bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced electrical properties of ferroelectric thin films by ultraviolet radiation
Authors: Alford Neil McN. , Petrov Peter Kr. , Gagarin Aleksandr G. , Kozyrev Andrey B. , Sokolov Aleksandr I. , Soldatenkov Oleg I. , Volpyas Valery A.
Published: November 2005

Ferroelectric films in the paraelectric phase exhibit two undesirable properties: hysteresis in the voltage-capacitance characteristics and a significant relaxation time of the capacitance. Our experiments show that suppression of both of these is achieved by using UV radiation with wavelengths corresponding to the material forbidden gap. Experimentally we also observed UV radiation induced modulation of thin film permittivity without an applied electric field. The observed phenomena are believed to have the same origin: UV light generates nonequilibrium charge carriers that screen out local electric field induced by defects and interfaces inside ferroelectric thin films and change films effective dielectric properties.
Room-temperature epitaxial growth of GaN on lattice-matched ZrB2 substrates by pulsed-laser deposition
Authors: Kawaguchi Y. , Ohta J. , Kobayashi A. , Fujioka H.
Published: November 2005

We have grown GaN films on ZrB2 substrates at room temperature (RT) by using a pulsed-laser deposition technique. Reflection high-energy electron diffraction observations have revealed that GaN growth can occur in a layer-by-layer mode, even at RT, and that the surfaces of the films are atomically flat. We found that intermixing reactions at the GaN∕ZrB2 heterointerfaces, which have been the most serious problem for this structure until now, are well suppressed in the case of RT growth. Electron backscattered diffraction measurements have revealed that the tilt angle and the twist angle of the RT GaN are 0.23° and 0.24°, respectively, even for film thicknesses as low as 20 nm. The fact that RT GaN exhibits quite high crystallinity from the early stages of film growth can be attributed to the small lattice mismatch of this system.
Angle-resolved transmission spectroscopy of three-dimensional photonic crystals fabricated by direct laser writing
Authors: Deubel M. , Wegener M. , Linden S. , von Freymann G.
Published: November 2005

Oblique incidence optical transmission spectra of three-dimensional photonic crystal templates, i.e., woodpile structures, are presented. They are compared with transmission spectra calculated using a scattering-matrix approach. In addition, band-structure calculations are presented. The comparison reveals intricate details of the three-dimensional photonic band structure demonstrating the high overall sample quality.
Deep levels in n-type AlGaN grown by hydride vapor-phase epitaxy on sapphire characterized by deep-level transient spectroscopy
Authors: Osaka J. , Ohno Y. , Kishimoto S. , Maezawa K. , Mizutani T.
Published: November 2005

Deep levels in unintentionally doped n-type Al0.09Ga0.91N and Al0.17Ga0.83N films grown on sapphire by hydride vapor-phase epitaxy were characterized using capacitance deep-level transient spectroscopy and were compared to the reported electron traps in GaN grown by various techniques. It was shown that at least three dominant deep levels exist in each sample. The Al mole fraction dependence of their activation energy suggested that each of these three levels has the same origin as the three dominant well known point-defect-related deep levels in GaN, respectively. It is thought that deep levels in GaN change their electric characteristics in low Al content AlGaN.
Formation of p-n homojunctions in n-ZnO bulk single crystals by diffusion from a Zn3P2 source
Authors: Jang Soohwan , Chen Jau-Jiun , Kang B. S. , Ren F. , Norton D. P. , Pearton S. J. , Lopata J. , Hobson W. S.
Published: November 2005

p - n junctions have been formed in lightly n-type (1017cm−3) bulk, single-crystal ZnO substrates by diffusion of P from a Cd3P2, arsenic and red phosphorous dopant source in a closed-ampoule system. The P incorporation depth was found to be ∼200nm after diffusion at 550°C for 30min, as determined by secondary ion mass spectrometry profiling. The resulting structures show rectification, with on-off current ratios of ∼70 at +3∕−5V. The forward current ideality factor was ⩾2, consistent with multiple current transport mechanisms present in the junction, such as defect-assisted tunneling and conventional carrier recombination in the space-charge region via midgap deep levels. The forward turn-on voltage, VF was ∼4V at 300K with a specific on-state resistance (RON) of ∼21mΩcm2. The activation energy of the forward current at low forward biases was ∼1.4eV. This is also consistent with carrier recombination in the space charge region via a midgap deep level.
Nanoscale hysteresis loop of individual Co dots by field-dependent magnetic force microscopy
Authors: Rastei M. V. , Meckenstock R. , Bucher J. P.
Published: November 2005

We present an approach in which field-dependent magnetic force microscopy (MFM) is used in order to determine the magnetic properties of individual magnetic nanodots. In this work, the integral value of the cantilever phase shift obtained in vibrating MFM experiment is used as a measure of the field dependent magnetization of single objects. The method accounts for details that are resolved at the 10 nm scale, including fine structures during magnetization reversal. Measurements have been done on a model system of embedded dots since the flatness of the free surface reduces strongly the topographic contaminations. It is shown that the method can easily be applied to investigate both out-of-plane and in-plane magnetized dots.
Self-assembled growth and green emission of gold nanowhiskers
Authors: Qiu T. , Wu X. L. , Siu G. G. , Chu Paul K.
Published: November 2005

Unique structured Au nanowhiskers were fabricated via electroless metal deposition on Si wafer in KAuCl4–HF solution. A self-assembled localized microscopic electrochemical cell model and a diffusion-limited aggregation process are associated with the formation of Au nanowhiskers. A green photoluminescence (PL) band was recorded. Spectral analyses suggest the green PL arises from the radiative recombination of sp-band electrons with d-band holes in the Au nanowhiskers and its intensity enhancement is due to local electric field connected with the Au particle plasmons oscillation. A red PL band was also observed from long-time etched Si substrates and proposed to be related to Si nanocrystals in the surface layer of etched Si wafer. Its stability was considered to be owing to the formation of stable Si–Au bonds on the surfaces of Si nanocrystals.
80
-
micron
interaction length silicon photonic crystal waveguide modulator
Authors: Jiang Yongqiang , Jiang Wei , Gu Lanlan , Chen Xiaonan , Chen Ray T.
Published: November 2005

An ultracompact silicon electro-optic modulator was experimentally demonstrated based on silicon photonic crystal (PhC) waveguides for the first time to our knowledge. Modulation operation was demonstrated by carrier injection into an 80μm-long silicon PhC waveguide of a Mach-Zehnder interferometer (MZI) structure. The π phase shift driving current, Iπ, across the active region is as low as 0.15mA, which is equivalent to a Vπ of 7.5mV when a 50Ω impedance-matched structure is applied. The modulation depth is 92% operating at 1567nm.
Direct photofabrication of refractive-index-modulated multimode optical waveguide using photosensitive sol-gel hybrid materials
Authors: Kang Dong Jun , Kim Woo-Soo , Bae Byeong-Soo , Park Hyun Kyu , Jung Bong Hyun
Published: November 2005

Photosensitive sol-gel hybrid materials (hybrimers) exhibited a thick film property, an efficient refractive index tunability through the control of their compositions, and a high photosensitivity upon UV exposure. The materials were used for the direct photofabrication of the multimode optical waveguide (MOW) with a large core structure. Due to the outstanding optical properties of these materials, problems and complexities associated with the fabrication of MOW could be overcome, and a MOW with good propagation performance could be easily fabricated. Importantly, a propagation loss of as low as 0.13dBcm−1 at 850nm could be obtained.
Establishment of native and exotic grasses on mine overburden and topsoil in the Hunter Valley, New South Wales
Authors: Huxtable C. H. A. , Koen T. B. , Waterhouse D.
Published: November 2005

Native grasses have an important role to play in mine rehabilitation throughout Australia, but there have been few scientifically designed studies of field establishment of native grasses from sown seed in this country. Current recommendations for rehabilitation of open-cut coal mines in the Hunter Valley involve the sowing of exotic pasture species to reinstate mined land to Class IV and V under the Rural Land Capability System. Despite the importance of native grasses in the pre-mined landscape, they are currently not widely included in mine rehabilitation. To address this issue a project was conducted between 1994 and 2000 to research the use of native grasses for rehabilitation of open-cut coal mines in the Hunter Valley. This paper reports on 2 mine site experiments that aimed to assess establishment and persistence of a broad range of native and exotic grass species from an autumn sowing in both topsoil and raw spoil over a period of 61 months. The most promising natives in terms of early establishment, persistence and spread over time, included six C3 accessions (five Austrodanthonia spp. and Austrostipa bigeniculata) and one C4 accession (Cynodon dactylon). Persistence of these accessions was better in raw spoil than topsoil, despite initial low numbers, due to a lack of weed competition and their ability to spread by self-seeding. In topsoil, and in the absence of any biomass reduction, native species were mostly out-competed by vigorous exotic perennial grasses which were sown in these experiments and from seed influx from adjacent rehabilitation areas or from the soil seed bank. The effects of climatic conditions and differences in soil physical, chemical and seed bank characteristics at the 2 mine sites are also discussed.
The role of the male flower spike as a cue for selective grazing in bladder saltbush
Authors: Walsh D. , Sinclair R. , Andrew M. H. , Coleman D.
Published: November 2005

This paper reports the results of three cafeteria trials used to study palatability variation between the sex phenotypes of bladder saltbush (Atriplex vesicaria Heward ex Benth.). The results of the first trial show that Merino sheep preferentially grazed female samples compared to male ones, which supported earlier paddock-scale grazing trials and observations. In the second trial, the removal of male flower spikes led to increased consumption of male samples, suggesting that male flower spikes contain a grazing deterrent. The third trial showed that sheep were able to detect male material with or without spikes even when it was completely hidden within female plant material. In combination with observations made during the trials, these results suggest that there is a grazing deterrent present in male plants and that sheep use the male flower spike primarily as a visual cue when making grazing decisions.
Reproductive and vegetative responses of different accessions of Microlaena stipoides (Labill.) R.Br. to nitrogen applications and supplementary irrigation in southern Australia
Authors: Chivers I. H. , Aldous D. E.
Published: November 2005

Native grasses such as Microlaena stipoides (Labill.) R.Br. have the potential to play an important role in pastures, revegetation and as turfgrasses, but their use to date has been limited by seed supply. The purpose of this study was to investigate, (i) the effect of nitrogen fertilisation on M. stipoides seed production, (ii) the effect of irrigation on seed production, and (iii) the variation among accessions in response to these 2 factors.
Microlaena stipoides accessions responded to added nitrogen with an increase in shoot growth, total amount of dry matter produced per plant and in reproductive characters at the end of the harvest season. Higher yields were recorded for high (split) nitrogen treatments in comparison to nil (control) or low nitrogen treatments, with added nitrogen extending seed production. Higher soil moisture regimes produced significantly more reproductive culms, more spikelets per culm, and more seeds per plant when compared to low soil moisture treatments. The frequency of irrigation had more effect on seed yield than the amount of water applied.
Microlaena stipoides appears to have a 2–step mechanism for regulating the yield of its summer inflorescences namely; the plant initially responds to a high frequency of rainfall or irrigation events by initiating culms. Numbers of culms and florets per culm that reach maturity are dependent on the volume of water applied. Such a mechanism would assist in the adaptation of this grass to a southern Australian climate, which often exhibits an erratic summer rainfall.
While there were differences among the accessions for both reproductive and vegetative characters, they gave a uniform response to the different nitrogen treatments. The responses of 3 accessions to different irrigation treatments were somewhat different but with respect to total number of spikelets produced per plant, they all responded in the same way. Different irrigation management schedules may be required for different cultivars for commercial seed production.
Numerical and functional response of feral cats (Felis catus) to variations in abundance of primary prey on Stewart Island (Rakiura), New Zealand
Authors: Harper Grant A.
Published: November 2005

Few studies of populations of feral cats have simultaneously monitored the seasonal abundance of primary prey and the possible ‘prey-switch’ to alternative prey when primary prey abundance declines. On Stewart Island, when the abundance of feral cats’ primary prey, rats (Rattus spp.), was very low, significantly more cats died or left the study area than when rats were abundant. Cats preferentially preyed on rats regardless of rat abundance. Birds were the main alternative prey but cats did not prey-switch to birds when rat abundance was low, possibly owing to the difficulty of capture, and small mass, of birds compared with rats. On Stewart Island numbers of feral cats are restricted by seasonal depressions in abundance of their primary prey, coupled with limited alternative prey biomass.
Are oestrous feral pigs, Sus scrofa, useful as trapping lures?
Authors: McIlroy J. C. , Gifford E. J.
Published: November 2005

Eight feral pigs (two boars, four sows and two piglets) were caught in traps using oestrous sows as lures during a control program on a remnant pig population in part of Namadgi National Park during spring, 1990. The program was mostly based on aerial baiting with warfarin. No pigs were caught in traps containing anoestrous sows or in traps containing bait only. Seven unmarked pigs (caught seven days after the cessation of baiting) did not appear to have eaten any warfarin bait. In an earlier pilot trial, two boars were caught at a trap containing an oestrous sow, one of these again in a trap baited only with fermented grain, but no pigs were caught at a trap containing an anoestrous sow. Although not cost-effective as a general technique, this method could be useful in specific circumstances, such as eradication campaigns on islands, if the last few pigs are, or have become bait shy, or are impossible to cull by other methods.
The timing of proton migration in membrane-reconstituted cytochrome
c
oxidase
Authors: Salomonsson Lina , Faxén Kristina , Ädelroth Pia , Brzezinski Peter
Published: November 2005

In mitochondria and aerobic bacteria energy conservation involves electron transfer through a number of membrane-bound protein complexes to O
2
. The reduction of O
2
, accompanied by the uptake of substrate protons to form H
2
O, is catalyzed by cytochrome
c
oxidase (C
c
O). This reaction is coupled to proton translocation (pumping) across the membrane such that each electron transfer to the catalytic site is linked to the uptake of two protons from one side and the release of one proton to the other side of the membrane. To address the mechanism of vectorial proton translocation, in this study we have investigated the solvent deuterium isotope effect of proton-transfer rates in C
c
O oriented in small unilamellar vesicles. Although in H
2
O the uptake and release reactions occur with the same rates, in D
2
O the substrate and pumped protons are taken up first (τ
D
≅ 200 μs, “peroxy” to “ferryl” transition) followed by a significantly slower proton release to the other side of the membrane (τ
D
≅ 1 ms). Thus, the results define the order and timing of the proton transfers during a pumping cycle. Furthermore, the results indicate that during C
c
O turnover internal electron transfer to the catalytic site is controlled by the release of the pumped proton, which suggests a mechanism by which C
c
O orchestrates a tight coupling between electron transfer and proton translocation.
Progression of primary pneumonic plague: A mouse model of infection, pathology, and bacterial transcriptional activity
Authors: Lathem Wyndham W. , Crosby Seth D. , Miller Virginia L. , Goldman William E.
Published: November 2005

Although pneumonic plague is the deadliest manifestation of disease caused by the bacteriumYersinia pestis, there is surprisingly little information on the cellular and molecular mechanisms responsible forY. pestis-triggered pathology in the lung. Therefore, to understand the progression of this unique disease, we characterized an intranasal mouse model of primary pneumonic plague. Mice succumbed to a purulent multifocal severe exudative bronchopneumonia that closely resembles the disease observed in humans. Analyses revealed a strikingly biphasic syndrome, in which the infection begins with an antiinflammatory state in the first 24-36 h that rapidly progresses to a highly proinflammatory state by 48 h and death by 3 days. To assess the adaptation ofY. pestisto a mammalian environment, we used DNA microarray technology to analyze the transcriptional responses of the bacteria during interaction with the mouse lung. Included among the genes up-regulatedin vivoare those comprising theyop-ysctype III secretion system and genes contained within the chromosomal pigmentation locus, validating the use of this technology to identify loci essential to the virulence ofY. pestis.
Coordinated transport of phosphorylated amyloid-β precursor protein and c-Jun NH2-terminal kinase–interacting protein-1
Authors: Muresan Zoia , Muresan Virgil
Published: November 2005

The transmembrane protein amyloid-β precursor protein (APP) and the vesicle-associated protein c-Jun NH2-terminal kinase–interacting protein-1 (JIP-1) are transported into axons by kinesin-1. Both proteins may bind to kinesin-1 directly and can be transported separately. Because JIP-1 and APP can interact, kinesin-1 may recruit them as a complex, enabling their cotransport. In this study, we tested whether APP and JIP-1 are transported together or separately on different vesicles. We found that, within the cellular context, JIP-1 preferentially interacts with Thr668-phosphorylated APP (pAPP), compared with nonphosphorylated APP. In neurons, JIP-1 colocalizes with vesicles containing pAPP and is excluded from those containing nonphosphorylated APP. The accumulation of JIP-1 and pAPP in neurites requires kinesin-1, and the expression of a phosphomimetic APP mutant increases JIP-1 transport. Down-regulation of JIP-1 by small interfering RNA specifically impairs transport of pAPP, with no effect on the trafficking of nonphosphorylated APP. These results indicate that the phosphorylation of APP regulates the formation of a pAPP–JIP-1 complex that accumulates in neurites independent of nonphosphorylated APP.
Ablation of β1 integrin in mammary epithelium reveals a key role for integrin in glandular morphogenesis and differentiation
Authors: Naylor Matthew J. , Li Na , Cheung Julia , Lowe Emma T. , Lambert Elise , Marlow Rebecca , Wang Pengbo , Schatzmann Franziska , Wintermantel Timothy , Schüetz Günther , Clarke Alan R. , Mueller Ulrich , Hynes Nancy E. , Streuli Charles H.
Published: November 2005

Integrin-mediated adhesion regulates the development and function of a range of tissues; however, little is known about its role in glandular epithelium. To assess the contribution of β1 integrin, we conditionally deleted its gene in luminal epithelia during different stages of mouse mammary gland development and in cultured primary mammary epithelia. Loss of β1 integrin in vivo resulted in impaired alveologenesis and lactation. Cultured β1 integrin–null cells displayed abnormal focal adhesion function and signal transduction and could not form or maintain polarized acini. In vivo, epithelial cells became detached from the extracellular matrix but remained associated with each other and did not undergo overt apoptosis. β1 integrin–null mammary epithelial cells did not differentiate in response to prolactin stimulation because of defective Stat5 activation. In mice where β1 integrin was deleted after the initiation of differentiation, fewer defects in alveolar morphology occurred, yet major deficiencies were also observed in milk protein and milk fat production and Stat5 activation, indicating a permissive role for β1 integrins in prolactin signaling. This study demonstrates that β1 integrin is critical for the alveolar morphogenesis of a glandular epithelium and for maintenance of its differentiated function. Moreover, it provides genetic evidence for the cooperation between integrin and cytokine signaling pathways.
Specific integrin α and β chain phosphorylations regulate LFA-1 activation through affinity-dependent and -independent mechanisms
Authors: Fagerholm Susanna C. , Hilden Tiina J. , Nurmi Susanna M. , Gahmberg Carl G.
Published: November 2005

Integrins are adhesion receptors that are crucial to the functions of multicellular organisms. Integrin-mediated adhesion is a complex process that involves both affinity regulation and cytoskeletal coupling, but the molecular mechanisms behind this process have remained incompletely understood. In this study, we report that the phosphorylation of each cytoplasmic domain of the leukocyte function-associated antigen-1 integrin mediates different modes of integrin activation. α Chain phosphorylation on Ser1140 is needed for conformational changes in the integrin after chemokine- or integrin ligand–induced activation or after activation induced by active Rap1 (Rap1V12). In contrast, the β chain Thr758 phosphorylation mediates selective binding to 14-3-3 proteins in response to inside-out activation through the T cell receptor, resulting in cytoskeletal rearrangements. Thus, site-specific phosphorylation of the integrin cytoplasmic domains is important for the dynamic regulation of these complex receptors in cells.
Pleiotropic effects of FGFR1 on cell proliferation, survival, and migration in a 3D mammary epithelial cell model
Authors: Xian Wa , Schwertfeger Kathryn L. , Vargo-Gogola Tracy , Rosen Jeffrey M.
Published: November 2005

Members of the fibroblast growth factor (FGF) family and the FGF receptors (FGFRs) have been implicated in mediating various aspects of mammary gland development and transformation. To elucidate the molecular mechanisms of FGFR1 action in a context that mimics polarized epithelial cells, we have developed an in vitro three-dimensional HC11 mouse mammary epithelial cell culture model expressing a drug-inducible FGFR1 (iFGFR1). Using this conditional model, iFGFR1 activation in these growth-arrested and polarized mammary acini initially led to reinitiation of cell proliferation, increased survival of luminal cells, and loss of cell polarity, resulting in the disruption of acinar structures characterized by the absence of an empty lumen. iFGFR1 activation also resulted in a gain of invasive properties and the induction of matrix metalloproteinase 3 (MMP-3), causing the cleavage of E-cadherin and increased expression of smooth muscle actin and vimentin. The addition of a pan MMP inhibitor abolished these phenotypes but did not prevent the effects of iFGFR1 on cell proliferation or survival.
Control of lateral migration and germ cell elimination by the Drosophila melanogaster lipid phosphate phosphatases Wunen and Wunen 2
Authors: Sano Hiroko , Renault Andrew D. , Lehmann Ruth
Published: November 2005

In most organisms, primordial germ cells (PGCs) arise far from the region where somatic gonadal precursors (SGPs) are specified. Although PGCs in general originate as a single cluster of cells, the somatic parts of the gonad form on each site of the embryo. Thus, to reach the gonad, PGCs not only migrate from their site of origin but also split into two groups. Taking advantage of high-resolution real-time imaging, we show that in Drosophila melanogaster PGCs are polarized and migrate directionally toward the SGPs, avoiding the midline. Unexpectedly, neither PGC attractants synthesized in the SGPs nor known midline repellents for axon guidance were required to sort PGCs bilaterally. Repellent activity provided by wunen (wun) and wunen-2 (wun-2) expressed in the central nervous system, however, is essential in this migration process and controls PGC survival. Our results suggest that expression of wun/wun-2 repellents along the migratory paths provides faithful control over the sorting of PGCs into two gonads and eliminates PGCs left in the middle of the embryo.
Androgen-dependent apoptosis in male germ cells is regulated through the proto-oncoprotein Cbl
Authors: El Chami Nisrine , Ikhlef Fouziha , Kaszas Krisztian , Yakoub Sadok , Tabone Eric , Siddeek Benazir , Cunha Stéphanie , Beaudoin Claude , Morel Laurent , Benahmed Mohamed , Régnier Daniel C.
Published: November 2005

The proto-oncoprotein Cbl is known to control several signaling processes. It is highly expressed in the testis, and because spermatogenesis is androgen dependent, we investigated the androgen dependency expression of Cbl through its testicular sublocalization and its expression levels in rats that were exposed to the antiandrogen flutamide or were hypophysectomized. We report the androgen dependency of Cbl as it localizes in pachytene spermatocytes during androgen-dependent stages, is down-regulated upon flutamide exposure, and is up-regulated with testosterone in hypophysectomized rats. Coculture experiments showed the key control exerted by the Sertoli cell on Cbl activity. As flutamide induces germ cell apoptosis, we investigate members of the Bcl-2 family upon flutamide exposure. We show that the proapoptotic Bcl-2 family member Bim mirrored Cbl expression through a posttranscriptional process. We also show that in Cbl knockout mouse testes, the imbalance between the high expression of Bim and Smac/Diablo and antiapoptotic factors such as cellular inhibitor of apoptosis 2 favors a survival process, which makes these mice unresponsive to androgen withdrawal and could explain their hypofertility.
Dissecting independent channel and scaffolding roles of the Drosophila transient receptor potential channel
Authors: Wang Tao , Jiao Yuchen , Montell Craig
Published: November 2005

Drosophila transient receptor potential (TRP) serves dual roles as a cation channel and as a molecular anchor for the PDZ protein, INAD (inactivation no afterpotential D). Null mutations in trp cause impairment of visual transduction, mislocalization of INAD, and retinal degeneration. However, the impact of specifically altering TRP channel function is not known because existing loss-of-function alleles greatly reduce protein expression. In the current study we describe the isolation of a set of new trp alleles, including trp14 with an amino acid substitution juxtaposed to the TRP domain. The trp14 flies stably express TRP and display normal molecular anchoring, but defective channel function. Elimination of the anchoring function alone in trpΔ1272, had minor effects on retinal morphology whereas disruption of channel function caused profound light-induced cell death. This retinal degeneration was greatly suppressed by elimination of the Na+/Ca2+ exchanger, CalX, indicating that the cell death was due primarily to deficient Ca2+ entry rather than disruption of the TRP-anchoring function.
Signal-mediated export of proteins from the malaria parasite to the host erythrocyte
Authors: Marti Matthias , Baum Jake , Rug Melanie , Tilley Leann , Cowman Alan F.
Published: November 2005

Intracellular parasites from the genus Plasmodium reside and multiply in a variety of cells during their development. After invasion of human erythrocytes, asexual stages from the most virulent malaria parasite, P. falciparum, drastically change their host cell and export remodelling and virulence proteins. Recent data demonstrate that a specific NH2-terminal signal conserved across the genus Plasmodium plays a central role in this export process.
The conserved kinase NHK-1 is essential for mitotic progression and unifying acentrosomal meiotic spindles in Drosophila melanogaster
Authors: Cullen C. Fiona , Brittle Amy L. , Ito Takashi , Ohkura Hiroyuki
Published: November 2005

Conventional centrosomes are absent from the spindle in female meiosis in many species, but it is not clear how multiple chromosomes form one shared bipolar spindle without centrosomes. We identified a female sterile mutant in which each bivalent chromosome often forms a separate bipolar metaphase I spindle. Unlike wild type, prophase I chromosomes fail to form a single compact structure within the oocyte nucleus, although the integrity of metaphase I chromosomes appears to be normal. Molecular analysis indicates that the mutant is defective in the conserved kinase nucleosomal histone kinase-1 (NHK-1). Isolation of further alleles and RNA interference in S2 cells demonstrated that NHK-1 is also required for mitotic progression. NHK-1 itself is phosphorylated in mitosis and female meiosis, suggesting that this kinase is part of the regulatory system coordinating progression of mitosis and meiosis.
Von Hippel-Lindau Disease Associated With Thymoma and Myasthenia Gravis
Authors: Sheth Maushmi N , Nations Sharon P , Wolfe Gil I , Trivedi Jaya R
Published: November 2005

Von Hippel-Lindau (VHL) disease is an autosomal-dominant disorder characterized by central nervous system hemangioblastomas, retinal angioma, and renal cell carcinoma. Thymoma and autoimmune neurologic disorders have not been reported in association with VHL disease. We report a unique concurrence of antibody-positive myasthenia gravis and thymoma in a patient with VHL disease. Although this may be coincidental, a possible genetic link between thymoma and VHL is described.
Lumbosacral Plexitis
Authors: Tarulli Andrew , Rutkove Seward B
Published: November 2005

Lumbosacral plexitis (LSP) is an uncommon idiopathic disorder characterized by the acute onset of severe lower extremity pain followed by wasting and weakness of leg muscles with variable sensory loss. Muscles innervated by multiple roots and multiple nerves are affected, and other causes of lumbosacral plexopathy such as mass lesions and trauma must be excluded. Postulated causes of LSP include vasculitis with subsequent axonal injury and autoimmune-related demyelination, although evidence is accumulating that the former pathophysiology is more likely. Recovery is variable but is often quite slow and incomplete. Immunomodulatory therapies such as corticosteroids, intravenous immunoglobulin, and plasma exchange are inconsistent in their efficacy.
Drug-Induced Myopathies
Authors: Bromberg Mark B
Published: November 2005

The incidence of drug-induced myopathic disorders is unknown. Estimates depend in part on definitions used. Cholesterol-lowering agents have been singled out as common offenders. However, the large number of available drugs, polypharmacy especially among the elderly, and known risk factors make the incidence of mild muscle disorders likely more common than suspected, but severe myopathies are likely rare. This article considers factors contributing to drug-induced myopathies and reviews examples of offending drugs.
Pediatric Deaths Due to Otolaryngologic Causes: A Population‐Based Study in Massachusetts, 1990–2002
Authors: Mehta Ritvik P. , Chesnulovitch Katrina , Jones Dwight T. , Roberson David W.
Published: November 2005

Objective: To identify the most common otolaryngologic causes of mortality in the 0 to 19 age group in the state of Massachusetts and to estimate the pediatric otolaryngologic mortality rate based on population data.

Study Design: Population‐based retrospective cohort study.

Methods: The Massachusetts State Registry of Vital Records and Statistics electronic database was searched for all otolaryngology related causes of death from 1990 to 2002 for children aged 0 to 19. The individual death certificates were then reviewed, and a database of otolaryngology related pediatric deaths was created.

Results: A total of 59 otolaryngology related deaths were identified in the pediatric population from 1990 to 2002. Eighty‐one percent of deaths occurred because of airway compromise caused by infection, anatomic obstruction, or congenital anomaly. The remaining 19% of deaths occurred because of aspiration, nonairway infections, and malignant neoplasms. Ninety‐five percent of deaths in the children under age 10 were caused by airway compromise. Six of seven deaths (86%) in the age 15 to 19 group occurred because of malignant neoplasms. The overall mortality rate caused by otolaryngologic causes was estimated to be 0.28 per 100,000 population.

Conclusions: The overall mortality rate for otolaryngology related deaths is low in the pediatric population. The vast majority of deaths are caused by airway compromise, primarily because of laryngotracheobronchitis or other upper airway obstruction. In older children (ages 15–19), malignant head and neck neoplasms are the leading cause of otolaryngology related deaths.
Transnasal Endoscopic Resection of Lesions of the Clivus: A Preliminary Report
Authors: Solares C Arturo , Fakhri Samer , Batra Pete S. , Lee Joung , Lanza Donald C.
Published: November 2005

Objective: To review our experience with transnasal endoscopic resection of clival lesions.

Background: Because of the surrounding vital structures and the difficulties in achieving wide surgical exposure, the treatment of clival lesions is challenging. In an effort to overcome these obstacles, many centers use facial incisions and osteotomies to approach clival lesions. Minimally invasive endoscopic techniques have the potential to minimize morbidity while yielding similar surgical results.

Study Design: Retrospective chart analysis.

Materials and Methods: Patients with tumors involving the clivus that underwent endoscopic resection between 2000 and 2004 were identified. Charts were reviewed for clinical characteristics, previous therapies, diagnosis, tumor extent, management modalities, length of hospital stay, complications, and outcome.

Results: A total of six patients were identified. There were four males and two females with a mean age of 50 years, ranging from 29 to 66 years. The most common presenting symptoms were visual disturbances. Three patients had prior craniotomy with subtotal tumor resection. The pathology included three clival chordomas, and one each of meningioma, adenoid cystic carcinoma, and sinonasal undifferentiated carcinoma. All patients were managed with computer‐aided transnasal endoscopic tumor resection with neurosurgical standby or involvement. None of the patients required additional craniotomies. The mean follow‐up was 13 (range, 8‐24) months. Intensity‐modulated radiation therapy was used in three patients, and two patients are currently undergoing proton beam radiation therapy (PBRT). The average length of hospital stay was 2 (range, 2‐3) days. There were no major postoperative complications. At the last follow‐up, five patients were alive with two patients being free of disease. Two patients with residual disease are currently undergoing PBRT, and one patient developed distant metastasis. One patient died of unrelated causes.

Conclusions: This preliminary report suggests that transnasal endoscopic management of clival lesions is a viable option to traditional open approaches with acceptable morbidity and mortality. The use of computer‐aided surgery further minimizes surgical risks while maximizing tumor resection.
Open Set Speech Perception with Auditory Brainstem Implant?
Authors: Colletti Vittorio , Shannon Robert V.
Published: November 2005

Objective: Only a small percentage of auditory brainstem implant (ABI) recipients treated for neurofibromatosis type 2 (NF2) have proved capable of identifying words using only the sound from the ABI. Recently, the ABI was applied to a series of patients with no cochlear nerve or with cochlear disorders that could not benefit from a cochlear implant (i.e., cochlear nerve aplasia or posttraumatic avulsion) or whose benefit was or would be severely compromised. A significant number of these patients have proven capable of understanding speech, including effortless telephone use. In the present study, a series of psychophysical tests were administered to determine the cause of the difference in performance between tumor (T) and nontumor (NT) ABI patients.

Study Design: Retrospective case review.

Setting: Tertiary referral center.

Patients: Twenty patients with ABIs participated in the investigation. Ten were NF2 patients and 10 NT subjects. Patient ages ranged from 24 to 61 years. Eleven were males and nine females.

Intervention: Auditory rehabilitation in auditory disconnection caused by cochlea or cochlear nerve disorders.

Results: There was a significant correlation between modulation detection thresholds and speech understanding and a significant difference in modulation detection between T and NT patients.

Conclusions: The difference in modulation detection between the two groups suggests a difference in the survival of specific cells in the cochlear nucleus that support modulation. The pattern of results indicates a separate pathway of auditory processing that is specialized for modulated sounds, and that pathway is critical for speech understanding. In NF2 patients, the tumor and surgery may selectively damage this pathway, resulting in poor speech recognition with prosthetic stimulation.
Osteoradionecrosis with Combined Mandibulotomy and Marginal Mandibulectomy
Authors: Wang Chih‐Chun , Cheng Ming‐Huei , Hao Sheng‐Po , Wu Chia‐Chen , Huang Shan‐Shung
Published: November 2005

Introduction: To evaluate the outcome of simultaneous anterior mandibulotomy and marginal mandibulectomy for patients with oral cavity cancer.

Material and Methods: The medical charts of seven patients who underwent simultaneous anterior mandibulotomy and marginal mandibulectomy for oral cavity cancer between July 1994 and June 2004 in Chang Gung Memorial Hospital, Taiwan were retrospectively reviewed. These seven patients had no prior radiation therapy nor clinical or radiographic evidence of mandible bone invasion.

Results: Seven patients, between 34 to 62 years of age, were followed up in the clinics from 4.5 to 39 months with an average of 19.4 months. Five (71%) patients developed mandible osteoradionecrosis. Among them, two patients underwent radical sequestrectomy followed by reconstruction with a free fibular osteoseptocutaneous flap or soft tissue flap, and the other three patients either received removal of the mandible fixation miniplate, limited sequestrectomy of the mandible, or conservative antibiotic treatment individually.

Conclusions: Simultaneous anterior mandibulotomy and marginal mandibulectomy results in a high morbidity rate of avascular necrosis of the mandible and therefore should be avoided. To avoid a disastrous complication, segmental mandibulectomy and a composite free fibular osteoseptocutaneous flap reconstruction would be a preferred surgical alternative.
Voice Disorders in the General Population: Prevalence, Risk Factors, and Occupational Impact
Authors: Roy Nelson , Merrill Ray M. , Gray Steven D. , Smith Elaine M.
Published: November 2005

Objectives: Epidemiologic studies of the prevalence and risk factors of voice disorders in the general adult population are rare. The purpose of this investigation was to 1) determine the prevalence of voice disorders, 2) identify variables associated with increased risk of voice disorders, and 3) establish the functional impact of voice disorders on the general population.

Study Design: Cross‐sectional telephone survey.

Methods: A random sample (n = 1,326) of adults in Iowa and Utah was interviewed using a questionnaire that addressed three areas related to voice disorders: prevalence, potential risk factors, and occupational consequences/effects.

Results: The lifetime prevalence of a voice disorder was 29.9%, with 6.6% of participants reporting a current voice disorder. Stepwise logistic regression identified specific factors that uniquely contributed to increased odds of reporting a chronic voice disorder including sex (women), age (40–59 years), voice use patterns and demands, esophageal reflux, chemical exposures, and frequent cold/sinus infections. However, tobacco or alcohol use did not independently increase the odds of reporting of a chronic voice disorder. Voice disorders adversely impacted job performance and attendance, with 4.3% of participants indicating that their voice had limited or rendered them unable to do certain tasks in their current job. Furthermore, 7.2% of employed respondents reported that they were absent from work 1 or more days in the past year because of their voice, and 2% reported more than 4 days of voice‐related absence.

Conclusions: The results of this large epidemiologic study provide valuable information regarding the prevalence of voice disorders, factors that contribute to voice disorder vulnerability, and the functional impact of voice problems on the general population.
Protective Effect of Isoflurane Anesthesia on Noise‐Induced Hearing Loss in Mice
Authors: Kim Joung Uk , Lee Hyun Jung , Kang Hun Hee , Shin Jin Woo , Ku Seung Woo , Ahn Joong Ho , Kim Young Jin , Chung Jong Woo
Published: November 2005

Hypothesis/Objectives:To examine the protective effect of general anesthesia with isoflurane against noise‐induced hearing loss in mice.

Study Design:Animal study using noise stimulation and measurement of hearing in BALB/c mice.

Methods:Mice were exposed to 122 dB peak equivalent sound pressure level click noise for 3 hours per day for 3 consecutive days with or without anesthesia using isoflurane. Hearing levels were measured and hair cell survival ratio was observed.

Results:In mice without anesthesia, hearing threshold increased after noise stimulation (73.7 dB hearing level [HL]) and persisted for at least 1 month. However, in mice exposed to noise under anesthesia, hearing loss was less severe (44.1 dB HL) and had recovered more (26.5 dB HL) by one month. Histological examination showed hair cell survival was higher in anesthetized compared to non‐anesthetized mice.

Conclusion:These data indicate isoflurane general anesthesia protects against noise‐induced hearing loss and tissue damage in mice.
Olivocochlear Activity and Temporary Threshold Shift‐Susceptibility in Humans
Authors: Wagner W , Heppelmann G , Kuehn M , Tisch M , Vonthein R , Zenner H ‐P.
Published: November 2005

Study Objectives: Animal studies (guinea pig, cat, chinchilla) have shown that activity of the medial olivocochlear efferents can exert noise‐protective effects on the cochlea. It is not yet known whether such effects are also existent in humans. Olivocochlear activity can be estimated indirectly by contralateral suppression (CS) of otoacoustic emissions (OAE).

Material and Methods: We measured Input/Output functions of distortion products of OAE (DPOAE), with and without contralateral acoustic stimulation by white noise, in 94 normal hearing young male subjects. Seven stimuli with L2 between 20 and 60 dB SPL and L1 = 39 dB + 0.4 L2 (“scissor paradigm”) were used at f2 = 2, 3, 4, 5, and 6 kHz. The measurement was repeated 2 weeks later. In 83 subjects of the same group, pure tone audiometry was registered before and 6 minutes after shooting exercises to evaluate individual susceptibility to develop a temporary threshold shift (TTS).

Results: Test‐retest repeatability of CS was generally good. CS averaged 0.98 dB SPL (SD 1.19 dB, median 0.56 dB). As expected, CS was greatest at low stimulus levels (median 1.06 dB at L2 = 20 dB, as compared with 0.33 dB at L2 = 60 dB). The smallest average CS was found at 4 kHz, and the greatest CS appeared at 2 kHz. A TTS occurred in 7 of 83 (8.5%) subjects. Statistical analysis did not reveal any correlation between the amount of CS and individual TTS susceptibility.

Conclusions and Outlook: 1) Measurement of CS of DPOAE using an extensive measurement paradigm revealed good test‐retest repeatability, confirming the reliability of this audiologic tool. 2) CS of DPOAE does not predict individual susceptibility to mild TTS induced by impulse noise in humans. Possible explanations for the missing association are discussed. Future perspectives include longitudinal studies to further elucidate the association between medial olivocochlear bundle‐activity and permanent threshold shift in humans. The goal is to develop a diagnostic tool for the prediction of individual noise vulnerability in humans, thereby preventing noise‐induced hearing loss.
In Vivo Optical Coherence Tomography of the Human Larynx: Normative and Benign Pathology in 82 Patients
Authors: Wong Brian J. F. , Jackson Ryan P. , Guo Shuguang , Ridgway James M. , Mahmood Usama , Su Jianping , Shibuya Terry Y. , Crumley Roger L. , Gu Mai , Armstrong William B. , Chen Zhongping
Published: November 2005

Objectives: Optical coherence tomography (OCT) is an emerging imaging modality that combines low‐coherence light with interferometry to produce cross‐sectional images of tissue with resolution about 10 μm. Patients undergoing surgical head and neck endoscopy were examined using a fiberoptic OCT imaging probe to study and characterize microstructural anatomy and features of the larynx and benign laryngeal pathology in vivo.

Study Design: Prospective clinical trial.

Materials and Methods: OCT imaging of the larynx was performed in 82 of 115 patients who underwent surgical endoscopy for various head and neck pathologies. The OCT device employs a 1.3 μm broadband light source (FWHM, 80 nm). The frame rate is 1 Hz. Imaging was performed using a handheld probe placed in near contact with the target site. The maximum axial and lateral dimensions for the region of interest imaged were 2.5 mm × 6 mm, with resolutions of 10 μm. Simultaneously, conventional endoscopic images were obtained to provide anatomic correlation with OCT images and histology. Optical micrometry was performed to measure the epithelium thickness.

Results: Systematic OCT imaging of laryngeal structures and subsites provided information on the thickness of the epithelium, integrity of the basement membrane, and structure of the lamina propria. Microstructural features identified included glands, ducts, blood vessels, fluid collection/edema, and the transitions between pseudostratified columnar and stratified squamous epithelium. The mean epithelial thickness of laryngeal subsites was calculated: true vocal cord (129 μm), false vocal cords (124 μm), aryepiglottic fold (177 μm), subglottis (98 μm), and epiglottis (185 μm). True vocal cord pathology imaged included Reinke's edema, papillomatosis, polyps, mucous cysts, and granulation tissue. Subglottic imaging identified boundaries between epithelium, lamina propria, and cartilage. The OCT images compared favorably with conventional histopathology.

Conclusion: OCT has the unique ability to image laryngeal tissue microstructure and can detail microanatomic changes in benign, premalignant, and malignant laryngeal pathologies. OCT holds the potential to guide surgical biopsies, direct therapy, and monitor disease, particularly when office‐based systems are developed. This is a promising imaging modality to study the larynx.