Comparação do efeito de beta alanina, bicarbonato de sódio e limão como agentes tamponantes entre ciclistas em exercício de alta intensidade / Comparison of the effect of beta alanine, sodium bicarbonate and lemon as tamponant agents among high-intensity exercise cyclists

Alguns suplementos exercem atividade tamponante e têm sido reconhecidos por sua contribuição anaeróbica em exercícios de alta intensidade, retardando a fadiga muscular periférica e potencializando assim a performance esportiva. O objetivo deste estudo foi comparar o benefício ergogênico no tamponamento e dano muscular, dos suplementos beta alanina, bicarbonato de sódio e suco de limão por meio da dosagem de lactato sanguíneo e creatinofosfoquinase (CPK) e na performance de ciclistas submetidos a exercício anaeróbico de alta intensidade. Estudo transversal crossover, realizado em quatro etapas, com ciclistas do sexo masculino. A suplementação foi constituída de 6 g de beta alanina, 0,2 g/kg de bicarbonato de sódio e 30 mL de suco de limão. Lactato sanguíneo e enzima CPK foram dosados pelo método teste ultravioleta enzimático e cinético, respectivamente, em cada uma das etapas. A performance correspondeu à rotação máxima por minuto (RPM) da Air Bike. Participaram do estudo sete ciclistas, com média de idade de 31,14 ± 3,71 anos. O lactato e a CPK apresentaram significância entre os momentos em todas as etapas avaliadas, porém as suplementações comparadas entre si não apresentaram diferença estatística. Não houve melhora da performance (p>0,05) com as utilizações de bicarbonato de sódio, beta alanina e suco de limão em ciclistas. Para os parâmetros avaliados, nenhum dos suplementos apresentou superioridade nas variáveis de tamponamento, dano muscular e performance no treinamento.

Some supplements exert buffering activity and have been recognized for their anaerobic contribution to high-intensity exercise, delaying peripheral muscle fatigue and thus enhancing sports performance. The aim of this study was to compare the ergogenic benefit in muscle buffering and damage of beta alanine, sodium bicarbonate and lemon juice supplements through the measurement of blood lactate and creatine phosphokinase (CPK) and on the performance of cyclists submitted to high intensity anaerobic exercise. Cross-sectional study, carried out in 4 stages, with male cyclists. Supplementation was 6 g beta alanine, 0.2 g/kg of sodium bicarbonate and 30 mL of lemon juice. Blood lactate and creatine phosphokinase enzyme were measured by the enzymatic and kinetic ultraviolet test method, respectively, in each of the steps. Performance corresponded to the maximum rotation per minute (RPM) of the Air Bike. Seven cyclists participated in the study, with a mean age of 31.14 ± 3.71 years. Lactate and CPK presented significance between the moments in all the evaluated stages, however the supplements compared to each other showed no statistical difference. There was no performance improvement (p>0.05) with the use of sodium bicarbonate, beta alanine and lemon juice in cyclists. For the parameters evaluated, none of the supplements showed superiority in the variables of buffering, muscle damage and training performance.

Bases moleculares da absorção de nutrientes, tamponamento e fluxos de fluídos no intestino médio de Musca domestica / Molecular bases of nutrient absorption, buffering and fluid fluxes in the midgut of Musca domestica

O intestino dos insetos representa uma interface pouco protegida dos agentes externos. A identificação dos mecanismos moleculares envolvidos nos processos fisiológico-digestivos permite encontrar alvos potenciais para o controle de insetos. As moléculas envolvidas na absorção de nutrientes, tamponamento e geração de fluxos de água no intestino médio do inseto-modelo Musca domestica (Diptera Cyclorrhapha) foram identificadas. Para isso, foi feita uma análise da expressão gênica ao longo do intestino médio, a identificação e anotação de proteínas por bioinformática, a confirmação da localização apical das proteínas por análise proteômica de membranas microvilares purificadas e a determinação do papel de algumas das proteínas através de experimentos in vivo utilizando diferentes dietas, corantes e inibidores. A acidificação da região média é consequência da atividade anidrase carbônica que gera prótons que são bombeados por uma H+ V-ATPase apical acompanhados por cloreto transportado por um simporter K+Cl-. O K+ é recuperado por um canal de K+ e a homeostase dos cátions mantida pela Na+/K+-ATPase basolateral. O bicarbonato é eliminado basolateralmente em troca por cloreto por um antiporter. A acidificação é regulada diretamente por um antiporter Na+/H+ e indiretamente por uma proteína envolvida na homeostase do cobre. O muco protetor da região média é tamponado com bicarbonato gerado por uma anidrase carbônica com âncora de GPI e transportado por um antiporter Na+HCO3-/H+Cl-. O excesso de ácido é eliminado por um antiporter Na+/H+ situado na membrana basolateral. A alcalinização da região posterior ocorre pelo transporte apical de NH3 que sequestra os prótons luminais gerando amônio, junto à remoção de prótons em simporte com aminoácidos e peptídeos. A acidificação intracelular, consequência da entrada de aminoácidos com prótons, é regulada por uma H+ V-ATPase basolateral. A geração de fluxos de água é consequência da atividade conjunta de simporters NKCC e KCC ajudados pelas aquaporinas. A inibição dos simporters com inibidores específicos mostrou que o contrafluxo de água está envolvido na reciclagem da enzima tripsina. Por último, o principal lugar de absorção nutrientes no intestino médio é a região posterior, a exceção do cobre que é absorvido na região média

The gut of insects is a less protected interphase against external agents. The identification of the molecular mechanisms involved in physiological-digestive processes allows one to find potential targets for insect control. The molecules involved in nutrient absorption, buffering and fluid fluxes in the midgut of the insect-model M. domestica (Diptera Cyclorrhapha) were identified. For this, gene expression along the midgut was analyzed; proteins were identified and annotated by bioinformatics; apical localization of proteins was confirmed by proteomics of purified microvillar membranes; the role of proteins was confirmed by in vivo experiments using different diets, dyes and inhibitors. Middle midgut acidification occurs by the action of an apical H+ V-ATPase with protons coming from carbonic anhydrase activity accompanied by chloride transported with potassium by a K+Cl- symporter. Potassium is recovered by a potassium channel, and cation homeostasis maintained by a basolateral Na+/K+-ATPase. Acidification is directly regulated by a Na+/H+ antiporter and indirectly by a copper homeostasis protein. Mucus protecting epithelium is neutralized with bicarbonate generated by a GPI-ancored carbonic anhydrase and transported by a Na+HCO3-/H+Cl- antiporter. Intracellular acidification is avoided by a basolateral Na+/H+ antiporter. Posterior midgut alkalization occurs by the action of an apical ammonia transporter and proton amino acid (and peptide) symporters. Intracellular acid is eliminated by a basolateral H+ V-ATPase. Fluid fluxes are generated by K+Cl- and Na+Cl-Cl- symporters helped by aquaporins. Inhibition of these symporters showed that the countercurrent flux of water allows trypsin recycling. Finally, posterior midgut is the main location of nutrient absorption, except for copper which is absorbed in the middle midgut

Adsorption and availability of phosphorus in response to humic acid rates in soils limed with CaCO3 or MgCO3 / Adsorção e disponibilidade de fósforo em resposta a doses de ácido húmico em solos corrigidos por CaCO3 ou MgCO3

ABSTRACT Humic acid (HA) may reduce adsorption and increase soil P availability, however, the magnitude of this effect is different when Ca2+ prevails over Mg2+ in limed soils. The objective of this study was to evaluate the effects of HA rates and carbonate sources on the adsorption, phosphate maximum buffering capacity (PMBC), and P availability in two contrasting soils. Oxisol and Entisol samples were firstly incubated with the following HA rates: 0, 20, 50, 100, 200 and 400 mg kg-1, combined with CaCO3 or MgCO3, to evaluate P adsorption. In sequence, soil samples were newly incubated with P (400 mg kg-1) to evaluate P availability. The least P adsorption was found when 296 mg kg-1 of HA was added to Oxisol. Applying HA rates decreased maximum adsorption capacity, increased P binding energy to soil colloids and did not alter PMBC of Entisol. Available P contents in Oxisol increased with HA rates, but it did not change in Entisol. Choosing the right HA rate can decrease PMBC up to 40% and increase the Oxisol P availability by 17%. Application of MgCO3 instead of CaCO3 decreased P adsorption in both soils. Thus, a positive correlation between Ca2+ content and PMBC was verified. Optimum rate of HA and the preponderance of Mg2+ instead of Ca2+ in soil volume fertilized with P are effective practices to reduce adsorption and increase P availability, especially in clayey Oxisol.

RESUMO O ácido húmico (AH) pode reduzir a adsorção e aumentar a disponibilidade de P nos solos, entretanto, a magnitude desse efeito é diferente quando o Ca2+ prevalece sobre Mg2+ em solos com acidez corrigida. Objetivou-se avaliar os efeitos de doses de AH e fontes de carbonato na adsorção, fator capacidade de P máximo (FCPm) e disponibilidade de P em solos contrastantes. Amostras de Latossolo e Gleissolo foram primeiramente incubadas com as seguintes doses de AH: 0, 20, 50, 100, 200 e 400 mg kg-1, combinadas com CaCO3 ou MgCO3, para avaliar a adsorção de P. Em sequência, as amostras de solo foram novamente incubadas com P (400 mg kg-1), para determinar a disponibilidade de P. A aplicação de doses de AH reduziu a capacidade máxima de adsorção, aumentou a energia de ligação do P e não alterou a FCPm do Gleissolo. O teor de P disponível aumentou com o acréscimo das doses de AH no Latossolo, contudo, não foram alterados no Gleissolo. A escolha correta da dose de AH reduziu a FCPm em até 40% e aumentou a disponibilidade de P no Latossolo em 17%. A aplicação de MgCO3 em vez do CaCO3 reduziu a adsorção de P em ambos os solos. Assim, houve correlação positiva entre o teor de Ca2+ e a FCPm. A dose ótima de AH e a predominância de Mg2+ sobre Ca2+ no volume de solo adubado com P são práticas efetivas para reduzir a adsorção e aumentar a disponibilidade de P, especialmente, no Latossolo argiloso.

Qualitative and quantitative salivary changes and subjective oral dryness among patients with thyroid dysfunction

There is a paucity of literature regarding the effects of thyroid disorders on the oral cavity by influencing the salivary gland function. Aims: This study aims to understand the qualitative and quantitative changes that thyroid disorder can cause in the salivary function. Settings and Design: After obtaining ethical clearance, 46 consecutive newly diagnosed thyroid dysfunction patients were enrolled in this cross-sectional study, along with 45 age-and sex-matched controls. Subjects and Methods: Unstimulated and stimulated salivary flow rates, pH, and buffering capacity of the whole saliva were studied in addition to subjective oral dryness in the study participants. Statistical Analysis Used: The independent t-test was employed to compare the means between the two groups and Pearson's Chi-square test was used to assess the goodness of fit. Results: The findings showed that females are more affected with thyroid disorders and that hypothyroidism is more commonly reported than hyperthyroidism. A significant reduction in the salivary flow rates and buffering capacity was observed among the affected group compared to the controls, whereas the salivary pH did not show significant differences between genders and also between the case and control groups. A feeling of subjective oral dryness was perceived by many affected patients. Conclusions: The study was able to establish an association between thyroid dysfunction and salivary gland function. We hope that this study leads to more high-impact research in this field as salivary diagnostics is gaining more popularity with every passing day.

Real-time Event Recognition and Analysis System for Nanopore Study / 分析化学

To achieve fast and accurate analysis of weak current signal of nanopore-based single molecule detection, we designed a real-time adaptive threshold data processing algorithm with data buffering technique and finite impulse response filtering. The system, which is designed based on the data processing algorithm, could realize real-time recognition and analysis of nanopore events during the data recording process. In order to verify the performance of the system, the ideal signals with different noise level (20-100 pA) and recording bandwidth (3 - 100 kHz) was generated. The results showed that the system was stable to analyze the generated signals even at high noise. In addition, the system was also suitable for the data recording conditions of low bandwidth and high sampling rate (250 kHz). The proposed nanopore data processing system was further applied in the Aerolysin nanopore experiment for the detection of poly(dA) 4 molecules. The results showed that the data processing system could be applied in real nanopore recording system with high accuracy and speed.

Differential Expression of Ca²⁺-buffering Protein Calretinin in Cochlear Afferent Fibers: A Possible Link to Vulnerability to Traumatic Noise

The synaptic contacts of cochlear afferent fibers (CAFs) with inner hair cells (IHCs) are spatially segregated according to their firing properties. CAFs also exhibit spatially segregated vulnerabilities to noise. The CAF fibers contacting the modiolar side of IHCs tend to be more vulnerable. Noise vulnerability is thought to be due to the absence of neuroprotective mechanisms in the modiolar side contacting CAFs. In this study, we investigated whether the expression of neuroprotective Ca²⁺-buffering proteins is spatially segregated in CAFs. The expression patterns of calretinin, parvalbumin, and calbindin were examined in rat CAFs using immunolabeling. Calretinin-rich fibers, which made up ~50% of the neurofilament (NF)-positive fibers, took the pillar side course and contacted all IHC sides. NF-positive and calretinin-poor fibers took the modiolar side pathway and contacted the modiolar side of IHCs. Both fiber categories juxtaposed the C-terminal binding protein 2 (CtBP2) puncta and were contacted by synaptophysin puncta. These results indicated that the calretinin-poor fibers, like the calretinin-rich ones, were afferent fibers and probably formed functional efferent synapses. However, the other Ca²⁺-buffering proteins did not exhibit CAF subgroup specificity. Most CAFs near IHCs were parvalbumin-positive. Only the pillar-side half of parvalbumin-positive fibers coexpressed calretinin. Calbindin was not detected in any nerve fibers near IHCs. Taken together, of the Ca²⁺-buffering proteins examined, only calretinin exhibited spatial segregation at IHC-CAF synapses. The absence of calretinin in modiolar-side CAFs might be related to the noise vulnerability of the fibers.

Buffering action of acetate on hydrogen production by Ethanoligenens harbinense B49

The buffering effect of acetate on hydrogen production during glucose fermentation by Ethanoligenens harbinense B49 was investigated compared to phosphate, a widely used fermentative hydrogen production buffer. Specific concentrations of sodium acetate or phosphate were added to batch cultures, and the effects on hydrogen production were comparatively analyzed using a modified Gompertz model. Adding 50 mM acetate or phosphate suppressed the hydrogen production peak and slightly extended the lag phase. However, the overall hydrogen yields were 113.5 and 108.5 mmol/L, respectively, and the final pH was effectively controlled. Acetate buffered against hydrogen production more effectively than did phosphate, promoting cell growth and preventing decreased pH. At buffer concentrations 100-250 mM, the maximum hydrogen production was barely suppressed, and the lag phase extended past 7 h. Therefore, although acetate inhibits hydrogen production, using acetate as a buffer (like phosphate) effectively prevented pH drops and increased substrate consumption, enhancing hydrogen production.

Evaluación de sobredentaduras mandibulares implanto-retenidas confeccionadas con técnica Rehabilitación Oral M/Prótesis, Facultad Odontología, Universidad de Concepción, en pacientes del Servicio Salud Bío-Bío / Evaluation of mandibular overdenture implant retained made with Oral Rehabilitation Prosthetic mention Technique from Faculty of Dentistry, University of Concepción, in patients Health Service Bío Bío

Los servicios asistenciales revelan interés por establecer protocolos de rehabilitación con sobredentaduras mandibulares retenidas a implantes, pero necesitan respaldo científico evaluado con instrumentos confiables. Objetivo: El objetivo de este estudio fue evaluar un modelo-protocolo de rehabilitación con sobredentaduras implanto retenidas para servicios públicos, por medio de test de rendimiento masticatorio, valores de retención y valoración de la satisfacción terapéutica obtenidos con las prótesis mandibulares implanto-retenidas. Materiales y métodos: Este trabajo fue realizado entre la Facultad de Odontología Universidad de Concepción (FAO-UDEC) y el Servicio de Salud Bío Bío (SS-BÍO-BÍO). Catorce pacientes fueron seleccionados, usuarios del SS-BÍO-BÍO, y recibieron sobredentaduras implanto-retenidas confeccionadas con protocolo del programa Rehabilitación Oral mención Prótesis (ROMPE. FAO-UDEC). Dos Implantes Neodent (3,75 × 11 y 13 mm) por paciente fueron instalados y conectados con carga temprana. Antes y después de instalar y conectar los implantes se evaluó: la satisfacción terapéutica con encuesta Programa ROMPE.FAO-UDEC, la retención con dinamómetro Force Gauge y el rendimiento masticatorio con test tamizado de maní. Los datos fueron procesados con programa SPSS 16.0 con test Kolmogorov-Smirnov, t-test para muestras relacionadas. Significación estadística p < 0,05. Resultados: La eficiencia masticatoria aumenta de forma significativa después de la conexión de los implantes. La satisfacción terapéutica con las prótesis y la resistencia a la tracción son altamente significativas posterior a la conexión de ellas. Conclusiones: Estos resultados son coincidentes con la gran mayoría de estudios publicados, y permiten sostener científicamente que el protocolo de confección de sobredentaduras ROMPE FAO-UDEC y SS-BÍO-BÍO es una alternativa confiable.

Health care services show interest in establishing rehabilitation protocols with mandibular overdentures retained on two implants, but they require scientific evidence evaluated with reliable instruments. Objective: To evaluate masticatory performance, retention and therapeutic satisfaction of patientswith a model rehabilitation protocol for implant-retained overdentures. Materials and methods: This study was conducted between the Faculty of Dentistry, University of Concepción (FAO UDEC) and Bío Bío Health Service(SS-Bío Bio). Fourteen patients, selected users of Bío Bío Health Service, Los Angeles, received implant-overdentures using a protocol of the Oral Rehabilitation Prosthesis Program (ROMPE FAO UDEC). Two Neodent™ implants (3.75 × 11 and 13 mm) were installed in each patient and connected with early loading. Before and after installing and connecting the implants, (0, 30 and 60 days), therapeutic satisfaction was assessed using the ROMPE FAO UDEC graduate program questionnaire. Retention was measured with a Force Gauge Dynamometer, and masticatory performance was quantified with a peanut screening test. Data were processed with SPSS 16.0 program and Kolmogorov-Smirnov test and t- test were used. Significance was set at P < .05. Results: Masticatory efficiency significantly increases after connectingthe implants. Therapeutic satisfaction with the prosthesis and the tensile strength are highly significant. Conclusions: These results coincide with the vast majority of published studies. It can be scientifically argued that the ROMPE FAO UDEC, SS Bío Bío overdenture protocol is a reliable alternative.

Capacidad buffer de la saliva en presencia de bebidas energéticas comercializadas en Chile, estudio in vitro / In vitro study of the buffering capacity of saliva in the presence of energy drinks sold in Chile

OBJETIVO Determinar la capacidad buffer de la saliva al ser añadida a distintas bebidas energéticas comercializadas en Chile, mediante mediciones de pH in vitro. MÉTODOS Fue requerida la participación de 3 pacientes jóvenes sistémicamente sanos, sin enfermedad de las glándulas salivales. Las muestras de saliva estimulada fueron obtenidas de cada paciente, las cuales fueron mezcladas y almacenadas en una sola muestra. Se seleccionaron 13 bebidas energéticas comercializadas a nivel nacional. Un total de 5 mL de cada bebida energética se distribuyó en 4 tubos Falcon. Se midió el pH de cada una de las bebidas energéticas, de la saliva y del agua potable. Se añadió 1 mL de agua potable al tubo Falcon número 1 y 1 mL de saliva a los 3 tubos restantes, cada 3 min hasta completar 13 mL de solución en cada uno (38% vol./vol.). Las mediciones de pH fueron realizadas en cada 1 mL añadido (saliva/agua), para permitir al ph-metro registrar de manera correcta. RESULTADOS Los rangos de pH para las bebidas energéticas van desde pH 2,42 ± 0,008 (Battery Gingered®), hasta pH 3,44 ± 0,005 (Battery Sugar Free®). La saliva en promedio tuvo un valor de pH 7,99 y el agua potable de 7,05. La bebida que más logró aumentar el pH, luego de agregar la saliva, fue la bebida Speed® que llegó a un valor de pH 4,38, mientras la que logró menos fue la bebida Quick Energy®, con un valor de pH 3,37. CONCLUSIÓN La capacidad buffer de la saliva logró aumentar entre 17 y 54% el pH de las bebidas energéticas analizadas en este estudio. Sin embargo, no pudo neutralizar los bajos niveles de pH de estas bebidas más allá de un pH final de 4,38, que es crítico para la estructura dentaria.

OBJECTIVE To determine, using in vitro pH measurements, the buffering capacity of saliva when added to different energy drinks sold in Chile. METHOD The participation of 3 young and systemically healthy patients, with no diseases of the saliva glands, was obtained. Samples of stimulated saliva where obtained from each patient and then mixed and stored as one sample. The study used 13 energy drinks sold nationwide, with 5 mL of each one being distributed into 4 Falcon tubes. The pH of each of the energy drinks, the saliva sample, and drinking water was measured. 1 mL of drinking water was added into Falcon tube number 1, and 1 mL of saliva into the 3 remaining every 3 min until completing 13 mL of solution in each one (38% vol./vol.). The pH measurements where performed upon adding each 1 mL (saliva/water) to allow the pH meter to correctly register the data. RESULTS The pH levels for energy drinks range between pH 2.42 ± 0.008 (Battery Gingered®), to pH 3.44 ± 0.005 (Battery Sugar Free®). The saliva had a mean pH value of 7.99, and 7.05 for drinkable water. The energy drink that achieved a higher increase in pH level was Speed®, reaching a value of pH 4.38, while the energy drink that increased the pH level the least was Quick Energy®, only reaching a pH of 3.37. CONCLUSION The buffering capacity of saliva managed to increase the pH level of energy drinks analyzed in this study between 17 and 54%. However, saliva was unable to neutralize further than 4.38 the low levels of pH in these drinks, thus being critical to dental structure.

Sodium bicarbonate as prevention of metabolic acidosis in sheep submitted to experimental ruminal acidosis / Bicarbonato de sódio como preventivo da acidose metabólica em ovinos submetidos à acidose ruminal experimental

The aim of this study was to evaluate the preventive effect of sodium bicarbonate on systemic acidosis due to ruminal acidosis, which was induced by ingestion of concentrate after prolonged fasting. Fourteen sheep were divided into three experimental groups: control group (Cg), with four sheep, submitted to fasting without development of ruminal acidosis; no-treated group (NTg), with five sheep with rumen acidosis without preventive treatment; and treated group (Tg), with five sheep with rumen acidosis and preventively treated with sodium bicarbonate. Assessments of ruminal pH and arterial hemogasometry were performed for 48 hours after ingestion of the concentrate. There was a reduction in the ruminal pH in all groups, whereas the Cg showed a reduction only after 24 hours. A reduction in the arterial pH, bicarbonate and base excess in all groups was also noted, indicating systemic metabolic acidosis, but the NTg presented the greatest alteration. It is concluded that sodium bicarbonate prevents systemic metabolic acidosis, reducing its severity in sheep subjected to ruminal acidosis.(AU)

O objetivo deste estudo foi avaliar o efeito preventivo do bicarbonato de sódio sobre a acidose sistêmica em decorrência da acidose ruminal, a qual foi induzida pelo fornecimento de concentrado após jejum prolongado. Foram utilizados 14 ovinos, divididos em três grupos experimentais: grupo controle (Cg), contendo quatro ovinos, submetidos a jejum sem desenvolvimento de acidose ruminal; grupo não tratado (NTg), contendo cinco ovinos submetidos a acidose ruminal sem tratamento preventivo; e grupo tratado (Tg), contendo cinco ovinos, submetidos a acidose ruminal e tratados preventivamente com bicarbonato de sódio. Foram realizadas avaliações do pH ruminal e hemogasometria arterial, durante 48 horas após o fornecimento do concentrado. Houve redução do pH ruminal em todos os grupos, sendo que o Cg apresentou a redução apenas às 24 horas. Notou-se redução do pH arterial, bicarbonato e excesso de base em todos os grupos, indicando acidose metabólica sistêmica; no entanto, o NTg apresentou o quadro mais grave. Conclui-se que o bicarbonato de sódio possui efeito preventivo da acidose metabólica sistêmica, reduzindo a sua gravidade em ovinos submetidos à acidose ruminal.(AU)

Lactato: de causa da fadiga a suplemento ergogênico? / Lactate: from cause of fatigue to ergogenic supplement?

Durante anos, pesquisadores inseridos na área de fisiologia do exercício apontaram para o lactato como o principal causador da fadiga durante exercícios de alta intensidade. Hoje, por outro lado, já existem diversos estudos demonstrando que o lactato per se não possui qualquer efeito sobre a fadiga neste tipo de exercício, mas que a acidose muscular, ocasionada pelo acúmulo de íons hidrogênio no interior da célula muscular, seria o fator limitante para o desempenho físico durante exercícios físicos de alta intensidade. Assim, estratégias com o objetivo de atenuar a queda do pH intramuscular, como a suplementação de beta-alanina e bicarbonato de sódio, têm se destacado no cenário esportivo. Embora anteriormente destacado como vilão durante esforços intensos, a suplementação de lactato vem recebendo especial atenção em anos recentes. A suplementação com este composto teoricamente pode aumentar os níveis sanguíneos de pH e bicarbonato, aumentando a capacidade de tamponamento extracelular, e por consequência, o desempenho físico. A suplementação com lactato também pode aumentar os níveis sanguíneos deste composto, aumentando sua disponibilidade como substrato para a gliconeogênese. Assim, estudos tem surgido com o intuito de avaliar a eficácia do lactato como tamponante e como substrato energético. Os poucos estudos até agora conduzidos, entretanto, não nos permitem atestar a eficácia ergogênica desta estratégia nutricional. A falta de estudos dose-resposta sobre as variáveis sanguíneas que caracterizam o mecanismo de ação do lactato, bem como de aplicação de testes físicos com baixo coeficiente de variação e boa validade externa exemplificam a necessidade de mais estudos investigando a eficácia ergogênica desta estratégia nutricional.

For years, researchers from the exercise physiology field pointed to lactate as the main cause of fatigue during high-intensity exercises. Today, however, there are several studies demonstrating that lactate per se does not have any effect on fatigue during this type of exercise, but muscle acidosis occasioned by hydrogen ions accumulation inside the muscle cell would be the limiting factor for performance during high-intensity exercises. Therefore strategies aiming to attenuate the decrease of intramuscular pH levels, like beta-alanine and sodium bicarbonate supplementation, have been prominent in the sports scenario. Although previously highlighted as a villain during high-intensity exercises, lactate supplementation has received special attention in recent years. Supplementation with this compound can theoretically increase blood pH and bicarbonate levels, increasing the extracellular buffering capacity, and hence, performance. Lactate supplementation can also increase lactate blood levels, increasing its availability as a substrate for gluconeogenesis. Thus, studies have arisen aiming to assess the effectiveness of lactate as a buffering agent and as an energy substrate. The few studies so far conducted, however, do not allow us to attest the ergogenic effectiveness of this nutritional strategy. The lack of dose-response studies on blood variables that characterize lactate mechanism of action, as well as the application of physical tests with a low coefficient of variation and good external validity exemplifies the need for further studies investigating the ergogenic effectiveness of this nutritional strategy.

Capacidad amortiguadora y ph salival en mujeres en etapa reproductiva y menopáusica por efecto de la terapia hormonal: prueba piloto / Buffer capacity and salivary ph in menopausal and reproductive age women by hormonal therapy effect: pilot study

El propósito de este estudio fue evaluar la capacidad amortiguadora y pH salival de mujeres en etapa reproductiva sin terapia hormonal, con [anticonceptivos] (AC) y en etapa menopáusica. Se recolectaron muestras de saliva estimulada (SE) y no estimulada (SNE) en 9 mujeres de entre 33 y 56 años de edad, las cuales se dividieron en tres grupos; el grupo 1, constituido por mujeres en etapa reproductiva sin terapia hormonal (grupo control), el grupo 2, constituido por mujeres en etapa reproductiva con terapia hormonal [anticonceptivos] AC y el grupo 3, constituido por mujeres en etapa menopáusica. La capacidad amortiguadora salival se determinó por titulación ácido-base utilizando el método descrito por Singer y col. (1983). El pH se midió en un potenciómetro marca Orion, modelo 710A y un electrodo para pH Accumet Fisher Scientific. La capacidad amortiguadora en SNE fue de (7,8±2,0) en el grupo control; (38,1±22,4) en las mujeres con terapia hormonal (AC) y (12,6±2,4) en el grupo de mujeres menopáusicas. Cuando se evaluaron las muestras de SE, el comportamiento fue similar y los resultados observados fueron (37,56±20,84) en el grupo 2 respecto al control (13,8±3,2). No se observaron cambios en el pH tanto de la SE como SNE en los grupos evaluados a excepción del grupo 2 donde el pH fue significativamente menor (p<0,05). Los resultados parecieran indicar que el uso de terapia hormonal con anticonceptivos (estrógenos) produce una modificación tanto en el pH como en la capacidad amortiguadora de la saliva...

The purpose of this study was to evaluate the salivary pH and buffering capacity of reproductive age women, without hormonal therapy, with [contraceptive] (CC) and menopausal. Samples of stimulated (SS) and unstimulated (USS) saliva were collected in 9 women between 33 and 56 years old, which were divided into three groups; Group 1, consisting of women of reproductive age without hormonal therapy (control group), group 2, consisting of women of reproductive age with hormone therapy [contraceptive] (CC) and group 3, consisting of menopausal women. Salivary buffering capacity was determined by acid-base titration using the method described by Singer et al. (1983). The pH was measured with an Orion potentiometer, model 710A and a Fisher Scientific Accumet electrode. The buffering capacity in SNE, was (7.8±2.0) in the control group, (38.1±22.4) in women with AC and (12.6±2.4) in the group of menopausal women. When samples were evaluated SE, the behavior was similar and the observed results were (37.56±3.2) in group 2 over control group (13,8±3,2). No changes in the pH of both the SE as SNE evaluated in groups 2 , group except where the pH was significantly lower (p<0.05). The results seem to indicate that use of hormonal contraceptive therapy (estrogens) causes a change in both the pH and buffering capacity of saliva...

Role of amylase, mucin, IgA and albumin on salivary protein buffering capacity: A pilot study.

It has been suggested that proteins serve as major salivary buffers below pH5. It remains unclear, however, which salivary proteins are responsible for these buffering properties. The aim of this pilot study was to evaluate the correlation between salivary concentration of total protein, amylase, mucin, immunoglobulin A (IgA), albumin and total salivary protein buffering capacity at a pH range of 4–5. In addition, the buffering capacity and the number of carboxylic acid moieties of single proteins were assessed. Stimulated saliva samples were collected at 9:00, 13:00 and 17:00 from 4 healthy volunteers on 3 successive days. The buffering capacities were measured for total salivary protein or for specific proteins. Also, the concentration of total protein, amylase, mucin, IgA and albumin were analysed. Within the limits of the current study, it was found that salivary protein buffering capacity was highly positively correlated with total protein, amylase and IgA concentrations. A weak correlation was observed for both albumin and mucin individually. Furthermore, the results suggest that amylase contributed to 35% of the salivary protein buffering capacity in the pH range of 4–5.

Effect of commercial alcoholic drinks on sound enamel surface of bovine teeth / 대한구강보건학회지

OBJECTIVES: The purpose of this study was to evaluate the change in surface microhardness of sound enamel of bovine teeth due to commercial alcoholic drinks. METHODS: The experiment group comprised of wines, makgeollis, and beers with low pH, while distilled water was used as the control. The two experiment groups were administered soju having the highest (SojuH) and lowest (SojuL) pH. Drinking wines were classified into 2 groups: agitated (wine A) and non-agitated (wine NA) wines. The pH values, buffering capacity, and concentrations of fluorine, calcium, and phosphorus of both the wine groups were measured. Eighty-four bovine specimens were divided into seven groups (N=12) and were immersed for 1, 3, 5, 10, 30, 60, and 120 min, respectively. The surface microhardness was measured using a microhardness tester before and after treatment with each alcoholic drink. After 120 min, the enamel surface was examined using a scanning electron microscope (SEM). The statistical methods used in this study were one-way analysis of variance (ANOVA) and repeated-measure ANOVA. RESULTS: The differences in the surface microhardness (DeltaVHN) values obtained before and after treatment for 120 min were statistically significant among groups. Makgeolli, wine A, and wine NA significantly eroded the enamel after 120 min. However, sojuH and sojuL had an effect similar to that of distilled water, which was used in the control group. Beer caused slight enamel erosion. SEM images revealed that makgeolli, wine A, and wine NA caused significant erosion of the enamel surface, while beer caused slight erosion. SEM observation results were similar to those obtained after surface microhardness evaluation. CONCLUSIONS: The study findings suggest that alcoholic drinks, such as makgeolli and wine, with organic acids and a pH value less than 4.0 can cause tooth enamel erosion. Therefore, alcoholic drinks with low pH values and organic acid composition should not be retained for long periods in the mouth.

The Moderating Effects of Social Problem-Solving in the Relationship between Risk Factors and Peer Victimization in Colombian Early Adolescents / Efectos Moderadores de la Habilidad de Solución de Problemas Sociales en la Relación entre Factores de Riesgo y Victimización en Adolescentes Colombianos / Efeitos Moderadores da Habilidade de Solução de Problemas Sociais na Relação entre Fatores de Risco e Vitimização em Adolescentes Colombianos

This study assessed the moderating effect of social problem-solving (SPS) in the association between risk factors and peer victimization in a sample of Colombian adolescents. Using structural equation modeling techniques, this study assessed the extent to which changes in victimization varied as a function of the interaction between risk factors and social problem-solving. Results showed that both aggression and avoidance were predictive of initial scores on victimization, but only avoidance was found to predict its change over time. Only a main effect of SPS was found at the beginning of the year; no moderating effects were found. Results are consistent with previous findings by confirming that avoidance and aggression are risk factors for peer victimization.

Este estudio examinó el rol moderador de la habilidad para resolver problemas sociales (SPS) en la asociación entre factores de riesgo y la victimización, en una muestra de adolescentes colombianos. Mediante el uso de técnicas de ecuaciones estructurales se evaluó qué tanto cambió la victimización a lo largo del tiempo, en función de la interacción entre factores de riesgo y la SPS. Los resultados mostraron que la agresión y la evitación son factores de riesgo y predicen puntajes iniciales en la victimización. Sin embargo, únicamente la evitación predijo los cambios de dicha variable en el tiempo. Adicionalmente, se encontró un efecto de la SPS en la victimización al inicio del año escolar, pero no se encontraron efectos moderadores. Los resultados son consistentes con estudios previos en los que se observa que la evitación y la agresión son factores de riesgo en la victimización.

Este estudo examinou o papel moderador da habilidade para resolver problemas sociais (SPS) na associação entre fatores de risco e a vitimização, em uma amostra de adolescentes colombianos. Mediante o uso de técnicas de equações estruturais, avaliou-se quanto a vitimização ao longo do tempo mudou, em função da interação entre fatores de risco e a SPS. Os resultados mostraram que a agressão e a evitação são fatores de risco e predizem pontuações iniciais na vitimização. Contudo, unicamente a evitação prediz as mudanças de dita variável no tempo. Adicionalmente, constatou-se um efeito da SPS na vitimização ao início do ano escolar, mas não se encontraram efeitos moderadores. Os resultados são consistentes com estudos prévios nos quais se observa que a evitação e a agressão são fatores de risco na vitimização.

Flujo y capacidad amortiguadora salival en dos grupos de sujetos de 6 a 11 años de edad con bajo y alto índice de dientes cariados, perdidos y obturados / Salivary flow and buffer capacity in two 6-to-11-year-old groups of subjects with low and high decayed, missing and filled teeth index

Objetivo: comprobar la relación entre el flujo y la capacidad amortiguadora salival con la experiencia de caries, en niños con bajo y alto índice de dientes cariados, perdidos y obturados (CPOD). Método: Se realizó un estudio descriptivo transversal a un grupo de 60 niños de 6 a 11 años de edad, de ambos sexos, admitidos para consulta en la Clínica de Admisión de la Facultad de Odontología de la Universidad Autónoma de Baja California, sede Mexicali. Se establecieron dos grupos en función del CPOD: grupo 1 (puntuación 0-3) y grupo 2 (4 o más). Se elaboró una historia clínica que incluyó tanto los datos generales del niño como el registro de la experiencia de caries bajo los criterios de la Organización Mundial de la Salud. Asimismo, se midieron y registraron el volumen de saliva estimulada y la capacidad amortiguadorapara cada sujeto. Resultados: se observó una correlación negativa (r=–0,221) entre el flujo salival y el CPOD; sin embargo, esta tendencia no fue estadísticamente significativa (p>0,05). En cuanto a la capacidad amortiguadora, se hallaron diferencias estadísticamente significativas al relacionar una mayor capacidad amortiguadora y un CPOD bajo (p<0,05). Conclusión: la mayor capacidad amortiguadora de la saliva se relacionó con la menor experiencia de caries. Por su parte, el flujo salival estimulado mostró alguna asociación descriptivamente con el CPOD, pero dicha asociación no fue estadísticamente significativa.

Objective: Demonstrate the association between salivary flow and buffer capacity with caries experience in children with low and high Decayed, Missing and Filled Teeth Index (DMFT). Methods: A cross-sectional study was conducted with 60 6-to-11-year-old children of both sexes, who attended the Dental School of Universidad Autónoma de Baja California, Mexicali campus. The patients were assigned to two groups according to the DMFT score, group 1 (score 0-3) and group 2 (score 4 or more). A clinical record including patient’s general information and dental evaluation was filled out. Cavity experience evaluation was carried out following WHO parameters. Also, salivary flow and buffer capacity were measured in each individual. Results: A weak negative correlation between salivary flow and DMFT score was observed (r=–0.221); however, this trend was not statistically significant (p>0.05). Regarding the buffer capacity, statistically significant differences between this salivary property and DMFT were found (p<0.05). Conclusion: The buffer capacity of saliva was associated with lower caries experience. On the other side, stimulated salivary flow show was not found to be related with the DMFT score.

Buffering capacity and membrane H+ conductance of protease producing facultative alkaliphilic bacterium Bacillus flexus from mangrove soil. Indian Journal of Biochemistry & Biophysics. 2009 June; 46(3): 261-265.

A facultative alkaliphilic protease-producing gram-positive rod-shaped bacteria (EMGA 5) was isolated from mangrove soil and confirmed as Bacillus flexus by the 16S rDNA sequence. Buffering capacity and membrane H+ conductance of this alkaliphilic isolate were investigated for the cells grown at pH 7.2 and 10.5 using acid pulse technique. Suspensions of B. flexus cells grown in poly peptone yeast glucose medium at pH 10.5 exhibited higher cytoplasmic membrane buffering capacity values (70 µmol H+/pH unit/mg protein at pH 9.9) than the cells grown at pH 7.2 (41 µmol H+/pH unit/mg protein at pH 9.9). B. flexus grown aerobically at pH 7.2 showed higher H+ conductance values than the cells grown at pH 10.5 (0.032 µmol H+/s/pH unit/mg protein at pH 9.9 and 0.028 µmol H+/s/pH unit/mg protein at pH 9.8, respectively). The present study revealed that the buffering capacity and membrane H+ conductance of the B. flexus isolates were influenced by pH of the medium.

Heterogeneity of the SR-dependent Inward Na+-Ca2+ Exchange Current in the Heavily Ca2+-buffered Rat Ventricular Myocytes

Voltage-sensitive release mechanism was pharmacologically dissected from the Ca2+-induced Ca2+ release in the SR Ca2+ release in the rat ventricular myocytes patch-clamped in a whole-cell mode. SR Ca2+ release process was monitored by using forward-mode Na+-Ca2+ exchange after restriction of the interactions between Ca2+ from SR and Na+-Ca2+ exchange within micro-domains with heavy cytosolic Ca2+ buffering with 10 mM BAPTA. During stimulation every 10 s with a pulse roughly mimicking action potential, the initial outward current gradually turned into a huge inward current of -12.9+/-0.5 pA/pF. From the inward current, two different inward INCXs were identified. One was 10 muM ryanodine-sensitive, constituting 14.2+/-2.3%. It was completely blocked by CdCl2 (0.1 mM and 0.5 mM) and by Na+-depletion. The other was identified by 5 mM NiCl2 after suppression of ICaL and ryanodine receptor, constituting 14.8+/-1.6%. This latter was blocked by either 10 mM caffeine-induced SR Ca2+-depletion or 1 mM tetracaine. IV-relationships illustrated that the latter was activated until the peak in 30~35 mV lower voltages than the former. Overall, it was concluded that the SR Ca2+ release process in the rat ventricular myocytes is mediated by the voltage-sensitive release mechanism in addition to the Ca2+-induced-Ca2+ release.

A further note on the sampling device for the anti-mutagenicity of saliva

<p><b>OBJECTIVES</b>The purpose of this study was to compare the anti-mutagenicity of Salivette and test-tube sampling saliva. In addition, the relation between the inhibiting and pH-buffering capacities of saliva was investigated.</p><p><b>METHODS</b>Subjects were 52 healthy female university students. The collection of saliva samples was carried out using 2 sampling devices; test-tube and Salivette. The anti-mutegenicity of the saliva was measured using the umu test.</p><p><b>RESULTS</b>The inhibiting capacity of Salivette-saliva was significantly lower compared with that of testube-saliva (p<0.01,t test). However, there was a significant correlation between them (r=0.35; p<0.05). In addition, there was a significant correlation between the inhibiting and pH-buffering capacities of saliva (r=-0.36; p<0.05).</p><p><b>CONCLUSIONS</b>These findings suggest that both the Salivette and the test-tube may be appropriate as saliva-sampling devices. In addition, they suggest that the bicarbonates might inhibit the anti-mutagenicity of saliva, or that the activity of substances related to the anti-mutagenicity of saliva might be dependent on pH.</p>

A Further Note on the Sampling Device for the Anti-Mutagenicity of Saliva

Objectives: The purpose of this study was to compare the anti-mutagenicity of Salivette and test-tube sampling saliva. In addition, the relation between the inhibiting and pH-buffering capacities of saliva was investigated. Methods: Subjects were 52 healthy female university students. The collection of saliva samples was carried out using 2 sampling devices; test-tube and Salivette. The anti-mutagenicity of the saliva was measured using the umu test. Results: The inhibiting capacity of Salivette-saliva was significantly lower compared with that of test-tube-saliva (p<0.01, t test). However, there was a significant correlation between them (r=0.35; p<0.05). In addition, there was a significant correlation between the inhibiting and pH-buffering capacities of saliva (r=−0.36; p<0.05). Conclusions: These findings suggest that both the Salivette and the test-tube may be appropriate as saliva-sampling devices. In addition, they suggest that the bicarbonates might inhibit the anti-mutagenicity of saliva, or that the activity of substances related to the anti-mutagenicity of saliva might be dependent on pH.