Muscle biopsy has long been expected to be replaced by noninvasive biomarkers with diagnostic value and prognostic applications for muscle atrophy. Growing evidence suggests that circulating microRNAs (miRNAs) could act as biomarkers for numerous pathophysiological statuses. In the present study, our results showed that the serum levels of six muscle-specific miRNAs (miR-1/23a/133/206/208b/499) were all elevated in unloading induced mice. The medium levels of these six muscle-specific miRNAs were all elevated in starvation induced atrophic C2C12 myotubes. Moreover, the serum levels of miR-23a/206/499 were induced in participants after 45 days of head-down bed rest (HDBR). The levels of miR-23a/206/499 were positively correlated with the ratio of soleus volume loss in HDBR participants, indicating that they might represent the process of muscle loss. In conclusion, our results demonstrated that circulating miRNAs could serve as useful biochemical and molecular indicators for muscle atrophy diagnosis and disease progression.

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Objective With the prevalence of electronic media use among Chinese adolescents and concerns regarding its potential negative consequences on their health and development, this study investigated the relationship between physical exercise and electronic media use. Utilizing data from the China Education Panel Survey, we examine the impact of physical activity on adolescents’ electronic media use. Methods A simultaneous equation model, including two-stage least square and three-stage least square, was employed to estimate the impact of physical activity on electronic media use among adolescents. Self-control theory and media addiction theory were also used to analyze electronic media use in adolescents. Descriptive statistics were used to analyzed the data. Results Chinese adolescents dedicated a substantial amount of time, averaging 2.95 hours per day, to electronic media activities. Increasing physical activity demonstrated an effective means to reduce electronic media use. Furthermore, the impact of physical activity on electronic media use exhibited urban-rural stratification, with family factors related to social class status primarily influencing electronic media use among urban students, while physical activity has a more pronounced influence among rural students. Conclusions Promoting physical activity represents a compelling and effective strategy for curbing excessive electronic media use among Chinese adolescents, particularly in rural areas where physical activity has a stronger influence. In addition, controlling media entertainment and recreation time and enhancing social cohesion can help to weaken media interest. While changing the social class status of families in urban areas may be difficult in the short term, parents should be aware that physical exercise is an effective way to reduce their children’s use of electronic media. Our findings suggested that promoting physical activity may be a promising strategy for reducing excessive electronic media use among Chinese adolescents, particularly in rural areas where physical activity has a stronger influence.

In this paper, a line-frequency dual input-voltagelevel LED driver is proposed. The conventional AC LED topologies are operated with single input voltage level, which cannot be suitable for both two major utility voltage levels of 110 V and 220 V. The proposed LED driver utilizes the automatic parallel/series switching mechanism to achieve the compatibility with the input voltages of 110 V and 220 V. Since the LED driver possesses the current-limiting mechanism, it can prevent LEDs from overcurrent no matter what the input voltage is. Finally, the prototype circuit of line-frequency dual input-voltage-level LED driver is built to verify the performances.978-1-4799-6735-3/15/$31.00 ©2015 IEEE