bluuebunny/crossref_metadata_2025 huggingface dataset:
Bioavailability and preliminary toxicity evaluations of alumina nanoparticles in vivo after oral exposure
Authors: Yang Sheng-Tao , Wang Tiancheng , Dong Erya , Chen Xin-Xin , Xiang Kun , Liu Jia-Hui , Liu Yuanfang , Wang Haifang
Published: May 2012

Alumina nanoparticles (NPs) are among the most important nanomaterials and are widely used in diverse areas. In this study, we evaluated the bioavailability and toxicity of alumina NPs in mice after oral exposure, compared with traditional alumina powder. Our results indicated that negligible alumina NPs were absorbed post-exposure and alumina NPs did not influence the balance of essential trace elements, including Fe, Cu and Zn. Preliminary toxicological evaluations suggested that alumina NPs were of low toxicity. The body weights were similar among the mice exposed to alumina NPs, alumina powder and 0.9% NaCl aqueous solution. The low toxicity was also indicated by the unchanged serum biochemical parameters. The implications related to the ongoing safety evaluations and applications of alumina NPs are discussed.
Deciphering the role of GLUT4 N-glycosylation in adipocyte and muscle cell models
Authors: Zaarour Nancy , Berenguer Marion , Le Marchand-Brustel Yannick , Govers Roland
Published: May 2012

GLUT4 (glucose transporter 4) is responsible for the insulin-induced uptake of glucose by muscle and fat cells. In non-stimulated (basal) cells, GLUT4 is retained intracellularly, whereas insulin stimulation leads to its translocation from storage compartments towards the cell surface. How GLUT4 is retained intracellularly is largely unknown. Previously, aberrant GLUT4 N-glycosylation has been linked to increased basal cell-surface levels, while N-glycosylation-deficient GLUT4 was found to be quickly degraded. As recycling and degradation of GLUT4 are positively correlated, we hypothesized that incorrect N-glycosylation of GLUT4 might reduce its intracellular retention, resulting in an increased cell-surface recycling, in increased basal cell-surface levels, and in enhanced GLUT4 degradation. In the present study, we have investigated N-glycosylation-deficient GLUT4 in detail in 3T3-L1 preadipocytes, 3T3-L1 adipocytes and L6 myoblasts. We have found no alterations in retention, insulin response, internalization or glucose transport activity. Degradation of the mutant molecule was increased, although once present at the cell surface, its degradation was identical with that of wild-type GLUT4. Our findings indicate that N-glycosylation is important for efficient trafficking of GLUT4 to its proper compartments, but once the transporter has arrived there, N-glycosylation plays no further major role in its intracellular trafficking, nor in its functional activity.
D-module representations of ${\cal N}=2,4,8$N=2,4,8 superconformal algebras and their superconformal mechanics
Authors: Kuznetsova Zhanna , Toppan Francesco
Published: May 2012

The linear (homogeneous and inhomogeneous) \documentclass[12pt]{minimal}\begin{document}$(k, {\cal N}, {\cal N}-k)$\end{document}(k,N,N−k) supermultiplets of the \documentclass[12pt]{minimal}\begin{document}${\cal N}$\end{document}N-extended one-dimensional supersymmetry algebra induce D-module representations for the \documentclass[12pt]{minimal}\begin{document}${\cal N}=2,4,8$\end{document}N=2,4,8 superconformal algebras. For \documentclass[12pt]{minimal}\begin{document}${\cal N}=2$\end{document}N=2, the D-module representations of the A(1, 0) superalgebra are obtained. For \documentclass[12pt]{minimal}\begin{document}${\cal N}=4$\end{document}N=4 and scaling dimension λ = 0, the D-module representations of the A(1, 1) superalgebra are obtained. For λ ≠ 0, the D-module representations of the D(2, 1; α) superalgebras are obtained, with α determined in terms of the scaling dimension λ according to: α = −2λ for k = 4, i.e., the (4, 4) supermultiplet, α = −λ for k = 3, i.e., (3, 4, 1), and α = λ for k = 1, i.e., (1, 4, 3). For λ ≠ 0 the (2, 4, 2) supermultiplet induces a D-module representation for the centrally extended sl(2|2) superalgebra. For \documentclass[12pt]{minimal}\begin{document}${\cal N}=8$\end{document}N=8, the (8, 8) root supermultiplet induces a D-module representation of the D(4, 1) superalgebra at the fixed value \documentclass[12pt]{minimal}\begin{document}$\lambda =\frac{1}{4}$\end{document}λ=14. A Lagrangian framework to construct one-dimensional, off-shell, superconformal-invariant actions from single-particle and multi-particles D-module representations is discussed. It is applied to explicitly construct invariant actions for the homogeneous and inhomogeneous \documentclass[12pt]{minimal}\begin{document}${\cal N}=4$\end{document}N=4 (1, 4, 3) D-module representations (in the last case for several interacting supermultiplets of different chirality).
Dielectric properties and relaxation behavior of the indium doped cadmium zinc telluride single crystal
Authors: Li Qiang , Fan Huiqing , Jie Wanqi , Peng Biaolin , Long Changbai
Published: May 2012

Low frequency dielectric dispersion behavior of the indium doped cadmium zinc telluride single crystal has been investigated. The temperature dependent of dielectric loss shows a broadening peak at high temperatures, which is attributed to thermally activated relaxation process. The large dielectric permittivity can be attributed to the influence of the dc conductivity and the predominance of the dc conduction in low frequency region overshadows the true behavior of the imaginary part of dielectric permittivity. The contribution of dc conduction and ac conduction has also been studied. A polaron theory indicates that the dielectric relaxation of the indium doped cadmium zinc telluride crystal at high temperature is associated with the hopping localized cadmium vacancies and telluride antisites defects. The hopping energy increases from 1.204 eV at 499 K to 1.267 eV at 534 K monotonically, which is close to the thermal activation energy 1.541 eV and dc conductivity activation energy 1.239 eV.
Dense arrays of microscopic optical vortex generators from femtosecond direct laser writing of radial birefringence in glass
Authors: Brasselet Etienne , Royon Arnaud , Canioni Lionel
Published: May 2012

We report on the generation of permanent singular light mode converters at the microscale using femtosecond direct laser writing in photo-thermo-refractive glass. It relies on the irreversible light-induced radial birefringence in the bulk of the material. The ability of such birefringence pattern to convert the spin angular momentum of light into orbital optical angular momentum is exploited to demonstrate the production of large arrays of optical vortex generators with surface densities up to 104cm-2.
Design of a beam emission spectroscopy diagnostic for negative ions radio frequency source SPIDER
Authors: Zaniol B. , Pasqualotto R. , Barbisan M.
Published: May 2012

A facility will be built in Padova (Italy) to develop, commission, and optimize the neutral beam injection system for ITER. The full scale prototype negative ion radio frequency source SPIDER, featuring up to 100 kV acceleration voltage, includes a full set of diagnostics, required for safe operation and to measure and optimize the beam performance. Among them, beam emission spectroscopy (BES) will be used to measure the line integrated beam uniformity, divergence, and neutralization losses inside the accelerator (stripping losses). In the absence of the neutralization stage, SPIDER beam is mainly composed by H− or D− particles, according to the source filling gas. The capability of a spectroscopic diagnostic of an H− (D−) beam relies on the interaction of the beam particles with the background gas particles. The BES diagnostic will be able to acquire the Hα (Dα) spectrum from up to 40 lines of sight. The system is capable to resolve stripping losses down to 2 keV and to measure beam divergence with an accuracy of about 10%. The design of this diagnostic is reported, with discussion of the layout and its components, together with simulations of the expected performance.
A miniature Joule-Thomson cooler for optical detectors in space
Authors: Derking J. H. , Holland H. J. , Tirolien T. , ter Brake H. J. M.
Published: May 2012

The utilization of single-stage micromachined Joule-Thomson (JT) coolers for cooling small optical detectors is investigated. A design of a micromachined JT cold stage–detector system is made that focuses on the interface between a JT cold stage and detector, and on the wiring of the detector. Among various techniques, adhesive bonding is selected as most suitable technique for integrating the detector with the JT cold stage. Also, the optimum wiring of the detector is discussed. In this respect, it is important to minimize the heat conduction through the wiring. Therefore, each wire should be optimized in terms of acceptable impedance and thermal heat load. It is shown that, given a certain impedance, the conductive heat load of electrically bad conducting materials is about twice as high as that of electrically good conducting materials. A micromachined JT cold stage is designed and integrated with a dummy detector. The JT cold stage is operated at 100 K with nitrogen as the working fluid and at 140 K with methane. Net cooling powers of 143 mW and 117 mW are measured, respectively. Taking into account a radiative heat load of 40 mW, these measured values make the JT cold stage suitable for cooling a photon detector with a power dissipation up to 50 mW, allowing for another 27 to 53 mW heat load arising from the electrical leads.
Conveyor belt effect in the flow through a tube of a viscous fluid with spinning particles
Authors: Felderhof B. U.
Published: May 2012

The extended Navier-Stokes equations describing the steady-state hydrodynamics of a viscous fluid with spinning particles are solved for flow through a circular cylindrical tube. The flow caused by an applied torque density in the azimuthal direction and linear in the radial distance from the axis is compared with the flow caused by a uniform applied force density directed along the axis of the tube. In both cases the flow velocity is of Poiseuille type plus a correction. In the first case the flow velocity is caused by the conveyor belt effect of spinning particles. The corrections to the Poiseuille flow pattern in the two cases differ only by a proportionality factor. The spin velocity profiles in the two cases are also proportional.
Two sources of asymmetry-induced transport
Authors: Eggleston D. L.
Published: May 2012

A single-particle computer code with collisional effects is used to study asymmetry-induced radial transport of a non-neutral plasma in a coaxial Malmberg-Penning trap. Following the time variation of the mean change and mean square change in radial position allows for the calculation of the radial drift velocity vD and the diffusion coefficient D as defined by the radial flux equation Γ=-Ddn0dr+n0vD. For asymmetries of the form φ1(r)cos(kz+ωt-lθ) and periodic boundary conditions, the transport coefficients obtained match those predicted by resonant particle transport theory where the transport is produced by particles with velocities near ±(lωR-ω)/k, with ωR being the azimuthal rotation frequency. For asymmetries of the form φ1(r)cos(kz)cos(ωt-lθ) and low collision frequency, there is a second contribution to the transport produced by low velocity particles axially trapped in the asymmetry potential. These produce a stronger variation of D with ω with a peak at ω=ωR. The width of the peak Δω increases with center conductor bias and decreases with radius, while the height shows the opposite behavior. The transport due to axially trapped particles is typically comparable to or larger than that from resonant particles. This second contribution to the transport may explain the discrepancies between experiments and resonant particle theory.
Divertor asymmetry and scrape-off layer flow in various divertor configurations in Experimental Advanced Superconducting Tokamak
Authors: Liu S. C. , Guo H. Y. , Xu G. S. , Gao X. , Zhu S. Z. , Wang H. Q. , Wang L. , Yan N. , Wang D. S. , Liu P. , Jiang M. , Zhang W. , Ming T. F. , Chang J. F. , Ding S. Y. , Xiong H. , Shao L. M. , Wu Z. W. , Luo G. N. , Team EAST
Published: May 2012

Divertor asymmetry and its dependence on the ion ▿B direction has been investigated in the Experimental Advanced Superconducting Tokamak by changing the divertor configuration from lower single null (LSN), via double null (DN), to upper single null (USN) during one single discharge. Divertor plasmas exhibit the usual in-out asymmetry in particle and heat fluxes in LSN with the ion ▿B direction toward the lower X-point, favoring the outer divertor, especially at high density. The in-out asymmetry is reversed when changing the divertor configuration from LSN to USN, thus clearly demonstrating the effect of classical drifts. DN exhibits an even stronger in-out divertor asymmetry, favoring the outer divertor. A significant top-down asymmetry is also seen for DN, with greater particle and heat fluxes to the bottom divertor. In addition, the parallel plasma flow has been measured by a fast moving Mach probe at the outer midplane, which shows similar magnitude to the Pfirsch-Schlüter flow. Its contribution to the poloidal particle flux is also assessed and comparison is made with that from the poloidal E × B drift.
Filamentation instability of quantum magnetized plasma in the presence of an external periodic magnetic field
Authors: Hasanbeigi A. , Saberi N. , Mehdian H.
Published: May 2012

This paper investigates the filamentation instability of a non-relativistic electron beam passing through a periodic longitudinal magnetic field and an infinite uniform magnetized plasma. The linearized fluid-Maxwell equations are used to derive an equation for the dispersion relation of quantum magnetized plasma. The resulting dispersion equation is analyzed numerically over a wide range of system parameters. It is found that the growth rate of the filamentation instabilities is strongly affected by the strength of the periodic magnetic field.
Large amplitude double-layers in a dusty plasma with a q-nonextensive electron velocity distribution and two-temperature isothermal ions
Authors: Roy Kaushik , Saha Taraknath , Chatterjee Prasanta , Tribeche Mouloud
Published: May 2012

Arbitrary amplitude dust-acoustic (DA) double-layers in a plasma with nonextensive electrons, two-temperature thermal ions, and warm drifting dust grains are addressed. It is shown that DA double-layer structures, the onset of which depends sensitively on the plasma parameters, can exist. In particular, it may be noted that the electron nonextensivity may affect drastically the existence of these localized structures. In view of recent observation, our results should assist in the interpretation of the nonlinear double-layers observed in the downward current region of the aurora.
Transmission electron microscopy study on the effect of various capping layers on CoFeB/MgO/CoFeB pseudo spin valves annealed at different temperatures
Authors: Karthik S. V. , Takahashi Y. K. , Ohkubo T. , Hono K. , Gan H. D. , Ikeda S. , Ohno H.
Published: May 2012

The microstructure of pseudo spin-valve magnetic tunnel junctions (MTJs) comprising a stacking structure of Ta/Ru/Ta/CoFeB/MgO/CoFeB/ with and without X = Pd, Ti, Ta fabricated on thermally oxidized Si wafer with different annealing temperatures, Ta = 250 °C, 300 °C, 400 °C, and 500 °C, has been investigated. The as-deposited MTJs exhibit an amorphous CoFeB structure that crystallizes into bcc Fe-Co (001) from the MgO (001) interface upon annealing at Ta ≥ 250 °C. A bcc Fe-Co (110) crystallizes from the fcc Pd (111) interface. The Fe-Co layer is alloyed with Pd layer at Ta = 500 °C to form an (Fe, Co)-Pd alloy layer, which causes a drastic reduction in the tunneling magnetoresistance (TMR) from 171% to −2.7%. In the Ti capped MTJs, bcc Fe-Co (001) crystallizes from the hcp (001) Ti interface at Ta = 300 °C. Upon further annealing to Ta ≥ 400 °C, the Ti oxidizes to form amorphous Ti-Ox. The rejected B diffuses back to the CoFe layer at Ta = 500 °C that degrades the TMR. On the other hand, the Ta capped MTJs annealed at 300 ≤ Ta ≤ 500 °C show a perfect grain-to-grain epitaxy with an orientation relationship of (001)[110]MgO//(001)[100]CoFe without interdiffusion or oxidation, resulting in the highest TMR value among all the MTJs with various capping layers.
Enforced c-axis growth of ZnO epitaxial chemical vapor deposition films on a-plane sapphire
Authors: Xie Yong , Madel Manfred , Zoberbier Thilo , Reiser Anton , Jie Wanqi , Neuschl Benjamin , Biskupek Johannes , Kaiser Ute , Feneberg Martin , Thonke Klaus
Published: May 2012

To enforce perfect c-axis orientation of ZnO epitaxial films grown on a-plane sapphire, we first grew perfectly perpendicularly aligned (i.e., c axis oriented) ZnO nanopillars on such sapphire substrates, and then over-grew these by a closed epitaxial film using a modified chemical vapor deposition process at atmospheric pressure. X-ray diffraction and low temperature photoluminescence measurements confirm the desired epitaxial relationship and very high crystalline quality. This growth scheme is an efficient method to suppress dislocations and polycrystalline growth of ZnO and could work equally well for other heteroepitaxial epilayer/substrate systems.
Cathode buffer layers based on vacuum and solution deposited poly(3,4-ethylenedioxythiophene) for efficient inverted organic solar cells
Authors: Barr Miles C. , Carbonera Chiara , Po Riccardo , Bulović Vladimir , Gleason Karen K.
Published: May 2012

Vacuum and solution processed versions of poly(3,4-ethylenedioxythiophene) (PEDOT) are used as cathode interlayers in inverted organic photovoltaic cells comprising tetraphenyldibenzoperiflanthene as the electron donor and C60 as the electron acceptor. Chemical treatment of the as-deposited PEDOT layers with tetrakis(dimethylamino)ethylene or cesium carbonate reduces the work function by up to 0.8 eV. Inserting these PEDOT layers at the indium tin oxide cathode results in improved electron collection and efficiencies of up to 2.3 ± 0.2%, approaching the 3.2 ± 0.3% of the conventional device. This illustrates the potential for efficient polymer cathode materials and inverted device architectures compatible with either solution or vacuum processing.
Low-voltage ambipolar polyelectrolyte-gated organic thin film transistors
Authors: Malti Abdellah , Berggren Magnus , Crispin Xavier
Published: May 2012

Organic transistors that use polyelectrolytes as gate insulators can be driven at very low voltages (<1 V). The low operating voltage is possible thanks to the formation of electric double layers upon polarization, which generates large electric fields at the critical interfaces in the device structure. In this work, we use a semiconducting blend (of a high electron affinity polymer and a low ionization potential one) in conjunction with a solid polyelectrolyte insulator to fabricate low-voltage ambipolar organic transistors. For both n- and p-channel operation, we use a polycation with readily mobile—yet large enough to limit bulk doping of the semiconductor—counterions.
Vertically integrated double-layer on-chip silicon membranes for 1-to-12 waveguide fanouts
Authors: Zhang Yang , Hosseini Amir , Ahn Jaehyun , Kwong David N. , Fallahazad Babak , Tutuc Emanuel , Chen Ray T.
Published: May 2012

We present an on-chip vertically integrated three-dimensional photonic integrated circuit. Double-layer 1 × 12 multimode interference (MMI) couplers are fabricated on silicon membranes using double-bonded silicon-on-insulator wafers. The input light is transverse electric polarized, operating at 1550 nm. The top layer MMI coupler has an excess loss of 0.48 dB and an uniformity within 1.1 dB. The bottom layer MMI coupler has an excess loss of 2.9 dB and an uniformity within 1.7 dB.
Lifetime statistics of quantum chaos studied by a multiscale analysis
Authors: Di Falco A. , Krauss T. F. , Fratalocchi A.
Published: May 2012

In a series of pump and probe experiments, we study the lifetime statistics of a quantum chaotic resonator when the number of open channels is greater than one. Our design embeds a stadium billiard into a two dimensional photonic crystal realized on a silicon-on-insulator substrate. We calculate resonances through a multiscale procedure that combines energy landscape analysis and wavelet transforms. Experimental data is found to follow the universal predictions arising from random matrix theory with an excellent level of agreement.
Invariant boundary value problems for a fourth-order dynamic Euler-Bernoulli beam equation
Authors: Bokhari Ashfaque H. , Mahomed F. M. , Zaman F. D.
Published: May 2012

We obtain the complete Lie symmetry group classification of the dynamic fourth-order Euler-Bernoulli partial differential equation, where the elastic modulus, the area moment of inertia are constants and the applied load is a nonlinear function. In the Lie analysis, the principal Lie algebra which is two-dimensional extends in three cases, viz., the linear, the exponential, and the general power law. For each of the nontrivial cases, we determine symmetry reductions to ordinary differential equations which are of order four. In only one case related to the power law we are able to have a compatible initial-boundary value problem for a clamped end and a free beam. For these cases we deduce the corresponding fourth-order ordinary differential equations with appropriate boundary conditions. We provide an asymptotic solution for the reduced fourth-order ordinary differential equation corresponding to a clamped or free beam.
Nucleotide-dependent mechanism of Get3 as elucidated from free energy calculations
Authors: Wereszczynski Jeff , McCammon J. Andrew
Published: May 2012

The unique topology of tail-anchored (TA) proteins precludes them from utilizing the well-studied cotranslational translocation mechanism of most transmembrane proteins, forcing them into a distinct, posttranslational pathway. In yeast, this process is the guided entry of TA-proteins (GET) pathway, which utilizes a combination of cytosolic and transmembrane proteins to identify a TA protein, transfer it, and insert it into the endoplasmic reticulum membrane. At the center of this mechanism is the Get3 homodimer, which transfers a TA protein between the two GET phases by leveraging energy gained in ATP binding and hydrolysis to undergo significant structural changes from “open” to “closed” conformations. We present all-atom molecular dynamics simulations of Get3 in multiple nucleotide states, and through rigorous potential of mean force calculations, compute the free energy landscape of the Get3 opening/closing pathway. Results agree well with experiments on the nucleotide bias of Get3 open and closed structures in the crystallographically observed no-nucleotide, two ATP, and two ADP states, and also reveal their populations in the asymmetric one ATP and one ADP cases. Structures also compare well with the recently observed “semiopen” conformation and suggest that Get3 may sample this state free in solution and not just when bound to Get1, as observed in experiments. Finally, we present evidence for a unique, “wide-open” conformation of Get3. These calculations describe the nucleotide-dependent thermodynamics of Get3 in solution, and improve our understanding of its mechanism in each phase of the GET cycle.
Revival of the abandoned therapeutic wortmannin by nanoparticle drug delivery
Authors: Karve Shrirang , Werner Michael E. , Sukumar Rohit , Cummings Natalie D. , Copp Jonathan A. , Wang Edina C. , Li Chenxi , Sethi Manish , Chen Ronald C. , Pacold Michael E. , Wang Andrew Z.
Published: May 2012

One of the promises of nanoparticle (NP) carriers is the reformulation of promising therapeutics that have failed clinical development due to pharmacologic challenges. However, current nanomedicine research has been focused on the delivery of established and novel therapeutics. Here we demonstrate proof of the principle of using NPs to revive the clinical potential of abandoned compounds using wortmannin (Wtmn) as a model drug. Wtmn is a potent inhibitor of phosphatidylinositol 3′ kinase-related kinases but failed clinical translation due to drug-delivery challenges. We engineered a NP formulation of Wtmn and demonstrated that NP Wtmn has higher solubility and lower toxicity compared with Wtmn. To establish the clinical translation potential of NP Wtmn, we evaluated the therapeutic as a radiosensitizer in vitro and in vivo. NP Wtmn was found to be a potent radiosensitizer and was significantly more effective than the commonly used radiosensitizer cisplatin in vitro in three cancer cell lines. The mechanism of action of NP Wtmn radiosensitization was found to be through the inhibition of DNA-dependent protein kinase phosphorylation. Finally, NP Wtmn was shown to be an effective radiosensitizer in vivo using two murine xenograft models of cancer. Our results demonstrate that NP drug-delivery systems can promote the readoption of abandoned drugs such as Wtmn by overcoming drug-delivery challenges.
Toxic fibrillar oligomers of amyloid-β have cross-β structure
Authors: Stroud James C. , Liu Cong , Teng Poh K. , Eisenberg David
Published: May 2012

Although amyloid fibers are found in neurodegenerative diseases, evidence points to soluble oligomers of amyloid-forming proteins as the cytotoxic species. Here, we establish that our preparation of toxic amyloid-β
1–42
(Abeta42) fibrillar oligomers (TABFOs) shares with mature amyloid fibrils the cross-β structure, in which adjacent β-sheets adhere by interpenetration of protein side chains. We study the structure and properties of TABFOs by powder X-ray diffraction, EM, circular dichroism, FTIR spectroscopy, chromatography, conformational antibodies, and celluar toxicity. In TABFOs, Abeta42 molecules stack into short protofilaments consisting of pairs of helical β-sheets that wrap around each other to form a superhelix. Wrapping results in a hole along the superhelix axis, providing insight into how Abeta may form pathogenic amyloid pores. Our model is consistent with numerous properties of Abeta42 fibrillar oligomers, including heterogenous size, ability to seed new populations of fibrillar oligomers, and fiber-like morphology.
ANTISEMITISM IN FRANCE
Authors: Altglas Véronique
Published: May 2012

This article discusses the so-called newness of today's antisemitism through the historical and social specificities of antisemitism in French society. It casts light on the continuities of antisemitic discourse in France, but also its transformation in relation to the French colonial heritage and the recent ‘communitarianisation’ of France's social life. This analysis of antisemitism is furthered by the presentation of two case-studies: the controversial discourses of comedian Dieudonné and Kémi Séba, leader of a black supremacist movement called Tribu KA which stirred controversies in the 2000s. These two examples emphasise the fact that antisemitic discourse is better understood as a narrative about downward social mobility and status, which hardly makes antisemitism new.
Effect of Perioperative Systemic α2 Agonists on Postoperative Morphine Consumption and Pain Intensity
Authors: Blaudszun Grégoire , Lysakowski Christopher , Elia Nadia , Tramèr Martin R.
Published: May 2012

Background

Systemic α2 agonists are believed to reduce pain and opioid requirements after surgery, thus decreasing the incidence of opioid-related adverse effects, including hyperalgesia.

Methods

The authors searched for randomized placebo-controlled trials testing systemic α2 agonists administrated in surgical patients and reporting on postoperative cumulative opioid consumption and/or pain intensity. Meta-analyses were performed when data from 5 or more trials and/or 100 or more patients could be combined.

Results

Thirty studies (1,792 patients, 933 received clonidine or dexmedetomidine) were included. There was evidence of postoperative morphine-sparing at 24 h; the weighted mean difference was -4.1 mg (95% confidence interval, -6.0 to -2.2) with clonidine and -14.5 mg (-22.1 to -6.8) with dexmedetomidine. There was also evidence of a decrease in pain intensity at 24 h; the weighted mean difference was -0.7 cm (-1.2 to -0.1) on a 10-cm visual analog scale with clonidine and -0.6 cm (-0.9 to -0.2) with dexmedetomidine. The incidence of early nausea was decreased with both (number needed to treat, approximately nine). Clonidine increased the risk of intraoperative (number needed to harm, approximately nine) and postoperative hypotension (number needed to harm, 20). Dexmedetomidine increased the risk of postoperative bradycardia (number needed to harm, three). Recovery times were not prolonged. No trial reported on chronic pain or hyperalgesia.

Conclusions

Perioperative systemic α2 agonists decrease postoperative opioid consumption, pain intensity, and nausea. Recovery times are not prolonged. Common adverse effects are bradycardia and arterial hypotension. The impact of α2 agonists on chronic pain or hyperalgesia remains unclear because valid data are lacking.
SPECT and PET Imaging of Meningiomas
Authors: Valotassiou Varvara , Leondi Anastasia , Angelidis George , Psimadas Dimitrios , Georgoulias Panagiotis
Published: May 2012

Meningiomas arise from the meningothelial cells of the arachnoid membranes. They are the most common primary intracranial neoplasms and represent about 20% of all intracranial tumors. They are usually diagnosed after the third decade of life and they are more frequent in women than in men. According to the World Health Organization (WHO) criteria, meningiomas can be classified into grade I meningiomas, which are benign, grade II (atypical) and grade III (anaplastic) meningiomas, which have a much more aggressive clinical behaviour. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are routinely used in the diagnostic workup of patients with meningiomas. Molecular Nuclear Medicine Imaging with Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) could provide complementary information to CT and MRI. Various SPECT and PET tracers may provide information about cellular processes and biological characteristics of meningiomas. Therefore, SPECT and PET imaging could be used for the preoperative noninvasive diagnosis and differential diagnosis of meningiomas, prediction of tumor grade and tumor recurrence, response to treatment, target volume delineation for radiation therapy planning, and distinction between residual or recurrent tumour from scar tissue.
Genetics and Epigenetics of Parkinson's Disease
Authors: Coppedè Fabio
Published: May 2012

In 1997 a mutation in thea-synuclein(SNCA) gene was associated with familial autosomal dominant Parkinson’s disease (PD). Since then, several loci (PARK1-15) and genes have been linked to familial forms of the disease. There is now sufficient evidence that six of the so far identified genes at PARK loci (a-synuclein, leucine-rich repeat kinase 2, parkin, PTEN-induced putative kinase 1, DJ-1, andATP13A2) cause inherited forms of typical PD or parkinsonian syndromes. Other genes at non-PARK loci (MAPT, SCA1, SCA2, spatacsin, POLG1) cause syndromes with parkinsonism as one of the symptoms. The majority of PD cases are however sporadic “idiopathic” forms, and the recent application of genome-wide screening revealed almost 20 genes that might contribute to disease risk. In addition, increasing evidence suggests that epigenetic mechanisms, such as DNA methylation, histone modifications, and small RNA-mediated mechanisms, could regulate the expression of PD-related genes.
General and Electrophysiological Toxic Effects of Manganese in Rats following Subacute Administration in Dissolved and Nanoparticle Form
Authors: Horváth Edina , Máté Zsuzsanna , Takács Szabolcs , Pusztai Péter , Sápi András , Kónya Zoltán , Nagymajtényi László , Papp András
Published: May 2012

In an attempt to model occupational and environmental Mn exposures and their possible interaction, young male Wistar rats were exposed to Mn by oral administration in dissolved form (MnCl2·4H2O, 14.84 and 59.36 mg/kg b.w.) and by intratracheal application of MnO2nanoparticles (2.63 mg/kg b.w.). After 3 and 6 weeks oral, or 3 weeks oral plus 3 weeks intratracheal, exposure, general toxicological, and electrophysiological tests were done. Body weight gain was significantly reduced after 6 and 3 plus 3 weeks exposure, but the effect of the latter on the pace of weight gain was stronger. Organ weights signalized systemic stress and effect on lungs. Changes in evoked electrophysiological responses (cortical sensory evoked potential and nerve action potential) indicated that the 3 plus 3 weeks combined exposure caused equal or higher changes in the latency of these responses than 6 weeks of exposure, although the calculated summed Mn dose in the former case was lower. The results showed the importance of the physicochemical form of Mn in determining the toxic outcome, and suggested that neurofunctional markers of Mn action may indicate the human health effect better than conventional blood Mn measurement.
Tautomerism in 11-Hydroxyaklavinone: A DFT Study
Authors: Türker Lemi
Published: May 2012

The antharquinone-based chromophore of 11-hydroxyaklavinone is present in the structure of an anticancer agent, daunomycin. On the other hand, aklavinone is the parent aglycone of certain anthracycline antibiotics that possess anti-cancer activity too. The structures of aklavinone and its 11-hydroxy derivative have many –OH groups, and two keto groups which may take place in certain tautomeric equilibria. Of these tautomeric forms, presently the one involving the anthraquinone based tautomers of 11-hydroxyaklavinone has been investigated quantum chemically in the framework of the density functional theory at the levels of RB3LYP/6-31G(d) and RB3LYP/6-31G(d,p).
Striatal Input- and Rate-Dependent Effects of Muscarinic Receptors on Pallidal Firing
Authors: Querejeta Enrique , Alatorre Alberto , Ríos Alain , Barrientos Rafael , Oviedo-Chávez Aldo , Bobadilla-Lugo Rosa Amalia , Delgado Alfonso
Published: May 2012

The globus pallidus (GP) plays a key role in the overall basal ganglia (BG) activity. Despite evidence of cholinergic inputs to GP, their role in the spiking activity of GP neurons has not received attention. We examine the effect of local activation and blockade of muscarinic receptors (MRs) in the spontaneous firing of GP neurons both in normal and ipsilateral striatum-lesioned rats. We found that activation of MRs produces heterogeneous responses in both normal and ipsilateral striatum-lesioned rats: in normal rats the response evoked by MRs depends on the predrug basal firing rate; the inhibition evoked by MRs is higher in normal rats than in striatum-lesioned rats; the number of neurons that undergo inhibition is lower in striatum-lesioned rats than in normal rats. Our data suggest that modulation of MRs in the GP depends on the firing rate before their activation and on the integrity of the striato-pallidal pathway.
Robust Optimization of Alginate-Carbopol 940 Bead Formulations
Authors: López-Cacho J. M. , González-R Pedro L. , Talero B. , Rabasco A. M. , González-Rodríguez M. L.
Published: May 2012

Formulation process is a very complex activity which sometimes implicates taking decisions about parameters or variables to obtain the best results in a high variability or uncertainty context. Therefore, robust optimization tools can be very useful for obtaining high quality formulations. This paper proposes the optimization of different responses through the robust Taguchi method. Each response was evaluated like a noise variable, allowing the application of Taguchi techniques to obtain a response under the point of view of the signal to noise ratio. AL18Taguchi orthogonal array design was employed to investigate the effect of eight independent variables involved in the formulation of alginate-Carbopol beads. Responses evaluated were related to drug release profile from beads (t50%and AUC), swelling performance, encapsulation efficiency, shape and size parameters. Confirmation tests to verify the prediction model were carried out and the obtained results were very similar to those predicted in every profile. Results reveal that the robust optimization is a very useful approach that allows greater precision and accuracy to the desired value.
Localisation of Abundant and Organ-Specific Genes Expressed inRosa hybridaLeaves and Flower Buds by DirectIn SituRT-PCR
Authors: Jedrzejuk Agata , Mibus Heiko , Serek Margrethe
Published: May 2012

In situPCR is a technique that allows specific nucleic acid sequences to be detected in individual cells and tissues.In situPCR and IS-RT-PCR are elegant techniques that can increase both sensitivity and throughput, but they are, at best, only semiquantitative; therefore, it is desirable first to ascertain the expression pattern by conventional means to establish the suitable conditions for each probe. In plants,in situRT-PCR is widely used in the expression localisation of specific genes, including MADS-box and other function-specific genes or housekeeping genes in floral buds and other organs. This method is especially useful in small organs or during early developmental stages when the separation of particular parts is impossible. In this paper, we compared three different labelling and immunodetection methods by usingin situRT-PCR inRosa hybridaflower buds and leaves. As target genes, we used the abundantβ-actinandRhFULgene, which is expressed only in the leaves and petals/sepals of flower buds. We used digoxygenin-11-dUTP, biotin-11-dUTP, and fluorescein-12-dUTP-labelled nucleotides and antidig-AP/ streptavidin-fluorescein-labelled antibodies. All of the used methods gave strong, specific signal and all of them may be used in localization of gene expression on tissue level in rose organs.
A Model Study on the Possible Effects of an External Electrical Field on Enzymes Having Dinuclear Iron Cluster [2Fe-2S]
Authors: Türker Lemi
Published: May 2012

Hydrogenases which catalyze the H2↔ 2H++ 2e−reaction are metalloenzymes that can be divided into two classes, the NiFe and Fe enzymes, on the basis of their metal content. Iron-sulfur clusters [2Fe-2S] and [4Fe-4S] are common in ironhydrogenases. In the present model study, [2Fe-2S] cluster has been considered to visualize the effect of external electric field on various quantum chemical properties of it. In the model, all the cysteinyl residues are in the amide form. The PM3 type semiempirical calculations have been performed for the geometry optimization of the model structure in the absence and presence of the external field. Then, single point DFT calculations (B3LYP/6-31+G(d)) have been carried out. Depending on the direction of the field, the chemical reactivity of the model enzyme varies which suggests that an external electric field could, under proper conditions, improve the enzymatic hydrogen production.
Surgical Implantation of a Head Plate in Mice in Preparation for In Vivo Two-Photon Imaging of Microglia: Figure 1.
Authors: Nimmerjahn Axel
Published: May 2012

Microglia are the primary immune effector cells of the brain parenchyma. They are distributed throughout the brain at various densities. Two-photon fluorescence microscopy, together with expression of fluorescent proteins in microglia, has enabled study of these fascinating cells in vivo. Imaging studies have shown, for example, that microglia continually survey their cellular environment and immediately respond to injury. However, we still know very little about their roles in various parts of the developing and adult brain or their diverse effector functions in aging and different disease states. Experimental procedures have been developed for minimally invasive short- and long-term two-photon imaging of microglial cells in cortical regions of the intact mouse brain. This protocol describes the initial preparation of the mice by surgical implantation of a head plate.
Fluorescent Labeling of Calmodulin with Bifunctional Rhodamine: Figure 1.
Authors: Beausang John F. , Sun Yujie , Quinlan Margot E. , Forkey Joseph N. , Goldman Yale E.
Published: May 2012

Polarized total internal reflection fluorescence microscopy (polTIRFM) can be used to detect the spatial orientation and rotational dynamics of single molecules. polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. This protocol describes how to label chicken calmodulin (CaM) with bifunctional rhodamine (BR) at two engineered cysteine (Cys) residues (P66C and A73C) so that it cross-links the two Cys sites. The resulting BR-CaM protein is then purified by high-performance liquid chromatography (HPLC) and concentrated by filter centrifugation. To confirm that the two Cys residues in the labeled CaM are actually cross-linked by BR, a sample of purified BR-CaM is digested by an endoproteinase and analyzed by mass spectrometry. The BR-CaM can then be used to label myosin V, which can in turn be used in a polTIRFM processive motility assay.
Preparation of Filamentous Actin for Polarized Total Internal Reflection Fluorescence Microscopy (polTIRFM) Motility Assays
Authors: Beausang John F. , Sun Yujie , Quinlan Margot E. , Forkey Joseph N. , Goldman Yale E.
Published: May 2012

Polarized total internal reflection fluorescence microscopy (polTIRFM) can be used to detect the spatial orientation and rotational dynamics of single molecules. polTIRFM determines the three-dimensional angular orientation and the extent of wobble of a fluorescent probe bound to the macromolecule of interest. In this protocol, filamentous actin (F-actin) is polymerized from purified, monomeric actin (G-actin) for use in polTIRFM motility assays in which actin interacts with myosin. The procedures include (1) the preparation of unlabeled F-actin from G-actin; (2) the preparation of F-actin that is sparsely labeled with 6′-IATR (6′-iodoacetamidotetramethylrhodamine); and (3) the preparation of F-actin with a combination of unlabeled, biotinylated, and rhodamine-labeled monomers. Rhodamine–phalloidin actin, also used in polTIRFM assays, can be prepared using a procedure similar to the one for unlabeled actin.
In Vivo Imaging of Synaptogenesis in Zebrafish
Authors: Jontes James D. , Emond Michelle R.
Published: May 2012

The embryonic zebrafish is a nearly ideal model system in which to use time-lapse imaging to study the development of the vertebrate nervous system in vivo. The embryos are small and transparent, they develop externally and rapidly, and the embryonic central nervous system is relatively simple and highly stereotyped. With the refinement of green fluorescent protein (GFP) as a genetically encoded fluorescent tag of neuronal proteins, along with advances in imaging technology, it is possible to follow the cellular and molecular events underlying development as they occur in the living embryo. This article describes strategies for imaging synapse formation in the embryonic zebrafish.
N-(2,6-Diisopropylphenyl)-N-{3-[(2,6-diisopropylphenyl)imino]butan-2-yl}azanide trichloridostannate(II)
Authors: Ma Xiaoli , Sun Shuai , Hao Pengfei , Yang Ying , Yang Zhi
Published: May 2012

In the title compound, (C28H43N2)[SnCl3], two pairs of molecular species are present in the asymmetric unit. The employed α-diimine opens up, forming a highly asymmetric ammonium that has its protons at one of the N atoms [N—C= 1.264 (4) and 1.516 (4) Å]. One of the C=N double bonds was oxidized to C—N, which is consistent with the bond length of 1.516 (4) Å. Meanwhile SnIV was reduced to SnII. The (SnCl)3
− anion is trigonal–pyramidal. In the crystal, molecules are linked by C—H...Cl, N—H...Cl, N—H...N and C—H...N bonds. The crystal studied was twinned by pseudo-merohedry.
catena-Poly[[(tetraaquacadmium)-μ-4,4′-bipyridine-κ2
N:N′] 4-hydroxy-3-sulfonatobenzoate monohydrate]
Authors: Gao Shan , Ng Seik Weng
Published: May 2012

The two independent CdII atoms in the polymeric title compound, [Cd(C10H8N2)(H2O)4](C7H4O6S)·H2O, lie on twofold rotation axes, and each is coordinated by four water molecules and the N atoms of two 4,4′-bipyridine molecules in an octahedral geometry. Bridging gives rise to chains along [101] and [-101]. The 4-hydroxy-3-sulfonatobenzoate dianions are not connected to the CdII atoms, but form hydrogen bonds to the coordinated water molecules as well as the lattice water molecule, generating a three-dimensional network.
4-[(4-Methoxybenzylidene)amino]benzenesulfonamide
Authors: Idemudia Omoruyi G. , Sadimenko Alexander P. , Afolayan Anthony J. , Hosten Eric C.
Published: May 2012

The title Schiff base compound, C14H14N2O3S, is non-planar, with a dihedral angle of 24.16 (7)° between the benzene rings. In the crystal, N—H...O and N—H...N hydrogen bonds link the molecules into a layer parallel to (011). Intra- and interlayer C—H...O interactions and π–π interactions [centroid–centroid distances = 3.8900 (9) and 3.9355 (8) Å] are also present.
N-Hexyl-3-(4-hydroxy-3,5-dimethoxyphenyl)propanamide
Authors: Andrade L. C. R. , Paixão J. A. , Almeida M. J. M. de , Tavares da Silva E. J. , Fernandes Roleira F. M.
Published: May 2012

In the title compound, C17H27NO4, which is an hydrosinapic acid derivative with increased lipophilicity conferred by an additional alkyl chain, the central and the hexyl linear chains contain slightly shorter bond lengths [C—N = 1.316 (2) Å; average linear chain C—C = 1.487 (6) Å] than reported average values [Csp
2—N = 1.334, C—C for CH2—CH2 = 1.524 and 1.513 Å for CH2—CH3]. The 4-hydroxy-3,5-dimethoxyphenyl plane [r.m.s. deviation 0.055 (12) Å] makes an angle of 59.89 (5)° with the central plane of the molecule (composed of the N atom, the carbonyl group and the two methylene C atoms linking the carbonyl group and the ring, [r.m.s. deviation 0.0026 (10) Å], which, in turn, makes an angle of 64.24 (13)° with the essentially planar hexyl chain [r.m.s. deviation 0.035 (18) Å]. The N—H group of the amide group is involved in a bifurcated hydrogen bond towards the hydroxy and one of the methoxy O atoms of the 4-hydroxy-3,5-dimethoxyphenyl substituent of a neighbouring molecule, forming a two-dimensional network in the (100) plane. In addition, the same hydroxy group acts as a donor towards the carbonyl O atom of another neighbouring molecule, forming chains running along the b axis.
Ultrasensitive detection of scrapie prion protein derived from ARQ and AHQ homozygote sheep by interspecies in vitro amplification
Authors: Murayama Yuichi , Imamura Morikazu , Masujin Kentaro , Shimozaki Noriko , Yoshioka Miyako , Mohri Shirou , Yokoyama Takashi
Published: May 2012

Prions, infectious agents causing TSEs, are composed primarily of the pathogenic form (PrPSc) of the PrPC. The susceptibility of sheep to scrapie is determined by polymorphisms in the coding region of the PRNP, mainly at codons 136, 154, and 171. The efficiency of in vitro amplification of sheep PrPSc seems to be linked also to the PrP genotype. PrPSc derived from sheep with V136R154Q171‐associated genotypes can be amplified efficiently by PMCA in the presence of additional polyanion such as poly A, but there are no reports that cite ultrasensitive detection of PrPSc derived from sheep of other PrP genotypes. We report here that sheep PrPSc derived from ARQ and AHQ homozygotes was amplified efficiently by serial PMCA using mouse brain homogenate as PrPC substrate. ARQ/ARQ PrPSc was detected in infected brain homogenates diluted up to 10−10 after five rounds of amplification, and AHQ/AHQ PrPSc was detected in samples diluted up to 10−8 after four rounds of amplification. On the other hand, amplification of PrPSc from VRQ/ARQ sheep seemed to be less efficient under the experimental conditions used. The interspecies PMCA developed in this study may be useful in the detailed analysis of PrPSc distribution in classical scrapie‐infected ARQ and AHQ homozygote sheep.