Central insulin and macronutrient intake in the rat

When rats are maintained on a standard laboratory diet, the infusion of low doses of insulin into the cerebroventricular system causes a reduction of food intake and body weight. It was recently reported that, if rats are maintained on a high-fat diet (56% calories as fat), they are insensitive to this action of insulin. To investigate further the effect of dietary composition on responsiveness to central insulin, we carried out two experiments. In experiment 1, rats were maintained on one of four equicaloric diets (providing 7, 22, 39, or 54% of calories as fat) before and during a 6-day third-ventricular infusion (i3vt) of insulin (10 mU/day) or saline. Rats consuming 7 or 22% of calories as fat had a significant reduction of both food intake (-17.2 +/- 2.9 and -14.6 +/- 3.3 g, respectively) and body weight (-50 +/- 5 and -41 +/- 5 g, respectively) from baseline over the insulin-infusion period. Rats consuming 39 or 54% calories as fat did not reliably alter food intake (-4.0 +/- 3.9 and -1.9 +/- 3.7 g, respectively) or body weight (-10 +/- 6 and -6 +/- 4 g, respectively) in response to i3vt of insulin. In experiment 2, rats were offered a choice of three macronutrients (carbohydrates, fats, and proteins) in separate jars in their home cages. After they had adapted to the diets, they were infused i3vt with insulin or saline. Insulin caused a significant reduction of body weight relative to saline-infused controls (body wt: -23.1 +/- 4 g) and a reduction in food intake that was selective for dietary fat. These data suggest that the effects of central insulin administration are highly dependent on the macronutrient content of the diet as well as the ability of rats to select their own diets

Xylitol gummy bear snacks: a school-based randomized clinical trial

Background: Habitual consumption of xylitol reduces mutans streptococci (MS) levels but the effect on Lactobacillus spp. is less clear. Reduction is dependent on daily dose and frequency of consumption. For xylitol to be successfully used in prevention programs to reduce MS and prevent caries, effective xylitol delivery methods must be identified. This study examines the response of MS, specifically S. mutans/sobrinus and Lactobacillus spp., levels to xylitol delivered via gummy bears at optimal exposures. Methods: Children, first to fifth grade (n = 154), from two elementary schools in rural Washington State, USA, were randomized to xylitol 15.6 g/day (X16, n = 53) or 11.7 g/day (X12, n = 49), or maltitol 44.7 g/ day (M45, n = 52). Gummy bear snacks were pre-packaged in unit-doses, labeled with ID numbers, and distributed three times/day during school hours. No snacks were sent home. Plaque was sampled at baseline and six weeks and cultured on modified Mitis Salivarius agar for S. mutans/sobrinus and Rogosa SL agar for Lactobacillus spp. enumeration. Results: There were no differences in S. mutans/sobrinus and Lactobacillus spp. levels in plaque between the groups at baseline. At six weeks, log10 S. mutans/sobrinus levels showed significant reductions for all groups (p = 0.0001): X16 = 1.13 (SD = 1.65); X12 = 0.89 (SD = 1.11); M45 = 0.91 (SD = 1.46). Reductions were not statistically different between groups. Results for Lactobacillus spp. were mixed. Group X16 and M45 showed 0.31 (SD = 2.35), and 0.52 (SD = 2.41) log10 reductions, respectively, while X12 showed a 0.11 (SD = 2.26) log10 increase. These changes were not significant. Post-study discussions with school staff indicated that it is feasible to implement an in-classroom gummy bear snack program. Parents are accepting and children willing to consume gummy bear snacks daily. Conclusion: Reductions in S. mutans/sobrinus levels were observed after six weeks of gummy bear snack consumption containing xylitol at 11.7 or 15.6 g/day or maltitol at 44.7 g/day divided in three exposures. Lactobacillus spp. levels were essentially unchanged in all groups. These results suggest that a xylitol gummy bear snack may be an alternative to xylitol chewing gum for dental caries prevention. Positive results with high dose maltitol limit the validity of xylitol findings. A larger clinical trial is needed to confirm the xylitol results. Trial registration: [ISRCTN63160504].Supported by Grant No. U54DE14254 from the National Institute of Dental and Craniofacial Research, and Grant No. 90YD0188 from the Office of Head Start

Principles of Collaborative Education Research with Stakeholders: Toward Requirements for a New Research and Development Infrastructure

A group of collaborative forms of education research sits uneasily within the existing infrastructure for research and development in the United States. Members of this group hold themselves to account to ways of working with schools, families, and communities different from the research models promoted in U.S. policies and endorsed by U.S. federal agencies. Those models privilege individual investigators&rsquo; priorities for research and regularly yield products and findings with little relevance to practice. Four such models are reviewed in this paper: the Strategic Education Research Partnership, Design-Based Implementation Research, Improvement Science within Networked Improvement Communities, and Community-Based Design Research. Through a participatory process involving developers and advocates for these group members&rsquo; approaches, we identified a set of interconnected principles related to collaboration, problem solving, and research. Further, we reviewed evidence for the embodiment of these principles in from four U.S. projects belonging to these approaches by examining a total of 13 journal articles, reports, and book chapters published between 2008 and 2018. Understanding, building, and supporting enactments of these principles is a worthwhile endeavor because there is evidence that these approaches to research can promote agency and equity in education. However, supporting these principles requires criteria for judging quality, which peers can use to evaluate individual studies or sets of research; new outcomes by which to measure progress; new venues for developing and giving accounts of research; and an appreciation for the value of developing and cultivating relationships with educators, families, and communities as an integral part of research.</p

A surrogate method for comparison analysis of salivary concentrations of Xylitol-containing products

Background: Xylitol chewing gum has been shown to reduce Streptococcus mutans levels and decay. Two studies examined the presence and time course of salivary xylitol concentrations delivered via xylitol-containing pellet gum and compared them to other xylitol-containing products. Methods: A within-subjects design was used for both studies. Study 1, adults (N = 15) received three xylitol-containing products (pellet gum (2.6 g), gummy bears (2.6 g), and commercially available stick gum (Koolerz, 3.0 g)); Study 2, a second group of adults (N = 15) received three xylitol-containing products (pellet gum, gummy bears, and a 33% xylitol syrup (2.67 g). For both studies subjects consumed one xylitol product per visit with a 7-day washout between each product. A standardized protocol was followed for each product visit. Product order was randomly determined at the initial visit. Saliva samples (0.5 mL to 1.0 mL) were collected at baseline and up to 10 time points (~16 min in length) after product consumption initiated. Concentration of xylitol in saliva samples was analyzed using high-performance liquid chromatography. Area under the curve (AUC) for determining the average xylitol concentration in saliva over the total sampling period was calculated for each product. Results: In both studies all three xylitol products (Study 1: pellet gum, gummy bears, and stick gum; Study 2: pellet gum, gummy bears, and syrup) had similar time curves with two xylitol concentration peaks during the sampling period. Study 1 had its highest mean peaks at the 4 min sampling point while Study 2 had its highest mean peaks between 13 to 16 minutes. Salivary xylitol levels returned to baseline at about 18 minutes for all forms tested. Additionally, for both studies the total AUC for the xylitol products were similar compared to the pellet gum (Study 1: pellet gum - 51.3 [micro]g.min/mL, gummy bears - 59.6 [micro]g.min/mL, and stick gum - 46.4 [micro]g.min/mL; Study 2: pellet gum - 63.0 [micro]g.min/mL, gummy bears - 55.9 [micro]g.min/mL, and syrup - 59.0 [micro]g.min/mL). Conclusion: The comparison method demonstrated high reliability and validity. In both studies other xylitol-containing products had time curves and mean xylitol concentration peaks similar to xylitol pellet gum suggesting this test may be a surrogate for longer studies comparing various products.NIDCR-NIH U54 DE14254; Head Start, HRSA 90YD0188/03; and MCHB, HRSA R40MC03622-03