Both Duchenne and golden retriever muscular dystrophy (GRMD) are caused by dystrophin deficiency. The Duchenne muscular dystrophy sartorius muscle and orthologous GRMD cranial sartorius (CS) are relatively spared/hypertrophied. We completed hierarchical clustering studies to define molecular mechanisms contributing to this differential involvement and their role in the GRMD phenotype. GRMD dogs with larger CS muscles had more severe deficits, suggesting that selective hypertrophy could be detrimental. Serial biopsies from the hypertrophied CS and other atrophied muscles were studied in a subset of these dogs. Myostatin showed an age-dependent decrease and an inverse correlation with the degree of GRMD CS hypertrophy. Regulators of myostatin at the protein (AKT1) and miRNA (miR-539 and miR-208b targeting myostatin mRNA) levels were altered in GRMD CS, consistent with down-regulation of myostatin signaling, CS hypertrophy, and functional rescue of this muscle. mRNA and proteomic profiling was used to identify additional candidate genes associated with CS hypertrophy. The top-ranked network included α-dystroglycan and like-acetylglucosaminyltransferase. Proteomics demonstrated increases in myotrophin and spectrin that could promote hypertrophy and cytoskeletal stability, respectively. Our results suggest that multiple pathways, including decreased myostatin and up-regulated miRNAs, α-dystroglycan/like-acetylglucosaminyltransferase, spectrin, and myotrophin, contribute to hypertrophy and functional sparing of the CS. These data also underscore the muscle-specific responses to dystrophin deficiency and the potential deleterious effects of differential muscle involvement.
Background:Social networking sites like Facebook, Orkut and Twitter are virtual communities where users can create individual public profiles, interact with real-life friends and meet other people based on shared interests. An exponential rise in usage of Social Networking Sites have been seen within the last few years. Their ease of use and immediate gratification effect on users has changed the way people in general and students in particular spend their time. Young adults, particularly teenagers tended to be unaware of just how much time they really spent on social networking sites. Negative correlates of Social Networking Sites usage include the decrease in real life social community participation and academic achievement, as well as relationship problems, each of which may be indicative of potential addiction.Aims:the aim of the study was to find out whether teenagers, specially those living in cities spend too much time on social networking websites.Materials and Methods:200 subjects, both boys and girls were included in the cross sectional study who were given a 20 item Young's internet addiction test modified for social networking sites. The responses were analyzed using chi square test and Fisher's exact test.Results:24.74% of the students were having occasional or ‘frequency’ problems while 2.02% of them were experiencing severe problems due to excessive time spent using social networking sites.Conclusion:With the ever increasing popularity of social media, teenagers are devoting significant time to social networking on websites and are prone to get ‘addicted’ to such form of online social interaction.
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