Irene Fleur Kramer

Impact of the Macronutrient Composition of a Nutritional Supplement on Muscle Protein Synthesis Rates in Older Men: A Randomized, Double Blind, Controlled Trial

CONTEXT An impaired muscle protein synthetic response to feeding likely contributes to muscle loss with aging. There are few data available on the effect of the macronutrient composition of clinical supplements on the postprandial muscle protein synthetic response in older subjects. OBJECTIVE The objective of the study was to determine the impact of the macronutrient composition of a nutritional supplement on the postprandial muscle protein synthetic response in older men. METHODS A total of 45 nonsarcopenic older men (aged 69 ± 1 y; body mass index 25.7 ± 0.3 kg/m(2)) were randomly assigned to ingest 21 g of leucine-enriched whey protein with carbohydrate (9 g) and fat (3 g) (Pro-En), an isonitrogenous amount of 21 g of leucine-enriched whey protein without carbohydrate and fat (Pro), or an isocaloric mixture (628 kJ) containing carbohydrate and fat only (En). Stable isotope tracer methodology was applied to assess the basal as well as the postprandial muscle protein synthesis rates in the three groups. RESULTS Ingestion of protein in the Pro-En and Pro groups significantly increased muscle protein synthesis rates when compared with the basal rates (from 0.032 ± 0.003%/h to 0.05%/h 3 ± 0.004%/h and 0.040%/h ± 0.003%/h to 0.049%/h ± 0.003%/h, respectively; P < .05), whereas ingestion of carbohydrate and fat did not increase muscle protein synthesis rates in the En group (from 0.039%/h ± 0.004%/h to 0.040%/h ± 0.003%/h; P = .60). Despite the greater postprandial rise in circulating insulin concentration in the Pro-En group, no significant differences were observed in postprandial muscle protein synthesis rates between the Pro-En and Pro groups (P = .32). Postprandial muscle protein synthesis rates were higher in the Pro-En vs En group (P = .01). CONCLUSION The ingestion of a nutritional supplement containing 21 g of leucine-enriched whey protein significantly raises muscle protein synthesis rates in nonsarcopenic older men, but coingestion of carbohydrate and fat does not modulate the postprandial muscle protein synthetic response to protein ingestion in older men.

Extensive Type II Muscle Fiber Atrophy in Elderly Female Hip Fracture Patients

Background Sarcopenia, or the loss of muscle mass and strength, is known to increase the risk for falls and (hip) fractures in older people. The objective of this study was to assess the skeletal muscle fiber characteristics in elderly female hip fracture patients. Method Percutaneous needle biopsies were collected from the vastus lateralis muscle in 15 healthy young women (20 ± 0.4 years), 15 healthy elderly women (79 ± 1.7 years), and 15 elderly women with a fall-related hip fracture (82 ± 1.5 years). Immunohistochemical analyses were performed to assess Type I and Type II muscle fiber size, and myonuclear and satellite cell content. Results Type II muscle fiber size was significantly different between all groups (p < .05), with smaller Type II muscle fibers in the hip fracture patients (2,609 ± 185 µm2) compared with healthy elderly group (3,723 ± 322 µm2) and the largest Type II muscle fibers in the healthy young group (4,755 ± 335 µm2). Furthermore, Type I muscle fiber size was significantly lower in the hip fracture patients (4,684 ± 211 µm2) compared with the healthy elderly group (5,842 ± 316 µm2, p = .02). The number of myonuclei per Type II muscle fiber was significantly lower in the healthy elderly and hip fracture group compared with the healthy young group (p = .011 and p = .002, respectively). Muscle fiber satellite cell content did not differ between groups. Conclusion Elderly female hip fracture patients show extensive Type II muscle fiber atrophy when compared with healthy young or age-matched healthy elderly controls. Type II muscle fiber atrophy is an important hallmark of sarcopenia and may predispose to falls and (hip) fractures in the older population.

Protein Ingestion before Sleep Increases Overnight Muscle Protein Synthesis Rates in Healthy Older Men: A Randomized Controlled Trial

Background: The loss of skeletal muscle mass with aging has been attributed to the blunted anabolic response to protein intake. Presleep protein ingestion has been suggested as an effective strategy to compensate for such anabolic resistance.Objective: We assessed the efficacy of presleep protein ingestion on dietary protein digestion and absorption kinetics and overnight muscle protein synthesis rates in older men.Methods: In a randomized, double-blind, parallel design, 48 older men (mean ± SEM age: 72 ± 1 y) ingested 40 g casein (PRO40), 20 g casein (PRO20), 20 g casein plus 1.5 g leucine (PRO20+LEU), or a placebo before sleep. Ingestion of intrinsically l-[1-13C]-phenylalanine- and l-[1-13C]-leucine-labeled protein was combined with intravenous l-[ring-2H5]-phenylalanine and l-[1-13C]-leucine infusions during sleep. Muscle and blood samples were collected throughout overnight sleep.Results: Exogenous phenylalanine appearance rates increased after protein ingestion, but to a greater extent in PRO40 than in PRO20 and PRO20+LEU (P < 0.05). Overnight myofibrillar protein synthesis rates (based on l-[ring-2H5]-phenylalanine) were 0.033% ± 0.002%/h, 0.037% ± 0.003%/h, 0.039% ± 0.002%/h, and 0.044% ± 0.003%/h in placebo, PRO20, PRO20+LEU, and PRO40, respectively, and were higher in PRO40 than in placebo (P = 0.02). Observations were similar based on l-[1-13C]-leucine tracer (placebo: 0.047% ± 0.004%/h and PRO40: 0.058% ± 0.003%/h, P = 0.08). More protein-derived amino acids (l-[1-13C]-phenylalanine) were incorporated into myofibrillar protein in PRO40 than in PRO20 (0.033 ± 0.002 and 0.019 ± 0.002 MPE, respectively, P < 0.001) and tended to be higher than in PRO20+LEU (0.025 ± 0.002 MPE, P = 0.06).Conclusions: Protein ingested before sleep is properly digested and absorbed throughout the night, providing precursors for myofibrillar protein synthesis during sleep in healthy older men. Ingestion of 40 g protein before sleep increases myofibrillar protein synthesis rates during overnight sleep. These findings provide the scientific basis for a novel nutritional strategy to support muscle mass preservation in aging and disease. This trial was registered at www.trialregister.nl as NTR3885.

Case Report: Snowboarders’ ankle

In this case study we report a fracture of the lateral process of the talus (LPF) in a snowboarder. The fracture is frequently overlooked initially, due to subtle clinical and radiological findings and a low incidence rate. However, LPF are associated with significant morbidity when missed. To address this, we report one case of a patient with a LPF and provide a review of the available literature.

A single session of neuromuscular electrical stimulation does not augment postprandial muscle protein accretion

The loss of muscle mass and strength that occurs with aging, termed sarcopenia, has been (at least partly) attributed to an impaired muscle protein synthetic response to food intake. Previously, we showed that neuromuscular electrical stimulation (NMES) can stimulate fasting muscle protein synthesis rates and prevent muscle atrophy during disuse. We hypothesized that NMES prior to protein ingestion would increase postprandial muscle protein accretion. Eighteen healthy elderly (69 ± 1 yr) males participated in this study. After a 70-min unilateral NMES protocol was performed, subjects ingested 20 g of intrinsically l-[1-(13)C]phenylalanine-labeled casein. Plasma samples and muscle biopsies were collected to assess postprandial mixed muscle and myofibrillar protein accretion as well as associated myocellular signaling during a 4-h postprandial period in both the control (CON) and stimulated (NMES) leg. Protein ingestion resulted in rapid increases in both plasma phenylalanine concentrations and l-[1-(13)C]phenylalanine enrichments, which remained elevated during the entire 4-h postprandial period (P < 0.05). Mixed-muscle protein-bound l-[1-(13)C]phenylalanine enrichments increased significantly over time following protein ingestion, with no differences between the CON (0.0164 ± 0.0019 MPE) and NMES (0.0164 ± 0.0019 MPE) leg (P > 0.05). In agreement, no differences were observed in the postprandial rise in myofibrillar protein bound l-[1-(13)C]phenylalanine enrichments between the CON and NMES legs (0.0115 ± 0.0014 vs. 0.0133 ± 0.0013 MPE, respectively, P > 0.05). Significant increases in mTOR and P70S6K phosphorylation status were observed in the NMES-stimulated leg only (P < 0.05). We conclude that a single session of NMES prior to food intake does not augment postprandial muscle protein accretion in healthy older men.

Contributions to the understanding of the anabolic properties of different dietary proteins

Skeletal muscle mass is maintained by the balance between muscle protein synthesis and breakdown rates such that overall muscle net protein balance (NPB) remains essentially unchanged over the course of the day. A prolonged negative NPB will result in a loss of skeletal muscle proteins. Ageing or prolonged periods of disuse (due to illness or a sedentary lifestyle) exacerbate the loss of skeletal muscle mass. It has been speculated that the capacity of skeletal muscle tissue to recover from prolonged periods of muscle unloading is reduced with advancing age. Therefore, a greater understanding of the proposed mechanisms underpinning the unloading induced atrophy, and the eventual incomplete recovery that generally follows, will certainly contribute to the development of more effective nutritional or lifestyle strategies to attenuate muscle mass loss and support healthy ageing. The lack of skeletal muscle recovery following unloading in the elderly may be explained by an observed phenomenon commonly coined ‘anabolic resistance’ of muscle protein synthesis rates. Specifically, frequent periods of disuse, simplified as ‘inactive muscle’, will desensitize skeletal muscle to hyperaminoacidaemia and ultimately lead to a reduced muscle protein synthetic response when compared with the response of active skeletal muscle to the same stimuli. There is no general consensus on whether anabolic resistance of muscle protein synthesis rates is truly an inherent intrinsic characteristic of ageing muscle or a self-induced product of a sedentary lifestyle. Hitherto, the role of muscle protein breakdown in unloading-induced disturbances of protein metabolism has not been studied profoundly. However, it is assumed that any change in muscle protein breakdown rates during unloading is an adaptive response to changes in muscle protein synthesis rates. Of course, more in vivo human research is necessary to understand the quantitative role of muscle protein breakdown during periods of unloading. Thus, due to the sparse knowledge regarding muscle protein breakdown rates in unloading-mediated muscle atrophy, contemporary interventions generally focus on nutritional strategies known to stimulate muscle protein synthesis rates. Recent work from our lab has revealed that the type of protein consumed can have a fundamental impact on postprandial muscle protein synthesis rates (Pennings et al. 2011). Specifically, we found that ingestion of a meal-like amount of whey protein (20 g) is more effective at stimulating postprandial muscle protein synthesis rates than ingestion of an isonitrogenous amount of casein hydrolysate or micellar casein (Pennings et al. 2011). We speculated that the superiority of whey protein for the stimulation of postprandial muscle protein synthesis rates is probably attributable to both its speed of digestion/absorption and its higher leucine content. Thus, meal-induced leucinaemia appears to be a primary driver of the anabolic response. Interestingly, Glover et al. (2008) investigated whether increasing the blood amino acid availability can overcome the anabolic resistance of muscle protein synthesis rates to amino acid provision induced by immobilization. It was observed across a wide range of amino acid concentrations that the immobilized limb revealed a blunted muscle protein synthetic response when compared to the non-immobilized limb. Notably, even a high-dose amino acid infusion could not overcome the anabolic resistance of muscle protein synthesis rates imposed by unloading. These data also suggest that eating large amounts of protein may be a fruitless nutritional strategy to offset muscle mass loss during unloading. Despite these results in young adults (Glover et al. 2008), it provides perspective for more research into the phenomenon of immobilization-induced anabolic resistance among the elderly. As a matter of fact, the effects of different anabolic stimuli, such as intact proteins or free dietary amino acid supplementation, after prolonged periods of unloading during ageing remain largely unknown. Recently, an article published in The Journal of Physiology by Magne et al. (2012) provided new insights into nutritional strategies that may help recover muscle mass after a prolonged period of unloading. The authors used a rodent (male Wister rats aged 22–24 months) unilateral hind-limb cast immobilization model. After 10, 20, 30 and 40 days of recovery from an 8 day immobilisation period, muscle protein synthesis rates, markers of proteolysis and intramuscular anabolic signalling protein phosphorylation were measured. The authors observed that ∼20% of the gastrocnemius muscle mass was lost following immobilisation. Muscle protein synthesis rates were depressed in the postprandial state after prolonged mechanical unloading in the elderly rats and did not normalize during reloading. In addition, the authors report that leucine supplementation was not as effective as whey or high-protein diets in maximizing skeletal muscle mass after 40 days of recovery. This is an interesting finding since leucine is presumed to be highly anabolic toward the stimulation of muscle protein synthesis rates and often used as a pharmaconutrient to improve muscle recovery after prolonged periods of unloading. However, it has recently been demonstrated that simply supplementating the diet with free dietary leucine (7.5 g d−1) is not an effective strategy to increase muscle mass or strength, in healthy elderly men consuming the recommended dietary allowance for protein (Verhoeven et al. 2009). With respect to the animal in vivo measurements of muscle protein synthesis by Magne et al. (2012), the positive leucine-induced effect on the stimulation of muscle protein synthesis rates failed to translate into muscle growth. Moreover, other factors involved in stimulating muscle protein synthesis rates were also altered in favour of muscle protein synthesis, despite the lack of long-term benefits. For example, free leucine supplementation increased the amount of phosphorylation of S6 and 4EBP1 proteins and at the same time generated a decrease in chymotrypsin- and trypsin-like activities of the 26S proteasome associated with a P-FOXO3a/FOXO3a ratio in favour of antiproteolytic processes. However, when the duration of muscle protein synthesis increment is inadequate to generate a significant muscle protein accretion, the effect on muscle mass is negligible, which is in accordance with the authors’ conclusion. Unlike free leucine supplementation, whey and high-protein diets resulted in a ∼60% regain of the amount of muscle lost with immobilization. This could be explained by the larger increases in muscle protein synthesis rates after the whey and high-protein diets. Despite the positive effects of free leucine supplementation on muscle protein synthesis rates, it appears that intact proteins are essential to gain muscle mass. Notwithstanding, proteins enriched with leucine might be applicable to accelerate muscle regain or prevent muscle loss. Magne et al. (2012) are to be praised for studying the role of leucine and even more for underpinning the importance of intact proteins such as whey or consumption of higher protein diets in the recovery of muscle mass during or after a period of muscle disuse. The next step is to translate the authors’ work to a human model. Therefore, we need immobilization trials with elderly people to investigate whether the animal findings are similar to that of in vivo human work. Notable is that Drummond et al. (2012) examined the effect of 7 days of bed rest and amino acid supplementation on muscle protein synthesis rates in humans. As in previous trials, Drummond et al. (2012) showed that 7 days of bed rest blunted the essential amino acid-induced increase in muscle protein synthesis rates. In addition, the workers studied different types of amino acid transporters, to decipher whether a reduced amino acid-transporter response was partly responsible for the desensitization to amino acidaemia of muscle during disuse. To stimulate mTORC1 signalling exogenous amino acids first have to enter the muscle cell via active transport. Interestingly, both amino acid transporters, LAT1 and SNAT2, are associated with mTORC1 activation and muscle protein synthesis rates. Indeed, in addition to the impaired response in muscle protein synthesis following an amino acid stimulation the authors found a decrease in amino acid-transporter content, thus providing some clue as to how anabolic resistance of muscle proteins synthesis rates to amino acids manifests during unloading. Taken together, the work from Magne et al. (2012) and other referenced authors contributes to the development of nutritional strategies to recover muscle mass after periods of muscle disuse (e.g. injury or illness) in the elderly. Importantly, the authors’ findings point to a thesis that high-quality proteins, such as whey, that are easily digested (and already high in leucine) are superior to create an anabolic environment, especially after periods of disuse. This message is one that those supplementing their diet with free dietary leucine with a wish of building bigger muscles might not want to hear! In conclusion, the addition of free leucine next to our habitual diet is not the answer to prevent muscle loss or accelerate muscle regain. More work is needed to explore the anabolic properties of our nutrition in general, with the functional properties of different proteins in particular.

OR043: One Week of Hospital Admission Following Elective Hip Surgery Induces Substantial Muscle Atrophy in Older Patients

atrophy in older patients I.W.K. Kouw,1 B.B.L. Groen,1 J.S.J. Smeets,1 J. van Kranenburg,1 M. Poeze,2 J.A. Geurts,3 R.H.M. ten Broeke,3 L.B. Verdijk1 and L.J.C. van Loon,1 1Department of Human Biology, School of NUTRIM, Maastricht University Medical Centre+, Maastricht, The Netherlands, 2Department of Surgery, School of NUTRIM, Maastricht University Medical Centre+, Maastricht, The Netherlands and 3Department of Orthopedic Surgery, CAPHRI Research Institute, Maastricht University Medical Centre+, Maastricht, The Netherlands.

OR001: Ingestion of 40 G Protein Prior to Sleep Stimulates Overnight Myofibrillar Protein Accretion in Healthy Older Men

Rationale: Pancreatic cancer related cachexia and skeletal muscle wasting is related to poor outcome. Body muscle mass can be assessed by CT-imaging. Intermuscular adipose tissue and/or intermyofibrillar fat accumulation (reflected by the “radiation attenuation”) are increased in cancer patients independent of sarcopenia, and might be indicators of muscle loss and muscle quality. This study aimed to assess the impact of fat accumulation in muscle on postoperative outcome in surgical patients with pancreatic cancer. Methods: A prospective cohort of 192 pancreatic cancer patients operated between 2008 2013 was analysed by CTimage analysis at the L3 level to measure cross-sectional surface area of (1) skeletal muscle, (2) intermuscular adipose tissue, (3) visceral adipose tissue; the mean muscle radiation attenuation, reflecting intermyofibrillar fat, was defined by the average muscle radiation attenuation in Hounsfield units. Results: Low muscle radiation attenuation, indicating high intermyofibrillar fat, was associated with low survival compared with middle and high muscle attenuation (median survival 46.5, 77.1, and 67.1 weeks, respectively; p < 0.001) and was associated with an increased risk of major complications (OR: 2.3, 95%CI: 1.4 5.6). Muscle attenuation index was negatively correlated with intermuscular adipose tissue (rp = 0.68, p < 0.001). Increased visceral adipose tissue was associated with development of pancreatic fistula (OR: 2.5, 95%CI: 1.1 6.1) and post-operative infections (OR: 2.7, 95%CI: 1.4 5.2). Conclusion: A reduced muscle radiation attenuation is associated with reduced survival and increased severe postoperative complications. The strong correlation between intermyofibrillar fat and intermuscular adipose tissue suggests a common mechanism of origin, warranting further investigation. Preoperative CT-image analysis of body tissue compartments likely is clinically useful to identify high-risk patients.