| Popis: |
Non-thermal ultrasound (US) is commonly used in an attempt to improve tissue repair and regeneration, although the efficacy of this practice is not firmly established. Previous research has investigated only a few dependent variables at discreet points in time. Therefore, the purposes of these studies were to examine the influence of non-thermal ultrasound markers on skeletal muscle regeneration and to compare 4 different combinations of duty cycle and SAI representing two common SATA intensities. Design and Setting: Multifactorial designs comparing treatment, duty cycle, SATA, and time were used. A bilateral contusion injury to the gastrocnemius via a drop mass technique was performed. US administration commenced 24-hr post-injury and was delivered 5minutes daily on 4 consecutive days. Rats received the US treatment on their left hindlimb, and the contralateral right hindlimb served as a non-US control. Subjects: Male Wistar rats were used in this study and the protocol was ILACUC approved. Measurements: Dependent variables included muscle mass, fiber cross-sectional area, centrally localized nuclei, embryonic myosin heavy chain, MGF (muscle specific IGF-1), M-cadherin, and MyoD. Data were analyzed using a factorial MANOVA. Results: US increased muscle mass more than no treatment (P < 0.0001) and increases in muscle mass were found with the continuous US treatment compared to the pulsed duty cycle treatment at the same SATA (P = 0.019). In the second experiment, ultrasound treatments also statistically significantly affected MGF levels compared to non-treated hind limb (P = 0.029). There was an effect observed for the day post-injury for MGF (P = 0.014). Post-hoc testing revealed that the MGF value on 1 day post-injury was statistically greater than the values observed for days 3 and 4 after injury. Conclusions: The specific non-thermal ultrasound treatments we studied had beneficial effects on skeletal muscle regeneration following blunt trauma. When comparing US treatments providing identical energy delivery, a continuous duty cycle has a greater influence on skeletal muscle regeneration following blunt trauma than does a pulsed duty cycle. |
