Plasma Amino Acid Concentrations Are Associated with Muscle Function in Older Japanese Women

A Principal Component Analysis of Metabolome and Cognitive Decline Among Japanese Older Adults: Cross-sectional Analysis Using Tohoku Medical Megabank Cohort Study Data

BACKGROUND

Dementia is the leading cause of disability and imposes a significant burden on society. Previous studies have suggested an association between metabolites and cognitive decline. Although the metabolite composition differs between Western and Asian populations, studies targeting Asian populations remain scarce.

METHODS

This cross-sectional study used data from a cohort survey of community-dwelling older adults aged ≥60 years living in Miyagi, Japan, conducted by Tohoku Medical Megabank Organization between 2013 and 2016. Forty-three metabolite variables quantified using nuclear magnetic resonance spectroscopy were used as explanatory variables. Dependent variable was the presence of cognitive decline (≤23 points), assessed by the Mini-Mental State Examination. Principal component (PC) analysis was performed to reduce the dimensionality of metabolite variables, followed by logistic regression analysis to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for cognitive decline.

RESULTS

A total of 2,940 participants were included (men: 49.0%, mean age: 67.6 years). Among them, 1.9% showed cognitive decline. The first 12 PC components (PC1-PC12) accounted for 71.7% of the total variance. Multivariate analysis showed that PC1, which mainly represented essential amino acids, was associated with lower odds of cognitive decline (OR 0.89; 95% CI, 0.80-0.98). PC2, which mainly included ketone bodies, was associated with cognitive decline (OR 1.29; 95% CI, 1.11-1.51). PC3, which included amino acids, was associated with lower odds of cognitive decline (OR 0.81; 95% CI, 0.66-0.99).

CONCLUSION

Amino acids are protectively associated with cognitive decline, whereas ketone metabolites are associated with higher odds of cognitive decline.

Associations of serum arginine acid with sarcopenia in Chinese eldely women

BACKGROUND

The prevalence of sarcopenia is increasing in worldwide with accelerated aging process. The high dietary protein intakes are associated with improved muscle mass and strength especially in Asian countries. However, there are few researches on amino acid levels or mechanism exploration. We conducted a case-control study to explore the amino acid metabolic characteristics and potential mechanism of elderly women with sarcopenia using targeted amino acid metabolomics approach combined with an analysis of dietary intake.

METHODS

For our case-control study, we recruited women (65-75 y) from a Shanghai community with 50 patients with sarcopenia and 50 healthy controls. The consensus updated by the Asian Working Group on Sarcopenia in 2019 was used to screening for sarcopenia and control groups. We collected fasting blood samples and evaluated dietary intake. We used the amino acid-targeted metabolomics by ultra performance liquid chromatography tandem mass spectrometry to identify metabolic differentials between the case and control groups and significantly enriched metabolic pathways.

RESULTS

The case (sarcopenia) group had a lower intake of energy, protein, and high-quality protein (P < 0.05) compared to the control (healthy) group. We identified four differential amino acids: arginine (P < 0.001) and cystine (P = 0.003) were lower, and taurine (P = 0.001) were higher in the case group.

CONCLUSION

Low levels of arginine in elderly women are associated with a higher risk of sarcopenia.

Associations between sarcopenia and circulating branched-chain amino acids: a cross-sectional study over 100,000 participants

BACKGROUND

Emerging evidence suggests that alterations in BCAA metabolism may contribute to the pathogenesis of sarcopenia. However, the relationship between branched-chain amino acids (BCAAs) and sarcopenia is incompletely understood, and existing literature presents conflicting results. In this study, we conducted a community-based study involving > 100,000 United Kingdom adults to comprehensively explore the association between BCAAs and sarcopenia, and assess the potential role of muscle mass in mediating the relationship between BCAAs and muscle strength.

METHODS

Multivariable linear regression analysis examined the relationship between circulating BCAAs and muscle mass/strength. Logistic regression analysis assessed the impact of circulating BCAAs and quartiles of BCAAs on sarcopenia risk. Subgroup analyses explored the variations in associations across age, and gender. Mediation analysis investigated the potential mediating effect of muscle mass on the BCAA-muscle strength relationship.

RESULTS

Among 108,017 participants (mean age: 56.40 ± 8.09 years; 46.23% men), positive associations were observed between total BCAA, isoleucine, leucine, valine, and muscle mass (beta, 0.56-2.53; p < 0.05) and between total BCAA, leucine, valine, and muscle strength (beta, 0.91-3.44; p < 0.05). Logistic regression analysis revealed that increased circulating valine was associated with a 47% reduced sarcopenia risk (odds ratio = 0.53; 95% confidence interval = 0.3-0.94; p = 0.029). Subgroup analyses demonstrated strong associations between circulating BCAAs and muscle mass/strength in men and individuals aged ≥ 60 years. Mediation analysis suggested that muscle mass completely mediated the relationship between total BCAA, and valine levels and muscle strength, partially mediated the relationship between leucine levels and muscle strength, obscuring the true effect of isoleucine on muscle strength.

CONCLUSION

This study suggested the potential benefits of BCAAs in preserving muscle mass/strength and highlighted muscle mass might be mediator of BCAA-muscle strength association. Our findings contribute new evidence for the clinical prevention and treatment of sarcopenia and related conditions involving muscle mass/strength loss.

Plasma amino acid signature for sarcopenic phenotypes in community-dwelling octogenarians: Results from the Kawasaki Aging Wellbeing Project

Sarcopenia is one of the primary risk factors for various adverse health events in later life. However, its pathophysiology in the very old population remains unclear. Hence, this study aimed to examine whether plasma free amino acids (PFAAs) correlate with major sarcopenic phenotypes (i.e., muscle mass, muscle strength, and physical performance) in community-dwelling adults aged 85-89 years living in Japan. Cross-sectional data from the Kawasaki Aging Well-being Project were used. We included 133 adults aged 85-89 years. In this study, fasting blood was collected to measure 20 plasma PFAAs. Measures for the three major sarcopenic phenotypes included appendicular lean mass assessed by multifrequency bioimpedance, isometric handgrip strength, and gait speed from a 5 m walk at a usual pace. Furthermore, we used phenotype-specific elastic net regression models adjusted for age centered at 85 years, sex, body mass index, education level, smoking status, and drinking habit to identify significant PFAAs for each sarcopenic phenotype. Higher histidine and lower alanine levels were associated with poor gait speed, but no PFAAs correlated with muscle strength or mass. In conclusion, PFAAs such as plasma histidine and alanine are novel blood biomarkers associated with physical performance in community-dwelling adults aged 85 years or older.

Exploring the impact of exercise and essential amino acid plus cholecalciferol supplementation on physical fitness and body composition in multiple sclerosis: A case study

Key Clinical Message

In MS patients, especially those frail or malnourished, combining home-based exercise twice weekly with essential amino acids and vitamin D may improve body composition, strength, and physical performance, enabling long-term functional improvements.

Abstract

Multiple sclerosis (MS) is associated with reduced bone and muscle strength and function. We aimed to investigate the effectiveness of a 24-week intervention in a 57-year-old frail female with MS. The participant completed a 2×/week exercise intervention and ingested 2×/day a supplement containing 7.5 g essential amino acids and 500 IU cholecalciferol. Body composition, 6-m gait speed (GS), handgrip strength (HGS), 30-sec arm-curl test (30ACT), 6-min walking test (6MWT), 30-sec chair-stand test (30CST), and plasma concentrations of 25-hydroxyvitamin D3 [25(OH)D3], insulin-like growth factor 1 (IGF-1), and amino acids were assessed at baseline, and at Weeks 12 and 24. Plasma 25(OH)D3 increased from 23.2 to 41.3 ng/mL and IGF-1 from 131.6 to 140.7 ng/mL from baseline to post-intervention. BMI, total lean tissue mass (LTM), fat mass, bone mineral content, and the sum of 17 amino acids increased by 3.8, 1.0, 3.5, 0.2, and 19%, respectively, at Week 24. There were clinically significant increases in regional LTM (6.9% arms and 6.3% legs) and large increases in GS (67.3%), dominant HGS (31.5%), non-dominant HGS (11.8%), dominant 30ACT (100%), non-dominant 30ACT (116.7%), 6MWT (125.6%), and 30CST (44.4%). The current intervention was effective in improving components of physical fitness and body composition in a female with MS.

Decreased circulating branched-chain amino acids are associated with development of Alzheimer's disease in elderly individuals with mild cognitive impairment

Background

Nutritional epidemiology has shown that inadequate dietary protein intake is associated with poor brain function in the elderly population. The plasma free amino acid (PFAA) profile reflects nutritional status and may have the potential to predict future changes in cognitive function. Here, we report the results of a 2-year interim analysis of a 3-year longitudinal study following mild cognitive impairment (MCI) participants.

Method

In a multicenter prospective cohort design, MCI participants were recruited, and fasting plasma samples were collected. Based on clinical assessment of cognitive function up to 2 years after blood collection, MCI participants were divided into two groups: remained with MCI or reverted to cognitively normal ("MCI-stable," N = 87) and converted to Alzheimer's disease (AD) ("AD-convert," N = 68). The baseline PFAA profile was compared between the two groups. Stratified analysis based on apolipoprotein E ε4 (APOE ε4) allele possession was also conducted.

Results

Plasma concentrations of all nine essential amino acids (EAAs) were lower in the AD-convert group. Among EAAs, three branched-chain amino acids (BCAAs), valine, leucine and isoleucine, and histidine (His) exhibited significant differences even in the logistic regression model adjusted for potential confounding factors such as age, sex, body mass index (BMI), and APOE ε4 possession (p < 0.05). In the stratified analysis, differences in plasma concentrations of these four EAAs were more pronounced in the APOE ε4-negative group.

Conclusion

The PFAA profile, especially decreases in BCAAs and His, is associated with development of AD in MCI participants, and the difference was larger in the APOE ε4-negative population, suggesting that the PFAA profile is an independent risk indicator for AD development. Measuring the PFAA profile may have importance in assessing the risk of AD conversion in the MCI population, possibly reflecting nutritional status.

Clinical trial registration

[https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000025322], identifier [UMIN000021965].

The Effect of Metabolites on Mitochondrial Functions in the Pathogenesis of Skeletal Muscle Aging

Sarcopenia is an age-related systemic disease characterized by skeletal muscle aging that generally severely affects the quality of life of elderly patients. Metabolomics analysis is a powerful tool for qualitatively and quantitatively characterizing the small molecule metabolomics of various biological matrices in order to clarify all key scientific problems concerning cell metabolism. The discovery of optimal therapy requires a thorough understanding of the cellular metabolic mechanism of skeletal muscle aging. In this review, the relationship between skeletal muscle mitochondria, amino acid, vitamin, lipid, adipokines, intestinal microbiota and vascular microenvironment has been separately reviewed from the perspective of metabolomics, and a new therapeutic direction has been suggested.

Metabolomic profiles to explore biomarkers of severe sarcopenia in older men: A pilot study

BACKGROUND

The pathophysiology of sarcopenia is complex and multifactorial; however, it has not yet been fully elucidated. Identifying metabolomic profiles may help clarify the mechanisms underlying sarcopenia.

OBJECTIVE

This pilot study explored potential noninvasive biomarkers of severe sarcopenia through metabolomic analysis in community-dwelling older men.

METHODS

Twenty older men (mean age: 81.9 ± 2.8 years) were selected from the Korean Frailty and Aging Cohort Study. Participants with severe sarcopenia (n = 10) were compared with non-sarcopenic, age- and body mass index-matched controls (n = 10). Severe sarcopenia was defined as low muscle mass, low muscle strength, and low physical performance using the Asian Working Group for Sarcopenia 2019 criteria. Non-targeted metabolomic profiling of plasma metabolites was performed using capillary electrophoresis time-of-flight mass spectrometry and absolute quantification was performed in target metabolites.

RESULTS

Among 191 plasma metabolic peaks, the concentrations of 10 metabolites significantly differed between severe sarcopenia group and non-sarcopenic controls. The plasma concentrations of L-alanine, homocitrulline, N-acetylserine, gluconic acid, N-acetylalanine, proline, and sulfotyrosine were higher, while those of 4-methyl-2-oxovaleric acid, 3-methyl-2-oxovaleric acid, and tryptophan were lower in participants with severe sarcopenia than in non-sarcopenic controls (all, p < 0.05). Among the 53 metabolites quantified as target metabolites, L-alanine (area under the receiver operating characteristic curve [AUC] = 0.760; p = 0.049), gluconic acid (AUC = 0.800; p = 0.023), proline (AUC = 0.785; p = 0.031), and tryptophan (AUC = 0.800; p = 0.023) determined the presence of severe sarcopenia.

CONCLUSIONS

Plasma metabolomic analysis demonstrated that L-alanine, gluconic acid, proline, and tryptophan may be potential biomarkers of severe sarcopenia. The identified metabolites can provide new insights into the underlying pathophysiology of severe sarcopenia and serve as the basis for preventive interventions.

The Association of Circulating Amino Acids and Dietary Inflammatory Potential with Muscle Health in Chinese Community-Dwelling Older People

Amino acids (AAs) and dietary inflammatory potential play essential roles in muscle health. We examined the associations of dietary inflammatory index (DII) of habitual diet with serum AA profile, and ascertained if the associations between DII and muscle outcomes were mediated by serum AAs, in 2994 older Chinese community-dwelling men and women (mean age 72 years) in Hong Kong. Higher serum branched chain AAs (BCAAs), aromatic AAs and total glutathione (tGSH) were generally associated with better muscle status at baseline. A more pro-inflammatory diet, correlating with higher serum total homocysteine and cystathionine, was directly (90.2%) and indirectly (9.8%) through lower tGSH associated with 4-year decline in hand grip strength in men. Higher tGSH was associated with favorable 4-year changes in hand grip strength, gait speed and time needed for 5-time chair stands in men and 4-year change in muscle mass in women. Higher leucine and isoleucine were associated with decreased risk of sarcopenia in men; the associations were abolished after adjustment for BMI. In older men, perturbations in serum sulfur AAs metabolism may be biomarkers of DII related adverse muscle status, while the lower risk of sarcopenia with higher BCAAs may partly be due to preserved BMI.

Plasma metabolites associated with functional and clinical outcomes in heart failure with reduced ejection fraction with and without type 2 diabetes

Heart failure with reduced ejection fraction (HFrEF) is increasingly treated with medications for type 2 diabetes mellitus (T2DM). Whether metabolic derangements in HFrEF and T2DM are associated with differential outcomes remains unclear. Therefore, understanding molecular pathways in HFrEF and T2DM and their effects on clinical endpoints is important. The FIGHT trial randomized 300 individuals with HFrEF and a recent HF hospitalization to liraglutide (a GLP-1 receptor agonist) versus placebo to assess effects on mortality, HF rehospitalization, and 6-month change in NT-ProBNP. Although the trial showed no clinical benefit of liraglutide, the trial population was highly enriched for individuals with T2DM. Sixty metabolites were quantified via mass spectrometry in plasma from 254 FIGHT participants (N = 147 (57.9%) with T2DM). Principal components analysis reduced the high number of correlated metabolites into uncorrelated factors. The association of factor levels with 90-day changes in 6-min walk distance (6MWD) and NT-proBNP, and with time to mortality or HF hospitalization were evaluated. There were no changes in metabolite factors according to treatment assignment. However, in analyses stratified by T2DM status, changes in five plasma metabolite factors correlated with changes in functional outcomes beyond adjustment: factor 2 (branched-chain amino acids [BCAA]) correlated with changes in NT-proBNP (ρ = − 0.291, p = 4 × 10^–4) and 6MWD (ρ= 0.265, p = 0.011); factor 1 (medium-chain acylcarnitines;  ρ = 0.220, p = 0.008), factor 4 (long-chain dicarboxylacylcarnitines; ρ = 0.191, p = 0.019), factor 5 (long-chain acylcarnitines; ρ = 0.198, p = 0.017), and factor 8 (urea cycle metabolites; ρ = − 0.239, p = 4 × 10^–3), correlated with change in NT-proBNP. Factor 4 was associated with time-to-event (HR = 1.513 [95% CI 1.208–1.896], p = 3 × 10^–4) with a trend towards stronger prognostic effect in T2DM (T2DM: p = 1 × 10^–3, non-T2DM: p = 0.1). We identified metabolites of BCAA, urea cycle and fatty acid metabolism as biomarkers of HFrEF outcomes, with observed differences in HFrEF patients with T2DM. Such biomarkers might enable future diagnostic or therapeutic interventions in individuals with HFrEF and T2DM.

Trial Registration: Clinicaltrials.gov. Identifier: NCT01800968. First posted: February 28, 2013.

Development of a Novel Nutrition-Related Multivariate Biomarker for Mild Cognitive Impairment Based on the Plasma Free Amino Acid Profile

Nutritional epidemiology has shown the importance of protein intake for maintaining brain function in the elderly population. Mild cognitive impairment (MCI) may be associated with malnutrition, especially protein intake. We explored blood-based biomarkers linking protein nutritional status with MCI in a multicenter study. In total, 219 individuals with MCI (79.5 ± 5.7 year) from 10 institutions and 220 individuals who were cognitively normal (CN, 76.3 ± 6.6 year) in four different cities in Japan were recruited. They were divided into the training (120 MCI and 120 CN) and validation (99 MCI and 100 CN) groups. A model involving concentrations of PFAAs and albumin to discriminate MCI from CN individuals was constructed by multivariate logistic regression analysis in the training dataset, and the performance was evaluated in the validation dataset. The concentrations of some essential amino acids and albumin were significantly lower in MCI group than CN group. An index incorporating albumin and PFAA discriminated MCI from CN participants with the AUC of 0.705 (95% CI: 0.632–0.778), and the sensitivities at specificities of 90% and 60% were 25.3% and 76.8%, respectively. No significant association with BMI or APOE status was observed. This cross-sectional study suggests that the biomarker changes in MCI group may be associated with protein nutrition.

Specific Metabolites Involved in Antioxidation and Mitochondrial Function Are Correlated With Frailty in Elderly Men

Background

As an age-related syndrome, frailty may play a central role in poor health among older adults. Sarcopenia overlaps with the physical domain of frailty, and most existing studies have analyzed the associated factors of frailty and sarcopenia as an isolated state. Perturbations in metabolism may play an important role in the presence of frailty or sarcopenia; however, the metabolites associated with frailty, especially overlapping with sarcopenia remain unclear. In this study, we aimed to explore whether amino acids, carnitines, acylcarnitines and lysophosphatidylcholines, as specific panels, are significantly correlated with frailty, especially overlapping with sarcopenia, to gain insight into potential biomarkers and possible biological mechanisms and to facilitate their management.

Methods

We applied a targeted high-performance liquid chromatography-tandem mass spectrometry approach in serum samples from 246 Chinese older men (age 79.2 ± 7.8 years) with frailty (n = 150), non-frailty (n = 96), frailty and sarcopenia (n = 52), non-frail and non-sarcopenic control (n = 85). Frailty was evaluated using Freid phenotype criteria, sarcopenia was defined by diagnostic algorithm of Asian Working Group on Sarcopenia, and the participants were diagnosed as frailty and sarcopenia when they met the evaluation criteria of both frailty and sarcopenia. A panel of 29 metabolomic profiles was assayed and included different classes of amino acids, carnitines, acylcarnitines, and lysophosphatidylcholines (LPCs). Multivariate logistic regression was used to screen the metabolic factors contributing to frailty status, and orthogonal partial least squares discriminant analysis was used to explore important factors and distinguish different groups.

Results

In older men demonstrating the frail phenotype, amino acid perturbations included lower tryptophan and higher glycine levels. With regard to lipid metabolism, the frailty phenotype was characterized by lower concentrations of isovalerylcarnitine (C5), LPC16:0 and LPC18:2, while higher levels of octanoyl-L-carnitine (C8), decanoyl-L-carnitine (C10), dodecanoyl-L-carnitine (C12) and tetradecanoyl-L-carnitine (C14). After adjusting for several clinical confounders, tryptophan, LPC18:2, LPC 16:0 and C5 were negatively correlated with frailty, and C8 and C12 were positively related to frailty. We preliminarily identified metabolic profiles (LPC16:0, LPC18:2, glycine and tryptophan) that may distinguish older men with frailty from those without frailty. Importantly, a set of serum amino acids and LPCs (LPC16:0, LPC18:2, and tryptophan) was characterized in the metabotype of older adults with an overlap of frailty and sarcopenia. The metabolites that were most discriminating of frailty status implied that the underlying mechanism might be involved in antioxidation and mitochondrial dysfunction.

Conclusions

These present metabolic analyses may provide valuable information on the potential biomarkers and possible biological mechanisms of frailty, and overlapping sarcopenia. The findings obtained may offer insight into their management in older adults.

Aging-related metabolic changes in the extensor digitorum longus muscle of senescence-accelerated mouse-prone 8

Aim

Sarcopenia – aging‐related loss of muscle mass and muscle strength – is a key feature of the frailty model. In the present study, we aimed to elucidate the molecular biological changes associated with aging in the extensor digitorum longus muscle of senescence‐accelerated mouse prone 8 mouse model by capillary electrophoresis–mass spectrometry.

Methods

Three groups of senescence‐accelerated mouse prone 8 mice were used, namely, 12‐week‐old (young; n = 5), 40‐week‐old (elderly; n = 5) and 55‐week‐old mice (late elderly; n = 5). The extensor digitorum longus muscle was collected. After preliminary analyses, metabolome analysis was carried out by capillary electrophoresis–mass spectrometry. Additionally, we examined whether the activity of enzymes in the metabolic pathway fluctuated with aging, by real‐time polymerase chain reaction.

Results

Among the 116 water‐soluble metabolites associated with the central energy metabolism pathway, changes were observed in 19 metabolites between 12‐ and 40 ‐weeks‐old, in 40 metabolites between 40‐ and 55‐weeks‐old, and in 57 metabolites between 12‐ and 55‐weeks‐old. The fluctuated metabolites that were common among the groups were Val, putrescine and His. The levels of putrescine, associated with cell proliferation, protein synthesis and nucleic acid synthesis, and β‐Ala and His, a component of carnosine that is characterized by its anti‐oxidant and anti‐fatigue effects, decreased with age.

Conclusions

We confirmed that there were two aging‐related metabolic changes in the extensor digitorum longus muscle of senescence‐accelerated mouse prone 8 mice. Based on the changes in metabolites, cell senescence and fatigue in the extensor digitorum longus muscle might increase in old mice compared with those in young mice, showing molecular biological changes with aging. Geriatr Gerontol Int 2022; 22: 160–167.

Metabolomics as an Important Tool for Determining the Mechanisms of Human Skeletal Muscle Deconditioning

Muscle deconditioning impairs both locomotor function and metabolic health, and is associated with reduced quality life and increased mortality rates. Despite an appreciation of the existence of phenomena such as muscle anabolic resistance, mitophagy, and insulin resistance with age and disease in humans, little is known about the mechanisms responsible for these negative traits. With the complexities surrounding these unknowns and the lack of progress to date in development of effective interventions, there is a need for alternative approaches. Metabolomics is the study of the full array of metabolites within cells or tissues, which collectively constitute the metabolome. As metabolomics allows for the assessment of the cellular metabolic state in response to physiological stimuli, any chronic change in the metabolome is likely to reflect adaptation in the physiological phenotype of an organism. This, therefore, provides a holistic and unbiased approach that could be applied to potentially uncover important novel facets in the pathophysiology of muscle decline in ageing and disease, as well as identifying prognostic markers of those at risk of decline. This review will aim to highlight the current knowledge and potential impact of metabolomics in the study of muscle mass loss and deconditioning in humans and will highlight key areas for future research.

Sarcopenic metabolomic profile reflected a sarcopenic phenotype associated with amino acid and essential fatty acid changes

INTRODUCTION

Although sarcopenia greatly affects health and quality of life in older people, its pathophysiological causes are not fully elucidated. To face this challenge, omics technologies can be used. The metabolome gives a vision of the interaction between the genome and the environment through metabolic networks, thus contributing in clarifying the pathophysiology of the sarcopenic phenotype.

OBJECTIVES

The main goal of this study was to compare the plasma metabolome of sarcopenic and non-sarcopenic older people.

METHODS

Cross-sectional study of 20 sarcopenic and 21 non-sarcopenic older subjects with available frozen plasma samples. Non-targeted metabolomic study by ultra-high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) analysis with later bioinformatics data analysis. Once the significantly different metabolites were identified, the KEGG database was used on them to establish which were the metabolic pathways mainly involved.

RESULTS

From 657 features identified, 210 showed significant differences between the study groups, and 30 had a FoldChangeLog₂ > 2. The most interesting metabolic pathways found with the KEGG database were the biosynthesis of amino acids, arginine and proline metabolism, the biosynthesis of alkaloids derived from ornithine, linoleic acid metabolism, and the biosynthesis of unsaturated fatty acids.

CONCLUSIONS

The study results allowed us to confirm that the concept of "sarcopenic phenotype" is also witnessed at the plasma metabolite levels. The non-targeted metabolomics study can open a wide view of the sarcopenic features changes at the plasma level, which would be linked to the sarcopenic physiopathological alterations.

Where to Find Leucine in Food and How to Feed Elderly With Sarcopenia in Order to Counteract Loss of Muscle Mass: Practical Advice

The term sarcopenia refers to the loss of skeletal muscle mass and strength that generally occurs during aging. The interventions that have proved most effective in reducing the severity and preventing the worsening of sarcopenia include physical exercise, especially resistance, and the administration of dietary supplements in association with a targeted diet; nutritional intervention is the main therapeutic approach for elderly people, since they are very often sedentary (also due to possible disabilities). Among the various nutrients, high biological value proteins and leucine are of particular interest for their demonstrated effects on the health of skeletal muscle. The intake of food containing proteins and leucine during meals stimulates muscle protein synthesis. Lower blood levels of leucine were associated with lower values of the skeletal muscle index, grip strength and performance. The international guidelines recommended that a leucine intake of 3 g at three main meals together with 25-30 g of protein is the goal to be achieved to counteract loss of lean mass in elderly. Food composition databases rarely show the amounts of leucine contained in foods and therefore it becomes difficult to build a diet that follows these guidelines. A table was therefore created for the first time in the literature to collect all the foods richest in leucine, thanks to the union of the most important Italian food databases. Moreover, in order to implement a diet that follows the right recommendations, another tables shows nutritional composition of breakfast, lunch and dinner (that each provide 3 grams of leucine and 25 grams of protein) for seven days.

Effects of In-Hospital Exercise on Frailty in Patients with Hepatocellular Carcinoma

Frailty including physical inactivity is associated with the survival of patients with hepatocellular carcinoma (HCC). We aimed to investigate the effects of in-hospital exercise on frailty in patients with HCC. This was a multi-center observational study. Patients with HCC were classified into exercise (n = 114) and non-exercise (n = 67) groups. The exercise group was treated with a mixture of aerobic and resistance exercises (20-40 min/day, median four days). Frailty was assessed using the liver frailty index (LFI). Factors for changes in LFI were examined by multivariate and decision-tree analyses. The factors were also examined after propensity score matching. During hospitalization, LFI was significantly improved in the exercise group compared to the non-exercise group (ΔLFI -0.17 vs. -0.02, p = 0.0119). In multivariate analysis, exercise (odds ratio (OR) 2.38, 95% confidence interval (CI) 1.240-4.570, p = 0.0091) and females (OR 2.09; 95%CI, 1.062-4.109; p = 0.0328) were identified as independent factors for the improvement of LFI. In the decision-tree analysis, exercise was identified as an initial classifier associated with the improvement of LFI. Similar findings were also seen in the propensity score matching analyses. We demonstrated that in-hospital exercise improved frailty in patients with HCC. Thus, in-hospital exercise may be beneficial for improving physical function in patients with HCC.

Signatures and Clinical Significance of Amino Acid Flux in Sarcopenia: A Systematic Review and Meta-Analysis

BACKGROUND

Dysregulation of amino acids is closely linked to the initiation and progression of sarcopenia. We summarized recent advancements in the studies of amino acid profiles in sarcopenia and systematically presented the clinical significance of amino acid flux in sarcopenia.

METHODS

We systematically searched in MEDLINE, EMBASE, and Cochrane library from inception to June 1, 2021 to capture all studies examining metabolomics of sarcopenia. We used the following keywords: sarcopenia, metabonomics, metabolomics, amino acid profile, and mass spectrometry. Original articles comparing amino acid patterns between persons with and without sarcopenia were included. Two independent investigators independently completed title and abstract screening, data extraction, and quality evaluation. We used a random effects model to examine the association between amino acids levels and sarcopenia. Sensitivity analyses restricted the analyses to studies in which muscle mass was measured by bioelectrical impedance analysis. Study quality was evaluated according to the Agency for Healthcare Research and Quality (AHRQ) checklist.

RESULTS

The systematic research yielded six eligible articles, comprising 1,120 participants. Five studies used muscle mass in combination with physical performance and/or muscle strength as the criteria to diagnose sarcopenia, while one study used muscle mass as a diagnostic criterion alone. We found that the concentrations of branched-chain amino acids leucine (standardized mean difference [SMD] -1.249; 95% confidence interval [CI]: -2.275, -0.223, P = 0.02, I² = 97.7%), isoleucine (SMD -1.077; 95% CI: -2.106, -0.049, P = 0.04, I² = 97.8%), and aromatic amino acid tryptophan (SMD -0.923; 95% CI: -1.580, -0.265, P = 0.01, I² = 89.9%) were significantly reduced in individuals with sarcopenia. Study results were robust in sensitivity analysis.

CONCLUSIONS

The homeostasis of amino acids is critical to maintaining muscle health. The profiles of amino acids might be useful biomarkers for the characterization of sarcopenia. Future studies are warranted to study the clinical significance of amino acids in the diagnosis and treatment of sarcopenia.

Use of plasma-free amino acids as biomarkers for detecting and predicting disease risk

This paper reviews developments regarding the use of plasma-free amino acid (PFAA) profiles as biomarkers for detecting and predicting disease risk. This work was initiated and first published in 2006 and was subsequently developed by Ajinomoto Co., Inc. After commercialization in 2011, PFAA-based tests were adopted in over 1500 clinics and hospitals in Japan, and numerous clinician-led studies have been performed to validate these tests. Evidence is accumulating that PFAA profiles can be used for diabetes prediction and evaluation of frailty; in particular, decreased plasma essential amino acids could contribute to the pathophysiology of severe frailty. Integration of PFAA evaluation as a biomarker and effective essential amino acid supplementation, which improves physical and mental functions in the elderly, could facilitate the development of precision nutrition, including personalized solutions. This present review provides the background for the technology as well as more recent clinical findings, and offers future possibilities regarding the implementation of precision nutrition.

Low Serum Branched-Chain Amino Acid and Insulin-Like Growth Factor-1 Levels Are Associated with Sarcopenia and Slow Gait Speed in Patients with Liver Cirrhosis

Branched-chain amino acid (BCAA) and insulin-like growth factor 1 (IGF-1) are essential for muscle protein synthesis. We investigated the association of serum BCAA and IGF-1 levels with sarcopenia and gait speed in 192 patients with liver cirrhosis (LC). Sarcopenia was diagnosed according to the Japan Society of Hepatology criteria. Slow gait speed was defined as <1.0 m/s. Subjects were divided into three groups based on baseline BCAA or IGF-1 levels: low (L), intermediate (I), and high (H) groups. The L-BCAA group had the highest prevalence of sarcopenia (60.4%, p < 0.001) and slow gait speed (56.3%, p = 0.008), whereas the H-BCAA group had the lowest prevalence of sarcopenia (8.5%, p < 0.001). The L-IGF-1 group showed the highest prevalence of sarcopenia (46.9%, p < 0.001), whereas the H-IGF-1 group had the lowest prevalence of sarcopenia (10.0%, p < 0.001) and slow gait speed (18.0%, p = 0.003). Using the optimal BCAA and IGF-1 cutoff values for predicting sarcopenia (372 μmol/L and 48.5 ng/mL, respectively), the sensitivity and specificity were 0.709 and 0.759 for BCAA and 0.636 and 0.715 for IGF-1, respectively. Low serum BCAA and IGF-1 levels were associated with sarcopenia and slow gait speed in patients with LC.

Plasma Metabolome Alterations Associated with Extrauterine Growth Restriction

Very preterm infants (VPI, born at or before 32 weeks of gestation) are at risk of adverse health outcomes, from which they might be partially protected with appropriate postnatal nutrition and growth. Metabolic processes or biochemical markers associated to extrauterine growth restriction (EUGR) have not been identified. We applied untargeted metabolomics to plasma samples of VPI with adequate weight for gestational age at birth and with different growth trajectories (29 well-grown, 22 EUGR) at the time of hospital discharge. A multivariate analysis showed significantly higher levels of amino-acids in well-grown patients. Other metabolites were also identified as statistically significant in the comparison between groups. Relevant differences (with corrections for multiple comparison) were found in levels of glycerophospholipids, sphingolipids and other lipids. Levels of many of the biochemical species decreased progressively as the level of growth restriction increased in severity. In conclusion, an untargeted metabolomic approach uncovered previously unknown differences in the levels of a range of plasma metabolites between well grown and EUGR infants at the time of discharge. Our findings open speculation about pathways involved in growth failure in preterm infants and the long-term relevance of this metabolic differences, as well as helping in the definition of potential biomarkers.

Synergistic effect of bodyweight resistance exercise and protein supplementation on skeletal muscle in sarcopenic or dynapenic older adults

AIM

The objective of this trial was to investigate the synergistic effects of bodyweight resistance exercise and a protein supplement with vitamin D on skeletal muscle in sarcopenic or dynapenic older adults.

METHODS

This was a four-arm randomized controlled trial. Sarcopenic or dynapenic older adults were recruited for this trial. After screening, a total of 112 older adults were randomly allocated among four groups; 28 older adults each were enrolled in the combined resistance exercise and nutritional supplementation group, the exercise alone group, the nutritional supplementation alone group, and the control group. Participants in the combined group and exercise alone groups took part in a bodyweight resistance exercise program for 12 weeks. Protein and vitamin D supplements were provided every day for 12 weeks for the participants in the combined group and nutritional supplementation alone groups. We assessed the echo intensity of participants' thigh muscle using ultrasonography, measured their appendicular muscle mass using a bioelectrical impedance data acquisition system, and tested their knee extension strength and physical function.

RESULTS

Participants in the combined group had a significantly greater improvement in rectus femoris echo intensity and knee extension torque than those in the other groups (P < 0.05). Furthermore, the combined program increased appendicular muscle mass in sarcopenic older adults (P < 0.05), but not in older adults with low physical function with normal muscle mass.

CONCLUSIONS

The present study confirmed the synergistic effect of bodyweight resistance exercise and protein supplement with vitamin D on muscle quality and muscle strength in sarcopenic or dynapenic older adults. Geriatr Gerontol Int 2019; 19: 429-437.

Phase Angle Is a Useful indicator for Muscle Function in Older Adults

AIM

Phase angle (PhA) can be determined through bioelectrical impedance analysis and is a unique variable for skeletal muscle. The objective of this study was to evaluate the relationship between PhA and muscle mass/quality in older adults. In addition, we attempted to determine the cutoff value of PhA for poor muscle function.

METHODS

Community-dwelling Japanese older men (n=285, 81.1±7.1 years) and women (n=724, 80.4±6.8 years) participated in this study and were classified into four groups based on the Asian Working Group for Sarcopenia (normal, presarcopenia, dynapenia, and sarcopenia). We measured PhA using bioelectrical impedance analysis, muscle quantity and quality indicators using ultrasonography, muscle strength, and physical performance and compared them in four groups. We also tried to determine the cutoff value of PhA for poor muscle function.

RESULTS

We found a significant difference in PhA among the four groups in men (P<0.05), and the dynapenia (3.61±0.75°) and sarcopenia groups (3.40±0.74°) showed significantly lower values than the normal group (4.50±0.86°) (P<0.05), but not the presarcopenia group (4.12±0.85°). In women, a significant difference was also observed among the four groups (P<0.05), and the dynapenia (3.41±0.65°) and sarcopenia groups (3.31±0.66°) showed significantly lower measures than the normal group (4.14±0.71°) (P<0.05), but not the presarcopenia group (4.07±0.51°). The receiver-operating characteristic curve analysis indicated the best cutoff value of PhA (men: 4.05°, women: 3.55°) to discriminate sarcopenia and dynapenia from normal and presarcopenia.

CONCLUSION

These findings suggest that PhA is a useful indicator for muscle function.