bluuebunny/crossref_metadata_2025_split huggingface dataset:
TAK1 contributes to the enhanced responsiveness of LTB4-treated neutrophils to Toll-like receptor ligands
Authors: Gaudreault Éric , Paquet-Bouchard Carine , Fiola Stéphanie , Le Bel Manon , Lacerte Patricia , Shio Marina Tiemi , Olivier Martin , Gosselin Jean 
Published: July 2012

Abstract
Pattern-recognition receptors such as Toll-like receptors (TLRs) are essential sensors implicated in the early and efficient innate immune response against pathogens. We have previously demonstrated that leukotriene B 4 (LTB 4 ) has the capacity to enhance leukocyte responses to TLR9 ligands and to control viral infection. In this report, we provide evidence that LTB 4 treatment of human neutrophils leads to a potentiation in proinflammatory cytokine secretion induced by various myeloid differentiation factor 88-dependent TLR agonists. LTB 4 failed to enhance TLR mRNA levels as well as expression of TLR2 and TLR4 receptors, suggesting that LTB 4 acts through intracellular mechanism(s) to potentiate neutrophil responses to TLR ligands. We found that while IRAK can be activated by LTB 4 , this process is dispensable to LTB 4 to potentiate neutrophil responses to TLR ligands since pretreatment of neutrophils with IRAK1/4 inhibitor did not affect its potentiating effects. However, our data clearly show that LTB 4 treatment of neutrophils led to the phosphorylation of downstream signaling molecules, TAK1 and p38, a process found essential to observe an increased secretion of cytokines by neutrophils activated with TLR ligands. Pretreatment of neutrophils with TAK1 or p38 kinase inhibitors strongly repressed the effect of LTB 4 on cytokine synthesis by neutrophils stimulated with LTA, LPS or CpG. The same pattern was observed in agonist-treated human embryonic kidney 293 cells transfected with TAK1-targeting siRNA where secretion of IL-8 was significantly reduced to basal levels. These results indicate that TAK1 and p38 kinases appear to be central in the ‘priming effect’ of LTB 4 on neutrophils to enhance response to TLR ligands.
Urinary continence after radical prostatectomy: Predictive factors of recovery after 1 year of surgery
Authors: Jeong Seong Jin , Kim Hyeon June , Kim Jeong Hyun , Oh Jong Jin , Lee Sang Cheol , Jeong Chang Wook , Yoon Cheol Yong , Hong Sung Kyu , Byun Seok‐Soo , Lee Sang Eun 
Published: July 2012

Objectives:  To evaluate the clinical prognosis of incontinence and to determine the predictors for further recovery of urinary continence in patients not achieving urinary continence within 1 year after radical prostatectomy.Methods:  A total of 708 patients were evaluated regarding urinary continence status at 1 year after surgery from a prospectively maintained radical prostatectomy database. Of these, 73 (10.3%) did not recover urinary continence within 1 year after surgery. For these patients, incontinence status and the number of pads for urinary control were assessed serially.Results:  In 708 patients, factors associated with the recovery of urinary continence within 1 year after radical prostatectomy were membranous urethral length, prostatic apex shape and patient age. Among 73 patients with urinary incontinence, 41 (56.2%) achieved urinary continence with a mean time of 15.4 months subsequent to the first year after radical prostatectomy (baseline). A younger age at surgery (P = 0.027) and one pad being required (vs≥2 pads) at baseline (P = 0.046) were identified as independent factors for achievement of urinary continence within a further 2 years. Only the number of pads was a significant factor for further recovery of urinary continence in the longer follow up (hazard ratio 0.36, P = 0.029).Conclusion:  Compared with factors related to the prostate or membranous urethra, patient age and severity of incontinence at 1 year after radical prostatectomy are more strongly related to the recovery of urinary continence later than 1 year after surgery. These findings might help to decide whether a definite treatment is required for persistent incontinence beyond 1 year after radical prostatectomy.
Fatty Acids Regulate Stress Resistance and Virulence Factor Production for Listeria monocytogenes
Authors: Sun Yvonne , Wilkinson Brian J. , Standiford Theodore J. , Akinbi Henry T. , O'Riordan Mary X. D. 
Published: July 2012

ABSTRACT

Fatty acids (FAs) are the major structural component of cellular membranes, which provide a physical and chemical barrier that insulates intracellular reactions from environmental fluctuations. The native composition of membrane FAs establishes the topological and chemical parameters for membrane-associated functions and is therefore modulated diligently by microorganisms especially in response to environmental stresses. However, the consequences of altered FA composition during host-pathogen interactions are poorly understood. The food-borne pathogen
Listeria monocytogenes
contains mostly saturated branched-chain FAs (BCFAs), which support growth at low pH and low temperature. In this study, we show that anteiso-BCFAs enhance bacterial resistance against phagosomal killing in macrophages. Specifically, BCFAs protect against antimicrobial peptides and peptidoglycan hydrolases, two classes of phagosome antimicrobial defense mechanisms. In addition, the production of the critical virulence factor, listeriolysin O, was compromised by FA modulation, suggesting that FAs play a key role in virulence regulation. In summary, our results emphasize the significance of FA metabolism, not only in bacterial virulence regulation but also in membrane barrier function by providing resistance against host antimicrobial stress.
Functional Characterization of the Role of the Chromosome I Partitioning System in Genome Segregation in Deinococcus radiodurans
Authors: Charaka Vijay Kumar , Misra Hari S. 
Published: July 2012

ABSTRACTDeinococcus radiodurans, a radiation-resistant bacterium, harbors a multipartite genome. Chromosome I contains three putative centromeres (segS1,segS2, andsegS3), and ParA (ParA1) and ParB (ParB1) homologues. The ParB1 interaction withsegSwas sequence specific, and ParA1 was shown to be a DNA binding ATPase. The ATPase activity of ParA1 was stimulated whensegSelements were coincubated with ParB1, but the greatest increase was observed withsegS3. ParA1 incubated with thesegS-ParB1 complex showed increased light scattering in the absence of ATP. In the presence of ATP, this increase was continued withsegS1-ParA1B1 andsegS2-ParA1B1 complexes, while it decreased rapidly after an initial increase for 30 min in the case ofsegS3.D. radioduranscells expressing green fluorescent protein (GFP)-ParB1 produced foci on nucleoids, and the ΔparB1mutant showed growth retardation and ∼13%-higher anucleation than the wild type. Unstable mini-F plasmids carryingsegS1andsegS2showed inheritance inEscherichia coliwithout ParA1B1, whilesegS3-mediated plasmid stability required the intransexpression of ParA1B1. Unlike untransformedE. colicells, cells harboring pDAGS3, a plasmid carryingsegS3and also expressing ParB1-GFP, produced discrete GFP foci on nucleoids. These findings suggested that bothsegSelements and the ParA1B1 proteins ofD. radioduransare functionally active and have a role in genome segregation.
Factors Limiting SOS Expression in Log-Phase Cells of Escherichia coli
Authors: Massoni Shawn C. , Leeson Michael C. , Long Jarukit Edward , Gemme Kristin , Mui Alice , Sandler Steven J. 
Published: July 2012

ABSTRACTInEscherichia coli, RecA–single-stranded DNA (RecA-ssDNA) filaments catalyze DNA repair, recombination, and induction of the SOS response. It has been shown that, while many (15 to 25%) log-phase cells have RecA filaments, few (about 1%) are induced for SOS. It is hypothesized that RecA's ability to induce SOS expression in log-phase cells is repressed because of the potentially detrimental effects of SOS mutagenesis. To test this, mutations were sought to produce a population where the number of cells with SOS expression more closely equaled the number of RecA filaments. Here, it is shown that deletingradA(important for resolution of recombination structures) and increasingrecAtranscription 2- to 3-fold with arecAo1403operator mutation act independently to minimally satisfy this condition. This allows 24% of mutant cells to have elevated levels of SOS expression, a percentage similar to that of cells with RecA-green fluorescent protein (RecA-GFP) foci. In anxthA(exonuclease III gene) mutant where there are 3-fold more RecA loading events,recX(a destabilizer of RecA filaments) must be additionally deleted to achieve a population of cells where the percentage having elevated SOS expression (91%) nearly equals the percentage with at least one RecA-GFP focus (83%). It is proposed that, in thexthAmutant, there are three independent mechanisms that repress SOS expression in log-phase cells. These are the rapid processing of RecA filaments by RadA, maintaining the concentration of RecA below a critical level, and the destabilizing of RecA filaments by RecX. Only the first two mechanisms operate independently in a wild-type cell.
Membrane Disruption by Antimicrobial Fatty Acids Releases Low-Molecular-Weight Proteins from Staphylococcus aureus
Authors: Parsons Joshua B. , Yao Jiangwei , Frank Matthew W. , Jackson Pamela , Rock Charles O. 
Published: July 2012

ABSTRACT

The skin represents an important barrier for pathogens and is known to produce fatty acids that are toxic toward Gram-positive bacteria. A screen of fatty acids as growth inhibitors of
Staphylococcus aureus
revealed structure-specific antibacterial activity. Fatty acids like oleate (18:1Δ9) were nontoxic, whereas palmitoleate (16:1Δ9) was a potent growth inhibitor. Cells treated with 16:1Δ9 exhibited rapid membrane depolarization, the disruption of all major branches of macromolecular synthesis, and the release of solutes and low-molecular-weight proteins into the medium. Other cytotoxic lipids, such as glycerol ethers, sphingosine, and acyl-amines blocked growth by the same mechanisms. Nontoxic 18:1Δ9 was used for phospholipid synthesis, whereas toxic 16:1Δ9 was not and required elongation to 18:1Δ11 prior to incorporation. However, blocking fatty acid metabolism using inhibitors to prevent acyl-acyl carrier protein formation or glycerol-phosphate acyltransferase activity did not increase the toxicity of 18:1Δ9, indicating that inefficient metabolism did not play a determinant role in fatty acid toxicity. Nontoxic 18:1Δ9 was as toxic as 16:1Δ9 in a strain lacking wall teichoic acids and led to growth arrest and enhanced release of intracellular contents. Thus, wall teichoic acids contribute to the structure-specific antimicrobial effects of unsaturated fatty acids. The ability of poorly metabolized 16:1 isomers to penetrate the cell wall defenses is a weakness that has been exploited by the innate immune system to combat
S. aureus
.
Epoxide-Mediated CifR Repression of
cif
Gene Expression Utilizes Two Binding Sites in Pseudomonas aeruginosa
Authors: Ballok Alicia E. , Bahl Christopher D. , Dolben Emily L. , Lindsay Allia K. , St. Laurent Jessica D. , Hogan Deborah A. , Madden Dean R. , O'Toole George A. 
Published: July 2012

ABSTRACT

Pseudomonas aeruginosa
secretes an epoxide hydrolase virulence factor that reduces the apical membrane expression of ABC transporters such as the cystic fibrosis transmembrane conductance regulator (CFTR). This virulence factor, named CFTR inhibitory factor (Cif), is regulated by a TetR-family, epoxide-responsive repressor known as CifR via direct binding and repression. We identified two sites of CifR binding in the intergenic space between
cifR
and
morB
, the first gene in the operon containing the
cif
gene. We have mapped these binding sites and found they are 27 bp in length, and they overlap the −10 and +1 sites of both the
cifR
and
morB
regulatory region and the start of transcription, respectively. In addition, we found that CifR binds to each repression site with differing affinity. Mutagenesis of these binding sites resulted in a loss of DNA binding
in vitro
, and mutation of one of these sites
in vivo
resulted in an increase in transcription of both the
cif
and
cifR
genes. We characterized
cif
and
cifR
gene expression in sputum and found that, whereas
cif
gene expression varied relative to an
in vitro
coculture control,
cifR
gene expression was consistently higher. Analysis of a longitudinal sample of CF isolates from nine patients revealed that Cif protein was expressed over time, although variably, and these changes could not be linked to mutations in the
cifR
gene or the promoters of these genes. Finally, we tested CifR responsiveness to other epoxides and showed that CifR can respond to multiple epoxides to various degrees.
Interaction of the Extreme N-Terminal Region of FliH with FlhA Is Required for Efficient Bacterial Flagellar Protein Export
Authors: Hara Noritaka , Morimoto Yusuke V. , Kawamoto Akihiro , Namba Keiichi , Minamino Tohru 
Published: July 2012

ABSTRACT

The flagellar type III protein export apparatus plays an essential role in the formation of the bacterial flagellum. FliH forms a complex along with FliI ATPase and is postulated to provide a link between FliI ring formation and flagellar protein export. Two tryptophan residues of FliH, Trp7 and Trp10, are required for the effective docking of the FliH-FliI complex to the export gate made of six membrane proteins. However, it remains unknown which export gate component interacts with these two tryptophan residues. Here, we performed targeted photo-cross-linking of the extreme N-terminal region of FliH (FliH
EN
) with its binding partners. We replaced Trp7 and Trp10 of FliH with
p
-benzoyl-phenylalanine (pBPA), a photo-cross-linkable unnatural amino acid, to produce FliH(W7pBPA) and FliH(W10pBPA). They were both functional and were photo-cross-linked with one of the export gate proteins, FlhA, but not with the other gate proteins, indicating that these two tryptophan residues are in close proximity to FlhA. Mutant FlhA proteins that are functional in the presence of FliH and FliI but not in their absence showed a significantly reduced function also by N-terminal FliH mutations even in the presence of FliI. We suggest that the interaction of FliH
EN
with FlhA is required for anchoring the FliI hexamer ring to the export gate for efficient flagellar protein export.
Activity of the Osmotically Regulated
yqiHIK
Promoter from Bacillus subtilis Is Controlled at a Distance
Authors: Fischer Kathleen E. , Bremer Erhard 
Published: July 2012

ABSTRACT

The
yqiHIK
gene cluster from
Bacillus subtilis
is predicted to encode an extracellular lipoprotein (YqiH), a secreted
N
-acetylmuramoyl-
l
-alanine amidase (YqiI), and a cytoplasmic glycerophosphodiester phosphodiesterase (YqiK). Reverse transcriptase PCR (RT-PCR) analysis showed that the
yqiHIK
genes are transcribed as an operon. Consistent with the
in silico
prediction, we found that the purified YqiI protein exhibited hydrolytic activity toward peptidoglycan sacculi. Transcription studies with
yqiH-treA
reporter fusion strains revealed that the expression of
yqiHIK
is subjected to finely tuned osmotic control, but enhanced expression occurs only in severely osmotically stressed cells. Primer extension analysis pinpointed the osmotically responsive
yqiHIK
promoter, and site-directed mutagenesis was employed to assess functionally important sequences required for promoter activity and osmotic control. Promoter variants with constitutive activity were isolated. A deletion analysis of the
yqiHIK
regulatory region showed that a 53-bp AT-rich DNA segment positioned 180 bp upstream of the −35 sequence is critical for the activity and osmotic regulation of the
yqiHIK
promoter. Hence, the expression of
yqiHIK
is subjected to genetic control at a distance. Upon the onset of growth of cells of the
B. subtilis
wild-type strain in high-salinity medium (1.2 M NaCl), we observed gross morphological deformations of cells that were then reversed to a rod-shaped morphology again when the cells had adjusted to the high-salinity environment. The products of the
yqiHIK
gene cluster were not critical for reestablishing rod-shaped morphology, but the deletion of this operon yielded a
B. subtilis
mutant impaired in growth in a defined minimal medium and at high salinity.
Novel Rapidly Diversifiable Antimicrobial RNA Polymerase Switch Region Inhibitors with Confirmed Mode of Action in Haemophilus influenzae
Authors: Buurman Ed T. , Foulk Melinda A. , Gao Ning , Laganas Valerie A. , McKinney David C. , Moustakas Demetri T. , Rose Jonathan A. , Shapiro Adam B. , Fleming Paul R. 
Published: July 2012

ABSTRACT

A series of inhibitors with a squaramide core was synthesized following its discovery in a high-throughput screen for novel inhibitors of a transcription-coupled translation assay using
Escherichia coli
S30 extracts. The inhibitors were inactive when the plasmid substrate was replaced with mRNA, suggesting they interfered with transcription. This was confirmed by their inhibition of purified
E. coli
RNA polymerase. The series had antimicrobial activity against efflux-negative strains of
E. coli
and
Haemophilus influenzae
. Like rifampin, the squaramides preferentially inhibited synthesis of RNA and protein over fatty acids, peptidoglycan, and DNA. However, squaramide-resistant mutants were not cross-resistant to rifampin. Nine different mutations were found in parts of
rpoB
or
rpoC
that together encode the so-called switch region of RNA polymerase. This is the binding site of the natural antibiotics myxopyronin, corallopyronin, and ripostatin and the drug fidaxomicin. Computational modeling using the X-ray crystal structure of the myxopyronin-bound RNA polymerase of
Thermus thermophilus
suggests a binding mode of these inhibitors that is consistent with the resistance mutations. The squaramides are the first reported non-natural-product-related, rapidly diversifiable antibacterial inhibitors acting via the switch region of RNA polymerase.
Residues in the N-Terminal Domain of MutL Required for Mismatch Repair in Bacillus subtilis
Authors: Bolz Nicholas J. , Lenhart Justin S. , Weindorf Steven C. , Simmons Lyle A. 
Published: July 2012

ABSTRACT

Mismatch repair is a highly conserved pathway responsible for correcting DNA polymerase errors incorporated during genome replication. MutL is a mismatch repair protein known to coordinate several steps in repair that ultimately results in strand removal following mismatch identification by MutS. MutL homologs from bacteria to humans contain well-conserved N-terminal and C-terminal domains. To understand the contribution of the MutL N-terminal domain to mismatch repair, we analyzed 14 different missense mutations in
Bacillus subtilis
MutL that were conserved with missense mutations identified in the human MutL homolog MLH1 from patients with hereditary nonpolyposis colorectal cancer (HNPCC). We characterized missense mutations in or near motifs important for ATP binding, ATPase activity, and DNA binding. We found that 13 of the 14 missense mutations conferred a substantial defect to mismatch repair
in vivo
, while three mutant alleles showed a dominant negative increase in mutation frequency to wild-type
mutL
. We performed immunoblot analysis to determine the relative stability of each mutant protein
in vivo
and found that, although most accumulated, several mutant proteins failed to maintain wild-type levels, suggesting defects in protein stability. The remaining missense mutations located in areas of the protein important for DNA binding, ATP binding, and ATPase activities of MutL compromised repair
in vivo
. Our results define functional residues in the N-terminal domain of
B. subtilis
MutL that are critical for mismatch repair
in vivo
.
Torsional injuries of the lower limb: an analysis of the frictional torque between different types of football turf and the shoe outsole
Authors: Smeets Kristof , Jacobs Pieter , Hertogs Robbin , Luyckx Jean-Philippe , Innocenti Bernardo , Corten Kristoff , Ekstrand Jan , Bellemans Johan 
Published: July 2012

BackgroundFootball turf is increasingly used in European soccer competition. Little is known on the rotational torque that players experience on these fields. High rotational torques between the shoe outsole and the sports surface has been correlated with torsional injuries of the lower limb and knee.PurposeTo evaluate the effect of six parameters that could influence the rotational torque between the shoe outsole and the latest generation football turf.Study designControlled laboratory study.MethodsA testing apparatus was constructed to measure the peak torque generated during a controlled rotation of the foot. Six parameters that could potentially influence the frictional forces, were considered: (1) the sports surface, (2) the shoe outsole cleat design, (3) the weather conditions, (4) the weight, (5) the presence of an impact and (6) the direction of rotation.ResultsThe football turf without infill showed significantly lower frictional torques than natural grass whereas a football turf with sand/rubber infill had significantly higher torques. Blades were associated with significantly higher torques than studs on natural grass and on one football turf with sand/rubber infill. Dry weather was associated with higher torques only for the football turf without infill. The torque increased linearly and significantly with an increasing vertical load. The rotational torque increased significantly following an impact. Torques on external rotational movements were significantly higher with blades.ConclusionsImportant differences in rotational torques are found and could be seen as potential risk factors for torsional injuries of the lower limb.
The effectiveness of a preconditioning programme on preventing running-related injuries in novice runners: a randomised controlled trial
Authors: Bredeweg Steef W , Zijlstra Sjouke , Bessem Bram , Buist Ida 
Published: July 2012

ObjectivesThere is no consensus on the aetiology and prevention of running-related injuries in runners. Preconditioning studies among different athlete populations show positive effects on the incidence of sports injuries.HypothesisA 4-week preconditioning programme in novice runners will reduce the incidence of running-related injuries.Study designRandomised controlled clinical trial; level of evidence, 1.MethodsNovice runners (N=432) prepared for a four-mile recreational running event. Participants were allocated to the 4-week preconditioning (PRECON) group (N=211) or the control group (N=221). The PRECON group started a 4-week training programme, prior to the running programme, with walking and hopping exercises. After the 4-week period both groups started a 9-week running programme. In both groups information was registered on running exposure and running-related injuries (RRIs) using an internet-based running log. Primary outcome measure was RRIs per 100 runners. An RRI was defined as any musculoskeletal complaint of the lower extremity or lower back causing restriction of running for at least a week.ResultsThe incidence of RRIs was 15.2% in the PRECON group and 16.8% in the control group. The difference in RRIs between the groups was not significant (χ2=0.161, df=1, p=0.69).ConclusionThis prospective study demonstrated that a 4-week PRECON programme with walking and hopping exercises had no influence on the incidence of RRIs in novice runners.