bluuebunny/crossref_metadata_2025 huggingface dataset:
Noncontact atomic force microscopy studies of ultrathin films of amorphous solid water deposited on Au(111)
Authors: Donev J. M. K. , Yu Q. , Long B. R. , Bollinger R. K. , Fain S. C.
Published: August 2005

Noncontact atomic force microscopy was used to study the morphological changes of an ultrathin amorphous solid water (ASW) film as a function of deposition temperature, annealing temperature, and annealing time. ASW deposited at 80 or 108K on Au(111) formed truncated hemispherical clusters of increasing size during annealing at 134K; these clusters were inferred to be crystalline. The number of nuclei present at the outer surface of the film after deposition was greater for higher deposition temperature. For lower cluster densities, depletion of the ASW film around the clusters was observed when the clusters became larger and dendritic growth was observed when the apparent cluster footprint radius exceeded 100nm.
Vibrational energy transfer in O2(XΣg−3,υ=2,3)+O2 collisions at 330K
Authors: Kalogerakis Konstantinos S. , Copeland Richard A. , Slanger Tom G.
Published: August 2005

Vibrational relaxation of O2(XΣg−3,υ=2,3) by O2 molecules is studied via a two-laser approach. Laser radiation at 266nm photodissociates ozone in a mixture of molecular oxygen and ozone. The photolysis step produces vibrationally excited O2(aΔg1) that is rapidly converted to O2(XΣg−3,υ=2,3) in a near-resonant adiabatic electronic energy-transfer process involving collisions with ground-state O2. The output of a tunable 193-nm ArF laser monitors the temporal evolution of the O2(XΣg−3,υ=2,3) population via laser-induced fluorescence detected near 360nm. The rate coefficients for the vibrational relaxation of O2(XΣg−3,υ=2,3) in collision with O2 are 2.0−0.4+0.6×10−13cm3s−1 and (2.6±0.4)×10−13cm3s−1, respectively. These rate coefficients agree well with other experimental work but are significantly larger than those produced by various semiclassical theoretical calculations.
Formation of Ti silicide nanocrystals in the amorphous interlayers in ultrahigh-vacuum-deposited Ti thin films on (001)Si
Authors: Yang T. H. , Chi K. S. , Chen L. J.
Published: August 2005

A number of nanosize Ti silicides, Ti5Si3,Ti5Si4, and TiSi, were found to form simultaneously in the amorphous intermixing layer of annealed ultrahigh-vacuum-deposited Ti thin films on (001)Si. Autocorrelation function analysis has been applied to the high-resolution transmission electron microscope images to identify the phases formed in the initial stages of reaction. The intermediate silicide phases were detected to form earlier than that of the previous study owing to the superior sensitivity in detecting nanocrystals in an amorphous layer. The phase formation can be explained from the constructed metastable free-energy diagram.
Energy transfer and intermittency in four-dimensional turbulence
Authors: Suzuki Eijiro , Nakano Tohru , Takahashi Naoya , Gotoh Toshiyuki
Published: August 2005

The energy transfer and small scale intermittency in decaying turbulence in four dimensions are studied by direct numerical simulation and by spectral theory. It is found that (1) a 1∕2 law, −(1∕2)ε¯r, in four dimensional (4D) for the longitudinal third-order structure function holds, (2) the energy transfer in 4D is more efficient than in three dimensional (3D), (3) the Kolmogorov constant in 4D is K4=1.28 which is smaller than K3=1.72 in 3D, (4) the velocity gradient intermittency is stronger than in 3D, while (5) the total-energy dissipation rate in 4D is less intermittent than in 3D. The conflicting trends in (4) and (5) are explained by the changes in the balance between the convective and pressure terms as the dimension increases.
Read-out of micromechanical cantilever sensors by phase shifting interferometry
Authors: Helm M. , Servant J. J. , Saurenbach F. , Berger R.
Published: August 2005

White light interferometry was applied to determine the bending of micromechanical cantilever sensors (MCS) with an error typically less than 1permille. Deflections smaller than 2nm could be resolved at a lateral resolution of 2μm. Absolute values for curvatures can be determined and suitable reference points can be chosen on the MCS support. This was demonstrated in experiments using plasma polymerized polyallylamine films, which cross link upon ultraviolet light irradiation. The results suggest that 100μm long segments are sufficient to estimate reliable curvature radii of 450μm long microcantilever sensors.
Enhancement of phase separation in the InGaN layer for self-assembled In-rich quantum dots
Authors: Park Il-Kyu , Kwon Min-Ki , Baek Sung-Ho , Ok Young-Woo , Seong Tae-Yeon , Park Seong-Ju , Kim Yoon-Seok , Moon Yong-Tae , Kim Dong-Joon
Published: August 2005

The enhancement of phase separation in the InGaN layer grown on a GaN layer with a rough surface was investigated for the formation of self-assembled In-rich quantum dots (QDs) in the InGaN layer. Transmission electron microscopy images showed that In-rich QDs with a size of 2–5 nm were formed even in an InGaN layer with a low indium content, and a layer thickness less than the critical thickness. The room-temperature photoluminescence (PL) spectrum of this layer showed emission peaks corresponding to In-rich QDs. The temperature-dependent PL spectra showed dominant peak shifts to the lower energy side, indicating that the self-assembled In-rich QDs are formed in the InGaN layer grown on a rough GaN surface and that the carriers are localized in In-rich QDs.
Magnetic tuning of Fermi level for tunnel spintronics devices
Authors: Pogorelov Yu. G. , Sousa J. B. , Araújo J. P.
Published: August 2005

Treating itinerant magnetism within the simplest two-subband Hubbard model, it is shown that the variation of the Fermi energy under applied magnetic field is inversely proportional to the spontaneous magnetization (when the latter is small). Hence, the variation is most pronounced at closeness to the critical Stoner condition, that is to the quantum critical point of ferromagnetic condition. The perspectives of this result for magnetic tuning of tunnel conductance in spintronics devices are discussed.
Optical and electrical properties of nanostructured LaCoO3 thin films
Authors: Losurdo Maria , Sacchetti Alberto , Capezzuto Pio , Bruno Giovanni , Armelao Lidia , Barreca Davide , Bottaro Gregorio , Gasparotto Alberto , Maragno Cinzia , Tondello Eugenio
Published: August 2005

Nanostructured lanthanum cobaltite thin films have been grown on silica substrates by hybrid chemical vapor deposition/sol-gel approaches. The refractive index and the extinction coefficient of the specimens have been determined in the spectral range of 0.75–6.5 eV by spectroscopic ellipsometry. The conductivity of the films as a function of temperature has been also investigated, highlighting the different electrical behavior of LaCoO3 nanosystems as a function of the adopted synthetic strategy.
Ultrasound-modulated optical speckle measurement for scattering medium in a coaxial transmission system
Authors: Hisaka Masaki
Published: August 2005

Ultrasound-modulated optical speckle measurement interfaced with a charge-coupled device camera has been developed to study the biological speckle pattern behavior modulated by a pulsed-ultrasound wave propagating through strong scattering media in a coaxial transmission system. This method reveals an absorptive object located at 5.0 mm depth within a 10.0 millimeter thick impedance-matched scattering media with submillimeter spatial resolution. Introducing a quantitative value to the speckle pattern in order to evaluate the modulated patterns, we have succeeded in obtaining a series of absorptive distribution values, and simultaneously have improved the signal to noise ratio by 3.8 times.
Mechanism of field-aided lateral crystallization of amorphous silicon
Authors: Choi Duck-Kyun , Kim Hyun-Chul , Kim Young-Bae
Published: August 2005

The crystallization mechanism of the amorphous silicon using the field-aided lateral crystallization process was studied. The crystallization initiates at the negatively biased side and progresses towards the positively biased side with an enhanced velocity. In addition, the crystallization velocity increases monotonically as the applied voltage increases to a point, and then decreases beyond the critical voltage point. The current level measurement during the heat treatment of simple test patterns showed that the resistivity of the Ni-free amorphous silicon was reduced by 4 orders of magnitude at 510°C. The current density under the bias of 100V is in the range of 100A∕cm2, which is enough to cause the electromigration at that temperature. Using the Nernst-Einstein equation, we prove that the process is governed by competition between the field-assisted diffusion and electromigration.
Two-dimensional electrons at a cleaved semiconductor surface: Observation of the quantum Hall effect
Authors: Tsuji Yukihide , Mochizuki Toshimitsu , Okamoto Tohru
Published: August 2005

Low-temperature in-plane magnetotransport measurements have been performed on adsorbate-induced electron systems formed at in situ cleaved surfaces of p-type InAs. The Ag-coverage dependence of the surface electron density strongly supports a simple model based on a surface donor level lying above the conduction-band minimum. The observations of the quantized Hall resistance and zero longitudinal resistivity demonstrate the perfect two dimensionality of the surface electron system. We also observed the Rashba effect due to the strong asymmetry of the confining potential well.
Organic light-emitting devices with in situ postgrowth annealed organic layers
Authors: Chen B. J. , Sun X. W. , Wong T. K. S. , Hu X. , Uddin A.
Published: August 2005

A comparative study of in situ postgrowth annealing of organic layers before metal cathode was conducted on tris-(8-hydroxyqunoline) aluminum (Alq3)-based organic light-emitting devices (OLEDs). The devices were fabricated in the same run with a standard device without annealing for comparison, with an identical structure of indium tin oxide (ITO)/copper phthalocyanine (CuPc) (10nm)∕N,N′-di(naphthalene-l-yl)-N,N′-diphenyl-benzidine (NPB) (90nm)∕Alq3(90nm)∕Mg:Ag(200nm)∕Ag(20nm). The annealing temperature used was 60, 80, and 100°C, respectively. It was found that, in situ postgrowth annealing improves the device performance, and annealing near the glass transition temperature of NPB (99.7°C), improves device performance drastically. Power efficiency and current efficiency increase significantly with the annealing temperature, except the current efficiency for device annealed at 100°C is slightly lower than that of the standard device. The voltage and current density for 100cd∕m2 luminance are 5.6V and 4.4mA∕cm2, respectively, for the device annealed at 100°C, in comparison to 9.2V and 4.3mA∕cm2, respectively, for the standard device, the power efficiency is much improved by more than 40%. The in situ postgrowth annealed organic layers were characterized by photoluminescence and Raman spectroscopy.
Observation of hysteretic magnetoresistance in Mn-doped GaN nanowires with the mesoscopic Co and Ti∕Au contacts
Authors: Han Seong-Eok , Oh Hwangyou , Kim Ju-Jin , Seong Han-Kyu , Choi Heon-Jin
Published: August 2005

We have studied the spin dependent tunneling properties of Mn-doped GaN nanowires with ferromagnetic Co contacts. The magnetoresistances were measured between two ferromagnetic Co electrodes, or Co and Ti∕Au electrodes through Mn-doped GaN nanowires. The magnetoresistances of nanowire with the Co electrode indicate hysteretic behaviors, which are commonly observed in tunnel magnetoresistance devices. The magnetoresistance ratio increases from −0.6% at 20K to −9.4% at 1.74K. It is believed that the hysteretic magnetoresistances originate from the tunnel magnetoresistance effect between the ferromagnetic phases of nanowire and Co electrode.
The roles of the residues on the channel β-hairpin and loop structures of simian virus 40 hexameric helicase
Authors: Shen Jingping , Gai Dahai , Patrick Aaron , Greenleaf William B. , Chen Xiaojiang S.
Published: August 2005

Simian virus 40 large tumor antigen is required for DNA unwinding during viral replication. The helicase-active form of large tumor antigen is a ring-shaped hexamer/double hexamer, which has a positively charged hexameric channel for interacting with DNA. On the hexameric channel surface are six β-hairpin structures and loops, emanating from each of the six subunits. At the tips of the β-hairpin and the loop structures are two ring-shaped residues, H513 and F459, respectively. Additionally, two positively charged residues, K512 and K516, are near the tip of the β-hairpin. The positions of these ring-shaped and positively charged residues suggest that they may play a role in binding DNA for helicase function. To understand the roles of these residues in helicase function, we obtained a set of mutants and examined various activities, including oligomerization, ATPase, DNA binding, and helicase activities. We found that substitution of these residues by Ala abolished helicase activity. Extensive mutagenesis showed that substitutions by ring-shaped residues (W and Y) at position F459 and by residues with hydrophobic or long aliphatic side chains (W, Y, F, L, M, and R) at position H513 supported helicase activity. Our study demonstrated that the four residues (F459, H513, K512, and K516) play a critical role in interacting with DNA for helicase function. The results suggest a possible mechanism to explain how these residues, as well as the β-hairpin and the loop structures on which the residues reside, participate in binding and translocating DNA for origin melting and unwinding.
Modular evolution of egg case silk genes across orb-weaving spider superfamilies
Authors: Garb Jessica E. , Hayashi Cheryl Y.
Published: August 2005

Spider silk proteins (fibroins) are renowned for their extraordinary mechanical properties and biomimetic potential. Despite extensive evolutionary, ecological, and industrial interest in these fibroins, only a fraction of the known silk types have been characterized at the molecular level. Here we report cDNA and genomic sequences of the fibroin TuSp1, which appears to be the major component of tubuliform gland silk, a fiber exclusively synthesized by female spiders for egg case construction. We obtainedTuSp1sequences from 12 spider species that represent the extremes of phylogenetic diversity within the Orbicularia (orb-weaver superfamilies, Araneoidea and Deinopoidea) and finer scale sampling within genera.TuSp1encodes tandem arrays of an ≈200-aa-long repeat unit and individual repeats are readily aligned, even among species that diverged >125 million years ago. Analyses of these repeats across species reveal the strong influence of concerted evolution, resulting in intragenic homogenization. However, deinopoidTuSp1repeats also contain insertions of coding, minisatellite-like sequences, an apparent result of replication slippage and nonreciprocal recombination. Phylogenetic analyses of 37 spider fibroin sequences support the monophyly ofTuSp1within the spider fibroin gene family, consistent with a single origin of this ortholog group. The diversity of taxa and silks examined here confirms that repetitive architecture is a general feature of this gene family. Moreover, we show thatTuSp1provides a clear example of modular evolution across a range of phylogenetic levels.
A three-dimensional model of myxobacterial aggregation by contact-mediated interactions
Authors: Sozinova Olga , Jiang Yi , Kaiser Dale , Alber Mark
Published: August 2005

Myxobacteria provide one of the simplest models of cell–cell interaction and organized cell movement leading to cellular differentiation. When starved, tens of thousands of cells change their movement pattern from outward spreading to inward concentration; they form aggregates that become fruiting bodies. Cells inside fruiting bodies differentiate into round, nonmotile, environmentally resistant spores. Traditionally, cell aggregation has been considered to imply chemotaxis; a long-range cell interaction. However, myxobacterial aggregation is the consequence of direct cell-contact interactions, not chemotaxis. We present here a 3D stochastic lattice-gas cellular automata model of cell aggregation based on local cell–cell contact, and no chemotaxis. We demonstrate that a 3D discrete stochastic model can simulate two stages of cell aggregation. First, a “traffic jam” forms embedded in a field of motile cells. The jam then becomes an aggregation center that accumulates more cells. We show that, at high cell density, cells stream around the traffic jam, generating a 3D hemispherical mound. Later, when the nuclear traffic jam dissolves, the aggregation center becomes a 3D ring of streaming cells.
Structure of λ CII: Implications for recognition of direct-repeat DNA by an unusual tetrameric organization
Authors: Datta Ajit B. , Panjikar Santosh , Weiss Manfred S. , Chakrabarti Pinak , Parrack Pradeep
Published: August 2005

The temperate coliphage λ, after infecting its host bacterium
Escherichia coli
, can develop either along the lytic or the lysogenic pathway. Crucial to the lysis/lysogeny decision is the homotetrameric transcription-activator protein CII (4 × 11 kDa) of the phage that binds to a unique direct-repeat sequence T-T-G-C-N
6
-T-T-G-C at each of the three phage promoters it activates:
p
E
,
p
I
, and
p
aQ
. Several regions of CII have been identified for its various functions (DNA binding, oligomerization, and susceptibility to host protease), but the crystal structure of the protein long remained elusive. Here, we present the three-dimensional structure of CII at 2.6-Å resolution. The CII monomer is comprised of four α helices and a disordered C terminus. The first three helices (α1–α3) form a compact domain, whereas the fourth helix (α4) protrudes in different orientations in each subunit. A four-helix bundle, formed by α4 from each subunit, holds the tetramer. The quaternary structure can be described as a dimer of dimers, but the tetramer does not exhibit a closed symmetry. This unusual quaternary arrangement allows the placement of the helix–turn–helix motifs of two of the four CII subunits for interaction with successive major grooves of B-DNA, from one face of DNA. This structure provides a simple explanation for how a homotetrameric protein may recognize a direct-repeat DNA sequence rather than the inverted-repeat sequences of most prokaryotic activators.
Negative control of keratinocyte differentiation by Rho/CRIK signaling coupled with up-regulation of KyoT1/2 (FHL1) expression
Authors: Grossi Maddalena , Hiou-Feige Agnès , Di Vignano Alice Tommasi , Calautti Enzo , Ostano Paola , Lee Sam , Chiorino Giovanna , Dotto G. Paolo
Published: August 2005

Rho GTPases integrate control of cell structure and adhesion with downstream signaling events. In keratinocytes, RhoA is activated at early times of differentiation and plays an essential function in establishment of cell–cell adhesion. We report here that, surprisingly, Rho signaling suppresses downstream gene expression events associated with differentiation. Similar inhibitory effects are exerted by a specific Rho effector, CRIK (Citron kinase), which is selectively down-modulated with differentiation, thereby allowing the normal process to occur. The suppressing function of Rho/CRIK on differentiation is associated with induction of KyoT1/2, a LIM domain protein gene implicated in integrin-mediated processes and/or Notch signaling. Like activated Rho and CRIK, elevated KyoT1/2 expression suppresses differentiation. Thus, Rho signaling exerts an unexpectedly complex role in keratinocyte differentiation, which is coupled with induction of KyoT1/2, a LIM domain protein gene with a potentially important role in control of cell self renewal.
Inhibitor κB-like proteins from a polydnavirus inhibit NF-κB activation and suppress the insect immune response
Authors: Thoetkiattikul Honglada , Beck Markus H. , Strand Michael R.
Published: August 2005

Complex signaling pathways regulate the innate immune system of insects, with NF-κB transcription factors playing a central role in the activation of antimicrobial peptides and other immune genes. Although numerous studies have characterized the immune responses of insects to pathogens, comparatively little is known about the counterstrategies pathogens have evolved to circumvent host defenses. Among the most potent immunosuppressive pathogens of insects are polydnaviruses that are symbiotically associated with parasitoid wasps. Here, we report that theMicroplitis demolitorbracovirus encodes a family of genes with homology to inhibitor κB (IκB) proteins from insects and mammals. Functional analysis of two of these genes,H4andN5, were conducted inDrosophilaS2 cells. RecombinantH4andN5greatly reduced the expression of drosomycin and attacin reporter constructs, which are under NF-κB regulation through the Toll and Imd pathways. Coimmunoprecipitation experiments indicated that H4 and N5 bound to the Rel proteins Dif and Relish, and N5 also weakly bound to Dorsal. H4 and N5 also inhibited binding of Dif and Relish to κB sites in the promoters of the drosomycin and cecropin A1 genes. Collectively, these results indicate thatH4andN5function as IκBs and, circumstantially, suggest that other IκB-like gene family members are involved in the suppression of the insect immune system.
Independent and sequential recruitment of NHEJ and HR factors to DNA damage sites in mammalian cells
Authors: Kim Jong-Soo , Krasieva Tatiana B. , Kurumizaka Hitoshi , Chen David J. , Taylor A. Malcolm R. , Yokomori Kyoko
Published: August 2005

Damage recognition by repair/checkpoint factors is the critical first step of the DNA damage response. DNA double strand breaks (DSBs) activate checkpoint signaling and are repaired by nonhomologous end-joining (NHEJ) and homologous recombination (HR) pathways. However, in vivo kinetics of the individual factor responses and the mechanism of pathway choice are not well understood. We report cell cycle and time course analyses of checkpoint activation by ataxia-telangiectasia mutated and damage site recruitment of the repair factors in response to laser-induced DSBs. We found that MRN acts as a DNA damage marker, continuously localizing at unrepaired damage sites. Damage recognition by NHEJ factors precedes that of HR factors. HR factor recruitment is not influenced by NHEJ factor assembly and occurs throughout interphase. Damage site retention of NHEJ factors is transient, whereas HR factors persist at unrepaired lesions, revealing unique roles of the two pathways in mammalian cells.
Coantagonism of glutamate receptors and nicotinic acetylcholinergic receptors disrupts fear conditioning and latent inhibition of fear conditioning
Authors: Gould Thomas J. , Lewis Michael C.
Published: August 2005

The present study investigated the hypothesis that both nicotinic
acetylcholinergic receptors (nAChRs) and glutamate receptors
(α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPARs)
and N-methyl-d-aspartate glutamate receptors (NMDARs)) are
involved in fear conditioning, and may modulate similar processes. The effects
of the nAChR antagonist mecamylamine administered alone, the AMPAR antagonist
NBQX administered alone, and the NMDAR antagonist MK-801 administered alone on
cued fear conditioning, contextual fear conditioning, and latent inhibition of
cued fear conditioning were examined. In addition, the effects of
coadministration of either mecamylamine and NBQX or mecamylamine and MK-801 on
these behaviors were examined. Consistent with previous studies, neither
mecamylamine nor NBQX administered alone disrupted any of the tasks. However,
coadministration of mecamylamine and NBQX disrupted both contextual fear
conditioning and latent inhibition of cued fear conditioning. In addition,
coadministration of mecamylamine with a dose of MK-801 subthreshold for
disrupting either task disrupted both contextual fear conditioning and latent
inhibition of cued fear conditioning. Coadministration of mecamylamine and
NBQX, and coadministration of mecamylamine with a dose of MK-801 subthreshold
for disrupting fear conditioning had little effect on cued fear conditioning.
These results suggest that nAChRs and glutamate receptors may support similar
processes mediating acquisition of contextual fear conditioning and latent
inhibition of fear conditioning.
Calcium-activated proteases are critical for refilling depleted vesicle stores in cultured sensory-motor synapses ofAplysia
Authors: Khoutorsky Arkady , Spira Micha E.
Published: August 2005

Aplysiamotoneurons cocultured with a presynaptic sensory neuron exhibit homosynaptic depression when stimulated at low frequencies. A single bath application of serotonin (5HT) leads within seconds to facilitation of the depressed synapse. The facilitation is attributed to mobilization of neurotransmitter-containing vesicles from a feeding vesicle store to the depleted, readily releasable pool by protein kinase C (PKC). Here, we demonstrate that the calpain inhibitors, calpeptin, MG132, and ALLN, but not the proteasome inhibitors, lactacystin andclasto-lactacystin β-lactone, block 5HT-induced facilitation of depressed synapses. Likewise the 5HT-induced enhancement of spontaneous miniature potentials (mEPSPs) frequency of depressed synapses is significantly reduced by calpeptin. In contrast, neither the facilitation of nondepressed synapses nor the enhancement of their mEPSPs frequency is affected by the inhibitor. The data suggest that action potentials-induced calcium influx activate calpains. These, in turn, play a role in the refilling processes of the depleted, releasable vesicle store.
Inhibition of cholesterol biosynthesis by 25‐hydroxycholesterol is independent of OSBP
Authors: Nishimura Taki , Inoue Takao , Shibata Norihito , Sekine Azusa , Takabe Wakako , Noguchi Noriko , Arai Hiroyuki
Published: August 2005

25‐hydroxycholesterol (25‐HC) is a potent suppressor of cholesterol synthesis gene transcription in cultured cells. A high affinity binding protein for 25‐HC, oxysterol‐binding protein (OSBP), has been identified from tissue cytosol. OSBP translocates from the cytosol to the Golgi apparatus membranes after addition of 25‐HC to cell cultures and is thought to mediate 25‐HC action on cholesterol metabolism through association to the Golgi apparatus. However, direct evidence to prove this hypothesis was lacking. In this study, we knocked down expression of OSBP by using duplex siRNAs specific for OSBP to examine the relationship between OSBP and 25‐HC‐induced inhibition of cholesterol synthesis gene transcription. We found that decreasing OSBP expression by ∼90% did not affect 25‐HC‐induced inhibition of transcription of 3‐hydoxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase and squalene epoxidase to any extent. Exogenous lysophosphatidylcholine (LPC), which is known to cause the efflux of cellular cholesterol into the medium and to increase cholesterol synthesis, was found to rescue the 25‐HC‐induced down‐regulation of sterol regulated genes, while LPC did not affect 25‐HC‐induced association of OSBP with the Golgi apparatus. These results suggest that inhibition of cholesterol biosynthesis genes by 25‐HC is OSBP‐independent.
ROCK‐I and ROCK‐II cooperatively regulate closure of eyelid and ventral body wall in mouse embryo
Authors: Thumkeo Dean , Shimizu Yoshihiko , Sakamoto Satoko , Yamada Shuichi , Narumiya Shuh
Published: August 2005

Rho‐associated kinase (ROCK) is a serine/threonine kinase working in the Rho signaling to actin cytoskeleton. We previously reported that loss of ROCK‐I results in the eyelid open at birth (EOB) and omphalocele phenotype in mice, while loss of ROCK‐II results in placental dysfunction leading to intrauterine growth retardation and fetal death. Here, we report that after backcross to the C57BL/6 N genetic background, ROCK‐II knockout (KO) neonates are born also with open eyelid and umbilical hernia, a phenotype similar to that of ROCK‐I KO mice. ROCK‐II KO embryos show impaired extension of the eyelid epithelial sheet with disorganized actin bundles in the leading edge of the sheet. These results suggest that ROCK‐I and ROCK‐II cooperatively regulates the assembly of actin bundles essential for closure of the eyelid and ventral body wall in mouse embryos. Consistently, ROCK‐I+/–ROCK‐II+/– double heterozygous mice also show the EOB and omphalocele phenotype.
Drosophila melanogaster Rac2 is necessary for a proper cellular immune response
Authors: Williams Michael J. , Ando Istvan , Hultmark Dan
Published: August 2005

It has been reported that during Drosophila embryonic development, and in cell culture, that the Rac GTPases are redundant. To better elucidate Rac function in Drosophila, we decided to study the role of Rac2 in larval cellular defense reactions against the parasitiod Leptopilina boulardi. Here we show a dramatic effect in the context of cellular immunity where, unlike embryonic development, Rac2 appears to have a non‐redundant function. When an invading parasitoid is recognized as foreign, circulating hemocytes (blood cells) should recognize and attach to the egg chorion. After attachment the hemocytes should then spread to form a multilayered capsule surrounding the invader. In Rac2 mutants this process is disrupted. Immune surveillance cells, known as plasmatocytes, adhere to the parasitoid egg but fail to spread, and septate junctions do not assemble, possibly due to mislocalization of the Protein 4.1 homolog Coracle. Finally, larger cells known as lamellocytes attach to the capsule but also fail to spread, and there is a lack of melanization. From these results it appears that Rac2 is necessary for the larval cellular immune response.
Diffusion in plant cuticles as affected by temperature and size of organic solutes: similarity and diversity among species
Authors: BAUR P. , BUCHHOLZ A. , SCHÖNHERR J.
Published: August 2005

Mobilities of lipophilic organic solutes in cuticular membranes (CM) isolated from mature leaves of Citrus aurantium L., Citrus grandis L., Hedera helix L., IIex aquifolium L., Ilex paraguariensis St.‐Hil., Mains domestica Borkh., Prunus armeniaca L., Primus laurocerasus L., Pyrus communis L., Pyrus pyrifolia (Burm. f.) Nakai, Stephanotis florihunda Brongn. and Strophantus gratus Baill. were measured over a temperature range of 15–78°C. In this range, solute mobilities increased up to 1000‐fold, which corresponds to temperature coefficients Q10 of 3 (IAA in P. armeniaca) to 14 (cholesterol in H. helix). For most species, Arrhenius graphs showed good linearity up to 40°C, and up to 78°C for some species, while for others activation energies declined with increasing temperature. However, no distinct phase transitions caused by sudden structural changes in the CM were observed. In three species we examined whether heating to 70°C changed solute mobility irreversibly by comparing Arrhenius graphs for two successive experiments with the same CM. The two graphs were very similar for P. laurocerasus, while mobilities in the second graph were somewhat reduced for C. aurantium and greatly increased (at 25 and 35°C) for H. helix. This indicates rearrangements of at least some wax constituents when heated to high temperatures. The activation energies of diffusion (ED) ranged from 75 to 189 KJ mol−11 depending on species and solute size. Size selectivity and variability between cuticles decreased with increasing temperature, and this is caused by differences in (ED). An excellent correlation between the pre‐exponential factor of the Arrhenius equation and ED was observed, which is evidence that organic solutes differing greatly in molecular size (130–349 cm3 mol−1) and cuticle/water partition coefficient (25–108) use similar diffusion paths in the CM of all 12 plant species tested. Diffusion occurs in regions with identical physicochemical properties and differs only in magnitude.
Impact of iron deficiency and iron re‐supply during the early stages of vegetative development in maize (Zea mays L.)
Authors: THOIRON S. , PASCAL N. , BRIAT J.‐F.
Published: August 2005

The consequences of iron deficiency and iron re‐supply were evaluated during the early stages of growth and development of young maize plantlets grown hydroponically in the absence of iron. Various parameters, such as fresh and dry weights, and the concentration of chlorophylls, iron, copper, manganese, calcium, magnesium and potassium in leaves, were measured at various times during the first 15 d of culture. Ten‐day‐old maize plantlets grown without iron displayed severe alterations, with a 50% decrease in iron and chlorophyll concentrations in leaves, and serious impairments in mitochondria and chloroplast ultrastructure. In contrast, neither leaf nor root growth, nor other mineral concentrations other than iron were significantly affected at this stage of development. In an attempt to characterize proteins potentially involved in iron nutrition or the adaptative response to iron starvation, comparative 2D‐gel electrophoretic analysis of polypeptides was carried out on soluble and membrane fractions prepared from leaves and roots of iron‐deficient and iron‐sufficient 10‐d‐old maize plantlets. Two polypeptides (11 and 17 kDa, pI of about 6.8) from the microsomal fraction of leaves were found to be repressed under iron‐deficient conditions. Some other polypeptides were found to he induced in microsomal fractions either from roots or leaves. Significant variations in the concentration of most of these polypeptides were observed from one experiment to another. It can be concluded from this study that, at this early stage of maize vegetative growth and development, molecular variations induced by iron deficiency do not affect major house‐keeping proteins, but probably affect very specific events depending on low abundance proteins.
Attenuation of UV radiation by plant cuticles from woody species
Authors: KRAUSS P. , MARKSTÄDTER C. , RIEDERER M.
Published: August 2005

Transmittance spectra of isolated plant cuticles were measured in the wavelength range from 270 to 600 nm. The cuticles were enzymatically isolated from the leaves of 27 species (26 evergreen or deciduous woody, one succulent herbaceous) and from four species of fruits. With the exception of subtropical and tropical species all plants were cultivated in the field. The cuticles of the species studied strongly attenuated ultraviolet (UV) radiation at wavelengths < 400 nm while they were practically translucent in the visible range. Relatively broad transmittance minima occurred at wavelengths from 280 to 320 nm (UV‐B). Spectral transmittances at 300 nm ranged from 0.004 (Ilex aquifolium) to 0.50 (Prunus avium) for leaf cuticles and from 0.00023 (Cydonia oblonga) to 0.005 (Mains domestica) for fruit cuticles. The constitutive UV protection by cuticular pigments may be supplemented, to varying degrees, by pigments located in the epidermal cell wall and protoplast. Thus, it is concluded that only a small fraction of incident UV‐B radiation may actually reach the sensitive tissues of the leaves of non‐herbaceous species and of fruits.
Allergen immunotherapy with heat‐killed Listeria monocytogenes alleviates peanut and food‐induced anaphylaxis in dogs
Authors: Frick O. L. , Teuber S. S. , Buchanan B. B. , Morigasaki S. , Umetsu D. T.
Published: August 2005

Background:  Heat‐killed Listeria monocytogenes (HKL) potently stimulates interferon (IFN)‐γ production in CD4 T‐lymphocytes, and when used as adjuvant for immunotherapy, reduces immunoglobulin (Ig)E production and reverses established allergen‐induced airway hyperreactivity (AHR) in a murine model of asthma. We asked if such treatment could decrease established peanut‐induced anaphylaxis or cow's milk‐induced food allergy in highly food‐allergic dogs.

Methods:  We therefore studied four 4‐year‐old atopic colony dogs extremely allergic to peanut (Group I), as well as five 7‐year‐old dogs very allergic to wheat, milk and other foods (Group II). All dogs experienced marked allergic symptoms, including vomiting and diarrhea on oral challenge with the relevant foods. The dogs were then vaccinated once subcutaneously with peanut or milk and wheat with HKL emulsified in incomplete Freund's adjuvant.

Results:  Following vaccination of the allergic dogs with HKL and allergen, oral challenges with peanut (Group I) or milk (Group II) elicited only minor or no symptoms. In addition, skin test end‐point titrations showed marked reductions for >10 weeks after treatment, and levels of Ara h 1‐specific IgE in serum of peanut sensitive dogs, as demonstrated by immunoblotting, were greatly reduced by treatment with HKL plus peanut allergen.

Conclusions:  Thus, HKL plus allergen treatment markedly improved established food allergic responses in dogs, suggesting that such an immunotherapy strategy in humans might greatly improve individuals with food allergy and anaphylaxis.
Allergic rhinitis and asthma comorbidity in a survey of young adults in Italy
Authors: Bugiani M. , Carosso A. , Migliore E. , Piccioni P. , Corsico A. , Olivieri M. , Ferrari M. , Pirina P. , De Marco R. ,   ISAYA (ECRHS Italy) Study Group
Published: August 2005

Background:  Several studies have provided evidence of a strong association between asthma and allergic or nonallergic rhinitis, leading to the hypothesis that allergic rhinitis (AR) and asthma represent a continuum of the same disease.

Aim:  The aims of our study were: (i) to measure the comorbidity of AR and asthma and asthma‐like symptoms and (ii) to assess whether asthma, AR, and their coexistence share a common pattern of individual risk factors.

Methods:  The subjects are participants from the Italian multicentre, cross‐sectional survey on respiratory symptoms in the young adult general population (Italian Study of Asthma in Young Adults, ISAYA). The relationship between individual risk factors and asthma, AR and their coexistence, was studied by means of a multinomial logistic regression.

Results:  About 60% of asthmatics reported AR. On the other hand, subjects with AR presented an eightfold risk of having asthma compared to subjects without AR. Age was negatively associated with asthma [OR = 0.89, 95% confidence interval (CI): 0.82–0.96], AR (OR = 0.92, 95% CI: 0.86–0.98), and asthma associated with AR (OR = 0.83, 95% CI: 0.79–0.88). The risk of AR without asthma was significantly higher in the upper social classes (OR = 1.23, 95% CI: 1.08–1.39). Active current smoking exposure was positively associated with asthma alone (OR = 1.24, 95% CI: 1.09–1.41) and negatively associated with AR with (OR = 0.69, 95% CI: 0.54–0.88) or without (OR = 0.76, 95% CI: 0.69–0.84) asthma.

Conclusions:  Asthma and AR coexist in a substantial percentage of patients; bronchial asthma and AR, when associated, seem to share the same risk factors as AR alone while asthma without AR seems to be a different condition, at least with respect to some relevant risk factors.
Crack trapping effect of persistent grain boundary islands
Authors: KONG X. , QIAO Y.
Published: August 2005

In the polycrystalline Fe–Si alloy, when a cleavage front transmits from one grain to another, it first penetrates stably across the grain boundary at a number of breakthrough points (BTPs) that distribute along the front quasi‐periodically. As the critical energy release rate is reached, unstable crack jump occurs and the persistent grain boundary islands (PGBI) between the BTPs are left behind the verge of propagating, bridging across the crack flanks, which leads to a 10–30% increase in fracture resistance. In this article, this process is investigated through an energy analysis. The influence of the size/spacing ratio of PGBI on the grain boundary toughness is discussed in detail.
Determination of structural stress for fatigue analysis of welded aluminium components subjected to bending
Authors: MATIC T. , DOMAZET Z.
Published: August 2005

The results of extrapolation procedures for the determination of structural stresses are often questionable due to the fact that the stresses at extrapolation points obtained with finite element analyses can be strongly dependent on the mesh size of finite element model and loading mode. Also, existing design S–N curves are derived mostly on the basis of fatigue testing of joints loaded axially. In the present paper the influence of the finite element mesh size on the structural stress value determined by a linear extrapolation method is analysed. Also, the paper examines the possibility of using existing design S–N curves for cases of bending induced by a force on the welded stiffener. Fatigue test results from aluminium welded components with longitudinal or round pad stiffeners subjected to bending loads have been assessed using a structural stress range approach, and compared with the structural stress design S–N curve FAT 40 (IIW) and the structural stress design S–N curve FAT 44 (Eurocode 9). It is concluded that the more precise estimation of fatigue life of aluminium components subjected to bending can be achieved with structural stress design S–N curve proposed by Eurocode 9. The conclusions also include recommendations for regarding component finite element modelling for the determination of structural stresses in case of bending.
Using the Patchwork Text as a vehicle for promoting interprofessional health and social care collaboration in Higher Education
Authors: Crow Jayne , Smith Lesley , Jones Shirley
Published: August 2005

The promotion of effective interprofessional collaboration is very high on the UK government's agenda for reform and modernization of the Health and Social Care Services. As lecturers in Higher Education we are concerned with developing meaningful learning experiences that facilitate this collaboration in practice. To this end we introduced the Patchwork Text as an innovative form of teaching, learning and assessment and, in this article, we report the findings of our small exploratory study examining the student experience of the process and the potential of the Patchwork Text to facilitate interprofessional collaboration. We collected data from students via open‐ended questionnaires and a focus group discussion. The findings that emanated from the data showed that the iterative process of the Patchwork Text enabled students to develop and express the characteristics that are essential for collaborative working. It thus acted as a powerful vehicle for the learning and practice of collaboration in the classroom.
Basic Mechanisms of Monogenic Inheritance
Authors: Ziegler Andreas
Published: August 2005

To revive the appreciation of the importance of genetic studies for the understanding of neurologic diseases inherited in a monogenic fashion. After a description of the basic patterns of monogenic inheritance, the importance of linkage studies for the mapping of a disease gene is mentioned. Furthermore, the term linkage disequilibrium is introduced. Finally, several procedures used in current linkage analyses are briefly mentioned, with the aim of identifying the disease gene. The importance of genetic studies of disease families with many members, preferably from isolated surroundings to favor homogeneity, is stressed. However, such analyses can be performed only as a consequence of a close cooperation between clinicians and research scientists.
Overview: Epilepsy Surgery in Developing Countries
Authors: Wieser Heinz‐Gregor , Silfvenius Herbert
Published: August 2005

Summary: Epilepsy surgery (ES) is addressed in relation to economic classifications of national resources and welfare in developing countries. A decade ago, ten developing countries conducted ES; now 26 such countries have reported results of ES. A number of international authorities define indicators of national economic welfare. Adopting the economic classification of the International Monetary Fund, we find that ES is nonexistent in 98% of African countries, 76% of Asian countries, 58% of European countries, 82% of Middle East countries, and in 86% of countries of the Western Hemisphere. The 1980–1990 global ES survey conducted by the International League Against Epilepsy identified ten developing countries reporting ES (DCRES): Brazil, China, Czechoslovakia, Hungary, Mexico, Poland, Taiwan, the U.S.S.R., Yugoslavia, and Viet Nam. The present survey based on the proceedings of the 19th–23rd International Epilepsy Congresses and Medline reports from 1991 to November 1999 revealed at least 26 (18·3%) DCRES of 142 developing countries: Argentina, Brazil, Chile, China, Colombia, Czech Republic, Egypt, Estonia, Hungary, India, Iran, Israel, Korea, Lithuania, Mexico, P.R.China, the U.S.S.R., Singapore, Slovenia, South Africa, South Korea, Taiwan, Turkey, Ukraine, Uruguay, and former Yugoslavia. National vital statistics expose the hardships of developing countries. The population ratio of developed countries to developing countries is ∼ 1:5. The reverse per capita Gross Domestic Product ratio is 20:1. Great disparities exist in vital statistics, all to the disadvantage of the DCRES. The World Health Organization defines health‐related sectors geographically, then divides developing countries into several subgroups. Disability caused by length of disease and years lived with disability can be quantified monetarily for epilepsy, and the total health expenditures of developed and developing countries can be compared. The DCRES are short of technology, and their ES teams must choose from an excess of surgical candidates, investigating with computed tomography, magnetic resonance imaging, noninvasive video‐electroencephalography, and neuropsychology. The surgical outcomes achieved are similar to those in the developed world, but at a fractional cost. To internationalize ES, outcome, cost, and savings from care, evolution of assessment methodology is needed. Also needed is general support from the developed world.
Epilepsy Surgery in Developing Countries
Authors: Williamson Peter D. , Jobst Barbara C.
Published: August 2005

Summary: Epilepsy surgery (ES) is a well‐accepted treatment for medically intractable epilepsy patients in developed countries, but it is highly technology dependent. Such technology is not usually available in developing countries. For presurgical evaluation, magnetic resonance imaging (MRI) and electroencephalogram recording while videotaping the patient have been important. High technology equipment will, in conjunction with MRI, identify ∼70% of ES candidates. Introducing ES into developing countries will require determining the candidates that are appropriate for the existing medical infrastructure. This article reviews ES and its possible introduction into conditions existing in developing countries. The authors address (a) the types of patients to be considered for resective ES (some patients require a fairly standard series of noninvasive studies; others will require extensive invasive studies), (b) ways to determine which patients might be appropriate for the existing situation (unilateral mesial temporal lobe epilepsy detected with MRI, epilepsy with a circumscribed MRI lesion, hemispheric lesions, circumscribed MRI detected neuronal migration, and development disorders), (c) surgical procedures (local resection, functional hemispherectomy, multiple subpial transections, corpus callosotomy, and implantation of a vagal nerve stimulator), (d) special considerations for introducing ES into developing countries (medical infrastructure, technology, seizure monitoring systems, selective intracarotid/carotid Amytal testing, and surgical equipment), and (e) the limitations, realistic expectations, personnel requirements, and educational function for selected professionals. Delivery of the technology and expertise to perform ES in developing regions of the world is a realizable project, but it would be limited by available technology and existing medical infrastructure. It should be possible in most areas to train local personnel and thereby leave a lasting legacy.