1,720,956 research outputs found
Exploring the Photoprotective Potential of Natural Compounds: Insights into UV-induced Oxidative Stress Modulation
No full textLa radiazione ultravioletta, in particolare gli UVA (315–400 nm), rappresenta uno dei principali fattori responsabili dell’invecchiamento cutaneo attraverso l’induzione di stress ossidativo, infiammazione e danno strutturale ai componenti dermici. Un’efficace fotoprotezione richiede un’interazione coordinata tra le difese antiossidanti endogene e strategie esogene, che includono formulazioni topiche ed interventi nutrizionali, volte a preservare l’omeostasi cellulare in condizioni di esposizione ai raggi UV. Questo lavoro esplora approcci complementari volti a contrastare il danno ossidativo indotto dai raggi UVA nei confronti della pelle. Composti naturali e sintetici dotati di capacità schermanti nei confronti dei raggi UV, sono stati valutati per il loro potenziale fotoprotettivo, con particolare attenzione a derivati tiolici di ispirazione marina (strutturalmente correlati agli ovotioli) ed estratti botanici come l’honeybush. Il ruolo del metabolismo a un carbonio nella fotoprotezione cutanea è stato inoltre esaminato attraverso la valutazione del 5-metiltetraidrofolato (5-MTHF) come strategia sistemica di supporto. Considerata la sensibilità dei folati alla radiazione UV e il loro coinvolgimento centrale nella biosintesi dei nucleotidi e nei processi di metilazione, il mantenimento di un’adeguata disponibilità di folati può rappresentare un fattore chiave per sostenere la capacità di riparazione cellulare e l’equilibrio redox in seguito all’esposizione ai raggi UV. Inoltre, l’enzima antiossidante endogeno paraoxonasi-2 (PON2) è stato studiato per caratterizzare meglio i meccanismi intrinseci di adattamento redox e le vie di risposta allo stress attivate in seguito all’esposizione a UVA. Parallelamente, è stato esplorato lo sviluppo e la caratterizzazione di formulazioni cosmetiche arricchite con estratti botanici acquosi, incorporati in emulsioni olio-in-acqua, al fine di valutarne il loro contributo all’attività antiossidante, alla stabilità della formulazione e alle potenziali proprietà di protezione dall’UV. Nel complesso, questa ricerca fornisce una prospettiva multidimensionale sulla fotoprotezione cutanea, integrando composti naturali con capacità schermante, supporto metabolico sistemico e formulazioni antiossidanti topiche, evidenziando la possibilità dell’utilizzo di strategie sinergiche topiche e nutrizionali per contrastare il danno indotto da UVA e promuovere la salute della pelle.Ultraviolet radiation, particularly UVA (315–400 nm), is a major contributor to skin photoaging through the induction of oxidative stress, inflammation, and structural damage to dermal components. Effective photoprotection requires a coordinated interplay between endogenous antioxidant defenses and exogenous strategies, including topical formulations and nutritional interventions, aimed at preserving cellular homeostasis under UV exposure. This work explores complementary approaches to enhance skin protection against UVA-induced oxidative damage. Natural and synthetic UV-shielding compounds were investigated for their photoprotective potential, with particular attention to marine-inspired thiol derivatives structurally related to ovothiols and botanical extracts such as honeybush. The role of one-carbon metabolism in skin photoprotection was also examined through the evaluation of 5-methyltetrahydrofolate (5-MTHF) as a systemic supportive strategy. Given the sensitivity of folates to UV radiation and their central involvement in nucleotide biosynthesis and methylation processes, maintaining adequate folate availability may represent a key factor in sustaining cellular repair capacity and redox balance following UV exposure. Additionally, the endogenous antioxidant enzyme paraoxonase-2 (PON2) was investigated as a potential indicator of UVA-induced oxidative stress and cellular adaptive responses, to better characterize cellular redox adaptation and stress-response pathways in skin cells. Building on the studies of UV-shielding compounds and systemic photoprotection, this thesis also explored the development and characterization of cosmetic formulations enriched with aqueous botanical extracts. Plant-derived infusions incorporated into oil-in-water emulsions were characterized to assess their contribution to antioxidant activity, formulation stability, and potential UV-filtering properties. Overall, this thesis analyzed a multidimensional perspective on skin photoprotection, integrating UV-shielding natural compounds, systemic folate metabolism, and topical antioxidant formulations, highlighting the potential of synergistic topical and nutritional strategies to counteract UVA-induced damage and promote skin health
Insights on the UV-Screening Potential of Marine-Inspired Thiol Compounds
Full text linkOne of the major threats to skin aging and the risk of developing skin cancer is excessive exposure to the sun’s ultraviolet radiation (UVR). The use of sunscreens containing different synthetic, organic, and inorganic UVR filters is one of the most widespread defensive measures. However, increasing evidence suggests that some of these compounds are potentially eco-toxic, causing subtle damage to the environment and to marine ecosystems. Resorting to natural products produced in a wide range of marine species to counteract UVR-mediated damage could be an alternative strategy. The present work investigates marine-inspired thiol compounds, derivatives of ovothiol A, isolated from marine invertebrates and known to exhibit unique antioxidant properties. However, their poten- tial use as photoprotective molecules for biocompatible sunscreens and anti-photo aging formulations has not yet been investigated. Here, we report on the UVR absorption properties, photostability, and in vitro UVA shielding activities of two synthetic ovothiol derivatives, 5-thiohistidine and iso- ovothiol A, by spectrophotometric and fluorimetric analysis. We found that the UVA properties of these compounds increase upon exposure to UVA and that their absorption activity is able to screen UVA rays, thus reducing the oxidative damage induced to proteins and lipids. The results of this work demonstrate that these novel marine-inspired compounds could represent an alternative eco-friendly approach for UVR skin protection
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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