bluuebunny/crossref_metadata_2025 huggingface dataset:
Toward the mechanism of dynamical couplings and translocation in hepatitis C virus NS3 helicase using elastic network model
Authors: Zheng Wenjun , Liao Jung‐Chi , Brooks Bernard R. , Doniach Sebastian
Published: March 2007

Hepatitis C virus NS3 helicase is an enzyme that unwinds double‐stranded polynucleotides in an ATP‐dependent reaction. It provides a promising target for small molecule therapeutic agents against hepatitis C. Design of such drugs requires a thorough understanding of the dynamical nature of the mechanochemical functioning of the helicase. Despite recent progress, the detailed mechanism of the coupling between ATPase activity and helicase activity remains unclear. Based on an elastic network model (ENM), we apply two computational analysis tools to probe the dynamical mechanism underlying the allosteric coupling between ATP binding and polynucleotide binding in this enzyme. The correlation analysis identifies a network of hot‐spot residues that dynamically couple the ATP‐binding site and the polynucleotide‐binding site. Several of these key residues have been found by mutational experiments as functionally important, while our analysis also reveals previously unexplored hot‐spot residues that are potential targets for future mutational studies. The conformational changes between different crystal structures of NS3 helicase are found to be dominated by the lowest frequency mode solved from the ENM. This mode corresponds to a hinge motion of the highly flexible domain 2. This motion simultaneously modulates the opening/closing of the domains 1–2 cleft where ATP binds, and the domains 2–3 cleft where the polynucleotide binds. Additionally, a small twisting motion of domain 1, observed in both mode 1 and the computed ATP binding induced conformational change, fine‐tunes the binding affinity of the domains 1–3 interface for the polynucleotide. The combination of these motions facilitates the translocation of a single‐stranded polynucleotide in an inchworm‐like manner. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Amino acid sequence autocorrelation vectors and bayesian‐regularized genetic neural networks for modeling protein conformational stability: Gene V protein mutants
Authors: Fernández Leyden , Caballero Julio , Abreu José Ignacio , Fernández Michael
Published: March 2007

Development of novel computational approaches for modeling protein properties from their primary structure is the main goal in applied proteomics. In this work, we reported the extension of the autocorrelation vector formalism to amino acid sequences for encoding protein structural information with modeling purposes. Amino acid sequence autocorrelation (AASA) vectors were calculated by measuring the autocorrelations at sequence lags ranging from 1 to 15 on the protein primary structure of 48 amino acid/residue properties selected from the AAindex data base. A total of 720 AASA descriptors were tested for building predictive models of the change of thermal unfolding Gibbs free energy change (ΔΔG) of gene V protein upon mutation. In this sense, ensembles of Bayesian‐regularized genetic neural networks (BRGNNs) were used for obtaining an optimum nonlinear model for the conformational stability. The ensemble predictor described about 88% and 66% variance of the data in training and test sets respectively. Furthermore, the optimum AASA vector subset not only helped to successfully model unfolding stability but also well distributed wild‐type and gene V protein mutants on a stability self‐organized map (SOM), when used for unsupervised training of competitive neurons. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Molecular simulations bring new insights into flavonoid/quercetinase interaction modes
Authors: Fiorucci Sébastien , Golebiowski Jérôme , Cabrol‐Bass Daniel , Antonczak Serge
Published: March 2007

Molecular dynamics simulations, using the AMBER force field, were performed to study Quercetin 2,3‐Dioxygenase enzyme (Quercetinase or 2,3QD). We have analyzed the structural modifications of the active site and of the linker region between the native enzyme and the enzyme‐substrate complex. New structural informations, such as an allosteric effect in the presence of the substrate, as well as description of the enzyme‐substrate interactions and values of binding free energies were brought out. All these results confirm the idea that the linker encloses the substrate in the active site and also enlighten the recognition role of the substrate B‐ring by the enzyme. Moreover, a specific interaction scheme has been proposed to explain the relative degradation rate of various flavonoid compounds under the oxygenolysis reaction catalyzed by the Quercetin 2,3‐Dioxygenase enzyme. Proteins 2007. © 2007 Wiley‐Liss, Inc.
The promise of insect genomics
Authors: Grimmelikhuijzen Cornelis JP , Cazzamali Giuseppe , Williamson Michael , Hauser Frank
Published: March 2007

Insects are the largest animal group in the world and are ecologically and economically extremely important. This importance of insects is reflected by the existence of currently 24 insect genome projects. Our perspective discusses the state‐of‐the‐art of these genome projects and the impacts that they have on basic insect science and pest control. Copyright © 2007 Society of Chemical Industry
Magnetic ordering of Mn and Ru in (La0.52Ba0.48) (Mn0.51Ru0.49)O3
Authors: Wu S. Y. , Li W.‐H. , Yang C. C. , Lynn J. W. , Liu R. S.
Published: March 2007

Neutron diffraction, dc magnetization, and ac magnetic susceptibility measurements have been performed to study the magnetic properties of perovskite (La0.52Ba0.48) (Mn0.51Ru0.49)O3. The compound crystallizes into a cubic Pm$ \bar 3 $m symmetry with a lattice constant of a = 3.9661(4) Å at room temperature. Two anomalies, at around 160 and 60 K, can clearly be seen in the ac susceptibility results, with the peak positions for both anomalies shifting to a higher temperature as a dc magnetic field is applied. Neutron magnetic diffraction measurements show that the anomalies that occur at high and low temperatures are associated, with the ferromagnetic ordering of the Mn and the Ru spins, respectively. The ordering temperatures for the Mn and Ru spins were found to be at TC (Mn) ≈ 195 K and TC (Ru) ≈ 80 K, with a saturated moment of 〈μz–Mn〉 = 2.21(5)μB for the Mn spins and 〈μz–Ru〉 = 1.00(5)μB for the Ru spins. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Order–disorder transitions of t2g‐orbitals of V3+ ions and incommensurate structural deformations in the metallic spinel CuV2S4
Authors: Hidaka M. , Tokiwa N. , Wijesundera R. P. , Awaka J. , Nagata S. , Park Young Jun , Lee Ki Bong
Published: March 2007

Structural transitions of the spinel CuV2S4 have been studied by means of X‐ray diffraction using synchrotron radiation. The temperature dependence of reflections forbidden in a cubic spinel structure of Fd3m suggests that there are order–disorder transitions of 3d2 (t2g) orbitals of V3+ ions at about 75 and 210 K. An incommensurate superlattice reflection of (2+3/4, 2, 2+3/4) shows the structural phase transition occurring at about 90 K, in addition to the superlattice structural modulation at about 30–35 and 55 K. A reduced wavevector q = (3/4–δ, 0, 3/4–δ) shows the temperature dependence of the δ value from 0.015 to –0.025. A lock‐in of δ = 0.0 and a crossover of the δ value occur in the region of 40 to 50 K. The incommensurate structural modulation along [110], [011], and [101] directions appearing below about 90 K affects a paramagnetic spin order of V3+ ions at about 30–35 and 55 K, in addition to the 90 K structural transition. The paramagnetic behavior is interpreted mainly by the structural deformation and the (dxy , dyz , dzx ) orbitals in the VS6 octahedral chains sited along [110], [011], and [101] directions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature dependent dielectric relaxation and electrical conductivity in single‐layer ZnO–Al2O3 nanocomposite thin films
Authors: Das Soumen , Chaudhuri Subhadra
Published: March 2007

Single‐layer ZnO–Al2O3 nanocomposite thin films with thickness approximately 119 nm, containing randomly dispersed nanocrystallites of ZnO in the Al2O3 matrix were prepared by sol gel technique. The relative molar concentration of ZnO was 20% in the matrix. The confined nanoparticles ZnO were investigated through ac impedance spectroscopy in the frequency range of 500 Hz to 5 MHz at 315 K, 325 K, 345 K, 355 K, 395 and 450 K. The dielectric relaxations in each case were found to be of Cole–Cole type. The thermally activated relaxation phenomenon was analysed with the help of an equivalent circuit which is proposed on the basis of the experimentally obtained complex capacitance and impedance spectral studies. The temperature dependent electrical conductivity was analysed on the basis of interstitial Zn ions and free electrons in the system. The defect concentration of the nanocomposite thin film was determined from the complex capacitance measurements. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction between edge dislocations and a circular hole with surface stress
Authors: Fang Q. H. , Li B. , Liu Y. W.
Published: March 2007

The problem of the interaction between several parallel edge dislocations and a circular nanosized hole with surface stress is investigated. The explicit solutions of stress fields and image forces exerted on edge dislocations are obtained by the use of the complex variable method. The influence of surface properties and the size of the hole on the glide/climb force is discussed. The results show that different surface properties may cause the glide/climb force to either increase or decrease, which implies that there exists a local softening or hardening at the surface of the hole for considering the surface effects. The effect of a nanosized hole and its surface properties on the image forces between two dislocations is also significant. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Field effect of carbon nanotubes with an ionomeric polymer
Authors: Levitsky Igor A. , Kolobov Igor G. , Euler William B.
Published: March 2007

Flexible field effect transistors based on a single walled carbon nanotube (SWNT) network and an ionomeric polymer (nafion) were obtained by spraying nanotubes onto the polymer film. The threshold gate voltage was extremely low, ∼1 V, which was surprising since the nafion layer was so thick, ∼180 μm. This was attributed to the electrolytic nature of nafion, which results in the existence of a screening layer at the polymer‐nanotube interface. FET hysteresis can be rationalized in terms of charge redistribution induced by mobile protons inside nafion clusters in proximity to the nanotube surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homoepitaxy of ZnO: from the substrates to doping
Authors: Neumann C. , Lautenschläger S. , Graubner S. , Sann J. , Volbers N. , Meyer B. K. , Bläsing J. , Krost A. , Bertram F. , Christen J.
Published: March 2007

We report on the homoepitaxial growth of ZnO thin films by chemical vapor deposition techniques. The preparation of the ZnO substrates after mechanical polishing employed a high temperature annealing step which produced atomically flat surfaces and removed all of the surface and subsurface damage. Two dimensional epitaxial growth was achieved without an additional buffer layer. The substrate had a rocking curve with a full width at half maximum of 27″ which can be compared with that of the film of 17″. The films had superior band edge luminescence as compared with the substrate for which the green luminescence band is dominating. The impurity content in the substrates especially Li is reduced by the high temperature annealing step and drops further close to the detection limit in the films. The low substrate temperatures around 660 °C allow for the incorporation of nitrogen on oxygen site as a shallow acceptor. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Non‐uniformity effects in CdZnTe coplanar‐grid detectors
Authors: Carini G. A. , Bolotnikov A. E. , Camarda G. C. , Wright G. W. , James R. B.
Published: March 2007

We discuss the findings from our studies of the performance of commercial coplanar‐grid CdZnTe detectors. The devices were investigated using a highly collimated X‐ray beam available at Brookhaven's National Synchrotron Light Source, and by applying pulse‐shape analysis to measure correlations between the signals read out from the devices. Although the operational principle of coplanar‐grid (CPG) detectors is well known, we found some important new details that help to better clarify the performance limitations of this type of device. The correlation plots we present can also be used as diagnostic tools to characterize the behavior of the CPG devices and to help to improve the designs of electrodes. This work illustrates the typical limitations related to the geometry of the contacts in CPG devices and how material non‐uniformities can amplify these problems. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Metal‐organic vapor phase epitaxy growth and crystallographic study of vanadium‐doped ZnSe
Authors: Tahashi Masahiro , Goto Hideo , Ido Toshiyuki
Published: March 2007

As a new diluted magnetic semiconductor, vanadium‐doped ZnSe is theoretically predicted to induce ferromagnetism above room temperature without carrier doping. Vanadium‐doped ZnSe was epitaxially grown on (100) GaAs substrate by metal‐organic vapor phase epitaxial method in an atmospheric pressure. The local structural of vanadium‐doped ZnSe crystal showed vanadium atoms in ZnSe crystal were substituted by the Se‐site and/or exist in interstitial sites so that ferromagnetism could not found in spite of vanadium doping. The influences of mol supply ratio of dimethyl Se to dimethyl Zn on crystallinity and growth rate were investigated in order to research the optimum vanadium‐doping condition. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical characterization of ZnO nanorods
Authors: Schlenker E. , Bakin A. , Postels B. , Mofor A. C. , Wehmann H.‐H. , Weimann T. , Hinze P. , Waag A.
Published: March 2007

Zinc oxide (ZnO) nanorods were grown by a wet chemical approach and by vapor phase transport. To explore the electrical properties of individual nanostructures current–voltage (I –V) characteristics were obtained by using an atomic force microscope (AFM) with a conductive tip or by detaching the nanorods from the growth substrate, transferring them to an isolating substrate and contacting them with evaporated Ti/Au electrodes patterned by electron‐beam lithography. The AFM‐approach only yields a Schottky diode behavior, while the Ti/Au forms ohmic contacts to the ZnO. For the latter method the obtained I –V curves reveal a resistivity of the nanorods in the order of 10–5 Ω cm which is unusually low for undoped ZnO. We therefore assume the existence of a highly conductive surface channel. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of growth temperature and oxygen pressure on the properties of heteroepitaxial ZnO thin films on sapphire (0001) substrates by pulsed laser deposition
Authors: Liu Chunli , Chang S. H. , Noh T. W. , Song J.‐H. , Xie J.
Published: March 2007

We report a systematic study on the effect of growth temperature and O2 pressure on the structural, optical, and electrical properties of heteroepitaxial ZnO thin films prepared by pulsed laser deposition on sapphire (0001) substrates. The combination of high growth temperature and low O2 pressure was found to improve the crystalline quality of initial heteroepitaxial ZnO films, which can be attributed to the enhanced surface migration of adatoms and thermal energy. The low‐temperature photoluminescence spectra from ZnO films were dominated by donor‐bound exciton emission with very weak deep level emission. The temperature dependent Hall measurement showed that the films are highly degenerated, mainly due to the high defect density near the interface region. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strong anharmonicity and phonon confinement on the lowest‐frequency Raman mode of nanocrystalline anatase TiO2
Authors: Gao Kun
Published: March 2007

We calculated and analyzed the effects of temperature and crystallite size on the Raman properties of nanocrystalline anatase TiO2 by using the related models mentioned previously [Tang and Herman, Phys. Rev. B 43, 2299 (1991); Richter et al., Solid State Commun. 39, 625 (1981)]. The temperature dependence of the Raman spectra of two different crystallite sizes of anatase TiO2 were obtained. Careful measurements of the frequency shifts of Raman modes were carried out at different temperatures. Through fitting the experimental data, pure‐volume and the pure‐temperature contributions to the frequency shifts of the lowest‐ and highest‐frequency Eg modes, respectively, have been calculated. The results indicated that strongly intrinsic anharmonicity arising from optical‐phonon couplings was the origin of hardening upon increasing temperature for the lowest‐frequency Raman mode. The phonon‐confinement effect on this mode was analyzed and anharmonic shifts of optical phonons with two different kinds of crystallite sizes were also compared. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weibull prediction of event times in clinical trials
Authors: Ying Gui‐shuang , Heitjan Daniel F.
Published: March 2007

In clinical trials with interim analyses planned at pre‐specified event counts, one may wish to predict the times of these landmark events as a tool for logistical planning. Currently available methods use either a parametric approach based on an exponential model for survival (Bagiella and Heitjan, Statistics in Medicine 2001; 20:2055) or a non‐parametric approach based on the Kaplan–Meier estimate (Ying et al., Clinical Trials 2004; 1:352). Ying et al. (2004) demonstrated the trade‐off between bias and variance in these models; the exponential method is highly efficient when its assumptions hold but potentially biased when they do not, whereas the non‐parametric method has minimal bias and is well calibrated under a range of survival models but typically gives wider prediction intervals and may fail to produce useful predictions early in the trial. As a potential compromise, we propose here to make predictions under a Weibull survival model. Computations are somewhat more difficult than with the simpler exponential model, but Monte Carlo studies show that predictions are robust under a broader range of assumptions. We demonstrate the method using data from a trial of immunotherapy for chronic granulomatous disease. Copyright © 2007 John Wiley & Sons, Ltd.
Semi‐geostrophic solutions for flow over a ridge
Authors: Cullen M. J. P.
Published: March 2007

An algorithm for solving the semi‐geostrophic (SG) equations using real physical variables in terrain‐following coordinates is developed and used to demonstrate the expected rate of convergence of solutions of the complete equations of motion to SG solutions as the Rossby number is reduced. The tests are carried out with significant orography in a vertical slice geometry. Two asymptotic limits are tested. The SG limit is singular in one of the limits and smooth in the other. The results show the validity of using the SG model for diagnostic purposes in appropriate regimes. They also expose a number of boundary condition and numerical issues, showing that comparison with rigorous error estimates is a useful way of validating numerical procedures. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd
Filtering properties of wavelets for local background‐error correlations
Authors: Pannekoucke Olivier , Berre Loïk , Desroziers Gerald
Published: March 2007

Background‐error covariances can be estimated from an ensemble of forecast differences. The finite size of the ensemble induces a sampling noise in the calculated statistics. It is shown formally that a wavelet diagonal approach amounts to locally averaging the correlations, and its ability to spatially filter this sampling noise is thus investigated experimentally.

This is first studied in a simple analytical one‐dimensional framework. The capacity of a wavelet diagonal approach to model the scale variations over the domain is illustrated. Moreover, the sampling noise appears to be better filtered than when only using a Schur filter, in particular for small ensembles.

The filtering properties are then illustrated for an ensemble of Météo‐France Arpège forecasts. This is done both for the ‘time‐averaged correlations’, and for the ‘correlations of the day’. It is shown that the wavelets are able to extract some length‐scale variations that are related to the meteorological situation. Copyright © 2007 Royal Meteorological Society
Background error statistics for aerosols
Authors: Benedetti Angela , Fisher Michael
Published: March 2007

As part of the European initiative for Global Monitoring for Environment and Security (GMES), the Global and regional Earth‐system Monitoring using Satellite and in situ data (GEMS) project has been funded to provide forecasts and analysis of atmospheric constituents such as aerosols, and greenhouse and reactive gases. In this context, the development of an aerosol analysis system based on a four‐dimensional variational (4D‐Var) assimilation was started in March 2005 at the European Centre for Medium‐Range Weather Forecasts (ECMWF). As part of the main building blocks of the system, an error background covariance matrix for aerosol mixing ratio was built based on background statistics constructed from aerosol forecasts. These statistics were generated from the differences between the 48‐hour and 24‐hour forecasts of aerosol mixing ratios for sea salt, desert dust and continental particulate, using the NMC method. This method has been widely used by many numerical weather prediction centres to build background error statistics for state variables. This is the first time, to our knowledge, that it has been applied to a novel variable such as an aerosol mixing ratio, in the context of a global model. Aerosol assimilation systems have been successfully run with either observationally‐derived or model‐prescribed error covariance matrices with pre‐assigned correlation lengths. In this study, the aerosol vertical and horizontal structures of these error correlations as derived with the aid of a state‐of‐the‐art model are investigated and discussed in depth. Successively these error correlations are modelled through a spectral/wavelet approach and used to construct a background error covariance matrix. Application of this background matrix in the context of a single observation 4D‐Var experiment produced successful preliminary analyses of the total aerosol mixing ratio. Copyright © 2007 Royal Meteorological Society
Mie simulations as an error source in mineral aerosol radiative forcing calculations
Authors: Kahnert M. , Nousiainen T. , Räisänen P.
Published: March 2007

The role of aerosols remains a major uncertainty for climate and climate change. For the direct radiative forcing by mineral aerosols, the uncertainty in the refractive index m has been regarded as the most important error source, while the impact of aerosol non‐sphericity has been considered a minor issue and is neglected in climate models. Here, the errors caused by the spherical particle approximation (SPA) are evaluated by comparing radiative fluxes based on (i) Mie simulations and (ii) laboratory measurements of aerosol optical properties. Furthermore, they are contrasted with the errors related to the uncertainty in the refractive index. These two error sources are found to be of comparable magnitude, although they are strongly dependent on optical depth, surface albedo, and particle size. Thus, our results provide evidence that, contrary to common beliefs, the use of spherical model particles in radiative transfer simulations is probably among the major sources of error in quantifying the climate forcing effect of mineral aerosols. This stems from misrepresentation of the scattering phase function and the asymmetry parameter. Aerosol single‐scattering computations based on non‐spherical model particles are expected to reduce the shape‐related errors and thus significantly improve the accuracy of radiative forcing simulations. Copyright © 2007 Royal Meteorological Society
Psychometric reevaluation of the Women in Science Scale (WiSS)
Authors: Owen Steven V. , Toepperwein Mary Anne , Pruski Linda A. , Blalock Cheryl L. , Liu Yan , Marshall Carolyn E. , Lichtenstein Michael J.
Published: March 2007

The Women in Science Scale (WiSS) was first developed in 1984, and is still being used in contemporary studies, yet its psychometric properties have not been evaluated with current statistical methods. In this study, the WiSS was administered in its original 27‐item form to 1,439 middle and high school students. Confirmatory factor analysis based upon the original description of the WiSS was modestly supportive of the proposed three‐factor structure, but the claimed dimensions showed substantial redundancy. Therefore, we split our sample and performed exploratory factor analyses on one half. The most satisfactory solution, a two‐factor model, was then applied to the crossvalidation sample with a confirmatory factor analysis. This two‐factor structure was supported with a total of 14 items. Factor 1, Equality, contains eight items, and factor 2, Sexism, six items. Although our data are limited to adolescents, the WiSS, with improved psychometric properties, may be used descriptively to assess attitudes toward women in science and with additional stability and repeatability testing, may be used in evaluation research. The shortened WiSS should result in shorter administration time, fewer missing data, and increased acceptance among survey administrators in classroom settings. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 1461–1478, 2007
The forum taxation of foreign source income. The treasury viewpoint
Authors: Smith Dan Throop
Published: March 2007

The Forum section of each issue presents two or more articles and an editorial on a subject of current interest. The views are those of the authors and do not necessarily represent the attitudes of the Advisory Council or Editorial Board.
Novel oxylipins formed from docosahexaenoic acid by potato lipoxygenase—10(S)‐hydroxydocosahexaenoic acid and 10,20‐dihydroxydocosahexaenoic acid
Authors: Butovich Igor A. , Hamberg Mats , Rådmark Olof
Published: March 2007

Potato tuber lipoxygenase (ptLOX) has been shown to catalyze the aerobic formation of at least four major oxygenated derivatives of DHA. Two of the products—7,17(S)‐ and 10,17(S)‐dihydro(pero)xy‐DHA [7,17‐ and 10,17‐diH(P)DHA]— were formed from soybean 15‐LOX‐derived 17(S)‐hydro(pero)xy‐DHA [17(S)‐H(P)DHA], whereas two novel oxylipin compounds— 10(S)‐hydro(pero)xy‐DHA and 10,20‐dihydro(pero)xy‐DHA [10(S)‐H(P)DHA and 10,20‐diH(P)DHA, respectively]—were the major direct products of DHA oxidation by ptLOX. The reactions proceeded relatively slowly but could be stimulated by catalytic amounts of SDS. Micromolar concentrations of 10(S)‐HPDHA effectively abolished the kinetic lag period of ptLOX activation. Enzymatic activity with DHA or 17(S)‐HPDHA as substrate was about 8% of that with linoleic acid—a standard natural ptLOX substrate—whereas 17(S)‐HDHA was converted at a rate of ∼1%. The enzyme was relatively unstable and quickly inactivated during the reaction with DHA on with 17(S)‐HPDHA (first‐order kinetic constant of inactivation kin=1.5±0.3 min−1), but not with 17(S)‐HDHA. Both 7,17‐ and 10,20‐diH(P)DHA were clearly products of double oxygenation catalyzed by soybean 15‐LOX and/or ptLOX. Our observation that ptLOX could convert 17‐HDHA to 10,17‐diH(P)DHA indicates that this dihydroxylated derivative of DHA also can be formed via a double lipoxygenation mechanism.
Effect of homocysteine, folates, and cobalamin on endothelial cell‐ and copper‐induced LDL oxidation
Authors: Ronco Ana María , Garrido Argelia , Llanos Miguel N. , Guerrero‐Bosagna Carlos , Tamayo Daniela , Hirsch Sandra
Published: March 2007

Oxidation of LDL contributes to endothelial dysfunction and atherosclerosis. This process could be associated with hyperhomocysteinemia, a condition that can be reduced after folic acid treatment. Because a reduction in LDL oxidation may improve endothelial function, we studied the effect of some vitamins (folic acid, 5‐methyltetrahydrofolic acid, and vitamin B‐12) on LDL oxidation, either in the presence or absence of homocysteine. For this purpose, two in vitro systems were used: an endothelial cell‐catalyzed LDL oxidation system and a cell‐free copper‐initiated LDL oxidation system. The kinetics of coppercatalyzed LDL oxidation was determined by continuous monitoring of the production of conjugated dienes in the reaction medium. TBARS production, a parameter of lipid peroxidation, was also evaluated. In both in vitro systems, only 5‐methyl‐tetrahydrofolic acid was able to decrease TBARS production in a concentration‐dependent manner, independently of the presence or absence of homocysteine. In the copper‐induced LDL oxidation system, vitamin B‐12 and 5‐methyltetrahydrofolic acid increased the lag time of conjugated diene production by 25 and 47%, respectively, suggesting that both vitamins in this system had antioxidant properties. Folic acid was unable to show antioxidant properties when included in either in vitro system. The results demonstrate that 5‐methyltetrahydrofolic acid and vitamin B‐12 are important protective agents against LDL oxidative modifications.
Size and number of lymph particles measured by a particle sizer during absorption of structured oils in rats
Authors: Porsgaard Trine , Kánský Jirí , Mason Sarah , Mu Huiling
Published: March 2007

Chylomicrons transport absorbed fat from the intestine to the circulation. During dietary fat absorption, the chylomicrons become larger in diameter, and in some studies an increase in chylomicron number has been observed as well. In the present study, we compared particle size and number in rat lymph following administration of four different oils. We administered fish oil, medium‐chain TAG (MCT), and two structured oils differing in intramolecular structure, with either medium‐chain FA in the outer positions of the TAG and long‐chain n−3 PUFA in the sn‐2 position (MLM oil) or with the reverse structure (LML oil), to lymph‐cannulated rats and collected lymph in fractions for the following 8 h. Chylomicron size was measured by a particle size analyzer immediately after collection, and from these data the number of chylomicrons present was estimated. The number of particles in lymph increased during the absorption of oils containing long‐chain PUFA (MLM, LML, and fish oil), whereas it was not affected by administration of MCT. The FA from MCT were probably absorbed via the portal vein; therefore, only a small number of particles were measured in lymph. When comparing the two structured oils, we observed a tendency toward a higher number of particles after LML administration, although the difference was not statistically significant. The highest number of particles after administration of all oils was observed in the size intervals 53–80 and 80–121 nm and probably represented small chylomicrons. Thus, the FA composition influenced the number of particles in lymph during absorption, whereas TAG structure had only a minor influence.
Anticancer activity and possible mode of action of 4‐O‐podophyllotoxinyl 12‐hydroxyl‐octadec‐Z‐9‐enoate
Authors: Ma Guoyi , Khan Shabana I. , Mustafa Jamal , Walker Larry A. , Khan Ikhlas A.
Published: March 2007

4‐O‐Podophyllotoxinyl 12‐hydroxyl‐octadec‐Z‐9‐enoate (PHEFE) is a structurally novel FA analog of podophyllotoxin. In the present study, in vitro effects of PHEFE on a panel of 60 human tumor cell lines and its potential modes of anticancer action were investigated. FHEFE exhibited strong growth‐inhibitory action in a number of solid tumor cells in vitro. It did not inhibit tubulin polymerization as podophyllotoxin does; rather, it inhibited the catalytic activity of topoisomerase II. Flow cytometry and staining assay with 4,6‐diamidine‐2‐phenylindole dihydrochloride showed that PHEFE blocked the cell cycle at the G2/M phase and induced apoptosis in HL‐60 cells. These analyses suggest that PHEFE has promising anticancer characteristics that differ from podophyllotoxin and etoposide.
Distribution of polyunsaturated fatty acids including conjugated linoleic acids in total and subcellular fractions from healthy and cancerous parts of human kidneys
Authors: Hoffmann Kristina , Blaudszun Jörg , Brunken Claus , Höpker Wilhelm‐Wolfgang , Tauber Roland , Steinhart Hans
Published: March 2007

Differences in the FA composition of subcellular fractions from healthy and cancerous kidney tissues from the same patients were examined. Only minor differences in CLA content were found between the healthy and the cancerous tissue portions. Regarding the distribution pattern, CLA incorporation into nuclei and cytosol was significantly higher than incorporation into plasma membranes and mitochondria, which could be correlated to the neutral lipid content of these fractions. The subcellular distribution pattern of CLA was similar to that observed with monounsaturated FA but unlike that found with 18∶2n−6, which underlines the different physiological properties of CLA and 18∶2n−6. Because PUFA have been suggested to have an effect on cancer risk, the contents of n−3 and n−6 PUFA were determined in kidney and renal cell carcinoma (RCC). The 18∶2n−6 content and Δ5 desaturase activity were significantly lower, and the 18∶3n−6, 20∶3n−6, and 20∶5n−3 contents and Δ6 desaturase activity were significantly higher in RCC than in healthy renal tissue, indicating a changed PUFA metabolism in RCC. Previous research has suggested that CLA inhibits the elongation and desaturation of 18∶2n−6 into 20∶4n−6. In that case, one might speculate that a diet enriched in CLA would be a useful tool in preventing RCC. However, the involvement of CLA in preventing renal cancer could not be demonstrated definitively from the design of this experiment. Further understanding of the cause and/or consequence of the difference in FA metabolism may lead to a better understanding of RCC.
Microbiological contamination in stem cell cultures
Authors: Cobo Fernando , Cortés José Luis , Cabrera Carmen , Nieto Ana , Concha Ángel
Published: March 2007

Cell therapy and regenerative medicine are potentially two of the most exciting aspects of the novel therapeutic methods currently under development. However, these treatments present a number of important biosafety issues, like the possible transmission of microorganisms to the recipients. The most common potential form of contamination in these cell products is by bacteria (including Mycoplasma), yeast and fungi. In our study, 32 stem cell lines and feeder cell lines were analysed. There were 19 contaminated cell passages (12%). The main contaminants were gram positive cocci and Mycoplasma species, followed by gram negative rods and gram positive rods. The Mycoplasma contamination rate was 4%. Stem cell banks and other research centres aim to screen all processed stem cell lines for these microorganisms, and to assure that no contaminants are introduced in the banking procedures. It is a standard part of current good practice in stem cell banks to carry out routine microbiological controls of the stem cell lines and to work in a controlled environment to reduce the probability of contamination in the final product.
Peroxisome proliferator‐activated receptor α is involved in cardiomyocyte differentiation of murine embryonic stem cells in vitro
Authors: Ding Ling , Liang Xingguang , Zhu Danyan , Lou Yijia
Published: March 2007

Peroxisome proliferator‐activated receptor α (PPARα) plays a key role in the transcriptional regulation of genes involved in cellular lipid and energy metabolism, which is abundantly expressed in tissues with high energy demand, including the mammalian heart. Although multiple roles for PPARα in adult cardiomyocytes have been proposed, little is known about the significance of PPARα in early differentiation of cardiomyocytes. To address this issue, murine embryonic stem (ES) cells were adopted in this study since they would differentiate in vitro into cardiomyocytes that faithfully recapitulated cardiomyocyte differentiation in vivo. As determined by semi‐quantitative RT‐PCR and Western‐blot, both PPARα and its coactivatior PGC‐1α were increased during cardiomyocyte differentiation. A positive correlation between PPARα and Troponin‐T expression was also observed by immunofluorescence in early differentiation. Application of PPARα antagonist GW6471 prevented cardiomyocyte differentiation as indicated by reduced expression of cardiac specific genes (α‐MHC, MLC2v) and cardiac sarcomeric proteins (α‐Actinin, Troponin‐T). However, gene expression of cardiac specific transcription factors (GATA4, Nkx2.5, and MEF2C) remained unchanged. Moreover, cardiomyocyte differentiation of EBs could be efficiently stimulated by WY14643 treatment, the specific agonist of PPARα. Taken together, these results suggested a facilitating role of PPARα in cardiomyocyte differentiation of murine ES cells in vitro.
Pro‐proliferating effect of homologous somatic cells on chicken primordial germ cells
Authors: Tang Xinyan , Zhang Caiqiao , Jin Yanmei , Ge Chutian , Wu Yanqun
Published: March 2007

Many studies demonstrated that chicken primordial germ cells (PGCs) could maintain undifferentiated state on mouse embryonic fibroblast feeders supplemented with growth factors and cytokines. However, the xenosupport systems may run risk of cross‐transfer of animal pathogens from the other animal feeder, matrix to the PGCs, then influencing later transgenic technology. In this study, chicken PGCs were identified by alkaline phosphatase, stage‐specific embryonic antigen‐1 and Oct‐4 immunocytochemical stainings. Three different homologous somatic cell feeder layers (chicken embryonic fibroblast feeder layer, CEF; embryonic skeletal myoblast feeder layer; follicular granulosa cell feeder layer) were used to support growth and proliferation of PGCs to find a better supporting culture system. In addition, the effects of fetal calf serum (FCS), leukemia inhibitory factor (LIF) and the combination of insulin, transferring and selenite (ITS) on PGC proliferation were compared. Results showed that CEF was the best supporter for PGC growth and proliferation, which was verified by 5‐bromo‐2′‐deoxyuridine incorporation stain. FCS alone or in combination with LIF could significantly promote PGC proliferation in the presence of CEF in ITS medium. This study will contribute to providing a safer supporting system for chicken PGC amplification in vitro, and may be applied in transgenic chicken production and transplantation therapy.
The low rate of HLA class I molecules on the human embryonic stem cell line HS293 is associated with the APM components' expression level
Authors: Cabrera C.M. , Nieto A. , Cortes J.L. , Montes R.M. , Catalina P. , Cobo F. , Barroso‐del‐Jesus A. , Concha A.
Published: March 2007

Human embryonic stem cells (hESCs) represent a promise for future strategies of tissue replacement. However, there are different issues that should be resolved before these cells can be used in cellular therapies; among others, the rejection of transplantable hESCs as a result of HLA incompatibility between donor cells and recipients. The hESCs exhibit a weak HLA class I expression on the cell surface, but today the responsible mechanisms are unknown. We have analyzed the level expression of HLA class I heavy chain, beta2‐microglobulin (β2‐m), and antigen‐processing machinery (APM) components (TAP1, TAP2, LMP2, LMP7, and Tapasin) using the HS293 hESC line by real‐time quantitative RT‐PCR. This analysis has revealed a low expression of β2‐m, HLA‐B, and Tapasin, and an absence of expression of: TAP1, TAP2, LMP2, and LMP7 genes in the HS293 hESC line respect to the embryoid bodies (EBs) and the induced stem cells with IFNγ (with significant differences, p < 0.05). The lack or loss of HLA class I molecules due to the down‐regulation of the APM components has been frequently found in tumors of different histology as specific mechanisms of immune‐evasion. We described for the first time in this report that the hESCs shared similar mechanisms with respect to tumor cells responsible for the weak HLA class I expression on the cell surface.
Hepatic stellate cell damage may lead to decreased plasma ADAMTS13 activity in rats
Authors: Kume Yukio , Ikeda Hitoshi , Inoue Morihiro , Tejima Kazuaki , Tomiya Tomoaki , Nishikawa Takako , Watanabe Naoko , Ichikawa Tatsuya , Kaneko Makoto , Okubo Shigeo , Yokota Hiromitsu , Omata Masao , Fujiwara Kenji , Yatomi Yutaka
Published: March 2007

ADAMTS13 is gaining attention, because its deficiency causes thrombotic thrombocytopenic purpura. Although its regulatory mechanism is not fully understood, we wondered if hepatic stellate cells (HSCs) play a role, because ADAMTS13 mRNA is exclusively expressed in the liver and primarily in HSCs. Plasma ADAMTS13 activity was markedly reduced in dimethylnitrosamine‐treated rats, where HSC apoptosis is an essential event, but not in carbon tetrachloride‐ or thioacetamide‐treated rats without HSC apoptosis. Furthermore, plasma ADAMTS13 activity was also reduced in 70% hepatectomized rats, where HSC loss occurs. These results suggest that HSC may be involved in the regulation of plasma ADAMTS13 activity.
Understanding behavioral sources of process variation following enterprise system deployment
Authors: Bendoly Elliot , Cotteleer Mark J.
Published: March 2007

This paper extends the current understanding of the time‐sensitivity of intent and usage following large‐scale IT implementation. Our study focuses on perceived system misfit with organizational processes in tandem with the availability of system circumvention opportunities. Case study comparisons and controlled experiments are used to support the theoretical unpacking of organizational and technical contingencies and their relationship to shifts in user intentions and variation in work‐processing tactics over time. Findings suggest that managers and users may retain strong intentions to circumvent systems in the presence of perceived task‐technology misfit. The perceived ease with which this circumvention is attainable factors significantly into the timeframe within which it is attempted, and subsequently impacts the onset of deviation from prescribed practice and anticipated dynamics.
Follow‐up of Abnormal Screening Mammography
Authors:   Committee on Gynecologic Practice
Published: March 2007

Screening mammography facilitates the early diagnosis of breast carcinoma in women. Timely follow‐up can optimize the diagnosis and treatment of women with abnormal screening test results. When test results reveal that additional studies are needed, no barriers should prohibit testing during the screening mammography visit.
Globalization, Immigration, and Lewisian Elastic Labor in Pre–World War II Southeast Asia
Authors: Huff Gregg , Caggiano Giovanni
Published: March 2007

Between 1880 and 1939 Burma, Malaya, and Thailand received inflows of migrants from India and China comparable in size to European immigration in the New World. This article examines the forces that lay behind migration to Southeast Asia and asks if experience there bears out Lewis's unlimited labor supply hypothesis. We find that it does and, furthermore, that immigration created a highly integrated labor market stretching from South India to Southeastern China. Emigration from India and China and elastic labor supply are identified as important components of Asian globalization before the Second World War.
Productivity, Wages, and Labor Politics in Brazil, 1945–1962
Authors: Colistete Renato P.
Published: March 2007

After World War II Brazil experienced exceptionally high economic growth, ranking tenth among the largest economies by 1960. Yet evidence shows that real wages lagged far behind productivity, especially from 1956, the heyday of “developmentalism”—an economic ideology aimed at state-led, accelerated industrialization, with foreign and domestic private capital as active partners. The outcome diverged from that of the “social compact for growth,” the cornerstone of the “golden age” in Europe and Japan. A key reason was that in Brazil left-wingers controlled the main trade unions and pushed an agenda of social reform that was widely rejected by industrialists.
A rapid simple sequence repeat (SSR)-based identification method for potato cultivars
Authors: Reid A. , Kerr E. M.
Published: March 2007

With the numbers of new varieties of potato obtaining Plant Breeders' Rights increasing yearly, the reliable maintenance of large culture collections is becoming more problematic. Additionally, the differentiation of cultivars based on morphological characteristics is a highly skilled and time-consuming task and for these reasons a rapid and robust method for variety differentiation has become highly desirable. By screening a number of microsatellite (simple sequence repeat, SSR) markers we have developed a set of six that can be used to differentiate over 400 cultivars, including those on the UK National List, but excluding somaclonal variants (e.g. Red King Edward and King Edward). The whole process from tuber to accurate identification can be carried out in a single day.
Nuclear and cytoplasmic microsatellite markers for the species of the Dilatata group of Paspalum (Poaceae)
Authors: Speranza Pablo , Malosetti Marcos
Published: March 2007

The Dilatata group ofPaspalumis a polyploid complex native to the grasslands of temperate South America. A pentaploid apomictic biotype ofP. dilatatumis a widely recognized forage grass; however, the complex includes apomictic tetra- and hexaploids along with sexual allotetraploids (P. urvillei,P. dasypleurum,P. dilatatumssp.flavescens, and biotypes Virasoro and Vacaria ofP. dilatatum) which are suspected to be hybrids between different combinations of biotypes. Fifteen primer pairs for nuclear microsatellite loci were developed from a (CA)n-enriched genomic library. A single, low stutter, robust two-step PCR profile was used for all the primer pairs. Twelve primer pairs were analysed for their variability and transferability among all the sexual biotypes of the Dilatata group and the common apomictic pentaploid. Six primer pairs amplified more than one locus, and sequence and segregation evidence suggest that the additional bands correspond to homeologous loci. No close linkage was found among the 16 loci amplified in the tetraploids. One variable chloroplast microsatellite is also reported. All loci were successfully amplified from most members of the Dilatata group and variability was recorded for all the biotypes analysed. The set of loci reported here provide highly variable markers for intra-biotypic population studies, biotype-specific markers for the analysis of hybrid apomicts and a biotype-specific chloroplast marker.
Sigmund Freuds psychoanalytische Kunstanalyse
Authors: Franzen Georg
Published: March 2007

Zusammenfassung. Ausgehend von der Freud-Studie “Der Moses des Michelangelo“ und psychoanalytischen und kunsthistorischen Interpretationen, werden Grundlagen der psychoanalytischen Kunstanalyse skizziert. Die psycho-ikonologische Interpretation als Grundlage einer kunstpsychologischen Untersuchung wird hervorgehoben.
Perspektiven der Kunsttherapie in der klinisch-medizinischen Rehabilitation von Patienten mit Hirnschädigungen
Authors: Mucha Christian
Published: March 2007

Zusammenfassung. Die Kunsttherapie kann bereits in der klinischen Rehabilitationsphase ein sinnvoller Bestandteil des Rehabilitationsplanes sein. Das gilt vor allem in der Rehabilitation von Patienten mit schweren Hirnerkrankungen und -verletzungen, die meistens von multimodalen Defiziten betroffen sind. Hier kann die Kunsttherapie als kreativ-schöpferisches Handeln und Erleben auf physiologischer und psychologischer Ebene wirken und im Rehabilitationsprozess Defizite rekonstruieren bzw. Defekte kompensieren helfen. In der Form eines Erfahrungsberichtes werden mögliche Einflüsse anhand konkreter Bildbeispiele besprochen, wobei die vorgestellte Bilderserie nur eine kleine Auswahl der Arbeiten unserer früheren Patienten beinhaltet.