1,720,985 research outputs found
Supplemental_Material – Supplemental material for OCTN: A Small Transporter Subfamily with Great Relevance to Human Pathophysiology, Drug Discovery, and Diagnostics
No full textSupplemental material, Supplemental_Material for OCTN: A Small Transporter Subfamily with Great Relevance to Human Pathophysiology, Drug Discovery, and Diagnostics by Lorena Pochini, Michele Galluccio, Mariafrancesca Scalise, Lara Console and Cesare Indiveri in SLAS Discovery</p
Functional Study of the Human Riboflavin Transporter 2 Using Proteoliposomes System
No full textRiboflavin is essential for cell viability. The biologically active forms of riboflavin, FMN and FAD, participate in many biochemical redox reactions including the metabolism of carbohydrates, amino acids, and lipids. Differently from bacteria, fungi, and plants which synthesize riboflavin, higher organisms have lost the ability to synthesize the vitamin and must absorb it from food and intestinal microflora production. The riboflavin flux through cell membranes occurs via specific transporters belonging to the SLC52 family. Three members of this family have been identified so far which show poor homology with the riboflavin transporters of Saccharomyces cerevisiae or bacteria. Alterations of RFVTs are causative of severe diseases. Indeed, under pathological stress, humans are susceptible of developing riboflavin deficiency. Such a deficiency in pregnancy induces fetus abnormalities, and has been indicated as a risk factor for anemia, cancer, cardiovascular diseases, and neurodegeneration. Moreover, inherited diseases are also of interest; the most well-described is the Brown-Vialetto-van Laere syndrome, a rare neurological disorder characterized by infancy onset sensorineural deafness and pontobulbar palsy. Numerous polymorphisms of Slc52a2 and Slc52a3 genes associated with this syndrome have been discovered. In spite of their important metabolic role and their relevance to human health, the riboflavin transporters are still poorly characterized. Bacterial overexpression, purification, and protein reconstitution in liposomes represent an up-to-date methodology for obtaining functional data information. The methodology for reconstituting the RFVT2 into proteoliposomes and performing transport assay is described. These methods will be suitable for investigating the functional defects of the variants of RFVTs associated with human pathologies
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
Human riboflavin transporters in health and diseases
No full textRiboflavin, otherwise known as vitamin B2, is an essential dietary component and it represents the precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), the redox enzymatic cofactors required for hundreds of enzymes involved in protein folding, apoptosis, epigenetics and mitochondrial terminal metabolism [1]. Flavin cofactor biosynthesis in different cells starts from riboflavin uptake, which occurs via specialized carrier-mediated processes which are supported by three specific members of the solute carrier family 52 (SLC52A), identified and named respectively RFVT1, RFVT2 and RFVT3. We pointed our attention on a profound alteration of flavin cofactor homeostasis in human colorectal [2] and some other types of cancer, which are accompanied by dysregulation of RFVTs expression. Changing the level of RFVTs expression as a possible mean to reprogram cellular flavoproteome will be discussed. Primary or secondary alterations of the activity/expression of RFVTs have been correlated with rare inherited neuro-muscular disorders, some of which treatable with high doses of the vitamin [3]. The effect of alteration of flavin cofactor availability on mitochondrial flavoenzymes in human cells and worm models will be discussed. To better study structure-function relationships in these human diseases over-production of the human RFVT2 transporter in E. coli was carried out and reconstitution of the purified protein in proteoliposomes for transport assay was performed
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
Function and dysfunction of human riboflavin transporters
No full textRiboflavin, otherwise known as vitamin B2, is an essential dietary component and represents the precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), the redox enzymatic cofactors required for mitochondrial terminal metabolism and for the functionality of mitochondrial respiratory chain. Protein folding, ROS production and defense, as well as redox epigenetics also depend on cellular supply of FAD [1].
FAD formation in different cells starts from riboflavin uptake, which occurs via specialized carrier-mediated processes which are supported by three specific members of the solute carrier family 52 (SLC52A), identified and named respectively RFVT1, RFVT2 and RFVT3. Alterations of RFVTs have been correlated with rare inherited neuro-muscular disorders, some of which treatable with high doses of the vitamin [2].
To better study structure-function relationships in these human diseases we produced the human RFVT2 transporter by over-expression in E. coli and we reconstituted the purified protein in proteoliposomes for transport assay.
We also pointed our attention on a profound alteration of flavin cofactor homeostasis in human colorectal [3] and some other types of cancer, which are accompanied by dysregulation of RFVTs expression. Changing the level of RFVTs expression as a possible mean to reprogram flavoproteome will be discussed
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
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