1,720,978 research outputs found
Liposome-encapsulated motomycin C for reduction of corneal healing rate and ocular toxicity
No full textMitomycin-C (MMC), a potent antibiotic-antineoplastic drug, has recently proven to be useful as additional treatment in ocular surgery (pterygium, glaucoma filtering, photorefractive laser keratectomy, etc.) when inhibiting the epithelial wound healing response and reducing surgical scarring is beneficial to surgical success. However, the therapeutic benefits of MMC are frequently offset by ocular toxicity and undesirable side effects (retinal toxicity, corneal edema, corneal perforation, cataract, secondary glaucoma, iritis, scleral calcification, pain, etc.). The purpose of this study was to evaluate if a liposomal preparation containing MMC was capable of reducing the corneal healing rate and drug toxicity of a corneal lesion in a rabbit model. To do this, a liposomal formulation containing 0.2 mg/ml of MMC was prepared and tested against aqueous solutions and viscous formulations based on tamarind seeds polysaccharide (TSP), which were used as references. In vitro release of MMC from the vehicles through a dialysis membrane was characterized by a fast diffusion of MMC from the aqueous solution, while a more gradual release from the TSP and the liposomal formulations was observed. To evaluate the intraocular penetration of MMC, the drug amount in the aqueous and vitreous humor of the animals was determined 60 min after treatment. MMC toxicity was analyzed by monitoring the proliferation and viability of a rabbit corneal epithelial cell line (RCE) in the different formulations under study. These results showed reduced cytotoxicity for MMC in TSP viscous vehicles; however, only the liposomal MMC vehicle appeared to produce both lower toxicity for a rabbit corneal epithelial cell line (RCE) culture and a substantial reduction of the corneal healing rate in vivo
Cytotoxicity on rabbit corneal epithelial cell cultures of some polymers used as ophthalmic adjuvants
No full textIncreased corneal hydration induced by potential ocular penetration enhancers: assessment by differential scanning calorimetry (DSC) and by desiccation
No full textThe corneal toxicity of some surfactants of possible use as ocular penetration enhancers was investigated by measuring their effect on hydration of rabbit corneas 'in vitro'. The tested substances were benzalkonium chloride (BAC), cetylpyridinium chloride (CPC), ethylenediaminetetraacetic acid disodium salt (EDTA), polyoxyethylene-20-stearyl ether (Brij(R) 78, PSE). polyethoxylated castor oil (Cremophor(R) EL, PCO) and sodium deoxycholate (DC). Freshly excised corneas, mounted in perfusion cells, were kept in contact for 1 h with solutions of these agents; corneal hydration was then evaluated by measuring: (a) their total (free + bound) water content by desiccation (gravimetric analysis); and (b) their free water content by differential scanning calorimetry (DSC). The DSC measurements also provided a rough quantitative estimate of corneal solutes. All tested agents significantly influenced corneal hydration. evidently as a consequence of alteration of the corneal epithelium. Although a brief contact with the precorneal tissues 'in vivo' may not prove harmful, the use of these compounds as potential ocular permeation enhancers or otherwise as ingredients of topical ocular formulations for long-term use should be considered with caution
Liposome-encapsulated mitomycin-C for reduction of corneal healing rate and ocular toxicity.
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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
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
Appropriate 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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