction and Adsorptive Differential Pulse Voltammetry
Authors: Fernández‐Llano Laura , Blanco‐López M. Carmen , Lobo‐Castañón M. Jesús , Miranda‐Ordieres Arturo J. , Tuñón‐Blanco Paulino
Published: June 2007

A molecularly imprinted polymer for diclofenac (DCF) was prepared by thermal polymerization over silica beads using 2‐(dimethylamino)ethyl‐methacrylate as functional monomer. After silica elimination by HF treatment, the polymer was applied to the selective solid‐phase extraction of the drug from urine followed by its quantification by adsorptive differential pulse voltammetry. Results indicate that the drug could be selectively extracted from the sample and quantified at clinically relevant concentrations (μg/mL).
Electrochemical Biosensing Platform Using Carbon Nanotube Activated Glassy Carbon Electrode
Authors: Zhang Renyun , Wang Xuemei , Chen Chen
Published: June 2007

Carbon nanotube enhanced electrochemically activated glassy carbon electrode (GCE) has been prepared and applied for sensitive electrochemical determination of DNA and DNA bases. The results indicate that the relative activation could efficiently enhance electron transfer at the pretreated GCE so that this carbon nanotube activated glassy carbon electrode could provide relatively low detection limit with good reproducibility for the respective biomolecular determination. Besides, greatly enhanced sensitivity could be obtained for the relevant electrochemical detection of the bio‐recognition process including DNA biosensing by using the carbon nanotube activated GCE. This approach provided a detection limit of 7.5 nM for guanine and 150 ng/mL for acid denatured DNA. These observations suggest that the carbon nanotube activated glassy carbon electrode could be utilized as a very sensitive and stable biosensor for some specific biological process.
CE analysis of the acidic organelles of a single cell
Authors: Chen Yun , Xiong Guohua , Arriaga Edgar A.
Published: June 2007

The properties of organelles within a cell have been shown to be highly heterogeneous. Until now, it has been unclear just how much of this heterogeneity is endemic to the organelle subpopulations themselves and how much is actually due to stochastic cellular noise. An attractive approach for investigating the origins of heterogeneity among the organelles of a single cell is CE with LIF detection (CE‐LIF). As a proof of principle, in this report we optimize and use a single cell CE‐LIF method to investigate the properties of endocytic (acidic) organelles. Our results show that the properties of individual acidic organelles containing Alexa Fluor® 488 Dextran suggest that there are two groups of CCRF‐CEM cells: a group with a high dextran content per cell, and a group with a low dextran content per cell. Furthermore, the individual organelle measurements of the single cells allow us to compare in each group the distributions of doxorubicin content per acidic organelle and electrophoretic mobilities of these organelles.
Investigation of β‐CD‐derivatized erythromycin as chiral selector in CE
Authors: Dai Rongji , Nie Xiaoying , Li Hong , Saeed M. Khalid , Deng Yulin , Yao Guowei
Published: June 2007

A novel water‐soluble β‐CD‐derivatized erythromycin (EM) was synthesized and used as an effective chiral selector for the resolution of chiral compounds in CZE. The purpose of substitution at the primary hydroxyl site of β‐CD with 1‐oxygen‐2,3‐epoxypropane is to produce a compound having functions of both β‐CD and EM. β‐CD‐derivatized EM exhibited excellent enantioselectivities compared with single β‐CD and EM for chiral separation in CE. We also investigated the influence of pH and concentration of BGE, concentration of chiral selector, applied potential, and organic modifier on chiral compounds' separation.
A novel LIF‐CE method for the separation of hyaluronan‐ and chondroitin sulfate‐derived disaccharides: Application to structural and quantitative analyses of human plasma low‐ and high‐charged chondroitin sulfate isomers
Authors: Zinellu Angelo , Pisanu Salvatore , Zinellu Elisabetta , Lepedda Antonio J. , Cherchi Gian Mario , Sotgia Salvatore , Carru Ciriaco , Deiana Luca , Formato Marilena
Published: June 2007

The report describes a rapid and simple CE method using LIF detection for the analysis of unsaturated disaccharides obtained from enzymatic depolymerization of plasma chondroitin sulfate (CS) isomers. The disaccharide reducing groups were labeled with 2‐aminoacridone (AMAC). The fluorotagged products can be separated by reversed‐polarity CE using a sodium acetate buffer, pH 3.8, in the presence of 0.05% methylcellulose. The choice of the appropriate electrophoretic conditions was performed after a deep analysis of the most important parameters affecting analyte separation. In particular, the effect of both run buffer concentration and pH on resolution, efficiency, migration times, and peak area was evaluated. The selected electrophoretic conditions allowed us to separate the CS isomers‐derived Δ‐disaccharides in less than 12 min, also resolving the nonsulfated disaccharides released from CS isomers from those released from hyaluronan (HA). Moreover, these conditions gave a good reproducibility of both the migration times (CV%, 0.25) and the peak areas (CV%, 1.4). Intra‐ and interassay CV were 5.37 and 7.23%, respectively, and analytical recovery was about 86%. The applicability of the above method to the quantitative and structural disaccharide analyses of plasma CS isomers was investigated. Data obtained from 44 healthy human subjects were compared with those obtained by a fluorophore‐assisted carbohydrate electrophoresis (FACE) reference assay, by using the Passing and Bablok regression and Bland–Altman tests. The developed method could represent a good tool for an ultrasensitive analysis of CS isomers in biological samples from different sources, particularly when samples are available in very low amounts.
Continuous‐flow single‐molecule CE with high detection efficiency
Authors: Schiro Perry G. , Kuyper Christopher L. , Chiu Daniel T.
Published: June 2007

This paper describes the use of two‐beam line‐confocal detection geometry for measuring the total mobility of individual molecules undergoing continuous‐flow CE separation. High‐sensitivity single‐molecule confocal detection is usually performed with a diffraction limited focal spot (∼500 nm in diameter), which necessitates the use of nanometer‐sized channels to ensure all molecules flow through the detection volume. To allow for the use of larger channels that are a few micrometers in width, we employed cylindrical optics to define a rectangular illumination area that is diffraction‐limited (∼500 nm) in width, but a few micrometers in length to match the width of the microchannel. We present detailed studies that compare the performance of this line‐confocal detection geometry with the more widely used point‐confocal geometry. Overall, we found line‐confocal detection to provide the highest combination of signal‐to‐background ratio and spatial detection efficiency when used with micrometer‐sized channels. For example, in a 2 μm wide channel we achieved a 94% overall detection efficiency for single Alexa488 dye molecules when a 2 μm×0.5 μm illumination area was used, but only 34% detection efficiency with a 0.5 μm‐diameter detection spot. To carry out continuous‐flow CE, we used two‐beam fluorescent cross‐correlation spectroscopy where the transit time of each molecule is determined by cross‐correlating the fluorescence registered by two spatially offset line‐confocal detectors. We successfully separated single molecules of FITC, FITC‐tagged glutamate, and FITC‐tagged glycine.
Off‐line integration of CE and MALDI‐MS using a closed–open–closed microchannel system
Authors: Jacksén Johan , Frisk Thomas , Redeby Theres , Parmar Varun , van der Wijngaart Wouter , Stemme Göran , Emmer Åsa
Published: June 2007

In this work, a new technique for off‐line hyphenation between CE and MALDI‐MS is presented. Two closed fused‐silica capillaries were connected via a silicon chip comprising an open microcanal. The EOF in the system was evaluated using mesityloxide or leucine‐enkephalin as a sample and with a running buffer that rendered the analyte neutrally charged. Comparison was made between the EOF in a closed system (first capillary solely included in the electrical circuit) and in a closed–open system (first capillary and microcanal included in the electrical circuit). It was concluded that the experimental values of the EOF agreed with the theory. The influence of the capillary outer diameter on the peak dispersion was investigated using a closed–open–closed system (first capillary, microcanal and second capillary included in the electrical circuit). It was clearly seen that a capillary with 375 μm od induced considerably higher peak dispersion than a 150 μm od capillary, due to a larger liquid dead volume in the connection between the first capillary outlet and the microcanal. Mass spectrometric analysis has also been performed following CE separation runs in a closed–open–closed system with cytochrome c and lysozyme as model proteins. It was demonstrated that a signal distribution profile of the separated analytes could be recorded over a 30 mm long microcanal.
Inelastic seismic response of stiffening systems and development of demand spectrum: Application to MSSS bridges
Authors: Saadeghvaziri M. Ala , Yazdani‐Motlagh A.
Published: June 2007

A stiffening system is a system that increases its stiffness as it goes under large displacements. Such behavioural characteristic can result from constitutive behaviour or at the structural level often from closure of gaps between various components (sub‐systems) of the structure. An example of the latter situation is multi‐span simply supported (MSSS) bridges under horizontal earthquake ground motion. Unlike softening systems, stiffening systems have not been studied. In addition to the need for more understanding of the seismic response of stiffening systems, there is a need to develop response spectrum that can be used in design. Several parameters
including gap size and ratios of sub‐systems stiffness, strength, and mass control the behaviour of a stiffening system. In this study, a simplified stiffening model is developed and over 367 000 cases are analysed to investigate the nonlinear stiffening behaviour and pounding. Parameters considered also include ground motion characteristic. Results are evaluated and compared in terms of displacement and dissipated hysteretic energy. Parameter study results show that, on average, the displacement response is lower for stiffening systems, however, they dissipates higher hysteretic energy, due to higher yield cycles and yield excursions, and can possibly sustain more damage than a bilinear, elastic–plastic system. Using parameter study database, design response spectrum for stiffening systems is also proposed and its practical application is demonstrated through its application to an MSSS bridge. Results of this study goes beyond MSSS bridges and will have application for many structural systems where response is characterized by a stiffening behaviour. Copyright © 2007 John Wiley & Sons, Ltd.
IGF‐1 protects oligodendrocyte progenitors against TNFα‐induced damage by activation of PI3K/Akt and interruption of the mitochondrial apoptotic pathway
Authors: Pang Yi , Zheng Baoying , Fan Lir‐Wan , Rhodes Philip G. , Cai Zhengwei
Published: June 2007

Proinflammatory cytokine‐mediated injury to oligodendrocyte progenitor cells (OPCs) has been proposed as a cause of periventricular leukomalacia (PVL), the most common brain injury found in preterm infants. Preventing death of OPCs is a potential strategy to prevent or treat PVL. In the current study, we utilized an in vitro cell culture system to investigate the effect of insulin‐like growth factor‐1 (IGF‐1) on tumor necrosis factor‐α (TNFα)‐induced OPC injury and the possible mechanisms involved. OPCs were isolated from neonatal rat optic nerves and cultured in chemically defined medium (CDM) supplemented with platelet‐derived growth factor and basic fibroblast growth factor. Exposure to TNFα resulted in death of OPCs. IGF‐1 protected OPCs from TNFα cytotoxicity in a dose‐dependent manner as measured by the XTT and TUNEL assays. IGF‐1 activates both the PI3K/Akt and the extracellular signal‐regulated kinase (ERK) pathway. However, IGF‐1‐enhanced cell survival signals were mediated by the PI3K/Akt, but not by the ERK pathway, as evidenced by the observation that IGF‐1‐enhanced cell survival was partially abrogated by Akti, the Akt inhibitor, or wortmannin, the PI3K inhibitor, but not by PD98059, the MAPK kinase/ERK kinase inhibitor. The downstream events of IGF‐1‐triggered survival signals included phosphorylation of BAD, blockade of TNFα‐induced translocation of Bax from the cytosol to the mitochondrial membrane, and suppression of caspase‐9 and caspase‐3 activation. These observations indicate that the protection of OPCs by IGF‐1 is mediated, at least partially, by interruption of the mitochondrial apoptotic pathway via activation of PI3K/Akt. © 2007 Wiley‐Liss, Inc.
The analysis of a cardiological network in a regulated setting: a spatial interaction approach
Authors: Lippi Bruni Matteo , Nobilio Lucia , Ugolini Cristina
Published: June 2007

We analyse referral patterns for patients undergoing percutaneous transluminal coronary angioplasty (PTCA) in the Emilia Romagna region of Italy, a procedure for which the assumption of a negative association between volume and adverse outcomes is used to justify its territorial concentration. Nevertheless, recent clinical evidence shows PTCA superiority for immediate treatment of acute myocardial infarction, which advises an increase in the number of points of delivery. Our paper aims to develop analytical tools designed to provide support to policy makers when they are asked to evaluate the spatial distribution of catheterisation laboratories that perform PTCA. Information is drawn from the regional administrative hospital discharge data (SDO) for the year 2002. We first use entropy indexes to investigate the spatial accessibility of the cardiological network. Secondly, by means of a gravity model estimated using Bayesian techniques we identify the determinants of patient flows in terms of demand and supply factors. Our results suggest that information on destinations is processed hierarchically and that agglomeration‐like forces are dominant. Furthermore, although self‐sufficiency of provision at the provincial level has been achieved to a large extent, there is still scope to improve the organisational efficiency of the network. Copyright © 2007 John Wiley & Sons, Ltd.
Exploring differences in empirical time preference rates for health: an application of meta‐regression
Authors: Asenso‐Boadi Francis , Peters Tim J. , Coast Joanna
Published: June 2007

Estimated time preference rates are extremely varied, with many rates being extremely high. Reviewing empirical studies without quantitative synthesis of their findings is largely unhelpful in determining how rates vary according to different factors. This study therefore explores the use of meta‐regression techniques to combine available evidence to draw reliable conclusions about the factors influencing empirical time preference rates. Papers reporting empirically derived time preference rates related to health and health‐care programmes were selected. Included were papers presenting all of: a mean time preference rate; information allowing derivation of standard errors; and one or more covariates. Appropriate data were derived from only eight of the 16 papers reporting empirical time preference rates. Meta‐regression indicated that there were statistically significant relationships between mean time preference rates and: (a) delay period on a log scale; (b) whether the outcome question related to a gain or a loss. There were a number of limitations related to the use of meta‐regression in this area, including difficulties in extracting appropriate data from the original studies, and the extent to which the original studies provide fully deliberated estimates of time preference. Copyright © 2007 John Wiley & Sons, Ltd.
The effect of terrace geology on ground‐water movement and on the interaction of ground water and surface water on a mountainside near Mirror Lake, New Hampshire, USA
Authors: Winter Thomas C. , Buso Donald C. , Shattuck Patricia C. , Harte Phillip T. , Vroblesky Donald A. , Goode Daniel J.
Published: June 2007

The west watershed of Mirror Lake in the White Mountains of New Hampshire contains several terraces that are at different altitudes and have different geologic compositions. The lowest terrace (FSE) has 5 m of sand overlying 9 m of till. The two next successively higher terraces (FS2 and FS1) consist entirely of sand and have maximum thicknesses of about 7 m. A fourth, and highest, terrace (FS3) lies in the north‐west watershed directly adjacent to the west watershed. This highest terrace has 2 m of sand overlying 8 m of till. All terraces overlie fractured crystalline bedrock. Numerical models of hypothetical settings simulating ground‐water flow in a mountainside indicated that the presence of a terrace can cause local ground‐water flow cells to develop, and that the flow patterns differ based on the geologic composition of the terrace. For example, more ground water moves from the bedrock to the glacial deposits beneath terraces consisting completely of sand than beneath terraces that have sand underlain by till. Field data from Mirror Lake watersheds corroborate the numerical experiments. The geology of the terraces also affects how the stream draining the west watershed interacts with ground water. The stream turns part way down the mountainside and passes between the two sand terraces, essentially transecting the movement of ground water down the valley side. Transects of water‐table wells were installed across the stream's riparian zone above, between, and below the sand terraces. Head data from these wells indicated that the stream gains ground water on both sides above and below the sand terraces. However, where it flows between the sand terraces the stream gains ground water on its uphill side and loses water on its downhill side. Biogeochemical processes in the riparian zone of the flow‐through reach have resulted in anoxic ground water beneath the lower sand terrace. Results of this study indicate that it is useful to understand patterns of ground‐water flow in order to fully understand the flow and chemical characteristics of both ground water and surface water in mountainous terrain. Copyright © 2007 John Wiley & Sons, Ltd.
The interactome of the histone gene regulatory factor HiNF‐P suggests novel cell cycle related roles in transcriptional control and RNA processing
Authors: Miele Angela , Medina Ricardo , van Wijnen Andre J. , Stein Gary S. , Stein Janet L.
Published: June 2007

HiNF‐P is a recently identified histone H4 subtype specific transcriptional regulator that associates with the conserved cell cycle control element in the proximal promoter regions of histone H4 genes. HiNF‐P interacts with the global histone gene regulator and direct cyclin E/CDK2 substrate p220NPAT to potently upregulate histone H4 gene transcription at the G1/S phase transition in response to cyclin E/CDK2 signaling. To gain insight into the function of HiNF‐P in a broader cellular context, we performed a yeast two‐hybrid screen to identify its novel interacting proteins. In this study, we detected 67 candidate HiNF‐P interacting proteins of varying cellular functions. We have identified multiple RNA associated proteins, including the splicing co‐factor SRm300. HiNF‐P and SRm300 interact in yeast two‐hybrid, co‐immunoprecipitation, and co‐immunofluorescence assays. Our screen also identified several gene regulators that associate with HiNF‐P including THAP7. HiNF‐P and THAP7 interact in mammalian cells and THAP7 abrogates HiNF‐P/p220 mediated activation of histone H4 gene transcription, consistent with its known role as a transcriptional repressor. Finally, we identified several proliferation related proteins including Ki‐67 and X transactivated protein 2 (XTP2) which may be functioning with HiNF‐P in cell cycle regulation. The HiNF‐P interactome indicates that HiNF‐P is a multifunctional gene regulator with a large functional network and roles beyond cell cycle‐dependent histone gene regulation. J. Cell. Biochem. 102: 136–148, 2007. © 2007 Wiley‐Liss, Inc.
Determination of the chromatin domain structure in arrayed repeat regions: Organization of the somatic 5S RNA domain during embryogenesis inXenopus laevis
Authors: Hair Alan , Vassetzky Yegor
Published: June 2007

The size of the DNA loop containing theXenopus laevissomatic 5S RNA gene cluster has been estimated using a simple, precise and sensitive method that we have developed for use on any tandemly arrayed DNA repeat region, and was found to increase during development We have found that after the mid‐blastula transition, when transcription is activated in the embryo, a subset of somatic 5S RNA genes becomes specifically associated with the nuclear matrix. This association correlates with the transcriptional activity of the 5S genes. J. Cell. Biochem. 102: 1140–1148, 2007. © 2007 Wiley‐Liss, Inc.
Regulation of arginase‐1 expression in macrophages by a protein kinase a type I and histone deacetylase dependent pathway
Authors: Haffner Ivonne , Teupser Daniel , Holdt Lesca M. , Ernst Jana , Burkhardt Ralph , Thiery Joachim
Published: June 2007

The aim of the current study was to investigate the cAMP‐dependent regulation of arginase‐1 (ARG1) expression in RAW‐macrophages. Basal ARG1 mRNA expression was low and increased upon incubation with the cAMP analogue Br‐cAMP. We used selective agonists of protein kinase A type I (PKAI), type II (PKAII) and exchange protein directly activated by cAMP (EPAC) to determine the pathway responsible for ARG1 expression. Activation of PKAI led to a significant up‐regulation of ARG1 mRNA expression and arginase enzyme activity. In contrast, neither activation of PKAII nor activation of EPAC affected ARG1 expression. In addition, it has been shown that histone deacetylase (HDAC) activity plays a critical role in cAMP‐dependent transcriptional regulation. Incubation with Br‐cAMP and the HDAC inhibitor trichostatin A (TSA) led to a concentration‐dependent suppression of ARG1 expression. These data indicate that cAMP‐dependent activation of ARG1 expression is mediated by PKAI and requires histone deacetylation. J. Cell. Biochem. 103: 520–527, 2008. © 2007 Wiley‐Liss, Inc.
Gene therapy: The first two decades and the current state‐of‐the‐art
Authors: Flotte Terence R.
Published: June 2007

The concept of gene therapy was envisioned soon after the emergence of restriction endonucleases and subcloning of mammalian genes in phage and plasmids. Over the ensuing decades, vectors were developed, including nonviral methods, integrating virus vectors (gammaretrovirus and lentivirus), and non‐integrating virus vectors (adenovirus, adeno‐associated virus, and herpes simplex virus vectors). Preclinical data demonstrated potential efficacy in a broad range of animal models of human diseases, but clinical efficacy in humans remained elusive in most cases, even after decades of experience in over 1000 trials. Adverse effects from gene therapy have been observed in some cases, often because of viral vectors retaining some of the pathogenic potential of the viruses upon which they are based. Later generation vectors have been developed in which the safety and/or the efficiency of gene transfer has been improved. Most recently this work has involved alterations of vector envelope or capsid proteins either by insertion of ligands to target specific receptors or by directed evolution. The disease targets for gene therapy are multiple, but the most promising data have come from monogenic disorders. As the number of potential targets for gene therapy continues to increase, and a substantial number of trials continue with both the standard and the later generation vector systems, it is hoped that a therapeutic niche for gene therapy will emerge in the coming decades. J. Cell. Physiol. 213: 301–305, 2007. © 2007 Wiley‐Liss, Inc.
Histochemical Demonstration of Two Subtypes of O‐linked Oligosaccharides in the Rat Gastric Glands
Authors: Gómez‐Santos Laura , Alonso Edurne , Ferrer Concepción , Zuasti Adelina , Sáez Francisco José , Madrid Juan Francisco
Published: June 2007

The gastric glands synthesize glycoproteins whose oligosaccharides are linked to the peptide core mainly by the O‐glycosidic bond, specifically removed by β‐elimination procedure. Our aim was to research the possibility of the existence of two subtypes of O‐linked oligosaccharides with a different behavior to the removal procedure. The lectins from peanut (PNA) and Maackia amurensis (MAA‐I) were histochemically used as markers of the O‐linked oligosaccharides. Sections were also pretreated with β‐elimination and/or peptide N‐Glycosidase F (PNGase‐F) for the specific removal of O‐ and N‐linked oligosaccharides, respectively. The lectin GNA, which mainly labels to N‐linked oligosaccharides, was used to test the correct working of PNGase‐F. To test the possibility that the β‐elimination treatment could remove the terminal sialic acid residues, the lectin LFA was used. The surface epithelium was negative to PNA, while it became strongly positive when β‐elimination was performed for 1 day. This staining was resistant to PNGase‐F, suggesting that PNA was labeling to O‐linked oligosaccharides. However, after β‐elimination for 5 days this staining is not observed. A similar pattern appeared with MAA‐I. We propose the existence of two subtypes of O‐linked oligosaccharides: labile and resistant. The labile O‐linked oligosaccharides are removed with β‐elimination for 1 day, unmasking the PNA‐positive oligosaccharides. These oligosaccharides are resistant O‐linked oligosaccharides because staining is abolished with longer treatment of β‐elimination. The results with MAA‐I also support this suggestion. In summary, the labile O‐linked oligosaccharides are removed with short treatment, while the resistant O‐linked oligosaccharides need a stronger procedure (for 5 days). Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Ontogenesis of the Thermogenic Center in Hornets
Authors: Ermakov Natalya Y. , Plotkin Marian , Volynchik Stanislav , Bergman David J. , Ishay Jacob S.
Published: June 2007

In the Oriental hornet, a thermogenic center is located in its prothorax. The present study attempted to elucidate the development of this organ with age, that is, by following the development of the thermogenic center in the hornet from its pupal stage until several days after eclosion of the imago. To this end, use was made of an infrared camera, with which pictures were taken of the prothorax in hornets at various ages, i.e., several days prior eclosion, 24 h after eclosion, and 48‐h posteclosion. The photographic findings established that prior to 48‐h posteclosion there was no thermally distinct region or spot in the prothorax, but at about 48 h, such a “hot spot,” namely, a point whose temperature is greater than that of the rest of the prothorax, does appear, and its appearance coincides with certain specific nest activities like warming of the pupae. Next, an attempt was made to transplant by allograft the region in the prothorax housing the hot spot. Accordingly, several pupae at 2 days prior to eclosion were subjected to the following procedure; their future prothoracic thermogenic center was excised and so also an equally sized piece of cuticle from the dorsal region of their abdomen, and the two now allografted in exchange, i.e., the piece from the prothorax replacing the abdominal piece and vice versa. The result of this exchange‐transplant was studied 48 h after eclosion of the operated hornets and showed disruption of heat formation in the prothoracic site coupled with nonappearance of a hot spot in the abdominal site. As for the functional, intact hot spot in the adult hornet, it is characterized by a high concentration of tracheae, with numerous mitochondria in between them that probably contribute to the heat generation. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.