Increased Expression of Syncytin-1 in Skeletal Muscle of Humans With Increased Body Mass Index.

Obesity negatively impacts skeletal muscle protein metabolism, and also impairs skeletal muscle maintenance and regeneration. We analyzed muscle biopsy samples from humans with increased body mass index (BMI) (i.e. > 30 kg/m2) and controls (i.e., BMI < 25 kg/m2) for expression of syncytin-1, a fusogenic protein regulating skeletal muscle regeneration. When compared to controls, humans with increased BMI and concomitant reduction in muscle protein synthesis had higher expression of syncytin-1 in skeletal muscle (p < 0.05). Across human subjects, muscle protein synthesis correlated inversely (r = -0.51; p = 0.03) with syncytin-1 expression in muscle. Using a C2C12 cell line we found that expression of syncytin-A (i.e, corresponding protein in murine tissue) is increased by insulin, and that this response is impaired in the presence of fatty acids, whose metabolism is altered within the metabolic environment induced by increased BMI. In C2C12 cells, the response of the protein 4E-BP1, which signals increase in protein synthesis in muscle, resembled that of syncytin-A. These findings provide novel insights into the expression of syncytin-1 in skeletal muscle of humans with increased BMI, as well as its basic regulation by insulin and fatty acids in muscle. The findings signify the need for further research into the regulation of syncytin-1 in skeletal muscle of humans with increased BMI, as well as its biological implications for altering muscle protein metabolism and regeneration.

Airborne particulate concentration during non-thermal nano-pulse stimulation wart clearance is negligible compared to thermal modalities.

OBJECTIVES: As clinicians continue to implement safety protocols amid the global pandemic, considerations to mitigate potential viral transmission of airborne particulates (plume) generated from certain dermatologic procedures are of growing interest. This study intended to measure the change in airborne particulate matter using a non-thermal energy modality called nano-pulse stimulation (NPS) and compare levels of concentration to common thermal modalities (CO2 laser and electrocautery). NPS is a new non-thermal modality that applies nanosecond pulses of electrical energy to induce regulated cell death in cellular structures while sparing the surrounding acellular structure of the dermis. MATERIALS AND METHODS: The study used a Condensation Particle Counter during four types of dermatologic procedures: (1) using non-thermal NPS for the clearance of cutaneous, nongenital warts; (2) an electrocautery treatment of warts; (3) a CO2 laser for facial resurfacing; and (4) an electrocautery procedure for a facelift. Four subjects and a total of 11 warts were treated with NPS while a particle counter was used to detect the average particles per cubic centimeter once per second. The same particle counter was used, for comparison, during a wart removal procedure using electrocautery for comparison, and for control, during a skin resurfacing procedure with a CO2 laser and a facelift in which electrocautery was used. RESULTS: Only one of the 11 NPS wart procedures generated any detectable change in the particulate concentration and that change was negligible in comparison to the increase in particulate concentration measured during the CO2 laser resurfacing and the electrocautery use during a facelift procedure. CONCLUSIONS: Procedures using non-thermal NPS technology do not generate significant plume when applied to eliminate warts, suggesting it is unlikely that this new energy modality would release viral DNA into the air.

Lower Fasted-State but Greater Increase in Muscle Protein Synthesis in Response to Elevated Plasma Amino Acids in Obesity.

OBJECTIVE: Obesity alters protein metabolism in skeletal muscle, but consistent evidence is lacking. This study compared muscle protein synthesis in adults with obesity and in lean controls in the fasted state and during an amino acid infusion. METHODS: Ten subjects with obesity (age: 36 ± 3 years; BMI: 34 ± 1 kg/m2 ) and ten controls (age: 35 ± 3 years; BMI: 23 ± 1 kg/m2 ) received an infusion of L-[2,3,3,4,5,5,5,6,6,6-2 H10 ]leucine (0.15 µmol/kg fat-free mass/min) to measure muscle protein synthesis after an overnight fast and during amino acid infusion. RESULTS: Despite greater muscle mammalian target of rapamycin phosphorylation (P ≤ 0.05), fasted-state mixed-muscle and mitochondrial protein synthesis were lower in subjects with obesity (P ≤ 0.05). However, the change in mixed-muscle protein synthesis during the amino acid infusion was 2.7-fold greater in subjects with obesity (P ≤ 0.05), accompanied by a greater change in S6 kinase-1 phosphorylation (P ≤ 0.05). The change in mitochondrial protein synthesis did not differ between groups (P > 0.05). CONCLUSIONS: Adults with obesity have reduced muscle protein synthesis in the fasted state, but this response is compensated for by a greater change in overall muscle protein synthesis during amino acid infusion.