YouTube video by Dreamland Songscape

YouTube video by Rijnmond

Новости из СШАТекст и перевод: Игорь Айзенберг Подписывайтесь на канал RЯ - Rashkin Report Facebook: https://www.facebook.com/RashkinReport/Telegram: https:/...

Human studies examining the cellular mechanisms behind sarcopenia, or age-related loss of skeletal muscle mass and function, have produced inconsistent results. A systematic review and meta-analysis were performed to determine the aging effects on protein expression, size, and distribution of fibers with various myosin heavy chain (MyHC) isoforms. Study eligibility included MyHC comparisons between young (18–49 yr) and older (≥60 yr) adults, with 27 studies identified. Relative protein expression was higher with age for the slow-contracting MyHC I fibers, with correspondingly lower fast-contracting MyHC II and IIA values. Fiber sizes were similar with age for MyHC I, but smaller for MyHC II and IIA. Fiber distributions were similar with age. When separated by sex, the few studies that examined females showed atrophy of MyHC II and IIA fibers with age, but no change in MyHC protein expression. Additional analyses by measurement technique, physical activity, and muscle biopsies provided important insights. In summary, age-related atrophy in fast-contracting fibers lead to more of the slow-contracting, lower force-producing isoform in older male muscles, which helps explain their age-related loss in whole muscle force, velocity, and power. Exercise or pharmacological interventions that shift MyHC expression toward faster isoforms and/or increase fast-contracting fiber size should decrease the prevalence of sarcopenia. Our findings also indicate that future studies need to include or focus solely on females, measure MyHC IIA and IIX isoforms separately, examine fiber type distribution, sample additional muscles to the vastus lateralis (VL), and incorporate an objective measurement of physical activity.

YouTube video by Beta Squad

YouTube video by Elliot Sang

The R403Q mutation of human cardiac beta-myosin heavy chain was the first missense mutation of a sar

The R403Q mutation of human cardiac beta-myosin heavy chain was the first missense mutation of a sar

Новости из СШАТекст и перевод: Игорь Айзенберг Подписывайтесь на канал RЯ - Rashkin Report Facebook: https://www.facebook.com/RashkinReport/Telegram: https:/...