Impact of age on host responses to diet-induced obesity:Development of joint damage and metabolic set points

Background:Osteoarthritis is one of the leading causes of pain and disability worldwide,and a large percentage of patients with osteoarthritis are individuals who are also obese.In recent years,a series of animal models have demonstrated that obesity-inducing diets can result in synovial joint damage(both with and without the superimposition of trauma),which may be related to changes in percentage of body fat and a series of low-level systemic inflammatory mediators.Of note,there is a disparity between whether the dietary challenges commence at weaning,representing a weanling onset,or at skeletal maturity,representing an adult onset of obesity.We wished to evaluate the effect ofthe dietary exposure time and the age at which animals are exposed to a high-fat and high-sucrose(HFS) diet to determine whether these factors may result in disparate outcomes,as there is evidence suggesting that these factors result in differential metabolic disturbances.Based on dietary exposure time,we hypothesized that rats fed an HFS diet for 14 weeks from weaning(HFS Weanling) would demonstrate an increase in knee joint damage scores,whereas rats exposed to the HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult) and rats exposed to a standard chow diet(Chow)would not display an increase in knee joint damage scores.Methods:Male Sprague-Dawley rats were fed either an HFS diet for 14 weeks from weaning(HFS Weanling) or an HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult).At sacrifice,joints were scored using the modified Mankin Criteria,and serum was analyzed for a defined subset of inflammatory markers(Interleukin-6,leptin,monocyte chemoattractant protein-1,and tumor necrosis factorα).Results:When the HFS Weanling and HFS Adult groups were compared,both groups had a similar percent of body fat,although the HFS Weanling group had a significantly greater body mass than the HFS Adult group.The HFS Weanling and HFS Adult animals had a significant increase in body mass and percentage of body fat when compared to the Chow group.Although knee joint damage scores were low in all 3 groups,we found,contrary to our hypothesis,that the HFS Adult group had statistically significant greater knee joint damage scores than the Chow and HFS Weanling groups.Furthermore,we observed that the HFS Weanling group did not have significant differences in knee joint damage scores relative to the Chow group.Conclusion:These findings indicate that the HFS Weanling animals were better able to cope with the dietary challenge of an HFS diet than the HFS Adult group.Interestingly,when assessing various serum proinflammatory markers,no significant differences were detected between the HTS Adult and HFS Weanling groups.Although details regarding the mechanisms underlying an increase in knee joint damage scores in the HFS Adult group remain to be elucidated,these findings indicate that dietary exposure time maybe less important than the age at which an HFS diet is introduced.Moreover,increases in serum proinflammatory mediators do not appear to be directly linked to knee joint damage scores in the HFS Weanling group animals but may be partially responsible for the observed knee joint damage in the adults over the very short time of exposure to the HFS diet.     

Analyzing and Selecting Instructional Strategies and Tactics

“Formulation of instructional strategy to match subject matter and learner requirements” is an integral part of most instructional design models (Andrews & Goodson, 1980, p.5). Yet the meaning and purpose of instructional strategies in these design models vary considerably. An instructional strategy in traditional design models usually refers to the selection of instructional delivery vehicles (e.g., lecture, demonstration, computer-assisted instruction) and support activities (e.g., practice exercises, tutoring) (cf. Tracey, Flynn, <& Legere, 1970). Contrast those conceptions with the many instructional strategies described in elaboration theory (Reigeluth & Stein, 1983), such as sub-sumptive sequencing, internally consistent orienting structures, synthesizers, summarizers, and cognitive strategy activators. What is obvious from these disparate conceptions is that instructional designers do not share a consistent definition of instructional strategies. Many of the activities that are referred to as instructional strategies are not in fact strategies, but rather are presentation vehicles. In this article, we first define instructional strategies and tactics in the context of an iterative design model. Instructional strategies are then distinguished from instructional tactics, which are the implementation of strategies. We then list the range of instructional strategies and tactics that implement them. Finally, we provide a decision tree for assisting designers to select appropriate instructional tactics.     

The Perception of Scientific Authorship Across Domains

Minerva - We extend previous research by systematically investigating whether perceptions of scientific authorship vary between domains. Employing regulations for authorship of scientific journals...     

Concurrent validity of the Woodcock-Johnson tests of cognitive ability with the WISC-R: EMR children

The Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Woodcock-Johnson Tests of Cognitive Ability (WJTCA) were administered in a counterbalanced order to 30 children referred for a three-year reevaluation. All children were currently placed in an educable mentally retarded (EMR) program. The children ranged in age from 8-0 to 12-5 years, with a mean of 10-6. The correlation coefficient between the WISC-R and WJTCA was observed to be .72. Significant mean differences were found between the WISC-R and WJTCA full scale standard scores. The implications of the findings are discussed relative to the placement of children in classes for the mentally retarded. Explanations for the mean differences between the WJTCA and WISC-R also are explored.