ABSTRACT
Drastic increases in myofiber number and size are essential to support vertebrate post-embryonic growth. However, the collective cellular behaviors that enable these increases have remained elusive. Here, we created the palmuscle myofiber tagging and tracking system for in toto monitoring of the growth and fates of ~5000 fast myofibers in developing zebrafish larvae. Through live tracking of individual myofibers within the same individuals over extended periods, we found that many larval myofibers readily dissolved during development, enabling the on-site addition of new and more myofibers. Remarkably, whole-body surveillance of multicolor-barcoded myofibers further unveiled a gradual yet extensive elimination of larval myofiber populations, resulting in near-total replacement by late juvenile stages. The subsequently emerging adult myofibers are not only long-lasting, but also morphologically and functionally distinct from the larval populations. Furthermore, we determined that the elimination-replacement process is dependent on and driven by the autophagy pathway. Altogether, we propose that the whole-body replacement of larval myofibers is an inherent yet previously unnoticed process driving organismic muscle growth during vertebrate post-embryonic development.
ABSTRACT
OBJECTIVE: To explore the effects of a 12-week aerobic exercise program with different frequencies on executive functions (EFs) in preschool children. METHOD: Four kindergartens, comprising 126 preschool children in Shanghai, were enrolled in this 12-week cluster randomized controlled trial with a 12-week follow-up period. Kindergartens were allocated to high-frequency (three times a week) or low-frequency (once a week) exercise groups using stratified block randomization. Three core sub-EFs, including inhibition, working memory, and cognitive flexibility, were assessed at baseline, post-intervention, and the 12-week follow-up. RESULTS: Compared to baseline, both groups showed significant improvements in inhibition and working memory after the intervention and at the 12-week follow-up. However, only the high-frequency exercise group demonstrated a significant improvement in cognitive flexibility after the follow-up period. Nonetheless, there were no significant differences in the core sub-functions of EFs between the two groups at the end of the intervention or the follow-up periods. CONCLUSION: A 12-week aerobic exercise of three times a week was insufficient to significantly improve EFs in preschool children compared to once a week. Future studies are needed to examine the dose-response relationship of aerobic exercise on EFs and to verify the effects of different exercise modalities on EFs in preschool children.
ABSTRACT
Purpose: Gross motor skills (GMS) and inhibitory control (IC) which are both development in preschool stage is significant for preschooler to healthy growth. However, the evidence of relationship between them in preschoolers are still insufficient, most of studies only focus on youth. Thus, the aim of this research is to examine the association between GMS and IC in preschool children. Methods: This cross-sectional study used baseline data from a previous intervention study of preschoolers conducted in 2018. GMS were assessed by using the Test for Gross Motor Development (2nd edition) in preschoolers, which includes two subtests of locomotor and object control skills. Total GMS is calculated from the sum of these two subtests. The Fish Flanker task was used to evaluate both accuracy and reaction time of IC. Multivariate linear regression models were established to analyze the relationships between GMS and IC. Results: A total of 123 preschool-age children (55 girls, 68 boys) were included in the final analysis. After adjusting for confounders, GMS (ß = -8.27 ms, 95%CI: -14.2, -2.34), locomotor (ß = -11.2 ms, 95%CI: -21.43, -0.97), and object control skills (ß = -12.15 ms, 95%CI: -22.07, -2.23) were all negatively related with reaction time of IC. Conclusion: There was a significant negative correlation between gross motor skills and the reaction time of inhibitory control in preschool children. Further research is needed to verify this finding in prospective and experimental studies.
ABSTRACT
Background: The results of sedentary time (ST) and health-related physical fitness (HPF) are not completely consistent and the studies concentrated on pre-schoolers are very limited. Methods: We measured ST and ST patterns (ST Bouts time, ST Breaks times) by accelerometer. The health-related physical fitness T-score (HPFT) was calculated by five indexes: height-weight standard score, 20 m shuttle-run test, grip strength, standing long jump and 2 × 10 m shuttle-run test. Results: We included 375 pre-schoolers (211 boys, 164 girls) in the final analysis. The total ST and ST Bouts times negatively correlated with HPFT in pre-schoolers. HPFT reduced by 1.69 and 0.70 points per 10 min increased in total ST and ST Bouts times, respectively. HPFT of the highest quartile group reduced by 9.85 points in total ST, and 10.54 points in ST Bouts time compared with the lowest quartile group. However, the HPFT increased by 0.09 points per 10 times increased in ST Breaks times; the HPFT increased by 16.21 and 15.59 points when moderate to vigorous physical activity (MVPA) replaced total ST and ST Bouts time. Conclusions: HPF negatively correlated with the Total ST and ST Bouts times, but positively correlated with ST Breaks times; and HPF significantly improved when MVPA replaced ST in pre-schoolers.
ABSTRACT
PURPOSE: To investigate the relationships between daily step counts and physical fitness in preschool children. METHODS: Preschoolers' step counts were assessed by ActiGraph accelerometers consecutively for seven days. Physical fitness was assessed by a 20 m shuttle run test (cardiorespiratory fitness), the handgrip and standing long jump tests (musculoskeletal fitness), and the 2 × 10 m shuttle run test (speed/agility). A composite score was created from the mean of the standardized values of all physical fitness tests. RESULTS: A total of 301 preschoolers (134 girls, mean age 57.40 ± 5.47 months; 167 boys, mean age 58.10 ± 5.34 months) were included in the final analysis. Compared with the lowest tertile, boys and girls in the highest tertile of step counts achieved high physical fitness with odds ratio (OR) being 5.39 (95% CI = 1.65-17.59) and 4.42 (95% CI = 1.30-14.99), respectively, after adjusting for confounders. Meanwhile, a relationship was observed for each 1000 steps/day increment being associated with 43% (OR = 1.43, 95% CI = 1.10-1.85) and 62% (OR = 1.62, 95% CI = 1.20-2.19) increment for high physical fitness in boys and girls, respectively. In addition, significant non-linear relationship was observed between daily steps and physical fitness in boys, which indicated that accumulated 8000 steps/day was associated with the highest ratio to achieve high physical fitness. CONCLUSIONS: Positive relationships between step counts and physical fitness were observed in preschool children, and the relationships were strongest for those who accumulated 8000 steps/day in boys. To confirm the findings in this study, well-designed and large-scale longitudinal studies are needed in the future.
ABSTRACT
We design and fabricate a deformable frequency selective surface (FSS) structure using shape memory alloys (SMA). The unit cell could "remember" two different geometrical shapes and the shapes convert to each other alternately during heating and cooling, that leads to the drift of resonant frequency. Qualitative analysis by equivalent circuit model and accurate numeric calculation are compared to display the character of the transmission. The measurements show that a tuning range of frequency from 13.07GHz to 16.29GHz is achieved when the morphology of the unit cell changes, making the deformable FSS an attractive choice for tunable filter in different frequency bands with the features of wide tuning range and sharp cut-off.
