Efeito de dentifrícios com reduzida concentração de fluoreto contendo trimetafosfato de sódio e polióis na erosão inicial do esmalte / Effect of low-fluoride toothpaste containing sodium trimetaphosphate and polyols on initial enamel erosion

Este estudo in vitro avaliou o efeito de dentifrícios contendo fluoreto (F), trimetafosfato de sódio (TMP) e/ou xilitol e eritritol (XE) em inibir ou reparar lesão erosiva inicial do esmalte. Blocos de esmalte bovino (n=120) foram selecionados por dureza de superfície (SH) inicial e divididos em 5 grupos compostos por dentifrícios (24 blocos/grupo): Placebo (sem F, TMP e XE); 1100 ppm F; 16% xilitol + 4% eritritol (XE); 200 ppm F + 0,2% TMP (200 ppm F/TMP); e 200 ppm F + 0,2% TMP + 16% xilitol + 4% eritritol (200 ppm F/TMP/XE). Para a análise do efeito protetor, blocos hígidos (n=60) foram imersos 1x/2 minutos em suspensão de dentifrícios/saliva humana. Em seguida, os blocos foram submetidos a 4 desafios erosivos com ácido cítrico (0,75%, pH 3,5) de 1 minuto cada, sob agitação. A seguir, a SH foi determinada pós-tratamento (t) e após o 1º, 2º, 3º e 4º desafios ácidos erosivos (d) para o cálculo da porcentagem de variação da SH (%SH). Para a análise do efeito reparador, esmalte previamente erodido (n=60) foi tratado e submetido aos mesmos desafios erosivos descritos anteriormente. A %SH de recuperação (R) e %SHt foram calculadas, bem como, a diferença entre a %SHR e %SHd obtendo-se o Δ%SH para cada desafio. Experimento adicional foi realizado para análise da deposição de precipitados por Microscopia Eletrônica de Varredura (MEV) em esmalte hígido e erodido. Os dados foram submetidos à análise de variância de medidas repetidas a dois critérios, seguida pelo teste de Student-Newman-Keuls (p<0,05). Os resultados mostraram que o maior efeito protetor e reparador foi produzido pelo dentifrício 200 ppm F/TMP/XE quando comparado aos demais grupos (p<0,001). Os grupos 1100 ppm F e 200 ppm F/TMP apresentaram similar efeito protetor para o 1º, 2º e 3º desafios (p>0,05), e menor quando comparados ao XE (p<0,001). O efeito protetor e reparador foi: XE>200 ppm F/TMP>1100 ppm F>Placebo (p<0,001). Na MEV observou-se deposição de precipitado no esmalte para todos os grupos, formando uma camada mais espessa e homogênea nos grupos contendo XE e/ou TMP. Concluiu-se que dentifrício contendo 200 ppm F, TMP e polióis apresenta efeito protetor e reparador superior quando comparado a um dentifrício 1100 ppm F em lesões erosivas iniciais no esmalte(AU)

This in vitro study evaluated the effect of toothpaste containing fluoride (F), sodium trimetaphosphate (TMP) and/or xylitol and erythritol (XE) in inhibit or repair initial enamel erosion lesions. Bovine enamel blocks (n=120) were selected by initial surface hardness (SH) and divided into 5 groups of toothpastes (n=24 blocks/group): Placebo (no F, TMP or XE); 1100 ppm F; 16% xylitol + 4% erythritol (XE); 200 ppm F + 0.2% TMP (200 ppm F/TMP); and 200 ppm F + 0.2% TMP + 16% xylitol + 4% erythritol (200 ppm F/TMP/XE). For the analysis of the protective effect, sound blocks (n=60) were immersed in toothpaste slurry in human saliva once for 2 minutes. Hereafter, the blocks were submitted to 4 erosive challenges in citric acid (0.75%, pH 3.5) by 1 minute, under stirring. Then, the SH was determined after treatment (t) and after the 1st, 2nd, 3rd and 4th erosive acid challenges (d) to calculate the percentage of change of the SH (%SH). For the analysis of the repair effect, eroded enamel (n=60) were treated and submitted to erosive challenges as describe previously. The recovery (R) of %SH and %SHt were calculated, as well as the difference between the %SHR and %SHd obtaining the Δ%SH for each challenge. Additional experimental was performed to analysis the deposition of precipitates by Scanning Electronic Microscopy (SEM) on sound and eroded enamel. Variables were submitted to two-way repeated measures analysis of variance followed by StudentNewman-Keuls test (p<0.05). The results showed that the highest protective and repair effect was produced by the 200 ppm F/TMP/XE toothpaste when compared to the other groups (p<0.001). The 1100 ppm F and 200 ppm F/TMP groups had similar protective effect for the 1st, 2nd and 3rd challenges (p>0.05), and lower when compared to XE (p<0.001). The protective and repair effect was: XE>200 ppm F/TMP>1100 ppm F>Placebo (p<0.001). There were deposition of precipitates on enamel for all groups, with a thicker layer and homogeneous for XE and/or TMP groups. It was concluded that toothpaste containing 200 ppm F, TMP and polyols has superior protective and repair effect when compared to 1100 ppm F toothpaste in initial enamel erosive lesions(AU)

Atividade antimicrobiana de Stevia rebaudiana Bertoni e de adoçantes não calóricos sobre bactérias cariogênicas: estudo in vitro / Antimicrobial activity of Stevia rebaudiana Bertoni and non-caloric sweeteners on cariogenic bacteria: in vitro study

Objetivo: avaliar a atividade antimicrobiana in vitro da planta Stevia rebaudiana Bertoni e de adoçantes não calóricos sobre o crescimento de Streptococcus mutanse Lactobacillus casei, micro-organismos cariogênicos presentes na cavidade bucal. Materiais e método: o estudo foi realizado utilizando as cepas padrões de S.mutans (UA159) e L. casei (ATCC7469). Foram avaliados diferentes compostos não calóricos substitutos dasacarose nas concentrações de 1%, 5% e 10%: eritritol(ER), Fit Sucralose® (SU), Stevita® (ST), solução de Steviarebaudiana Bertoni (SSr) e, como controle positivo,digluconato de clorexidina (DC). A análise do efeito inibitório desses compostos no crescimento das bactériasfoi feita por meio da técnica de difusão em ágar. Resultado:observou-se que existe um efeito inibitório decrescimento de ambos os micro-organismos por parte da SSr e do ER, enquanto os demais adoçantes testa dosnão tiveram efeito inibitório sobre esses micro-organismos.Conclusão: os resultados demonstram que SSR eER apresentam efeito inibidor no crescimento das cepastestadas de S. mutans e L. casei. (AU)

Objective: The study evaluated the in vitro antimicrobial activity of the Stevia rebaudiana Bertoni plant and non-caloric sweeteners on the growth of Streptococcus mutans and Lactobacillus casei, which are cariogenic microorganisms present in the oral cavity. Materials and method: The study was conducted using the standard strains of S. mutans (UA159) and L. casei (ATCC7469). Different non-caloric compounds were evaluated at concentrations of 1%, 5%, and 10%: erythritol (ER), Fit Sucralose™ (SU), Stevita™ (ST), Stevia rebaudiana Bertoni solution (SSr), and chlorhexidine digluconate (CD) as positive control. The inhibitory effect of these compounds on the growth of bacteria were analyzed by the agar diffusion technique. Result: There was a growth inhibition effect for both microorganisms by SSr and ER, whereas the other sweeteners tested had no inhibitory effect on the microorganisms. Conclusion: The results showed that SSr and ER present an inhibitory effect on the growth the strains tested of S. mutans and L. casei. (AU)

Strategy of oxygen transfer coefficient control on the L-erythrulose fermentation by newly isolated Gluconobacter kondonii

Background: The effect of diverse oxygen transfer coefficient on the L-erythrulose production from meso-erythritol by a newly isolated strain, Gluconobacter kondonii CGMCC8391 was investigated. In order to elucidate the effects of volumetric mass transfer coefficient (K La) on the fermentations, baffled and unbaffled flask cultures, and fed-batch cultures were developed in present work. Results: With the increase of the K La value in the fed-batch culture, L-erythrulose concentration, productivity and yield were significantly improved, while cell growth was not the best in the high K La. Thus, a two-stage oxygen supply control strategy was proposed, aimed at achieving high concentration and high productivity of L-erythrulose. During the first 12 h, Klawas controlled at 40.28 h-1 to obtain high value for cell growth, subsequently K La was controlled at 86.31 h-1 to allow for high L-erythrulose accumulation. Conclusions: Under optimal conditions, the L-erythrulose concentration, productivity, yield and DCW reached 207.9 ± 7.78 g/L, 6.50 g/L/h, 0.94 g/g, 2.68 ± 0.17 g/L, respectively. At the end of fermentation, the L-erythrulose concentration and productivity were higher than those in the previous similar reports.

Enhanced production of erythritol and mannitol by Yarrowia lipolytica in media containing surfactants

Abstract Various chemical compounds, including surfactants, when introduced to culture media may increase the permeability of cellular membranes and thereby affect the quantity of metabolites excreted by cells. The aim of the present study was to evaluate the impact of detergents including Triton X-100, Span 20 and Tween 80 on erythritol production from glycerol by Yarrowia lipolytica Wratislavia K1 in a shake-flask experiment, batch and fed-batch cultures. When Span 20 was added to a fed-batch culture with glycerol as a carbon source (300 g L-1), erythritol production increased by 15% compared to the culture without the surfactant where it reached 142 g L-1 after 5 days, which corresponded to 0.47 g g-1 yield and productivity of 1.1 g L-1 h-1. Therefore, it was concluded that Span 20 considerably enhanced the production of this polyol from glycerol.

Effect of fosmidomycin on metabolic and transcript profiles of the methylerythritol phosphate pathway in Plasmodium falciparum

In Plasmodium falciparum, the formation of isopentenyl diphosphate and dimethylallyl diphosphate, central intermediates in the biosynthesis of isoprenoids, occurs via the methylerythritol phosphate (MEP) pathway. Fosmidomycin is a specific inhibitor of the second enzyme of the MEP pathway, 1-deoxy-D-xylulose-5-phosphate reductoisomerase. We analyzed the effect of fosmidomycin on the levels of each intermediate and its metabolic requirement for the isoprenoid biosynthesis, such as dolichols and ubiquinones, throughout the intraerythrocytic cycle of P. falciparum. The steady-state RNA levels of the MEP pathway-associated genes were quantified by real-time polymerase chain reaction and correlated with the related metabolite levels. Our results indicate that MEP pathway metabolite peak precede maximum transcript abundance during the intraerythrocytic cycle. Fosmidomycin-treatment resulted in a decrease of the intermediate levels in the MEP pathway as well as in ubiquinone and dolichol biosynthesis. The MEP pathway associated transcripts were modestly altered by the drug, indicating that the parasite is not strongly responsive at the transcriptional level. This is the first study that compares the effect of fosmidomycin on the metabolic and transcript profiles in P. falciparum, which has only the MEP pathway for isoprenoid biosynthesis.

Tipificación molecular de Brucella abortus cepa 19 y su aplicación al control de biológicos / Molecular characterization of Brucella abortus strain 19 and its application for controlling biologics

Brucella abortus es el agente etiológico de la brucelosis bovina. La cepa 19, utilizada en la elaboración de vacunas, puede ser identificada a través de una deleción en la región eri asociada con la sensibilidad al eritritol. Se optimizó un ensayo de PCR para caracterizar específicamente esta cepa. El método que describimos es un procedimiento rápido para identificar B. abortus y simultáneamente diferenciar la cepa 19 de otras cepas de B. abortus biovar 1. Hemos aplicado este ensayo para la detección de la cepa 19 en vacunas contra la brucelosis bovina elaboradas en Argentina. Los resultados indican que este método podría ser útil para el seguimiento de las cepas madres y semillas utilizadas en la producción industrial de esta vacuna. Esta metodología también contribuiría a la reducción del riesgo de la infección adquirida en el laboratorio y podría aplicarse como prueba de rutina para confirmar la presencia de B. abortus en vacunas no relacionadas.

Brucella abortus is the etiological agent of bovine brucellosis. The strain 19 used in vaccine elaboration can be identified through a deletion in the eri region associated with its susceptibility to erythritol. We optimized a PCR assay for specific characterization of this strain. The method described here is a rapid procedure that enables identification of B. abortus, and simultaneous differentiation of the strain 19 from other B. abortus biovar 1 strains. We applied the assay to detect the strain 19 in vaccines against B. abortus produced in Argentina. The results show this method could be used to follow vaccine seed cultures of this strain. The methodology could also contribute to reduce the risk of a laboratory-acquired infection and could be of great help as a routine test for confirmation of B. abortus in non related vaccines.