bluuebunny/crossref_metadata_2025 huggingface dataset:
An explanation for the effect of clouds over snow on the top‐of‐atmosphere bidirectional reflectance
Authors: Hudson Stephen R. , Warren Stephen G.
Published: October 2007

It has been a long‐standing puzzle why clouds, which should interact with solar radiation similarly to a thin layer of snow, have such a dramatic effect on the reflectance observed by satellites over snow‐covered regions. The presence of a cloud over the snow strongly enhances the anisotropy of the scene, so that a cloud‐over‐snow scene appears darker than clear sky over snow when observed near nadir, but much brighter when observed at large zenith angles in the forward reflected direction. By contrast, when a plane‐parallel cloud is placed above a plane‐parallel snow surface in a model, it slightly decreases the anisotropy of the system because of the cloud's smaller particles. Using a parameterization for the directional reflectance from East Antarctic snow, developed from extensive near‐surface observations from a tower, we show that the unexpected effect of clouds over snow in this region is due to the non‐plane‐parallel nature of the snow surface, not to unexpected features of the clouds. The snow surface roughness reduces the anisotropy of the reflected sunlight compared to that from a plane‐parallel snow surface. Clouds, by hiding this roughness with a surface that is very smooth in units of optical depth, increase the anisotropy by bringing the system closer to the plane‐parallel case. We use the surface parameterization to accurately model reflectance observations made from the tower over a ground fog and from the top of the atmosphere over cloud‐covered snow by the MISR satellite instrument.
Correlates of protective immunity in poxvirus infection: where does antibody stand?
Authors: Panchanathan Vijay , Chaudhri Geeta , Karupiah Gunasegaran
Published: October 2007

Even though smallpox has been eradicated, the threat of accidental or intentional release has highlighted the fact there is little consensus about correlates of protective immunity or immunity against re‐infection with the causative poxvirus, variola virus (VARV). As the existing vaccine for smallpox has unacceptable rates of side effects and complications, new vaccines are urgently needed. Surrogate animal models of VARV infection in humans, including vaccinia virus (VACV) and ectromelia virus (ECTV) infection in mice, monkeypox virus (MPXV) infection in macaques have been used as tools to dissect the immune response to poxviruses. Mousepox, caused by ECTV, a natural mouse pathogen, is arguably the best surrogate small‐animal model, as it shares many aspects of virus biology, pathology and clinical features with smallpox in humans. The requirements for recovery from a primary ECTV infection have been well characterized and include type I and II interferons, natural killer cells, CD4T cells, CD8T cell effector function and antibody. From a vaccine standpoint, it is imperative that the requirements for recovery from secondary infection are also identified. We have investigated host immune parameters in response to a secondary ECTV infection, and have identified that interferon and CD8T cell effector functions are not essential; however, T‐ and B‐cell interaction and antibody are absolutely critical for recovery from a secondary challenge. The central role of antibody has been also been identified in the secondary response to other poxviruses. These findings have important clinical implications and would greatly assist the design of therapeutic interventions and new vaccines for smallpox.
Protective effects ofHelicobacter pyloriagainst gastroesophageal reflux disease may be due to a neuroimmunological anti‐inflammatory mechanism
Authors: Shahabi Shahram , Rasmi Yousef , Jazani Nima Hosseini , Hassan Zuhair Muhammad
Published: October 2007

There is some evidence thatHelicobacter pyloriinfection has a protective effect against gastroesophageal reflux disease (GORD) and its complications such as Barrett's oesophagus and oesophageal adenocarcinoma. In this paper, we propose that a neuroimmunological mechanism is responsible for the protective effect ofH. pylorion GORD.H. pyloriinfection of the gastric mucosa induces a T helper1‐like immune response and production of pro‐inflammatory cytokines. These cytokines can inhibit local sympathetic tone, whereas they increase systemic sympathetic tone. Increased sympathetic tone can induce an anti‐inflammatory milieu, which in turn can inhibit inflammation in the oesophagus and lower oesophageal sphincter (LOS). Furthermore,H. pyloriinfection may stimulate the cholinergic anti‐inflammatory pathway. It has been suggested that reflux‐induced oesophageal inflammation plays an important role in the pathogenesis of reflux oesophagitis. Reduction of oesophageal inflammation by increased systemic sympathetic tone and vagal activity may lead to a decrease in reflux‐induced oesophageal injury and LOS dysfunction in GORD.
Bovine dendritic cells are more permissive forMycobacterium bovisreplication than macrophages, but release more IL‐12 and induce better immune T‐cell proliferation
Authors: Denis Michel , Buddle Bryce M
Published: October 2007

Bovine dendritic cells (DCs) were obtained by incubating blood monocytes with interleukin‐4 (IL‐4) and granulocyte–macrophage colony‐stimulating factor (GM‐CSF). The ability of DCs to phagocytose and allow the replication of virulentMycobacterium bovis in vitrowas studied, and compared with bovine blood monocyte‐derived macrophages. In addition, the release of cytokines byM. bovis‐infected DCs was assessed. DCs were shown to phagocytoseM. bovisefficiently, and allowed a more substantial replication ofM. boviswhen compared to macrophages, as assessed by the metabolic activity of intracellular bacteria. During the course ofM. bovisinfection, it was found that macrophages released substantial amounts of pro‐inflammatory factors such as tumour necrosis factor‐α (TNF‐α), nitric oxide (NO) and interleukin‐1β (IL‐1β).M. bovis‐infected DCs released much smaller quantities of NO, IL‐1β and TNF‐α (5‐ to 10‐fold lower amounts), when compared to macrophages. Treating cells with interferon‐gamma (IFN‐γ) before and during thein vitroinfection process was shown to increase the release of NO, TNF‐α and IL‐1β byM. bovis‐infected macrophages, but not byM. bovis‐infected DCs.M. bovis‐infected macrophages released more interleukin‐10 (IL‐10) than infected DCs. Treating cells with IFN‐γ/LPS was shown to reduceM. bovismetabolic activity in infected macrophages, but had no such impact onM. bovismetabolic activity in infected DCs. A variety of T‐cell‐derived cytokines (IFN‐γ, GM‐CSF, IL‐4) had no impact on the replication ofM. bovisin infected DCs. On the other hand, DCs infected withM. bovissustained a more efficient replication of autologous sensitized T lymphocytes compared toM. bovis‐infected macrophages.M. bovis‐infected DCs released more substantial amounts of interleukin‐12 (IL‐12) than similarly infected macrophages. These data suggest a complementary role for DCs and macrophages with regard to bacteriostatic activity and induction of an efficient immune response againstM. bovis.
Controlled growth of Zn nano-dots on a Si(111)-7×7 surface saturated with C2H5OH
Authors: Jiang Xiaohong , Xie Zhaoxiong , Shimojo Masayuki , Tanaka Ken-ichi
Published: October 2007

Metal atoms bonded with Si adatoms on the Si(111)-(7×7) surface undergo migration by hopping adjacent Si-rest atoms with dangling bond. By saturated adsorption of Si(111)-(7×7) surface with C2H5OH, the whole Si-rest atoms and a half of Si adatoms are occupied with Si–H and Si–OC2H5, so that the Zn atoms adsorbed on this surface cannot migrate by hopping. When Zn atoms were deposited on this surface, ca. 5nm Zn dots were grown in the hexagonal spacing of ca. 5.4nm width around the corner holes, which work as a mold. This is quite different from the growth of honeycomb layers composed of Zn3 clusters on the clean Si(111)-(7×7) surface. The dots grow up to nine (1.97nm) to 13 layers (2.64nm) by keeping their size, which implies a layer-by-layer growth of dots in the mold, where the growth is controlled by the kinetics instead of energetic feasibility.
Semiclassical initial value representation treatment of a hydrogen bonded complex of rigid water molecules from a single trajectory in Cartesian coordinates
Authors: Issack Bilkiss B. , Roy Pierre-Nicholas
Published: October 2007

A semiclassical initial value representation approach for molecular systems in Cartesian coordinates is combined with a recently proposed time averaging technique [J. Chem. Phys. 118, 7174 (2003)]. It is shown that a single trajectory can yield the zero-point energy of the water dimer with good accuracy for the model chosen when compared to fully constrained Cartesian semiclassical calculations. The convergence with respect to the number of averaging time origins is discussed.
Effect of nanometric grain size on room temperature magnetoimpedance, magnetoresistance, and magnetic properties of La0.7Sr0.3MnO3 nanoparticles
Authors: Dutta P. , Dey P. , Nath T. K.
Published: October 2007

In this paper we have investigated the effect of nanometric grain size modulation on the behavior of magnetoimpedance (MI), magnetoresistance, and magnetic properties of a series of single-phase nanocrystalline colossal magnetoresistance La0.7Sr0.3MnO3 (LSMO) manganites all synthesized through chemical route “pyrophoric reaction process.” MI measurements were carried out at room temperature (T=300K) in the ac signal frequency (f) range of 40kHz-110MHz and in dc magnetic field (H) range of −2.5kOe<H<+2.5kOe, respectively. The experimental results show that MI% increases with the increase in nanometric grain size (ϕ) for this series of samples. This behavior can be explained in the light of classical electrodynamics, which relates this effect with the dependency of skin depth on external magnetic field and applied ac signal frequency. Interestingly, MI of about 92% was obtained for the 28nm LSMO sample at a frequency (f) of 10MHz and at H=2.5kOe. The same sample also showed a maximum MI sensitivity of about 1%/Oe near 60Oe dc magnetic field at f=10MHz. Magnetization measurements were carried out in the applied magnetic field range of −5kOe<H<+5kOe and the experimental results reveal that spontaneous magnetization decreases with decrease in particle size. These nanometric LSMO samples also showed a paramagnetic-ferromagnetic transition near TC=360K. For comparison, we have also presented room temperature low-field magnetoresistance (LFMR) study of this series of LSMO nanoparticles. This study reveals that within this particle size range, 14–28nm, LFMR decreases with decrease in particle size, which in fact mimics the variation of MI with particle size.
Charge injection and polarization fatigue in ferroelectric thin films
Authors: Jiang A. Q. , Lin Y. Y. , Tang T. A.
Published: October 2007

Typical experimental data of polarization fatigue in Pb(Zr,Ti)O3 thin films have been presented: (1) The coercive voltage Vc and the shape of the polarization-electric (P-E) hysteresis loop unnecessarily change with the number N of fatigue cycles except the remanent polarization; (2) the capacitance at voltages close to Vc decreases monotonically with increased N, in comparison with its enhancement at voltages far away from Vc; (3) electrode damage occurs after the appearance of the amount of pinned domain walls; and (4) domain-wall pinning and depinning coexist during fatigue cycling. All phenomena mentioned above are interpreted in terms of charge injection into regions with the inhomogeneities of dielectric constant, conductivity, and polarization, especially near film-electrode interfaces. Pinning and depinning coefficients of domain walls are extracted from fatigue profiles and found to be useful in the prediction of charge injection depending on the fatigue voltage and frequency. Domain-wall motion impeded by screening carriers within film thickness is suggested during fatigue through the mimic of two in-series ferroelectric capacitors with different polarizations.
Photocurrent characteristics of individual ZnGa2O4 nanowires
Authors: Feng P. , Zhang J. Y. , Wan Q. , Wang T. H.
Published: October 2007

Zn Ga 2 O 4 nanowires were grown via a low-pressure chemical vapor deposition method, and the electrical transport properties of these nanowires were investigated. It was found that the current across individual nanowires was several picoamperes at a bias of 30V, and the current was insensitive to oxygen and temperature. These behaviors still maintained as the ZnGa2O4 nanowires were exposed to below-band-gap irradiation. In contrast, upon exposure to 254nm ultraviolet light, the current across the nanowire increased a lot. With decreasing oxygen pressure or increasing temperature, the photocurrent increased evidently; this could be understood from the Langmuir model and the adsorption isobar, respectively. The present results demonstrate that surface-related processes especially oxygen chemisorption have significant effects on the photoelectric properties of nanostructures. The optically driven oxygen and temperature sensing as found in the ZnGa2O4 nanowires may find promising applications in functional devices.
On the Hugoniot elastic limit in polycrystalline alumina
Authors: Bourne N. K. , Millett J. C. F. , Chen M. , McCauley J. W. , Dandekar D. P.
Published: October 2007

The use of polycrystalline ceramics in engineering applications requires a better knowledge of microstructural response than exists at present. The continuum response of the alumina AD995 to shock loading has been extensively investigated. This work aims to connect microstructural response with continuum observations. Over recent years, workers have reported failure in various polycrystalline ceramics occurring behind a propagating front running behind the shock. These phenomena have been investigated using embedded stress sensors and a recovery technique that has allowed the observation of the microstructure above and below the Hugoniot elastic limit (HEL). These results are brought together here to explain the observed behavior. The failure front velocity is found to change with the applied stress, in particular, it slows markedly as the HEL is exceeded. Further, the curvature of histories recorded by sensors may be related to the observed response. The evidence in the microstructure shows that the response below HEL is dominated by the intergranular failure, while above it by plasticity in grains (including twinning), which alters the deformation and failure characteristics. These microstructural features are combined with the continuum observations to review the response of the alumina.
On the dispersion characteristics of metamaterial transmission lines
Authors: Sisó G. , Gil M. , Bonache J. , Martín F.
Published: October 2007

In this paper, a detailed analysis of the dispersion characteristics of metamaterial transmission lines, based on the lumped element T-circuit model is carried out. One of the main relevant characteristics of these artificial lines is the possibility to tailor the phase response. This leads to unique properties which are of interest for microwave circuit design, such as bandwidth enhancement or multiband (dual-band) operation, among others. However, it is shown in this paper that, in spite of the larger number of circuit parameters (as compared to conventional lines), there exist intrinsic limitations that may limit the performance of such metamaterial transmission lines under certain conditions. In this paper these limitations are pointed out from an accurate analysis of the phase response and the Foster’s reactance theorem [Bell Syst. Tech. 3, 259 (1924)]. From the results of this paper, important guidelines for the design of microwave components based on metamaterial transmission lines are inferred. The fabrication and characterization of different metamaterial transmission lines will corroborate the theoretical results.
Dynamics of Li+ ions in strontium metaphosphate glasses
Authors: Dutta A. , Ghosh A.
Published: October 2007

Dynamics of Li+ ions in strontium metaphosphate glasses has been studied in the frequency range of 10Hz–2MHz and in the temperature range of 273–573K. The dc conductivity increases and the activation energy decreases with the replacement of strontium ions by lithium ions in the glass compositions. The ac electrical data have been studied using the modulus and conductivity formalisms. We have observed that the stretching exponent decreases and the frequency exponent increases with the replacement of strontium ions by lithium ions in these glasses. The variation of these parameters was explained in terms of ion-ion interaction. The mobile ion concentration remains nearly constant, which indicates that the mobility of the migrating ions increases when the alkaline earth ions are replaced by the alkali ions.
Dissipative particle dynamics simulation study on the binary mixture phase separation coupled with polymerization
Authors: Liu Hong , Qian Hu-Jun , Zhao Ying , Lu Zhong-Yuan
Published: October 2007

The influence of polymerization on the phase separation of binary immiscible mixtures has been investigated by the dissipative particle dynamics simulations in two dimensions. During polymerization, the bulk viscosity increases, which consequently slows down the spinodal decomposition process. The domain size growth is monitored in the simulations. The absence of 2∕3 exponent for inertial hydrodynamic mechanism clearly reflects the suppressing effect of polymerization on the phase separation. Due to the increasing viscosity, the individual phase may be trapped in a metastable stage instead of the lamellar morphology identified for symmetric mixtures. Moreover, the polymerization induced phase separation in the binary miscible mixture has been studied. The domain growth is strongly dependent on the polymerization probability, which is naturally related to the activation energy for polymerization. The observed complex phase separation behavior is attributed to the interplay between the increasing thermodynamic driving force for phase separation and the increasing viscosity that suppresses phase separation as the polymerization proceeds.
Vibrational dynamics of excited electronic states of molecular iodine
Authors: Scaria A. , Namboodiri V. , Konradi J. , Materny A.
Published: October 2007

Femtosecond degenerate four-wave-mixing spectroscopy following an initial pump laser pulse was used to observe the wave packet dynamics in excited electronic states of gas phase iodine. The focus of the investigation was on the ion pair states belonging to the first tier dissociating into the two ions I−(S1)+I+(P23). By a proper choice of the wavelengths of the initial pump and degenerate four-wave-mixing pulses, we were able to observe the vibrational dynamics of the BΠu+3 state of molecular iodine as well as the ion pair states accessible from there by a one-photon transition. The method proves to be a valuable tool for exploring higher lying states that cannot be directly accessed from the ground state due to selection rule exclusion or unfavorable Franck-Condon overlap.
In situ small-angle neutron scattering and rheological measurements of shear-induced gelation
Authors: Shibayama Mitsuhiro , Kawada Hiromitsu , Kume Takuji , Matsunaga Takuro , Iwai Hidetaka , Sano Tomohiko , Osaka Noboru , Miyazaki Sho , Okabe Satoshi , Endo Hitoshi
Published: October 2007

The microscopic structure of shear-induced gels for a mixed solution of 2-hydroxyethyl cellulose and nanometer-size spherical droplets has been investigated by in situ small-angle neutron scattering (SANS) with a Couette geometry as a function of shear rate γ̇. With increasing γ̇, the viscosity increased rapidly at γ̇≃4.0s−1, followed by a shear thinning. After cessation of shear, the system exhibited an extraordinarily large steady viscosity. This phenomenon was observed as a shear-induced sol-gel transition. Real-time SANS measurements showed an increase in the scattering intensity exclusively at low scattering angle region. However, neither orientation of polymer chains nor droplet deformation was detected and the SANS patterns remained isotropic irrespective of γ̇. It took about a few days for the gel to recover its original sol state. A possible mechanism of gelation is proposed from the viewpoint of shear-induced percolation transition.
Active control effectiveness and synchronization of wall turbulence under localized imposed unsteadiness
Authors: Tardu Sedat F. , Doche Olivier
Published: October 2007

The effect of a spatially localized time-periodic perturbation on the efficiency of suboptimal control of the wall turbulence is analyzed. It is shown that the imposed unsteadiness with a frequency in the median production range doubles the turbulent drag reduction under suboptimal control strategy. It is further observed that the spatially averaged turbulent wall shear is synchronized in time with the imposed perturbation waveform. This is related to the synchronization of the unstable periodic orbits present in the near-wall turbulence in connection with the regeneration cycle of turbulence producing coherent structures.
Relaxation of transport properties in electron-doped SrTiO3
Authors: Schultz Moty , Klein Lior
Published: October 2007

We electron-dope single crystal samples of SrTiO3 by exposing them to Ar+ irradiation and observe carrier mobility similar in its magnitude and temperature dependence to the carrier mobility in other electron-doped SrTiO3 systems. We find that some transport properties are time dependent. In particular, the sheet resistance increases with time at a temperature-dependent rate, suggesting an activation barrier on the order of 1eV. We attribute the relaxation effects to diffusion of oxygen vacancies—a process with energy barrier similar to the observed activation energy.
Spin field effect transistor with a graphene channel
Authors: Semenov Y. G. , Kim K. W. , Zavada J. M.
Published: October 2007

A spin field effect transistor (FET) is proposed by utilizing a graphene layer as the channel. Similar to the conventional spin FETs, the device involves spin injection and spin detection by ferromagnetic source and drain. Due to the negligible spin-orbit coupling in the carbon based materials, spin manipulation in the channel is achieved via electrical control of the electron exchange interaction with a ferromagnetic gate dielectric. Numerical estimates indicate the feasibility of the concept if the bias can induce a change in the exchange interaction energy of the order of meV. When nanoribbons are used for a finite channel width, those with armchair-type edges can maintain the device stability against the thermal dispersion.
Enhancing the optical properties of InAs quantum dots by an InAlAsSb overgrown layer
Authors: Chiu Pei-Chin , Liu Wei-Sheng , Shiau Meng-Jie , Chyi Jen-Inn , Chen Wen-Yen , Chang Hsing-Szu , Hsu Tzu-Min
Published: October 2007

The optical properties of InAs quantum dots (QDs) with a GaAs, an InAlAs, or an InAlAsSb overgrown layer are studied. For the InAs QDs with an InAlAsSb overgrown layer, their room temperature photoluminescence intensity is enhanced by as much as 4.5-fold compared to that of the QDs with an InAlAs one while maintaining similar narrow linewidth (26meV) and large ground-to first excited-state separation (103meV). The increase in radiative efficiency of the InAs∕InAlAsSb heterostructure is attributed to its better material quality due to the surfactant nature of Sb adatoms.
Self-Association and Crystallization of Amylose
Authors: Buléon Alain , Véronèse Gabrielle , Putaux Jean-Luc
Published: October 2007

Amylose, the linear constituent of starch, consists of α(1,4)-linked glucose monomers. Although weakly involved in the crystalline structure of starch, it can be recrystallized in a variety of allomorphic types, including those encountered in native starch (A- and B-types). Amylose can either be extracted from starch or produced in vitro by enzymatic synthesis using amylosucrase or phosphorylase. Recrystallization and self-association of amylose in aqueous solutions have been widely studied to understand both the crystallization of starch during biosynthesis and the structural changes that occur during starch processing. Depending on the chain length, concentration, and temperature, gels, spherulites, or lamellar crystals can be formed with A or B allomorphic type. Other ligand-dependent allomorphs (the various V-types) are obtained when amylose is complexed with molecules such as alcohols, lipids, or flavours. Amylose also self-associates into networks, spherulites, or axialites during in-vitro enzymatic synthesis by amylosucrase. When a highly branched acceptor like glycogen is used, dendritic nanoparticles are formed by elongation of the external chains. The recrystallization of amylose extracted from starch and the self-association of amylose during its in-vitro synthesis are described. The amylose properties are discussed in terms of polymer behaviour and model systems to investigate the structure and formation of starch granules.
Dissociating speech perception and comprehension at reduced levels of awareness
Authors: Davis Matthew H. , Coleman Martin R. , Absalom Anthony R. , Rodd Jennifer M. , Johnsrude Ingrid S. , Matta Basil F. , Owen Adrian M. , Menon David K.
Published: October 2007

We used functional MRI and the anesthetic agent propofol to assess the relationship among neural responses to speech, successful comprehension, and conscious awareness. Volunteers were scanned while listening to sentences containing ambiguous words, matched sentences without ambiguous words, and signal-correlated noise (SCN). During three scanning sessions, participants were nonsedated (awake), lightly sedated (a slowed response to conversation), and deeply sedated (no conversational response, rousable by loud command). Bilateral temporal-lobe responses for sentences compared with signal-correlated noise were observed at all three levels of sedation, although prefrontal and premotor responses to speech were absent at the deepest level of sedation. Additional inferior frontal and posterior temporal responses to ambiguous sentences provide a neural correlate of semantic processes critical for comprehending sentences containing ambiguous words. However, this additional response was absent during light sedation, suggesting a marked impairment of sentence comprehension. A significant decline in postscan recognition memory for sentences also suggests that sedation impaired encoding of sentences into memory, with left inferior frontal and temporal lobe responses during light sedation predicting subsequent recognition memory. These findings suggest a graded degradation of cognitive function in response to sedation such that “higher-level” semantic and mnemonic processes can be impaired at relatively low levels of sedation, whereas perceptual processing of speech remains resilient even during deep sedation. These results have important implications for understanding the relationship between speech comprehension and awareness in the healthy brain in patients receiving sedation and in patients with disorders of consciousness.
Hypertension and dysregulated proinflammatory cytokine production in receptor activity-modifying protein 1-deficient mice
Authors: Tsujikawa Kazutake , Yayama Katsutoshi , Hayashi Tamon , Matsushita Hiroaki , Yamaguchi Taijiro , Shigeno Tomomi , Ogitani Yusuke , Hirayama Megumi , Kato Tetsuya , Fukada So-ichiro , Takatori Shingo , Kawasaki Hiromu , Okamoto Hiroshi , Ikawa Masahito , Okabe Masaru , Yamamoto Hiroshi
Published: October 2007

Calcitonin gene-related peptide (CGRP) is thought to be a prominent neuropeptide in cardiovascular regulation and neuroimmune modulation. There are two isoforms of CGRP (αCGRP and βCGRP), and the main CGRP receptors are probably composed of a calcitonin receptor-like receptor (CLR) and a receptor activity-modifying protein (RAMP)1. However, the physiological functions of CGRP that are mediated through the CLR/RAMP1 receptors remain to be clarified. For an improved understanding of the functions, we generated mice deficient in RAMP1, a specific subunit of CGRP receptors, by a conditional gene-targeting technique. The RAMP1-deficient mice (RAMP1
−/−
) exhibited high blood pressure, with no changes in heart rate. αCGRP was found to have a potent vascular relaxant activity compared with βCGRP in the artery of the WT (RAMP1
+/+
) mice. The activities of both CGRP isoforms were remarkably suppressed in the arteries of the RAMP1
−/−
mice. The LPS-induced inflammatory responses of the RAMP1
−/−
mice revealed a transient and significant increase in the serum CGRP levels and high serum levels of proinflammatory cytokines compared with the RAMP1
+/+
mice. αCGRP and βCGRP equally suppressed the production of TNF-α and IL-12 in bone marrow-derived dendritic cells stimulated with lipopolysaccharide. Their inhibitory effects were not observed in the bone marrow-derived dendritic cells of the RAMP1
−/−
mice. These results indicate that CGRP signaling through CLR/RAMP1 receptors plays a crucial role in the regulation of both blood pressure by vascular relaxation and proinflammatory cytokine production from dendritic cells.
Continuous fat oxidation in acetyl–CoA carboxylase 2 knockout mice increases total energy expenditure, reduces fat mass, and improves insulin sensitivity
Authors: Choi Cheol Soo , Savage David B. , Abu-Elheiga Lutfi , Liu Zhen-Xiang , Kim Sheene , Kulkarni Ameya , Distefano Alberto , Hwang Yu-Jin , Reznick Richard M. , Codella Roberto , Zhang Dongyan , Cline Gary W. , Wakil Salih J. , Shulman Gerald I.
Published: October 2007

Acetyl–CoA carboxylase 2 (ACC)2 is a key regulator of mitochondrial fat oxidation. To examine the impact of ACC2 deletion on whole-body energy metabolism, we measured changes in substrate oxidation and total energy expenditure in
Acc2
−/−
and WT control mice fed either regular or high-fat diets. To determine insulin action
in vivo
, we also measured whole-body insulin-stimulated liver and muscle glucose metabolism during a hyperinsulinemic–euglycemic clamp in
Acc2
−/−
and WT control mice fed a high-fat diet. Contrary to previous studies that have suggested that increased fat oxidation might result in lower glucose oxidation, both fat and carbohydrate oxidation were simultaneously increased in
Acc2
−/−
mice. This increase in both fat and carbohydrate oxidation resulted in an increase in total energy expenditure, reductions in fat and lean body mass and prevention from diet-induced obesity. Furthermore,
Acc2
−/−
mice were protected from fat-induced peripheral and hepatic insulin resistance. These improvements in insulin-stimulated glucose metabolism were associated with reduced diacylglycerol content in muscle and liver, decreased PKCθ activity in muscle and PKCε activity in liver, and increased insulin-stimulated Akt2 activity in these tissues. Taken together with previous work demonstrating that
Acc2
−/−
mice have a normal lifespan, these data suggest that
Acc2
inhibition is a viable therapeutic option for the treatment of obesity and type 2 diabetes.
Altered phase diagram due to a single point mutation in human γD-crystallin
Authors: McManus Jennifer J. , Lomakin Aleksey , Ogun Olutayo , Pande Ajay , Basan Markus , Pande Jayanti , Benedek George B.
Published: October 2007

The P23T mutant of human γD-crystallin (HGD) is associated with cataract. We have previously investigated the solution properties of this mutant, as well as those of the closely related P23V and P23S mutants, and shown that although mutations at site 23 of HGD do not produce a significant structural change in the protein, they nevertheless profoundly alter the solubility of the protein. Remarkably, the solubility of the mutants decreases with increasing temperature, in sharp contrast to the behavior of the native protein. This inverted solubility corresponds to a strong increase in the binding energy with temperature. Here we have investigated the liquid–liquid coexistence curve and the diffusivity of the P23V mutant and find that these solution properties are unaffected by the mutation. This means that the chemical potentials in the solution phase are essentially unaltered. The apparent discrepancy between the interaction energies in the solution phase, as compared with the solid phase, is explicable in terms of highly anisotropic interprotein interactions, which are averaged out in the solution phase but are fully engaged in the solid phase.
Self-assembled lamellar complexes of siRNA with lipidic aminoglycoside derivatives promote efficient siRNA delivery and interference
Authors: Desigaux Léa , Sainlos Matthieu , Lambert Olivier , Chevre Raphael , Letrou-Bonneval Emilie , Vigneron Jean-Pierre , Lehn Pierre , Lehn Jean-Marie , Pitard Bruno
Published: October 2007

RNA interference requires efficient delivery of small double-stranded RNA molecules into the target cells and their subsequent incorporation into RNA-induced silencing complexes. Although current cationic lipids commonly used for DNA transfection have also been used for siRNA transfection, a clear need still exists for better siRNA delivery to improve the gene silencing efficiency. We synthesized a series of cationic lipids characterized by head groups bearing various aminoglycosides for specific interaction with RNA. siRNA complexation with such lipidic aminoglycoside derivatives exhibited three lipid/siRNA ratio-dependent domains of colloidal stability. Fluorescence and dynamic light-scattering experiments showed that cationic lipid/siRNA complexes were formed at lower charge ratios, exhibited a reduced zone of colloidal instability, and had smaller mean diameters compared with our previously described guanidinium-based cationic lipids. Cryo-transmission electron microscopy and x-ray-scattering experiments showed that, although the final
in toto
morphology of the lipid/siRNA complexes depended on the aminoglycoside type, there was a general supramolecular arrangement consisting of ordered lamellar domains with an even spacing of 67 Å. The most active cationic lipid/siRNA complexes for gene silencing were obtained with 4,5-disubstituted 2-deoxystreptamine aminoglycoside derivatives and were characterized by the siRNA being entrapped in small particles exhibiting lamellar microdomains corresponding to siRNA molecules sandwiched between the lipid bilayers. These results clearly show that lipidic aminoglycoside derivatives constitute a versatile class of siRNA nanocarriers allowing efficient gene silencing.
3′-
O
-modified nucleotides as reversible terminators for pyrosequencing
Authors: Wu Jian , Zhang Shenglong , Meng Qinglin , Cao Huanyan , Li Zengmin , Li Xiaoxu , Shi Shundi , Kim Dae Hyun , Bi Lanrong , Turro Nicholas J. , Ju Jingyue
Published: October 2007

Pyrosequencing is a method used to sequence DNA by detecting the pyrophosphate (PPi) group that is generated when a nucleotide is incorporated into the growing DNA strand in polymerase reaction. However, this method has an inherent difficulty in accurately deciphering the homopolymeric regions of the DNA templates. We report here the development of a method to solve this problem by using nucleotide reversible terminators. These nucleotide analogues are modified with a reversible chemical moiety capping the 3′-OH group to temporarily terminate the polymerase reaction. In this way, only one nucleotide is incorporated into the growing DNA strand even in homopolymeric regions. After detection of the PPi for sequence determination, the 3′-OH of the primer extension products is regenerated through different deprotection methods. Using an allyl or a 2-nitrobenzyl group as the reversible moiety to cap the 3′-OH of the four nucleotides, we have synthesized two sets of 3′-
O
-modified nucleotides, 3′-
O
-allyl-dNTPs and 3′-
O
-(2-nitrobenzyl)-dNTPs as reversible terminators for pyrosequencing. The capping moiety on the 3′-OH of the DNA extension product is efficiently removed after PPi detection by either a chemical method or photolysis. To sequence DNA, templates containing homopolymeric regions are immobilized on Sepharose beads, and then extension–signal detection–deprotection cycles are conducted by using the nucleotide reversible terminators on the DNA beads to unambiguously decipher the sequence of DNA templates. Our results establish that this reversible-terminator-pyrosequencing approach can be potentially developed into a powerful methodology to accurately determine DNA sequences.
Strategies for developing Green Super Rice
Authors: Zhang Qifa
Published: October 2007

From a global viewpoint, a number of challenges need to be met for sustainable rice production: (
i
) increasingly severe occurrence of insects and diseases and indiscriminate pesticide applications; (
ii
) high pressure for yield increase and overuse of fertilizers; (
iii
) water shortage and increasingly frequent occurrence of drought; and (
iv
) extensive cultivation in marginal lands. A combination of approaches based on the recent advances in genomic research has been formulated to address these challenges, with the long-term goal to develop rice cultivars referred to as Green Super Rice. On the premise of continued yield increase and quality improvement, Green Super Rice should possess resistances to multiple insects and diseases, high nutrient efficiency, and drought resistance, promising to greatly reduce the consumption of pesticides, chemical fertilizers, and water. Large efforts have been focused on identifying germplasms and discovering genes for resistance to diseases and insects, N- and P-use efficiency, drought resistance, grain quality, and yield. The approaches adopted include screening of germplasm collections and mutant libraries, gene discovery and identification, microarray analysis of differentially regulated genes under stressed conditions, and functional test of candidate genes by transgenic analysis. Genes for almost all of the traits have now been isolated in a global perspective and are gradually incorporated into genetic backgrounds of elite cultivars by molecular marker-assisted selection or transformation. It is anticipated that such strategies and efforts would eventually lead to the development of Green Super Rice.
Regulation of B cell homeostasis and activation by the tumor suppressor gene CYLD
Authors: Hövelmeyer Nadine , Wunderlich F. Thomas , Massoumi Ramin , Jakobsen Charlotte G. , Song Jian , Wörns Marcus A. , Merkwirth Carsten , Kovalenko Andrew , Aumailley Monique , Strand Dennis , Brüning Jens C. , Galle Peter R. , Wallach David , Fässler Reinhard , Waisman Ari
Published: October 2007

B cell homeostasis is regulated by multiple signaling processes, including nuclear factor-κB (NF-κB), BAFF-, and B cell receptor signaling. Conditional disruption of genes involved in these pathways has shed light on the mechanisms governing signaling from the cell surface to the nucleus. We describe a novel mouse strain that expresses solely and excessively a naturally occurring splice variant of CYLD (CYLDex7/8 mice), which is a deubiquitinating enzyme that is integral to NF-κB signaling. This shorter CYLD protein lacks the TRAF2 and NEMO binding sites present in full-length CYLD. A dramatic expansion of mature B lymphocyte populations in all peripheral lymphoid organs occurs in this strain. The B lymphocytes themselves exhibit prolonged survival and manifest a variety of signaling disarrangements that do not occur in mice with a complete deletion of CYLD. Although both the full-length and the mutant CYLD are able to interact with Bcl-3, a predominant nuclear accumulation of Bcl-3 occurs in the CYLD mutant B cells. More dramatic, however, is the accumulation of the NF-κB proteins p100 and RelB in CYLDex7/8 B cells, which, presumably in combination with nuclear Bcl-3, results in increased levels of Bcl-2 expression. These findings suggest that CYLD can both positively and negatively regulate signal transduction and homeostasis of B cells in vivo, depending on the expression of CYLD splice variants.
Different composition of the human and the mouse γδ T cell receptor explains different phenotypes of CD3γ and CD3δ immunodeficiencies
Authors: Siegers Gabrielle M. , Swamy Mahima , Fernández-Malavé Edgar , Minguet Susana , Rathmann Sylvia , Guardo Alberto C. , Pérez-Flores Verónica , Regueiro Jose R. , Alarcón Balbino , Fisch Paul , Schamel Wolfgang W.A.
Published: October 2007

The γδ T cell receptor for antigen (TCR) comprises the clonotypic TCRγδ, the CD3 (CD3γε and/or CD3δε), and the ζζ dimers. γδ T cells do not develop in CD3γ-deficient mice, whereas human patients lacking CD3γ have abundant peripheral blood γδ T cells expressing high γδ TCR levels. In an attempt to identify the molecular basis for these discordant phenotypes, we determined the stoichiometries of mouse and human γδ TCRs using blue native polyacrylamide gel electrophoresis and anti-TCR–specific antibodies. The γδ TCR isolated in digitonin from primary and cultured human γδ T cells includes CD3δ, with a TCRγδCD3ε2δγζ2 stoichiometry. In CD3γ-deficient patients, this may allow substitution of CD3γ by the CD3δ chain and thereby support γδ T cell development. In contrast, the mouse γδ TCR does not incorporate CD3δ and has a TCRγδCD3ε2γ2ζ2 stoichiometry. CD3γ-deficient mice exhibit a block in γδ T cell development. A human, but not a mouse, CD3δ transgene rescues γδ T cell development in mice lacking both mouse CD3δ and CD3γ chains. This suggests important structural and/or functional differences between human and mouse CD3δ chains during γδ T cell development. Collectively, our results indicate that the different γδ T cell phenotypes between CD3γ-deficient humans and mice can be explained by differences in their γδ TCR composition.
Putative IKDCs are functionally and developmentally similar to natural killer cells, but not to dendritic cells
Authors: Caminschi Irina , Ahmet Fatma , Heger Klaus , Brady Jason , Nutt Stephen L. , Vremec David , Pietersz Suzanne , Lahoud Mireille H. , Schofield Louis , Hansen Diana S. , O'Keeffe Meredith , Smyth Mark J. , Bedoui Sammy , Davey Gayle M. , Villadangos Jose A. , Heath William R. , Shortman Ken
Published: October 2007

Interferon-producing killer dendritic cells (IKDCs) have been described as possessing the lytic potential of NK cells and the antigen-presenting capacity of dendritic cells (DCs). In this study, we examine the lytic function and antigen-presenting capacity of mouse spleen IKDCs, including those found in DC preparations. IKDCs efficiently killed NK cell targets, without requiring additional activation stimuli. However, in our hands, when exposed to protein antigen or to MHC class II peptide, IKDCs induced little or no T cell proliferation relative to conventional DCs or plasmacytoid DCs, either before or after activation with CpG, or in several disease models. Certain developmental features indicated that IKDCs resembled NK cells more than DCs. IKDCs, like NK cells, did not express the transcription factor PU.1 and were absent from recombinase activating gene-2–null, common γ-chain–null (Rag2−/−Il2rg−/−) mice. When cultured with IL-15 and -18, IKDCs proliferated extensively, like NK cells. Under these conditions, a proportion of expanded IKDCs and NK cells expressed high levels of surface MHC class II. However, even such MHC class II+ IKDCs and NK cells induced poor T cell proliferative responses compared with DCs. Thus, IKDCs resemble NK cells functionally, and neither cell type could be induced to be effective antigen-presenting cells.
CD11cloB220+ interferon-producing killer dendritic cells are activated natural killer cells
Authors: Vosshenrich Christian A.J. , Lesjean-Pottier Sarah , Hasan Milena , Richard-Le Goff Odile , Corcuff Erwan , Mandelboim Ofer , Di Santo James P.
Published: October 2007

Interferon-producing killer dendritic cells (IKDCs) are a recently described subset of CD11cloB220+ cells that share phenotypic and functional properties of DCs and natural killer (NK) cells (Chan, C.W., E. Crafton, H.N. Fan, J. Flook, K. Yoshimura, M. Skarica, D. Brockstedt, T.W. Dubensky, M.F. Stins, L.L. Lanier, et al. 2006. Nat. Med. 12:207–213; Taieb, J., N. Chaput, C. Menard, L. Apetoh, E. Ullrich, M. Bonmort, M. Pequignot, N. Casares, M. Terme, C. Flament, et al. 2006. Nat. Med. 12:214–219). IKDC development appears unusual in that cytokines using the interleukin (IL)-2 receptor β (IL-2Rβ) chain but not those using the common γ chain (γc) are necessary for their generation. By directly comparing Rag2−/−γc−/y, Rag2−/−IL-2Rβ−/−, Rag2−/−IL-15−/−, and Rag2−/−IL-2−/− mice, we demonstrate that IKDC development parallels NK cell development in its strict IL-15 dependence. Moreover, IKDCs uniformly express NK-specific Ncr-1 transcripts (encoding NKp46), whereas NKp46+ cells are absent in Ncr1gfp/+γc−/y mice. Distinguishing features of IKDCs (CD11cloB220+MHC-II+) were carefully examined on developing NK cells in the bone marrow and on peripheral NK cells. As B220 expression was heterogeneous, defining B220lo versus B220hi NK1.1+ NK cells could be considered as arbitrary, and few phenotypic differences were noted between NK1.1+ NK cells bearing different levels of B220. CD11c expression did not correlate with B220 or major histocompatibility complex (MHC) class II (MHC-II) expression, and most MHC-II+ NK1.1+ cells did not express B220 and were thus not IKDCs. Finally, CD11c, MHC-II, and B220 levels were up-regulated on NK1.1+ cells upon activation in vitro or in vivo in a proliferation-dependent fashion. Our data suggest that the majority of CD11cloB220+ “IKDC-like” cells represent activated NK cells.
Relationship Between the Inoculum Density of Verticillium dahliae and the Progress of Verticillium Wilt of Olive
Authors: López-Escudero F. J. , Blanco-López M. A.
Published: October 2007

An experiment was conducted in microplots which were artificially infested with a defoliating isolate of Verticillium dahliae using seven different treatments of inoculum densities ranging from 0 to 10 microsclerotia per gram of soil (ppg). The experiment was conducted in Andalucía (southern Spain), and the susceptible Spanish olive cv. Picual was used to determine the relationship between pathogen inoculum density and the progress of Verticillium wilt of olive (VWO). The inoculum, produced on a sodium pectate cellophane medium, was found to efficiently infect olive trees. Symptoms first appeared 30 weeks after the trees were transplanted into infested soil. Periods of increasing disease incidence in the following seasons and years were mainly during spring and autumn, particularly in the second year after planting. Olive trees exhibited a high susceptibility to the defoliating pathotype of the pathogen, even at very low inoculum levels; in fact, diseased plants were encountered throughout the experiment regardless of the inoculum density treatment. Inoculum densities greater than 3 ppg in the soil resulted in final disease incidence greater than 50% for the trees after 2.5 years. Therefore, these inoculum densities must be considered very high for olive trees. There were no differences in final disease incidence, mean symptom severity, or area under the disease progress curve between plots infested with 10 or 3.33 ppg, whereas other treatments exhibited lower values for each of these disease parameters. The temporal variations of disease incidence and severity were highly correlated for the higher inoculum density treatments, with r2 values ranging from 0.92 to 0.84 for disease incidence and from 0.93 to 0.88 for severity. However, r2 was slightly lower for the treatments involving lower inoculum densities of the pathogen in microplots. The slopes of the linear regression curves were statistically different for nearly all the inoculum density treatments. Positive correlation was found between the initial inoculum density and final disease incidence values after the study period that was accurately explained by mathematical models. The results suggest that susceptible olive cultivars should not be planted in soils infested with virulent defoliating pathotypes of V. dahliae. Results also clarify that inoculum density levels obtained from field soil analyses can be used for establishing a risk prediction system with a view to controlling VWO in olive tree plantations.