bluuebunny/crossref_metadata_2025 huggingface dataset:
Emergency pediatric anesthesia – accessibility of information
Authors: King Hannah , Pipe Georgina E.M. , Linford Sarah L. , Moppett Iain K. , Armstrong James A.M.
Published: October 2014

Background

Emergency pediatric situations are stressful for all involved. Variation in weight, physiology, and anatomy can be substantial and errors in calculating drugs and fluids can be catastrophic.

Objectives

To evaluate the reliability of information resources that anesthetic trainees might use when faced with common pediatric emergencies.

Methods

Anesthetic trainees from a single UK deanery were recruited and timed while they identified 18 predetermined pieces of information from three Advanced Pediatric Life Support (APLS) scenarios. The two most popular smartphone applications identified from a previous survey, PaedsED (PaedsED. iED limited, Version 1.0.8, Updated March 2011. ©2009) and Anapaed (AnaPaed. Thierry Girard, Version 1.4.2, Updated Nov 2, 2012. ©Thierry Girard), the British National Formulary for Children (cBNF) and trainee's inherent knowledge were compared with a local, check‐list style, handbook of pediatric emergency algorithms – Pediatric Anesthetic Emergency Data sheets (PAEDs).

Results

Twenty anesthetic trainees were recruited. The fastest source of information was the trainees own knowledge (median 61 s, IQR 51–83 s). Second fastest was PAEDs (80, [59–110] s), followed by PaedsED (84, [65–111]). The most accurate source overall was PaedsED (100, [83–100]) although the accuracy varied between scenarios. The handbook was rated as the most popular resource by the trainees.

Conclusion

Although fastest, trainees own knowledge is inaccurate, highlighting the need for additional, rapidly accessible, information. Of the two smartphone applications, PaedsED proved to be fast, accurate, and more popular, while Anapaed was accurate but slow to use. The PAEDs handbook, with its checklist‐style format, was also fast, accurate and rated the most popular information source.
Genetic dissection of seed vigour under artificial ageing conditions using two joined maize recombinant inbred line populations
Authors: Ku Lixia , Cui Xinjian , Cheng Fangfang , Guo Shulei , Qi Jianshuang , Tian Zhiqiang , Han Tuo , Ren Zhenzhen , Zhang Liangkun , Su Huihui , Chen Yanhui
Published: October 2014

Seed vigour plays an important role in agricultural production, and seeds with high sowing quality are necessary for improving agriculture production. In our study, two connected maize recombinant inbred line (RIL) populations derived from Yu82 × Shen137 and Yu537A × Shen137 crosses were evaluated for the mean germination time (MGT) and other related traits under three artificial ageing treatments. We used meta‐analysis to integrate genetic maps and identify quantitative trait loci (QTLs) across the two populations. In total, 74 QTLs and 20 meta‐QTLs (mQTLs) were identified. Four key mQTLs, mQTL2‐2, mQTL5‐4, mQTL6 and mQTL8, which contained initial QTLs with R2 values >10% and included 5–9 initial QTLs, may be hot spots of important QTLs for the associated traits. Twenty‐two key candidate genes associated with four seed vigour‐related traits mapped to 14 mQTLs. In particular, the GRMZM2G163749, GRMZM2G122172/GRMZM2G554885/GRMZM2G122871 and GRMZM2G150367 genes mapped within the important mQTL5–4, mQTL6 and mQTL8 regions, respectively. Fine mapping for the genetic regions of these three mQTLs merits further study and could be utilized for marker‐assisted breeding.
Effects of freeze–thaw on aggregate stability and the organic carbon and nitrogen enrichment ratios in aggregate fractions
Authors: Chai Y. J. , Zeng X. B. , E S. Z. , Bai L. Y. , Su S. M. , Huang T.
Published: October 2014

Soil samples from the Hexi Corridor located in the arid regions of Northwestern China were collected from a site that had received fertilizer applications for 23 years. Effects of freeze–thaw on aggregate stability and the organic carbon (OC) and nitrogen (N) enrichment ratios in water stable aggregate (WSA) fractions were investigated. In treatments combining the application of N fertilizer with green manure (GN) or straw (SN), the percentage of >0.25 mm WSA fraction was not significantly different from the control soil that received no fertilizer or organic amendment. After a freeze–thaw cycle, the percentages of the >0.25 mm WSA fraction in the GN and SN treatments showed no change, but the size of this fraction in the other treatments decreased. In addition, the organic carbon (OC) and N enrichment ratios in the >0.25 mm WSA fraction in GN and SN treatments increased after a freeze–thaw cycle. However, in this size fraction, the OC and N enrichment ratios decreased in other treatments. Both the changes of the percentages of the >0.25 mm WSA fraction and the OC and N enrichment ratios in this fraction under freeze–thaw in the GN and SN treatments exhibited the most significant increases compared with other treatments (P < 0.05). The results indicated that the GN and SN treatments could prevent the damaging effects of freeze–thaw on aggregate stability and protect soil from erosion.
Herbivore‐induced poplar cytochrome P450 enzymes of the CYP71 family convert aldoximes to nitriles which repel a generalist caterpillar
Authors: Irmisch Sandra , Clavijo McCormick Andrea , Günther Jan , Schmidt Axel , Boeckler Gerhard Andreas , Gershenzon Jonathan , Unsicker Sybille B. , Köllner Tobias G.
Published: October 2014

Numerous plant species emit volatile nitriles upon herbivory, but the biosynthesis as well as the relevance of these nitrogenous compounds in plant–insect interactions remains unknown. Populus trichocarpa has been shown to produce a complex blend of nitrogenous volatiles, including aldoximes and nitriles, after herbivore attack. The aldoximes were previously reported to be derived from amino acids by the action of cytochrome P450 enzymes of the CYP79 family. Here we show that nitriles are derived from aldoximes by another type of P450 enzyme in P. trichocarpa. First, feeding of deuterium‐labeled phenylacetaldoxime to poplar leaves resulted in incorporation of the label into benzyl cyanide, demonstrating that poplar volatile nitriles are derived from aldoximes. Then two P450 enzymes, CYP71B40v3 and CYP71B41v2, were characterized that produce aliphatic and aromatic nitriles from their respective aldoxime precursors. Both possess typical P450 sequence motifs but do not require added NADPH or cytochrome P450 reductase for catalysis. Since both enzymes are expressed after feeding by gypsy moth caterpillars, they are likely to be involved in herbivore‐induced volatile nitrile emission in P. trichocarpa. Olfactometer experiments showed that these volatile nitriles have a strong repellent activity against gypsy moth caterpillars, suggesting they play a role in induced direct defense against poplar herbivores.
Lipidomic and proteomic characterization of platelet extracellular vesicle subfractions from senescent platelets
Authors: Pienimaeki‐Roemer Annika , Kuhlmann Katja , Böttcher Alfred , Konovalova Tatiana , Black Anne , Orsó Evelyn , Liebisch Gerhard , Ahrens Maike , Eisenacher Martin , Meyer Helmut E. , Schmitz Gerd
Published: October 2014

Background

Platelets (PLTs) in stored PLT concentrates (PLCs) release PLT extracellular vesicles (PL‐EVs) induced by senescence and activation, resembling the PLT storage lesion. No comprehensive classification or molecular characterization of senescence‐induced PL‐EVs exists to understand PL‐EV heterogeneity.

Study Design and Methods

PL‐EVs from 5‐day‐stored PLCs from healthy individuals were isolated and subfractionated by differential centrifugation, filtration, and density gradient ultracentrifugation into five PLT microvesicle (PL‐MV) subfractions (Fraction [F]1‐F5) and PLT exosomes (PL‐EXs). PL‐EV size, concentration, and composition were analyzed by nanoparticle tracking analysis, flow cytometry, and lipid and protein mass spectrometry. Protein data were verified by Western blot.

Results

PL‐EVs showed overlapping mean particle sizes of 180 to 260 nm, but differed significantly in composition. Less dense, intermediate, and dense PL‐MVs enriched specific lipidomic and proteomic markers related to the plasma membrane, intracellular membranes, PLT granules, mitochondria, and PLT activation. α‐Synuclein (81% of total) accumulated in F1 and F2, amyloid‐β (Aβ) precursor protein in F3 and F4 (84%), and apolipoprotein (Apo)E (88%) and ApoJ (92%) in F3 to F5. PL‐EXs enriched lipid species and proteins, with high abundance of lipid raft, PLT adhesion, and immune response–related markers.

Conclusion

Differential lipid and protein compositions of PL‐EVs suggest their unique cellular origins and functions, partly overlapping with PLT granule secretion. Dense PL‐MVs might represent autophagic vesicles released during PLT activation and apoptosis and PL‐EXs resemble lipid rafts, with a potential role in PLT aggregation and immunity. Segregation of α‐synuclein and Aβ precursor protein, ApoE, and ApoJ into less dense and dense PL‐MVs, respectively, show their differential carrier role of neurologic disease–related cargo.
The evaluation of a new apheresis device for automated red blood cell exchange procedures in patients with sickle cell disease
Authors: Quirolo Keith , Bertolone Salvatore , Hassell Kathryn , Howard Thomas , King Karen E. , Rhodes Diane K. , Bill Jerry
Published: October 2014

Background

The Spectra Optia apheresis system (SO), a blood component separator, can be used to perform red blood cell exchange (RBCX) procedures for the transfusion management of sickle cell disease (SCD) in adults and children. This study was designed to evaluate the performance of the SO RBCX protocols (exchange and depletion/exchange) in patients with SCD.

Study Design and Methods

Patients with SCD and a need for an RBCX procedure as part of a chronic program or as a single procedure were enrolled in this multicenter, single‐arm, open‐label study. The primary goal of the study was to confirm that the predicted percentage of the patient's original RBCs remaining at the end of the procedure (FCRp) reflects the actual cell fraction remaining, as measured by %HbS (FCRa). Secondary endpoints included ability of the SO to achieve the desired final hematocrit (Hct) and device‐related serious adverse events (SAEs).

Results

Seventy‐two patients 12 years of age or older were enrolled in the study; 60 were evaluable. The ratio of FCRa to FCRp after the RBCX procedure was 0.90, well within the prespecified range of 0.75 to 1.25. The SO was able to achieve the desired final Hct in the evaluable population. The safety profile was favorable, and no patients had an SAE or unexpected adverse device effect or withdrew from the procedure or treatment due to an adverse event.

Conclusion

The SO performed effectively and safely for both the RBCX procedure and the RBCX depletion/exchange procedure.
Why Are Agricultural Goods Not Traded More Intensively: High Trade Costs or Low Productivity Variation?
Authors: Xu Kai
Published: October 2014

This paper empirically studies the sizes of agricultural trade costs and productivity variation in the agriculture sector. In a general Ricardian trade model, I identify these two factors as possible causes of the observed low trade intensity of agricultural goods. Using data on bilateral trade flows, prices of agricultural goods and sectoral production from a sample of 46 countries, I estimate the variation of agricultural productivity as well as trade costs on agricultural and manufactured goods. I find that trade costs are substantial, with agricultural trade costs roughly twice as large as manufacturing trade costs. Moreover, consistent with the existing literature, I find that distance is the dominant part in the estimated trade costs. Lastly, relative to existing estimates of the heterogeneity of manufacturing productivity, the heterogeneity of agricultural productivity is large. These findings suggest that high trade costs are the main impediments to agricultural trade.
Amotosalen‐HCl‐UVA pathogen reduction does not alter poststorage metabolism of soluble CD40 ligand, Ox40 ligand and interkeukin‐27, the cytokines that generally associate with serious adverse events
Authors: Hamzeh‐Cognasse H. , Laradi S. , Osselaer J. C. , Cognasse F. , Garraud O.
Published: October 2014

Platelets in therapeutic platelet concentrates are commonly acknowledged to release biologically active constituents during storage. This study examined the influence of photochemical pathogen reduction treatment (PRT) using amotosalen‐HCl and UVA light vs. untreated control platelet components, on three factors recently reported to be associated with serious adverse events associated with platelet component (PC) transfusions: sCD40L, IL‐27 and sOX40 ligand. Levels of such cytokine‐like factors increased significantly during storage, but no significant difference was detected between PRT‐ and control PCs. This suggests that occurrences of AEs are not directly influenced by PRT but rather may depend on alternate determinants.
Effects of some chemical factors, prechilling treatments and interactions on the seed dormancy‐breaking of two Papaver species
Authors: Golmohammadzadeh Sajedeh , Zaefarian Faezeh , Rezvani Mohammad
Published: October 2014

Seed dormancy is a common strategy of many plants to survive in natural and agricultural ecosystems. This study examined the effects of some chemical factors, including gibberellic acid and potassium nitrate, the prechilling temperature, duration and conditions and the light regimes on the seed dormancy‐breaking of Papaver rhoeas L. and Papaver dubium L. The results showed that all the tested seed dormancy‐breaking treatments significantly stimulated the germination of the two Papaver species. The seed germination was significantly influenced in relation to the seeds that were treated with 0–1250 p.p.m. of gibberellic acid. The maximum germination was observed in P. rhoeas L. at 750 p.p.m. and in Pa. dubium L. at 500 p.p.m. in the light/dark regime. There was a significant increase in the germination with an increase in the potassium nitrate concentration. The greatest germination was achieved at the lowest potassium nitrate concentration (0.5 g L−1) in the light/dark regime. The wet prechilling was more effective than the dry prechilling in the dormancy‐breaking of both P. rhoeas L. and Pa. dubium L. The highest germination percentage was found in the wet prechilling condition after 45 days' prechilling duration. The combination of gibberellic acid and potassium nitrate was more successful than their separate application in the stimulation of germination in both Papaver species. Among the combined treatments of prechilling and gibberellic acid, the highest germination of P. rhoeas L. was recorded in the seeds that were treated with wet prechilling for 45 days with 750 p.p.m. gibberellic acid, while in Pa. dubium L., the maximum germination was recorded with wet prechilling for 45 days with 500 p.p.m. of gibberellic acid.
Plasma dynamics in a discharge produced by a pulsed dual frequency inductively coupled plasma source
Authors: Mishra Anurag , Lee Sehan , Yeom Geun Y.
Published: October 2014

Using a Langmuir probe, time resolved measurements of plasma parameters were carried out in a discharge produced by a pulsed dual frequency inductively coupled plasma source. The discharge was sustained in an argon gas environment at a pressure of 10 mTorr. The low frequency (P2 MHz) was pulsed at 1 kHz and a duty ratio of 50%, while high frequency (P13.56 MHz) was maintained in the CW mode. All measurements were carried out at the center of the discharge and 20 mm above the substrate. The results show that, at a particular condition (P2 MHz = 200 W and P13.56 MHz = 600 W), plasma density increases with time and stabilizes at up to ∼200 μs after the initiation of P2 MHz pulse at a plasma density of (2 × 1017 m−3) for the remaining duration of pulse “on.” This stabilization time for plasma density increases with increasing P2 MHz and becomes ∼300 μs when P2 MHz is 600 W; however, the growth rate of plasma density is almost independent of P2 MHz. Interestingly, the plasma density sharply increases as the pulse is switched off and reaches a peak value in ∼10 μs, then decreases for the remaining pulse “off-time.” This phenomenon is thought to be due to the sheath modulation during the transition from “pulse on” to “pulse off” and partly due to RF noise during the transition period. The magnitude of peak plasma density in off time increases with increasing P2 MHz. The plasma potential and electron temperature decrease as the pulse develops and shows similar behavior to that of the plasma density when the pulse is switched off.
Enhanced photoresponse of conformal TiO2/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing angle and atomic layer deposition
Authors: Haider Ali , Cansizoglu Hilal , Cansizoglu Mehmet Fatih , Karabacak Tansel , Okyay Ali Kemal , Biyikli Necmi
Published: October 2014

In this study, the authors demonstrate a proof of concept nanostructured photodiode fabrication method via successive glancing angle deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse compared to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO2) was deposited conformally on Ag NRs via ALD. Scanning electron microscopy studies confirmed the successful formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO2 on Ag NRs via ALD. Following the growth of TiO2 on Ag NRs, aluminum metallic top contacts were formed to complete the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a photo response enhancement factor of 1.49 × 102 under a reverse bias of 3 V.
Three-dimensional numerical investigations of air bubble defects during antireflective pattern fabrication via ultraviolet nanoimprint lithography
Authors: Yoo David , Seok Jeong-Min , Kim Nam Woong
Published: October 2014

This study uses three-dimensional computational fluid dynamics analysis to investigate air bubble formation during the cavity-filling process of ultraviolet nanoimprint lithography. The three distinct antireflective patterns of pyramid-, cone-, and modified cone-shaped patterns are considered, and a parametric study is performed to analyze the effects upon air bubble formation that come by varying the pattern period (p), height (hp), and the resist thickness (ThR). Based on the simulation results, matching equations in terms of hp/ThR versus ThR/p are obtained by curve fitting for the air bubble formation. The obtained equations themselves can be very useful to avoid air bubble defects, especially when the pattern geometries are fixed, because the resist thickness can be controlled. Using the obtained equations, changes in the values of p and hp are investigated with regard to their effects upon the conditions for maximum antireflectivity and for reliability of being free from air bubble defects. It is found that small p and large hp values make it increasingly difficult to choose appropriate values of p, hp, and ThR, wherein both of the antireflectivity and air bubble-free conditions are met. The cone pattern is found to be the least suitable, whereas the most suitable pattern satisfying both conditions is the pyramid pattern.
Compartment modeling of dynamic brain PET—The impact of scatter corrections on parameter errors
Authors: Häggström Ida , Schmidtlein C. Ross , Karlsson Mikael , Larsson Anne
Published: October 2014

Purpose:

The aim of this study was to investigate the effect of scatter and its correction on kinetic parameters in dynamic brain positron emission tomography (PET) tumor imaging. The 2‐tissue compartment model was used, and two different reconstruction methods and two scatter correction (SC) schemes were investigated.

Methods:

The gate Monte Carlo (MC) software was used to perform 2 × 15 full PET scan simulations of a voxelized head phantom with inserted tumor regions. The two sets of kinetic parameters of all tissues were chosen to represent the 2‐tissue compartment model for the tracer 3′‐deoxy‐3′‐(18F)fluorothymidine (FLT), and were denoted FLT1 and FLT2. PET data were reconstructed with both 3D filtered back‐projection with reprojection (3DRP) and 3D ordered‐subset expectation maximization (OSEM). Images including true coincidences with attenuation correction (AC) and true+scattered coincidences with AC and with and without one of two applied SC schemes were reconstructed. Kinetic parameters were estimated by weighted nonlinear least squares fitting of image derived time–activity curves. Calculated parameters were compared to the true input to the MC simulations.

Results:

The relative parameter biases for scatter‐eliminated data were 15%, 16%, 4%, 30%, 9%, and 7% (FLT1) and 13%, 6%, 1%, 46%, 12%, and 8% (FLT2) for K1, k2, k3, k4, Va, and Ki, respectively. As expected, SC was essential for most parameters since omitting it increased biases by 10 percentage points on average. SC was not found necessary for the estimation of Ki and k3, however. There was no significant difference in parameter biases between the two investigated SC schemes or from parameter biases from scatter‐eliminated PET data. Furthermore, neither 3DRP nor OSEM yielded the smallest parameter biases consistently although there was a slight favor for 3DRP which produced less biased k3 and Ki estimates while OSEM resulted in a less biased Va. The uncertainty in OSEM parameters was about 26% (FLT1) and 12% (FLT2) larger than for 3DRP although identical postfilters were applied.

Conclusions:

SC was important for good parameter estimations. Both investigated SC schemes performed equally well on average and properly corrected for the scattered radiation, without introducing further bias. Furthermore, 3DRP was slightly favorable over OSEM in terms of kinetic parameter biases and SDs.
RhoA signaling in cardiomyocytes protects against stress-induced heart failure but facilitates cardiac fibrosis
Authors: Lauriol Jessica , Keith Kimberly , Jaffré Fabrice , Couvillon Anthony , Saci Abdel , Goonasekera Sanjeewa A. , McCarthy Jason R. , Kessinger Chase W. , Wang Jianxun , Ke Qingen , Kang Peter M. , Molkentin Jeffery D. , Carpenter Christopher , Kontaridis Maria I.
Published: October 2014

Mice lacking the GTPase RhoA in cardiomyocytes develop greater pathological hypertrophy but reduced fibrosis with chronic stress to the heart.
Notch activity in neural progenitors coordinates cytokinesis and asymmetric differentiation
Authors: Pinto-Teixeira Filipe , Desplan Claude
Published: October 2014

Notch signaling acts early to promote asymmetric cell division in
Drosophila
neural precursor cells.
T
regs
Muscle In on the Action
Authors: Smith Orla
Published: October 2014

Regulatory T cells ameliorate symptoms of muscular dystrophy by suppressing type 1 inflammatory responses in muscle.
Finding the Targets of T Cells Gone Bad
Authors: Mueller Kristen L.
Published: October 2014

In a mouse model of rheumatoid arthritis, autoimmune T cells recognize a protein from the ribosome.
Atovaquone Tolerance in Plasmodium falciparum Parasites Selected for High-Level Resistance to a Dihydroorotate Dehydrogenase Inhibitor
Authors: Guler Jennifer L. , White John , Phillips Margaret A. , Rathod Pradipsinh K.
Published: October 2014

Atovaquone is a component of Malarone, a widely prescribed antimalarial combination, that targets malaria respiration. Here we show that parasites with high-level resistance to an inhibitor of dihydroorotate dehydrogenase demonstrate unexpected atovaquone tolerance. Fortunately, the tolerance is diminished with proguanil, the second partner in Malarone. It is important to understand such “genetic cross talk” between respiration and pyrimidine biosynthesis since many antimalarial drug development programs target these two seemingly independent pathways.
Nonclinical and Pharmacokinetic Assessments To Evaluate the Potential of Tedizolid and Linezolid To Affect Mitochondrial Function
Authors: Flanagan Shawn , McKee Edward E. , Das Debaditya , Tulkens Paul M. , Hosako Hiromi , Fiedler-Kelly Jill , Passarell Julie , Radovsky Ann , Prokocimer Philippe
Published: October 2014

Prolonged treatment with the oxazolidinone linezolid is associated with myelosuppression, lactic acidosis, and neuropathies, toxicities likely caused by impairment of mitochondrial protein synthesis (MPS). To evaluate the potential of the novel oxazolidinone tedizolid to cause similar side effects, nonclinical and pharmacokinetic assessments were conducted. In isolated rat heart mitochondria, tedizolid inhibited MPS more potently than did linezolid (average [± standard error of the mean] 50% inhibitory concentration [IC
50
] for MPS of 0.31 ± 0.02 μM versus 6.4 ± 1.2 μM). However, a rigorous 9-month rat study comparing placebo and high-dose tedizolid (resulting in steady-state area under the plasma concentration-time curve values about 8-fold greater than those with the standard therapeutic dose in humans) showed no evidence of neuropathy. Additional studies explored why prolonged, high-dose tedizolid did not cause these mitochondriopathic side effects despite potent MPS inhibition by tedizolid. Murine macrophage (J774) cell fractionation studies found no evidence of a stable association of tedizolid with eukaryotic mitochondria. Monte Carlo simulations based on population pharmacokinetic models showed that over the course of a dosing interval using standard therapeutic doses, free plasma concentrations fell below the respective MPS IC
50
in 84% of tedizolid-treated patients (for a median duration of 7.94 h) and 38% of linezolid-treated patients (for a median duration of 0 h). Therapeutic doses of tedizolid, but not linezolid, may therefore allow for mitochondrial recovery during antibacterial therapy. The overall results suggest that tedizolid has less potential to cause myelosuppression and neuropathy than that of linezolid during prolonged treatment courses. This, however, remains a hypothesis that must be confirmed in clinical studies.
In Vitro
and
In Vivo
Activities of the Nitroimidazole TBA-354 against Mycobacterium tuberculosis
Authors: Upton A. M. , Cho S. , Yang T. J. , Kim Y. , Wang Y. , Lu Y. , Wang B. , Xu J. , Mdluli K. , Ma Z. , Franzblau S. G.
Published: October 2014

Nitroimidazoles are a promising new class of antitubercular agents. The nitroimidazo-oxazole delamanid (OPC-67683, Deltyba) is in phase III trials for the treatment of multidrug-resistant tuberculosis, while the nitroimidazo-oxazine PA-824 is entering phase III for drug-sensitive and drug-resistant tuberculosis. TBA-354 (SN31354[(
S
)-2-nitro-6-((6-(4-trifluoromethoxy)phenyl)pyridine-3-yl)methoxy)-6,7-dihydro-5
H
-imidazo[2,1-
b
][1,3]oxazine]) is a pyridine-containing biaryl compound with exceptional efficacy against chronic murine tuberculosis and favorable bioavailability in preliminary rodent studies. It was selected as a potential next-generation antituberculosis nitroimidazole following an extensive medicinal chemistry effort. Here, we further evaluate the pharmacokinetic properties and activity of TBA-354 against
Mycobacterium tuberculosis
. TBA-354 is narrow spectrum and bactericidal
in vitro
against replicating and nonreplicating
Mycobacterium tuberculosis
, with potency similar to that of delamanid and greater than that of PA-824. The addition of serum protein or albumin does not significantly alter this activity. TBA-354 maintains activity against
Mycobacterium tuberculosis
H37Rv isogenic monoresistant strains and clinical drug-sensitive and drug-resistant isolates. Spontaneous resistant mutants appear at a frequency of 3 × 10
−7
.
In vitro
studies and
in vivo
studies in mice confirm that TBA-354 has high bioavailability and a long elimination half-life.
In vitro
studies suggest a low risk of drug-drug interactions. Low-dose aerosol infection models of acute and chronic murine tuberculosis reveal time- and dose-dependent
in vivo
bactericidal activity that is at least as potent as that of delamanid and more potent than that of PA-824. Its superior potency and pharmacokinetic profile that predicts suitability for once-daily oral dosing suggest that TBA-354 be studied further for its potential as a next-generation nitroimidazole.
Verapamil Increases the Bactericidal Activity of Bedaquiline against Mycobacterium tuberculosis in a Mouse Model
Authors: Gupta Shashank , Tyagi Sandeep , Bishai William R.
Published: October 2014

Bedaquiline is a newly approved drug for the treatment of multidrug-resistant tuberculosis, but there are concerns about its safety in humans. We found that the coadministration of verapamil with subinhibitory doses of bedaquiline gave the same bactericidal effect in mice as did the full human bioequivalent bedaquiline dosing. Adding verapamil to bedaquiline monotherapy also protected against the development of resistant mutants
in vivo
. The adjunctive use of verapamil may permit use of lower doses of bedaquiline to be used and thereby reduce its dose-related toxicities in tuberculosis patients.
Activity Spectrum of Colicins Produced by Shigella sonnei and Genetic Mechanism of Colicin Resistance in Conspecific S. sonnei Strains and Escherichia coli
Authors: Calcuttawala Fatema , Hariharan Chellaram , Pazhani Gururaja P. , Ghosh Santanu , Ramamurthy Thandavarayan
Published: October 2014

Colicin-mediated killing is an example of allelopathy, which has been found among several bacteria. Screening of 42 strains of
Shigella sonnei
isolated from diarrheal patients revealed that 39 (93%)
S. sonnei
strains were positive for colicin production against
Escherichia coli
DH5α. In the PCR-based detection of the colicin types, 36 (92.3%) were identified as E3, 2 (5.1%) as E3 and E8, and 1 (2.6%) as E3 and E2. Representative
S. sonnei
strains producing heterologous colicins exhibited antagonism against diarrheagenic
Escherichia coli
(DEC) groups. Although it is known that mutation in the colicin receptor renders the host resistant to colicin, there is a dearth of information on the genetic characterization of such mutants. In the fluctuation test, colicin-resistant
E. coli
mutants were found to occur spontaneously at the rates of 2.51 × 10
−8
and 5.52 × 10
−8
per generation when exposed to colicins E3 and E8 and colicins E3 and E2, respectively. Genotypic characterization of colicin-resistant
E. coli
(EC
Cr
) and
S. sonnei
(SS
Cr
) strains displayed mutations in the
btuB
gene, which encodes the receptor for vitamin B
12
uptake. This gene was interrupted by various insertion sequences, such as IS
1
, IS
2
, and IS
911
. Complementation of EC
Cr
and SS
Cr
with plasmid-borne
btuB
(p
btuB
) accomplished restoration of the colicin-susceptible phenotype. The vitamin B
12
uptake assay gave an insight into the physiological relevance of the
btuB
mutation. Our studies provide insights into the latent influence of
S. sonnei
colicins in governing the existence of some of the shigellae and all of the DEC and the genetic mechanism underlying the emergence of resistance.
Surface Glycosaminoglycans Protect Eukaryotic Cells against Membrane-Driven Peptide Bacteriocins
Authors: Martín Rebeca , Escobedo Susana , Martín Carla , Crespo Ainara , Quiros Luis M. , Suarez Juan E.
Published: October 2014

Enzymatic elimination of surface glycosaminoglycans or inhibition of their sulfation provokes sensitizing of HT-29 and HeLa cells toward the peptide bacteriocins nisin A, plantaricin C, and pediocin PA-1/AcH. The effect can be partially reversed by heparin, which also lowers the susceptibility of
Lactococcus lactis
to nisin A. These data indicate that the negative charge of the glycosaminoglycan sulfate residues binds the positively charged bacteriocins, thus protecting eukaryotic cells from plasma membrane damage.
Accumulation-Associated Protein Enhances Staphylococcus epidermidis Biofilm Formation under Dynamic Conditions and Is Required for Infection in a Rat Catheter Model
Authors: Schaeffer Carolyn R. , Woods Keith M. , Longo G. Matt , Kiedrowski Megan R. , Paharik Alexandra E. , Büttner Henning , Christner Martin , Boissy Robert J. , Horswill Alexander R. , Rohde Holger , Fey Paul D.
Published: October 2014

Biofilm formation is the primary virulence factor of
Staphylococcus epidermidis
.
S. epidermidis
biofilms preferentially form on abiotic surfaces and may contain multiple matrix components, including proteins such as accumulation-associated protein (Aap). Following proteolytic cleavage of the A domain, which has been shown to enhance binding to host cells, B domain homotypic interactions support cell accumulation and biofilm formation. To further define the contribution of Aap to biofilm formation and infection, we constructed an
aap
allelic replacement mutant and an
icaADBC aap
double mutant. When subjected to fluid shear, strains deficient in Aap production produced significantly less biofilm than Aap-positive strains. To examine the
in vivo
relevance of our findings, we modified our previously described rat jugular catheter model and validated the importance of immunosuppression and the presence of a foreign body to the establishment of infection. The use of our allelic replacement mutants in the model revealed a significant decrease in bacterial recovery from the catheter and the blood in the absence of Aap, regardless of the production of polysaccharide intercellular adhesin (PIA), a well-characterized, robust matrix molecule. Complementation of the
aap
mutant with full-length Aap (containing the A domain), but not the B domain alone, increased initial attachment to microtiter plates, as did in
trans
expression of the A domain in adhesion-deficient
Staphylococcus carnosus
. These results demonstrate Aap contributes to
S. epidermidis
infection, which may in part be due to A domain-mediated attachment to abiotic surfaces.
A Bivalent Typhoid Live Vector Vaccine Expressing both Chromosome- and Plasmid-Encoded Yersinia pestis Antigens Fully Protects against Murine Lethal Pulmonary Plague Infection
Authors: Galen James E. , Wang Jin Yuan , Carrasco Jose A. , Lloyd Scott A. , Mellado-Sanchez Gabriela , Diaz-McNair Jovita , Franco Olga , Buskirk Amanda D. , Nataro James P. , Pasetti Marcela F.
Published: October 2014

Live attenuated bacteria hold great promise as multivalent mucosal vaccines against a variety of pathogens. A major challenge of this approach has been the successful delivery of sufficient amounts of vaccine antigens to adequately prime the immune system without overattenuating the live vaccine. Here we used a live attenuatedSalmonella entericaserovar Typhi strain to create a bivalent mucosal plague vaccine that produces both the protective F1 capsular antigen ofYersinia pestisand the LcrV protein required for secretion of virulence effector proteins. To reduce the metabolic burden associated with the coexpression of F1 and LcrV within the live vector, we balanced expression of both antigens by combining plasmid-based expression of F1 with chromosomal expression of LcrV from three independent loci. The immunogenicity and protective efficacy of this novel vaccine were assessed in mice by using a heterologous prime-boost immunization strategy and compared to those of a conventional strain in which F1 and LcrV were expressed from a single low-copy-number plasmid. The serum antibody responses to lipopolysaccharide (LPS) induced by the optimized bivalent vaccine were indistinguishable from those elicited by the parent strain, suggesting an adequate immunogenic capacity maintained through preservation of bacterial fitness; in contrast, LPS titers were 10-fold lower in mice immunized with the conventional vaccine strain. Importantly, mice receiving the optimized bivalent vaccine were fully protected against lethal pulmonary challenge. These results demonstrate the feasibility of distributing foreign antigen expression across both chromosomal and plasmid locations within a single vaccine organism for induction of protective immunity.
CFP-10 from Mycobacterium tuberculosis Selectively Activates Human Neutrophils through a Pertussis Toxin-Sensitive Chemotactic Receptor
Authors: Welin Amanda , Björnsdottir Halla , Winther Malene , Christenson Karin , Oprea Tudor , Karlsson Anna , Forsman Huamei , Dahlgren Claes , Bylund Johan
Published: October 2014

Upon infection with
Mycobacterium tuberculosis
, neutrophils are massively recruited to the lungs, but the role of these cells in combating the infection is poorly understood. Through a type VII secretion system,
M. tuberculosis
releases a heterodimeric protein complex, containing a 6-kDa early secreted antigenic target (ESAT-6) and a 10-kDa culture filtrate protein (CFP-10), that is essential for virulence. Whereas the ESAT-6 component possesses multiple virulence-related activities, no direct biological activity of CFP-10 has been shown, and CFP-10 has been described as a chaperone protein for ESAT-6. We here show that the ESAT-6:CFP-10 complex induces a transient release of Ca
2+
from intracellular stores in human neutrophils. Surprisingly, CFP-10 rather than ESAT-6 was responsible for triggering the Ca
2+
response, in a pertussis toxin-sensitive manner, suggesting the involvement of a G-protein-coupled receptor. In line with this, the response was accompanied by neutrophil chemotaxis and activation of the superoxide-producing NADPH-oxidase. Neutrophils were unique among leukocytes in responding to CFP-10, as monocytes and lymphocytes failed to produce a Ca
2+
signal upon stimulation with the
M. tuberculosis
protein. Hence, CFP-10 may contribute specifically to neutrophil recruitment and activation during
M. tuberculosis
infection, representing a novel biological role for CFP-10 in the ESAT-6:CFP-10 complex, beyond the previously described chaperone function.
Macrophage-Inducible C-Type Lectin Mincle-Expressing Dendritic Cells Contribute to Control of Splenic Mycobacterium bovis BCG Infection in Mice
Authors: Behler Friederike , Maus Regina , Bohling Jennifer , Knippenberg Sarah , Kirchhof Gabriele , Nagata Masahiro , Jonigk Danny , Izykowski Nicole , Mägel Lavinia , Welte Tobias , Yamasaki Sho , Maus Ulrich A.
Published: October 2014

The macrophage-inducible C-type lectin Mincle has recently been identified to be a pattern recognition receptor sensing mycobacterial infection via recognition of the mycobacterial cell wall component trehalose-6′,6-dimycolate (TDM). However, its role in systemic mycobacterial infections has not been examined so far. Mincle-knockout (KO) mice were infected intravenously withMycobacterium bovisBCG to mimic the systemic spread of mycobacteria under defined experimental conditions. After intravenous infection withM. bovisBCG, Mincle-KO mice responded with significantly higher numbers of mycobacterial CFU in spleen and liver, while reduced granuloma formation was observed only in the spleen. At the same time, reduced Th1 cytokine production and decreased numbers of gamma interferon-producing T cells were observed in the spleens of Mincle-KO mice relative to the numbers in the spleens of wild-type (WT) mice. The effect of adoptive transfer of defined WT leukocyte subsets generated from bone marrow cells of zDC+/DTRmice (which bear the human diphtheria toxin receptor [DTR] under the control of the classical dendritic cell-specific zinc finger transcription factor zDC) to specifically deplete Mincle-expressing classical dendritic cells (cDCs) but not macrophages after diphtheria toxin application on the numbers of splenic and hepatic CFU and T cell subsets was then determined. Adoptive transfer experiments revealed that Mincle-expressing splenic cDCs rather than Mincle-expressing macrophages contributed to the reconstitution of attenuated splenic antimycobacterial immune responses in Mincle-KO mice after intravenous challenge with BCG. Collectively, we show that expression of Mincle, particularly by cDCs, contributes to the control of splenicM. bovisBCG infection in mice.
Plasmid-Encoded MCP Is Involved in Virulence, Motility, and Biofilm Formation of Cronobacter sakazakii ATCC 29544
Authors: Choi Younho , Kim Seongok , Hwang Hyelyeon , Kim Kwang-Pyo , Kang Dong-Hyun , Ryu Sangryeol
Published: October 2014

The aim of this study was to elucidate the function of the plasmid-borne
mcp
(methyl-accepting chemotaxis protein) gene, which plays pleiotropic roles in
Cronobacter sakazakii
ATCC 29544. By searching for virulence factors using a random transposon insertion mutant library, we identified and sequenced a new plasmid, pCSA2, in
C. sakazakii
ATCC 29544. An
in silico
analysis of pCSA2 revealed that it included six putative open reading frames, and one of them was
mcp
. The
mcp
mutant was defective for invasion into and adhesion to epithelial cells, and the virulence of the
mcp
mutant was attenuated in rat pups. In addition, we demonstrated that putative MCP regulates the motility of
C. sakazakii
, and the expression of the flagellar genes was enhanced in the absence of a functional
mcp
gene. Furthermore, a lack of the
mcp
gene also impaired the ability of
C. sakazakii
to form a biofilm. Our results demonstrate a regulatory role for MCP in diverse biological processes, including the virulence of
C. sakazakii
ATCC 29544. To the best of our knowledge, this study is the first to elucidate a potential function of a plasmid-encoded MCP homolog in the
C. sakazakii
sequence type 8 (ST8) lineage.
Flavobacterium johnsoniae PorV Is Required for Secretion of a Subset of Proteins Targeted to the Type IX Secretion System
Authors: Kharade Sampada S. , McBride Mark J.
Published: October 2014

Flavobacterium johnsoniae
exhibits gliding motility and digests many polysaccharides, including chitin. A novel protein secretion system, the type IX secretion system (T9SS), is required for gliding and chitin utilization. The T9SS secretes the cell surface motility adhesins SprB and RemA and the chitinase ChiA. Proteins involved in secretion by the T9SS include GldK, GldL, GldM, GldN, SprA, SprE, and SprT.
Porphyromonas gingivalis
has orthologs for each of these that are required for secretion of gingipain protease virulence factors by its T9SS.
P. gingivalis
porU
and
porV
have also been linked to T9SS-mediated secretion, and
F. johnsoniae
has orthologs of these. Mutations in
F. johnsoniae
porU
and
porV
were constructed to determine if they function in secretion. Cells of a
porV
deletion mutant were deficient in chitin utilization and failed to secrete ChiA. They were also deficient in secretion of the motility adhesin RemA but retained the ability to secrete SprB. SprB is involved in gliding motility and is needed for formation of spreading colonies on agar, and the
porV
mutant exhibited gliding motility and formed spreading colonies. However, the
porV
mutant was partially deficient in attachment to glass, apparently because of the absence of RemA and other adhesins on the cell surface. The
porV
mutant also appeared to be deficient in secretion of numerous other proteins that have carboxy-terminal domains associated with targeting to the T9SS. PorU was not required for secretion of ChiA, RemA, or SprB, indicating that it does not play an essential role in the
F. johnsoniae
T9SS.
Noncanonical Cell-to-Cell DNA Transfer in Thermus spp. Is Insensitive to Argonaute-Mediated Interference
Authors: Blesa Alba , César Carolina Elvira , Averhoff Beate , Berenguer José
Published: October 2014

Horizontal gene transfer drives the rapid evolution of bacterial populations. Classical processes that promote the lateral flow of genetic information are conserved throughout the prokaryotic world. However, some species have nonconserved transfer mechanisms that are not well known. This is the case for the ancient extreme thermophile
Thermus thermophilus
. In this work, we show that
T. thermophilus
strains are capable of exchanging large DNA fragments by a novel mechanism that requires cell-to-cell contacts and employs components of the natural transformation machinery. This process facilitates the bidirectional transfer of virtually any DNA locus but favors by 10-fold loci found in the megaplasmid over those in the chromosome. In contrast to naked DNA acquisition by transformation, the system does not activate the recently described DNA-DNA interference mechanism mediated by the prokaryotic Argonaute protein, thus allowing the organism to distinguish between DNA transferred from a mate and exogenous DNA acquired from unknown hosts. This Argonaute-mediated discrimination may be tentatively viewed as a strategy for safe sharing of potentially “useful” traits by the components of a given population of
Thermus
spp. without increasing the genome sizes of its individuals.
Loss of FliL Alters Proteus mirabilis Surface Sensing and Temperature-Dependent Swarming
Authors: Lee Yi-Ying , Belas Robert
Published: October 2014

Proteus mirabilis
is a dimorphic motile bacterium well known for its flagellum-dependent swarming motility over surfaces. In liquid,
P. mirabilis
cells are 1.5- to 2.0-μm swimmer cells with 4 to 6 flagella. When
P. mirabilis
encounters a solid surface, where flagellar rotation is limited, swimmer cells differentiate into elongated (10- to 80-μm), highly flagellated swarmer cells. In order for
P. mirabilis
to swarm, it first needs to detect a surface. The ubiquitous but functionally enigmatic flagellar basal body protein FliL is involved in
P. mirabilis
surface sensing. Previous studies have suggested that FliL is essential for swarming through its involvement in viscosity-dependent monitoring of flagellar rotation. In this study, we constructed and characterized Δ
fliL
mutants of
P. mirabilis
and
Escherichia coli
. Unexpectedly and unlike other
fliL
mutants, both
P. mirabilis
and
E. coli
Δ
fliL
cells swarm (Swr
+
). Further analysis revealed that
P. mirabilis
Δ
fliL
cells also exhibit an alteration in their ability to sense a surface: e.g., Δ
fliL
P. mirabilis
cells swarm precociously over surfaces with low viscosity that normally impede wild-type swarming. Precocious swarming is due to an increase in the number of elongated swarmer cells in the population. Loss of
fliL
also results in an inhibition of swarming at <30°C.
E. coli
Δ
fliL
cells also exhibit temperature-sensitive swarming. These results suggest an involvement of FliL in the energetics and function of the flagellar motor.
The Diguanylate Cyclase GcbA Facilitates Pseudomonas aeruginosa Biofilm Dispersion by Activating BdlA
Authors: Petrova Olga E. , Cherny Kathryn E. , Sauer Karin
Published: October 2014

Biofilm dispersion is a highly regulated process that allows biofilm bacteria to respond to changing environmental conditions and to disseminate to new locations. The dispersion of biofilms formed by the opportunistic pathogen
Pseudomonas aeruginosa
is known to require a number of cyclic di-GMP (c-di-GMP)-degrading phosphodiesterases (PDEs) and the chemosensory protein BdlA, with BdlA playing a pivotal role in regulating PDE activity and enabling dispersion in response to a wide array of cues. BdlA is activated during biofilm growth via posttranslational modifications and nonprocessive cleavage in a manner that is dependent on elevated c-di-GMP levels. Here, we provide evidence that the diguanylate cyclase (DGC) GcbA contributes to the regulation of BdlA cleavage shortly after initial cellular attachment to surfaces and, thus, plays an essential role in allowing biofilm cells to disperse in response to increasing concentrations of a variety of substances, including carbohydrates, heavy metals, and nitric oxide. DGC activity of GcbA was required for its function, as a catalytically inactive variant could not rescue impaired BdlA processing or the dispersion-deficient phenotype of
gcbA
mutant biofilms to wild-type levels. While modulating BdlA cleavage during biofilm growth, GcbA itself was found to be subject to c-di-GMP-dependent and growth-mode-specific regulation. GcbA production was suppressed in mature wild-type biofilms and could be induced by reducing c-di-GMP levels via overexpression of genes encoding PDEs. Taken together, the present findings demonstrate that the regulatory functions of c-di-GMP-synthesizing DGCs expand beyond surface attachment and biofilm formation and illustrate a novel role for DGCs in the regulation of the reverse sessile-motile transition of dispersion.