1,720,958 research outputs found
Resveratrol prevents age-dependent motor and cognitive decline and prolongs life span in a short-lived vertebrate
No full textCentral regulation of food intake during aging in the teleost fish Nothobranchius furzeri.in Annals of Anatomy-Anatomischer Anzeiger 10.1016/j.aanat.2016.04.020 special issue on Animal Anatomy II, vol 207:123-124 A. Montesano, N. Arcamone,T. Genade,P.de Girolamo
No full text4.2 Central regulation of food intake during aging in the teleost fish Nothobranchius furzeri Montesano A, Arcamone N, Genade T, De Girolamo P The mechanisms deputed to energetic control have been selected by ancestral diets resulting from the nutrient disposal during the evolution. They are regulated by a network of molecules controlling metabolic needs and influence caloric intake. Also the course of aging adds significant modifications to energy homeostasis and fuel metabolism in. An emerging model for aging research, a teleost fish Nothobranchius furzeri, the vertebrate with the shortest lifespan described in laboratory, is employed to investigate the regulation of Neuropeptide Y (NPY) and Orexin A and B in the hypothalamus. The study is carried out on specimens at different age stages and fed with different diets. Immunohistochemical analyses revealed the localization and co-labeling of NPY, Orexins A and B in some hypothalamic areas, as the dorsal hypotalamus (Hd) and diffuse inferiore lobe (DIL). The co-labeled neurons were identified as serotoninergic. In addition, the median lifespan is prolonged of more than one week in subjects treated with hypocaloric diet. In the latter group, western blot analyses revealed high expression of NPY in the brain. These observations suggest that the role of NPY in food intake regulation is modulated during aging and hypocaloric regime, and is linked to the action of Orexin A. Furthermore, the co-presence of NPY and Orexin A in serotoninergic neurons could indicate the involvement of the two peptides also in the circadian rhythm regulation
“Annual fishes of the genus Nothobranchius as a model system for aging research”
Full text linkAging research in vertebrates is hampered by the lack of short-lived models. Annual fishes of the genus Nothobranchius live in East African seasonal ponds. Their life expectancy in the wild is limited by the duration of the wet season and their lifespan in captivity is also short. Nothobranchius are popular aquarium fishes and many different species are kept as captive strains, providing rich material for comparative studies. The present paper aims at reviving the interest in these fishes by reporting that: (1) Nothobranchius can be cultured, and their eggs stored dry at room temperature for months or years, offering inexpensive methods of embryo storage; (2) Nothobranchius show accelerated growth and expression of aging biomarkers at the level of histology and behaviour; (3) the species Nothobranchius furzeri has a maximum lifespan of only 3 months and offers the possibility to perform investigations thus far unthinkable in a vertebrate, such as drug screening with life-long pharmacological treatments and experimental evolution; (4) when the lifespan of different species is compared, a general correlation is found between wet season duration in their natural habitat and longevity in captivity; and (5) vertebrate aging-related genes, such as p66Shc and MTP, can be easily isolated in Nothobranchius by homology cloning. These fishes can become excellent models for aging studies. They can be employed to test the effects of experimental manipulation on aging at a pace comparable with that of Drosophila and to probe the effects of natural selection on the evolution of aging-related genes
Resveratrol prolongs lifespan and retards the onset of age-related markers in a short-lived vertebrate
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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
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