1,720,967 research outputs found
Preliminary study on in vitro activity and cytotoxicity on cell cultures of a new polyene antifungal molecule (SPA-S-843)
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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
Sequenza di due forme alleliche del gene di beta-lattamasi cromosomiale di S. marcescens : effetto della loro espressione sulla sensibilità ad antibiotici-betalattamici di ospiti trasformati=Sequence of two alleles of the chromosomal ß-lactamase gene of S. marcescens : effect of their expression on the antibiotic susceptibility of trasformed hosts
No full textSecretion of basic fibroblast growth factor (FGF-2) by WEHI-3B myelomonocitic leukemia cells
No full textIn order to investigate the role of Fibroblast Growth Factors in hematopoietic cells, we studied the expression of FGF-1, FGF-2, FGF-3, FGF-4, FGF-5 and FGF-6 mRNAs both in murine myelomonocytic leukemia WEHI-3B and in a murine stromal cell line SR-4987. Secretion of FGF-2 in the cell culture supernatant was also studied. Expression of mRNA encoding for the above-mentioned FGFs was analyzed by RT-PCR. The production of FGF-2 in the conditioned media of WEHI-3B and SR-4987 cell cultures was evaluated by techniques of affinity chromatography, chromatofocusing and immunoblotting. The biological activity of FGF-2 was checked on SR-4987 cells by a agar clonogenic assay. In both cell lines mRNA was found encoding for FGF-1, FGF-2 and FGF-6 and WEHI-3B cells express also mRNA for FGF-3 (int-2) and FGF-4 (K-FGF/hst). Furthermore, supernatant from WEHI-3B cells was found to stimulate dramatically the agar clonogenicity of SR-4987 cells which have a very poor basal capacity for growth in agar. The clonogenic activity of WEHI-3B conditioned medium is due to FGF-2 secreted into cell culture supernatant whereas SR-4987 cells, although express FGF-2 mRNA, do not seem able to secrete this factor. The expression in myeloid leukemia cells of oncogene-related factors such as FGF-3, FGF-4 and FGF-6 together with the secretion of FGF-2 able to support a positive regulation of bone marrow stromal cells function suggest that FGFs may have an important role in sustaining the leukemogenic process and related disorders
Role of SR-4987 stromal cells in the modulation of Doxorubicin toxicity to in vitro granulocyte-macrophage progenitors (GM-CFU)
No full textBone marrow stromal microenvironment is essential for the maintenance of the hematopoietic stem cell renewal both by cell-cell interaction and cytokine production. However, stromal cells also exhibit drug metabolizing activities and they may accumulate the drug and successively affect hematopoietic progenitors by a retarded release. Our study investigated the role of both primary culture of murine bone marrow stroma and established stromal cells (SR-4987) in modulating the "in vitro" toxic activity of Doxorubicin (DXR) against murine granulocyte-macrophage progenitors (CFU-GM). The main part of the study has been performed by a "in vitro" agar bilayer technique based on the CFU-GM assay performed over a feederlayer of stromal cells. The results suggest that bone marrow stromal cells play also an important role in decreasing the toxicity of Doxorubicin. Further SR-4987 stromal cells produce a Doxorubicin metabolite (not belonging to the series of metabolites described in literature) which is completely ineffective in inhibiting the growth of CFU-GM and the activity of topoisomerase I. Our data suggest that bone marrow stromal cells must be considered as a cell population having opposite pharmacological roles in modulating the drug toxicity on hematopoietic progenitors. In our model a mechanism of detoxification concerns the capacity of SR-4987 stromal cells to inactivate the drug. For a better prediction of drug hematotoxicity, it is very important to develop "in vitro" cell models able to discriminate between positive and negative modulation of drug toxicity that stromal cells can exert in the bone marrow microenvironment
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