1,720,959 research outputs found
Effects of genistein on Leber’s hereditary optic neuropathy (LHON) mitochondrial metabolism.
No full textLeber's hereditary optic neuropathy (LHON), a maternally inherited form of central vision loss, is caused by pathogenic point mutations in mitochondrial-encoded subunits of complex I, the first site of the mitochondrial respiratory chain. The most frequent LHON-associated mutations are the homoplasmic m. 11778 G>A in MTND4 gene, the m. 14484 T>C in MTND6 and the m.3460 G>A in ND1 gene [1-2].
One of the open problems in LHON is the variable penetrance: mtDNA mutations are necessary but not sufficient to induce the clinical phenotype. In fact, approximately 50% of males and only 10% of females harboring a primary mtDNA mutation develop the disease. Proposed modifiers include, secondary mtDNA mutations, mtDNA haplogroup, nuclear encoded genes, tobacco and alcohol consumption, and the exposure to toxic compounds [3-4].
By using the cell model of trans-mitochondrial cybrids we recently showed that estrogens ameliorate mitochondrial function, increase cell viability and prevent oxidative stress damage in LHON [5]. Thus, different exposure to estrogens between males and females may account for the still unexplained male prevalence.
Aim of the present study was to compare the anti-oxidative effects of estrogens and phytoestrogens (i.e genistein, one of the soy isoflavones) on LHON metabolism by using the cybrid cells model.
Cybrids were incubated in glucose-free, galactose supplemented medium, forcing the cells to rely mainly on the mitochondrial respiratory chain to produce ATP. Results show that, contrary to control cybrids, in each cell line harboring one of the three most frequent LHON pathogenic mutations, ROS increase, mitochondrial network is altered and there is an high percentage of cell death. Genistein (0.1 μM), similar to estrogens, prevents the alterations induced by galactose on cell growth, ROS production and mitochondrial network. Furthermore genistein activates ERK1 and ERK2 MAP kinases thus up-regulating Mn-SOD antioxidant enzyme. The effects of genistein are antagonised by ERs specific inhibitor (ICI 182780), demonstrating the involvement of estrogen-receptors as mechanism of protection of LHON cybrids from oxidative stress.
Our results open new therapeutic approaches for LHON.
1. Carelli V et al. (2004) - Prog Retin Eye Res, 23: 53–89.
2. Man PY et al. (2009) - J Med Genet, 46: 145–58.
3. Phasukkijwatana N et al. (2010) - Hum Genet 2010, 128: 39–49.
4. Kirkman MA et al. (2009) - Brain, 132: 2317–26.
5. Giordano C, Montopoli M et al. (2011) – Brain, 134:220-34
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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