Search

Living longer without simultaneously extending years spent in good health ("health span") is an increasing societal burden, demanding new therapeutic strategies. Hydrogen sulfide (H S) can correct disease-related mitochondrial metabolic deficiencies, and supraphysiological H S concentrations can pro health span. However, the efficacy and mechanisms of mitochondrion-targeted sulfide delivery molecules (mtH S) administered across the adult life course are unknown. Using a aging model, we compared untargeted H S (NaGYY4137, 100 µM and 100 nM) and mtH S (AP39, 100 nM) donor effects on life span, neuromuscular health span, and mitochondrial integrity. H S donors were administered from birth or in young/middle-aged animals (day 0, 2, or 4 postadulthood). RNAi pharmacogenetic interventions and transcriptomics/network analysis explored molecular events governing mtH S donor-mediated health span. Developmentally administered mtH S (100 nM) improved life/health span vs. equivalent untargeted H S doses. mtH S preserved aging mitochondrial structure, content (citrate synthase activity) and neuromuscular strength. Knockdown of H S metabolism enzymes and FoxO/ prevented the positive health span effects of mtH S, whereas DCAF11/ - Nrf2/ oxidative stress protection pathways were dispensable. Health span, but not life span, increased with all adult-onset mtH S treatments. Adult mtH S treatment also rejuvenated aging transcriptomes by minimizing expression declines of mitochondria and cytoskeletal components, and peroxisome metabolism hub components, under mechanistic control by the / transcription factor circuit. H S health span extension likely acts at the mitochondrial level, the mechanisms of which dissociate from life span across adult vs. developmental treatment timings. The small mtH S doses required for health span extension, combined with efficacy in adult animals, suggest mtH S is a potential healthy aging therapeutic.

Impairments in myofibrillar protein synthesis (MyoPS) during bed rest accelerate skeletal muscle loss in older adults, increasing the risk of adverse secondary health outcomes. We investigated the effect of prior resistance exercise (RE) on MyoPS and muscle morphology during a disuse event in 10 healthy older men (65–80 years). Participants completed a single bout of unilateral leg RE the evening prior to 5 days of in-patient bed-rest. Quadriceps cross-sectional area (CSA) was determined prior to and following bed-rest. Serial muscle biopsies and dual stable isotope tracers were used to determine rates of integrated MyoPS (iMyoPS) over a 7 day habitual ‘free-living’ phase and the bed-rest phase, and rates of acute postabsorptive and postprandial MyoPS (aMyoPS) at the end of bed rest. Quadriceps CSA at 40%, 60% and 80% of muscle length significantly decreased in exercised (EX) and non-exercised control (CTL) legs with bed-rest. The decline in quadriceps CSA at 40% and 60% of muscle length was attenuated in EX compared with CTL. During bed-rest, iMyoPS rates decreased from habitual values in CTL, but not EX, and were significantly different between legs. Postprandial aMyoPS rates increased above postabsorptive values in EX only. The change in iMyoPS over bed-rest correlated with the change in quadriceps CSA in CTL, but not EX. A single bout of RE attenuated the decline in iMyoPS rates and quadriceps atrophy with 5 days of bed-rest in older men. Further work is required to understand the functional and clinical implications of prior RE in older patient populations. (Figure presented.). Key points: Age-related skeletal muscle deterioration, linked to numerous adverse health outcomes, is driven by impairments in muscle protein synthesis that are accelerated during periods of disuse. Resistance exercise can stimulate muscle protein synthesis over several days of recovery and therefore could counteract impairments in this process that occur in the early phase of disuse. In

BACKGROUND: The relative role of skeletal muscle mechano-transduction in comparison with systemic hormones, such as testosterone (T), in regulating hypertrophic responses to exercise is contentious. We investigated the mechanistic effects of chemical endogenous T depletion adjuvant to 6 weeks of resistance exercise training (RET) on muscle mass, function, myogenic regulatory factors, and muscle anabolic signalling in younger men. METHODS: Non-hypogonadal men (n = 16; 18-30 years) were randomized in a double-blinded fashion to receive placebo (P, saline n = 8) or the GnRH analogue, Goserelin [Zoladex (Z), 3.6 mg, n = 8], injections, before 6 weeks of supervised whole-body RET. Participants underwent dual-energy X-ray absorptiometry (DXA), ultrasound of m. vastus lateralis (VL), and VL biopsies for assessment of cumulative muscle protein synthesis (MPS), myogenic gene expression, and anabolic signalling pathway responses. RESULTS: Zoladex suppressed endogenous T to within the hypogonadal range and was well tolerated; suppression was associated with blunted fat free mass [Z: 55.4 ± 2.8 to 55.8 ± 3.1 kg, P = 0.61 vs. P: 55.9 ± 1.7 to 57.4 ± 1.7 kg, P = 0.006, effect size (ES) = 0.31], composite strength (Z: 40 ± 2.3% vs. P: 49.8 ± 3.3%, P = 0.03, ES = 1.4), and muscle thickness (Z: 2.7 ± 0.4 to 2.69 ± 0.36 cm, P > 0.99 vs. P: 2.74 ± 0.32 to 2.91 ± 0.32 cm, P < 0.0001, ES = 0.48) gains. Hypogonadism attenuated molecular transducers of muscle growth related to T metabolism (e.g. androgen receptor: Z: 1.2 fold, P > 0.99 vs. P: 1.9 fold, P < 0.0001, ES = 0.85), anabolism/myogenesis (e.g. IGF-1Ea: Z: 1.9 fold, P = 0.5 vs. P: 3.3 fold, P = 0.0005, ES = 0.72; IGF-1Ec: Z: 2 fold, P > 0.99 vs. P: 4.7 fold, P = 0.0005, ES = 0.68; myogenin: Z: 1.3 fold, P > 0.99 vs. P: 2.7 fold, P = 0.002, ES = 0.72), RNA/DNA (Z: 0.47 ± 0.03 to 0.53 ± 0.03, P = 0.31 vs. P: 0.50 ± 0.01 to 0.64 ± 0.04, P = 0.003, ES = 0.72), and RNA/ASP (Z: 5.8 ± 0.4 to 6.8 ± 0.5, P > 0.99 vs. P, Funding agency:Medical Research Council as part of the MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research MR/R502364/1 MR/P021220/1

School students in the US have the ability to commercially fly experiments on-board the International Space Station (ISS) via programmes like the Nanoracks sponsored Student Spaceflight Experiment Program (SSEP). Programs like SSEP do allow international schools to participate but similar programmes do not currently exist within the European Space Agency (ESA). ESA does, however, support commercial access to space via companies like Airbus and Kayser Italia. A key principle of SSEP is that students propose to fly experiments that will work within existing spaceflight hardware. This is similar to the idea of using standardized CubeSat platforms in education and ESA’s long-standing use of standardized Experiment Containers (ECs). These ECs form the starting point for Airbus and Kayser Italia’s commercial access programmes. In 2018 we were selected by the UK Space Agency to develop and fly a UK national payload to the ISS. This payload will conduct scientific experiments proposed by ourselves, international partners, and schools in the UK. All experiments will take place inside ECs that are refurbished, and flight qualified in the UK. If we can successfully conduct student experiments during this mission, we will have demonstrated the possibility of conducting UK student experiments in space via a UK company. This should pave the way for UK-based commercial access to the ISS that could be used by schools much like the US based SSEP.

Background: The andropause is associated with declines in serum testosterone (T), loss of muscle mass (sarcopenia), and frailty. Two major interventions purported to offset sarcopenia are anabolic steroid therapies and resistance exercise training (RET). Nonetheless, the efficacy and physiological and molecular impacts of T therapy adjuvant to short-term RET remain poorly defined. Methods: Eighteen non-hypogonadal healthy older men, 65-75 years, were assigned in a random double-blinded fashion to receive, biweekly, either placebo (P, saline, n = 9) or T (Sustanon 250 mg, n = 9) injections over 6 week whole-body RET (three sets of 8-10 repetitions at 80% one-repetition maximum). Subjects underwent dual-energy X-ray absorptiometry, ultrasound of vastus lateralis (VL) muscle architecture, and knee extensor isometric muscle force tests; VL muscle biopsies were taken to quantify myogenic/anabolic gene expression, anabolic signalling, muscle protein synthesis (D2O), and breakdown (extrapolated). Results: Testosterone adjuvant to RET augmented total fat-free mass (P=0.007), legs fat-free mass (P=0.02), and appendicular fat-free mass (P=0.001) gains while decreasing total fat mass (P=0.02). Augmentations in VL muscle thickness, fascicle length, and quadriceps cross-section area with RET occured to a greater extent in T (P < 0.05). Sum strength (P=0.0009) and maximal voluntary contract (e.g. knee extension at 70 degrees) (P=0.002) increased significantly more in the T group. Mechanistically, both muscle protein synthesis rates (T: 2.13 +/- 0.21%center dot day(-1) vs. P: 1.34 +/- 0.13%center dot day(-1), P=0.0009) and absolute breakdown rates (T: 140.2 +/- 15.8 g center dot day(-1) vs. P: 90.2 +/- 11.7 g center dot day(-1), P=0.02) were elevated with T therapy, which led to higher net turnover and protein accretion in the T group (T: 8.3 +/- 1.4 g center dot day (-1) vs. P: 1.9 +/- 1.2 g center dot day (-1), P=0.004). Increases in ribosomal biogenesis (RNA:DNA ratio); mRNA, Funding Agencies:Medical Research Council as part of the MRC-ARUK Centre for Musculoskeletal Ageing Research MR/R502364/1 MR/P021220/1National Institute for Health Research, Nottingham Biomedical Research Centre