bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the resonant vibration of thin plates: Reconstruction of Chladni patterns and determination of resonant wave numbers
Authors: Tuan P. H. , Wen C. P. , Chiang P. Y. , Yu Y. T. , Liang H. C. , Huang K. F. , Chen Y. F.
Published: April 2015

The Chladni nodal line patterns and resonant frequencies for a thin plate excited by an electronically controlled mechanical oscillator are experimentally measured. Experimental results reveal that the resonant frequencies can be fairly obtained by means of probing the variation of the effective impedance of the exciter with and without the thin plate. The influence of the extra mass from the central exciter is confirmed to be insignificant in measuring the resonant frequencies of the present system. In the theoretical aspect, the inhomogeneous Helmholtz equation is exploited to derive the response function as a function of the driving wave number for reconstructing experimental Chladni patterns. The resonant wave numbers are theoretically identified with the maximum coupling efficiency as well as the maximum entropy principle. Substituting the theoretical resonant wave numbers into the derived response function, all experimental Chladni patterns can be excellently reconstructed. More importantly, the dispersion relationship for the flexural wave of the vibrating plate can be determined with the experimental resonant frequencies and the theoretical resonant wave numbers. The determined dispersion relationship is confirmed to agree very well with the formula of the Kirchhoff–Love plate theory.
Coupling of transverse and longitudinal waves in piano strings
Authors: Etchenique Nikki , Collin Samantha R. , Moore Thomas R.
Published: April 2015

The existence of longitudinal waves in vibrating piano strings has been previously established, as has their importance in producing the characteristic sound of the piano. Modeling of the coupling between the transverse and longitudinal motion of strings indicates that the amplitude of the longitudinal waves are quadratically related to the transverse displacement of the string, however, experimental verification of this relationship is lacking. In the work reported here this relationship is tested by driving the transverse motion of a piano string at only two frequencies, which simplifies the task of unambiguously identifying the constituent signals. The results indicate that the generally accepted relationship between the transverse motion and the longitudinal motion is valid. It is further shown that this dependence on transverse displacement is a good approximation when a string is excited by the impact of the hammer during normal play.
Barriers to Physical Activity in Children With Autism Spectrum Disorders: Relationship to Physical Activity and Screen Time
Authors: Must Aviva , Phillips Sarah , Curtin Carol , Bandini Linda G.
Published: April 2015

Background:

Individual, social, and community barriers to physical activity (PA) experienced by children with autism spectrum disorder (ASD) make PA participation more difficult and may contribute to increased screen time.

Methods:

We compared the prevalence of parent-reported barriers to PA among 58 typically developing (TD) children and 53 children with an ASD, 3 to 11 years, and assessed the association between barriers and PA participation and screen time among children with ASD.

Results:

Parents of children with ASD reported significantly more barriers than parents of TD children. Based on parent-report, 60% of children with ASD required too much supervision compared with no TD children (P < .001). Parents of children with ASD were more likely to report that adults lack skills needed to include their child (58%), that their child has few friends (45%), and that other children exclude their child (23%). The number of parent-reported barriers to PA was inversely correlated with the hours spent in PA per year (r = −0.27, P = .05) and positively related to total screen time (r = .32, P < .03).

Conclusions:

These findings underscore the need for community-based PA programs designed to meet the special requirements of this population and policies that compel schools and other government-supported organizations for inclusion and/or targeted programming.
Family Cohesion and Moderate-to-Vigorous Physical Activity Among Mexican Origin Adolescents: A Longitudinal Perspective
Authors: Bigman Galya , Rajesh Vandita , Koehly Laura M. , Strong Larkin L. , Oluyomi Abiodun O. , Strom Sara S. , Wilkinson Anna V.
Published: April 2015

Background:

Existing racial/ethnic disparities in physical activity during childhood increase Hispanics’ risk of developing chronic diseases, which serves to increase health disparities. This study examined associations of family cohesion and conflict with self-reported moderate-tovigorous physical activity (MVPA), controlling for psychosocial covariates such as subjective social status, anxiety, and sensation-seeking.

Methods:

1000 Mexican origin adolescents reported their MVPA levels approximately 2 years apart. Psychosocial covariates, family cohesion and conflict were measured at the first assessment. Generalized Linear Models were used to prospectively examine the relationship between family cohesion and conflict and subsequent MVPA based on 711 participants who had low levels of baseline MVPA.

Results:

35% of boys and 24% of girls reported adequate MVPA levels at follow-up; girls were less likely to report adequate MVPA (RR = 0.76; 95% CI: 0.61–0.93) than boys. Overall, family cohesion was associated with MVPA (P = .01), but family cohesion was not (P = .41). Gender-based analyses revealed that adequate MVPA was associated with family cohesion (RR = 1.40; 95% CI: 1.03–1.88), sensation seeking (RR = 1.05; 95% CI: 1.00–1.10), and age (RR = 0.85; 95% CI: 0.74–0.98) among girls and with subjective social status (RR = 1.20; 95% CI: 1.08–1.33) among boys.

Conclusions:

The family social environment and gender differences should be addressed in health promotion programs targeting MVPA.
The Relationship Between Parental Physical Activity and Screen Time Behaviors and the Behaviors of their Young Children
Authors: Carson Valerie , Stearns Jodie , Janssen Ian
Published: April 2015

The main purpose of this study was to examine the relationships between parental and children’s physical activity and screen time behaviors in a large sample of children in the early years. The results are based on 738 children aged 0–5 years and their parents from the Kingston, Canada area. Parents completed a questionnaire from May to September 2011 that assessed sociodemographic characteristics, their physical activity and screen time, and their child’s physical activity and screen time. Logistic regression models, adjusted for potential confounders, were conducted. Parents in the lowest quartile of physical activity were 2.77 (95% confidence interval (CI): 1.68–4.57) times more likely to have a child in the lowest quartile of physical activity compared with parents in the highest quartile of physical activity. Relationships were stronger in two parent homes compared with single-parent homes. Parents in the second (odds ratio = 2.27, 95% CI: 1.36–3.78), third (2.30, 1.32–3.99), and fourth (7.47, 4.53–12.33) screen time quartiles were significantly more likely to have a child in the highest quartile of screen time compared with parents in quartile one. To optimize healthy growth and development in the early years, future family-centered interventions targeting both physical activity and screen time appear important.
Dynamic Stability of Task-Related Thoughts in Trained Runners
Authors: García Sergi , Razon Selen , Hristovski Robert , Balagué Natàlia , Tenenbaum Gershon
Published: April 2015

Drawing upon the nonlinear model of attention focus, the purpose of this study was to compare the intrinsic and intentional dynamics of task-related thoughts (TRT) in trained runners and nonrunners during an incremental maximal test. Fourteen trained runners and 14 nonrunners were assigned to 2 conditions: intrinsic (nonimposed thoughts) and intentional (imposed, task-unrelated thoughts; TUT). A significant effect of running velocity over TUT/TRT dynamics in both groups and conditions was observed (p < .001). Although, all participants received instructions to keep TUT for the entire duration of the test, an initially stable TUT phase was followed by a metastable phase (i.e., switches between TUT and TRT) an a final stable TRT phase nearing volitional exhaustion. The stable TRT phase lasted longer in runners group (p < .05) and included higher probabilities in pace monitoring thoughts subcategory (p < .05). The results revealed that trained runners seem to use TRT (i.e., pace monitoring) to maximize performance, and confirm the nonlinear model of attention focus during incremental maximal run in trained runners and nonrunners.
Dynamic phosphoproteomics reveals TORC1-dependent regulation of yeast nucleotide and amino acid biosynthesis
Authors: Oliveira Ana Paula , Ludwig Christina , Zampieri Mattia , Weisser Hendrik , Aebersold Ruedi , Sauer Uwe
Published: April 2015

The effect of phosphorylation on metabolic enzyme activity could be inferred by correlating phosphoproteomics and metabolomics data.
G protein activation at the Golgi
Authors: VanHook Annalisa M.
Published: April 2015

GIV regulates both heterotrimeric and monomeric G protein signaling at the Golgi.
Keeping cells from getting Hippo-sized under energy stress
Authors: Wong Wei
Published: April 2015

The transcriptional coactivator YAP is inhibited by AMPK-mediated phosphorylation during energy stress.
First Description of Azole-Resistant Aspergillus fumigatus Due to TR
46
/Y121F/T289A Mutation in France
Authors: Lavergne Rose-Anne , Morio Florent , Favennec Loïc , Dominique Stéphane , Meis Jacques F. , Gargala Gilles , Verweij Paul E. , Le Pape Patrice
Published: April 2015

Azole resistance in
Aspergillus fumigatus
is an emerging public health concern. Recently, a novel fungicide-driven mutation in the
cyp51A
gene and its promoter, TR
46
/Y121F/T289A, leading to high-level resistance to voriconazole has been identified in The Netherlands, Belgium, Germany, Denmark, Tanzania, and India in both clinical and environmental samples. Here we report the first description of
A. fumigatus
carrying this mutation in France, in a cystic fibrosis patient, underlining the need for extensive monitoring of
Aspergillus
resistance.
Cross-Protection of Influenza A Virus Infection by a DNA Aptamer Targeting the PA Endonuclease Domain
Authors: Yuan Shuofeng , Zhang Naru , Singh Kailash , Shuai Huiping , Chu Hin , Zhou Jie , Chow Billy K. C. , Zheng Bo-Jian
Published: April 2015

Amino acid residues in the N-terminal of the PA subunit (PAN) of the influenza A virus polymerase play critical roles in endonuclease activity, protein stability, and viral RNA (vRNA) promoter binding. In addition, PANis highly conserved among different subtypes of influenza virus, which suggests PANto be a desired target in the development of anti-influenza agents. We selected DNA aptamers targeting the intact PA protein or the PANdomain of an H5N1 virus strain using systematic evolution of ligands by exponential enrichment (SELEX). The binding affinities of selected aptamers were measured, followed by an evaluation ofin vitroendonuclease inhibitory activity. Next, the antiviral effects of enriched aptamers against influenza A virus infections were examined. A total of three aptamers targeting PA and six aptamers targeting PANwere selected. Our data demonstrated that all three PA-selected aptamers neither inhibited endonuclease activity nor exhibited antiviral efficacy, whereas four of the six PAN-selected aptamers inhibited both endonuclease activity and H5N1 virus infection. Among the four effective aptamers, one exhibited cross-protection against infections of H1N1, H5N1, H7N7, and H7N9 influenza viruses, with a 50% inhibitory concentration (IC50) of around 10 nM. Notably, this aptamer was identified at the 5th round but disappeared after the 10th round of selection, suggesting that the identification and evaluation of aptamers at early rounds of selection may be highly helpful for screening effective aptamers. Overall, our study provides novel insights for screening and developing effective aptamers for use as anti-influenza drugs.
Saccharomyces cerevisiae-Based Mutational Analysis of the
bc
1
Complex Q
o
Site Residue 279 To Study the Trade-Off between Atovaquone Resistance and Function
Authors: Song Zehua , Clain Jérôme , Iorga Bogdan I. , Yi Zhou , Fisher Nicholas , Meunier Brigitte
Published: April 2015

The
bc
1
complex is central to mitochondrial bioenergetics and the target of the antimalarial drug atovaquone that binds in the quinol oxidation (Q
o
) site of the complex. Structural analysis has shown that the Q
o
site residue Y279 (Y268 in
Plasmodium falciparum
) is key for atovaquone binding. Consequently, atovaquone resistance can be acquired by mutation of that residue. In addition to the probability of amino acid substitution, the level of atovaquone resistance and the loss of
bc
1
complex activity that are associated with the novel amino acid would restrict the nature of resistance-driven mutations occurring on atovaquone exposure in native parasite populations. Using the yeast model, we characterized the effect of all the amino acid replacements resulting from a single nucleotide substitution at codon 279: Y279C, Y279D, Y279F, Y279H, Y279N, and Y279S (Y279C, D, F, H, N, and S). Two residue changes that required a double nucleotide substitution, Y279A and W, were added to the series. We found that mutations Y279A, C, and S conferred high atovaquone resistance but decreased the catalytic activity. Y279F had wild-type enzymatic activity and sensitivity to atovaquone, while the other substitutions caused a dramatic respiratory defect. The results obtained with the yeast model were examined in regard to atomic structure and compared to the reported data on the evolution of acquired atovaquone resistance in
P. falciparum
.
Dominance of IMP-4-Producing Enterobacter cloacae among Carbapenemase-Producing Enterobacteriaceae in Australia
Authors: Sidjabat Hanna E. , Townell Nicola , Nimmo Graeme R. , George Narelle M. , Robson Jennifer , Vohra Renu , Davis Louise , Heney Claire , Paterson David L.
Published: April 2015

The prevalence of carbapenemase-producing
Enterobacteriaceae
(CPE) has been increasing worldwide.
bla
IMP
has been reported to be the predominant carbapenemase-encoding gene within
Enterobacteriaceae
in Australia. However, there are limited data currently available on CPE from Queensland, Australia. A total of 58 CPE isolates were isolated between July 2009 and March 2014 from Queensland hospitals. The clonality of isolates was determined by Diversilab repetitive sequence-based PCR. The isolates were investigated for the resistance mechanisms carbapenemase, extended-spectrum β-lactamase, and AmpC β-lactamase and for aminoglycoside resistance and plasmid-mediated quinolone resistance genes by PCR. The plasmid types associated with carbapenemase-encoding genes were characterized. The majority of the CPE were
Enterobacter cloacae
(
n
= 29). The majority of Queensland CPE isolates were IMP producers and comprised 11 species (
n
= 48). Nine NDM-producing
Enterobacteriaceae
were identified. One NDM-producing
Klebsiella pneumoniae
isolate coproduced OXA-48. One
K. pneumoniae
isolate was an OXA-181 producer. The incidence of IMP producers increased significantly in 2013.
bla
IMP-4
was found in all IMP-producing isolates.
bla
TEM
,
qnrB
, and
aacA4
were common among IMP-4 producers. The HI2 (67%) and L/M (21%) replicons were associated with
bla
IMP-4
. All HI2 plasmids were of sequence type 1 (ST1). All but one of the NDM producers possessed
bla
CTX-M-15
. The 16S rRNA methylase genes found among NDM producers were
armA
,
rmtB
,
rmtC
, and
rmtF
. The substantial increase in the prevalence of CPE in Queensland has been associated mainly with the emergence
E. cloacae
strains possessing HI2 plasmids carrying
bla
IMP-4
over the past 2 years. The importation of NDM producers and/or OXA-48-like producers in patients also contributed to the increased emergence of CPE.
Emergence of Polymyxin B Resistance Influences Pathogenicity in Pseudomonas aeruginosa Mutators
Authors: Bulman Zackery P. , Sutton Mark D. , Ly Neang S. , Bulitta Jurgen B. , Holden Patricia N. , Nation Roger L. , Li Jian , Tsuji Brian T.
Published: April 2015

The interplay between polymyxin B pharmacodynamics and pathogenicity was examined in
Pseudomonas aeruginosa
PAO1 and isogenic DNA repair-deficient mutators (
mutM
and
mutS
strains). Against
mutS
mutators, polymyxin B initial killing was concentration dependent, with >99.9% bacterial reduction at 2 h followed by regrowth and resistance. The pre- versus postexposed strains were inoculated real time into
Galleria mellonella
waxworms, resulting in increased median survival times from 20 h to 23 h (
P
< 0.001). Emergence of resistance in
mutS
P. aeruginosa
resulted in attenuation of virulence.
Interspecies Transfer of the Penicillin-Binding Protein 3-Encoding Gene
ftsI
between Haemophilus influenzae and Haemophilus haemolyticus Can Confer Reduced Susceptibility to β-Lactam Antimicrobial Agents
Authors: Søndergaard Annette , Witherden Elizabeth A. , Nørskov-Lauritsen Niels , Tristram Stephen G.
Published: April 2015

Mutations in
ftsI
, encoding penicillin-binding protein 3, can cause decreased β-lactam susceptibility in
Haemophilus influenzae
. Sequencing of
ftsI
from clinical strains has indicated interspecies recombination of
ftsI
between
H. influenzae
and
Haemophilus haemolyticus
. This study documented apparently unrestricted homologous recombination of
ftsI
between
H. influenzae
and
H. haemolyticus in vitro
. Transfer of
ftsI
from resistant isolates conferred similar but not identical increases in the MICs of susceptible strains of
H. influenzae
and
H. haemolyticus
.
Evidence for Proinflammatory β-1,6 Glucans in the Pneumocystis carinii Cell Wall
Authors: Kottom Theodore J. , Hebrink Deanne M. , Jenson Paige E. , Gudmundsson Gunnar , Limper Andrew H.
Published: April 2015

Inflammation is a major cause of respiratory impairment during
Pneumocystis
pneumonia. Studies support a significant role for cell wall β-glucans in stimulating inflammatory responses. Fungal β-glucans are comprised of
d
-glucose homopolymers containing β-1,3-linked glucose backbones with β-1,6-linked glucose side chains. Prior studies in
Pneumocystis carinii
have characterized β-1,3 glucan components of the organism. However, recent investigations in other organisms support important roles for β-1,6 glucans, predominantly in mediating host cellular activation. Accordingly, we sought to characterize β-1,6 glucans in the cell wall of
Pneumocystis
and to establish their activity in lung cell inflammation. Immune staining revealed specific β-1,6 localization in
P. carinii
cyst walls. Homology-based cloning facilitated characterization of a functional
P. carinii
kre6
(
Pckre6
) β-1,6 glucan synthase in
Pneumocystis
that, when expressed in
kre6
-deficient
Saccharomyces cerevisiae
, restored cell wall stability. Recently synthesized β-1,6 glucan synthase inhibitors decreased the ability of isolated
P. carinii
preparations to generate β-1,6 carbohydrate. In addition, isolated β-1,6 glucan fractions from
Pneumocystis
elicited vigorous tumor necrosis factor alpha (TNF-α) responses from macrophages. These inflammatory responses were significantly dampened by inhibition of host cell plasma membrane microdomain function. Together, these studies indicate that β-1,6 glucans are present in the
P. carinii
cell wall and contribute to lung cell inflammatory activation during infection.
Simultaneous Identification of Potential Pathogenicity Factors of Mycoplasma agalactiae in the Natural Ovine Host by Negative Selection
Authors: Hegde Shivanand , Hegde Shrilakshmi , Zimmermann Martina , Flöck Martina , Spergser Joachim , Rosengarten Renate , Chopra-Dewasthaly Rohini
Published: April 2015

Mycoplasmas possess complex pathogenicity determinants that are largely unknown at the molecular level.
Mycoplasma agalactiae
serves as a useful model to study the molecular basis of mycoplasma pathogenicity. The generation and
in vivo
screening of a transposon mutant library of
M. agalactiae
were employed to unravel its host colonization factors. Tn
4001
mod mutants were sequenced using a novel sequencing method, and functionally heterogeneous pools containing 15 to 19 selected mutants were screened simultaneously through two successive cycles of sheep intramammary infections. A PCR-based negative selection method was employed to identify mutants that failed to colonize the udders and draining lymph nodes in the animals. A total of 14 different mutants found to be absent from ≥95% of samples were identified and subsequently verified via a second round of stringent confirmatory screening where 100% absence was considered attenuation. Using this criterion, seven mutants with insertions in genes MAG1050, MAG2540, MAG3390,
uhpT
,
eutD
,
adhT
, and MAG4460 were not recovered from any of the infected animals. Among the attenuated mutants, many contain disruptions in hypothetical genes, implying their previously unknown role in
M. agalactiae
pathogenicity. These data indicate the putative role of functionally different genes, including hypothetical ones, in the pathogenesis of
M. agalactiae
. Defining the precise functions of the identified genes is anticipated to increase our understanding of
M. agalactiae
infections and to develop successful intervention strategies against it.
Attenuated Mutants of Ehrlichia chaffeensis Induce Protection against Wild-Type Infection Challenge in the Reservoir Host and in an Incidental Host
Authors: Nair Arathy D. S. , Cheng Chuanmin , Jaworski Deborah C. , Ganta Suhasini , Sanderson Michael W. , Ganta Roman R.
Published: April 2015

Ehrlichia chaffeensis
, a tick-borne rickettsial organism, causes the disease human monocytic ehrlichiosis. The pathogen also causes disease in several other vertebrates, including dogs and deer. In this study, we assessed two clonally purified
E. chaffeensis
mutants with insertions within the genes Ech_0379 and Ech_0660 as vaccine candidates in deer and dogs. Infection with the Ech_0379 mutant and challenge with wild-type
E. chaffeensis
1 month following inoculation with the mutant resulted in the reduced presence of the organism in blood compared to the presence of wild-type infection in both deer and dogs. The Ech_0660 mutant infection resulted in its rapid clearance from the bloodstream. The wild-type infection challenge following Ech_0660 mutant inoculation also caused the pathogen's clearance from blood and tissue samples as assessed at the end of the study. The Ech_0379 mutant-infected and -challenged animals also remained positive for the organism in tissue samples in deer but not in dogs. This is the first study that documents that insertion mutations in
E. chaffeensis
that cause attenuated growth confer protection against wild-type infection challenge. This study is important in developing vaccines to protect animals and people against
Ehrlichia
species infections.
NAD-Independent l-Lactate Dehydrogenase Required for l-Lactate Utilization in Pseudomonas stutzeri A1501
Authors: Gao Chao , Wang Yujiao , Zhang Yingxin , Lv Min , Dou Peipei , Xu Ping , Ma Cuiqing
Published: April 2015

NAD-independentl-lactate dehydrogenases (l-iLDHs) play important roles inl-lactate utilization of different organisms. All of the previously reportedl-iLDHs were flavoproteins that catalyze the oxidation ofl-lactate by the flavin mononucleotide (FMN)-dependent mechanism. Based on comparative genomic analysis, a gene cluster with three genes (lldA,lldB, andlldC) encoding a novel type ofl-iLDH was identified inPseudomonas stutzeriA1501. When the gene cluster was expressed inEscherichia coli, distinctivel-iLDH activity was detected. The expressedl-iLDH was purified by ammonium sulfate precipitation, ion-exchange chromatography, and affinity chromatography. SDS-PAGE and successive matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis of the purifiedl-iLDH indicated that it is a complex of LldA, LldB, and LldC (encoded bylldA,lldB, andlldC, respectively). Purifiedl-iLDH (LldABC) is a dimer of three subunits (LldA, LldB, and LldC), and the ratio between LldA, LldB, and LldC is 1:1:1. Different from the FMN-containingl-iLDH, absorption spectra and elemental analysis suggested that LldABC might use the iron-sulfur cluster for thel-lactate oxidation. LldABC has narrow substrate specificity, and onlyl-lactate anddl-2-hydrobutyrate were rapidly oxidized. Mg2+could activatel-iLDH activity effectively (6.6-fold). Steady-state kinetics indicated a ping-pong mechanism of LldABC for thel-lactate oxidation. Based on the gene knockout results, LldABC was confirmed to be required for thel-lactate metabolism ofP. stutzeriA1501. LldABC is the first purified and characterizedl-iLDH with different subunits that uses the iron-sulfur cluster as the cofactor.

IMPORTANCEProviding new insights into the diversity of microbial lactate utilization could assist in the production of valuable chemicals and understanding microbial pathogenesis. An NAD-independentl-lactate dehydrogenase (l-iLDH) encoded by the gene clusterlldABCis indispensable for thel-lactate metabolism inPseudomonas stutzeriA1501. This novel type of enzyme was purified and characterized in this study. Different from the well-characterized FMN-containingl-iLDH in other microbes, LldABC inP. stutzeriA1501 is a dimer of three subunits (LldA, LldB, and LldC) and uses the iron-sulfur cluster as a cofactor.
Coculture of Staphylococcus aureus with Pseudomonas aeruginosa Drives S. aureus towards Fermentative Metabolism and Reduced Viability in a Cystic Fibrosis Model
Authors: Filkins Laura M. , Graber Jyoti A. , Olson Daniel G. , Dolben Emily L. , Lynd Lee R. , Bhuju Sabin , O'Toole George A.
Published: April 2015

The airways of patients with cystic fibrosis are colonized with diverse bacterial communities that change dynamically during pediatric years and early adulthood.
Staphylococcus aureus
is the most prevalent pathogen during early childhood, but during late teens and early adulthood, a shift in microbial composition occurs leading to
Pseudomonas aeruginosa
community predominance in ∼50% of adults. We developed a robust dual-bacterial
in vitro
coculture system of
P. aeruginosa
and
S. aureus
on monolayers of human bronchial epithelial cells homozygous for the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) mutation to better model the mechanisms of this interaction. We show that
P. aeruginosa
drives the
S. aureus
expression profile from that of aerobic respiration to fermentation. This shift is dependent on the production of both 2-heptyl-4-hydroxyquinoline
N
-oxide (HQNO) and siderophores by
P. aeruginosa
. Furthermore,
S. aureus
-produced lactate is a carbon source that
P. aeruginosa
preferentially consumes over medium-supplied glucose. We find that initially
S. aureus
and
P. aeruginosa
coexist; however, over extended coculture
P. aeruginosa
reduces
S. aureus
viability, also in an HQNO- and
P. aeruginosa
siderophore-dependent manner. Interestingly,
S. aureus
small-colony-variant (SCV) genetic mutant strains, which have defects in their electron transport chain, experience reduced killing by
P. aeruginosa
compared to their wild-type parent strains; thus, SCVs may provide a mechanism for persistence of
S. aureus
in the presence of
P. aeruginosa
. We propose that the mechanism of
P. aeruginosa
-mediated killing of
S. aureus
is multifactorial, requiring HQNO and
P. aeruginosa
siderophores as well as additional genetic, environmental, and nutritional factors.

IMPORTANCE
In individuals with cystic fibrosis,
Staphylococcus aureus
is the primary respiratory pathogen during childhood. During adulthood,
Pseudomonas aeruginosa
predominates and correlates with worse patient outcome. The mechanism(s) by which
P. aeruginosa
outcompetes or kills
S. aureus
is not well understood. We describe an
in vitro
dual-bacterial species coculture system on cystic fibrosis-derived airway cells, which models interactions relevant to patients with cystic fibrosis. Further, we show that molecules produced by
P. aeruginosa
additively induce a transition of
S. aureus
metabolism from aerobic respiration to fermentation and eventually lead to loss of
S. aureus
viability. Elucidating the molecular mechanisms of
P. aeruginosa
community predominance can provide new therapeutic targets and approaches to impede this microbial community transition and subsequent patient worsening.
Iron Depletion Enhances Production of Antimicrobials by Pseudomonas aeruginosa
Authors: Nguyen Angela T. , Jones Jace W. , Ruge Max A. , Kane Maureen A. , Oglesby-Sherrouse Amanda G.
Published: April 2015

Cystic fibrosis (CF) is a heritable disease characterized by chronic, polymicrobial lung infections. While
Staphylococcus aureus
is the dominant lung pathogen in young CF patients,
Pseudomonas aeruginosa
becomes predominant by adulthood.
P. aeruginosa
produces a variety of antimicrobials that likely contribute to this shift in microbial populations. In particular, secretion of 2-alkyl-4(1
H
)-quinolones (AQs) contributes to lysis of
S. aureus
in coculture, providing an iron source to
P. aeruginosa
both
in vitro
and
in vivo
. We previously showed that production of one such AQ, the
Pseudomonas
quinolone signal (PQS), is enhanced by iron depletion and that this induction is dependent upon the iron-responsive PrrF small RNAs (sRNAs). Here, we demonstrate that antimicrobial activity against
S. aureus
during coculture is also enhanced by iron depletion, and we provide evidence that multiple AQs contribute to this activity. Strikingly, a
P. aeruginosa
Δ
prrF
mutant, which produces very little PQS in monoculture, was capable of mediating iron-regulated growth suppression of
S. aureus
. We show that the presence of
S. aureus
suppresses the Δ
prrF1
,
2
mutant's defect in iron-regulated PQS production, indicating that a PrrF-independent iron regulatory pathway mediates AQ production in coculture. We further demonstrate that iron-regulated antimicrobial production is conserved in multiple
P. aeruginosa
strains, including clinical isolates from CF patients. These results demonstrate that iron plays a central role in modulating interactions of
P. aeruginosa
with
S. aureus
. Moreover, our studies suggest that established iron regulatory pathways of these pathogens are significantly altered during polymicrobial infections.

IMPORTANCE
Chronic polymicrobial infections involving
Pseudomonas aeruginosa
and
Staphylococcus aureus
are a significant cause of morbidity and mortality, as the interplay between these two organisms exacerbates infection. This is in part due to enhanced production of antimicrobial metabolites by
P. aeruginosa
when these two species are cocultured. Using both established and newly developed coculture techniques, this report demonstrates that iron depletion increases
P. aeruginosa
's ability to suppress growth of
S. aureus
. These findings present a novel role for iron in modulating microbial interaction and provide the basis for understanding how essential nutrients drive polymicrobial infections.
Iron-Mediated Control of Pseudomonas aeruginosa-Staphylococcus aureus Interactions in the Cystic Fibrosis Lung
Authors: Barnabie Patricia M. , Whiteley Marvin
Published: April 2015

Communication is an important factor for bacterial survival, growth, and persistence. Much work has examined both inter- and intraspecies interactions and their effects on virulence. Now, researchers have begun to explore the ways in which host-modulated factors can impact bacterial interactions and subsequently affect patient outcomes. In this issue, two papers discuss how the host environment alters interactions between the pathogens
Pseudomonas aeruginosa
and
Staphylococcus aureus
, largely in the context of cystic fibrosis.
Lower motor neuron facial palsy after ventriculoperitoneal shunt surgery
Authors: Ramdasi Raghvendra Vijayrao , Rangarajan Vithal , Mahore Amit
Published: April 2015

A 40-year-old woman underwent marsupialisation of a symptomatic retrocerebellar cyst. She developed pseudomeningocoele after the procedure. CT of the brain showed hydrocephalus. Therefore, a right-sided ventriculoperitoneal shunt procedure was performed. Unfortunately, the patient developed lower motor neuron-type facial paralysis immediately after the surgery. We localised the site of injury in the distal fallopian canal probably during tunnelling of the subcutaneous tract for passage of the shunt. We discuss the steps to be followed to avoid such mishaps with a brief review of the literature.
Metastatic renal cell carcinoma presenting with mediastinal eggshell calcification
Authors: Heng Jacob S , Ghuman Abeer S , Hamdulay Shahir S , Hirji Hassan
Published: April 2015

An 81-year-old South Asian man normally resident in the UK presented with night sweats for over 2 months on a background of weight loss of 4 kg in 6 months. His medical history was significant for metastatic renal cell carcinoma treated 5 years previously with cytoreductive nephrectomy and adjuvant chemotherapy. Following an abnormal chest radiograph showing an ill-defined right paratracheal mass, a CT scan showed eggshell calcification (circumferential calcification) of enlarged low right paratracheal lymph nodes. An endobronchial ultrasound–guided transbronchial needle aspiration of an involved large paratracheal lymph node showed cytology consistent with metastatic renal cell carcinoma.
Visceral leishmaniasis in an infant following a holiday trip to Spain
Authors: Trück Johannes , Rampton Charlotte , Kelly Susan Jane , Kelly Dominic
Published: April 2015

Imported leishmaniasis is rare in non-endemic countries such as the UK. Visceral leishmaniasis (VL) can be life-threatening and its recognition is imperative for successful clinical management. We present a case of VL in an 11-month-old infant several months after returning from a 1-week holiday trip to the South of Spain. The infant suffered from intermittent fever for 5 weeks, and hepatosplenomegaly and pancytopenia, and was successfully treated with a short course of liposomal amphotericin B. This case of VL is to highlight the possibility of transmission of unusual pathogens when travelling to the Mediterranean and therefore the importance of taking a detailed travel history. VL should be considered in the differential diagnosis in returning travellers presenting with prolonged fever, hepatosplenomegaly and/or pancytopenia.
Safe-sex belief and sexual risk behaviours among adolescents from three developing countries: a cross-sectional study
Authors: Osorio Alfonso , Lopez-del Burgo Cristina , Ruiz-Canela Miguel , Carlos Silvia , de Irala Jokin
Published: April 2015

Objectives

This study intends to evaluate whether the belief that condoms are 100% effective in protecting against HIV infection is associated with sexual risk behaviours among youth.

Methods

A cross-sectional study was performed in representative samples of high-school students in the Philippines, El Salvador and Peru. Participants completed a self-administered questionnaire. Students were asked about the risk of HIV transmission if one has sex using condoms. They were also asked to indicate whether they had ever had sexual relations and whether they used a condom in their first sexual relation. The sample was composed of 8994 students, aged 13–18.

Results

One out of seven adolescents believed condoms are 100% effective (safe-sex believers). Those adolescents were 82% more likely to have had sex than those without such belief, after adjusting for confounders (OR=1.82; 95% CI 1.51 to 2.21). On the contrary, no association was found between risk perception and condom use. Subgroup and sensitivity analyses produced similar results.

Conclusions

This is, to the best of our knowledge, the first study conducted specifically to evaluate this phenomenon and that has used the same questionnaire and the same data collection protocol in three different developing countries from Asia, Central and South America. These results reasonably suggest that there could be an association between safe sex beliefs and sexual initiation. Longitudinal studies are needed to better understand this possible association as it could influence how to better promote sexual health.
A qualitative study of the variable effects of audit and feedback in the ICU
Authors: Sinuff Tasnim , Muscedere John , Rozmovits Linda , Dale Craig M , Scales Damon C
Published: April 2015

Background

Audit and feedback is integral to performance improvement and behaviour change in the intensive care unit (ICU). However, there remain large gaps in our understanding of the social experience of audit and feedback and the mechanisms whereby it can be optimised as a quality improvement strategy in the ICU setting.

Methods

We conducted a modified grounded theory qualitative study. Seventy-two clinicians from five academic and five community ICUs in Ontario, Canada, were interviewed. Team members reviewed interview transcripts independently. Data analysis used constant comparative methods.

Results

Clinicians interviewed experienced audit and feedback as fragmented and variable in its effectiveness. Moreover, clinicians felt disconnected from the process. The audit process was perceived as being insufficiently transparent. Feedback was often untimely, incomplete and not actionable. Specific groups such as respiratory therapists and night-shift clinicians felt marginalised. Suggestions for improvement included improving information sharing about the rationale for change and the audit process, tools and metrics; implementing peer-to-peer quality discussions to avoid a top-down approach (eg, incorporating feedback into discussions at daily rounds); providing effective feedback which contains specific, transparent and actionable information; delivering timely feedback (ie, balancing feedback proximate to events with trends over time) and increasing engagement by senior management.

Conclusions

ICU clinicians experience audit and feedback as fragmented communication with feedback being especially problematic. Attention to improving communication, integration of the process into daily clinical activities and making feedback timely, specific and actionable may increase the effectiveness of audit and feedback to affect desired change.
Nuclear and extranuclear effects of vitamin A
Authors: Iskakova Madina , Karbyshev Mikhail , Piskunov Aleksandr , Rochette-Egly Cécile
Published: April 2015

Vitamin A or retinol is a multifunctional vitamin that is essential at all stages of life from embryogenesis to adulthood. Up to now, it has been accepted that the effects of vitamin A are exerted by active metabolites, the major ones being 11-cis retinal for vision, and all trans-retinoic acid (RA) for cell growth and differentiation. Basically RA binds nuclear receptors, RARs, which regulate the expression of a battery of target genes in a ligand dependent manner. During the last decade, new scenarios have been discovered, providing a rationale for the understanding of other long-noted but not explained functions of retinol. These novel scenarios involve: (i) other nuclear receptors such as PPAR β/δ, which regulate the expression of other target genes with other functions; (ii) extranuclear and nontranscriptional effects, such as the activation of kinases, which phosphorylate RARs and other transcription factors, thus expanding the list of the RA-activated genes; (iii) finally, vitamin A is active per se and can work as a cytokine that regulates gene transcription by activating STRA6. New effects of vitamin A and RA are continuously being discovered in new fields, revealing new targets and new mechanisms thus improving the understanding the pleiotropicity of their effects.
The mechanical and thermodynamic properties of ZrAl2 under pressure from first-principles investigation
Authors: Wei Ning , Wang Xuefei , Zuo Xuzhong
Published: April 2015

The mechanical and thermodynamic properties of ZrAl2 alloy under high pressure are investigated by first-principles based on the density functional theory. Due to all the elastic constants of ZrAl2 alloy satisfy generalized stabilities criteria, ZrAl2 is mechanically stable under pressure up to 100[Formula: see text]GPa. By analyzing the value of B/G and Poisson’s ratio [Formula: see text] which are correlated with the ductility and brittleness of material, we found that ZrAl2 belongs to brittle material at pressure of 0–70[Formula: see text]GPa and will change from brittleness to ductility at 70[Formula: see text]GPa. Combining with high bulk modulus B and shear modulus G, the mechanical of properties will be improved under high pressure. Moreover, the thermodynamic properties, such as the Debye temperature [Formula: see text], heat capacity [Formula: see text] and thermal expansion [Formula: see text], are discussed using the quasi-harmonic Debye model. We noted that the Debye temperature [Formula: see text] is mainly dependent on the pressure and the effect of temperature on the heat capacity [Formula: see text] is more important than the applied pressure.
The effect of anchoring groups on the electro-optical and charge injection in triphenylamine derivatives@Ti6O12
Authors: Irfan Ahmad , Muhammad Shabbir , Al-Sehemi Abdullah G. , Al-Assiri M. S. , Kalam Abul , Chaudhry Aijaz Rasool
Published: April 2015

The triphenylamine (TPA), thiophene and pyrimidine are being used as efficient advanced functional semiconductor materials. In the present study, some new TPA donor–π–acceptor derivatives were designed where TPA moiety acts as donor, thiophene-pyrimidine π-bridge and acetic/cyanoacetic acid as acceptor. The ground-state geometries were optimized at B3LYP/6-31G** level of theory. The excitation energies and oscillator strengths were computed at TD-CAM-B3LYP/6-31G** (polarizable continuum model (PCM), in methanol) level of theory. The electronic, photophysical and charge transport properties were calculated wherever possible the computed values were compared with the available experimental as well as computational data. The electron injection (ΔGinject), relative electron injection [Formula: see text], electron coupling constants (∣VRP∣) and light harvesting efficiencies (LHE) have been calculated and compared with referenced compounds. The energies of the lowest unoccupied molecular orbitals (ELUMOs), diagonal bandgaps and energy level offsets were studied to shed light on the electron transport behavior. The effect of anchoring groups (acetic acid and cyanoacetic acid) was studied on the properties of interests in the dye and dye@ Ti6O12. It was observed that after interaction of dye with the TiO2cluster intra-molecular charge transport enhanced from HOMO of the dye to LUMO of the semiconductor cluster. The cyanoacetic acid anchoring group leads the superior LHE, ΔGinjectand ∣VRP∣ which might improve the solar cell performance.
The effect of phonon modes and electron–hole pair couplings on molecule–surface scattering processes
Authors: Mandal Souvik , Sahoo Tapas , Ghosh Sandip , Adhikari Satrajit
Published: April 2015

The effect of phonon modes and electron–hole pair (elhp) couplings at different surface temperature on D 2(v = 0, 1; j = 0)– Cu (111) collision has been explored by assuming weakly correlated interactions between molecular Degrees of Freedoms (DOFs) with surface modes and elhp excitations through a Hartree product type wavefunction, where the initial state distributions for the phonon modes and the elhp couplings are incorporated by using Bose–Einstein and Fermi–Dirac probability factors, respectively. We carry out four (4D⊗2D)- and six (6D)- dimensional quantum dynamics on such an effective Hamiltonian, and depict the calculated sticking/transition probabilities and energy transfer from molecule to the surface. The phonon modes slightly affect the sticking probability by broadening the profile, but the transition probability are substantially changed with respect to the rigid surface. On the contrary, the inclusion of elhp coupling along with phonon modes does not change the results much compared to the only phonon case.
On-Chip Universal Supervised Learning Methods for Neuro-Inspired Block of Memristive Nanodevices
Authors: Chabi Djaafar , Zhao Weisheng , Querlioz Damien , Klein Jacques-Olivier
Published: April 2015

Scaling down beyond CMOS transistors requires the combination of new computing paradigms and novel devices. In this context, neuromorphic architecture is developed to achieve robust and ultra-low power computing systems. Memristive nanodevices are often associated with this architecture to implement efficiently synapses for ultra-high density. In this article, we investigate the design of a neuro-inspired logic block (NLB) dedicated to on-chip function learning and propose learning strategy. It is composed of an array of memristive nanodevices as synapses associated to neuronal circuits. Supervised learning methods are proposed for different type of memristive nanodevices and simulations are performed to demonstrate the ability to learn logic functions with memristive nanodevices. Benefiting from a compact implementation of neuron circuits and the optimization of learning process, this architecture requires small number of nanodevices and moderate power consumption.
Decoding femininity in computer science in India
Authors: Varma Roli , Kapur Deepak
Published: April 2015

The benefits in school and the job market so far outweigh any potential gender bias that few women are deterred.
Managing your digital life
Authors: Abiteboul Serge , André Benjamin , Kaplan Daniel
Published: April 2015

Everyone should be able to manage their personal data with a personal information management system.
Degree Reduction in Labeled Graph Retrieval
Authors: Ullmann Julian R.
Published: April 2015

Within a given collection of graphs, a graph retrieval system may seek all graphs that contain a given graph, or may instead seek all graphs that are contained within a given graph. Although subgraph isomorphism is worst-case exponential, it may be average-case polynomial if graphs are labeled so as to restrict possible correspondences between vertices of included and includer graphs. Degree reduction is a procedure that uses logical inference to preclude some such correspondences, thereby substantially increasing the size of includer graphs that can be processed, without preventing any existent isomorphism from being found. Degree reduction works only with labeled graphs, which may be directed or undirected, with or without edge labels. Inexact or approximate isomorphism is accommodated by reducing strictness of conditions for perfect isomorphism. Disk-based degree reduction, which is an order of magnitude slower than memory-based degree reduction, has successfully processed graphs that have millions of vertices. Although the principle of degree reduction is simple and fundamental, its efficient practical implementation involves intricate procedural detail. Its average-case complexity analysis is currently intractable, so cost-benefit assessment has to be experimental.