bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid crystal alignment with a molecular template of imprinted polymer layer during phase separation
Authors: Kim Hak-Rin , Jung Jong-Wook , Lee You-Jin , Kim Jae-Hoon
Published: March 2006

We developed a liquid crystal (LC) alignment method using a molecular template of an imprinted polymer layer during polymerization-induced phase separation. Our results showed that the nematic ordering of LC is transferred to the polymer chain ordering during an anisotropic phase separation, which produces an anisotropic azimuthal surface anchoring. Using in-plane field treatment during phase separation, a twisted nematic cell is demonstrated.
Influence of surface segregation on the optical properties of semiconductor quantum wells
Authors: Schowalter M. , Rosenauer A. , Gerthsen D.
Published: March 2006

We studied the influence of surface segregation on optical properties of semiconductor quantum wells. This effect leads to significant deviations of composition profiles from expected rectangular profiles. The model of Muraki is used to simulate composition profiles of InGaAs∕GaAs quantum wells for different segregation efficiencies from which we derive potentials for electrons and holes. To compute eigenenergies the Schrödinger equation is numerically solved. The transition energies are calculated from the energy differences of electrons and holes as a function of segregation efficiency. We find that the optical properties are influenced for segregation efficiencies larger than 0.7.
Effects of nitrogen atom doping on dielectric constants of Hf-based gate oxides
Authors: Momida Hiroyoshi , Hamada Tomoyuki , Yamamoto Takenori , Uda Tsuyoshi , Umezawa Naoto , Chikyow Toyohiro , Shiraishi Kenji , Ohno Takahisa
Published: March 2006

We have theoretically shown that doping of N atoms increases the dielectric constant of the Hf silicates, enhancing both the electronic and lattice polarization contributions. The enhancement of the lattice contribution is dominant and is attributed to low-frequency vibration modes induced by the N doping. It is found that Hf and Si ions bonded to N atoms located at O vacancies largely vibrate in the modes and play a crucial role in the enhancement. Doped N atoms are shown to also improve the electric characteristic of the silicates, elevating O vacancy levels appearing in the band gap of the silicates.
Microcavity two-unit tandem organic light-emitting devices having a high efficiency
Authors: Cho Ting-Yi , Lin Chun-Liang , Wu Chung-Chih
Published: March 2006

In pursuit of further enhancement in luminance and efficiency of organic light-emitting devices (OLEDs), it is worth exploring what benefits could be obtained by combining two luminance-enhancement techniques, i.e., microcavity and tandem OLEDs. In this letter, we have investigated theoretically and experimentally the characteristics of noncavity and microcavity tandem OLEDs. Results show that with well designed microcavity and device structures (i.e., consistent with resonant and antinode conditions), a fivefold enhancement in luminance can be achieved with cavity tandem devices having only two emitting units. A very high efficiency of 200cd∕A has been demonstrated with a phosphorescent cavity two-unit device.
Dehydriding reaction of metal hydrides and alkali borohydrides enhanced by microwave irradiation
Authors: Nakamori Yuko , Orimo Shin-ichi , Tsutaoka Takanori
Published: March 2006

Effects of microwave irradiation on metal hydrides (LiH, NaH, MgH2, CaH2, and TiH2) and alkali borohydrides (LiBH4, NaBH4, and KBH4) were systematically investigated for the first time. TiH2 was heated to 600K by microwave irradiation for 3.5min, at which less than 0.16mass% of hydrogen was desorbed from surface of the powder. On the other hand, LiBH4 was heated rapidly above 380K, at which almost all hydrogen, 13mass%, was desorbed. The rapid heating of TiH2 is mainly due to conductive loss, while that of LiBH4 is related to a structural transition at approximately 380K.
InGaN
light-emitting diodes with naturally formed truncated micropyramids on top surface
Authors: Sheu J. K. , Tsai C. M. , Lee M. L. , Shei S. C. , Lai W. C.
Published: March 2006

GaN -based light-emitting diodes (LEDs) with truncated micropyramids surfaces performed by metalorganic chemical vapor deposition were demonstrated. In this study, a growth-interruption step and an Mg-treatment process were simultaneously performed to create multiple truncated micropyramids on LED surface. Experimental results indicated that GaN-based LEDs with the truncated micropyramids on the top surface demonstrate improved external efficiency of around 60% at 20mA. It is worth noting that the typical 20mA driven forward voltage is only 0.15V higher than that of conventional LEDs (LEDs with specular surface).
Photonic surgery with noncoherent light
Authors: Feuermann Daniel , Gordon Jeffrey M. , Ng Tuck Wah
Published: March 2006

Extensive photothermal surgical effects have been generated with artificial noncoherent light. Our ex vivo experiments produced the same type and extent of tissue damage ordinarily achieved with laser fiber-optic surgery, at comparable surgical efficacy, the motivation being the possibility of supplanting surgical lasers with a potentially far less expensive device. Maximum-flux optics reconstitute the immense power density at the core of an ultrabright discharge lamp inside an optical fiber the distal tip of which couples light into the organ.
Absence of ferromagnetism in Al-doped Zn0.9Co0.10O diluted magnetic semiconductors
Authors: Alaria J. , Bieber H. , Colis S. , Schmerber G. , Dinia A.
Published: March 2006

A 0.5% Al-doped Zn0.895Co0.100O polycrystalline powder was synthesized by the co-precipitation method. Raman spectroscopy revealed that divalent cobalt ions were substituted for Zn2+ ions into the ZnO matrix and that Al ions activate additional modes which are nonspecific to the dopant. These additional modes disappear after annealing at 1373K for 1h under Ar flow. We suggest that the electrical dopant becomes active in substitutional sites after annealing. Resistance measurements confirm that free carriers were created in our sample. Nevertheless, the sample shows the same magnetic properties: a mixture of paramagnetism and antiferromagnetism.
Highly efficient white organic light-emitting diode
Authors: Krummacher Benjamin C. , Choong Vi-En , Mathai Mathew K. , Choulis Stelios A. , So Franky , Jermann Frank , Fiedler Tim , Zachau M.
Published: March 2006

We present a highly efficient white electroluminescence device by the combination of a solution processed blue organic phosphorescence light-emitting diode with appropriate down-conversion phosphor system. The use of this down-conversion system produced an extraordinary enhancement on device performance, resulting in a white electroluminescence device with luminance efficacy of 25lm∕W at luminance efficiency reaching 39cd∕A. The extraordinary enhancement on device performance is attributed to isotropic radiation pattern of the excited phosphor particles, leading to high light extraction properties.
Introduction of an interlayer between metal and semiconductor for organic thin-film transistors
Authors: Park S. Young , Noh Young H. , Lee Hong H.
Published: March 2006

The concept of utilizing an organic interlayer between metal electrodes and underlying semiconductor is introduced for organic thin-film transistors. Inserting the interlayer between the source/drain electrodes and pentacene leads to improving the effective mobility by more than 1 order of magnitude and the on-off current ratio by almost 1 order of magnitude. The improvement can be attributed to a reduction in contact resistance that is made possible by reducing the energy barrier with the introduction of the interlayer. Simultaneous formation and patterning of both the electrodes and the interlayer is accomplished in one single-step transfer of a bilayer of metal on organic through a bilayer transfer technique based on rigiflex lithography.
Characterization of As-doped, p-type ZnO by x-ray absorption near-edge structure spectroscopy
Authors: Vaithianathan Veeramuthu , Lee Byung-Teak , Chang Chang-Hwan , Asokan Kandasami , Kim Sang Sub
Published: March 2006

The x-ray absorption near-edge structure (XANES) spectroscopy has been used as a “fingerprint” to address the unresolved issues related to the changes in the local structure around As and to identify its chemical state in the As-doped, p-type ZnO. The spectral features of both AsK- and OK-edge XANES spectra strongly suggest that in the p-type state As substitutionally replaces O in the ZnO lattice, thereby forming AsO, which is the acceptor responsible for p-type conduction in the As-doped, p-type ZnO.
ErAs
:
InGaAs
∕
InGaAlAs
superlattice thin-film power generator array
Authors: Zeng Gehong , Bowers John E. , Zide Joshua M. O. , Gossard Arthur C. , Kim Woochul , Singer Suzanne , Majumdar Arun , Singh Rajeev , Bian Zhixi , Zhang Yan , Shakouri Ali
Published: March 2006

We report a wafer scale approach for the fabrication of thin-film power generators composed of arrays of 400 p and n type ErAs:InGaAs∕InGaAlAs superlattice thermoelectric elements. The elements incorporate ErAs metallic nanoparticles into the semiconductor superlattice structure to provide charge carriers and create scattering centers for phonons. p- and n-type ErAs:InGaAs∕InGaAlAs superlattices with a total thickness of 5μm were grown on InP substrate using molecular beam epitaxy. The cross-plane Seebeck coefficients and cross-plane thermal conductivity of the superlattice were measured using test pattern devices and the 3ω method, respectively. Four hundred element power generators were fabricated from these 5μm thick, 200μm×200μm in area superlattice elements. The output power was over 0.7mW for an external resistor of 100Ω with a 30K temperature difference drop across the generator. We discuss the limitations to the generator performance and provide suggestions for improvements.
Field emission arrays for medical x-ray imaging
Authors: Schwoebel P. R.
Published: March 2006

Experiments demonstrate the feasibility of using microfabricated cold field emission cathodes in x-ray sources for medical imaging. Electron beam currents of 25mA at voltages of 25kV have been used to produce x-ray source focal spot diameters of 0.2mm. Analysis of both filtered and unfiltered x-ray spectra from molybdenum anodes show clear characteristic x-ray lines. These x-ray source characteristics are consistent with the requirements for human breast imaging.
Piezoelectric and piezooptic effects in porous silicon
Authors: Vinikman-Pinhasi Shirly , Ribak Erez N.
Published: March 2006

Although silicon is a simple cubic crystal, it can be induced to have a piezoelectric response, by making pores in it and thus spoiling its symmetry. By etching a silicon wafer into porous material, we found that it responds to voltage applied to it, as well as to light. A porous shallow layer on the surface of the wafer induced bimorph bending roughly proportional to the voltage squared. Illuminating the porous patch caused a similar bending.
Investigation of edge recombination effects in silicon solar cell structures using photoluminescence
Authors: Abbott M. D. , Cotter J. E. , Trupke T. , Bardos R. A.
Published: March 2006

Edge recombination can have a significant impact on the performance of small-area, high-efficiency silicon solar cells. Photoluminescence characterization techniques are applied to assess isolation trench techniques that are designed to remove edge recombination from such solar cells, thereby improving performance and allowing the true bulk properties of the solar cell to be evaluated independent of edge effects.
Phosphoinositide 3-kinase and Akt are essential for Sonic Hedgehog signaling
Authors: Riobó Natalia A. , Lu Ke , Ai Xingbin , Haines Gwendolyn M. , Emerson Charles P.
Published: March 2006

Hedgehogs (Hhs) are key signaling regulators of stem cell maintenance and tissue patterning in embryos, and activating mutations in the pathway that increase Gli transcriptional activity are causal in a diversity of cancers. Here, we report that phosphoinositide 3-kinase (PI3-kinase)-dependent Akt activation is essential for Sonic Hedgehog (Shh) signaling in the specification of neuronal fates in chicken neural explants, chondrogenic differentiation of 10T1/2 cells, and Gli activation in NIH 3T3 cells. Stimulation of PI3-kinase/Akt by insulin-like growth factor I potentiates Gli activation induced by low levels of Shh; however, insulin-like growth factor I alone is insufficient to induce Gli-dependent transcription. Protein kinase A (PKA) and glycogen synthase kinase 3β sequentially phosphorylate Gli2 at multiple sites, identified by mutagenesis, thus resulting in a reduction of its transcriptional activity. Gli2 mutant proteins in which the major PKA and glycogen synthase kinase 3β phosphorylation sites were mutated to alanine remain fully transcriptionally active; however, PKA-mutant Gli2 functions independently of Akt signaling, indicating that Akt positively regulates Shh signaling by controlling PKA-mediated Gli inactivation. Our findings provide a basis for the synergistic role of PI3-kinase/Akt in Hh signaling in embryonic development and Hh-dependent tumors.
Self-catalyzed site-specific depurination of guanine residues within gene sequences
Authors: Amosova Olga , Coulter Richard , Fresco Jacques R.
Published: March 2006

A self-catalyzed, site-specific guanine-depurination activity has been found to occur in short gene sequences with a potential to form a stem-loop structure. The critical features of that catalytic intermediate are a 5′-G-T-G-G-3′ loop and an adjacent 5′-T·A-3′ base pair of a short duplex stem stable enough to fix the loop structure required for depurination of its 5′-G residue. That residue is uniquely depurinated with a rate some 5 orders of magnitude faster than that of random “spontaneous” depurination. In contrast, all other purine residues in the sequence depurinate at the spontaneous background rate. The reaction requires no divalent cations or other cofactors and occurs under essentially physiological conditions. Such stem-loops can form in duplex DNA under superhelical stress, and their critical sequence features have been found at numerous sites in the human genome. Self-catalyzed stem-loop-mediated depurination leading to flexible apurinic sites may therefore serve some important biological role, e.g., in nucleosome positioning, genetic recombination, or chromosome superfolding.
Prevention of cytotoxic T lymphocyte responses to factor IX-expressing hepatocytes by gene transfer-induced regulatory T cells
Authors: Dobrzynski Eric , Fitzgerald Julie C. , Cao Ou , Mingozzi Federico , Wang Lixin , Herzog Roland W.
Published: March 2006

Treatment of genetic disease such as the bleeding disorder hemophilia B [deficiency in blood coagulation factor IX (F.IX)] by gene replacement therapy is hampered by the risk of immune responses to the therapeutic gene product and to the gene transfer vector. Immune competent mice of two different strains were tolerized to human F.IX by hepatic gene transfer mediated by adenoassociated viral vector. These animals were subsequently challenged by systemic administration of an E1/E3-deleted adenoviral vector, which is known to induce a cytotoxic T lymphocyte response to the transgene product. Immune tolerance prevented cytotoxic T lymphocyte activation to F.IX and CD8
+
cellular infiltrates in the liver. Moreover, a sustained and substantial increase in hepatic F.IX expression from the adenoviral vector was achieved despite
in vitro
T cell responses to adenoviral antigens. Cytolytic responses to therapeutic and to viral vector-derived antigens had been prevented
in vivo
by activation of regulatory CD4
+
T cells, which mediated suppression of inflammatory lymphocyte responses to the liver. This result suggests that augmentation of regulatory T cell activation should provide new means to avoid destructive immune responses in gene transfer.
Cross influences of ozone and sulfate precursor emissions changes on air quality and climate
Authors: Unger Nadine , Shindell Drew T. , Koch Dorothy M. , Streets David G.
Published: March 2006

Tropospheric O
3
and sulfate both contribute to air pollution and climate forcing. There is a growing realization that air quality and climate change issues are strongly connected. To date, the importance of the coupling between O
3
and sulfate has not been fully appreciated, and thus regulations treat each pollutant separately. We show that emissions of O
3
precursors can dramatically affect regional sulfate air quality and climate forcing. At 2030 in an A1B future, increased O
3
precursor emissions enhance surface sulfate over India and China by up to 20% because of increased levels of OH and gas-phase SO
2
oxidation rates and add up to 20% to the direct sulfate forcing for that region relative to the present day. Hence, O
3
precursors impose an indirect forcing via sulfate, which is more than twice the direct O
3
forcing itself (compare −0.61 vs. +0.35 W/m
2
). Regulatory policy should consider both air quality and climate and should address O
3
and sulfate simultaneously because of the strong interaction between these species.
Automated local bright feature image analysis of nuclear protein distribution identifies changes in tissue phenotype
Authors: Knowles David W. , Sudar Damir , Bator-Kelly Carol , Bissell Mina J. , Lelièvre Sophie A.
Published: March 2006

The organization of nuclear proteins is linked to cell and tissue phenotypes. When cells arrest proliferation, undergo apoptosis, or differentiate, distribution of nuclear proteins changes. Conversely, forced alteration of the distribution of nuclear proteins modifies cell phenotype. Immunostaining and fluorescence microscopy have been critical for such findings. However, there is increasing need for quantitative analysis of nuclear protein distribution to decipher epigenetic relationships between nuclear structure and cell phenotype and to unravel the mechanisms linking nuclear structure and function. We have developed imaging methods to quantify the distribution of fluorescently stained nuclear protein NuMA in different mammary phenotypes obtained using 3D cell culture. Automated image segmentation of DAPI-stained nuclei was generated to isolate thousands of nuclei from 3D confocal images. Prominent features of fluorescently stained NuMA were detected by using a previously undescribed local bright feature analysis technique, and their normalized spatial density was calculated as a function of the distance from the nuclear perimeter to its center. The results revealed marked changes in the distribution of the density of NuMA bright features when nonneoplastic cells underwent phenotypically normal acinar morphogenesis. Conversely, we did not detect any reorganization of NuMA during formation of tumor nodules by malignant cells. Importantly, the analysis also discriminated proliferating nonneoplastic from proliferating malignant cells, suggesting that these imaging methods are capable of identifying alterations linked not only to the proliferation status but also to the malignant character of cells. We believe that this quantitative analysis will have additional applications for classifying normal and pathological tissues.
Seeing the content of the mind: Enhanced awareness through working memory in patients with visual extinction
Authors: Soto David , Humphreys Glyn W.
Published: March 2006

In the present study, we demonstrate that parietal patients with visual extinction show enhanced awareness when there is a match between the current contents of their working memory and the stimuli presented in the visual field. This effect cannot be attributed to automatic bottom-up priming from the presentation of a memory cue, because extinction was reduced only when patients committed the cue to memory, and not when primes were viewed passively or merely identified. The results suggest that reentrant processes, from working memory, modulate awareness.
A role for chlorophyllide
a
oxygenase in the regulated import and stabilization of light-harvesting chlorophyll
a
/
b
proteins
Authors: Reinbothe Christiane , Bartsch Sandra , Eggink Laura L. , Hoober J. Kenneth , Brusslan Judy , Andrade-Paz Ricardo , Monnet Julie , Reinbothe Steffen
Published: March 2006

The
Arabidopsis CAO
gene encodes a 52-kDa protein with predicted localization in the plastid compartment. Here, we report that CAO is an intrinsic Rieske iron-sulfur protein of the plastid-envelope inner and thylakoid membranes. Activity measurements revealed that CAO catalyzes chlorophyllide
a
to chlorophyllide
b
conversion
in vitro
and that the enzyme was only slightly active with protochlorophyllide
a
, the nonreduced precursor of chlorophyllide
a
. Protein import and organelle fractionation studies identified CAO to be distinct from Ptc52 in the substrate-dependent transport pathway of NADPH:protochlorophyllide oxidoreductase A but instead to be part of a separate translocon complex. This complex was involved in the regulated import and stabilization of the chlorophyllide
b
-binding light-harvesting proteins Lhcb1 (LHCII) and Lhcb4 (CP29) in chloroplasts. Together, our results provide insights into the plastid subcompartmentalization and evolution of chlorophyll precursor biosynthesis in relation to protein import in higher plants.
Structural model for γ-aminobutyric acid receptor noncompetitive antagonist binding: Widely diverse structures fit the same site
Authors: Chen Ligong , Durkin Kathleen A. , Casida John E.
Published: March 2006

Several major insecticides, including α-endosulfan, lindane, and fipronil, and the botanical picrotoxinin are noncompetitive antagonists (NCAs) for the GABA receptor. We showed earlier that human β3homopentameric GABAAreceptor recognizes all of the important GABAergic insecticides and reproduces the high insecticide sensitivity and structure-activity relationships of the native insect receptor. Despite large structural diversity, the NCAs are proposed to fit a single binding site in the chloride channel lumen lined by five transmembrane 2 segments. This hypothesis is examined with the β3homopentamer by mutagenesis, pore structure studies, NCA binding, and molecular modeling. The 15 amino acids in the cytoplasmic half of the pore were mutated to cysteine, serine, or other residue for 22 mutants overall. Localization of A-1′C, A2′C, T6′C, and L9′C (index numbers for the transmembrane 2 region) in the channel lumen was established by disulfide cross-linking. Binding of two NCA radioligands [3H]1-(4-ethynylphenyl)-4-n-propyl-2,6,7-trioxabicyclo[2.2.2]octane and [3H] 3,3-bis-trifluoromethyl-bicyclo[2,2,1]heptane-2,2-dicarbonitrile was dramatically reduced with 8 of the 15 mutated positions, focusing attention on A2′, T6′, and L9′ as proposed binding sites, consistent with earlier mutagenesis studies. The cytoplasmic half of the β3 homopentamer pore was modeled as an α-helix. The six NCAs listed above plus t-butylbicyclophosphorothionate fit the 2′ to 9′ pore region forming hydrogen bonds with the T6′ hydroxyl and hydrophobic interactions with A2′, T6′, and L9′ alkyl substituents, thereby blocking the channel. Thus, widely diverse NCA structures fit the same GABA receptor β subunit site with important implications for insecticide cross-resistance and selective toxicity between insects and mammals.
p90 ribosomal S6 kinase 2 exerts a tonic brake on G protein-coupled receptor signaling
Authors: Sheffler Douglas J. , Kroeze Wesley K. , Garcia Bonnie G. , Deutch Ariel Y. , Hufeisen Sandra J. , Leahy Patrick , Brüning Jens C. , Roth Bryan L.
Published: March 2006

G protein-coupled receptors (GPCRs) are essential for normal central CNS function and represent the proximal site(s) of action for most neurotransmitters and many therapeutic drugs, including typical and atypical antipsychotic drugs. Similarly, protein kinases mediate many of the downstream actions for both ionotropic and metabotropic receptors. We report here that genetic deletion of p90 ribosomal S6 kinase 2 (RSK2) potentiates GPCR signaling. Initial studies of 5-hydroxytryptamine (5-HT)
2A
receptor signaling in fibroblasts obtained from RSK2 wild-type (+/+) and knockout (−/−) mice showed that 5-HT
2A
receptor-mediated phosphoinositide hydrolysis and both basal and 5-HT-stimulated extracellular signal-regulated kinase 1/2 phosphorylation are augmented in RSK2 knockout fibroblasts. Endogenous signaling by other GPCRs, including P2Y-purinergic, PAR-1-thrombinergic, β1-adrenergic, and bradykinin-B receptors, was also potentiated in RSK2-deficient fibroblasts. Importantly, reintroduction of RSK2 into RSK2−/− fibroblasts normalized signaling, thus demonstrating that RSK2 apparently modulates GPCR signaling by exerting a “tonic brake” on GPCR signal transduction. Our results imply the existence of a novel pathway regulating GPCR signaling, modulated by downstream members of the extracellular signal-related kinase/mitogen-activated protein kinase cascade. The loss of RSK2 activity in humans leads to Coffin–Lowry syndrome, which is manifested by mental retardation, growth deficits, skeletal deformations, and psychosis. Because RSK2-inactivating mutations in humans lead to Coffin–Lowry syndrome, our results imply that alterations in GPCR signaling may account for some of its clinical manifestations.
The
Phycomyces madA
gene encodes a blue-light photoreceptor for phototropism and other light responses
Authors: Idnurm Alexander , Rodríguez-Romero Julio , Corrochano Luis M. , Sanz Catalina , Iturriaga Enrique A. , Eslava Arturo P. , Heitman Joseph
Published: March 2006

Phycomyces blakesleeanus
is a filamentous zygomycete fungus that produces striking elongated single cells that extend up to 10 cm into the air, with each such sporangiophore supporting a sphere containing the spores for dispersal. This organism has served as a model for the detection of environmental signals as diverse as light, chemicals, touch, wind, gravity, and adjacent objects. In particular, sporangiophore growth is regulated by light, and it exhibits phototropism by bending toward near-UV and blue wavelengths and away from far-UV wavelengths in a manner that is physiologically similar to plant phototropic responses. The
Phycomyces madA
mutants were first isolated more than 40 years ago, and they exhibit reduced sensitivity to light. Here, we identify two (duplicated) homologs in the White Collar 1 family of blue-light photoreceptors in
Phycomyces
. We describe that the
madA
mutant strains contain point mutations in one of these genes and that these mutations cosegregate with a defect in phototropism after genetic crosses. Thus, the phototropic responses of fungi through
madA
and plants through phototropin rely on diverse proteins; however, these proteins share a conserved flavin-binding domain for photon detection.
A Case Report of a Spontaneous Gastrointestinal Stromal Tumor (GIST) Occurring in a F344 Rat
Authors: Fujimoto Hitoshi , Shibutani Makoto , Kuroiwa Keiko , Inoue Kaoru , Woo Gye-Hyeong , U Mami , Hirose Masao
Published: March 2006

We report a case of gastrointestinal stromal tumor (GIST) that developed in a male F344 rat at week 101 of an experiment in a carcinogenicity study. Macroscopically, the primary tumor, which measured 1 cm in diameter, involved the submucosal tissue of the forestomach at the lesser curvature extending to the glandular stomach and esophagus. Histopathologically, the tumor was composed of neoplastic cells with small- to medium-sized spindle-shaped single nuclei and fibrillary cytoplasm lacking distinct cell borders. It invaded extensively into the tunica muscularis and subserosa, further extending to the lamina propria mucosa and serosal surface. A few densely proliferating portions showed a tendency to storiform pattern. Metastatic tumor nodules were found in the liver, spleen, and femur bone marrow, with multiple nodules, up to 1 cm in diameter, apparent in the liver. Immunohistochemically, diffuse, but weak cytoplasmic immunoreactivity for KIT was evident, and most neoplastic cells also exhibited strong immunoreactivity for α-smooth muscle actin and vimentin. Sparse nuclear S-100-immunoreactive cells were further observed, but none of neoplastic cells were immunoreactive for CD34, caldesmon, desmin, cytokeratin, or synaptophysin. Collectively, these features meet the criteria for a GIST, with limited potential for differentiation to smooth muscle and neural cells.
A 26-Week Carcinogenicity Study of 2-Amino-3-Methylimidazo[4,5-f]Quinoline in rasH2 Mice
Authors: Okamura Miwa , Moto Mitsuyoshi , Muguruma Masako , Ito Tadashi , Jin Meilan , Kashida Yoko , Mitsumori Kunitoshi
Published: March 2006

To evaluate the carcinogenic susceptibility of rasH2 mice to 2-amino-3-methylimidazo[4,5- f ]quinoline (IQ), 7-week-old rasH2 mice and their wild-type littermates (non-Tg mice) of both the sexes were fed a diet containing 0 or 300 ppm IQ for 26 weeks. Microscopical examinations revealed that the proliferative lesions of the forestomach, including squamous cell hyperplasias, papillomas, and carcinomas, were frequently encountered in male and female rasH2 mice fed with IQ. In non-Tg mice, no significant differences in the incidence of forestomach lesions were observed between the 0 ppm and 300 ppm groups. Histopathological changes such as periportal hepatocellular hypertrophy and oval cell proliferation in the liver were more apparent in female rasH2 and non-Tg mice than in males, and the incidence of hepatocellular altered foci significantly increased in female rasH2 mice in the 300 ppm group as compared to that in the 0 ppm group. These results suggest that the carcinogenic potential of IQ can be detected in rasH2 mice by a 26-week, short-term carcinogenicity test.
A New Map of Censorship
Authors: Dworkin Ronald
Published: March 2006

THE OLD ORDER CHANGES, YIELDING PLACE TO NEW, AND FREEDOM FINDS ITSELF IN DISARRAY, UNDER ATTACK FROM NEW ENEMIES AMONG ITS OLD CHAMPIONS
Words That Kill
Authors: Nicolae Valeriu
Published: March 2006

‘GYPSIES ARE THE ONLY GROUP ABOUT WHICH ANYTHING CAN BE SAID WITHOUT CHALLENGE OR DEMURRAL.’ EDWARD SAID
Where the Lines Are Drawn
Authors: Freedland Jonathan
Published: March 2006

WHEN IT COMES TO ANTISEMITISM, IT’S NOT SO MUCH WHAT YOU SAY, BUT WHAT YOU INTEND
Beyond Tolerance and the Intolerable
Authors: Malik Kenan
Published: March 2006

THE SPEECH THAT OFFENDS MAY CREATE POLITICAL AND SOCIAL PROBLEMS BUT SHOULD NOT BE THE EXCUSE FOR LEGISLATION RESTRICTING FREE EXPRESSION
Regulation, Responsibility and the Case Against Censorship
Authors: Sambrook Richard
Published: March 2006

THE PRICE OF FREE SPEECH IS THE CONTINUAL OBSERVANCE AND QUESTIONING OF THE MEDIA’ S ACTIONS, BY EDITORS, REGULATORS AND AUDIENCES, SAYS THE BBC’S HEAD OF NEWS
Put Your Own House in Order First
Authors: Koven Ronald
Published: March 2006

WHY SHOULD THE MEDIA BE COERCED INTO BEHAVING ‘RESPONSIBLY’ BY GOVERNMENTS NOTORIOUS FOR THEIR OWN IRRESPONSIBILITY?
No Peace No Justice
Authors: Badcock James
Published: March 2006

‘SMALL’ IS SOMETHING OF A MISNOMER FOR A CIVIL WAR THAT HAS TAKEN 150,000 LIVES AND LEFT ALGERIA A DEEPLY DIVIDED COUNTRY
Back Where We Started
Authors: Forna Aminatta
Published: March 2006

UK-BASED WRITER AMINATTA FORNA DESCRIBES LIFE IN POST-WAR SIERRA LEONE THROUGH THE EYES OF HER COUSIN MORLAI
War On the Roof of the World
Authors: Hilton Isabel
Published: March 2006

THE MAOISTS CANNOT TAKE THE CITIES AND THE ARMY CANNOT RECONQUER THE COUNTRYSIDE. TIME TO NEGOTIATE
Election Diary: Taking the Pulse
Authors: Gunesekera Romesh
Published: March 2006

LAST YEAR’S PRESIDENTIAL ELECTION WAS A WATERSHED FOR SRI LANKA BUT DESPITE THE CAMPAIGNING, THE ONLY ISSUE THAT MATTERED TO THE ELECTORATE WAS ENDING THE WAR
Into the Quick of Life
Authors: Hatzfeld Jean
Published: March 2006

SYLVIE UMUBYEYI, A SURVIVOR OF THE RWANDAN GENOCIDE AND NOW THE OWNER OF A RESTAURANT IN NYAMATA WHERE 50,000 TUTSI WERE MURDERED IN ONE MONTH, TELLS HER STORY
The Orange Revolution Loses Its Zest
Authors: Foley Michael
Published: March 2006

ONE YEAR ON, UKRAINIANS HAVE LOST FAITH IN THEIR NEW GOVERNMENT AND THE MEDIA IS ALL AT SEA IN THE RUN UP TO MARCH ELECTIONS
The Archipelago of Gulags
Authors: Smith Clive Stafford
Published: March 2006

IT’S NOT ONLY IN GUANTANAMO THAT PRISONERS ARE ILLEGALLY DETAINED. THERE’S A WHOLE STRING OF TORTURE CHAMBERS AROUND THE WORLD TO WHICH THE US IS SENDING ITS SUSPECTED TERRORISTS
The Irresistible Rise of Democracy
Authors: Andersen Michael
Published: March 2006

THE US ADMINISTRATION PUBLICLY STRESSES ITS SUPPORT FOR DEMOCRACY BUT FOUR YEARS INTO THE ‘WAR AGAINST TERROR’ AND NUMEROUS ELECTIONS ON, CENTRAL ASIA NO LONGER BELIEVES THE RHETORIC
Staying On in El Salvador
Authors: Danner Mark
Published: March 2006

TIMES CHANGE, THE SEARCHLIGHT MOVES ON TO ILLUMINATE THE NEXT CRISIS, BUT THERE ARE SOME, LIKE THE PHOTOGRAPHER LARRY TOWELL, WHO STAY ON, TO TELL THE STORY NO ONE WANTS TO HEAR ANY LONGER. MARK DANNER TELLS THE STORY BEHIND THE PICTURES
Animal models of drug addiction: Where do we go from here?
Authors: Olmstead Mary C.
Published: March 2006

Compulsion and impulsivity are both primary features of drug addiction. Based on decades of animal research, we have a detailed understanding of the factors (both environmental and physiological) that influence compulsive drug use, but still know relatively little about the impulsive aspects of drug addiction. This review outlines our current knowledge of the relationship between impulsivity and drug addiction, focusing on cognitive and motor impulsivity, which are particularly relevant to this disorder. Topics to be discussed include the influence of chronic drug administration on impulsivity, the mechanisms that may explain drug-induced impulsivity, and the role of individual differences in the development of impulsive drug use. In addition, the manner in which contemporary theories of drug addiction conceptualize the relationship between impulsivity and compulsion is examined. Most importantly, this review emphasizes a critical role for animal research in understanding the role of impulsivity in the development and maintenance of drug addiction.
Separase: a universal trigger for sister chromatid disjunction but not chromosome cycle progression
Authors: Wirth Karin G. , Wutz Gordana , Kudo Nobuaki R. , Desdouets Chantal , Zetterberg Anders , Taghybeeglu Shahryar , Seznec Janina , Ducos Germain M. , Ricci Romeo , Firnberg Nicole , Peters Jan-Michael , Nasmyth Kim
Published: March 2006

Separase is a protease whose liberation from its inhibitory chaperone Securin triggers sister chromatid disjunction at anaphase onset in yeast by cleaving cohesin's kleisin subunit. We have created conditional knockout alleles of the mouse Separase and Securin genes. Deletion of both copies of Separase but not Securin causes embryonic lethality. Loss of Securin reduces Separase activity because deletion of just one copy of the Separase gene is lethal to embryos lacking Securin. In embryonic fibroblasts, Separase depletion blocks sister chromatid separation but does not prevent other aspects of mitosis, cytokinesis, or chromosome replication. Thus, fibroblasts lacking Separase become highly polyploid. Hepatocytes stimulated to proliferate in vivo by hepatectomy also become unusually large and polyploid in the absence of Separase but are able to regenerate functional livers. Separase depletion in bone marrow causes aplasia and the presumed death of hematopoietic cells other than erythrocytes. Destruction of sister chromatid cohesion by Separase may be a universal feature of mitosis in eukaryotic cells.
ERK1c regulates Golgi fragmentation during mitosis
Authors: Shaul Yoav D. , Seger Rony
Published: March 2006

Extracellular signal-regulated kinase 1c (ERK1c) is an alternatively spliced form of ERK1 that is regulated differently than other ERK isoforms. We studied the Golgi functions of ERK1c and found that it plays a role in MEK-induced mitotic Golgi fragmentation. Thus, in late G2 and mitosis of synchronized cells, the expression and activity of ERK1c was increased and it colocalized mainly with Golgi markers. Small interfering RNA of ERK1c significantly attenuated, whereas ERK1c overexpression facilitated, mitotic Golgi fragmentation. These effects were also reflected in mitotic progression, indicating that ERK1c is involved in cell cycle regulation via modulation of Golgi fragmentation. Although ERK1 was activated in mitosis as well, it could not replace ERK1c in regulating Golgi fragmentation. Therefore, MEKs regulate mitosis via all three ERK isoforms, where ERK1c acts specifically in the Golgi, whereas ERK1 and 2 regulate other mitosis-related processes. Thus, ERK1c extends the specificity of the Ras-MEK cascade by activating ERK1/2-independent processes.
The Drosophila melanogaster Cajal body
Authors: Liu Ji-Long , Murphy Christine , Buszczak Michael , Clatterbuck Sarah , Goodman Robyn , Gall Joseph G.
Published: March 2006

Cajal bodies (CBs) are nuclear organelles that are usually identified by the marker protein p80-coilin. Because no orthologue of coilin is known in Drosophila melanogaster, we identified D. melanogaster CBs using probes for other components that are relatively diagnostic for CBs in vertebrate cells. U85 small CB–specific RNA, U2 small nuclear RNA, the survival of motor neurons protein, and fibrillarin occur together in a nuclear body that is closely associated with the nucleolus. Based on its similarity to CBs in other organisms, we refer to this structure as the D. melanogaster CB. Surprisingly, the D. melanogaster U7 small nuclear RNP resides in a separate nuclear body, which we call the histone locus body (HLB). The HLB is invariably colocalized with the histone gene locus. Thus, canonical CB components are distributed into at least two nuclear bodies in D. melanogaster. The identification of these nuclear bodies now permits a broad range of questions to be asked about CB structure and function in a genetically tractable organism.
The selective continued linkage of centromeres from mitosis to interphase in the absence of mammalian separase
Authors: Kumada Kazuki , Yao Ryoji , Kawaguchi Tokuichi , Karasawa Mika , Hoshikawa Yutaka , Ichikawa Koji , Sugitani Yoshinobu , Imoto Issei , Inazawa Johji , Sugawara Minoru , Yanagida Mitsuhiro , Noda Tetsuo
Published: March 2006

Separase is an evolutionarily conserved protease that is essential for chromosome segregation and cleaves cohesin Scc1/Rad21, which joins the sister chromatids together. Although mammalian separase also functions in chromosome segregation, our understanding of this process in mammals is still incomplete. We generated separase knockout mice, reporting an essential function for mammalian separase. Separase-deficient mouse embryonic fibroblasts exhibited severely restrained increases in cell number, polyploid chromosomes, and amplified centrosomes. Chromosome spreads demonstrated that multiple chromosomes connected to a centromeric region. Live observation demonstrated that the chromosomes of separase-deficient cells condensed, but failed to segregate, although subsequent cytokinesis and chromosome decondensation proceeded normally. These results establish that mammalian separase is essential for the separation of centromeres, but not of the arm regions of chromosomes. Other cell cycle events, such as mitotic exit, DNA replication, and centrosome duplication appear to occur normally. We also demonstrated that heterozygous separase-deficient cells exhibited severely restrained increases in cell number with apparently normal mitosis in the absence of securin, which is an inhibitory partner of separase.
Skeletons in the p53 tumor suppressor closet: genetic evidence that p53 blocks bone differentiation and development
Authors: Zambetti Gerard P. , Horwitz Edwin M. , Schipani Ernestina
Published: March 2006

A series of in vitro tissue culture studies indicated that the p53 tumor suppressor promotes cellular differentiation, which could explain its role in preventing cancer. Quite surprisingly, however, two new in vivo studies (Lengner et al., 2006; Wang et al., 2006) provide genetic evidence that p53 blocks osteoblast differentiation and bone development. These interesting results and their biological and clinical implications are the focus of this comment.
Myelin under construction—teamwork required
Authors: Boiko Tatiana , Winckler Bettina
Published: March 2006

Myelinating glial cells synthesize specialized myelin proteins and deposit them in the growing myelin sheath that enwraps axons multiple times. How do axons and myelinating glial cells coordinate this spectacular cell–cell interaction? In this issue, Trajkovic et al. (p. 937) show that neuronal signaling regulates cell surface expression of the myelin proteolipid protein in cultured oligodendrocytes in unexpected ways that may also contribute to myelination in situ.
An Outbreak of Community-Onset Methicillin-ResistantStaphylococcus aureusSkin Infections in Southwestern Alaska
Authors: Baggett Henry C. , Hennessy Thomas W. , Leman Richard , Hamlin Cindy , Bruden Dana , Reasonover Alisa , Martinez Patricia , Butler Jay C.
Published: March 2006

Objective:

We investigated a large outbreak of community-onset methicillin-resistantStaphylococcus aureus(MRSA) infections in southwestern Alaska to determine the extent of these infections and whether MRSA isolates were likely community acquired.

Design:

Retrospective cohort study.

Setting:

Rural southwestern Alaska.

Patients:

All patients with a history of culture-confirmed S.aureusinfection from March 1, 1999, through August 10, 2000.

Results:

More than 80% of culture-confirmed S.aureusinfections were methicillin resistant, and 84% of MRSA infections involved skin or soft tissue; invasive disease was rare. Most (77%) of the patients with MRSA skin infections had communityacquired MRSA (no hospitalization, surgery, dialysis, indwelling line or catheter, or admission to a long-term-care facility in the 12 months before infection). Patients with MRSA skin infections were more likely to have received a prescription for an antimicrobial agent in the 180 days before infection than were patients with methicillin-susceptible S.aureusskin infections.

Conclusions:

Our findings indicate that the epidemiology of MRSA in rural southwestern Alaska has changed and suggest that the emergence of community-onset MRSA in this region was not related to spread of a hospital organism. Treatment guidelines were developed recommending that beta-lactam antimicrobial agents not be used as a first-line therapy for suspectedS. aureusinfections.
Antimicrobial Resistance in Staphylococcus aureus at the University of Chicago Hospitals: A 15-Year Longitudinal Assessment in a Large University-Based Hospital
Authors: Seal John B. , Moreira Beatriz , Bethel Cindy D. , Daum Robert S.
Published: March 2006

Objectives:

To describe a longitudinal profile of resistance to beta-lactam antimicrobials among isolates of Staphylococcus aureus at a large university teaching hospital and to evaluate the impact of the methicillin resistance phenotype on resistance trends for non-beta-lactam antimicrobials.

Design:

Retrospective evaluation of antimicrobial susceptibility data for all 17,287 S. aureus isolates obtained from January 1986 through December 2000.

Setting:

The University of Chicago Hospitals, a family of tertiary-care, university-affiliated hospitals in Chicago, Illinois, consisting of 547 adult and pediatric beds.

Results:

The annual rate of resistance to methicillin increased from 13% in 1986 to 28% in 2000 (P < .001) and has not plateaued. For each non-beta-lactam antimicrobial tested, the annual rates of resistance were far higher among methicillinresistant S. aureus (MRSA) isolates than among methicillin-susceptible S. aureus (MSSA) isolates. The annual rates of resistance to the macrolide, lincosamide, and streptogramin (MLS) antimicrobials erythromycin and clindamycin increased among MSSA isolates (P < .01), but remained lower than 20%. Resistance to the MLS antimicrobials was higher among MRSA isolates (higher than 60%), but the annual rate decreased significantly during the study (P < .01).

Conclusion:

The prevalence of methicillin resistance among S. aureus isolates has continued to increase; resistance to non-beta-lactam antimicrobials is far more common among MRSA isolates. Recent decreases in the proportion of MRSA isolates resistant to non-beta-lactam antimicrobials suggest important changes in the epidemiology of this pathogen.
Prevalence of and Risk Factors for Colonization With Methicillin-ResistantStaphylococcus aureusin an Outpatient Clinic Population
Authors: Jernigan John A. , Pullen Amy L. , Partin Clyde , Jarvis William R.
Published: March 2006

Objecttves:

To determine the prevalence of methicillin-resistantStaphylococcus aureus(MRSA) colonization in an outpatient population and to identify risk factors for MRSA colonization.

Design:

Surveillance cultures were performed during outpatient visits to identify S.aureuscolonization. A case-control study was performed to identify risk factors for MRSA colonization.

Setting:

Primary care internal medicine clinic. PATTENTS: Adults presenting for non-acute primary care (N = 494).

Results:

S.aureuswas isolated from 122 (24.7%) of the patients for whom cultures were performed. Methicillin-susceptible S.aureuswas isolated from 107 (21.7%) of the patients, whereas MRSA was isolated from 15 (3.0%) of the patients. All MRSA isolates were resistant to multiple non-beta-lactam antimicrobial agents. In multivariate analyses, MRSA colonization was independently associated with admission to a nursing home (adjusted odds ratio [OR], 103; 95% confidence interval [CI95], 7 to 999) or hospital in the previous year, although the association with hospital admission was observed only among those without chronic illness (adjusted OR 7.1; CI95, 1.3 to 38.1). In addition, MRSA colonization was associated with the presence of at least one underlying chronic illness, although this association was observed only among those who had not been hospitalized in the previous year (adjusted OR, 5.1; CI95, 1.2 to 21.9).

Conclusions:

We found a low prevalence of MRSA colonization in an adult outpatient population. MRSA carriers most likely acquired the organism through contact with healthcare facilities rather than in the community. These data show that care must be taken when attributing MRSA colonization to the community if detected in outpatients or during the first 24 to 48 hours of hospitalization.
Nosocomial Transmission of Methicillin-Resistant Staphylococcus aureus: A Blinded Study to Establish Baseline Acquisition Rates
Authors: Fishbain Joel T. , Lee Joseph C. , Nguyen Honghung D. , Mikita Jeffery A. , Mikita Cecilia P. , Uyehara Catherine F. T. , Hospenthal Duane R.
Published: March 2006

Objective:

To define the extent of nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to a tertiary-care hospital.

Design:

A blinded, prospective surveillance culture study of patients admitted to the hospital to determine the transmission (acquisition) rate of MRSA Risk factors associated with the likelihood of MRSA colonization on admission were investigated.

Setting:

Tertiary-care military medical facility.

Participants:

All patients admitted to the medicine, surgery, and pediatric wards, and to the medical, surgical, and pediatric intensive care units were eligible for inclusion.

Results:

Five hundred thirty-five admission and 374 discharge samples were collected during the study period. One hundred forty-one patients were colonized with methicillin-susceptible S. aureus (MSSA) and 20 patients (3.7%) were colonized with MRSA on admission. Of the 354 susceptible patients, 6 acquired MRSA during the study for a transmission rate of 1.7%. Patients colonized with MRSA on admission were more likely to be older than non-colonized or MSSA-colonized patients, to have received antibiotics within the past year, to have been hospitalized within the prior 3 years, or to have a known history of MRSA. Patients acquiring MRSA had an average hospital stay of 17.7 days compared with 5.3 days for those who did not acquire MRSA. Pulsed-field gel electrophoresis of the 6 MRSA isolates from patients who acquired MRSA revealed 4 distinct band patterns.

Conclusions:

Most patients colonized with MRSA were identified on admission samples. Surveillance cultures of patients admitted may help to prevent MRSA transmission and infection.