1,720,971 research outputs found
Hyaluronic acid based nanoparticles are suitable carriers to muscle cells: the ultrastructural evidence
No full textMyotonic dystrophies (DMs) are neuromuscular diseases of genetic origin that involve multiple organs and tissues, with particular emphasis on skeletal muscles. Although only palliative treatments are administered, some molecules (e.g. pentamidine) have been proven to be efficient in mitigating the pathological halmarks of DMs. Actually, the therapeutic application of these compounds is impaired by their low bioavailability and high toxicity. To overcome these limitations, polymeric hyaluronic-acid-based nanoparticles (HA-NPs) were developed as a therapeutic strategy to efficiently deliver pentamidine (PTM) to skeletal muscle cells [1]. Howerver, to obtain HA-NPs suitable for clinical applications, it is mandatory to elucidate their behaviors and interactions with the biological milieu. Electron microscopy represents a suitable tecnique able to characterize, localize and track the fate of NPs inside cells thanks to its high resolution [2]. Firstly, morphological analysis of HA-NPs and PTM-loaded NPs was carried out using trasmission electron microscopy (TEM) and Cryogenic transmission electron microscopy (CryoTEM). As shown in Fig. 1 (A,B), both HA-NPs and PTM-loaded NPs formed monodispersed populations of rounded shaped particles. Moreover, to precisely investigate NPs behaviour at the ultrastructural level, NPs must be unequivocally visualized. This is easily obtained for NPs containing electron dense components but it may be difficult for organic NPs having an intrinsic moderate electron density such as HA-NPs. A valid detection method to overcome this limitation is represented by the Alcian Blue (AB) staining, a long-estabilished histochemical technique [3]. In muscle cells treated with HA-NPs, the AB staining appeared as an irregular granular electron dense product found on weakly electron dense NPs (Fig.2) similar to those observed in cells processed for conventional ultrastructural morphology (Fig 3). Once HA-NPs were unequivocally identified, their internalization and trafficking were investigated by TEM. As shown in Fig. 3 (A,B), HA-NPs were internalized individually via endocytosis and localized throughout the cytoplasms, being never observed inside the cell nuclei. HA-NPs rapidly escaped endosomes occurring free in cytosol and, after 24 h, they formed large cluster. However, no organelle damage or alteration was ever observed. The results obtained underline the importance of transmission electron microscopy tecnique to investigate the behaviour of NPs inside cells and tissue, providing essential information on their actual spatial relationships with biological components
Novel applications of long-established histochemical techniques to study nanoparticle-cell interactions at transmission electron microscopy
Get PDFAlcian blue staining has been used to visualise nanoparticles at transmission electron microscop
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Alcian Blue Staining to Visualize Intracellular Hyaluronic Acid-Based Nanoparticles
No full textInvestigating at transmission electron microscopy the intracellular trafficking of hyaluronic acid-based nanoparticles remains a challenge due to their intrinsic weak electron density. Here we describe a simple protocol to stain hyaluronic acid that allows visualization of hyaluronic acid-based nanoparticles inside cells at both light and electron microscopy. By applying the critical-electrolyte-concentration Alcian blue method, these nanoparticles were observed as blue dots at bright-field microscopy or filled with fine electron dense precipitates at transmission electron microscopy
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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