1,721,122 research outputs found
Anomalie genetiche dei tumori neuroendocrini del pancreas
No full textAnalisi delle più comuni anomalie genetiche dei tumori neuroendocrini del pancreas e comparazione con le più comuni anomalie riscontrate nel carcinoma pancreatic
NEU4L INDUCES ALTERATIONS ON CELL PROLIFERATION AND DIFFERENTIATION IN NEUROBLASTOMA CELL LINE, SK-N-BE
Full text linkSialidases are glycohydrolytic enzymes that remove sialic acid residues from gangliosides, sialoglycoproteins and oligosaccharides. The most recently identified member of the human sialidase family is Neu4 and is found in two forms, NEU4 long (Neu4L) and NEU4 short (Neu4S), differing in the presence of a 12-amino-acid sequence at the N-terminus (1-2). Overall, Neu4 is scarcely expressed in adult tissues, in contrast to fetal tissues, where its biological role is currently unclear. We evidenced that the more aggressive neuroblastoma cell lines, a tumor derived from the neural crest, characteristically show a high expression of Neu4L. Here, we demonstrated that this feature is connected to the distorted control of proliferation and differentiation in neuroblastoma.
In order to understand Neu4L role in neuroblastoma, we stably over-expressed Neu4L in human neuroblastoma cells, SK-N-BE.
The first important consequence was a marked acceleration of proliferation rate assessed by increase of 3[H]thymidine incorporation (+ 36%), by cell count for up to 4 days (+36%), by MTT test for up 4 days (+26) and by soft agar assay. Moreover, Neu4L over-expressing cells were impaired to differentiate under FBS depletion culture, as we assessed following the formation and the length of neurites, MTT assay and the content of src, as neuronal marker.
These phenotypical modifications were associated to a marker activation of Wnt/-Catenin pathway, a well-known regulator of proliferation and self-renewal in many cell types.
We assessed an increased content of intracellular, not phosphorylated -Catenin (+30%) in Neu4L over-expressing SK-N-BE cells. In parallel, the main inhibitor of Wnt pathway, GSK3, decreased its expression as mRNA (-30%), while c-myc, cyclin D2 and axin2, which have been identified as target genes of -Catenin (3), underwent a significant increase, as mRNA content, in Neu4L over-expressing SK-N-BE cells. In order to further confirm the activation of the Wnt canonical pathway, we transiently transfected the TOP-Flash luciferase vector into mock and Neu4L over-expressing cells, as gene reporter assay responsive to -Catenin. We detected an increased activation of luciferase in Neu4L over-expressing cell (+52%), confirming our previous results. In order to confirm the greater ability of control cells to differentiate, we studied the neuronal marker , v-src. During the process of differentiation, we observed that Neu4L over-expressing cells had a lower content of this protein in contrast with control cells. Moreover, we identified the precise localization of Neu4L in SK-N-BE cells. We observed that Neu4L mainly localized in mitochondria (40%) and in endoplasmatic reticulum (60%). The direct substrates of Neu4L, in SK-N-BE cells, seem to be soluble glycoproteins in the range of 60 kDa; on the base of literature data, it could be hypothesized that one of these glycoproteins could belong to the Wnt family or to inhibitor-glycoproteins interacting with Wnt signaling. Therefore, we provided the evidence that Neu4L promotes the activation of Wnt/-Catenin signaling in neuroblastoma, inducing proliferation and inhibiting differentiation at the same time, enhancing self-renewal of malignant neuroblasts. 1 Monti E et al. (2004) Genomics 83: 445–53 2 Yamaguchi K et al. (2005) Biochem J 390: 85–93 3 Clevers H et al. (2006) Cell 127; 469-480
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
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