1,720,986 research outputs found
Ethyl ferulate, a lipophilic polyphenol, induces HO-1 and protects rat neurons against oxidative stress
No full textIn the CNS, the heme oxygenase (HO) system has been reported to be active and to operate as a fundamental
defensive mechanism for neurons exposed to an oxidant challenge. We have recently shown that both curcumin
and caffeic acid phenethyl ester, two phenolic natural compounds, potently induce HO-1 expression
and activity in rat astrocytes. We have extended our previous findings examining the effects of two other
plant-derived phenolic compounds, with analogous chemical structures, in rat astrocytes and neurons. Ethyl
ferulate (ethyl 4-hydroxy-3-methoxycinnamate) (EFE), the naturally occurring ester of ferulic acid, was able
to induce HO-1 protein expression. Maximal expression of HO-1 mRNA and protein and a significant increase
in HO activity were detected after 6 h of incubation with 15 μM EFE in astrocytes and 5 μM EFE in neurons.
Higher concentrations of EFE (50 μM) caused a substantial cytotoxic effect with no change in HO-1 protein
expression and activity. Exposure of astrocytes to resveratrol, a phytoalexin derived from grapes, resulted in
an increase of HO-1 mRNA, but it was not able to induce HO-1 protein expression and activity. Interestingly,
preincubation (12 h) of neurons with EFE resulted in an enhanced cellular resistence to glucose oxidasemediated
oxidative damage; this cytoprotective effect was considerably attenuated by zinc protoporphyrin
IX, an inhibitor of HO activity. This study identifies a novel natural compound that could be used for therapeutic
purposes as a potent inducer of HO-1 for the protection of brain cells against oxidative and neurodegenerative
conditions
Gene expression profiles of heme oxygenase isoforms in the rat brain.
No full textIn the last decade the heme oxygenase (HO) system has been strongly highlighted for its potential significance in maintaining cellular homeostasis. Nevertheless the physiological relevance of the three isoforms cloned to date, HO-1, HO-2 and HO-3, and their reciprocal interrelation have been poorly understood. In the brain the HO system has been reported to be very active and its modulation seems to play a crucial role in the pathogenesis of neurodegenerative disorders. To discriminate the regional and cellular distribution of HO isoforms in the CNS, we have developed a real time quantitative reverse transcription-polymerase chain reaction (RT-PCR) protocol. With
this highly sensitive methodology we have assessed for the first time the expression of all known HO isoform mRNAs in different rat brain areas. Although they presented a highly dissimilar range of expression, with HO-2.HO-1.HO-3, all three HO isoform transcripts demonstrated high level of expression in the cerebellum and the hippocampus, showing in a different scale, a strikingly parallel distribution gradient.We have also quantified the expression of HO mRNAs in primary culture of cortical neurons and type I astrocytes. While HO-1 and HO-2 were detected in both cellular types, HO-3 transcript was uniquely found in astrocytes. To further investigate the
regional brain expression of this elusive and poorly studied isoform, we have performed in situ hybridization using an HO-3 specific riboprobe. HO-3 mRNA was expressed mainly in hippocampus, cerebellum and cortex. The initial elucidation of HO isoforms distribution should facilitate further research on their pathophysiological role in the nervous system
Modulation of cellular stress response in the CNS by a novel class of polyphenolic compounds
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
- …
