1,721,555 research outputs found
La supplementazione umana con vitamina E = Vitamin E supplementation
No full textAfter near to one century of research and speculations on beneficial properties, vitamin E has recently become to the scientific reconsideration due to possible adverse effects. Metanalysis studies have in fact suggested that supplementation at doses higher than 400 UI/die (i.e. 400 mg of synthetic alpha-tocopherol or approximately 180 mg of its natural form) would increase the risk of mortality in cardiovascular risk patients. Toxicology data provide solid evidence on the fact that vitamin E is well tolerated in humans. Toxicity effects are difficult to be demonstrated even at dosages of several grams per day maintained for years. The levels defined as potentially harmful in these metanalysis studies do not exceed the tolerable upper intake level (UL) nor the acceptable daily intake (ADI) that have been established by the most authoritative food safety and nutrition boards and institutions worldwide. For european countries these levels correspond to 300 mg/die and 0.15-2 mg/kg of body weight/die of natural alpha-tocopherol, respectively. These aspects and the debate on scientific value and implications for human health of the information rising from vitamin E metanalysis studies has lead to the conclusion that these do not provide a sufficient level of evidence for such a risk. On the other hand, these metanalysis studies have provided an occasion for further evaluating safety and need of dietary supplements that have been proposed for the primary and secondary prevention of chronic-degenerative diseases such as CVD, cancer and neurodegenerative diseases. Actually, largest clinical trials on vitamin E supplementation and assessed in these metanalysis studies did not provide solid evidence for any prevention effects. Therefore, massive and indiscriminate supplementation protocols should be avoided and the general population should be advised against this. A sceptic attitude has to be adopted against the use of high doses vitamin E as a therapeutic measure for the clinical end-points so far taken into consideration. Instead of this, it has to be recommended to reach the optimal intake of this vitamin (in Europe the RDA is 10 mg) by means of a balanced consumption of natural sources of this vitamin (main food sources of vitamin E are wheat germ, nuts and seeds, and plant oils in general), and this type of recommendation can guaranty to have all the possible beneficial effects of this vitamin as well as of other micronutrients, without any potential risk
Headache and anxiety/mood disorders: are we trapped in a cul-de-sac?
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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
IDENTIFICATION OF THREE NOVEL REGULATORY PATHWAYS INVOLVED IN THE DOWN-REGULATION OF P63 PROTEIN LEVELS
Full text linkOne way to regulate protein functions is by post-translational modification. Post-translational modifications have an important role in the regulation of biological activity of the protein because they allow both to extend the range of functions of a protein and to monitor the activity and determine the activation or inactivation of a protein. The most common protein post-translational modifications include ubiquitylation, phosphorylation and acetylation play an essential role in cellular functions such as cellular differentiation, apoptosis, DNA repair, antigen processing, and stress response. Under particular conditions abnormal post-translational modifications were found in many diseases like: Alzheimer’s disease, Parkinson’s disease, induction of different cancer and others. These abnormal post-translational modifications are permanent and can cause loss or alteration of protein function by changing enzyme activities or capacity aggregation (Stadtman and Levine 2000; Shacter 2000).
p63 protein stability is regulated by different protein modifications such phosphorylation, ubiquitylation and sumoylation. p63 is known to be degraded by ubiquitin-mediated proteasomal degradation, the E3 ubiquitin ligase NEDD4-like, ubiquitin protein ligase Itch and ubiquitin-like protein SUMO-1 have been shown to directly interact with p63 and regulate p63 protein stability (Ghioni et al. 2005; Rossi at al. 2006; Rossi et al. 2006) suggest the importance of regulating p63 to tune its biological activity.
During my PhD thesis we found three novel and distinct mechanisms that are involved in the regulation of the p63 protein levels; all these mechanisms induce p63 degradation. We demonstrated that these mechanisms are relevant in different physiological contexts and that they are involved in the regulation of p63 biological function.
1. MDM2-Fbw7 pathway contribute to reduce ΔNp63α protein levels during keratinocytes differentiation and upon DNA-damage induced by UV exposure and adriamycin treatment.
2. TRIM8 plays a role in enhancing p53 anti-oncogenic activity and at the same time down-modulate oncogenic ΔNp63α activity.
3. Hipk2 phosphorylates and promotes proteasomal degradation of ΔNp63α to enable an effective DNA-damage response induced by genotoxic drugs.
All these evidences indicate that regulation of p63 protein stability is a key mechanism to control p63 activities, in particular during epithelia differentiation and in response to genotoxic agents.
The knowledge and the identification of the molecular mechanisms governing p63 regulation under physiological context might be fundamental for understanding the pathogenesis of human syndromes associated to p63 mutations and the mechanism by which p63 promotes disease development.
We hope that future studies focusing on the mechanisms involved in p63 protein regulation might increase our knowledge on the p63 role in tumorigenicity and in response to anti-cancer therapy to improve anti-cancer therapies
REDUCTION OF THE CARBON FOOTPRINT OF FUELS AND PETROCHEMICALS STARTING FROM VEGETABLE OILS
Full text linkIn this work developments and innovative studies are proposed for the current biodiesel technology in order to make the whole productive process more efficient. In particular, three main aspects were deeply investigated, the oil deacidification, as a pre-step to the oil transesterification, working on the optimization of the operative parameters and developing a suitable kinetic model able to predict, in a wide range of concentrations and temperatures, the acid conversion and the eventual double phase system formation. Moreover, the extraction of carotenes from crude palm oil was investigated, focusing on finding the operative parameters that permitted its complete preservation. Experimental results showed that at the optimized condition these molecules were adsorbed on the catalyst, giving encouraging information regarding their extraction from crude oils. Secondly, the transesterification reaction was studied in a novel way, trying to overcome the mass limitation due to the low methanol solubility in oil using a suitable co-solvent and CaO as catalyst. Good results were obtained when THF was used, the biodiesel yield was comparable to the homogeneous catalyzed process. Finally, a possible improvement of biodiesel to valuable chemical was studied. In particular the synthesis of epoxidized biodiesel was firstly optimized and then performed on biodiesel and distilled biodiesel, obtaining with this latter substrate a product with an epoxide content comparable to a commercial product, giving positive suggestion for its application as bioplasticizer
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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