bluuebunny/crossref_metadata_2025 huggingface dataset:
Central nitric oxide blocks vasopressin, oxytocin and atrial natriuretic peptide release and antidiuretic and natriuretic responses induced by central angiotensin II in conscious rats
Authors: Reis Wagner Luis , Giusti‐Paiva Alexandre , Ventura Renato Rizo , Margatho Lisandra Oliveira , Gomes Dayane Aparecida , Elias Lucila Leico Kagohara , Antunes‐Rodrigues José
Published: May 2007

The presence of nitric oxide synthase (NOS), the enzyme that catalyses the formation of nitric oxide (NO), in the circumventricular organs and magnocellular neurones suggests an important role of NO in the modulation of vasopressin (AVP) and oxytocin (OT) release. Intracerebroventricular (i.c.v.) injection of angiotensin II (Ang II) stimulates the release of AVP, OT and atrial natriuretic peptide (ANP), with the resultant antidiuretic and natriuretic effects. This study investigated the interaction between nitrergic and angiotensinergic pathways on the release of AVP, OT and ANP and on urinary volume and sodium excretion in water‐loaded rats. Unanaesthetized, freely moving, male Wistar rats received two water loads followed by an injection into the lateral ventricle of an inhibitor of NOS (l‐NAME), a NO donor [3‐morpholinylsydnoneimine chloride (SIN‐1) or S‐nitroso‐N‐acetyl penicillamine (SNAP)] or vehicle (isotonic saline) and, 20 min after, they received a second i.c.v. injection of Ang II or vehicle. Injections of l‐NAME or Ang II produced an increase in plasma levels of AVP, OT and ANP, a reduction in urinary volume and an increase in sodium excretion. Pretreatment with l‐NAME enhanced the Ang II‐induced increase in AVP, OT and ANP release, as well as the antidiuresis and natriuresis. Injection of SIN‐1 or SNAP did not modify hormonal plasma levels and urinary parameters. In contrast SNAP blocked the AVP, OT and ANP release, as well as antidiuretic and natriuretic responses induced by ANG‐II. Thus, the central nitrergic system can act to inhibit AVP, OT and ANP secretion and the antidiuretic and natriuretic effects in response to Ang II.
A Stochastic Form of a Human Driver Steering Dynamics Model
Authors: Gabibulayev Magomed , Ravani Bahram
Published: May 2007

This work develops a stochastic form of a human driver model which can be used for simulating vehicle guidance and control. The human motor-control function is complex and can be affected by factors such as driver’s training and experience, fatigue, road conditions, and attention. The variations in these effects become more pronounced in hazardous driving conditions such as in snow and ice. One example of such driving conditions is snow removal operation in highway maintenance, where the use of a stochastic driver model seems to be more desirable. This work evaluates and extends existing models of a human driver including stochastic or statistical considerations related to differences in drivers’ experiences and their conditions as well as variations in the effect of disturbances such as plowing forces. The aim is to develop a simulation environment that can be used in design and evaluation of driver assistance systems for snow removal operation in an Intelligent Transportation System environment.
Reliable Robust H∞ Fuzzy Control for Uncertain Nonlinear Systems With Markovian Jumping Actuator Faults
Authors: Wu Huai-Ning
Published: May 2007

This paper is concerned with the design of reliable robust H∞ fuzzy control for uncertain nonlinear continuous-time systems with Markovian jumping actuator faults. The Takagi and Sugeno fuzzy model is employed to represent an uncertain nonlinear system with Markovian jumping actuator faults. First, based on the parallel distributed compensation (PDC) scheme, a sufficient condition such that the closed-loop fuzzy system is robustly stochastically stable and satisfies a prescribed level of H∞-disturbance attenuation is derived. In the derivation process, a stochastic Lyapunov function is used to test the stability and H∞ performance of the system. Then, a new improved linear matrix inequality (LMI) formulation is applied to this condition to alleviate the interrelation between the stochastic Lyapunov matrix and system matrices containing controller variables, which results in a tractable LMI-based condition for the existence of reliable and robust H∞ fuzzy controllers. A suboptimal fuzzy controller is proposed to minimize the level of disturbance attenuation subject to the LMI constraints. Finally, a simulation example is given to illustrate the effectiveness of the proposed method.
Thinning of N-face GaN (0001 ¯) samples by inductively coupled plasma etching and chemomechanical polishing
Authors: Rizzi F. , Gu E. , Dawson M. D. , Watson I. M. , Martin R. W. , Kang X. N. , Zhang G. Y.
Published: May 2007

The processing of N-polar GaN (0001 ¯) samples has been studied, motivated by applications in which extensive back side thinning of freestanding GaN (FS-GaN) substrates is required. Experiments were conducted on FS-GaN from two commercial sources, in addition to epitaxial GaN with the N-face exposed by a laser lift-off process. The different types of samples produced equivalent results. Surface morphologies were examined over relatively large areas, using scanning electron microscopy and stylus profiling. The main focus of this study was on inductively coupled plasma (ICP) etch processes, employing Cl2∕Ar or Cl2∕BCl3Ar gas mixtures. Application of a standard etch recipe, optimized for feature etching of Ga-polar GaN (0001) surfaces, caused severe roughening of N-polar samples and confirmed the necessity for specific optimization of etch conditions for N-face material. A series of recipes with a reduced physical (sputter-based) contribution to etching allowed average surface roughness values to be consistently reduced to below 3nm. Maximum N-face etch rates of 370–390nm∕min have been obtained in recipes examined to date. These are typically faster than etch rates obtained on Ga-face samples under the same conditions and adequate for the process flows of interest. Mechanistic aspects of the ICP etch process and possible factors contributing to residual surface roughness are discussed. This study also included work on chemomechanical polishing (CMP). The optimized CMP process had stock removal rates of ∼500nm∕h on the GaN N face. This was much slower than the ICP etching but showed the important capability of recovering smooth surfaces on samples roughened in previous processing. In one example, a surface roughened by nonoptimized ICP etching was smoothed to give an average surface roughness of ∼2nm.
Metal-gate-induced reduction of the interfacial layer in Hf oxide gate stacks
Authors: Goncharova L. V. , Dalponte M. , Gustafsson T. , Celik O. , Garfunkel E. , Lysaght P. S. , Bersuker G.
Published: May 2007

The properties of high-κ metal oxide gate stacks are often determined in the final processing steps following dielectric deposition. We report here results from medium energy ion scattering and x-ray photoelectron spectroscopy studies of oxygen and silicon diffusion and interfacial layer reactions in multilayer gate stacks. Our results show that Ti metallization of HfO2∕SiO2∕Si stacks reduces the SiO2 interlayer and (to a more limited extent) the HfO2 layer. We find that Si atoms initially present in the interfacial SiO2 layer incorporate into the bottom of the high-κ layer. Some evidence for Ti–Si interdiffusion through the high-κ film in the presence of a Ti gate in the crystalline HfO2 films is also reported. This diffusion is likely to be related to defects in crystalline HfO2 films, such as grain boundaries. High-resolution transmission electron microscopy and corresponding electron energy loss spectroscopy scans show aggressive Ti–Si intermixing and oxygen diffusion to the outermost Ti layer, given high enough annealing temperature. Thermodynamic calculations show that the driving forces exist for some of the observed diffusion processes.
Study of poly(vinylidene fluoride-trifluoroethylene) as a potential organic high K gate dielectric
Authors: Li Y. X. , Yan L. , Shrestha R. P. , Yang D. , Irene E. A.
Published: May 2007

Spin cast films of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer deposited on bare Si and SiO2 coated Si substrates were vacuum annealed and treated in supercritical carbon dioxide (scCO2) and the dielectric properties of the films before and after treatments were studied using capacitance-voltage and conductance-voltage techniques on thin film capacitor structures. After annealing, the static dielectric constant (K) for P(VDF-TrFE) was found to be more than double that for SiO2 films and to increase with film thickness and annealing time, and reached a maximum of nearly 10 for thick films on SiO2 or Si substrates. Treating annealed P(VDF-TrFE) films in scCO2 initially decreased K and the refractive index n to as-deposited values that increased and stabilized after reannealing. The changes in P(VDF-TrFE) were attributed to densification and ordering. No systematic differences in interface charges and states were found between treated and untreated samples and with various substrates. The leakage current for P(VDF-TrFE) films was found to be higher than that for SiO2.
Effect of NH3 on the low pressure chemical vapor deposition of TiO2 film at low temperature using tetrakis(diethylamino)titanium and oxygen
Authors: Song Xuemei , Takoudis Christos G.
Published: May 2007

The effect of NH3 on TiO2 film deposition using tetrakis(diethylamino)titanium (TDEAT) and O2 as source gases in a low pressure chemical vapor deposition reactor was studied at low temperatures ranging from 100to250°C. TiO2 film is traditionally deposited at temperature above 300°C using oxygen-based Ti precursors, such as titanium tetraisopropoxide. In this study, the authors demonstrate that a combination of both reactive precursors, i.e., TDEAT and NH3, is an effective technique for TiO2 film deposition at lower temperatures, albeit with some nitrogen incorporation. It was found that films can be formed at temperatures as low as 100°C when NH3 is used. At higher temperatures, the growth rate of TiO2 films deposited using NH3 is higher than that of films deposited without NH3 by up to one order of magnitude. X-ray photoelectron spectroscopy data show that NH3 enhances the formation of TiNO and TiN, and x-ray diffraction analysis shows that all as-deposited films have amorphous structure. Both x-ray photoelectron spectroscopy and secondary ion mass spectroscopy depth profiles show that nitrogen, carbon, and oxygen are uniformly distributed throughout the film. The mechanism of enhancement of growth rate using NH3 is also discussed.
Effect of oxygen concentration on the spike formation during reactive ion etching of SiC using the mixed gas plasma of NF3 and O2
Authors: Tasaka A. , Watanabe E. , Kai T. , Shimizu W. , Kanatani T. , Inaba M. , Tojo T. , Tanaka M. , Abe T. , Ogumi Z.
Published: May 2007

Reactive ion etching (RIE) of poly-β-SiC was investigated in the NF3∕O2 mixture gas plasma. The addition of 10% oxygen concentration to the NF3 plasma increased the etching rate to ∼80nm∕min at a total pressure of 10Pa and 997nm∕min at a total pressure of 20Pa. The ratio of increase in etching rate against that in the pure NF3 plasma was ∼43%. RIE for longer than 30min in the 90% NF3 and 10% O2 mixture gas plasma gave a much smoother surface than that etched in the pure NF3 plasma. However, the further addition of O2 decreased the etching rate. Optical-emission spectra indicated the presence of an oxygen radical, in addition to fluorine radical and molecular nitrogen cations, in the NF3∕O2 mixture gas plasma. X-ray photoemission spectroscopy analysis of the etched samples revealed that the SiO2 layer was formed on the surface at the higher O2 concentration. The role of oxygen in the NF3∕O2 mixture gas plasma was elucidated. Scanning electron microscopy observation revealed that many thornlike substances, i.e., spikes, were formed on the SiC surface during RIE at the total pressure of 10Pa. Images of the cross section of spike formed during RIE at the total pressure of 2Pa also indicated that the sputtered aluminum particle from a mask may be preferentially deposited on the top of carbon-rich island formed on the SiC surface and act as a micromask together with carbon on the carbon-rich island to form a thornlike spike. An etching model of the SiC surface and the mechanism on formation and growth of the spike on the SiC surface in the NF3∕O2 mixture gas plasma are proposed.
Prevalence, Characteristics, and Molecular Epidemiology of Macrolide and Fluoroquinolone Resistance in Clinical Isolates of
Streptococcus pneumoniae
at Five Tertiary-Care Hospitals in Korea
Authors: Shin Jeong Hwan , Jung Hee Jung , Kim Hye Ran , Jeong Joseph , Jeong Seok Hoon , Kim Sunjoo , Lee Eun Yup , Lee Jeong Nyeo , Chang Chulhun Ludgerus
Published: May 2007

The genes
erm
(B),
mef
(A), and both
erm
(B) and
mef
(A) were identified in 42.6, 10.1, and 47.3%, respectively, of the erythromycin-resistant
Streptococcus pneumoniae
isolates. Of the strains, 3.8% were nonsusceptible to levofloxacin and had 1 to 6 amino acid changes in the quinolone resistance-determining region, including a new mutation, Asn94Ser, in the product of
parC
. Levofloxacin with reserpine was highly specific for efflux screening.
Inhibition of Type III Secretion inSalmonella entericaSerovar Typhimurium by Small-Molecule Inhibitors
Authors: Hudson Debra L. , Layton Abigail N. , Field Terry R. , Bowen Alison J. , Wolf-Watz Hans , Elofsson Mikael , Stevens Mark P. , Galyov Edouard E.
Published: May 2007

Type III secretion systems (T3SS) are conserved in many pathogenic gram-negative bacteria. Small molecules that specifically target T3SS inYersiniaandChlamydiaspp. have recently been identified. Here we show that two such compounds inhibitSalmonellaT3SS-1, preventing secretion of T3SS-1 effectors, invasion of cultured epithelial cells, and enteritis in vivo.
Expression of Reductive Dehalogenase Genes in
Dehalococcoides ethenogenes
Strain 195 Growing on Tetrachloroethene, Trichloroethene, or 2,3-Dichlorophenol
Authors: Fung Jennifer M. , Morris Robert M. , Adrian Lorenz , Zinder Stephen H.
Published: May 2007

Reductive dehalogenase (RD) gene transcript levels in
Dehalococcoides ethenogenes
strain 195 were investigated using reverse transcriptase quantitative PCR during growth and reductive dechlorination of tetrachloroethene (PCE), trichloroethene (TCE), or 2,3-dichlorophenol (2,3-DCP). Cells grown with PCE or TCE had high transcript levels (greater than that for
rpoB
) for
tceA
, which encodes the TCE RD,
pceA
, which encodes the PCE RD, and DET0162, which contains a predicted stop codon and is considered nonfunctional. In cells grown with 2,3-DCP,
tceA
mRNA was less than 1% of that for
rpoB
, indicating that its transcription was regulated.
pceA
and DET0162 were the only RD genes with high transcript levels in cells grown with 2,3-DCP. Proteomic analysis of PCE-grown cells detected both PceA and TceA with high peptide coverage but not DET0162, and analysis of 2,3-DCP-grown cells detected PceA with high coverage but not TceA, DET0162, or any other potential RD. Cells grown with PCE or 2,3-DCP were tested for the ability to dechlorinate PCE, TCE, or 2,3-DCP with H
2
as the electron donor. 2,3-DCP-grown cells were unable to dechlorinate TCE but dechlorinated PCE to TCE without a lag, and PCE-grown cells dechlorinated 2,3-DCP without a lag. These results show that 2,3-DCP-grown cells do not produce TceA and that DET0162 is transcribed but its translation product is not detectable in cells and are consistent with PceA's being bifunctional, also serving as the 2,3-DCP RD. Chlorophenols naturally occur in soils and are good candidates for the original substrates for PceA.
Highly Efficient Gluten Degradation by Lactobacilli and Fungal Proteases during Food Processing: New Perspectives for Celiac Disease
Authors: Rizzello Carlo G. , De Angelis Maria , Di Cagno Raffaella , Camarca Alessandra , Silano Marco , Losito Ilario , De Vincenzi Massimo , De Bari Maria D. , Palmisano Francesco , Maurano Francesco , Gianfrani Carmen , Gobbetti Marco
Published: May 2007

Presently, the only effective treatment for celiac disease is a life-long gluten-free diet. In this work, we used a new mixture of selected sourdough lactobacilli and fungal proteases to eliminate the toxicity of wheat flour during long-time fermentation. Immunological (R5 antibody-based sandwich and competitive enzyme-linked immunosorbent assay [ELISA] and R5 antibody-based Western blot), two-dimensional electrophoresis, and mass spectrometry (matrix-assisted laser desorption ionization-time of flight, strong-cation-exchange-liquid chromatography/capillary liquid chromatography-electrospray ionization-quadrupole-time of flight [SCX-LC/CapLC-ESI-Q-TOF], and high-pressure liquid chromatography-electrospray ionization-ion trap mass spectrometry) analyses were used to determine the gluten concentration. Assays based on the proliferation of peripheral blood mononuclear cells (PBMCs) and gamma interferon production by PBMCs and intestinal T-cell lines (iTCLs) from 12 celiac disease patients were used to determine the protein toxicity of the pepsin-trypsin digests from fermented wheat dough (sourdough). As determined by R5-based sandwich and competitive ELISAs, the residual concentration of gluten in sourdough was 12 ppm. Albumins, globulins, and gliadins were completely hydrolyzed, while ca. 20% of glutenins persisted. Low-molecular-weight epitopes were not detectable by SCX-LC/CapLC-ESI-Q-TOF mass spectrometry and R5-based Western blot analyses. The kinetics of the hydrolysis of the 33-mer by lactobacilli were highly efficient. All proteins extracted from sourdough activated PBMCs and induced gamma interferon production at levels comparable to the negative control. None of the iTCLs demonstrated immunoreactivity towards pepsin-trypsin digests. Bread making was standardized to show the suitability of the detoxified wheat flour. Food processing by selected sourdough lactobacilli and fungal proteases may be considered an efficient approach to eliminate gluten toxicity.
Mutational Analysis of Endoxylanases XylA and XylB from the Phytopathogen
Fusarium graminearum
Reveals Comprehensive Insights into Their Inhibitor Insensitivity
Authors: Beliën Tim , Van Campenhout Steven , Van Acker Maarten , Robben Johan , Courtin Christophe M. , Delcour Jan A. , Volckaert Guido
Published: May 2007

Endo-β-1,4-xylanases (EC 3.2.1.8; endoxylanases), key enzymes in the degradation of xylan, are considered to play an important role in phytopathogenesis, as they occupy a prominent position in the arsenal of hydrolytic enzymes secreted by phytopathogens to breach the cell wall and invade the plant tissue. Plant endoxylanase inhibitors are increasingly being pinpointed as part of a counterattack mechanism. To understand the surprising XIP-type endoxylanase inhibitor insensitivity of endoxylanases XylA and XylB from the phytopathogen
Fusarium graminearum
, an extensive mutational study of these enzymes was performed. Using combinatorial and site-directed mutagenesis, the XIP insensitivity of XylA as well as XylB was proven to be solely due to amino acid sequence adaptations in the “thumb” structural region. While XylB residues Cys
141
, Asp
148
, and Cys
149
were shown to prevent XIP interaction, the XIP insensitivity of XylA could be ascribed to the occurrence of only one aberrant residue, i.e., Val
151
. This study, in addition to providing a thorough explanation for the XIP insensitivity of both
F. graminearum
endoxylanases at the molecular level, generated XylA and XylB mutants with altered inhibition specificities and pH optima. As this is the first experimental elucidation of the molecular determinants dictating the specificity of the interaction between endoxylanases of phytopathogenic origin and a plant inhibitor, this work sheds more light on the ongoing evolutionary arms race between plants and phytopathogenic fungi involving recognition of endoxylanases.
Alpha-Agarases Define a New Family of Glycoside Hydrolases, Distinct from Beta-Agarase Families
Authors: Flament Didier , Barbeyron Tristan , Jam Murielle , Potin Philippe , Czjzek Mirjam , Kloareg Bernard , Michel Gurvan
Published: May 2007

The gene encoding the α-agarase from “
Alteromonas agarilytica
” (proposed name) has been cloned and sequenced. The gene product (154 kDa) is unrelated to β-agarases and instead belongs to a new family of glycoside hydrolases (GH96). The α-agarase also displays a complex modularity, with the presence of five thrombospondin type 3 repeats and three carbohydrate-binding modules.
Extended-Spectrum β-Lactamase CTX-M-1 in
Escherichia coli
Isolates from Healthy Poultry in France
Authors: Girlich Delphine , Poirel Laurent , Carattoli Alessandra , Kempf Isabelle , Lartigue Marie-Frédérique , Bertini Alessia , Nordmann Patrice
Published: May 2007

Genes encoding extended-spectrum β-lactamase CTX-M-1 were detected in 12
Escherichia coli
isolates recovered over a 7-month period from the ceca of healthy poultry in seven districts in France in 2005. Eleven of those strains were not clonally related and had a
bla
CTX-M-1
gene located on transferable plasmids of different sizes and structures.
Role of Primary Human Alveolar Epithelial Cells in Host Defense against
Francisella tularensis
Infection
Authors: Gentry Megan , Taormina Joanna , Pyles Richard B. , Yeager Linsey , Kirtley Michelle , Popov Vsevolod L. , Klimpel Gary , Eaves-Pyles Tonyia
Published: May 2007

Francisella tularensis
, an intracellular pathogen, is highly virulent when inhaled. Alveolar epithelial type I (ATI) and type II (ATII) cells line the majority of the alveolar surface and respond to inhaled pathogenic bacteria via cytokine secretion. We hypothesized that these cells contribute to the lung innate immune response to
F. tularensis
. Results demonstrated that the live vaccine strain (LVS) contacted ATI and ATII cells by 2 h following intranasal inoculation of mice. In culture, primary human ATI or ATII cells, grown on transwell filters, were stimulated on the apical (AP) surface with virulent
F. tularensis
Schu 4 or LVS. Basolateral (BL) conditioned medium (CM), collected 6 and 24 h later, was added to the BL surfaces of transwell cultures of primary human pulmonary microvasculature endothelial cells (HPMEC) prior to the addition of polymorphonuclear leukocytes (PMNs) or dendritic cells (DCs) to the AP surface. HPMEC responded to S4- or LVS-stimulated ATII, but not ATI, CM as evidenced by PMN and DC migration. Analysis of the AP and BL ATII CM revealed that both
F. tularensis
strains induced various levels of a variety of cytokines via NF-κB activation. ATII cells pretreated with an NF-κB inhibitor prior to
F. tularensis
stimulation substantially decreased interleukin-8 secretion, which did not occur through Toll-like receptor 2, 2/6, 4, or 5 stimulation. These data indicate a crucial role for ATII cells in the innate immune response to
F. tularensis
.
Enucleated L929 Cells Support Invasion, Differentiation, and Multiplication of
Trypanosoma cruzi
Parasites
Authors: Coimbra Vanessa C. , Yamamoto Denise , Khusal Ketna G. , Atayde Vanessa Diniz , Fernandes Maria Cecília , Mortara Renato A. , Yoshida Nobuko , Alves Maria Julia M. , Rabinovitch Michel
Published: May 2007

Cell infection with
Trypanosoma cruzi
, the agent of Chagas’ disease, begins with the uptake of infective trypomastigotes within phagosomes and their release into the cytosol, where they transform into replicating amastigotes; the latter, in turn, differentiate into cytolytically released and infective trypomastigotes. We ask here if the
T. cruzi
infection program can develop in enucleated host cells. Monolayers of L929 cells, enucleated by centrifugation in the presence of cytochalasin B and kept at 34°C to extend the survival of cytoplasts, were infected with parasites of the CL strain. Percent infection, morphology, stage-specific markers, and numbers of parasites per cell were evaluated in nucleated and enucleated cells, both of which were present in the same preparations. Parasite uptake, differentiation and multiplication of amastigotes, development of epimastigote- and trypomastigote-like forms, and initial cytolytic release of parasites were all documented for cytoplasts and nucleated cells. Although the doubling times were similar, parasite loads at 48 and 72 h were significantly lower in the cytoplasts than in nucleated cells. Similar results were obtained with the highly virulent strain Y as well as with strains CL-14 and G, which exhibit low virulence for mice. Cytoplasts could also be infected with the CL strain 24 or 48 h after enucleation. Thus, infection of cells by
T. cruzi
can take place in enucleated host cells, i.e., in the absence of modulation of chromosomal and nucleolar gene transcription and of RNA modification and processing in the nucleus.
Eca1, a Sarcoplasmic/Endoplasmic Reticulum Ca2+-ATPase, Is Involved in Stress Tolerance and Virulence inCryptococcus neoformans
Authors: Fan Weihua , Idnurm Alexander , Breger Julia , Mylonakis Eleftherios , Heitman Joseph
Published: May 2007

The basidiomycetous fungal pathogenCryptococcus neoformansis adapted to survive challenges in the soil and environment and within the unique setting of the mammalian host. AC. neoformansmutant was isolated with enhanced virulence in a soil amoeba model that nevertheless exhibits dramatically reduced growth at mammalian body temperature (37°C). This mutant phenotype results from an insertion in theECA1gene, which encodes a sarcoplasmic/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA)-type calcium pump. Infection in murine macrophages, amoebae (Acanthamoeba castellanii), nematodes (Caenorhabditis elegans), and wax moth (Galleria mellonella) larvae revealed that theeca1mutants are virulent or hypervirulent at permissive growth temperatures but attenuated at 37°C. Deletion mutants lacking the entireECA1gene were also hypersensitive to the calcineurin inhibitors cyclosporin and FK506 and to ER and osmotic stresses. Aneca1Δcna1Δ mutant lacking both Eca1 and the calcineurin catalytic subunit was more sensitive to high temperature and ER stresses than the single mutants and exhibited reduced survival inC. elegansand attenuated virulence towards wax moth larvae at temperatures that permit normal growth in vitro. Eca1 is likely involved in maintaining ER function, thus contributing to stress tolerance and virulence acting in parallel with Ca2+-calcineurin signaling.
Lack of Immune Responses to
Mycobacterium tuberculosis
DosR Regulon Proteins following
Mycobacterium bovis
BCG Vaccination
Authors: Lin May Young , Geluk Annemieke , Smith Steven G. , Stewart Amanda L. , Friggen Annemieke H. , Franken Kees L. M. C. , Verduyn Marleen J. C. , van Meijgaarden Krista E. , Voskuil Martin I. , Dockrell Hazel M. , Huygen Kris , Ottenhoff Tom H. M. , Klein Michèl R.
Published: May 2007

Mycobacterium bovis
BCG is widely used as a vaccine against tuberculosis (TB), despite its variable protective efficacy. Relatively little is known about the immune response profiles following BCG vaccination in relation to protection against TB. Here we tested whether BCG vaccination results in immune responses to DosR (Rv3133c) regulon-encoded proteins. These so-called TB latency antigens are targeted by the immune system during persistent
Mycobacterium tuberculosis
infection and have been associated with immunity against latent
M. tuberculosis
infection. In silico analysis of the DosR regulon in BCG and
M. tuberculosis
showed at least 97% amino acid sequence homology, with 41 out of 48 genes being identical. Transcriptional profiling of 14 different BCG strains, under hypoxia and nitric oxide exposure in vitro, revealed a functional DosR regulon similar to that observed in
M. tuberculosis
. Next, we assessed human immune responses to a series of immunodominant TB latency antigens and found that BCG vaccination fails to induce significant responses to latency antigens. Similar results were obtained with BCG-vaccinated BALB/c mice. In contrast, responses to latency antigens were observed in individuals with suspected exposure to TB (as indicated by positive gamma interferon responses to TB-specific antigens ESAT-6 and CFP-10) and in mice vaccinated with plasmid DNA encoding selected latency antigens. Since immune responses to TB latency antigens have been associated with control of latent
M. tuberculosis
infection, our findings support the development of vaccination strategies incorporating DosR regulon antigens to complement and improve the current BCG vaccine.
Requirement for YaeT in the Outer Membrane Assembly of Autotransporter Proteins
Authors: Jain Sumita , Goldberg Marcia B.
Published: May 2007

Autotransporters constitute the largest group of secreted proteins in gram-negative bacteria. Autotransporter secretion involves the insertion of a carboxy-terminal beta barrel into and the translocation of an amino-terminal domain across the outer membrane. Here, we demonstrate that secretion of autotransporters from several organisms requires the outer membrane assembly factor YaeT.
The 2004 Olympic Games: physiotherapy services in the Olympic Village polyclinic
Authors: Athanasopoulos Spyridon , Kapreli Eleni , Tsakoniti Aikaterini , Karatsolis Konstantinos , Diamantopoulos Konstantinos , Kalampakas Konstantinos , Pyrros Demetrios G , Parisis Costas , Strimpakos Nikolaos
Published: May 2007

Objective:

First, to document the injuries sustained during the 2004 Olympic Games in a sample of patients visiting the physiotherapy department of the Olympic Village polyclinic. Second, to provide information and data about the physiotherapy services for planning future Olympics and other mass gatherings.

Design:

Observational study.

Setting:

Olympic Village polyclinic.

Participants:

457 patients aged 15–72 years visited the physiotherapy department from 30 July through 30 August.

Results:

The department’s workload was at a peak during the last 15 days of the Olympic Games (periods B and C). The most common injuries were overuse injuries (47.3%). The most common pathology for physiotherapy attendance was myofascial pain/muscle spasm (32.5%), followed by tendinopathy (19.2%) and ligament sprain (18.7%). The most prevalent site of injury was the thigh (21%), followed by the knee (14.1%) and the lumbar spine (13.5%). Most injuries had symptoms of <7 days’ duration. The geographical region with the greatest demand for physiotherapy services was Africa (40.6%). Most patients were athletes (74.8%), although team officials accounted for a considerable number (14%).

Conclusions:

The smallest national teams—especially those from developing countries—were more likely to take advantage of services, probably because the larger teams had their own medical and physiotherapy staff. The characteristics of patients, their sustained injuries and the subsequent treatment varied by the accreditation status of the patients. The physiotherapy department’s workload was dependent on the Olympic Games schedule.
Management of macroscopic haematuria in the emergency department
Authors: Hicks D , Li C-Y
Published: May 2007

Macroscopic haematuria is a commonly seen condition in the emergency department (ED), which has a variety of causes. However, most importantly, macroscopic haematuria has a high diagnostic yield for urological malignancy. 30% of patients presenting with painless haematuria are found to have a malignancy. The majority of these patients can be managed in the outpatient setting. This review of current literature suggests a management pathway that can be used in the ED. A literature search was done using Medline, PubMed and Google. In men aged >60 years, the positive predictive value of macroscopic haematuria for urological malignancy is 22.1%, and in women of the same age it is 8.3%. In terms of the need for follow-up investigation, a single episode of haematuria is equally important as recurrent episodes. Baseline investigation in the ED includes full blood count, urea and electrolyte levels, midstream urine dipstick, β human chorionic gonadotrophin, and formal microscopy, culture and sensitivities. Treatment of macroscopic haematuria aims at RESP—Resuscitation, Ensuring, Safe and Prompt. Indications for admission include clot retention, cardiovascular instability, uncontrolled pain, sepsis, acute renal failure, coagulopathy, severe comorbidity, heavy haematuria or social restrictions. Discharged patients should drink plenty of clear fluids and return for further medical attention if the following occur: clot retention, worsening haematuria despite adequate fluid intake, uncontrolled pain or fever, or inability to cope at home. Follow-up by a urological team should be promptly arranged, ideally within the 2-week cancer referral target.
Comparison of the clinical utility of atrial and B type natriuretic peptide measurement for the diagnosis of systolic dysfunction in a low-risk population
Authors: Galasko Gavin , Collinson Paul O , Barnes Sophie C , Gaze David , Lahiri Arjivit , Senior Roxy
Published: May 2007

Background:Measurement of B type natriuretic peptide and its N terminal prohormone (NTproBNP) can now be performed routinely by automated high-throughput immunoassays. The study compared measurement of NTproBNP with measurement of N terminal pro-atrial natriuretic peptide (NTproANP) for detection of ventricular systolic dysfunction in primary care.

Methods:734 subjects aged >45 years (349 men and 385 women, median age 58 years, range 45–89, interquartile range 51–67 years) from seven representative general practices attended for echocardiography with determination of ejection fraction and completed a questionnaire. Blood samples were collected into gel serum separation tubes (Becton–Dickinson, Franklin Lakes, New Jersey, USA), the serum separated and aliquots stored frozen at −70°C until analyses. Samples were analysed for NTproBNP (Roche Diagnostics, Lewes, UK; coefficient of variation (CV) 3.2–2.4%) and for NTproANP (Biomedica, Vienna, Austria; CV 5.6–10.1%). Echocardiography was used as the diagnostic “gold standard”, with ventricular systolic dysfunction defined as abnormal when there was an ejection fraction of ⩽40%. Patients were dichotomised by ejection fraction from 50% to 30%, and receiver operating characteristic curves constructed and the area under the curve (AUC) compared.

Results:At 40% ejection fraction, NTproANP and NTproBNP showed AUCs of, respectively, 0.738 (0.601–0.875) and 0.973 (0.958–0.989), p<0.004.

Conclusion:NTproBNP is superior to NTproANP for detection of systolic dysfunction.
Abundance, diversity, and resilience of nematode assemblages in forest soilsThis article is one of a selection of papers published in the Special Forum on Towards Sustainable Forestry — The Living Soil: Soil Biodiversity and Ecosystem Function.
Authors: Yeates G.W.
Published: May 2007

Forest litter and soil may contain >10 × 106individual nematodes·m–2and, regionally, >400 species. Root-feeding nematodes may be pathogenic to young plants; microbial-feeding nematodes may increase turnover of the microbial pool; predacious and omnivorous nematodes represent higher trophic levels. The spatial distribution and abundance of nematode species in forests reflect soil type, soil fertility, climate, canopy and understorey plant species, litter depth, forest age, and management. Nematodes may be important in forest nurseries; they occur throughout the rooting depth of forest trees; hyphal-feeding species may influence mycorrhizae; and insect-vectored Bursaphelenchus species are a quarantine risk. Nematode populations interact with those of other soil animals (e.g., mites, tardigrades, enchytraeids, and protozoa). The diversity and abundance of the nematode assemblage make nematodes a useful indicator of soil condition and soil processes. Information available from forest systems suggests that, as long as physical disturbance is minimized and remaining trees or herb layer moderate the microclimate, logging and other forestry operations have only transitory effects on nematode populations. Extreme disturbance, such as bulldozing and slash-and-burn management, can significantly reduce nematode abundance and diversity. In contrast, management that enhances growth of understorey or herb layer can stimulate nematode populations. Each of these changes can be related to changes in food resource availability and environmental conditions, such as soil temperature and moisture. Although details of soil nematode contributions to nutrient processes in forest soils are sparse, that their populations are maintained through cycles of moderate management practices suggest that their beneficial contributions will also be maintained.
Scots pine bait seedling performance and root colonizing ectomycorrhizal fungal community dynamics before and during the 4 years after forest clear-cut logging
Authors: Heinonsalo Jussi , Koskiahde Ilpo , Sen Robin
Published: May 2007

The aim of the study was an integrated monitoring of Scots pine ( Pinus sylvestris L.) bait seedling performance and ectomycorrhizal fungal community dynamics in a Scots pine dominated stand one growing season before and over four seasons after forest clear-cut logging. The effects of planting location and time were assessed in relation to subsequent seedling performance and ectomycorrhizal diversity. Application of advanced regeneration, where seedlings were planted one growing season before the clear-cut event, resulted in increased seedling growth in the clear-cut area over the subsequent 4 years. However, counterparts planted in the interface zone in 1997, between the future uncut stand and the clear-cut area, exhibited poorer growth compared with those planted after clear-cut harvesting. The interface zone was generally richest in ectomycorrhizal diversity, and this was confirmed using complementary morphotyping and rDNA-based identification methods. Large numbers of ectomycorrhizal types were present on Scots pine seedling roots and instead of detecting dramatic changes in total number of types, species composition changes could be better related to changes in exploratory types of ectomycorrhizas with a trend towards less rhizomorphic types in the clear-cut treatment compared with the control forest. Changes in the community structure are presumably influenced by changing environmental conditions in the site.
Frost hollows of the boreal forest as extreme environments for black spruce tree growth
Authors: Dy Goulwen , Payette Serge
Published: May 2007

An extensive survey of spruce growth forms was conducted in frost hollows of the Parc national des Grands-Jardins located in the highlands of the Charlevoix region (Quebec). Frost hollows studied were situated within lichen woodlands, which are a favourable environment for the formation of cold air masses. The mean number of frosts recorded 1 m aboveground during the growing seasons of 1997–2002 indicates that there is no frost-free period in frost hollows. Based on the records of minimum temperature in two frost hollows, the critical threshold for frost-ring formation is a nocturnal temperature below 0 °C for 6.4 h with a climax at around –5.7 °C, i.e., at a cooling rate of 1.78 °C/h under the freezing point for at least 3.2 h. Frequent and severe nocturnal frosts slow down the colonization of black spruce in frost hollows, and are at the origin of the inverted tree line that surrounds frost hollows. Mean stem height of black spruce in frost hollows is 1.97 m ± 2.15. A comparative analysis of aerial photographs between 1950 and 1996 showed a 34% reduction in frost hollow area due to the progressive colonization of black spruce. Massive tree establishment occurred in frost hollows between 1970 and 1980 because of the reduced frequency of freezing temperatures during the growing season.
Regeneration differences between fire and clearcut logging in southeastern Labrador: a multiple spatial scale analysis
Authors: Elson Leanne T. , Simon Neal P.P. , Kneeshaw Daniel
Published: May 2007

To determine scale-specific effects of disturbance type, soil, and topography on regenerating plant species, we compared regeneration in 10- and 50-year-old clearcuts and burns in southeastern Labrador. Data were analyzed at three scales of resolution: subplot (5 m2), plot (398 m2), and site (3.89 ha). The influence of topography and edaphic factors, and the variance explained by these environmental variables, increased with scale. Disturbance type and year were important across all three scales, but soil and topography were most important at the site scale. Regeneration was more abundant within clearcuts, notably black spruce ( Picea mariana (Mill.) BSP) and balsam fir ( Abies balsamea (L.) Mill.). Disturbance type had a greater influence on plant species composition than disturbance age as plant communities remained dissimilar within 50 years after disturbance. Because regeneration is often low after fire in southeastern Labrador, it may be undesirable for forest harvesting to mimic the effects of fire at the scales we evaluated.
Genetic variability at allozyme markers in sycamore (Acer pseudoplatanus) populations from northwestern Italy
Authors: Belletti P. , Monteleone I. , Ferrazzini D.
Published: May 2007

Genetic diversity and differentiation of 12 native populations of sycamore ( Acer pseudoplatanus L.) from northwestern Italy were investigated by means of variation detected in 10 polymorphic isozyme systems encoded by 16 loci. The trees showed relatively large genetic variability (mean number of alleles per locus = 2.78, effective number of alleles per locus = 1.47, percentage of polymorphic loci = 96.9, expected heterozygosity = 0.280) but small interpopulational variation (FST= 0.019), suggesting the presence of a single gene pool. A slight excess of heterozygotes was found, and the overall inbreeding coefficient (FIS) was –0.038. There was a positive correlation between the age of the individuals sampled and heterozygosity, suggesting the occurrence of natural selection against homozygotes. No significant correlation was detected between genetic and geographic distances of populations, confirming the lack of any barriers to gene flow. Estimate of the mean effective number of migrants exchanged between populations was 4.399, based on the private alleles method. The contribution of the results in relation to terms of the most appropriate strategies to preserve genetic variability of sycamore and to collect forest reproductive material is discussed.
CYCLOTRON RESONANCE IN MEGAGAUSS FIELDS
Authors: von ORTENBERG MICHAEL
Published: May 2007

A review of magneto-optical experiments on semiconductor structures in megagauss fields is presented, featuring both the single-turn coil-generator and the explosive flux compression. Special emphasis is laid on the transient character of the fields resulting in unexpected and sophisticated response of the materials investigated.
RESONANT INTERACTION BETWEEN A QUANTUM DOT AND A NARROWBAND LASER: SPECTROSCOPY AND OPTICAL PUMPING OF A SINGLE SPIN
Authors: KRONER M. , SEIDL S. , GERARDOT B. D. , Biedermann B. , Badolato A. , Petroff P. M. , Karrai K. , Warburton R. J.
Published: May 2007

Recently, a technique has been developed for performing laser spectroscopy on single self-assembled quantum dots. A summary is presented here of spectroscopy results concerning the charge- and magnetic-field dependent energies and selection rules of the fundamental exciton. In addition, it is also shown how the resonant interaction of a laser with a singly-charged dot can be exploited to pump the electron into one of the spin states. This involves applying a small magnetic field and an appropriate bias in order to suppress spin relaxation through the hyperfine interaction and through co-tunneling processes, respectively.
COHERENT SPIN DYNAMICS OF ELECTRONS IN II-VI SEMICONDUCTOR QUANTUM WELLS
Authors: YAKOVLEV D. R. , ZHUKOV E. A. , BAYER M. , KARCZEWSKI G. , WOJTOWICZ T. , KOSSUT J.
Published: May 2007

Coherent spin dynamics of electrons and holes is studied experimentally in CdTe/Cd 0.78 Mg 0.22 Te quantum wells with a two-dimensional electron gas of low density. A picosecond pump-probe Kerr rotation and time-resolved polarized photoluminescence detected by a streak camera are used as experimental techniques. Strong Coulomb interaction between electrons and holes, which results in large binding energies of neutral and negatively charged excitons (trions), allows selective addressing of exciton and trion states with resonant optical excitation. Spin dephasing time of electrons up to 30 ns is achieved at a low temperature of 1.9 K and in a zero magnetic field limit. It decreases for higher lattice temperatures and with increase of excitation density. Spin relaxation times for exciton of 65 ps and trion of 25 ps have been measured under quasi-resonant excitation of excitons.
MICROWAVE RESONANCE STUDY OF MELTING IN HIGH MAGNETIC FIELD WIGNER SOLID
Authors: CHEN YONG P. , SAMBANDAMURTHY G. , ENGEL L. W. , TSUI D. C. , PFEIFFER L. N. , WEST K. W.
Published: May 2007

Wigner solids in two-dimensional electron systems in high magnetic field B exhibit a striking, microwave or rf resonance, that is understood as a pinning mode. The temperature, Tm, above which the resonance is absent, is interpreted as the melting temperature of the solid. Studies of Tm for many B and many sample densities n show that Tm is a function of the Landau level filling ν alone for a given sample. This indicates that quantum mechanics figures importantly in the melting. Tm also appears to be increased by larger sample disorder.
CAPACITIVE CONTACTS: MAKING FOUR-POINT CHARACTERIZATIONS WITHOUT OHMIC CONTACTS
Authors: ISIK N. , BICHLER M. , ROTH S. , GRAYSON M.
Published: May 2007

Four-point measurements are carried out on a Hall bar using specially designed capacitive contacts, reproducing the transport characteristics Rxx measured using standard ohmic contacts. All Rxx measurements using various combinations of ohmic and capacitive contacts are in quantitative agreement, with a calibrated scaling factor arising because of the device and measurement setup capacitances. Also amplitude and phase measurements represented with the Bode plots for all combinations of ohmic and capacitive contacts are carried out and the results compare favorably with our circuit analysis.
THE OBSERVATION OF THE MAGNETIC PHONON MODE IN MODULATION DOPED DILUTE Cd1-xMnxTe/Cd1-yMgyTe QUANTUM WELL STRUCTURE
Authors: TUNG LI-CHUN , WANG YONG-JIE , KARCZEWSKI GRZEGORZ
Published: May 2007

The CdMnTe/CdMgTe quantum wells have been a focus of interests for its novel magnetic and transport properties and applications in spintronics. We have carried out a systematic study over a series of CdMnTe quantum wells with a range of Mn concentration (0%–3.9%) and modulation doping. Far-infrared transmission spectra have revealed several new infrared-active modes which are both magnetic-field and Mn -concentration dependent. The absorption mode near 125cm-1 (B1) is possibly resulted from the magnetic-order-dependent phonon mode due to an ion-position dependent spin Hamiltonian, while the other two (M1 & M2) may be related to the CdTe optical phonon modes.
PROBING THE SCATTERING POTENTIAL OF N-IMPURITIES IN GaAs BY MAGNETO-TUNNELING
Authors: ALLISON G. , PATANÈ A. , ENDICOTT J. , EAVES L. , MORI N. , KOZLOVA N. , FREUDENBERGER J. , MIURA N. , MAUDE D. K. , HOPKINSON M.
Published: May 2007

We study the strong effect of a small concentration (1 part per 1000) of randomly distributed N-resonant scatterers on the quantized Landau level states of a GaAs quantum well. Our magneto-tunneling spectroscopy measurements allow us to probe the resonant and non-resonant component of the N-related scattering potential.