1,720,989 research outputs found
Chitosans as new tools against biofilms formation on the surface of silicone urinary catheters
No full textUrinary catheters contamination by microorganisms is a major cause of hospital acquired infections and represents a limitation for long-term use. In this work, biofilms of Klebsiella pneumoniae and Escherichia coli clinical isolates were developed on urinary catheters for 48 and 72 h in artificial urine medium (AUM) with different molecular weight chitosans (AUM-CS solutions) at pH 5.0. The number of viable bacteria was determined by standard plate count agar while crystal violet (CV) staining was carried out to assess biomass production (optical density at 570 nm) in the mentioned conditions. Re-growth of each strain was also evaluated after 24 h re-incubation of the treated catheters. Significant decreases of log CFU/catheter and biomass production were observed for all the biofilms developed in AUM-CS compared with the controls in AUM. The percentages of biofilm removal were slightly higher for E. coli biofilms (up to 90.4%) than those of K. pneumoniae (89.7%); in most cases, the complete inhibition of bacterial re-growth on treated catheter pieces was observed. Contact time influenced chitosan efficacy rather than its molecular weight or the biofilms age. The results confirmed the potentiality of chitosans as a biomacromolecule tool to contrast biofilm formation and reduce bacterial re-growth on urinary catheters
PEG-Lipid core micelles with pH responsiveness for tumor cell targeting
No full textIn the latest years, investigations have been performed to develop smart stimuli responsive drug delivery systems. These systems are intended to move through the body in a dormant state but can selectively respond to physiopathological environmental changes. These systems can be exploited for ameliorating cell targeting or for controlled drug release in specific body districts [1]. Typically, solid tumours present lower pH, higher temperature, peculiar enzymatic pool and higher redox potential as compared to normal tissues. Therefore, these physiopathological stimuli can promote surface or macroscopic alterations of nanocarriers chemically constructed to sense the stimulus. This may result in exposition of the targeting moieties, improved cellular association or activation of drug release.
Here we report the synthesis and characterization of a new stimulus responsive supramolecular system based on the pH sensitive amphiphilic unimer stearoyl-PEG-poly-sulfadimethoxine (stearoyl-PEG-(SDM)7). Sulfadimethoxine (SDM) was chosen for its ionic character (pKa = 6.1) which allows for pH induced hydrophobic/hydrophilic switching [2]
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mesenchymal Stem Cell Membrane-Coated TPCS2a-Loaded Nanoparticles for Breast Cancer Photodynamic Therapy
Full text linkDespite substantial improvements in breast cancer (BC) treatment there is still an urgent need to find alternative treatment options to improve the outcomes for patients with advanced-stage disease. Photodynamic therapy (PDT) is gaining a lot of attention as a BC therapeutic option because of its selectivity and low off-target effects. However, the hydrophobicity of photosensitizers (PSs) impairs their solubility and limits the circulation in the bloodstream, thus representing a major challenge. The use of polymeric nanoparticles (NPs) to encapsulate the PS may represent a valuable strategy to overcome these issues. Herein, we developed a novel biomimetic PDT nanoplatform (NPs) based on a polymeric core of poly(lactic-co-glycolic)acid (PLGA) loaded with the PS meso-tetraphenylchlorin disulfonate (TPCS2a). TPCS2a@NPs of 98.89 ± 18.56 nm with an encapsulation efficiency percentage (EE%) of 81.9 ± 7.92% were obtained and coated with mesenchymal stem cells-derived plasma membranes (mMSCs) (mMSC-TPCS2a@NPs, size of 139.31 ± 12.94 nm). The mMSC coating armed NPs with biomimetic features to impart long circulation times and tumor-homing capabilities. In vitro, biomimetic mMSC-TPCS2a@NPs showed a decrease in macrophage uptake of 54% to 70%, depending on the conditions applied, as compared to uncoated TPCS2a@NPs. Both NP formulations efficiently accumulated in MCF7 and MDA-MB-231 BC cells, while the uptake was significantly lower in normal breast epithelial MCF10A cells with respect to tumor cells. Moreover, encapsulation of TPCS2a in mMSC-TPCS2a@NPs effectively prevents its aggregation, ensuring efficient singlet oxygen (1O2) production after red light irradiation, which resulted in a considerable in vitro anticancer effect in both BC cell monolayers (IC50 < 0.15 μM) and three-dimensional spheroids
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Gold nanoparticles with triggerable biorecognition for enhanced tumour specificity.
No full textIn latest years colloidal gold systems decorated with biological molecules and polymers have been developed as a platform for drug and gene delivery, for diagnostic and other biomedical applications. Gold nanopaprticles are particularly interesting because of the Surface Plasmon Absorption (SPA) properties, which allows for localized heating by laser irradiation. They are devoid of targeting properties that must be conferred by surface functionalization. Indeed, gold nanoparticles can be coated with a variety of functional modifiers: polymers, environmentally-sensitive and targeting agents which allow obtaining versatile systems. Previous studies showed that decoration of gold nanoparticles with thermosensitive polymers allow for temperature controlled cellular penetration [1]. Here we report the preparation of a “smart” system by decorating gold nanoparticles with thermo-responsive polymers and folic acid to achieve temperature triggered biorecognition of folate receptor overexpressing tumor cells. This is aimed to improve site selectivity in the tumor compartment where a physiopathologic temperature increase is found [2]
Tumour cells active targeting by gold nanoparticles with temperature controlled biorecognition properties.
No full textAppropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Thermosensitive Decorated Gold Nanoparticles For Thermal Triggered Biological Recognition.
No full textGold nanoparticles decorated with thermosensitive polymers reversibly switched from stable colloidal dispersion to a self-associated state by temperature changes. Above the polymer LCST, the coated nanoparticles were taken into human MCF7 cells at a higher extent compared to what was observed at 34 °C. The laser irradiation of the intracellular nanoparticle clusters induced cell damage
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