1,720,963 research outputs found
Exposing mice to low Cd doses triggers a biphasic oxidative stress response in the kidney: a role for Prdx2 and Nox4?
No full textIn previous studies exposing animals to Cd caused oxidative stress and kidney damage. Mostly high doses were applied, often by injection. In the present study mice were exposed up to 23 weeks to low Cd concentrations (10 and 100 mg CdCl2/l) in the drinking water.
Antioxidant gene expression levels as well as glutathione, ascorbate and lipid peroxidation levels were measured.
Metallothionein 1 and 2 were upregulated from 1 week of exposure on. An early induction of the Prdx2 gene suggested that peroxiredoxin might be involved in the early response as well.
After 8 weeks Cd reduced antioxidant expression of Bcl2, Prdx2 and Sod1 which might indicate a toxic effect. No significant effect was seen on lipid peroxidation however, and the overall redox status remained in balance throughout the whole experiment. Levels of reduced glutathione and ascorbate and of transcription of Sod2 remained stable. This suggested that the energy maintenance in mitochondria was under control.
A second response was observed after 23 weeks. Interestingly, the expression of renal NADPH oxidase 4 (Nox4) increased. Nox4 has not been studied yet in Cd nephrotoxicity. The antioxidants catalase, glutathione peroxidase 4 and heme oxygenase 1 also responded. In conclusion our study reveals a two-step oxidative stress response in the kidney. Clearly the kidney was in control of Cd-induced oxidative stress after exposure to low Cd concentrations
Low cadmium exposure triggers a biphasic oxidative stress response in mice kidneys
No full textOxidative stress is believed to participate in the early processes of cadmium (Cd)-induced proximal tubular kidney damage. Mice were chronically exposed up to 23 weeks to low Cd concentrations (10 and 100 mg CdCl2/l) via the drinking water. Pro- and antioxidant gene expression levels, glutathione, ascorbate and lipid peroxidation levels were measured. Our study provided evidence for an early and a late stress response in the kidney. Metallothioneins were upregulated from 1 week of exposure on and they stayed important during the whole exposure period. After 8 weeks the expression of Bcl2 (anti -apoptotic), Prdx2 and cytosolic superoxide dismutase (Sod1) was reduced in the group exposed to 100 mg CdCl2/1, which might indicate a response to Cd-stress. However glutathione, ascorbate and lipid peroxidation levels did not significantly change, and the overall redox balance remained stable. Stable Sod2 transcriptional levels suggested that an increased formation of superoxide anions, which can arise upon Cd-induced mitochondrial free radical generation, was not appearing. A second defence activation was observed after 23 weeks: i.e. an increase of catalase (Cat), glutathione peroxidase 4 (Gpx4) and heme oxygenase 1 (Hmox1), together with NADPH oxidase 4 (Nox4), of which the role has not been studied yet in Cd nephrotoxicity. These findings were in contrast with previous studies, where Cd-induced oxidative stress was detrimental when high Cd concentrations were applied. In conclusion our study provided evidence that a chronic exposure to low Cd concentrations triggered a biphasic defence activation in the kidney that might lead to adaptation and survival. (c) 2007 Elsevier Ireland Ltd. All rights reserved
Exposing mice to low Cd doses triggers a biphasic oxidative stress response in the kidney: a role for Prdx2 and Nox4?
No full textIn previous studies exposing animals to Cd caused oxidative stress and kidney damage. Mostly high doses were applied, often by injection. In the present study mice were exposed up to 23 weeks to low Cd concentrations (10 and 100 mg CdCl2/l) in the drinking water.
Antioxidant gene expression levels as well as glutathione, ascorbate and lipid peroxidation levels were measured.
Metallothionein 1 and 2 were upregulated from 1 week of exposure on. An early induction of the Prdx2 gene suggested that peroxiredoxin might be involved in the early response as well.
After 8 weeks Cd reduced antioxidant expression of Bcl2, Prdx2 and Sod1 which might indicate a toxic effect. No significant effect was seen on lipid peroxidation however, and the overall redox status remained in balance throughout the whole experiment. Levels of reduced glutathione and ascorbate and of transcription of Sod2 remained stable. This suggested that the energy maintenance in mitochondria was under control.
A second response was observed after 23 weeks. Interestingly, the expression of renal NADPH oxidase 4 (Nox4) increased. Nox4 has not been studied yet in Cd nephrotoxicity. The antioxidants catalase, glutathione peroxidase 4 and heme oxygenase 1 also responded. In conclusion our study reveals a two-step oxidative stress response in the kidney. Clearly the kidney was in control of Cd-induced oxidative stress after exposure to low Cd concentrations
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
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