RESUMEN
Abstract Sucrose is the most cariogenic dietary carbohydrate and starch is considered non-cariogenic for enamel and moderately cariogenic for dentine. However, the cariogenicity of the combination of starch and sucrose remains unclear. The aim of this study was to evaluate the effect of this combination on Streptococcus mutans biofilm composition and enamel and dentine demineralization. Biofilms of S. mutans UA159 were grown on saliva-coated enamel and dentine slabs in culture medium containing 10% saliva. They were exposed (8 times/day) to one of the following treatments: 0.9% NaCl (negative control), 1% starch, 10% sucrose, or 1% starch and 10% sucrose (starch + sucrose). To simulate the effect of human salivary amylase on the starch metabolization, the biofilms were pretreated with saliva before each treatment and saliva was also added to the culture medium. Acidogenicity of the biofilm was estimated by evaluating (2 times/day) the culture medium pH. After 4 (dentine) or 5 (enamel) days of growth, biofilms (n = 9) were individually collected, and the biomass, viable microorganism count, and polysaccharide content were quantified. Dentine and enamel demineralization was assessed by determining the percentage of surface hardness loss. Biofilms exposed to starch + sucrose were more acidogenic and caused higher demineralization (p < 0.0001) on either enamel or dentine than those exposed to each carbohydrate alone. The findings suggest that starch increases the cariogenic potential of sucrose.
Asunto(s)
Humanos , Animales , Bovinos , Adulto Joven , Almidón/química , Cariogénicos/química , Desmineralización Dental/etiología , Sacarosa en la Dieta/química , Esmalte Dental/química , Dentina/química , Valores de Referencia , Saliva/microbiología , Saliva/química , Streptococcus mutans/crecimiento & desarrollo , Factores de Tiempo , Recuento de Colonia Microbiana , Desmineralización Dental/microbiología , Estadísticas no Paramétricas , Biopelículas/crecimiento & desarrollo , Esmalte Dental/microbiología , Dentina/microbiologíaRESUMEN
La fosforilación de la glucosa en los mamíferos, es catalizada por una familia de isoenzimas (hexoquinasas I-IV; HQ) de diferente Km para el azúcar. En los hepatocitos y células b-pancreáticas se encuentra la glucoquinasa (GQ; HQ IV) de Km elevado (12-20 mM). Hemos observado que GQ está presente en el intestino delgado y podría contribuir a la producción de lactato durante la absorción del azúcar. En este trabajo se determinó el efecto de la dieta (ratarina R; 60% de glucosa G; sacarosa S; almidón A; caseína C), suministrada ad libitum, sobre las actividades de HQ y GQ en homogenatos de hígado y mucosa intestinal de rata. El suministro de glucosa (5%) en el agua de beber (SG) también fue evaluado en las dietas con R y G. Las actividades de HQ (Glucosa 1 mM) y la capacidad fosforilativa total (CFT: Glucosa = 100 mM) se determinaron enzimáticamente. GQ se estimó por diferencia. En el grupo control (R) y en S, A y C, la GQ hepática fue un 85% de la CFT, mientras que en G, GSG y RSG un 66%. La HQ intestinal alcanzó en los grupos R, GSG, A y C un 87% y en RSG un 30% de la CFT. La GQ en G, S, aumentó, pero una menor magnitud. La presencia de GQ en el intestino delgado y su expresión diferencial de acuerdo a la dieta, abren la posibilidad de que dicho órgano contribuya al metabolismo inicial de la glucosa procedente de la dieta y provea al hígado de un precursor (lactato) muy eficaz para sus procesos anabólicos.
Glucose phosphorylation in mammals, is catalyzed by a family of isoenzymes (hexokinases I- IV; HQ) of different Km for the sugar. In hepatocytes and pancreatic b- cells are glucokinase (GQ ; HQ IV) of high Km (12-20 mM). We observed that GQ is present in the small intestine and may contribute to the production of lactate during the absorption of sugar. In this work, the effect of diet (ratarina R, G 60% glucose, sucrose S; starch A; casein C) provided ad libitum , on the activities of HQ and GQ in liver homogenates of rat intestinal mucosa . The supply of glucose (5%) in the drinking water ( SG ) was also evaluated in the diets with R and G. HQ activities (Glucose 1 mM) and phosphorylating full capacity ( CFT : Glucose = 100 mM ) were determined enzymatically . GQ was estimated by difference. In the control group (R) and S, A and C, the GQ liver was about 85% of CFT, whereas G, GSG and RSG 66%. The intestinal HQ reached in the R groups, GSG, A and C by 87% and 30% RSG the CFT. The GQ in G, S , increased , but a lower magnitude. the presence of glucokinase in the small intestine and its differential expression according to diet, open the possibility that this structure contributes to initial metabolism of glucose and provide to the liver a precursor (lactate) very effective for their anabolic processes.