👤 Naomi Nakagata

The association between exercise behaviors-including physical activity (PA), light-intensity PA (LPA), moderate-to-vigorous-intensity PA (MVPA), sedentary behavior (SB), and sleep-and muscle quality remains unclear. This study aimed to examine the association between 24-h movement behaviors and muscle quality, as assessed by bioelectrical impedance spectroscopy (BIS). A total of 294 participants were enrolled in the cross-sectional study. LPA, MVPA, and SB were objectively measured using a tri-axial accelerometer. Sleep duration was assessed through a validated self-reported questionnaire. Muscle quality, based on electrical properties, was evaluated using a BIS device including parameters such as phase angle, intracellular-to-extracellular water ratio, membrane capacitance, characteristic frequency. Associations between 24-h movement behaviors and muscle quality derived from electrical properties were examined using compositional multiple linear regression. Additionally, hypothetical time reallocations among different movement behaviors in relation to muscle quality were evaluated using compositional isotemporal substitution. The same analyses were also conducted among participants classified as non-regular exercisers. Longer durations of MVPA were significantly associated with better indicators of muscle quality. Theoretical time reallocation analyses suggested that 30 min from SB, LPA, or sleep to MVPA was associated with approximately 0.5-3.8% higher values of BIS-derived muscle quality indices. This association remained consistent among non-regular exercisers. These cross-sectional findings indicate that greater daily MVPA is associated with a more favorable BIS-derived muscle-quality profile. MVPA is a key component of daily movement that contributes to the maintenance and potential improvement of muscle quality, as evaluated through electrical properties measured using BIS in both regular and non-regular exercisers. Show less

The exchange of genetically engineered mouse strains between research facilities requires transporting fresh mouse sperm under refrigerated temperatures. Although sperm generally maintains fertility for 48 h at cold temperatures, in vitro fertilization rates of C57BL/6 mouse sperm are low after 48-h cold storage. Furthermore, 48 h is often not sufficient for the specimens to reach their destinations. To increase the availability of this technology, we aimed to extend the cold storage period while maintaining sperm fertility. In this study, we determined the optimal medium for sperm preservation and evaluated the effect of reduced glutathione in the fertilization medium on sperm fertility after cold storage. We found that higher fertility levels were maintained after 72-h cold storage in the preservation medium Lifor compared with storage in paraffin oil, M2 medium, or CPS-1 medium. In addition, 1.0 mM glutathione enhanced sperm fertility. After transporting sperm from Asahikawa Medical University to our laboratory, embryos were efficiently produced from the cold-stored sperm. After transfer, these embryos developed normally into live pups. Finally, we tested the transport system using genetically engineered mouse strains and obtained similar high fertilization rates with all specimens. In summary, we demonstrated that cold storage of sperm in Lifor maintains fertility, and glutathione supplementation increased the in vitro fertilization rates of sperm after up to 96 h of cold storage. This improved protocol provides a simple alternative to transporting live animals or cryopreserved samples for the exchange of genetically engineered mouse strains among research facilities. Show less