1,720,969 research outputs found
Porous collagen scaffolds enable endothelial lumen formation in vitro under both static and dynamic growth conditions
No full textAbstract Despite recent advances in the field of tissue engineering, the development of complex tissue‐like structures in vitro is compromised by the lack of integration of a functioning vasculature. In this study, we propose a mesoscale three‐dimensional (3D) in vitro vascularized connective tissue model and demonstrate its feasibility to prompt the self‐assembly of endothelial cells into vessel‐like structures. Moreover, we investigate the effect of perfusion on the organization of the cells. For this purpose, primary endothelial cells (HUVECs) and a cell line of human foreskin fibroblasts are cultivated in ECM‐like matrices made up of freeze‐dried collagen scaffolds permeated with collagen type I hydrogel. A tailored bioreactor is designed to investigate the effect of perfusion on self‐organization of HUVECs. Immunofluorescent staining, two‐photon microscopy, second‐harmonic generation imaging, and scanning electron microscopy are applied to visualize the spatial arrangement of the cells. The analyses reveal the formation of hollow, vessel‐like structures of HUVECs in hydrogel‐permeated collagen scaffolds under both static and dynamic conditions. In conclusion, we demonstrate the feasibility of a 3D porous collagen scaffolding system that enables and maintains the self‐organization of HUVECs into vessel‐like structures independent of a dynamic flow
Numerical analysis of bioprinting-related shear stress and hydrostatic pressure during acoustic droplet ejection method versus microvalve-based technique and experimental investigation of their effects on epithelial and endothelial cells
No full textThe aim of this work was to explore the mechanobiological effects of the bioprinting process on cells. It was hypothesized that the bioprinting-induced mechanical signals affect the cellular behavior. To test this hypothesis, finite volume-based numerical simulation and experimental measurements were utilized. A custom-made pressure setup was used to examine the cellular response to hydrostatic pressure. Viability analysis, immunohistochemistry and qRT-PCR were used for experimental evaluation of cellular responses. Numerical simulation revealed that the maximum shear stress in acoustic droplet ejection is one third of the maximum wall shear stress in microvalve inkjet bioprinting. The impingement shear stress is in the same range as the nozzle wall shear stress. The viability analysis of cells after ejection from the microvalve confirmed that nozzle-to-platform distance is an additional parameter to be optimized for cell-friendly bioprinting. No change in cytoskeletal organization of actin filament, intermediate filament, focal adhesion and cell-cell contact were detected. However, in the case of stimulation with pulsatile hydrostatic pressure, a proinflammatory response of HUVECs was observed by an increase of interleukin 8 and a decrease of thrombomodulin transcripts. In a next step, the inflammatory response of the cells to bioprinting-induced shear stress should be further explored
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
Stem cell morphology controls the nuclear import of transcription factors within a bioengineered 3D niche
Full text linkLAUREA MAGISTRALENelle cellule staminali la morfologia controlla l'importo nucleare di fattori di trascrizione all'interno di una nicchia cellulare 3D ingegnerizzataSTEM CELL MORPHOLOGY CONTROLS THE NUCLEAR IMPORT OF TRANSCRIPTION FACTORS WITHIN A BIOENGINEERED 3D NICH
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
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