bluuebunny/crossref_metadata_2025 huggingface dataset:
Papers of note in
Science Translational Medicine
Authors: Gough Nancy R.
Published: February 2016

This week’s articles feature an antibody for treating drug-resistant colon cancer and insights into circadian rhythms in aging.
Engineered cells to treat hyperthyroidism
Authors: Prabakaran Sudhakaran
Published: February 2016

Cells with engineered circuits maintain thyroid hormone balance in hyperthyroid mice.
Rewarded with active Rap1
Authors: Gough Nancy R.
Published: February 2016

Reward behaviors induced by cocaine involve activation of the GTPase Rap1 in medium spiny neurons of the striatum.
A “LINK” in triple-negative breast cancer
Authors: Wong Wei
Published: February 2016

A long noncoding RNA promotes the aberrant stabilization of HIF-1α under normoxic conditions in triple-negative breast cancer.
In Vitro
and
In Vivo
Trypanosomicidal Action of Novel Arylimidamides against Trypanosoma cruzi
Authors: Guedes-da-Silva F. H. , Batista D. G. J. , Meuser M. B. , Demarque K. C. , Fulco T. O. , Araújo J. S. , Da Silva P. B. , Da Silva C. F. , Patrick D. A. , Bakunova S. M. , Bakunov S. A. , Tidwell R. R. , Oliveira G. M. , Britto C. , Moreira O. C. , Soeiro M. N. C.
Published: February 2016

Arylimidamides (AIAs) have been shown to have considerable biological activity against intracellular pathogens, including
Trypanosoma cruzi
, which causes Chagas disease. In the present study, the activities of 12 novel bis-AIAs and 2 mono-AIAs against different strains of
T. cruzi
in vitro
and
in vivo
were analyzed. The most active was
m
-terphenyl bis-AIA (35DAP073), which had a 50% effective concentration (EC
50
) of 0.5 μM for trypomastigotes (Y strain), which made it 26-fold more effective than benznidazole (Bz; 13 μM). It was also active against the Colombiana strain (EC
50
= 3.8 μM). Analysis of the activity against intracellular forms of the Tulahuen strain showed that this bis-AIA (EC
50
= 0.04 μM) was about 100-fold more active than Bz (2 μM). The trypanocidal effect was dissociated from the ability to trigger intracellular lipid bodies within host cells, detected by oil red labeling. Both an active compound (35DAP073) and an inactive compound (26SMB060) displayed similar activation profiles. Due to their high selectivity indexes, two AIAs (35DAP073 and 35DAP081) were moved to
in vivo
studies, but because of the results of acute toxicity assays, 35DAP081 was excluded from the subsequent tests. The findings obtained with 35DAP073 treatment of infections caused by the Y strain revealed that 2 days of therapy induced a dose-dependent action, leading to 96 to 46% reductions in the level of parasitemia. However, the administration of 10 daily doses in animals infected with the Colombiana strain resulted in toxicity, preventing longer periods of treatment. The activity of the combination of 0.5 mg/kg of body weight/day 35DAP073 with 100 mg/kg/day Bz for 10 consecutive days was then assayed. Treatment with the combination resulted in the suppression of parasitemia, the elimination of neurological toxic effects, and survival of 100% of the animals. Quantitative PCR showed a considerable reduction in the parasite load (60%) compared to that achieved with Bz or the amidine alone. Our results support further investigations of this class with the aim of developing novel alternatives for the treatment of Chagas disease.
Dissecting the Structure-Function Relationship of a Fungicidal Peptide Derived from the Constant Region of Human Immunoglobulins
Authors: Ciociola Tecla , Pertinhez Thelma A. , Giovati Laura , Sperindè Martina , Magliani Walter , Ferrari Elena , Gatti Rita , D'Adda Tiziana , Spisni Alberto , Conti Stefania , Polonelli Luciano
Published: February 2016

Synthetic peptides encompassing sequences related to the complementarity-determining regions of antibodies or derived from their constant region (Fc peptides) were proven to exert differential antimicrobial, antiviral, antitumor, and/or immunomodulatory activities
in vitro
and/or
in vivo
, regardless of the specificity and isotype of the parental antibody. Alanine substitution derivatives of these peptides exhibited unaltered, increased, or decreased candidacidal activities
in vitro
. The bioactive IgG-derived Fc N10K peptide (NQVSLTCLVK) spontaneously self-assembles, a feature previously recognized as relevant for the therapeutic activity of another antibody-derived peptide. We evaluated the contribution of each residue to the peptide self-assembling capability by circular-dichroism spectroscopy. The interaction of the N10K peptide and its derivatives with
Candida albicans
cells was studied by confocal, transmission, and scanning electron microscopy. The apoptosis and autophagy induction profiles in yeast cells treated with the peptides were evaluated by flow cytometry, and the therapeutic efficacy against candidal infection was studied in a
Galleria mellonella
model. Overall, the results indicate a critical role for some residues in the self-assembly process and a correlation of that capability with the candidacidal activities of the peptides
in vitro
and their therapeutic effects
in vivo
.
Effects of Low-Dose Amoxicillin on Staphylococcus aureus USA300 Biofilms
Authors: Mlynek Kevin D. , Callahan Mary T. , Shimkevitch Anton V. , Farmer Jackson T. , Endres Jennifer L. , Marchand Mélodie , Bayles Kenneth W. , Horswill Alexander R. , Kaplan Jeffrey B.
Published: February 2016

Previous studies showed that sub-MIC levels of β-lactam antibiotics stimulate biofilm formation in most methicillin-resistant
Staphylococcus aureus
(MRSA) strains. Here, we investigated this process by measuring the effects of sub-MIC amoxicillin on biofilm formation by the epidemic community-associated MRSA strain USA300. We found that sub-MIC amoxicillin increased the ability of USA300 cells to attach to surfaces and form biofilms under both static and flow conditions. We also found that USA300 biofilms cultured in sub-MIC amoxicillin were thicker, contained more pillar and channel structures, and were less porous than biofilms cultured without antibiotic. Biofilm formation in sub-MIC amoxicillin correlated with the production of extracellular DNA (eDNA). However, eDNA released by amoxicillin-induced cell lysis alone was evidently not sufficient to stimulate biofilm. Sub-MIC levels of two other cell wall-active agents with different mechanisms of action—
d
-cycloserine and fosfomycin—also stimulated eDNA-dependent biofilm, suggesting that biofilm formation may be a mechanistic adaptation to cell wall stress. Screening a USA300 mariner transposon library for mutants deficient in biofilm formation in sub-MIC amoxicillin identified numerous known mediators of
S. aureus
β-lactam resistance and biofilm formation, as well as novel genes not previously associated with these phenotypes. Our results link cell wall stress and biofilm formation in MRSA and suggest that eDNA-dependent biofilm formation by strain USA300 in low-dose amoxicillin is an inducible phenotype that can be used to identify novel genes impacting MRSA β-lactam resistance and biofilm formation.
Low Concentrations of Nitric Oxide Modulate Streptococcus pneumoniae Biofilm Metabolism and Antibiotic Tolerance
Authors: Allan Raymond N. , Morgan Samantha , Brito-Mutunayagam Sanjita , Skipp Paul , Feelisch Martin , Hayes Stephen M. , Hellier William , Clarke Stuart C. , Stoodley Paul , Burgess Andrea , Ismail-Koch Hasnaa , Salib Rami J. , Webb Jeremy S. , Faust Saul N. , Hall-Stoodley Luanne
Published: February 2016

Streptococcus pneumoniae
is one of the key pathogens responsible for otitis media (OM), the most common infection in children and the largest cause of childhood antibiotic prescription. Novel therapeutic strategies that reduce the overall antibiotic consumption due to OM are required because, although widespread pneumococcal conjugate immunization has controlled invasive pneumococcal disease, overall OM incidence has not decreased. Biofilm formation represents an important phenotype contributing to the antibiotic tolerance and persistence of
S. pneumoniae
in chronic or recurrent OM. We investigated the treatment of pneumococcal biofilms with nitric oxide (NO), an endogenous signaling molecule and therapeutic agent that has been demonstrated to trigger biofilm dispersal in other bacterial species. We hypothesized that addition of low concentrations of NO to pneumococcal biofilms would improve antibiotic efficacy and that higher concentrations exert direct antibacterial effects. Unlike in many other bacterial species, low concentrations of NO did not result in
S. pneumoniae
biofilm dispersal. Instead, treatment of both
in vitro
biofilms and
ex vivo
adenoid tissue samples (a reservoir for
S. pneumoniae
biofilms) with low concentrations of NO enhanced pneumococcal killing when combined with amoxicillin-clavulanic acid, an antibiotic commonly used to treat chronic OM. Quantitative proteomic analysis using iTRAQ (isobaric tag for relative and absolute quantitation) identified 13 proteins that were differentially expressed following low-concentration NO treatment, 85% of which function in metabolism or translation. Treatment with low-concentration NO, therefore, appears to modulate pneumococcal metabolism and may represent a novel therapeutic approach to reduce antibiotic tolerance in pneumococcal biofilms.
Association of Novel Nonsynonymous Single Nucleotide Polymorphisms inampDwith Cephalosporin Resistance and Phylogenetic Variations inampC,ampR,ompF, andompCin Enterobacter cloacae Isolates That Are Highly Resistant to Carbapenems
Authors: Babouee Flury Baharak , Ellington Matthew J. , Hopkins Katie L. , Turton Jane F. , Doumith Michel , Loy Richard , Staves Peter , Hinic Vladimira , Frei Reno , Woodford Neil
Published: February 2016

InEnterobacter cloacae, the genetic lesions associated with derepression of the AmpC β-lactamase include diverse single nucleotide polymorphisms (SNPs) and/or indels in theampDandampRgenes and SNPs inampC, while diverse SNPs in the promoter region or SNPs/indels within the coding sequence of outer membrane proteins have been described to alter porin production leading to carbapenem resistance. We sought to define the underlying mechanisms conferring cephalosporin and carbapenem resistance in a collection ofE. cloacaeisolates with unusually high carbapenem resistance and no known carbapenemase and, in contrast to many previous studies, considered the SNPs we detected in relation to the multilocus sequence type (MLST)-based phylogeny of our collection. Whole-genome sequencing was applied on the most resistant isolates to seek novel carbapenemases, expression ofampCwas measured by reverse transcriptase PCR, and porin translation was detected by SDS-PAGE. SNPs occurring inampC,ampR,ompF, andompCgenes (and their promoter regions) were mostly phylogenetic variations, relating to the isolates' sequence types, whereas nonsynonymous SNPs inampDwere associated with derepression of AmpC and cephalosporin resistance. The additional loss of porins resulted in high-level carbapenem resistance, underlining the clinical importance of chromosomal mutations among carbapenem-resistantE. cloacae.
Landscape of Resistance-Nodulation-Cell Division (RND)-Type Efflux Pumps in Enterobacter cloacae Complex
Authors: Guérin François , Lallement Claire , Isnard Christophe , Dhalluin Anne , Cattoir Vincent , Giard Jean-Christophe
Published: February 2016

In Gram-negative bacteria, the active efflux is an important mechanism of antimicrobial resistance, but little is known about the
Enterobacter cloacae
complex (ECC). It is mediated primarily by pumps belonging to the RND (resistance-nodulation-cell division) family, and only AcrB, part of the AcrAB-TolC tripartite system, was characterized in ECC. However, detailed genome sequence analysis of the strain
E. cloacae
subsp.
cloacae
ATCC 13047 revealed to us that 10 other genes putatively coded for RND-type transporters. We then characterized the role of all of these candidates by construction of corresponding deletion mutants, which were tested for their antimicrobial susceptibility to 36 compounds, their virulence in the invertebrate
Galleria mellonella
model of infection, and their ability to form biofilm. Only the Δ
acrB
mutant displayed significantly different phenotypes compared to that of the wild-type strain: 4- to 32-fold decrease of MICs of several antibiotics, antiseptics, and dyes, increased production of biofilm, and attenuated virulence in
G. mellonella
. In order to identify specific substrates of each pump, we individually expressed in
trans
all operons containing an RND pump-encoding gene into the Δ
acrB
hypersusceptible strain. We showed that three other RND-type efflux systems (ECL_00053-00055, ECL_01758-01759, and ECL_02124-02125) were able to partially restore the wild-type phenotype and to superadd to and even enlarge the broad range of antimicrobial resistance. This is the first global study assessing the role of all RND efflux pumps chromosomally encoded by the ECC, which confirms the major role of AcrB in both pathogenicity and resistance and the potential involvement of other RND-type members in acquired resistance.
Rapid Emergence and Evolution of Staphylococcus aureus Clones Harboring
fusC
-Containing Staphylococcal Cassette Chromosome Elements
Authors: Baines Sarah L. , Howden Benjamin P. , Heffernan Helen , Stinear Timothy P. , Carter Glen P. , Seemann Torsten , Kwong Jason C. , Ritchie Stephen R. , Williamson Deborah A.
Published: February 2016

The prevalence of fusidic acid (FA) resistance among
Staphylococcus aureus
strains in New Zealand (NZ) is among the highest reported globally, with a recent study describing a resistance rate of approximately 28%. Three FA-resistant
S. aureus
clones (ST5 MRSA, ST1 MSSA, and ST1 MRSA) have emerged over the past decade and now predominate in NZ, and in all three clones FA resistance is mediated by the
fusC
gene. In particular, ST5 MRSA has rapidly become the dominant MRSA clone in NZ, although the origin of FA-resistant ST5 MRSA has not been explored, and the genetic context of
fusC
in FA-resistant NZ isolates is unknown. To better understand the rapid emergence of FA-resistant
S. aureus
, we used population-based comparative genomics to characterize a collection of FA-resistant and FA-susceptible isolates from NZ. FA-resistant NZ ST5 MRSA displayed minimal genetic diversity and represented a phylogenetically distinct clade within a global population model of clonal complex 5 (CC5)
S. aureus
. In all lineages,
fusC
was invariably located within staphylococcal cassette chromosome (SCC) elements, suggesting that SCC-mediated horizontal transfer is the primary mechanism of
fusC
dissemination. The genotypic association of
fusC
with
mecA
has important implications for the emergence of MRSA clones in populations with high usage of fusidic acid. In addition, we found that
fusC
was colocated with a recently described virulence factor (
tirS
) in dominant NZ
S. aureus
clones, suggesting a fitness advantage. This study points to the likely molecular mechanisms responsible for the successful emergence and spread of FA-resistant
S. aureus
.
Derivation and Multicenter Validation of the Drug Resistance in Pneumonia Clinical Prediction Score
Authors: Webb Brandon J. , Dascomb Kristin , Stenehjem Edward , Vikram Holenarasipur R. , Agrwal Neera , Sakata Kenneth , Williams Kathryn , Bockorny Bruno , Bagavathy Kavitha , Mirza Shireen , Metersky Mark , Dean Nathan C.
Published: February 2016

The health care-associated pneumonia (HCAP) criteria have a limited ability to predict pneumonia caused by drug-resistant bacteria and favor the overutilization of broad-spectrum antibiotics. We aimed to derive and validate a clinical prediction score with an improved ability to predict the risk of pneumonia due to drug-resistant pathogens compared to that of HCAP criteria. A derivation cohort of 200 microbiologically confirmed pneumonia cases in 2011 and 2012 was identified retrospectively. Risk factors for pneumonia due to drug-resistant pathogens were evaluated by logistic regression, and a novel prediction score (the drug resistance in pneumonia [DRIP] score) was derived. The score was then validated in a prospective, observational cohort of 200 microbiologically confirmed cases of pneumonia at four U.S. centers in 2013 and 2014. The DRIP score (area under the receiver operator curve [AUROC], 0.88 [95% confidence interval {CI}, 0.82 to 0.93]) performed significantly better (
P
= 0.02) than the HCAP criteria (AUROC, 0.72 [95% CI, 0.64 to 0.79]). At a threshold of ≥4 points, the DRIP score demonstrated a sensitivity of 0.82 (95% CI, 0.67 to 0.88), a specificity of 0.81 (95% CI, 0.73 to 0.87), a positive predictive value (PPV) of 0.68 (95% CI, 0.56 to 0.78), and a negative predictive value (NPV) of 0.90 (95% CI, 0.81 to 0.93). By comparison, the performance of HCAP criteria was less favorable: sensitivity was 0.79 (95% CI, 0.67 to 0.88), specificity was 0.65 (95% CI, 0.56 to 0.73), PPV was 0.53 (95% CI, 0.42 to 0.63), and NPV was 0.86 (95% CI, 0.77 to 0.92). The overall accuracy of the HCAP criteria was 69.5% (95% CI, 62.5 to 75.7%), whereas that of the DRIP score was 81.5% (95% CI, 74.2 to 85.6%) (
P
= 0.005). Unnecessary extended-spectrum antibiotics were recommended 46% less frequently by applying the DRIP score (25/200, 12.5%) than by use of HCAP criteria (47/200, 23.5%) (
P
= 0.004), without increasing the rate at which inadequate treatment recommendations were made. The DRIP score was more predictive of the risk of pneumonia due to drug-resistant pathogens than HCAP criteria and may have the potential to decrease antibiotic overutilization in patients with pneumonia. Validation in larger cohorts of patients with pneumonia due to all causes is necessary.
Optimizing the Clinical Use of Vancomycin
Authors: Álvarez Rocío , López Cortés Luis E. , Molina José , Cisneros José M. , Pachón Jerónimo
Published: February 2016

The increasing number of infections produced by beta-lactam–resistant Gram-positive bacteria and the morbidity secondary to these infections make it necessary to optimize the use of vancomycin. In 2009, the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Disease Pharmacists published specific guidelines about vancomycin dosage and monitoring. However, these guidelines have not been updated in the past 6 years. This review analyzes the new available information about vancomycin published in recent years regarding pharmacokinetics and pharmacodynamics, serum concentration monitoring, and optimal vancomycin dosing in special situations (obese people, burn patients, renal replacement therapy, among others). Vancomycin efficacy is linked to a correct dosage which should aim to reach an area under the curve (AUC)/MIC ratio of ≥400; serum trough levels of 15 to 20 mg/liter are considered a surrogate marker of an AUC/MIC ratio of ≥400 for a MIC of ≤1 mg/liter. For
Staphylococcus aureus
strains presenting with a MIC >1 mg/liter, an alternative agent should be considered. Vancomycin doses must be adjusted according to body weight and the plasma trough levels of the drug. Nephrotoxicity has been associated with target vancomycin trough levels above 15 mg/liter. Continuous infusion is an option, especially for patients at high risk of renal impairment or unstable vancomycin clearance. In such cases, vancomycin plasma steady-state level and creatinine monitoring are strongly indicated.
Card9- and MyD88-Mediated Gamma Interferon and Nitric Oxide Production Is Essential for Resistance to Subcutaneous Coccidioides posadasii Infection
Authors: Hung Chiung-Yu , Castro-Lopez Natalia , Cole Garry T.
Published: February 2016

Coccidioidomycosis is a potentially life-threatening respiratory disease which is endemic to the southwestern United States and arid regions of Central and South America. It is responsible for approximately 150,000 infections annually in the United States alone. Almost every human organ has been reported to harbor parasitic cells of
Coccidioides
spp. in collective cases of the disseminated form of this mycosis. Current understanding of the mechanisms of protective immunity against lung infection has been largely derived from murine models of pulmonary coccidioidomycosis. However, little is known about the nature of the host response to
Coccidioides
in extrapulmonary tissue. Primary subcutaneous coccidioidal infection is rare but has been reported to result in disseminated disease. Here, we show that activation of MyD88 and Card9 signal pathways are required for resistance to
Coccidioides
infection following subcutaneous challenge of C57BL/6 mice, which correlates with earlier findings of the protective response to pulmonary infection.
MyD88
−/−
and
Card9
−/−
mice recruited reduced numbers of T cells, B cells, and neutrophils to the
Coccidioides
-infected hypodermis compared to wild-type mice; however, neutrophils were dispensable for resistance to skin infection. Further studies have shown that gamma interferon (IFN-γ) production and activation of Th1 cells characterize resistance to subcutaneous infection. Furthermore, activation of a phagosomal enzyme, inducible nitric oxide synthase, which is necessary for NO production, is a requisite for fungal clearance in the hypodermis. Collectively, our data demonstrate that MyD88- and Card9-mediated IFN-γ and nitric oxide production is essential for protection against subcutaneous
Coccidioides
infection.
Local Generation of Kynurenines Mediates Inhibition of Neutrophil Chemotaxis by Uropathogenic Escherichia coli
Authors: Loughman Jennifer A. , Yarbrough Melanie L. , Tiemann Kristin M. , Hunstad David A.
Published: February 2016

During epithelial infections, pathogenic bacteria employ an array of strategies to attenuate and evade host immune responses, including the influx of polymorphonuclear leukocytes (PMN; neutrophils). Among the most common bacterial infections in humans are those of the urinary tract, caused chiefly by uropathogenic
Escherichia coli
(UPEC). During the establishment of bacterial cystitis, UPEC suppresses innate responses via multiple independent strategies. We recently described UPEC attenuation of PMN trafficking to the urinary bladder through pathogen-specific local induction of indoleamine 2,3-dioxygenase (IDO), a tryptophan catabolic enzyme previously shown to have regulatory activity only in adaptive immunity. Here, we investigated the mechanism by which IDO induction attenuates PMN migration. Local tryptophan limitation, by which IDO is known to influence T cell longevity and proliferation, was not involved in its effect on PMN trafficking. Instead, metabolites in the IDO pathway, particularly
l
-kynurenine, directly suppressed PMN transepithelial migration and induced an attached, spread morphology in PMN both at rest and in the presence of chemotactic stimuli. Finally, kynurenines represent known ligands of the mammalian aryl hydrocarbon receptor (AHR), and UPEC infection of
Ahr
−/−
mice recapitulated the derepressed PMN recruitment observed previously in
Ido1
−/−
mice. UPEC therefore suppresses neutrophil migration early in bacterial cystitis by eliciting an IDO-mediated increase in local production of kynurenines, which act through the AHR to impair neutrophil chemotaxis.
Galectin-3 Plays an Important Role in Innate Immunity to Gastric Infection by Helicobacter pylori
Authors: Park Ah-Mee , Hagiwara Satoru , Hsu Daniel K. , Liu Fu-Tong , Yoshie Osamu
Published: February 2016

We studied the role of galectin-3 (Gal3) in gastric infection by
Helicobacter pylori
. We first demonstrated that Gal3 was selectively expressed by gastric surface epithelial cells and abundantly secreted into the surface mucus layer. We next inoculated
H. pylori
Sydney strain 1 into wild-type (WT) and Gal3-deficient mice using a stomach tube. At 2 weeks postinoculation, the bacterial cells were mostly trapped within the surface mucus layer in WT mice. In sharp contrast, they infiltrated deep into the gastric glands in Gal3-deficient mice. Bacterial loads in the gastric tissues were also much higher in Gal3-deficient mice than in WT mice. At 6 months postinoculation,
H. pylori
had successfully colonized within the gastric glands of both WT and Gal3-deficient mice, although the bacterial loads were still higher in the latter. Furthermore, large lymphoid clusters mostly consisting of B cells were frequently observed in the gastric submucosa of Gal3-deficient mice.
In vitro
, peritoneal macrophages from Gal3-deficient mice were inefficient in killing engulfed
H. pylori
. Furthermore, recombinant Gal3 not only induced rapid aggregation of
H. pylori
but also exerted a potent bactericidal effect on
H. pylori
as revealed by propidium iodide uptake and a morphological shift from spiral to coccoid form. However, a minor fraction of bacterial cells, probably transient phase variants of Gal3-binding sugar moieties, escaped killing by Gal3. Collectively, our data demonstrate that Gal3 plays an important role in innate immunity to infection and colonization of
H. pylori
.
Porphyromonas gingivalis Outer Membrane Vesicles Induce Selective Tumor Necrosis Factor Tolerance in a Toll-Like Receptor 4- and mTOR-Dependent Manner
Authors: Waller Tobias , Kesper Laura , Hirschfeld Josefine , Dommisch Henrik , Kölpin Johanna , Oldenburg Johannes , Uebele Julia , Hoerauf Achim , Deschner James , Jepsen Sören , Bekeredjian-Ding Isabelle
Published: February 2016

Porphyromonas gingivalis
is an important member of the anaerobic oral flora. Its presence fosters growth of periodontal biofilm and development of periodontitis. In this study, we demonstrated that lipophilic outer membrane vesicles (OMV) shed from
P. gingivalis
promote monocyte unresponsiveness to live
P. gingivalis
but retain reactivity to stimulation with bacterial DNA isolated from
P. gingivalis
or AIM2 ligand poly(dA·dT). OMV-mediated tolerance of
P. gingivalis
is characterized by selective abrogation of tumor necrosis factor (TNF). Neutralization of interleukin-10 (IL-10) during OMV challenge partially restores monocyte responsiveness to
P. gingivalis
; full reactivity to
P. gingivalis
can be restored by inhibition of mTOR signaling, which we previously identified as the major signaling pathway promoting Toll-like receptor 2 and Toll-like receptor 4 (TLR2/4)-mediated tolerance in monocytes. However, despite previous reports emphasizing a central role of TLR2 in innate immune recognition of
P. gingivalis
, our current findings highlight a selective role of TLR4 in the promotion of OMV-mediated TNF tolerance: only blockade of TLR4—and not of TLR2—restores responsiveness to
P. gingivalis
. Of further note, OMV-mediated tolerance is preserved in the presence of cytochalasin B and chloroquine, indicating that triggering of surface TLR4 is sufficient for this effect. Taking the results together, we propose that
P. gingivalis
OMV contribute to local immune evasion of
P. gingivalis
by hampering the host response.
Dietary Omega-3 Fatty Acids Increase Survival and Decrease Bacterial Load in Mice Subjected to Staphylococcus aureus-Induced Sepsis
Authors: Svahn Sara L. , Ulleryd Marcus A. , Grahnemo Louise , Ståhlman Marcus , Borén Jan , Nilsson Staffan , Jansson John-Olov , Johansson Maria E.
Published: February 2016

Sepsis caused by
Staphylococcus aureus
is increasing in incidence. With the alarming use of antibiotics,
S. aureus
is prone to become methicillin resistant. Antibiotics are the only widely used pharmacological treatment for sepsis. Interestingly, mice fed high-fat diet (HFD) rich in polyunsaturated fatty acids have better survival of
S. aureus
-induced sepsis than mice fed HFD rich in saturated fatty acids (HFD-S). To investigate what component of polyunsaturated fatty acids, i.e., omega-3 or omega-6 fatty acids, exerts beneficial effects on the survival of
S. aureus
-induced sepsis, mice were fed HFD rich in omega-3 or omega-6 fatty acids for 8 weeks prior to inoculation with
S. aureus
. Further, mice fed HFD-S were treated with omega-3 fatty acid metabolites known as resolvins. Mice fed HFD rich in omega-3 fatty acids had increased survival and decreased bacterial loads compared to those for mice fed HFD-S after
S. aureus
-induced sepsis. Furthermore, the bacterial load was decreased in resolvin-treated mice fed HFD-S after
S. aureus
-induced sepsis compared with that in mice treated with vehicle. Dietary omega-3 fatty acids increase the survival of
S. aureus
-induced sepsis by reversing the deleterious effect of HFD-S on mouse survival.
Limitations of Murine Models for Assessment of Antibody-Mediated Therapies or Vaccine Candidates against Staphylococcus epidermidis Bloodstream Infection
Authors: Cole Leah E. , Zhang Jinrong , Kesselly Augustus , Anosova Natalie G. , Lam Hubert , Kleanthous Harry , Yethon Jeremy A.
Published: February 2016

Staphylococcus epidermidis
is normally a commensal colonizer of human skin and mucus membranes, but, due to its ability to form biofilms on indwelling medical devices, it has emerged as a leading cause of nosocomial infections. Bacteremia or bloodstream infection is a frequent and costly complication resulting from biofilm fouling of medical devices. Our goal was to develop a murine model of
S. epidermidis
infection to identify potential vaccine targets for the prevention of
S. epidermidis
bacteremia. However, assessing the contribution of adaptive immunity to protection against
S. epidermidis
challenge was complicated by a highly efficacious innate immune response in mice. Naive mice rapidly cleared
S. epidermidis
infections from blood and solid organs, even when the animals were immunocompromised. Cyclophosphamide-mediated leukopenia reduced the size of the bacterial challenge dose required to cause lethality but did not impair clearance after a nonlethal challenge. Nonspecific innate immune stimulation, such as treatment with a Toll-like receptor 4 (TLR4) agonist, enhanced bacterial clearance. TLR2 signaling was confirmed to accelerate the clearance of
S. epidermidis
bacteremia, but TLR2
−/−
mice could still resolve a bloodstream infection. Furthermore, TLR2 signaling played no role in the clearance of bacteria from the spleen. In conclusion, these data suggest that
S. epidermidis
bloodstream infection is cleared in a highly efficient manner that is mediated by both TLR2-dependent and -independent innate immune mechanisms. The inability to establish a persistent infection in mice, even in immunocompromised animals, rendered these murine models unsuitable for meaningful assessment of antibody-mediated therapies or vaccine candidates.
Mice with Genetic Deletion of Group VIA Phospholipase A
2
β Exhibit Impaired Macrophage Function and Increased Parasite Load in Trypanosoma cruzi-Induced Myocarditis
Authors: Sharma Janhavi , Blase Jennifer R. , Hoft Daniel F. , Marentette John O. , Turk John , McHowat Jane
Published: February 2016

Trypanosoma cruzi
infection, which is the etiological agent of Chagas disease, is associated with intense inflammation during the acute and chronic phases. The pathological progression of Chagas disease is influenced by the infiltration and transmigration of inflammatory cells across the endothelium to infected tissues, which are carefully regulated processes involving several molecular mediators, including adhesion molecules and platelet-activating factor (PAF). We have shown that PAF production is dependent upon calcium-independent group VIA phospholipase A
2
β (iPLA
2
β) following infection of human coronary artery endothelial cells (HCAECs) with
T. cruzi
, suggesting that the absence of iPLA
2
β may decrease the recruitment of inflammatory cells to the heart to manage parasite accumulation. Cardiac endothelial cells isolated from iPLA
2
β-knockout (iPLA
2
β-KO) mice infected with
T. cruzi
demonstrated decreased PAF production compared to that by cells isolated from wild-type (WT) mice but demonstrated increases in adhesion molecule expression similar to those seen in WT mice. Myocardial inflammation in iPLA
2
β-KO mice infected with
T. cruzi
was similar in severity to that in WT mice, but the iPLA
2
β-KO mouse myocardium contained more parasite pseudocysts. Upon activation, macrophages from iPLA
2
β-KO mice produced significantly less nitric oxide (NO) and caused less
T. cruzi
inhibition than macrophages from wild-type mice. Thus, the absence of iPLA
2
β activity does not influence myocardial inflammation, but iPLA
2
β is essential for
T. cruzi
clearance.
Molecular Characterization of the Vacuolating Autotransporter Toxin in Uropathogenic Escherichia coli
Authors: Nichols Katie B. , Totsika Makrina , Moriel Danilo G. , Lo Alvin W. , Yang Ji , Wurpel Daniël J. , Rossiter Amanda E. , Strugnell Richard A. , Henderson Ian R. , Ulett Glen C. , Beatson Scott A. , Schembri Mark A.
Published: February 2016

The vacuolating autotransporter toxin (Vat) contributes to uropathogenic
Escherichia coli
(UPEC) fitness during systemic infection. Here, we characterized Vat and investigated its regulation in UPEC. We assessed the prevalence of
vat
in a collection of 45 UPEC urosepsis strains and showed that it was present in 31 (68%) of the isolates. The isolates containing the
vat
gene corresponded to three major
E. coli
sequence types (ST12, ST73, and ST95), and these strains secreted the Vat protein. Further analysis of the
vat
genomic locus identified a conserved gene located directly downstream of
vat
that encodes a putative MarR-like transcriptional regulator; we termed this gene
vatX
. The
vat-vatX
genes were present in the UPEC reference strain CFT073, and reverse transcriptase PCR (RT-PCR) revealed that the two genes are cotranscribed. Overexpression of
vatX
in CFT073 led to a 3-fold increase in
vat
gene transcription. The
vat
promoter region contained three putative nucleation sites for the global transcriptional regulator histone-like nucleoid structuring protein (H-NS); thus, the
hns
gene was mutated in CFT073 (to generate CFT073
hns
). Western blot analysis using a Vat-specific antibody revealed a significant increase in Vat expression in CFT073
hns
compared to that in wild-type CFT073. Direct H-NS binding to the
vat
promoter region was demonstrated using purified H-NS in combination with electrophoresis mobility shift assays. Finally, Vat-specific antibodies were detected in plasma samples from urosepsis patients infected by
vat
-containing UPEC strains, demonstrating that Vat is expressed during infection. Overall, this study has demonstrated that Vat is a highly prevalent and tightly regulated immunogenic serine protease autotransporter protein of
Enterobacteriaceae
(SPATE) secreted by UPEC during infection.

IMPORTANCE
Uropathogenic
Escherichia coli
(UPEC) is the major cause of hospital- and community-acquired urinary tract infections. The vacuolating autotransporter toxin (Vat) is a cytotoxin known to contribute to UPEC fitness during murine sepsis infection. In this study, Vat was found to be highly conserved and prevalent among a collection of urosepsis clinical isolates and was expressed at human core body temperature. Regulation of
vat
was demonstrated to be directly repressed by the global transcriptional regulator H-NS and upregulated by the downstream gene
vatX
(encoding a new MarR-type transcriptional regulator). Additionally, increased Vat-specific IgG titers were detected in plasma from corresponding urosepsis patients infected with
vat
-positive isolates. Hence, Vat is a highly conserved and tightly regulated urosepsis-associated virulence factor.
WrpA Is an Atypical Flavodoxin Family Protein under Regulatory Control of the Brucella abortus General Stress Response System
Authors: Herrou Julien , Czyż Daniel M. , Willett Jonathan W. , Kim Hye-Sook , Chhor Gekleng , Babnigg Gyorgy , Kim Youngchang , Crosson Sean
Published: February 2016

The general stress response (GSR) system of the intracellular pathogenBrucella abortuscontrols the transcription of approximately 100 genes in response to a range of stress cues. The core genetic regulatory components of the GSR are required forB. abortussurvival under nonoptimal growth conditionsin vitroand for maintenance of chronic infection in anin vivomouse model. The functions of the majority of the genes in the GSR transcriptional regulon remain undefined.bab1_1070is among the most highly regulated genes in this regulon: its transcription is activated 20- to 30-fold by the GSR system under oxidative conditionsin vitro. We have solved crystal structures of Bab1_1070 and demonstrate that it forms a homotetrameric complex that resembles those of WrbA-type NADH:quinone oxidoreductases, which are members of the flavodoxin protein family. However,B. abortusWrbA-relatedprotein (WrpA) does not bind flavin cofactors with a high affinity and does not function as an NADH:quinone oxidoreductasein vitro. Soaking crystals with flavin mononucleotide (FMN) revealed a likely low-affinity binding site adjacent to the canonical WrbA flavin binding site. Deletion ofwrpA(ΔwrpA) does not compromise cell survival under acute oxidative stressin vitroor attenuate infection in cell-based or mouse models. However, a ΔwrpAstrain does elicit increased splenomegaly in a mouse model, suggesting that WrpA modulatesB. abortusinteraction with its mammalian host. Despite high structural homology with canonical WrbA proteins, we propose thatB. abortusWrpA represents a functionally distinct member of the diverse flavodoxin family.

IMPORTANCEBrucella abortusis an etiological agent of brucellosis, which is among the most common zoonotic diseases worldwide. The general stress response (GSR) regulatory system ofB. abortuscontrols the transcription of approximately 100 genes and is required for maintenance of chronic infection in a murine model; the majority of GSR-regulated genes remain uncharacterized. We presentin vitroandin vivofunctional and structural analyses of WrpA, whose expression is strongly induced by GSR under oxidative conditions. Though WrpA is structurally related to NADH:quinone oxidoreductases, it does not bind redox cofactors in solution, nor does it exhibit oxidoreductase activityin vitro. However, WrpA does affect spleen inflammation in a murine infection model. Our data provide evidence that WrpA forms a new functional class of WrbA/flavodoxin family proteins.
Bibliometric analysis of the top-cited gastroenterology and hepatology articles
Authors: Azer Samy A , Azer Sarah
Published: February 2016

Objective

To identify the top-cited articles in gastroenterology and hepatology, and analyse their characteristics.

Methods

Two searches were conducted in the Science Citation Index Expanded database; a search of 69 journals under the category ‘Gastroenterology and Hepatology’ (list A) and a keyword search of all journals (list B). The search results were analysed and the inter-rater coefficient of agreement between evaluators was measured using Cohen κ.

Results

The number of citations varied from 1049 to 2959 in list A and from 1929 to 5500 in list B. In both lists, the majority of articles were research papers. No significant correlations were found between the number of citations and the number of years since publication (R2=0.00992, p=0.473 and R2=0.00202, p=0.757, respectively). However, the mean number of citations of papers published before the year 2000 was lower than those published after 2000 (36.70±19.31 vs 106.03±39.22). No correlation was found between number of authors and the number of citations (R2=0.04352, p=0.130), but strong correlations were found between the number of institutes involved or number of countries and the number of citations (R2=0.275, p<0.001 and R2=0.16181, p=0.003, respectively). Females were under-represented in authorship (45 vs 254, p=0.004). Only 21 papers (of 54) in list A were supported by grants. No correlation was found between number of grants received and the number of citations (R2=0.02573, p=0.247). The inter-rater agreement between evaluators had a Cohen κ coefficient 0.76–0.84.

Conclusions

Top-cited articles were not only published in highly ranked journals specialising in Gastroenterology and Hepatology but also in 14 journals not specialised in this field. The number of citations correlated with the number of institutes and the number of countries involved but not with the number of grants received or the number of authors. Females were under-represented in the authorship.
Social inequalities in prevalence of diagnosed and undiagnosed diabetes and impaired glucose regulation in participants in the Health Surveys for England series
Authors: Moody Alison , Cowley Giovanna , Ng Fat Linda , Mindell Jennifer S
Published: February 2016

Objectives

To ascertain the extent of socioeconomic and health condition inequalities in people with diagnosed and undiagnosed diabetes and impaired glucose regulation (IGR) in random samples of the general population in England, as earlier diagnosis of diabetes and treatment of people with IGR can reduce adverse sequelae of diabetes. Various screening instruments were compared to identify IGR, in addition to undiagnosed diabetes.

Design

5, annual cross-sectional health examination surveys; data adjusted for complex survey design.

Setting

Random selection of private homes across England, new sample annually 2009–2013.

Participants

5, nationally representative random samples of the general, free-living population: ≥1 adult interviewed in 24 254 of 36 889 eligible addresses selected. 18 399 adults had a valid glycated haemoglobin (HbA1c) measurement and answered the diabetes questions.

Main outcome measures

Diagnosed diabetes, undiagnosed diabetes (HbA1c ≥48 mmol/mol), IGR (HbA1c 42–47 mmol/mol).

Results

Overall, 11% of the population had IGR, 2% undiagnosed and 6% diagnosed diabetes. Age-standardised prevalence was highest among Asian (19% (95% CI 16% to 23%), 3% (2% to 5%) and 12% (9% to 16%) respectively) and black participants (17% (13% to 21%), 2% (1% to 4%) and 14% (9% to 20%) respectively). These were also higher among people with lower income, less education, lower occupational class and greater deprivation. Education (OR 1.49 (95% CI 1.27 to 1.74) for no qualifications vs degree or higher) and income (1.35 (1.12 to 1.62) for lowest vs highest income quintile) remained significantly associated with IGR or undiagnosed diabetes on multivariate regression. The greatest odds of IGR or undiagnosed diabetes were with increasing age over 34 years (eg, OR 18.69 (11.53 to 30.28) aged 65–74 vs 16–24). Other significant associations were ethnic group (Asian (3.91 (3.02 to 5.05)), African-American (2.34 (1.62 to 3.38)) or ‘other’ (2.04 (1.07 to 3.88)) vs Caucasian); sex (OR 1.32(1.19 to 1.46) for men vs women); body mass index (3.54 (2.52 to 4.96) for morbidly obese vs not overweight); and waist circumference (2.00 (1.67 to 2.38) for very high vs low).

Conclusions

Social inequalities in hyperglycaemia exist, additional to well-known demographic and anthropometric risk factors for diabetes and IGR.
Introduction of a junior doctors' handbook: an essential guide for new doctors
Authors: Ross Daniella , Petrie Claire , Tully Vicki
Published: February 2016

The transition period for new junior doctors is a daunting and challenging time, as vast amounts of information specific to each hospital, ward, and job must be learnt while maintaining patient care standards.[1] In NHS Tayside, Scotland, tips and guidance for each job are informally handed over from previous junior doctors to the next, resulting in an unreliable and unsustainable handover of information. Time must then be spent by new doctors learning the intricacies and practicalities of their new job, rather than spending time focusing on patient care.

Our aim was to improve this transition period for new junior doctors to NHS Tayside through the creation and implementation of a junior doctors' handbook, which would provide information and practical advice on day to day life as a junior doctor. We hoped to implement this project by August 2015 to coincide with the arrival of these new doctors to NHS Tayside. Through repeat PDSA cycles we created a sustainable and reliable junior doctors' handbook, containing a centralised hub of information for doctors that was accessible through our health board’s website. The junior doctors' handbook has been a highly beneficial resource that has been praised for its detailed information on all aspects of day to day life for doctors in NHS Tayside. Feedback also demonstrated that doctors felt the junior doctors' handbook had improved their efficiency. Our hope is that this project can continue to be developed within our hospital, but also to be used as an idea outside our health board to improve the transition period for new doctors on a wider scale.
Clinical, ECG and echocardiographic clues to the diagnosis of TTR-related cardiomyopathy
Authors: Damy Thibaud , Maurer Mathew S , Rapezzi Claudio , Planté-Bordeneuve Violaine , Karayal Onur N , Mundayat Rajiv , Suhr Ole B , Kristen Arnt V
Published: February 2016

Background

Signs of cardiac transthyretin (TTR) amyloidosis (ATTR) in patients with echocardiographic increase in interventricular septal thickness (IVST) are lacking.

Objectives

To identify clinical and ECG/echocardiographic signs associated with increased IVST in ATTR.

Methods

Analysis of patients with baseline echocardiography in the Transthyretin Amyloidosis Outcomes Survey (THAOS) registry (N=1682). Patients were categorised into IVST classes according to the American Society of Echocardiography classification adapted to gender (ie, normal, mild, moderate, severe); then into two combined IVST classes (normal-mild and moderate-severe).

Results

425 patients were included: 336 with a TTR mutation (m-TTR) and 89 with wild-type TTR (WT-TTR). 72% were men. Median (25th, 75th centile) age was 62 (45, 72) years. Non-Val30Met and WT-TTR were frequent in moderate (41% and 35%) and severe (50% and 33%) IVST classes. Median IVST was 15 mm (14, 16) (moderate) and 20 mm (18, 22) (severe). In the combined moderate-severe class, 85% of patients were ≥55 years of age; 81% were men; 86% had blood pressure <140 mm Hg; and 77% had increased right ventricle thickness (≥7 mm). Up to 66% of patients had cardiac sparkling. Systolic dysfunction (left ventricular ejection fraction <50%), restrictive pattern and low voltage were less frequent, and observed in 49%, 18% and 33% of patients, respectively.

Conclusions

Increased IVST, especially in men ≥55 years with normal systolic blood pressure, increase in right ventricle free wall and valve thicknesses, and sparkling, should alert practitioners to the possibility of ATTR. Absence of restrictive pattern and low voltage should not rule out the suspicion.

Trial registration number:

NCT00628745 (clinicaltrials.gov).