1,721,064 research outputs found
Lycopene phytocomplex, but not pure lycopene, is able to trigger apoptosis and improve the efficacy of photodynamic therapy in HL60 human leukemia cells.
No full textWe compared the ability of pure lycopene (Lyco) versus lycopene phytocomplex (LycoC) to induce apoptosis in vitro. We found that LycoC, but not Lyco, was able to trigger apoptosis in HL60 cells, as documented by subdiploid DNA content and phosphatidylserine exposure. LycoC-induced apoptosis was associated with reactive oxygen species (ROS) generation and loss of mitochondrial transmembrane potential, suggesting that LycoC triggered apoptosis via a mitochondrial pathway. We also verified the redox state of cells by measuring glutathione (GSH) content, but only a small percentage of cells showed GSH depletion, suggesting that the loss of GSH may be a secondary consequence of ROS generation. Moreover, LycoC pretreatment effectively increased apoptosis induced by photodynamic therapy (PDT), a mode of cancer treatment using a photosensitizer and visible light. LycoC pretreatment was even more potent in improving PDT than pretreatment with ascorbic acid or alpha-tocopherol (or the two combined). Our results demonstrate that LycoC has a stronger cytotoxic effect than Lyco and is a better source of agents able to trigger apoptosis in HL60 cells and improve the efficacy of PDT in vitr
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
Glutathione recycling and antioxidant enzyme activities in erythrocytes of term and preterm newborns at birth
No full textWe previously demonstrated a high susceptibility of neonatal red blood cells (RBC) to oxidative stress at birth. The aim of this study was to compare the RBC antioxidant capacity and redox cycle enzyme activities as well as glutathione (GSH) recycling in full-term and preterm infants at birth and in normal adults. GSH and GSH disulfide (GSSG) concentrations, GSH/GSSG ratio, and the activities of glucose-6-phosphate dehydrogenase (G-6-PDH), GSH peroxidase, GSH reductase (GR), catalase (CAT), superoxide dismutase (SOD), and hexokinase (HK) were measured in RBC of 25 healthy adults and 56 newborns (23 term, 33 preterm) at birth. The GSH recycling was measured in adult and newborn RBC exposed to oxidative stress (1 mM tert-butylhydroperoxide). The RBC of term and preterm babies showed higher GSH, GSSG, G-6-PDH, GR, and HK levels/activities and lower GSH/GSSG ratios and higher GSH-recycling rates than those of adults. In preterm babies significant correlations were found between G-6-PDH and CAT, GSH, GSH/GSSG ratio, and GSSG (r = -0.67, r = 0.71, r = -0.66, p < 0.01; r = 0.71, p < 0.05, respectively). In term newborns, statistically significant correlations were observed between G-6-PDH and CAT, SOD, and GSH (r = -0.65, r = -0.65, r = -0.69, p < 0.01, respectively). The results indicate the central role of the G-6-PDH activity in antioxidant defenses. We speculate that preterm babies have prompter involvement of antioxidant defenses than term babies
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