927 resultados para ageing - ethnology
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The aim of the present study was to evaluate the effect of disinfection and accelerated ageing on the dimensional stability and detail reproduction of a facial silicone with different types of nanoparticle. A total of 60 specimens were fabricated with Silastic MDX 4-4210 silicone and they were divided into three groups: colourless and pigmented with nanoparticles (make-up powder and ceramic powder). Half of the specimens of each group were disinfected with Efferdent tablets and half with neutral soap for 60 days. Afterwards, all specimens were subjected to accelerated ageing. Both dimensional stability and detail reproduction tests were performed after specimen fabrication (initial period), after chemical disinfection, and after accelerated ageing periods (252, 504 and 1008 hours). The dimensional stability test was conducted using AutoCAD software, while detail reproduction was analysed using a stereoscope magnifying glass. Dimensional stability values were statistically evaluated by analysis of variance (ANOVA) followed by Tukey's test (p < 0.01). Detail reproduction results were compared using a score. Chemical disinfection and also accelerated ageing affected the dimensional stability of the facial silicone with statistically significant results. The silicone's detail reproduction was not affected by these two factors regardless of nanoparticle type, disinfection and accelerated ageing. © 2012 Informa UK, Ltd.
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Background: Aging is associated with complex and constant remodeling of the immune function, resulting in an increasing susceptibility to infection and others diseases. The infections caused by Gram-negative microorganisms, present in nursing homes and hospitals, constitute one of the most common infections in the elderly, and are mainly combated by innate immune cells. Although the functions of innate immunity seem more preserved during aging than of adaptive immune mechanisms, two systems operate in an integrated way in the body, so that injury in one part of the immune system inevitably affects the other as they are part of a defensive network. The aim of this study was to investigate the in vitro production of proinflammatory (TNF-α, IL-6, IL-1β, CXCL-8 and MCP-1) and anti-inflammatory (TGF-β and IL-10) cytokines by monocytes, stimulated or not (basal) with lipopolysaccharide, from healthy young and elderly subjects. By means of PBMCs, we also studied if cytokine profile is altered in these different patient groups, in the presence of lymphocytes, under the same experimental conditions.Results: The monocytes from elderly presented higher basal production of TNF-α, MCP-1 and lower of TGF-β than young monocytes. PBMC showed similar cytokines production, irrespective age or stimulation presence. In the presence of lymphocytes, the spontaneous production of IL-10 was higher and of TGF-β was lower than monocytes, regardless of age. After LPS-stimulation, the presence of lymphocytes resulted in increased IL-6, IL-1β, MCP-1 and IL-10 and decreased CXCL-8 and TGF-β in comparison to pure culture of monocytes from young patients. With age, the same differences were observed, except for CXCL-8 and TGF-β which production was the same between monocytes and PBMC stimulated with LPS.Conclusion: These findings reinforce the systemic state of inflamm-aging frequently reported in elderly and considered a factor of susceptibility to numerous diseases. Still, the cytokine production from just monocytes of the elderly showed alterations, while in the lymphocyte presence not, suggesting an immunomodulator role of lymphocytes on monocytes. In addition, the differences between the production patterns by LPS-stimulated PBMC between young and elderly volunteers can be related with an imbalance in response against Gram-negative bacteria in throughout life. © 2013 Pinke et al.; licensee BioMed Central Ltd.
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Cellulose micro and nano fibrils were extracted from banana macro fibres and chemically modified using sodium hydroxide, formic acid, 3-methacryloxy propyltrimethoxy silane. These untreated and chemically treated fibrils were incorporated into PF resin and the specimens were prepared. The composites were subjected to long-term water ageing, thermal ageing soil burial and outdoor weathering. The mechanical properties are reduced under all ageing conditions. The present study investigates the effects of different types of ageing on macro fibre, microfibril and nanofibril reinforced PF composites. The effect of chemical modifications of fibres on the degradability of the composites at different environments also has been analysed. © 2013 Elsevier B.V.
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Objectives: This study evaluated the microtensile bond strength (MTBS) of non-aged and aged resin-based composites (RBC) (nanohybrid and nanofilled) after two surface conditioning methods, repaired using the composite of the same kind or a microhybrid composite. Materials and methods: Nanohybrid (Tetric EvoCeram-TE) and nanofilled (Filtek Supreme-FS) RBC blocks (5 × 5 × 6 mm) (N = 128) were fabricated and randomly divided into two groups: (a) no ageing (control group) and (b) ageing (5.000 thermocycling, 5-55 °C). RBC surfaces were polished by up to 1,200-grit silicone carbide papers and conditioned with either (a) air abrasion with 30-μm SiO2 particles (CoJet Sand) for 4 s + silane coupling agent (ESPE-Sil) + adhesive resin (VisioBond) (n = 16) or (b) adhesive application only (Multilink A+B for TE; Adper ScotchBond 1XT for FS) (n = 16). In half of the groups, repair resin of the same kind with the RBC and, in the other half, a different kind of composite (microhybrid, Quadrant Anterior Shine-AS) with its corresponding adhesive (Quadrant UniBond) was used. The specimens were submitted to MTBS test (0.5 mm/min). Data were analysed using three-way ANOVA and Tukey's tests. Degree of conversion (DC) of non-aged and aged resin composites (TE, FS) (n = 3 per group) was measured by micro-Raman analyses. Results: RBC type (p = 0.001) and ageing affected the MTBS results significantly (p = 0.001). Surface conditioning type did not show significant difference (p = 0.726), but less number of pre-test failures was experienced with the CoJet system compared to adhesive resin application only. Repair strength on aged TE showed significantly less (p < 0.05) MTBS than for FS. FS repaired with the same kind of RBC and adhesive resin presented the highest cohesive failures (43 %). DC was higher for TE (71 %) than for FS (58 %) before ageing. Conclusion: On the aged RBCs, less favourable repair strength could be expected especially for nanohybrid composite. For repair actions, RBC surface conditioning could be accomplished with either adhesive resin application only or with CoJet system, providing that the latter resulted in less pre-test failures. Clinical relevance: Clinicians could condition the resin surface prior to repair or relayering with either CoJet system or adhesive resin application only, depending on the availability of the system. © 2012 Springer-Verlag Berlin Heidelberg.
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Spanish version available at the Library
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Includes bibliography
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Includes bibliography
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Spanish version available at the Library (146537)
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Spanish version available at the Library
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Spanish version available at the Library
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Spanish version availanle at the Library
