1,720,975 research outputs found
Sodium coupled Neutral Aminoacid Transporter 2 (SNAT2) Intron1 methylation levels and Single Nucleotide Polymorphism in IUGR placentas
No full textA reduction in placental nutrient transport is clearly involved in Intrauterine Growth Restriction (IUGR).
The Sodium coupled Neutral Aminoacid Transporter 2 (SNAT2) has a crucial role in the control of fetal growth, promoting the transport of neutral aminoacids from the mother to the fetus. We recently demonstrated that SNAT2 mRNA expression is significantly lower in human IUGR compared to control placentas. The SNAT2 Intron1 (Int1) is an important regulatory region: it activates SNAT2 expression in aa deficiency conditions; Int1 presents many CpG islands. We measured its methylation levels in IUGR vs control placentas and we investigated a possible association with IUGR of a Single Nucleotide Polymorphism (SNP) located in the Int1, in which the ancestral nucleotide is a Cytosine belonging to a CpG island.
Methylation levels of 13 CpG islands located in the SNAT2 Int1 were analysed by Pyrosequencing in 37 IUGR and 28 control placentas, and in 10 peripheral blood from healthy adults as external control. We genotyped the Int1 SNP in 68 IUGR and 34 control placentas.
No significant differences were found in methylation levels between IUGR and controls. Interestingly, methylation was steadily low in all the observed CpGs.
No association was found between the Int1 SNP and IUGR, analysing data under a codominant, a dominant and a recessive model.
Hypomethylation of control samples (placenta and healthy adults) confirm the great importance of SNAT2, since it is known that CpG islands hypomethylation is a guarantee for gene expression, giving to the gene the potential of being expressed. Our results suggest that the alteration of SNAT2 mRNA that we found in IUGR compared to control placentas, is not due to epigenetic modifications in the SNAT2 Int1 and that IUGR is not associated to the SNP located in this region
Placental LPL gene expression is increased in severe intrauterine growth-restricted pregnancies
No full textIntrauterine growth restriction (IUGR) is associated with reduced placental supply of nutrients to the fetus. Lipoprotein lipase (LPL) mediates the hydrolysis of triolycerides from maternal lipoproteins to obtain fatty acids. Here, we tested the hypothesis that placental LPL gene expression level is altered in pregnancies complicated by IUGR. To this purpose, 28 IUGR fetuses were identified during pregnancy and divided in two groups: 7 M-IUGR ['' mild '' IUGR, with normal umbilical artery pulsatility index (PI)] and 21 S-IUGR ('' severe '' IUGR, with abnormal PI). Moreover, 10 out of 28 IUGR pregnancies were associated with preeclampsia. Controls were 19 normal pregnancies delivering appropriate for gestational age (AGA) fetuses. Relative real-time quantification of LPL was carried out in RNA from placental chorionic villi by the Delta Delta Ct method, using beta-actin as normalizing gene. Placental LPL mRNA expression levels were significantly higher in IUGR than in AGA. In particular, significantly higher values were observed in S-IUGR, independent from the concomitant association with preeclampsia. No significant relationship was observed between placental LPL mRNA expression levels or gestational age. In conclusion, placental LPL mRNA gene expression is increased in severe IUGR, characterized by enhanced vascular placental resistances and alterations of placental nutrient transport
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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