bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic diversity, anti‐microbial resistance, plasmid profile and frequency of the Vi antigen in Salmonella Dublin strains isolated in Brazil
Authors: Vilela F. P. , Frazão M. R. , Rodrigues D. P. , Costa R. G. , Casas M. R. T. , Fernandes S. A. , Falcão J. P. , Campioni F. 
Published: September 2017

SummarySalmonella Dublin is strongly adapted to cattle causing enteritis and/or systemic disease with high rates of mortality. However, it can be sporadically isolated from humans, usually causing serious disease, especially in patients with underlying chronic diseases. The aim of this study was to molecularly type S. Dublin strains isolated from humans and animals in Brazil to verify the diversity of these strains as well as to ascertain possible differences between strains isolated from humans and animals. Moreover, the presence of the capsular antigen Vi and the plasmid profile was characterized in addition to the anti‐microbial resistance against 15 drugs. For this reason, 113 S. Dublin strains isolated between 1983 and 2016 from humans (83) and animals (30) in Brazil were typed by PFGE and MLVA. The presence of the capsular antigen Vi was verified by PCR, and the phenotypic expression of the capsular antigen was determined serologically. Also, a plasmid analysis for each strain was carried out. The strains studied were divided into 35 different PFGE types and 89 MLVA‐types with a similarity of ≥80% and ≥17.5%, respectively. The plasmid sizes found ranged from 2 to >150 kb and none of the strains studied presented the capsular antigen Vi. Resistance or intermediate resistance was found in 23 strains (20.3%) that were resistant to ampicillin, ciprofloxacin, chloramphenicol, imipenem, nalidixic acid, piperacillin, streptomycin and/or tetracycline. The majority of the S. Dublin strains studied and isolated over a 33‐year period may descend from a common subtype that has been contaminating humans and animals in Brazil and able to cause invasive disease even in the absence of the capsular antigen. The higher diversity of resistance phenotypes in human isolates, as compared with animal strains, may be a reflection of the different anti‐microbial treatments used to control S. Dublin infections in humans in Brazil.
The α2A‐adrenoceptor suppresses excitatory synaptic transmission to both excitatory and inhibitory neurons in layer 4 barrel cortex
Authors: Ohshima Minoru , Itami Chiaki , Kimura Fumitaka 
Published: September 2017

Key points
The effects of noradrenaline on excitatory synaptic transmission to regular spiking (excitatory) cells as well as regular spiking non‐pyramidal and fast spiking (both inhibitory) cells in cortical layer 4 were studied in thalamocortical slice preparations, focusing on vertical input from thalamus and layer 2/3 in the mouse barrel cortex.
Excitatory synaptic responses were suppressed by noradrenaline. However, currents induced by iontophoretically applied glutamate were not suppressed. Further, paired pulse ratio and coefficient of variation analysis indicated the site of action was presynaptic.
Pharmacological studies indicated that the suppression was mediated by the α2‐adrenoceptor.
Consistent with this, involvement of α2A‐adrenoceptor activation in the synaptic suppression in excitatory and inhibitory cells was confirmed by the use of α2A‐adrenoceptor knockout mice.
AbstractThe mammalian neocortex is widely innervated by noradrenergic (NA) fibres from the locus coeruleus. To determine the effects of NA on vertical synaptic inputs to layer 4 (L4) cells from the ventrobasal thalamus and layer 2/3 (L2/3), thalamocortical slices were prepared and whole‐cell recordings were made from L4 cells. Excitatory synaptic responses were evoked by electrical stimulation of the thalamus or L2/3 immediately above. Recorded cells were identified as regular spiking, regular spiking non‐pyramidal or fast spiking cells through their firing patterns in response to current injections. NA suppressed (∼50% of control) excitatory vertical inputs to all cell types in a dose‐dependent manner. The presynaptic site of action of NA was suggested by three independent studies. First, responses caused by iontophoretically applied glutamate were not suppressed by NA. Second, the paired pulse ratio was increased during NA suppression. Finally, a coefficient of variation (CV) analysis was performed and the resultant diagonal alignment of the ratio of CV−2 plotted against the ratio of the amplitude of postsynaptic responses suggests a presynaptic mechanism for the suppression. Experiments with phenylephrine (an α1‐agonist), prazosin (an α1‐antagonist), yohimbine (an α2‐antagonist) and propranolol (a β‐antagonist) indicated that suppression was mediated by the α2‐adrenoceptor. To determine whether the α2A‐adrenoceptor subtype was involved, α2A‐adrenoceptor knockout mice were used. NA failed to suppress EPSCs in all cell types, suggesting an involvement of the α2A‐adrenoceptor. Altogether, we concluded that NA suppresses vertical excitatory synaptic connections in L4 excitatory and inhibitory cells through the presynaptic α2A‐adrenoceptor.
Pharmacokinetics-Pharmacodynamics of CB-618 in Combination with Cefepime, Ceftazidime, Ceftolozane, or Meropenem: the Pharmacological Basis for a Stand-Alone β-Lactamase Inhibitor
Authors: Ambrose Paul G. , VanScoy Brian D. , Trang Michael , McCauley-Miller Jennifer , Conde Haley , Bhavnani Sujata M. , Alexander Dylan C. , Friedrich Lawrence V. 
Published: September 2017

ABSTRACT

A major challenge in treating patients is the selection of the “right” antibiotic regimen. Given that the optimal β-lactam/β-lactamase inhibitor pair is dependent upon the spectrum of β-lactamase enzymes produced and the frequency of resistance to the β-lactamase inhibitor, it might be useful if a stand-alone were available for the clinician to pair with the “right” β-lactam rather than only in a fixed combination. We describe herein a one-compartment
in vitro
infection model studies conducted to identify the magnitudes of the pharmacokinetic-pharmacodynamic (PK-PD) index for a β-lactamase inhibitor, CB-618, that would restore the activity of four β-lactam partner agents (cefepime, ceftazidime, ceftolozane, and meropenem) with various doses (1 or 2 g) and dosing intervals (8 or 12 h). The challenge panel included
Klebsiella pneumoniae
(
n
= 5),
Escherichia coli
(
n
= 2), and
Enterobacter cloacae
(
n
= 1) strains, which produced a wide variety of β-lactamase enzymes (AmpC, CTXM-15, KPC-2, KPC-3, FOX-5, OXA-1/30, OXA-48, SHV-1, SHV-11, SHV-27, and TEM-1). Free-drug human concentration-time profiles were simulated for each agent, and specimens were collected for drug concentration and bacterial density determinations. CB-618 restored the activity of each β-lactam partner. The magnitudes of the CB-618 ratio of the area under the concentration-time curve from 0 to 24 h to the MIC (i.e., the AUC/MIC ratio) associated with net bacterial stasis and 1- and 2-log
10
CFU/ml reductions from baseline at 24 h were 11.2, 32.9, and 136.3, respectively. These data may provide a PK-PD basis for the development of a stand-alone β-lactamase inhibitor.
Phasevarion-Regulated Virulence in the Emerging Pediatric Pathogen Kingella kingae
Authors: Srikhanta Yogitha N. , Fung Ka Yee , Pollock Georgina L. , Bennett-Wood Vicki , Howden Benjamin P. , Hartland Elizabeth L. 
Published: September 2017

ABSTRACT

Kingella kingae
is a common etiological agent of pediatric osteoarticular infections. While current research has expanded our understanding of
K. kingae
pathogenesis, there is a paucity of knowledge about host-pathogen interactions and virulence gene regulation. Many host-adapted bacterial pathogens contain phase variable DNA methyltransferases (
mod
genes), which can control expression of a regulon of genes (phasevarion) through differential methylation of the genome. Here, we identify a phase variable type III
mod
gene in
K. kingae
, suggesting that phasevarions operate in this pathogen. Phylogenetic studies revealed that there are two active
modK
alleles in
K. kingae
. Proteomic analysis of secreted and surface-associated proteins, quantitative PCR, and a heat shock assay comparing the wild-type
modK1
ON (i.e., in frame for expression) strain to a
modK1
OFF (i.e., out of frame) strain revealed three virulence-associated genes under ModK1 control. These include the
K. kingae
toxin
rtxA
and the heat shock genes
groEL
and
dnaK
. Cytokine expression analysis showed that the interleukin-8 (IL-8), IL-1β, and tumor necrosis factor responses of THP-1 macrophages were lower in the
modK1
ON strain than in the
modK1
::
kan
mutant. This suggests that the ModK1 phasevarion influences the host inflammatory response and provides the first evidence of this phase variable epigenetic mechanism of gene regulation in
K. kingae
.
Contribution of Streptococcus mutans Strains with Collagen-Binding Proteins in the Presence of Serum to the Pathogenesis of Infective Endocarditis
Authors: Otsugu Masatoshi , Nomura Ryota , Matayoshi Saaya , Teramoto Noboru , Nakano Kazuhiko 
Published: September 2017

ABSTRACT

Streptococcus mutans
, a major pathogen of dental caries, is considered one of the causative agents of infective endocarditis (IE). Recently, bacterial DNA encoding 120-kDa cell surface collagen-binding proteins (CBPs) has frequently been detected from
S. mutans
-positive IE patients. In addition, some of the CBP-positive
S. mutans
strains lacked a 190-kDa protein antigen (PA), whose absence strengthened the adhesion to and invasion of endothelial cells. The interaction between pathogenic bacteria and serum or plasma is considered an important virulence factor in developing systemic diseases; thus, we decided to analyze the pathogenesis of IE induced by
S. mutans
strains with different patterns of CBP and PA expression by focusing on the interaction with serum or plasma. CBP-positive (CBP
+
)/PA-negative (PA
−
) strains showed prominent aggregation in the presence of human serum or plasma, which was significantly greater than that with CBP
+
/PA-positive (PA
+
) and CBP-negative (CBP
−
)/PA+ strains. Aggregation of CBP
+
/PA
−
strains was also observed in the presence of a high concentration of type IV collagen, a major extracellular matrix protein in serum. In addition, aggregation of CBP
+
/PA
−
strains was drastically reduced when serum complement was inactivated. Furthermore, an
ex vivo
adherence model and an
in vivo
rat model of IE showed that extirpated heart valves infected with CBP
+
/PA
−
strains displayed prominent bacterial mass formation, which was not observed following infection with CBP
+
/PA
+
and CBP
−
/PA
+
strains. These results suggest that CBP
+
/PA
−
S. mutans
strains utilize serum to contribute to their pathogenicity in IE.
PhoU2 but Not PhoU1 as an Important Regulator of Biofilm Formation and Tolerance to Multiple Stresses by Participating in Various Fundamental Metabolic Processes in Staphylococcus epidermidis
Authors: Wang Xiaofei , Han Haiyan , Lv Zhihui , Lin Zhiwei , Shang Yongpeng , Xu Tao , Wu Yang , Zhang Ying , Qu Di 
Published: September 2017

ABSTRACT

PhoU, a conserved protein that has been proposed to coordinate phosphate import, is a negative regulator of drug tolerance in most bacteria. In
Staphylococcus epidermidis
, the role of PhoU in biofilm formation and drug tolerance has not yet been investigated. Two PhoU homologs in the genome of
S. epidermidis
have been identified by the presence of the conserved motif E(D)XXXD of PhoU. We separately constructed Δ
phoU1
and Δ
phoU2
mutants of
S. epidermidis
strain 1457. The Δ
phoU2
mutant displayed growth retardation, a weakened biofilm formation capacity, a higher sensitivity to H
2
O
2
, and reduced tolerance to multiple antibiotics. However, deletion of
phoU1
had no effect on those. We compared the transcriptome profiles of the Δ
phoU2
and Δ
phoU1
mutants with that of the parent strain. In the Δ
phoU2
mutant, expression of genes related to inorganic phosphate uptake was significantly upregulated (
pst
operon) and the levels of intracellular inorganic polyphosphate (polyP) were increased. In the Δ
phoU2
mutant, expression of enzymes in the pentose phosphate pathway (PPP) was downregulated and less NADP (NADPH) was detected, consistent with the high sensitivity to H
2
O
2
and the growth retardation of the Δ
phoU2
mutant. The upregulated expression of ATP synthase was consistent with the high intracellular ATP content in the Δ
phoU2
mutant, which may have been related to the lower drug tolerance of the Δ
phoU2
mutant. This study demonstrates that PhoU2, but not PhoU1, in
S. epidermidis
regulates bacterial growth, biofilm formation, oxidative stress, and drug tolerance in association with alterations to inorganic phosphate metabolism, the pentose phosphate pathway, galactose metabolism, the tricarboxylic acid (TCA) or citric cycle, glycolysis and gluconeogenesis, and respiratory reactions.

IMPORTANCE
PhoU is widely conserved throughout the bacterial kingdom and plays an important role in response to stress and metabolic maintenance. In our study, two PhoU homologs were found in
S. epidermidis
. The function of
phoU2
, but not
phoU1
, in
S. epidermidis
is related to growth, drug tolerance, the oxidative stress response, polyP levels, and ATP accumulation. In addition,
phoU2
regulates biofilm formation. Hence,
phoU2
is a regulator of both drug tolerance and biofilm formation, which are two bacterial properties that present major challenges to the clinical treatment of infections. Analysis of differential gene expression revealed that
phoU2
is involved in fundamental metabolic processes, such as the PPP pathway. These findings indicate that
phoU2
is a crucial regulator in
S. epidermidis
.
Phenotypes of

dnaX
E145A

Mutant Cells Indicate that the Escherichia coli Clamp Loader Has a Role in the Restart of Stalled Replication Forks
Authors: Flåtten Ingvild , Helgesen Emily , Pedersen Ida Benedikte , Waldminghaus Torsten , Rothe Christiane , Taipale Riikka , Johnsen Line , Skarstad Kirsten 
Published: September 2017

ABSTRACT

The
Escherichia coli

dnaX
E145A

mutation was discovered in connection with a screen for multicopy suppressors of the temperature-sensitive topoisomerase IV mutation
parE10
. The gene for the clamp loader subunits τ and γ,
dnaX
, but not the mutant

dnaX
E145A

, was found to suppress
parE10
(Ts) when overexpressed. Purified mutant protein was found to be functional
in vitro
, and few phenotypes were found
in vivo
apart from problems with partitioning of DNA in rich medium. We show here that a large number of the replication forks that initiate at
oriC
never reach the terminus in

dnaX
E145A

mutant cells. The SOS response was found to be induced, and a combination of the

dnaX
E145A

mutation with
recBC
and
recA
mutations led to reduced viability. The mutant cells exhibited extensive chromosome fragmentation and degradation upon inactivation of
recBC
and
recA
, respectively. The results indicate that the

dnaX
E145A

mutant cells suffer from broken replication forks and that these need to be repaired by homologous recombination. We suggest that the
dnaX
-encoded τ and γ subunits of the clamp loader, or the clamp loader complex itself, has a role in the restart of stalled replication forks without extensive homologous recombination.

IMPORTANCE
The
E. coli
clamp loader complex has a role in coordinating the activity of the replisome at the replication fork and loading β-clamps for lagging-strand synthesis. Replication forks frequently encounter obstacles, such as template lesions, secondary structures, and tightly bound protein complexes, which will lead to fork stalling. Some pathways of fork restart have been characterized, but much is still unknown about the actors and mechanisms involved. We have in this work characterized the

dnaX
E145A

clamp loader mutant. We find that the naturally occurring obstacles encountered by a replication fork are not tackled in a proper way by the mutant clamp loader and suggest a role for the clamp loader in the restart of stalled replication forks.
Population-based cohort study examining the association between splenectomy and empyema in adults in Taiwan
Authors: Lin Hsien-Feng , Liao Kuan-Fu , Chang Ching-Mei , Lin Cheng-Li , Lai Shih-Wei 
Published: September 2017

ObjectiveThis study aimed to investigate the association between splenectomy and empyema in Taiwan.MethodsA population-based cohort study was conducted using the hospitalisation dataset of the Taiwan National Health Insurance Program. A total of 13 193 subjects aged 20–84 years who were newly diagnosed with splenectomy from 2000 to 2010 were enrolled in the splenectomy group and 52 464 randomly selected subjects without splenectomy were enrolled in the non-splenectomy group. Both groups were matched by sex, age, comorbidities and the index year of undergoing splenectomy. The incidence of empyema at the end of 2011 was calculated. A multivariable Cox proportional hazards regression model was used to estimate the HR with 95% CI of empyema associated with splenectomy and other comorbidities.ResultsThe overall incidence rate of empyema was 2.56-fold higher in the splenectomy group than in the non-splenectomy group (8.85 vs 3.46 per 1000 person-years). The Kaplan-Meier analysis revealed a higher cumulative incidence of empyema in the splenectomy group than in the non-splenectomy group (6.99% vs 3.37% at the end of follow-up). After adjusting for confounding variables, the adjusted HR of empyema was 2.89 for the splenectomy group compared with that for the non-splenectomy group. Further analysis revealed that HR of empyema was 4.52 for subjects with splenectomy alone.ConclusionThe incidence rate ratio between the splenectomy and non-splenectomy groups reduced from 2.87 in the first 5 years of follow-up to 1.73 in the period following the 5 years. Future studies are required to confirm whether a longer follow-up period would further reduce this average ratio. For the splenectomy group, the overall HR of developing empyema was 2.89 after adjusting for age, sex and comorbidities, which was identified from previous literature. The risk of empyema following splenectomy remains high despite the absence of these comorbidities.
Relationship of altitude mountain sickness and smoking: a Catalan traveller’s cohort study
Authors: Sánchez-Mascuñano Alba , Masuet-Aumatell Cristina , Morchón-Ramos Sergio , Ramon Josep M 
Published: September 2017

ObjectivesThe aim of this study is to analyse the relationship between smoking andaltitude mountain sicknessin a cohort of travellers to 2500 metres above sea level (masl) or higher.SettingTravel Health Clinic at the Hospital Universitari de Bellvitge, in Barcelona, Spain.ParticipantsA total of 302 adults seeking medical advice at the travel clinic, between July 2012 and August 2014, before travelling to 2500 masl or above, who agreed to participate in the study and to be contacted after the trip were included. Individuals who met the following criteria were excluded: younger than 18 years old, taking carbonic anhydrase inhibitors for chronic use, undergoing treatment with systemic corticosteroids and taking any medication that might prevent or treat altitude mountain sickness (AMS) prior to or during the trip. The majority of participants were women (n=156, 51.7%). The mean age was 37.7 years (SD 12.3). The studied cohort included 74 smokers (24.5%), 158 (52.3%) non-smokers and 70 (23.2%) ex-smokers. No statistical differences were observed between different sociodemographic characteristics, constitutional symptoms or drug use and smoking status.OutcomesThe main outcome was the development of AMS, which was defined according to the Lake Louise AMS criteria.ResultsAMS, according to the Lake Louise score, was significantly lower in smokers; the value was 14.9%, 95% CI (6.8 to 23.0%) in smokers and 29.4%, 95% CI (23.5 to 35.3%) in non-smokers with an adjusted OR of 0.54, 95% CI (0.31 to 0.97) independent of gender, age and maximum altitude reached.ConclusionsThese results suggest that smoking could reduce the risk of AMS in non-acclimated individuals. Further studies should be performed in larger cohorts of travellers to confirm these results. Despite the results, smoking must be strongly discouraged because it greatly increases the risk of cardiorespiratory diseases, cancer and other diseases.
Baseline characteristics, survival and direct costs associated to treatment of gastric cancer patients at the National Oncology Institute of Panama from 2012 to 2015: a hospital-based observational study
Authors: Castro Franz , Shahal David , Tarajia Musharaf , Velásquez Ilais Moreno , Causadias Maribel Tribaldos , Herrera Víctor , Gómez Beatriz , Cukier Moisés , Motta Jorge 
Published: September 2017

ObjectivesComprehensive epidemiological and economic studies of gastric cancer (GC) in Panama are limited. This study aims to evaluate the association between socioeconomic and clinical variables with survival, describe the survival outcomes according to clinical stage and estimate the direct costs associated to GC care in a Panamanian population with GC.Design and settingA retrospective observational study was conducted at the leading public institution for cancer treatment in Panama.ParticipantsData were obtained from 611 records of patients diagnosed with gastric adenocarcinoma (codes C16.0–C16.9 of the International Classification of Diseases 10th revision), identified between 1 January 2012 and 31 December 2015.MethodsCox proportional hazards models were used to calculate HRs with 95%  CI to examine associations between the variables and survival. Kaplan-Meier curves were used to assess overall and stage-specific survival. Direct costs (based on 2015 US$) were calculated per patient using standard costs provided by the institution for hospital admission (occupied bed-days), radiotherapy, surgery and chemotherapy, yielding total and overall mean costs (OMC). A comparison of OMC between groups (sex, social security status, clinical stage) was performed applying the bootstrap method with a t-test of unequal variances.ResultsAn increased risk of dying was observed for patients without social security coverage (HR: 2.02; 95% CI 1.16 to 3.53), overlapping tumours (HR: 1.50; 95% CI 1.02 to 2.22), poorly differentiated tumours (HR: 2.27; 95% CI 1.22 to 4.22) and stage IV disease (HR: 5.54; 95% CI 3.38 to 9.08) (adjusted models). Overall 1-year survival rate was 41%. The estimated OMC of GC care per patient was 4259 US$. No statistically significant differences were found in OMC between groups.ConclusionsSocioeconomic disparities influence GC outcomes and healthcare utilisation. Policies addressing healthcare disparities related to GC are needed, as well as in-depth studies evaluating barriers of access to GC-related services.