Chronic inhibition, self-control and eating behavior: test of a 'resource depletion' model

The current research tested the hypothesis that individuals engaged in long-term efforts to limit food intake (e.g., individuals with high eating restraint) would have reduced capacity to regulate eating when self-control resources are limited. In the current research, body mass index (BMI) was used as a proxy for eating restraint based on the assumption that individuals with high BMI would have elevated levels of chronic eating restraint. A preliminary study (Study 1) aimed to provide evidence for the assumed relationship between eating restraint and BMI. Participants (N = 72) categorized into high or normal-range BMI groups completed the eating restraint scale. Consistent with the hypothesis, results revealed significantly higher scores on the weight fluctuation and concern for dieting subscales of the restraint scale among participants in the high BMI group compared to the normal-range BMI group. The main study (Study 2) aimed to test the hypothesized interactive effect of BMI and diminished self-control resources on eating behavior. Participants (N = 83) classified as having high or normal-range BMI were randomly allocated to receive a challenging counting task that depleted self-control resources (ego-depletion condition) or a non-depleting control task (no depletion condition). Participants then engaged in a second task in which required tasting and rating tempting cookies and candies. Amount of food consumed during the taste-and-rate task constituted the behavioral dependent measure. Regression analyses revealed a significant interaction effect of these variables on amount of food eaten in the taste-and-rate task. Individuals with high BMI had reduced capacity to regulate eating under conditions of self-control resource depletion as predicted. The interactive effects of BMI and self-control resource depletion on eating behavior were independent of trait self-control. Results extend knowledge of the role of self-control in regulating eating behavior and provide support for a limited-resource model of self-control. © 2013 Hagger et al

Novel strategies in tendon and ligament tissue engineering: Advanced biomaterials and regeneration motifs

Tendon and ligaments have poor healing capacity and when injured often require surgical intervention. Tissue replacement via autografts and allografts are non-ideal strategies that can lead to future problems. As an alternative, scaffold-based tissue engineering strategies are being pursued. In this review, we describe design considerations and major recent advancements of scaffolds for tendon/ligament engineering. Specifically, we outline native tendon/ligament characteristics critical for design parameters and outcome measures, and introduce synthetic and naturally-derived biomaterials used in tendon/ligament scaffolds. We will describe applications of these biomaterials in advanced tendon/ligament engineering strategies including the utility of scaffold functionalization, cyclic strain, growth factors, and interface considerations. The goal of this review is to compile and interpret the important findings of recent tendon/ligament engineering research in an effort towards the advancement of regenerative strategies

Mesenchymal Stem Cell Therapy Regenerates the Native Bone-Tendon Junction after Surgical Repair in a Degenerative Rat Model

BACKGROUND: The enthesis, which attaches the tendon to the bone, naturally disappears with aging, thus limiting joint mobility. Surgery is frequently needed but the clinical outcome is often poor due to the decreased natural healing capacity of the elderly. This study explored the benefits of a treatment based on injecting chondrocyte and mesenchymal stem cells (MSC) in a new rat model of degenerative enthesis repair. METHODOLOGY: The Achilles' tendon was cut and the enthesis destroyed. The damage was repaired by classical surgery without cell injection (group G1, n = 52) and with chondrocyte (group G2, n = 51) or MSC injection (group G3, n = 39). The healing rate was determined macroscopically 15, 30 and 45 days later. The production and organization of a new enthesis was assessed by histological scoring of collagen II immunostaining, glycoaminoglycan production and the presence of columnar chondrocytes. The biomechanical load required to rupture the bone-tendon junction was determined. PRINCIPAL FINDINGS: The spontaneous healing rate in the G1 control group was 40%, close to those observed in humans. Cell injection significantly improved healing (69%, p = 0.0028 for G2 and p = 0.006 for G3) and the load-to-failure after 45 days (p<0.05) over controls. A new enthesis was clearly produced in cell-injected G2 and G3 rats, but not in the controls. Only the MSC-injected G3 rats had an organized enthesis with columnar chondrocytes as in a native enthesis 45 days after surgery. CONCLUSIONS: Cell therapy is an efficient procedure for reconstructing degenerative entheses. MSC treatment produced better organ regeneration than chondrocyte treatment. The morphological and biomechanical properties were similar to those of a native enthesis

Rotator cuff repair: challenges and solutions

Michael H Amini,1 Eric T Ricchetti,1 Joseph P Iannotti,1 Kathleen A Derwin2 1Orthopaedic and Rheumatologic Institute, Cleveland Clinic, Cleveland, OH, USA; 2Department of Biomedical Engineering and Orthopaedic Surgery, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA Abstract: Each year, 250,000 rotator cuff repairs are performed in the United States at a cost of $3 billion. Despite advancements in repair techniques and rehabilitation, 20%&ndash;70% of repairs continue to undergo structural failure; however, there is a poor correlation between clinical and structural outcomes, both before and after surgery. &quot;Failure in continuity&quot;, or retraction of the repair site without a structural defect, is likely a common phenomenon after rotator cuff repair, and this retraction of the myotendinous unit and interposing scar tissue may be one explanation for the discordance between clinical and structural outcomes. Scaffolds, both synthetic and biologic, have shown promise in both augmentation of repairs and interposition of irreparable tears, but most studies are small retrospective case series without control groups. Future efforts will need to determine the ideal indications for use, methods of application, and comparative effectiveness between the devices. Platelet-rich plasma also has potential to improve rotator cuff healing, but current limitations include the significant variation in preparation methods, biologic makeup, and application methods. Future work may help us understand whether application of platelet-rich plasma and its growth factors should be done at the time of surgery or later during a more advanced stage of healing. Regardless of the device or technique, mechanical and/or biologic augmentation of rotator cuff repairs requires the surgeon to be technically proficient in its use and aware of its associated increased operative time and cost. In order to justify the use of these technologies and their associated incremental cost, we must demonstrate efficacy in improving both clinical and structural outcomes. Keywords: rotator cuff, repair, tear, augmentation, scaffold, biologic, PR