Browsing by Author "Bettencourt, Ana F."
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- Biodegradation of acrylic based resins: a reviewPublication . Bettencourt, Ana F.; Neves, Cristina B.; Almeida, Marise S. de; Pinheiro, Lídia M.; Oliveira, Sofia Arantes e; Lopes, Luís P.; Castro, Matilde F.Objectives. The development of different types of materials with application in dentistry is an area of intense growth and research, due to its importance in oral health. Among the different materials there are the acrylic based resins that have been extensively used either in restorations or in dentures. The objective of this manuscript was to review the acrylic based resins biodegradation phenomena. Specific attention was given to the causes and consequences of materials degradation under the oral environment. Data and sources. Information from scientific full papers, reviews or abstracts published from 1963 to datewere included in the review. Published materialwas searched in dental literature using general and specialist databases, like the PubMED database. Study selection. Published studies regarding the description of biodegradation mechanisms, in vitro and in vivo release experiments and cell based studies conducted on acrylic based resins or their components were evaluated. Studies related to the effect of biodegradation on the physical and mechanical properties of the materials were also analyzed. Conclusions. Different factors such as saliva characteristics, chewing or thermal and chemical dietary changes may be responsible for the biodegradation of acrylic based resins. Release of potential toxic compounds from the material and change on their physical and mechanical properties are the major consequences of biodegradation. Increasing concern arises from potential toxic effects of biodegradation products under clinical application thus justifying an intensive research in this área.
- Evaluation of cytotoxicity and oxidative stress induced by acrylic bone cement in raw 264.7 macrophagesPublication . Bettencourt, Ana F.; Fernandes, Ana S.; Oliveira, Nuno G.; Monteiro, Jacinto; Calado, Antonio; Castro, Matilde
- Evaluation of the protective effect of MnTMPyP on the cytotoxicity induced by different oxidant agentsPublication . Fernandes, Ana Sofia; Gaspar, Jorge; Cabral, M. Fatima; Bettencourt, Ana F.; Caneiras, Catla; Rueff, Jose; Castro, Matilde; Costa, Judite; Oliveira, Nuno G.
- Fighting S. aureus catheter-related infections with sophorolipids: electing an antiadhesive strategy or a release one?Publication . Mendes, Rita M.; Francisco, Ana P.; Carvalho, Filomena Almeida; Dardouri, Maissa; Costa, Bruna; Bettencourt, Ana F.; Costa, Judite; Gonçalves, Lidia; Costa, Fabíola; Ribeiro, Isabel A.C.Staphylococcus aureus medical devices related-infections, such as blood stream catheter are of major concern. Their prevention is compulsory and strategies, not prone to the development of resistance, to prevent S. aureus biofilms on catheter surfaces (e.g. silicone) are needed. In this work two different approaches using sophorolipids were studied to prevent S. aureus biofilm formation on medical grade silicone: i) an antiadhesive strategy through covalent bond of sophorolipids to the surface; ii) and a release strategy using isolated most active sophorolipids. Sophorolipids produced by Starmerella bombicola, were characterized by UHPLC-MS and RMN, purified by automatic flash chromatography and tested for their antimicrobial activity towards S. aureus. Highest antimicrobial activity was observed for C18:0 and C18:1 diacetylated lactonic sophorolipids showing a MIC of 50 μg mL-1. Surface modification with acidic or lactonic sophorolipids when evaluating the anti-adhesive or release strategy, respectively, was confirmed by contact angle, FTIR-ATR and AFM analysis. When using a mixture of acidic sophorolipids covalently bonded to silicone surface as antiadhesive strategy cytocompatible surfaces were obtained and a reduction of 90 % on biofilm formation was observed. Nevertheless, if a release strategy is adopted with purified lactonic sophorolipids a higher effect is achieved. Most promising compound was C18:1 diacateylated lactonic sophorolipid that showed no cellular viability reduction when a concentration of 1.5 mg mL-1 was selected and a reduction on biofilm around 5 log units. Results reinforce the applicability of these antimicrobial biosurfactants on preventing biofilms and disclose that their antimicrobial effect is imperative when comparing to their antiadhesive properties.
- Oxidative injury in V79 Chinese hamster cells: protectivePublication . Fernandes, Ana S.; Serejo, João; Gaspar, Jorge; Cabral, Fátima; Bettencourt, Ana F.; Rueff, José; Castro, Matilde; Costa, Judite; Oliveira, Nuno G.Oxidative cell injury could be induced by different reactive oxygen species (ROS) operating in multiple pathways. The present work is focused on three different models of oxidative stress: the xanthine/xanthine oxidase system (XXO), an extracellular superoxide anion generator; tert-butylhydroperoxide (TBHP), an analogue of lipid hydroperoxides; and doxorubicin (Dox), an anticancer drug. Superoxide and peroxyl radicals, among other ROS, could be effectively scavenged by MnTM-4-PyP, a polyfunctional catalytic antioxidant. In this report, we have addressed the role of MnTM-4-PyP on the protection against the cytotoxicity induced by the three aforementioned oxidants. The effect of MnTM-4-PyP (0.1–100 μM) was evaluated in V79 fibroblasts using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide reduction and the crystal violet assays, as well as the mitotic index. Also, the generation of intracellular ROS was studied by the fluorescent probe dihydroethidium. MnTM-4-PyP has shown significant protective effects against the cytotoxicity of XXO and TBHP, increasing the cell viability in approximately 40% and reducing the intracellular level of ROS. However, no considerable protection occurred against Dox. The three oxidants caused a mitotic index reduction that was not altered by MnTM-4-PyP. In summary, MnTM-4-PyP appears to be a promising agent for the protection against oxidative injury. However, it has shown differential responses, reinforcing the need to study different experimental models for the adequate evaluation of its potentialities as a catalytic antioxidant.