Skeletal muscle disuse atrophy is not attenuated by dietary protein supplementation in healthy older men

This is the author accepted manuscript. The final version is available from OUP via the DOI in this recordShort successive periods of muscle disuse, due to injury or illness, can contribute significantly to the loss of muscle mass with aging (sarcopenia). It has been suggested that increasing the protein content of the diet may be an effective dietary strategy to attenuate muscle disuse atrophy. We hypothesized that protein supplementation twice daily would preserve muscle mass during a short period of limb immobilization. Twenty-three healthy older (69 ± 1 y) men were subjected to 5 d of one-legged knee immobilization by means of a full-leg cast with (PRO group; n = 11) or without (CON group; n = 12) administration of a dietary protein supplement (20.7 g of protein, 9.3 g of carbohydrate, and 3.0 g of fat) twice daily. Two d prior to and immediately after the immobilization period, single-slice computed tomography scans of the quadriceps and single-leg 1 repetition maximum strength tests were performed to assess muscle cross-sectional area (CSA) and leg muscle strength, respectively. Additionally, muscle biopsies were collected to assess muscle fiber characteristics as well as mRNA and protein expression of selected genes. Immobilization decreased quadriceps' CSAs by 1.5 ± 0.7% (P < 0.05) and 2.0 ± 0.6% (P < 0.05), and muscle strength by 8.3 ± 3.3% (P < 0.05) and 9.3 ± 1.6% (P < 0.05) in the CON and PRO groups, respectively, without differences between groups. Skeletal muscle myostatin, myogenin, and muscle RING-finger protein-1 (MuRF1) mRNA expression increased following immobilization in both groups (P < 0.05), whereas muscle atrophy F-box/atrogen-1 (MAFBx) mRNA expression increased in the PRO group only (P < 0.05). In conclusion, dietary protein supplementation (∼20 g twice daily) does not attenuate muscle loss during short-term muscle disuse in healthy older men. This trial was registered at clinicaltrials.gov as NCT01588808

Age-period-cohort analysis for trends in body mass index in Ireland

Background: Obesity is a growing problem worldwide and can often result in a variety of negative health outcomes. In this study we aim to apply partial least squares (PLS) methodology to estimate the separate effects of age, period and cohort on the trends in obesity as measured by body mass index (BMI). Methods. Using PLS we will obtain gender specific linear effects of age, period and cohort on obesity. We also explore and model nonlinear relationships of BMI with age, period and cohort. We analysed the results from 7,796 men and 10,220 women collected through the SLAN (Surveys of Lifestyle, attitudes and Nutrition) in Ireland in the years 1998, 2002 and 2007. Results: PLS analysis revealed a positive period effect over the years. Additionally, men born later tended to have lower BMI (-0.026 kg·m-2 yr-1, 95% CI: -0.030 to -0.024) and older men had in general higher BMI (0.029 kg·m -2 yr-1, 95% CI: 0.026 to 0.033). Similarly for women, those born later had lower BMI (-0.025 kg·m-2 yr-1, 95% CI: -0.029 to -0.022) and older women in general had higher BMI (0.029 kg·m-2 yr-1, 95% CI: 0.025 to 0.033). Nonlinear analyses revealed that BMI has a substantial curvilinear relationship with age, though less so with birth cohort. Conclusion: We notice a generally positive age and period effect but a slightly negative cohort effect. Knowing this, we have a better understanding of the different risk groups which allows for effective public intervention measures to be designed and targeted for these specific population subgroups

The role of resveratrol on skeletal muscle cell differentiation and myotube hypertrophy during glucose restriction

Glucose restriction (GR) impairs muscle cell differentiation and evokes myotube atrophy. Resveratrol treatment in skeletal muscle cells improves inflammatory-induced reductions in skeletal muscle cell differentiation. We therefore hypothesised that resveratrol treatment would improve muscle cell differentiation and myotube hypertrophy in differentiating C2C12 myoblasts and mature myotubes during GR. Glucose restriction at 0.6 g/L (3.3 mM) blocked differentiation and myotube hypertrophy versus high-glucose (4.5 g/L or 25 mM) differentiation media (DM) conditions universally used for myoblast culture. Resveratrol (10 μM) treatment increased SIRT1 phosphorylation in DM conditions, yet did not improve differentiation when administered to differentiating myoblasts in GR conditions. Resveratrol did evoke increases in hypertrophy of mature myotubes under DM conditions with corresponding elevated Igf-I and Myhc7 gene expression, coding for the ‘slow’ type I MYHC protein isoform. Inhibition of SIRT1 via EX-527 administration (100 nM) also reduced myotube diameter and area in DM conditions and resulted in lower gene expression of Myhc 1, 2 and 4 coding for ‘intermediate’ and ‘faster’ IIx, IIa and IIb protein isoforms, respectively. Resveratrol treatment did not appear to modulate phosphorylation of energy-sensing protein AMPK or protein translation initiator P70S6K. Importantly, in mature myotubes, resveratrol treatment was able to ameliorate reduced myotube growth in GR conditions over an acute 24-h period, but not over 48–72 h. Overall, resveratrol evoked myotube hypertrophy in DM conditions while favouring ‘slower’ Myhc gene expression and acutely ameliorated impaired myotube growth observed during glucose restriction

Using Light to Improve Commercial Value

The plasticity of plant morphology has evolved to maximize reproductive fitness in response to prevailing environmental conditions. Leaf architecture elaborates to maximize light harvesting, while the transition to flowering can either be accelerated or delayed to improve an individual's fitness. One of the most important environmental signals is light, with plants using light for both photosynthesis and as an environmental signal. Plants perceive different wavelengths of light using distinct photoreceptors. Recent advances in LED technology now enable light quality to be manipulated at a commercial scale, and as such opportunities now exist to take advantage of plants' developmental plasticity to enhance crop yield and quality through precise manipulation of a crops' lighting regime. This review will discuss how plants perceive and respond to light, and consider how these specific signaling pathways can be manipulated to improve crop yield and quality

Elderly men and women benefit equally from prolonged resistance-type exercise training.

This study compares the effects of 6 months resistance-type exercise training (three times per week) between healthy elderly women (n = 24; 71 ± 1 years) and men (n = 29; 70 ± 1 years). Muscle mass (dual-energy x-ray absorptiometry–computed tomography), strength (one-repetition maximum), functional capacity (sit-to-stand time), muscle fiber characteristics (muscle biopsies), and metabolic profile (blood samples) were assessed. Leg lean mass (3% ± 1%) and quadriceps cross-sectional area (9% ± 1%) increased similarly in both groups. One-repetition maximum leg extension strength increased by 42% ± 3% (women) and 43% ± 3% (men). Following training, type II muscle fiber size had increased, and a type II muscle fiber specific increase in myonuclear and satellite cell content was observed with no differences between genders. Sit-to-stand time decreased similarly in both groups. Glycemic control and blood lipid profiles improved to a similar extent in both women and men. A generic resistance-type exercise training program can be applied for both women and men to effectively counteract the loss of muscle mass and strength with aging

The decline in skeletal muscle mass with aging is mainly attributed to a reduction in type II muscle fiber size.

BACKGROUND: The loss of skeletal muscle mass with aging has been decline in muscle fiber number and muscle fiber size. OBJECTIVE: To what extent differences in leg muscle cross-sectional area (CSA) between and elderly men are attributed to differences in muscle fiber size. Quadriceps muscle CSA and type I and II muscle fiber size were measured healthy young (n=25; 23+/-1y) and older (n=26; 71+/-1y) men. older subjects performed 6 months of resistance type exercise training, which measurements were repeated. Differences in quadriceps muscle CSA compared with differences in type I and II muscle fiber size. RESULTS: CSA was substantially smaller in older versus young men (68+/-2 vs 80+/- respectively; P<0.001). Type II muscle fiber size was substantially the elderly vs the young (29%; P<0.001), with a tendency of smaller type fibers (P=0.052). Differences in type II muscle fiber size fully differences in quadriceps CSA between groups. Prolonged resistance type training in the elderly increased type II muscle fiber size by 24+/-8% explaining 100+/-3% of the increase in quadriceps muscle CSA (from 68+/- 74+/-2 cm(2)). CONCLUSION: Reduced muscle mass with aging is mainly smaller type II muscle fiber size and, as such, is unlikely accompanied substantial muscle fiber loss. In line, the increase in muscle mass prolonged resistance type exercise training can be attributed entirely specific type II muscle fiber hypertrophy

Protein Supplementation Augments Muscle Fiber Hypertrophy but Does Not Modulate Satellite Cell Content During Prolonged Resistance-Type Exercise Training in Frail Elderly

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.OBJECTIVE: Protein supplementation increases gains in lean body mass following prolonged resistance-type exercise training in frail older adults. We assessed whether the greater increase in lean body mass can be attributed to muscle fiber type specific hypertrophy with concomitant changes in satellite cell (SC) content. DESIGN: A total of 34 frail elderly individuals (77 ± 1 years, n = 12 male adults) participated in this randomized, double-blind, placebo-controlled trial with 2 arms in parallel. INTERVENTION: Participants performed 24 weeks of progressive resistance-type exercise training (2 sessions per week) during which they were supplemented twice-daily with milk protein (2 × 15 g) or a placebo. METHODS: Muscle biopsies were taken at baseline, and after 12 and 24 weeks of intervention, to determine type I and type II muscle fiber specific cross-sectional area (CSA), SC content, and myocellular characteristics. RESULTS: In the placebo group, a trend for a 20% ± 11% increase in muscle fiber CSA was observed in type II fibers only (P = .051), with no increase in type I muscle fiber CSA. In the protein group, type I and II muscle fiber CSA increased by 23% ± 7% and 34% ± 10% following 6 months of training, respectively (P  .05). No changes in myonuclear content and SC contents were observed over time in either group (both P > .05). Regression analysis showed that changes in myonuclear content and domain size are predictive of muscle fiber hypertrophy. CONCLUSIONS: Protein supplementation augments muscle fiber hypertrophy following prolonged resistance-type exercise training in frail older people, without changes in myonuclear and SC content.The project is partly funded by TI Food and Nutrition, a public-private partnership on precompetitive research in food and nutrition. The researchers are responsible for the study design, data collection and analysis, decision to publish, and preparation of the manuscript. The industrial partners have contributed to the project through regular discussion

Patients with type 2 diabetes show a greater decline in muscle mass, muscle strength, and functional capacity with aging.

BACKGROUND: The loss of muscle mass with aging reduces muscle strength, functional capacity, and increases the risk of developing chronic disease. It has been suggested that the development of type 2 diabetes a more rapid decline in muscle mass, strength, and functional capacity. OBJECTIVE: To investigate the impact of type 2 diabetes on muscle mass, and functional capacity in an older population. METHODS: Muscle mass muscle biopsies), strength (1-repetition maximum), functional capacity (sit-to-stand test and handgrip strength), and reaction time performance (computer task) were compared between 60 older men with type 2 diabetes years) and 32 age-matched normoglycemic controls (70 +/- 1 years). Data analyzed using ANCOVA to adjust for several potential confounders. lean mass and appendicular skeletal muscle mass were significantly lower men with type 2 diabetes (19.1 +/- 0.3 and 25.9 +/- 0.4 kg, compared with normoglycemic controls (19.7 +/- 0.3 and 26.7 +/- 0.5 kg, respectively). Additionally, leg extension strength was significantly the group with type 2 diabetes (84 +/- 2 vs 91 +/- 2 kg, respectively). agreement, functional performance was impaired in the men with type 2 with longer sit-to-stand time (9.1 +/- 0.4 vs 7.8 +/- 0.3 seconds) and handgrip strength (39.5 +/- 5.8 vs 44.6 +/- 6.1 kg) when compared with normoglycemic controls. However, muscle fiber size and reaction time did not differ between groups. CONCLUSION: Older patients with type 2 show an accelerated decline in leg lean mass, muscle strength, and capacity when compared with normoglycemic controls. Exercise programs should be individualized to specifically target muscle mass, and functional capacity in the older population with type 2 diabetes