Effects of Exercise and Steroid on Apoptosis in Skeletal Muscle of Mdx Mouse

OBJECTIVE: To investigate the effect of exercise and steroid to the muscle of animal model of Duchenne muscular dystrophy. METHOD: We used 15 mdx and 15 control mice. To grade exercise loading, control and mdx mice were divided into free-living, exercise and immobilization groups. Free-living and exercise groups were further divided into steroid-treated and sham-treated groups to evaluate the effect of steroid administration. We measured the apoptotic changes using in situ DNA nick-end labling (TUNEL), DNA fragmentation assay and western blots for Bcl-2 and BAX. RESULT: With TUNEL method, the largest number of myonuclei became positive in sham-treated exercise group while apoptosis was significantly reduced in steroid-treated exercise group in mdx mice. Steroid-treated free-living group showed higher rate of apoptotic change than sham-treated free-living group. With western blots for Bcl-2 and BAX, the value of BAX/Bcl-2 ratio was highest in sham-treated exercise group and among free living mdx mice, it was higher in steroid-treated group than sham-treated one. CONCLUSION: Apoptosis can be minimized in free living condition while exercise loading or immobilization can cause apoptotic change in muscular dystrophy animal model. Steroid administration induces apoptosis in free living muscle and it alleviates apoptotic damage caused by exercise loading in mdx mice.

Effect of Dexamethasone on Experimental Candida Endophthalmitis

The use of intravitreal corticosteroids in the management of endophthalmitis remains controversial. This study was performed to evaluate the effectiveness of dexamethasone(DXM) in Candida endophthalmitis. In rabbits, Candida albicans(3,000 blastospore: Group A, 30,000 blastopore: Group B) was inoculated intrabitreally. At 24, 48, and 72 hours postinoculation, single intravitreal dose of amphotericin B(AMP, 5microgram/0.1ml) with DXM(400microgram/0.1ml) or AMP alone was given. Clinical examination, protein analysis, electrophysiological and histopathologic measures were utilized to rate DXM effectiveness. Dosage of 5microgram AMP resulted in no culture in both Group A and B, On examinations including the electrophysiologic and histopathologic studies, eyes treated with AMP and DXM did not differ from eyes treated with AMP alone in the Group A(p>0.05). On protein analysis for vitreous in the Group B, however, eyes treated with AMP alone at 24 and 48 hours postinoculation(p<0.05). On electrophysiologic study the decrease rate of the amplitude showed the difference between at 24 hours postinoculation and at 48 or 72 hours postinoculation(p<0.05). Histologic preparations showed a mild or moderate cellular infilteration in the vitreous and swelling in the sensory retina, but small abscess in the vitreous observed when treatment was delayed more than 72 hours following inoculation in both Group A and B. DXM in the experimental Candida endophthalmitis had the beneficial effect in eyes with 30,000 blastspore inoculation and in eyes treated with AMP and DXM at 24 hours postinoculation.