1,721,029 research outputs found
Glial cell-derived neurotrophic factor (GDNF) promotes invasive bahavior in testicular seminoma cells
Full text linkThe neurotrophic factor GDNF has multiple functions that promote cell survival, proliferation and migration in different cell types. The experimental over-expression of GDNF in mouse testis leads to infertility and promotes seminomatous germ cell tumors in older animals, which suggests that although the underlying mechanisms are unknown, deregulation of the GDNF pathway may be implicated in germ cell carcinogenesis. To explore the involvement of the GDNF pathway in the onset and progression of testicular germ cell tumors, we firstly analyzed the expression pattern of GFRA1 and Ret, the two major co-receptors for GDNF, in seminoma samples. We report that GFRA1 was expressed more extensively in carcinoma in situ (CIS) cells and intratubular invasive seminoma compared with normal testis.
Functional analysis of the GDNF biological activity was performed on TCam-2 human seminoma cell line. RT-PCR and immunohistochemical analyses demonstrate that TCam-2 cells express both GFRA1 and Ret mRNA, but only GFRA1 was detected at the protein level. It is well known that GDNF plays a central role in spermatogonial stem cell self-renewal and proliferation (Hoffman MC et al., 2008). Therefore, in order to evaluate if GDNF could act as a mitogenic factor in TCam-2 cells, we performed proliferation assays and cell cycle analyses. Interestingly we observed that GDNF doesn’t induce increase in total cell number or S-phase entry in TCam-2 cell line.
Several evidences suggested that GDNF is able to induce cell migration and invasion in several normal and tumor cell types (Okada Y et al., 1999; Veit C et al., 2004; Su CM et al., 2009; Song H et al., 2006; Paratcha G et al., 2006; Tang MJ et al., 1998; Young HM et al., 2001). Therefore we have hypothesized that GDNF can act as a chemoattractant also in seminoma cells. On this purpose we stimulated directional TCam-2 cell migration and invasion in the presence of GDNF gradients and we investigated the downstream pathways responsible for the GDNF-induced invasive behaviour. We demonstrated that GDNF is able to induce migration, possibly through the Src and MEK pathways. It is documented that tumor cell invasion can occur through two modalities: a proteolytic mesenchymal-like or non-proteolytic amoeboid-like modality (Sahai E and Marshall CJ, 2003; Wolf K et al., 2003). GDNF is able to induce TCam-2 seminoma cell invasion in a mesenchymal-like metalloprotease-dependent manner.
In conclusion, GFRA1 over-expression in CIS and seminoma cells, along with the functional analyses in TCam-2 cells, suggests an involvement of the GDNF pathway in the progression of testicular germ cell cancer
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
Nanomedicine and bacterial infections: expertise and experience of the microbilogy group of "SAPIENZA university of ROME"
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San Vincenzo, Isola di Stromboli (Lipari, Prov. Di Messina) - Campagna 2014
No full textPresentazione sintetica dei risultati della campagne di scavo effettuate nel 2014 nel sito archeologico di San Vincenzo a Strombol
Experimental morphogenetic field (EMF) promotes cell adhesion, cell spreading and modifies F- actin distribution pattern of TCAM-2 seminoma cells.
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