bluuebunny/crossref_metadata_2025_split huggingface dataset:
Downregulation of Cellular c-Jun N-Terminal Protein Kinase and NF-κB Activation by Berberine May Result in Inhibition of Herpes Simplex Virus Replication
Authors: Song Siwei , Qiu Min , Chu Ying , Chen Deyan , Wang Xiaohui , Su Airong , Wu Zhiwei 
Published: June 2014

ABSTRACTBerberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. Some reports show that berberine exhibits anti-inflammatory, antitumor, and antiviral properties by modulating multiple cellular signaling pathways, including p53, nuclear factor κB (NF-κB), and mitogen-activated protein kinase. In the present study, we investigated the antiviral effect of berberine against herpes simplex virus (HSV) infection. Current antiherpes medicines such as acyclovir can lessen the recurring activation when used early at infection but are unable to prevent or cure infections where treatment has selected for resistant mutants. In searching for new antiviral agents against herpesvirus infection, we found that berberine reduced viral RNA transcription, protein synthesis, and virus titers in a dose-dependent manner. To elucidate the mechanism of its antiviral activity, the effect of berberine on the individual steps of viral replication cycle of HSV was investigated via time-of-drug addition assay. We found that berberine acted at the early stage of HSV replication cycle, between viral attachment/entry and genomic DNA replication, probably at the immediate-early gene expression stage. We further demonstrated that berberine significantly reduced HSV-induced NF-κB activation, as well as IκB-α degradation and p65 nuclear translocation. Moreover, we found that berberine also depressed HSV-induced c-Jun N-terminal kinase (JNK) phosphorylation but had little effect on p38 phosphorylation. Our results suggest that the berberine inhibition of HSV infection may be mediated through modulating cellular JNK and NF-κB pathways.
Antibiotics for Treatment of Clostridium difficile Infection in Hospitalized Patients with Inflammatory Bowel Disease
Authors: Horton Henry A. , Dezfoli Seper , Berel Dror , Hirsch Julianna , Ippoliti Andrew , McGovern Dermot , Kaur Manreet , Shih David , Dubinsky Marla , Targan Stephan R. , Fleshner Phillip , Vasiliauskas Eric A. , Grein Jonathan , Murthy Rekha , Melmed Gil Y. 
Published: June 2014

ABSTRACT

Patients with inflammatory bowel disease (IBD), namely ulcerative colitis (UC) and Crohn's disease (CD), have worse outcomes with
Clostridium difficile
infection (CDI), including increased readmissions, colectomy, and death. Oral vancomycin is recommended for the treatment of severe CDI, while metronidazole is the standard of care for nonsevere infection. We aimed to assess treatment outcomes of CDI in IBD. We conducted a retrospective observational study of inpatients with CDI and IBD from January 2006 through December 2010. CDI severity was assessed using published criteria. Outcomes included readmission for CDI within 30 days and 12 weeks, length of stay, colectomy, and death. A total of 114 patients met inclusion criteria (UC, 62; CD, 52). Thirty-day readmissions were more common among UC than CD patients (24.2% versus 9.6%;
P
= 0.04). Same-admission colectomy occurred in 27.4% of UC patients and 0% of CD patients (
P
< 0.01). Severe CDI was more common among UC than CD patients (32.2% versus 19.4%;
P
= 0.12) but not statistically significant. Two patients died from CDI-associated complications (UC, 1; CD, 1). Patients with UC and nonsevere CDI had fewer readmissions and shorter lengths of stay when treated with a vancomycin-containing regimen compared to those treated with metronidazole (30-day readmissions, 31.0% versus 0% [
P
= 0.04]; length of stay, 13.62 days versus 6.38 days [
P
= 0.02]). Patients with UC and nonsevere CDI have fewer readmissions and shorter lengths of stay when treated with a vancomycin-containing regimen relative to those treated with metronidazole alone. Patients with ulcerative colitis and CDI should be treated with vancomycin.
Switch-Loop Flexibility Affects Transport of Large Drugs by the Promiscuous AcrB Multidrug Efflux Transporter
Authors: Cha Hi-jea , Müller Reinke T. , Pos Klaas M. 
Published: June 2014

ABSTRACT

Multidrug efflux transporters recognize a variety of structurally unrelated compounds for which the molecular basis is poorly understood. For the
r
esistance
n
odulation and cell
d
ivision (RND) inner membrane component AcrB of the AcrAB-TolC multidrug efflux system from
Escherichia coli
, drug binding occurs at the access and deep binding pockets. These two binding areas are separated by an 11-amino-acid-residue-containing switch loop whose conformational flexibility is speculated to be essential for drug binding and transport. A G616N substitution in the switch loop has a distinct and local effect on the orientation of the loop and on the ability to transport larger drugs. Here, we report a distinct phenotypical pattern of drug recognition and transport for the G616N variant, indicating that drug substrates with minimal projection areas of >70 Å
2
are less well transported than other substrates.
Differential Protection from Tobramycin by Extracellular Polymeric Substances from Acinetobacter baumannii and Staphylococcus aureus Biofilms
Authors: Davenport Emily K. , Call Douglas R. , Beyenal Haluk 
Published: June 2014

ABSTRACT

We investigated biofilms of two pathogens,
Acinetobacter baumannii
and
Staphylococcus aureus
, to characterize mechanisms by which the extracellular polymeric substance (EPS) found in biofilms can protect bacteria against tobramycin exposure. To do so, it is critical to study EPS-antibiotic interactions in a homogeneous environment without mass transfer limitations. Consequently, we developed a method to grow biofilms, harvest EPS, and then augment planktonic cultures with isolated EPS and tobramycin. We demonstrated that planktonic cultures respond differently to being treated with different types of EPS (
A. baumannii
versus
S. aureus
) in the presence of tobramycin. By harvesting EPS from the biofilms, we found that
A. baumannii
EPS acts as a “universal protector” by inhibiting tobramycin activity against bacterial cells regardless of species;
S. aureus
EPS did not show any protective ability in cell cultures. Adding Mg
2+
or Ca
2+
reduced the protective effect of
A. baumannii
EPS. Finally, when we selectively digested the proteins or DNA of the EPS, we found that the protective ability did not change, suggesting that neither has a significant role in protection. To the best of our knowledge, this is the first study that demonstrates how EPS protects pathogens against antibiotics in a homogeneous system without mass transfer limitations. Our results suggest that EPS protects biofilm communities, in part, by adsorbing antibiotics near the surface. This may limit antibiotic diffusion to the bottom of the biofilms but is not likely to be the only mechanism of protection.
Discovery of Gene Cluster for Mycosporine-Like Amino Acid Biosynthesis from Actinomycetales Microorganisms and Production of a Novel Mycosporine-Like Amino Acid by Heterologous Expression
Authors: Miyamoto Kiyoko T. , Komatsu Mamoru , Ikeda Haruo 
Published: June 2014

ABSTRACT

Mycosporines and mycosporine-like amino acids (MAAs), including shinorine (mycosporine-glycine-serine) and porphyra-334 (mycosporine-glycine-threonine), are UV-absorbing compounds produced by cyanobacteria, fungi, and marine micro- and macroalgae. These MAAs have the ability to protect these organisms from damage by environmental UV radiation. Although no reports have described the production of MAAs and the corresponding genes involved in MAA biosynthesis from Gram-positive bacteria to date, genome mining of the Gram-positive bacterial database revealed that two microorganisms belonging to the order
Actinomycetales
,
Actinosynnema mirum
DSM 43827 and
Pseudonocardia
sp. strain P1, possess a gene cluster homologous to the biosynthetic gene clusters identified from cyanobacteria. When the two strains were grown in liquid culture,
Pseudonocardia
sp. accumulated a very small amount of MAA-like compound in a medium-dependent manner, whereas
A. mirum
did not produce MAAs under any culture conditions, indicating that the biosynthetic gene cluster of
A. mirum
was in a cryptic state in this microorganism. In order to characterize these biosynthetic gene clusters, each biosynthetic gene cluster was heterologously expressed in an engineered host,
Streptomyces avermitilis
SUKA22. Since the resultant transformants carrying the entire biosynthetic gene cluster controlled by an alternative promoter produced mainly shinorine, this is the first confirmation of a biosynthetic gene cluster for MAA from Gram-positive bacteria. Furthermore,
S. avermitilis
SUKA22 transformants carrying the biosynthetic gene cluster for MAA of
A. mirum
accumulated not only shinorine and porphyra-334 but also a novel MAA. Structure elucidation revealed that the novel MAA is mycosporine-glycine-alanine, which substitutes
l
-alanine for the
l
-serine of shinorine.
ε-Poly-
l
-Lysine Peptide Chain Length Regulated by the Linkers Connecting the Transmembrane Domains of ε-Poly-
l
-Lysine Synthetase
Authors: Hamano Yoshimitsu , Kito Naoko , Kita Akihiro , Imokawa Yuuki , Yamanaka Kazuya , Maruyama Chitose , Katano Hajime 
Published: June 2014

ABSTRACT

ε-Poly-
l
-lysine (ε-PL), consisting of 25 to 35
l
-lysine residues with linkages between the α-carboxyl groups and ε-amino groups, is produced by
Streptomyces albulus
NBRC14147. ε-PL synthetase (Pls) is a membrane protein with six transmembrane domains (TM1 to TM6) as well as both an adenylation domain and a thiolation domain, characteristic of the nonribosomal peptide synthetases. Pls directly generates ε-PL chain length diversity (25- to 35-mer), but the processes that control the chain length of ε-PL during the polymerization reaction are still not fully understood. Here, we report on the identification of Pls amino acid residues involved in the regulation of the ε-PL chain length. From approximately 12,000 variants generated by random mutagenesis, we found 8 Pls variants that produced shorter chains of ε-PL. These variants have one or more mutations in two linker regions connecting the TM1 and TM2 domains and the TM3 and TM4 domains. In the Pls catalytic mechanism, the growing chain of ε-PL is not tethered to the enzyme, implying that the enzyme must hold the growing chain until the polymerization reaction is complete. Our findings reveal that the linker regions are important contributors to grasp the growing chain of ε-PL.
Knockout of Extracytoplasmic Function Sigma Factor ECF-10 Affects Stress Resistance and Biofilm Formation in Pseudomonas putida KT2440
Authors: Tettmann Beatrix , Dötsch Andreas , Armant Olivier , Fjell Christopher D. , Overhage Joerg 
Published: June 2014

ABSTRACT

Pseudomonas putida
is a Gram-negative soil bacterium which is well-known for its versatile lifestyle, controlled by a large repertoire of transcriptional regulators. Besides one- and two-component regulatory systems, the genome of
P. putida
reveals 19 extracytoplasmic function (ECF) sigma factors involved in the adaptation to changing environmental conditions. In this study, we demonstrate that knockout of extracytoplasmic function sigma factor ECF-10, encoded by open reading frame PP4553, resulted in 2- to 4-fold increased antibiotic resistance to quinolone, β-lactam, sulfonamide, and chloramphenicol antibiotics. In addition, the ECF-10 mutant exhibited enhanced formation of biofilms after 24 h of incubation. Transcriptome analysis using Illumina sequencing technology resulted in the detection of 12 genes differentially expressed (>2-fold) in the ECF-10 knockout mutant strain compared to their levels of expression in wild-type cells. Among the upregulated genes were
ttgA
,
ttgB
, and
ttgC
, which code for the major multidrug efflux pump TtgABC in
P. putida
KT2440. Investigation of an ECF-10 and
ttgA
double-knockout strain and a
ttgABC
-overexpressing strain demonstrated the involvement of efflux pump TtgABC in the stress resistance and biofilm formation phenotypes of the ECF-10 mutant strain, indicating a new role for this efflux pump beyond simple antibiotic resistance in
P. putida
KT2440.
Platelet Endothelial Cell Adhesion Molecule-1, a Putative Receptor for the Adhesion of Streptococcus pneumoniae to the Vascular Endothelium of the Blood-Brain Barrier
Authors: Iovino Federico , Molema Grietje , Bijlsma Jetta J. E. 
Published: June 2014

ABSTRACT

The Gram-positive bacterium
Streptococcus pneumoniae
is the main causative agent of bacterial meningitis.
S. pneumoniae
is thought to invade the central nervous system via the bloodstream by crossing the vascular endothelium of the blood-brain barrier. The exact mechanism by which pneumococci cross endothelial cell barriers before meningitis develops is unknown. Here, we investigated the role of PECAM-1/CD31, one of the major endothelial cell adhesion molecules, in
S. pneumoniae
adhesion to vascular endothelium of the blood-brain barrier. Mice were intravenously infected with pneumococci and sacrificed at various time points to represent stages preceding meningitis. Immunofluorescent analysis of brain tissue of infected mice showed that pneumococci colocalized with PECAM-1. In human brain microvascular endothelial cells (HBMEC) incubated with
S. pneumoniae
, we observed a clear colocalization between PECAM-1 and pneumococci. Blocking of PECAM-1 reduced the adhesion of
S. pneumoniae
to endothelial cells
in vitro
, implying that PECAM-1 is involved in pneumococcal adhesion to the cells. Furthermore, using endothelial cell protein lysates, we demonstrated that
S. pneumoniae
physically binds to PECAM-1. Moreover, both
in vitro
and
in vivo
PECAM-1 colocalizes with the
S. pneumoniae
adhesion receptor pIgR. Lastly, immunoprecipitation experiments revealed that PECAM-1 can physically interact with pIgR. In summary, we show for the first time that blood-borne
S. pneumoniae
colocalizes with PECAM-1 expressed by brain microvascular endothelium and that, in addition, they colocalize with pIgR. We hypothesize that this interaction plays a role in pneumococcal binding to the blood-brain barrier vasculature prior to invasion into the brain.
Benzylidene Acylhydrazides Inhibit Chlamydial Growth in a Type III Secretion- and Iron Chelation-Independent Manner
Authors: Bao Xiaofeng , Gylfe Åsa , Sturdevant Gail L. , Gong Zheng , Xu Shuang , Caldwell Harlan D. , Elofsson Mikael , Fan Huizhou 
Published: June 2014

ABSTRACT

Chlamydiae are widespread Gram-negative pathogens of humans and animals. Salicylidene acylhydrazides, developed as inhibitors of type III secretion system (T3SS) in
Yersinia
spp., have an inhibitory effect on chlamydial infection. However, these inhibitors also have the capacity to chelate iron, and it is possible that their antichlamydial effects are caused by iron starvation. Therefore, we have explored the modification of salicylidene acylhydrazides with the goal to uncouple the antichlamydial effect from iron starvation. We discovered that benzylidene acylhydrazides, which cannot chelate iron, inhibit chlamydial growth. Biochemical and genetic analyses suggest that the derivative compounds inhibit chlamydiae through a T3SS-independent mechanism. Four single nucleotide polymorphisms were identified in a
Chlamydia muridarum
variant resistant to benzylidene acylhydrazides, but it may be necessary to segregate the mutations to differentiate their roles in the resistance phenotype. Benzylidene acylhydrazides are well tolerated by host cells and probiotic vaginal
Lactobacillus
species and are therefore of potential therapeutic value.
Fifty Years after the Replicon Hypothesis: Cell-Specific Master Regulators as New Players in Chromosome Replication Control
Authors: Wolański Marcin , Jakimowicz Dagmara , Zakrzewska-Czerwińska Jolanta 
Published: June 2014

ABSTRACT

Numerous free-living bacteria undergo complex differentiation in response to unfavorable environmental conditions or as part of their natural cell cycle. Developmental programs require the
de novo
expression of several sets of genes responsible for morphological, physiological, and metabolic changes, such as spore/endospore formation, the generation of flagella, and the synthesis of antibiotics. Notably, the frequency of chromosomal replication initiation events must also be adjusted with respect to the developmental stage in order to ensure that each nascent cell receives a single copy of the chromosomal DNA. In this review, we focus on the master transcriptional factors, Spo0A, CtrA, and AdpA, which coordinate developmental program and which were recently demonstrated to control chromosome replication. We summarize the current state of knowledge on the role of these developmental regulators in synchronizing the replication with cell differentiation in
Bacillus subtilis
,
Caulobacter crescentus
, and
Streptomyces coelicolor
, respectively.
Identification of Three Noncontiguous Regions on Bacillus anthracis Plasmid pXO1 That Are Important for Its Maintenance
Authors: Pomerantsev Andrei P. , Chang Zanetta , Rappole Catherine , Leppla Stephen H. 
Published: June 2014

ABSTRACT

Bacillus anthracis
pXO1 minireplicon (MR) plasmid consisting of open reading frames (ORFs) GBAA_pXO1_0020 to GBAA_pXO1_0023 is not stably maintained in
B. anthracis
, whereas the full-size parent pXO1 plasmid (having 181,677 bp and 217 ORFs) is extremely stable under the same growth conditions. Two genetic tools developed for DNA manipulation in
B. anthracis
(Cre-
loxP
and Flp-
FRT
systems) were used to identify pXO1 regions important for plasmid stability. We localized a large segment of pXO1 that enables stable plasmid maintenance during vegetative growth. Further genetic analysis identified three genes that are necessary for pXO1 maintenance:
amsP
(GBAA_pXO1_0069),
minP
(GBAA_pXO1_0082), and
sojP
(GBAA_pXO1_0084). Analysis of conserved domains in the corresponding proteins indicated that only AmsP (activator of maintenance system of pXO1) is predicted to bind DNA, due to its strong helix-turn-helix domain. Two conserved domains were found in the MinP protein (Min protein from pXO1): an N-terminal domain having some similarity to the
B. anthracis
septum site-determining protein MinD and a C-terminal domain that resembles a baculovirus single-stranded-DNA-binding protein. The SojP protein (Soj from pXO1) contains putative Walker box motifs and belongs to the ParA family of ATPases. No sequences encoding other components of type I plasmid partition systems, namely,
cis
-acting centromere
parS
and its binding ParB protein, were identified within the pXO1 genome. A model describing the role of the MinP protein in pXO1 distribution between daughter cells is proposed.
TraK and TraB Are Conserved Outer Membrane Proteins of the Neisseria gonorrhoeae Type IV Secretion System and Are Expressed at Low Levels in Wild-Type Cells
Authors: Ramsey Meghan E. , Hackett Kathleen T. , Bender Tobias , Kotha Chaitra , van der Does Chris , Dillard Joseph P. 
Published: June 2014

ABSTRACT

Neisseria gonorrhoeae
uses a type IV secretion system (T4SS) to secrete chromosomal DNA into the medium, and this DNA is effective in transforming other gonococci via natural transformation. In addition, the T4SS is important in the initial stages of biofilm development and mediates intracellular iron uptake in the absence of TonB. To better understand the mechanism of type IV secretion in
N. gonorrhoeae
, we examined the expression levels and localization of two predicted T4SS outer membrane proteins, TraK and TraB, in the wild-type strain as well as in overexpression strains and in a strain lacking all of the T4SS proteins. Despite very low sequence similarity to known homologues, TraB (VirB10 homolog) and TraK (VirB9 homolog) localized similarly to related proteins in other systems. Additionally, we found that TraV (a VirB7 homolog) interacts with TraK, as in other T4SSs. However, unlike in other systems, neither TraK nor TraB required the presence of other T4SS components for proper localization. Unlike other gonococcal T4SS proteins we have investigated, protein levels of the outer membrane proteins TraK and TraB were extremely low in wild-type cells and were undetectable by Western blotting unless overexpressed or tagged with a FLAG3 triple-epitope tag. Localization of TraK-FLAG3 in otherwise wild-type cells using immunogold electron microscopy of thin sections revealed a single gold particle on some cells. These results suggest that the gonococcal T4SS may be present in single copy per cell and that small amounts of T4SS proteins TraK and TraB are sufficient for DNA secretion.
Psychiatric disorders following fetal death: a population-based cohort study
Authors: Munk-Olsen Trine , Bech Bodil Hammer , Vestergaard Mogens , Li Jiong , Olsen Jørn , Laursen Thomas Munk 
Published: June 2014

ObjectivesWomen have increased risks of severe mental disorders after childbirth and death of a child, but it remains unclear whether this association also applies to fetal loss and, if so, to which extent. We studied the risk of any inpatient or outpatient psychiatric treatment during the time period from 12 months before to 12 months after fetal death.DesignCohort study using Danish population-based registers.SettingDenmark.ParticipantsA total of 1 112 831 women born in Denmark from 1960 to 1995 were included. In total, 87 687cases of fetal death (International Classification of Disease-10 codes for spontaneous abortion or stillbirth) were recorded between 1996 and 2010.Primary and secondary outcome measuresThe main outcome measures were incidence rate ratios (risk of first psychiatric inpatient or outpatient treatment).ResultsA total of 1379 women had at least one psychiatric episode during follow-up from the year before fetal death to the year after. Within the first few months after the loss, women had an increased risk of psychiatric contact, IRR: 1.51 (95% CI 1.15 to 1.99). In comparison, no increased risk of psychiatric contact was found for the period before fetal death. The risk of experiencing a psychiatric episode was highest for women with a loss occurring after 20 weeks of gestation (12 month probability: 1.95%, 95% CI 1.50 to 2.39).ConclusionsFetal death was associated with a transient increased risk of experiencing a first-time episode of a psychiatric disorder, primarily adjustment disorders. The risk of psychiatric episodes tended to increase with increasing gestational age at the time of the loss.