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In vitro study of the possible biomolecular mechanisms implicated in cyto and genotoxicity induced by several asbestos mineral fibers
Get PDFL'amianto è un termine generico per descrivere specie minerali appartenenti a famiglie di silicati serpentini e anfiboli. L'amianto crisotilo, il più utilizzato al mondo, appartiene alla famiglia dei serpentini, la crocidolite agli anfiboli, con differenze di composizione cristallo-chimica. Nel XX secolo l'amianto è stato utilizzato perché resistente, flessibile e poco costoso. È ritenuto il terzo inquinante più abbondante e di causa malattie amianto correlate. Nonostante riduzioni di utilizzo e divieti in molti paesi, è ancora presente in edifici, siti industriali abbandonati, affioramenti naturali (NOA), miniere e cave. In alcuni paesi è ancora utilizzato ed estratto. Valutazioni di tossicità/cancerogenicità di NOA e di fibre estratte sono quindi altamente raccomandate. Questo studio verte sugli effetti biologici in vitro di i) NOA: crisotilo di Valmalenco (Italia) ed erionite (Nevada, USA); ii) Crisotilo russo da attività estrattive. Gli studi su linee cellulari MeT5A e A549 hanno compreso standard cancerogeni positivi e negativi. Le fibre sono state somministrate in coltura come sospensioni di 50 μg/ml. Aspetti morfostrutturali e vitalità cellulare sono stati valutati con microscopia ottica e MTT test. La produzione intracellulare di specie reattive dell'ossigeno è stata accoppiata alla risposta antiossidante di glutatione. La genotossicità è stata valutata con i: Comet test per stimare il danno al DNA; ii: perturbazione del ciclo cellulare; iii: immunofluorescenza e western blotting di γ-H2AX/RAD51 marcatori di danno/riparazione del DNA. La capacità infiammatoria è stata valutata mediante l’analisi di interleuchine. L'espressione dei miRNA-126 e miRNA-222, biomarcatori di mesotelioma maligno, è stata considerata per la valutazione della pathway tumorale. Tutte le fibre hanno indotto perturbazioni cellulari con risposte diverse dei profili di tossicità. Ulteriori indagini sono quindi auspicabili per comprendere più a fondo i meccanismi dei loro rischi biologici.Asbestos is a generic term to describe mineral species belonging to silicate families of serpentine and amphiboles. Chrysotile asbestos, the most used worldwide, belongs to serpentine family, crocidolite to amphiboles, with differences in crystal-chemical composition. In 20th century asbestos was highly used being resistant, flexible, and inexpensive. It is listed as the third most abundant pollutant causing Asbestos Related Diseases (ARDs). Despite reductions in its use and bans in many countries, asbestos is still present in buildings, abandoned industrial sites, natural outcrops, Naturally Occurring Asbestos, NOA and in mines or quarries. In some countries, China, India, Russia, Brazil, Indonesia, it is still used and mined. Toxicity/carcinogenicity evaluations of NOA and mined fibers are therefore highly recommended. This study deals with in vitro biological effects of i) NOA: Valmalenco chrysotile (Italy); erionite (Nevada, USA); ii) Russian chrysotile from extractive activities R1 and R2. Studies including standards positive and negative carcinogenic were conducted in MeT5A and A549 human cell lines. Fibers were administered in culture as 50μg/ml suspensions. Morphostructural aspects and cell viability were evaluated by light microscopy and MTT assay. Reactive Oxygen Species (ROS) production was coupled to cell glutathione antioxidant response. Genotoxic effects were explored by i: Comet assay to estimate DNA damage; ii: perturbation of cell cycle; iii: immunofluorescence and western blotting of γ-H2AX/RAD51 markers of DNA damage/repair. Inflammatory capacity was assessed by interleukins evaluations. Expression of miRNA-126 and miRNA-222 biomarkers of malignant mesothelioma resulted upregulated in both cell lines, suggesting a role of fibers in tumor progression, particularly with R1 and R2. Results showed fibers different answers of toxic profiles. Further investigations are prominent to deeper understand biological risks mechanisms
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
Sequential one-pot glycosidations catalytically promoted: unprecedented strategy in oligosaccharide synthesis for the straightforward assemblage of the antitumor PI-88 pentasaccharide
No full textA one-pot glycosidation-transient protecting group removal iterable scheme for the rapid assembly of the D1 tetrasaccharide of gp 120
No full textRapid assembly of gp120 oligosaccharide moieties via one-pot glycosidation-deprotection sequences
No full textSynthesis of the mannopeptimycin disaccharide and its conjugation with 4-alkylidene-beta-lactams
No full textThe I2/Et3SiH system: A versatile combination with multiple applications in carbohydrate chemistry
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