1,720,973 research outputs found
Chromatin Structure of the Human NK Cells Perforin Gene Promoter
No full textInnate immunity plays a vital role in host defense against viral infection and tumor development. Natural Killer (NK)cells are important for the earliest stage of immuneresponse, which occurs without prior sensitization. NK cells have the ability to kill malignant or infected cellsby releasing cytotoxic proteins contained in their cytoplasmic granules. . One of these proteins is the perforin which is responsible for forming pores in the target cell membrane. Although it is believed that the control of perforin expression occurs at the transcriptional level, the molecular mechanisms responsible for that control have not been completely characterized. Our aim is to understand whether this control is somehow related to the chromatin organization of its promoter. We started defining the chromatin organization of perforin promoter using NK cells derived from peripheral blood of healthy individuals: preliminary results indicate that the promoter region spanning the gamma-interferron responsive element is occupied by a positioned nucleosome particle. We are currently analyzing the chromatin structure of the perforin promoter following activation by cytokines treatment of the in vitro cultured cells. Moreover, a similar study has been undertaken on the promoter of the gamma-interferon gene
Le biotecnologie e l'invecchiamento della popolazione: problemi di equità e di epistemologia civica
No full text.Prima di affrontare lo studio dei processi di invecchiamento è necessario partire dalla definizione stessa del fenomeno. La salute di ogni cellula, sia essa giovane o vecchia, è legata al corretto funzionamento di una serie di meccanismi che assicurano l’ingresso all’interno della cellula di sostanze nutrienti e di ossigeno e provvedono contemporaneamente a smaltire i rifiuti. Come fa la cellula a sapere di aver oltrepassato, per così dire, la “soglia della terza età” e di dover fermare il proprio ciclo di replicazione? In altre parole, cosa distingue una cellula giovane da una senescente? Il fenomeno dell’invecchiamento cellulare più che a un’unità genica singola, è da ascriversi a una serie di geni che interagiscono durante la vita della cellula e quindi dell’intero organismo. Numerosi lavori scientifici dimostrano che la senescenza cellulare sia connessa sia con l’accorciamento delle estremità del DNA, i cosiddetti “telomeri”, sia con uno sbilanciamento nello stato ossidoriduttivo della cellula. Molte malattie nell’anziano, tra cui l’arteriosclerosi, la cataratta, il morbo di Parkinson e il morbo di Alzheimer, si associano in gran parte ad una prevalenza di sistemi ossidativi su quelli antiossidanti. E' quindi di fondamentale importanza poter individuare marcatori molecolari specifici, soprattutto quando si vuole affrontare la previsione di patologie associate all’invecchiamento. Un primo passo è, indubbiamente, quello di poter definire i profili di espressione genica specifici (quindi le basi genetiche) per le varie patologie. Alla luce dei meccanismi biochimici dell’invecchiamento individuati finora, i ricercatori stanno sviluppando metodiche e strumenti che consentiranno un controllo sui fondamentali processi biologici al livello cellulare e genetico. Al momento non esistono ancora degli interventi anti-invecchiamento efficaci. Molti biogerontologi, però, sono convinti che le ricerche attualmente in corso potranno produrre in futuro interventi anti-invecchiamento. Sicuramente lo studio delle interazioni tra cause intrinseche (genetiche), estrinseche (ambientali) e stocastiche (danni casuali subiti dalle molecole) permetterà di progettare approcci più mirati per la comprensione del processo dell’invecchiamento
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
Lsm Proteins Promote Regeneration of Pre-mRNA Splicing Activity
No full textAbstractLsm proteins are ubiquitous, multifunctional proteins that affect the processing of most RNAs in eukaryotic cells [1–11], but their function is unknown. A complex of seven Lsm proteins, Lsm2-8, associates with the U6 small nuclear RNA (snRNA) that is a component of spliceosome complexes in which pre-mRNA splicing occurs. Spliceosomes contain five snRNAs, U1, U2, U4, U5, and U6, that are packaged as ribonucleoprotein particles (snRNPs) [12, 13]. U4 and U6 snRNAs contain extensive sequence complementarity and interact to form U4/U6 di-snRNPs. U4/U6 di-snRNPs associate with U5 snRNPs to form U4/U6.U5 tri-snRNPs prior to spliceosome assembly. Within spliceosomes, disruption of base-paired U4/U6 heterodimer allows U6 snRNA to form part of the catalytic center [14]. Following completion of the splicing reaction, snRNPs must be recycled for subsequent rounds of splicing, although little is known about this process. Here we present evidence that regeneration of splicing activity in vitro is dependent on Lsm proteins. RNP reconstitution experiments with exogenous U6 RNA show that Lsm proteins promote the formation of U6-containing complexes and suggest that Lsm proteins have a chaperone-like function, supporting the assembly or remodeling of RNP complexes involved in splicing. Such a function could explain the involvement of Lsm proteins in a wide variety of RNA processing pathways
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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