1,720,984 research outputs found
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
Lipid-based microparticles for TB inhaled therapy: physical properties and cell internalization
No full textTuberculosis (TB) disease is caused by Mycobacterium tuberculosis that survives and replicates within human alveolar macrophages and is characterized by a long chronic stage of infection and progressive pathology mainly compromising (90% of cases) the respiratory system. Current TB therapies have exploited conventional routes of administration, such as oral or intramuscular, based on high and frequent dosages to maintain the drug therapeutic concentration in infection site because of poor drug permeability, poor drug bioavailability and pre-systemic clearance. An alternative acceptable therapy to systemic treatments involves inhalation route delivering the drug directly to the desired site, enabling a rapid onset of the action and avoiding the long period of the current treatment and the first-pass metabolism, as well as the use of high doses of drug resulting in drug resistance onset and in severe side effects on other organs. Inhaled TB therapy can presuppose the development of micro- or nanoparticles acting as drug carriers toward the alveolar region in the deepest lung so inducing the endocytosis process of alveolar macrophages being many antimicrobials difficult to cross cell membranes (1-3). Lipid-based particulate systems have been poorly investigated for TB inhaled therapy (4) though they were generally recognized as safe, poor liable to swell upon contact with the moisture located into the lungs and, consequently, to release the drug before the target site. Among the lipid-based particulate systems, Solid Lipid Microparticles (SLM), constituted by a solid lipid core stabilized by a surfactant at the surface, exhibit several favourable properties as production without organic solvents and long-term stability.
In the present study, SLM loaded with rifampicin, a first-line anti-TB drug, were developed by the melt emulsification technique and evaluated in a perspective of an inhaled therapy for the treatment of TB infection. The lipid-based microparticles designed as rifampicin carrier showed features proper to be delivered from a DPI device, to deposit onto alveolar epithelium and to be internalized by macrophages in which Mycobacterium tuberculosis resides
Development and in vitro characterization of SLN encapsulating magnetic Heparin coated Iron Oxide for theranostic application
No full textSolid Lipid Nanoparticles (SLN) have been proposed for the oral delivery of drugs with poor oral bioavailability for their ability to be internalized directly by the lymphatic circulation, like chylomicrons, through intestinal absorption. Lymphatic system is considered an interesting target for anti-cancer drugs and contrast agents because exerts an active role in the cancer metastasis being the major route of the solid tumor spread. Recently, according to the potentiality of the iron oxide in diagnostic and of heparin in the cancer therapy, iron oxide nanoparticles non-covalently coated with heparin (Fe@hepa) have been proposed as delivery systems for theranostic application (1). The aim of this work was to encapsulateFe@hepa in a biocompatible solid lipid shell in order to obtain a nanotheranostic tool for promoting the oral absorption through the lymphatic route. SLN have been formulated by a modified self nanoemulsifying technique by using Gelucire50/13 and GeleolTM. The resulted Fe@hepa-SLN were characterized regarding size, morphology, storage stability as well in vitro release of heparin and iron oxide. In addition, preliminary studies on Caco-2 cell line were carried out evaluating cytotoxicity by MTT tests and internalization by the direct quantification of Fe@hepa inside the cells. Fe@hepa-SLN displayed a mean diameter below 300 nm, suitable for the oral administration, and an incorporation efficiency of 75% ± 3.9. Morphology analyisis showed the lipid shell surrounding the Fe@hepa nanoparticles and the release studies demonstrated that this lipid envelop stabilized the heparin coating in physiological conditions. Finally, studies on Caco2 cells showed the low cytotoxicity of the Fe@hepa-SLN and their ability to be internalized in the cells used as intestinal permeability model. These results indicate that this novel nanotechnology strategy could be a promising tool for oral nanotheranostic approaches
Inhalated drug delivery systems to target alveolar macrophages for tuberculosis therapy: design of safe SLM loaded with rifampicin
No full textThe present research aimed to improve the effectiveness of TB treatment by a non conventional therapy and using teh respiratory tract as a novel adminictration route for rifampicin. The study dealt with the design of Solid Lipid Microparticles (SLM) to be delivered by a Dry Powder Inhaler (DPI) device and to target the alveolar macrophages. The negligible in vitro drug release indicated the capacity of the matrix to firmly entrap the drug. Rifampicin maintained its biological activity during the preparation steps. Moreover, SLM were suitable to be taken up by murine J774 cells
Anti-TB inhalation therapy: Design of mannose-based functionalised Solid Lipid Microparticles for an active targeting to alveolar macrophages
No full textHuman tuberculosis (TB) is mainly a disease of the lung characterised by a long chronic stage of infection and progressive pathology that compromise the respiratory system. This is a curable infectious bacterial disease caused by the Mycobacterium tuberculosis (Mtb). TB therapies have exploited conventional routes of administration, such as oral and intramuscular1. The pulmonary route appears the most reasonable and effective way to target the alveolar macrophages (AM) and eradicate surviving Mtb at the primary infected site of TB, especially considering that 75-80% of cases remain localised in the lungs. The anti-TB therapy by inhalation offers benefits compared with the current treatment in terms of patient’s compliance improvement, reduction in dose amount and frequency, treatment duration and TB diffusion in other organs, thus minimising the risk of drug-resistant mutants, toxicity and side effects.
For a direct intramacrophagic antitubercular therapy using Dry Powder Inhaler (DPI) devices, Solid Lipid Microparticles (SLM), produced using the melt emulsifying technique followed by freeze-drying, were developed to load rifampicin, a first-line antitubercular drug.
In the present project, SLM were modified to improve drug loading level and release as well as AM targeting. Several biocompatible lipid components such as fatty acids and their derivatives, diglycerides and triglycerides, were processed using mixtures of biocompatible stabilisers (sodium taurocholate and methyl mannopyranoside) in order to obtain SLM with maximum efficiency in terms of drug loading and release in simulated lung fluid. Lipids in the liquid physical state embedded into SLM provided Microstructured Lipid Carriers (MLC) that are known to exhibit superior advantages over SLM such as enhanced drug loading capacity and prevention of drug expulsion intended to maximise the drug concentration at the primary site of TB infection. The obtained microcarriers were examined for their intrinsic properties such as size and size distribution, morphology and shape, surface charge, bulk and tap density, aerodynamic diameter, physical state of the components, wettability, drug loading and release.
Macrophages, as is common knowledge, possess mannose-specific membrane receptors (MR) that can be recognised by carriers bearing mannose residues, facilitating their internalisation 2, 3.
Therefore, the functionalisation of SLM surface by mannose derivatives used as the co- stabiliser in the SLM formulation was used to achieve an active targeting. The actual presence of mannose on SLM surface was investigated by means of X-ray Photoelectron Spectroscopy for Chemical Analysis (XPS) and Energy Dispersive X-ray Analysis (EDX)
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