Activity of fosfomycin and amikacin against fosfomycin-heteroresistant Escherichia coli strains in a hollow-fiber infection model.

Objectives:To evaluate human-like intravenous doses of fosfomycin (8g/Q8h) and amikacin (15mg/kg/Q24h) efficacy in monotherapy and in combination against six fosfomycin-heteroresistant Escherichia coli isolates using a hollow-fiber infection model (HFIM).Materials and methods:Six fosfomycin-heteroresistant E. coli isolates (4 with strong mutator phenotype) and the control strain E. coli ATCC 25922 were used. Mutant frequencies for rifampin (100mg/L), fosfomycin (50 and 200mg/L) and amikacin (32mg/L) were determined. Fosfomycin and amikacin MICs were assessed by agar dilution (AD), gradient strip (GSA) and broth microdilution (BMD) assays. Fosfomycin and amikacin synergies were studied by checkerboard and time-kill assays at different concentrations. Fosfomycin (8g/Q8h) and amikacin (15mg/kg/Q24h) efficacy alone and in combination were assessed using a HFIM.Results:Five isolates were resistant to fosfomycin by AD and BMD, but all susceptible by GSA. All isolates were considered susceptible to amikacin. Antibiotic combinations were synergistic in two isolates and no antagonism was detected. In time-kill assays, all isolates survived under fosfomycin at 64mg/L, although, at 307mg/L, only the normomutators and two hypermutators survived. Four isolates survived under 16mg/L amikacin and none at 45mg/L. No growth was detected under combination conditions. In HFIM, fosfomycin and amikacin monotherapies failed to sterilise bacterial cultures, however, fosfomycin and amikacin combination showed a rapid eradication.Conclusions.There may be a risk of treatment failure of fosfomycin-heteroresistant E. coli isolates using either amikacin or fosfomycin in monotherapy. These results support that the combination amikacin-fosfomycin can rapidly decrease bacterial burden and prevent the emergence of resistant subpopulations against fosfomycin-heteroresistant strains.

Effect of RecA inactivation and detoxification systems on the evolution of ciprofloxacin resistance in Escherichia coli.

BACKGROUND: Suppression of SOS response and overproduction of reactive oxygen species (ROS) through detoxification system suppression enhance the activity of fluoroquinolones. OBJECTIVES: To evaluate the role of both systems in the evolution of resistance to ciprofloxacin in an isogenic model of Escherichia coli. METHODS: Single-gene deletion mutants of E. coli BW25113 (wild-type) (ΔrecA, ΔkatG, ΔkatE, ΔsodA, ΔsodB), double-gene (ΔrecA-ΔkatG, ΔrecA-ΔkatE, ΔrecA-ΔsodA, ΔrecA-ΔsodB, ΔkatG-ΔkatE, ΔsodB-ΔsodA) and triple-gene (ΔrecA-ΔkatG-ΔkatE) mutants were included. The response to sudden high ciprofloxacin pressure was evaluated by mutant prevention concentration (MPC). The gradual antimicrobial pressure response was evaluated through experimental evolution and antibiotic resistance assays. RESULTS: For E. coli BW25113 strain, ΔkatE, ΔsodB and ΔsodB/ΔsodA mutants, MPC values were 0.25 mg/L. The ΔkatG, ΔsodA, ΔkatG/katE and ΔrecA mutants showed 2-fold reductions (0.125 mg/L). The ΔkatG/ΔrecA, ΔkatE/ΔrecA, ΔsodA/ΔrecA, ΔsodB/ΔrecA and ΔkatG/ΔkatE/ΔrecA strains showed 4-8-fold reductions (0.03-0.06 mg/L) relative to the wild-type. Gradual antimicrobial pressure increased growth capacity for ΔsodA and ΔsodB and ΔsodB/ΔsodA mutants (no growth in 4 mg/L) compared with the wild-type (no growth in the range of 0.5-2 mg/L). Accordingly, increased growth was observed with the mutants ΔrecA/ΔkatG (no growth in 2 mg/L), ΔrecA/ΔkatE (no growth in 2 mg/L), ΔrecA/ΔsodA (no growth in 0.06 mg/L), ΔrecA/ΔsodB (no growth in 0.25 mg/L) and ΔrecA/ΔkatG/ΔkatE (no growth in 0.5 mg/L) compared with ΔrecA (no growth in the range of 0.002-0.015 mg/L). CONCLUSIONS: After RecA inactivation, gradual exposure to ciprofloxacin reduces the evolution of resistance. After suppression of RecA and detoxification systems, sudden high exposure to ciprofloxacin reduces the evolution of resistance in E. coli.

Synergistic Quinolone Sensitization by Targeting the recA SOS Response Gene and Oxidative Stress.

Suppression of the recA SOS response gene and reactive oxygen species (ROS) overproduction have been shown, separately, to enhance fluoroquinolone activity and lethality. Their putative synergistic impact as a strategy to potentiate the efficacy of bactericidal antimicrobial agents such as fluoroquinolones is unknown. We generated Escherichia coli mutants that exhibited a suppressed ΔrecA gene in combination with inactivated ROS detoxification system genes (ΔsodA, ΔsodB, ΔkatG, ΔkatE, and ΔahpC) or inactivated oxidative stress regulator genes (ΔoxyR and ΔrpoS) to evaluate the interplay of both DNA repair and detoxification systems in drug response. Synergistic sensitization effects, ranging from 7.5- to 30-fold relative to the wild type, were observed with ciprofloxacin in double knockouts of recA and inactivated detoxification system genes. Compared to recA knockout, inactivation of an additional detoxification system gene reduced MIC values up to 8-fold. In growth curves, no growth was evident in mutants doubly deficient for recA gene and oxidative detoxification systems at subinhibitory concentrations of ciprofloxacin, in contrast to the recA-deficient strain. There was a marked reduction of viable bacteria in a short period of time when the recA gene and other detoxification system genes (katG, sodA, or ahpC) were inactivated (using absolute ciprofloxacin concentrations). At 4 h, a bactericidal effect of ciprofloxacin was observed for ΔkatG ΔrecA and ΔahpC ΔrecA double mutants compared to the single ΔrecA mutant (Δ3.4 log10 CFU/ml). Synergistic quinolone sensitization, by targeting the recA gene and oxidative detoxification stress systems, reinforces the role of both DNA repair systems and ROS in antibiotic-induced bacterial cell death, opening up a new pathway for antimicrobial sensitization.

Interplay among Different Fosfomycin Resistance Mechanisms in Klebsiella pneumoniae.

The objectives of this study were to characterize the role of the uhpT, glpT, and fosA genes in fosfomycin resistance in Klebsiella pneumoniae and evaluate the use of sodium phosphonoformate (PPF) in combination with fosfomycin. Seven clinical isolates of K. pneumoniae and the reference strain (ATCC 700721) were used, and their genomes were sequenced. ΔuhpT, ΔglpT, and ΔfosA mutants were constructed from two isolates and K. pneumoniae ATCC 700721. Fosfomycin susceptibility testing was done by the gradient strip method. Synergy between fosfomycin and PPF was studied by checkerboard assay and analyzed using SynergyFinder. Spontaneous fosfomycin mutant frequencies at 64 and 512 mg/liter, in vitro activity using growth curves with fosfomycin gradient concentrations (0 to 256mg/liter), and time-kill assays at 64 and 307 mg/liter were evaluated with and without PPF (0.623 mM). The MICs of fosfomycin against the clinical isolates ranged from 16 to ≥1,024 mg/liter. The addition of 0.623 mM PPF reduced fosfomycin MIC between 2- and 8-fold. Deletion of fosA led to a 32-fold decrease. Synergistic activities were observed with the combination of fosfomycin and PPF (most synergistic area at 0.623 mM). The lowest fosfomycin-resistant mutant frequencies were found in ΔfosA mutants, with decreases in frequency from 1.69 × 10-1 to 1.60 × 10-5 for 64 mg/liter of fosfomycin. In the final growth monitoring and time-kill assays, fosfomycin showed a bactericidal effect only with the deletion of fosA and not with the addition of PPF. We conclude that fosA gene inactivation leads to a decrease in fosfomycin resistance in K. pneumoniae The pharmacological approach using PPF did not achieve enough activity, and the effect decreased with the presence of fosfomycin-resistant mutations.

Effect of RecA inactivation on quinolone susceptibility and the evolution of resistance in clinical isolates of Escherichia coli.

BACKGROUND: SOS response suppression (by RecA inactivation) has been postulated as a therapeutic strategy for potentiating antimicrobials against Enterobacterales. OBJECTIVES: To evaluate the impact of RecA inactivation on the reversion and evolution of quinolone resistance using a collection of Escherichia coli clinical isolates. METHODS: Twenty-three E. coli clinical isolates, including isolates belonging to the high-risk clone ST131, were included. SOS response was suppressed by recA inactivation. Susceptibility to fluoroquinolones was determined by broth microdilution, growth curves and killing curves. Evolution of quinolone resistance was evaluated by mutant frequency and mutant prevention concentration (MPC). RESULTS: RecA inactivation resulted in 2-16-fold reductions in fluoroquinolone MICs and modified EUCAST clinical category for several isolates, including ST131 clone isolates. Growth curves and time-kill curves showed a clear disadvantage (up to 10 log10 cfu/mL after 24 h) for survival in strains with an inactivated SOS system. For recA-deficient mutants, MPC values decreased 4-8-fold, with values below the maximum serum concentration of ciprofloxacin. RecA inactivation led to a decrease in mutant frequency (≥103-fold) compared with isolates with unmodified SOS responses at ciprofloxacin concentrations of 4×MIC and 1 mg/L. These effects were also observed in ST131 clone isolates. CONCLUSIONS: While RecA inactivation does not reverse existing resistance, it is a promising strategy for increasing the effectiveness of fluoroquinolones against susceptible clinical isolates, including high-risk clone isolates.

Blood Orange Juice Consumption Increases Flow-Mediated Dilation in Adults with Overweight and Obesity: A Randomized Controlled Trial.

BACKGROUND: Epidemiological studies have indicated an inverse association between citrus fruit consumption and cardiovascular disease (CVD) risk. There is, however, a paucity of data concerning effects of blood orange juice (BOJ) intake on endothelial function and cardiovascular risk biomarkers. OBJECTIVES: We examined short-term effects of BOJ on endothelial function, blood pressure, lipid profile, and inflammatory markers in healthy participants of European origin who were overweight or obese. METHODS: In a randomized, controlled, single-blind, crossover trial, 15 men and women (age: 28.7 ± 6.5 y; BMI: 28.3 ± 3.1 kg/m2) consumed BOJ or a sugar-matched control drink (CD) (200 mL twice daily) for 2 wk with a washout period of 1 wk. Endothelial function, measured as flow-mediated dilation (FMD) (primary outcome), and the secondary outcomes blood pressure, anthropometric measures, lipid profile, inflammatory markers, markers of vasodilation and vasoconstriction, and urinary flavanone metabolites were evaluated prior to and at the end of each treatment period following an overnight fast. Changes between treatments over time were assessed using repeated-measures ANOVA. RESULTS: The results demonstrate a significant increase in FMD following BOJ consumption (pre: 8.15% ± 2.92%; post: 10.2% ± 3.31%; P = 0.002) compared with CD (pre: 8.11% ± 2.52%; post: 7.77% ± 2.43%; time × treatment interaction: P = 0.001). Concurrent significant increases in urinary hesperetin-3'-glucuronide and hesperetin-7-glucuronide were observed following BOJ supplementation only (time × treatment interaction: P ≤ 0.01). Baseline blood pressure, lipid profile, high-sensitivity C-reactive protein, and endothelin-1 were generally within healthy ranges and unaffected by the intervention. CONCLUSIONS: A 2-wk consumption of BOJ exerted favorable effects on endothelial function in healthy women and men who were overweight or obese, which is likely mediated by the combined actions of anthocyanin and flavanone metabolites on mechanisms that contribute to enhancing NO bioavailability. This trial was registered at clinicaltrials.gov as NCT03611114.

Suppression of the SOS response modifies spatiotemporal evolution, post-antibiotic effect, bacterial fitness and biofilm formation in quinolone-resistant Escherichia coli.

Background: Suppression of the SOS response has been proposed as a therapeutic strategy for potentiating quinolones against susceptible, low-level quinolone-resistant (LLQR) and resistant Enterobacteriaceae. Objectives: To monitor the functionality of the SOS response in the evolution towards clinical quinolone resistance and study its impact on the evolution of spatiotemporal resistance. Methods: An isogenic collection of Escherichia coli (derived from the strain ATCC 25922) carrying combinations of chromosomally and plasmid-mediated quinolone resistance mechanisms (including susceptible, LLQR and resistant phenotypes) and exhibiting a spectrum of SOS activity was used. Relevant clinical parameters such as mutation rate, mutant prevention concentration (MPC), bacterial fitness, biofilm formation and post-antibiotic effect (PAE) were evaluated. Results: Inactivating the SOS response (recA deletion) led to a decrease in mutation rate (∼103 fold) in LLQR compared with WT strains at ciprofloxacin concentrations of 1 mg/L (the EUCAST breakpoint for resistance) and 2.5 mg/L (Cmax), as well as a remarkable delay in the spatiotemporal evolution of quinolone resistance. For all strains, there was an 8-fold decrease in MPC in RecA-deficient strains, with values for LLQR strains decreasing below the Cmax of ciprofloxacin. Inactivation of the SOS response reduced competitive fitness by 33%-50%, biofilm production by 22%-80% and increased the PAE by ∼3-4 h at sub-MIC concentrations of ciprofloxacin. Conclusions: Our data indicate that suppression of the SOS response affects key bacterial traits and is a promising strategy for reversing and tackling the evolution of antibiotic resistance in E. coli, including low-level and resistant phenotypes at therapeutic quinolone concentrations.

Correction to: Ouabain Accelerates Collective Cell Migration Through a cSrc and ERK1/2 Sensitive Metalloproteinase Activity.

The original version of the article unfortunately contained an error in the author group. Dr. Isabel Larré was not submitted and published in the original version.

Ouabain Accelerates Collective Cell Migration Through a cSrc and ERK1/2 Sensitive Metalloproteinase Activity.

Studies made in the Madin-Darby canine kidney (MDCK) epithelial cell line showed that ouabain regulates cell adhesion and cell-adhesion-related biological processes, such as migration. Here, we demonstrated that 10 nM ouabain accelerates collective cell migration and heals wounds in cultured MDCK cell monolayers. Ouabain-induced acceleration of cell migration depends on activation of the cSrc-ERK1/2 signaling cascade, as it was inhibited by the kinase inhibitors PP2 and PD98059. Activation of the cSrc-ERK1/2 signaling cascade increased expression and activation of the extracellular matrix metalloproteinase-2 (MMP-2). Inhibition of MMP activity using the generic inhibitor GM6001 or the potent iMMP-2 inhibitor prevented the accelerative effect of ouabain. Likewise, Focal Adhesion Kinase (FAK) inhibition with the transfection of dominant negative peptide FRNK impaired the effect of ouabain. These results suggest that ouabain binding to the Na+,K+-ATPase accelerates collective migration of MDCK cells through activation of the cSrc-ERK1/2-FAK signaling cascade and promoting secretion and MMP activity.

Urinary Tract Conditions Affect Fosfomycin Activity against Escherichia coli Strains Harboring Chromosomal Mutations Involved in Fosfomycin Uptake.

The steps by which Escherichia coli strains harboring mutations related to fosfomycin (FOS) resistance arise and spread during urinary tract infections (UTIs) are far from being understood. The aim of this study was to evaluate the effects of urine, pH, and anaerobiosis on FOS activity against a set of isogenic strains carrying the most prevalent chromosomal mutations conferring FOS resistance (ΔuhpT, ΔglpT, ΔcyaA, and ΔptsI), either singly or in combination. We also studied fosfomycin-resistant E. coli clinical isolates from patients with UTI. Our results demonstrate that urinary tract physiological conditions might have a profound impact on FOS activity against strains with chromosomal FOS resistance mutations. Specifically, acidic pH values and anaerobiosis convert most of the strains categorized as resistant to fosfomycin according to the international guidelines to a susceptible status. Therefore, urinary pH values may have practical interest in the management of UTIs. Finally, our results, together with the high fitness cost associated with FOS resistance mutations, might explain the low prevalence of fosfomycin-resistant E. coli variants in UTIs.

Molecular insights into fosfomycin resistance in Escherichia coli.

Objectives: Fosfomycin activity in Escherichia coli depends on several genes of unknown importance for fosfomycin resistance. The objective was to characterize the role of uhpT , glpT , cyaA and ptsI genes in fosfomycin resistance in E. coli. Methods: WT E. coli BW25113 and null mutants, Δ uhpT , Δ glpT , Δ cyaA , Δ ptsI , Δ glpT-uhpT , Δ glpT-cyaA , Δ glpT-ptsI , Δ uhpT-cyaA , Δ uhpT-ptsI and Δ ptsI-cyaA , were studied. Susceptibility to fosfomycin was tested using CLSI guidelines. Fosfomycin mutant frequencies were determined at concentrations of 64 and 256 mg/L. Fosfomycin in vitro activity was tested using time-kill assays at concentrations of 64 and 307 mg/L (human C max ). Results: Fosfomycin MICs were: WT E. coli BW25113 (2 mg/L), Δ glpT (2 mg/L), Δ uhpT (64 mg/L), Δ cyaA (8 mg/L), Δ ptsI (2 mg/L), Δ glpT-uhpT (256 mg/L), Δ glpT-cyaA (8 mg/L), Δ glpT-ptsI (2 mg/L), Δ uhpT-cyaA (512 mg/L), Δ uhpT-ptsI (64 mg/L) and Δ ptsI-cyaA (32 mg/L). In the mutant frequency assays, no mutants were recovered from BW25113. Mutants appeared in Δ glpT , Δ uhpT , Δ cyaA and Δ ptsI at 64 mg/L and in Δ uhpT and Δ cyaA at 256 mg/L. Δ glpT-ptsI , but not Δ glpT-cyaA , Δ uhpT-cyaA or Δ uhpT-ptsI , increased the mutant frequency compared with the highest frequency found in each single mutant. In time-kill assays, all mutants regrew at 64 mg/L. Initial bacterial reductions of 2-4 log 10 cfu/mL were observed for all strains, except for Δ uhpT-ptsI , Δ glpT-uhpT and Δ uhpT-cyaA . Only Δ glpT and Δ ptsI mutants were cleared using 307 mg/L. Conclusions: Fosfomycin MIC may not be a good efficacy predictor, as highly resistant mutants may appear, depending on other pre-existing mutations with no impact on MIC.

New challenges in kidney cancer management: integration of surgery and novel therapies.

Despite early renal carcinoma diagnosis is more frequent nowadays, ~25-30 % of patients have metastatic disease at presentation and another ~30 % develop recurrent or metastatic disease after radical treatment for localized disease. In recent years, treatment of renal carcinoma is increasing in complexity due to the inclusion of a number of effective systemic treatments prolonging survival and increasing the therapeutic strategies for tumor debulking, or even achieving surgical complete responses and prolonged disease-free intervals. Initial multimodal approaches with immunotherapeutic agents are now being validated in patients treated with the new-targeted agents. Patients are now able to receive an optimal therapeutic strategy seeking a longer survival with an acceptable life quality and avoiding unnecessary comorbidities. In this context and as an initial therapeutic approach, it is imperative to promote patients' selection with established prognostic models within a multidisciplinary team to assess the recommendation of a cytoreductive nephrectomy (CN), metastasectomy, and/or systemic treatment. In the context of mRCC, when feasible and in patients with favorable prognostic factors, the strategy should be to consider a CN or metastasectomy for tumor debulking in order to achieve free intervals of prolonged disease. By contrast, it is recommended to evaluate whether to perform a biopsy for histological diagnosis without nephrectomy in the following situations: high surgical risk, bulky metastatic disease or in specific sites (brain or liver) or ECOG PS 3/4. The following review covers from initial to recent studies on the integration of systemic treatment and surgery in the context of metastatic disease for an optimal multimodal management in renal carcinoma.

Mechanical properties, in vitro degradation and cytocompatibility of woven textiles manufactured from PLA/PCL commingled yarns.

The mechanical, thermal, and biological performance of fabrics manufactured with hybrid PLA/PCL commingled yarns were studied. Commingled hybrid yarns take advantage of the higher elastic modulus of PLA and the higher ductility and toughness of PCL to produce yarns and fabrics with high strength and ductility that is transferred to the woven textiles. Furthermore, PLA and PCL exhibit different degradation rates and also allow to tailor this property. Degradation of the textiles was carried out in phosphate-buffered saline solution for up to 160 days at 37 °C and 50 °C (accelerated degradation). Neither the thermal nor the mechanical properties were altered by immersion at 37 °C during 80 days and a slight degradation was observed as a result of chain scission of the PLA fibres after 160 days. However, immersion at 50 °C led to a rapid reduction in strength after 40 days due to the hydrolysis of PLA, and the fabric was highly degraded after 160 days as a result of chain scission in PCL. Finally, while indirect tests did not predict optimal biocompatibility, the direct tests provided a different perspective of the cell interaction between the textile and pre-osteoblasts regarding cell attachment and cell morphology. These results show the potential of hybrid commingled yarns to manufacture textile scaffolds of biodegradable polymers with tailored mechanical properties and good ductility for connective tissue engineering (ligaments and tendons).

Selective Pressure by Rifampicin Modulates Mutation Rates and Evolutionary Trajectories of Mycobacterial Genomes.

Resistance to the frontline antibiotic rifampicin constitutes a challenge to the treatment and control of tuberculosis. Here, we analyzed the mutational landscape of Mycobacterium smegmatis during long-term evolution with increasing concentrations of rifampicin, using a mutation accumulation assay combined with whole-genome sequencing. Antibiotic treatment enhanced the acquisition of mutations, doubling the genome-wide mutation rate of the wild-type cells. While antibiotic exposure led to extinction of almost all wild-type lines, the hypermutable phenotype of the ΔnucS mutant strain (noncanonical mismatch repair deficient) provided an efficient response to the antibiotic, leading to high rates of survival. This adaptative advantage resulted in the emergence of higher levels of rifampicin resistance, an accelerated acquisition of drug resistance mutations in rpoB (ß RNA polymerase), and a wider diversity of evolutionary pathways that led to drug resistance. Finally, this approach revealed a subset of adaptive genes under positive selection with rifampicin that could be associated with the development of antibiotic resistance. IMPORTANCE Rifampicin is the most important first-line antibiotic against mycobacterial infections, including tuberculosis, one of the top causes of death worldwide. Acquisition of rifampicin resistance constitutes a major global public health problem that makes the control of the disease challenging. Here, we performed an experimental evolution assay under antibiotic selection to analyze the response and adaptation of mycobacteria, leading to the acquisition of rifampicin resistance. This approach explored the total number of mutations that arose in the mycobacterial genomes under long-term rifampicin exposure, using whole-genome sequencing. Our results revealed the effect of rifampicin at a genomic level, identifying different mechanisms and multiple pathways leading to rifampicin resistance in mycobacteria. Moreover, this study detected that an increase in the rate of mutations led to enhanced levels of drug resistance and survival. In summary, all of these results could be useful to understand and prevent the emergence of drug-resistant isolates in mycobacterial infections.

Exposure to diverse antimicrobials induces the expression of qnrB1, qnrD and smaqnr genes by SOS-dependent regulation.

OBJECTIVES: Direct SOS-dependent regulation of qnrB genes by fluoroquinolones mediated by LexA was reported. The smaqnr gene, on the Serratia marcescens chromosome, and qnrD both contain a putative LexA box. The aim of this study was to evaluate whether smaqnr or qnrD genes are induced via SOS-dependent mechanisms, and to investigate whether other antimicrobial agents induce qnrB, qnrD and smaqnr expression. METHODS: RT-PCR was used to evaluate qnrB1, qnrD and smaqnr expression. Different concentrations of ciprofloxacin, levofloxacin, moxifloxacin and ceftazidime were evaluated as inducers. Additionally, the promoter regions of qnrB1, qnrD and smaqnr were fused transcriptionally to green fluorescent protein and used in reporter gene assays. Disc diffusion assays with different antimicrobial agents were used to detect induction. Measurements of transcriptional induction by ciprofloxacin were carried out using a plate reader. RESULTS: RT-PCR assays showed that qnrB1, qnrD and smaqnr were induced at different concentrations of ciprofloxacin, moxifloxacin, levofloxacin and ceftazidime, increasing transcription 1.5- to 16.3-fold compared with basal expression, and depending on the antimicrobial agent and promoter analysed. The reporter gene assays showed that the qnrB1, qnrD and smaqnr genes were induced by ciprofloxacin, as expected, but also by ceftazidime, ampicillin and trimethoprim in Escherichia coli wild-type strains, but not in the recA-deficient E. coli HB101. Induction was not evident for imipenem or gentamicin. CONCLUSIONS: ß-Lactams and trimethoprim, along with fluoroquinolones, induce transcription of qnrB, qnrD and smaqnr genes using SOS-dependent regulation. These results show the direct SOS-dependent regulation of a low-level fluoroquinolone resistance mechanism in response to other antimicrobials.

Understanding of Crucial Factors for Improving the Energy Density of Lithium-Sulfur Pouch Cells.

Rechargeable lithium-sulfur (Li-S) batteries are the most promising next-generation energy storage system owing to their high energy density and low cost. Despite the increasing number of publications on the Li-S technology, the number of studies on real prototype cells is rather low. Furthermore, novel concepts developed using small lab cells cannot simply be transferred to high-energy cell prototypes due to the fundamental differences. The electrolyte and lithium anode excess used in small lab cells is known to have a huge impact on the cycle life, capacity, and rate capability of the Li-S system. This work analyses the performance of pouch cell prototypes demonstrating the potential and hurdles of the technology. The impact of electrolyte variations and the sulfur cathode loading are studied. The energy density of Li-S pouch cell is improved up to 436 Wh kg-1 by a combination of different approaches related to cell manufacturing, sulfur cathode optimization, and electrolyte amount adjustment.

Processing and mechanical properties of novel biodegradable poly-lactic acid/Zn 3D printed scaffolds for application in tissue regeneration.

The feasibility to manufacture scaffolds of poly-lactic acid reinforced with Zn particles by fused filament fabrication is demonstrated for the first time. Filaments of 2.85 mm in diameter of PLA reinforced with different weight fractions of µm-sized Zn - 1 wt.% Mg alloy particles (in the range 3.5 to 17.5 wt.%) were manufactured by a double extrusion method in which standard extrusion is followed by precision extrusion in a filament-maker machine. Filaments with constant diameter, negligible porosity and a homogeneous reinforcement distribution were obtained for Zn weight fractions of up to 10.5%. It was found that the presence of Zn particles led to limited changes in the physico-chemical properties of the PLA that did not affect the window temperature for 3D printing nor the melt flow index. Thus, porous scaffolds could be manufactured by fused filament fabrication at 190 °C with poly-lactic acid/Zn composites containing 3.5 and 7 wt.% of Zn and at 170 °C when the Zn content was 10.5 wt.% with excellent dimensional accuracy and mechanical properties.

AZ31 Magnesium Alloy Foils as Thin Anodes for Rechargeable Magnesium Batteries.

In recent decades, rechargeable Mg batteries (RMBs) technologies have attracted much attention because the use of thin Mg foil anodes may enable development of high-energy-density batteries. One of the most critical challenges for RMBs is finding suitable electrolyte solutions that enable efficient and reversible Mg cells operation. Most RMB studies concentrate on the development of novel electrolyte systems, while only few studies have focused on the practical feasibility of using pure metallic Mg as the anode material. Pure Mg metal anodes have been demonstrated to be useful in studying the fundamentals of nonaqueous Mg electrochemistry. However, pure Mg metal may not be suitable for mass production of ultrathin foils (<100 microns) due to its limited ductility. The metals industry overcomes this problem by using ductile Mg alloys. Herein, the feasibility of processing ultrathin Mg anodes in electrochemical cells was demonstrated by using AZ31 Mg alloys (3 % Al; 1 % Zn). Thin-film Mg AZ31 anodes presented reversible Mg dissolution and deposition behavior in complex ethereal Mg electrolytes solutions that was comparable to that of pure Mg foils. Moreover, it was demonstrated that secondary Mg battery prototypes comprising ultrathin AZ31 Mg alloy anodes (≈25 µm thick) and Mgx Mo6 S8 Chevrel-phase cathodes exhibited cycling performance equal to that of similar cells containing thicker pure Mg foil anodes. The possibility of using ultrathin processable Mg metal anodes is an important step in the realization of rechargeable Mg batteries.

Postprandial glucose-lowering effect of cagaita (Eugenia dysenterica DC) fruit juice in dysglycemic subjects with metabolic syndrome: An exploratory study.

Cagaita (Eugenia dysenterica DC) is an ellagitannin-containing Myrtaceae fruit from Cerrado biome. This fruit seems to be a promising candidate for an adjuvant in glucose regulation in healthy subjects. However, it is not known whether cagaita juice would have the same effect on dysglycemic subjects with metabolic syndrome (MetS). Therefore, the present work aimed to evaluate the effect of cagaita fruit juice on postprandial glycemia in dysglycemic subjects with MetS, and whether cagaita ellagitannins could be metabolized to urolithins. To evaluate glycemic effects, two different meals were consumed by volunteers (n = 12) with a 1-week interval among them. The first one consisted of white bread (50 g) plus water (300 mL) as a control; the second one, white bread (50 g) plus clarified cagaita juice (300 mL). Bioavailability was assessed in 24 h urine, after the consumption of a single amount of 300 mL of cagaita juice by healthy (n = 16) and MetS subjects (n = 7). The results showed that dysglycemic subjects with MetS presented a 53% reduction of incremental area under the curve (iAUC) of glucose, 38% reduction of insulin, 78% reduction of GIP (glucose-dependent insulinotropic polypeptide), and 58% reduction of C-peptide (p < 0.05), after the consumption of cagaita juice along with bread, in comparison to control water. However, both GLP-1 (glucagon-like peptide-1) and glucagon were not affected by cagaita juice ingestion. Concerning bioavailability, it was observed, for the first time, the metabolization of cagaita ellagitannins to urolithins by healthy and dysglycemic individuals with MetS, with a prevalence of metabotype B in both groups (44% and 42%, respectively), followed by metabotype A (37% and 29%, respectively), and metabotype 0 (19% and 29%, respectively).

Specificity and mutagenesis bias of the mycobacterial alternative mismatch repair analyzed by mutation accumulation studies.

The postreplicative mismatch repair (MMR) is an almost ubiquitous DNA repair essential for maintaining genome stability. It has been suggested that Mycobacteria have an alternative MMR in which NucS, an endonuclease with no structural homology to the canonical MMR proteins (MutS/MutL), is the key factor. Here, we analyze the spontaneous mutations accumulated in a neutral manner over thousands of generations by Mycobacterium smegmatis and its MMR-deficient derivative (ΔnucS). The base pair substitution rates per genome per generation are 0.004 and 0.165 for wild type and ΔnucS, respectively. By comparing the activity of different bacterial MMR pathways, we demonstrate that both MutS/L- and NucS-based systems display similar specificity and mutagenesis bias, revealing a functional evolutionary convergence. However, NucS is not able to repair indels in vivo. Our results provide an unparalleled view of how this mycobacterial system works in vivo to maintain genome stability and how it may affect Mycobacterium evolution.