bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the Relation between Amplification and Binding in Dynamic Combinatorial Libraries of Macrocyclic Synthetic Receptors in Water
Authors: Corbett Peter T. , Sanders Jeremy K. M. , Otto Sijbren
Published: December 2007

Herein we describe an extensive study of the response of a set of closely related dynamic combinatorial libraries (DCLs) of macrocyclic receptors to the introduction of a focused range of guest molecules. We have determined the amplification of two sets of diastereomeric receptors induced by a series of neutral and cationic guests, including biologically relevant compounds such as acetylcholine and morphine. The host–guest binding affinities were investigated using isothermal titration calorimetry. The resulting dataset enabled a detailed analysis of the relationship between the amplification of selected receptors and host–guest Gibbs binding energies, giving insight into the factors affecting the design, simulation and interpretation of DCL experiments. In particular, two questions were addressed: Is amplification by a given guest selective for the best receptor? And does the best guest induce the largest amplification of a given receptor? Our experimental results and computer simulations showed that the relative levels of amplification of hosts by a guest are well‐correlated with their relative affinities, and simulations have confirmed previous observations that amplification can be selective for the best receptor when only modest amounts of guest are used. In contrast, the correlation between guest binding and the extent of amplification of a given receptor across a wide range of guests tends to be poorer, because every guest has its own unique set of affinities for competing receptors in the DCL. This implies that the results of screening a DCL for selective receptors by comparing the response of the mixture to two different guests should be interpreted with caution. DCLs are complex mixtures in which all compounds are connected through a set of equilibria. Obtaining quantitative information about all host–guest binding constants from such systems will require the explicit and simultaneous consideration of all of the main equilibria within a DCL.
Enantioselective CC Bond Formation to Sulfonylimines through Use of the 2‐Pyridinesulfonyl Group as a Novel Stereocontroller
Authors: Nakamura Shuichi , Nakashima Hiroki , Sugimoto Hideki , Sano Hideaki , Hattori Masataka , Shibata Norio , Toru Takeshi
Published: December 2007

Enantioselective CC bond formation to 2‐pyridinesulfonylimines afforded products with good enantioselectivity. Dynamic induction of chirality on the sulfur by coordination of a chiral Lewis acid to the pyridine nitrogen and one of the prochiral sulfonyl oxygens induces enantioselectivity. Since the 2‐pyridinesulfonyl group can easily be removed after the reaction, it acts not only as an activating group but also as an efficient stereocontroller.
Excess Molar Volumes and Viscosities for Binary Mixtures of 1‐Alkoxypropan‐2‐ols with 1‐Butanol, and 2‐Butanol at 298.15 K and Atmospheric Pressure
Authors: PAL Amalendu , GABA Rekha
Published: December 2007

Excess molar volumes VmEand kinematic viscosities ν have been measured as a function of composition for binary mixtures of propylene glycol monomethyl ether (1‐methoxy‐2‐propanol), MeOCH2CH(OH)Me, propylene glycol monoethyl ether (1‐ethoxy‐2‐propanol), EtOCH2CH(OH)Me, propylene glycol monopropyl ether (1‐propoxy‐2‐propanol), PrOCH2CH(OH)Me, propylene glycol monobutyl ether (1‐butoxy‐2‐propanol), BuOCH2CH(OH)Me, and propylene glycol tert‐butyl ether (1‐tert‐butoxy‐2‐propanol), t‐BuOCH2CH(OH)Me with 1‐butanol, and 2‐butanol, at 298.15 K and atmospheric pressure. The excess molar volumes are negative across the entire range ofcomposition for all the systems with 1‐butanol, and positive for the systems 2‐butanol+1‐methoxy‐2‐propanol, and +1‐propoxy‐2‐propanol, negative for the systems 2‐butanol+1‐butoxy‐2‐propanol, and change sign for the systems 2‐butanol+1‐ethoxy‐2‐propanol, and +1‐tert‐butoxy‐2‐propanol. From the experimental data, the deviation in dynamic viscosity η from Δxiηi has been calculated. Both excess molar volumes and viscosity deviations have been correlated using a Redlich‐Kister type polynomial equation by the method of least‐squares for the estimation of the binary coefficients and the standard errors.
Distribution and Transfer of Gatifloxacin Between Two Microemulsion Phases with Different Structures in SDS/n‐C5H11OH/H2O System
Authors: CHEN Yuan , GUO Rong
Published: December 2007

At a weight ratio of n‐C5H11OH/H2O=50/50, when the total content of sodium dodecyl sulfate (SDS) was less than 6.0%, the ternary mixture of SDS/n‐C5H11OH/H2O coexisted in two immiscible microemulsions. The distribution and transfer of gatifloxacin (GTFX) between the two phases were studied using UV‐Vis and electrochemistry AC impedance spectra. The results show that GTFX transferred from the upper phase (W/O) to the lower phase (O/W or bicontinuous microemulsion), but a small amount of SDS transferred from the lower phase to the upper phase correspondingly with the increase of the total SDS content at a total GTFX concentration of 1.0×10−5 mol/L. The addition of GTFX did not change the structures of the two different phases fundamentally, but resulted in the transfer and redistribution of GTFX and SDS, so the electric properties of the system were changed correspondingly.
Microcalorimetric Investigation of Influence of Fungicide SYP‐L190 on Growth Metabolism of Tetrahymena thermophila and Bacillus thuringiensis
Authors: LI Hui‐Rong , KU Zong‐Jun , QIN Cai‐Qin , ZHANG Zhong‐Hai , LIU Yi
Published: December 2007

Flumorph (SYP‐L190) is a new systemic fungicide with good protective, curative and antisporulant activities but no phytotoxicity to certain plants. Its performance on the environmental ecosystem is unknown. Tetrahymena thermophila and Bacillus thuringiensis are two of biological indicators for the aquatic and soil environmental ecosystem respectively. Microcalorimetric technique based on the heat output was applied to evaluate the influence of fungicide flumorph (SYP‐L190) on the two microorganisms. The thermogenic curves and corresponding thermodynamic and thermokinetic parameters were obtained. SYP‐L190 at a concentration of 50–100 µg·mL−1 had 5% –10% inhibitory ratios aganist Tetrahymena thermophila and was used as a protection reagent, while at a concentration of 100–200 µg·mL−1 SYP‐L190 had 10% –20% inhibitory ratios and was used as a therapy reagent. The metabolic thermogenic curves of Bacillus thuringiensis contained bacterial growth phase and sporulation phase. The SYP‐L190 at a concentration of 0–200 µg·mL−1 had no influence on bacterial growth phase, but led to a little lag of the sporulation phase with a constant heat output. Hormesis was obviously observed in present study.
Synthesis and Kinetic Study on the Chromium(III) Complex [Cr(ASA)(en)2]Cl·2H2O
Authors: LIU Bin , YANG Bin‐Sheng
Published: December 2007

In order to explore the transfer mechanism of chromium(III) in mammals, a novel complex [Cr(ASA)(en)2]Cl· 2H2O, bis(ethylenediamine‐κ2 N,N′)(4‐aminosalicylic acid‐κ2 O,O′) chromium(III) monochloride dihydrate was synthesized (4‐aminosalicylic acid=H2ASA, ethylenediamine=en). The crystal structure belongs to orthorhombic system with the space group P212121 by means of X‐ray diffraction. The characteristic for transfer of Cr3+ from the compound to the low‐molecular‐mass chelator EDTA and the iron‐binding protein apoovotransferrin (apoOTf) was followed by UV‐visible (UV‐Vis) and fluorescence spectra in 0.01 mol·L−1 Hepes at pH 7.4. The second order rate constants were calculated. Those spectra in conjunction were used to obtain more accurate information about the interaction of chromium complex with apoOTf. The experimental results indicate that Cr3+ can be transferred from the complex to apoOTf with the retention of the 4‐aminosalicylic acid acting as a synergistic anion.
Synthesis, Characterization and Activity against Staphylococcus of Metal(II)‐Gatifloxacin Complexes
Authors: LI Ze‐Quan , WU Feng‐Jing , GONG Yun , HU Chang‐We , ZHANG Yun‐Huai , GAN Meng‐Yu
Published: December 2007

Three novel isostructural complexes M(gatx)2(H2O)2·4H2O [gatx=gatifloxacin, M=Zn (1), Ni (2) and Co (3)] were synthesized at room temperature and structurally characterized by elemental analysis, IR and single crystal X‐ray diffraction, which exhibit a similar mononuclear structure, in which the metal ion is coordinated by two gatifloxacin and two aqua ligands to furnish a distorted octahedral geometry, and show different activities against staphylococcus due to the different metal ions in the structures.
Study on the Complexation of Molybdenum(VI) with Iminodiacetic Acid and Ethylenediamine‐N,N′‐diacetic Acid by Specific Ion Interaction and Debye‐Hückel Theories
Authors: MAJLESI Kavosh , REZAIENEJAD Saghar
Published: December 2007

Complexation of two ligands, iminodiacetic acid and ethylenediamine‐N,N′‐diacetic acid, with molybdenum(VI) was studied in aqueous solutions. Molybdenum(VI) forms a mononuclear complex with the aforementioned ligands of the type MoO3L2−. All measurements have been carried out at 25 °C and different ionic strengths ranging from 0.1 to 1.0 mol·L−1 of NaClO4, with the pH justified to 6.0. Equilibrium concentration products and stoichiometry of the complexes have been determined from a combination of potentiometric and UV spectroscopic measurements. Comparison of the ionic strength effect on these complex formation reactions has been made using a Debye‐Hückel type equation and Bronsted‐Guggenheim‐Scatchard specific ion interaction theory (SIT). Debye‐Hückel theory predicted the first order effects on simple electrolyte solutions. Interactions between the reacting species and the ionic medium were taken into account in the SIT model. All of the calculations have been done by the computer program Excel 2000.
Unprecedented 1D Mixed‐metal Polynuclear Cyclometalated Platinum Complexes: Synthesis, Structural Characterization and Spectroscopic Properties
Authors: CAO Qian‐Yong , GAN Xin , ZHANG Jun‐Feng , CHI Shao‐Ming , LI Hui‐Fangjie , FU Wen‐Fu
Published: December 2007

The complexes [Pt2L2(μ‐dppm)](ClO4)2 (1) and {[Pt2L2(μ‐dppm)Li(CH3CN)2](ClO4)3}n (2), where HL is 6‐[4‐(diethoxyphosphorylmethyl)phenyl]‐2,2′‐bipyridinyl and dppm is bis(diphenylphosphino)methane, have been synthesized and characterized. In complex 1 the platinum(II) center adopts a distorted square planar coordination geometry. The polymer 2 exhibits a "stairstep" configuration with one‐dimensional Pt(II)NˆNˆCPO‐ Li(I)‐OPCˆNˆNPt(II) mixed‐metal units which are linked through dppm. Both complexes have metal‐metal interaction with Pt–Pt distances of 3.325(2) and 3.1432(9) Å, respectively, and display strong metal‐metal‐to‐ligand charge‐transfer (MMLCT) triplet state emission. The density‐functional‐theory calculation was used to interpret the absorption spectra of the complexes.
Development and Validation of Spectrophotometric Methods for the Determination of Cefetamet in Pharmaceutical Dosage Forms
Authors: HIREMATH Basavaraj , MRUTHYUNJAYASWAMY Bennikallu Hire Mathada
Published: December 2007

Two simple and sensitive spectrophotometric methods for the determination of cefetamet in either pure form or in its pharmaceutical formulations were described. The method I is based on the interaction of 3‐methylbenzo[d]‐ thiazolin‐2‐one hydrazone (MBTH) with cefetamet in the presence of freshly prepared ferric chloride in a neutral medium. The resulting blue colored product has λmax at 628 nm. The method II describes the reduction of ferric ion by the drug to ferrous ion followed by a complex formation reaction with 1,10‐phenanthroline (1,10‐phen) to form an orange red colored chromogen exhibiting λmax at 510 nm. The products are stable for more than 5 and 8 h respectively. Common excipients used as additives in pharmaceutical preparations do not interfere in the proposed methods. Both methods are highly reproducible and have been applied to a wide variety of pharmaceutical preparations and the results are comparable with those of official methods.
Selective Detection of Mercury(II) and Copper(II) Based on the Opposite Size‐dependent Fluorescence Quenching of CdTe Quantum Dots
Authors: XIA Yun‐Sheng , CAO Chun , ZHU Chang‐Qing
Published: December 2007

Three different size CdTe quantum dots (QDs) capped by 3‐mercaptopropionic acid (MPA) have been prepared in aqueous solutions, and their interactions with Cu2+ and Hg2+ have been investigated. The opposite size‐dependent fluorescence quenching of CdTe QDs by Hg2+ and Cu2+ was observed: Hg2+ quenched smaller particles more efficiently than larger ones while larger particles were more markedly quenched by Cu2+. Based on the different size responses, Hg2+ and Cu2+ were respectively detected with high sensitivity and selectivity, for the first time, using the QDs with different sizes but the same components and capping ligands.
Solid Phase Extraction of Trace Copper(II) Using Octadecyl Silica Membrane Disks Modified with N,N′‐Disalicylideneethylenediamine
Authors: MOGHIMI Ali
Published: December 2007

ZY
Al2O3/SnO2 Co‐Nanoparticle Modified Grafted Collagen for Improving Thermal Stability and Infrared Emissivity
Authors: CAO Yong , ZHOU Yu‐Ming , SHAN Yun , JU Huang‐Xian , XUE Xue‐Jia
Published: December 2007

Al2O3/SnO2 co‐nanoparticles were prepared with a modified sol‐gel technique followed by a thermal treatment process. With these co‐nanoparticles the grafted collagen‐Al2O3/SnO2 nanocomposites were obtained using a supersonic dispersion method. X‐ray diffraction, FT‐IR analysis, transmission electron microscopy, TGA/DTA and infrared emissivity test were performed to characterize the resulting nanoparticles and nanocomposites, respectively. The Al2O3/SnO2 co‐nanoparticles showed a narrow distribution of size between 20–40 nm and could be uniformly absorbed on the tri‐helix scaffolds of the grafted collagen without any aggregation. The nanocomposites possessed better thermal stability and substantially lower infrared emissivity than the grafted collagen and Al2O3/SnO2 co‐nanoparticles with an increase of degradation temperature from 39 to 210 °C and a decrease of infrared emissivity from 0.850 of the grafted collagen and 0.708 of the Al2O3/SnO2 co‐nanoparticles to 0.424, which provided a potential application of the nanocomposites to areas such as photoelectronics.
Preconcentration and Determination of Chromium Species Using Octadecyl Silica Membrane Disks and Flame Atomic Absorption Spectrometry
Authors: MOGHIMI Ali , SABER‐TEHRANI Mohammad , WAQIF‐HUSAIN Syed , MOHAMMADHOSSEINI Majid
Published: December 2007

A novel and selective method for the fast determination of trace amounts of chromium species in water samples has been developed. The procedure is based on the selective formation of chromium diethyldithiocarbamate complexes at different pH in the presence of Mn(II) as an enhancement agent of chromium signals followed by elution with organic eluents and determination by atomic flame absorption spectrometry. The maximum capacity of the employed disks was found to be (396±3) µg and (376±2) µg for Cr(III) and Cr(VI), respectively. The detection limit of the proposed method is 49 and 43 ng·L−1 for Cr(III) and Cr(VI), respectively. The proposed method was successfully applied for determination of chromium species Cr(III) and Cr(VI) in different water samples.
A Concise and Convenient Synthesis of Stilbenes via Benzils and Arylmethyldiphenylphosphine Oxides
Authors: SUN Xun , ZHU Jun , ZHONG Chen , IZUMI Ken‐Ji , ZHANG Chen
Published: December 2007

A new and convenient synthetic method has been developed for the construction of stilbenes bearing electron‐withdrawing group(s) by using benzils and arylmethyldiphenylphosphine oxides via sequences involving Wittig‐Horner reaction and a rearrangement in the presence of t‐BuOK in toluene under mild conditions. This approach could be readily applied to a facile synthesis of biologically important natural products, resveratrol and its derivatives, such as trimethoxystilbenes 1 (Z) and 2 (E).
Synthesis of Some N‐Alkoxycarbonyl‐N′′‐benzoyl‐benzamidrazones(p‐toluamidrazones) and 1,3,5‐Trisubstituted 1,2,4‐Triazole Derivatives from N‐Benzoylimidates and their Antimicrobial and Anticancer Screening Studies
Authors: BEKIRCAN Olcay , KAHVECI Bahittin , OZGUMUS Osman Birol
Published: December 2007

Some new N‐alkoxycarbonyl‐N′′‐benzoyl‐benzamidrazones (p‐toluamidrazones) 3a–3d, and 1,3,5‐trisubstituted 1,2,4‐triazole 4a–4h derivatives by starting from N‐benzoylbenzimidates or N‐benzoyl‐p‐toluimidates. The structures of compounds 3 and 4 were established on the basis of elemental analyses, IR, 1H NMR, 13C NMR and UV data. Antimicrobial experiments of the compounds performed by using agar‐well diffusion and broth microdilution methods revealed that only compounds 3a–3d, 4a and 4b showed inhibitory effect only on Candida albicans ATCC 60193. However, compound 4b had also specific antibacterial activity against Staphylococcus aureus ATCC 25923. The other compounds showed neither antifungal nor antibacterial activities. Compounds 3a, 4a and 4b have been screened on three human tumor cell lines, breast cancer (MCF7), non small cell lung cancer (NCI‐H460), and CNS cancer (SF‐268) at the National Cancer Institute (NCI), USA, which were found to exhibit low antiproliferative activity.
Synthesis and Nonlinear Optical Properties of a New A‐π‐A Two‐Photon Compound Utilizing Dibenzothiophene as Center
Authors: ZHANG Xian , YU Xiao‐Qiang , YAO Jin‐Shui , JIANG Min‐Hua
Published: December 2007

A new two‐photon material, 3E,6E‐bis(2‐pyrid‐4′‐ylvinyl)dibenzothiophene (BPVDBT), has been firstly synthesized by an efficient Pd‐catalyzed Heck coupling route. The single‐ and two‐photon fluorescence, quantum yields, lifetimes, solvent effects of the chromophore were studied in detail and the compound exhibited solvent‐sensitivity. The fluorescence intensity (Iout) and input excitation intensity (Iin) can fit in well with the quadratic parabolas, which indicates that the up‐converted fluorescence was induced by the two‐photon absorption (TPA). TPA cross‐section of BPVDBT has been measured using the two‐photon‐induced fluorescence method, whose value is 14.24×10−50 cm4·s·photon−1·molecule−1 at 750 nm. The experimental results confirm that BPVDBT is a good two‐photon absorbing chromophore with an A‐π‐A type.
Synthesis of Certain 3‐Aminopyrazolo[5,4‐b]pyridine and 3,4‐Substituted Pyrido[2′,3′ :3,4]pyrazolo[5,1‐c][1,2,4]triazine Derivatives
Authors: EL‐LOUH Ali Khader Khalil , ABUNADA Nada Mohamed , EL‐SHOUBAKI Mohamed
Published: December 2007

2‐Thioxo‐1,2‐dihydropyridine derivatives 2a, 2b were reacted with methyl iodide to give 2‐methylthiopyridines 3a, 3b, which were reacted with hydrazine hydrate to produce 3‐aminopyrazolo[5,4‐b]pyridines 4a, 4b. Compounds 4a, 4b were diazotized to afford the corresponding diazonium salts 5a, 5b, which were reacted with some active methylene compounds 6a–6h to give the corresponding pyrido[2′,3′:3,4]pyrazole[5,1‐c][1,2,4]triazines 7–14.
Studies on the Refolding of Egg White Lysozyme Denatured by Urea Using "Phase Diagram" Method of Fluorescence
Authors: BIAN Liu‐Jiao , DONG Fa‐Xin , LIANG Chang‐Li , YANG Xiao‐Yan , LIU Li
Published: December 2007

The refolding of reduced and non‐reducing egg white lysozymes in a urea solution was studied by a "phase diagram" method of fluorescence. The result showed that in the refolding of the reduced egg white lysozyme, an intermediate state of an egg white lysozyme exists at the urea concentrations in a final renaturation solution being about 4.5 mol/L, their refolding follows a three‐state model; while in the refolding of the non‐reducing egg white lysozyme, two intermediate states exist at the urea concentrations being separately 4.0 and 2.5 mol/L, and their refolding follows a four‐state model. Through the comparison between the unfolding and refolding of an egg white lysozyme in the urea solution, it was found that both of the refolding of reduced and non‐reducing egg white lysozyme molecules was irreversible to their unfolding in the urea solution. Finally, a suggested refolding was separately presented for the reduced and non‐reducing egg white lysozymes in the urea solution.
The Pharmacophore Hypothesis of Novel Inhibitors for Aurora A Kinase
Authors: WANG Xiao‐Jian , CHEN Ya‐Dong , YANG Qian , YOU Qi‐Dong
Published: December 2007

A three‐dimensional pharmacophore model was developed from a series of inhibitors of Aurora A kinase to discover new potent anti‐cancer agents using the HypoGen module in the Catalyst software. The pharmacophore model was developed based on the structure of 20 currently available inhibitors, which were carefully selected from the literature. The best hypothesis (Hypo l) was defined by four features: one hydrogen‐bond donor and three hydrophobic points, with the best correlation coefficient of 0.909, the lowest rms deviation of 1.563, and the highest cost difference of 99.075. The Hypo 1 was then validated by a test set consisting of 24 compounds and by a cross‐validation of 95% confidence level through randomizing the data using the CatScramble program, which suggested that a predictive pharmacophore model had been successfully obtained.
Reaction of 3‐Thioformylindolizines with Tributylphosphine
Authors: LIU Wei‐Wei , LI Na , ZHAO Yue‐Qiang , TANG Li‐Juan , HU Hong‐Wen
Published: December 2007

2‐Phenyl‐3‐thioformylindolizine and 1,2‐dimethyl‐3‐thioformylindolizine undergo a novel desulfur coupling reaction in the presence of tributylphosphine to give (E)‐1,2‐bis(3‐indolizinyl)ethenes in high yields. The structures of products were confirmed by IR, 1H NMR, MS, elemental analysis and single crystal X‐ray diffraction analysis. The mechanisms involved in various stages of the reaction were discussed.
A Novel Stereoselective Synthesis of (1Z,3E)‐2‐Phenyl(or p‐Tolyl)sulfonyl‐substituted 1,3‐Dienes via Palladium Catalyzed Cross‐coupling Reactions of (E)‐α‐Iodovinyl Sulfones
Authors: HU Rong‐Hua , CHEN Gui‐Qin , CAI Ming‐Zhong
Published: December 2007

(E)‐α‐Stannylvinyl phenyl(or p‐tolyl)sulfones underwent an iododestannylation reaction to afford (E)‐α‐iodovinyl phenyl(or p‐tolyl)sulfones 1, which reacted with (E)‐alkenylzirconium(IV) complexes 2 produced in situ by hydrozirconation of terminal alkynes in the presence of a Pd(PPh3)4 catalyst to afford stereoselectively (1Z,3E)‐2‐ phenyl(or p‐tolyl)sulfonyl‐substituted 1,3‐dienes 3 in good yields.
A Multidisciplinary Approach for the Identification of Novel HIV‐1 Non‐Nucleoside Reverse Transcriptase Inhibitors: S‐DABOCs and DAVPs
Authors: Radi Marco , Falciani Chiara , Contemori Lorenzo , Petricci Elena , Maga Giovanni , Samuele Alberta , Zanoli Samantha , Terrazas Montserrat , Castria Marinunzia , Togninelli Andrea , Esté José A. , Clotet‐Codina Imma , Armand‐Ugón Mercedes , Botta Maurizio
Published: December 2007

Among the FDA approved drugs for the treatment of AIDS, non‐nucleoside reverse transcriptase inhibitors (NNRTIs) are essential components of first‐line anti‐HIV‐1 therapy because of the less‐severe adverse effects associated with NNRTIs administration in comparison to therapies based on other anti‐HIV‐1 agents. In this contest, 3,4‐dihydro‐2‐alkoxy‐6‐benzyl‐4‐oxypyrimidines (DABOs) have been the object of many studies aimed at identifying novel analogues endowed with potent inhibitory activity towards HIV‐1 wild type and especially drug‐resistant mutants. Accordingly, based on the encouraging results obtained from the biological screening of our internal collection of S‐DABO derivatives, we started with the systematic functionalization of the pyrimidine scaffold to identify the minimal required structural features for RT inhibition. Herein, we describe how the combination of synthetic, biological, and molecular modeling studies led to the identification of two novel subclasses of S‐DABO analogues: S‐DABO cytosine analogues (S‐DABOCs) and 4‐dimethyamino‐6‐vinylpyrimidines (DAVPs).
Modeling and Selection of Flexible Proteins for Structure‐Based Drug Design: Backbone and Side Chain Movements in p38 MAPK
Authors: Subramanian Jyothi , Sharma Somesh , B‐Rao Chandrika
Published: December 2007

Receptor rearrangement upon ligand binding (induced fit) is a major stumbling block in docking and virtual screening. Even though numerous studies have stressed the importance of including protein flexibility in ligand docking, currently available methods provide only a partial solution to the problem. Most of these methods, being computer intensive, are often impractical to use in actual drug discovery settings. We had earlier shown that ligand‐induced receptor side‐chain conformational changes could be modeled statistically using data on known receptor–ligand complexes. In this paper, we show that a similar approach can be used to model more complex changes like backbone flips and loop movements. We have used p38 MAPK as a test case and have shown that a few simple structural features of ligands are sufficient to predict the induced variation in receptor conformations. Rigorous validation, both by internal resampling methods and on an external test set, corroborates this finding and demonstrates the robustness of the models. We have also compared our results with those from an earlier molecular dynamics simulation study on DFG loop conformations of p38 MAPK, and found that the results matched in the two cases. Our statistical approach enables one to predict the final ligand‐induced conformation of the active site of a protein, based on a few ligand properties, prior to docking the ligand. We can do this without having to trace the step‐by‐step process by which this state is arrived at (as in molecular dynamics simulations), thereby drastically reducing computational effort.
Esthetic decision‐making: How do people select colours for real settings?
Authors: de Destefani Lucila R. Geymonat , Whitfield T. W. Allan
Published: December 2007

A feature of the empirical literature in colour psychology is that little attention has been given to how people in real settings engage in colour selection. Surprisingly, with rare exceptions, we know almost nothing about this. Besides its theoretical significance within psychology, this question has practical implications for industries where colour choice is important. A study is reported into that most ubiquitous of activities, selecting a paint colour for the home. This used a retrospective method supported by qualitative data analysis (NVivo) in which participants described their process of colour selection. The results indicate a process that is far from uniform, but one that consists of two essential stages. The first involves arriving at what we refer to as an affective specification of the qualities sought. Once constructed, this leads to the second stage of matching colour attributes to that specification. Selecting a wall colour emerges as a surprisingly complex process, and one that corresponds more closely to a search than to a simple affective choice. A parallel is drawn with decision research, particularly the field of naturalistic decision‐making. From participants' reports, colour selection also emerges as a process that women appear to understand better than men. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 55–60, 2008
Using symmetry to understand the attributes of color
Authors: Adams Louis W.
Published: December 2007

The common attributes of color are distinguishable by their symmetries. Hue, saturation, chroma, chromaticness, whiteness, and blackness symmetries are discussed. Symmetries are generally not sufficient to specify unique formulas for color attributes, nor are they an endorsement of color model accuracy. However, symmetries do provide constraints for valid formulae, which are useful even when symmetries are only approximate. They also provide an alternate conceptual understanding of color attributes that differs from standard color science definitions. Symmetries provide a simplified framework for calculating groups of colors that share color attributes. Color models examined include the Hunt Model, a simple color model (SCM), various CIE color spaces, and IPT. A general functional form describes symmetries and scaling laws for many color models, and exceptions are discussed. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 27–44, 2008
Research on the location characters of urban color plan in China
Authors: Gou Aiping , Wang Jiangbo
Published: December 2007

“Urban color” has gradually become one of the hot topics in the field of urban planning in China, and many cities have done research and developed planning practices. On the basis of the comparisons of those cities, numbers and figures show that most of them locate in the eastern part of China. Through the introduction of the Chinese urban planning system and implementation procedure, the authors indicate the status of the urban color plan and analyze the maneuverability of items on color in related laws and regulations. Next, we discuss the reasons of the distribution character with the examples of urban color plan of Yiyuan and architectural façade rebuilt of Guidu Holiday Inn in Suzhou. Finally, the authors point out that under the present Chinese system, urban color planning is the result of the game between urban planners and architects who come out from the rapid boom of urban construction and economy development. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 68–76, 2008
The Particle‐In‐Cell Method
Authors: Tskhakaya D. , Matyash K. , Schneider R. , Taccogna F.
Published: December 2007

This paper is the first in a series of three papers to summarize the recent work of an European‐wide collaborationwhich is ongoing since about one decade using Particle‐in‐Cell (PIC) methods in low temperature plasma physics. In the present first paper the main aspects of this computational technique will be presented. In the second paper, an overview of applications in low‐temperature plasma modelling will be given, whereas the third part will put emphasis on the specific results of modelling ion thrusters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Particle in Cell Simulation of Low Temperature Laboratory Plasmas
Authors: Matyash K. , Schneider R. , Taccogna F. , Hatayama A. , Longo S. , Capitelli M. , Tskhakaya D. , Bronold F. X.
Published: December 2007

Several applications of PIC simulations for understanding basic physics phenomena in low‐temperature plasmas are presented: capacitive radiofrequency discharges in Oxygen, dusty plasmas and negative ion sources for heating of fusion plasmas. The analysis of these systems based on their microscopic properties as accessible with PIC gives improved insight into their complex behavior. These studies are results of joint efforts over about one decade of research groups from Greifswald University, Germany; Bari University, Italy; Keio University, Japan and Innsbruck University, Austria. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simple Analytical Model of the Anodic Streamer
Authors: Amir‐Aid D. , Harrache Z. , Belasri A.
Published: December 2007

In this work, an analytical model is used to study the formation of the anodic streamer in high pressure electrical discharge. This model enabled us to see the space variations of the characteristics of the streamer such as the electric field and the propagation velocity of streamer. The validity of the analytic approach is demonstrated by comparing the model results to the data from the literature. A qualitative concord was found. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Chemokine receptor 4 (CXCR4) is part of the lipopolysaccharide “sensing apparatus”
Authors: Triantafilou Martha , Lepper Philipp M. , Briault Caspar David , Ahmed Mohamed Abd Elrahman , Dmochowski Josh M. , Schumann Christian , Triantafilou Kathy
Published: December 2007

Recognition of bacterial lipopolysaccharide (LPS) by the innate immune system involves at least three receptor molecules: CD14, TLR4 and MD‐2. Additional receptor components such as heat shock proteins, chemokine receptor 4 (CXCR4), or CD55 have been suggested to be part of this activation cluster; possibly acting as additional LPS transfer molecules. Our group has previously identified CXCR4 as a component of the “LPS‐sensing apparatus”. In this study we aimed to elucidate the role that CXCR4 plays in innate immune responses to LPS. Here we demonstrate that CXCR4 transfection results in responsiveness to LPS. Fluorescence correlation spectroscopy experiments further showed that LPS directly interacts with CXCR4. Our data suggest that CXCR4 is not only involved in LPS binding but is also responsible for triggering signalling, especially mitogen‐activated protein kinases in response to LPS. Finally, co‐clustering of CXCR4 with other LPS receptors seems to be crucial for LPS signalling, thus suggesting that CXCR4 is a functional part of the multimeric LPS “sensing apparatus”.
c‐FLIPS reduces activation of caspase and NF‐κB pathways and decreases T cell survival
Authors: Hinshaw‐Makepeace Jennifer , Huston Gail , Fortner Karen A. , Russell Jennifer Q. , Holoch Daniel , Swain Susan , Budd Ralph C.
Published: December 2007

Effective stimulation of NF‐κB in T cells following TCR ligation requires the activity of caspase‐8. The active caspase‐8 complex includes the paracaspase, MALT1, and Bcl‐10, which connect to the NF‐κB pathway. It has been less clear what regulates the level of caspase‐8 activity during T cell activation. A likely candidate is cellular FLIP (c‐FLIP), an enzymatically inert caspase‐8 homologue. Two alternatively spliced forms of c‐FLIP exist, a long form (c‐FLIPL) and a short‐form (c‐FLIPS). The latter lacks the C‐terminal caspase‐like domain. c‐FLIPL can heterodimerize with and activate caspase‐8 through an activation loop in the C terminus of c‐FLIPL. Here we show that, in contrast to c‐FLIPL, c‐FLIPS inhibits activation of caspase‐8 in T cells, and consequently reduces recruitment of MALT1 and Bcl‐10 to the active caspase complex. This results in reduced activity of NF‐κB. Consequently, T cells from c‐FLIPS‐transgenic mice undergo more rapid cell death both spontaneously and after activation. The findings suggest that c‐FLIPS functions to reduce the expansion of T cells during an immune response.
Efficient induction of mucosal and systemic immune responses by virus‐like particles administered intranasally: implications for vaccine design
Authors: Bessa Juliana , Schmitz Nicole , Hinton Heather J. , Schwarz Katrin , Jegerlehner Andrea , Bachmann Martin F.
Published: December 2007

Intranasal (i.n.) immunization aims to induce local as well as systemic immune responses. In the present study, we assessed a vaccine platform based on virus‐like particles (VLP) derived from the RNA phage Qβ for i.n. immunization. We found that both i.n. and subcutaneous (s.c.) administration of Qβ‐VLP elicited strong and comparable specific IgG responses in serum and lung. Surprisingly, both routes also induced high levels of specific IgA in serum. In contrast, only i.n. administration of Qβ‐VLP resulted in local IgA production in the lung. Efficient induction of B cell responses by i.n. administration of VLP was further supported by the presence of large numbers of germinal centers (GC) as well as memory B cells in the spleen and plasma cells in the bone marrow. Results obtained for the VLP itself could be extended to an antigen covalently attached to it. Specifically, i.n. immunization of mice with VLP displaying the influenza virus derived ectodomain of the M2 protein resulted in strong M2‐specific antibody responses as well as anti‐viral protection. In contrast, i.n. immunization with VLP displaying p33 peptide, the major CTL epitope of lymphocytic choriomeningitis virus, induced relatively inefficient cytotoxic T cell responses, resulting in low numbers of specific T cells and poor effector cell differentiation. Taken together, these results suggest that effective antibody‐based vaccines are achievable by i.n. administration of Qβ‐VLP displaying specific antigens.
Characterization of a subset of antigen‐specific human central memory CD4+ T lymphocytes producing effector cytokines
Authors: Stubbe Muriel , Vanderheyde Nathalie , Pircher Hanspeter , Goldman Michel , Marchant Arnaud
Published: December 2007

CCR7+ central memory (TCM) CD4+ T cells play a central role in long‐term immunological memory. Recent reports indicate that a proportion of CD4+ TCM is able to produce effector cytokines. The phenotype and the role of this subset remain unknown. We characterized cytokine‐producing human CD4+ TCM specific for cleared protein and persistent viral Ag. Our results demonstrate that the type of Ag stimulation is a major determinant of CD4+ TCM differentiation. CMV‐specific TCM were significantly more differentiated than protein Ag‐specific TCM and included higher proportions of IFN‐γ‐producing cells. The expression of killer cell lectin‐like receptor G1 (KLRG1) by protein Ag‐ and CMV‐specific TCM was associated with increased production of effector cytokines. KLRG1+ TCM expressed high levels of CD127, suggesting that they can survive long term under the influence of IL‐7. The induction of KLRG1+ TCM may therefore represent an important target of vaccination against pathogens controlled by cellular immune responses.

See accompanying commentary: http://dx.doi.org/10.1002/eji.200738044
Broad T cell immunity to the LcrV virulence protein is induced by targeted delivery to DEC‐205/CD205‐positive mouse dendritic cells
Authors: Do Yoonkyung , Park Chae Gyu , Kang Young‐Sun , Park Sung Ho , Lynch Rebecca M. , Lee Haekyung , Powell Bradford S. , Steinman Ralph M.
Published: December 2007

There is a need for a more efficient vaccine against the bacterium Yersinia pestis, the agent of pneumonic plague. The F1‐LcrV (F1‐V) subunit vaccine in alhydrogel is known to induce humoral immunity. In this study, we utilized DC to investigate cellular immunity. We genetically engineered the LcrV virulence protein into the anti‐DEC‐205/CD205 mAb and thereby targeted the conjugated protein directly to mouse DEC‐205+ DC in situ. We observed antigen‐specific CD4+ T cell immunity measured by intracellular staining for IFN‐γ in three different mouse strains (C57BL/6, BALB/c, and C3H/HeJ), while we could not observe such T cell responses with F1‐V vaccine in alhydrogel. Using a peptide library for LcrV protein, we identified two or more distinct CD4+ T cell mimetopes in each MHC haplotype, consistent with the induction of broad immunity. When compared to nontargeted standard protein vaccine, DC targeting greatly increased the efficiency for inducing IFN‐γ‐producing T cells. The targeted LcrV protein induced antibody responses to a similar extent as the F1‐V subunit vaccine, but Th1‐dependent IgG2a and IgG2c isotypes were observed only after anti‐DEC‐205:LcrV mAb immunization. This study sets the stage for the analysis of functional roles of IFN‐γ‐producing T cells in Y. pestis infection.
The strength of T cell stimulation determines IL‐7 responsiveness, secondary expansion, and lineage commitment of primed human CD4+IL‐7Rhi T cells
Authors: Lozza Laura , Rivino Laura , Guarda Greta , Jarrossay David , Rinaldi Andrea , Bertoni Francesco , Sallusto Federica , Lanzavecchia Antonio , Geginat Jens
Published: December 2007

Mouse memory T cell precursors express IL‐7 receptor‐α (IL‐7R), proliferate with homeostatic cytokines and undergo secondary expansions with antigen. Here, we analyzed how the strength of antigenic stimulation regulates IL‐7R expression, cytokine responsiveness and expansion potential of DC‐primed human CD4+ T cells. IL‐7R expression on proliferating T cells was highest at intermediate strength of stimulation, and purified CCR7+IL‐7Rhi and CCR7–IL‐7Rlo subsets had characteristics of memory and effector cells, respectively. However, CCR7+IL‐7Rhi cells generated under different priming conditions had strikingly different properties. Thus, increasing strength of stimulation promoted IL‐7 responsiveness that correlated with reduced phosphatase and tensin homologue deleted on chromosome 10 (PTEN) expression and enhanced s6 kinase activation, suggesting a tunable IL‐7R coupling to PI3 kinase‐dependent signaling pathways. Furthermore, functional and gene expression analysis revealed that intermediate‐stimulated CCR7+IL‐7Rhi cells were similar to non‐polarized central memory cells with high expansion potential. Conversely, high‐stimulated CCR7+IL‐7Rhi cells shared characteristics with circulating pre‐Th1 cells and differentiated spontaneously to Th1 effector cells. These results show that the strength of stimulation determines properties of activated IL‐7Rhi T cells, and suggest that memory T cell subsets could be derived from CCR7+ precursors that received different strengths of stimulation.

See accompanying commentary: http://dx.doi.org/10.1002/eji.200738044
Colloidal Strategies for Preparing Oxide‐Based Hybrid Nanocrystals
Authors: Casavola Marianna , Buonsanti Raffaella , Caputo Gianvito , Cozzoli Pantaleo Davide
Published: December 2007

Recent progress of colloidal chemistry in the synthesis of multimaterial nanostructures incorporating transition‐metal oxides is reviewed. Attention is focused on the emerging class of hybrid nanocrystals (HNCs), in which domains of different materials are interconnected through inorganic junctions in defined spatial arrangements. The level of expertise so far achieved in the preparation of single‐material NCs with finely tuned geometric parameters has been further extended into elegant “seeded growth” approaches for accessing elaborate HNCs by control of interfacial lattice strain and surface energy in liquid media. Various topological configurations are analyzed, including concentric core/shell architectures, hetero‐oligomers grouping spherical material domains and more asymmetric hybrid nanostructures based on rod‐shaped sections. The chemical‐physical properties and technological advantages offered by such multifunctional HNCs are also summarized.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Stearidonic acid (18:4n‐3): Metabolism, nutritional importance, medical uses and natural sources
Authors: Guil‐Guerrero José Luis
Published: December 2007

Stearidonic acid (SA, 18:4n‐3) is a polyunsaturated fatty acid (PUFA) that constitutes the first metabolite of α‐linolenic acid (ALA, 18:3n‐3) in the metabolic pathway leading to C20–22 PUFA, such as eicosapentaenoic acid (EPA, 20:5n‐3), and docosahexaenoic acid (DHA, 22:6n‐3), which recently have received much attention because of their various physiological functions in the human body. Recently, several studies indicated that dietary SA increased EPA more efficiently than ALA. Thus, vegetable oils containing SA may become a dietary source of n‐3 fatty acids that is more effective in increasing tissue n‐3 PUFA concentrations than the current ALA‐containing vegetable oils. Nevertheless, few SA sources occur in nature, although there are still a large number of species untested to date. SA has been detected in variable amounts in several species of algae, fungi and animals tissues, but the seeds of some plant families seem to be better sources of SA, especially Echium (Boraginaceae) species. This work reviews the nutritional significance, medical uses and natural occurrence of SA.
Domino Heck–Diels–Alder Reactions of Monosubstituted Bicyclopropylidenes
Authors: Yucel Baris , Noltemeyer Mathias , de Meijere Armin
Published: December 2007

A three‐component domino Heck–Diels–Alder reaction involving pinacol bicyclopropylideneboronate (8b), iodobenzene (9) and methyl acrylate (12) under Jeffery conditions [Pd(OAc)2, PPh3, K2CO3, Et4NCl, MeCN] produced a mixture of phenylspiro[2.5]octeneboronates syn/anti‐(E)‐14b and methyl phenylspirooctenecarboxylate 25 in 25 and 38 % yield, respectively. The major product 25 was most probably formed via the homoallylpalladium complex 23b undergoing deboropalladation rather than dehydropalladation. Similarly, reactions of tributylstannyl‐ and hydroxydimethylsilyl‐substituted bicyclopropylidenes 8c–d with 9 and tert‐butyl acrylate gave the tert‐butyl phenylspirooctenecarboxylate 26 via the diene 24 formed by demetallopalladation processes. The reaction of methyl 1,1′‐bicyclopropylidene‐2‐carboxylate (8e) with iodobenzene (9) in the presence of tert‐butyl acrylate (13) furnished a mixture of regioisomeric and diastereomeric spirooctenes syn/anti‐(E)‐15e and syn/anti‐(Z)‐15e in 69 and 6 % yield, respectively. The structures of the major pair of diastereomers syn‐(E)‐15e and anti‐(E)‐15e were rigorously proved by X‐ray crystal structure analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Optimal futures heading: Quadratic versus exponential utility functions
Authors: Lien Donald
Published: December 2007

Although quadratic and exponential utility functions both lead to mean‐variance expected utility analysis, this study demonstrates that the two approaches produce different optimal futures hedging decisions. Specifically, the deviation between the optimal production level and the optimal futures position is always smaller under the exponential utility framework. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28: 208–211, 2008
Interdealer inference and price discovery
Authors: Huang Tzu‐man , Locke Peter
Published: December 2007

Futures floor dealers are investigated in terms of their joint product of price discovery. A vector error correction model is estimated using floor trader proprietary prices, examining the resulting information shares and common factor components. More active dealers are significant price leaders, with only one fifth of the traders responsible for a significantly higher degree of price discovery. Price leadership is more significant in both volatile and falling markets, when information is perhaps more valuable. It is also found that the most active floor traders generally trade at the same time and in the same direction. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28: 131–154, 2008
Multi‐period hedge ratios for a multi‐asset portfolio when accounting for returns co‐movement
Authors: Fernandez Viviana
Published: December 2007

This study presents a model to select the optimal hedge ratios of a portfolio composed of an arbitrary number of commodities. In particular, returns dependency and heterogeneous investment horizons are accounted for by copulas and wavelets, respectively. A portfolio of London Metal Exchange metals is analyzed for the period July 1993–December 2005, and it is concluded that neglecting cross correlations leads to biased estimates of the optimal hedge ratios and the degree of hedge effectiveness. Furthermore, when compared with a multivariate‐GARCH specification, our methodology yields higher hedge effectiveness for the raw returns and their short‐term components. © 2008 Wiley Periodicals, Inc. Jrl Fut Mark 28:182–207, 2008