Age-induced oxidative stress: how does it influence skeletal muscle quantity and quality?

Inducible and reversible SOD2 knockdown in mouse skeletal muscle drives impaired pyruvate oxidation and reduced metabolic flexibility

INTRODUCTION

Skeletal muscle mitochondrial dysfunction is a key characteristic of aging muscle and contributes to age related diseases such as sarcopenia, frailty, and type 2 diabetes. Mitochondrial oxidative stress has been implicated as a driving factor in these age-related diseases, however whether it is a cause, or a consequence of mitochondrial dysfunction remains to be determined. The development of flexible genetic models is an important tool to test the mechanistic role of mitochondrial oxidative stress on skeletal muscle metabolic dysfunction. We characterize a new model of inducible and reversible mitochondrial redox stress using a tetracycline controlled skeletal muscle specific short hairpin RNA targeted to superoxide dismutase 2 (iSOD2).

METHODS

iSOD2 KD and control (CON) animals were administered doxycycline for 3- or 12- weeks and followed for up to 24 weeks and mitochondrial respiration and muscle contraction were measured to define the time course of SOD2 KD and muscle functional changes and recovery.

RESULTS

Maximum knockdown of SOD2 protein occurred by 6 weeks and recovered by 24 weeks after DOX treatment. Mitochondrial aconitase activity and maximum mitochondrial respiration declined in KD muscle by 12 weeks and recovered by 24 weeks. There were no significant differences in antioxidant or mitochondrial biogenesis genes between groups. Twelve-week KD showed a small, but significant decrease in muscle fatigue resistance. The primary phenotype was reduced metabolic flexibility characterized by impaired pyruvate driven respiration when other substrates are present. The pyruvate dehydrogenase kinase inhibitor dichloroacetate partially restored pyruvate driven respiration, while the thiol reductant DTT did not.

CONCLUSION

We use a model of inducible and reversible skeletal muscle SOD2 knockdown to demonstrate that elevated matrix superoxide reversibly impairs mitochondrial substrate flexibility characterized by impaired pyruvate oxidation. Despite the bioenergetic effect, the limited change in gene expression suggests that the elevated redox stress in this model is confined to the mitochondrial matrix.

Aging impaired locomotor and biochemical activities in Drosophila melanogaster Oregon R (fruit fly) model

Despite advancements in healthcare and increased lifespan, aging populations face numerous challenges, including declining cognitive function, increased susceptibility to chronic diseases, and reduced quality of life. This study investigated Aging impaired Locomotors and Biochemical Activities in Drosophila melanogaster Oregon R (Fruit Fly) Model with the aim to elucidate the mechanism involved. Adult wild-type Drosophila melanogaster Oregon R was used for this study. Survival assay, antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and malondialdehyde (MDA)) and total protein (TP) concentration were investigated. Data obtained were analyzed using R studio and GraphPad Prism. The result indicated low survival in male flies compared to female flies and the highest survival rate was observed with both flies reared together in the same vial. There was impaired locomotor activity in the flies with age. There was a significant decrease in the level of SOD, CAT, GSH and TP with age with a corresponding significant increase in the level of MDA. This finding demonstrated that locomotor activity decreased with aging with decrease performance index and also established the involvement of oxidation through the activities of antioxidant enzymes in aging; decreased (p < 0.05) concentration of antioxidant enzymes and increased (p < 0.05) lipid peroxidation. Also, it demonstrated that female species had longer lifespan compared to males while co-habiting of male and female species extended lifespan.

Association between the composite dietary antioxidant index and sarcopenia among United States adults: A cross-sectional study

BACKGROUND

Diets high in antioxidants are associated with decreased prevalence of sarcopenia. This study aimed to investigate whether the composite dietary antioxidant index (CDAI) and sarcopenia have an underlying relationship.

METHODS

We used the data from the National Health and Nutrition Examination Survey 2011-2018. According to dietary antioxidant intake, the CDAI was calculated for each individual. Appendicular skeletal muscle mass index was employed to determine sarcopenia. Multivariate weighted logistic models and restricted cubic spline regression analysis was undertaken to determine the association between CDAI and sarcopenia.

RESULTS

A total of 7012 participants were enrolled in this study, including 473 with sarcopenia (weighted percentage, 5.6%). Compared with the lowest tertile, those in the highest tertile of the CDAI exhibited a greater likelihood of being male, with lower body mass index, higher education level and economic standard, and more chance of being single or separated. In multivariate weighted logistic models, model 3 revealed a noteworthy inverse association between the CDAI and sarcopenia (odds ratio = 0.94; 95% CI, 0.91-0.98; P = 0.003). Compared with the lowest tertile, the highest tertile of CDAI was associated with a 0.57-fold risk of sarcopenia (95% CI, 0.42-0.77; P < 0.001). The inverse association between CDAI and sarcopenia strengthened in the participants with elevated education levels (P for interaction = 0.003).

CONCLUSION

The CDAI was inversely correlated with the prevalence of sarcopenia. As a comprehensive measurement representing antioxidant status, the CDAI may help manage and prevent sarcopenia.

Decreased grip strength is associated with paraspinal muscular oxidative stress in female lumbar degenerative disease patients

We aimed to investigate the relationship between superoxide dismutase 2-related oxidative stress in the paraspinal muscles and spinal alignment, clinical skeletal muscle parameters, and mitochondrial function. Multifidus muscle samples from patients who underwent posterior lumbar surgery were analyzed. Patients with diseases affecting oxidative stress and spinal alignment were excluded. The superoxide dismutase 2 redox index was defined as the ratio of reactive oxygen species (superoxide) to antioxidant enzymes (superoxide dismutase 2) and was used as an index of oxidative stress. Patients were divided into two groups based on the superoxide dismutase 2 redox index. Spinal alignment, clinical skeletal muscle parameters, and succinic dehydrogenase (SDH) mean grayscale value were compared between the groups, with analyzes for both sexes. Multiple regression analyzes were used to adjust for the confounding effect of age on variables showing a significant difference between the two groups. Thirty-five patients with lumbar degenerative diseases were included. No significant differences were observed between the two groups for any of the parameters in males; however, females with a higher superoxide dismutase 2 redox index had greater lumbar lordosis, lower grip strength, and higher SDH mean grayscale value than those with a lower index. Multiple regression analyzes revealed that the superoxide dismutase 2 redox index was an independent explanatory variable for lumbar lordosis, grip strength, and SDH mean grayscale value in female patients. In conclusion, superoxide dismutase 2-related oxidative stress in the paraspinal muscles was associated with mitochondrial dysfunction and decreased grip strength in female lumbar degenerative disease patients.

Inducible and reversible SOD2 knockdown in mouse skeletal muscle drives impaired pyruvate oxidation and reduced metabolic flexibility

Introduction

Skeletal muscle mitochondrial dysfunction is a key characteristic of aging muscle and contributes to age related diseases such as sarcopenia, frailty, and type 2 diabetes. Mitochondrial oxidative distress has been implicated as a driving factor in these age-related diseases, however whether it is a cause, or a consequence of mitochondrial dysfunction remains to be determined. The development of more flexible genetic models is an important tool to test the mechanistic role of mitochondrial oxidative stress on skeletal muscle metabolic dysfunction. We characterize a new model of inducible and reversible mitochondrial redox stress using a tetracycline controlled skeletal muscle specific short hairpin RNA targeted to superoxide dismutase 2 (iSOD2).

Methods

iSOD2 KD and control (CON) animals were administered doxycycline for 3- or 12- weeks and followed for up to 24 weeks and mitochondrial respiration and muscle contraction were measured to define the time course of SOD2 KD and muscle functional changes and recovery.

Results

Maximum knockdown of SOD2 protein occurred by 6 weeks and recovered by 24 weeks after DOX treatment. Mitochondrial aconitase activity and maximum mitochondrial respiration declined in KD muscle by 12 weeks and recovered by 24 weeks. There were minimal changes in gene expression between KD and CON muscle. Twelve-week KD showed a small, but significant decrease in muscle fatigue resistance. The primary phenotype was reduced metabolic flexibility characterized by impaired pyruvate driven respiration when other substrates are present. The pyruvate dehydrogenase kinase inhibitor dichloroacetate partially restored pyruvate driven respiration, while the thiol reductant DTT did not.

Conclusion

We use a model of inducible and reversible skeletal muscle SOD2 knockdown to demonstrate that elevated matrix superoxide reversibly impairs mitochondrial substrate flexibility characterized by impaired pyruvate oxidation. Despite the bioenergetic effect, the limited change in gene expression suggests that the elevated redox stress in this model is confined to the mitochondrial matrix.

Unveiling frailty: comprehensive and sex-specific characterization in prematurely aging PolgA mice

Frailty, a geriatric syndrome, is assessed using the frailty phenotype (FP) and frailty index (FI). While these approaches have been applied to aging mice, their effectiveness in prematurely aging mouse models such as PolgAD257A/D257A (PolgA) has not been completely explored. We demonstrated that frailty became evident in PolgA mice around 40 weeks, validated through body weight loss, reduced walking speed, decreased physical activity, and weaker grip strength. Moreover, we also identified sex differences in these mice with females exhibiting slightly more physical decline compared to males. Frailty prevalence in PolgA mice at 40 weeks parallels that observed in naturally aging mice at 27 months and aging humans at 65-70 years. These findings contribute to understanding frailty onset and sex-specific patterns in this prematurely aging mouse model, emphasizing the significance of the PolgA mouse model in investigating aging and related disorders.

Branched-chain amino acids and L-alanine supplementation ameliorate calcium dyshomeostasis in sarcopenia: New insights for nutritional interventions

Introduction: During aging, sarcopenia and decline in physiological processes lead to partial loss of muscle strength, atrophy, and increased fatigability. Muscle changes may be related to a reduced intake of essential amino acids playing a role in proteostasis. We have recently shown that branched-chain amino acid (BCAA) supplements improve atrophy and weakness in models of muscle disuse and aging. Considering the key roles that the alteration of Ca2+-related homeostasis and store-operated calcium entry (SOCE) play in several muscle dysfunctions, this study has been aimed at gaining insight into the potential ability of BCAA-based dietary formulations in aged mice on various players of Ca2+ dyshomeostasis. Methods: Seventeen-month-old male C57BL/6J mice received a 12-week supplementation with BCAAs alone or boosted with two equivalents of L-alanine (2-Ala) or with dipeptide L-alanyl-L-alanine (Di-Ala) in drinking water. Outcomes were evaluated on ex vivo skeletal muscles indices vs. adult 3-month-old male C57BL/6J mice. Results: Ca2+ imaging confirmed a decrease in SOCE and an increase of resting Ca2+ concentration in aged vs. adult mice without alteration in the canonical components of SOCE. Aged muscles vs. adult muscles were characterized by a decrease in the expression of ryanodine receptor 1 (RyR1), the Sarco-Endoplasmic Reticulum Calcium ATPase (SERCA) pump, and sarcalumenin together with an alteration of the expression of mitsugumin 29 and mitsugumin 53, two recently recognized players in the SOCE mechanism. BCAAs, particularly the formulation BCAAs+2-Ala, were able to ameliorate all these alterations. Discussion: These results provide evidence that Ca2+ homeostasis dysfunction plays a role in the functional deficit observed in aged muscle and supports the interest of dietary BCAA supplementation in counteracting sarcopenia-related SOCE dysregulation.

Mouse sarcopenia model reveals sex- and age-specific differences in phenotypic and molecular characteristics

Our study was to characterize sarcopenia in C57BL/6J mice using a clinically relevant definition to investigate the underlying molecular mechanisms. Aged male (23-32 months old) and female (27-28 months old) C57BL/6J mice were classified as non-, probable-, or sarcopenic based on assessments of grip strength, muscle mass, and treadmill running time, using 2 SDs below the mean of their young counterparts as cutoff points. A 9%-22% prevalence of sarcopenia was identified in 23-26 month-old male mice, with more severe age-related declines in muscle function than mass. Females aged 27-28 months showed fewer sarcopenic but more probable cases compared with the males. As sarcopenia progressed, a decrease in muscle contractility and a trend toward lower type IIB fiber size were observed in males. Mitochondrial biogenesis, oxidative capacity, and AMPK-autophagy signaling decreased as sarcopenia progressed in males, with pathways linked to mitochondrial metabolism positively correlated with muscle mass. No age- or sarcopenia-related changes were observed in mitochondrial biogenesis, OXPHOS complexes, AMPK signaling, mitophagy, or atrogenes in females. Our results highlight the different trajectories of age-related declines in muscle mass and function, providing insights into sex-dependent molecular changes associated with sarcopenia progression, which may inform the future development of novel therapeutic interventions.

Expression of mitochondrial oxidative stress response genes in muscle is associated with mitochondrial respiration, physical performance, and muscle mass in the Study of Muscle, Mobility, and Aging

Gene expression in skeletal muscle of older individuals may reflect compensatory adaptations in response to oxidative damage that preserve tissue integrity and maintain function. Identifying associations between oxidative stress response gene expression patterns and mitochondrial function, physical performance, and muscle mass in older individuals would further our knowledge of mechanisms related to managing molecular damage that may be targeted to preserve physical resilience. To characterize expression patterns of genes responsible for the oxidative stress response, RNA was extracted and sequenced from skeletal muscle biopsies collected from 575 participants (≥70 years old) from the Study of Muscle, Mobility, and Aging. Expression levels of 21 protein-coding RNAs related to the oxidative stress response were analyzed in relation to six phenotypic measures, including maximal mitochondrial respiration from muscle biopsies (Max OXPHOS), physical performance (VO2 peak, 400-m walking speed, and leg strength), and muscle size (thigh muscle volume and whole-body D3Cr muscle mass). The mRNA level of the oxidative stress response genes most consistently associated across outcomes are preferentially expressed within the mitochondria. Higher expression of mRNAs that encode generally mitochondria located proteins SOD2, TRX2, PRX3, PRX5, and GRX2 were associated with higher levels of mitochondrial respiration and VO2 peak. In addition, greater SOD2, PRX3, and GRX2 expression was associated with higher physical performance and muscle size. Identifying specific mechanisms associated with high functioning across multiple performance and physical domains may lead to targeted antioxidant interventions with greater impacts on mobility and independence.

Biomarkers of frailty

Several biomarkers have been proposed to identify frailty, a multisystemic age-related syndrome. However, the complex pathophysiology and the absence of a consensus on a comprehensive and universal definition make it challenging to pinpoint a singular biomarker or set of biomarkers that conclusively characterize frailty. This review delves into the main laboratory biomarkers, placing special emphasis on those associated with various pathways closely tied to the frailty condition, such as inflammation, oxidative stress, mitochondrial dysfunction, metabolic and endocrine alterations and microRNA. Additionally, we provide a summary of different clinical biomarkers encompassing different tools that have been proposed to assess frailty. We further address various imaging biomarkers such as Dual Energy X-ray Absorptiometry, Bioelectrical Impedance analysis, Computed Tomography and Magnetic Resonance Imaging, Ultrasound and D3 Creatine dilution. Intervention to treat frailty, including non-pharmacological ones, especially those involving physical exercise and nutrition, and pharmacological interventions, that include those targeting specific mechanisms such as myostatin inhibitors, insulin sensitizer metformin and with special relevance for hormonal treatments are mentioned. We further address the levels of different biomarkers in monitoring the potential positive effects of some of these interventions. Despite the availability of numerous biomarkers, their performance and usefulness in the clinical arena are far from being satisfactory. Considering the multicausality of frailty, there is an increasing need to assess the role of sets of biomarkers and the combination between laboratory, clinical and image biomarkers, in terms of sensitivity, specificity and predictive values for the diagnosis and prognosis of the different outcomes of frailty to improve detection and monitoring of older people with frailty or at risk of developing it, being this a need in the everyday clinical practice.

Effects of a ketogenic diet on motor function and motor unit number estimation in aged C57BL/6 mice

OBJECTIVE

Pathological, age-related loss of muscle function, commonly referred to as sarcopenia, contributes to loss of mobility, impaired independence, as well as increased risk of adverse health events. Sarcopenia has been attributed to changes in both neural and muscular integrity during aging. Current treatment options are primarily limited to exercise and dietary protein fortification, but the therapeutic impact of these approaches are often inadequate. Prior work has suggested that a ketogenic diet (KD) might improve healthspan and lifespan in aging mice. Thus, we sought to investigate the effects of a KD on neuromuscular indices of sarcopenia in aged C57BL/6 mice.

DESIGN

A randomized, controlled pre-clinical experiment consisting of longitudinal assessments performed starting at 22-months of age (baseline) as well as 2, 6 and 10 weeks after the start of a KD vs. regular chow intervention.

SETTING

Preclinical laboratory study.

SAMPLE SIZE

Thirty-six 22-month-old mice were randomized into 2 dietary groups: KD [n = 22 (13 female and 9 male)], and regular chow [n = 15 (7 female and 8 male)].

MEASUREMENTS

Measures included body mass, hindlimb and all limb grip strength, rotarod for motor performance, plantarflexion muscle contractility, motor unit number estimations (MUNE), and repetitive nerve stimulation (RNS) as an index of neuromuscular junction transmission efficacy recorded from the gastrocnemius muscle. At end point, muscle wet weight and blood samples were collected to assess blood beta-hydroxybutyrate levels.

STATISTICAL ANALYSIS

Primary analyses were two-way mixed effects ANOVA (diet and time × diet) to determine the effect of a KD on indices of motor function (grip, rotarod) and indices of motor unit (MUNE) and muscle (contractility) function.

RESULTS

Beta-hydroxybutyrate (BHB) was significantly higher at 10 weeks in mice on a KD vs control group (0.83 ± 0.44 mmol/l versus 0.42 ± 0.21 mmol/l, η2 = 0.265, unpaired t-test, p = 0.0060). Mice on the KD intervention demonstrated significantly increased hindlimb grip strength (diet, p = 0.0001; time × diet, p = 0.0030), all limb grip strength (diet, p = 0.0005; time × diet, p = 0.0523), and rotarod latency to fall (diet, p = 0.0126; time × diet, p = 0.0021). Mice treated with the KD intervention also demonstrated increased MUNE (diet, p = 0.0465; time × diet, p = 0.0064), but no difference in muscle contractility (diet, p = 0.5248; time × diet, p = 0.5836) or RNS (diet, p = 0.3562; time × diet, p = 0.9871).

CONCLUSION

KD intervention improved neuromuscular and motor function in aged mice. This pre-clinical work suggests that further research is needed to assess the efficacy and physiological effects of a KD on indices of sarcopenia.

How soon do metabolic alterations and oxidative distress precede the reduction of muscle mass and strength in Wistar rats in aging process?

Here we investigate metabolic changes, the antioxidant system and the accumulation of oxidative damage in muscles with different fiber types during the aging process in Wistar rats and try to map how sooner the changes occur. To do so, 30 male Wistar rats were submitted to behavioral evaluation to determine voluntary strength in the 11, 15, and 19 month old rats, measuring the energy metabolism, antioxidant system, oxidative damage and structure in the soleus and extensor digitorum longus muscles. We detected structural and metabolic changes in both muscles, especially in the EDL of 15 month old rats and in the soleus of 19 month old rats. In the 15 month old rats, there was a reduction in the cross-sectional area of the fibers, and a reduction in the proportion of type I fibers, accompanied by an increase in fiber density and the amount of type IIA fibers. This change in the fiber profile was followed by an increase in the activity of anaerobic metabolism enzymes, suggesting a reduction in the oxidative capacity of the muscle. In addition, there was an increase in the rate of lipid peroxidation, accompanied by a reduced antioxidant capacity. In the 19 month old rats, these disturbances got stronger. In summary, the present study demonstrated that before functional disturbances, there was an accumulation of oxidative damage and structural changes in the skeletal muscle beginning at 15 months old in the EDL and the soleus only in the biochemical parameters. Therefore, the metabolic alterations occurred at 15 months old and not before.

Aging-affiliated post-translational modifications of skeletal muscle myosin affect biochemical properties, myofibril structure, muscle function, and proteostasis

The molecular motor myosin is post-translationally modified in its globular head, its S2 hinge, and its thick filament domain during human skeletal muscle aging. To determine the importance of such modifications, we performed an integrative analysis of transgenic Drosophila melanogaster expressing myosin containing post-translational modification mimic mutations. We determined effects on muscle function, myofibril structure, and myosin biochemistry. Modifications in the homozygous state decreased jump muscle function by a third at 3 weeks of age and reduced indirect flight muscle function to negligible levels in young flies, with severe effects on flight muscle myofibril assembly and/or maintenance. Expression of mimic mutations in the heterozygous state or in a wild-type background yielded significant, but less severe, age-dependent effects upon flight muscle structure and function. Modification of the residue in the globular head disabled ATPase activity and in vitro actin filament motility, whereas the S2 hinge mutation reduced actin-activated ATPase activity by 30%. The rod modification diminished filament formation in vitro. The latter mutation also reduced proteostasis, as demonstrated by enhanced accumulation of polyubiquitinated proteins. Overall, we find that mutation of amino acids at sites that are chemically modified during human skeletal muscle aging can disrupt myosin ATPase, myosin filament formation, and/or proteostasis, providing a mechanistic basis for the observed muscle defects. We conclude that age-specific post-translational modifications present in human skeletal muscle are likely to act in a dominant fashion to affect muscle structure and function and may therefore be implicated in degeneration and dysfunction associated with sarcopenia.

Uremia Impedes Skeletal Myocyte Myomixer Expression and Fusogenic Activity: Implication for Uremic Sarcopenia

In patients with chronic kidney disease (CKD), skeletal muscle mass and function are known to occasionally decline. However, the muscle regeneration and differentiation process in uremia has not been extensively studied. In mice with CKD induced by adenine-containing diet, the tibialis anterior muscle injured using a barium chloride injection method recovered poorly as compared to control mice. In the cultured murine skeletal myocytes, stimulation with indoxyl sulfate (IS), a representative uremic toxin, morphologically jeopardized the differentiation, which was counteracted by L-ascorbic acid (L-AsA) treatment. Transcriptome analysis of cultured myocytes identified a set of genes whose expression was down-regulated by IS stimulation but up-regulated by L-AsA treatment. Gene silencing of myomixer, one of the genes in the set, impaired myocyte fusion during differentiation. By contrast, lentiviral overexpression of myomixer compensated for a hypomorphic phenotype caused by IS treatment. The split-luciferase technique demonstrated that IS stimulation negatively affected early myofusion activity that was rescued by L-AsA treatment. Lastly, in mice with CKD compared with control mice, myomixer expression in the muscle tissue in addition to the muscle weight after the injury was reduced, both of which were restored with L-AsA treatment. Collectively, data showed that the uremic milieu impairs the expression of myomixer and impedes the myofusion process. Considering frequent musculoskeletal injuries in uremic patients, defective myocyte fusion followed by delayed muscle damage recovery could underlie their muscle loss and weakness.

Azilsartan prevents muscle loss and fast- to slow-twitch muscle fiber shift in natural ageing sarcopenic rats

Sarcopenia is a musculoskeletal disease that reduces muscle mass and strength in older individuals. The study investigates the effects of azilsartan (AZL) on skeletal muscle loss in natural sarcopenic rats. Male Sprague-Dawley rats aged 4-6 months and 18-21 months were selected as young-matched control and natural-aged (sarcopenic) rats, respectively. Rats were allocated into young and old control (YC and OC) and young and old AZL treatment (YT and OT) groups, which received vehicles and AZL (8 mg/kg, orally) for 6 weeks. Rats were then sacrificed after muscle function analysis. Serum and gastrocnemius (GN) muscles were isolated for further endpoints. AZL significantly improved muscle grip strength and antioxidant levels in sarcopenic rats. AZL also restored the levels of insulin, testosterone, and muscle biomarkers such as myostatin and creatinine kinase in sarcopenic rats. Furthermore, AZL treatment improved the cellular and ultrastructure of GN muscle and prevented the shift of type II (glycolytic) myofibers to type I (oxidative) myofibers. The results showed that AZL intervention restored protein synthesis in natural sarcopenic rats by increasing p-Akt-1 and decreasing muscle RING-finger protein-1 and tumor necrosis factor alpha immunoexpressions. In conclusion, the present findings showed that AZL could be an effective intervention in treating age-related muscle impairments.

Exercise-Induced Transient Oxidative Stress Is Mitigated in Down Syndrome: Insights About Redox Balance and Muscle Strength

ABSTRACT

Reis, AL, Deus, LA, Neves, RVP, Corrêa, HL Reis, TL, Aguiar, LS Honorato, FS, Barbosa, JMS, Araújo, TB, Palmeira, TRC, Simões, HG, Prestes, J, Sousa, CV, Ide, BN, and Rosa, TdS. Exercise-induced transient oxidative stress is mitigated in Down syndrome: insights about redox balance and muscle strength. J Strength Cond Res 38(3): e125-e34, 2024-This study aimed to evaluate the acute effects of a session of resistance exercise (RE) performed with elastic tubes on the redox balance and inflammatory profile in individuals with Down syndrome (DS). Subjects ( n = 23) were allocated into 2 groups: individuals with DS (DS; n = 11) and individuals without DS (WDS; n = 12), who performed an acute RE session. Diagnostic assessment included medical history, anthropometric measures (body height, body mass, body mass index, and body composition assessment), biological collections, muscle strength assessments (handgrip and maximal voluntary isometric contraction tests), and exercises. The redox balance and inflammatory profile were assessed in urine and saliva samples before and after an acute RE session. There were no differences between WDS and DS groups for body composition ( p > 0.05). The DS group presented higher values pre and post an acute RE session with elastic tubes for oxidative and proinflammatory markers compared with WDS ( p < 0.05). Uric acid values increased from pre-acute RE session to post-acute RE session for WDS ( p < 0.0001). No differences were identified within groups for the delta analysis ( p > 0.05). Inverse correlations were found between total force and F2-isoprostane, 8OHdG, uric acid, allantoin, IL-6, TNF-α, and the TNF-α:IL-10 ratio. A positive correlation was found between IL-10 and total force. The DS group presented increased peak force in the knee extension and elbow flexion exercises (∼25 and 12%, respectively) but decreases in handgrip strength of ∼7%. The WDS group showed higher peak force values for knee extension, elbow flexion, and handgrip (∼16, 10, and 14%, respectively). The DS group had lower transient elevation of oxidative stress after an acute RE session compared with WDS. Oxidative stress and inflammation responses of DS to an acute RE session with elastic tubes may be insufficient to induce health adaptations for the same relative load compared with WDS.

Mitochondrial involvement in sarcopenia

Sarcopenia lowers the quality-of-life for millions of people across the world, as accelerated loss of skeletal muscle mass and function contributes to both age- and disease-related frailty. Physical activity remains the only proven therapy for sarcopenia to date, but alternatives are much sought after to manage this progressive muscle disorder in individuals who are unable to exercise. Mitochondria have been widely implicated in the etiology of sarcopenia and are increasingly suggested as attractive therapeutic targets to help restore the perturbed balance between protein synthesis and breakdown that underpins skeletal muscle atrophy. Reviewing current literature, we note that mitochondrial bioenergetic changes in sarcopenia are generally interpreted as intrinsic dysfunction that renders muscle cells incapable of making sufficient ATP to fuel protein synthesis. Based on the reported mitochondrial effects of therapeutic interventions, however, we argue that the observed bioenergetic changes may instead reflect an adaptation to pathologically decreased energy expenditure in sarcopenic muscle. Discrimination between these mechanistic possibilities will be crucial for improving the management of sarcopenia.

Zebrafish and cellular models of SELENON-Related Myopathy exhibit novel embryonic and metabolic phenotypes

SELENON-Related Myopathy (SELENON-RM) is a rare congenital myopathy caused by mutations of the SELENON gene characterized by axial muscle weakness and progressive respiratory insufficiency. Muscle histopathology commonly includes multiminicores or a dystrophic pattern but is often non-specific. The SELENON gene encodes selenoprotein N (SelN), a selenocysteine-containing redox enzyme located in the endo/sarcoplasmic reticulum membrane where it colocalizes with mitochondria-associated membranes. However, the molecular mechanism(s) by which SelN deficiency causes SELENON-RM are undetermined. A hurdle is the lack of cellular and animal models that show assayable phenotypes. Here we report deep-phenotyping of SelN-deficient zebrafish and muscle cells. SelN-deficient zebrafish exhibit changes in embryonic muscle function and swimming activity in larvae. Analysis of single cell RNAseq data in a zebrafish embryo-atlas revealed coexpression between selenon and genes involved in glutathione redox pathway. SelN-deficient zebrafish and mouse myoblasts exhibit changes in glutathione and redox homeostasis, suggesting a direct relationship with SelN function. We report changes in metabolic function abnormalities in SelN-null myotubes when compared to WT. These results suggest that SelN has functional roles during zebrafish early development and myoblast metabolism.

Low handgrip strength is associated with worse functional outcomes in long COVID

The diagnosis of long COVID is troublesome, even when functional limitations are present. Dynapenia is the loss of muscle strength and power production that is not caused by neurologic or muscular diseases, being mostly associated with changes in neurologic function and/or the intrinsic force-generating properties of skeletal muscle, which altogether, may partially explain the limitations seen in long COVID. This study aimed to identify the distribution and possible associations of dynapenia with functional assessments in patients with long COVID. A total of 113 patients with COVID-19 were evaluated by functional assessment 120 days post-acute severe disease. Body composition, respiratory muscle strength, spirometry, six-minute walk test (6MWT, meters), and hand-grip strength (HGS, Kilogram-force) were assessed. Dynapenia was defined as HGS < 30 Kgf (men), and < 20 Kgf (women). Twenty-five (22%) participants were dynapenic, presenting lower muscle mass (p < 0.001), worse forced expiratory volume in the first second (FEV1) (p = 0.0001), lower forced vital capacity (p < 0.001), and inspiratory (p = 0.007) and expiratory (p = 0.002) peek pressures, as well as worse 6MWT performance (p < 0.001). Dynapenia, independently of age, was associated with worse FEV1, maximal expiratory pressure (MEP), and 6MWT, (p < 0.001) outcomes. Patients with dynapenia had higher intensive care unit (ICU) admission rates (p = 0.01) and need for invasive mechanical ventilation (p = 0.007) during hospitalization. The HGS is a simple, reliable, and low-cost measurement that can be performed in outpatient clinics in low- and middle-income countries. Thus, HGS may be used as a proxy indicator of functional impairment in this population.

Mouse models of accelerated aging in musculoskeletal research for assessing frailty, sarcopenia, and osteoporosis - A review

Musculoskeletal aging encompasses the decline in bone and muscle function, leading to conditions such as frailty, osteoporosis, and sarcopenia. Unraveling the underlying molecular mechanisms and developing effective treatments are crucial for improving the quality of life for those affected. In this context, accelerated aging models offer valuable insights into these conditions by displaying the hallmarks of human aging. Herein, this review focuses on relevant mouse models of musculoskeletal aging with particular emphasis on frailty, osteoporosis, and sarcopenia. Among the discussed models, PolgA mice in particular exhibit hallmarks of musculoskeletal aging, presenting early-onset frailty, as well as reduced bone and muscle mass that closely resemble human musculoskeletal aging. Ultimately, findings from these models hold promise for advancing interventions targeted at age-related musculoskeletal disorders, effectively addressing the challenges posed by musculoskeletal aging and associated conditions in humans.

Expression of mitochondrial oxidative stress response genes in muscle is associated with mitochondrial respiration, physical performance, and muscle mass in the Study of Muscle, Mobility and Aging (SOMMA)

Gene expression in skeletal muscle of older individuals may reflect compensatory adaptations in response to oxidative damage that preserve tissue integrity and maintain function. Identifying associations between oxidative stress response gene expression patterns and mitochondrial function, physical performance, and muscle mass in older individuals would further our knowledge of mechanisms related to managing molecular damage that may be targeted to preserve physical resilience. To characterize expression patterns of genes responsible for the oxidative stress response, RNA was extracted and sequenced from skeletal muscle biopsies collected from 575 participants (≥70 years old) from the Study of Muscle, Mobility and Aging. Expression levels of twenty-one protein coding RNAs related to the oxidative stress response were analyzed in relation to six phenotypic measures, including: maximal mitochondrial respiration from muscle biopsies (Max OXPHOS), physical performance (VO2 peak, 400m walking speed, and leg strength), and muscle size (thigh muscle volume and whole-body D3Cr muscle mass). The mRNA level of the oxidative stress response genes most consistently associated across outcomes are preferentially expressed within the mitochondria. Higher expression of mRNAs that encode generally mitochondria located proteins SOD2, TRX2, PRX3, PRX5, and GRX2 were associated with higher levels of mitochondrial respiration and VO2 peak. In addition, greater SOD2, PRX3, and GRX2 expression was associated with higher physical performance and muscle size. Identifying specific mechanisms associated with high functioning across multiple performance and physical domains may lead to targeted antioxidant interventions with greater impacts on mobility and independence.

Dehydroepiandrosterone Sulfate, an Adrenal Androgen, Is Inversely Associated with Prevalence of Dynapenia in Male Individuals with Type 2 Diabetes

Dehydroepiandrosterone sulfate (DHEAS) is thought to be associated with life expectancy and anti-aging. Although skeletal muscle disorders are often found in diabetic people, the clinical significance of DHEAS in skeletal muscle remains unclear. Therefore, we aimed to determine whether DHEAS is associated with the development of skeletal muscle disorders in individuals with type 2 diabetes (T2D). A cross-sectional study was conducted in 361 individuals with T2D. Serum DHEAS levels, skeletal muscle mass index (SMI), handgrip strength (HS), and gait speed (GS) were measured in the participants. Pre-sarcopenia, sarcopenia, and dynapenia were defined according to the definitions of the AWGS 2019 criteria. DHEAS level was positively associated with HS but not with SMI or GS after adjustment of confounding factors. Multiple logistic regression analyses in total subjects showed that DHEAS level had an inverse association with the prevalence of dynapenia but not with the prevalence of pre-sarcopenia or sarcopenia. Furthermore, a significant association between DHEAS level and dynapenia was found in males but not in females. ROC curve analysis indicated that cutoff values of serum DHEAS for risk of dynapenia in males was 92.0 μg/dL. Therefore, in male individuals with T2D who have low serum levels of DHEAS, adequate exercise might be needed to prevent dynapenia.

Ketogenic Diet Improves Motor Function and Motor Unit Connectivity in Aged C57BL/6 Mice

Objective

Pathological, age-related loss of muscle function, commonly referred to as sarcopenia, contributes to loss of mobility, impaired independence, as well as increased risk of adverse health events. Sarcopenia has been attributed to changes in both neural and muscular integrity during aging. Current treatment options are primarily limited to exercise and dietary protein fortification, but the therapeutic impact of these approaches are often inadequate. Prior work has suggested that a ketogenic diet (KD) might improve healthspan and lifespan in aging mice. Thus, we sought to investigate the effects of a KD on neuromuscular indices of sarcopenia in aged C57BL/6 mice.

Design

A randomized, controlled pre-clinical experiment consisting of longitudinal assessments performed starting at 22-months of age (baseline) as well as 2, 6 and 10 weeks after the start of a KD vs. regular chow intervention.

Setting

Preclinical laboratory study.

Sample size

Thirty-six 22-month-old mice were randomized into 2 dietary groups: KD [n = 22 (13 female and 9 male)], and regular chow [n = 15 (7 female and 8 male)].

Measurements

Measures included body mass, hindlimb and all limb grip strength, rotarod for motor performance, plantarflexion muscle contractility, motor unit number estimations (MUNE), and repetitive nerve stimulation (RNS) as an index of neuromuscular junction transmission efficacy recorded from the gastrocnemius muscle. At end point, blood samples were collected to assess blood beta-hydroxybutyrate levels.

Statistical Analysis

Two-way ANOVA mixed-effects analysis (time x diet) were performed to analyze grip, rotarod, MUNE, and muscle contractility data.

Results

Beta-hydroxybutyrate (BHB) was significantly higher at 10 weeks in mice on a KD vs control group (0.83 ± 0.44 mmol/l versus 0.42 ± 0.21 mmol/l, η2 = 0.265, unpaired t-test, p = 0.0060). Mice on the KD intervention demonstrated significantly increased hindlimb grip strength (time x diet, p = 0.0030), all limb grip strength (time x diet, p = 0.0523), and rotarod latency to fall (time x diet, p = 0.0021). Mice treated with the KD intervention also demonstrated significantly greater MUNE (time x diet, p = 0.0064), but no difference in muscle contractility (time x diet, p = 0.5836) or RNS (time x diet, p = 0.9871).

Conclusion

KD intervention improved neuromuscular and motor function in aged mice. This pre-clinical work suggests that further research is needed to assess the efficacy and physiological effects of a KD on indices of sarcopenia.

ROCK1 activates mitochondrial fission leading to oxidative stress and muscle atrophy

Chronic kidney disease (CKD) is often associated with protein-energy wasting (PEW), which is characterized by a reduction in muscle mass and strength. Although mitochondrial dysfunction and oxidative stress have been implicated to play a role in the pathogenesis of muscle wasting, the underlying mechanisms remain unclear. In this study, we used transcriptomics, metabolomics analyses and mouse gene manipulating approaches to investigate the effects of mitochondrial plasticity and oxidative stress on muscle wasting in mouse CKD models. Our results showed that the expression of oxidative stress response genes was increased, and that of oxidative phosphorylation genes was decreased in the muscles of mice with CKD. This was accompanied by reduced oxygen consumption rates, decreased levels of mitochondrial electron transport chain proteins, and increased cellular oxidative damage. Excessive mitochondrial fission was also observed, and we found that the activation of ROCK1 was responsible for this process. Inducible expression of muscle-specific constitutively active ROCK1(mROCK1ca)exacerbated mitochondrial fragmentation and muscle wasting in CKD mice. Conversely, ROCK1 depletion (ROCK1-/-) alleviated these phenomena. Mechanistically, ROCK1 activation promoted the recruitment of Drp1 to mitochondria, thereby facilitating fragmentation. Notably, the pharmacological inhibition of ROCK1 mitigated muscle wasting by suppressing mitochondrial fission and oxidative stress. Our findings demonstrate that ROCK1 participates in CKD-induced muscle wasting by promoting mitochondrial fission and oxidative stress, and pharmacological suppression of ROCK1 could be a therapeutic strategy for combating muscle wasting in CKD conditions.

Frailty but not low muscle quality nor sarcopenia is independently associated with mortality among previously hospitalized older adults: A prospective study

AIM

There are few studies comparing the effects of geriatric syndromes and abnormalities in nutritional status and body composition on outcomes among older individuals who have been previously hospitalized. Our study aimed to evaluate the frequency and diagnosis of geriatric syndromes, low muscle quality, and nutritional status in hospitalized older individuals, and to examine their impact on both short- and long-term outcomes.

METHODS

This was a prospective study involving older adults (≥60 years). We assessed nutritional status, muscle quality, sarcopenia, and frailty. The outcomes were functional dependence, length of hospital stay, transfer to the Intensive Care Unit, number of readmissions, and mortality. Multivariate analysis was conducted to identify independent risk factors.

RESULTS

Even after adjustment for age and sex, increased risk of death was associated with possible undernourishment, sarcopenia, low muscle quality, and frailty (P < 0.05), but not the length of hospital stay (P > 0.05). Our multivariate analysis showed that frailty was independently associated with mortality and functional dependence. Low muscle quality was independently associated with functional dependence.

CONCLUSIONS

Geriatric syndromes, abnormalities in body composition, and the overall nutritional status of older patients are important risk factors for adverse outcomes, including functional dependence and mortality. These findings emphasize the need for interventions to improve muscle quality, prevent and treat malnutrition and sarcopenia, and address frailty in hospitalized patients. Geriatr Gerontol Int 2023; 23: 736-743.

Azilsartan Ameliorates Skeletal Muscle Wasting in High Fat Diet (HFD)-induced Sarcopenic Obesity in Rats via Activating Akt Signalling Pathway

An association between the loss of skeletal muscle mass and obesity in the geriatric population has been identified as a disease known as sarcopenic obesity. Therefore, therapeutic/preventive interventions are needed to ameliorate sarcopenia. The present study investigates the effect of azilsartan (AZL) on skeletal muscle loss in High-Fat Diet (HFD)-induced sarcopenic obese (SO) rats. Four- and fourteen-months male Sprague Dawley rats were used and randomized in control and azilsartan treatment. 14 months animals were fed with HFD for four months and labeled as HFD-fed SO rats. Young & old rats received 0.5% carboxymethyl cellulose as a vehicle/AZL (8 mg/kg, per oral) treatment for six weeks. Grip strength and body composition analysis were performed after the last dose of AZL. Serum and gastrocnemius (GN)muscles were collected after animal sacrifice. AZL treatment significantly increased lean muscle mass, grip strength, myofibrillar protein, and antioxidant (superoxide dismutase & nitric oxide) levels in SO rats. AZL also restored the muscle biomarkers (creatine kinase, myostatin & testosterone), and insulin levels. AZL improves cellular, and ultracellular muscle structure and prevents type I to type II myofiber transitions in SO rats. Further, immunohistochemistry results showed increased expressions of pAkt and reduced expression of MuRF-1 and TNF-α exhibiting that AZL intervention could decrease protein degradation in SO rats. In conclusion, present results showed that AZL significantly increased lean mass, and restored muscle biomarkers, and muscle architecture. Taken together, the aforementioned findings suggest that azilsartan could be a possible therapeutic approach to reduce muscle wasting in sarcopenic obesity.

Which vertebral level should be used to calculate sarcopenia in covid-19 patients? A systematic review and meta-analysis

BACKGROUND & AIMS

Evidence shows that CT-derived sarcopenia can predict adverse outcomes in COVID-19 patients. However, discrepancies exist as to which vertebral level can be used to calculate sarcopenia which can effectively serve as a prognostic tool. Thus, we aim to investigate the difference in sarcopenia calculated at the Thoracic and Lumbar vertebral levels.

METHODS

An online literature search was conducted on Electronic databases such as PubMed, Cochrane CENTRAL, and Google scholar. Meta-analysis was performed by using Revman 5.3 software.

RESULTS

A total of 14 articles were selected for meta-analysis. The prevalence of sarcopenia calculated at the Thoracic level was 31% (95%CI 24%-37%; p < 0.00001; I² = 86%), while sarcopenia calculated at the Lumbar vertebral level was 63% (95%CI 51%-75%; p < 0.00001; I² = 88%). Meanwhile, sarcopenia calculated at the Upper thoracic level was a significant predictor of mortality OR 3.47 (95%CI 1.74-6.91; p = 0.0004; I² = 56%)as compared to sarcopenia calculated at the lower thoracic OR 1.74 (95%Cl 0.91-3.33; p = 0.10; I² = 60%)or lumbar level OR 2.49 (95%CI 0.45-13.72; p = 0.30; I² = 57%). In addition to this sarcopenia calculated at the Upper thoracic level was also a significant predictor of severe illness OR 3.92 (95%CI 2.33-6.58; p < 0.00001; I² = 0%) as compared to lower thoracic OR 1.40 (95%CI 0.78-2.53; p = 0.26; I² = 67%) or lumbar level OR 1.64 (95%CI 0.26-10.50; p = 0.60; I² = 81%) CONCLUSIONS: Sarcopenia calculated at the thoracic vertebrae and lumber level has different prognostic values. Sarcopenia is prevalent at the lumbar level. Sarcopenia at the thoracic level has a higher mortality and severity rate.

Effects of polyphenols and their metabolites on age-related diseases

Aging contributes to the progressive loss of cellular biological functions and increases the risk of age-related diseases. Cardiovascular diseases, some neurological disorders and cancers are generally classified as age-related diseases that affect the lifespan of individuals. These diseases result from the accumulation of cellular damage and reduced activity of protective stress response pathways, which can lead to inflammation and oxidative stress, which play a key role in the aging process. There is now increasing interest in the therapeutic effects of edible plants for the prevention of various diseases, including those associated with aging. It has become clear that the beneficial effects of these foods are due, at least in part, to the high concentration of bioactive phenolic compounds with low side effects. Antioxidants are the most abundant, and their high consumption in the Mediterranean diet has been associated with slower ageing in humans. Extensive human dietary intervention studies strongly suggest that polyphenol supplementation protects against the development of degenerative diseases, especially in the elderly. In this review, we present data on the biological effects of plant polyphenols in the context of their relevance to human health, ageing and the prevention of age-related diseases.

Association of a mixture of phthalates and phenols with frailty among middle-aged and older adults: A population-based cross-sectional study

BACKGROUND

Frailty is a complex geriatric syndrome caused by degenerative changes in the body or various chronic diseases. The use of personal care and consumer products is associated with a wide range of health outcomes, but its relationship with frailty remains unknown. Therefore, our primary aim was to explore the potential links between exposure to phenols and phthalates, either separately or in combination, and frailty.

METHODS

The exposure levels of phthalates and phenols were evaluated through the measurement of metabolites in urine samples. Frailty state was assessed by a 36-item frailty index with values ≥ 0.25 indicating frailty. Weighted logistic regression was used to explore the relationship between individual chemical exposure and frailty. In addition, multi-pollutant strategies (WQS, Qgcomp, BKMR) were used to examine the joint effect of chemical mixture on frailty. A series of subgroup analyses and sensitivity analyses were conducted as well.

RESULTS

In the multivariate logistic regression model, each unit increase in natural log-transformed BPA (OR: 1.21; 95%CI: 1.04, 1.40), MBP (OR: 1.25; 95%CI: 1.07, 1.46), MBzP (OR: 1.18; 95%CI: 1.03, 1.36), and MiBP (OR: 1.19; 95%CI: 1.03, 1.37) were significantly associated with higher odds of frailty. The results of the WQS and Qgcomp indicated that increasing quartiles of chemical mixture was associated with odds of frailty with ORs of 1.29 (95%CI: 1.01, 1.66) and 1.37 (95%CI: 1.06, 1.76). The weight of MBzP is dominant in both the WQS index and the positive weight of Qgcomp. In the BKMR model, the cumulative effect of chemical mixture was positively correlated with the prevalence of frailty.

CONCLUSIONS

In summary, higher levels of BPA, MBP, MBzP, and MiBP are significantly associated with higher odds of frailty. Our study provides preliminary evidence that phenol and phthalate biomarker mixture is positively associated with frailty, with MBzP contributing most to the positive association.

Mitochondrial transplantation as a possible therapeutic option for sarcopenia

With advancing age, the skeletal muscle phenotype is characterized by a progressive loss of mass, strength, and quality. This phenomenon, known as sarcopenia, has a negative impact on quality of life and increases the risk of morbidity and mortality in older adults. Accumulating evidence suggests that damaged and dysfunctional mitochondria play a critical role in the pathogenesis of sarcopenia. Lifestyle modifications, such as physical activity, exercise, and nutrition, as well as medical interventions with therapeutic agents, are effective in the management of sarcopenia and offer solutions to maintain and improve skeletal muscle health. Although a great deal of effort has been devoted to the identification of the best treatment option, these strategies are not sufficient to overcome sarcopenia. Recently, it has been reported that mitochondrial transplantation may be a possible therapeutic approach for the treatment of mitochondria-related pathological conditions such as ischemia, liver toxicity, kidney injury, cancer, and non-alcoholic fatty liver disease. Given the role of mitochondria in the function and metabolism of skeletal muscle, mitochondrial transplantation may be a possible option for the treatment of sarcopenia. In this review, we summarize the definition and characteristics of sarcopenia and molecular mechanisms associated with mitochondria that are known to contribute to sarcopenia. We also discuss mitochondrial transplantation as a possible option. Despite the progress made in the field of mitochondrial transplantation, further studies are needed to elucidate the role of mitochondrial transplantation in sarcopenia. KEY MESSAGES: Sarcopenia is the progressive loss of skeletal muscle mass, strength, and quality. Although the specific mechanisms that lead to sarcopenia are not fully understood, mitochondria have been identified as a key factor in the development of sarcopenia. Damaged and dysfunctional mitochondria initiate various cellular mediators and signaling pathways, which largely contribute to the age-related loss of skeletal muscle mass and strength. Mitochondrial transplantation has been reported to be a possible option for the treatment/prevention of several diseases. Mitochondrial transplantation may be a possible therapeutic option for improving skeletal muscle health and treating sarcopenia. Mitochondrial transplantation as a possible treatment option for sarcopenia.

Fast and slow skeletal myosin binding protein-C and aging

Aging is associated with skeletal muscle strength decline and cardiac diastolic dysfunction. The structural arrangements of the sarcomeric proteins, such as myosin binding protein-C (MyBP-C) are shown to be pivotal in the pathogenesis of diastolic dysfunction. Yet, the role of fast (fMyBP-C) and slow (sMyBP-C) skeletal muscle MyBP-C remains to be elucidated. Herein, we aimed to characterize MyBP-C and its paralogs in the fast tibialis anterior (TA) muscle from adult and old mice. Immunoreactivity preparations showed that the relative abundance of the fMyBP-C paralog was greater in the TA of both adult and old, but no differences were noted between groups. We further found that the expression level of cardiac myosin binding protein-C (cMyBP-C), an important modulator of cardiac output, was lowered by age. Standard SDS-PAGE along with Pro-Q Diamond phosphoprotein staining did not identify age-related changes in phosphorylated MyBP-C proteins from TA and cardiac muscles; however, it revealed that MyBP-C paralogs in fast skeletal and cardiac muscle were highly phosphorylated. Mass spectrometry further identified glycogen phosphorylase, desmin, actin, troponin T, and myosin regulatory light chain 2 as phosphorylated myofilament proteins in both ages. MyBP-C protein-bound carbonyls were determined using anti-DNP immunostaining and found the carbonyl level of fMyBP-C, sMyBP-C, and cMyBP-C to be similar between old and adult animals. In summary, our data showed some differences regarding the MyBP-C paralog expression and identified an age-related reduction of cMyBP-C expression. Future studies are needed to elucidate which are the age-driven post-translational modifications in the MyBP-C paralogs.

Association between composite dietary antioxidant index and handgrip strength in American adults: Data from National Health and Nutrition Examination Survey (NHANES, 2011-2014)

Background

The Composite Dietary Antioxidant Index (CDAI), a composite score of multiple dietary antioxidants (including vitamin A, C, and E, selenium, zinc, and carotenoids), represents an individual's comprehensive dietary antioxidant intake profile. CDAI was developed based on its combined effect on pro-inflammatory markers Tumor Necrosis Factor-α (TNF-α) and anti-inflammatory effects of Interleukin-1β (IL-1β), which are associated with many health outcomes, including depression, all-cause mortality, colorectal cancer, etc. Handgrip strength is used as a simple measure of muscle strength, not only is it highly correlated with overall muscle strength, but also serves as a diagnostic tool for many adverse health outcomes, including sarcopenia and frailty syndromes.

Purpose

The association between CDAI and Handgrip strength (HGS) is currently unclear. This study investigated the association between CDAI (including its components) and HGS in 6,019 American adults.

Method

The research data were selected from the 2011-2014 National Health and Nutrition Survey (NHANES), and a total of 6,019 American adults were screened and included. A weighted generalized linear regression model was used to evaluate CDAI (including its components) and HGS.

Results

(1) CDAI was significantly positively correlated with HGS (β = 0.009, 0.005∼0.013, P < 0.001), and the trend test showed that compared with the lowest quartile of CDAI, the highest quartile of CDAI was positively correlated with HGS (β = 0.084, 0.042∼0.126, P = 0.002) and significant in trend test (P for trend < 0.0100). Gender subgroup analysis showed that male CDAI was significantly positively correlated with HGS (β = 0.015, 0.007∼0.023, P = 0.002), and the trend test showed that compared with the lowest quartile of CDAI, the highest quartile of CDAI was positively correlated with HGS (β = 0.131, 0.049∼0.213, P = 0.006) and the trend test was significant (P for trend < 0.0100). There was no correlation between female CDAI and HGS, and the trend test was not statistically significant (P > 0.05). (2) The intake of dietary vitamin E, Zinc and Selenium showed a significant positive correlation with HGS (β = 0.004, 0.002∼0.007, P = 0.006; β = 0.007, 0.004∼0.009, P < 0.001; β = 0.001, 0.001∼0.001, P < 0.001), vitamin A, vitamin C and carotenoid were significantly associated with HGS in the Crude Model, but this significant association disappeared in the complete model with the increase of control variables. Gender subgroup analysis showed that in model 3, male dietary intake levels of vitamin E, Zinc, and Selenium were significantly positively correlated with HGS (β = 0.005, 0.002∼0.009, P = 0.011; β = 0.007, 0.004∼0.011, P = 0.001; β = 0.001, 0.001∼0.001, P = 0.004), the rest of the indicators had no significant correlation with HGS. Among the female subjects, dietary zinc intake was significantly positively correlated with HGS (β = 0.005, 0.001∼0.008, P = 0.008), and there was no significant correlation between other indicators and HGS (P > 0.05).

Conclusion

There was an association between the CDAI and HGS, but there was a gender difference, and there was an association between the CDAI and HGS in male, but the association was not significant in female. Intake of the dietary antioxidants vitamin E, selenium, and zinc was associated with HGS in male, but only zinc was associated with HGS among dietary antioxidants in female.

C-reactive protein, but not neutrophil-lymphocyte ratio, is inversely associated with muscle strength only in older men: NHANES 1999-2002

To evaluate the association of inflammation (C-reactive protein (CRP) and neutrophil-lymphocyte ratio (NLR) levels) with muscle strength in older adults. We also aimed to evaluate whether these associations are sex-specific. A cross-sectional study was performed with data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 and 2001-2002. A total of 2387 individuals over 50 years of both sexes were evaluated, according to the eligibility criteria for the strength test. Muscle strength was measured by Kinetic Communicator isokinetic dynamometer; while the NLR was obtained by the ratio of the total neutrophil for lymphocyte count and CRP was quantified by latex nephelometry. Linear regression analyses, crude and adjusted for confounders, were used to estimate the coefficients and 95 % confidence intervals for peak strength (muscle strength) by tertiles of NLR and CRP. There was no association between NLR and peak strength for both sexes. CRP levels were inversely associated with peak force in men [2nd tertile β = -3.33 (-15.92; 9.25); 3rd tertile β = -24.69 (-41.18; -8.20), p for trend = 0.005], but not in women [2nd tertile β = -3.22 (-15.00; 8.56); 3rd tertile β = -9.23 (-28.40; -9.94), p for trend = 0.332]. In conclusion, NLR levels were not associated with muscle strength in both sexes. CRP levels were inversely associated with muscle strength in older men, but not in women, suggesting that the association between inflammation and muscle strength in older adults can be sex-specific.

Targeting Mitochondria and Oxidative Stress in Cancer- and Chemotherapy-Induced Muscle Wasting

Significance: Cancer is frequently associated with the early appearance of cachexia, a multifactorial wasting syndrome. If not present at diagnosis, cachexia develops either as a result of tumor progression or as a side effect of anticancer treatments, especially of standard chemotherapy, eventually representing the direct cause of death in up to one-third of all cancer patients. Cachexia, within its multiorgan affection, is characterized by severe loss of muscle mass and function, representing the most relevant subject of preclinical and clinical investigation. Recent Advances: The pathogenesis of muscle wasting in cancer- and chemotherapy-induced cachexia is complex, and encompasses heightened protein catabolism and reduced anabolism, disrupted mitochondria and energy metabolism, and even neuromuscular junction dismantling. The mechanisms underlying these alterations are still controversial, especially concerning the molecular drivers that could be targeted for anticachexia therapies. Inflammation and mitochondrial oxidative stress are among the principal candidates; the latter being extensively discussed in the present review. Critical Issues: Several approaches have been tested to modulate the redox homeostasis in tumor hosts, and to counteract cancer- and chemotherapy-induced muscle wasting, from exercise training to distinct classes of direct or indirect antioxidants. We herein report the most relevant results obtained from both preclinical and clinical trials. Future Directions: Including the assessment and the treatment of altered redox balance in the clinical management of cancer patients is still a big challenge. The available evidence suggests that fortifying the antioxidant defenses by either pharmacological or nonpharmacological strategies will likely improve cachexia and eventually the outcome of a broad cancer patient population. Antioxid. Redox Signal. 38, 352-370.

Age-Related Changes in Skeletal Muscle Iron Homeostasis

Sarcopenia is an age-related condition of slow, progressive loss of muscle mass and strength, which contributes to frailty, increased risk of hospitalization and mortality, and increased health care costs. The incidence of sarcopenia is predicted to increase to >200 million affected older adults worldwide over the next 40 years, highlighting the urgency for understanding biological mechanisms and developing effective interventions. An understanding of the mechanisms underlying sarcopenia remains incomplete. Iron in the muscle is important for various metabolic functions, including oxygen supply and electron transfer during energy production, yet these same chemical properties of iron may be deleterious to the muscle when either in excess or when biochemically unshackled (eg, in ferroptosis), it can promote oxidative stress and induce inflammation. This review outlines the mechanisms leading to iron overload in muscle with aging and evaluates the evidence for the iron overload hypothesis of sarcopenia. Based on current evidence, studies are needed to (a) determine the mechanisms leading to iron overload in skeletal muscle during aging; and (b) investigate whether skeletal muscles are functionally deficient in iron during aging leading to impairments in oxidative metabolism.

Dynapenic Abdominal Obesity as a Risk Factor for Metabolic Syndrome in Individual 50 Years of Age or Older: English Longitudinal Study of Ageing

OBJECTIVES

To analyse whether dynapenic abdominal obesity is a risk factor for Metabolic syndrome (MetS) and its components in individuals 50 years of age or older.

DESIGN

A longitudinal study was conducted with an eight-year follow-up.

SETTING

Representative sample of community-dwelling participants of the English Longitudinal Study of Ageing (ELSA).

PARTICIPANTS

3,952 individuals free of MetS at baseline.

MEASUREMENTS

Dynapenic abdominal obesity was defined based on waist circumference (> 102 cm for men and > 88 cm for women) and grip strength (< 26 kg for men and < 16 kg for women). The participants were classified as non-abdominally obese/non-dynapenic (NAO/ND - reference group), abdominally obese/non-dynapenic (AO/ND), non-abdominally obese/dynapenic (NAO/D) and abdominally obese/dynapenic (AO/D). The outcome was the incidence of MetS based on the presence of three or more of the following criteria: hypertriglyceridemia, hyperglycaemia, low HDL cholesterol, arterial hypertension or body mass index ≥ 30 kg/m2 throughout eight-year follow-up. Additionally, the incidence of each component of MetS was also analyzed. Poisson regression models were run and controlled for sociodemographic, behavioural and clinical variables.

RESULTS

The mean age of the participants was 65 years and 55% were women. The prevalence of AO/ND, NAO/D and AO/D were 35.3, 4.3 and 2.2%, respectively. At the end of follow-up 558 incident cases of MetS were recorded. The adjusted model demonstrated that although abdominal obesity was a risk factor for MetS (IRR: 2.26; 95% CI: 1.87 - 2.73), the IRR was greater in AO/D individuals (IRR: 3.34; 95% CI: 2.03 - 5.50) compared with ND/NAO group. Furthermore, ND/AO was a risk factor for incidence of hypertriglyceridemia (IRR: 1.27; 95% CI: 1.06 - 1.52), hyperglycaemia (IRR: 1.41; 95% CI: 1.18 - 1.69), low HDL cholesterol (IRR: 1.70; 95% CI: 1.32 - 2.19) and BMI ≥ 30 kg/m2 (IRR: 2.58; 95% CI: 2.04 - 3.26) while D/AO was a risk factor for hyperglycaemia (IRR: 1.78; 95% CI: 1.02 - 3.10), low HDL cholesterol (IRR: 2.36; 95% CI: 1.10 - 5.08), and BMI ≥ 30 kg/m2 (IRR: 2.79; 95% CI: 1.38 - 5.62).

CONCLUSIONS

Dynapenic abdominal obesity increases the risk of MetS, with a higher IRR compared to obesity alone. The understanding of this synergic action could guide specific clinical strategies, enabling the prevention of metabolic changes that can lead to cardiovascular disease, disability and death.

Effects of Fisetin, a Plant-Derived Flavonoid, on Response to Oxidative Stress, Aging, and Age-Related Diseases in Caenorhabditis elegans

Fisetin (3,3',4',7-tetrahydroxyflavone), a flavonoid abundant in various fruits and vegetables, including apple, strawberry, and onion, shows several beneficial effects such as anti-oxidant, anti-inflammatory, and anti-tumor effects. The free radical theory of aging suggests that age-related accumulation of oxidative damage is the major cause of aging and that decreasing cellular oxidative stress can regulate aging. Here, we investigated the effects of dietary supplementation with fisetin on the stress response, aging, and age-related diseases. Fisetin reduced the cellular ROS levels and increased the resistance to oxidative stress. However, the response to UV irradiation was not affected by fisetin. Both the mean and maximum lifespans were significantly extended by fisetin; lifespan extension by fisetin was accompanied by reduced fertility as a trade-off. Age-related decline in motility was also delayed by supplementation with fisetin. Amyloid beta-induced toxicity was markedly decreased by fisetin, which required DAF-16 and SKN-1. Reduced motility induced by a high-glucose diet was completely recovered by supplementation with fisetin, which was dependent on SKN-1. Using a Parkinson's disease model, we showed that degeneration of dopaminergic neurons was significantly inhibited by treatment with fisetin. Genetic analysis revealed that lifespan extension by fisetin was mediated by DAF-16-induced stress response and autophagy. These findings support the free radical theory of aging and suggest that fisetin can be a strong candidate for use in novel anti-aging anti-oxidant nutraceuticals.

Serum uric acid is not associated with appendicular muscle mass index in young and middle-aged adults: Results from NHANES 2011-2012

BACKGROUND

Recent studies have evaluated the association between uric acid (UA) and muscle mass in older adults; however, little is known about this relationship in young and middle-aged individuals. Our aim was to investigate whether serum UA is associated with appendicular muscle mass index (AMMI) in young and middle-aged individuals. We also aimed to evaluate whether this association is sex-specific.

METHODS

A cross-sectional study was performed with young and middle-aged individuals aged from 20 to 59 years from National Health and Nutrition Examination Survey (NHANES) 2011-2012. A total of 2255 individuals (1440 young and 815 middle-aged individuals; 1167 men and 1088 women) were evaluated. Body composition was assessed by Dual Energy X-ray absorptiometry (DXA) and AMMI was calculated using the arms plus legs lean mass divided by the height squared. UA levels were measured by colorimetric method. Regression analyzes were performed to evaluate whether AMMI is associated with the tertiles of UA levels after adjustments for potential confounders.

RESULTS

In the unadjusted analyzes, serum UA was positively associated with AMMI for total sample, young, and middle-aged individuals of both sexes. However, after adjustments for confounders, UA levels were no longer associated with AMMI independent of the age-rage and sex.

CONCLUSION

Serum UA is not associated with AMMI in young or middle-aged individuals independent of the sex.

Elamipretide effects on the skeletal muscle phosphoproteome in aged female mice

The age-related decline in skeletal muscle mass and function is known as sarcopenia. Sarcopenia progresses based on complex processes involving protein dynamics, cell signaling, oxidative stress, and repair. We have previously found that 8-week treatment with elamipretide improves skeletal muscle function, reverses redox stress, and restores protein S-glutathionylation changes in aged female mice. This study tested whether 8-week treatment with elamipretide also affects global phosphorylation in skeletal muscle consistent with functional improvements and S-glutathionylation. Using female 6-7-month-old mice and 28-29-month-old mice, we found that phosphorylation changes did not relate to S-glutathionylation modifications, but that treatment with elamipretide did partially reverse age-related changes in protein phosphorylation in mouse skeletal muscle.

Serum α-Carotene, but Not Other Antioxidants, Is Positively Associated with Muscle Strength in Older Adults: NHANES 2001-2002

Aging is associated with an increased reactive oxygen species that can decrease muscle strength. Thus, antioxidant substances could be positively associated with muscle strength in older adults. To investigate the association between serum antioxidants and muscle strength in older adults. A cross-sectional study evaluating 1172 individuals (627 men and 545 women), aged 50 to 85 years from NHANES 2001-2002, was performed. Carotenoids (α-carotene, trans-β-carotene, cis-β-carotene, β-cryptoxanthin, lutein/zeaxanthin combination, trans-lycopene), vitamin E, and retinol were analyzed via the high-performance liquid chromatography method. Muscle strength was evaluated by the isokinetic knee extension test. Linear regression was performed to evaluate the association between tertiles of serum antioxidant levels and strength, adjusted for confounders (energy and protein intake, body mass index, sex, age, C-reactive protein, uric acid, race/ethnicity, marital status, annual household income, educational level, physical activity, smoking, hypertension, arthritis, and diabetes). Alpha-carotene levels (p-trend = 0.027) were positively associated with muscle strength. However, serum vitamin E, trans-β-carotene, cis-β-carotene, β-cryptoxanthin, carotenoids, and retinol levels were not associated with strength. Serum α-carotene, but not other antioxidants, was positively associated with muscle strength in older adults.

ALDH2 gene polymorphism is associated with fitness in the elderly Japanese population

PURPOSE

The aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphism, which is exclusive to the Asian population, is related to many diseases. A high reactive oxygen species production in mitochondria, and low muscle strength in athletes and non-athletes, has been observed, as our previous study demonstrated. The purpose of this research was to investigate the influence of ALDH2 rs671 on the loss of muscle strength with aging and replicate our previous study in non-athletes.

METHODS

Healthy Japanese individuals (n = 1804) aged 23-94 years were genotyped using DNA extracted from saliva. Muscle strength was assessed using grip strength and chair stand test (CST). The interaction between age and genotypes was analyzed by two-way analysis of covariance (ANCOVA) adjusted for sex, body mass index (BMI), and exercise habit.

RESULTS

Individuals aged ≧55 with the AA genotype had a lower performance than those with the GG + GA genotype in the grip strength test (28.1 ± 9.1 kg vs. 29.1 ± 8.3 kg, p = 0.021). There was an interaction between age and genotype, where individuals with ≧55 years old AA genotype had a higher loss of strength compared to GG + GA genotypes in the CST (0.025). No interaction in other models and no sex differences were found.

CONCLUSION

This study replicated previous results of the relationship between the AA genotype with lower muscle strength and as a novelty showed that this genotype is associated with a higher age-related loss of strength.

Connexin 43 Channels in Osteocytes Are Necessary for Bone Mass and Skeletal Muscle Function in Aged Male Mice

Osteoporosis and sarcopenia (termed "Osteosarcopenia"), the twin-aging diseases, are major contributors to reduced bone mass and muscle weakness in the elderly population. Connexin 43 (Cx43) in osteocytes has been previously reported to play vital roles in bone homeostasis and muscle function in mature mice. The Cx43-formed gap junctions (GJs) and hemichannels (HCs) in osteocytes are important portals for the exchange of small molecules in cell-to-cell and cell-to-extracellular matrix, respectively. However, the roles of Cx43-based GJs and HCs in both bone and muscle aging are still unclear. Here, we used two transgenic mouse models with overexpression of the dominant negative Cx43 mutants primarily in osteocytes driven by the 10-kb Dmp1 promoter, R76W mice (inhibited gap junctions but enhanced hemichannels) and Δ130-136 mice (both gap junction and hemichannels are inhibited), to determine the actions of Cx43-based hemichannels (HCs) and gap junctions (GJs) in the regulation of bone and skeletal muscle from aged mice (18 months) as compared with those from adult mice (10 months). We demonstrated that enhancement of Cx43 HCs reduces bone mass due to increased osteoclast surfaces while the impairment of Cx43 HCs increases osteocyte apoptosis in aged mice caused by reduced PGE2 levels. Furthermore, altered mitochondrial homeostasis with reduced expression of Sirt-1, OPA-1, and Drp-1 resulted in excessive ROS level in muscle soleus (SL) of aged transgenic mice. In vitro, the impairment of Cx43 HCs in osteocytes from aged mice also promoted muscle collagen synthesis through activation of TGFβ/smad2/3 signaling because of reduced PGE2 levels in the PO CM. These findings indicate that the enhancement of Cx43 HCs while GJs are inhibited reduces bone mass, and the impairment of Cx43 HCs inhibits PGE2 level in osteocytes and this reduction promotes muscle collagen synthesis in skeletal muscle through activation of TGFβ/smad2/3 signaling, which together with increased ROS level contributes to reduced muscle force in aged mice.

Relationship between serum indirect bilirubin levels and skeletal muscle mass in older male and female patients with type 2 diabetes

Objective

We previously showed that low serum bilirubin levels are associated with disability in quality of daily living in older patients with diabetes. However, the underlying mechanism is not fully understood. The aim of this study is to assess the relationship between serum bilirubin levels and skeletal muscle mass in older patients with type2 diabetes.

Methods

A total of 272 older patients with type2 diabetes (152 male and 120 female) aged 60 years and over were continuously recruited from April 2020 to July 2020. Body composition was evaluated by bioelectrical impedance analysis. The skeletal muscle mass index (SMI) was calculated as appendicular muscle mass divided by height squared (m²).

Results

The SMI was markedly lower in old-old patients (aged 75 years and over) than in young-old patients (aged 60–74 years) in both male and female (7.1 ± 0.8 kg/m² vs 7.6 ± 0.9 kg/m², P<0.001; 5.5 ± 0.9 kg/m² vs 6.3 ± 0.8 kg/m², P<0.001, respectively). Multivariate regression analysis showed that the SMI was associated with body mass index (BMI) (p<0.001) and age (p = 0.048) in male young-old patients, while it was associated with BMI (p<0.001), age (p = 0.008), and serum indirect bilirubin levels (p = 0.038) in male old-old patients. In female, the SMI was associated with BMI (p<0.001) and age (p = 0.042) in young-old patients and associated with BMI alone (p<0.001) in old-old patients.

Conclusion

Serum indirect bilirubin levels may be associated with the decreased skeletal muscle mass in male older patients (aged 75 years and over) with type 2 diabetes.

Handgrip strength and the risk of major depressive disorder: a two-sample Mendelian randomisation study

Background

Major depressive disorder (MDD) is a common psychiatric disease and a leading cause of disability worldwide. Handgrip strength (HGS) as an objective physical fitness test is a practical index for identifying many diseases. Previous studies drew different conclusions about the relationship between HGS and MDD.

Aims

We aim to explore whether HGS has an effect on the risk of MDD.

Methods

HGS-related single-nucleotide polymorphisms identified by a genome-wide association study were used as instrumental variables in this Mendelian randomisation (MR) study. Summary data on MDD were obtained from the Psychiatric Genomics Consortium. Four methods were applied, including inverse variance weighted (IVW), MR Egger, weighted median and weighted mode. Additional sensitivity analyses, including leave-one-out, heterogeneity test, pleiotropy test and confounders identification, were conducted to test the robustness of our results.

Results

Each 1 kg increase in left HGS is associated with a 21.95% reduction in the risk of MDD (OR_IVW = 0.781, 95% CI: 0.650 to 0.937, p=0.009), while no significant correlation exists in the estimation of right HGS (p=0.146). Sensitivity analyses demonstrated statistical significance (β_IVW = −0.195, p=0.023) after excluding some genetic loci that cause pleiotropy.

Conclusions

Increased left HGS is associated with a reduced risk of MDD. In the future, it may be used as an index for the clinical screening, observation and treatment of MDD.

Neuromuscular mechanisms of weakness in a mouse model of chronic alcoholic myopathy

BACKGROUND

Weakness is a common clinical symptom reported in individuals with chronic alcohol use disorder. However, it remains unclear whether low strength in these individuals is directly related to excessive ethanol intake, other deleterious factors (lifestyle, environment, genetics, etc.), or a combination of both. Therefore, we examined whether (and how) ethanol reduces the muscle's force-producing capacity using a controlled in vivo preclinical mouse model of excessive ethanol intake.

METHODS

To establish whether chronic ethanol consumption causes weakness, C57BL/6 female mice consumed 20% ethanol for 40 weeks (following a 2-week ethanol ramping period), and various measures of muscular force were quantified. Functional measures included all-limb grip strength and in vivo contractility of the left ankle dorsiflexors and plantarflexors. Once confirmed that mice consuming ethanol were weaker than age-matched controls, we sought to determine the potential neuromuscular mechanisms of muscle dysfunction by assessing neuromuscular excitation, muscle quantity, and muscle quality.

RESULTS

Mice consuming chronic ethanol were 13 to 16% weaker (p ≤ 0.016) than controls (i.e., mice consuming 100% water) with the negative impact of ethanol on voluntary grip strength (ƞ²  = 0.603) being slightly larger than that of electrically stimulated muscle contractility (ƞ²  = 0.482). Relative to controls, lean mass and muscle wet masses were 9 to 16% lower in ethanol-consuming mice (p ≤ 0.048, ƞ²  ≥ 0.268). No significant changes were observed between groups for indices of neuromuscular excitation at the level of the motor unit, neuromuscular junction, or plasmalemma (p ≥ 0.259, ƞ²  ≤ 0.097), nor was muscle quality altered after 40 weeks of 20% ethanol consumption (p ≥ 0.695, ƞ²  ≤ 0.012).

CONCLUSIONS

Together, these findings establish that chronic ethanol consumption in mice induces a substantial weakness in vivo that we interpret to be primarily due to muscle atrophy (i.e., reduced muscle quantity) and possibly, to a lesser degree, loss of central neural drive.

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.

Effect of Physical Activity/Exercise on Oxidative Stress and Inflammation in Muscle and Vascular Aging

Functional status is considered the main determinant of healthy aging. Impairment in skeletal muscle and the cardiovascular system, two interrelated systems, results in compromised functional status in aging. Increased oxidative stress and inflammation in older subjects constitute the background for skeletal muscle and cardiovascular system alterations. Aged skeletal muscle mass and strength impairment is related to anabolic resistance, mitochondrial dysfunction, increased oxidative stress and inflammation as well as a reduced antioxidant response and myokine profile. Arterial stiffness and endothelial function stand out as the main cardiovascular alterations related to aging, where increased systemic and vascular oxidative stress and inflammation play a key role. Physical activity and exercise training arise as modifiable determinants of functional outcomes in older persons. Exercise enhances antioxidant response, decreases age-related oxidative stress and pro-inflammatory signals, and promotes the activation of anabolic and mitochondrial biogenesis pathways in skeletal muscle. Additionally, exercise improves endothelial function and arterial stiffness by reducing inflammatory and oxidative damage signaling in vascular tissue together with an increase in antioxidant enzymes and nitric oxide availability, globally promoting functional performance and healthy aging. This review focuses on the role of oxidative stress and inflammation in aged musculoskeletal and vascular systems and how physical activity/exercise influences functional status in the elderly.

Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet in relation to age-associated poor muscle strength; a cross-sectional study from the Kurdish cohort study

The Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet is an eating pattern associated with multiple health benefits, including the conservation of skeletal muscle. The Hand Grip Strength (HGS) is the most frequently used indicator of muscle functional capacity and muscle strength for clinical purposes. The current study aims to investigate the association between adherence to MIND diet and prevention of age-associated decline in muscle strength among the Kurdish population in Iran. This cross-sectional study was performed using data from Ravansar non-communicable diseases (RaNCD) cohort study on 3181 adults (48.5% men) aged 35–65 years. The dietary intake of the studied participants was assessed using a 114-item food frequency questionnaire (FFQ) developed by RaNCD cohort study. The MIND diet and the major dietary patterns were identified based on the participants’ dietary intake and three dietary patterns emerged including plant-based diet, high protein diet, and unhealthy diet. Hand grip strength (HGS) was measured using a hand-held hydraulic handgrip dynamometer and poor HGS was defined as HGS less than 32.8 and 20.5 kg in men and women, respectively. Compared with participants in the lowest category of MIND diet, those in the highest category had lower odds of poor HGS (OR: 0.65; CI 95%: 0.51–0.83). Furthermore, participants who were in third tertiles of plant-based and high protein diet were more likely 37% and 33% lower odds ratio of poor HGS (OR: 0.63; CI 95%: 0.5–0.79), (OR: 0.67; CI 95%: 0.54–0.84), respectively. On the other hand, greater adherence to the unhealthy diet was increased odds of poor HGS (OR: 1.39; CI 95%: 1.11–1.74). Overall, our findings suggest that adherence to the MIND diet and high protein diet may be associated with higher HGS, while adherence to the unhealthy diet can increase the odds of age-associated poor HGS in the Kurdish population.

Sarcopenia in Menopausal Women: Current Perspectives

Menopause is associated with hormonal changes, which could accelerate or lead to sarcopenia. Functional impairment and physical disability are the major consequences of sarcopenia. In order to hamper these negative health outcomes, it appears necessary to prevent and even treat sarcopenia, through healthy lifestyle changes including diet and regular physical activity or through hormonal replacement therapy when appropriate. Therefore, the purpose of this narrative review will be 1) to present the prevalence of sarcopenia in postmenopausal women; 2) to address the risk factors related to sarcopenia in this specific population; and 3) to discuss how to manage sarcopenia among postmenopausal women.