ORCID Profile
0000-0003-2403-3387
Current Organisations
Mary MacKillop Institute for Health Research, Australian Catholic University
,
University of Nottingham
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Publications
Protein ingestion preserves proteasome activity during intense aseptic inflammation and facilitates skeletal muscle recovery in humans
Publisher: Cambridge University Press (CUP)
Date: 14-08-2017
DOI: 10.1017/S0007114517001829
Abstract: The ubiquitin–proteasome system (UPS) is the main cellular proteolytic system responsible for the degradation of normal and abnormal (e.g. oxidised) proteins. Under catabolic conditions characterised by chronic inflammation, the UPS is activated resulting in proteolysis, muscle wasting and impaired muscle function. Milk proteins provide sulphur-containing amino acid and have been proposed to affect muscle inflammation. However, the response of the UPS to aseptic inflammation and protein supplementation is largely unknown. The aim of this study was to investigate how milk protein supplementation affects UPS activity and skeletal muscle function under conditions of aseptic injury induced by intense, eccentric exercise. In a double-blind, cross-over, repeated measures design, eleven men received either placebo (PLA) or milk protein concentrate (PRO, 4×20 g on exercise day and 20 g/d for the following 8 days), following an acute bout of eccentric exercise (twenty sets of fifteen eccentric contractions at 30°/s) on an isokinetic dynamometer. In each trial, muscle biopsies were obtained from the vastus lateralis muscle at baseline, as well as at 2 and 8 d post exercise, whereas blood s les were collected before exercise and at 6 h, 1 d, 2 d and 8 d post exercise. Muscle strength and soreness were assessed before exercise, 6 h post exercise and then daily for 8 consecutive days. PRO preserved chymotrypsin-like activity and attenuated the decrease of strength, facilitating its recovery. PRO also prevented the increase of NF- κ B phosphorylation and HSP70 expression throughout recovery. We conclude that milk PRO supplementation following exercise-induced muscle trauma preserves proteasome activity and attenuates strength decline during the pro-inflammatory phase.
Reprint of: Musculoskeletal system in the old age and the demand for healthy ageing biomarkers
Publisher: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.MAD.2014.03.002
Abstract: Population ageing has emerged as a major demographic trend worldwide due to improved health and longevity. This global ageing phenomenon will have a major impact on health-care systems worldwide due to increased morbidity and greater needs for hospitalization/institutionalization. As the ageing population increases worldwide, there is an increasing awareness not only of increased longevity but also of the importance of "healthy ageing" and "quality of life". Yet, the age related chronic inflammation is believed to be pathogenic with regards to its contribution to frailty and degenerative disorders. In particular, the frailty syndrome is increasingly being considered as a key risk indicator of adverse health outcomes. In addition, elderly may be also prone to be resistant to anabolic stimuli which is likely a key factor in the loss of skeletal muscle mass with ageing. Vital to understand these key biological processes is the development of biological markers, through system biology approaches, aiding at strategies for tailored therapeutic and personalized nutritional program. Overall aim is to prevent or attenuate decline of key physiological functions required to live an active, independent life. This review focus on core indicators of health and functions in older adults, where nutrition and tailored personalized programs could exhibit preventive roles, and where the aid of metabolomics technologies are increasingly displaying potential in revealing key molecular mechanisms/targets linked to specific ageing and/or healthy ageing processes.
Screen-based sedentary behavior and associations with functional strength in 6–15 year-old children in the United States
Publisher: Springer Science and Business Media LLC
Date: 12-2015
Amino Acid Composition of Breast Milk from Urban Chinese Mothers
Publisher: MDPI AG
Date: 28-09-2016
DOI: 10.3390/NU8100606
Unacylated ghrelin, leptin, and appetite display diurnal rhythmicity in lean adults
Publisher: American Physiological Society
Date: 05-2021
DOI: 10.1152/JAPPLPHYSIOL.00920.2020
Abstract: Simultaneous assessment of subjective appetite, unacylated ghrelin, and leptin was carried out over a continuous 37-h protocol for the first time under conditions of controlled light, sleep, and feeding in healthy, lean adults. Rhythms were observed in unacylated ghrelin, leptin, and components of subjective appetite, such as hunger, prospective consumption, and fullness. Concurrent measurement of rhythms in these variables is important to fully understand the temporal relationships between components of appetite as well as the influence of diurnal factors such as sleep, light, and feeding.
Low-Grade Systemic Inflammation Interferes with Anabolic and Catabolic Characteristics of the Aged Human Skeletal Muscle
Publisher: Hindawi Limited
Date: 07-12-2021
DOI: 10.1155/2021/8376915
Abstract: Aging is associated with the development of chronic low-grade systemic inflammation (LGSI) characterized by increased circulating levels of proinflammatory cytokines and acute phase proteins such as C-reactive protein (CRP). Collective evidence suggests that elevated levels of inflammatory mediators such as CRP, interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α) are correlated with deteriorated skeletal muscle mass and function, though the molecular footprint of this observation in the aged human skeletal muscle remains obscure. Based on animal models showing impaired protein synthesis and enhanced degradation in response to LGSI, we compared here the response of proteolysis- and protein synthesis-related signaling proteins as well as the satellite cell and amino acid transporter protein content between healthy older adults with increased versus physiological blood hs-CRP levels in the fasted (basal) state and after an anabolic stimulus comprised of acute resistance exercise (RE) and protein feeding. Our main findings indicate that older adults with increased hs-CRP levels demonstrate (i) increased proteasome activity, accompanied by increased protein carbonylation and IKKα/β phosphorylation (ii) reduced Pax7+ satellite cells (iii) increased insulin resistance, at the basal state and (iv) impaired S6 ribosomal protein phosphorylation accompanied by hyperinsulinemia following an acute RE bout combined with protein ingestion. Collectively, these data provide support to the concept that age-related chronic LGSI may upregulate proteasome activity via induction of the NF-κB signaling and protein oxidation and impair the insulin-dependent anabolic potential of human skeletal muscle.
Intermittent fasting, energy balance and associated health outcomes in adults: Study protocol for a randomised controlled trial
Publisher: Springer Science and Business Media LLC
Date: 02-02-2018
Impact of moderate dietary protein restriction on glucose homeostasis in a model of estrogen deficiency
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.JNUTBIO.2022.108952
Abstract: The need to consume adequate dietary protein to preserve physical function during ageing is well recognized. However, the effect of protein intakes on glucose metabolism is still intensively debated. During age-related estrogen withdrawal at the time of the menopause, it is known that glucose homeostasis may be impaired but the influence of dietary protein levels in this context is unknown. The aim of the present study is to elucidate the in idual and interactive effects of estrogen deficiency and suboptimal protein intake on glucose homeostasis in a preclinical model involving ovariectomy (OVX) and a 13 week period of a moderately reduced protein intake in 7 month-old ageing rats. To investigate mechanisms of action acting via the pancreas-liver-muscle axis, fasting circulating levels of insulin, glucagon, IGF-1, FGF21 and glycemia were measured. The hepatic lipid infiltration and the protein expression of GLUT4 in the gastrocnemius were analyzed. The gene expression of some hepatokines, myokines and lipid storage/oxidation related transcription factors were quantified in the liver and the gastrocnemius. We show that, regardless of the estrogen status, moderate dietary protein restriction increases fasting glycemia without modifying insulinemia, body weight gain and composition. This fasting hyperglycemia is associated with estrogen status-specific metabolic alterations in the muscle and liver. In estrogen-replete (SHAM) rats, GLUT4 was down-regulated in skeletal muscle while in estrogen-deficient (OVX) rats, hepatic stress-associated hyperglucagonemia and high serum FGF21 were observed. These findings highlight the importance of meeting dietary protein needs to avoid disturbances in glucose homeostasis in ageing female rats with or without estrogen withdrawal.
Thiol-based antioxidant supplementation alters human skeletal muscle signaling and attenuates its inflammatory response and recovery after intense eccentric exercise
Publisher: Elsevier BV
Date: 07-2013
Abstract: The major thiol-disulfide couple of reduced glutathione (GSH) and oxidized glutathione is a key regulator of major transcriptional pathways regulating aseptic inflammation and recovery of skeletal muscle after aseptic injury. Antioxidant supplementation may h er exercise-induced cellular adaptations. The objective was to examine how thiol-based antioxidant supplementation affects skeletal muscle's performance and redox-sensitive signaling during the inflammatory and repair phases associated with exercise-induced microtrauma. In a double-blind, crossover design, 10 men received placebo or N-acetylcysteine (NAC 20 mg · kg(-1) · d(-1)) after muscle-damaging exercise (300 eccentric contractions). In each trial, muscle performance was measured at baseline, after exercise, 2 h after exercise, and daily for 8 consecutive days. Muscle biopsy s les from vastus lateralis and blood s les were collected before exercise and 2 h, 2 d, and 8 d after exercise. NAC attenuated the elevation of inflammatory markers of muscle damage (creatine kinase activity, C-reactive protein, proinflammatory cytokines), nuclear factor κB phosphorylation, and the decrease in strength during the first 2 d of recovery. NAC also blunted the increase in phosphorylation of protein kinase B, mammalian target of rapamycin, p70 ribosomal S6 kinase, ribosomal protein S6, and mitogen activated protein kinase p38 at 2 and 8 d after exercise. NAC also abolished the increase in myogenic determination factor and reduced tumor necrosis factor-α 8 d after exercise. Performance was completely recovered only in the placebo group. Although thiol-based antioxidant supplementation enhances GSH availability in skeletal muscle, it disrupts the skeletal muscle inflammatory response and repair capability, potentially because of a blunted activation of redox-sensitive signaling pathways. This trial was registered at clinicaltrials.gov as NCT01778309.
Longitudinal association of dietary protein intake in infancy and adiposity throughout childhood
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.CLNU.2018.05.013
Abstract: Protein intake in infancy promotes growth, but excessive intake may lead to adiposity in children. However, whether this increased adiposity persists throughout childhood and is independent of diet in later life remains unclear. Therefore, we studied the associations of total protein intake and protein from different sources at age 1 year with repeatedly measured growth and body composition up to age 10 years. Additionally, we examined whether these associations are independent of protein intake and overall diet quality at age 8 years. We included 3573 children from the Generation R study, a population-based prospective cohort in the Netherlands. Dietary intakes were assessed with food-frequency questionnaires at ages 1 and 8 years and macronutrient intakes were expressed as energy percentages (E%). Height and weight were measured at eight time points between ages 1 and 10 years. Fat and fat-free masses were measured at ages 6 and 10 years with dual-energy X-ray-absorptiometry. We calculated body mass index (BMI), fat mass index (FMI) and fat-free mass index (FFMI). Outcomes were standardized for sex and age and expressed as standard deviation scores (SDS). Associations of protein intake with growth and body composition trajectories were examined with multivariable linear mixed models. After adjustment for confounders, 5E% additional protein intake at age 1 year was associated with a 0.10 SDS higher weight (95% CI 0.04, 0.16), 0.10 SDS higher BMI (95% CI 0.04, 0.16), and 0.07 SDS higher FMI (95% CI 0.01, 0.13) up to age 10 years. These associations were explained by protein from animal sources and not plant sources. Associations were independent of protein intake and overall diet quality at age 8 years, and were independent of whether higher protein was consumed at the expense of carbohydrates or fat in the diet. Our study suggests that high protein intake in infancy, particularly from animal food sources, is persistently associated with adiposity up to age 10 years. Restricting protein intake in this critical period of development may aid in the early prevention of adiposity in childhood.
Dietary protein intake in school-age children and detailed measures of body composition: the Generation R Study
Publisher: Springer Science and Business Media LLC
Date: 17-05-2018
DOI: 10.1038/S41366-018-0098-X
Abstract: A high-protein diet in infancy increases the risk of obesity, but the effects of dietary protein intake in mid-childhood on body composition are unclear. Therefore, we studied associations of protein intake (total, animal and plant-sourced) at 8 years of age with anthropometric measures and body composition up to age 10 years. We included 3991 children of the Generation R Study, a prospective cohort in the Netherlands. Dietary protein intake was assessed at 8 years of age using a food-frequency questionnaire and is expressed in energy percentage (E%). Anthropometric measures and body composition (using dual-energy X-ray absorptiometry (DXA)) were assessed at 6 years and during follow-up at 10 years. We calculated body mass index (BMI), fat mass index (FMI), and fat-free mass index (FFMI). All outcomes were sex- and age-standardized and overweight (yes/no) was derived from BMI-SDS. We examined associations of protein intake at 8 years with the combined risk of overweight and obesity, and body composition at 10 years using multivariable logistic and linear regression models. These analyses were adjusted for outcomes at 6 years and protein intake in early life. In multivariable-adjusted models, a 5E% higher protein intake at 8 years was associated with a higher combined risk of overweight and obesity up to 10 years (odds ratio (OR) 1.51, 95% confidence interval (CI): 1.22,1.86), independent of whether it replaced carbohydrates or fat. However, this was mainly explained by an association of protein intake with a higher FFMI (0.07 standard deviation scores (SDS) per 5E%, 95% CI: 0.02,0.11), not FMI. Both plant and animal were associated with a higher FFMI, but the association was stronger for protein from plant sources. For FMI, our findings also suggest trends of higher plant protein intake with lower FMI, and higher animal protein intake with higher FMI. Following this, a higher plant protein intake at the expense of animal protein was associated with a lower FMI (-0.08 SDS per 5E%, 95% CI: -0.15,-0.01). We observed that a higher protein intake in mid-childhood is associated with a higher fat-free mass. Our findings also suggest that protein from plant sources seems to be beneficial for body composition in school-age children.
Lipidomics reveals diurnal lipid oscillations in human skeletal muscle persisting in cellular myotubes cultured in vitro
Publisher: Proceedings of the National Academy of Sciences
Date: 25-09-2017
Abstract: Our experiments provide the analysis of lipid metabolite circadian oscillations in a cellular system synchronized in vitro, suggesting cell-autonomous diurnal changes in lipid profiles independent of feeding. Moreover, our work represents a comprehensive comparison between the lipid composition of human skeletal muscle derived from sedentary healthy adults, receiving hourly isocaloric solutions, and human primary skeletal myotubes cultured in vitro. A substantial number of lipid metabolites, in particular membrane lipids, exhibited oscillatory patterns in muscle tissue and in myotube cells, where they were blunted upon cell-autonomous clock disruption. As lipid oscillations in skeletal muscle membrane lipids may impact on insulin signaling and on the development of insulin resistance, studying the temporal lipid composition of human muscle is therefore of utmost importance.
Two weeks of reduced-volume sprint interval or traditional exercise training does not improve metabolic functioning in sedentary obese men
Publisher: Wiley
Date: 16-07-2013
DOI: 10.1111/DOM.12150
Abstract: To investigate the effects of short-term, reduced-volume sprint interval training (SIT) compared to traditional exercise recommendations (TER) in sedentary obese men. Sixteen subjects [37.8 ± 5.8 years body mass index (BMI) 32.8 ± 4.7 kg/m(2)] were randomly allocated to 2 weeks of either SIT (6 sessions of 8-12 × 10 s sprints) or TER [10 sessions of 30 min at 65% peak oxygen consumption (VO(2peak))] cycle exercise. Fasting plasma glucose, insulin, non-esterified fatty acids (NEFA), homeostasis model assessment of insulin sensitivity (HOMA-IR), body composition and VO(2peak) were assessed at baseline and approximately 72 h after the final training bout. Skeletal muscle biopsy s les were also obtained before and 72 h after training and analysed for AS160 phosphorylation and COX II, COX IV, GLUT-4, Nur77 and SIRT1 protein expression. No changes in BMI, body composition, VO(2peak), glucose, insulin, NEFA and HOMA-IR were observed after training, either within or between groups. Skeletal muscle markers of glucose metabolism and mitochondrial function also remained unaltered after 2 weeks of exercise training. Our findings show that 2 weeks of reduced-volume SIT or TER did not elicit any measurable metabolic adaptations in sedentary obese men. Further work is needed to determine the minimal amount of exercise required for short-term adaptations in this population.
Musculoskeletal system in the old age and the demand for healthy ageing biomarkers
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.MAD.2013.11.003
Abstract: Population ageing has emerged as a major demographic trend worldwide due to improved health and longevity. This global ageing phenomenon will have a major impact on health-care systems worldwide due to increased morbidity and greater needs for hospitalization/institutionalization. As the ageing population increases worldwide, there is an increasing awareness not only of increased longevity but also of the importance of "healthy ageing" and "quality of life". Yet, the age related chronic inflammation is believed to be pathogenic with regards to its contribution to frailty and degenerative disorders. In particular, the frailty syndrome is increasingly being considered as a key risk indicator of adverse health outcomes. In addition, elderly may be also prone to be resistant to anabolic stimuli which is likely a key factor in the loss of skeletal muscle mass with ageing. Vital to understand these key biological processes is the development of biological markers, through system biology approaches, aiding at strategies for tailored therapeutic and personalized nutritional program. Overall aim is to prevent or attenuate decline of key physiological functions required to live an active, independent life. This review focus on core indicators of health and functions in older adults, where nutrition and tailored personalized programs could exhibit preventive roles, and where the aid of metabolomics technologies are increasingly displaying potential in revealing key molecular mechanisms/targets linked to specific ageing and/or healthy ageing processes.
A meta‐analysis comparing the effectiveness of alternate day fasting, the 5:2 diet, and time‐restricted eating for weight loss
Publisher: Wiley
Date: 08-11-2022
DOI: 10.1002/OBY.23568
Abstract: The objective of this meta‐analysis was to compare the effectiveness of different intermittent fasting (IF) regimens on weight loss, in the general population, and compare these to traditional caloric energy restriction (CER). Three databases were searched from 2011 to June 2021 for randomized controlled trials (RCTs) that assessed weight loss and IF, including alternate day fasting (ADF), the 5:2 diet, and time‐restricted eating (TRE). A random effect network analysis was used to compare the effectiveness between the three regimens. Meta‐regression analysis was presented as weighted mean differences of body weight loss. The exploratory random effects network analysis of 24 RCTs ( n = 1768) ranked ADF as the most effective, followed by CER and TRE. The meta‐analysis showed that IF regimens resulted in similar weight loss to CER (mean difference 0.26 kg, 95% CI: –0.31 to 0.84 p = 0.37). Compliance was generally high ( %) in trials shorter than 3 months. The present meta‐analysis concludes that IF is comparable to CER and a promising alternative for weight loss. Among the three regimens, ADF showed the highest effectiveness for weight loss, followed by CER and TRE. Further well‐powered RCTs with longer durations of intervention are required to draw solid conclusions.
Protein and Energy Intakes Are Skewed toward the Evening among Children and Adolescents in the United States: NHANES 2013-2014
Publisher: Elsevier BV
Date: 03-05-2017
Transcriptomic analyses reveal rhythmic and CLOCK-driven pathways in human skeletal muscle
Publisher: eLife Sciences Publications, Ltd
Date: 16-04-2018
DOI: 10.7554/ELIFE.34114
Abstract: Circadian regulation of transcriptional processes has a broad impact on cell metabolism. Here, we compared the diurnal transcriptome of human skeletal muscle conducted on serial muscle biopsies in vivo with profiles of human skeletal myotubes synchronized in vitro. More extensive rhythmic transcription was observed in human skeletal muscle compared to in vitro cell culture as a large part of the in vivo mRNA rhythmicity was lost in vitro. siRNA-mediated clock disruption in primary myotubes significantly affected the expression of ~8% of all genes, with impact on glucose homeostasis and lipid metabolism. Genes involved in GLUT4 expression, translocation and recycling were negatively affected, whereas lipid metabolic genes were altered to promote activation of lipid utilization. Moreover, basal and insulin-stimulated glucose uptake were significantly reduced upon CLOCK depletion. Our findings suggest an essential role for the circadian coordination of skeletal muscle glucose homeostasis and lipid metabolism in humans.
Timing and pattern of postexercise protein ingestion affects whole-body protein balance in healthy children: a randomized trial
Publisher: Canadian Science Publishing
Date: 11-2017
Abstract: The dose and timing of postexercise protein ingestion can influence whole-body protein balance (WBPB) in adults, although comparable data from children are scarce. This study investigated how protein intake (both amount and distribution) postexercise can affect WBPB in physically active children. Thirty-five children (26 males 9–13 years old) underwent a 5-day adaptation diet, maintaining a protein intake of 0.95 g·kg −1 ·day −1 . Participants consumed [ 15 N]glycine (2 mg·kg −1 ) before performing 3 × 20 min of variable-intensity cycling, and whole-body protein kinetics were assessed over 6 and 24 h of recovery. Fifteen grams of protein was distributed across 2 isoenergetic carbohydrate-containing beverages (15 and 240 min postexercise) containing reciprocal amounts of protein (i.e., 0 + 15 g, 5 + 10 g, 10 + 5 g, and 15 + 0 g for Groups A–D, respectively). Over the 6 h that included the exercise bout and consumption of the first beverage at 15 min postexercise, WBPB (i.e., synthesis – breakdown) demonstrated a linear increase of 0.647 g·kg −1 ·day −1 per 1 g protein intake (P 0.001). Over 24 h, robust regression revealed that WBPB was best modeled by a parabola (P 0.05), suggesting that a maximum in WBPB was achieved between groups B and C. In conclusion, despite a dose response early in recovery, a periodized protein intake with multiple smaller doses after physical activity may be more beneficial than a single bolus dose in promoting daily WBPB in healthy active children.
Protein Intake at Breakfast Promotes a Positive Whole-Body Protein Balance in a Dose-Response Manner in Healthy Children: A Randomized Trial
Publisher: Elsevier BV
Date: 05-2018
DOI: 10.1093/JN/NXY026
Abstract: Protein ingestion promotes whole-body net protein balance (NB) in children, which is a prerequisite for growth. Determining how much protein is required at breakfast to promote a positive NB, which may be negative after the traditional overnight fast in children, has yet to be determined. We determined the impact of incremental doses of milk protein at breakfast as well as the impact of daily dietary protein distribution on NB in children. A total of 28 children [14 boys, 14 girls age range: 7-11 y body mass index (mean ± SD, in kg/m2): 16.0 ± 1.9] completed 2 intervention trials. During the breakfast meal, participants consumed an isoenergetic beverage with different amounts of protein (0, 7, 14, or 21 g for Groups A-D, respectively) and [15N]-glycine to measure whole body protein metabolism. Whole-body nitrogen turnover, protein synthesis (PS), protein breakdown, and NB were measured over 9 and 24 h. Following an overnight fast, children were in negative NB (-64.5 mg · kg-1 · h-1). Protein ingestion at breakfast induced a stepwise increase in NB over 9 h [Groups A (6.2 mg · kg-1 · h-1) < B (27.9 mg · kg-1 · h-1) < C (46.9 mg · kg-1 · h-1) < D (66.0 mg · kg-1 · h-1)] with all conditions different from each other (all P < 0.01). PS was 42% greater in Group D than in Group A over 9 h (P < 0.05). Consuming ≥7 g of the total daily protein intake at breakfast attenuates the observed overnight protein losses in children during the subsequent 9 h following breakfast consumption. The dose-dependent increase in NB over a daytime fed period, inclusive of breakfast and lunch, highlights the importance of breakfast protein intake on acute anabolism in healthy active children. This trial was registered at clinicaltrials.gov as NCT02465151.
Systemic and Metabolic Signature of Sarcopenia in Community-Dwelling Older Adults
Publisher: Oxford University Press (OUP)
Date: 08-01-2019
Abstract: Evidence suggests the pivotal contribution of nutrition as a modifiable risk factor for sarcopenia. The present cross-sectional study characterized the nutritional and metabolic profile of sarcopenia through an extensive exploration of a wide array of blood biomarkers related to muscle protein metabolism and transcriptomic signatures in community-dwelling elderly adults. Among 189 older in iduals with a mean age of 73.2 years, sarcopenia was diagnosed according to the Asian Working Group for Sarcopenia criteria based on appendicular lean mass measured by dual-energy X-ray absorptiometry scan, muscle strength, and gait speed. Nutritional status was evaluated using the mini-nutritional assessment (MNA). In addition, we assessed specific blood biomarkers of nutritional status (plasma essential amino acids [EAAs], vitamins), nicotine-derived metabolites, and an extensive microarray analysis from peripheral blood mononuclear cells. Malnutrition defined by low MNA score was independently associated with sarcopenia (p < .001). Sarcopenic elderly showed lower body mass index and leptin and higher adiponectin and high-density lipoproteins. Levels of EAAs including lysine, methionine, phenylalanine, threonine, as well as branched-chain AAs and choline, were inversely associated with sarcopenia. Furthermore, nicotine metabolites (cotinine and trans-3'-hydroxycotine) and vitamin B6 status were linked to one or more clinical and functional measures of sarcopenia. Differentially expressed genes and ingenuity pathway analysis supported the association of nutrition with sarcopenia. Herein, the characterization of a nutritional and metabolic signature of sarcopenia provides a firm basis and potential identification of specific targets and directions for the nutritional approach to the prevention and treatment of sarcopenia in aging populations.
Nutrition and the biology of human ageing: Bone health & osteoporosis / sarcopenia / immune deficiency
Publisher: Springer Science and Business Media LLC
Date: 14-09-2013
Regulation of Granulocyte Colony-Stimulating Factor and Its Receptor in Skeletal Muscle Is Dependent Upon the Type of Inflammatory Stimulus
Publisher: Mary Ann Liebert Inc
Date: 09-2015
Abstract: The cytokine granulocyte colony-stimulating factor (G-CSF) binds to its receptor (G-CSFR) to stimulate hematopoietic stem cell mobilization, myelopoiesis, and the production and activation of neutrophils. In response to exercise-induced muscle damage, G-CSF is increased in circulation and G-CSFR has recently been identified in skeletal muscle cells. While G-CSF/G-CSFR activation mediates pro- and anti-inflammatory responses, our understanding of the role and regulation in the muscle is limited. The aim of this study was to investigate, in vitro and in vivo, the role and regulation of G-CSF and G-CSFR in skeletal muscle under conditions of muscle inflammation and damage. First, C2C12 myotubes were treated with lipopolysaccharide (LPS) with and without G-CSF to determine if G-CSF modulates the inflammatory response. Second, the regulation of G-CSF and its receptor was measured following eccentric exercise-induced muscle damage and the expression levels we investigated for redox sensitivity by administering the antioxidant N-acetylcysteine (NAC). LPS stimulation of C2C12 myotubes resulted in increases in G-CSF, interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-α (TNFα) messenger RNA (mRNA) and an increase in G-CSF, IL-6, and MCP-1 release from C2C12 myotubes. The addition of G-CSF following LPS stimulation of C2C12 myotubes increased IL-6 mRNA and cytokine release into the media, however it did not affect MCP-1 or TNFα. Following eccentric exercise-induced muscle damage in humans, G-CSF levels were either marginally increased in circulation or remain unaltered in skeletal muscle. Similarly, G-CSFR levels remained unchanged in response to damaging exercise and G-CSF/G-CSFR did not change in response to NAC. Collectively, these findings suggest that G-CSF may cooperate with IL-6 and potentially promote muscle regeneration in vitro, whereas in vivo aseptic inflammation induced by exercise did not change G-CSF and G-CSFR responses. These observations suggest that different models of inflammation produce a different G-CSF response.
Skeletal muscle myostatin mRNA expression is upregulated in aged human adults with excess adiposity but is not associated with insulin resistance and ageing
Publisher: Springer Science and Business Media LLC
Date: 06-10-2023
Sedentary Behavior Research Network (SBRN) – Terminology Consensus Project process and outcome
Publisher: Springer Science and Business Media LLC
Date: 10-06-2017
The Importance of Dietary Protein at Breakfast in Childhood
Publisher: S. Karger AG
Date: 2019
DOI: 10.1159/000493706
Abstract: In order for the body to maintain a healthy and normal steady state of lean body mass, body proteins constantly undergo breakdown and synthesis. The rate at which lean tissue is synthetized must equal the rate at which it is being broken down in order to maintain body protein levels. During growth, not only is there an increase in the net deposition of protein, but the rates of both protein synthesis and breakdown are also increased leading potentially to an increased demand of dietary protein in conditions of increased turnover. When referring to growth, the growth potential of an in idual in height and overall shape tends to be genetically determined so that each in idual follows a growth curve canalized in terms of both extent and time course if conditions are favorable, where nutrition status may be classed as such as a favorable condition. To this end, identifying specific moments throughout the day whereby whole body protein balance is in a net negative state may provide key opportunities for specific nutrient provision with the aim of optimizing whole body protein accrual.
Ingestion of a Pre-bedtime Protein Containing Beverage Prevents Overnight Induced Negative Whole Body Protein Balance in Healthy Middle-Aged Men: A Randomized Trial.
Publisher: Frontiers Media SA
Date: 29-11-2019
Chronotype: Implications for Epidemiologic Studies on Chrono-Nutrition and Cardiometabolic Health
Publisher: Elsevier BV
Date: 2019
The 5′ adenosine monophosphate-activated protein kinase: Regulating the ebb and flow of cellular energetics
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.BIOCEL.2009.07.004
Abstract: The 5' adenosine monophosphate-activated protein kinase (AMPK) is a heterotrimeric, evolutionary conserved enzyme which has emerged as a critical regulator of skeletal muscle cellular bioenergetics. AMPK is activated by both chemical (adipokines) and mechanical (stretch, contraction) stimuli leading to metabolic changes within muscle cells that include increased fatty acid oxidation, glucose uptake and glycolysis, as well as the stimulation and regulation of mitochondrial biogenesis. Collectively these acute responses and chronic adaptations act to reduce cellular disturbances, resulting in tighter metabolic control and maintenance of energy homeostasis. This brief review will describe the structure, function and activation of AMPK in skeletal muscle and how this ubiquitous molecule may be a plausible target for the treatment of several lifestyle-related metabolic disorders.
Single-leg cycle training is superior to double-leg cycling in improving the oxidative potential and metabolic profile of trained skeletal muscle
Publisher: American Physiological Society
Date: 05-2011
DOI: 10.1152/JAPPLPHYSIOL.01247.2010
Abstract: Single-leg cycling may enhance the peripheral adaptations of skeletal muscle to a greater extent than double-leg cycling. The purpose of the current study was to determine the influence of 3 wk of high-intensity single- and double-leg cycle training on markers of oxidative potential and muscle metabolism and exercise performance. In a crossover design, nine trained cyclists (78 ± 7 kg body wt, 59 ± 5 ml·kg −1 ·min −1 maximal O 2 consumption) performed an incremental cycling test and a 16-km cycling time trial before and after 3 wk of double-leg and counterweighted single-leg cycle training (2 training sessions per week). Training involved three (double) or six (single) maximal 4-min intervals with 6 min of recovery. Mean power output during the single-leg intervals was more than half that during the double-leg intervals (198 ± 29 vs. 344 ± 38 W, P 0.05). Skeletal muscle biopsy s les from the vastus lateralis revealed a training-induced increase in Thr 172 -phosphorylated 5′-AMP-activated protein kinase α-subunit for both groups ( P 0.05). However, the increase in cytochrome c oxidase subunits II and IV and GLUT-4 protein concentration was greater following single- than double-leg cycling ( P 0.05). Training-induced improvements in maximal O 2 consumption (3.9 ± 6.2% vs. 0.6 ± 3.6%) and time-trial performance (1.3 ± 0.5% vs. 2.3 ± 4.2%) were similar following both interventions. We conclude that short-term high-intensity single-leg cycle training can elicit greater enhancement in the metabolic and oxidative potential of skeletal muscle than traditional double-leg cycling. Single-leg cycling may therefore provide a valuable training stimulus for trained and clinical populations.
Disassociation between the effects of amino acids and insulin on signaling, ubiquitin ligases, and protein turnover in human muscle
Publisher: American Physiological Society
Date: 09-2008
DOI: 10.1152/AJPENDO.90411.2008
Abstract: We determined the effects of intravenous infusion of amino acids (AA) at serum insulin of 5, 30, 72, and 167 mU/l on anabolic signaling, expression of ubiquitin-proteasome components, and protein turnover in muscles of healthy young men. Tripling AA availability at 5 mU/l insulin doubled incorporation of [1- 13 C]leucine [i.e., muscle protein synthesis (MPS), P 0.01] without affecting the rate of leg protein breakdown (LPB appearance of d 5 -phenylalanine). While keeping AA availability constant, increasing insulin to 30 mU/l halved LPB ( P 0.05) without further inhibition at higher doses, whereas rates of MPS were identical to that at 5 mU/l insulin. The phosphorylation of PKB Ser 473 and p70 S6k Thr 389 increased concomitantly with insulin, but whereas raising insulin to 30 mU/l increased the phosphorylation of mTOR Ser 2448 , 4E-BP1 Thr 37/46 , or GSK3β Ser 9 and decreased that of eEF2 Thr 56 , higher insulin doses to 72 and 167 mU/l did not augment these latter responses. MAFbx and proteasome C2 subunit proteins declined as insulin increased, with MuRF-1 expression largely unchanged. Thus increasing AA and insulin availability causes changes in anabolic signaling and amounts of enzymes of the ubiquitin-proteasome pathway, which cannot be easily reconciled with observed effects on MPS or LPB.
Postexercise Dietary Protein Ingestion Increases Whole-Body Leucine Balance in a Dose-Dependent Manner in Healthy Children
Publisher: Elsevier BV
Date: 05-04-2017
A randomized controlled trial to isolate the effects of fasting and energy restriction on weight loss and metabolic health in lean adults
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-06-2021
DOI: 10.1126/SCITRANSLMED.ABD8034
Abstract: Daily energy restriction more effectively reduces body fat content than alternate-day fasting, with no evidence of fasting-specific health benefits.
Caffeine Ingestion and Cycling Power Output in a Low or Normal Muscle Glycogen State
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2013
Skeletal muscle: increasing the size of the locomotor cell
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.BIOCEL.2010.05.013
Abstract: Skeletal muscle is the most abundant tissue in the body comprising 40-50% of body mass in humans and playing a central role in maintaining metabolic health. Skeletal muscle protein undergoes rapid turnover, a process that is intricately regulated by the balance between the rates of protein synthesis and degradation. The process of skeletal muscle hypertrophy and regeneration is an important adaptive response to both contractile activity (i.e., exercise) and nutrient availability (i.e., protein ingestion). Ageing and physical inactivity are two conditions associated with a loss of skeletal muscle protein (sarcopenia). Sarcopenia is characterised by a deterioration of muscle quantity and quality, although the precise mechanism(s) underlying this condition remain to be elucidated. This review will (1) summarise our current understanding of the origin and plasticity of skeletal muscle, (2) discuss the major effectors of muscle growth, and (3) highlight the importance of skeletal muscle health in the prevention of several common pathologies.
Effect of resistance training and protein intake pattern on myofibrillar protein synthesis and proteome kinetics in older men in energy restriction
Publisher: Wiley
Date: 17-04-2018
DOI: 10.1113/JP275246
A Systematic Review of the Effects of Plant Compared with Animal Protein Sources on Features of Metabolic Syndrome
Publisher: Elsevier BV
Date: 25-01-2017
Abstract: Dietary protein may play an important role in the prevention of metabolic dysfunctions. However, the way in which the protein source affects these dysfunctions has not been clearly established. The aim of the current systematic review was to compare the impact of plant- and animal-sourced dietary proteins on several features of metabolic syndrome in humans. The PubMed database was searched for both chronic and acute interventional studies, as well as observational studies, in healthy humans or those with metabolic dysfunctions, in which the impact of animal and plant protein intake was compared while using the following variables: cholesterolemia and triglyceridemia, blood pressure, glucose homeostasis, and body composition. Based on data extraction, we observed that soy protein consumption (with isoflavones), but not soy protein alone (without isoflavones) or other plant proteins (pea and lupine proteins, wheat gluten), leads to a 3% greater decrease in both total and LDL cholesterol compared with animal-sourced protein ingestion, especially in in iduals with high fasting cholesterol concentrations. This observation was made when animal proteins were provided as a whole diet rather than given supplementally. Some observational studies reported an inverse association between plant protein intake and systolic and diastolic blood pressure, but this was not confirmed by intervention studies. Moreover, plant protein (wheat gluten, soy protein) intake as part of a mixed meal resulted in a lower postprandial insulin response than did whey. This systematic review provides some evidence that the intake of soy protein associated with isoflavones may prevent the onset of risk factors associated with cardiovascular disease, i.e., hypercholesterolemia and hypertension, in humans. However, we were not able to draw any further conclusions from the present work on the positive effects of plant proteins relating to glucose homeostasis and body composition.
Hypoenergetic diet-induced reductions in myofibrillar protein synthesis are restored with resistance training and balanced daily protein ingestion in older men
Publisher: American Physiological Society
Date: 05-2015
DOI: 10.1152/AJPENDO.00550.2014
Abstract: Strategies to enhance weight loss with a high fat-to-lean ratio in overweight/obese older adults are important since lean loss could exacerbate sarcopenia. We examined how dietary protein distribution affected muscle protein synthesis during energy balance (EB), energy restriction (ER), and energy restriction plus resistance training (ER + RT). A 4-wk ER diet was provided to overweight/obese older men (66 ± 4 yr, 31 ± 5 kg/m 2 ) who were randomized to either a balanced (BAL: 25% daily protein/meal × 4) or skewed (SKEW: 7:17:72:4% daily protein/meal n = 10/group) pattern. Myofibrillar and sarcoplasmic protein fractional synthetic rates (FSR) were measured during a 13-h primed continuous infusion of l-[ ring- 13 C 6 ]phenylalanine with BAL and SKEW pattern of protein intake in EB, after 2 wk ER, and after 2 wk ER + RT. Fed-state myofibrillar FSR was lower in ER than EB in both groups ( P 0.001), but was greater in BAL than SKEW ( P = 0.014). In ER + RT, fed-state myofibrillar FSR increased above ER in both groups and in BAL was not different from EB ( P = 0.903). In SKEW myofibrillar FSR remained lower than EB ( P = 0.002) and lower than BAL ( P = 0.006). Fed-state sarcoplasmic protein FSR was reduced similarly in ER and ER + RT compared with EB ( P 0.01) in both groups. During ER in overweight/obese older men a BAL consumption of protein stimulated the synthesis of muscle contractile proteins more effectively than traditional, SKEW distribution. Combining RT with a BAL protein distribution “rescued” the lower rates of myofibrillar protein synthesis during moderate ER.
Contraction-induced changes in TNFα and Akt-mediated signalling are associated with increased myofibrillar protein in rat skeletal muscle
Publisher: Springer Science and Business Media LLC
Date: 13-03-2010
DOI: 10.1007/S00421-010-1427-5
Abstract: Resistance training results in skeletal muscle hypertrophy, but the molecular signalling mechanisms responsible for this altered phenotype are incompletely understood. We used a resistance training (RT) protocol consisting of three sessions [day 1 (d1), day 3 (d3), day 5 (d5)] separated by 48 h recovery (squat exercise, 4 sets x 10 repetitions, 3 min recovery) to determine early signalling responses to RT in rodent skeletal muscle. Six animals per group were killed 3 h after each resistance training session and 24 and 48 h after the last training session (d5). There was a robust increase in TNFalpha protein expression, and IKK(Ser180/181) and p38MAPK(Thr180/Tyr182) phosphorylation on d1 (P < 0.05), which abated with subsequent RT, returning to control levels by d5 for TNFalpha and IKK(Ser180/181). There was a trend for a decrease in MuRF-1 protein expression, 48 h following d5 of training (P = 0.08). Notably, muscle myofibrillar protein concentration was elevated compared to control 24 and 48 h following RT (P < 0.05). Akt(Ser473) and mTOR(Ser2448) phosphorylation were unchanged throughout RT. Phosphorylation of p70S6k(Thr389) increased 3 h post-exercise on d1, d3 and d5 (P < 0.05), whilst phosphorylation of S6(Ser235/236) increased on d1 and d3 (P < 0.05). Our results show a rapid attenuation of inflammatory signalling with repeated bouts of resistance exercise, concomitant with summation in translation initiation signalling in skeletal muscle. Indeed, the cumulative effect of these signalling events was associated with myofibrillar protein accretion, which likely contributes to the early adaptations in response to resistance training overload in the skeletal muscle.
Chrono-nutrition: a review of current evidence from observational studies on global trends in time-of-day of energy intake and its association with obesity
Publisher: Cambridge University Press (CUP)
Date: 22-06-2016
DOI: 10.1017/S0029665116000306
Abstract: The importance of the circadian rhythm in regulating human food intake behaviour and metabolism has long been recognised. However, little is known as to how energy intake is distributed over the day in existing populations, and its potential association with obesity. The present review describes global trends in time-of-day of energy intake in the general population based on data from cross-sectional surveys and longitudinal cohorts. Evidence of the association between time-of-day of energy intake and obesity is also summarised. Overall, there were a limited number of cross-sectional surveys and longitudinal cohorts that provided data on time-of-day of energy intake. In the identified studies, a wide variation in time-of-day of energy intake was observed, with patterns of energy distribution varying greatly by country and geographical area. In relation to obesity, eight cross-sectional surveys and two longitudinal cohorts were identified. The association between time-of-day of energy intake and obesity varied widely, with several studies reporting a positive link between evening energy intake and obesity. In conclusion, the current review summarises global trends in time-of-day of energy intake. The large variations across countries and global regions could have important implications to health, emphasising the need to understand the socio-environmental factors guiding such differences in eating patterns. Evidence of the association between time-of-day of energy intake and BMI also varied. Further larger scale collaborations between various countries and regions are needed to sum data from existing surveys and cohorts, and guide our understanding of the role of chrono-nutrition in health.
Related Organisations
Mary MacKillop Institute For Health Research, Australian Catholic University
Location: Australia
University Of Nottingham
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
No related grants have been discovered for Leonidas Karagounis.