bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mycobacterium tuberculosis Subculture Results in Loss of Potentially Clinically Relevant Heteroresistance
Authors: Metcalfe John Z. , Streicher Elizabeth , Theron Grant , Colman Rebecca E. , Penaloza Renee , Allender Christopher , Lemmer Darrin , Warren Robin M. , Engelthaler David M. 
Published: September 2017

ABSTRACT

Multidrug-resistant tuberculosis (TB) presents a major public health dilemma. Heteroresistance, the coexistence of drug-resistant and drug-susceptible strains or of multiple drug-resistant strains with discrete haplotypes, may affect accurate diagnosis and the institution of effective treatment. Subculture, or passage of cells onto fresh growth medium, is utilized to preserve
Mycobacterium tuberculosis
cell lines and is universally employed in TB diagnostics. The impact of such passages, typically performed in the absence of drug, on drug-resistant subpopulations is hypothesized to vary according to the competitive costs of genotypic resistance-associated variants. We applied ultradeep next-generation sequencing to 61 phenotypically rifampin-monoresistant (
n
= 17) and preextensively (
n
= 41) and extensively (
n
= 3) drug-resistant isolates with presumptive heteroresistance at two time points in serial subculture. We found significant dynamic loss of minor-variant resistant subpopulations across all analyzed resistance-determining regions, including eight isolates (13%) whose antibiogram data would have transitioned from resistant to susceptible for at least one drug through subculture. Surprisingly, some resistance-associated variants appeared to be selected for in subculture.
Protocol for Identifying Natural Agents That Selectively Affect Adhesion, Thickness, Architecture, Cellular Phenotypes, Extracellular Matrix, and Human White Blood Cell Impenetrability of Candida albicans Biofilms
Authors: Park Yang-Nim , Srikantha Thyagarajan , Daniels Karla J. , Jacob Melissa R. , Agarwal Ameeta K. , Li Xing-Cong , Soll David R. 
Published: September 2017

ABSTRACT

In the screening of natural plant extracts for antifungal activity, assessment of their effects on the growth of cells in suspension or in the wells of microtiter plates is expedient. However, microorganisms, including
Candida albicans
, grow in nature as biofilms, which are organized cellular communities with a complex architecture capable of conditioning their microenvironment, communicating, and excluding low- and high-molecular-weight molecules and white blood cells. Here, a confocal laser scanning microscopy (CLSM) protocol for testing the effects of large numbers of agents on biofilm development is described. The protocol assessed nine parameters from a single z-stack series of CLSM scans for each individual biofilm analyzed. The parameters included adhesion, thickness, formation of a basal yeast cell polylayer, hypha formation, the vertical orientation of hyphae, the hyphal bend point, pseudohypha formation, calcofluor white staining of the extracellular matrix (ECM), and human white blood cell impenetrability. The protocol was applied first to five plant extracts and derivative compounds and then to a collection of 88 previously untested plant extracts. They were found to cause a variety of phenotypic profiles, as was the case for 64 of the 88 extracts (73%). Half of the 46 extracts that did not affect biofilm thickness affected other biofilm parameters. Correlations between specific effects were revealed. The protocol will be useful not only in the screening of chemical libraries but also in the analysis of compounds with known effects and mutations.
Modulation of Staphylococcus aureus Response to Antimicrobials by the Candida albicans Quorum Sensing Molecule Farnesol
Authors: Kong Eric F. , Tsui Christina , Kucharíková Sona , Van Dijck Patrick , Jabra-Rizk Mary Ann 
Published: September 2017

ABSTRACT

In microbial biofilms, microorganisms utilize secreted signaling chemical molecules to coordinate their collective behavior. Farnesol is a quorum sensing molecule secreted by the fungal species
Candida albicans
and shown to play a central physiological role during fungal biofilm growth. Our pervious
in vitro
and
in vivo
studies characterized an intricate interaction between
C. albicans
and the bacterial pathogen
Staphylococcus aureus
, as these species coexist in biofilm. In this study, we aimed to investigate the impact of farnesol on
S. aureus
survival, biofilm formation, and response to antimicrobials. The results demonstrated that in the presence of exogenously supplemented farnesol or farnesol secreted by
C. albicans
in biofilm,
S. aureus
exhibited significantly enhanced tolerance to antimicrobials. By using gene expression studies,
S. aureus
mutant strains, and chemical inhibitors, the mechanism for the enhanced tolerance was attributed to upregulation of drug efflux pumps. Importantly, we showed that sequential exposure of
S. aureus
to farnesol generated a phenotype of high resistance to antimicrobials. Based on the presence of intracellular reactive oxygen species upon farnesol exposure, we hypothesize that antimicrobial tolerance in
S. aureus
may be mediated by farnesol-induced oxidative stress triggering the upregulation of efflux pumps, as part of a general stress response system. Hence, in mixed biofilms,
C. albicans
may influence the pathogenicity of
S. aureus
through acquisition of a drug-tolerant phenotype, with important therapeutic implications. Understanding interspecies signaling in polymicrobial biofilms and the specific drug resistance responses to secreted molecules may lead to the identification of novel targets for drug development.
Role of Activins in Hepcidin Regulation during Malaria
Authors: Spottiswoode Natasha , Armitage Andrew E. , Williams Andrew R. , Fyfe Alex J. , Biswas Sumi , Hodgson Susanne H. , Llewellyn David , Choudhary Prateek , Draper Simon J. , Duffy Patrick E. , Drakesmith Hal 
Published: September 2017

ABSTRACT

Epidemiological observations have linked increased host iron with malaria susceptibility, and perturbed iron handling has been hypothesized to contribute to the potentially life-threatening anemia that may accompany blood-stage malaria infection. To improve our understanding of these relationships, we examined the pathways involved in regulation of the master controller of iron metabolism, the hormone hepcidin, in malaria infection. We show that hepcidin upregulation in
Plasmodium berghei
murine malaria infection was accompanied by changes in expression of bone morphogenetic protein (BMP)/sons of mothers against decapentaplegic (SMAD) pathway target genes, a key pathway involved in hepcidin regulation. We therefore investigated known agonists of the BMP/SMAD pathway and found that
Bmp
gene expression was not increased in infection. In contrast, activin B, which can signal through the BMP/SMAD pathway and has been associated with increased hepcidin during inflammation, was upregulated in the livers of
Plasmodium berghei
-infected mice; hepatic activin B was also upregulated at peak parasitemia during infection with
Plasmodium chabaudi
. Concentrations of the closely related protein activin A increased in parallel with hepcidin in serum from malaria-naive volunteers infected in controlled human malaria infection (CHMI) clinical trials. However, antibody-mediated neutralization of activin activity during murine malaria infection did not affect hepcidin expression, suggesting that these proteins do not stimulate hepcidin upregulation directly. In conclusion, we present evidence that the BMP/SMAD signaling pathway is perturbed in malaria infection but that activins, although raised in malaria infection, may not have a critical role in hepcidin upregulation in this setting.
Hyperbiofilm Formation by Bordetella pertussis Strains Correlates with Enhanced Virulence Traits
Authors: Cattelan Natalia , Jennings-Gee Jamie , Dubey Purnima , Yantorno Osvaldo M. , Deora Rajendar 
Published: September 2017

ABSTRACT

Pertussis, or whooping cough, caused by the obligate human pathogen
Bordetella pertussis
is undergoing a worldwide resurgence. The majority of studies of this pathogen are conducted with laboratory-adapted strains which may not be representative of the species as a whole. Biofilm formation by
B. pertussis
plays an important role in pathogenesis. We conducted a side-by-side comparison of the biofilm-forming abilities of the prototype laboratory strains and the currently circulating isolates from two countries with different vaccination programs. Compared to the reference strain, all strains examined herein formed biofilms at high levels. Biofilm structural analyses revealed country-specific differences, with strains from the United States forming more structured biofilms. Bacterial hyperaggregation and reciprocal expression of biofilm-promoting and -inhibitory factors were observed in clinical isolates. An association of increased biofilm formation with augmented epithelial cell adhesion and higher levels of bacterial colonization in the mouse nose and trachea was detected. To our knowledge, this work links for the first time increased biofilm formation in bacteria with a colonization advantage in an animal model. We propose that the enhanced biofilm-forming capacity of currently circulating strains contributes to their persistence, transmission, and continued circulation.
Enterococcus faecalis Promotes Innate Immune Suppression and Polymicrobial Catheter-Associated Urinary Tract Infection
Authors: Tien Brenda Yin Qi , Goh Hwee Mian Sharon , Chong Kelvin Kian Long , Bhaduri-Tagore Soumili , Holec Sarah , Dress Regine , Ginhoux Florent , Ingersoll Molly A. , Williams Rohan B. H. , Kline Kimberly A. 
Published: September 2017

ABSTRACTEnterococcus faecalis, a member of the human gastrointestinal microbiota, is an opportunistic pathogen associated with hospital-acquired wound, bloodstream, and urinary tract infections.E. faecaliscan subvert or evade immune-mediated clearance, although the mechanisms are poorly understood. In this study, we examinedE. faecalis-mediated subversion of macrophage activation. We observed thatE. faecalisactively prevents NF-κB signaling in mouse RAW264.7 macrophages in the presence of Toll-like receptor agonists and during polymicrobial infection withEscherichia coli.E. faecalisandE. colicoinfection in a mouse model of catheter-associated urinary tract infection (CAUTI) resulted in a suppressed macrophage transcriptional response in the bladder compared to that withE. coliinfection alone. Finally, we demonstrated that coinoculation ofE. faecaliswith a commensal strain ofE. coliinto catheterized bladders significantly augmentedE. coliCAUTI. Taken together, these results support the hypothesis thatE. faecalissuppression of NF-κB-driven responses in macrophages promotes polymicrobial CAUTI pathogenesis, especially during coinfection with less virulent or commensalE. colistrains.
Stenotrophomonas maltophilia Serine Protease StmPr1 Induces Matrilysis, Anoikis, and Protease-Activated Receptor 2 Activation in Human Lung Epithelial Cells
Authors: DuMont Ashley L. , Cianciotto Nicholas P. 
Published: September 2017

ABSTRACT

Stenotrophomonas maltophilia
is an emerging, opportunistic nosocomial pathogen that can cause severe disease in immunocompromised individuals. We recently identified the StmPr1 and StmPr2 serine proteases to be the substrates of the Xps type II secretion system in
S. maltophilia
strain K279a. Here, we report that a third serine protease, StmPr3, is also secreted in an Xps-dependent manner. By constructing a panel of protease mutants in strain K279a, we were able to determine that StmPr3 contributes to the previously described Xps-mediated rounding and detachment of cells of the A549 human lung epithelial cell line as well as the Xps-mediated degradation of fibronectin, fibrinogen, and the cytokine interleukin-8 (IL-8). We also determined that StmPr1, StmPr2, and StmPr3 account for all Xps-mediated effects toward A549 cells and that StmPr1 contributes the most to Xps-mediated activities. Thus, we purified StmPr1 from the
S. maltophilia
strain K279a culture supernatant and evaluated the protease's activity toward A549 cells. Our analyses revealed that purified StmPr1 behaves more similarly to subtilisin than to trypsin. We also determined that purified StmPr1 likely induces cell rounding and detachment of A549 cells by targeting cell integrin-extracellular matrix connections (matrilysis) as well as adherence and tight junction proteins for degradation. In this study, we also identified anoikis as the mechanism by which StmPr1 induces the death of A549 cells and found that StmPr1 induces A549 IL-8 secretion via activation of protease-activated receptor 2. Altogether, these results suggest that the degradative and cytotoxic activities exhibited by StmPr1 may contribute to
S. maltophilia
pathogenesis in the lung by inducing tissue damage and inflammation.
Phenol-Soluble Modulin Peptides Contribute to Influenza A Virus-Associated Staphylococcus aureus Pneumonia
Authors: Bloes Dominik Alexander , Haasbach Emanuel , Hartmayer Carmen , Hertlein Tobias , Klingel Karin , Kretschmer Dorothee , Planz Oliver , Peschel Andreas 
Published: September 2017

ABSTRACTInfluenza A virus (IAV) infection is often followed by secondary bacterial lung infection, which is a major reason for severe, often fatal pneumonia. Community-associated methicillin-resistantStaphylococcus aureus(CA-MRSA) strains such as USA300 cause particularly severe and difficult-to-treat cases of IAV-associated pneumonia. CA-MRSA strains are known to produce extraordinarily large amounts of phenol-soluble modulin (PSM) peptides, which are important cytotoxins and proinflammatory molecules that contribute to several types ofS. aureusinfection. However, their potential role in pneumonia has remained elusive. We determined the impact of PSMs on human lung epithelial cells and found that PSMs are cytotoxic and induce the secretion of the proinflammatory cytokine interleukin-8 (IL-8) in these cells. Both effects were boosted by previous infection with the 2009 swine flu pandemic IAV H1N1 strain, suggesting that PSMs may contribute to lung inflammation and damage in IAV-associatedS. aureuspneumonia. Notably, the PSM-producing USA300 strain caused a higher mortality rate than did an isogenic PSM-deficient mutant in a mouse IAV-S. aureuspneumonia coinfection model, indicating that PSMs are major virulence factors in IAV-associatedS. aureuspneumonia and may represent important targets for future anti-infective therapies.
Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) RNAs in the Porphyromonas gingivalis CRISPR-Cas I-C System
Authors: Burmistrz Michal , Rodriguez Martinez Jose Ignacio , Krochmal Daniel , Staniec Dominika , Pyrc Krzysztof 
Published: September 2017

ABSTRACT

The CRISPR-Cas (clustered regularly interspaced short palindromic repeat–CRISPR-associated protein) system is unique to prokaryotes and provides the majority of bacteria and archaea with immunity against nucleic acids of foreign origin. CRISPR RNAs (crRNAs) are the key element of this system, since they are responsible for its selectivity and effectiveness. Typical crRNAs consist of a spacer sequence flanked with 5′ and 3′ handles originating from repeat sequences that are important for recognition of these small RNAs by the Cas machinery. In this investigation, we studied the type I-C CRISPR-Cas system in
Porphyromonas gingivalis
, a human pathogen associated with periodontitis, rheumatoid arthritis, cardiovascular disease, and aspiration pneumonia. We demonstrated the importance of the 5′ handle for crRNA recognition by the effector complex and consequently activity, as well as secondary trimming of the 3′ handle, which was not affected by modifications of the repeat sequence.

IMPORTANCE
Porphyromonas gingivalis
, a clinically relevant Gram-negative, anaerobic bacterium, is one of the major etiologic agents of periodontitis and has been linked with the development of other clinical conditions, including rheumatoid arthritis, cardiovascular disease, and aspiration pneumonia. The presented results on the biogenesis and functions of crRNAs expand our understanding of CRISPR-Cas cellular defenses in
P. gingivalis
and of horizontal gene transfer in bacteria.
Concussion knowledge and experience among Welsh amateur rugby union coaches and referees
Authors: Griffin Steffan Arthur , Ranson Craig , Moore Isabel , Mathema Prabhat 
Published: September 2017

BackgroundRugby union is a collision sport where participants are at high risk of sustaining a concussion. In settings where there is little qualified medical supervision, certain stakeholders (eg, coaches and officials) should possess sufficient knowledge in regard to the recognition and management of concussion.AimThe aim of this study was to assess the knowledge and experience of various aspects of concussion among coaches and referees involved in Welsh amateur rugby union.MethodsA questionnaire was distributed to 1843 coaches and 420 referees.ResultsA total of 333 coaches and 283 referees completed the questionnaire (18% and 68% response rates, respectively). Participants exhibited greater knowledge of concussion symptom recognition relative to knowledge of both the consequences of concussion and associated return-to-play protocols, both of which could be considered poor. There were no differences in knowledge levels between coaches and referees or between participants with or without a history of concussion. Two-thirds of participants incorrectly believed that headgear could prevent concussion, and nearly 30% of coaches reported having witnessed other coaches allowing a potentially concussed player to continue playing.ConclusionsIdentification of several misconceptions indicates that concussion management within Welsh amateur rugby union needs to be improved, warranting a multi-faceted educational intervention.
Molecular profile of nasopharyngeal carcinoma: analysing tumour suppressor gene promoter hypermethylation by multiplex ligation-dependent probe amplification
Authors: Ooft Marc L , van Ipenburg Jolique , van Loo Rob , de Jong Rick , Moelans Cathy , Braunius Weibel , de Bree Remco , van Diest Paul , Koljenović Senada , Baatenburg de Jong Rob , Hardillo Jose , Willems Stefan M 
Published: September 2017

AimsTo assess differences in methylation profiles, and thus pathogenesis, between Epstein-Barr virus (EBV)-positive and negative nasopharyngeal carcinomas (NPCs). Also, promoter hypermethylation is a common phenomenon in early carcinogenesis to inactivate tumour suppressor genes. Since epigenetic changes are reversible, the therapeutic application of methylation inhibitors could provide treatment options.MethodsWe evaluated promoter hypermethylation profiles of 22 common tumour suppressor genes in 108 NPCs using methylation-specific multiplex ligation-dependent probe amplification. Correlation between methylation, clinicopathological features (including EBV) and survival was examined. Cluster analysis was also performed.ResultsHypermethylation of RASSF1A and ESR1 was significantly more frequent in EBV-positive NPC, while hypermethylation of DAPK1 was more frequent in EBV-negative NPC. In logistic regression, age, with EBV-positive NPC occurring at earlier age, and RASSF1, with RASSF1 hypermethylation being more frequent in EBV-positive NPC, remained significant. In EBV-positive NPC, hypermethylation of RASSF1A predicted worse overall survival (OS) (HR 3.058,95% CI 1.027 to 9.107). In EBV-negative NPC, hypermethylated adenomatous polyposis coli (APC) was a predictor of poor disease-free survival (DFS) (HR 6.868, 95% CI 2.142 to 22.022).ConclusionThere are important epigenetic differences between EBV-negative and EBV-positive NPCs, with EBV-negative NPC having a more similar hypermethylation profile to other head and neck squamous cell carcinomas than EBV-positive NPC. Hypermethylation of RASSF1A might contribute to worse OS in EBV-positive NPC, and may be an important event in the pathogenesis of EBV-infected NPC. Hypermethylation of APC might contribute to worse DFS in EBV-negative NPC.
A review of 10 years of scapula injuries sustained by UK military personnel on operations
Authors: Roberts Darren C , Power D M , Stapley S A 
Published: September 2017

BackgroundScapula fractures are relatively uncommon injuries, mostly occurring due to the effects of high-energy trauma. Rates of scapula fractures are unknown in the military setting. The aim of this study is to analyse the incidence, aetiology, associated injuries, treatment and complications of these fractures occurring in deployed military personnel.MethodsAll UK military personnel returning with upper limb injuries from Afghanistan and Iraq were retrospectively reviewed using the Royal Centre for Defence Medicine database and case notes (2004–2014).ResultsForty-four scapula fractures out of 572 upper limb fractures (7.7%) were sustained over 10 years. Blast and gunshot wounds (GSW) were leading causative factors in 85%. Over half were open fractures (54%), with open blast fractures often having significant bone and soft tissue loss requiring extensive reconstruction. Multiple injuries were noted including lung, head, vascular and nerve injuries. Injury Severity Scores (ISS) were significantly higher than the average upper limb injury without a scapula fracture (p<0.0001). Brachial plexus injuries occurred in 17%. While military personnel with GSW have a favourable chance of nerve recovery, 75% of brachial plexus injuries that are associated with blast have poorer outcomes. Fixation occurred with either glenoid fractures or floating shoulders (10%); these were as a result of high velocity GSW or mounted blast ejections. There were no cases of deep soft tissue infection or osteomyelitis and all scapula fractures united.ConclusionScapula fractures have a 20 times higher incidence in military personnel compared with the civilian population, occurring predominantly as a result of blast and GSW, and a higher than average ISS. These fractures are often associated with multiple injuries, including brachial plexus injuries, where those sustained from blast have less favourable outcome. High rates of union following fixation and low rates of infection are expected despite significant contamination and soft tissue loss.
Field study on the safety and efficacy of intradermal versus intramuscular vaccination against Mycoplasma hyopneumoniae
Authors: Beffort Lisa , Weiß Christine , Fiebig Kerstin , Jolie Rika , Ritzmann Mathias , Eddicks Matthias 
Published: September 2017

The present study compares the safety and efficacy of a needle‐free, intradermal Mycoplasma hyopneumoniae vaccine to an intramuscular one. 420 piglets (21+3 days of age) were randomly assigned to two vaccination groups (intradermal vaccination V1 (n=138), intramuscular vaccination V2 (n=144)) and one unvaccinated control group (CG, n=138). As safety parameters clinical observations, local injection site reactions (ISR) and rectal temperatures were assessed. Average daily weight gain (ADWG) and pneumonic lung lesions (LL) were measured as efficacy parameters. ISRs were minor in V1. After both vaccinations, no adverse impact on appetite was observed and mean rectal temperatures remained within physiological range. ADWG during the fattening period was significantly higher in vaccinated groups (V1: 913.4 g, V2: 924.5 g) compared with CG (875.6 g). No differences in ADWG were observed between V1 and V2. Vaccinated pigs had a significantly reduced mean extent of LL compared with CG. V1 was superior in reducing the extent and prevalence of LL compared with V2. These results reveal that a needle‐free intradermal vaccination is safe and efficacious in reducing both the prevalence and extent of lung lesions, as well as in improving performance parameters, in a farrow‐to‐finish farm with a late onset of M hyopneumoniae infection.