In vitro selection of resistance in Streptococcus pneumoniae at in vivo fluoroquinolone concentrations

Methods: Twenty strains of S. pneumoniae susceptible to fluoroquinolones were used. The frequencies of spontaneous single-step mutations at plasma and epithelial lining fluid (ELF) peak and trough antibiotic concentrations were calculated. Multi-step selection of resistance was evaluated by performing 10 serial subcultures on agar plates containing a linear gradient from peak to trough antimicrobial concentrations, followed by 10 subcultures on antibiotic-free agar. Resistant strains selected after multi-step selection were characterized for DNA mutations by sequencing gyrA, gyrB, parC and parE genes. Results: Levofloxacin and moxifloxacin showed the lowest frequencies of mutations (median <10 211 ) at plasma peak and at ELF concentrations, while medians ranging from 10 28 to 10 26 were observed for ciprofloxacin and prulifloxacin. In a multi-step selection assay, ciprofloxacin and prulifloxacin selected for the highest number of resistant strains (19 and 31, respectively). No selection of resistance was observed for levofloxacin at ELF concentrations and for moxifloxacin at plasma and ELF concentrations. Mutations in parC, parE and gyrA genes were found in ciprofloxacin- and prulifloxacinresistant strains, while only parC mutations were found for levofloxacin. Conclusions: Levofloxacin and moxifloxacin are characterized by a lower propensity to select in vitro for resistance in S. pneumoniae than ciprofloxacin and prulifloxacin, when tested at plasma and lung concentrations

Quali Ragioni e Quali Possibili Soluzioni per il Mancato Sviluppo Della Dialisi Peritoneale in Italia

Abstract non disponibil

Daylight-Transfer Systems: Physiological And Energetic Advantages

Daylight-transfer systems are devices designed to operate according to the law of reflection: they collect and transfer it to rooms lacking in light. On the whole, possible applications can deal with rooms which do not communicate directly with the outside. For instance, it can be the case of both basements and large-sized buildings like those devoted to the service industry. In recent years, the considerable attention devoted to sustainable development has prompted planners to reconsider the use of daylighting in architecture. Current research, partly examined in this article, aims at producing a range of systematised products and techniques according to some specific characteristics in order to highlight the advantages of these systems in terms of energy conservation as for essential artificial lighting and, consequently, to contribute towards decreasing the use of non-renewable sources of energy and related problems about sustainability

Fast analysis of large finite arrays with a combined multiresolution-SM/AIM approach

We present a synthesis of the sparse matrix/adaptive integral method (SM/AIM) and the multiresolution (MR) approach for the analysis of electrically large finite arrays, with planar or 3-D radiating elements; the two methods were separately introduced previously. The use of the MR has the effect of a preconditioner and speeds up the convergence rate of the SM/AIM of almost two orders of magnitude, with a total reduction of the numerical complexity with respect to the standard MoM of almost three orders of magnitude

La imagen en la novel hipertextual electrónica : el caso de Stuart Moulthrop

Este artículo describe la utilización de la imagen en algunos hipertextos electrónicos literarios, tomando como eje la experimentación y la hibridación entre narrativa y juego que ha hecho en algunas de sus obras Stuart Moulthrop, uno de los autores más reconocidos en el campo.This article describes image uses in some electronic literary hypertexts; it focuses on covering the experimentation and hybridization between narrative and games made in some of his works by Stuart Moulthrop, one of the most renowned authors in the field

Could specific EKG markers identify a pharmacologically induced type 1 Brugada pattern? Insights from a large, single-centre cohort

Abstract Funding Acknowledgements Type of funding sources: None. Background. Pharmacological (Ajmaline) induction of a type 1 Brugada pattern is currently considered mandatory for the diagnosis of Brugada syndrome. However, performing the test requires time and healthcare resources. Some EKG markers have been proposed as predictors of positive result at Ajmaline test. Aim. To evaluate in a large population the predictive value of multiple EKG markers for Ajmaline test results. Methods. We retrospectively analysed consecutive patients (pts) referred to our Centre to perform Ajmaline test. All pts had type 2 Brugada pattern detected at a conventional EKG or were relatives of pts with positive Ajmaline test, with or without type 2 Brugada pattern at EKG. All pts performed the Ajmaline pharmacological test (1 mg/Kg iv) with EKG "superior" right precordial unipolar derivations monitoring. To determine whether clinical parameters (age, gender, cardiomyopathy, history of arrhythmias, symptoms, familiarity) and EKG markers (heart rate (HR), PR duration, R1V1 and SV6 duration and amplitude, QRSV1/QRSV6 duration, V1 and V2 ST amplitude (coved or saddle back pattern) were independently associated to positivity at Ajmaline test, a logistic regression model was applied. Results. From January 2010 to December 2019 we evaluated 442 consecutive pts: mean age 40.1 ± 14.5 years; 273 (65%) male; 352 (80%) pts were included because of type 2 Brugada pattern at EKG and 90 (20%) for familial screening. The Ajmaline test was positive in 150 (34%) pts. At multivariate logistic regression analysis adjusted for baseline confounders, age &gt; 45 years (OR= 1.64, 95%CI: 1.03 to 2.54; p = 0.0385), female gender (OR = 1.79, 95%CI: 1.12 to 2.85; p = 0.0141), HR &gt; 60 bpm (OR = 2.44, 95%CI: 1.48 to 4.03; p = 0.0005), QRSV1/QRSV6 duration (msec) &gt;1 (OR = 5.34, 95%CI: 3.28 to 8.69; p &lt; 0.0001) and non isoelectric pattern (coved/saddle back) in V2 (OR = 1.93, 95%CI: 1.03 to 3.63, p = 0.0416) remained associated with a positive Ajmaline test. The percentage of pts with positive Ajmaline test increased according to the presence of significant EKG markers in their risk profile: 11.3% (8 out 71, absence of both QRSV1/QRSV6 duration (msec) &gt;1 and V2 non isoelectric pattern), 24.3% (50 out 206, presence of only V2 non isoelectric pattern), 48.5% (16 out 33, presence of only QRSV1/QRSV6 duration (msec) &gt;1), 57.6% (76 out 132, presence of both factors). Conclusions. In our large population: 1) we confirmed the positive predictive power of QRSV1/QRSV6 duration (msec) &gt;1 and of a non isoelectric pattern (coved/saddle back) in V2 for a pharmacologically induced type 1 Brugada pattern; 2) we observed a non-negligible percentage of pts who would not be correctly diagnosed for type 1 Brugada pattern, if selected according to an EKG parameters-based prescreening

Dynamical charge density fluctuations pervading the phase diagram of a Cu-based high-Tc superconductor

Charge density waves are a common occurrence in all families of high critical temperature superconducting cuprates. Although consistently observed in the underdoped region of the phase diagram and at relatively low temperatures, it is still unclear to what extent they influence the unusual properties of these systems. Using resonant x-ray scattering we carefully determined the temperature dependence of charge density modulations in (Y,Nd)Ba$_2$Cu$_3$O$_{7-{\delta}}$ for three doping levels. We discovered short-range dynamical charge density fluctuations besides the previously known quasi-critical charge density waves. They persist up to well above the pseudogap temperature T*, are characterized by energies of few meV and pervade a large area of the phase diagram, so that they can play a key role in shaping the peculiar normal-state properties of cuprates.Comment: 34 pages, 4 figures, 11 supplementary figure

Development of a Novel Snom Probe for in Liquid Biological Samples

This work is focused on the study and implementation of a novel method for the development of probes for Scanning Near-field Optical Microscopy (SNOM). The proposed approach is based on the mechanical impedance matching between the optical fiber tip and the resonating tuning fork. This methodology allowed an increase of the quality factor of the piezoelectric resonator used as atomic force transducer in the SNOM probe, thus increasing its overall sensitivity. This kind of probes are often used on biological soft samples in liquid. The presence of water medium has a strong dumping effect on probe sensitivity. Experimental validation of the proposed methodology showed an increase of robustness of SNOM probes also for in liquid samples