1,721,065 research outputs found
Cholesterol depletion modifies plasma membrane lipid raft integrity and affects glucose uptake in a human leukemic cell line
Full text linkCholesterol depletion modifies plasma membrane lipid raft integrity and affects glucose uptake in a human leukemic cell line
C. Caliceti, L. Zambonin, C. Prata, F. Vieceli Dalla Sega, G. Hakim and D. Fiorentini
Dipartimento di Biochimica “G. Moruzzi”, Università di Bologna - Italy
In hemopoietic M07e cells, stem cell factor (SCF) activates glucose transport through GLUT1 translocation from intracellular stores. Recently, it has been reported that in many cell types GLUT1 is localized in part in detergent-resistant membrane (DRM) domains and a role for lipid rafts in GLUT1 stimulation has been suggested. We investigated whether a plasma membrane cholesterol depletion might play a role in GLUT1 activity. Cell exposure to 10 mM methyl--cyclodextrin (MBCD) for 20 min resulted in a loss of cholesterol from plasma membrane, without affecting viability. MBCD-treated cells exhibited a rise in glucose uptake, higher than that observed upon SCF treatment. The combined cell treatment with SCF and MBCD determined a further increase in glucose uptake, showing an additive effect. Membrane fractionation by flotation on sucrose density gradient showed that in untreated cells most of GLUT1 is distributed in the high-density region, but a little amount is colocalized with lipid raft marker proteins in low-density regions, corresponding to DRM. Upon MBCD treatment, GLUT1 resulted totally confined to the high-density region. DRM exhibited also the highest cholesterol content. The cholesterol distribution profile of the MBCD-treated samples shows that the cholesterol preferentially decreased in DRM, confirming its selective depletion. Cell membrane isolation by biotinylation and immunofluorescence staining indicated that MBCD treatment, like SCF stimulation, greatly enhanced the amount of GLUT1 at cell surface, promoting a translocation from intracellular stores. MBCD increases Akt-pS473, while SCF positively regulates PLCγ signaling cascade, both involved in GLUT translocation and in glucose uptake control. Therefore, these two stimuli could proceed through distinct signalling pathways. In summary, a mild lipid environment alteration in lipid rafts enhances GLUT1 activity in M07e cells via a cholesterol-dependent mechanism, possibly involving Akt
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
Role of aquaporins in the cell signalling mediated by hydrogen peroxide in leukemic cells
Full text linkRole of aquaporins in the cell signalling mediated by hydrogen peroxide in leukemic cells
F. Vieceli Dalla Sega, C. Prata, C. Caliceti, L. Zambonin, D. Fiorentini, G. Hakim, L. Landi
Department of Biochemistry “G. Moruzzi”, University of Bologna, Bologna, Italy
Aquaporins (AQP) constitute a large family of integral membrane proteins, present in all domains of life, that form pores appearing to be designed for the selective passage of water and glycerol [1]. Hydrogen peroxide has been long thought to be freely diffusible but recent evidence suggest that specific mammalian aquaporin homologues (AQP8) possess the capacity to channel H2O2 across membranes [2,3]. Moreover, it has been recently shown that human cells AQP3 expression can modulate the intracellular level of H2O2 and is required for NOX-derived H2O2 signalling [3]. Redox deregulation of proliferative pathways involving ROS (particularly H2O2) in cancer initiation and progression is now firmly established. Here we tested the hypothesis that specific isoforms of aquaporins regulate the level of intracellular H2O2 produced by NOX affecting downstream pathways linked to cell proliferation. In the present study, we show that in different leukemic cell lines NOX2 and/or NOX4 are expressed and are necessary to produce ROS that, in turn, are able to sustain glucose uptake and cell proliferation. Furthermore, we report that inhibition of aquaporins diminishes intracellular ROS accumulation either when H2O2 is produced by Nox enzymes or when is added exogenously to the medium. Finally, we observe a decrease in glucose transport following aquaporins inhibition. Taken together data suggest that aquaporins can regulate hydrogen peroxide uptake and downstream pathways mediated by H2O2
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
- …
