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Pabla P, Jones E, Piasecki M, Phillips B. Skeletal muscle dysfunction with advancing age. Clin Sci (Lond) 2024; 138:863-882. [PMID: 38994723 PMCID: PMC11250095 DOI: 10.1042/cs20231197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 06/15/2024] [Accepted: 06/20/2024] [Indexed: 07/13/2024]
Abstract
As a result of advances in medical treatments and associated policy over the last century, life expectancy has risen substantially and continues to increase globally. However, the disconnect between lifespan and 'health span' (the length of time spent in a healthy, disease-free state) has also increased, with skeletal muscle being a substantial contributor to this. Biological ageing is accompanied by declines in both skeletal muscle mass and function, termed sarcopenia. The mechanisms underpinning sarcopenia are multifactorial and are known to include marked alterations in muscle protein turnover and adaptations to the neural input to muscle. However, to date, the relative contribution of each factor remains largely unexplored. Specifically, muscle protein synthetic responses to key anabolic stimuli are blunted with advancing age, whilst alterations to neural components, spanning from the motor cortex and motoneuron excitability to the neuromuscular junction, may explain the greater magnitude of function losses when compared with mass. The consequences of these losses can be devastating for individuals, their support networks, and healthcare services; with clear detrimental impacts on both clinical (e.g., mortality, frailty, and post-treatment complications) and societal (e.g., independence maintenance) outcomes. Whether declines in muscle quantity and quality are an inevitable component of ageing remains to be completely understood. Nevertheless, strategies to mitigate these declines are of vital importance to improve the health span of older adults. This review aims to provide an overview of the declines in skeletal muscle mass and function with advancing age, describes the wide-ranging implications of these declines, and finally suggests strategies to mitigate them, including the merits of emerging pharmaceutical agents.
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Affiliation(s)
- Pardeep Pabla
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
| | - Eleanor J. Jones
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
| | - Mathew Piasecki
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research (CMAR), U.K
- NIHR Nottingham Biomedical Research Centre (BRC), U.K
| | - Bethan E. Phillips
- Centre of Metabolism, Ageing and Physiology (COMAP), School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, DE22 3DT, U.K
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research (CMAR), U.K
- NIHR Nottingham Biomedical Research Centre (BRC), U.K
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Pagano AP, Montenegro J, Oliveira CLP, Desai N, Gonzalez MC, Cawthon PM, Evans WJ, Prado CM. Estimating Muscle Mass Using D3-Creatine Dilution: A Narrative Review of Clinical Implications and Comparison With Other Methods. J Gerontol A Biol Sci Med Sci 2024; 79:glad280. [PMID: 38135279 PMCID: PMC10959434 DOI: 10.1093/gerona/glad280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Indexed: 12/24/2023] Open
Abstract
BACKGROUND The D3-creatine (D3-Cr) dilution method is of emerging interest for estimating total-body skeletal muscle mass. This review explores the association of muscle mass estimated via D3-Cr with various clinical outcomes and provides a summary of the literature comparing D3-Cr with other body composition techniques. METHODS A literature search was conducted on PubMed/MEDLINE and Web of Science for studies using D3-Cr to measure muscle in adult populations (ie, ≥18 years old) from inception until September 2023. RESULTS Out of the 23 included studies, 15 investigated the correlation between D3-Cr and clinical outcomes. More consistent associations were reported for mortality (100%, n = 2), mobility disability (100%; n = 5), falls and fractures (100%; n = 3), physical performance (63.3%; n = 11), muscle strength (44.4%; n = 9), and muscle composition (33.3%; n = 3). However, conflicting findings were also reported for such correlations. Among the 23 studies, 14 compared D3-Cr-estimated muscle with other body composition techniques, including magnetic resonance imaging (MRI) as a reference method. Strong and positive correlations were found between D3-Cr and MRI. Nonetheless, variations in muscle measurements were noted, with differences in D3-Cr values ranging from 0.62 kg lower to 13.47 kg higher compared to MRI. CONCLUSIONS D3-Cr-estimated muscle mass may be a valuable predictor of clinical outcomes showing consistent associations with falls and fractures, mobility disability, and mortality. However, less consistent associations were found with muscle strength and composition, and physical performance. Although a strong correlation exists between D3-Cr-estimated muscle mass and MRI measurements, under- or overestimation may occur.
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Affiliation(s)
- Ana Paula Pagano
- Human Nutrition Research Unit, Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- Women and Children’s Health Research Institute, Edmonton, Alberta, Canada
| | - Julia Montenegro
- Human Nutrition Research Unit, Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Camila L P Oliveira
- Human Nutrition Research Unit, Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Nidhi Desai
- Human Nutrition Research Unit, Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Nursing, University of Calgary, Calgary, Alberta, Canada
| | - M Cristina Gonzalez
- Postgraduate Program in Nutrition and Food, Federal University of Pelotas, Pelotas, State of Rio Grande do Sul, Brazil
| | - Peggy M Cawthon
- California Pacific Medical Center Research Institute, San Francisco, California, USA
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA
| | - William J Evans
- Department of Nutritional Sciences and Toxicology, University of California Berkeley, Berkeley, California, USA
- Division of Geriatrics, Duke University School of Medicine, Durham, North Carolina, USA
| | - Carla M Prado
- Human Nutrition Research Unit, Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
- Women and Children’s Health Research Institute, Edmonton, Alberta, Canada
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O'Leary MF, Jackman SR, Bowtell JL. Shatavari supplementation in postmenopausal women alters the skeletal muscle proteome and pathways involved in training adaptation. Eur J Nutr 2024; 63:869-879. [PMID: 38214710 PMCID: PMC10948523 DOI: 10.1007/s00394-023-03310-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 12/10/2023] [Indexed: 01/13/2024]
Abstract
PURPOSE Shatavari is an understudied, widely available herbal supplement. It contains steroidal saponins and phytoestrogens. We previously showed that six weeks of shatavari supplementation improved handgrip strength and increased markers of myosin contractile function. Mechanistic insights into shatavari's actions are limited. Therefore, we performed proteomics on vastus lateralis (VL) samples that remained from our original study. METHODS In a randomised double-blind trial, women (68.5 ± 6 years) ingested either placebo or shatavari (equivalent to 26,500 mg/d fresh weight) for six weeks. Tandem mass tag global proteomic analysis of VL samples was conducted (N = 7 shatavari, N = 5 placebo). Data were normalized to total peptides and scaled using a reference sample. Data were filtered using a 5% FDR. For each protein, the pre to post supplementation difference was expressed as log2 fold change. Welch's t tests with Benjamini-Hochberg corrections were performed for each protein. Pathway enrichment (PADOG, CAMERA) was interrogated in Reactome (v85). RESULTS No individual protein was significantly different between supplementation conditions. Both PADOG and CAMERA indicated that pathways related to (1) Integrin/MAPK signalling, (2) metabolism/insulin secretion; (3) cell proliferation/senescence/DNA repair/cell death; (4) haemostasis/platelets/fibrin; (5) signal transduction; (6) neutrophil degranulation and (7) chemical synapse function were significantly upregulated. CAMERA indicated pathways related to translation/amino acid metabolism, viral infection, and muscle contraction were downregulated. CONCLUSION Our analyses indicate that shatavari may support muscle adaptation responses to exercise. These data provide useful signposts for future investigation of shatavari's utility in conserving and enhancing musculoskeletal function in older age. TRIAL REGISTRATION NCT05025917 30/08/21, retrospectively registered.
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Affiliation(s)
- Mary F O'Leary
- Department of Public Health and Sport Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK.
| | - Sarah R Jackman
- Department of Public Health and Sport Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
| | - Joanna L Bowtell
- Department of Public Health and Sport Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, UK
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Cegielski J, Brook MS, Phillips BE, Boereboom C, Gates A, Gladman JFR, Smith K, Wilkinson DJ, Atherton PJ. The Combined Oral Stable Isotope Assessment of Muscle (COSIAM) reveals D-3 creatine derived muscle mass as a standout cross-sectional biomarker of muscle physiology vitality in older age. GeroScience 2022; 44:2129-2138. [PMID: 35303223 DOI: 10.1007/s11357-022-00541-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/03/2022] [Indexed: 12/21/2022] Open
Abstract
Validated diagnostics of skeletal muscle vitality could benefit clinical and basic science in terms of mechanistic insights and in determining the efficacy of interventions, e.g. exercise/pharmaceuticals/nutrients. We recently developed a Combined Oral Assessment of Muscle (COSIAM) that can be used to simultaneously quantify whole-body muscle mass (WBMM), muscle protein synthesis (MPS) and muscle protein breakdown (MPB). Here, we aimed to establish, in a cross-sectional fashion, links between COSIAM parameters and established aspects of muscle function. We recruited 37 healthy older adults (male (M):female (F) (21/16); 72 ± 5 y)) into a 3-day trial. Subjects consumed D3-creatine (D3-Cr dilution to assess WBMM), D2O (MPS by incorporation of alanine) and D3-3-methylhistidine (D3-MH dilution to assess MPB). A biopsy at day 3 was used to determine MPS, and blood/urine samples were collected to determine D3-Cr/D3-MH dilution for WBMM and MPB. Physiological measures of muscle mass (e.g. DXA/ultrasound) and function (e.g. handgrip strength, maximum voluntary contraction (MVC), one-repetition maximum (1-RM)) were ascertained. A stepwise linear regression approach was used to address links between facets of COSIAM (MPS, MPB, WBMM) and muscle physiology. Despite expected differences in muscle mass, there were no significant differences in MPS or MPB between sexes. WBMM as measured using D3-Cr positively correlated with DXA-derived lean body mass (LBM) and appendicular LBM (ABLM). Stepwise linear regression was used to assess which combination of MPS, MPB, D3-Cr and absolute synthesis rate (ASR) best predicted physiological measures of muscle health in these older adults. D3-Cr WBMM alone was the best predictor of handgrip, 1RM and MVC, and outperformed more traditional measures of muscle mass by DXA. The COSIAM approach substantiates D3-Cr as a robust biomarker of multiple muscle physiology health biomarkers. Future work using COSIAM should focus upon how and which parameters it can inform upon in relation to disease progression and the efficacy of interventions.
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Affiliation(s)
- Jessica Cegielski
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK
| | - Matthew S Brook
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK
| | - Bethan E Phillips
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK
| | - Catherine Boereboom
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK
| | - Amanda Gates
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK
| | | | - Kenneth Smith
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK
| | - Daniel J Wilkinson
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK
| | - Philip J Atherton
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Clinical, Metabolic and Molecular Physiology, School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK. .,MRC/Versus Arthritis Centre for Musculoskeletal Ageing Research, Division of Medical Sciences and Graduate Entry Medicine, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Road, Derby, DE22 3DT, UK.
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Lahaye C, Derumeaux-Burel H, Guillet C, Pereira B, Boirie Y. Determinants of Resting Energy Expenditure in Very Old Nursing Home Residents. J Nutr Health Aging 2022; 26:872-878. [PMID: 36156679 DOI: 10.1007/s12603-022-1837-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
OBJECTIVES This study aimed to measure resting energy expenditure (REE) in institutionalized old persons and to determine factors possibly related to change in REE as a basis for estimating energy requirements. DESIGN AND SETTINGS A monocentric cross-sectional study was conducted. Statistical approaches were conducted to determine independent factors associated with REE. Various published predictive equations of REE were compared to our population. PARTICIPANTS 72 residents of a nursing home, mostly women (80.5%) aged 87.4±6.6 years were included. MEASUREMENTS REE (indirect calorimetry), body composition (bio-impedance analysis), biological and anthropometric data were collected. RESULTS Mean REE was 1006±181 kcal/d and was higher in men than in (1227±195 vs. 953±131 kcal/d, p<0.05). According to criteria adapted from the Global Leadership Initiative on Malnutrition consensus, 65.3 % of the institutionalized population were malnourished. In multivariate analysis adjusted on gender and age, REE was positively associated with calorie intake, fat-free mass (FFM), functional abilities (French Autonomie Gérontologie Groupe Iso Ressources scale), and elevated CRP level (> 25 mg/l). Significant differences (p<0.05) appeared between measured REE and predicted REE by using various published equations. CONCLUSION REE of very old nursing home residents is influenced by FFM, calorie intake, functional abilities, and CRP levels and is poorly predicted by classical equations based on age, gender, height, and weight. This suggests a metabolic adaptation to caloric restriction and inflammation and prompts to consider the level of physical activity and muscle loss when assessing caloric requirements in this population.
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Affiliation(s)
- C Lahaye
- Dr. Clément LAHAYE, CHU Clermont-Ferrand, Department of Clinical Nutrition, Hôpital Gabriel Montpied, 58 Rue Montalembert, F-63003 Clermont-Ferrand, France, Mail: , Telephone: 04 73 75 45 94, Fax 04 73 75 45 99
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Traversa C, Hannaian SJ. A 'virtual' revolution: non-invasive methods to probe skeletal muscle metabolism in Duchenne muscular dystrophy. J Physiol 2021; 600:429-430. [PMID: 34877686 DOI: 10.1113/jp282558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 12/03/2021] [Indexed: 01/05/2023] Open
Affiliation(s)
- Claire Traversa
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC, Canada
| | - Sarkis J Hannaian
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC, Canada
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Mathewson SL, Gordon AL, Smith K, Atherton PJ, Greig CA, Phillips BE. Determining the Influence of Habitual Dietary Protein Intake on Physiological Muscle Parameters in Youth and Older Age. Nutrients 2021; 13:nu13103560. [PMID: 34684561 PMCID: PMC8539198 DOI: 10.3390/nu13103560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 11/16/2022] Open
Abstract
Protein ingestion is a potent stimulator of skeletal muscle protein synthesis (MPS). However, older adults demonstrate resistance to anabolic stimuli. Some evidence has demonstrated that a larger acute protein dose is required in older compared to younger adults to elicit the same synthetic response, suggesting that older adults should be consuming higher habitual dietary protein to optimise muscle mass. However, limited research has explored dietary habits in different age groups or the relationship between habitual dietary intake and mechanistic physiological parameters associated with muscle mass and function. This work investigated the effect of habitual dietary intake in young (n = 10, 25.9 (3.2y)) and older (n = 16, 70.2 (3.2y)) community-dwelling adults (16:10 male: female) on physiological muscle parameters. Dietary intake was assessed using four-day diet diaries. Post-absorptive MPS and MPS responses to feeding (4.25x basal metabolic rate; 16% protein) were determined in muscle biopsies of the m. vastus lateralis via stable isotope tracer ([1, 2-13C2]-leucine) infusions with mass-spectrometric analyses. Body composition was measured by dual-energy x-ray absorptiometry. Whole body strength was assessed via 1-repetition maximum assessments. No significant differences in habitual dietary intake (protein, fat, carbohydrate and leucine as g.kgWBLM-1.day-1) were observed between age groups. Whole-body lean mass (61.8 ± 9.9 vs. 49.8 ± 11.9 kg, p = 0.01) and knee-extensor strength (87.7 ± 28.3 vs. 56.8 ± 16.4 kg, p = 0.002) were significantly higher in young adults. Habitual protein intake (g.kg-1.day-1) was not associated with whole-body lean mass, upper-leg lean mass, whole-body strength, knee-extensor strength, basal MPS or fed-state MPS across both age groups. These findings suggest that differences in muscle mass and strength parameters between youth and older age are not explained by differences in habitual dietary protein intake. Further research with a larger sample size is needed to fully explore these relationships and inform on interventions to mitigate sarcopenia development.
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Affiliation(s)
- Sophie L. Mathewson
- School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Edgbaston B15 2TT, UK; (S.L.M.); (C.A.G.)
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing, University of Birmingham, Edgbaston B15 2TT, UK
| | - Adam L. Gordon
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing and NIHR Nottingham Biomedical Research Centre, University of Nottingham, Derby DE22 3DT, UK; (A.L.G.); (K.S.); (P.J.A.)
- Department of Medicine for the Elderly, University Hospitals of Derby and Burton NHS Foundation Trust, Derby DE22 3NE, UK
| | - Kenneth Smith
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing and NIHR Nottingham Biomedical Research Centre, University of Nottingham, Derby DE22 3DT, UK; (A.L.G.); (K.S.); (P.J.A.)
| | - Philip J. Atherton
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing and NIHR Nottingham Biomedical Research Centre, University of Nottingham, Derby DE22 3DT, UK; (A.L.G.); (K.S.); (P.J.A.)
| | - Carolyn A. Greig
- School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Edgbaston B15 2TT, UK; (S.L.M.); (C.A.G.)
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing, University of Birmingham, Edgbaston B15 2TT, UK
- NIHR Birmingham Biomedical Research Centre, University Hospitals Birmingham NHS Foundation Trust and the University of Birmingham, Edgbaston B15 2TT, UK
| | - Bethan E. Phillips
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing and NIHR Nottingham Biomedical Research Centre, University of Nottingham, Derby DE22 3DT, UK; (A.L.G.); (K.S.); (P.J.A.)
- Correspondence:
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Evans WJ, Shankaran M, Smith EC, Morris C, Nyangau E, Bizieff A, Matthews M, Mohamed H, Hellerstein M. Profoundly lower muscle mass and rate of contractile protein synthesis in boys with Duchenne muscular dystrophy. J Physiol 2021; 599:5215-5227. [PMID: 34569076 DOI: 10.1113/jp282227] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 09/15/2021] [Indexed: 12/29/2022] Open
Abstract
Boys with Duchenne muscular dystrophy (DMD) experience a progressive loss of functional muscle mass, with fibrosis and lipid accumulation. Accurate evaluation of whole-body functional muscle mass (MM) in DMD patients has not previously been possible and the rate of synthesis of muscle proteins remains unexplored. We used non-invasive, stable isotope-based methods from plasma and urine to measure the fractional rate of muscle protein synthesis (FSR) functional muscle mass (MM), and fat free mass (FFM) in 10 DMD (6-17 years) and 9 age-matched healthy subjects. An oral dose of D3 creatine in 70% 2 H2 O was administered to determine MM and FFM followed by daily 70% 2 H2 O to measure protein FSR. Functional MM was profoundly reduced in DMD subjects compared to controls (17% vs. 41% of body weight, P < 0.0001), particularly in older, non-ambulant patients in whom functional MM was extraordinarily low (<13% body weight). We explored the urine proteome to measure FSR of skeletal muscle-derived proteins. Titin, myosin light chain and gelsolin FSRs were substantially lower in DMD subjects compared to controls (27%, 11% and 40% of control, respectively, P < 0.0001) and were strongly correlated. There were no differences in muscle-derived sarcoplasmic proteins FSRs (creatine kinase M-type and carbonic anhydrase-3) measured in plasma. These data demonstrate that both functional MM, body composition and muscle protein synthesis rates can be quantified non-invasively and are markedly different between DMD and control subjects and suggest that the rate of contractile but not sarcoplasmic protein synthesis is affected by a lack of dystrophin. KEY POINTS: Duchenne muscular dystrophy (DMD) results in a progressive loss of functional skeletal muscle but total body functional muscle mass or rates of muscle protein synthesis have not previously been assessed in these patients. D3 -creatine dilution was used to measure total functional muscle mass and oral 2 H2 O was used to examine the rates of muscle protein synthesis non-invasively in boys with DMD and healthy controls using urine samples. Muscle mass was profoundly lower in DMD compared to control subjects, particularly in older, non-ambulant patients. The rates of contractile protein synthesis but not sarcoplasmic proteins were substantially lower in DMD. These results may provide non-invasive biomarkers for disease progression and therapeutic efficacy in DMD and other neuromuscular diseases.
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Affiliation(s)
- William J Evans
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA, USA.,Department of Medicine, Duke Medical Center, Durham, NC, USA
| | - Mahalakshmi Shankaran
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA, USA
| | - Edward C Smith
- Department of Pediatrics, Duke Medical Center, Durham, NC, USA
| | | | - Edna Nyangau
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA, USA
| | - Alec Bizieff
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA, USA
| | - Marcy Matthews
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA, USA
| | - Hussein Mohamed
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA, USA
| | - Marc Hellerstein
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA, USA
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