1,720,967 research outputs found
Effect of PUFAs-ω3 and ω6 on oxidative stress of sheep erythrocytes
No full textBackground: In recent years, the use of long-chain polyunsaturated fatty acids (PUFA) ω3 and ω6, as food supplements in livestock has increased due to their beneficial properties related to their antioxidant activity. It has been demonstrated however that a high intake of these substances has prooxidant and cell-damaging effects, especially if their circulating concentrations are unbalanced. Starting from these premises, and taking advantage of previous findings, the present study aimed at defining the optimal circulating concentrations and PUFAs ω3/ω6 ratio, to ensure the antioxidant/oxidant balance in sheep RBCs. Results: All tested concentrations (25–300 μg/mL in PBS) of PUFAs-ω3 after 4 h of treatment on sheep RBCs, showed antioxidant properties with a significant decrease in reactive oxygen species (ROS) versus the control group (CTRL) (p < 0.05). Furthermore, ω6 showed an antioxidant effect at low concentrations (25–200 g/mL) but a pro-oxidant effect at the highest concentrations (250 and 300 μg/mL) with a significant increase in ROS production (123.6 ± 2.1 and 131.4 ± 6.5% sloope RFU of CTRL respectively p < 0,001), malondialdehyde (MDA) (p < 0.01), and haemolysis (p < 0.01) versus CTRL group (1.1 ± 0.1%), and, also with a decrease of Trolox equivalent antioxidant capacity (TEAC) (p < 0,05). The ratio ω3/ω6 of 1:10 (25/250 μg/mL) and 1:4 (25/100 μg/mL) showed an intracellular ROS level like the CTRL group whereas, the ratio 1:2 (100/200 μg/mL) resulted in a significant decrease in ROS production (62.71 ± 2.31% slope RFU of CTRL, p < 0.001) and MDA (p < 0.001), with an increase in TEAC (p < 0.05), and a decrease haemolysis versus the control group (p < 0,01). Conclusions: Our results showed that a beneficial effect on the oxidative state of sheep RBCs was obtained with in vitro administration of low concentrations of ω6 and with all tested concentrations of ω3. The addition of ω6 at high concentrations leads to an imbalance in the PUFA ω3/ω6 ratio, compromising the oxidative state and viability of the RBCs. The maximum antioxidative effect was found at ω3/ω6 ratio 1:2)
Effect of aging on follicular function may be relieved by exogenous gonadotropin treatment in a sheep model
No full text"The current study investigated hormonal and ovarian changes during physiological reproductive aging in Sarda ewes. In a first experiment, follicular and corpus luteum dynamics were compared during an induced oestrus cycle in aged (12-14 years) and young adult ewes (4-5 years). Oestrus cycle characteristics did not differ between the two experimental groups. However, follicular function during the follicular phase showed significant alterations in aged ewes, as determined by a lack of dominance effect and by lower mean values of circulating oestradiol (E(2)) and inhibin levels, compared with young adult ewes. In a second experiment, differences in follicle growth, hormonal milieu and oocyte quality in response to exogenous FSH administration were assessed in aged and adult ewes. No differences were recorded in ovarian response to FSH treatment between young adult and aged ewes, as evaluated by ultrasonographic data and circulating concentrations of LH, E(2) and inhibin-A. Although the total number of recovered oocytes was similar in the two age groups, the number of good quality oocytes selected for IVM was significantly lower in aged ewes compared with adult ones. Thereafter, no differences were recorded in cleavage rates, total blastocyst output, embryo developmental kinetic and quality between aged and adult groups. In conclusion, this study demonstrated that reproductive aging in sheep is associated with impaired follicle functionality and an increase in the proportion of oocytes showing morphological abnormalities. However interestingly, oocyte developmental competence in vitro and embryo cryotolerance were not affected by the aging process, when only good quality oocytes were chosen.
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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