1,720,966 research outputs found
Studio sull'induzione di danno al DNA, micronuclei ed alterazioni del ciclo cellulare da condensato di sigaretta
No full textNumerosi studi confermano l’associazione tra fumo di sigaretta e insorgenza di patologie-polmonari, cardiovascolari e tumori. Il fumo, infatti, contiene diversi composti mutageni c cancerogeni. Premesso che non esiste una sigaretta sicura, è comunque possibile attuare strategie per caratterizzare e ridurre il rischio. In questo studio, abbiamo utilizzato test in vitro per investigare i possibili meccanismi d’azione del condensato di sigaretta (CSC), ovvero la frazione particolata del fumo, assorbita nei polmoni del fumatore e successivamente metabolizzata. Analisi precedenti avevano dimostrato che il CSC, dopo 24h di trattamento induce decremento della vitalità delle cellule Swiss3T3 (IC50 = 130 μg/ml), inibizione dell’efficienza di clonaggio (circa il 60% a`50 μg/ml) e attivazione delle caspasi già a partire dalla prima dose testata (25 μg/ml). La natura degli effetti genotossici del CSC è stata analizzata con il Comet assay che ha evidenziato la capacità del CSC di indurre rotture a singolo e doppio filamento del DNA, dopo trattamenti per 90min e 3 h, a partire dalla dose di 100 μg/ml (p<0.001 Kruskall-Wallis). Il significativo aumento (p<0.001 Mann-Whitney U-test`) delle rotture al DNA è stato osservato dopo 90 min di esposizione a 100 e 150 μg/ml di CSC lascia ipotizzare che la componente ossidativa del danno indotto da CSC venga rapidamente riparata. Il saggio del micronucleo è stato effettuato su cellule trattate con 30 μg/ml di CSC e osservate immediatamente dopo il trattamento e fino a 120h di coltura in terreno completo senza condensato. I risultati ottenuti hanno evidenziato un aumento significativo (p<0.005 t-Student) di cellule micronucleate dopo 72h di recupero. Utilizzando anticorpi anti-nucleari (ANA test) contro il cinetocore è stato possibile mettere in evidenza che il trattamento con CSC esplica prevalentemente un effetto clastogeno. La comparsa dei micnonuclei solo dopo 72h dal trattamento sembra essere correlata al ritardo nella progressione del ciclo cellulare come indicano sia il decremento di cellule in mitosi osservato subito dopo il trattamento, sia l’accumulo dose-dipendente di cellule in G2/M
Evaluation of DNA damage in murine fibroblasts treated with cigarette smoke condensate
No full textCSC is a complex chemical mixture containing about 4800 compounds, many of them have cytotoxic and mutagenic activities on mammalian cells. Most of these compounds are able to interact with DNA at different levels. Cells may respond to DNA damage by following different pathways, such as the DNA repair processes and the cell cycle and DNA damage checkpoint activation.
To the aim to evaluate the biological effects of CSC on cells, alkaline comet assay and flow cytofluorimetry were used to examine DNA damage/repair and cell cycle progression. All experiments were performed by using CSC from standard cigarettes in the range of doses 30-180g/ml and Swiss 3T3 murine fibroblasts.
Results obtained by comet assay showed that CSC induces DNA strand breaks, significantly higher after 90 min of treatment than 3hrs. This difference, particularly evident at 100 and 150g/ml, it is probably due to a fast repair that can be explained by the oxidative component of the DNA damage CSC-induced. To clarify these results, further investigations on the evaluation of the oxidative damage are in progress by applying two different methods. one is the detection of the oxidised bases on the DNA by using the modified protocol of Comet assay with FPG and endo III, the second is the analysis of the intracellular levels of ROS, measured as the ability of treated cells to oxidise a fluorogenic dye, is going to be carried out.
Previous results of long-term survival showed that cells lose their ability to form colonies in dose-dependent manner, after 24hrs of CSC treatment and 168 hrs of culture. However, the cytofluorimetric analysis showed that a fraction of cells, blocked in G2/M immediately after 24hrs of treatment, are gradually granted to continue the cell cycle, after incubation for further 6hrs in medium CSC-free. Further investigations on the cell cycle alteration are on going
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
Development of hybrid materials based on hydroxyethylmethacrylate as supports for improving cell adhesion and proliferation
No full textA novel hydrogel based on 2-hydroxyethylmethacrylate and fumed silica nanoparticles is presented. The filler was mixed at increasing amount (3-40% w/w) to the organic monomer, before accomplish thermal polymerization. The hybrid composite materials obtained were characterized as far as concern the physical-chemical stability and sorption behaviour in water and water solutions. The novel hybrid hydrogels were compared to poly(hydroxyethylmethacrylate) (pHEMA) on cytocompatibility and ability to elicit cell adhesion and proliferation. These in vitro assays showed that the first ones were supporting cell growth better then pHEMA, moreover experiments on murine fibroblasts showed improved adhesion and proliferation with the increase of the nanomeric filler content. For a more physiological response, the in vitro tests should match biomaterials with cell populations typical of the implant site. Therefore, in view of future applications of these composites as scaffolds for bone engineering, in a successive step of our research we selected primary cultures of human osteoblasts (OB) as the most appropriate models to study the in vitro performance of these materials. The preliminary results obtained confirmed the remarkable improvement of OB adhesion properties of the new hybrids with respect to pure pHEMA
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