bluuebunny/crossref_metadata_2025_split huggingface dataset:
Small-Molecule Inhibitors of Staphylococcus aureus RnpA-Mediated RNA Turnover and tRNA Processing
Authors: Eidem Tess M. , Lounsbury Nicole , Emery John F. , Bulger Jeffrey , Smith Andrew , Abou-Gharbia Magid , Childers Wayne , Dunman Paul M. 
Published: January 2015

ABSTRACT

New agents are urgently needed for the therapeutic treatment of
Staphylococcus aureus
infections. In that regard,
S. aureus
RNase RnpA may represent a promising novel dual-function antimicrobial target that participates in two essential cellular processes, RNA degradation and tRNA maturation. Accordingly, we previously used a high-throughput screen to identify small-molecule inhibitors of the RNA-degrading activity of the enzyme and showed that the RnpA inhibitor RNPA1000 is an attractive antimicrobial development candidate. In this study, we used a series of
in vitro
and cellular assays to characterize a second RnpA inhibitor, RNPA2000, which was identified in our initial screening campaign and is structurally distinct from RNPA1000. In doing so, it was found that
S. aureus
RnpA does indeed participate in 5′-precursor tRNA processing, as was previously hypothesized. Further, we show that RNPA2000 is a bactericidal agent that inhibits both RnpA-associated RNA degradation and tRNA maturation activities both
in vitro
and within
S. aureus
. The compound appears to display specificity for RnpA, as it did not significantly affect the
in vitro
activities of unrelated bacterial or eukaryotic ribonucleases and did not display measurable human cytotoxicity. Finally, we show that RNPA2000 exhibits antimicrobial activity and inhibits tRNA processing in efflux-deficient Gram-negative pathogens. Taken together, these data support the targeting of RnpA for antimicrobial development purposes, establish that small-molecule inhibitors of both of the functions of the enzyme can be identified, and lend evidence that RnpA inhibitors may have broad-spectrum antimicrobial activities.
Examining the Use of Ceftaroline in the Treatment of Streptococcus pneumoniae Meningitis with Reference to Human Cathelicidin LL-37
Authors: Sakoulas George , Nonejuie Poochit , Kullar Ravina , Pogliano Joseph , Rybak Michael J. , Nizet Victor 
Published: January 2015

ABSTRACT

Five cases of bacterial meningitis treated with ceftaroline (4
Streptococcus pneumoniae
and 1
Staphylococcus aureus
) are summarized here. The pharmacodynamics of human cathelicidin LL-37 and ceftaroline were evaluated against
S. pneumoniae
. Patients who received ceftaroline 600 mg every 8 h (q8h) (1
S. aureus
and 3
S. pneumoniae
) were successfully treated; treatment failed in 1 patient with
S. pneumoniae
who received 600 mg q12h. Ceftaroline increased the negative surface charge and sensitized
S. pneumoniae
to killing by LL-37, a peptide implicated in blood-brain barrier defense.
Global Analysis of Posttranscriptional Regulation by GlmY and GlmZ in Enterohemorrhagic Escherichia coli O157:H7
Authors: Gruber Charley C. , Sperandio Vanessa 
Published: January 2015

ABSTRACT

Enterohemorrhagic
Escherichia coli
(EHEC) is a significant human pathogen and is the cause of bloody diarrhea and hemolytic-uremic syndrome. The virulence repertoire of EHEC includes the genes within the locus of enterocyte effacement (LEE) that are largely organized in five operons,
LEE1
to
LEE5
, which encode a type III secretion system, several effectors, chaperones, and regulatory proteins. In addition, EHEC also encodes several non-LEE-encoded effectors and fimbrial operons. The virulence genes of this pathogen are under a large amount of posttranscriptional regulation. The small RNAs (sRNAs) GlmY and GlmZ activate the translation of glucosamine synthase (GlmS) in
E. coli
K-12, and in EHEC they destabilize the 3′ fragments of the
LEE4
and
LEE5
operons and promote translation of the non-LEE-encoded effector EspFu. We investigated the global changes of EHEC gene expression governed by GlmY and GlmZ using RNA sequencing and gene arrays. This study extends the known effects of GlmY and GlmZ regulation to show that they promote expression of the curli adhesin, repress the expression of tryptophan metabolism genes, and promote the expression of acid resistance genes and the non-LEE-encoded effector NleA. In addition, seven novel EHEC-specific sRNAs were identified using RNA sequencing, and three of them—sRNA56, sRNA103, and sRNA350—were shown to regulate urease, fimbria, and the LEE, respectively. These findings expand the knowledge of posttranscriptional regulation in EHEC.
Identification of a Putative Flavin Adenine Dinucleotide-Binding Monooxygenase as a Regulator for Myxococcus xanthus Development
Authors: Cao Shanshan , Wu Miaomiao , Xu Shihui , Yan Xiuwen , Mao Xiaohua 
Published: January 2015

ABSTRACTGene clusters coding for the chaperone/usher (CU) pathway are widely distributed in many important environmental and pathogenic microbes; however, information about the regulatory machineries controlling CU gene expression during multicellular morphogenesis is missing. TheMyxococcus xanthusMcu system, encoded by themcuABCDgene cluster, represents a prototype of the archaic CU family that functions in spore coat formation. Using genome-wide transposon mutagenesis, we identified MXAN2872 to be a potential regulator of themcuABCoperon and demonstrated the necessity of MXAN2872 formcuABCexpression and fruiting body morphogenesis in early development.In silico, biochemical, and genetic analyses suggest that MXAN2872 encodes a Baeyer-Villiger monooxygenase (BVMO) of flavoproteins, and the potential cofactor-binding site as well as the BVMO fingerprint sequence is important for the regulatory role of the MXAN2872 protein. The expression profile ofmcuAin strains with an MXAN2872 deletion and point mutation agrees well with the timing of cell aggregation of these mutants. Furthermore, McuA could not be detected either in afruA-null mutant, where starvation-induced aggregation was completely blocked, or in the glycerol-induced spores, where sporulation was uncoupled from cell aggregation. In sum, the present work uncovers a positive role for MXAN2872, a metabolic enzyme-encoding gene, in controllingM. xanthusdevelopment. MXAN2872 functions by affecting the onset of cell aggregation, thereby leading to a secondary effect on the timing ofmcuABCexpression of this model organism.IMPORTANCEIdentification of the players that driveMyxococcus xanthusfruiting body formation is necessary for studying the mechanism of multicellular morphogenesis in this model organism. This study identifies MXAN2872, a gene encoding a putative flavin adenine dinucleotide-binding monooxygenase, to be a new interesting regulator regulating the timing of developmental aggregation. In addition, MXAN2872 seems to affect the expression of the chaperone/usher gene clustermcuin a manner that is aggregation dependent. Thus, in organisms characterized by a developmental cycle, expression of the chaperone/usher pathway can be controlled by morphological checkpoints, demonstrating another layer of complexity in the regulation of this conserved protein secretion pathway.
Diffusion of Antibiotics through the PilQ Secretin in Neisseria gonorrhoeae Occurs through the Immature, Sodium Dodecyl Sulfate-Labile Form
Authors: Nandi Sobhan , Swanson Shauna , Tomberg Joshua , Nicholas Robert A. 
Published: January 2015

ABSTRACT

In strains of
Neisseria gonorrhoeae
harboring the
mtr
and
penB
determinants that decrease permeation of antibiotics into the periplasm, mutation or deletion of the PilQ secretin of type IV pili increases resistance to penicillin by ∼3-fold, indicating a role for PilQ in antibiotic permeation. In this study, we examined spontaneously arising mutants with decreased susceptibility to penicillin. One class of mutants had a phenotype indistinguishable from that of a previously characterized
pilQ2
mutation that interfered with the formation of SDS-resistant PilQ multimers. A second class of mutants contained frameshift mutations in genes upstream of
pilQ
in the
pilMNOPQ
operon that increased resistance to levels similar to those of the
pilQ2
mutation. In-frame deletions of these genes were constructed, but only the frameshift mutations increased antibiotic resistance, suggesting that the mutations had polar effects on PilQ. Consistent with this result, titration of wild-type PilQ levels revealed a direct correlation between resistance and expression levels of PilQ. To determine which form of PilQ, the monomer or the multimer, was responsible for antibiotic permeation, we manipulated and quantified these forms in different mutants. Deletion of PilW, which is responsible for the maturation of PilQ into SDS-resistant multimers, had no effect on resistance. Moreover, Western blot analysis revealed that while SDS-resistant multimer levels were decreased by 26% in frameshift mutants, the levels of PilQ monomers were decreased by 48%. These data suggest that immature, SDS-labile complexes, not mature, SDS-resistant PilQ complexes, serve as the route of entry of antibiotics into the periplasm.

IMPORTANCE
The capacity of antibiotics to reach their target is crucial for their activity. In
Neisseria gonorrhoeae
, the PilQ secretin of type IV pili plays an important role in antibiotic influx when diffusion of antibiotics through porins is limited (e.g., in most resistant strains). On Western blots, PilQ exists both as a mature higher-order multimer and an immature, SDS-labile monomer. In this study, we examined spontaneously arising mutations in PilQ and in the genes upstream of PilQ in the
pilMNOPQ
operon that increase resistance to penicillin. We provide evidence that PilQ monomers associate by mass action to form immature multimers and that these complexes likely mediate the diffusion of antibiotics across the outer membrane.
Degradation Products of the Extracellular Pathogen Streptococcus pneumoniae Access the Cytosol via Its Pore-Forming Toxin
Authors: Lemon Jamie K. , Weiser Jeffrey N. 
Published: January 2015

ABSTRACT

Streptococcus pneumoniae
is a leading pathogen with an extracellular lifestyle; however, it is detected by cytosolic surveillance systems of macrophages. The innate immune response that follows cytosolic sensing of cell wall components results in recruitment of additional macrophages, which subsequently clear colonizing organisms from host airways. In this study, we monitored cytosolic access by following the transit of the abundant bacterial surface component capsular polysaccharide, which is linked to the cell wall. Confocal and electron microscopy visually characterized the location of cell wall components in murine macrophages outside membrane-bound organelles. Quantification of capsular polysaccharide through cellular fractionation demonstrated that cytosolic access of bacterial cell wall components is dependent on phagocytosis, bacterial sensitivity to the host’s degradative enzyme lysozyme, and release of the pore-forming toxin pneumolysin. Activation of p38 mitogen-activated protein kinase (MAPK) signaling is important for limiting access to the cytosol; however, ultimately, these are catastrophic events for both the bacteria and the macrophage, which undergoes cell death. Our results show how expression of a pore-forming toxin ensures the death of phagocytes that take up the organism, although cytosolic sensing results in innate immune detection that eventually allows for successful host defense. These findings provide an example of how cytosolic access applies to an extracellular microbe and contributes to its pathogenesis.

IMPORTANCE

Streptococcus pneumoniae
(the pneumococcus) is a bacterial pathogen that is a leading cause of pneumonia. Pneumococcal disease is preceded by colonization of the nasopharynx, which lasts several weeks before being cleared by the host’s immune system. Although S. pneumoniae is an extracellular microbe, intracellular detection of pneumococcal components is critical for bacterial clearance. In this study, we show that following bacterial uptake and degradation by phagocytes, pneumococcal products access the host cell cytosol via its pore-forming toxin. This phenomenon of cytosolic access results in phagocyte death and may serve to combat the host cells responsible for clearing the organism. Our results provide an example of how intracellular access and subsequent immune detection occurs during infection with an extracellular pathogen.
Malaria Induces Anemia through CD8+T Cell-Dependent Parasite Clearance and Erythrocyte Removal in the Spleen
Authors: Safeukui Innocent , Gomez Noé D. , Adelani Aanuoluwa A. , Burte Florence , Afolabi Nathaniel K. , Akondy Rama , Velazquez Peter , Holder Anthony , Tewari Rita , Buffet Pierre , Brown Biobele J. , Shokunbi Wuraola A. , Olaleye David , Sodeinde Olugbemiro , Kazura James , Ahmed Rafi , Mohandas Narla , Fernandez-Reyes Delmiro , Haldar Kasturi 
Published: January 2015

ABSTRACT Severe malarial anemia (SMA) in semi-immune individuals eliminates both infected and uninfected erythrocytes and is a frequent fatal complication. It is proportional not to circulating parasitemia but total parasite mass (sequestered) in the organs. Thus, immune responses that clear parasites in organs may trigger changes leading to anemia. Here, we use an outbred-rat model where increasing parasite removal in the spleen escalated uninfected-erythrocyte removal. Splenic parasite clearance was associated with activated CD8+T cells, immunodepletion of which prevented parasite clearance. CD8+T cell repletion and concomitant reduction of the parasite load was associated with exacerbated (40 to 60%) hemoglobin loss and changes in properties of uninfected erythrocytes. Together, these data suggest that CD8+T cell-dependent parasite clearance causes erythrocyte removal in the spleen and thus anemia. In children infected with the human malaria parasite Plasmodium falciparum, elevation of parasite biomass (not the number of circulating parasites) increased the odds ratio for SMA by 3.5-fold (95% confidence intervals [CI95%], 1.8- to 7.5-fold). CD8+T cell expansion/activation independently increased the odds ratio by 2.4-fold (CI95%, 1.0- to 5.7-fold). Concomitant increases in both conferred a 7-fold (CI95%, 1.9- to 27.4-fold)-greater risk for SMA. Together, these data suggest that CD8+-dependent parasite clearance may predispose individuals to uninfected-erythrocyte loss and SMA, thus informing severe disease diagnosis and strategies for vaccine development.IMPORTANCEMalaria is a major global health problem. Severe malaria anemia (SMA) is a complex disease associated with partial immunity. Rapid hemoglobin reductions of 20 to 50% are commonly observed and must be rescued by transfusion (which can carry a risk of HIV acquisition). The causes and risk factors of SMA remain poorly understood. Recent studies suggest that SMA is linked to parasite biomass sequestered in organs. This led us to investigate whether immune mechanisms that clear parasites in organs trigger anemia. In rats, erythropoiesis is largely restricted to the bone marrow, and critical aspects of the spleen expected to be important in anemia are similar to those in humans. Therefore, using a rat model, we show that severe anemia is caused through CD8+T cell-dependent parasite clearance and erythrocyte removal in the spleen. CD8 activation may also be a new risk factor for SMA in African children.
Tracheal intubation related complications in the prehospital setting
Authors: Caruana Emmanuel , Duchateau François-Xavier , Cornaglia Carole , Devaud Marie-Laure , Pirracchio Romain 
Published: January 2015

BackgroundPrehospital tracheal intubation (TI) is associated with morbidity and mortality, particularly in cases of difficult intubation. The goal of the present study was to describe factors associated with TI related complications in the prehospital setting.MethodsThis was a prospective cohort study including all patients intubated on scene in a prehospital emergency medical service over a 4 year period. TI related complications included oxygen desaturation, aspiration, vomiting, bronchospasm and/or laryngospasm, and mechanical complications (mainstem intubation, oesophageal intubation and airway lesion— that is, dental or laryngeal trauma caused by the laryngoscope). Difficult intubation was defined as >2 failed laryngoscopic attempts, or the need for any alternative TI method. A multivariate logistic regression was used to identify the risk factors for TI related complications.Results1251 patients were included; 208 complications occurred in 165 patients (13.1%). Among the 208 complications, the most frequent were oesophageal intubation (n=69, 29.7%), desaturation (n=58, 25.0%) and mainstem intubation (n=37, 15.9%). In multivariate analysis, difficult intubation (OR=6.13, 3.93 to 9.54), Cormack and Lehane grades 3 and 4 (OR=2.23, 1.26 to 3.96 for Cormack and Lehane grade 3 and OR=2.61, 1.28 to 5.33 for Cormack and Lehane grade 4 compared with Cormack and Lehane grade 1) and a body mass index >30 kg/m2(OR=2.22, 1.38 to 3.56) were significantly associated with TI related complications.ConclusionsDespite specific guidelines, TI related complications are more frequent in the prehospital setting when intubation is deemed difficult, the Cormack and Lehane grade is greater than grade 1 and the patient is overweight. In such situations, particular attention is needed to avoid complications.
Epidemiology of bicycle injuries and risk factors for serious injury
Authors: Rivara Frederick P , Thompson Diane C , Thompson Robert S 
Published: January 2015

ObjectiveTo determine the risk factors for serious injury to bicyclists, aside from helmet use.DesignProspective case-control study.SettingSeven Seattle area hospital emergency departments and two county medical examiner's offices.PatientsIndividuals treated in the emergency department or dying from bicycle related injuries.MeasurementsInformation collected from injured bicyclists or their parents by questionnaire on circumstances of the crash; abstract of medical records for injury data. Serious injury defined as an injury severity score>8.AnalysisOdd ratios computed using the maximum likelihood method, and adjusted using unconditional logistic regression.ResultsThere were 3854 injured cyclists in the three year period; 3390 (88%) completed questionnaires were returned. 51% wore helmets at the time of crash. Only 22.3% of patients had head injuries and 34% had facial injuries. Risk of serious injury was increased by collision with a motor vehicle (odds ratio (OR)=4.6), self reported speed >15 mph (OR=1.2), young age (<6 years), and age >39 years (OR=2.1 and 2.2 respectively, compared with adults 20-39 years). Risk for serious injury was not affected by helmet use (OR=0.9). Risk of neck injury was increased in those struck by motor vehicles (OR=4.0), hospitalized for any injury (OR=2.0), and those who died (OR=15.1), but neck injury was not affected by helmet use.ConclusionsPrevention of serious bicycle injuries cannot be accomplished through helmet use alone, and may require separation of cyclists from motor vehicles, and delaying cycling until children are developmentally ready.
Does research into contraceptive method discontinuation address women's own reasons? A critical review
Authors: Inoue Kumiyo , Barratt Alexandra , Richters Juliet 
Published: January 2015

ObjectiveTo examine the clinical and epidemiological literature addressing contraceptive method change or discontinuation and to assess whether the documented reasons reflected women's experiences.MethodsMajor databases including Medline and PsycINFO were searched using keywords related to contraception and discontinuation, adherence and satisfaction, for articles published between January 2003 and February 2013. Studies in developed countries that focused on women of reproductive age and reasons for method change or discontinuation were included. Reasons reported were categorised and examined.ResultsA total of 123 papers were reviewed in detail. Medical terminology was generally used to describe reasons for method discontinuation. The top two reported reasons were bleeding and pregnancy, but there was a lack of consensus about the categorisation of reasons. Broad categories that were not self-explanatory were included in more than half of the papers, often without further explanation. Only 12 studies expanded on categories containing ‘other’, ‘non-medical’ or ‘personal’ reasons. Eight papers included categories that attributed discontinuation to the participant, such as ‘dissatisfied with method’.ConclusionsStudies of reasons for discontinuation of contraceptives do not well describe women's specific reasons. Studies rely heavily on medical terms and often fail to document women's subjective experiences. Future studies should create an opportunity for women to articulate their non-medical reasons in their own words, including those related to their sexual lives. Furthermore, researchers should distinguish, if possible, between reasons for discontinuation of a method and reasons for ceasing participation in a research study.
A Phase IIa Randomized, Double-Blind Trial of Erlotinib in Inhibiting Epidermal Growth Factor Receptor Signaling in Aberrant Crypt Foci of the Colorectum
Authors: Gillen Daniel L. , Meyskens Frank L. , Morgan Timothy R. , Zell Jason A. , Carroll Robert , Benya Richard , Chen Wen-Pin , Mo Allen , Tucker Chris , Bhattacharya Asmita , Huang Zhiliang , Arcilla Myra , Wong Vanessa , Chung Jinah , Gonzalez Rachel , Rodriguez Luz Maria , Szabo Eva , Rosenberg Daniel W. , Lipkin Steven M. 
Published: January 2015

Abstract
Colorectal cancer progresses through multiple distinct stages that are potentially amenable to chemopreventative intervention. Epidermal growth factor receptor (EGFR) inhibitors are efficacious in advanced tumors including colorectal cancer. There is significant evidence that EGFR also plays important roles in colorectal cancer initiation, and that EGFR inhibitors block tumorigenesis. We performed a double-blind randomized clinical trial to test whether the EGFR inhibitor erlotinib given for up to 30 days had an acceptable safety and efficacy profile to reduce EGFR signaling biomarkers in colorectal aberrant crypt foci (ACF), a subset of which progress to colorectal cancer, and normal rectal tissue. A total of 45 patients were randomized to one of three erlotinib doses (25, 50, and 100 mg) with randomization stratified by nonsteroidal anti-inflammatory drug (NSAID) use. There were no unanticipated adverse events with erlotinib therapy. Erlotinib was detected in both normal rectal mucosa and ACFs. Colorectal ACF phosphorylated ERK (pERK), phosphorylated EGFR (pEGFR), and total EGFR signaling changes from baseline were modest and there was no dose response. Overall, this trial did not meet is primary efficacy endpoint. Colorectal EGFR signaling inhibition by erlotinib is therefore likely insufficient to merit further studies without additional prescreening stratification or potentially longer duration of use. Cancer Prev Res; 8(3); 222–30. ©2015 AACR.