bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical Activity Trajectories During Daily Middle School Physical Education
Authors: Burns Ryan D. , Brusseau Timothy A. , Hannon James C. 
Published: September 2014

Background:Optimal levels of moderate-to-vigorous physical activity (MVPA) have been shown to improve health and academic outcomes in youth. Limited research has examined MVPA trajectories throughout a daily middle school physical education (PE) curriculum. The purpose of this study was to examine MVPA trajectories over a daily PE curriculum and the modifying effects of sex, body composition, and cardiorespiratory endurance.Methods:One hundred 7th- and 8th-grade students participated in daily PE lessons. There were 66 lessons throughout the semester. MVPA was monitored during each lesson using NL-1000 piezoelectric pedometers. Students were classified into FITNESSGRAM Healthy Fitness Zones using estimated VO2 Max and Body Mass Index (BMI). A population averaged generalized estimating equation was employed to examine MVPA trajectories.Results:On average, students’ MVPA decreased over time (β = –0.35, P < .001). Poor student VO2max classification significantly modified the trajectories (β = –0.14, P < .001), however poor BMI classification did not have a modifying effect (β = 0.03, P = .158).Conclusions:MVPA decreased in daily PE over time and cardiorespiratory endurance significantly modified the trajectories. The results support that extra efforts have to be made by teachers and students to sustain MVPA behaviors over a semester.
Ramoplanin at Bactericidal Concentrations Induces Bacterial Membrane Depolarization in Staphylococcus aureus
Authors: Cheng Mu , Huang Johnny X. , Ramu Soumya , Butler Mark S. , Cooper Matthew A. 
Published: September 2014

ABSTRACT

Ramoplanin is an actinomycetes-derived antibiotic with broad-spectrum activity against Gram-positive bacteria that has been evaluated in clinical trials for the treatment of gastrointestinal vancomycin-resistant enterococci (VRE) and
Clostridium difficile
infections. Recent studies have proposed that ramoplanin binds to bacterial membranes as a C
2
symmetrical dimer that can sequester Lipid II, which causes inhibition of cell wall peptidoglycan biosynthesis and cell death. In this study, ramoplanin was shown to bind to anionic and zwitterionic membrane mimetics with a higher affinity for anionic membranes and to induce membrane depolarization of methicillin-susceptible
Staphylococcus aureus
(MSSA) ATCC 25923 at concentrations at or above the minimal bactericidal concentration (MBC). The ultrastructural effects of ramoplanin on
S. aureus
were also examined by transmission electron microscopy (TEM), and this showed dramatic changes to bacterial cell morphology. The correlation observed between membrane depolarization and bacterial cell viability suggests that this mechanism may contribute to the bactericidal activity of ramoplanin.
Integron-Borne Transmission of VEB-1 Extended-Spectrum β-Lactamase in Pseudomonas aeruginosa in a Tertiary Care Hospital in India
Authors: Maurya Anand Prakash , Talukdar Anupam Das , Chanda Debadatta Dhar , Chakravarty Atanu , Bhattacharjee Amitabha 
Published: September 2014

ABSTRACT

A total 14 clinical isolates of
Pseudomonas aeruginosa
that produced VEB-1 and were susceptible only to polymyxin B were recovered from hospitalized patients. VEB-1 was located within variable regions of the class 1 integron, flanked by resistant genes, and was horizontally transferable as well as carried within the IncP-type plasmid. We conclude that the IncP-type plasmid is responsible for the horizontal transmission of VEB-1-mediated expanded-spectrum cephalosporin resistance in this medical center.
EnhancedIn VitroFormation and Antibiotic Resistance of Nonattached Pseudomonas aeruginosa Aggregates through Incorporation of Neutrophil Products
Authors: Caceres Silvia M. , Malcolm Kenneth C. , Taylor-Cousar Jennifer L. , Nichols David P. , Saavedra Milene T. , Bratton Donna L. , Moskowitz Samuel M. , Burns Jane L. , Nick Jerry A. 
Published: September 2014

ABSTRACTPseudomonas aeruginosais a major pathogen in cystic fibrosis (CF) lung disease. Children with CF are routinely exposed toP. aeruginosafrom the natural environment, and by adulthood, 80% of patients are chronically infected.P. aeruginosain the CF airway exhibits a unique biofilm-like structure, where it grows in small clusters or aggregates of bacteria in association with abundant polymers of neutrophil-derived components F-actin and DNA, among other components. These aggregates differ substantially in size and appearance compared to surface-attachedin vitrobiofilm models classically utilized for studies but are believed to share properties of surface-attached biofilms, including antibiotic resistance. However, little is known about the formation and function of surface-independent modes of biofilm growth, how they might be eradicated, and quorum sensing communication. To address these issues, we developed a novelin vitromodel ofP. aeruginosaaggregates incorporating human neutrophil-derived products. Aggregates grownin vitroand those found in CF patients' sputum samples were morphologically similar; viable bacteria were distributed in small pockets throughout the aggregate. ThelasAquorum sensing gene was differentially expressed in the presence of neutrophil products. Importantly, aggregates formed in the presence of neutrophils acquired resistance to tobramycin, which was lost when the aggregates were dispersed with DNase, and antagonism of tobramycin and azithromycin was observed. This novel yet simplein vitrosystem advances our ability to model infection of the CF airway and will be an important tool to study virulence and test alternative eradication strategies againstP. aeruginosa.
Clinical Validation of the Analysis of Fluconazole in Oral Fluid in Hospitalized Children
Authors: van der Elst Kim C. M. , van Alst Manouche , Lub-de Hooge Marjolijn N. , van Hateren Kai , Kosterink Jos G. W. , Alffenaar Jan-Willem C. , Schölvinck Elisabeth H. 
Published: September 2014

ABSTRACT

Fluconazole is a first-line antifungal agent for the treatment and prophylaxis of invasive candidiasis in pediatric patients. Pediatric patients are at risk of suboptimal drug exposure, due to developmental changes in gastrointestinal and renal function, metabolic capacity, and volume of distribution. Therapeutic drug monitoring (TDM) can therefore be useful to prevent underexposure of fluconazole in children and infants. Children, however, often fear needles and can have difficult vascular access. The purpose of this study was to develop and clinically validate a method of analysis to determine fluconazole in oral fluid in pediatric patients. Twenty-one paired serum and oral fluid samples were obtained from 19 patients and were analyzed using a validated liquid chromatography-tandem mass spectrometry (LC–MS-MS) method after cross-validation between serum and oral fluid. The results were within accepted ranges for accuracy and precision, and samples were stable at room temperature for at least 17 days. A Pearson correlation test for the fluconazole concentrations in serum and oral fluid showed a correlation coefficient of 0.960 (
P
< 0.01). The mean oral fluid-to-serum concentration ratio was 0.99 (95% confidence interval [CI], 0.88 to 1.10) with Bland-Altman analysis. In conclusion, an oral fluid method of analysis was successfully developed and clinically validated for fluconazole in pediatric patients and can be a noninvasive, painless alternative to perform TDM of fluconazole when blood sampling is not possible or desirable. When patients receive prolonged courses of antifungal treatment and use fluconazole at home, this method of analysis can extend the possibilities of TDM for patients at home.
Effect of Suberoylanilide Hydroxamic Acid (SAHA) Administration on the Residual Virus Pool in a Model of Combination Antiretroviral Therapy-Mediated Suppression in SIVmac239-Infected Indian Rhesus Macaques
Authors: Del Prete Gregory Q. , Shoemaker Rebecca , Oswald Kelli , Lara Abigail , Trubey Charles M. , Fast Randy , Schneider Douglas K. , Kiser Rebecca , Coalter Vicky , Wiles Adam , Wiles Rodney , Freemire Brandi , Keele Brandon F. , Estes Jacob D. , Quiñones Octavio A. , Smedley Jeremy , Macallister Rhonda , Sanchez Rosa I. , Wai John S. , Tan Christopher M. , Alvord W. Gregory , Hazuda Daria J. , Piatak Michael , Lifson Jeffrey D. 
Published: September 2014

ABSTRACTNonhuman primate models are needed for evaluations of proposed strategies targeting residual virus that persists in HIV-1-infected individuals receiving suppressive combination antiretroviral therapy (cART). However, relevant nonhuman primate (NHP) models of cART-mediated suppression have proven challenging to develop. We used a novel three-class, six-drug cART regimen to achieve durable 4.0- to 5.5-log reductions in plasma viremia levels and declines in cell-associated viral RNA and DNA in blood and tissues of simian immunodeficiency virus SIVmac239-infected Indian-origin rhesus macaques, then evaluated the impact of treatment with the histone deacetylase inhibitor (HDACi) suberoylanilide hydroxamic acid (SAHA; Vorinostat) on the residual virus pool.Ex vivoSAHA treatment of CD4+T cells obtained from cART-suppressed animals increased histone acetylation and viral RNA levels in culture supernatants. cART-suppressed animals each received 84 total doses of oral SAHA. We observed SAHA dose-dependent increases in acetylated histones with evidence for sustained modulation as well as refractoriness following prolonged administration.In vivovirologic activity was demonstrated based on the ratio of viral RNA to viral DNA in peripheral blood mononuclear cells, a presumptive measure of viral transcription, which significantly increased in SAHA-treated animals. However, residual virus was readily detected at the end of treatment, suggesting that SAHA alone may be insufficient for viral eradication in the setting of suppressive cART. The effects observed were similar to emerging data for repeat-dose SAHA treatment of HIV-infected individuals on cART, demonstrating the feasibility, utility, and relevance of NHP models of cART-mediated suppression forin vivoassessments of AIDS virus functional cure/eradication approaches.
Random Mutagenesis of the Multidrug Transporter AcrB from Escherichia coli for Identification of Putative Target Residues of Efflux Pump Inhibitors
Authors: Schuster Sabine , Kohler Samay , Buck Annika , Dambacher Christine , König Armin , Bohnert Jürgen A. , Kern Winfried V. 
Published: September 2014

ABSTRACT

Efflux is an important mechanism of bacterial multidrug resistance (MDR), and the inhibition of MDR pumps by efflux pump inhibitors (EPIs) could be a promising strategy to overcome MDR. 1-(1-Naphthylmethyl)-piperazine (NMP) and phenylalanine-arginine-β-naphthylamide (PAβN) are model EPIs with activity in various Gram-negative bacteria expressing AcrB, the major efflux pump of
Escherichia coli
, or similar homologous pumps of the resistance-nodulation-cell division class. The aim of the present study was to generate
E. coli
AcrB mutants resistant to the inhibitory action of the two model EPIs and to identify putative EPI target residues in order to better understand mechanisms of pump inhibition. Using an
in vitro
random mutagenesis approach focusing on the periplasmic domain of AcrB, we identified the double mutation G141D N282Y, which substantially compromised the synergistic activity of NMP with linezolid, was associated with similar intracellular linezolid concentrations in the presence and absence of NMP, and did not impair the intrinsic MICs of various pump substrates and dye accumulation. We propose that these mutations near the outer face of the distal substrate binding pocket reduce NMP trapping. Other residues found to be relevant for efflux inhibition by NMP were G288 and A279, but mutations at these sites also changed the susceptibility to several pump substrates. Unlike with NMP, we were unable to generate AcrB periplasmic domain mutants with resistance or partial resistance to the EPI activity of PAβN, which is consistent with the modes of action of PAβN differing from those of NMP.
Mechanisms of Tigecycline Resistance among Klebsiella pneumoniae Clinical Isolates
Authors: Sheng Zi-Ke , Hu Fupin , Wang Weixia , Guo Qinglan , Chen Zhijun , Xu Xiaogang , Zhu Demei , Wang Minggui 
Published: September 2014

ABSTRACT

Of 26 tigecycline-nonsusceptible
Klebsiella pneumonia
e (TNSKP) clinical isolates, 25 had nonsynonymous mutations in
ramR
and/or
acrR
(23 in
ramR
and 10 in
acrR
). Eight TNSKP isolates possessed overexpression of
ramA
,
acrB
,
rarA
, and
oqxB
simultaneously, while 8 and 1 TNSKP strains had upregulation of
ramA
and
acrB
and of
rarA
and
oqxB
, respectively. Thus, resistance mechanisms of 9 TNSKP isolates cannot be explained by the present pathways. This study underscores the role of RamA in TNSKP and suggests the presence of novel tigecycline resistance mechanisms.
Molecular and Structural Basis for the Roles of Hepatitis C Virus Polymerase NS5B Amino Acids 15, 223, and 321 in Viral Replication and Drug Resistance
Authors: Lam Angela M. , Edwards Thomas E. , Mosley Ralph T. , Murakami Eisuke , Bansal Shalini , Lugo Christopher , Bao Haiying , Otto Michael J. , Sofia Michael J. , Furman Phillip A. 
Published: September 2014

ABSTRACT

Resistance to the 2′-F-2′-
C
-methylguanosine monophosphate nucleotide hepatitis C virus (HCV) inhibitors PSI-352938 and PSI-353661 was associated with a combination of amino acid changes (changes of S to G at position 15 [S15G], C223H, and V321I) within the genotype 2a nonstructural protein 5B (NS5B), an RNA-dependent RNA polymerase. To understand the role of these residues in viral replication, we examined the effects of single and multiple point mutations on replication fitness and inhibition by a series of nucleotide analog inhibitors. An acidic residue at position 15 reduced replicon fitness, consistent with its proximity to the RNA template. A change of the residue at position 223 to an acidic or large residue reduced replicon fitness, consistent with its proposed proximity to the incoming nucleoside triphosphate (NTP). A change of the residue at position 321 to a charged residue was not tolerated, consistent with its position within a hydrophobic cavity. This triple resistance mutation was specific to both genotype 2a virus and 2′-F-2′-
C
-methylguanosine inhibitors. A crystal structure of the NS5B S15G/C223H/V321I mutant of the JFH-1 isolate exhibited rearrangement to a conformation potentially consistent with short primer-template RNA binding, which could suggest a mechanism of resistance accomplished through a change in the NS5B conformation, which was better tolerated by genotype 2a virus than by viruses of other genotypes.
Rat Indwelling Urinary Catheter Model of Candida albicans Biofilm Infection
Authors: Nett Jeniel E. , Brooks Erin G. , Cabezas-Olcoz Jonathan , Sanchez Hiram , Zarnowski Robert , Marchillo Karen , Andes David R. 
Published: September 2014

ABSTRACT

Indwelling urinary catheters are commonly used in the management of hospitalized patients.
Candida
can adhere to the device surface and propagate as a biofilm. These
Candida
biofilm communities differ from free-floating
Candida
, exhibiting high tolerance to antifungal therapy. The significance of catheter-associated candiduria is often unclear, and treatment may be problematic considering the biofilm drug-resistant phenotype. Here we describe a rodent model for the study of urinary catheter-associated
Candida albicans
biofilm infection that mimics this common process in patients. In the setting of a functioning, indwelling urinary catheter in a rat,
Candida
proliferated as a biofilm on the device surface. Characteristic biofilm architecture was observed, including adherent, filamentous cells embedded in an extracellular matrix. Similar to what occurs in human patients, animals with this infection developed candiduria and pyuria. Infection progressed to cystitis, and a biofilmlike covering was observed over the bladder surface. Furthermore, large numbers of
C. albicans
cells were dispersed into the urine from either the catheter or bladder wall biofilm over the infection period. We successfully utilized the model to test the efficacy of antifungals, analyze transcriptional patterns, and examine the phenotype of a genetic mutant. The model should be useful for future investigations involving the pathogenesis, diagnosis, therapy, prevention, and drug resistance of
Candida
biofilms in the urinary tract.
Bicarbonate Increases Binding Affinity of Vibrio cholerae ToxT to Virulence Gene Promoters
Authors: Thomson Joshua J. , Withey Jeffrey H. 
Published: September 2014

ABSTRACT

The major
Vibrio cholerae
virulence gene transcription activator, ToxT, is responsible for the production of the diarrhea-inducing cholera toxin (CT) and the major colonization factor, toxin coregulated pilus (TCP). In addition to the two primary virulence factors mentioned, ToxT is responsible for the activation of accessory virulence genes, such as
aldA
,
tagA
,
acfA
,
acfD
,
tcpI
, and
tarAB
. ToxT activity is negatively modulated by bile and unsaturated fatty acids found in the upper small intestine. Conversely, previous work identified another intestinal signal, bicarbonate, which enhances the ability of ToxT to activate production of CT and TCP. The work presented here further elucidates the mechanism for the enhancement of ToxT activity by bicarbonate. Bicarbonate was found to increase the activation of ToxT-dependent accessory virulence promoters in addition to those that produce CT and TCP. Bicarbonate is taken up into the
V. cholerae
cell, where it positively affects ToxT activity by increasing DNA binding affinity for the virulence gene promoters that ToxT activates regardless of toxbox configuration. The increase in ToxT binding affinity in the presence of bicarbonate explains the elevated level of virulence gene transcription.
Defect in the Formation of 70S Ribosomes Caused by Lack of Ribosomal Protein L34 Can Be Suppressed by Magnesium
Authors: Akanuma Genki , Kobayashi Ako , Suzuki Shota , Kawamura Fujio , Shiwa Yuh , Watanabe Satoru , Yoshikawa Hirofumi , Hanai Ryo , Ishizuka Morio 
Published: September 2014

ABSTRACT

To elucidate the biological functions of the ribosomal protein L34, which is encoded by the
rpmH
gene, the
rpmH
deletion mutant of
Bacillus subtilis
and two suppressor mutants were characterized. Although the Δ
rpmH
mutant exhibited a severe slow-growth phenotype, additional mutations in the
yhdP
or
mgtE
gene restored the growth rate of the Δ
rpmH
strain. Either the disruption of
yhdP
, which is thought to be involved in the efflux of Mg
2+
, or overexpression of
mgtE
, which plays a major role in the import of Mg
2+
, could suppress defects in both the formation of the 70S ribosome and growth caused by the absence of L34. Interestingly, the Mg
2+
content was lower in the Δ
rpmH
cells than in the wild type, and the Mg
2+
content in the Δ
rpmH
cells was restored by either the disruption of
yhdP
or overexpression of
mgtE. In vitro
experiments on subunit association demonstrated that 50S subunits that lacked L34 could form 70S ribosomes only at a high concentration of Mg
2+
. These results showed that L34 is required for efficient 70S ribosome formation and that L34 function can be restored partially by Mg
2+
. In addition, the Mg
2+
content was consistently lower in mutants that contained significantly reduced amounts of the 70S ribosome, such as the Δ
rplA
(L1) and Δ
rplW
(L23) strains and mutant strains with a reduced number of copies of the
rrn
operon. Thus, the results indicated that the cellular Mg
2+
content is influenced by the amount of 70S ribosomes.
Staphylococcus aureus Alters Growth Activity, Autolysis, and Antibiotic Tolerance in a Human Host-Adapted Pseudomonas aeruginosa Lineage
Authors: Michelsen Charlotte Frydenlund , Christensen Anne-Mette Juel , Bojer Martin Saxtorph , Høiby Niels , Ingmer Hanne , Jelsbak Lars 
Published: September 2014

ABSTRACT

Interactions among members of polymicrobial infections or between pathogens and the commensal flora may determine disease outcomes.
Pseudomonas aeruginosa
and
Staphylococcus aureus
are important opportunistic human pathogens and are both part of the polymicrobial infection communities in human hosts. In this study, we analyzed the
in vitro
interaction between
S. aureus
and a collection of
P. aeruginosa
isolates representing different evolutionary steps of a dominant lineage, DK2, that have evolved through decades of growth in chronically infected patients. While the early adapted
P. aeruginosa
DK2 strains outcompeted
S. aureus
during coculture on agar plates, we found that later
P. aeruginosa
DK2 strains showed a commensal-like interaction, where
S. aureus
was not inhibited by
P. aeruginosa
and the growth activity of
P. aeruginosa
was enhanced in the presence of
S. aureus
. This effect is mediated by one or more extracellular
S. aureus
proteins greater than 10 kDa, which also suppressed
P. aeruginosa
autolysis and prevented killing by clinically relevant antibiotics through promoting small-colony variant (SCV) formation. The commensal interaction was abolished with
S. aureus
strains mutated in the
agr
quorum sensing system or in the SarA transcriptional virulence regulator, as well as with strains lacking the proteolytic subunit, ClpP, of the Clp protease. Our results show that during evolution of a dominant cystic fibrosis lineage of
P. aeruginosa
, a commensal interaction potential with
S. aureus
has developed.
The Cysteine Desulfhydrase CdsH Is Conditionally Required for Sulfur Mobilization to the Thiamine Thiazole in Salmonella enterica
Authors: Palmer Lauren D. , Leung Man Him , Downs Diana M. 
Published: September 2014

ABSTRACT

Thiamine pyrophosphate is a required coenzyme that contains a mechanistically important sulfur atom. In
Salmonella enterica
, sulfur is trafficked to both thiamine biosynthesis and 4-thiouridine biosynthesis by the enzyme ThiI using persulfide (R-S-S-H) chemistry. It was previously reported that a
thiI
mutant strain could grow independent of exogenous thiamine in the presence of cysteine, suggesting there was a second mechanism for sulfur mobilization. Data reported here show that oxidation products of cysteine rescue the growth of a
thiI
mutant strain by a mechanism that requires the transporter YdjN and the cysteine desulfhydrase CdsH. The data are consistent with a model in which sulfide produced by CdsH reacts with cystine (Cys-S-S-Cys),
S
-sulfocysteine (Cys-S-SO
3
−
), or another disulfide to form a small-molecule persulfide (R-S-S-H). We suggest that this persulfide replaced ThiI by donating sulfur to the thiamine sulfur carrier protein ThiS. This model describes a potential mechanism used for sulfur trafficking in organisms that lack ThiI but are capable of thiamine biosynthesis.