1,720,963 research outputs found
ALTERAZIONI MOLECOLARI ASSOCIATE ALLA SENESCENZA DELL’OVOCITA DI MAMMI-FERO. VI CONGRESSO AIBG, ASSOCIAZIONE ITALIANA DI BIOLOGIA E GENETICA GENE-RALE E MOLECOLARE
No full textPossible role for Ca+clmodulin-dependent protein kinase as an effector of the fertilization Ca+ signal in mouse oocytes activation
No full textAug
RUOLO DEL METILGLIOSSALE NELL’INVECCHIAMENTO OVARICO
No full textRUOLO DEL METILGLIOSSALE NELL’INVECCHIAMENTO OVARICO Maria Cristina Carbone*, Claudio Festuccia§, Roberto Gualtieri●, Anna Maria D’Alessandro°, Mario Di Cola°, Fernanda Amicarelli*, Carla Tatone° *Dip. di Biologia di Base ed Applicata, §Dip. di Medicina Sperimentale, °Dip. di Scienze e Tecnologie Biomediche, Università dell’Aquila; ●Dip. di Biologia Strutturale e Funzionale, Università di Napoli. Carla Tatone, Dip. di S.T.B., Università dell’Aquila, Via Vetoio, 67100 L’Aquila – tel. 0862 433441 – fax 0862 433433 – e-mail [email protected] Uno dei meccanismi alla base dell’invecchiamento è rappresentato dall’accumulo di danni irreversibili associati a reazioni biochimiche collaterali a quelle dei processi metabolici di base [1]. Un prodotto collaterale della glicolisi è il metilgliossale, un ossialdeide altamente reattiva con proprietà citotossiche associate alla modificazione di proteine e acidi nucleici, alla produzione di specie reattive dell’ossigeno, ad alterazioni mitocondriali e all’induzione di apoptosi [2]. Il metilgliossale è responsabile della formazione di AGE (Advanced Glycation End products), proteine glicate in modo irreversibile che possono provocare danni tissutali attraverso processi di crosslinking o mediante l’attivazione di specifici recettori contribuendo all’insorgenza di patologie come l’ischemia, l’invecchiamento e le complicanze diabetiche [3]. In questo studio è stata investigata la presenza di AGE derivati dal metilgliossale (MG-AGE) in ovaie di topi giovani ed in avanzata età riproduttiva (anziani) utilizzando un anticorpo specifico per questo tipo di addotti. I risultati ottenuti mediante immunoistochimica hanno evidenziato la presenza di MG-AGE nelle ovaie indipendentemente dall’età. Tuttavia, l’immunopositività, localizzata soprattutto a livello dello stroma ovarico, della parete dei vasi, e della teca follicolare, risultava più intensa nelle ovaie dei topi anziani. Questa valutazione era confermata dall’analisi degli MG-AGE mediante Western blotting che dimostrava un notevole aumento di questi addotti nei lisati proteici delle ovaie di topi anziani. Poiché queste osservazioni suggerivano che l’invecchiamento ovarico è associato ad un accumulo di metilgliossale, abbiamo valutato gli effetti di questo composto sulla funzionalità mitocondriale e sulla vitalità delle cellule germinali esponendo ovociti ovarici di topi giovani e anziani a diverse concentrazione di questo composto. I risultati ottenuti hanno evidenziato la presenza di frammentazione del DNA in assenza di attivazione di caspasi ed un cambiamento nella localizzazione intracellulare dei mitocondri ad alto potenziale in entrambe le classi di età, ma con un maggiore effetto sugli ovociti di topi anziani. Queste osservazioni supportano l’ipotesi che l’accumulo di danni irreversibili associati ai processi di glicazione proteica rappresentano uno dei meccanismi responsabili della produzione di ovociti con ridotta potenzialità di sviluppo in avanzata età riproduttiva. BIBLIOGRAFIA 1. D. Yin and K. Chen (2005) The essential mechanisms of aging: irreparabile damage accumulation of biochemical side-reactions. Experimental Gerontology 40:455-465. 2. M.P. Kalapos (1999) Methylglyoxal in living organisms, Chemistry, biochemistry, toxicology and biological implications. Toxicology Letters 110: 145-175. 3. T. Oya, N. Hattori et al. (1999) Methylglyoxal modification of protein. The Journal of Biological Chemistry 274:18492-18502
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
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