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PURPOSE: The purpose of this study was to investigate the age-related changes in diastolic filling parameters in the aging hearts of active C57Bl/6J mice throughout the life span to indicate optimal age periods for improvements in resting diastolic parameters. METHODS: Fourteen C57Bl/6J mice (seven males and seven females) were individually housed at 8 wk of age in cages with a running wheel, magnetic sensor, and digital odometer. Duration, distance, and running velocity were recorded daily. Fourteen additional mice C57Bl/6J mice (seven males and seven females) were placed in individual cages without running wheels at 8 wk of age. Pulsed-wave Doppler transmitral inflow recordings with a SONOS 5500 ultrasound and 15-6L ultrasound probe were used to image the left ventricle every 4 wk throughout the life span. RESULTS: Peak E wave filling velocities were significantly greater by the start of the second quarter of the life span in the mice with access to running wheels (P < 0.0001). Peak E wave velocities improved in both groups during the first half of the life span (P < 0.0001) and declined throughout the second half of the life span (P < 0.0001). Early-to-late (E:A) filling ratio was significantly greater for the physically active mice by the start of the second quarter of the life span (P < 0.0001) and continued throughout most of the remainder of the life span (P < 0.0001). No differences were observed between the two groups of mice with peak A wave filling velocities (P > 0.05). Similar findings were observed when corrected for resting heart rate. CONCLUSIONS: Lifelong physical activity resulted in greater diastolic filling parameters by the second quarter of the life span, highlighting the clinical importance of regular aerobic activity in young adulthood as a mechanism for improved left ventricular performance with aging. [ABSTRACT FROM AUTHOR]

Ankle sprains are the most common orthopedic pathology experienced during sport and physical activity and often result in chronic ankle instability (CAI). Understanding how to prevent CAI is difficult because of the costs and logistics associated with clinical trials aimed at preventing the heterogeneous symptoms associated with CAI. Thus, a need exists to develop an animal model that presents similar long-term consequences as CAI to assess preclinical data. Thus, the purpose was to determine whether surgically transecting the lateral ligaments of a mouse hind limb results in the development of CAI-like symptoms 12 months after injury. Methods: Thirty male mice (CBA/J) were randomly placed into a SHAM (control), CFL (calcaneofibular ligament; mild ankle sprain), or ATFL/CFL (anterior talofibular ligament/ CFL; severe) ankle sprain group and housed individually. Three days after surgically transecting the respective lateral ligaments, mice were given a solid surface running wheel and daily running wheel measurements were recorded. Outcome measures of balance and gait were obtained before and at 4, 48, 54, and 60 wk after injury. Results: The ATFL/CFL group had significantly more hind foot slips than the CFL and SHAM groups (P < 0.05). The CFL also had more hind foot slips relative to the SHAM group (P < 0.05). The ATFL/CFL group was significantly less physically active relative to the SHAM and CFL groups (P < 0.05). A cut score of 4.75 foot slips had a sensitivity of 0.68 and specificity of 1.00 and indicates that 70% (14/20) of mice with an ankle sprain had developed CAI. Conclusions: The results of this study indicate that an acute ankle sprain in mice can result in the development of CAI-like symptoms 12 months after injury. [ABSTRACT FROM AUTHOR]

Introduction: Ankle sprains remain the most common orthopedic pathology. Conducting long-term studies in humans is difficult and costly, so the long-term consequences of an ankle sprain are not entirely known. Purpose: The objective of this study is to develop and test a mechanical ankle instability model in mice. Methods: Thirty male mice (CBA/2J) were randomly placed into one of three groups: the transected calcaneal fibular ligament (CFL) group, the transected anterior talofibular ligament (ATFL)/CFL group, and a SHAM group. Three days after surgery, all of the mice were individually housed in a cage containing a solid surface running wheel, and daily running wheel measurements were recorded. Before and after surgery, measures of balance and gait were measured on all mice for 4 wk. Results: The mice in the ATFL/CFL group had significantly decreased duration (P = 0.0239), distance (P = 0.013), and speed (P = 0.003) compared with the SHAM group during week 1. During weeks 2 and 3, the ATFL/CFL group had significantly less distance (P = 0.0001) and duration (P = 0.002) compared with the SHAM and CFL-only group. The transection of the lateral ankle ligaments did affect the number of slips experienced during the balance test. The ATFL/CFL group had greater slips at 1 and 4 wk postsurgery (P = 0.05), whereas the CFL-only group had greater slips at 3 d and 1 wk postsurgery (P = 0.05). Relative to the SHAM group, the ATFL/CFL group and CFL-only group had smaller right-stride lengths (involved limb) at 3 d postsurgery (P = 0.05). The ATFL/CFL group also had smaller right-side stride lengths at 1 and 4 wk postsurgery (P = 0.05). Conclusions: The results of this study indicate that a mouse model can be used to induce mechanical instability in the ankle. [ABSTRACT FROM AUTHOR]