bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxo-4-methylpentanoic acid directs the metabolism of GABA into the Krebs cycle in rat pancreatic islets
Authors: Hernández-Fisac Inés , Fernández-Pascual Sergio , Ortsäter Henrik , Pizarro-Delgado Javier , Martín Del Río Rafael , Bergsten Peter , Tamarit-Rodriguez Jorge
Published: October 2006

OMP (oxo-4-methylpentanoic acid) stimulates by itself a biphasic secretion of insulin whereas L-leucine requires the presence of L-glutamine. L-Glutamine is predominantly converted into GABA (γ-aminobutyric acid) in rat islets and L-leucine seems to promote its metabolism in the ‘GABA shunt’ [Fernández-Pascual, Mukala-Nsengu-Tshibangu, Martín del Río and Tamarit-Rodríguez (2004) Biochem. J. 379, 721–729]. In the present study, we have investigated how 10 mM OMP affects L-glutamine metabolism to uncover possible differences with L-leucine that might help to elucidate whether they share a common mechanism of stimulation of insulin secretion. In contrast with L-leucine, OMP alone stimulated a biphasic insulin secretion in rat perifused islets and decreased the islet content of GABA without modifying its extracellular release irrespective of the concentration of L-glutamine in the medium. GABA was transaminated to L-leucine whose intracellular concentration did not change because it was efficiently transported out of the islet cells. The L-[U-14C]-Glutamine (at 0.5 and 10.0 mM) conversion to 14CO2 was enhanced by 10 mM OMP within 30% and 70% respectively. Gabaculine (250 μM), a GABA transaminase inhibitor, suppressed OMP-induced oxygen consumption but not L-leucine- or glucose-stimulated respiration. It also suppressed the OMP-induced decrease in islet GABA content and the OMP-induced increase in insulin release. These results support the view that OMP promotes islet metabolism in the ‘GABA shunt’ generating 2-oxo-glutarate, in the branched-chain α-amino acid transaminase reaction, which would in turn trigger GABA deamination by GABA transaminase. OMP, but not L-leucine, suppressed islet semialdehyde succinic acid reductase activity and this might shift the metabolic flux of the ‘GABA shunt’ from γ-hydroxybutyrate to succinic acid production.
RNAi-mediated silencing of prohormone convertase (PC) 5/6 expression leads to impairment in processing of cocaine- and amphetamine-regulated transcript (CART) precursor
Authors: Stein Jeffrey , Shah Rohan , Steiner Donald F. , Dey Arunangsu
Published: October 2006

Understanding the functions of the widely expressed PCs (prohormone/proprotein convertases), including PC5/6, furin and PACE4 (paired basic amino acid cleaving enzyme 4), in animal models is difficult since individual knockouts of these PCs in mice exhibit early embryonic lethality. To investigate the roles of PC5/6 in processing pro-CART (pro-cocaine- and amphetamine-regulated transcript), an important anorexigenic peptide precursor, we have generated GH3 cells silenced for PC5/6 expression by RNAi (RNA interference). We show, following transient knockdown of PC5/6 in these neuroendocrine cells, that generation of the two bioactive forms, CART I (amino acids 42–89/55–102) and CART II (amino acids 49–89/62–102), from pro-CART is impaired due to a lack particularly of the A isoform of PC5/6. The results indicate that PC5/6A shares specificities primarily with PC2 (PC5/6A<PC2) in cleaving the pairs of basic residues, KR (40, 41↓/53, 54↓) and KK (47, 48↓/60, 61↓), within the pro-CART isoforms [see Dey, Zhu, Carroll, Turck, Stein and Steiner (2003) J. Biol. Chem. 278, 15007–15014]. We do not find any significant role of PC5/6A in processing the RXXR (29–32↓) site for production of intermediate CART (amino acids 33–102) from long pro-CART. The findings taken altogether indicate that PC5/6 participates in normal processing of pro-CART.
The differential catalytic activity of ribosome-inactivating proteins saporin 5 and 6 is due to a single substitution at position 162
Authors: Ghosh Paroma , Batra Janendra K.
Published: October 2006

Saporin, a type I ribosome-inactivating protein produced by the soapwort plant Saponaria officinalis belongs to a multigene family that encodes its several isoforms. The saporin seed isoform 6 has significantly higher N-glycosidase and cytotoxic activities compared with the seed isoform 5, although the two have identical active sites. In the present study, we have investigated the contribution of non-conservative amino acid changes outside the active sites of these isoforms towards their differential catalytic activity. The saporin 6 residues Lys134, Leu147, Phe149, Asn162, Thr188 and Asp196 were replaced by the corresponding saporin 5 residues, Gln134, Ser147, Ser149, Asp162, Ile188 and Asn196, to generate six variants of saporin 6, K134Q, L147S, F149S, N162D, T188I and D196N. By functional characterization, we show that the change in amino acid Asn162 in saporin 6 to aspartic acid residue of saporin 5 contributes mainly to the lower catalytic activity of saporin 5 compared with saporin 6. The non-involvement of other non-conservative amino acids in the differential catalytic activity of these isoforms was confirmed with the help of the double mutations N162D/K134Q, N162D/L147S, N162D/F149S, N162D/T188I and N162D/D196N.
CHMP7, a novel ESCRT-III-related protein, associates with CHMP4b and functions in the endosomal sorting pathway
Authors: Horii Mio , Shibata Hideki , Kobayashi Ryota , Katoh Keiichi , Yorikawa Chiharu , Yasuda Jiro , Maki Masatoshi
Published: October 2006

All CHMPs (charged multivesicular body proteins) reported to date have common features: they all contain approx. 200 amino acid residues, have coiled-coil regions and have a biased distribution of charged residues (basic N-terminal and acidic C-terminal halves). Yeast orthologues of CHMPs, including an ESCRT-III component Snf7, are required for the sorting of cargo proteins to intraluminal vesicles of multivesicular bodies. We have characterized a novel human ESCRT-III-related protein, designated CHMP7, which consists of 453 amino acid residues. CHMP7 contains an SNF7 domain and a distantly SNF7-related domain in its C-terminal half and N-terminal half respectively. Among the ten CHMP proteins classified previously in six subfamilies (CHMP1–CHMP6), the C-terminal SNF7 domain of CHMP7 is most similar to the SNF7 domain of CHMP6, which associates with CHMP4 proteins and EAP20, a component of ESCRT-II. Pull-down assays using lysates of HEK-293T (human embryonic kidney) cells that overexpressed Strep-tagged CHMP7 and GFP (green fluorescent protein)-fused CHMP4b (also named Shax1) revealed a positive interaction between the C-terminal half of CHMP7 and CHMP4b. However, interaction was not observed between CHMP7 and EAP20. Confocal fluorescence microscopic analyses revealed that FLAG–CHMP7 is distributed in HeLa cells diffusely throughout the cytoplasm, but with some accumulation, especially in the perinuclear area. The distribution of FLAG–CHMP7 was altered to a cytoplasmic punctate pattern by overexpression of either CHMP4b–GFP or GFP–Vps4BE235Q, a dominant-negative mutant of the AAA (ATPase associated with various cellular activities) Vps4B, and partially co-localized with them. Ubiquitinated proteins and endocytosed EGF accumulated in GFP–CHMP7-expressing cells. A dominant-negative effect of overexpressed GFP–CHMP7 was also observed in the release of virus-like particles from HEK-293T cells that transiently expressed the MLV (murine leukaemia virus) Gag protein. These results suggest that CHMP7, a novel CHMP4-associated ESCRT-III-related protein, functions in the endosomal sorting pathway.
Accumulation of lipophilic dications by mitochondria and cells
Authors: Ross Meredith F. , Da Ros Tatiana , Blaikie Frances H. , Prime Tracy A. , Porteous Carolyn M. , Severina Inna I. , Skulachev Vladimir P. , Kjaergaard Henrik G. , Smith Robin A. J. , Murphy Michael P.
Published: October 2006

Lipophilic monocations can pass through phospholipid bilayers and accumulate in negatively-charged compartments such as the mitochondrial matrix, driven by the membrane potential. This property is used to visualize mitochondria, to deliver therapeutic molecules to mitochondria and to measure the membrane potential. In theory, lipophilic dications have a number of advantages over monocations for these tasks, as the double charge should lead to a far greater and more selective uptake by mitochondria, increasing their therapeutic potential. However, the double charge might also limit the movement of lipophilic dications through phospholipid bilayers and little is known about their interaction with mitochondria. To see whether lipophilic dications could be taken up by mitochondria and cells, we made a series of bistriphenylphosphonium cations comprising two triphenylphosphonium moieties linked by a 2-, 4-, 5-, 6- or 10-carbon methylene bridge. The 5-, 6- and 10-carbon dications were taken up by energized mitochondria, whereas the 2- and 4-carbon dications were not. The accumulation of the dication was greater than that of the monocation methyltriphenylphosphonium. However, the uptake of dications was only described by the Nernst equation at low levels of accumulation, and beyond a threshold membrane potential of 90–100 mV there was negligible increase in dication uptake. Interestingly, the 5- and 6-carbon dications were not accumulated by cells, due to lack of permeation through the plasma membrane. These findings indicate that conjugating compounds to dications offers only a minor increase over monocations in delivery to mitochondria. Instead, this suggests that it may be possible to form dications within mitochondria that then remain within the cell.
Symmetries of the Robinson-Trautman equation
Authors: Natorf W. , Tafel J.
Published: October 2006

We study point symmetries of the Robinson-Trautman equation. The cases of one- and two-dimensional algebras of infinitesimal symmetries are discussed in detail. The corresponding symmetry reductions of the equation are given. Higher dimensional symmetries are shortly discussed. It turns out that all known exact solutions of the Robinson-Trautman equation are symmetric.
Selective adsorption of block copolymers on patterned surfaces
Authors: Moghaddam Maria Sabaye , Chan Hue Sun
Published: October 2006

Adsorption of copolymers on patterned surfaces is studied using lattice modeling and multiple Markov chain Monte Carlo methods. The copolymer is composed of alternating blocks of A and B monomers, and the adsorbing surface is composed of alternating square blocks containing C and D sites. Effects of interaction specificity on the adsorbed pattern of the copolymer and the sharpness of the adsorption transition are investigated by comparing three different models of copolymer-surface interactions. Analyses of the underlying energy distribution indicate that adsorption transitions in our models are not two-state-like. We show how the corresponding experimental question may be addressed by calorimetric measurements as have been applied to protein folding. Although the adsorption transitions are not “first order” or two-state-like, the sharpness of the transition increases when interaction specificity is enhanced by either including more attractive interaction types or by introducing repulsive interactions. Uniformity of the pattern of the adsorbed copolymer is also sensitive to the interaction scheme. Ramifications of the results from the present minimalist models of pattern recognition on the energetic and statistical mechanical origins of undesirable nonspecific adsorption of synthetic biopolymers in cellular environments are discussed.
Electronic properties of ultrathin HfO2, Al2O3, and Hf–Al–O dielectric films on Si(100) studied by quantitative analysis of reflection electron energy loss spectra
Authors: Jin Hua , Oh Suhk Kun , Kang Hee Jae , Tougaard Sven
Published: October 2006

Quantitative analysis of reflection electron energy loss spectra for ultrathin HfO2, Al2O3, and Hf–Al–O dielectric thin films on Si(100) were carried out by using Tougaard-Yubero [Surf. Interface Anal. 36, 824 (2004)] QUEELS-ε(k,ω)-REELS software. Experimental cross sections obtained from reflection electron energy loss spectroscopy were compared with theoretical inelastic scattering cross section Ksc deduced from the simulated energy loss function (ELF). The ELF is expressed as a sum of Drude oscillators. For HfO2, the ELF shows peaks in the vicinity of 10, 17, 22, 27, 37, and 47eV. For Al2O3, a broad peak at 22eV with a very weak shoulder at 14eV and a shoulder at 32eV were observed, while for the Al2O3 doped HfO2, the peak position is similar to that of HfO2. This indicates that when Hf–Al–O film is used as a gate dielectric in a complementary metal-oxide semiconductor transistor, its electronic structure is mainly determined by the d state of Hf. In addition, the inelastic mean free path (IMFP) was also calculated from the theoretical inelastic scattering cross section. The IMFPs at 300eV were about 7.05, 9.62, and 8.48Å and those at 500eV were 11.42, 15.40, and 13.64Å for HfO2, Al2O3, and Hf–Al–O, respectively. The method of determining the IMFP from the ELF is a convenient tool for ultrathin dielectric materials.
Magnetic-field-dependent type-II transition induced by resonant electron tunneling from a diluted magnetic semiconductor quantum well into self-assembled quantum dots
Authors: Murayama A. , Asahina T. , Nishibayashi K. , Souma I. , Oka Y.
Published: October 2006

Magnetic-field-dependent type-II transition has been observed between electrons in self-assembled quantum dots (QDs) of CdSe and heavy holes (hhs) in a diluted magnetic semiconductor quantum well (DMS-QW) of Zn1−x−yCdxMnySe, originating from an electron tunneling from the DMS-QW into the QDs. The electron tunneling is resonantly assisted by LO-phonon scattering in the QDs. As a result, the type-II emission energy depends on a magnetic field, since the electron energy in the DMS-QW is a function of field strength. The magnetic-field dependence of intensity of the type-II emission suggests a level-crossing field of the hh states between the QD and DMS-QW.
On-ground characterization of Rosetta/VIRTIS-M. II. Spatial and radiometric calibrations
Authors: Filacchione G. , Ammannito E. , Coradini A. , Capaccioni F. , Piccioni G. , De Sanctis M. C. , Dami M. , Barbis A.
Published: October 2006

After having considered the spectral and geometrical performances of the Rosetta/VIRTIS-M experiment, we complete here the analysis by evaluating quantitatively the flat-field and radiometric responses. The purpose of this work is to retrieve the flat-field matrix necessary to homogenize the focal plane response. Moreover, the most important result is the determination of the instrument transfer function that allows to convert digital numbers in physical units of spectral radiance (Wm−2μm−1sterad−1). The strategy adopted to organize measurement sequence, a basic description of the on-ground experimental setups and the analysis of the collected data, is included in this article. An analysis of the instrumental stability has been performed as well by examining how the internal calibration data are affected by environmental conditions. These data allow to evaluate the cumulative effects of thermal and vibrational stresses on the instrumental performances: up to now we have verified that this effect is negligible. Finally the basic calibration pipeline used to calibrate in-flight data with on-ground parameters is fully described.
Ferroelectric aging effect in hybrid-doped BaTiO3 ceramics and the associated large recoverable electrostrain
Authors: Liu Wenfeng , Chen Wei , Yang Liu , Zhang Lixue , Wang Yu , Zhou Chao , Li Shengtao , Ren Xiaobing
Published: October 2006

Acceptor doping and donor doping have been known to result in opposite ferroelectric aging effects, but the aging effect of hybrid-doped (acceptor+donor) ferroelectrics has remained unclear. In this letter the authors report the aging effect in Mn3++Nb5+ hybrid-doped BaTiO3 ceramics with acceptor fixed at 1mol% but with donor varied from 0.5to2mol%. The authors found surprisingly that ferroelectric aging existed in all the samples, no matter which of the two, acceptor or donor, was dominant: all the samples showed a double hysteresis loop after aging, but with increasing donor (Nb5+) concentration the coercive field and hysteresis decrease. Meanwhile, a large nonlinear recoverable electrostrain up to 0.17% (due to reversible domain switching) was observed at 3kV∕mm, which exceeded that of acceptor-monodoped ceramics and was about twice the piezoelectric strain of hard lead zirconate titanate. These results demonstrate that hybrid doping is an effective way to enhance the domain-switching-related electrostrain properties. Finally, the aging effect of hybrid-doped ferroelectrics was explained.
Ligand reorganization and activation energies in nonadiabatic electron transfer reactions
Authors: Zhu Jianjun , Wang Jianji , Stell George
Published: October 2006

The activation energy and ligand reorganization energy for nonadiabatic electron transfer reactions in chemical and biological systems are investigated in this paper. The free energy surfaces and the activation energy are derived exactly in the general case in which the ligand vibration frequencies are not equal. The activation energy is derived by free energy minimization at the transition state. Our formulation leads to the Marcus-Hush [J. Chem. Phys. 24, 979 (1956); 98, 7170 (1994); 28, 962 (1958)] results in the equal-frequency limit and also generalizes the Marcus-Sumi [J. Chem. Phys. 84, 4894 (1986)] model in the context of studying the solvent dynamic effect on electron transfer reactions. It is found that when the ligand vibration frequencies are different, the activation energy derived from the Marcus-Hush formula deviates by 5%–10% from the exact value. If the reduced reorganization energy approximation is introduced in the Marcus-Hush formula, the result is almost exact.
Time-dependent density functional theory investigation of the absorption, fluorescence, and phosphorescence spectra of solvated coumarins
Authors: Jacquemin Denis , Perpète Eric A. , Scalmani Giovanni , Frisch Michael J. , Assfeld Xavier , Ciofini Ilaria , Adamo Carlo
Published: October 2006

Using time-dependent density functional theory (TD-DFT) and the polarizable continuum model, we have computed the electronic transitions of a large panel of coumarin dyes in their enol, keto, cationic, and anionic forms. Several processes have been studied: absorption, fluorescence, 0-0 phosphorescence, and triplet-triplet excitations. For each process, detailed comparison with experimental data has been carried out. Using the PBE0∕6-31+G(d) scheme, it turns out that for a given electronic transition the experimental shifts resulting from the substitution of the coumarin core are nicely reproduced. Indeed, once a simple statistical correction is applied, the mean absolute errors on the absorption and fluorescence wavelengths are limited to 8nm (0.09eV) and 9nm (0.07eV), respectively. A valuable correlation between the experimental and theoretical phosphorescence auxochromic displacements has also been unravelled. The differences between the wavelengths of the various electronic processes of a given dye tend to be fairly predicted, especially for the fluorescence-phosphoresence shifts that are strongly overestimated by TD-DFT.
Growth and structure of Pd films on ZnO(0001)
Authors: Bera Parthasarathi , Vohs John M.
Published: October 2006

The growth and structure of Pd films on ZnO(0001) were investigated using high resolution electron energy loss spectroscopy, x-ray photoelectron spectroscopy, and low energy electron diffraction. Vapor deposited Pd films at 300K were found to follow a two-dimensional (2D) island growth mode, in which 2D metal islands are formed up to a critical coverage at which point growth occurs primarily in a layer-by-layer fashion on top of the islands. Heating to only 350K was found to be sufficient to induce partial agglomeration of Pd films into three-dimensional particles. In addition to causing further agglomeration into particles, heating to 700K resulted in partial reduction of the ZnO surface and the formation of a PdZn alloy.
Helium clusters seeded with CO molecules: New results for HeN–C1813O and the approach to the nanodroplet limit
Authors: McKellar A. R. W.
Published: October 2006

Infrared spectra of helium clusters seeded with doubly substituted carbon monoxide molecules, C1813O, have been studied in order to complement recent helium nanocluster results and to determine whether additional isotopic data would help to separate vibrational and rotational contributions to the observed transitions. The experiments were made by direct infrared absorption in pulsed supersonic jet expansions using a tunable diode laser probe in the region of the fundamental band (∼2045cm−1 for C1813O). Even with data on the R(0) transitions from four CO isotopomers, it was found that a clear and consistent separation of vibration and rotation could not be achieved for HeN–CO clusters in the size range N≈10–20. Isotope shifts observed for clusters with C1813O (relative to C1612O) were found to be close to the sums of the shifts previously determined for C1613O and C1812O. The new measurements generally supported previous assignments of cluster size, but some modifications for the range N=14–16 are suggested here. New measurements for HeN–C1612O under conditions favoring larger clusters (high backing pressure and low jet temperature) showed that individual transitions could be resolved even at N≈50. For larger clusters, a partly resolved “lump” of transitions was observed to approach the nanodroplet limit.
Testing ion-neutral interaction potentials using calculated ion transport coefficients
Authors: Hogan M. J.
Published: October 2006

Several commonly measured ion transport coefficients were investigated in order to determine their sensitivity for testing and comparing proposed ion-neutral interaction potentials. A variety of positive ions, negative ions, neutrals, and temperatures were included in order to draw as general a conclusion as possible. All transport coefficients considered were found to be sufficiently sensitive to be used to clearly distinguish between less and more accurate interaction potentials. It was also found that the longitudinal diffusion coefficient is the most sensitive test, followed by both the transverse diffusion coefficient and the ratio of the longitudinal diffusion coefficient to mobility, followed by the ratio of the transverse diffusion coefficient to mobility and that the mobility is the least sensitive test. When presently achievable levels of experimental error were also taken into account, however, there was no significant difference in the sensitivities.
Microwave dissipation in arrays of single-wall carbon nanotubes
Authors: Highstrete Clark , Shaner Eric A. , Lee Mark , Jones Frank E. , Dentinger Paul M. , Alec Talin A.
Published: October 2006

The transmission and reflection scattering parameters of arrays of single-wall carbon nanotubes (SWCNTs) directly assembled onto coplanar waveguides (CPWs) have been measured from 0.01to50GHz at room temperature. Typical arrays consisted of roughly ∼103 SWCNTs aligned parallel to the electric field polarization of the propagating field. Scattering parameters were measured on CPWs both before and after SWCNT assembly, allowing separation of SWCNT effects from the characteristics of the bare CPWs. Additional frequency-dependent power dissipation was consistently observed after assembly of SWCNT arrays.
Domain size effects in molecular dynamics simulation of phonon transport in silicon
Authors: Sun Lin , Murthy Jayathi Y.
Published: October 2006

Molecular dynamics (MD) simulation is employed to compute thermal conductivity and dispersion curves for bulk silicon using the environment dependent interatomic potential. Thermal conductivity simulations using the Green-Kubo method are found to converge to the bulk value with 216 atoms or more. Computed values in the 300–1000K range compare well with experiment. MD results are analyzed to obtain phonon dispersion curves along the [100] direction and compare well with those using the dynamical matrix approach. It is found that bulk thermal properties may be computed using MD in relatively small domains provided that the dominant energy-containing wavelengths are well resolved.
Soft x-ray magnetic circular dichroism study of Mn–Ir∕Co–Fe bilayers with giant exchange anisotropy
Authors: Tsunoda M. , Nakamura T. , Naka M. , Yoshitaki S. , Mitsumata C. , Takahashi M.
Published: October 2006

Soft x-ray magnetic circular dichroism (XMCD) and element-specific magnetic hysteresis (ESMH) measurements were performed in transmission mode on Mn73Ir27 10nm∕Co70Fe30 2nm bilayers with different chemical orderings of the Mn–Ir layer.The unidirectional anisotropy constant was 0.55erg∕cm2 for the disordered Mn–Ir layer and 1.18erg∕cm2 for the ordered Mn–Ir layer. The XMCD signal of Mn was observed, which means the induced ferromagnetic component of Mn spins through the exchange coupling at the interface. No vertical offset of the Mn ESMH loops was observed for either the disordered or the ordered bilayers, which means that insignificant uncompensated Mn spin was pinned at the interface to induce exchange bias on the Co–Fe layer.
Micromachined piconewton force sensor for biophysics investigations
Authors: Koch Steven J. , Thayer Gayle E. , Corwin Alex D. , de Boer Maarten P.
Published: October 2006

The authors describe a micromachined force sensor that is able to measure forces as small as 1pN in both air and water. First, they measured the force field produced by an electromagnet on individual 2.8μm magnetic beads glued to the sensor. By repeating with 11 different beads, they measured a 9% standard deviation in saturation magnetization. They next demonstrated that the sensor was fully functional when immersed in physiological buffer. These results show that the force sensors can be useful for magnetic force calibration and also for measurement of biophysical forces on chip.
Midgap luminescence centers in single-wall carbon nanotubes created by ultraviolet illumination
Authors: Iakoubovskii Konstantin , Minami Nobutsugu , Kim Yeji , Miyashita Kanae , Kazaoui Said , Nalini Balakrishnan
Published: October 2006

The authors report the effect of ultraviolet (UV) illumination on optical properties of single-wall carbon nanotubes (SWCNTs) isolated using various dispersants. It is demonstrated that even weak UV light (∼1mW∕cm2) can irreversibly alter the SWCNT structure, thus resulting in the emergence of hitherto unknown, redshifted photoluminescence (PL) peaks with concomitant reduction in some of the original PL peaks. These UV-induced changes are characterized in detail and attributed to the creation of midgap PL centers.
Efficient blue organic light-emitting device based on N, N′-di(naphth-2-yl)-N, N′-diphenyl-benzidine with an exciton-confining structure
Authors: Divayana Y. , Sun X. W. , Chen B. J. , Lo G. Q. , Jiang C. Y. , Sarma K. R.
Published: October 2006

A blue organic light-emitting device with improved efficiency and excellent color purity is reported (Commission Internationale de’l Eclairage coordinates of x=0.1659 and y=0.0772 at 5V), where N, N′-di(naphth-2-yl)-N, N′-diphenyl-benzidine (NPB), a traditional hole-transporting layer, was used as the emission layer. A significant increase in efficiency was achieved by confining the excitons within the NPB layer by two wide-band-gap hole-blocking layers sandwiching the NPB layer. This structure also increases the direct exciton formation at the NPB layer by promoting electrons to cross the NPB layer, responsible for further efficiency improvement. Optimized structure showed an external quantum efficiency of 1.38%, which accounts for a 25% increase compared to a standard device.
Phase diagram of AlN:(Ga, As)
Authors: Elyukhin V. A. , Escobosa A. , Sánchez-R. V. M.
Published: October 2006

Self-assembling of 1As4Ga tetrahedral clusters in zinc blende AlN doped with Ga and As in the ultradilute As impurity limit is described by a phase diagram. The occurrence of these clusters is an initial stage of self-assembling. The final stage of self-assembling when all As impurities are in 1As4Ga clusters is reached at a finite temperature. Both stages are results of the second-order transitions. The conditions of these phase transitions are represented. It is shown that the phase diagram of wurtzite AlN:(Ga, As) should be quantitatively similar to the considered zinc blende one.
Angle dependent surface enhanced Raman scattering obtained from a Ag nanorod array substrate
Authors: Liu Yongjun , Fan Jianguo , Zhao Y.-P. , Shanmukh Saratchandra , Dluhy Richard A.
Published: October 2006

The angular dependence of surface enhanced Raman scattering (SERS) has been investigated for molecules adsorbed onto Ag nanorod array substrates fabricated using an oblique angle deposition technique. The strong SERS signal of trans-1,2-bis(4-pyridyl) ethene (BPE) was found to be strongly dependent on the incident angle of the excitation laser, with the maximum SERS intensity appearing at approximately 45° relative to the surface normal. A scattering model based on classical electrodynamic dipole radiation has been developed for BPE adsorbed onto these Ag nanorod substrates, and the theoretical SERS scattering intensity was found to be in good agreement with the experimental results.
Carrier recombination and diffusion in GaN revealed by transient luminescence under one-photon and two-photon excitations
Authors: Juršėnas S. , Miasojedovas S. , Žukauskas A. , Lucznik B. , Grzegory I. , Suski T.
Published: October 2006

Carrier recombination and diffusion dynamics in a 100-μm-thick GaN grown by hydride vapor phase epitaxy on semi-insulating GaN:Mg substrate have been studied by means of transient photoluminescence under one-photon (1P) and two-photon (2P) excitations. For 2P bulk excitation the luminescence transients featured an exponential decay with the time constant of 1100ps, which was mainly due to carrier capture to nonradiative deep traps. Meanwhile for 1P surface excitation, the luminescence transients showed a nonexponential decay with the mean time constant of 440ps, which was shown to be due to both carrier in-depth diffusion and recombination.
Pressure enhancement of the giant magnetocaloric effect in LaFe11.6Si1.4
Authors: Sun Young , Arnold Z. , Kamarad J. , Wang Guang-Jun , Shen Bao-Gen , Cheng Zhao-Hua
Published: October 2006

The authors have studied the effects of pressure on the magnetocaloric effect in a polycrystalline LaFe11.6Si1.4 sample. The Curie temperature TC of the sample rapidly decreases from 191K at ambient pressure to 80K under 8.3kbar pressure. The metamagnetic transition induced by field at temperatures above TC becomes extremely sharp under high pressure and the critical field Hc of the transition increases fast with increasing temperature. As a result, the giant magnetocaloric effect in LaFe11.6Si1.4 is greatly enhanced by pressure, especially at low magnetic fields. For a field variation of 1T only, the maximum value of the entropy change is as high as 34J∕kgK.
Modelling of wheat black point incidence based on meteorological variables in the southern Argentinean Pampas region
Authors: Moschini Ricardo C. , Sisterna M. N. , Carmona M. A.
Published: October 2006

Studies were undertaken during 3 growing seasons at several locations on the Argentinean Pampas to investigate the relationships between environmental factors and black point incidence, and to develop predictive models. The strongest associations were observed throughout the critical period starting at 543 degree-days from heading to 861 degree-days (base temperature = 0°C). After a selection process, the best regression equation was: PI % = –6.50 + 0.07 DPrDDTd + 0.23 DRH, where PI is predicted disease incidence, DPrDDTd is a product of days with precipitation and the total degree-day accumulation of mean daily temperatures greater than 17°C (DDTd), and DRH is the total days with relative humidity above 62%. The equation accounted for 87% of the total variance in the disease incidence. Using logistic regression techniques, a model including precipitation frequency and DDTd could satisfactorily explain the probability of occurrence of severe, moderate, and light epidemics.
Improving the performance of canola in retained wheat stubble
Authors: Bruce S. E. , Ryan M. H. , Kirkegaard J. A. , Pratley J.
Published: October 2006

Four field experiments investigated strategies to reduce the negative effects of surface-retained wheat stubble on the emergence, growth, and yield of canola. All experiments compared 3 stubble treatments: (1) no stubble (stubble removed or burnt); (2) stubble-spread (6 t/ha wheat stubble evenly distributed on the surface); and (3) stubble-inter-row (6 t/ha stubble distributed on the inter-rows only). Seedling emergence was reduced in the presence of evenly spread stubble compared with no stubble, and the emerged seedlings had longer hypocotyls, reduced leaf number, and reduced biomass. Reduced shoot growth was not associated with lower shoot N concentration. These early effects on shoot growth persisted at 3 of the 4 sites, resulting in average yield reductions of 26% (range 0–59%) in the stubble-spread treatments compared with no stubble. Restricting stubble to the inter-rows resulted in an initial reduction in seedling growth compared with no stubble, but this difference had diminished by flowering. The yield for the stubble inter-row treatment was similar to no stubble at 2 sites and intermediate between no stubble and stubble-spread at the other 2 sites, with an overall yield reduction of 5.3% compared with no stubble. The results indicate that the negative effects on canola performance of surface-retained wheat stubble can be largely eliminated by adopting sowing techniques that push wheat stubble away from the seeding row and onto the inter-row. This provides a viable option to stubble burning and maintains the benefits of stubble retention.
The effect of time off feed prior to slaughter on muscle glycogen metabolism and rate of pH decline in three different muscles of stimulated and non-stimulated sheep carcasses
Authors: Daly B. L. , Gardner G. E. , Ferguson D. M. , Thompson J. M.
Published: October 2006

The aim of this study was to determine the effect of time off feed (TOF) prior to slaughter on muscle glycogen metabolism and rate of pH decline in sheep muscle. All animals were maintained on a roughage diet for 6 weeks and were then subjected to either 0, 2, or 4 days TOF with access to water, prior to slaughter. Glycogen concentrations were determined post-slaughter for 3 different muscles, M. longissimus thoracis et lumborum (LTL), M. semimembranosus (SM), and M. semitendinosus (ST), as well as measuring pH declines for all animals in each of the 3 muscles under both electrically stimulated and control conditions. Ultimate pH values (pHu) were determined 48 h post-slaughter. Both the 2-day and 4-day TOF groups lost liveweight during their curfew period, whereas the control (0-day) group gained weight. TOF had no effect on post-slaughter carcass characteristics, muscle glycogen concentrations, pHu, or rate of pH decline. Increased muscle glycogen concentrations resulted in faster rates of pH decline. This response was curvilinear, plateauing at a glycogen concentration of about 56 mmol/kg muscle. Muscle glycogen concentration also affected the response of pH decline to electrical stimulation, interacting with muscle and pre-stimulation pH. Low muscle glycogen levels limited delta pH only in the SM and ST and only in muscles of lower pre-stimulation pH.
Navigation-associated medial parietal neurons in monkeys
Authors: Sato Nobuya , Sakata Hideo , Tanaka Yuji L. , Taira Masato
Published: October 2006

To examine the neural basis of route knowledge by which one can reach one's destination, we recorded the activity of 580 neurons in the monkey medial parietal region (MPR) while monkeys actively navigated through a virtual environment. One hundred eighty of these neurons (31%) showed significant responses to the monkeys' movements in the virtual environment. Of these responsive neurons, 77% (139/180) showed responses associated with a specific movement at a specific location (navigation neurons), 8% (14/180) showed responses associated with a specific movement (movement-selective neurons), and the remaining 27 neurons (15%) were nonselective. We found navigation neurons whose responses to the same movement at the same location were modulated depending on the route that the monkey was currently taking, that is, in a route-selective manner (32 of 59 tested neurons among 139 navigation neurons, route-selective navigation neurons). The reversible inactivation of MPR neurons by muscimol resulted in a monkey becoming lost during the navigation task trial. These results suggest that MPR plays a critical role in route-based navigation by integrating location information and self-movement information.
Impacts of genetic bottlenecks on soybean genome diversity
Authors: Hyten David L. , Song Qijian , Zhu Youlin , Choi Ik-Young , Nelson Randall L. , Costa Jose M. , Specht James E. , Shoemaker Randy C. , Cregan Perry B.
Published: October 2006

Soybean has undergone several genetic bottlenecks. These include domestication in Asia to produce numerous Asian landraces, introduction of relatively few landraces to North America, and then selective breeding over the past 75 years. It is presumed that these three human-mediated events have reduced genetic diversity. We sequenced 111 fragments from 102 genes in four soybean populations representing the populations before and after genetic bottlenecks. We show that soybean has lost many rare sequence variants and has undergone numerous allele frequency changes throughout its history. Although soybean genetic diversity has been eroded by human selection after domestication, it is notable that modern cultivars have retained 72% of the sequence diversity present in the Asian landraces but lost 79% of rare alleles (frequency ≤0.10) found in the Asian landraces. Simulations indicated that the diversity lost through the genetic bottlenecks of introduction and plant breeding was mostly due to the small number of Asian introductions and not the artificial selection subsequently imposed by selective breeding. The bottleneck with the most impact was domestication; when the low sequence diversity present in the wild species was halved, 81% of the rare alleles were lost, and 60% of the genes exhibited evidence of significant allele frequency changes.
Cdx4 dysregulates
Hox
gene expression and generates acute myeloid leukemia alone and in cooperation with Meis1a in a murine model
Authors: Bansal Dimple , Scholl Claudia , Fröhling Stefan , McDowell Elizabeth , Lee Benjamin H. , Döhner Konstanze , Ernst Patricia , Davidson Alan J. , Daley George Q. , Zon Leonard I. , Gilliland D. Gary , Huntly Brian J. P.
Published: October 2006

HOX
genes have emerged as critical effectors of leukemogenesis, but the mechanisms that regulate their expression in leukemia are not well understood. Recent data suggest that the caudal homeobox transcription factors CDX1, CDX2, and CDX4, developmental regulators of
HOX
gene expression, may contribute to HOX gene dysregulation in leukemia. We report here that
CDX4
is expressed normally in early hematopoietic progenitors and is expressed aberrantly in ≈25% of acute myeloid leukemia (AML) patient samples. Cdx4 regulates
Hox
gene expression in the adult murine hematopoietic system and dysregulates
Hox
genes that are implicated in leukemogenesis. Furthermore, bone marrow progenitors that are retrovirally engineered to express Cdx4 serially replate in methylcellulose cultures, grow in liquid culture, and generate a partially penetrant, long-latency AML in bone marrow transplant recipients. Coexpression of the Hox cofactor Meis1a accelerates the Cdx4 AML phenotype and renders it fully penetrant. Structure–function analysis demonstrates that leukemic transformation requires intact Cdx4 transactivation and DNA-binding domains but not the putative Pbx cofactor interaction motif. Together, these data indicate that Cdx4 regulates
Hox
gene expression in adult hematopoiesis and may serve as an upstream regulator of
Hox
gene expression in the induction of acute leukemia. Inasmuch as many human leukemias show dysregulated expression of a spectrum of HOX family members, these collective findings also suggest a central role for CDX4 expression in the genesis of acute leukemia.
Modern Quaternary plant lineages promote diversity through facilitation of ancient Tertiary lineages
Authors: Valiente-Banuet Alfonso , Rumebe Adolfo Vital , Verdú Miguel , Callaway Ragan M.
Published: October 2006

One of the most important floristic sorting periods to affect modern plant communities occurred during the shift from the wet Tertiary period to the unusually dry Quaternary, when most global deserts developed. During this time, a wave of new plant species emerged, presumably in response to the new climate. Interestingly, most Tertiary species that have been tracked through the fossil record did not disappear but remained relatively abundant despite the development of a much more unfavorable climate for species adapted to moist conditions. Here we find, by integrating paleobotanical, ecological, and phylogenetic analyses, that a large number of ancient Tertiary species in Mediterranean-climate ecosystems appear to have been preserved by the facilitative or “nurse” effects of modern Quaternary species. Our results indicate that these interdependent relationships among plants have played a central role in the preservation of the global biodiversity and provided a mechanism for stabilizing selection and the conservation of ecological traits over evolutionary time scales.
Sexual dysfunction in patients with psoriasis
Authors: TÜREL ERMERTCAN Aylin , TEMELTAŞ Gökhan , DEVECI Artuner , DINÇ Gönül , GÜLER H. Bilge , ÖZTÜRKCAN Serap
Published: October 2006

Psoriasis can have a significant impact upon sexual function. The aim of this study was to investigate sexual function in females and males with psoriasis and to evaluate whether coexistent depression has an additional negative effect on sexual function in these patients. A total of 66 female subjects (39 with psoriasis and 27 healthy volunteers as a control group) and 70 male subjects (39 with psoriasis and 31 healthy volunteers as a control group) were enrolled in the study. A Psoriasis Area and Severity Index (PASI) was used to determine the severity of psoriasis for the patient groups. The Female Sexual Function Index (FSFI) was used to assess female sexual function and the International Index of Erectile Function (IIEF) was used to evaluate male sexual function. Quality of life was assessed with the Dermatology Life Quality Index (DLQI). The diagnosis of depression was made according to the Structured Clinical Interview for DSM‐IV (SCID‐I) interview and Hamilton Depression Rate Scale (HDRS) was used for grading depression. FSFI total score was found to be significantly decreased in female psoriatic patients without depression and psoriatic patients plus depression compared with healthy controls (24.09 ± 5.33 vs. 24.25 ± 4.52 vs. 28.12 ± 3.48, respectively, p = 0.004). However, FSFI score was not significantly different between patients with psoriasis without depression and those with psoriasis plus depression (p > 0.05). IIEF total score was also found to be significantly decreased in male psoriasis without depression and psoriasis plus depression patients compared with healthy controls (54.21 ± 13.07 vs. 52.0 ± 14.73 vs. 61.69 ± 9.49, respectively, p = 0.023). The difference in IIEF scores between patients with psoriasis without depression and in those with psoriasis plus depression were not statistically significant (p > 0.05). The results of the study demonstrated that patients with psoriasis, especially females have distinct sexual dysfunction compared with healthy controls, and coexistent depression has no additional negative effect on sexual dysfunction in our patients. Patients with psoriasis should be evaluated in terms of sexual function in order to provide a better quality of life.
Nitazoxanide in the treatment of viral gastroenteritis: a randomized double‐blind placebo‐controlled clinical trial
Authors: ROSSIGNOL J.‐F. , EL‐GOHARY Y. M.
Published: October 2006

Background

Enteric viruses including noroviruses and rotavirus are leading causes of diarrhoeal disease and gastroenteritis worldwide, and there is no effective treatment.

Aim

To evaluate nitazoxanide, a thiazolide anti‐infective agent, in treating viral gastroenteritis in adults and adolescents.

Methods

50 out‐patients at least 12 years of age (mean 33.5 years) presenting with diarrhoea and stool‐positive by enzyme‐linked immunosorbent assay for norovirus, rotavirus or adenovirus were enrolled in a double‐blind, placebo‐controlled clinical trial. Patients were randomly assigned either nitazoxanide 500 mg or placebo twice daily for 3 days. The primary end point was time from first dose to resolution of symptoms. Analysis was modified intent‐to‐treat for 45 patients, excluding five patients with other identified enteropathogens at baseline.

Results

The median time from first dose to resolution of symptoms was 1.5 days (IQR: 0.5–2.5) for nitazoxanide‐treated patients and 2.5 days (IQR: 1.5–4.5) for the placebo group. Significant reductions in time to resolution of symptoms were observed for all patients analysed (P < 0.0001) and for subsets of patients with rotavirus (P = 0.0052) and norovirus (P = 0.0295). The number of patients with adenovirus (n = 5) was too small to draw any conclusion. No significant adverse events were reported.

Conclusions

Nitazoxanide may play an important role in managing viral gastroenteritis in adults.
An open‐label study of rabeprazole in patients with Zollinger–Ellison syndrome or idiopathic gastric acid hypersecretion
Authors: MOROCUTTI A. , MERROUCHE M. , BJAALAND T. , HUMPHRIES T. , MIGNON M.
Published: October 2006

Background

Omeprazole and lansoprazole are both of proven efficacy in the treatment of Zollinger–Ellison syndrome and idiopathic gastric acid hypersecretion. Rabeprazole, which has a similar mechanism of action, has not previously been studied in these diseases.

Aim

To determine the dose of rabeprazole that decreased basal acid output to safe levels in patients with Zollinger–Ellison syndrome or idiopathic gastric acid hypersecretion.

Methods

Patients with Zollinger–Ellison syndrome or idiopathic gastric acid hypersecretion were given rabeprazole 60 mg once daily for uncomplicated disease or 40 mg twice daily for complicated disease. Doses were titrated according to response and continued for 2 years. Efficacy was assessed primarily by measuring basal acid output.

Results

All patients had basal acid output before the next dose controlled to <10 mmol/h either at the starting dose or after minor dose titration. Control of acid output was maintained for 2 years. Consistent with this, most patients reported few gastrointestinal symptoms. Gastric biopsy showed no enterochromaffin‐like cell dysplasia or neoplasia.

Conclusions

Rabeprazole was an effective and well‐tolerated treatment for Zollinger–Ellison syndrome or idiopathic gastric acid hypersecretion, which reliably reduced gastric acid output to safe levels. Although a dose of 60 mg once daily was appropriate for most patients in this study, doses may need adjustment according to individual response.
An evaluation of ciclosporin and corticosteroids individually as adjuncts to plasma exchange in the treatment of thrombotic thrombocytopenic purpura
Authors: Cataland Spero R. , Jin Ming , Ferketich Amy K. , Kennedy Melanie S. , Kraut Eric H. , George James N. , Wu Haifeng M.
Published: October 2006

We present the results of two consecutively performed cohort studies that evaluated the clinical effects of corticosteroids or ciclosporin as an adjunct to plasma exchange (PE) for the treatment of an acute episode of thrombotic thrombocytopenic purpura (TTP). In comparing 12 corticosteroid‐treated patients with eight ciclosporin‐treated patients, none of the ciclosporin‐treated patients suffered an exacerbation or recurrence of TTP in the first 30 d after discontinuing PE compared with 6/10 (60%) of the corticosteroid‐treated patients (P = 0·042). These data suggest that ciclosporin may have advantages over corticosteroids as an adjunct to PE therapy in the initial treatment of idiopathic TTP.