No abstract

Streptococcus mutans is the primary agent of dental cavities, in large part due to its ability to adhere to teeth and create a molecular scaffold of glucan polysaccharides on the tooth surface. Disrupting the architecture of S. mutans biofilms could help undermine the establishment of biofilm communities that cause cavities and tooth decay. Here we present a synthetic peptide P1, derived from a tick antifreeze protein, which significantly reduces S. mutans biofilm formation. Incubating cells with this peptide decreased biofilm biomass by approximately 75% in both a crystal violet microplate assay and an in vitro tooth model using saliva-coated hydroxyapatite discs. Bacteria treated with peptide P1 formed irregular biofilms with disconnected aggregates of cells and exopolymeric matrix that readily detached from surfaces. Peptide P1 can bind directly to S. mutans cells but does not possess bactericidal activity. Anti-biofilm activity was correlated with peptide aggregation and β-sheet formation in solution, and alternative synthetic peptides of different lengths or charge distribution did not inhibit biofilms. This anti-biofilm peptide interferes with S. mutans biofilm formation and architecture, and may have future applications in preventing bacterial buildup on teeth.

Background Little is known about diet quality with a reduced-energy, low-fat, partial meal replacement (PMR) plan, especially in individuals with type 2 diabetes. The Action for Health in Diabetes (Look AHEAD) trial implemented a PMR plan in the intensive lifestyle intervention (ILI). Objective Compare dietary intake and percent meeting fat-related and food group dietary recommendations in ILI and diabetes support and education (DSE) groups at 12 months. Design Randomized controlled trial, comparing ILI to DSE, at 0- and 12-months. Participants/setting From 16 United States sites, the first 50% of participants (aged 45 to 76 years, overweight or obese, with type 2 diabetes) were invited to complete dietary assessments. Complete 0- and 12-month dietary assessments (collected between 2001 and 2004) were available on 2,397 participants (46.6% of total participants), with 1,186 randomized to DSE and 1,211 randomized to ILI. Main outcome measures A food frequency questionnaire assessed intake: energy; percent energy from protein, fat, carbohydrate, polyunsaturated fatty acids (PUFA), and saturated fats; trans fatty acids; cholesterol; fiber; weekly meal replacements (MRs); and daily servings from food groups from the Food Guide Pyramid. Statistical analyses performed Mixed-factor analyses of covariance (ANCOVA), using Proc MIXED with a repeated statement, with age, sex, race/ethnicity, education, and income controlled. Unadjusted chi-square tests compared percent meeting fat-related and food group recommendations at 12 months. Results At 12 months, ILI had a significantly lower fat and cholesterol intake and greater fiber intake than DSE. ILI consumed more servings/day of fruits; vegetables; and milk, yogurt & cheese; and fewer servings/day of fats, oils & sweets than DSE. A greater percentage of ILI than DSE participants met fat-related and most food group recommendations. Within ILI, a greater percentage of participants consuming ≥ 2 MRs/day than < 1 MR/day met most fat-related and food group recommendations. Conclusions The PMR plan consumed by ILI was related to superior diet quality.

Look AHEAD was a randomized clinical trial designed to examine the long-term health effects of weight loss in overweight and obese individuals with type 2 diabetes. The primary result was that the incidence of cardiovascular events over a median follow up of 9.6 years was not reduced in the intensive lifestyle group relative to the control group. This finding is discussed, with emphasis on its implications for design of clinical trials and clinical treatment of obese people with type 2 diabetes.