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Caratterizzazione e plasticità differenziativa di popolazioni cellulari staminali isolate da sangue periferico
Get PDFStem cells are primitive undifferentiated cells with unlimited proliferative capacity and defined differentiative abilities under specific stimula. Over the last decade, great interest has been addressed versus the clinical use of adult stem cells that, in comparison to embryonic stem cells, do not involve the destruction of embryos to be obtained and therefore do not induce any ethical problem. Adult stem cells are mostly multipotent and are present within niches in adipose tissue, bone marrow and skin of adults and children. Experimental studies have shown that multipotent stem cells are present in animal and human peripheral blood and their potentialities make them ideal candidate for clinical programs of cell therapy to restore structural or functional tissue defects that are difficult to be solved with traditional medical therapies.
It was also shown that, using in vitro defined culture conditions, they can be modified acquiring cardiomyocyte phenotype. After 24h exposure with DNA demethylating chemical 5-azacitidine (5-AZA), the commonest strategy to induce the in vitro cardiac differentiation, MSC demonstrated a cardiomyocyte-like ultrastructure, including typical sarcomeres, a centrally positioned nucleus and atrial granules. The expression of contractile protein genes for myosin heavy chain, myosin light chain and α-actin, confirmed them to be similar to the foetal ventricular cardiomyocytes.
In the last decade, the development of the heart valve tissue engineering provided promises to obtain fully compatible grafts able, after transplantation, to be in vivo remodelled. Researchers have demonstrated the efficacy of acellular and natural matrices to repair muscle, bone and trachea. Some of the most widely used techniques have involved detergents such as sodium dodecylsulphate (SDS), sodium deoxycholate (SD), sodium cholate (SC), Triton X–100 (TX) and trypsin enzyme. TRICOL, a technique employing TX, sodium cholate (SC), hypo- and hyper-tonic solutions and Benzonase has been developed by Spina et al. to obtain porcine aortic and pulmonary valves. Acellular matrices have been tested in combination or not with differentiated tissue-specific cells (endothelial and/or smooth muscle cells), autologous or allogenic stem cells. Seeding peripheral blood-derived autologous cells on acellular matrices could optimize the in vivo functionality of the implant to its final complete integration.
The aim of this thesis has been the isolation of circulating cells from peripheral blood to be used in tissue engineering strategies. The study envolved minipig as animal model. CD44high, CD106+, CD90low, SLA-DRlow, CD45-, CD34-, CXCR4- (CSP) fibroblastic cells have been isolated using the strategy by adherence to plastic. The long term expansion has been performed for 39 passages and demonstrated that CSP phenotype and morphology are highly stable, as cytometrical study and microscopical analysis demonstrated on subcultures VIII, XXIV and XXXIX. Moreover, the specific induction with adipogenic, osteogenic and cardiomyogenic media revealed that CSP cells are able to specifically respond to the induction stimula, accumulating lipids within cytoplasm, producing mineralized extracellular matrix and expressing cardiomyogenic markers such as phospholamban, alpha actin muscle specific and troponin T. In order to test the clinical potentialities of CD44high, CD106+, CD90low, SLA-DRlow, CD45-, CD34-, CXCR4- circulating cells, in cardiological field, the seeding of CSP cells has been performed on acellular porcine valves (VD) (aortic and pulmonary) as scaffolds. The cellular adhesion has been studied by SEM at different time points (7, 14, 28, 35 and 42 days). The morphological study by SEM demonstrated that CSP cells colonized the seeding surface and organized themselves into continuous monolayers. The histological study by immunofluorescence showed the presence of elastin and collagen (IV and I) whereas immunohystochemistry demonstrated the positivity of cells for alpha actin.Le cellule staminali sono cellule primitive indifferenziate, dotate di capacità proliferativa illimitata e in grado di differenziare in cellule specializzate in presenza di stimoli specifici. Nell’ultimo decennio, grande interesse è stato rivolto all’impiego in campo medico di cellule staminali adulte che, rispetto alle cellule staminali embrionali totipotenti, non comportano la distruzione dell’embrione per il loro ottenimento e pertanto non sollevano alcun problema di carattere etico. Le cellule staminali adulte sono cellule prevalentemente multipotenti, identificate in nicchie a livello del tessuto adiposo, del midollo osseo e della cute di individui adulti e bambini. Studi sperimentali hanno evidenziato che nel sangue periferico animale e umano sono presenti cellule ad alta capacità plastica e che dunque potrebbero essere utilizzate in clinica per lo sviluppo di programmi di terapia cellulare ed il recupero di danni tessutali refrattari alle terapie mediche classiche. Le cellule staminali mesenchimali (MSC) hanno dimostrato di essere idonee all’impiego in vivo per lo sviluppo di programmi di terapia cellulare.
È stato inoltre dimostrato che, in definite condizioni di coltura, le cellule MSC possono acquisire un fenotipo simil-cardiomiocitario. La strategia più comune utilizzata per indurre il loro differenziamento cardiomiogenico in vitro è il trattamento per 24 ore con la 5-azacitidina (5-AZA), un agente chimico demetilante del DNA. Dopo induzione, le cellule mostrano una morfologia miotubulare, caratterizzata dalla presenza di unità sarcomeriche, un nucleo centrale e tipici granuli atriali. Similmente ai cardiomiociti fetali ventricolari, esse esprimono proteine contrattili, quali l’α-actina, la catena pesante (MHC) e leggera della miosina (MLC). Nel corso degli ultimi dieci anni, lo sviluppo dell’ingegneria tessutale delle valvole cardiache ha aperto un nuovo orizzonte verso l’utilizzo di un costrutto biocompatibile in grado di essere rimodellato dopo l’impianto. Numerosi studi hanno messo in luce l’efficacia delle matrici naturali acellulari per il recupero di danni tessutali a livello muscolare, osseo e tracheale. I metodi sperimentati per la decellularizzazione di valvole aortiche e polmonari hanno previsto l’uso di detergenti quali il sodio dodecilsolfato (SDS), il sodio deossicolato (SD), il sodio colato (SC), il Triton X–100 (TX) e l’enzima tripsina. Il trattamento TRICOL, che comprende l’uso di TX, sodio colato (SC), soluzioni ipo- ed iper-toniche e Benzonase, è stato sviluppato da Spina e collaboratori per la preparazione di valvole porcine aortiche e polmonari. L’ingegnerizzazione della matrice con cellule autologhe isolate da sangue periferico potrebbe ottimizzare l’attecchimento dell’impianto e consentire il suo mantenimento in sede fino a completa integrazione. Lo scopo della tesi è stato isolare cellule circolanti multipotenti da sangue periferico, idonee ad applicazioni di ingegneria tessutale. Lo studio è stato eseguito utilizzando il modello animale minipig. Sono state isolate popolazioni fibroblastoidi mediante la tecnica di adesione alla plastica, aventi fenotipo CD44high, CD106+, CD90low, SLA-DRlow, CD45-, CD34-, CXCR4- (CSP). L’espansione a lungo termine, eseguita per 39 passaggi, ha dimostrato che le popolazioni CSP sono altamente stabili da un punto di vista fenotipico e morfologico, come dimostrato mediante analisi citometrica e di microscopia ottica su subcolture intermedie VIII, XXIV e XXXIX. Inoltre, la specifica induzione con terreni differenziativi in senso adipogenico, osteogenico e cardiomiogenico ha dimostrato che le cellule CSP sono cellule plastiche, che rispondono agli stimoli in modo specifico accumulando trigliceridi, producendo matrice extracellulare mineralizzata ed esprimendo marcatori cardiomiogenici quali il fosfolambano, l’alfa-actina muscolo specifica e la troponina cardiaca T. Allo scopo di valutare le potenzialità di impiego in campo cardiologico di popolazioni circolanti con immunofenotipo CD44high, CD106+, CD90low, SLA-DRlow, CD45-, CD34-, CXCR4-, è stata oggetto di studio la crescita delle cellule CSP su matrici valvolari decellularizzate (VD) aortiche e polmonari. La valutazione dell’adesione è stata eseguita mediante analisi SEM a differenti intervalli di tempo (7, 14, 28, 35 e 42 giorni). Lo studio morfologico mediante analisi SEM ha dimostrato la colonizzazione della superficie di semina da parte delle cellule CSP e la loro organizzazione in monostrati continui. Lo studio istologico mediante immunofluorescenza ha evidenziato sui campioni la presenza di elastina e di collagene (IV e I) mentre lo studio immunoistochimico ha dimostrato la positività delle cellule per l’alfa-actina cellulare scheletrica
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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