1,721,008 research outputs found
High dietary fat increases polyamine content of murine mammary glands
No full textFemale C57BL/6J mice, nine weeks old, were fed diets differing in the amount and type of fat (5% and 23.5% w/w olive oil and corn oil), for a period of two weeks. The levels of total and individual polyamines putrescine, spermidine and spermine) were measured in the mammary glands after two weeks of experimental diet. For this analysis we used a liquid-liquid chromatography apparatus equipped with a fluorescence detector. The levels of putrescine and spermine were higher in the 23.5% fat diets compared to the 5% fat diets. This increase was induced by olive and corn oil, while the content of spermidine increased only in high olive oil diets. Mice in estrus had higher polyamine levels in mammary tissue than mice in diestrus on the same diet. The results were analyzed with a regression analysis model considering the interaction of variables like estrus, diestrus, type of polyamine and type of dietary fat. The increase in mammary polyamine levels induced by high dietary fats is an indicator of increased proliferation since cell polyamines increase during the early phase of cell growth both in normal and in cancer mammary tissues. Although the role of dietary fat in mammary carcinogenesis has not been well established yet, our data demonstrate that a variation of cell proliferation induced by fat may modify the response to chemical carcinogens
Modification of azoxymethane intestinal carcinogenesis in rats by feeding sucrose boluses, pasta, and glucose
No full textWe studied whether repeated boluses of sucrose or diets containing carbohydrates with a variable glycemic index (GI) affect intestinal carcinogenesis in rats. Male F344 rats were treated twice (1 wk apart) with 15 mg/kg sc azoxymethane (AOM) and then divided into four experimental dietary groups with different carbohydrate composition and administration schedules: the sucrose group was fed 44% (wt/wt) sucrose (GI = 65), the bolus group was fed sucrose as carbohydrate and 43 boluses of sucrose (10-15 g/kg) at various time intervals, the pasta group was fed pasta [77% (wt/wt) cooked pasta, GI = 55], and the glucose group was fed 44% (wt/wt) glucose (GI = 97). All nutrients, including carbohydrates, were provided in similar amount to the different groups. The experiment was terminated between Day 230 and Day 245 after AOM administration. At this time the pasta group had significantly higher cecal short-chain fatty acids than the other groups. Intestinal adenomas and cancers occurred with the same frequency in the bolus, sucrose, and glucose groups. On the contrary, we observed a significant decrease (p = 0.03) in the cumulative incidence of intestinal adenomas, but not adenocarcinomas, in the pasta group compared with the sucrose group (intestinal adenoma incidence in the pasta group was 31% compared with 63% in the sucrose group, 46% in the bolus group, and 37% in the glucose group). In conclusion, these results do not support the hypothesis that sucrose boluses or carbohydrates with a high GI stimulate colon carcinogenesis, but they indicate that foods such as pasta may exert a protective effect
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
Update on sequential isologous rat organ transplantation: pancreaticoduodenal and kidney transplantations.
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