1,721,020 research outputs found
Stability and bifurcation problems
No full textThis contribution is devoted to some problems on stability, observability and bifurcation in mechanics and their applications: the direct Lyapunov’s method; one-parameter families of Lyapunov’s functions, (theory and applications); stability and Andronov-Hopf bifurcation; total stability and observability
Sertoli cell-secreted factors have promyogenic and antifibrotic properties on human DMD myoblasts with different mutations.
No full textDuchenne muscular dystrophy (DMD) is a recessive X-linked lethal disease affecting one over 5,000 live male births in which mutations in the dystrophin gene (DMD) lead to lack of a functional protein resulting in susceptibility of myofibers to rupture during contraction. Muscles of DMD patients or experimental models of DMD show progressive necrosis of the myofibers, chronic inflammation and reactive regeneration, which lead to exhaustion of muscle precursor cell pool and replacement of myofibers with fibrous and fatty tissues.1 Although multiple therapeutic approaches have been explored in the last decades and are still under investigation, the standard therapy to DMD remains the use of glucocorticoids despite their limited efficacy and undesired side effects.2 We set up a preclinical approach based on the peculiar properties of Sertoli cells (SeC)3,4 a cell type of the seminiferous tubules of the testis in which they favor the maturation of developing germ cells and protect them against the host immune system. Besides creating a physical barrier (the blood-testis barrier), SeC secrete a plethora of trophic and immunomodulatory factors that confer to these cells the ability to survive long time after engraftment, and protect allo- and xenogenic engraftments of tissues and organs.5 SeC isolated from specific pathogens free (SPF) pre-pubertal pigs were encapsulated in highly biocompatible alginate-based microcapsules (MC-SeC) and injected into the peritoneal cavity of mdx mice, an experimental model of DMD, in the absence of pharmacological immunosuppression.3,4A single i.p. injection of MC-SeC resulted in amelioration of muscle morphology and performance as a consequence of the secretion by SeC of anti-inflammatory factors and heregulin β1, an inducer of the dystrophin paralogue, utrophin, opening new routes in the treatment of DMD. However, information is lacking about possible direct effects of SeC on myoblasts/myotubes. Here, we show that SeC secrete factors able to stimulate cell proliferation in the early phase of the myogenic differentiation process in murine C2C12 and human (healthy and DMD) myoblasts. In DMD myoblasts, SeC-derived factors delayed the expression of the muscle-specific terminal differentiation markers, myogenin and myosin heavy chain (MyHC)-II in the early phase (24h) of the differentiation process; nevertheless, SeC stimulated terminal differentiation (6 days) in these cells, suggesting that the promitogenic activity of SeC does not affect the myogenic potential. Moreover, SeC inhibit the expression of the myofibroblast transdifferentiation markers, COL1A1, FN1 and CTGF/CCN2 in DMD myoblasts, suggesting an antifibrotic effect of the SeC-derived factors. Finally, SeC induced utrophin expression in preformed DMD myotubes regardless of the mutation, with the same mechanism reported in dystrophic mice. Altogether, these results further support the use of MC-SeC or SeC-derived factors in the treatment of DMD patients, and suggest that SeC-based approaches might be useful also in improving the early phase of muscle regeneration, during which myoblasts have to proliferate in order to reach the critical amount required to replace the damaged muscle mass.
Keywords: Duchenne muscular dystrophy; Sertoli cell; muscle differentiation; fibrosis.
References
1. Davies KE, Nowak KJ. Molecular mechanisms of muscular dystrophies: old and new players. Nat Rev Mol Cell Biol. 2006;10:762-73. doi: 10.1038/nrm 2024
2. Muntoni F, Fisher I, Morgan, JE, Abraham D. Steroids in Duchenne muscular dystrophy: from clinical trials to genomic research. Neuromuscul. Disord. 2002;1:S162-5. doi: 10.1016/s0960-8966 (02)00101-3
3. Chiappalupi S, Luca G, Mancuso F, Madaro L, Fallarino F, Nicoletti C, Calvitti M, Arato I, Falabella F, Salvadori L, Di Meo A, Bufalari A, Giovagnoli S, Calafiore R, Donato R, Sorci G. Intraperitoneal injection of microencapsulated Sertoli cells restores muscle morphology and performance in dystrophic mice. Biomaterials. 2016;75:313-26. doi:10.1016/j.biomaterials. 2015. 10.029
4. Chiappalupi S, Luca G, Mancuso F, Madaro L, Fallarino F, Nicoletti C, Calvitti M, Arato I, Falabella F, Salvadori L, Di Meo A, Bufalari A, Giovagnoli S, Calafiore R, Donato R, Sorci G. Effects of intraperitoneal injection of microencapsulated Sertoli cells on chronic and presymptomatic dystrophic mice. Data in Brief. 2015;5:1015-21. doi:10.1016/j.dib.2015.11.016
5. Chiappalupi S, Salvadori L, Luca G, Riuzzi F, Calafiore R, Donato R, Sorci G. Do porcine Sertoli cells represent an opportunity for Duchenne muscular dystrophy? Cell Proliferation. 2019;26:e12599; doi: 10.1111/cpr.12599
Infezioni profonde del collo: una realtà oggi da non sottovalutare. Analisi retrospettiva di 83 casi
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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
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