799 research outputs found

    Geometric construction of D-branes in WZW models

    Get PDF
    The geometric description of D-branes in WZW models is pushed forward. Our starting point is a gluing condition\, J+=FJ−J_{+}=FJ_- that matches the model's chiral currents at the worldsheet boundary through a linear map FF acting on the WZW Lie algebra. The equivalence of boundary and gluing conditions of this type is studied in detail. The analysis involves a thorough discussion of Frobenius integrability, shows that FF must be an isometry, and applies to both metrically degenerate and nondegenerate D-branes. The isometry FF need not be a Lie algebra automorphism nor constantly defined over the brane. This approach, when applied to isometries of the form F=RF=R with RR a constant Lie algebra automorphism, validates metrically degenerate RR-twined conjugacy classes as D-branes. It also shows that no D-branes exist in semisimple WZW models for constant\, F=−RF=-R.Comment: 23 pages, discussion of limitations of the gluing condition approach adde

    Bismuth coordination networks containing deferiprone: synthesis, characterisation, stability and antibacterial activity

    Get PDF
    A series of bismuth–dicarboxylate–deferiprone coordination networks have been prepared and structurally characterised. The new compounds have been demonstrated to release the iron overload drug deferiprone on treatment with PBS and have also been shown to have antibacterial activity against H. pylori

    Plasma and cerebrospinal fluid concentrations of linezolid in neurosurgical critically ill patients with proven or suspected central nervous system infections

    Get PDF
    Linezolid is a valuable treatment option for central nervous system (CNS) infections caused by multidrug-resistant Gram-positive micro-organisms. Data regarding its penetration into the CNS have shown wide variability. The aim of this study was to describe the population pharmacokinetics of linezolid in plasma and cerebrospinal fluid (CSF) in critically ill patients with external CSF drainage and proven or suspected CNS infections. This was an observational pharmacokinetic (PK) study in 11 critically ill patients with proven or suspected CNS infection receiving linezolid. Serial blood and CSF samples were taken and were subject to population PK analysis. The median (interquartile range) of AUC(0-12h) was 47.6 (17.9-58.6) mg h/L in plasma and 21.1(18.8-30.4) mg h/L in CSF, with a median CSF/plasma ratio of 0.77. At pre-dose at steady state, a strong positive correlation was observed between linezolid concentrations in CSF and plasma (Spearman's rho = 0.758; P = 0.011). For a minimum inhibitory concentration (MIC) of 2 mg/L, the median AUC(0-24h)/MIC values in plasma and CSF wer

    Chitosan-coated mesoporous MIL-100(Fe) nanoparticles as improved bio-compatible oral nanocarriers

    Get PDF
    Nanometric biocompatible Metal-Organic Frameworks (nanoMOFs) are promising candidates for drug delivery. Up to now, most studies have targeted the intravenous route, related to pain and severe complications; whereas nanoMOFs for oral administration, a commonly used non-invasive and simpler route, remains however unexplored. We propose here the biofriendly preparation of a suitable oral nanocarrier based on the benchmarked biocompatible mesoporous iron(III) trimesate nanoparticles coated with the bioadhesive polysaccharide chitosan (CS). This method does not hamper the textural/ structural properties and the sorption/release abilities of the nanoMOFs upon surface engineering. The interaction between the CS and the nanoparticles has been characterized through a combination of high resolution soft X-ray absorption and computing simulation, while the positive impact of the coating on the colloidal and chemical stability under oral simulated conditions is here demonstrated. Finally, the intestinal barrier bypass capability and biocompatibility of CS-coated nanoMOF have been assessed in vitro, leading to an increased intestinal permeability with respect to the noncoated material, maintaining an optimal biocompatibility. In conclusion, the preservation of the interesting physicochemical features of the CS-coated nanoMOF and their adapted colloidal stability and progressive biodegradation, together with their improved intestinal barrier bypass, make these nanoparticles a promising oral nanocarrier

    A Robust and Biocompatible Bismuth Ellagate MOF Synthesized Under Green Ambient Conditions

    Get PDF
    The first bioinspired microporous metal-organic framework (MOF) synthesized using ellagic acid, a common natural antioxidant and polyphenol building unit, is presented. Bi2O(H2O)2(C14H2O8)\ub7nH2O (SU-101) was inspired by bismuth phenolate metallodrugs, and could be synthesized entirely from nonhazardous or edible reagents under ambient aqueous conditions, enabling simple scale-up. Reagent-grade and affordable dietary supplement-grade ellagic acid was sourced from tree bark and pomegranate hulls, respectively. Biocompatibility and colloidal stability were confirmed by in vitro assays. The material exhibits remarkable chemical stability for a bioinspired MOF (pH = 2-14, hydrothermal conditions, heated organic solvents, biological media, SO2 and H2S), attributed to the strongly chelating phenolates. A total H2S uptake of 15.95 mmol g-1 was recorded, representing one of the highest H2S capacities for a MOF, where polysulfides are formed inside the pores of the material. Phenolic phytochemicals remain largely unexplored as linkers for MOF synthesis, opening new avenues to design stable, eco-friendly, scalable, and low-cost MOFs for diverse applications, including drug delivery

    Economic evaluation of the treatment of Acute Bacterial Skin and Skin Structure Infections (ABSSSIs) from the national payer perspective : introduction of a new treatment to the patient journey. A simulation of three European countries

    Get PDF
    The aim of this study was to develop a spending predictor model to evaluate the direct costs associated with the management of ABSSSIs from the National health-care provider's perspective of Italy, Romania, and Spain. METHODOLOGY: A decision-analytic model was developed to evaluate the diagnostic and clinical pathways of hospitalized ABSSSI patients based on scientific guidelines and real-world data. A Standard of Care (SoC) scenario was compared with a dalbavancin scenario in which the patients could be discharged early. The epidemiological and cost parameters were extrapolated from national administrative databases (i.e., hospital information system). A probabilistic sensitivity analysis (PSA) and one-way sensitivity analysis (OWA) were performed. RESULTS: Overall, the model estimated an average annual number of patients with ABSSSIs of approximately 50,000 in Italy, Spain, and Romania. On average, the introduction of dalbavancin reduced the length of stay by 3.3 days per ABSSSI patient. From an economic perspective, dalbavancin did not incur any additional cost from the National Healthcare perspective, and the results were consistent among the countries. The PSA and OWA demonstrated the robustness of these results. CONCLUSION: This model represents a useful tool for policymakers by providing information regarding the economic and organizational consequences of an early discharge approach in ABSSSI management

    Aqueous Stable Gold Nanostar/ZIF‐8 Nanocomposites for Light‐Triggered Release of Active Cargo Inside Living Cells

    Get PDF
    This is the peer reviewed version of the following article: C. Carrillo-CarriĂłn, R. MartĂ­nez, M. F. Navarro Poupard, B. Pelaz, E. Polo, A. Arenas-Vivo, A. Olgiati, P. Taboada, M. G. Soliman, Ú. CatalĂĄn, S. FernĂĄndez-Castillejo, R. SolĂ , W. J. Parak, P. Horcajada, R. A. Alvarez-Puebla, P. del Pino, Angew. Chem. Int. Ed. 2019, 58, 7078, which has been published in final form at https:// doi.org/10.1002/anie.201902817. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsA plasmonic core–shell gold nanostar/zeolitic‐imidazolate‐framework‐8 (ZIF‐8) nanocomposite was developed for the thermoplasmonic‐driven release of encapsulated active molecules inside living cells. The nanocomposites were loaded, as a proof of concept, with bisbenzimide molecules as functional cargo and wrapped with an amphiphilic polymer that prevents ZIF‐8 degradation and bisbenzimide leaking in aqueous media or inside living cells. The demonstrated molecule‐release mechanism relies on the use of near‐IR light coupled to the plasmonic absorption of the core gold nanostars, which creates local temperature gradients and thus, bisbenzimide thermodiffusion. Confocal microscopy and surface‐enhanced Raman spectroscopy (SERS) were used to demonstrate bisbenzimide loading/leaking and near‐IR‐triggered cargo release inside cells, thereby leading to DNA stainingThis work has received financial support from the MINECO‐Spain (MAT2016‐80266‐R, MAT2015‐74381‐JIN, CTQ2017‐88648R, ENE2016‐79608‐C2‐1‐R, CTQ2017‐89588‐R, RYC‐2014‐15039, RYC‐2014‐16962), the Xunta de Galicia, Centro singular de investigaciĂłn de Galicia accreditation 2016–2019 (ED431G/09), the AgrupaciĂłn EstratĂ©gica de Materiales Action (ED431E 2018/08), the Generalitat de Cataluña (2017SGR522, 2017SGR883, SLT002/16/00239), the URV (2017PFR‐URV‐B2‐02), the German Research Society (DFG PA 794‐21‐1), and the European Union (European Regional Development Fund—ERDF, H2020‐MSCA‐IF‐2016, project 749667). M.F.N.P acknowledges the CONACYT PhD fellowship programS

    Designed Single-Step Synthesis, Structure, and Derivative Textural Properties of Well-Ordered Layered Penta-coordinate Silicon Alcoholate Complexes

    Get PDF
    The controllable synthesis of well-ordered layered materials with specific nanoarchitecture poses a grand challenge in materials chemistry. Here the solvothermal synthesis of two structurally analogous 5-coordinate organosilicate complexes through a novel transesterification mechanism is reported. Since the polycrystalline nature of the intrinsic hypervalent Si complex thwarts the endeavor in determining its structure, a novel strategy concerning the elegant addition of a small fraction of B species as an effective crystal growth mediator and a sacrificial agent is proposed to directly prepare diffraction-quality single crystals without disrupting the intrinsic elemental type. In the determined crystal structure, two monomeric primary building units (PBUs) self-assemble into a dimeric asymmetric secondary BU via strong Na+[BOND]O2− ionic bonds. The designed one-pot synthesis is straightforward, robust, and efficient, leading to a well-ordered (10ī)-parallel layered Si complex with its principal interlayers intercalated with extensive van der Waals gaps in spite of the presence of substantial Na+ counter-ions as a result of unique atomic arrangement in its structure. However, upon fast pyrolysis, followed by acid leaching, both complexes are converted into two SiO2 composites bearing BET surface areas of 163.3 and 254.7 m2 g−1 for the pyrolyzed intrinsic and B-assisted Si complexes, respectively. The transesterification methodology merely involving alcoholysis but without any hydrolysis side reaction is designed to have generalized applicability for use in synthesizing new layered metal–organic compounds with tailored PBUs and corresponding metal oxide particles with hierarchical porosity.United States. Defense Advanced Research Projects Agency (control No. 0471-1627)National Institute for Biomedical Imaging and Bioengineering (U.S.) (award No. EB-001960)National Institutes of Health (U.S.) (NIBIB award No. EB-002026)National Science Foundation (U.S.) (Grant No. CHE-0946721
    • 

    corecore