Skeletal Muscle Apoptosis and Physical Performance; Oxidative RNA/DNA Damage and Repair in Aged Human Muscle

Plain-language summary

The age-related loss of muscle mass and strength, also termed sarcopenia, is a commonly recognized consequence of aging and has been associated with frailty, functional loss, hospitalization, and increased mortality among older people. Sarcopenia and its consequences have a considerable economic impact, since it has been estimated that the healthcare cost attributable to sarcopenia in the US in 2000 was $ 18.5 billions. Preclinical animal models strongly suggest that apoptosis, a programmed cell death, might play a prominent role in the age-related muscle wasting. In specific aim one, the investigators will assess the extent of muscle apoptosis in muscle biopsies obtained from the vastus lateralis muscle of young control subjects (ages 20-35) and high-performance and low-performance older subjects (age range 70-99 years). In specific aim 2, the investigators will investigate the role of Poly (ADP-ribose) polymerase 1 (PARP-1) and apoptosis-inducing factor (AIF) in the induction of skeletal muscle apoptosis. In specific aim 3, the investigators propose to investigate the contribution of the muscle energy deficit, due to the age-related mitochondrial dysfunction, in the development of muscle wasting. Finally, in specific aim 4, the investigators propose to reassess after four years physical performance, muscle mass and the extent of muscle apoptosis, in the high-performing participants, in order to correlate eventual decline in physical function, muscle mass and functional status, with changes in muscle apoptosis and in biochemical parameters in this very old population. Physical performance will be established according to the summary performance score obtained in the Short Form Physical Performance Battery (SPPB). In addition to the SPPB the investigators will also employ hand grip strength and knee extensor strength tests and the investigators will quantify muscle contractile area using 3D magnetic resonance imaging. Disability will be assessed using a self-report questionnaire. These studies will enhance our understanding of the biology and pathophysiology underlying the geriatric syndrome of sarcopenia and provide significant and novel insights that will enable us to identify new potential targets for interventions aimed at preventing and treating sarcopenia and functional impairment in older adults.

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