bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pharmacokinetics-Pharmacodynamics of a Novel β-Lactamase Inhibitor, CB-618, in Combination with Meropenem in an
In Vitro
Infection Model
Authors: VanScoy Brian D. , Trang Michael , McCauley Jennifer , Conde Haley , Bhavnani Sujata M. , Friedrich Lawrence V. , Alexander Dylan C. , Ambrose Paul G. 
Published: March 2016

ABSTRACT

The usefulness of β-lactam antimicrobial agents is threatened as never before by β-lactamase-producing bacteria. For this reason, there has been renewed interest in the development of broad-spectrum β-lactamase inhibitors. Herein we describe the results of dose fractionation and dose-ranging studies carried out using a one-compartment
in vitro
infection model to determine the exposure measure for CB-618, a novel β-lactamase inhibitor, most predictive of the efficacy when given in combination with meropenem. The challenge panel included
Enterobacteriaceae
clinical isolates, which collectively produced a wide range of β-lactamase enzymes (KPC-2, KPC-3, FOX-5, OXA-48, SHV-11, SHV-27, and TEM-1). Human concentration-time profiles were simulated for each drug, and samples were collected for drug concentration and bacterial density determinations. Using data from dose fractionation studies and a challenge
Klebsiella pneumoniae
isolate (CB-618-potentiated meropenem MIC = 1 mg/liter), relationships between change from baseline in log
10
CFU/ml at 24 h and each of CB-618 area under the concentration-time curve over 24 h (AUC
0–24
), maximum concentration (
C
max
), and percentage of the dosing interval that CB-618 concentrations remained above a given threshold were evaluated in combination with meropenem at 2 g every 8 h (q8h). The exposure measures most closely associated with CB-618 efficacy in combination with meropenem were the CB-618 AUC
0–24
(
r
2
= 0.835) and
C
max
(
r
2
= 0.826). Using the CB-618 AUC
0–24
indexed to the CB-618-potentiated meropenem MIC value, the relationship between change from baseline in log
10
CFU/ml at 24 h and CB-618 AUC
0–24
/MIC ratio in combination with meropenem was evaluated using the pooled data from five challenge isolates; the CB-618 AUC
0–24
/MIC ratio associated with net bacterial stasis and the 1- and 2-log
10
CFU/ml reductions from baseline at 24 h were 27.3, 86.1, and 444.8, respectively. These data provide a pharmacokinetics-pharmacodynamics (PK-PD) basis for evaluating potential CB-618 dosing regimens in combination with meropenem in future studies.
Excreted Cytoplasmic Proteins Contribute to Pathogenicity in Staphylococcus aureus
Authors: Ebner Patrick , Rinker Janina , Nguyen Minh Thu , Popella Peter , Nega Mulugeta , Luqman Arif , Schittek Birgit , Di Marco Moreno , Stevanovic Stefan , Götz Friedrich 
Published: March 2016

ABSTRACT

Excretion of cytoplasmic proteins in pro- and eukaryotes, also referred to as “nonclassical protein export,” is a well-known phenomenon. However, comparatively little is known about the role of the excreted proteins in relation to pathogenicity. Here, the impact of two excreted glycolytic enzymes, aldolase (FbaA) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), on pathogenicity was investigated in
Staphylococcus aureus
. Both enzymes bound to certain host matrix proteins and enhanced adherence of the bacterial cells to host cells but caused a decrease in host cell invasion. FbaA and GAPDH also bound to the cell surfaces of staphylococcal cells by interaction with the major autolysin, Atl, that is involved in host cell internalization. Surprisingly, FbaA showed high cytotoxicity to both MonoMac 6 (MM6) and HaCaT cells, while GAPDH was cytotoxic only for MM6 cells. Finally, the contribution of external FbaA and GAPDH to
S. aureus
pathogenicity was confirmed in an insect infection model.
Staphylococcus aureus Phenol-Soluble Modulins Impair Interleukin Expression in Bovine Mammary Epithelial Cells
Authors: Deplanche Martine , Alekseeva Ludmila , Semenovskaya Ksenia , Fu Chih-Lung , Dessauge Frederic , Finot Laurence , Petzl Wolfram , Zerbe Holm , Le Loir Yves , Rainard Pascal , Smith David G. E. , Germon Pierre , Otto Michael , Berkova Nadia 
Published: March 2016

ABSTRACTThe role of the recently described interleukin-32 (IL-32) inStaphylococcus aureus-induced mastitis, an inflammation of the mammary gland, is unclear. We determined expression of IL-32, IL-6, and IL-8 inS. aureus- andEscherichia coli-infected bovine mammary gland epithelial cells. Using live bacteria, we found that inS. aureus-infected cells, induction of IL-6 and IL-8 expression was less pronounced than inE. coli-infected cells. Notably, IL-32 expression was decreased inS. aureus-infected cells, while it was increased inE. coli-infected cells. We identified the staphylococcal phenol-soluble modulin (PSM) peptides as key contributors to these effects, as IL-32, IL-6, and IL-8 expression by epithelial cells exposed topsmmutant strains was significantly increased compared to that in cells exposed to the isogenicS. aureuswild-type strain, indicating that PSMs inhibit the production of these interleukins. The use of genetically complemented strains confirmed this observation. Inasmuch as the decreased expression of IL-32, which is involved in dendritic cell maturation, impairs immune responses, our results support a PSM-dependent mechanism that allows for the development of chronicS. aureus-related mastitis.
Novel Strategy To Protect against Influenza Virus-Induced Pneumococcal Disease without Interfering with Commensal Colonization
Authors: Greene Christopher J. , Marks Laura R. , Hu John C. , Reddinger Ryan , Mandell Lorrie , Roche-Hakansson Hazeline , King-Lyons Natalie D. , Connell Terry D. , Hakansson Anders P. 
Published: March 2016

ABSTRACT

Streptococcus pneumoniae
commonly inhabits the nasopharynx as a member of the commensal biofilm. Infection with respiratory viruses, such as influenza A virus, induces commensal
S. pneumoniae
to disseminate beyond the nasopharynx and to elicit severe infections of the middle ears, lungs, and blood that are associated with high rates of morbidity and mortality. Current preventive strategies, including the polysaccharide conjugate vaccines, aim to eliminate asymptomatic carriage with vaccine-type pneumococci. However, this has resulted in serotype replacement with, so far, less fit pneumococcal strains, which has changed the nasopharyngeal flora, opening the niche for entry of other virulent pathogens (e.g.,
Streptococcus pyogenes
,
Staphylococcus aureus
, and potentially
Haemophilus influenzae
). The long-term effects of these changes are unknown. Here, we present an attractive, alternative preventive approach where we subvert virus-induced pneumococcal disease without interfering with commensal colonization, thus specifically targeting disease-causing organisms. In that regard, pneumococcal surface protein A (PspA), a major surface protein of pneumococci, is a promising vaccine target. Intradermal (i.d.) immunization of mice with recombinant PspA in combination with LT-IIb(T13I), a novel i.d. adjuvant of the type II heat-labile enterotoxin family, elicited strong systemic PspA-specific IgG responses without inducing mucosal anti-PspA IgA responses. This response protected mice from otitis media, pneumonia, and septicemia and averted the cytokine storm associated with septic infection but had no effect on asymptomatic colonization. Our results firmly demonstrated that this immunization strategy against virally induced pneumococcal disease can be conferred without disturbing the desirable preexisting commensal colonization of the nasopharynx.
The Helicobacter pylori CZB Cytoplasmic Chemoreceptor TlpD Forms an Autonomous Polar Chemotaxis Signaling Complex That Mediates a Tactic Response to Oxidative Stress
Authors: Collins Kieran D. , Andermann Tessa M. , Draper Jenny , Sanders Lisa , Williams Susan M. , Araghi Cameron , Ottemann Karen M. 
Published: March 2016

ABSTRACTCytoplasmic chemoreceptors are widespread among prokaryotes but are far less understood than transmembrane chemoreceptors, despite being implicated in many processes. One such cytoplasmic chemoreceptor isHelicobacter pyloriTlpD, which is required for stomach colonization and drives a chemotaxis response to cellular energy levels. Neither the signals sensed by TlpD nor its molecular mechanisms of action are known. We report here that TlpD functions independently of the other chemoreceptors. When TlpD is the sole chemoreceptor, it is able to localize to the pole and recruits CheW, CheA, and at least two CheV proteins to this location. It loses the normal membrane association that appears to be driven by interactions with other chemoreceptors and with CheW, CheV1, and CheA. These results suggest that TlpD can form an autonomous signaling unit. We further determined that TlpD mediates a repellent chemotaxis response to conditions that promote oxidative stress, including being in the presence of iron, hydrogen peroxide, paraquat, and metronidazole. Last, we found that all testedH. pyloristrains express TlpD, whereas other chemoreceptors were present to various degrees. Our data suggest a model in which TlpD coordinates a signaling complex that responds to oxidative stress and may allowH. pylorito avoid areas of the stomach with high concentrations of reactive oxygen species.IMPORTANCEHelicobacter pylorisenses its environment with proteins called chemoreceptors. Chemoreceptors integrate this sensory information to affect flagellum-based motility in a process called chemotaxis. Chemotaxis is employed during infection and presumably aidsH. pyloriin encountering and colonizing preferred niches. A cytoplasmic chemoreceptor named TlpD is particularly important in this process, and we report here that this chemoreceptor is able to operate independently of other chemoreceptors to organize a chemotaxis signaling complex and mediate a repellent response to oxidative stress conditions.H. pyloriencounters and must cope with oxidative stress during infection due to oxygen and reactive oxygen species produced by host cells. TlpD's repellent response may allow the bacteria to escape niches experiencing inflammation and elevated reactive oxygen species (ROS) production.
Transcriptome Analysis of Escherichia coli during dGTP Starvation
Authors: Itsko Mark , Schaaper Roel M. 
Published: March 2016

ABSTRACT

Our laboratory recently discovered that
Escherichia coli
cells starved for the DNA precursor dGTP are killed efficiently (dGTP starvation) in a manner similar to that described for thymineless death (TLD). Conditions for specific dGTP starvation can be achieved by depriving an
E. coli
optA1 gpt
strain of the purine nucleotide precursor hypoxanthine (Hx). To gain insight into the mechanisms underlying dGTP starvation, we conducted genome-wide gene expression analyses of actively growing
optA1 gpt
cells subjected to hypoxanthine deprivation for increasing periods. The data show that upon Hx withdrawal, the
optA1 gpt
strain displays a diminished ability to derepress the
de novo
purine biosynthesis genes, likely due to internal guanine accumulation. The impairment in fully inducing the
purR
regulon may be a contributing factor to the lethality of dGTP starvation. At later time points, and coinciding with cell lethality, strong induction of the SOS response was observed, supporting the concept of replication stress as a final cause of death. No evidence was observed in the starved cells for the participation of other stress responses, including the
rpoS
-mediated global stress response, reinforcing the lack of feedback of replication stress to the global metabolism of the cell. The genome-wide expression data also provide direct evidence for increased genome complexity during dGTP starvation, as a markedly increased gradient was observed for expression of genes located near the replication origin relative to those located toward the replication terminus.

IMPORTANCE
Control of the supply of the building blocks (deoxynucleoside triphosphates [dNTPs]) for DNA replication is important for ensuring genome integrity and cell viability. When cells are starved specifically for one of the four dNTPs, dGTP, the process of DNA replication is disturbed in a manner that can lead to eventual death. In the present study, we investigated the transcriptional changes in the bacterium
E. coli
during dGTP starvation. The results show increasing DNA replication stress with an increased time of starvation, as evidenced by induction of the bacterial SOS system, as well as a notable lack of induction of other stress responses that could have saved the cells from cell death by slowing down cell growth.
Rv2744c Is a PspA Ortholog That Regulates Lipid Droplet Homeostasis and Nonreplicating Persistence in Mycobacterium tuberculosis
Authors: Armstrong Richard M. , Adams Katherine L. , Zilisch Joseph E. , Bretl Daniel J. , Sato Hiromi , Anderson David M. , Zahrt Thomas C. 
Published: March 2016

ABSTRACT

Mycobacterium tuberculosis
, the causative agent of tuberculosis (TB), remains a significant cause of morbidity and mortality worldwide, despite the availability of a live attenuated vaccine and anti-TB antibiotics. The vast majority of individuals infected with
M. tuberculosis
develop an asymptomatic latent infection in which the bacterium survives within host-generated granulomatous lesions in a physiologically altered metabolic state of nonreplicating persistence. The granuloma represents an adverse environment, as
M. tuberculosis
is exposed to various stressors capable of disrupting the essential constituents of the bacterium. In Gram-negative and Gram-positive bacteria, resistance to cell envelope stressors that perturb the plasma membrane is mediated in part by proteins comprising the phage shock protein (Psp) system. PspA is an important component of the Psp system; in the presence of envelope stress, PspA localizes to the inner face of the plasma membrane, homo-oligomerizes to form a large scaffold-like complex, and helps maintain plasma membrane integrity to prevent a loss of proton motive force.
M. tuberculosis
and other members of the
Mycobacterium
genus are thought to encode a minimal functional unit of the Psp system, including an ortholog of PspA. Here, we show that Rv2744c possesses structural and physical characteristics that are consistent with its designation as a PspA family member. However, although
Rv2744c
is upregulated under conditions of cell envelope stress, loss of
Rv2744c
does not alter resistance to cell envelope stressors. Furthermore, Rv2744c localizes to the surface of lipid droplets in
Mycobacterium
spp. and regulates lipid droplet number, size, and
M. tuberculosis
persistence during anaerobically induced dormancy. Collectively, our results indicate that Rv2744c is a bona fide ortholog of PspA that may function in a novel role to regulate lipid droplet homeostasis and nonreplicating persistence (NRP) in
M. tuberculosis
.

IMPORTANCE
Mycobacterium tuberculosis
is the causative agent of tuberculosis, a disease associated with significant morbidity and mortality worldwide.
M. tuberculosis
is capable of establishing lifelong asymptomatic infections in susceptible individuals and reactivating during periods of immune suppression to cause active disease. The determinants that are important for persistent infection of
M. tuberculosis
or for reactivation of this organism from latency are poorly understood. In this study, we describe our initial characterizations of Rv2744c, an ortholog of phage shock protein A (PspA) that regulates the homeostasis of lipid bodies and nonreplicating persistence in
M. tuberculosis
. This function of PspA in
M. tuberculosis
is novel and suggests that PspA may represent a unique bacterial target upon which to base therapeutic interventions against this organism.
Identification of the Three Genes Involved in Controlling Production of a Phytotoxin Tropolone in Burkholderia plantarii
Authors: Miwa Shunpei , Kihira Eri , Yoshioka Akinori , Nakasone Kaoru , Okamoto Sho , Hatano Masaki , Igarashi Masayuki , Eguchi Yoko , Kato Akinori , Ichikawa Natsuko , Sekine Mitsuo , Fujita Nobuyuki , Kanesaki Yu , Yoshikawa Hirofumi , Utsumi Ryutaro 
Published: March 2016

ABSTRACT

Tropolone, a phytotoxin produced by
Burkholderia plantarii
, causes rice seedling blight. To identify genes involved in tropolone synthesis, we systematically constructed mutations in the genes encoding 55 histidine kinases and 72 response regulators. From the resulting defective strains, we isolated three mutants, KE1, KE2, and KE3, in which tropolone production was repressed. The deleted genes of these mutants were named
troR1
,
troK
, and
troR2
, respectively. The mutant strains did not cause rice seedling blight, and complementation experiments indicated that TroR1, TroK, and TroR2 were involved in the synthesis of tropolone in
B. plantarii
. However, tropolone synthesis was repressed in the TroR1 D52A, TroK H253A, and TroR2 D46A site-directed mutants. These results suggest that the putative sensor kinase (TroK) and two response regulators (TroR1 and TroR2) control the production of tropolone in
B. plantarii
.

IMPORTANCE
A two-component system is normally composed of a sensor histidine kinase (HK) and a cognate response regulator (RR) pair. In this study, HK (TroK) and two RRs (TroR1 and TroR2) were found to be involved in controlling tropolone production in
B. plantarii
. These three genes may be part of a bacterial signal transduction network. Such networks are thought to exist in other bacteria to regulate phytotoxin production, as well as environmental adaptation and signal transduction.
ABC-F Proteins Mediate Antibiotic Resistance through Ribosomal Protection
Authors: Sharkey Liam K. R. , Edwards Thomas A. , O’Neill Alex J. 
Published: March 2016

ABSTRACT

Members of the ABC-F subfamily of ATP-binding cassette proteins mediate resistance to a broad array of clinically important antibiotic classes that target the ribosome of Gram-positive pathogens. The mechanism by which these proteins act has been a subject of long-standing controversy, with two competing hypotheses each having gained considerable support: antibiotic efflux versus ribosomal protection. Here, we report on studies employing a combination of bacteriological and biochemical techniques to unravel the mechanism of resistance of these proteins, and provide several lines of evidence that together offer clear support to the ribosomal protection hypothesis. Of particular note, we show that addition of purified ABC-F proteins to an
in vitro
translation assay prompts dose-dependent rescue of translation, and demonstrate that such proteins are capable of displacing antibiotic from the ribosome
in vitro
. To our knowledge, these experiments constitute the first direct evidence that ABC-F proteins mediate antibiotic resistance through ribosomal protection.

IMPORTANCE
Antimicrobial resistance ranks among the greatest threats currently facing human health. Elucidation of the mechanisms by which microorganisms resist the effect of antibiotics is central to understanding the biology of this phenomenon and has the potential to inform the development of new drugs capable of blocking or circumventing resistance. Members of the ABC-F family, which include
lsa
(A),
msr
(A),
optr
(A), and
vga
(A), collectively yield resistance to a broader range of clinically significant antibiotic classes than any other family of resistance determinants, although their mechanism of action has been controversial since their discovery 25 years ago. Here we present the first direct evidence that proteins of the ABC-F family act to protect the bacterial ribosome from antibiotic-mediated inhibition.
Impact of socioeconomic deprivation on screening for cardiovascular disease risk in a primary prevention population: a cross-sectional study
Authors: Lang Sarah-Jane , Abel Gary A , Mant Jonathan , Mullis Ricky 
Published: March 2016

ObjectivesInvestigate the association between socioeconomic deprivation and completeness of cardiovascular disease (CVD) risk factor recording in primary care, uptake of screening in people with incomplete risk factor recording and with actual CVD risk within the screened subgroup.DesignCross-sectional study.SettingNine UK general practices.Participants7987 people aged 50–74 years with no CVD diagnosis.MethodsCVD risk was estimated using the Framingham equation from data extracted from primary care electronic health records. Where there was insufficient information to calculate risk, patients were invited to attend a screening assessment.AnalysisProportion of patients for whom clinical data were sufficiently complete to enable CVD risk to be calculated; proportion of patients invited to screening who attended; proportion of patients who attended screening whose 10-year risk of a cardiovascular event was high (>20%). For each outcome, a set of logistic regression models were run. Crude and adjusted ORs were estimated for person-level deprivation, age, gender and smoking status. We included practice-level deprivation as a continuous variable and practice as a random effect to account for clustering.ResultsPeople who had lower Indices of Multiple Deprivation (IMD) scores (less deprived) had significantly worse routine CVD risk factor recording (adjusted OR 0.97 (0.95 to 1.00) per IMD decile; p=0.042). Screening attendance was poorer in those with more deprivation (adjusted OR 0.89 (0.86 to 0.91) per IMD decile; p<0.001). Among those who attended screening, the most deprived were more likely to have CVD risk >20% (OR 1.09 (1.03 to 1.15) per IMD decile; p=0.004).ConclusionsOur data suggest that those who had the most to gain from screening were least likely to attend, potentially exacerbating existing health inequalities. Future research should focus on tailoring the delivery of CVD screening to ensure engagement of socioeconomically deprived groups.
Sports injuries and ill-health episodes in the Cali 2013 World Games
Authors: Llinás Paulo José , Serrano Rafael Fernando , Quintero Barrera Laureano , Quiceno Noguera Juan Carlos , Martinez Cano Juan Pablo 
Published: March 2016

BackgroundThe World Games is a multisport event, second in importance only to the Olympic Games. Systematic surveillance of injuries and ill-health episodes is an essential part of modern integral healthcare given to athletes.AimTo describe and analyse injuries and ill-health episodes affecting competitors during the Cali World Games 2013.MethodsThis is a cross-sectional study of injuries and ill-health episodes suffered by competing athletes. Entries to the registry were systematically recorded by official doctors and medical staff at the Games, and included attention to emergencies at the sport venues and data of reports received from health facilities around the city.ResultsIn all, 2824 athletes, 1216 women and 1608 men, participated in the 2013 Cali World Games. There were 88 injuries and 29 ill-health episodes, for an overall incidence of 31.2 injuries and 10.3 ill-health episodes per 1000 athletes, over an 11 day period. The highest incidence of sport associated injuries affected jiu-jitsu athletes. Hands were the most common site of injury. Injury rates for men and women were 35.5 and 25.5/1000 athletes, respectively, (RR=1.41, 95% CI 0.90 to 2.19, p=0.066). National delegations with less than 25 athletes suffered more injuries compared to larger delegations, with 40.9 vs 29.2 injuries per 1000 athletes (RR 1.4, 95% CI 0.85 to 2.30, p=0.12). The gastrointestinal system was the most affected by illness. The sport where most competitors suffered ill-health episodes was softball. The rate of ill-health episodes in women was 15/1000, and for men 6.8/1000 athletes (RR=2.16, 95% CI 1.03 to 4.56, p=0.038).Conclusions3.1% of the athletes had sport-related injuries, and 1% had at least one episode of ill health. These are low numbers compared to other multisport events such as the Olympic Games. Men had a higher incidence of injuries, and women a higher incidence of episodes of ill health. Future World Games should improve data-collection strategies and develop preventive measures accordingly.