In vitro enamel remineralization by low-fluoride toothpaste with calcium citrate and sodium trimetaphosphate

The objective of this study was to evaluate in vitro the effect of a low fluoride toothpaste (450 μgF/g, NaF) combined with calcium citrate (Cacit) and sodium trimetaphosphate (TMP) on enamel remineralization. Bovine enamel blocks had the enamel surface polished sequentially to determine the surface hardness. After production of artificial carious lesions, the blocks selected by their surface hardness were submitted to remineralization pH cycling and daily treatment with dentifrice suspensions (diluted in deionized water or artificial saliva): placebo, 275, 450, 550 and 1,100 μgF/g and commercial dentifrice (positive control, 1,100 μgF/g). Finally, the surface and cross-section hardness was determined for calculating the change of surface hardness (%SH) and mineral content (%ΔZ). Fluoride in enamel was also determined. The data from %SH, %ΔZ and fluoride were subjected to two-way analysis of variance followed by Student-Newman-Keuls's test (p<0.05). The mineral gain (%SH and %ΔZ) was higher for toothpastes diluted in saliva (p<0.05), except for the 450 mgF/g dentifrice with Cacit/TMP (p>0.05). The 450 Cacit/ TMP toothpaste and the positive control showed similar results (p>0.05) when diluted in water. A dose-response was observed between fluoride concentration in toothpastes and fluoride present in enamel, regardless of dilution. It was concluded that it is possible to enhance the remineralization capacity of low F concentration toothpaste by of organic (Cacit) and inorganic (TMP) compounds with affinity to hydroxyapatite.

Low tungsten content of nanostructured material supported on carbon for the degradation of phenol

A comparative study using different mass proportions of WO3/C (1%, 5%, 10% and 15%) for H2O2 electrogeneration and subsequent phenol degradation was performed. To include the influence of the carbon substrate and the preparation methods, all synthesis parameters were evaluated. The WO3/C materials were prepared by a modified polymeric precursor method (PPM) and the sol-gel method (SGM) on Vulcan XC 72R and Printex L6 carbon supports, verifying the most efficient metal/carbon proportion. The materials were physically characterized by X-ray diffraction (XRD) and by X-ray photoelectron spectroscopy (XPS) techniques. The XRD and the XPS techniques identified just one phase containing WO3 and elevated oxygen concentration on carbon with the presence of WO3. The oxygen reduction reaction (ORR), studied by the rotating ring-disk electrode technique, showed that WO3/C material with the lowest tungsten content (1% WO3/C), supported on Vulcan XC 72R and prepared by SGM, was the most promising electrocatalyst for H2O2 electrogeneration. This material was then analyzed using a gas diffusion electrode (GDE) and 585mgL-1 of H2O2 was produced in acid media. This GDE was employed as a working electrode in an electrochemical cell to promote phenol degradation by an advanced oxidative process. The most efficient method applied was the photo-electro-Fenton; this method allowed for 65% degradation and 11% mineralization of phenol during a 2-h period. Following 12h of exhaustive electrolysis using the photo-electro-Fenton method, the total degradation of phenol was observed after 4h and the mineralization of phenol approached 75% after 12h. © 2013 Elsevier B.V.

Macauba palm (acrocomia aculeata) cake from biodiesel processing: an efficient and low cost substrate for the adsorption of dyes

The potential of natural and heat-treated Macauba palm cake as adsorbent for the removal of Methylene Blue (MB) and Congo Red (CR) from solution has been investigated. Equilibrium adsorption was attained in <7 h and the process was favored at pH 5.0 for MB and pH 6.5 for CR with an adsorbent (g):adsorbate (mL) ratio of 1:200 and an initial concentration of adsorbate of 25 mg L−1. The maximum adsorption capacities of the natural and heat-treated materials were, respectively, 25.80 and 32.30 mg g−1 for MB, and 32.00 and 20.30 mg g−1 for CR. The isotherm model proposed by Sips represented most adequately the adsorption of MB and CR. The adsorptions of the dyes were best described in terms of a pseudo second-order reaction. Thermodynamic parameters such as ΔHo, ΔSo and ΔGo were calculated. The adsorption process was found to be endothermic and spontaneous. Macauba palm cake is adequate for the removal of waste dye from industrial effluents by virtue of its abundance, low cost and efficiency of adsorption.

Rising concentration in Asia-Latin American value chains: Can small firms turn the tide?

Dynamic Asia has overtaken the European Union as Latin America and the Caribbean’s second largest export market, after the United States. However, the region’s exports to Asia remain concentrated in few commodities involving a small number of large firms. This book explores the present and future scope for the participation of small and medium-sized enterprises (SMEs) in biregional trade and value chains and the measures that can be taken to make those chains more inclusive and sustainable. SMEs have a low direct presence in the region’s export flows and their participation in the supplier networks of multinational companies is weak. This volume reviews several supplier development programmes (SDPs) adopted in various countries in Asia and Latin America to increase SME linkages with multinational firms. These programmes, many of which are public-private initiatives, aim to boost SME productivity and enhance their participation in value chains.

Cytogenetic damage related to low levels of methyl mercury contamination in the Brazilian Amazon

The mercury rejected in the water system, from mining operations and lixiviation of soils after deforestation, is considered to be the main contributors to the contamination of the ecosystem in the Amazon Basin. The objectives of the present study were to examine cytogenetic functions in peripheral lymphocytes within a population living on the banks of the Tapajós River with respect to methylmercury (MeHg) contamination, using hair mercury as a biological indicator of exposure. Our investigation shows a clear relation between methylmercury contamination and cytogenetic damage in lymphocytes at levels well below 50 micrograms/gram, the level at which initial clinical signs and symptoms of mercury poisoning occur. The first apparent biological effect with increasing MeHg hair level was the impairment of lymphocyte proliferation measured as mitotic index (MI). The relation between mercury concentration in hair and MI suggests that this parameter, an indicator of changes in lymphocytes and their ability to respond to culture conditions, may be an early marker of cytotoxicity and genotoxicity in humans and should be taken into account in the preliminary evaluation of the risks to populations exposed in vivo. This is the first report showing clear cytotoxic effects of long-term exposure to MeHg. Although the results strongly suggest that, under the conditions examined here, MeHg is both a spindle poison and a clastogen, the biological significance of these observations are as yet unknown. A long-term follow-up of these subjects should be undertaken.

Effects of Low-Level Laser Therapy on Biceps Braquialis Muscle Fatigue in Young Women

Objective: This study aims to investigate the effects of low-level laser therapy (LLLT) on biceps brachi muscular fatigue in 20 young females. Background data: Exhausting physical activity leads to muscular fatigue, which could decrease muscular strength, and may cause impairment in motor control and muscle pain. Several biochemical and biophysical resources have been studied in an attempt to accelerate the recovery of muscle fatigue. Among these, LLLT is emphasized. Methods: Twenty subjects were randomized in one laser group and one placebo group in two sessions of a crossover design experimental procedure; the second session taking place within 7 days of the first. In the first session, subjects underwent a collection of surface electromyographic (SEMG) data of the biceps brachii muscle, followed by active or placebo LLLT at the same muscle, followed then by another EMG sample of biceps brachii. Blood samples were collected five times during the experimental procedure. Second session procedures were identical to the first, with exception of LLLT, which was the opposite of the first session. The fatigue protocol consisted of 60sec of elbow flexion-extension movement performed with 75% of one maximum repetition. Blood lactate, EMG fatigue, and the number of elbow flexion-extension repetitions during the fatigue protocol were used to evaluate the effects of laser therapy (808nm wavelength, 100mW output power, power density of 35.7 W/cm(2), 70sec each point and 7J/point on eight points). Results: No statistical differences were found for eletromyographic fatigue and blood lactate values between groups. Mean numbers of elbow flexion-extension repetitions were 22.6 +/- 7.58 after placebo, and 25.1 +/- 9.89 after active LLLT group, but these differences were not statistically significant (p=0.342). Conclusions: LLLT had limited effects on delaying muscle fatigue in a young female sample, although a tendency was observed in the active laser group toward showing lower electromyography fatigue of biceps brachii muscle. No intergroup differences were found in the number of muscle contractions and lactate concentration.

Plaque fluoride concentrations associated to the use of conventional and low-fluoride dentifrices

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of low-fluoride toothpastes combined with hexametaphosphate on in vitro enamel demineralization

Objectives: The aim of this study was to evaluate the anticaries effect of low-fluoride toothpastes combined with hexametaphosphate (HMP) on enamel demineralization.Methods: Bovine enamel blocks were subjected to pH cycling and treatment with toothpaste's slurries (15 groups; 2x/day). Toothpaste mixtures contained the following: no fluoride (F) plus HMP (from 0 to 3.0%); 250 ppm F plus HMP (from 0 to 3.0%); 500 ppm F; 1100 ppm F; and a commercial toothpaste (1100 ppm F). After pH cycling, surface and cross-sectional hardness, as well as F present in the enamel were determined. The demineralization depth was analyzed using polarized light microscopy. The variables were subjected to 1-way ANOVA, followed by Student-Newman-Keuls' test (p < 0.05).Results: In the absence of fluoride, 0.5% HMP promoted the lowest mineral loss and its effect was similar to that of a 250 ppm F toothpaste (p > 0.05). The combination of 0.5% HMP and 250 ppm F resulted in lower mineral loss (p < 0.05) and similar lesion depth when compared to the 1100 ppm F toothpaste (p > 0.05).Conclusion: To conclude, the combination of 0.5% HMP and 250 ppm fluoride in a toothpaste has a similar inhibitory effect on enamel demineralization in vitro when compared to a toothpaste containing 1100 ppm F.Clinical significance: The anticaries effect of toothpaste containing 250 ppm F combined with 0.5% HMP was similar to that of a 1100 ppm F toothpaste, despite the 4-fold difference in F concentration. Although such effects still need to be demonstrated in clinical studies, it may be a viable alternative for preschool children. (C) 2013 Elsevier Ltd. All rights reserved.

The effects of low-fluoride toothpaste supplemented with calcium glycerophosphate on enamel demineralization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The negligible effects of the antifungal natamycin on cholesterol-dipalmitoyl phosphatidylcholine monolayers may explain its low oral and topical toxicity for mammals

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rheological behavior of Peruvian carrot starch gels as affected by temperature and concentration

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

In situ evaluation of low-fluoride toothpastes associated to calcium glycerophosphate on enamel remineralization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of the concentration of phenothiazine photosensitizers in antimicrobial photodynamic therapy on bone loss and the immune inflammatory response of induced periodontitis in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tumescent local anesthesia with ropivacaine in different concentrations in bitches undergoing mastectomy: plasma concentration and post-operative analgesia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Long-term low intensity physical exercise attenuates heart failure development in aging spontaneously hypertensive rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)