1,720,961 research outputs found
Folic acid
No full textCaco-2, HT29, CCD841CoTr exposed to 10ng/mL, 100ng/mL and 4000ng/mL folic acid, dose respons
Folate metabolism in the human colon: cellular responses identified through in vitro studies
No full textLow folate intake influences the risk of not only neural tube defects and vascular diseases, but also colorectal tumours. Folate forms have different roles in the one-carbon metabolism. This includes DNA synthesis and methylation reactions. Folate is present as 5'-methyltetrahydrofolate (MTHF) in the diet and plasma, while in supplements the synthetic form is present, known as folic acid (pteryol glutamic acid, PGA). In animal studies, PGA seemed to have dual modulatory effects on colorectal carcinogenesis depending on the timing and dose of intervention. In this thesis the effect of different folate forms and dosages in the colon were studied in vitro using a nutrigenomics approach. The DNA microarray technique was applied to study the expression pattern of thousands of genes, and assess known and identify new processes affected by folate. Gene expression analysis revealed that high PGA concentrationsincreased energy metabolism and lowered iron metabolism related genes in the human colorectal cell line, HT29. Further investigation showed that intracellular iron concentration was decreased in three human colorectal cell lines. This effect on iron metabolism was studied in an existing human randomized, placebo-controlled trial. After six months of folate supplementation the serum ferritin, but not the colonic iron, was decreased. We also studied the difference between PGA and MTHF exposure in HT29 cells, using a physiological concentration range of both folates. A dose dependent effect was found for both folates. The normal serum values of PGA increased genes involved in the folate metabolism, compared to identical MTHF concentration. Supplemental concentrations of MTHF affected protein synthesis, endoplasmatic reticulum/Golgi and cancer related genes, compared to identical PGA concentrations. More specifically, high MTHF increased differentiation, adhesion and cell viability; all known cancer related processes. This may suggest a more beneficial effect of MTHF as compared to PGA. However we need to further investigate the effect of PGA and MTHF on iron metabolism, cancer related processes or energy metabolism in humans. Hopefully this will lead to more insight in the effect of folate supplementation with regard to colorectal carcinogenesis
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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