bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pharmacokinetics of Tedizolid in Morbidly Obese and Covariate-Matched Nonobese Adults
Authors: Pai Manjunath P. 
Published: May 2016

ABSTRACT

Tedizolid is a novel oxazolidinone antimicrobial administered in its prodrug form, tedizolid phosphate, as a fixed once-daily dose. The pharmacokinetics of tedizolid has been studied in a relatively small proportion of morbidly obese (body mass index [BMI] of ≥40 kg/m
2
) adults through population analyses with sparse sampling. The current study compared the intensively sampled plasma pharmacokinetics of tedizolid phosphate and tedizolid in 9 morbidly obese and 9 age-, sex-, and ideal body weight-matched nonobese (BMI, 18.5 to 29.9 kg/m
2
) healthy adult (18 to 50 years of age) volunteers after administration of a single intravenous dose of tedizolid phosphate. The median (range) weights were 72.6 kg (58.9 to 89.5 kg) and 117 kg (102 to 176 kg) for the mostly female (77.8%) nonobese and morbidly obese adults, respectively. Tedizolid phosphate concentrations were below the limit of quantitation in a majority of subjects after the 2-h time point. The tedizolid median (range) maximum concentration of drug in plasma (
C
max
) and area under the concentration-time curve from 0 h to infinity (AUC
0–∞
) were 2.38 (1.28 to 3.99) mg/liter and 26.3 (18.4 to 43.2) h · mg/liter, respectively, for morbidly obese subjects, and these were nonsignificantly different (
P
≥ 0.214) from the values for nonobese subjects. Similarly, the volumes of distribution (

V
z

) (
P
= 0.110) and clearance (CL) values (
P
= 0.214) were comparable between groups. Nearly identical (
P
= 0.953) median tedizolid half-lives of approximately 12 h were observed for both groups. Tedizolid

V
z

and CL scaled with body weight, but not proportionately. The small and nonsignificant differences in tedizolid AUC
0–∞
values between morbidly obese and nonobese subjects suggest that dose modification is not necessary for morbidly obese adults. (This study has been registered at ClinicalTrials.gov under number NCT02342418.)
Antiviral Activity of Favipiravir (T-705) against a Broad Range of Paramyxoviruses
In Vitro
and against Human Metapneumovirus in Hamsters
Authors: Jochmans D. , van Nieuwkoop S. , Smits S. L. , Neyts J. , Fouchier R. A. M. , van den Hoogen B. G. 
Published: May 2016

ABSTRACT

The clinical impact of infections with respiratory viruses belonging to the family
Paramyxoviridae
argues for the development of antiviral therapies with broad-spectrum activity. Favipiravir (T-705) has demonstrated potent antiviral activity against multiple RNA virus families and is presently in clinical evaluation for the treatment of influenza. Here we demonstrate
in vitro
activity of T-705 against the paramyxoviruses human metapneumovirus (HMPV), respiratory syncytial virus, human parainfluenza virus, measles virus, Newcastle disease virus, and avian metapneumovirus. In addition, we demonstrate activity against HMPV in hamsters. T-705 treatment inhibited replication of all paramyxoviruses tested
in vitro
, with 90% effective concentration (EC
90
) values of 8 to 40 μM. Treatment of HMPV-challenged hamsters with T-705 at 200 mg/kg of body weight/day resulted in 100% protection from infection of the lungs. In all treated and challenged animals, viral RNA remained detectable in the respiratory tract. The observation that T-705 treatment had a significant effect on infectious viral titers, with a limited effect on viral genome titers, is in agreement with its proposed mode of action of viral mutagenesis. However, next-generation sequencing of viral genomes isolated from treated and challenged hamsters did not reveal (hyper)mutation. Polymerase activity assays revealed a specific effect of T-705 on the activity of the HMPV polymerase. With the reported antiviral activity of T-705 against a broad range of RNA virus families, this small molecule is a promising broad-range antiviral drug candidate for limiting the viral burden of paramyxoviruses and for evaluation for treatment of infections with (re)emerging viruses, such as the henipaviruses.
Mutations in
pepQ
Confer Low-Level Resistance to Bedaquiline and Clofazimine in Mycobacterium tuberculosis
Authors: Almeida Deepak , Ioerger Thomas , Tyagi Sandeep , Li Si-Yang , Mdluli Khisimuzi , Andries Koen , Grosset Jacques , Sacchettini Jim , Nuermberger Eric 
Published: May 2016

ABSTRACT

The novel ATP synthase inhibitor bedaquiline recently received accelerated approval for treatment of multidrug-resistant tuberculosis and is currently being studied as a component of novel treatment-shortening regimens for drug-susceptible and multidrug-resistant tuberculosis. In a limited number of bedaquiline-treated patients reported to date, ≥4-fold upward shifts in bedaquiline MIC during treatment have been attributed to non-target-based mutations in
Rv0678
that putatively increase bedaquiline efflux through the MmpS5-MmpL5 pump. These mutations also confer low-level clofazimine resistance, presumably by a similar mechanism. Here, we describe a new non-target-based determinant of low-level bedaquiline and clofazimine cross-resistance in
Mycobacterium tuberculosis
: loss-of-function mutations in
pepQ
(
Rv2535c
), which corresponds to a putative Xaa-Pro aminopeptidase.
pepQ
mutants were selected in mice by treatment with clinically relevant doses of bedaquiline, with or without clofazimine, and were shown to have bedaquiline and clofazimine MICs 4 times higher than those for the parental H37Rv strain. Coincubation with efflux inhibitors verapamil and reserpine lowered bedaquiline MICs against both mutant and parent strains to a level below the MIC against H37Rv in the absence of efflux pump inhibitors. However, quantitative PCR (qPCR) revealed no significant differences in expression of
Rv0678
,
mmpS5
, or
mmpL5
between mutant and parent strains. Complementation of a
pepQ
mutant with the wild-type gene restored susceptibility, indicating that loss of PepQ function is sufficient for reduced susceptibility both
in vitro
and in mice. Although the mechanism by which mutations in
pepQ
confer bedaquiline and clofazimine cross-resistance remains unclear, these results may have clinical implications and warrant further evaluation of clinical isolates with reduced susceptibility to either drug for mutations in this gene.
Absence of Association between Polymorphisms in the RING E3 Ubiquitin Protein Ligase Gene and
Ex Vivo
Susceptibility to Conventional Antimalarial Drugs in Plasmodium falciparum Isolates from Dakar, Senegal
Authors: Gendrot Mathieu , Fall Bécaye , Madamet Marylin , Fall Mansour , Wade Khalifa Ababacar , Amalvict Rémy , Nakoulima Aminata , Benoit Nicolas , Diawara Silman , Diémé Yaya , Diatta Bakary , Wade Boubacar , Pradines Bruno 
Published: May 2016

ABSTRACT

The RING E3 ubiquitin protein ligase is crucial for facilitating the transfer of ubiquitin. The only polymorphism identified in the E3 ubiquitin protein ligase gene was the D113N mutation (62.5%) but was not significantly associated with the 50% inhibitory concentration (IC
50
) of conventional antimalarial drugs. However, some mutated isolates (D113N) present a trend of reduced susceptibility to piperaquine (
P
= 0.0938). To evaluate the association of D113N polymorphism with susceptibility to antimalarials, more isolates are necessary.
Clustered Intracellular Salmonella enterica Serovar Typhimurium Blocks Host Cell Cytokinesis
Authors: Santos António J. M. , Durkin Charlotte H. , Helaine Sophie , Boucrot Emmanuel , Holden David W. 
Published: May 2016

ABSTRACT

Several bacterial pathogens and viruses interfere with the cell cycle of their host cells to enhance virulence. This is especially apparent in bacteria that colonize the gut epithelium, where inhibition of the cell cycle of infected cells enhances the intestinal colonization. We found that intracellular
Salmonella enterica
serovar Typhimurium induced the binucleation of a large proportion of epithelial cells by 14 h postinvasion and that the effect was dependent on an intact
Salmonella
pathogenicity island 2 (SPI-2) type 3 secretion system. The SPI-2 effectors SseF and SseG were required to induce binucleation. SseF and SseG are known to maintain microcolonies of
Salmonella-
containing vacuoles close to the microtubule organizing center of infected epithelial cells. During host cell division, these clustered microcolonies prevented the correct localization of members of the chromosomal passenger complex and mitotic kinesin-like protein 1 and consequently prevented cytokinesis. Tetraploidy, arising from a cytokinesis defect, is known to have a deleterious effect on subsequent cell divisions, resulting in either chromosomal instabilities or cell cycle arrest. In infected mice, proliferation of small intestinal epithelial cells was compromised in an SseF/SseG-dependent manner, suggesting that cytokinesis failure caused by
S
. Typhimurium delays epithelial cell turnover in the intestine.
Merozoite Antigens of Plasmodium falciparum Elicit Strain-Transcending Opsonizing Immunity
Authors: Hill Danika L. , Wilson Danny W. , Sampaio Natalia G. , Eriksson Emily M. , Ryg-Cornejo Victoria , Harrison G. L. Abby , Uboldi Alessandro D. , Robinson Leanne J. , Beeson James G. , Siba Peter , Cowman Alan F. , Hansen Diana S. , Mueller Ivo , Schofield Louis 
Published: May 2016

ABSTRACT

It is unclear whether naturally acquired immunity to
Plasmodium falciparum
results from the acquisition of antibodies to multiple, diverse antigens or to fewer, highly conserved antigens. Moreover, the specific antibody functions required for malaria immunity are unknown, and hence informative immunological assays are urgently needed to address these knowledge gaps and guide vaccine development. In this study, we investigated whether merozoite-opsonizing antibodies are associated with protection from malaria in a strain-specific or strain-transcending manner by using a novel field isolate and an immune plasma-matched cohort from Papua New Guinea with our validated assay of merozoite phagocytosis. Highly correlated opsonization responses were observed across the 15 parasite strains tested, as were strong associations with protection (composite phagocytosis score across all strains in children uninfected at baseline: hazard ratio of 0.15, 95% confidence interval of 0.04 to 0.63). Opsonizing antibodies had a strong strain-transcending component, and the opsonization of transgenic parasites deficient for MSP3, MSP6, MSPDBL1, or
P. falciparum
MSP1-19 (PfMSP1-19) was similar to that of wild-type parasites. We have provided the first evidence that merozoite opsonization is predominantly strain transcending, and the highly consistent associations with protection against diverse parasite strains strongly supports the use of merozoite opsonization as a correlate of immunity for field studies and vaccine trials. These results demonstrate that conserved domains within merozoite antigens targeted by opsonization generate strain-transcending immune responses and represent promising vaccine candidates.
Use of Attenuated but Metabolically Competent Salmonella as a Probiotic To Prevent or Treat Salmonella Infection
Authors: Sabag-Daigle Anice , Blunk Henry M. , Gonzalez Juan F. , Steidley Brandi L. , Boyaka Prosper N. , Ahmer Brian M. M. 
Published: May 2016

ABSTRACT

Salmonella enterica
is among the most burdensome of foodborne disease agents. There are over 2,600 serovars that cause a range of disease manifestations ranging from enterocolitis to typhoid fever. While there are two vaccines in use in humans to protect against typhoid fever, there are none that prevent enterocolitis. If vaccines preventing enterocolitis were to be developed, they would likely protect against only one or a few serovars. In this report, we tested the hypothesis that probiotic organisms could compete for the preferred nutrient sources of
Salmonella
and thus prevent or treat infection. To this end, we added the
fra
locus, which encodes a utilization pathway for the
Salmonella
-specific nutrient source fructose-asparagine (F-Asn), to the probiotic bacterium
Escherichia coli
Nissle 1917 (Nissle) to increase its ability to compete with
Salmonella
in mouse models. We also tested a metabolically competent, but avirulent,
Salmonella enterica
serovar Typhimurium mutant for its ability to compete with wild-type
Salmonella
. The modified Nissle strain became more virulent and less able to protect against
Salmonella
in some instances. On the other hand, the modified
Salmonella
strain was safe and effective in preventing infection with wild-type
Salmonella
. While we tested for efficacy only against
Salmonella
Typhimurium, the modified
Salmonella
strain may be able to compete metabolically with most, if not all,
Salmonella
serovars, representing a novel approach to control of this pathogen.
Identification of a Lipoteichoic Acid Glycosyltransferase Enzyme Reveals that GW-Domain-Containing Proteins Can Be Retained in the Cell Wall of Listeria monocytogenes in the Absence of Lipoteichoic Acid or Its Modifications
Authors: Percy Matthew G. , Karinou Eleni , Webb Alexander J. , Gründling Angelika 
Published: May 2016

ABSTRACT

Listeria monocytogenes
is a foodborne Gram-positive bacterial pathogen, and many of its virulence factors are either secreted proteins or proteins covalently or noncovalently attached to the cell wall. Previous work has indicated that noncovalently attached proteins with GW (glycine-tryptophan) domains are retained in the cell wall by binding to the cell wall polymer lipoteichoic acid (LTA). LTA is a glycerol phosphate polymer, which is modified in
L. monocytogenes
with galactose and
d
-alanine residues. We identified Lmo0933 as the cytoplasmic glycosyltransferase required for the LTA glycosylation process and renamed the protein GtlA, for
g
lycosyl
t
ransferase
L
TA
A
. Using
L. monocytogenes
mutants lacking galactose or
d
-alanine modifications or the complete LTA polymer, we show that GW domain proteins are retained within the cell wall, indicating that other cell wall polymers are involved in the retention of GW domain proteins. Further experiments revealed peptidoglycan as the binding receptor as a purified GW domain fusion protein can bind to
L. monocytogenes
cells lacking wall teichoic acid (WTA) as well as purified peptidoglycan derived from a wild-type or WTA-negative strain. With this, we not only identify the first enzyme involved in the LTA glycosylation process, but we also provide new insight into the binding mechanism of noncovalently attached cell wall proteins.

IMPORTANCE
Over the past 20 years, a large number of bacterial genome sequences have become available. Computational approaches are used for the genome annotation and identification of genes and encoded proteins. However, the function of many proteins is still unknown and often cannot be predicted bioinformatically. Here, we show that the previously uncharacterized
Listeria monocytogenes
gene
lmo0933
likely codes for a glycosyltransferase required for the decoration of the cell wall polymer lipoteichoic acid (LTA) with galactose residues. Using
L. monocytogenes
mutants lacking LTA modifications or the complete polymer, we show that specific cell wall proteins, often associated with virulence, are retained within the cell wall, indicating that additional cell wall polymers are involved in their retention.
Pseudomonas aeruginosa AmrZ Binds to Four Sites in the
algD
Promoter, Inducing DNA-AmrZ Complex Formation and Transcriptional Activation
Authors: Xu Binjie , Soukup Randal J. , Jones Christopher J. , Fishel Richard , Wozniak Daniel J. 
Published: May 2016

ABSTRACT

During late stages of cystic fibrosis pulmonary infections,
Pseudomonas aeruginosa
often overproduces the exopolysaccharide alginate, protecting the bacterial community from host immunity and antimicrobials. The transcription of the alginate biosynthesis operon is under tight control by a number of factors, including AmrZ, the focus of this study. Interestingly, multiple transcription factors interact with the far-upstream region of this promoter (P
algD
), in which one AmrZ binding site has been identified previously. The mechanisms of AmrZ binding and subsequent activation remain unclear and require more-detailed investigation. In this study, in-depth examinations elucidated four AmrZ binding sites, and their disruption eliminated AmrZ binding and promoter activation. Furthermore, our
in vitro
fluorescence resonance energy transfer experiments suggest that AmrZ holds together multiple binding sites in P
algD
and thereafter induces the formation of higher-order DNA-AmrZ complexes. To determine the importance of interactions between those AmrZ oligomers in the cell, a DNA phasing experiment was performed. P
algD
transcription was significantly impaired when the relative phase between AmrZ binding sites was reversed (5 bp), while a full-DNA-turn insertion (10 bp) restored promoter activity. Taken together, the investigations presented here provide a deeper mechanistic understanding of AmrZ-mediated binding to P
algD
.

IMPORTANCE
Overproduction of the exopolysaccharide alginate provides protection to
Pseudomonas aeruginosa
against antimicrobial treatments and is associated with chronic
P. aeruginosa
infections in the lungs of cystic fibrosis patients. In this study, we combined a variety of microbiological, genetic, biochemical, and biophysical approaches to investigate the activation of the alginate biosynthesis operon promoter by a key transcription factor named AmrZ. This study has provided important new information on the mechanism of activation of this extremely complex promoter.
F
420
H
2
Is Required for Phthiocerol Dimycocerosate Synthesis in Mycobacteria
Authors: Purwantini Endang , Daniels Lacy , Mukhopadhyay Biswarup 
Published: May 2016

ABSTRACT

Phthiocerol dimycocerosates (PDIM) are a group of cell surface-associated apolar lipids of
Mycobacterium tuberculosis
and closely related mycobacteria, such as
Mycobacterium bovis
and
Mycobacterium leprae
. A characteristic methoxy group of these lipids is generated from the methylation of a hydroxyl group of the direct precursors, the phthiotriols. The precursors arise from the reduction of phthiodiolones, the keto intermediates, by a ketoreductase. The putative phthiodiolone ketoreductase (PKR) is encoded by Rv2951c in
M. tuberculosis
and BCG_2972c in
M. bovis
BCG, and these open reading frames (ORFs) encode identical amino acid sequences. We investigated the cofactor requirement of the BCG_2972c protein. A comparative analysis based on the crystallographic structures of similar enzymes identified structural elements for binding of coenzyme F
420
and hydrophobic phthiodiolones in PKR. Coenzyme F
420
is a deazaflavin coenzyme that serves several key functions in pathogenic and nonpathogenic mycobacteria. We found that an
M. bovis
BCG mutant lacking F
420
-dependent glucose-6-phosphate dehydrogenase (Fgd), which generates F
420
H
2
(glucose-6-phosphate + F
420
→ 6-phosphogluconate + F
420
H
2
), was devoid of phthiocerols and accumulated phthiodiolones. When the mutant was provided with F
420
H
2
, a broken-cell slurry of the mutant converted accumulated phthiodiolones to phthiocerols; F
420
H
2
was generated
in situ
from F
420
and glucose-6-phosphate by the action of Fgd. Thus, the reaction mixture was competent in reducing phthiodiolones to phthiotriols (phthiodiolones + F
420
H
2
→ phthiotriols + F
420
), which were then methylated to phthiocerols. These results established the mycobacterial
p
hthiodiolone
k
eto
r
eductase as an
F
420
H
2
-dependent enzyme (fPKR). A phylogenetic analysis of close homologs of fPKR revealed potential F
420
-dependent lipid-modifying enzymes in a broad range of mycobacteria.

IMPORTANCE
Mycobacterium tuberculosis
is the causative agent of tuberculosis, and phthiocerol dimycocerosates (PDIM) protect this pathogen from the early innate immune response of an infected host. Thus, the PDIM synthesis system is a potential target for the development of effective treatments for tuberculosis. The current study shows that a PDIM synthesis enzyme is dependent on the coenzyme F
420
. F
420
is universally present in mycobacteria and absent in humans. This finding expands the number of experimentally validated F
420
-dependent enzymes in
M. tuberculosis
to six, each of which helps the pathogen to evade killing by the host immune system, and one of which activates an antituberculosis drug, PA-824. This work also has relevance to leprosy, since similar waxy lipids are found in
Mycobacterium leprae
.
Cronobacter
spp
Authors: Blackwood Brian P. , Hunter Catherine J. 
Published: May 2016

ABSTRACT

The
Cronobacter
group of pathogens, associated with severe and potentially life-threatening diseases, until recently were classified as a single species,
Enterobacter sakazakii
. The group was reclassified in 2007 into the genus
Cronobacter
as a member of the
Enterobacteriaceae
. This chapter outlines the history behind the epidemiology, analyzes how our understanding of these bacteria has evolved, and highlights the clinical significance the
Cronobacter
spp. have for neonatal and elderly patient populations and treatment of the associated infections.
Chikungunya Virus: Current Perspectives on a Reemerging Virus
Authors: Morrison Clayton R. , Plante Kenneth S. , Heise Mark T. 
Published: May 2016

ABSTRACTChikungunya virus (CHIKV) is a mosquito-borne alphavirus in the familyTogaviridaethat causes outbreaks of debilitating acute and chronic arthralgia in humans. Although historically associated with localized outbreaks in Africa and Asia, recent epidemics in the Indian Ocean region and the Americas have led to the recognition that CHIKV is capable of moving into previously unaffected areas and causing significant levels of human suffering. The severity of CHIKV rheumatic disease, which can severely impact life quality of infected individuals for weeks, months, or even years, combined with the explosive nature of CHIKV outbreaks and its demonstrated ability to quickly spread into new regions, has led to renewed interest in developing strategies for the prevention or treatment of CHIKV-induced disease. Therefore, this chapter briefly discusses the biology of CHIKV and the factors contributing to CHIKV dissemination, while also discussing the pathogenesis of CHIKV-induced disease and summarizing the status of efforts to develop safe and effective therapies and vaccines against CHIKV and related viruses.
Sociomicrobiology and Pathogenic Bacteria
Authors: Xavier Joao B. 
Published: May 2016

ABSTRACT
The study of microbial pathogenesis has been primarily a reductionist science since Koch’s principles. Reductionist approaches are essential to identify the causal agents of infectious disease, their molecular mechanisms of action, and potential drug targets, and much of medicine’s success in the treatment of infectious disease stems from that approach. But many bacteria-caused diseases cannot be explained by a single bacterium. Several aspects of bacterial pathogenesis will benefit from a more holistic approach that takes into account social interaction among bacteria of the same species and between species in consortia such as the human microbiome. The emerging discipline of sociomicrobiology provides a framework to dissect microbial interactions in single and multi-species communities without compromising mechanistic detail. The study of bacterial pathogenesis can benefit greatly from incorporating concepts from other disciplines such as social evolution theory and microbial ecology, where communities, their interactions with hosts, and with the environment play key roles.