A spectrophotometric study on light attenuation properties of dental bleaching gels: potential relevance to irradiation parameters.

open access articleBackground: During in-office bleaching, appropriate light sources are applied in order to enhance the activity of the bleaching gels applied onto teeth. For this method to be effective, a high absorption of light within the gel is necessary. Variation in the light attenuation capability of the gel, the duration of application and light activation can contribute towards safety hazards associated with this procedure. Methods: In this study, seven different gels and hydrogen peroxide have been evaluated for their optical properties by means of spectrophotometry (440–1000 nm). The transmitted light spectrum was used to estimate the intensity loss for each gel. The mean intensity decreases observed were statistically analysed using an analysis of variance (ANOVA). Results: The five more-pigmented gels tested indicated a very similar intensity loss of around 80%, whereas the remaining two gels showed significantly less attenuation (predominantly, p < 10−6). Conclusions: Throughout the spectrum of wavelengths examined, and according to the underlying studies evaluated, five of the gels assessed demonstrated an attenuation high enough to possibly avoid overheating of the underlying enamel dentine and pulp. An evaluation of appropriate irradiation parameters is proposed

Diet and body constitution in relation to subgroups of breast cancer defined by tumour grade, proliferation and key cell cycle regulators

BACKGROUND: The general lack of clear associations between diet and breast cancer in epidemiological studies may partly be explained by the fact that breast cancer is a heterogeneous disease that may have disparate genetic associations and different aetiological bases. METHOD: A total of 346 incident breast cancers in a prospective cohort of 17,035 women enrolled in the Malmö Diet and Cancer study (Sweden) were subcategorized according to conventional pathology parameters, proliferation and expression of key cell cycle regulators. Subcategories were compared with prediagnostic diet and body measurements using analysis of variance. RESULTS: A large hip circumference and high body mass index were associated with high grade tumours (P = 0.03 and 0.009, respectively), whereas low energy and unadjusted fat intakes were associated with high proliferation (P = 0.03 and 0.004, respectively). Low intakes of saturated, monounsaturated and polyunsaturated fatty acids were also associated with high proliferation (P = 0.02, 0.004 and 0.003, respectively). Low energy and unadjusted fat intakes were associated with cyclin D(1 )overexpression (P = 0.02 and 0.007, respectively), whereas cyclin E overexpression was positively correlated with fat intake. Oestrogen receptor status and expression of the tumour suppressor gene p27 were not associated with either diet or body constitution. CONCLUSION: Low energy and low total fat (polyunsaturated fatty acids in particular) intakes, and high body mass index were associated with relatively more malignant breast tumours. Dietary behaviours and body constitution may be associated with specific types of breast cancer defined by conventional pathology parameters and cyclin D(1 )and cyclin E expression. Further studies including healthy control individuals are needed to confirm our results

Assembly of spherical-shaped resistant starch nanoparticles to the oil droplet surface promotes the formation of stable oil in water Pickering emulsions

The use of starch-based nanoparticles in stabilizing Pickering emulsions has gained momentum since it offers a versatile, biocompatible, and sustainable approach with a wide range of applications. In the present study, starch nanoparticles produced using a sequential 3-step physical process were used as particle stabilizers to create Pickering emulsions. According to our results, high amylose starch nanoparticles can provide long-term colloidal stability to Pickering emulsions. The concentration of the particle-based stabilizer affected the size of the droplets, which in turn had an impact on the stability properties of the produced emulsions. By increasing nanoparticle concentration, surface and interfacial tension were reduced, providing the ability to the particles to adsorb at the interface. When starch and oil concentrations were compared using Dynamic Laser Scattering (DLS) and zeta potential, smaller droplets were produced by increasing starch amount and improved stability was depicted. Rheological profiles showed that the emulsion network structure was strengthened by the addition of nanoparticles, increasing the storage (G′) and loss (G″) moduli, as well as viscosity. In conclusion, the produced emulsions can be categorized as Pickering emulsion gels. These networks, specifically at starch nanoparticle concentration of 3% w/v and 5% w/v, have the advantage of preventing phase separation, droplet coalescence, and Ostwald ripening. The formation of a strong gel network was also obtained by Confocal Laser Microscopy (CLSM). All in all, this study provides new insights into the preparation and stabilization of starch-based Pickering emulsions, as the demand for sustainable and eco-friendly solutions in food product development is growing