1,720,953 research outputs found
Emulsion templated scaffolds based on gelatin and glycosaminoglycans (Massimi: co-corresponding author)
No full textGelatin is one of the most commonly used biopolymer for creating cellular scaffolds due to its innocuous nature. To create stable gelatin scaffolds at physiological temperature (37 degrees C), chemical cross-linking is a necessary step. In a previous paper (Biomacromolecules 2006, 7, 3059-3068), cross-linking was carried out by either radical polymerization of the methacrylated derivative of gelatin (GMA) or through the formation of isopeptide bonds catalyzed by transglutaminase. The method of scaffold production was based on emulsion templating in which an organic phase is dispersed in the form of discrete droplets into a continuous aqueous solution of the biopolymer. Both kinds of scaffolds were tested as culture medium for hepatocytes. It turned out that the enzymatic cross-linked scaffold performed superiorily in this respect, even though it was mechanically less stable than the GMA scaffold. In the present paper, in an attempt to improve the biocompatibility of the GMA-based scaffold, biopolymers present in the extracellular matrix (ECM) were included in scaffold formulation, namely, chondroitin sulfate and hyaluronic acid. These biopolymers were derivatized with methacrylic moieties to undergo radical polymerization together with GMA. The morphology of the scaffolds was tuned to some extent by varying the volume fraction of the internal phase and to a larger extent by inducing a controlled destabilization of the precursor emulsion through the use of additives. In this way, scaffolds with 44% of the void volume attributable to voids with a diameter exceeding 60 microm and with 79% of the interconnect area attributable to interconnects with a diameter exceeding 20 microm in diameter could be successfully synthesized. To test whether the inclusion of ECM components into scaffold formulation resolves in an improvement of their biocompatibility with respect to GMA scaffolds, hepatocytes were seeded on both kinds of scaffolds and cell viability and function assays were carried out and compared
A biomimetic porous hydrogel of gelatin and glycosaminoglycans cross-linked with transglutaminase and its application in the culture of hepatocytes
No full textAbstract
The development of blended gelatin and glycosaminoglycan (GAG) scaffolds can potentially be used
in many soft tissue engineering applications since these scaffolds mimic the structure and biological
function of native extracellular matrix (ECM). In this study, we were able to obtain a gelatin-GAG by
using a concentrated emulsion templating technique known as high internal phase emulsion (HIPE), in which a prevailing in volume organic phase is dispersed in the form of discrete droplets inside an
aqueous solution of three biopolymers represented by gelatin, hyaluronic acid (HA) and chondroitin sulfate (CS) in the presence of a suitable surfactant. In order to preserve the bioactive potential of the biopolymers employed, the cross-linking procedure involved the use of transglutaminase (MTGase) that catalyses the formation of covalent N-ε-(γ-glutamyl) lysine amide bonds. Since both HA and CS do not posses the necessary primary amino groups towards which MTGase is active, they were functionalised with the dipeptide glycine-lysine (GK). In this way the introduction of foreign cross linking bridging units with an unpredictable biocompatibility was avoided.
These enzymatic cross-linked gelatin-GAG scaffolds were tested in the culture of primary rat and
C3A hepatocytes. Results underlined the good performance of this novel support in maintaining and
promoting hepatocyte functions in vitro
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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