1,720,963 research outputs found
Estrazione di cellule staminali da cordone ombelicale e loro differenziamento in colangiociti
Full text linkAll acquired or congenital cholestatic diseases (primary biliary cirrhosis, sclerosing cholangitis, pediatric biliary atresia) represent one of major indications for liver transplantation. In the last 20 years new and innovative cell-based therapeutic strategies using post-natal multipotent stem cells have been characterised and proposed for hepatic surgery.
This work develops a research program aimed to identify and isolate adult stem cells from an easy and ethic approved source like Wharton jelly (CCO) for liver applications in particular for cholangiopathies. In perspective, CCO cells have been in vitro
stimulated with specific inducers in order to test their ability to differentiate into cholangiocyte-like cells.
By cytometrical analysis, the isolated fibroblastic populations have showed to be positive for stem cell markers like CD105, CD90, CD133 and negative for CD45, cKit, CD44 and HLA-DR. Although cell immunophenotype revealed to keep stable all over
subculturing, after 15 passages a significative percentage increase of CD133, CD44 and cKit positive cells has been observed. Similarly to stem cells defined as “migrating”, CCO populations expressed mRNAs for matrix metalloproteinases such as MMP2, MMP3. Moreover, they showed to respond to differentiative adipogenic, osteogenic and chondrogenic stimula until XV culture passage, as demonstrated by cytoplasmic lipid
droplets and expression of specific markers as perlecan, Runx-2, osteocalcin and osteopontin.
In order to evaluate the cholangiocyte differentiative potential of CCOs, it has been set on: a) 2D culture system based on unconditionated plates; b) 3D culture system for studying the in vitro tubulogenesis using a scaffold constituted of collagen type 1 and MatrigelTM (MATCO); c) MATCO coating-based culture system. After 7 days of stimulation, by immunofluorescence and cytometrical analysis, cells cultured in 2D system demonstrated the expression of typical cholangiocite markers as CK19 and
GGT-1. The MATCO matrix prepared as a coating layer showed to sustain the differentiaton of CCOs into cholangiocyte-like cells. Indeed, by RT-PCR study, the encapsulated cells into MATCO demonstrated to express only GGT-1 marker and, by
morphogenesis study, resulted not to be organized into tubular like structures. When induced and cultured on MATCO coating, CCOs showed similarities to cholangiocytes as demonstrated by the expression of mRNAs for GGT-1, CK19, MMP1, MMP2 and
aquaporin 1. No expression of ALB, INTβ4, HNF1B.
So, the present work demonstrated that, using a standadized procedure, it is possible to isolate from Wharton jelly a multipotent stem cell population, characterized by stable immunophenotype, long-term growth and responsivity to cholangiocyte differentiative stimulus on unconditioned plates or on matrix prepared with collagen type 1 and MatrigelTM. The in vivo study using a biliary damage model will permit to evaluate the real differentiative potential of CCO populations.Le malattie colestatiche croniche congenite o acquisite (cirrosi biliare primitiva, colangite sclerosante, atresia pediatrica delle vie biliari) rappresentano nel loro insieme una delle principali indicazioni al trapianto di fegato. Nell’ultimo ventennio, nuove ed
innovative strategie terapeutiche basate sull’impiego di cellule staminali adulte, ovvero cellule staminali multipotenti identificate in tessuti diversi dell’organismo in età postnatale, sono state caratterizzate e proposte in chirurgia epatica.
Tale ricerca si inserisce in un programma di studio che in campo epatologico mira all’identificazione di popolazioni cellulari staminali adulte (CCO), che, isolate da una fonte di facile accesso ed eticamente approvata quale la gelatina di Wharton., possono rappresentare candidati ideali per la terapia cellulare delle colangiopatie. In tale prospettiva, le popolazioni cellulari CCO sono state stimolate in vitro con fattori induttivi per testare la loro capacità di differenziare in cellule simil colangiociti.
All’analisi di citofluorimetria, le popolazioni fibroblastoidi ottenute hanno mostrato positività all’espressione di marcatori di staminalità quali CD105, CD90, CD133 e negatività alla presenza di CD45, cKit, CD44 e HLA-DR. Sebbene l’immunofenotipo si sia mantenuto stabile nel corso delle subcolture, è stato osservato, dopo 15 passaggi, un significativo aumento percentuale di cellule positive per i marcatori CD133, CD44 e cKit. Similmente alle popolazioni cellulari staminali definite “migranti”, le popolazioni CCO presentano mRNA specifici per le metalloproteinasi di matrice quali MMP2 e MMP3 e rispondono agli stimoli differenziativi in senso adipogenico, osteogenico e condrogenico fino alla subcoltura XV, come dimostrato dai tipici accumuli lipidici citoplasmatici e dall’espressione di specifici marcatori quali il perlecano, Runx-2,
osteocalcina ed osteopontina.
Per valutare il grado di potenzialità differenziativa colangiocitaria sono stati allestiti a) un sistema di coltura bidimensionale per semina su piastre di polistirene non condizionate, b) un sistema di coltura tridimensionale per lo studio della tubulogenesi in vitro mediante incapsulazione delle cellule in una matrice di collagene 1 e Matrigel (MATCO), c) un sistema di coltura su coating di matrice MATCO. Dopo 7 giorni di stimolazione, le cellule coltivate nel sistema bidimensionale hanno dimostrato, all’analisi di immunofluorescenza e di citofluorimetria, l’espressione di marcatori tipici di linea colangiocitaria quali CK19 e GGT-1. La matrice MATCO si è dimostrata adatta a sostenere il differenziamento delle cellule CCO in senso simil-colangiocitario solo nella forma di substrato. Infatti, all’analisi d’espressione mediante RT-PCR le cellule incapsulate in MATCO hanno dimostrato dopo trattamento induttivo la sola espressione di RNA messaggero per il marcatore GGT-1 e, all’analisi di morfogenesi, non hanno evidenziato alcuna organizzazione simil tubulare. Le cellule CCO differenziate su coating MATCO hanno acquisito caratteristiche simili a quelle dei colangiociti come dimostrato dall’espressione di mRNA per i marcatori GGT-1, CK19, MMP1, MMP2 e acquaporina 1. Non è stata osservata l’espressione di marcatori quali ALB, INTb4 e fattore HNF1B.
Dal presente studio è quindi emerso che, mediante una procedura standardizzata, è possibile isolare da gelatina di Wharton una popolazione cellulare staminale multipotente, dotata di caratteristiche immunofenotipiche stabili, potenziale di crescita a lungo termine in vitro e capace di rispondere allo stimolo differenziativo colangiocitario su piastre di polistirene condizionate o meno con una matrice di collagene 1 e matrigel.
L’impianto in vivo in un modello animale di danno biliare consentirà la valutazione del reale potenziale differenziativo delle popolazioni CCO
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
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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