bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the development of a nanosecond pulsed corona on a two-wire transmission line using the method of q-v curves
Authors: Nissim N. , Ashkenazy J. , Yankelevich Y. , Baksht R. , Pokryvailo A.
Published: November 2006

An indoor two-wire transmission line (TL) was used to investigate the development of corona discharge during the propagation of a short HV pulse, for both polarities. The pulse voltage peak ranged from 40 to 100 kV with a pulse width of 5 ns at the full-width half-maximum points. The charge per unit length q was derived from the measurement of the voltage and current at the beginning of the TL. The q-v hysteresis curves were used to analyze the properties of the corona developed along the TL. It was found that at peak voltages much higher than the corona onset voltage, the q-v curves’ characteristics were similar to those found for μs surge pulses at overhead transmission lines. For peak voltages close to the corona onset, the corona exhibited charge neutralization oscillations and the charge buildup delay time vanished. It was also found that the positive corona is up to about six times more dissipative than the negative one, even though the negative corona onset voltage was somewhat lower than the positive, and q at the peak voltage is similar for both polarities.
The model of level broadening in condensed phase
Authors: Basilevsky M. V. , Davidovich G. V. , Voronin A. I.
Published: November 2006

We study a model of non-Markovian kinetics for a harmonic oscillator embedded in a harmonic heat bath. We present a new scheme for approximately solving the quantum relaxation equation for the density matrix to find a distribution of level populations. It is found to be an extended Lorentzian with the width depending on the energy. A more convenient non-Markovian distribution called square root Fourier distribution that was implemented in the preceding paper [M. V. Basilevsky et al., J. Chem. Phys. 125, 194513 (2006)] is closely related to this extended Lorentzian model. Both distributions decay exponentially far away from their centers and reproduce well standard Lorentzian widths in the vicinity of the central region. A conventional Lorentzian model with such widths results when the Redfield approximation is applied in the frame of the present procedure.
Structural and electrical characteristics of Ga2O3(Gd2O3)∕GaAs under high temperature annealing
Authors: Chen C. P. , Lee Y. J. , Chang Y. C. , Yang Z. K. , Hong M. , Kwo J. , Lee H. Y. , Lay T. S.
Published: November 2006

Atomically smooth Ga2O3(Gd2O3)∕GaAs interface with low interfacial density of states and low electrical leakage currents have been achieved after the heterostructures were air exposed and tailor annealed to ∼750°C. The heat treatments, with annealing at an intermediate temperature of ∼300°C as a necessary step, were carried out under ultrahigh vacuum (UHV) and via standard rapid thermal annealing with flow of pure nitrogen gas. Furthermore, the oxide remains amorphous and minimal interfacial reaction occurred between the oxide and substrate, critical aspects for device performance. Studies using x-ray reflectivity and high-resolution transmission electron microscopy show that the interfacial roughness is <0.2 and <0.4nm for annealing under UHV and non-UHV, respectively. Electrical measurements on the metal-oxide-semiconductor diodes have exhibited low leakage currents (10−8–10−9A∕cm2), a dielectric constant of ⩾14, and a low interfacial density of states (Dit) of <1012cm−2eV−1.
Synthesis of high quality n-type CdS nanobelts and their applications in nanodevices
Authors: Ma R. M. , Dai L. , Huo H. B. , Yang W. Q. , Qin G. G. , Tan P. H. , Huang C. H. , Zheng J.
Published: November 2006

High quality n-type CdS nanobelts (NBs) were synthesized via an in situ indium doping chemical vapor deposition method and fabricated into field effect transistors (FETs). The electron concentrations and mobilities of these CdS NBs are around (1.0×1016–3.0×1017)∕cm3 and 100–350cm2∕Vs, respectively. An on-off ratio greater than 108 and a subthreshold swing as small as 65mV∕decade are obtained at room temperature, which give the best performance of CdS nanowire/nanobelt FETs reported so far. n-type CdS NB∕p+-Si heterojunction light emitting diodes were fabricated. Their electroluminescence spectra are dominated by an intense sharp band-edge emission and free from deep-level defect emissions.
Mechanism of interfacial layer suppression after performing surface Al(CH3)3 pretreatment during atomic layer deposition of Al2O3
Authors: Xu Min , Zhang Chi , Ding Shi-Jin , Lu Hong-Liang , Chen Wei , Sun Qing-Qing , Zhang David Wei , Wang Li-Kang
Published: November 2006

During atomic layer deposition of high permittivity (high-k) metal oxide gate dielectrics, an interfacial layer (IL) containing SiOx between high-k dielectric and Si substrate is almost unavoidable. However, an Al(CH3)3 (TMA) pretreatment for 3600s on H-terminated silicon surface can effectively reduce the interfacial layer from 1.7to0.5nm during atomic layer deposition of aluminum oxide. Interestingly, the surface TMA pretreatment increases the thickness of the initial IL during atomic layer deposition, but it greatly suppresses the final IL after 35 growth cycles. A reasonable mechanism is proposed based on the steric hindrance effect cofunctioning with the interfacial Al catalyzing effect.
Planar nanoscale architecture for organic thin-film field-effect transistors
Authors: Fine Daniel , Wang Liang , Sharma Deepak , Dodabalapur Ananth
Published: November 2006

A nanoscale architecture for an organic thin-film field-effect transistor is presented. It comprises an aluminum gate electrode, which forms its own oxide in air, placed near a titanium/gold source, and drain electrodes in the same horizontal plane. The gate to channel separation is about 50nm with the channel length also being around 50nm for the best performing devices. Although pentacene is used for the purpose of device demonstration, this architecture lends itself well to any organic or polymer semiconductor as well as the possibility for molecular devices.
Anisotropic broadening of Cu nanorods during glancing angle deposition
Authors: Kesapragada S. V. , Gall D.
Published: November 2006

Regular arrays of freestanding Cu nanostructures were grown on patterned Si substrates using glancing angle deposition (GLAD) from two oppositely positioned sputtering sources. Continuous azimuthal substrate rotation during deposition leads to the formation of vertical 430-nm-wide rods, which broaden anisotropically during subsequent growth with a stationary substrate. Statistical analyses of plan-view micrographs combined with numerical simulations indicate a linear increase in the width aspect ratio with deposition time that is attributed to a change in the growth front direction. This technique, termed simultaneous opposite GLAD, provides a unique approach for nanostructure shaping.
Hot phonons in Si-doped GaN
Authors: Liberis J. , Ramonas M. , Kiprijanovic O. , Matulionis A. , Goel N. , Simon J. , Wang K. , Xing H. , Jena D.
Published: November 2006

Microwave noise and electron transport are studied in silicon-doped GaN channels grown by molecular beam epitaxy and subjected to a high electric field. The drift velocity of 2.8×107cm∕s is reached at 290kV∕cm for n∼1×1018cm−3 channel. No negative differential resistance is observed. The noise temperature exceeds ∼5000K at ∼110kV∕cm for n∼3×1017cm−3 channel. The hot-phonon effect on power dissipation in GaN:Si is 3–4 times weaker as compared with the effect in an undoped AlGaN∕GaN two-dimensional channel. Monte Carlo simulation shows a weak effect of hot phonons on hot-electron energy distribution.
Photoluminescence and bowing parameters of InAsSb∕InAs multiple quantum wells grown by molecular beam epitaxy
Authors: Liu Po-Wei , Tsai G. , Lin H. H. , Krier A. , Zhuang Q. D. , Stone M.
Published: November 2006

Detailed studies are reported on the photoluminescence of InAsSb∕InAs multiple quantum wells grown by molecular beam epitaxy on InAs substrates with the Sb mole fraction ranging from 0.06 to 0.13. From 4K photoluminescence the band alignment was determined to be staggered type II. By comparing the emission peak energies with a transition energy calculation it was found that both the conduction and valence bands of InAsSb alloy exhibit some bowing. The bowing parameters were determined to be in the ratio of 4:6. For a sample with Sb composition ∼0.12 in the quantum well the photoluminescence emission band covers the CO2 absorption peak making it suitable for use in sources for CO2 detection.
Generation of misfit dislocations by basal-plane slip in InGaN∕GaN heterostructures
Authors: Liu R. , Mei J. , Srinivasan S. , Ponce F. A. , Omiya H. , Narukawa Y. , Mukai T.
Published: November 2006

The authors have observed that for InxGa1−xN epitaxial layers grown on bulk GaN substrates exhibit slip on the basal plane, when in the presence of free surfaces that intercept the heterointerface and for indium compositions x⩾0.07. This leads to almost complete relaxation of the local misfit strain by generation of radial-shape dislocation half loops. For x⩾0.17, generation of straight misfit dislocations by glide on the secondary ⟨112¯3⟩ {112¯2} slip system is observed, in addition to the radial-shape half loops at surface pits. These two mechanisms act independently with no observed interaction between them, leading to the conclusion that slip on the basal plane occurs first during the growth process. The secondary slip system is activated later and involves a significantly higher critical stress energy.
Self-assembly of ultrafine nanolines upon Ho reaction with the Ge(001) surface
Authors: Bonet C. , Tear S. P.
Published: November 2006

The reaction of the rare earth metal Ho with the Ge(001) surface at 440°C has been studied by scanning tunneling microscopy (STM). The self-assembly of ultrafine nanolines growing along substrate ⟨110⟩ directions has been observed, and based on atomic resolution STM images, the authors propose a model of the nanolines and comment on their relationship to the very initial stages of growth of a hexagonal germanide structure. The authors further report the presence of nanoscale trenches associated with well-ordered lines of missing dimer defects and discuss the relationship of these to the nanolines. Their results have possible applications involving interconnects or templating in nanoscale devices, and additionally, may provide insight into the nucleation mechanism of coarser nanowires.
Broadband solid state optical amplifier based on a semiconducting polymer
Authors: Amarasinghe D. , Ruseckas A. , Vasdekis A. E. , Goossens M. , Turnbull G. A. , Samuel I. D. W.
Published: November 2006

A compact, solid state optical amplifier based on the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] has been demonstrated. The amplifier was optically pumped. Gratings were used to couple the signal into and out of the film. The transmitted signal was amplified over 100 times in a 1mm long waveguide giving 21dB gain at 630nm. A gain of >13dB was observed at 615 and 650nm giving a gain bandwidth of >26THz. The gain dynamics at pump densities below 5μJ∕cm2 are described by an exciton-exciton annihilation model. At higher pump intensities, amplified spontaneous emission and photoinduced losses become significant.
Perfluorocyclobutane containing polymeric gate dielectric for organic thin film transistors with high on/off ratio
Authors: Ghim Jieun , Baeg Kang-Jun , Noh Yong-Young , Kang Seok-Ju , Jo Jang , Kim Dong-Yu , Cho Shinuk , Yuen Jonathan , Lee Kwanghee , Heeger Alan J.
Published: November 2006

A thermally cross-linkable perfluorocyclobutane (PFCB) polymer was synthesized and examined for use as the gate dielectric in organic thin film transistors (OTFTs). The PFCB polymer showed good solvent and process resistance during the photolithographic patterning of the electrodes. Bottom contact OTFTs were fabricated with poly(3-hexylthiophene)-2,5-diyl (P3HT) as the semiconductor, either spin cast or dip coated, on the PFCB gate dielectric. OTFTs fabricated with dip-coated P3HT showed a field effect mobility of 1.8×10−3cm2∕Vs and a high on/off current ratio of 8.3×106 in the saturation regime, with a source-drain voltage of VD=−50V.
Improvement of the thermoelectric characteristics of Fe-doped misfit-layered Ca3Co4−xFexO9+δ (x=, 0.05, 0.1, and 0.2)
Authors: Liu Chia-Jyi , Huang Li-Chen , Wang Jung-Sheng
Published: November 2006

The authors report measurements of the electrical resistivity, Seebeck coefficient, and thermal conductivity for a series of misfit-layered oxides Ca3Co4−xFexO9+δ (x=0, 0.05, 0.1, 0.15, 0.2) prepared by solid state reaction. Structural parameters are refined with superspace group of X2∕m(0b0)s0 using powder x-ray diffraction data. With partial substitution of Fe+2 for Co+3, the resistivity decreases, while the thermopower increases simultaneously. The x=0.05 sample exhibits a higher figure of merit (Z=3.01×10−4K−1) than that of Ca3Co4O9+δ (0.33×10−4K−1) at 300K, indicating much improvement of thermoelectric characteristics via partial substitution of Fe for Co.
Protective layer formation during oxidation of Cu3Au(100) using hyperthermal O2 molecular beam
Authors: Okada Michio , Hashinokuchi Michihiro , Fukuoka Masayuki , Kasai Toshio , Moritani Kousuke , Teraoka Yuden
Published: November 2006

Oxidation of Cu3Au(100) using a hyperthermal O2 molecular beam (HOMB) was investigated by x-ray photoemission spectroscopy in conjunction with a synchrotron light source. From the incident energy dependence of the O-uptake curve, it was determined that the dissociative adsorption of O2 implies a higher activation barrier and therefore less reactivity compared to Cu, owing to the Au alloying. The dissociative adsorption progresses with the Cu segregation on the surface. No prominent growth of Cu2O even for 2eV HOMB suggests that the Au alloying of Cu can serve as a protective layer against further oxidation into the bulk.
Incomplete Figure Perception and Invisible Masking
Authors: Chikhman Valery , Shelepin Yuri , Foreman Nigel , Merkuljev Aleksey , Pronin Sergey
Published: November 2006

The Gollin test (measuring recognition thresholds for fragmented line drawings of everyday objects and animals) has traditionally been regarded as a test of incomplete figure perception or ‘closure’, though there is a debate about how such closure is achieved. Here, figural incompleteness is considered to be the result of masking, such that absence of contour elements of a fragmented figure is the result of the influence of an ‘invisible’ mask. It is as though the figure is partly obscured by a mask having parameters identical to those of the background. This mask is ‘invisible’ only consciously, but for the early stages of visual processing it is real and has properties of multiplicative noise. Incomplete Gollin figures were modeled as the figure covered by the mask with randomly distributed transparent and opaque patches. We adjusted the statistical characteristics of the contour image and empty noise patches and processed those using spatial and spatial-frequency measures. Across 73 figures, despite inter-subject variability, mean recognition threshold was always approximately 15% of total contour in naive observers. Recognition worsened with increasing spectral similarity between the figure and the ‘invisible’ mask. Near threshold, the spectrum of the fragmented image was equally similar to that of the ‘invisible’ mask and complete image. The correlation between spectral parameters of figures at threshold and complete figures was greatest for figures that were most easily recognised. Across test sessions, thresholds reduced when either figure or mask parameters were familiar. We argue that recognition thresholds for Gollin stimuli in part reflect the extraction of signal from noise.
Triage in a public outpatient sexual health clinic
Authors: Knight Vickie , McNulty Anna
Published: November 2006

Background:The increasing prevalence of sexually transmissible infections in Australia, coupled with a NSW Health Department requirement to target services to those most in need, has led many services to investigate patient triage as a way of better using scarce resources.2 In October 1997, a Triage Nurse position was trialled that aimed to facilitate the optimal flow of patients through the Sydney Sexual Health Centre (SSHC) clinic in an efficient and patient-focussed manner. A pre and post implementation time-flow study was conducted to analyse the effect. A staff survey was also completed to ascertain staff acceptance of the Nurse Triage system. Methods:A time-flow data survey tool was developed and placed in the medical record of every person attending the SSHC in one month in 1997 and again in 1999. The staff survey was an 11-item likert scale questionnaire administered to all centre staff. Data were analysed and average visit and waiting times were generated. Results:When comparing 1997 with 1999 data, the main results of note were that the length of consultation had been stable or decreased, the average wait time had remained stable or decreased and the wait time in the medical and nursing unbooked clinic had decreased. The average wait time for the unbooked clinic had decreased from ~24 minutes in 1997 to ~12 minutes in 1999. Conclusions:Since the introduction of Nurse Triage, the average overall waiting times for those who attend without an appointment has halved and the wait to see a doctor and a nurse has decreased. The majority of staff felt that the triage process had improved patient flow.
Prolyl hydroxylase-1 negatively regulates IκB kinase-β, giving insight into hypoxia-induced NFκB activity
Authors: Cummins Eoin P. , Berra Edurne , Comerford Katrina M. , Ginouves Amandine , Fitzgerald Kathleen T. , Seeballuck Fergal , Godson Catherine , Nielsen Jens E. , Moynagh Paul , Pouyssegur Jacques , Taylor Cormac T.
Published: November 2006

Hypoxia is a feature of the microenvironment of a growing tumor. The transcription factor NFκB is activated in hypoxia, an event that has significant implications for tumor progression. Here, we demonstrate that hypoxia activates NFκB through a pathway involving activation of IκB kinase-β (IKKβ) leading to phosphorylation-dependent degradation of IκBα and liberation of NFκB. Furthermore, through increasing the pool and/or activation potential of IKKβ, hypoxia amplifies cellular sensitivity to stimulation with TNFα. Within its activation loop, IKKβ contains an evolutionarily conserved LxxLAP consensus motif for hydroxylation by prolyl hydroxylases (PHDs). Mimicking hypoxia by treatment of cells with siRNA against PHD-1 or PHD-2 or the pan-prolyl hydroxylase inhibitor DMOG results in NFκB activation. Conversely, overexpression of PHD-1 decreases cytokine-stimulated NFκB reporter activity, further suggesting a repressive role for PHD-1 in controlling the activity of NFκB. Hypoxia increases both the expression and activity of IKKβ, and site-directed mutagenesis of the proline residue (P191A) of the putative IKKβ hydroxylation site results in a loss of hypoxic inducibility. Thus, we hypothesize that hypoxia releases repression of NFκB activity through decreased PHD-dependent hydroxylation of IKKβ, an event that may contribute to tumor development and progression through amplification of tumorigenic signaling pathways.
Mst3b, a purine-sensitive Ste20-like protein kinase, regulates axon outgrowth
Authors: Irwin N. , Li Y.-M. , O'Toole J. E. , Benowitz L. I.
Published: November 2006

The growth of axons is fundamental to the development and repair of brain circuitry. We show here that Mst3b, a neuron-specific homolog of the yeast kinase Ste20, is critical for axon outgrowth. Mst3b is activated in response to trophic factors, and suppressing its expression (via siRNAs) or its function (by a dominant-negative mutant) blocks axon outgrowth. Inosine, a purine nucleoside that stimulates axon outgrowth, activates Mst3b kinase activity, whereas 6-thioguanine, a purine analog that blocks outgrowth, inhibits the activity of this kinase. These findings place Mst3b as a key regulator of axon outgrowth and help explain the purine sensitivity of this process.
Paclitaxel induces calcium oscillations via an inositol 1,4,5-trisphosphate receptor and neuronal calcium sensor 1-dependent mechanism
Authors: Boehmerle Wolfgang , Splittgerber Ute , Lazarus Michael B. , McKenzie Kathleen M. , Johnston David G. , Austin David J. , Ehrlich Barbara E.
Published: November 2006

Taxol (Paclitaxel) is an important natural product for the treatment of solid tumors. Despite a well documented tubulin-stabilizing effect, many side effects of taxol therapy cannot be explained by cytoskeletal mechanisms. In the present study submicromolar concentrations of taxol, mimicking concentrations found in patients, induced cytosolic calcium (Ca2+) oscillations in a human neuronal cell line. These oscillations were independent of extracellular and mitochondrial Ca2+but dependent on intact signaling via the phosphoinositide signaling pathway. We identified a taxol binding protein, neuronal Ca2+sensor 1 (NCS-1), a Ca2+binding protein that interacts with the inositol 1,4,5-trisphosphate receptor from a human brain cDNA phage display library. Taxol increased binding of NCS-1 to the inositol 1,4,5-trisphosphate receptor. Short hairpin RNA-mediated knockdown of NCS-1 in the same cell line abrogated the response to taxol but not to other agonists stimulating the phosphoinositide signaling pathway. These findings are important for studies involving taxol as a research tool in cell biology and may help to devise new strategies for the management of side effects induced by taxol therapy.
Elucidation of the function of type 1 human methionine aminopeptidase during cell cycle progression
Authors: Hu Xiaoyi , Addlagatta Anthony , Lu Jun , Matthews Brian W. , Liu Jun O.
Published: November 2006

Processing of the N-terminal initiator methionine is an essential cellular process conserved from prokaryotes to eukaryotes. The enzymes that remove N-terminal methionine are known as methionine aminopeptidases (MetAPs). Human MetAP2 has been shown to be required for the proliferation of endothelial cells and angiogenesis. The physiological function of MetAP1, however, has remained elusive. In this report we demonstrate that a family of inhibitors with a core structure of pyridine-2-carboxylic acid previously developed for the bacterial and yeast MetAP1 is also specific for human MetAP1 (
Hs
MetAP1), as confirmed by both enzymatic assay and high-resolution x-ray crystallography. Treatment of tumor cell lines with the MetAP1-specific inhibitors led to an accumulation of cells in the G
2
/M phase, suggesting that
Hs
MetAP1 may play an important role in G
2
/M phase transition. Overexpression of
Hs
MetAP1, but not
Hs
MetAP2, conferred resistance of cells to the inhibitors, and the inhibitors caused retention of N-terminal methionine of a known MetAP substrate, suggesting that
Hs
MetAP1 is the cellular target for the inhibitors. In addition, when
Hs
MetAP1 was knocked down by gene-specific siRNA, cells exhibited slower progression during G
2
/M phase, a phenotype similar to cells treated with MetAP1 inhibitors. Importantly, MetAP1 inhibitors were able to induce apoptosis of leukemia cell lines, presumably as a consequence of their interference with the G
2
/M phase checkpoint. Together, these results suggest that MetAP1 plays an important role in G
2
/M phase of the cell cycle and that it may serve as a promising target for the discovery and development of new anticancer agents.
Laser trapping in anisotropic fluids and polarization-controlled particle dynamics
Authors: Smalyukh Ivan I. , Kachynski Aliaksandr V. , Kuzmin Andrey N. , Prasad Paras N.
Published: November 2006

Anisotropic fluids are widespread, ranging from liquid crystals used in displays to ordered states of a biological cell interior. Optical trapping is potentially a powerful technique in the fundamental studies and applications of anisotropic fluids. We demonstrate that laser beams in these fluids can generate anisotropic optical trapping forces, even for particles larger than the trapping beam wavelength. Immersed colloidal particles modify the fluid's ordered molecular structures and locally distort its optic axis. This distortion produces a refractive index “corona” around the particles that depends on their surface characteristics. The laser beam can trap such particles not only at their center but also at the high-index corona. Trapping forces in the beam's lateral plane mimic the corona and are polarization-controlled. This control allows the optical forces to be reversed and cause the particle to follow a prescribed trajectory. Anisotropic particle dynamics in the trap varies with laser power because of the anisotropy of both viscous drag and trapping forces. Using thermotropic liquid crystals and biological materials, we show that these phenomena are quite general for all anisotropic fluids and impinge broadly on their quantitative studies using laser tweezers. Potential applications include modeling thermodynamic systems with anisotropic polarization-controlled potential wells, producing optically tunable photonic crystals, and fabricating light-controlled nano- and micropumps.
The gatekeeper residue controls autoactivation of ERK2 via a pathway of intramolecular connectivity
Authors: Emrick Michelle A. , Lee Thomas , Starkey Paul J. , Mumby Marc C. , Resing Katheryn A. , Ahn Natalie G.
Published: November 2006

Studies of protein kinases have identified a “gatekeeper” residue, which confers selectivity for binding nucleotides and small-molecule inhibitors. We report that, in the MAP kinase ERK2, mutations at the gatekeeper residue unexpectedly lead to autoactivation due to enhanced autophosphorylation of regulatory Tyr and Thr sites within the activation lip that control kinase activity. This occurs through an intramolecular mechanism, indicating that the gatekeeper residue indirectly constrains flexibility at the activation lip, precluding access of the phosphoacceptor residues to the catalytic base. Other residues that interact with the gatekeeper site to form a hydrophobic cluster in the N-terminal domain also cause autoactivation when mutated. Hydrogen-exchange studies of a mutant within this cluster reveal perturbations in the conserved DFG motif, predicting a route for side chain connectivity from the hydrophobic cluster to the activation lip. Mutations of residues along this route support this model, explaining how information about the gatekeeper residue identity can be transmitted to the activation lip. Thus, an N-terminal hydrophobic cluster that includes the gatekeeper forms a novel structural unit, which functions to maintain the “off” state of ERK2 before cell signal activation.
Characterization of a cancer/testis (CT) antigen gene family capable of eliciting humoral response in cancer patients
Authors: Parmigiani Raphael B. , Bettoni Fabiana , Vibranovski Maria D. , Lopes Marilene H. , Martins Waleska K. , Cunha Isabela W. , Soares Fernando A. , Simpson Andrew J. G. , de Souza Sandro J. , Camargo Anamaria A.
Published: November 2006

Cancer/testis (CT) antigens are immunogenic proteins expressed in normal gametogenic tissues and in different types of tumors. CT antigens are promising candidates for cancer immunotherapy, and the identification of novel CT antigens is a prerequisite for the development of cancer vaccines. We have identified a CT antigen, named CTSP-1, with partial similarity to the breast differentiation antigen NY-BR-1. CTSP-1 presents several splicing and polyadenylation variants and has a very restricted expression pattern among normal tissues. CTSP-1 is exclusively expressed in normal testis and is aberrantly expressed in 47.6% (10 of 21) of tumor cell lines and in 44.4% (75 of 169) of tumors from different histological types. The highest percentages of positive expression were observed in melanomas (59.0%) followed by prostate (58.0%) and lung (57.0%) tumors. CTSP-1 is part of a highly conserved gene family, and members of this family also have a restricted expression pattern and similar protein structure. Antibodies against members of this gene family were detected in 10% (14 of 141) of plasma samples from patients with a wide spectrum of tumors. The highest percentages of antibody response were observed in patients with prostate (20.8%), thyroid (20.0%), and breast (16.6%) tumors. Because of its very restricted expression pattern in normal tissues and immunogenicity in different types of tumors, CTSP-1 should be considered a promising candidate for cancer immunotherapy.
Estimation of Mean Body Temperature from Mean Skin and Core Temperature
Authors: Lenhardt Rainer , Sessler Daniel I.
Published: November 2006

Background

Mean body temperature (MBT) is the mass-weighted average temperature of body tissues. Core temperature is easy to measure, but direct measurement of peripheral tissue temperature is painful and risky and requires complex calculations. Alternatively MBT can be estimated from core and mean skin temperatures with a formula proposed by Burton in 1935: MBT = 0.64 x TCore + 0.36 x TSkin. This formula remains widely used, but has not been validated in the perioperative period and seems unlikely to remain accurate in dynamic perioperative conditions such as cardiopulmonary bypass. Therefore, the authors tested the hypothesis that MBT, as estimated with Burton's formula, poorly estimates measured MBT at a temperature range between 18 degrees and 36.5 degrees C.

Methods

The authors reevaluated four of their previously published studies in which core and mass-weighted mean peripheral tissue temperatures were measured in patients undergoing substantial thermal perturbations. Peripheral compartment temperatures were estimated using fourth-order regression and integration over volume from 18 intramuscular needle thermocouples, 9 skin temperatures, and "deep" hand and foot temperature. MBT was determined from mass-weighted average of core and peripheral tissue temperatures and estimated from core temperature and mean skin temperature (15 area-weighted sites) using Burton's formula.

Results

Nine hundred thirteen data pairs from 44 study subjects were included in the analysis. Measured MBT ranged from 18 degrees to 36.5 degrees C. There was a remarkably good relation between measured and estimated MBT: MBTmeasured = 0.94 x MBTestimated + 2.15, r = 0.98. Differences between the estimated and measured values averaged -0.09 degrees +/- 0.42 degrees C.

Conclusions

The authors concluded that estimation of MBT from mean skin and core temperatures is generally accurate and precise.
Extent and Localization of Changes in Upper Airway Caliber with Varying Concentrations of Sevoflurane in Children
Authors: Crawford Mark W. , Arrica Mauro , Macgowan Christopher K. , Yoo Shi-Joon
Published: November 2006

Background

Previous studies in humans suggest that inhibition of upper airway muscle activity is independent of the dose of inhalational anesthesia. Whether a dose-independent relation applies to changes in airway caliber is unknown. The authors sought to evaluate the configurational changes that lead to upper airway narrowing during inhalational anesthesia with sevoflurane and to determine whether these changes are dose dependent within a clinically relevant dose range.

Methods

Fifteen children undergoing elective magnetic resonance imaging of the brain were studied. Magnetic resonance images of the upper airway were acquired at sevoflurane concentrations of 0.5, 1.0, and 1.5 minimum alveolar concentration (MAC), administered in random sequence. At least 15 min was allowed for equilibration of inspired and alveolar partial pressures of sevoflurane. Images were acquired in early expiration at the level of the soft palate, base of the tongue, and tip of the epiglottis. Airway cross-sectional area (CSA), anteroposterior, and transverse dimension were determined using image-analysis software.

Results

At each anatomical level, pharyngeal CSA decreased progressively with increasing depth of sevoflurane anesthesia (P < 0.001). Increasing the sevoflurane concentration from 0.5 to 1.0 MAC reduced airway CSA by 13-18%, and a further increase to 1.5 MAC resulted in an overall 28-34% reduction in CSA. The reduction in CSA was predominantly due to a decrease in anteroposterior dimension.

Conclusions

Increasing the depth of sevoflurane anesthesia resulted in a relatively uniform reduction in pharyngeal caliber at each anatomical level studied. The effect of sevoflurane on upper airway caliber is dose dependent.
Strain and Sex Influence on Pain Sensitivity after Plantar Incision in the Mouse
Authors: Banik Ratan K. , Woo Young Cheol , Park Soo Seog , Brennan Timothy J.
Published: November 2006

Background

A small surgical incision in mouse glabrous hind-paw skin induces short-lasting guarding behavior and mechanical and heat hyperalgesia-like behaviors, which imitate human postoperative pain. The increasing popularity of this animal model in drug discovery necessitates the understanding of genetic and sex influence on this animal model.

Methods

The authors examined pain behaviors on DBA2, C57Bl/6, and 129X1/SvJ mice and male and female DBA2 mice before and after plantar incision.

Results

The baseline nociceptive responses of these strains were similar, with a few exceptions. Heat responses were different between DBA2 and C57Bl/6 mice, and responses to one filament, 14.0 mN, were intermittently different. Sex did not greatly influence baseline responses. After plantar incision, these three strains of mice were not different in the development of guarding behaviors. Heat responses were only different on postincision day 3 (129X1/SvJ vs. C57Bl/6 mice); otherwise, they were the same. The responses to the series of von Frey filaments were the same after incision in the three strains. Sex did not influence incision-induced pain behaviors in DBA2 mice.

Conclusion

Although several studies postulated that mouse strain influences pain models, the authors' data indicate that such influence on incisional pain is negligible. This suggests that studies using an incision and knockout mice resulting from 129 strain mutation in a C57BL/6 strain background should have modest influence. The lack of sex differences in incisional pain may encourage researchers to use both male and female subjects in their studies.
The tail of the Ordovician fishSacabambaspis
Authors: Pradel Alan , Sansom Ivan. J , Gagnier Pierre-Yves , Cespedes Ricardo , Janvier Philippe
Published: November 2006

The tail of the earliest known articulated fully skeletonized vertebrate, the arandaspidSacabambaspisfrom the Ordovician of Bolivia, is redescribed on the basis of further preparation of the only specimen in which it is most extensively preserved. The first, but soon discarded, reconstruction, which assumed the presence of a long horizontal notochordal lobe separating equal sized dorsal and ventral fin webs, appears to have considerable merit. Although the ventral web is significantly smaller than the dorsal one, the presence of a very long notochordal lobe bearing a small terminal web is confirmed. The discrepancy in the size of the ventral and dorsal webs rather suggests that the tail was hypocercal, a condition that would better accord with the caudal morphology of the living agnathans and the other jawless stem gnathostomes.
Reduced growth of Drosophila neurofibromatosis 1 mutants reflects a non-cell-autonomous requirement for GTPase-Activating Protein activity in larval neurons
Authors: Walker James A. , Tchoudakova Anna V. , McKenney Peter T. , Brill Suzanne , Wu Dongyun , Cowley Glenn S. , Hariharan Iswar K. , Bernards André
Published: November 2006

Neurofibromatosis type 1 (NF1) is among the most common genetic disorders of humans and is caused by loss of neurofibromin, a large and highly conserved protein whose only known function is to serve as a GTPase-Activating Protein (GAP) for Ras. However, most Drosophila NF1 mutant phenotypes, including an overall growth deficiency, are not readily modified by manipulating Ras signaling strength, but are rescued by increasing signaling through the cAMP-dependent protein kinase A pathway. This has led to suggestions that NF1 has distinct Ras- and cAMP-related functions. Here we report that the Drosophila NF1 growth defect reflects a non-cell-autonomous requirement for NF1 in larval neurons that express the R-Ras ortholog Ras2, that NF1 is a GAP for Ras1 and Ras2, and that a functional NF1-GAP catalytic domain is both necessary and sufficient for rescue. Moreover, a Drosophila p120RasGAP ortholog, when expressed in the appropriate cells, can substitute for NF1 in growth regulation. Our results show that loss of NF1 can give rise to non-cell-autonomous developmental defects, implicate aberrant Ras-mediated signaling in larval neurons as the primary cause of the NF1 growth deficiency, and argue against the notion that neurofibromin has separable Ras- and cAMP-related functions.
AtERF14, a Member of the ERF Family of Transcription Factors, Plays a Nonredundant Role in Plant Defense
Authors: Oñate-Sánchez Luis , Anderson Jonathan P. , Young Jodi , Singh Karam B.
Published: November 2006

We had previously shown that several transcription factors of the ethylene (ET) response factor (ERF) family were induced with different but overlapping kinetics following challenge of Arabidopsis (Arabidopsis thaliana) with Pseudomonas syringae pv tomato DC3000 (avrRpt2). One of these genes, a transcriptional activator, AtERF14, was induced at the same time as ERF-target genes (ChiB, basic chitinase). To unravel the potential function of AtERF14 in regulating the plant defense response, we have analyzed gain- and loss-of-function mutants. We show here that AtERF14 has a prominent role in the plant defense response, since overexpression of AtERF14 had dramatic effects on both plant phenotype and defense gene expression and AtERF14 loss-of-function mutants showed impaired induction of defense genes following exogenous ET treatment and increased susceptibility to Fusarium oxysporum. Moreover, the expression of other ERF genes involved in defense and ET/jasmonic acid responses, such as ERF1 and AtERF2, depends on AtERF14 expression. A number of ERFs have been shown to function in the defense response through overexpression. However, the effect of loss of AtERF14 function on defense gene expression, pathogen resistance, and regulation of the expression of other ERF genes is unique thus far. These results suggest a unique role for AtERF14 in regulating the plant defense response.
Putative Role of Aquaporins in Variable Hydraulic Conductance of Leaves in Response to Light
Authors: Cochard Hervé , Venisse Jean-Stéphane , Barigah Têtè Sévérien , Brunel Nicole , Herbette Stéphane , Guilliot Agnès , Tyree Melvin T. , Sakr Soulaiman
Published: November 2006

Molecular and physiological studies in walnut (Juglans regia) are combined to establish the putative role of leaf plasma membrane aquaporins in the response of leaf hydraulic conductance (K  leaf) to irradiance. The effects of light and temperature on K  leaf are described. Under dark conditions, K  leaf was low, but increased by 400% upon exposure to light. In contrast to dark conditions, K  leaf values of light-exposed leaves responded to temperature and 0.1 mm cycloheximide treatments. Furthermore, K  leaf was not related to stomatal aperture. Data of real-time reverse transcription-polymerase chain reaction showed that K  leaf dynamics were tightly correlated with the transcript abundance of two walnut aquaporins (JrPIP2,1 and JrPIP2,2). Low K  leaf in the dark was associated with down-regulation, whereas high K  leaf in the light was associated with up-regulation of JrPIP2. Light responses of K  leaf and aquaporin transcripts were reversible and inhibited by cycloheximide, indicating the importance of de novo protein biosynthesis in this process. Our results indicate that walnut leaves can rapidly change their hydraulic conductance and suggest that these changes can be explained by regulation of plasma membrane aquaporins. Model simulation suggests that variable leaf hydraulic conductance in walnut might enhance leaf gas exchanges while buffering leaf water status in response to ambient light fluctuations.
A Constitutive Shade-Avoidance Mutant Implicates TIR-NBS-LRR Proteins inArabidopsisPhotomorphogenic Development
Authors: Faigón-Soverna Ana , Harmon Franklin G. , Storani Leonardo , Karayekov Elizabeth , Staneloni Roberto J. , Gassmann Walter , Más Paloma , Casal Jorge J. , Kay Steve A. , Yanovsky Marcelo J.
Published: November 2006

In plants, light signals caused by the presence of neighbors accelerate stem growth and flowering and induce a more erect position of the leaves, a developmental strategy known as shade-avoidance syndrome. In addition, mutations in the photoreceptors that mediate shade-avoidance responses enhance disease susceptibility in Arabidopsis thaliana. Here, we describe the Arabidopsis constitutive shade-avoidance1 (csa1) mutant, which shows a shade-avoidance phenotype in the absence of shade and enhanced growth of a bacterial pathogen. The csa1 mutant has a T-DNA inserted within the second exon of a Toll/Interleukin1 receptor–nucleotide binding site–leucine-rich repeat (TIR-NBS-LRR) gene, which leads to the production of a truncated mRNA. Arabidopsis plants transformed with the truncated TIR-NBS-LRR gene recapitulate the mutant phenotype, indicating that csa1 is a dominant-negative mutation that interferes with phytochrome signaling. TIR-NBS-LRR proteins have been implicated in defense responses in plants. RPS4, the closest homolog of CSA1, confers resistance to Pseudomonas syringae and complements the csa1 mutant phenotype, indicating that responses to pathogens and neighbors share core-signaling components in Arabidopsis. In Drosophila melanogaster and Caenorhabditis elegans, TIR domain proteins are implicated in both development and immunity. Thus, the dual role of the TIR domain is conserved across kingdoms.
Subcellular Trafficking of the Arabidopsis Auxin Influx Carrier AUX1 Uses a Novel Pathway Distinct from PIN1
Authors: Kleine-Vehn Jürgen , Dhonukshe Pankaj , Swarup Ranjan , Bennett Malcolm , Friml Jiří
Published: November 2006

The directional flow of the plant hormone auxin mediates multiple developmental processes, including patterning and tropisms. Apical and basal plasma membrane localization of AUXIN-RESISTANT1 (AUX1) and PIN-FORMED1 (PIN1) auxin transport components underpins the directionality of intercellular auxin flow in Arabidopsis thaliana roots. Here, we examined the mechanism of polar trafficking of AUX1. Real-time live cell analysis along with subcellular markers revealed that AUX1 resides at the apical plasma membrane of protophloem cells and at highly dynamic subpopulations of Golgi apparatus and endosomes in all cell types. Plasma membrane and intracellular pools of AUX1 are interconnected by actin-dependent constitutive trafficking, which is not sensitive to the vesicle trafficking inhibitor brefeldin A. AUX1 subcellular dynamics are not influenced by the auxin influx inhibitor NOA but are blocked by the auxin efflux inhibitors TIBA and PBA. Furthermore, auxin transport inhibitors and interference with the sterol composition of membranes disrupt polar AUX1 distribution at the plasma membrane. Compared with PIN1 trafficking, AUX1 dynamics display different sensitivities to trafficking inhibitors and are independent of the endosomal trafficking regulator ARF GEF GNOM. Hence, AUX1 uses a novel trafficking pathway in plants that is distinct from PIN trafficking, providing an additional mechanism for the fine regulation of auxin transport.
Insights into Nuclear Organization in Plants as Revealed by the Dynamic Distribution ofArabidopsisSR Splicing Factors
Authors: Tillemans Vinciane , Leponce Isabelle , Rausin Glwadys , Dispa Laurence , Motte Patrick
Published: November 2006

Serine/arginine-rich (SR) proteins are splicing regulators that share a modular structure consisting of one or two N-terminal RNA recognition motif domains and a C-terminal RS-rich domain. We investigated the dynamic localization of the Arabidopsis thaliana SR protein RSZp22, which, as we showed previously, distributes in predominant speckle-like structures and in the nucleolus. To determine the role of RSZp22 diverse domains in its nucleolar distribution, we investigated the subnuclear localization of domain-deleted mutant proteins. Our results suggest that the nucleolar localization of RSZp22 does not depend on a single targeting signal but likely involves different domains/motifs. Photobleaching experiments demonstrated the unrestricted dynamics of RSZp22 between nuclear compartments. Selective inhibitor experiments of ongoing cellular phosphorylation influenced the rates of exchange of RSZp22 between the different nuclear territories, indicating that SR protein mobility is dependent on the phosphorylation state of the cell. Furthermore, based on a leptomycin B– and fluorescence loss in photobleaching–based sensitive assay, we suggest that RSZp22 is a nucleocytoplasmic shuttling protein. Finally, with electron microscopy, we confirmed that RSp31, a plant-specific SR protein, is dynamically distributed in nucleolar cap-like structures upon phosphorylation inhibition. Our findings emphasize the high mobility of Arabidopsis SR splicing factors and provide insights into the dynamic relationships between the different nuclear compartments.
SND1, a NAC Domain Transcription Factor, Is a Key Regulator of Secondary Wall Synthesis in Fibers ofArabidopsis
Authors: Zhong Ruiqin , Demura Taku , Ye Zheng-Hua
Published: November 2006

Secondary walls in fibers and tracheary elements constitute the most abundant biomass produced by plants. Although a number of genes involved in the biosynthesis of secondary wall components have been characterized, little is known about the molecular mechanisms underlying the coordinated expression of these genes. Here, we demonstrate that the Arabidopsis thaliana NAC (for NAM, ATAF1/2, and CUC2) domain transcription factor, SND1 (for secondary wall–associated NAC domain protein), is a key transcriptional switch regulating secondary wall synthesis in fibers. We show that SND1 is expressed specifically in interfascicular fibers and xylary fibers in stems and that dominant repression of SND1 causes a drastic reduction in the secondary wall thickening of fibers. Ectopic overexpression of SND1 results in activation of the expression of secondary wall biosynthetic genes, leading to massive deposition of secondary walls in cells that are normally nonsclerenchymatous. In addition, we have found that SND1 upregulates the expression of several transcription factors that are highly expressed in fibers during secondary wall synthesis. Together, our results reveal that SND1 is a key transcriptional activator involved in secondary wall biosynthesis in fibers.
Radiotherapy for metastatic melanoma presenting in pregnancy
Authors: Daly TA , Burmeister BH , Smithers BM , Doody J , Kane A
Published: November 2006

We describe the study of a patient with metastatic melanoma to axillary nodes presenting during pregnancy. The factors considered in her management are discussed, including issues related to staging, the decision not to terminate the pregnancy and the relative efficacy and fetal toxicity of the available treatment options. An overview of the known effects of radiotherapy on the fetus is presented and the technical alterations that were used to decrease the toxicity of radiotherapy are discussed.