Enhanced healing outcomes in MRL/MpJ mouse tissues conserved in insertion site following surgical repair.

BACKGROUND: Surgical repair of supraspinatus tendons (SSTs) has a high failure rate at the insertion site. A significant hurdle to therapeutic development is that effective intrinsic healing mechanisms are unknown. The MRL/MpJ (MRL) mouse exhibits tissue-specific enhanced healing; however, these tissues exhibit disparate properties from the complex SST. The extent of SST healing in the complex environment of the rotator cuff is unknown. We hypothesized that MRL mice would exhibit enhanced restoration of the structurally complex insertion site, resulting in functional improvements. METHODS: B6 and MRL mice underwent SST detachment and immediate surgical repair. Mice were analyzed for gait assessment after either 2 or 6 weeks and were then killed humanely for immunohistologic analysis. RESULTS: MRL SSTs demonstrated enhanced recovery of zonal architecture and bone structure compared with B6 SSTs. MRL SSTs exhibited decreased levels of type III collagen at 2 weeks and increased levels of type I procollagen at 6 weeks compared with B6 SSTs. MRL mice experienced initial gait deficits at 2 weeks that had recovered by 6 weeks. DISCUSSION: The temporal balance of collagen in MRL mice suggests recovery toward naive composition. Initial gait deficits in MRL mice may provide a protective loading environment that is ultimately beneficial. The mechanisms of enhanced healing observed previously in MRL mice may be conserved in the complex SST, providing a platform to interrogate specific aspects of improved healing.

Does measuring body weight impact subsequent response to eating behavior questions?

OBJECTIVES: If being weighed impacts perceptions of eating behavior, it is important that the order of questionnaires and weighing be considered in research and practice. A quasi-experimental study was performed to examine whether being weighed immediately prior to completing a questionnaire affects responses to eating behavior questions. It was hypothesized that being weighed would serve as a priming stimulus and increase measures of dietary restraint, disinhibition, and hunger. METHODS: Trained researchers collected a sample of volunteers (n = 355) in 8 locations in the United States on two Saturdays in the summer of 2011. Half of the participants were weighed immediately prior to completing the Three Factor Eating Questionnaire (TFEQ), with the remaining half weighed immediately after TFEQ completion. RESULTS: A priori hypotheses were not supported despite replicating known relationships between weight, dietary restraint and disinhibition. Results indicated that being weighed first produced a difference in differences on disinhibition scores between low restraint score (95% CI = 4.65-6.02) and high restraint score (95% CI = 6.11-7.57) compared to being weighed after questionnaire completion (p = 0.003). However, this relationship was not significant when modeling restraint as a continuous variable, questioning the use of dichotomization. CONCLUSIONS: Being weighed is unlikely to be a strong enough prime to significantly change scores on eating behavior questionnaires for everyone, but may allow differences in restraint status to become more evident. Researchers assessing dietary restraint should be wary of the possibility of producing different results when treating restraint as continuous or dichotomous, which could lead to different interpretations.