bluuebunny/crossref_metadata_2025 huggingface dataset:
Vitamin D and glucocorticoids differentially modulate chemokine expression in human airway smooth muscle cells
Authors: Banerjee A , Damera G , Bhandare R , Gu S , Lopez‐Boado Y S , Panettieri R A , Tliba O
Published: June 2008

Background and purpose:

Chemokines play a critical role in the pathogenesis of asthma and facilitate the recruitment of inflammatory cells in the airways. Evidence now suggests that airway smooth muscle (ASM) may serve as a source of chemokines in inflamed airways. Although vitamin D has potent anti‐inflammatory propertiesin vitroin some cell types, its effects on ASM cells remain unclear. Here, we investigated whether 1α, 25‐dihydroxy vitamin D3(calcitriol) modulated chemokine production in ASM.

Experimental approach:

Human ASM cell cultures were derived from tracheal samples taken during surgery. ASM cells were treated with tumour necrosis factor alpha (TNFα) and/or interferon gamma (IFNγ) for 24 h in the presence of calcitriol and/or the glucocorticoid fluticasone added 2 h before. RANTES (regulated upon activation, normal T‐cell expressed and secreted), interferon‐inducible protein 10 (IP‐10) and fractalkine (FKN) levels in cell supernatants were measured by ELISA.

Key results:

In TNFα‐treated cells, calcitriol inhibited RANTES and IP‐10 secretion in a concentration‐dependent manner. FKN levels were negligible. In TNFα/IFNγ‐treated cells, whereas fluticasone or calcitriol alone partially inhibited RANTES secretion (by 38 and 20%, respectively), the combination of both drugs additively inhibited RANTES secretion (by 60%). No effect was observed on IP‐10 secretion. Whereas fluticasone enhanced FKN secretion (by 50%), calcitriol significantly decreased FKN levels (by 50%). Interestingly, calcitriol blocked the stimulatory effect of fluticasone on FKN secretion, which was inhibited by 60% with the combination of calcitriol and fluticasone.

Conclusions and implications:

These findings suggest that vitamin D uniquely modulates human ASM expression of chemokines and may exert some beneficial effects in the treatment of steroid‐resistant patients with asthma.

British Journal of Pharmacology(2008)155, 84–92; doi:10.1038/bjp.2008.232; published online 16 June 2008
Interactions between CB1receptors and TRPV1 channels mediated by 12‐HPETE are cytotoxic to mesencephalic dopaminergic neurons
Authors: Kim S R , Bok E , Chung Y C , Chung E S , Jin B K
Published: June 2008

Background and purposes:

We recently proposed the existence of neurotoxic interactions between the cannabinoid type 1 (CB1) receptor and transient receptor potential vanilloid 1 (TRPV1) channels in rat mesencephalic cultures. This study seeks evidence for the mediator(s) and mechanisms underlying the neurotoxic interactions between CB1receptors and TRPV1in vitroandin vivo.

Experimental approach:

The mediator(s) and mechanism(s) for the interactions between CB1receptors and TRPV1 were evaluated by cell viability assays, immunocytochemistry, Fura‐2 calcium imaging, mitochondrial morphology assay, ELISA and Western blot assayin vitroin neuron‐enriched mesencephalic cultures. Injections into the substantia nigra and subsequent cell counts were also used to confirm these interactionsin vivo.

Key results:

The neurotoxic interactions were mediated by 12(S)‐hydroperoxyeicosatetraenoic acid (12(S)‐HPETE), an endogenous TRPV1 agonist. CB1receptor agonists (HU210 and WIN55,212‐2) increased the level of 12(S)‐hydroxyeicosatetraenoic acid (12(S)‐HETE), a downstream metabolite of 12(S)‐HPETE, which stimulates TRPV1‐mediated death of mesencephalic neurons, bothin vitroandin vivo. The neurotoxicity was mediated by increased intracellular Ca2+concentration ([Ca2+]i) through TRPV1, consequently leading to mitochondrial damage and was attenuated by baicalein, a 12‐lipoxygenase inhibitor.

Conclusion and implications:

Activation of CB1receptors in rat mesencephalic neurons was associated with biosynthesis of 12(S)‐HPETE, which in turn stimulated TRPV1 activity, leading to increased [Ca2+]i, mitochondrial damage and neuronal death.

British Journal of Pharmacology(2008)155, 253–264; doi:10.1038/bjp.2008.246; published online 16 June 2008
Focusing on clathrin-mediated endocytosis
Authors: Rappoport Joshua Z.
Published: June 2008

Investigations into the mechanisms which regulate entry of integral membrane proteins, and associated ligands, into the cell through vesicular carriers (endocytosis) have greatly benefited from the application of live-cell imaging. Several excellent recent reviews have detailed specific aspects of endocytosis, such as entry of particular cargo, or the different routes of internalization. The aim of the present review is to highlight how advances in live-cell fluorescence microscopy have affected the study of clathrin-mediated endocytosis. The last decade has seen a tremendous increase in the development and dissemination of methods for imaging endocytosis in live cells, and this has been followed by a dramatic shift in the way this critical cellular pathway is studied and understood. The present review begins with a description of the technical advances which have permitted new types of experiment to be performed, as well as potential pitfalls of these new technologies. Subsequently, advances in the understanding of three key endocytic proteins will be addressed: clathrin, dynamin and AP-2 (adaptor protein 2). Although great strides have clearly been made in these areas in recent years, as is often the case, each answer has bred numerous questions. Furthermore, several examples are highlighted where, because of seemingly minor differences in experimental systems, what appear at first to be very similar studies have, at times, yielded vastly differing results and conclusions. Thus this is an exceedingly exciting time to study endocytosis, and this area serves as a clear demonstration of the power of applying live-cell imaging to answer fundamental biological questions.
Regulation of hypoxia-inducible factor-1α by NF-κB
Authors: van Uden Patrick , Kenneth Niall S. , Rocha Sonia
Published: June 2008

HIF (hypoxia-inducible factor) is the main transcription factor activated by low oxygen tensions. HIF-1α (and other α subunits) is tightly controlled mostly at the protein level, through the concerted action of a class of enzymes called PHDs (prolyl hydroxylases) 1, 2 and 3. Most of the knowledge of HIF derives from studies following hypoxic stress; however, HIF-1α stabilization is also found in non-hypoxic conditions through an unknown mechanism. In the present study, we demonstrate that NF-κB (nuclear factor κB) is a direct modulator of HIF-1α expression. The HIF-1α promoter is responsive to selective NF-κB subunits. siRNA (small interfering RNA) studies for individual NF-κB members revealed differential effects on HIF-1α mRNA levels, indicating that NF-κB can regulate basal HIF-1α expression. Finally, when endogenous NF-κB is induced by TNFα (tumour necrosis factor α) treatment, HIF-1α levels also change in an NF-κB-dependent manner. In conclusion, we find that NF-κB can regulate basal TNFα and, in certain circumstances, the hypoxia-induced HIF-1α.
A single bout of whole-body resistance exercise augments basal VLDL-triacylglycerol removal from plasma in healthy untrained men
Authors: Tsekouras Yiannis E. , Magkos Faidon , Prentzas Konstantinos I. , Basioukas Konstantinos N. , Matsama Stergoula G. , Yanni Amalia E. , Kavouras Stavros A. , Sidossis Labros S.
Published: June 2008

A single bout of prolonged aerobic exercise lowers plasma TAG (triacylglycerol) concentrations the next day by increasing the efficiency of VLDL (very-low-density lipoprotein)-TAG removal from the circulation. The effect of resistance exercise on VLDL-TAG metabolism is not known. Therefore we evaluated VLDL-TAG kinetics by using stable isotope-labelled tracers in eight healthy untrained men (age, 25.3±0.8 years; body mass index, 24.5±0.6 kg/m2) in the post-absorptive state in the morning on two separate occasions: once after performing a single 90-min bout of strenuous isokinetic resistance exercise (three sets×ten repetitions, 12 exercises at 80% of maximum peak torque production, with a 2-min rest interval between exercises) on the preceding afternoon and once after an equivalent period of rest. Fasting plasma VLDL-TAG concentrations in the morning after exercise were significantly lower than in the morning after rest (0.23±0.04 compared with 0.33±0.06 mmol/l respectively; P=0.001). Hepatic VLDL-TAG secretion rate was not different (P=0.31), but plasma clearance rate of VLDL-TAG was significantly higher (by 26±8%) after exercise than rest (31±3 compared with 25±3 ml/min respectively; P=0.004), and the mean residence time of VLDL-TAG in the circulation was significantly shorter (113±10 compared with 144±18 min respectively; P=0.02). Fasting plasma NEFA (non-esterified fatty acid; ‘free’ fatty acid) and serum β-hydroxybutyrate concentrations were both significantly higher after exercise than rest (P<0.05), whereas plasma glucose and serum insulin concentrations were not different (P>0.30). We conclude that, in healthy untrained men, a single bout of whole-body resistance exercise lowers fasting plasma VLDL-TAG concentrations by augmenting VLDL-TAG removal from plasma. The effect appears to be qualitatively and quantitatively similar to that reported previously for aerobic exercise.
High frequency dynamics in liquid nickel: An inelastic x-ray scattering study
Authors: Cazzato S. , Scopigno T. , Hosokawa S. , Inui M. , Pilgrim W.-C. , Ruocco G.
Published: June 2008

Owing to their large relatively thermal conductivity, peculiar, nonhydrodynamic features are expected to characterize the acousticlike excitations observed in liquid metals. We report here an experimental study of collective modes in molten nickel, a case of exceptional geophysical interest for its relevance in earth interior science. Our result shed light on previously reported contrasting evidences: In the explored energy-momentum region, no deviation from the generalized hydrodynamic picture describing nonconductive fluids is observed. Implications for high frequency transport properties in metallic fluids are discussed.
A robust volumetric apparatus and method for measuring high pressure hydrogen storage properties of nanostructured materials
Authors: Lachawiec Anthony J. , DiRaimondo Thomas R. , Yang Ralph T.
Published: June 2008

A volumetric apparatus to measure hydrogen adsorption and desorption at room temperature and up to 100atm has been constructed and studied for accuracy, reproducibility, and stability. The design principles are presented and considerable attention to detail is given to examine the effects of diurnal temperature changes in the manifold and helium adsorption by carbon-based adsorbents during free volume measurement. A heuristic for helium correction is derived from a model with a basis in literature and verified through calculation of adsorbent density. Several materials with well-known hydrogen capacities are studied to examine reproducibility. The microporous carbon AX-21 is studied to examine the effects of pressure step size and approach to equilibrium caused by gas mixing and the Joule–Thomson effect. Hydrogen spillover on a hybrid material, Pt on templated carbon, is examined for several loadings of metal. Kinetics of both physisorption and spillover are compared via the diffusion time constant (D∕R2) estimated by fitting models for pore and surface diffusion to time-dependent adsorption profiles. No concentration dependence was found for pore diffusion; however, the surface diffusion time constant was shown to decrease with respect to increasing hydrogen concentration.
Double photoionization and dication fragmentation of CF3I: Experiment and theory
Authors: Eland J. H. D. , Feifel R. , Hochlaf M.
Published: June 2008

The double photoionization of CF3I and the electronic structure and the dissociation dynamics of the CF3I++ dication have been investigated using large ab initio calculations and coincidence techniques. The double photoionization spectrum of CF3I consists of a continuous background with a number of narrow bands superimposed. The spectrum is attributed here to the population of groups of close lying electronic states interacting mutually by spin-orbit, spin-spin, and rovibronic couplings. At energies near the vertical double ionization threshold, CF3++I+ ionic fragments are produced. At higher energies, a very specific dissociation with double charge retained on one fragment, CF3I++→CF2I+++F becomes dominant and is attributed to a specific group of dication electronic states.
Low-lying isomers of Sin+ and Sin− (n=31–50) clusters
Authors: Zhou R. L. , Pan B. C.
Published: June 2008

We carry out a systematic search for the atomic structures of silicon cluster cations and anions in the size range n=31–50 using density functional theory in the generalized-gradient approximation. The obtained lowest-energy candidates feature cagelike structures. We find that the computed binding energies and the dissociation pathways as well as the mobilities of our lowest-energy isomers of the cations are all in good agreement with the measured data from experiments. Furthermore, based on these isomers, we reveal that the steplike feature appearing in the measured high-resolution mobilities can be correlated with the corresponding fullerenes explicitly, which strongly support the notion that endohedral silicon fullerenelike structures are the most favored growth pattern for silicon clusters in the range n=31–50. Our calculation and analysis suggest that the proposed isomers are probably very close to the major-abundance isomers observed in experiments.
Pressure-induced incompressibility of ReC and effect of metallic bonding on its hardness
Authors: Gou Huiyang , Hou Li , Zhang Jingwu , Gao Faming
Published: June 2008

The compressible behaviors of the selected 5d transition metal carbides MC (M=W,Re,Os,Ir) with hexagonal tungsten carbide-type structure were studied by first-principles calculations. Results indicate that the incompressibility of ReC exceeds that of diamond under higher pressure. The calculated method for hardness of crystals with partial metallic bonding is suggested and the calculated results indicate that hexagonal ReC crystal possesses excellent mechanical properties.
Fourier transform infrared observation and density functional theory study of the AlC3 and AlC3Al linear chains trapped in solid Ar
Authors: Bates S. A. , Rittby C. M. L. , Graham W. R. M.
Published: June 2008

The vibrational spectra of linear AlC3 and AlC3Al, formed by trapping the products of the dual laser evaporation of aluminum and carbon rods in solid Ar at ∼10K, were observed. Fourier transform infrared (FTIR) measurements of C13 isotopic shifts are in good agreement with the predictions of density functional theory (DFT) B3LYP∕6-311+G(3df) calculations, enabling the first assignments of the ν3(σu) and ν4(σu) fundamentals of (Σg+3) linear AlC3Al at 1624.0 and 528.3cm−1, respectively, and the ν2(σ) vibrational fundamental of (Π2) linear AlC3 at 1210.9cm−1.
Experimental study of the relationship between temperature and adhesive forces for low-alloyed steel, stainless steel, and titanium using atomic force microscopy in ultrahigh vacuum
Authors: Gåård A. , Krakhmalev P. , Bergström J. , Hirvonen Grytzelius J. , Zhang H. M.
Published: June 2008

Dry sliding contact between metallic surfaces is often associated with high surface temperatures due to frictional heating and adhesive wear, resulting in high friction and severe surface damage. In the present research, the dependence of adhesive forces on temperature, for commercial low-alloyed steel, stainless steel, and pure titanium, was investigated in ultrahigh vacuum at elevated temperatures using atomic force microscopy. It was found that adhesive forces increased as the temperature increased. Room-temperature values of adhesive forces decreased in the order Ti, stainless steel, and low-alloyed steel, which agreed with the values of the electron work function measured by a Kelvin probe. The findings correlate well with results observed for the same materials using conventional macroscopic tribotesters.
Investigation of strain relaxation mechanisms and transport properties in epitaxial SmNiO3 films
Authors: Conchon F. , Boulle A. , Guinebretière R. , Dooryhée E. , Hodeau J.-L. , Girardot C. , Pignard S. , Kreisel J. , Weiss F. , Libralesso L. , Lee T. L.
Published: June 2008

This article deals with strain relaxation in SmNiO3 epitaxial films deposited by chemical vapor deposition on SrTiO3 substrates. Thanks to x-ray reciprocal space mapping, we demonstrate that the strain relaxation is driven both “chemically” and “mechanically” by the formation of oxygen vacancies and misfit dislocations, respectively. Besides, a careful interpretation of the resistivity measurements allows us to highlight a correlation between the formation of oxygen vacancies, the stabilization of Ni3+, and the metal-insulator transition in the SmNiO3 films. Furthermore, using coplanar and grazing incidence diffraction, the shape of the strain gradient within the films is retrieved. This latter is calculated using a versatile scattering model involving B-spline functions. Finally, particular planar faults (Ruddlesden–Popper faults) that give rise to extended diffuse scattering on transverse scans are analyzed using a recent phenomenological model.
The Kirkwood–Buff integrals for one-component liquids
Authors: Ben-Naim Arieh
Published: June 2008

The Kirkwood–Buff integrals (KBIs) for one-component systems are calculated from either the pair correlation functions or from experimental macroscopic quantities. As in the case of mixtures, the KBIs provide important information on the local densities around a molecule. In the low density limit (ρ→0) one can extract from the KBI some information on the strength of the intermolecular forces. No such information may be extracted from the KBIs at higher densities. We used experimental data on densities and isothermal compressibilities to calculate the KBIs for various liquids ranging from inert molecules, to hydrocarbons, alcohols, and liquid water.
The effect of disorder on two-dimensional photonic crystal waveguides
Authors: Lima Leonardo L. , Alencar Márcio A. R. C. , Caetano Dilson P. , Solli Daniel R. , Hickmann Jandir M.
Published: June 2008

We investigate the effect of positional disorder on two-dimensional photonic crystal waveguides created by removing a line of cells from a finite 11×11 square lattice. By using transverse magnetic and transverse electric waves, we have studied three different configurations: disorder throughout the whole crystal, disorder only in the waveguide border, and disorder in the whole crystal except the waveguide border. We found that the waveguide performance is quite robust against disorder in the case where the waveguide border is not affected by disorder. In the other cases, disorder changes the size of the waveguide channel, which has a detrimental effect on the performance of the waveguide.
The exact connections of the effective thermal properties of ferroelectric crystals with domain configurations
Authors: Li J. Y. , Chen T.
Published: June 2008

Exact connections between the effective thermal expansion and pyroelectric coefficients and the effective elastic and piezoelectric coefficients have been established for trigonal, tetragonal, and hexagonal ferroelectric crystals with compatible domain configurations, taking advantage of compatible but not necessarily uniform internal field resulted from a hydrostatic stress and uniform temperature change. These exact connections reduce the number of independent material constants, and thus the number of necessary experimental measurements, and allow the determination of the effective thermal moduli of a ferroelectric crystal from its effective electroelastic moduli. Numerical results are also presented to demonstrate the application of such exact connections.
Probing the underlying physics of ejecta production from shocked Sn samples
Authors: Zellner M. B. , McNeil W. Vogan , Hammerberg J. E. , Hixson R. S. , Obst A. W. , Olson R. T. , Payton J. R. , Rigg P. A. , Routley N. , Stevens G. D. , Turley W. D. , Veeser L. , Buttler W. T.
Published: June 2008

This effort investigates the underlying physics of ejecta production for high explosive (HE) shocked Sn surfaces prepared with finishes typical to those roughened by tool marks left from machining processes. To investigate the physical mechanisms of ejecta production, we compiled and re-examined ejecta data from two experimental campaigns [W. S. Vogan et al., J. Appl. Phys. 98, 113508 (1998); M. B. Zellner et al., ibid. 102, 013522 (2007)] to form a self-consistent data set spanning a large parameter space. In the first campaign, ejecta created upon shock release at the back side of HE shocked Sn samples were characterized for samples with varying surface finishes but at similar shock-breakout pressures PSB. In the second campaign, ejecta were characterized for HE shocked Sn samples with a constant surface finish but at varying PSB.
Micro-Raman thermometry in the presence of complex stresses in GaN devices
Authors: Beechem T. , Christensen A. , Graham S. , Green D.
Published: June 2008

Raman thermometry is often utilized to measure temperature in gallium nitride (GaN) electronics. However, the accuracy of the technique is subject to errors arising from stresses which develop during device operation as a result of both thermoelastic and inverse piezoelectric effects. To assess the implications of these stresses on Raman thermometry, we investigate the use of the Stokes peak position, linewidth, and Stokes to anti-Stokes intensity ratio to estimate the temperature of GaN devices during operation. Our results indicate that only temperature measurements obtained from the intensity ratio method are independent of these stresses. Measurements using the linewidth, meanwhile, were found to correspond well with those obtained from the intensity ratio through the use of a reference condition which accounted for the stress dependency of this spectral component. These results were then compared to a three dimensional finite element model which yielded a correlation to within 5% between the computational and experimental methods. The peak position method, in contrast, was found to underpredict temperature in all circumstances due to the stress distribution which is present during device operation.
Electromigration behavior of lead-free solder flip chip bumps on NiP/Cu metallization
Authors: Jang J. W. , Ramanathan L. N. , Frear D. R.
Published: June 2008

The electromigration behavior of Sn–2.5Ag and Sn–0.7Cu (in wt %) flip chip solder joints on electroless NiP/Cu metallization at a current density of 1.3×104 A/cm2 was studied. For Sn-2.5 Ag solder, electromigration at 115 °C for 250 h showed a selective dissolution of Ni from the electroless NiP layer forming crystallized Ni3P. At 140 °C, the damage to the NiP layer was accelerated and instability of the NiP/Cu interface was observed. For eutectic Sn–0.7Cu solder, the electromigration behavior at a higher temperature was evaluated. At 180 °C, the NiP/Cu under bump metallurgy (UBM) started to show damage after 50 h. At 200 °C, the entire NiP/Cu layer was damaged, and P in the NiP layer moved to the edge of the anode much faster than the other species forming CuP2 intermetallics. NiP/Cu UBM experiences selective dissolution of Ni at lower temperatures, and the damage of the entire UBM occurred abruptly at the higher temperature.
In situ estimation of thin film growth rate, complex refractive index, and roughness during chemical vapor deposition using a modified moving horizon estimator
Authors: Xiong Rentian , Grover Martha A.
Published: June 2008

The primary method of estimating thin film properties from in situ reflectance measurements is the least squares fitting method. However, a state estimator offers a more rigorous approach to extract the quantities of interest from indirect measurements. The extended Kalman filter is a state estimator that has been applied previously in film deposition and etching processes. A modified moving horizon estimator was used here to estimate thin film growth rate, complex refractive index, and surface roughness in situ from a dual-wavelength reflectance measurement during a chemical vapor deposition process. Moving horizon estimation is a general framework, for which least squares fitting and the extended Kalman filter can be viewed as special cases. Predictions of the state estimates by the modified moving horizon estimator are compared with the predictions of the recursive least squares fitting method and the extended Kalman filter. The comparison of estimators is made first in simulations and then using experimental data. The simulation results indicate that the modified moving horizon estimator consistently yields more accurate estimates, by incorporating the prior estimates and error correlations in the optimization. The modified moving horizon estimator shows even more benefit in the experimental data, due to its enhanced robustness to nonideal behavior that is not included in the models.
A new photolysis laser-induced fluorescence instrument for the detection of H2O and HDO in the lower stratosphere
Authors: St. Clair J. M. , Hanisco T. F. , Weinstock E. M. , Moyer E. J. , Sayres D. S. , Keutsch F. N. , Kroll J. H. , Demusz J. N. , Allen N. T. , Smith J. B. , Spackman J. R. , Anderson J. G.
Published: June 2008

We present a new instrument, Hoxotope, for the in situ measurement of H2O and its heavy deuterium isotopologue (HDO) in the upper troposphere and lower stratosphere aboard the NASA WB-57. Sensitive measurements of δD are accomplished through the vacuum UV photolysis of water followed by laser-induced fluorescence detection of the resultant OH and OD photofragments. The photolysis laser-induced fluorescence technique can obtain S∕N>20 for 1ppbv HDO and S∕N>30 for 5ppmv H2O for 10s data, providing the sensitivity required for δD measurements in the tropopause region. The technique responds rapidly to changing water concentrations due to its inherently small sampling volume, augmented by steps taken to minimize water uptake on instrument plumbing. Data from the summer 2005 Aura Validation Experiment Water Isotope Intercomparison Flights (AVE-WIIF) out of Houston, TX show agreement for H2O between Hoxotope and the Harvard water vapor instrument and for HDO between Hoxotope and the Harvard ICOS water isotope instrument, to within stated instrument uncertainties. The successful intercomparison validates Hoxotope as a credible source of δD data in the upper troposphere and lower stratosphere.
Atomic ordering in CuZnAl shape memory alloys investigated via x-ray absorption and diffraction
Authors: Ciatto G. , Solari P. L. , De Panfilis S. , Fiorini A. L. , Amadori S. , Pasquini L. , Bonetti E.
Published: June 2008

We investigate the structure of the austenite phase in CuZnAl shape memory alloys by a combined x-ray absorption and diffraction analysis. Ab initio simulations of the near Zn-edge x-ray absorption coefficient allow us to directly discard the hypothesis of a DO3 superstructure. At the same time, we give evidence of the existence of an ordered structure (B2-like) different from the L21 one recently proposed by neutron diffraction. However, some partial L21 ordering is present at room temperature. This superstructure develops and recovers order when increasing the temperature above 400K.
Convective effect on the microstructure evolution during a liquid-liquid decomposition
Authors: Li H. L. , Zhao J. Z.
Published: June 2008

The microstructure evolution during a liquid-liquid phase transformation was calculated. The effect of convections on the microstructure development was investigated. The results demonstrate that the convective flow against the solidification direction causes an increase in the local nucleation rate. Convections lead to a more nonuniform distribution of the minority phase droplets (MPDs) in the melt. They cause an increase in the size of the largest MPDs and are against the obtaining of the immiscible alloys with a well dispersed microstructure.
Bending and buckling of rolled-up SiGe∕Si microtubes using nanorobotic manipulation
Authors: Zhang Li , Dong Lixin , Nelson Bradley J.
Published: June 2008

Mechanical properties of individual rolled-up SiGe∕Si microtubes are investigated experimentally using nanorobotic manipulation. By applying bending loads, individual SiGe∕Si microtubes demonstrate various deformation modes with increasing bending angle. Remarkably, the tested microtubes resist fracture even when bent back onto themselves (180° bending angle). Axial compression tests of microtubes with different turns are also performed. Among those tubes, 1.6-turn rolled-up SiGe∕Si microtubes show typical Euler buckling behavior when the load is larger than a critical load, which can be estimated by the Euler formula for columns.
Measurement of ultralow injection current to polymethyl-methacrylate film
Authors: Yan Feng , Hong Yi , Chan Helen L. W.
Published: June 2008

Ultralow electron/hole injection currents from an electrode to a polymethyl-methacrylate (PMMA) film can be accurately decided by measuring the slow shift in the flatband voltage of a metal-insulator-semiconductor (MIS) device. It has been found that both the electron and hole injection currents are limited by the metal/PMMA interface and can be roughly described with a modified Richardson–Schottky equation. The space charge or dipole relaxation in PMMA films has been observed as well, which induces an instant change in flatband voltage of the MIS devices. These properties are critical issues for the stability of organic thin film transistors with PMMA gate insulator.
The Human Müller-Lyer Illusion in Goalkeeping
Authors: van der Kamp John , Masters Rich S W
Published: June 2008

We examined whether a goalkeeper can influence a penalty-taker's actions by assuming postures that mimic Müller-Lyer configurations. The results of two studies indicate that (i) goalkeeper posture affects the perception of the goalkeeper's height in a manner consistent with the Müller-Lyer illusion; (ii) this influences penalty-taking accuracy; and (iii) a posture which resembles a wing-out Müller-Lyer configuration results in wider and lower throws.
Demographics, pollination syndrome and conservation status of Macrozamia platyrhachis (Zamiaceae), a geographically restricted Queensland cycad
Authors: Terry Irene , Forster Paul I. , Moore Chris J. , Roemer Robert B. , Machin Peter J.
Published: June 2008

To assess the International Union for Conservation of Nature (IUCN) status of Macrozamia platyrhachis F.M.Bailey, we surveyed this central Queensland cycad for its population abundance and health and its pollinator type and pollination syndrome (thermogenesis and volatile emissions). Plants are locally abundant within the 11 discrete populations surveyed, with an estimated population of 611 315 adult plants. Plants are highly restricted to a small area of occupancy, seed dispersal is nearly non-existent and extreme fires appear to have destroyed almost all seeds and seedlings and decimated the pollinators. Of known Macrozamia pollinators, only the thrips, Cycadothrips chadwicki Mound, were found on cones, and these were found in very low numbers. The pollination syndrome for this cycad appears to be unique, based on two cone traits. For one, thermogenesis peaks in early evening, a contrast with daytime peaks of other Cycadothrips-pollinated Macrozamia, but matches that of the Tranes weevil-pollinated Macrozamia machinii. In addition, cone volatiles include both previously unreported compounds as well as those reported exclusively on either Cycadothrips- or Tranes-pollinated species. Based on its small, fragmented area of occupancy, projected population declines and the unique pollination syndrome, we recommend that M. platyrhachis retain its current status as ‘Endangered’. Habitat management plans should stipulate that controlled burns be avoided during cycad coning season and that wildfires be controlled to minimise damage to seedlings and pollinators.
The dendrochronology of Callitris intratropica in northern Australia: annual ring structure, chronology development and climate correlations
Authors: Baker Patrick J. , Palmer Jonathan G. , D'Arrigo Rosanne
Published: June 2008

In this study we demonstrate the significant dendrochronological potential of Callitris intratropica, a native conifer distributed across much of the seasonal tropics of northern Australia. We developed two rigorously cross-dated chronologies from sites in the Northern Territory, Australia. The first chronology (1965–2004) was developed from plantation C. intratropica of known-age at Howard Springs and was heavily replicated both within and among trees to evaluate the quality of cross-dating for the species. The second chronology (1847–2006) was developed from trees growing naturally near Pine Creek and compared with long-term instrumental climate records to assess the potential for dendroclimatic reconstructions. Both chronologies had mean interseries correlations >0.65, the highest reported for a tropical tree species. The Howard Springs chronology demonstrated that C. intratropica produces anatomically distinct annual growth rings with the consistent ring-width variation within and among trees necessary for rigorous dendrochronological studies. The Pine Creek chronology exhibited statistically significant correlations with rainfall and the Palmer Drought Severity Index (PDSI; integrated measures of plant water stress), and to a lesser extent temperature. The strongest correlations between the climate data and tree-ring width indices were for early monsoon rainfall (October–December; Pearson’s r = 0.53) and late monsoon PDSI (May; Pearson’s r = 0.41). Our study demonstrates the significant potential of high-quality dendrochronological research on mainland Australia in general, and of C. intratropica, specifically, to reconstruct historical variation of the Australian monsoon system. In addition, C. intratropica may be able to provide novel insights into the dynamics of forests in the seasonal tropics of northern Australia and the role of disturbances, such as fire and cyclones, on these ecosystems.
Biologically active
Phytophthora
mating hormone prepared by catalytic asymmetric total synthesis
Authors: Harutyunyan Syuzanna R. , Zhao Zhijian , Hartog Tim den , Bouwmeester Klaas , Minnaard Adriaan J. , Feringa Ben L. , Govers Francine
Published: June 2008

A
Phytophthora
mating hormone with an array of 1,5-stereogenic centers has been synthesized by using our recently developed methodology of catalytic enantioselective conjugate addition of Grignard reagents. We applied this methodology in a diastereo- and enantioselective iterative route and obtained two of the 16 possible stereoisomers of
Phytophthora
hormone α1. These synthetic stereoisomers induced the formation of sexual spores (oospores) in A2 mating type strains of three heterothallic
Phytophthora
species,
P. infestans
,
P. capsici
, and
P. nicotianae
but not in A1 mating type strains. The response was concentration-dependent, and the oospores were viable. These results demonstrate that the biological activity of the synthetic hormone resembles that of the natural hormone α1. Mating hormones are essential components in the sexual life cycle of a variety of organisms. For plant pathogens like
Phytophthora
, sexual reproduction is important as a source of genetic variation. Moreover, the thick-walled oospores are the most durable propagules that can survive harsh environmental conditions. Sexual reproduction can thus greatly affect disease epidemics. The availability of synthetic compounds mimicking the activity of
Phytophthora
mating hormone will be instrumental for further unravelling sexual reproduction in this important group of plant pathogens.
PET and MRI show differences in cerebral asymmetry and functional connectivity between homo- and heterosexual subjects
Authors: Savic Ivanka , Lindström Per
Published: June 2008

Cerebral responses to putative pheromones and objects of sexual attraction were recently found to differ between homo- and heterosexual subjects. Although this observation may merely mirror perceptional differences, it raises the intriguing question as to whether certain sexually dimorphic features in the brain may differ between individuals of the same sex but different sexual orientation. We addressed this issue by studying hemispheric asymmetry and functional connectivity, two parameters that in previous publications have shown specific sex differences. Ninety subjects [25 heterosexual men (HeM) and women (HeW), and 20 homosexual men (HoM) and women (HoW)] were investigated with magnetic resonance volumetry of cerebral and cerebellar hemispheres. Fifty of them also participated in PET measurements of cerebral blood flow, used for analyses of functional connections from the right and left amygdalae. HeM and HoW showed a rightward cerebral asymmetry, whereas volumes of the cerebral hemispheres were symmetrical in HoM and HeW. No cerebellar asymmetries were found. Homosexual subjects also showed sex-atypical amygdala connections. In HoM, as in HeW, the connections were more widespread from the left amygdala; in HoW and HeM, on the other hand, from the right amygdala. Furthermore, in HoM and HeW the connections were primarily displayed with the contralateral amygdala and the anterior cingulate, in HeM and HoW with the caudate, putamen, and the prefrontal cortex. The present study shows sex-atypical cerebral asymmetry and functional connections in homosexual subjects. The results cannot be primarily ascribed to learned effects, and they suggest a linkage to neurobiological entities.
Minor spliceosome components are predominantly localized in the nucleus
Authors: Pessa Heli K. J. , Will Cindy L. , Meng Xiaojuan , Schneider Claudia , Watkins Nicholas J. , Perälä Nina , Nymark Mariann , Turunen Janne J. , Lührmann Reinhard , Frilander Mikko J.
Published: June 2008

Recently, it has been reported that there is a differential subcellular distribution of components of the minor U12-dependent and major U2-dependent spliceosome, and further that the minor spliceosome functions in the cytoplasm. To study the subcellular localization of the snRNA components of both the major and minor spliceosomes, we performedin situhybridizations with mouse tissues and human cells. In both cases, all spliceosomal snRNAs were nearly exclusively detected in the nucleus, and the minor U11 and U12 snRNAs were further shown to colocalize with U4 and U2, respectively, in human cells. Additionally, we examined the distribution of several spliceosomal snRNAs and proteins in nuclear and cytoplasmic fractions isolated from human cells. These studies revealed an identical subcellular distribution of components of both the U12- and U2-dependent spliceosomes. Thus, our data, combined with several earlier publications, establish that, like the major spliceosome, components of the U12-dependent spliceosome are localized predominantly in the nucleus.
Isoform- and cell cycle–dependent substrate degradation by the Fbw7 ubiquitin ligase
Authors: Grim Jonathan E. , Gustafson Michael P. , Hirata Roli K. , Hagar Amanda C. , Swanger Jherek , Welcker Markus , Hwang Harry C. , Ericsson Johan , Russell David W. , Clurman Bruce E.
Published: June 2008

The SCFFBW7 ubiquitin ligase degrades proteins involved in cell division, growth, and differentiation and is commonly mutated in cancers. The Fbw7 locus encodes three protein isoforms that occupy distinct subcellular localizations, suggesting that each has unique functions. We used gene targeting to create isoform-specific Fbw7-null mutations in human cells and found that the nucleoplasmic Fbw7α isoform accounts for almost all Fbw7 activity toward cyclin E, c-Myc, and sterol regulatory element binding protein 1. Cyclin E sensitivity to Fbw7 varies during the cell cycle, and this correlates with changes in cyclin E–cyclin-dependent kinase 2 (CDK2)–specific activity, cyclin E autophosphorylation, and CDK2 inhibitory phosphorylation. These data suggest that oscillations in cyclin E–CDK2-specific activity during the cell cycle regulate the timing of cyclin E degradation. Moreover, they highlight the utility of adeno-associated virus–mediated gene targeting in functional analyses of complex loci.
Generation of temperature-sensitive human metapneumovirus strains that provide protective immunity in hamsters
Authors: Herfst Sander , de Graaf Miranda , Schrauwen Eefje J. A. , Sprong Leo , Hussain Karim , van den Hoogen Bernadette G. , Osterhaus Albert D. M. E. , Fouchier Ron A. M.
Published: June 2008

Human metapneumovirus (HMPV) causes acute respiratory tract illness primarily in young children, immunocompromised individuals and the elderly. Vaccines would be desirable to prevent severe illnesses in these risk groups. Here, we describe the generation and evaluation of cold-passage (cp) temperature-sensitive (ts) HMPV strains as vaccine candidates. Repeated passage of HMPV at low temperatures in Vero cells resulted in the accumulation of mutations in the viral genome. Introduction of these mutations in a recombinant HMPV by reverse genetics resulted in a ts-phenotype, judged on the decreased shut-off temperature for virus replication in vitro. As an alternative approach, three previously described cp-respiratory syncytial virus (cp-HRSV) mutations were introduced in a recombinant HMPV, which also resulted in a low shut-off temperature in vitro. Replication of these ts-viruses containing either the cp-HMPV or cp-HRSV mutations was reduced in the upper respiratory tract (URT) and undetectable in the lower respiratory tract (LRT) of hamsters. Nevertheless, high titres of HMPV-specific antibodies were induced by both ts-viruses. Upon immunization with the ts-viruses, the LRT of hamsters were completely protected against challenge infection with a heterologous HMPV strain, and URT viral titres were reduced by 10 000-fold. In conclusion, we provide proof-of-principle for two candidate live-attenuated HMPV vaccines that induce cross-protective immunity to prevent infection of the LRT in Syrian golden hamsters. Further mapping of the molecular determinants of attenuation of HMPV should be the subject of future studies.
Transcriptional slippage prompts recoding in alternate reading frames in the hepatitis C virus (HCV) core sequence from strain HCV-1
Authors: Ratinier Maxime , Boulant Steeve , Combet Christophe , Targett-Adams Paul , McLauchlan John , Lavergne Jean-Pierre
Published: June 2008

Since the first report of frameshifting in HCV-1, its sequence has been the paradigm for examining the mechanism that directs alternative translation of the hepatitis C virus (HCV) genome. The region encoding the core protein from this strain contains a cluster of 10 adenines at codons 8–11, which is thought to direct programmed ribosomal frameshifting (PRF), but formal evidence for this process has not been established unequivocally. To identify the mechanisms of frameshifting, this study used a bicistronic dual luciferase reporter system in a coupled transcription/translation in vitro assay. This approach revealed +1 as well as –1 frameshifting, whereas point mutations, selectively introduced between codons 8 and 11, demonstrated that PRF did not readily account for frameshifting in strain HCV-1. Sequence analysis of cDNAs derived from RNA transcribed by T7 RNA polymerase in the dual luciferase reporter system, as well as in both a subgenomic replicon and an infectious clone derived from strain JFH1, identified additions and deletions of adenines between codons 8 and 11 due to transcriptional slippage (TS). Moreover, RNA isolated from cells infected with virus generated by JFH1 containing the A-rich tract also contained heterogeneity in the adenine sequence, strongly suggesting TS by the NS5B viral polymerase. These findings have important implications for insight into frameshifting events in HCV-1 and demonstrate for the first time the involvement of transcriptional slippage in this recoding event.
Complex genome-wide transcription dynamics orchestrated by Blimp1 for the specification of the germ cell lineage in mice
Authors: Kurimoto Kazuki , Yabuta Yukihiro , Ohinata Yasuhide , Shigeta Mayo , Yamanaka Kaori , Saitou Mitinori
Published: June 2008

Specification of germ cell fate is fundamental in development. With a highly representative single-cell microarray and rigorous quantitative PCR analysis, we defined the genome-wide transcription dynamics that create primordial germ cells (PGCs) from the epiblast, a process that exclusively segregates them from their somatic neighbors. We also analyzed the effect of the loss of Blimp1, a key transcriptional regulator, on these dynamics. Our analysis revealed that PGC specification involves complex, yet highly ordered regulation of a large number of genes, proceeding under the strong influence of mesoderm induction but specifically avoiding developmental programs such as the epithelial–mesenchymal transition, Hox cluster activation, cell cycle progression, and DNA methyltransferase machinery. Remarkably, Blimp1 is essential for repressing nearly all the genes normally down-regulated in PGCs relative to their somatic neighbors. In contrast, it is dispensable for the activation of approximately half of the genes up-regulated in PGCs, uncovering the Blimp1-independent events for PGC specification. Notably, however, highly PGC-specific genes exhibited distinct correlations to Blimp1 in wild-type embryos, and these correlations faithfully predicted their expression impairments in Blimp1 mutants. Moreover, their expression overlaps within single cells were severely damaged without Blimp1, demonstrating that Blimp1 exerts positive influence on their concerted activation. Thus, Blimp1 is not a single initiator but a dominant coordinator of the transcriptional program for the establishment of the germ cell fate in mice.
Mitochondrial dynamics and apoptosis
Authors: Suen Der-Fen , Norris Kristi L. , Youle Richard J.
Published: June 2008

In healthy cells, mitochondria continually divide and fuse to form a dynamic interconnecting network. The molecular machinery that mediates this organelle fission and fusion is necessary to maintain mitochondrial integrity, perhaps by facilitating DNA or protein quality control. This network disintegrates during apoptosis at the time of cytochrome c release and prior to caspase activation, yielding more numerous and smaller mitochondria. Recent work shows that proteins involved in mitochondrial fission and fusion also actively participate in apoptosis induction. This review will cover the recent advances and presents competing models on how the mitochondrial fission and fusion machinery may intersect apoptosis pathways.
Safeguarding parental identity: Dnmt1 maintains imprints during epigenetic reprogramming in early embryogenesis: Figure 1.
Authors: Branco Miguel R. , Oda Masaaki , Reik Wolf
Published: June 2008

During early mammalian embryogenesis, the genome undergoes global epigenetic reprogramming, losing most of its methylation before re-establishing it de novo at implantation. However, faithful maintenance of methylation at imprinted genes during this process is vital for embryonic development, but the DNA methyltransferase responsible for this maintenance has remained unknown. In this issue of Genes & Development, Hirasawa and colleagues (pp. 1607–1616) show that Dnmt1, and not Dnmt3a or Dnmt3b, maintains methylation at genomic imprints during preimplantation development.