1,720,960 research outputs found
Influence of organic acids on aluminium absorption and storage in rat tissues
No full textSix groups of 16 rats each were fed a standard diet for 8 weeks. Aluminium (Al) complexed with organic anions (citrate, lactate, malate, or tartrate) was added to the diet of four of the groups and aluminium hydroxide to the diet of one group (control 'Al +'). Aluminium concentrations in the diets were 1500-2000 mg/kg. The sixth group (control 'Al -') served as control. Plasma, bone (femur), kidneys, cerebral cortex and cerebellum levels of aluminium were determined at 4 and 8 weeks. All the complexing agents increased tissue accumulations, compared with values in the two control groups, especially citrate in bone and kidneys and lactate in cerebral cortex. There were no significant differences (P < 0.05) in aluminium levels in the tissues considered between the 'Al +' and 'Al -' control groups. Our results show the ability of dietary organic acids to increase aluminium absorption and tissue accumulation and indicate that concurrent intake of aluminium and dietary organic acids is not appropriate
Dietary Selenium Intake and Selenoproteins in Rat Plasma
No full textSelenium (Se) is vital for animals and humans, as it is an essential component of Se-dependent glutathione peroxidase (GPx), an enzyme that reduces peroxides and protects cells against the damaging effects of oxidation. Se has, however, been found in rat plasma even when the enzymatic activity of GPx is very low, supporting the hypothesis that Se is also bound to other proteic structures. The purpose of this work was partially to purify the selenium-containing proteins in plasma, without denaturation, by isoelectrofocusing. We observed two pH intervals in the plasma where Se-containing proteins concentrated upon focusing: the first, at pH 6.0 ± 0.2 and with GPx activity, and the second, between pH 4.6 and 5.4, with no enzymatic activity. We can infer therefore that other Se-containing proteins are present at a lower pH than 6, and in particular between 4.6 and 5.4
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
A suitable method for defining the nutritional quality of virgin olive oil
No full textModification of the membrane fatty acids affects the structure of the surrounding environment causing a variation in membrane stability, fluidity and permeability. In this study we developed a red blood cells fragility measurement to evaluate the influence of antioxidant intake on membrane functionality. Rats were fed diets differing in oxidized (peroxide value 400 mEq/kg fat) and antioxidant (vitamin E 7.8mg/kg diet) compounds. The results indicate that the resistance of red blood cells to the oxidative stress test was related to the tocopherols present in diets. The main effect on red blood cells fragility was due to the tocopherols which produced the greatest antioxidant response. The fluidity and resistance of red blood cell membranes were determined by their lipid and antioxidant composition. The higher the antioxidant, the more efficient the red blood cell resistance
Some nutritional benefits of extra virgin olive oil
No full textThe benefits of olive oil could be related to its antioxidant potential. The aim of this study was to evaluate the "in vivo" antioxidant activity of different extra virgin olive oils (EVOO) produced in the Mediterranean area. One hundred and twenty rats were fed diets containing oxidised and refined olive oil (400 mEq O2 kg) for 11 weeks, a period of time sufficient to induce globular fragility and marginal plasma tocopherols deficiency.
The animals were then fed 5 diets containing EVOO with content of tocopherols and phenols ranging from 165 to 335 and from 62 to 389 ppm respectively, in different tocopherols/phenols ratios, for 4 weeks. Results show that plasma tocopherols concentration after EVOO feeding was directly related to dietary intake.
Moreover, globular resistance improved to a different extent with EVOO diets compared to the oxidised oil diet. The most favourable antioxidant response was obtained by feeding the oil high in both tocopherols and phenols; the action of phenols was considered synergetic to that of tocopherols in restoring normal conditions, impaired by the oxidised oil diet
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
- …
