1,720,963 research outputs found
Strategies for engineering vascularized islet organoids using human induced pluripotent stem cells and microfluidic organoid-on-chip technologies
No full textLe diabète sucré est une maladie chronique qui touche 61 millions de personnes vivant en Europe, soit 1 adulte sur 11. Dans le diabète de type 1, une destruction auto-immune des cellules bêta productrices d’insuline conduit à une hyperglycémie. Le seul traitement des patients consiste en des injections pluri quotidiennes d’insuline afin de contrôler leur taux de glucose dans le sang, sans les guérir. Ces patients ont désespérément besoin d'un traitement durable, qui leur permettent d’améliorer leur qualité de vie. Une possibilité concerne la transplantation d'îlots pancréatiques provenant d’un donneur en état de mort cérébrale, permettant ainsi de rétablir le contrôle de la glycémie normale. Il existe plusieurs limites à cette thérapie cellulaire de remplacement, dont le nombre de patients diabétiques qui est bien supérieur au nombre de donneurs. Ainsi, une nouvelle source de cellules bêta est nécessaire pour que la transplantation puisse être disponible pour tous les patients. Les cellules souches ont le potentiel de fournir une source illimitée de nouvelles cellules productrices d'insuline. Plusieurs équipes ont obtenus ces cellules avec succès dans une boîte de Pétri en exposant les cellules souches à une succession de combinaisons de molécules qui imitent le développement du pancréas humain. Cependant, comme ces cellules sont cultivées dans une boîte de Pétri, elles sont dépourvues du micro environnement pancréatique qui joue un rôle important pendant leur développement. L'objectif de ma thèse est de produire des cellules bêta dérivées de cellules souches pluripotentes induites (CSPi) humaines et de leur fournir un micro environnement et une vascularisation humains. Pour y parvenir, nous avons d'abord utilisé un modèle d'organoïdes-sur-puce qui imite les caractéristiques clés du micro environnement du pancréas natif. Dans une puce microfluidique perfusable, les îlots seront vascularisés via des cellules endothéliales et perfusés assurant ainsi un meilleur apport en oxygène et en nutriments. Nous avons démontré la biocompatibilité de notre plateforme microfluidique qui a permis de vasculariser des organoïdes de cellules bêta dérivées de CSPi avec une perfusion continue du milieu à un débit contrôlé et un micro environnement avec un hydrogel de soutien enrichi de fibroblastes et de cellules endothéliales. Dans la seconde stratégie, nous avons fusionné et vascularisé des organoïdes d'îlots et de vaisseaux sanguins dérivés de CSPi pour améliorer la réponse à l'insuline au fil du temps. Nous avons montré que la co-culture d'organoïdes d'îlots et de vaisseaux sanguins a un effet positif sur la fonctionnalité des îlots et maintient la réactivité au glucose des cellules bêta pendant une culture prolongée. Dans l'ensemble, cette étude explore de nouvelles stratégies in vitro pour la vascularisation des îlots en utilisant les technologies des organoïdes-sur-puce et des cellules souches pluripotentes induites humaines, ouvrant la voie à leur utilisation future dans la médecine personnalisée et régénérative.Diabetes mellitus is a chronic disease affecting 61 million people living in Europe, or 1 in 11 adults. In type 1 diabetes an autoimmune mediated destruction of insulin-producing beta cells leads to hyperglycemia. The only treatment for patients consists of multiple daily insulin injections to control their blood glucose level, without curing them. These patients are in desperate need of long-lasting treatment that will improve their quality of life. One possibility is the transplantation of pancreatic islets from a brain-dead donor, thereby restoring control of the normal blood sugar. There are several limitations to this cell replacement therapy, including the number of diabetic patients which is much higher than the number of donors. Thus, a new source of beta cells is needed so that transplantation can be available to all patients. Stem cells have the potential to provide an unlimited source of new insulin-producing cells. Several teams have successfully obtained these cells in a Petri dish by exposing the stem cells to a succession of different molecule combinations that mimic the development of the human pancreas. However, since these cells are grown in a petri dish, they lack the pancreatic microenvironment that plays an important role during their development. The aim of my thesis is to produce beta cells derived from human induced pluripotent stem cells (hiPSC) and provide them with a human microenvironment and vascularization. To achieve this, first we used an organoid-on-a-chip model that mimics key features of the native pancreas microenvironment: islet vascularization by endothelial cells for improved oxygen and nutrient delivery in a perfusable microfluidic chip. We showed biocompatibility of our microfluidic platform that demonstrated possibility to vascularize hiPSC-derived beta cell organoids with continuous media perfusion at controlled flow rate and microenvironment with supporting hydrogel enriched with fibroblasts and endothelial cell. In the second strategy, we have fused and vascularized islets and blood vessel organoids derived from hiPSC for improved insulin response over time. We have shown that islet and blood vessel organoid co-culture has a positive effect on islet functionality with maintained beta cell glucose responsiveness over prolonged culture. Overall, this study explores novel in vitro strategies for islet vascularization using organoid-on-a-chip and human induced pluripotent stem cell technologies, opening the path for their future use in personalized and regenerative medicine
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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