1,720,959 research outputs found
Optimization of resveratrol nanoformulation and evaluation of its cytotoxicity on cochlear derived cells
No full textPurpose: The aim of the work is to develop resveratrol (RES)-loaded nanocarriers (NCs) intended for cochlear drug delivery. Furthermore, in vitro toxicity of the synthesized NCs is evaluated in cochlear cell lines.
Methods: RES-NCs are prepared by solvent-diffusion technique without surfactant. RES, PLGA and PCL-PEG di-block are mixed in different ratios, dissolved in acetone and added dropwise to aqueous phase under constant stirring (acetone/water ratio 1/20). RES-NCs are washed twice and freeze-dried. Box-Behnken design (BBD) is used to study the influence of formulation variables on Z-size, Polydispersity index (PDI), Zeta-potential, drug encapsulation efficiency (EE%) and ratio between Z-size before and after freeze-drying (S f/Si). To increase RES-NC stability during freeze-drying, lactose, mannitol, sucrose and trehalose are tested at different concentrations (1%, 5%, 10%, 15%, 20%w/v). Finally, MTS and LDH assays are carried out to check RES and Blank NCs in vitro toxicity after 24h incubation in an organ of Corti (HEI-OC1) and a stria vascularis
(SVK-1) cell lines.
Results: BBD model is validated since all experimental responses fit with predicted values. Checkpoint analyses (bias 500μM) and blank NCs (>800μg/mL) affect the cell viability.
Conclusion: RES-NCs are successfully synthesized and optimized by BBD. In addition, in vitro studies show that RES (<500μM) and blank NCs (< 800μg/mL) are non-toxic for HEI-OC1 and SVK-1 cells
Ferrocene-loaded nanocarrier as probe for cochlear biodistribution study
No full textPurpose: The fate of drug nanocarriers (NCs) in the inner ear remains elusive. The aim of the work is to develop ferrocene (FER)-loaded NCs to elucidate the cochlear biodistribution of such NCs.
Methods: FER-NCs were prepared by surfactant free solvent-diffusion technique using a mixture of PLGA/PCL-PEG (ratios 1/1, 1/2) dissolved in acetone. FER-NCs were washed and freeze-dried. TEM analyses were carried out to study the FER-NC morphology. Lactose, mannitol, sucrose were tested at different cryoprotectant/nanocarrier ratios (0/1, 1/1, 3/1, 5/1) to stabilize FER-NCs during freeze-drying. The stability of the FER-NCs was checked by measuring particle size and zeta potential (ZP) immediately after water dispersion and after 12 days. FER-NCs were placed in the round window (RW) niche of the middle ear in guinea pigs. After 48 hours, the animals were sacrificed, the cochlea isolated and prepared for TEM.
Results: The Ferrocene-loaded NCs had a mean diameter of 201.2±57.7, PDI of 0.328±0.074 and ZP of -20.2±4.8mV. PLGA/PCLPEG NCs of 1/2 allowed higher EE% (85.50±11.15) than ones made with 1/1 ratio (42.93±3.65). The FER-NCs appeared spherical with smooth surface. All cryoprotectants increased RES-NCs stability during the freeze-drying process. However, lactose, especially when used in 3/1 ratio, was more effective than other ones after dispersion and during 12-day stability studies. FER-NCs crossed the RW membrane and were found adjacent or in the cells lining the scala tympani of the cochlea. Hearing was normal after RW placement of NCs.
Conclusion: FER-NCs were successfully prepared by emulsion-diffusion technique and the 1/2 PLGA/PLC-PEG ratio was selected in term of best encapsulation efficiency. Moreover, lactose (3/1 cryoprotectant/NCs ratio) guaranteed FER-NCs stability during freeze-drying process and maintained FER-NCs stable in suspension for at least 12 days. When placed into the RW niche, FER-NCs enter the cochlea and do not appear to cause hearing loss
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
- …
