Effect of pH and titratable acidity on enamel and dentine erosion.

OBJECTIVES: The relative effect of pH and titratable acidity on tooth erosion remains unclear. We determined the effect of both properties on in vivo salivary pH recovery and on enamel and dentine early erosion in situ. METHODS: Solutions simulating acidic beverages with different pHs (2.5 or 3.5) and titratable acidities (0, 25, or 100 mM citric acid) were tested. In an in vivo study (n = 20 participants), the salivary pH was determined before, during, and up to 2 min after exposure to the tested solutions. In situ, 12 participants exposed enamel and root dentine slabs to the tested solutions simulating a beverage consumption; early erosion was assessed by percentage of surface hardness loss (%SHL). Groups were compared by ANOVA (p < 0.05). RESULTS: Saliva pH was lower after exposure to solutions at pH 2.5, irrespective of titratable acidity; pH recovery took longer for solutions with higher titratable acidities, irrespective of their pHs. In situ, the highest %SHL was observed for the solution with lower pH and higher titratable acidities. The addition of citric acid increased the %SHL by 2.5-3 times in enamel, and at least 5 times in dentine. CONCLUSIONS: Both pH and titratable acidity may play a role on the erosive potential of acidic beverages. CLINICAL RELEVANCE: Acidic beverages with lower pHs promote erosion by an initial acid etching of the surface; those with a higher titratable acidity slow down the salivary pH recovery. Both properties contribute to the overall erosive potential.

Changes in Ca2+ Removal Can Mask the Effects of Geometry During IP3R Mediated Ca2+ Signals.

Calcium (Ca2+) signals are ubiquitous. Most intracellular Ca2+ signals involve the release of Ca2+ from the endoplasmic reticulum (ER) through Inositol 1,4,5-Trisphosphate Receptors (IP3Rs). The non-uniform spatial organization of IP3Rs and the fact that their individual openings are coupled via cytosolic Ca2+ are key factors for the variety of spatio-temporal distributions of the cytosolic [Ca2+] and the versatility of the signals. In this paper we combine experiments performed in untreated and in progesterone-treated Xenopus laevis oocytes and mathematical models to investigate how the interplay between geometry (the IP3R spatial distribution) and dynamics (the processes that characterize the release, transport, and removal of cytosolic Ca2+) affects the resulting signals. Signal propagation looks more continuous and spatially uniform in treated (mature) than in untreated (immature) oocytes. This could be due to the different underlying IP3R spatial distribution that has been observed in both cell types. The models, however, show that the rate of cytosolic Ca2+ removal, which is also different in both cell types, plays a key role affecting the coupling between Ca2+ release sites in such a way that the effect of the underlying IP3R spatial distribution can be modified.

Beta-alanine supplementation enhances judo-related performance in highly-trained athletes.

OBJECTIVES: In official judo competitions, athletes usually engage in 5-7 matches in the same day, performing numerous high-intensity efforts interspersed by short recovery intervals. Thus, glycolytic demand in judo is high and acidosis may limit performance. Carnosine is a relevant intracellular acid buffer whose content is increased with beta-alanine supplementation. Thus, we hypothesized that beta-alanine supplementation could attenuate acidosis and improve judo performance. DESIGN: Twenty-three highly-trained judo athletes were randomly assigned to receive either beta-alanine (6.4gday-1) or placebo (dextrose, same dosage) for 4 weeks. METHODS: Performance was assessed before (PRE) and after (POST) supplementation through a 5-min simulated fight (randori) followed by 3 bouts of the Special Judo Fitness Test (SJFT). Blood samples were collected for blood pH, bicarbonate (HCO3-) and lactate determination. RESULTS: Beta-alanine supplementation improved the number of throws per set and the total number of throws (both p<0.05). Placebo did not change these variables (both p>0.05). Blood pH and HCO3- reduced after exercise (all p<0.001), with no between-group differences (all p>0.05). However, the lactate response to exercise increased in the beta-alanine group as compared to placebo (p<0.05). CONCLUSIONS: In conclusion, 4 weeks of beta-alanine supplementation effectively enhance judo-related performance in highly-trained athletes.

Insecticide concentrations in stream sediments of soy production regions of South America.

Concentrations of 17 insecticides were measured in sediments collected from 53 streams in soy production regions of South America (Argentina in 2011-2014, Paraguay and Brazil in 2013) during peak application periods. Although environmental regulations are quite different in each country, commonly used insecticides were detected at high frequencies in all regions. Maximum concentrations (and detection frequencies) for each sampling event ranged from: 1.2-7.4 ng/g dw chlorpyrifos (56-100%); 0.9-8.3 ng/g dw cypermethrin (20-100%); 0.42-16.6 ng/g dw lambda-cyhalothrin (60-100%); and, 0.49-2.1 ng/g dw endosulfan (13-100%). Other pyrethroids were detected less frequently. Banned organochlorines were most frequently detected in Brazil. In all countries, cypermethrin and/or lambda-cyhalothrin toxic units (TUs), based on Hyalella azteca LC50 bioassays, were occasionally>0.5 (indicating likely acute toxicity), while TUs for other insecticides were <0.5. All samples with total insecticide TU>1 were collected from streams with riparian buffer width<20 m. A multiple regression analysis that included five landscape and habitat predictor variables for the Brazilian streams examined indicated that buffer width was the most important predictor variable in explaining total insecticide TU values. While Brazil and Paraguay require forested stream buffers, there were no such regulations in the Argentine pampas, where buffer widths were smaller. Multiple insecticides were found in almost all stream sediment samples in intensive soy production regions, with pyrethroids most often occurring at acutely toxic concentrations, and the greatest potential for insecticide toxicity occurring in streams with minimum buffer width<20 m.

Titratable acidity of beverages influences salivary pH recovery

A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conductedin vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control) were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively) and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and < 0.005 mmols OH- to reach pH 5.5, respectively). Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

Dental caries and related factors in Brazilian children from fluoridated and non-fluoridated areas / Cárie dentária e fatores relacionados em crianças brasileiras de região com água fluoretada e não fluoretada

Purpose: To compare the caries prevalence, saliva buffering capacity (SBC), oral hygiene (OH), dietary habits, family income (FI) and frequency of visits to a dental office (Do) between Brazilian children living in areas with and without fluoridated public water supply. Methods: Forty-six 5-7-year-old preschoolers were selected in Itatiba, SP, Brazil; 19 were from a fluoridated area, and 27 were from a non-fluoridated area. The caries index was determined according to the World Health Organization criteria, and the SBC was assessed by titration with hydrochloric acid. The FI, frequency of OH and visits to Do were estimated by questionnaire. The dietary habits were assessed with a diet chart. The differences between the groups were analyzed with Mann-Whitney-U tests (α=0.05). Results: Children from the non-fluoridated area showed significantly higher dmft/DMFT than those from the fluoridated area, but they showed significantly lower SBC, OH frequency and FI. No significant differences were observed between the areas for dietary habits and visits to Do. Conclusion: Children from fluoridated areas showed higher salivary buffering capacity, family income and oral hygiene frequency as well as lower caries prevalence, supporting the beneficial effect of fluoride in the tap water for caries prevention.

Objetivo: Comparar prevalência de cárie, capacidade tamponante da saliva (CTS), higiene bucal (HB), hábitos dietéticos, renda familiar (RF) e frequência de visita a consultórios odontológicos (Co) entre crianças brasileiras residentes em áreas de água de abastecimento público fluoretadas e não fluoretadas. Metodologia: Quarenta e seis crianças entre 5-7 anos foram selecionadas em Itatiba-SP-Brasil, sendo 19 pertencentes à área fluoretada e 27 à área não fluoretada. O índice de cárie foi determinado de acordo com o critério da Organização Mundial de Saúde e a CTS foi medida por titulação com ácido clorídrico. A RF, frequência de HB e visita ao Co foram estimadas por questionário. Os hábitos dietéticos foram avaliados com diário de dieta. As diferenças entre as variáveis foram analisadas pelo teste de Mann Whitney (α=0,05). Resultados: As crianças da área não fluoretada apresentaram significativamente maior ceod/CPOD que àquelas da área fluoretada, porém significativamente menor CTS, HB e RF. Com relação a hábitos dietéticos e visitas ao Co, não foi observada diferença significativa entre as áreas. Conclusão: As crianças da área fluoretada apresentaram maior capacidade tamponante da saliva, renda familiar e frequência de higiene bucal, assim como menor prevalência de cárie, reforçando o efeito benéfico do flúor nas águas de abastecimento para prevenir a cárie.

Cobertura e uso do solo e sua influência na ocorrência de raiva nos municípios de Jacareí e Santa Branca, Vale do Paraíba, Estado de São Paulo, entre 2002 e 2009 / Influence of landscape and land use on the occurrence of rabies in the municipalities of Jacareí and Santa Branca, Vale do Paraíba, State of São Paulo, between 2002 and 2009

Objetivo: Realizou-se um estudo, no período de 2002 a 2009, com a finalidade de verificar se as mudanças nas classes de cobertura da terra e no uso do solo podem exercer influência na ocorrência da raiva, nos municípios de Jacareí e de Santa Branca, situados na Região do Vale do Paraíba, no Estado de São Paulo, Sudeste do Brasil. Métodos: A ferramenta utilizada para avaliar estas alterações foi o sensoriamento remoto, através de imagens de satélite Land-sat. Para pesquisar a presença do vírus da raiva (RABV) foram coletados animais silvestres atropelados nas rodovias, morcegos encontrados na área urbana em atitude suspeita, morcegos hematófagos da espécie Desmodus rotundus e animais de interesse econômico (ADIE) que vieram a óbito por enfermidade com sintomatologia nervosa. O material coletado, sistema nervoso central (SNC), desses animais foi encaminhado para o laboratório de referência nacional, o Instituto Pasteur de São Paulo (IP-SP) e para o Laboratório de Sanidade Animal da Agência Paulista de Tecnologia dos Agronegócios (APTA)- Pólo Regional do Vale Paraíba (PRDTA/VP) - Pindamonhangaba-SP. A determinação da presença do antígeno viral foi feita através da prova de imunofluorescência direta (IFD) e o isolamento do vírus através da inoculação intracerebral em camundongos (IC). Os inóculos das amostras foram submetidos à prova de reação em cadeia pela polimerase transcriptase reversa (RT-PCR) para verificar a presença do vírus da raiva. Resultados: No período de estudo tivemos a ocorrência de dez casos da doença, sendo três em morcegos insetívoros na zona urbana de Jacareí, e sete em ADIE, sendo dois, em Jacareí e cinco, em Santa Branca. Todos os animais silvestres terrestres examinados foram negativos para a presença do vírus da raiva em todas as provas realizadas (IFD, IC, RT-PCR)...

Objective: This study was carried out during the period of 2002-2009, with the purpose to verify whether the changes in types of land cover and in land use can influence the occurrence of rabies in Jacareí and Santa Branca, situated in the Vale do Paraíba, State of São Paulo, southeastern brazil. Methods: The tool used to evaluate these alterations was the remote sensing through images of satellite land-sat. In order to search for the presence of rabies virus, brain materials were collected from wild animals roadkilled in highways, bats found in the urban area in suspicious attitude, desmodus rotundus hematophagous bats captured in rural areas and farm animals of economic importance (aei) dead with suspect of rabies. For rabies diagnosis, specimens of central nervous system (cns) of these animals were sent to the Pasteur Institute of São Paulo (IP-SP) - national reference laboratory and to the laboratory of animal Paulista Agency for Agribusiness Technology (APTA) - Polo Valley Regional of Paraíba (PRDTA / VP), in Pindamonhangaba, state of SP. The presence of viral antigen was determined by the direct fluorescent antibody technique (D-FAT) and the isolation of the virus by means of intracerebal mouse inoculation test (MIT). The brain suspensions were submitted to reverse transcriptase. Polymerase chain reaction to check the presence of rabies virus. Results: In the period of study, 10 positive cases were detected, being 3 in insectivorous bats in the urbane zone of jacareí, and 7 in aei, being 2 in jacareí and 5 in santa branca. All the terrestrial wild animals examined were negative for the presence of rabies virus in all tests performed (d-fat, mit, and rt-pcr)...