bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial impulse responses from a flexible baffled circular piston
Authors: Aarts Ronald M. , Janssen Augustus J. E. M.
Published: May 2011

The theory of orthogonal polynomial (Zernike) expansions of functions on a disk, as used in the diffraction theory of optical aberrations, is applied to obtain (semi-) analytical expressions for the spatial impulse responses arising from a non-uniformly moving, baffled, circular piston. These expressions are in terms of the expansion coefficients of the non-uniformity and the responses of the orthogonal expansion functions. The latter impulse responses have a closed form as finite series involving the Legendre functions and the sinc function. The method is compared with a similar method, proposed by P. R. Stepanishen [J. Acoust. Soc. Am. 70, 1176–1181 (1981)] where zeroth order orthogonal Bessel functions, rather than Zernike polynomials, are used as expansion functions.
Automatic estimation of the first subglottal resonance
Authors: Arsikere Harish , Lulich Steven M. , Alwan Abeer
Published: May 2011

This letter focuses on the automatic estimation of the first subglottal resonance (Sg1). A database comprising speech and subglottal data of native American English speakers and bilingual Spanish/English speakers was used for the analysis. Data from 11 speakers (five males and six females) were used to derive an empirical relation among the first formant frequency, fundamental frequency, and Sg1. Using the derived relation, Sg1 was automatically estimated from voiced sounds in English and Spanish sentences spoken by 22 different speakers (11 males and 11 females). The error in estimating Sg1 was less than 50 Hz, on average.
Broadband trailing edge noise from a sharp-edged strut
Authors: Moreau Danielle J. , Brooks Laura A. , Doolan Con J.
Published: May 2011

This paper presents experimental data concerning the flow and noise generated by a sharp-edged flat plate at low-to-moderate Reynolds number (Reynolds number based on chord of 2.0 × 105 to 5.0 × 105). The data are used to evaluate a variety of semi-empirical trailing edge noise prediction methods. All were found to under-predict noise at lower frequencies. Examination of the velocity spectra in the near wake reveals that there are energetic velocity fluctuations at low frequency about the trailing edge. A semi-empirical model of the surface pressure spectrum is derived for predicting the trailing edge noise at low-to-moderate Reynolds number.
The relation between the waveguide invariant, multipath impulse response, and ray cycles
Authors: Harrison Chris H.
Published: May 2011

The waveguide invariant, β, that manifests itself as interference fringes or “striations” in a plot of frequency vs source–receiver separation, is usually thought of as a modal phenomenon. This paper shows that striations can be explained simply through the variation of the eigenray arrival times with range, in short, the variation of the multipath impulse response. It is possible to calculate β for a number of sound speed profiles analytically and to find what β depends on, why it switches from one value to another, how it depends on source–receiver depth, how it depends on variable bathymetry, and how smooth the sound speed profile needs to be for clear fringes. The analytical findings are confirmed by calculating striation patterns numerically starting from eigenray travel times in various stratified environments. Most importantly the approach throws some light on what can be deduced from β alone and the likelihood and utility of striations in reverberation.
Bat noseleaf model: Echolocation function, design considerations, and experimental verification
Authors: Kuc Roman
Published: May 2011

This paper describes a possible bat noseleaf echolocation function that improves target elevation resolution. Bats with a protruding noseleaf can rotate the lancet to act as an acoustic mirror that reflects the nostril emission, modeled as a virtual nostril that produces a delayed emission. The cancellation of the nostril and virtual nostril components at a target produces a sharp spectral notch whose frequency location relates to target elevation. This notch can be observed directly from the swept-frequency emission waveform, suggesting cochlear processing capabilities. Physical acoustic principles indicate the design considerations and trade-offs that a bat can accomplish through noseleaf shape and emission characteristics. An experimental model verifies the analysis and exhibits an elevation versus notch frequency sensitivity of approximately 1°/kHz.
The psychophysics of absolute threshold and signal duration: A probabilistic approach
Authors: Meddis Ray , Lecluyse Wendy
Published: May 2011

The absolute threshold for a tone depends on its duration; longer tones have lower thresholds. This effect has traditionally been explained in terms of “temporal integration” involving the summation of energy or perceptual information over time. An alternative probabilistic explanation of the process is formulated in terms of simple equations that predict not only the time/duration dependence but also the shape of the psychometric function at absolute threshold. It also predicts a tight relationship between these two functions. Measurements made using listeners with either normal or impaired hearing show that the probabilistic equations adequately fit observed threshold-duration functions and psychometric functions. The mathematical formulation implies that absolute threshold can be construed as a two-valued function: (a) gain and (b) sensory threshold, and both parameters can be estimated from threshold-duration data. Sensorineural hearing impairment is sometimes associated with a smaller threshold/duration effect and sometimes with steeper psychometric functions. The equations explain why these two effects are expected to be linked. The probabilistic approach has the potential to discriminate between hearing deficits involving gain reduction and those resulting from a raised sensory threshold.
Ray-based description of shadow zone arrivals
Authors: Virovlyansky A. L. , Kazarova A. Yu , Lyubavin L. Ya
Published: May 2011

Field experiments and numerical simulation show that due to scattering from internal-wave-induced sound speed perturbations, the sound energy at megameter ranges penetrates well below the unperturbed timefront, i.e., into the geometric shadow. Shadow zone arrivals form continuations of cusps of the timefront. In the present paper, this effect is analyzed using a stochastic ray theory derived for statistical description of chaotic rays. Probability density functions for parameters of perturbed rays, including those penetrating into the shadow zone, are evaluated analytically. This made it possible to derive analytical estimates for a vertical extent of shadow zone arrivals and for a coarse-grained distribution of sound energy in the shadow zone. It is shown that the lengths of cusp extensions into the shadow zone grow with range r as r1/2. A known estimate for the spread of timefront segments in the presence of internal waves is applied for obtaining a criterion of nonoverlapping of the cusp continuations. These results are derived for steep rays whose grazing angles at the sound channel axis exceed 5°.
Hearing thresholds of a harbor porpoise (Phocoena phocoena) for sweeps (1–2 kHz and 6–7 kHz bands) mimicking naval sonar signals
Authors: Kastelein Ronald A. , Hoek Lean , de Jong Christ A. F.
Published: May 2011

The distance at which active naval sonar signals can be heard by harbor porpoises depends, among other factors, on the hearing thresholds of the species for those signals. Therefore the hearing sensitivity of a harbor porpoise was determined for 1 s up-sweep and down-sweep signals, mimicking mid-frequency and low-frequency active sonar sweeps (MFAS, 6–7 kHz band; LFAS, 1–2 kHz band). The 1–2 kHz sweeps were also tested with harmonics, as sonars sometimes produce these as byproducts of the fundamental signal. The hearing thresholds for up-sweeps and down-sweeps within each sweep pair were similar. The 50% detection threshold sound pressure levels (broadband, averaged over the signal duration) of the 1–2 kHz and 6–7 kHz sweeps were 75 and 67 dB re 1 μPa2, respectively. Harmonic deformation of the 1–2 kHz sweeps reduced the threshold to 59 dB re 1 μPa2. This study shows that the presence of harmonics in sonar signals can increase the detectability of a signal by harbor porpoises, and that tonal audiograms may not accurately predict the audibility of sweeps. LFAS systems, when designed to produce signals without harmonics, can operate at higher source levels than MFAS systems, at similar audibility distances for porpoises.
Outdoor ground impedance models
Authors: Attenborough Keith , Bashir Imran , Taherzadeh Shahram
Published: May 2011

Many models for the acoustical properties of rigid-porous media require knowledge of parameter values that are not available for outdoor ground surfaces. The relationship used between tortuosity and porosity for stacked spheres results in five characteristic impedance models that require not more than two adjustable parameters. These models and hard-backed-layer versions are considered further through numerical fitting of 42 short range level difference spectra measured over various ground surfaces. For all but eight sites, slit-pore, phenomenological and variable porosity models yield lower fitting errors than those given by the widely used one-parameter semi-empirical model. Data for 12 of 26 grassland sites and for three beech wood sites are fitted better by hard-backed-layer models. Parameter values obtained by fitting slit-pore and phenomenological models to data for relatively low flow resistivity grounds, such as forest floors, porous asphalt, and gravel, are consistent with values that have been obtained non-acoustically. Three impedance models yield reasonable fits to a narrow band excess attenuation spectrum measured at short range over railway ballast but, if extended reaction is taken into account, the hard-backed-layer version of the slit-pore model gives the most reasonable parameter values.
Predicting the intelligibility of vocoded and wideband Mandarin Chinese
Authors: Chen Fei , Loizou Philipos C.
Published: May 2011

Due to the limited number of cochlear implantees speaking Mandarin Chinese, it is extremely difficult to evaluate new speech coding algorithms designed for tonal languages. Access to an intelligibility index that could reliably predict the intelligibility of vocoded (and non-vocoded) Mandarin Chinese is a viable solution to address this challenge. The speech-transmission index (STI) and coherence-based intelligibility measures, among others, have been examined extensively for predicting the intelligibility of English speech but have not been evaluated for vocoded or wideband (non-vocoded) Mandarin speech despite the perceptual differences between the two languages. The results indicated that the coherence-based measures seem to be influenced by the characteristics of the spoken language. The highest correlation (r = 0.91–0.97) was obtained in Mandarin Chinese with a weighted coherence measure that included primarily information from high-intensity voiced segments (e.g., vowels) containing F0 information, known to be important for lexical tone recognition. In contrast, in English, highest correlation was obtained with a coherence measure that included information from weak consonants and vowel/consonant transitions. A band-importance function was proposed that captured information about the amplitude envelope contour. A higher modulation rate (100 Hz) was found necessary for the STI-based measures for maximum correlation (r = 0.94–0.96) with vocoded Mandarin and English recognition.
Investigating temporal asymmetry using masking period patterns and models of peripheral auditory processing
Authors: Lentz Jennifer J. , Shen Yi
Published: May 2011

Two experiments were conducted in conjunction with modeling to evaluate the role of peripheral nonlinearity and neural adaptation in the perception of temporally asymmetric sounds. In both experiments, maskers were broadband noises amplitude modulated with ramped and damped exponential modulators that repeated at 40 Hz. Masking period patterns (MPPs) were constructed by measuring detection threshold of a 5-ms, 1000-Hz tone burst as function of the signal’s onset delay. Experiment I showed that varying modulator half-life from 1 to 16 ms led to differences in the damped and the ramped MPPs that were largest at the short half-lives and diminished at the longer half-lives. When masker level was varied (experiment II), the largest difference between ramped and damped MPPs occurred at moderate stimulus levels. Two peripheral auditory models were evaluated, one a simple auditory filter followed by a power-law nonlinearity and another, a model of auditory nerve processing [J. Acoust. Soc. Am. 126, 2390–2412 (2009)] that includes neural adaptation. Neither models predicted differences between the ramped and damped MPPs, providing indirect support that the central auditory system has a role in perceptual temporal asymmetry.
Identification of auditory distance cues by zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus)
Authors: Radziwon Kelly E. , Welch Thomas E. , Cone Jarrod P. , Dent Micheal L.
Published: May 2011

The present study examined auditory distance perception cues in a non-territorial songbird, the zebra finch (Taeniopygia guttata), and in a non-songbird, the budgerigar (Melopsittacus undulatus). Using operant conditioning procedures, three zebra finches and three budgerigars were trained to identify 1- (Near) and 75-m (Far) recordings of three budgerigar contact calls, one male zebra finch song, and one female zebra finch call. Once the birds were trained on these endpoint stimuli, other stimuli were introduced into the operant task. These stimuli included recordings at intermediate distances and artificially altered stimuli simulating changes in overall amplitude, high-frequency attenuation, reverberation, and all three cues combined. By examining distance cues (amplitude, high-frequency attenuation, and reverberation) separately, this study sought to determine which cue was the most salient for the birds. The results suggest that both species could scale the stimuli on a continuum from Near to Far and that amplitude was the most important cue for these birds in auditory distance perception, as in humans and other animals.
Improved Learning in a Large-Enrollment Physics Class
Authors: Deslauriers Louis , Schelew Ellen , Wieman Carl
Published: May 2011

Encouraging active engagement results in enhanced learning.
Polarized
notum
Activation at Wounds Inhibits Wnt Function to Promote Planarian Head Regeneration
Authors: Petersen Christian P. , Reddien Peter W.
Published: May 2011

Local detection of tissue polarity results in selective feedback inhibition of signaling at posterior-facing wounds.
Arts and the Dreaming Mind
Brainwave 2011
Dreams

Tim McHenry, Producer

Rubin Museum of Art, New York, 7 February to 29 April 2011. www.rmanyc.org/brainwave
Authors: Requarth Tim , Crist Meehan
Published: May 2011

Exploring the interplay between neuroscience and the arts, this year's Brainwave Festival was centered on dreaming.
Our Caring Neurons
Braintrust
What Neuroscience Tells Us About Morality

by Patricia S. Churchland

Princeton University Press, Princeton, NJ, 2011. 285 pp. $24.95, £16.95. ISBN 9780691137032.
Authors: Mathis Richard S.
Published: May 2011

Churchland approaches the question of what grounds morality through a consideration of the neurobiological foundations of human sociability.
The Cost of Being Male
Authors: Parsch John
Published: May 2011

Mitochondrial mutations influence nuclear gene expression more in male
Drosophila
than in females.
Scientific Link-Up Yields ‘Control Panel’ for Networks
Authors: Cho Adrian
Published: May 2011

A trio of physicists has found a way to determine the smallest number of nodes that must be externally controlled to force a given network from any initial state to any desired final state.
The Emerging Race to Cure HIV Infections
Authors: Cohen Jon
Published: May 2011

Timothy Ray Brown's startling fate has pushed to the front a daunting research challenge that long seemed a fool's errand
A Peptide-Based Target Screen Implicates the Protein Kinase CK2 in the Global Regulation of Caspase Signaling
Authors: Duncan James S. , Turowec Jacob P. , Duncan Kelly E. , Vilk Greg , Wu Chenggang , Lüscher Bernhard , Li Shawn S.-C. , Gloor Greg B. , Litchfield David W.
Published: May 2011

Phosphorylation of caspase substrates by the protein kinase CK2 may underlie its role in tumorigenesis.
PP2A Phosphatases: The “On-Off” Regulatory Switches of Brassinosteroid Signaling
Authors: Di Rubbo Simone , Irani, Niloufer G. , Russinova Eugenia
Published: May 2011

Protein phosphatase 2A acts as both a positive and negative regulator of brassinosteroid signaling, depending on where in the pathway the phosphatase acts.
Light Sensing with Vitamin B
12
Authors: Gough Nancy R.
Published: May 2011

Bacteria use B
12
as a light-sensitive switch to control DNA binding of a transcriptional repressor.
Nuclear PI3Kβ
Authors: Foley John F.
Published: May 2011

To promote cell survival, the β isoform of phosphoinositide 3-kinase must be present in the nucleus.
Priming the Intracellular Armory
Authors: Hurtley Stella M.
Published: May 2011

Guanylate-binding proteins coordinately regulate oxidative and autophagic responses to intracellular bacteria.
Dissemination of Clinical Isolates of Klebsiella oxytoca Harboring CMY-31, VIM-1, and a New OXY-2-Type Variant in the Community
Authors: Tsakris Athanassios , Poulou Aggeliki , Markou Fani , Pitiriga Vassiliki , Piperaki Evangelia-Theophano , Kristo Ioulia , Pournaras Spyros
Published: May 2011

The aim of the present study was to investigate the epidemiological link of multidrug-resistant
Klebsiella oxytoca
isolates causing community-onset infections among patients attending our outpatient department and to investigate the underlying resistance mechanisms. The isolates were tested by agar dilution MICs, phenotypic carbapenemase testing, enterobacterial repetitive intergenic consensus-PCR, and pulsed-field gel electrophoresis (PFGE). PCR assays and nucleotide sequencing were employed for the identification of
bla
gene types and the mapping of the integron-containing metallo-β-lactamase (MBL) gene. During the study period (January 2005 to April 2007), nine broad-spectrum cephalosporin-resistant
K. oxytoca
clinical isolates were prospectively collected from separate outpatients with urinary tract infections. In all cases, the patients had been hospitalized or exposed to health care facilities during the preceding year. Molecular typing revealed that all isolates belonged to the same
K. oxytoca
clonal type, which contained five PFGE subtypes. A novel chromosomal OXY-2 β-lactamase type variant (OXY-2-9) was detected in all isolates, but no mutations in the promoter region justifying
bla
OXY
gene overproduction were detected. In addition, all isolates harbored the plasmidic CMY-31 (LAT-4) AmpC cephalosporinase, while three of them harbored VIM-1 MBL in a class 1 integron structure. This is the first study to present the dissemination in the community of multidrug-resistant
K. oxytoca
isolates causing extrahospital infections.
JNJ-Q2, a New Fluoroquinolone with Potent
In Vitro
Activity against Staphylococcus aureus, Including Methicillin- and Fluoroquinolone-Resistant Strains
Authors: Farrell David J. , Liverman Lisa C. , Biedenbach Douglas J. , Jones Ronald N.
Published: May 2011

JNJ-Q2 is a broad-spectrum bactericidal fluoroquinolone with potent activity against Gram-positive and -negative pathogens. In this study, the
in vitro
activity of JNJ-Q2 was evaluated against 511 selected
Staphylococcus aureus
samples isolated in 2008-2009 from patients with acute bacterial skin and skin structure infections in the United States by using reference methodology. JNJ-Q2 was the most potent fluoroquinolone tested overall (MIC
50
and MIC
90
, 0.12 and 0.5 μg/ml, respectively) and against methicillin- and fluoroquinolone-resistant subgroups in direct comparisons to moxifloxacin, levofloxacin, and ciprofloxacin (each being ≥16-fold less potent than JNJ-Q2).
Implication of the NorB Efflux Pump in the Adaptation of Staphylococcus aureus to Growth at Acid pH and in Resistance to Moxifloxacin
Authors: Truong-Bolduc Que Chi , Bolduc Gilles R. , Okumura Ryo , Celino Brian , Bevis Jennifer , Liao Chun-Hsing , Hooper David C.
Published: May 2011

Staphylococcus aureus
is an important pathogen that adapts and survives in low-pH environments. One component of this adaptation involves the regulation of genes encoding bacterial transporters that could affect response to antibiotics under these conditions. We previously demonstrated that the transcriptional regulator MgrA in its phosphorylated form (MgrA-P) represses the expression of
norB
, encoding the NorB multidrug resistance efflux pump. In this study, we focused on changes in the expression of
mgrA
at the transcriptional and posttranslational levels, following a shift from pH 7.0 to pH 4.5. We then correlated those changes with modifications in transcript levels of
norB
and to resistance to moxifloxacin, a substrate of NorB. At pH 4.5,
S. aureus
MgrA increased 2-fold and MgrA-P decreased 4-fold, associated with an 8-fold increase in
norB
transcripts and a 6-fold reduction in bacterial killing by moxifloxacin, and the phenomenon was dependent on intact
mgrA
. Taken together, these new data showed that phosphoregulation of MgrA at low pH reverses its repression of
norB
expression, conferring resistance to moxifloxacin.
Characteristic Resistance Mechanism of
Mycobacterium tuberculosis
to DC-159a, a New Respiratory Quinolone
Authors: Sekiguchi Jun-ichiro , Disratthakit Areeya , Maeda Shinji , Doi Norio
Published: May 2011

A G88C mutation in GyrA is one of the key alterations by which
Mycobacterium tuberculosis
mutants acquire DC-159a resistance
in vitro
. A novel double mutation in GyrA, G88C D94H, conferred high DC-159a resistance. Different mutation patterns in GyrA were demonstrated for DC-159a-resistant mutants and quinolone-resistant multidrug-resistant (QR-MDR)
M. tuberculosis
isolates, with a mutation either at position 90 or 94 and double mutations at 90 and 91 or at 90 and 94. DC-159a might be promising for QR
M. tuberculosis
treatment.
Trends towards Lower Antimicrobial Susceptibility and Characterization of Acquired Resistance among Clinical Isolates of Brachyspira hyodysenteriae in Spain
Authors: Hidalgo Álvaro , Carvajal Ana , Vester Birte , Pringle Märit , Naharro Germán , Rubio Pedro
Published: May 2011

The antimicrobial susceptibility of clinical isolates of
Brachyspira hyodysenteriae
in Spain was monitored, and the underlying molecular mechanisms of resistance were investigated. MICs of tylosin, tiamulin, valnemulin, lincomycin, and tylvalosin were determined for 87
B. hyodysenteriae
isolates recovered from 2008 to 2009 by broth dilution. Domain V of the 23S rRNA gene and the ribosomal protein L3 gene were sequenced in 20 isolates for which the tiamulin MIC was ≥4 μg/ml, presenting decreased susceptibility, and in 18 tiamulin-susceptible isolates (MIC ≤ 0.125 μg/ml), and all isolates were typed by multiple-locus variable-number tandem repeats analysis. A comparison with antimicrobial susceptibility data from 2000 to 2007 showed an increase in pleuromutilin resistance over time, doubling the number of isolates with decreased susceptibility to tiamulin. No alteration in susceptibility was detected for lincomycin, and the MIC of tylosin remained high (MIC
50
> 128 μg/ml). The decreased susceptibility to tylosin and lincomycin can be explained by mutations at position A2058 of the 23S rRNA gene (
Escherichia coli
numbering). A2058T was the predominant mutation, but A2058G also was found together with a change of the neighboring base pair at positions 2057 to 2611. The role of additional point mutations in the vicinity of the peptidyl transferase center and mutations in the L3 at amino acids 148 and 149 and their possible involvement in antimicrobial susceptibility are considered. An association between G2032A and high levels of tiamulin and lincomycin MICs was found, suggesting an increasing importance of this mutation in antimicrobial resistance of clinical isolates of
B. hyodysenteriae
.
Prevalence and Significance of Plasmid Maintenance Functions in the Virulence Plasmids of Pathogenic Bacteria
Authors: Sengupta Manjistha , Austin Stuart
Published: May 2011

Virulence functions of pathogenic bacteria are often encoded on large extrachromosomal plasmids. These plasmids are maintained at low copy number to reduce the metabolic burden on their host. Low-copy-number plasmids risk loss during cell division. This is countered by plasmid-encoded systems that ensure that each cell receives at least one plasmid copy. Plasmid replication and recombination can produce plasmid multimers that hinder plasmid segregation. These are removed by multimer resolution systems. Equitable distribution of the resulting monomers to daughter cells is ensured by plasmid partition systems that actively segregate plasmid copies to daughter cells in a process akin to mitosis in higher organisms. Any plasmid-free cells that still arise due to occasional failures of replication, multimer resolution, or partition are eliminated by plasmid-encoded postsegregational killing systems. Here we argue that all of these three systems are essential for the stable maintenance of large low-copy-number plasmids. Thus, they should be found on all large virulence plasmids. Where available, well-annotated sequences of virulence plasmids confirm this. Indeed, virulence plasmids often appear to contain more than one example conforming to each of the three system classes. Since these systems are essential for virulence, they can be regarded as ubiquitous virulence factors. As such, they should be informative in the search for new antibacterial agents and drug targets.
TREM-1 Amplifies Corneal Inflammation after Pseudomonas aeruginosa Infection by Modulating Toll-Like Receptor Signaling and Th1/Th2-Type Immune Responses
Authors: Wu Minhao , Peng Anping , Sun Mingxia , Deng Qiuchan , Hazlett Linda D. , Yuan Jin , Liu Xialin , Gao Qianying , Feng Lianqiang , He Junfang , Zhang Ping , Huang Xi
Published: May 2011

As a novel family of cell surface receptors, triggering receptors expressed on myeloid cells (TREMs) play an important role in inflammatory responses. However, the role of TREMs in the ocular immune system remains unknown. In this study, we examined the expression and function of TREM-1 inPseudomonas aeruginosakeratitis, one of the most common sight-threatening ocular diseases. TREM-1 was significantly increased in human corneas afterP. aeruginosainfection. Consistent with TREM-1 expression at the human ocular surface, TREM-1 levels (mRNA and protein) were also elevated in the infected corneas of C57BL/6 (B6) mice at 1, 3, and 5 days postinfection. To determine whether TREM-1 dictates the outcome ofP. aeruginosakeratitis in susceptible mice, TREM-1 signaling in B6 mice was blocked with a soluble mTREM-1/Fc fusion protein. The results indicated that blockade of TREM-1 reduced the severity of corneal disease, polymorphonuclear neutrophil infiltration, Th1/proinflammatory cytokine expression and Toll-like receptor (TLR) activation but enhanced the production of Th2 cytokines, murine β-defensin 2 (mBD2), single Ig interleukin-1R-related molecule (SIGIRR), and ST2. Furthermore, we also used agonistic anti-mTREM-1 antibody to activate TREM-1 signaling in B6 mice and found that TREM-1 activation resulted in worsened disease and earlier corneal perforation in infected B6 mouse corneas and elevated production of proinflammatory cytokines and TLR signaling molecules but reduced expression of mBD2, SIGIRR, and ST2. To the best of our knowledge, this study provides the first evidence that TREM-1 functions as an inflammatory amplifier inP. aeruginosakeratitis by modulating TLR signaling and Th1/Th2 responses.
Protective Role of Akt2 in Salmonella enterica Serovar Typhimurium-Induced Gastroenterocolitis
Authors: Kum Winnie W. S. , Lo Bernard C. , Yu Hong B. , Finlay B. Brett
Published: May 2011

TheSalmonellaeffector protein SopB has previously been shown to induce activation of Akt and protect epithelial cells from apoptosisin vitro. To characterize the role of Akt2 in host defense againstSalmonella entericaserovar Typhimurium infection, wild-type (WT) mice and mice lacking Akt2 (Akt2 knockout [KO] mice) were infected using aSalmonellaacute gastroenteritis model. Infected Akt2 KO mice showed a more pronounced morbidity and mortality associated with higher bacterial loads in the intestines and elevated levels of proinflammatory cytokines, including tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), and MCP-1, in the colons at 1 day postinfection compared to those shown in WT mice. Histopathological assessment and immunohistochemical analysis of cecal sections at 1 day postinfection revealed more severe inflammation and higher levels of neutrophil infiltration in the ceca of Akt2 KO mice. Flow cytometry analysis further confirmed an increase in the recruitment of Gr-1+CD11b+neutrophils and F4/80+CD11b+macrophages in the intestines of infected Akt2 KO mice. Additionally, enhanced levels of annexin V+and terminal transferase dUTP nick end labeling-positive (TUNEL+) apoptotic cells in the intestines of infected Akt2 KO mice were also observed, indicating that Akt2 plays an essential role in protection against apoptosis. Finally, the differences in bacterial loads and cecal inflammation in WT and Akt2 KO mice infected with WTSalmonellawere abolished when these mice were infected with thesopBdeletion mutant, indicating that SopB may play a role in protecting the mice fromSalmonellainfection through the activation of Akt2. These data demonstrate a definitive phenotypic abnormality in the innate response in mice lacking Akt2, underscoring the important protective role of Akt2 inSalmonellainfection.
Burkholderia pseudomallei-Induced Expression of a Negative Regulator, Sterile-α and Armadillo Motif-Containing Protein, in Mouse Macrophages: a Possible Mechanism for Suppression of the MyD88-Independent Pathway
Authors: Pudla M. , Limposuwan K. , Utaisincharoen P.
Published: May 2011

Burkholderia pseudomallei
, a causative agent of melioidosis, is a Gram-negative facultative intracellular bacterium that can survive and multiply in macrophages. Previously, we demonstrated that
B. pseudomallei
failed to activate gene expression downstream of the MyD88-independent pathway, particularly the expression of beta interferon (IFN-β) and inducible nitric oxide synthase (iNOS), leading to the inability of macrophages to kill this bacterium. In the present report, we extended our study to show that
B. pseudomallei
was able to activate sterile-α and Armadillo motif (SARM)-containing protein, a known negative regulator of the MyD88-independent pathway. Both live
B. pseudomallei
and heat-killed
B. pseudomallei
were able to upregulate SARM expression in a time-dependent manner in mouse macrophage cell line RAW 264.7. The expression of SARM required bacterial internalization, as it could be inhibited by cytochalasin D. In addition, the intracellular survival of
B. pseudomallei
was suppressed in SARM-deficient macrophages. Increased expression of IFN-β and iNOS and degradation of IκBα correlated with enhanced macrophage killing capability. These results demonstrated that
B. pseudomallei
modulated macrophage defense mechanisms by upregulating SARM, thus leading to the suppression of IFN-β and iNOS needed for bacterial elimination.
Comparison of In Vitro Susceptibility Characteristics of
Candida
Species from Cases of Invasive Candidiasis in Solid Organ and Stem Cell Transplant Recipients: Transplant-Associated Infections Surveillance Network (TRANSNET), 2001 to 2006
Authors: Lockhart Shawn R. , Wagner Debra , Iqbal Naureen , Pappas Peter G. , Andes David R. , Kauffman Carol A. , Brumble Lisa M. , Hadley Susan , Walker Randall , Ito James I. , Baddley John W. , Chiller Tom , Park Benjamin J.
Published: May 2011

Invasive fungal infections (IFI) are a major cause of morbidity and mortality among both solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients.
Candida
is the most common cause of IFI in SOT recipients and the second most common cause of IFI in HSCT recipients. We determined susceptibilities to fluconazole, voriconazole, itraconazole, posaconazole, amphotericin B, and caspofungin for 383 invasive
Candida
sp. isolates from SOT and HSCT recipients enrolled in the Transplant-Associated Infection Surveillance Network and correlated these results to clinical data. Fluconazole resistance in
C. albicans
,
C. tropicalis
, and
C. parapsilosis
isolates was low (1%), but the high percentage of
C. glabrata
and
C. krusei
isolates within this group of patients increased the overall percentage of fluconazole resistance to 16%. Voriconazole resistance was 3% overall but was 8% among
C. glabrata
isolates. On multivariable analysis, among HSCT recipients fluconazole nonsusceptibility was independently associated with
C. glabrata
, non-Hodgkin's lymphoma, cytomegalovirus (CMV) antigenemia, diabetes active at the time of the IFI, and any prior amphotericin B use; among SOT recipients, fluconazole nonsusceptibility was independently associated with any fluconazole use in the 3 months prior to the IFI,
C. glabrata
, ganciclovir use in the 3 months prior to the IFI, diabetes acquired since the transplant, and gender.
Structure and Genetic Analysis of the Arterivirus Nonstructural Protein 7α
Authors: Manolaridis Ioannis , Gaudin Cyril , Posthuma Clara C. , Zevenhoven-Dobbe Jessika C. , Imbert Isabelle , Canard Bruno , Kelly Geoff , Tucker Paul A. , Conte Maria R. , Snijder Eric J.
Published: May 2011

Arterivirus replicase polyproteins are cleaved into at least 13 mature nonstructural proteins (nsps), and in particular the nsp5-to-nsp8 region is subject to a complex processing cascade. The function of the largest subunit from this region, nsp7, which is further cleaved into nsp7α and nsp7β, is unknown. Using nuclear magnetic resonance (NMR) spectroscopy, we determined the solution structure of nsp7α of equine arteritis virus, revealing an interesting unique fold for this protein but thereby providing little clue to its possible functions. Nevertheless, structure-based reverse genetics studies established the importance of nsp7/nsp7α for viral RNA synthesis, thus providing a basis for future studies.
Non-compliance with health surveillance is a matter of Biosafety: a survey of latent tuberculosis infection in a highly endemic setting
Authors: da Rocha Sheila Sotelino , Marinho Jamocyr Moura , Oliveira Evelin Santos , Rodrigues Jaqueline Silva , Conceição Elisabete Lopes , Meira Antonio Edson , Almeida Alzira , Mendes Carlos Mauricio Cardeal , Arruda Sérgio , Barbosa Theolis
Published: May 2011

Objective

This study aimed at identifying demographic, socio-economic and tuberculosis (TB) exposure factors associated with non-compliance with the tuberculin skin test, the management and prevention of non-compliance to the test. It was carried out in the context of a survey of latent TB infection among undergraduate students taking healthcare courses in two universities in Salvador, Brazil, a city highly endemic for TB.

Methods

This is a cross-sectional study of 1164 volunteers carried out between October 2004 and June 2008. Bivariate analysis followed by logistic regression was used to measure the association between non-compliance and potential risk factors through non-biased estimates of the adjusted OR for confounding variables. A parallel evaluation of occupational risk perception and of knowledge of Biosafety measures was also conducted.

Results

The non-compliance rate was above 40% even among individuals potentially at higher risk of disease, which included those who had not been vaccinated (OR 3.33; 95% CI 1.50 to 7.93; p=0.0018), those reporting having had contact with TB patients among close relatives or household contacts (p=0.3673), or those whose tuberculin skin test status was shown within the survey to have recently converted (17.3% of those completing the study). In spite of the observed homogeneity in the degree of Biosafety knowledge, and the awareness campaigns developed within the study focussing on TB prevention, the analysis has shown that different groups have different behaviours in relation to the test. Family income was found to have opposite effects in groups studying different courses as well as attending public versus private universities.

Conclusions

Although the data presented may not be directly generalisable to other situations and cultural settings, this study highlights the need to evaluate factors associated with non-compliance with routine testing, as they may affect the efficacy of Biosafety programs.
A single center comparison of coiling versus stent assisted coiling in 90 consecutive paraophthalmic region aneurysms
Authors: Colby Geoffrey P , Paul Alexandra R , Radvany Martin G , Gandhi Dheeraj , Gailloud Philippe , Huang Judy , Tamargo Rafael J , Coon Alexander L
Published: May 2011

Introduction

Aneurysm recurrence is a principle limitation of endovascular coiling procedures, with recurrence rates reported of >30%. The adjunct use of self-expandable stents has revolutionized the treatment of intracranial aneurysms, especially for complex morphologies, wide necks or unfavorable dome to neck ratios. However, further investigation into the durability and outcomes of stent assisted coiling procedures is required.

Methods

The records of a prospective single center aneurysm database were retrospectively reviewed, and 90 consecutive patients with paraophthalmic aneurysms who underwent coil embolization were identified, 30 of which included stent placement. Patient demographics, aneurysm characteristics, coil packing density, angiographic results (initial and follow-up) and complications were analyzed.

Results

Complete aneurysm occlusion was obtained on initial angiography in 13/30 (43.3%) stented and 19/60 (31.7%) non-stented patients. At ≤24 months (mean follow-up 12.8±6.2 months for stented and 12.8±6.6 months for non-stented group), aneurysm recurrence occurred in 3/26 (11.5%) stented and 14/39 (35.9%) non-stented patients (p<0.05). At the longest follow-up (mean 14.5±12.5 months for stented and 37.6±35.3 months for non-stented), aneurysm recurrence occurred in 4/26 (15.4%) stented and 17/41 (41.5%) non-stented patients (p<0.03). There was no statistically significant correlation between recurrence and aneurysm size or coiling packing.

Conclusions

Following endovascular coil embolization of paraophthalmic region aneurysms, recurrence rates at 2 years were significantly lower in patients who had stent assisted coiling (11.5%) compared with patients who had coiling procedures without the use of a stent (35.9%). Aneurysm size and coiling packing density did not significantly affect recurrence in our study population.
Evaluation of a human generic formulation of ciclosporin in the treatment of canine atopic dermatitis with in vitro assessment of the functional capacity of phagocytic cells
Authors: Kovalik M. , Taszkun I. , Pomorski Z. , Kozak M. , Pomorska D. , Szczepanik M. , Wilkolek P. , Palenik L. , Shaw D. J. , van den Broek A. H. M. , Thoday K. L.
Published: May 2011

To compare the efficacy, tolerability and safety of a generic formulation of ciclosporin for human beings with prednisone in the treatment of canine atopic dermatitis), human generic ciclosporin A (hgCsA) (5 mg/kg daily) and prednisone (1 mg/kg daily for seven days, followed by 1 mg/kg every second day) were administered to 13 and seven dogs with atopic dermatitis, respectively, for 42 days. Skin changes were assessed using a modified canine atopic dermatitis extent and severity index (mCADESI‐01) and a pruritus intensity scale system. The in vitro functional capacity of phagocytic cells was assessed using the tetrazolium reductase activity and zymosan‐stimulated tetrazolium reductase activity tests, as well as measurements of the percentage phagocytic activity and the ingestion capacity of phagocytic cells. Haematological and biochemical parameters were also monitored. There was a greater than or equal to 50 per cent reduction from the baseline in mCADESI‐01 scores in 84.6 and 100 per cent of dogs, and a greater than or equal to 50 per cent reduction from the baseline in pruritus scores in 76.9 and 85.7 per cent of dogs, treated with hgCsA and prednisone, respectively. No important adverse physical, haematological or biochemical effects occurred with either drug and no statistically significant changes were detected in any of the four tests assessing the functional activity of phagocytes. The generic formulation of ciclosporin was effective in reducing the severity of physical signs of canine atopic dermatitis and was well tolerated.
Acute phase proteins in milk in naturally acquired bovine mastitis caused by different pathogens
Authors: Pyörälä S. , Hovinen M. , Simojoki H. , Fitzpatrick J. , Eckersall P. D. , Orro T.
Published: May 2011

The concentrations of haptoglobin (Hp) and serum amyloid A (SAA) and the activity of N‐acetyl‐β‐D‐glucosaminidase (NAGase) in milk from 234 cows with spontaneous mastitis caused by different pathogens were measured to assess whether they corresponded with the clinical signs of mastitis and whether there were any differences between pathogens. Ninety‐eight of the cows had clinical mastitis and 136 had subclinical mastitis. There were statistically significant positive correlations between the concentrations of SAA and Hp and the activity of NAGase. Significant differences in the concentrations of acute phase proteins and NAGase activity were found in milk from cows with mastitis caused by different pathogens. The highest concentrations of Hp and NAGase were found in cases of mastitis caused by Escherichia coli and Arcanobacterium pyogenes, and the lowest concentrations were from cases of mastitis caused by coagulase‐negative staphylococci. Very low SAA concentrations were found in milk from the cases caused by A pyogenes, in contrast to cases caused by other major mastitis pathogens. The median concentration of SAA was over 10 times higher in cases of mastitis caused by E coli than in mastitis caused by other pathogens. There were significant differences in the mean Hp concentration and NAGase activity between clinical and subclinical mastitis. In approximately one‐third of the samples, the Hp concentration was below the detection limit, potentially compromising the use of Hp as a mastitis marker.
Early gene response of human brain microvascular endothelial cells toListeria monocytogenesinfection
Authors: Wang Chinling , Chou Chung-Hsi , Tseng Charles , Ge Xijin , Pinchuk Lesya M.
Published: May 2011

The gene expression of human brain microvascular endothelial cells (HBMEC) in response to 4 h of infection by Listeria monocytogenes was analyzed. Four hours after infection, the expression of 456 genes of HBMEC had changed (p < 0.05). We noted that many active genes were involved in the formyl-methionyl-leucyl-phenylalanine pathway in infected HBMEC. In the upregulated genes, mRNA levels of interleukin-8 and interleukin-15 in infected cells increased according to microarray and real-time reverse transcription – PCR analyses. Since both cytokines are regarded as potent chemotactic factors, the results suggest that HBMEC are capable of recruiting cells of innate and adaptive immune responses during early L. monocytogenes infection.
Ophiostoma mitovirus 3a, ascorbic acid, glutathione, and photoperiod affect the development of stromata and apothecia by Sclerotinia homoeocarpa
Authors: Orshinsky A.M. , Boland G.J.
Published: May 2011

Hypovirulence in Sclerotinia homoeocarpa is associated with infection by Ophiostoma mitovirus 3a (OMV3a). OMV3a is also present in asymptomatic isolates, with growth and virulence comparable to that of virus-free isolates. Hypovirulent isolates have impaired mitochondrial function resulting in increased activity of the alternative oxidase pathway, which is implicated in the reduction of reactive oxygen species in other fungi. In this study, hypovirulent, asymptomatic, and virus-free isolates were grown on potato dextrose agar amended with ascorbic acid or glutathione and were incubated under various photoperiods to determine the importance of reactive oxygen species, light, and OMV3a infection for differentiation of stromata and apothecia by S. homoeocarpa. Hypovirulent isolates did not form stromata or apothecia. Glutathione and darkness reduced stromata size and apothecia production by virulent and asymptomatic isolates. Apothecia formed under several different photoperiods, and ascorbic acid increased apothecia production. Ascospores were not detected in these apothecia. The results suggest that hypovirulence, light, and the superoxide radical are important factors in the formation of stromata and apothecia by S. homoeocarpa isolates. This is the first report of sterile apothecia production by North American isolates of S. homoeocarpa and provides a starting point for attempts to produce fertile apothecia.
Occurrence of both subspecies of Photobacterium damselae in mullets collected in the river Magra (Italy)
Authors: Serracca Laura , Ercolini Carlo , Rossini Irene , Battistini Roberta , Giorgi Ilaria , Prearo Marino
Published: May 2011

The natural reservoirs and biological characteristics of pathogenic populations of both subspecies of Photobacterium damselae in aquatic habitants remain unclear because of difficulties in obtaining pathogenic strains from the environment. In the present study, we assessed the occurrence of Photobacterium damselae subsp. piscicida and Photobacterium damselae subsp. damselae , considered to be the causative agent of past epizootic outbreaks in mullets collected in the river Magra, Italy. Two hundred and seventy-eight mullets were collected during a period of two years (2008–2009) and analyzed using multiplex PCR. During this period, 57% of fishes were positive for Photobacterium damselae subsp. piscicida and 37% for Photobacterium damselae subsp. damselae, with an higher presence in summer months although none of PCR-positive mullets showed clinical signs of disease. Our results indicate that the two microrganisms are widespread in the population of mullets studied, and this could be a possible cause for outbreaks in favourable environmental conditions.
In vitro degradation of the moss Hylocomium splendens by three pleosporalean fungi
Authors: Day Melissa J. , Currah Randolph S.
Published: May 2011

Three darkly pigmented species of conidial fungi of the family Pleosporaceae isolated from plants colonizing the Saskatchewan Glacier forefield were examined for potential roles in the degradation of moss gametophytes. Curvularia inaequalis and Ulocladium atrum isolated from bryophytes Ditrichum flexicaule and Tortella tortuosa , respectively, and Chalastospora gossypii from Saxifraga oppositifolia were inoculated onto autoclaved gametophytes of the moss Hylocomium splendens. All three species of fungi caused mass losses of the moss gametophytes. In vitro enzymatic tests revealed that all three fungi degraded cellulose, while none degraded insoluble polyphenols. When this material was examined by scanning electron microscopy, it was evident that the fungi had eroded the outer wall layer of the moss leaf cells to some extent but not the inner layer containing more lignin-like compounds. Once the outer wall layer was removed, the cells easily disarticulated. It is proposed that accumulations of these phenolics-rich leaf fragments subsequently ameliorate the rooting environment for vascular plants and have the potential to support the growth of basidiomycetes and other fungi, potentially mycorrhizal with pioneer vascular plants.