bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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

ABSTRACT

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

ABSTRACTAmino 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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACT

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

ABSTRACTNAD-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

ABSTRACT

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

ABSTRACT

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.