Effect of ß-hydroxy-ß-methylbutyrate in masticatory muscles of rats.

The aim of this research was to examine the influence of ß-hydroxy-ß-methylbutyrate (HMB) on changes in the profile of muscle fibers, whether these alterations were similar between the elevator and depressor muscles of the jaw, and whether the effects would be similar in male and female animals. Fifty-eight rats aged 60 days (29 animals of each gender) were divided into four groups: the initial control group (ICG) was sacrificed at the beginning of the experiment; the placebo control group (PCG) received saline and was fed ad libitum; the experimental group (EG) received 0.3 g kg(-1) of HMB daily for 4 weeks by gavage as well as the same amount of food consumed by the PCG in the previous day; and the experimental ad libitum group (EAG) received the same dose of the supplement along with food ad libitum. Samples included the digastric and masseter muscles for the histoenzymological analysis. Data were subjected to statistical analysis with a significance level of P < 0.05. Use of HMB caused a decrease in the percentage of fast twitch glycolytic (FG) fibers and an increase in fast twitch oxidative glycolytic (FOG) fibers in males in both experimental groups (EG and EAG). However, it produced no increase in the muscle fiber area, in either gender, in the masseter muscle. In the digastric muscle, the HMB did not change the frequency or the area of any muscle fiber types in either gender. Our data suggest that the use of HMB caused small changes in the enzymological profile of fibers of the mastication muscles; the changes were different in the elevator and depressor muscles of the jaw and the results were different depending on gender.

Effect of low-intensity pulsed ultrasound on bone regeneration: biochemical and radiologic analyses.

OBJECTIVES: The purpose of this study was to evaluate the effects of low-intensity pulsed ultrasound at 1.0 MHz on the healing process of fractures with bone loss in the rat fibula by alkaline phosphate level measurement and radiologic analyses. METHODS: Thirty 70-day-old male Wistar rats underwent a bone resection of 2.5 to 3.0 mm between the proximal and middle third of the right fibular diaphysis. The animals were randomly divided into 3 experimental groups: reference (uninjured), control (injured only), and treated (injured and treated with 5 applications of ultrasound, interspersed by 2 days of rest, beginning 24 hours after the osteotomy). Euthanasia was performed at experimental periods of 7 and 14 days. The right hind limb was removed for radiologic analysis. The blood was collected via cardiac puncture to determine the serum alkaline phosphatase activity. RESULTS: The bone fractures had not been completely consolidated in the treated and control group when analysis of the bone took place. At day 7, the serum alkaline phosphatase activity was higher in the treated group (mean ± SD, 72.17 ± 7.02 U/L) compared to the control (65.26 ± 8.41 U/L) and reference (67.21 ± 7.86 U/L) groups. At day 14, higher alkaline phosphatase activity was seen in the control group (68.96 ± 8.12 U/L) compared to the treated (66.09 ± 8.46 U/L) and reference (67.14 ± 7.96 U/L) groups. CONCLUSIONS: The biochemical and radiologic results suggest that low-intensity pulsed ultrasound can be used as an auxiliary method to consolidate fractures and probably reduces the bone healing time, offering clinical benefits.