Systematic test of neurotoxin dose and volume on muscle function in a rat model

Introduction: Onabotulinum toxin serotype A (BT‐A) is used for a variety of motor and sensory disorders related to abnormal muscle activity. Methods: We developed a high‐resolution rodent model to allow precise determination of the effect of BT‐A dose (measured in units) and injectate volume (measured in μl) on the efficacy of the injection and systemic side effects. Dorsiflexion is the best indicator of injected and contralateral muscle function. Results: One month after injection, dorsiflexion torque of BT‐A‐injected limbs was decreased significantly in all experimental groups compared with saline controls (P < 0.05). Torque was also compared among the BT‐A groups, which demonstrated a significant effect of dose (P < 0.001), but no effect of volume (P > 0.2) and no dose × volume interaction (P > 0.3). Similar results were observed for other parameters measured. Conclusions: These data demonstrate that injection dose and not volume or concentration is the primary determinant of neurotoxin efficacy in a rodent model. Muscle Nerve 49 : 709–715, 2014     

Stakeholder involvement in Multi-Criteria Decision Analysis

This brief perspective highlights the importance of decision maker buy-in and ownership through stakeholder engagement in the co-construction of the multi-criteria decision analysis (MCDA) model. A brief historical overview of MCDA is presented before outlining the importance of bridging the gap (and to gain trust) between the tool developers and users. The issues with the current MCDA tool development and testing efforts are highlighted, and the ownership and routine adoption of the MCDA process is discussed.     

Leg loading during quiet standing and sit-to-stand movement for one year after total hip arthroplasty

Background: The objective of the present study was to investigate loading of the operated leg during quiet standing and sit-to-stand (STS) movement for 1 year after total hip arthroplasty (THA). Methods: One hundred and fifty-eight patients with end-stage hip osteoarthritis (OA) who had undergone unilateral primary THA participated in this study. The load distribution on the operated and non-operated legs was computed by measuring the vertical reaction force of the operated and non-operated legs during quiet standing and STS movement. We investigated the load distribution using Pressure Distribution Measurement Platform preoperatively and 1, 2, 3, 6, and 12 months postoperatively. Findings: Loading of the operated leg during quiet standing was restored 1 month postoperatively. Loading of the operated leg during STS movement was higher within 2 months postoperatively than the preoperative levels and continued to increase 1 year postoperatively. Loading of the operated leg was lower during STS movement than that during quiet standing, even 1 year postoperatively. Interpretation: A longitudinal and dynamic assessment of loading of the operated leg after THA is clinically important, and the loading during STS movement might continue to increase for a year after THA.     

Skeletal muscle satellite cells: Mediators of muscle growth during development and implications for developmental disorders

Satellite cells (SCs) are the muscle stem cells responsible for longitudinal and cross‐sectional postnatal growth and repair after injury and which provide new myonuclei when needed. We review their morphology and contribution to development and their role in sarcomere and myonuclear addition. SCs, similar to other tissue stem cells, cycle through different states, such as quiescence, activation, and self‐renewal, and thus we consider the signaling mechanisms involved in maintenance of these states. The role of the SC niche and their interactions with other cells, such as fibroblasts and the extracellular matrix, are all emerging as major factors that affect aging and disease. Interestingly, children with cerebral palsy appear to have a reduced SC number, which could play a role in their reduced muscular development and even in muscular contracture formation. Finally, we review the current information on SC dysfunction in children with muscular dystrophy and emerging therapies that target promotion of myogenesis and reduction of fibrosis. Muscle Nerve 50 : 723–732, 2014