bluuebunny/crossref_metadata_2025 huggingface dataset:
Ordering and single-file diffusion in colloidal systems
Authors: Herrera-Velarde Salvador , Zamudio-Ojeda Adalberto , Castañeda-Priego Ramón
Published: September 2010

The structural properties and the single-file diffusion in one-dimensional interacting colloidal systems are studied by means of Brownian dynamics simulations. We consider three types of particle interactions, namely, Weeks–Chandler–Andersen, screened Coulomb, and superparamagnetic potentials. We find that, regardless of the interaction potential, at low densities particles are distributed in a typical fluidlike structure and at higher densities or potential strengths become spatially correlated at long-distances. Particularly, our findings demonstrate that one-dimensional systems, with particles interacting repulsively, show common structural and dynamical behaviors at the boundary in which the degree of ordering changes dramatically; the main peak of the static structure factor becomes highly narrow with a height of Sc≈7, whereas the reduced mobility factor F, which is associated with the single-file diffusion at long-times or long wavelengths, reaches values F∗≈0.1. These features are analyzed and discussed in the context of a local order-disorder transition.
Ultrahigh-resolution spin-resolved photoemission spectrometer with a mini Mott detector
Authors: Souma S. , Takayama A. , Sugawara K. , Sato T. , Takahashi T.
Published: September 2010

We have developed an ultrahigh-resolution spin-resolved photoemission spectrometer with a highly efficient mini Mott detector and an intense xenon plasma discharge lamp. The spectrometer achieves the energy resolutions of 0.9 and 8 meV for non-spin-resolved and spin-resolved modes, respectively. Three-dimensional spin-polarization is determined by using a 90° electron deflector situated before the Mott detector. The performance of spectrometer is demonstrated by observation of a clear Rashba splitting of the Bi(111) surface states.
Laboratory experiments on multipolar vortices in a rotating fluid
Authors: Trieling R. R. , van Heijst G. J. F. , Kizner Z.
Published: September 2010

The instability properties of isolated monopolar vortices have been investigated experimentally and the corresponding multipolar quasisteady states have been compared with semianalytical vorticity-distributed solutions to the Euler equations in two dimensions. A novel experimental technique was introduced to generate unstable monopolar vortices whose nonlinear evolution resulted in the formation of multipolar vortices. Dye-visualization and particle imaging techniques revealed the existence of tripolar, quadrupolar, and pentapolar vortices. Also evidence was found of the onset of hexapolar and heptapolar vortices. The observed multipolar vortices were found to be unstable and generally broke up into multipolar vortices of lesser complexity. The characteristic flow properties of the quadrupolar vortex were in close agreement with the semianalytical model solutions. Higher-order multipolar vortices were observed to be susceptible to strong inertial oscillations.
Local temperature measurement in the vicinity of electromagnetically heated magnetite and gold nanoparticles
Authors: Gupta Amit , Kane Ravi S. , Borca-Tasciuc Diana-Andra
Published: September 2010

This paper describes a new technique employing fluorescent quantum dots as temperature probes for measuring the temperature rise in the proximity of nanoparticles heated by a radio frequency (rf) electromagnetic field. The remote heating of nanoparticles by an rf field is a promising approach to control biological transformations at the molecular level. In principle, the heat dissipated by each nanoparticle might produce a temperature increase in its proximity, facilitating a change in the molecules directly attached to it but not in the others. Although this method has been demonstrated to provide control over biological transformations, the proposed mechanism involves producing and maintaining large temperature differences across small distances, in the range of several degrees Celsius across tens of nanometers. Existing theories for heat generation and transfer in rf heated nanoparticle systems cannot account for these gradients. To better understand the limitations of local heating, the temperature in the vicinity of rf heated nanoparticles was measured. Dilute aqueous suspensions of gold and magnetite nanoparticles were remotely heated by an rf field between 600–800 kHz. Two systems were investigated: a control sample consisting of quantum dots mixed with nanoparticles and a solution of quantum dots covalently linked to nanoparticles. The temperature of the fluorescent probes represents the average temperature in the former and the local temperature in the later. For the experimental conditions employed in this study, the measured temperature rise in the vicinity of rf heated nanoparticles were similar to the average or “bulk” temperature, in agreement with theoretical predictions.
Slow and fast light in photorefractive GaAs–AlGaAs multiple quantum wells in transverse geometry
Authors: Bo Fang , Liu Ze , Gao Feng , Zhang Guoquan , Xu Jingjun
Published: September 2010

We show theoretically that, based on the dispersive phase coupling effect during the wave mixing process, both slow and fast light can be achieved in GaAs–AlGaAs photorefractive multiple quantum wells (PRMQWs) films applied with a transverse direct-current electric field. The general formula for the group velocity of the diffracted beams in the Raman–Nath regime during the wave mixing process in a nonlinear thin film is derived and is then applied to the case of the PRMQWs films in the transverse geometry. The simulation results in the transverse-geometry PRMQWs films show that the group velocity and bandwidth of slow light can be on the order of centimeter per second and 100 kHz, respectively. The extremely low group velocity and the relatively broad bandwidth are mainly originated from the strong quadratic electro-optic effect and the fast response rate of the PRMQWs films, respectively. Our results show that the delay-bandwidth product of slow light can be significantly improved in PRMQWs films as compared to the reported results in other photorefractive materials.
Single crystalline Sc2O3/Y2O3 heterostructures as novel engineered buffer approach for GaN integration on Si (111)
Authors: Tarnawska L. , Giussani A. , Zaumseil P. , Schubert M. A. , Paszkiewicz R. , Brandt O. , Storck P. , Schroeder T.
Published: September 2010

The preparation of GaN virtual substrates on Si wafers via buffer layers is intensively pursued for high power/high frequency electronics as well as optoelectronics applications. Here, GaN is integrated on the Si platform by a novel engineered bilayer oxide buffer, namely, Sc2O3/Y2O3, which gradually reduces the lattice misfit of ∼−17% between GaN and Si. Single crystalline GaN(0001)/Sc2O3(111)/Y2O3(111)/Si(111) heterostructures were prepared by molecular beam epitaxy and characterized ex situ by various techniques. Laboratory-based x-ray diffraction shows that the epitaxial Sc2O3 grows fully relaxed on the Y2O3/Si(111) support, creating a high quality template for subsequent GaN overgrowth. The high structural quality of the Sc2O3 film is demonstrated by the fact that the concentration of extended planar defects in the preferred {111} slip planes is below the detection limit of synchrotron based diffuse x-ray scattering studies. Transmission electron microscopy (TEM) analysis reveal that the full relaxation of the −7% lattice misfit between the isomorphic oxides is achieved by a network of misfit dislocations at the Sc2O3/Y2O3 interface. X-ray reflectivity and TEM prove that closed epitaxial GaN layers as thin as 30 nm can be grown on these templates. Finally, the GaN thin film quality is studied using a detailed Williamson–Hall analysis.
Energy band structure of the single crystalline MgO/n-Ge(001) heterojunction determined by x-ray photoelectron spectroscopy
Authors: Jeon Kun-Rok , Lee Sang-Jun , Park Chang-Yup , Lee Hun-Sung , Shin Sung-Chul
Published: September 2010

We report the energy band structure of the single crystalline MgO/n-Ge(001) heterojunction characterized by x-ray photoelectron spectroscopy. The valence band offset of ΔEV=3.64±0.07 eV with a 1.49±0.02 eV band bending was obtained. Given the experimental band gap of MgO (7.83 eV), a type-I band alignment with a conduction band offset of ΔEC=3.52±0.07 eV is found. The band alignment of the MgO/n-Ge heterojunction including the large band bending was analyzed by a theoretical model taking into account the formation of the interface dipole.
Charge transfer between epitaxial graphene and silicon carbide
Authors: Kopylov Sergey , Tzalenchuk Alexander , Kubatkin Sergey , Fal’ko Vladimir I.
Published: September 2010

We analyze doping of graphene grown on SiC in two models which differ by the source of charge transferred to graphene, namely, from SiC surface and from bulk donors. For each of the two models, we find the maximum electron density induced in monolayer and bilayer graphene, which is determined by the difference between the work function for electrons in pristine graphene and donor states on/in SiC, and analyze the responsivity of graphene to the density variation by means of electrostatic gates.
New Products
Authors: Mandelis Andreas
Published: September 2010

In order to supplement manufacturers’ information this Department will welcome the submission by our readers of brief communications reporting measurements on the physical properties of materials which supersede earlier data or suggest new research applications.
Lattice site location of optical centers in GaN:Eu light emitting diode material grown by organometallic vapor phase epitaxy
Authors: Lorenz K. , Alves E. , Roqan I. S. , O’Donnell K. P. , Nishikawa A. , Fujiwara Y. , Boćkowski M.
Published: September 2010

Eu-doped GaN was grown by organometallic vapor phase epitaxy at temperatures from 900 to 1100 °C. Eu incorporation is influenced by temperature with the highest concentration found for growth at 1000 °C. In all samples, Eu is incorporated entirely on substitutional Ga sites with a slight displacement which is highest (∼0.2 Å) in the sample grown at 900 °C and mainly directed along the c-axis. The major optical Eu3+ centers are identical for in situ doped and ion-implanted samples after high temperature and pressure annealing. The dominant Eu3+ luminescence lines are attributed to isolated, substitutional Eu.
Emission mechanisms of passivated single n-ZnO:In/i-ZnO/p-GaN-heterostructured nanorod light-emitting diodes
Authors: Lee Hsin-Ying , Lee Ching-Ting , Yan Jheng-Tai
Published: September 2010

The single n-ZnO:In/i-ZnO/p-GaN-heterostructured n-i-p nanorod was deposited using a vapor cooling condensation system. The photoelectrochemical system was used to directly passivate the nanorod sidewall surface with a Zn(OH)2 layer. The electrical performance of the passivated and unpassivated single nanorod was measured using a conductive atomic force microscopy. The resulting nanorod light-emitting diodes were investigated for understanding the relevant light emission mechanisms. Since the nonradiative recombination centers, native defects, and dangling bonds existed on the nanorod sidewall surface were effectively passivated, the resultant surface leakage current was reduced and the near-band emission intensity of the nanorod light-emitting diode was increased accordingly.
Imaging of multinuclear spin system (I>1/2) in semiconductor microstructures using longitudinal-magnetization-detection nuclear magnetic resonance
Authors: Kawamura Takashi , Yusa Go
Published: September 2010

We propose a method for detecting the local nuclear spin in semiconductor microstructures using a nuclear magnetic resonance technique that detects the longitudinal magnetization (Mz) of nuclear spins. This technique involves manipulating the nuclear spin by applying a particular sequence of pulsed gradient and homogeneous magnetic fields. By calculating the time evolution of the density operators, we demonstrate that the local change in magnetization can be extracted from the change in the magnetization of the whole system. This technique is suitable for investigating microscopic semiconductor systems with a multinuclear spin of I>1/2.
Implementing TiO2 as gate dielectric for Ge-channel complementary metal-oxide-semiconductor devices by using HfO2/GeO2 interlayer
Authors: Xie Qi , Deduytsche Davy , Schaekers Marc , Caymax Matty , Delabie Annelies , Qu Xin-Ping , Detavernier Christophe
Published: September 2010

The electrical properties of plasma-enhanced atomic-layer-deposited (PE-ALD) TiO2 as gate dielectric were investigated for germanium-channel complementary metal-oxide-semiconductor capacitors by using ultrathin in situ HfO2/GeO2 interlayers. TiO2 grown by PE-ALD exhibited a k value of 50±5. An equivalent oxide thickness of 0.9 nm was obtained for the TiO2(3 nm)/HfO2(1.2 nm)/GeO2(0.7 nm)/Ge capacitor with very low leakage current density of 2×10−7 A/cm2 at VFB±1 V. Capacitance-voltage hysteresis was below 30 mV for the TiO2/HfO2/GeO2/Ge capacitors. Relatively low minimum density of interface states, Dit ∼5×1011 eV−1 cm−2 was obtained, suggesting the potential of HfO2/GeO2 passivation layer for the application of TiO2 as gate dielectric for both p- and n-type Ge channels.
Centriolar Association of ALMS1 and Likely Centrosomal Functions of the ALMS Motif–containing Proteins C10orf90 and KIAA1731
Authors: Knorz Victoria J. , Spalluto Cosma , Lessard Mark , Purvis Tracey L. , Adigun Fiona F. , Collin Gayle B. , Hanley Neil A. , Wilson David I. , Hearn Thomas
Published: September 2010

Mutations in the human gene ALMS1 cause Alström syndrome, a rare progressive condition characterized by neurosensory degeneration and metabolic defects. ALMS1 protein localizes to the centrosome and has been implicated in the assembly and/or maintenance of primary cilia; however its precise function, distribution within the centrosome, and mechanism of centrosomal recruitment are unknown. The C-terminus of ALMS1 contains a region with similarity to the uncharacterized human protein C10orf90, termed the ALMS motif. Here, we show that a third human protein, the candidate centrosomal protein KIAA1731, contains an ALMS motif and that exogenously expressed KIAA1731 and C10orf90 localize to the centrosome. However, based on deletion analysis of ALMS1, the ALMS motif appears unlikely to be critical for centrosomal targeting. RNAi analyses suggest that C10orf90 and KIAA1731 have roles in primary cilium assembly and centriole formation/stability, respectively. We also show that ALMS1 localizes specifically to the proximal ends of centrioles and basal bodies, where it colocalizes with the centrosome cohesion protein C-Nap1. RNAi analysis reveals markedly diminished centrosomal levels of C-Nap1 and compromised cohesion of parental centrioles in ALMS1-depleted cells. In summary, these data suggest centrosomal functions for C10orf90 and KIAA1731 and new centriole-related functions for ALMS1.
Adenomatous Polyposis Coli and Hypoxia-inducible Factor-1α Have an Antagonistic Connection
Authors: Newton Ian P. , Kenneth Niall S. , Appleton Paul L. , Näthke Inke , Rocha Sonia
Published: September 2010

The tumor suppressor adenomatous polyposis coli (APC) is mutated in the majority of colorectal cancers and is best known for its role as a scaffold in a Wnt-regulated protein complex that determines the availability of β-catenin. Another common feature of solid tumors is the presence of hypoxia as indicated by the up-regulation of hypoxia-inducible factors (HIFs) such as HIF-1α. Here, we demonstrate a novel link between APC and hypoxia and show that APC and HIF-1α antagonize each other. Hypoxia results in reduced levels of APC mRNA and protein via a HIF-1α–dependent mechanism. HIF-1α represses the APC gene via a functional hypoxia-responsive element on the APC promoter. In contrast, APC-mediated repression of HIF-1α requires wild-type APC, low levels of β-catenin, and nuclear factor-κB activity. These results reveal down-regulation of APC as a new mechanism that contributes to the survival advantage induced by hypoxia and also show that loss of APC mutations produces a survival advantage by mimicking hypoxic conditions.
Dynamics of Multiple Nuclei inAshbya gossypiiHyphae Depend on the Control of Cytoplasmic Microtubules Length by Bik1, Kip2, Kip3, and Not on a Capture/Shrinkage Mechanism
Authors: Grava Sandrine , Philippsen Peter
Published: September 2010

Ashbya gossypii has a budding yeast-like genome but grows exclusively as multinucleated hyphae. In contrast to budding yeast where positioning of nuclei at the bud neck is a major function of cytoplasmic microtubules (cMTs), A. gossypii nuclei are constantly in motion and positioning is not an issue. To investigate the role of cMTs in nuclear oscillation and bypassing, we constructed mutants potentially affecting cMT lengths. Hyphae lacking the plus (+)end marker Bik1 or the kinesin Kip2 cannot polymerize long cMTs and lose wild-type nuclear movements. Interestingly, hyphae lacking the kinesin Kip3 display longer cMTs concomitant with increased nuclear oscillation and bypassing. Polymerization and depolymerization rates of cMTs are 3 times higher in A. gossypii than in budding yeast and cMT catastrophes are rare. Growing cMTs slide along the hyphal cortex and exert pulling forces on nuclei. Surprisingly, a capture/shrinkage mechanism seems to be absent in A. gossypii. cMTs reaching a hyphal tip do not shrink, and cMT +ends accumulate in hyphal tips. Thus, differences in cMT dynamics and length control between budding yeast and A. gossypii are key elements in the adaptation of the cMT cytoskeleton to much longer cells and much higher degrees of nuclear mobilities.
Dual Functions of Yeast tRNA Ligase in the Unfolded Protein Response: Unconventional Cytoplasmic Splicing ofHAC1Pre-mRNA Is Not Sufficient to Release Translational Attenuation
Authors: Mori Takao , Ogasawara Chiharu , Inada Toshifumi , Englert Markus , Beier Hildburg , Takezawa Mine , Endo Toshiya , Yoshihisa Tohru
Published: September 2010

The unfolded protein response (UPR) is an essential signal transduction to cope with protein-folding stress in the endoplasmic reticulum. In the yeast UPR, the unconventional splicing of HAC1 mRNA is a key step. Translation of HAC1 pre-mRNA (HAC1umRNA) is attenuated on polysomes and restarted only after splicing upon the UPR. However, the precise mechanism of this restart remained unclear. Here we show that yeast tRNA ligase (Rlg1p/Trl1p) acting on HAC1 ligation has an unexpected role in HAC1 translation. An RLG1 homologue from Arabidopsis thaliana (AtRLG1) substitutes for yeast RLG1 in tRNA splicing but not in the UPR. Surprisingly, AtRlg1p ligates HAC1 exons, but the spliced mRNA (HAC1imRNA) is not translated efficiently. In the AtRLG1 cells, the HAC1 intron is circularized after splicing and remains associated on polysomes, impairing relief of the translational repression of HAC1imRNA. Furthermore, the HAC1 5′ UTR itself enables yeast Rlg1p to regulate translation of the following ORF. RNA IP revealed that yeast Rlg1p is integrated in HAC1 mRNP, before Ire1p cleaves HAC1umRNA. These results indicate that the splicing and the release of translational attenuation of HAC1 mRNA are separable steps and that Rlg1p has pivotal roles in both of these steps.
Genetic variation in resistance, but not tolerance, to a protozoan parasite in the monarch butterfly
Authors: Lefèvre Thierry , Williams Amanda Jo , de Roode Jacobus C.
Published: September 2010

Natural selection should strongly favour hosts that can protect themselves against parasites. Most studies on animals so far have focused on resistance, a series of mechanisms through which hosts prevent infection, reduce parasite growth or clear infection. However, animals may instead evolve tolerance, a defence mechanism by which hosts do not reduce parasite infection or growth, but instead alleviate the negative fitness consequences of such infection and growth. Here, we studied genetic variation in resistance and tolerance in the monarch butterfly (Danaus plexippus) to its naturally occurring protozoan parasite,Ophryocystis elektroscirrha. We exposed 560 monarch larvae of 19 different family lines to one of five different parasite inoculation doses (0, 1, 5, 10 and 100 infective spores) to create a range of parasite loads in infected butterflies. We then used two proxies of host fitness (adult lifespan and body mass) to quantify: (i) qualitative resistance (the ability to prevent infection; also known as avoidance or anti-infection resistance); (ii) quantitative resistance (the ability to limit parasite growth upon infection; also known as control or anti-growth resistance); and (iii) tolerance (the ability to maintain fitness with increasing parasite infection intensity). We found significant differences among host families in qualitative and quantitative resistance, indicating genetic variation in resistance. However, we found no genetic variation in tolerance. This may indicate that all butterflies in our studied population have evolved maximum tolerance, as predicted by some theoretical models.
Leaving home ain't easy: non-local seed dispersal is only evolutionarily stable in highly unpredictable environments
Authors: Snyder Robin E.
Published: September 2010

It is widely understood that in the presence of asynchronous environmental variation, seeds disperse to escape disturbances, avoid crowding or colonize newly favourable habitat before a superior competitor can arrive. If seeds are dispersing for any of these reasons, it seems intuitive that they should travel far enough to reach conditions uncorrelated with their natal environment: why ‘escape in space’ only to land somewhere more or less like where they started? However, in this paper, I present a series of mathematical experiments which show that the evolutionarily stable mean dispersal distance remains well short of the spatial correlation length of the environmental variation, regardless of disturbance severity, coevolution with a superior competitor or the presence of a small fraction of seeds which travel well beyond the mean distance. Non-local dispersal arises only as part of a polymorphism that evolves when favourable conditions are fleeting. To the degree that non-local dispersal is a response to environmental variation, it appears to be a response to environmental unpredictability.
Rapid change in host use of the common cuckooCuculus canoruslinked to climate change
Authors: Møller A. P. , Saino N. , Adamík P. , Ambrosini R. , Antonov A. , Campobello D. , Stokke B. G. , Fossøy F. , Lehikoinen E. , Martin-Vivaldi M. , Moksnes A. , Moskat C. , Røskaft E. , Rubolini D. , Schulze-Hagen K. , Soler M. , Shykoff J. A.
Published: September 2010

Parasites require synchrony with their hosts so if host timing changes with climate change, some parasites may decline and eventually go extinct. Residents and short-distance migrant hosts of the brood parasitic common cuckoo,Cuculus canorus, have advanced their phenology in response to climate change more than long-distance migrants, including the cuckoo itself. Because different parts of Europe show different degrees of climate change, we predicted that use of residents or short-distance migrants as hosts should have declined in areas with greater increase in spring temperature. Comparing relative frequency of parasitism of the two host categories in 23 European countries before and after 1990, when spring temperatures in many areas had started to increase, we found that relative parasitism of residents and short-distance migrants decreased. This change in host use was positively related to increase in spring temperature, consistent with the prediction that relative change in phenology for different migrant classes drives host-use patterns. These findings are consistent with the hypothesis that climate change affects the relative abundance of different host races of the common cuckoo.
Plant nutrient supply determines competition between phytophagous insects
Authors: Staley Joanna T. , Stafford David B. , Green Emma R. , Leather Simon R. , Rossiter John T. , Poppy Guy M. , Wright Denis J.
Published: September 2010

Indirect competition is often mediated by plant responses to herbivore feeding damage and is common among phytophagous insect species. Plant-mediated responses may be altered by abiotic conditions such as nutrient supply, which can affect plant growth, morphology, and the concentration of primary and secondary metabolites. Nutrient supply can be manipulated by the type and amount of fertilizer applied to a plant.Brassica oleraceaplants were grown in several types of fertilizer, including those commonly used in sustainable and conventional agricultural systems. The occurrence of indirect competition between two phytophagous species from different feeding guilds (a phloem-feeder and leaf-chewer) was assessed. The leaf-chewer reduced aphid populations on plants growing in most fertilizer treatments, but not on those in the ammonium nitrate fertilizer treatment, which caused the highest concentration of foliar nitrogen. The potential consequences of our findings are discussed for phytophagous species in conventional and sustainable agricultural systems.
Sometimes slower is better: slow-exploring birds are more sensitive to changes in a vocal discrimination task
Authors: Guillette Lauren M. , Reddon Adam R. , Hoeschele Marisa , Sturdy Christopher B.
Published: September 2010

Animal personality, defined as consistent individual differences across context and time, has attracted much recent research interest in the study of animal behaviour. More recently, this field has begun to examine how such variation arose and is maintained within populations. The habitat-dependent selection hypothesis, which posits that animals with differing personality types may fare better (i.e. have a fitness advantage) in different habitats, suggests one possible mechanism. In the current experiment, we tested whether slow- and fast-exploring black-capped chickadees (Poecile atricapillus), determined by performance in a novel environment exploration task, perform differentially when the demands of an acoustic operant discrimination (cognitive) task were altered following successful task acquisition. We found that slow-exploring birds learn to reverse previously learned natural category rules more quickly than faster exploring conspecifics. In accordance with the habitat-dependent selection hypothesis, and previous work with great tits (Parus major), a close relative of the black-capped chickadee, our results suggest that fast-exploring birds may perform better in stable, predictable environments where forming a routine is advantageous, while slow-exploring birds are favoured in unstable, unpredictable environments, where task demands often change. Our results also support a hypothesis derived from previous work with great tits; slow-exploring birds may be generally more flexible (i.e. able to modify their behaviour in accordance with changes in environmental stimuli) in some learning tasks.
Testing the Vision: Preschool Settings as Places for Meeting, Bonding and Bridging
Authors: Thorpe Karen , Staton Sally , Morgan Robert , Danby Susan , Tayler Collette
Published: September 2010

The OECD (2006 Starting Strong II: Early Childhood Education and Care. OECD Publishing: Paris) envisions early childhood education and care settings as meeting places for diverse social groups; places that build social capital. This vision was assessed in a comparison of three preschools types: full‐fee paying, subsidised‐fee and publicly funded. The social composition within each was examined and the connectedness of the children (n = 472) who attended compared. Publicly funded preschools had more socially diverse populations. The quantity of social connectedness did not differ but children in publicly funded preschools described higher quality social relationships. Not all preschool settings are socially diverse but, where they are, the quality of relationships is highest.
Low endotoxic activity of lipopolysaccharides isolated from Bradyrhizobium, Mesorhizobium, and Azospirillum strains
Authors: Komaniecka Iwona , Zdzisinska Barbara , Kandefer‐Szerszen Martyna , Choma Adam
Published: September 2010

The endotoxic activities of lipopolysaccharides (LPS) isolated from different strains of rhizobia and rhizobacteria (Bradyrhizobium, Mesorhizobium, and Azospirillum) were compared to those of Salmonella enterica sv. Typhimurium LPS. The biological activity of all the examined preparations, measured as Limulus lysate gelation, production of tumor necrosis factor (TNF), interleukin‐1β (IL‐1β), and interleukin‐6 (IL‐6), and nitrogen oxide (NO) induction in human myelomonocytic cells (line THP‐1), was considerably lower than that of the reference enterobacterial endotoxin. Among the rhizobial lipopolysaccharides, the activities of Mesorhizobium huakuii and Azospirillum lipoferum LPSs were higher than those of the LPS preparations from five strains of Bradyrhizobium. The weak endotoxic activity of the examined preparations was correlated with differences in lipid A structure compared to Salmonella.
Spatial distribution of intraperitoneally administrated paclitaxel nanoparticles solubilized with poly (2‐methacryloxyethyl phosphorylcholine‐con‐butyl methacrylate) in peritoneal metastatic nodules
Authors: Kamei Takao , Kitayama Joji , Yamaguchi Hironori , Soma Daisuke , Emoto Shigenobu , Konno Tomohiro , Ishihara Kazuhiko , Ishigami Hironori , Kaisaki Shoichi , Nagawa Hirokazu
Published: September 2010

Intraperitoneal (i.p.) administration of paclitaxel nanoparticles (PTX‐30W) prepared by solubulization with the amphiphilic copolymer of 2‐methacryloxyethyl phosphorylcholine andn‐butyl methacrylate can efficiently suppress the growth of peritoneal metastasis. In this study, we characterized the drug distribution of i.p. injected PTX‐30W in peritoneal tumor and liver in a mouse model using MKN45, human gastric cancer cells. Oregon green‐conjugated PTX‐30W showed perivascular accumulation in MKN45 tumor in the peritoneum at 24 h after intravenous (i.v.) injection; however, the amount of PTX in tumor was markedly less than that in liver. In contrast, a larger amount of PTX accumulated in the peripheral area of disseminated nodules at 1 h after i.p. injection and the area gradually enlarged. The depth of PTX infiltration reached 1 mm from the tumor surface at 48 h after i.p. injection, and the fluorescence intensity was markedly greater than that in liver. Interestingly, i.p. injected PTX preferentially accumulated in relatively hypovascular areas, and many tumor cells in the vicinity of PTX accumulation showed apoptosis. This unique accumulation pattern and lesser washout in hypovascular areas are thought to be attributable to the superior penetrating activity of PTX‐30W, and thus, PTX‐30W is considered to be highly suitable for i.p. chemotherapy for peritoneal dissemination. (Cancer Sci2011; 102: 200–205)
Nationwide survey and establishment of a clinical database for gastrointestinal surgery in Japan: Targeting integration of a cancer registration system and improving the outcome of cancer treatment
Authors: Suzuki Hiroyuki , Gotoh Mitsukazu , Sugihara Kenichi , Kitagawa Yuko , Kimura Wataru , Kondo Satoshi , Shimada Mitsuo , Tomita Naohiro , Nakagoe Tohru , Hashimoto Hideki , Baba Hideo , Miyata Hiroaki , Motomura Noboru
Published: September 2010

As there was no nationwide database for gastrointestinal surgery in Japan at the time, in 2006, a Clinical Database Committee was established in the Japanese Society of Gastrointestinal Surgery (JSGS) to create a clinical database in Japan. The Committee first organized preliminary nationwide Japanese surveys in gastrointestinal surgery in 2006 and 2007. Data from more than 770 000 patients were accumulated from these web‐based surveys, including 333 627 patients in 1039 institutions in 2006 and 440 230 patients in 1464 institutions in 2007. The mortality rate was stratified by organ, surgical procedure and hospital volume without using risk‐adjustment techniques. The overall mortality rate was 0.95% in the 2006 survey and 0.92% in the 2007 survey. The organ‐based analysis found that the mortality rates were almost similar in 2006 and 2007. Hospital volume influenced the mortality rate in six major surgical procedures, namely esophagectomy, gastrectomy, total gastrectomy, low anterior rectal resection, hepatic resection and pancreaticoduodenectomy. A risk reduction of 30–80% was noted in each surgical procedure, at least in our non‐risk‐adjusted analysis, in hospitals with a high volume of operations. These preliminary surveys indicate that hospital volume might influence the mortality rate after major abdominal surgery. Further analysis using risk‐adjustment techniques should be conducted to understand the specific contribution of hospital volume to surgical mortality. A nationwide database of patients who have undergone gastrointestinal surgery and risk‐adjustment analysis of the data are currently planned in Japan. (Cancer Sci 2011; 102: 226–230)
Dissecting the T‐cell response to hordeins in coeliac disease can develop barley with reduced immunotoxicity
Authors: Tanner G. J. , Howitt C. A. , Forrester R. I. , Campbell P. M. , Tye‐Din J. A. , Anderson R. P.
Published: September 2010

Aliment Pharmacol Ther 2010; 32: 1184–1191

Background  Wheat, rye and barley prolamins are toxic to patients with coeliac disease. Barley is diploid with pure inbred cultivars available, and is attractive for genetic approaches to detoxification.

Aim  To identify barley hordein fractions which activated the interferon‐γ (IFN‐γ) secreting peripheral blood T‐cells from coeliac volunteers, and compare immunotoxicity of hordeins from experimental barley lines.

Methods  To reactivate a T‐cell response to hordein, volunteers underwent a 3‐day oral barley challenge. Peripheral blood mononuclear cells (PBMC) were isolated from twenty‐one HLA DQ2+ patients with confirmed coeliac disease. IFN‐γ ELISpot assays enumerated T‐cells activated by purified prolamins and positive controls.

Results  Hordein‐specific T‐cells were induced by oral barley challenge. All prolamin fractions were immunotoxic, but D‐ and C‐hordeins were most active. Barley lines lacking B‐ and C‐hordeins had a 5‐fold reduced hordein‐content, and immunotoxicity of hordein extracts were reduced 20‐fold compared with wild‐type barley.

Conclusions  In vivo oral barley challenge offers a convenient and rapid approach to test the immunotoxicity of small amounts of purified hordeins using fresh T‐cells from patients in high throughput overnight assays. Barley lines that did not accumulate B‐ and C‐hordeins were viable, yet had substantially reduced immunotoxicity. Creation of hordein‐free barley may therefore be possible.
The epidemiology and clinical features of portal vein thrombosis: a multicentre study
Authors: Rajani R. , Björnsson E. , Bergquist A. , Danielsson Å. , Gustavsson A. , Grip O. , Melin T. , Sangfelt P. , Wallerstedt S. , Almer S.
Published: September 2010

Aliment Pharmacol Ther 2010; 32: 1154–1162

Background  Reliable epidemiological data for portal vein thrombosis are lacking.

Aims  To investigate the incidence, prevalence and survival rates for patients with portal vein thrombosis.

Methods  Retrospective multicentre study of all patients registered with the diagnosis of portal vein thrombosis between 1995 and 2004.

Results  A total of 173 patients (median age 57 years, 93 men) with portal vein thrombosis were identified and followed up for a median of 2.5 years (range 0–9.7). The mean age‐standardized incidence and prevalence rates were 0.7 per 100 000 per year and 3.7 per 100 000 inhabitants, respectively. Liver disease was present in 70 patients (40%), malignancy in 27%, thrombophilic factors in 22% and myeloproliferative disorders in 11%. Two or more risk factors were identified in 80 patients (46%). At diagnosis, 65% were put on anticoagulant therapy. Thrombolysis, TIPS, surgical shunting and liver transplantation were performed in 6, 3, 2 and 8 patients, respectively. The overall survival at 1 year and 5 years was 69% and 54%. In the absence of malignancy and cirrhosis, the survival was 92% and 76%, respectively.

Conclusions  The incidence and prevalence rates of portal vein thrombosis were 0.7 per 100 000 inhabitants per year and 3.7 per 100 000 inhabitants, respectively. Concurrent prothrombotic risk factors are common. The prognosis is variable and highly dependent on underlying disease.
Additional benefit of procalcitonin to C‐reactive protein to assess disease activity and severity in Crohn’s disease
Authors: Oussalah A. , Laurent V. , Bruot O. , Guéant J.‐L. , Régent D. , Bigard M.‐A. , Peyrin‐Biroulet L.
Published: September 2010

Aliment Pharmacol Ther 2010; 32: 1135–1144

Background  Serum procalcitonin level may reflect non‐infectious inflammation.

Aim  To assess the correlation of serum procalcitonin level with clinical, biological, endoscopic and radiological markers of disease activity in inflammatory bowel diseases (IBD), and to evaluate the additional diagnostic benefit of measuring serum procalcitonin level to that of C‐reactive protein (CRP) for disease activity appraisal.

Methods  We performed a prospective observational study. Spearman’s rank correlation and receiver operating characteristic analysis were used to evaluate correlation and diagnostic accuracy respectively.

Results  In Crohn’s disease (CD) (n = 30), serum procalcitonin level was strongly correlated with clinical, biological, endoscopic and radiological disease activity markers. In CD, the serum procalcitonin level >0.14 μg/L demonstrated a high accuracy for detecting severe disease (Sensitivity = 100%; Specificity = 96%; AUROC = 0.963; P = 0.0001). The diagnostic accuracy of the ‘serum procalcitonin level‐CRP strategy’ (CRP >5 mg/L and serum procalcitonin level >0.05 μg/L) was significantly superior to that of CRP alone for diagnosing severe CD (AUROC = 0.783 vs. 0.674; P = 0.01). In ulcerative colitis (UC) (n = 27), serum procalcitonin level was correlated with CRP and with endoscopic and radiological disease activity markers.

Conclusions  In CD, the serum procalcitonin level was correlated with all disease activity markers and a cut‐off of 0.14 μg/L could distinguish severe forms of the disease. The ‘serum procalcitonin level‐CRP strategy’ was superior to CRP alone for diagnosing active or severe CD.
A homozygous inactivating calcium‐sensing receptor mutation, Pro339Thr, is associated with isolated primary hyperparathyroidism: correlation between location of mutations and severity of hypercalcaemia
Authors: Hannan Fadil M. , Nesbit M. A. , Christie Paul T. , Lissens Willy , Van der Schueren Bart , Bex Marie , Bouillon Roger , Thakker Rajesh V.
Published: September 2010

Background  Inactivating mutations of the calcium‐sensing receptor (CaSR), a G‐protein‐coupled receptor with extracellular (ECD), transmembrane (TMD) and intracellular (ICD) domains, cause familial hypocalciuric hypercalcaemia, neonatal severe primary hyperparathyroidism and occasionally primary hyperparathyroidism in adults.

Objective  To investigate a patient with typical symptomatic primary hyperparathyroidism for CaSR abnormalities.

Patient and design  A 51‐year‐old woman with primary hyperparathyroidism was investigated for CaSR abnormalities as her severe hypercalcaemia (3·75 mm) persisted after the removal of two large parathyroid adenomas and she was the daughter of normocalcaemic consanguineous parents. Following informed consent, CASR mutational analysis was undertaken using leucocyte DNA. Wild‐type and mutant CaSR constructs were expressed in human embryonic kidney (HEK) 293 cells and assessed by measuring their intracellular calcium responses to changes in extracellular calcium. Clinical data were pooled with previous studies to search for genotype–phenotype correlations.

Results  The proband was homozygous for a Pro339Thr CaSR missense mutation, located in the ECD, and her normocalcaemic relatives were heterozygous. The mutant Thr339 CaSR had a rightward shift in its dose–response curve with a significantly higher EC50 = 3·18 mm ± 0·19 compared to the wild‐type EC50 =  2·16 mm ± 0·1 (P < 0·01), consistent with a loss‐of‐function mutation. An analysis of CaSR mutations in patients with primary hyperparathyroidism revealed that those of the ECD were associated with a significantly greater hypercalcaemia that was less likely to be corrected after removal of the parathyroid tumours.

Conclusions  A CaSR missense mutation causing a loss‐of‐receptor‐function can cause symptomatic primary hyperparathyroidism in adulthood.
Ethnic differences in Rotterdam criteria and metabolic risk factors in a multiethnic group of women with PCOS studied in Denmark
Authors: Glintborg Dorte , Mumm Hanne , Hougaard David , Ravn Pernille , Andersen Marianne
Published: September 2010

Objective  Clinical manifestations and metabolic risk factors may differ in ethnic subgroups of patients with polycystic ovary syndrome (PCOS).

Design  Retrospective trans‐sectional study.

Patients  One thousand and two premenopausal women with the diagnoses hirsutism or PCOS were divided according to ethnicity: Caucasian (CA, n = 784), Middle East (ME, n = 190), Asian (n = 14) and others (n = 14).

Measurements  Clinical evaluation (hirsutism, BMI, waist, blood pressure), hormone analyses (testosterone, sex hormone–binding globulin, prolactin, lipids, insulin, glucose) and transvaginal ultrasound were performed. Oral glucose tolerance tests (OGTT) (n = 499) and ACTH tests (n = 434) were performed in a subgroup of patients.

Results (CA vs ME women)  CA women were older [32(25–37) vs 25(18–32) years, median (quartiles)] and had increased BMI compared to ME women. After correcting for age and BMI, CA women were less hirsute, but had increased testosterone levels compared to ME women. The Rotterdam criteria were fulfilled in 56% of both populations, but PCO was diagnosed in 47% CA vs 29% ME women, P < 0·01. CA women had increased blood pressure and smoked at a higher frequency (40 vs 23%), whereas area under the curve for insulin during OGTT was decreased, all P < 0·001. Prolactin levels were significantly lower in CA women compared to ME women [7(5–10) vs 9(6–12) μg/l] and were inversely associated with smoking status.

Conclusion  CA women had a more adverse cardiovascular profile than ME women, whereas insulin sensitivity was higher. The prevalence of the individual Rotterdam criteria differed significantly in the two study populations.
Outcomes of surgical treatment for nonfunctioning pituitary adenomas: a systematic review and meta‐analysis
Authors: Murad Mohammad Hassan , Fernández‐Balsells M. M. , Barwise Amelia , Gallegos‐Orozco Juan F. , Paul Anu , Lane Melanie A. , Lampropulos Julianna F. , Natividad Inés , Perestelo‐Pérez Lilisbeth , Ponce de León‐Lovatón Paula G. , Albuquerque Felipe N. , Carey Jantey , Erwin Patricia J. , Montori Victor M.
Published: September 2010

Background  Surgery is commonly used in the management of pituitary nonfunctioning adenomas (NFPA). The goal of this systematic review and meta‐analysis is to evaluate the effect of surgery on mortality, surgical complications, pituitary function and vision.

Methods  We searched MEDLINE, EMBASE and Cochrane CENTRAL, queried experts and reviewed the reference list of included publications. Eligible studies were comparative and noncomparative longitudinal studies that enroled patients with NFPA who underwent surgery (alone or in combination with other therapies). Reviewers, working independently and in duplicate, determined study eligibility with adequate reproducibility and extracted descriptive, quality and outcome data. Risks, relative risks (RR) and 95% confidence intervals (CIs) were estimated from each study and pooled using random‐effects meta‐analysis.

Results  Most included studies were uncontrolled case series in which patients received a combination of surgery and radiotherapy. The overall quality of the evidence was very low. Median follow‐up was 4·29 years. When surgery was not combined with radiotherapy, there was an increased risk of tumour recurrence (RR 1·97; 95% CI, 1·15–3·35). Complications were more likely with the transcranial than with the transsphenoidal approach (mortality RR 4·89; 95% CI, 3·15–6·47; new anterior pituitary deficits RR 4·90; 95% CI, 2·94–7·82; and persistent diabetes insipidus RR 2·50; 95% CI, 1·05–5·35). Overall, transsphenoidal surgery had fairly low perioperative mortality (≤1%) and low complication rate (≤5% for all patient‐important outcomes), but only less than a third of the patients had improvement in pituitary function.

Conclusions  Observational evidence supports the association between a combined approach of transsphenoidal surgery with radiotherapy and improvements in visual field defects and reduction in tumour recurrence.
From molecules to living systems: historical and contemporary issues in oxidative stress and antioxidant ecology
Authors: Costantini David , Rowe Melissah , Butler Michael W. , McGraw Kevin J.
Published: September 2010

1. Initial work on oxidative stress and antioxidant defences described basic chemical and biochemical properties and processes and applied this information to issues of animal health and husbandry. Seminal experimental investigations on the damaging effects of oxidative stress and the mitigating effects of antioxidant defences were conducted primarily in domesticated organisms.

2. In recent years, ecologists have taken to studying antioxidants and oxidative stress in free‐ranging organisms and have integrated principles of oxidative stress into several core evolutionary concepts, such as life‐history trade‐offs (e.g. survival vs. reproduction), senescence and sexual selection. This initial flurry of studies has provided major advances in our understanding of how antioxidant defences evolve and function.

3. In this overview, it is our goal to provide ecologists with an accessible summary of (i) the biochemical basis and conceptual frameworks behind oxidative stress and antioxidants, (ii) the research questions and hypotheses that are generated by incorporating antioxidants and oxidative stress into models of life‐history theory, ageing, mate selection, and honest signalling, and (iii) the trends in the evidence that have emerged from initial studies in these areas.

4. Though much progress has been made on the ecological and evolutionary relevance of antioxidant and oxidative stress physiology, no consensus has emerged regarding the primacy of how oxidative stress challenges or antioxidant limits or values shape organismal life‐histories. However, there are many taxonomic biases in studies to date and several ideal environmental systems that are as‐of‐yet untapped.