Sarcopenia

Aging Triggers H3K27 Trimethylation Hoarding in the Chromatin of Nothobranchius furzeri Skeletal Muscle

Aging associates with progressive loss of skeletal muscle function, sometimes leading to sarcopenia, a process characterized by impaired mobility and weakening of muscle strength. Since aging associates with profound epigenetic changes, epigenetic landscape alteration analysis in the skeletal muscle promises to highlight molecular mechanisms of age-associated alteration in skeletal muscle. This study was conducted exploiting the short-lived turquoise killifish Nothobranchius furzeri (Nfu), a relatively new model for aging studies. The epigenetic analysis suggested a less accessible and more condensed chromatin in old Nfu skeletal muscle. Specifically, an accumulation of heterochromatin regions was observed as a consequence of increased levels of H3K27me3, HP1α, polycomb complex subunits, and senescence-associated heterochromatic foci (SAHFs). Consistently, euchromatin histone marks, including H3K9ac, were significantly reduced. In this context, integrated bioinformatics analysis of RNASeq and ChIPSeq, related to skeletal muscle of Nfu at different ages, revealed a down-modulation of genes involved in cell cycle, differentiation, and DNA repair and an up-regulation of inflammation and senescence genes. Undoubtedly, more studies are needed to disclose the detailed mechanisms; however, our approach enlightened unprecedented features of Nfu skeletal muscle aging, potentially associated with swimming impairment and reduced mobility typical of old Nfu.

Osteosarcopenia

Osteosarcopenia is a newly described syndrome that describes the co-existence of osteoporosis and sarcopenia, two chronic musculoskeletal conditions associated with ageing. Osteoporosis, a condition of low bone mass and micro-architectural deterioration of bone, and sarcopenia, the loss of muscle mass, strength and function, often co-exist in a frail subset of the elderly population, leading to significantly worsened outcomes than seen in either condition alone. These include a greater risk of falls, fractures and institutionalization, and significant socioeconomic costs. With our ageing population, osteosarcopenia is a public health concern that will become increasingly relevant in the future. Its aetiology is multifactorial, with mechanical, biochemical, genetic and lifestyle factors all contributing to involution of the 'bone-muscle unit'. Improved understanding of the interactions between muscle and bone could facilitate the development of new therapeutic agents which target muscle and bone as one. Together with existing pharmacological, nutritional and exercise-based therapies, this should enable a more holistic approach to osteosarcopenia in the future.

The Role of the Molecular Clock in Promoting Skeletal Muscle Growth and Protecting against Sarcopenia

The circadian clock has a critical role in many physiological functions of skeletal muscle and is essential to fully understand the precise underlying mechanisms involved in these complex interactions. The importance of circadian expression for structure, function and metabolism of skeletal muscle is clear when observing the muscle phenotype in models of molecular clock disruption. Presently, the maintenance of circadian rhythms is emerging as an important new factor in human health, with disruptions linked to ageing, as well as to the development of many chronic diseases, including sarcopenia. Therefore, the aim of this review is to present the latest findings demonstrating how circadian rhythms in skeletal muscle are important for maintenance of the cellular physiology, metabolism and function of skeletal muscle. Moreover, we will present the current knowledge about the tissue-specific functions of the molecular clock in skeletal muscle.

Correlation between lower limb isometric strength and muscle structure with normal and challenged gait performance in older adults

BACKGROUND

Muscular parameters have been considered to influence gait of older adults, but it is still unclear which specific lower limb muscular parameters correlate with kinematics of overground and obstacle crossing in older adults.

RESEARCH QUESTION

What lower limb muscular parameters correlate and explain kinematics of overground walking and obstacle crossing ability in the elderly?

METHODS

Muscle structure was evaluated in 15 older individuals (75.4 ± 5 years) through measures of architecture (muscle thickness, fascicle length, and pennation angle) and muscle quality (echo intensity) from lower limb muscles (vastus lateralis, biceps femoris, rectus femoris, tibialis anterior, and gastrocnemius medialis). Muscle function was assessed through isometric strength of hip, knee and ankle joint muscles. Gait kinematics (toe and heel clearances, step length and gait speed) was evaluated during walking with and without obstacle crossing at preferred and maximal gait speeds. Correlation and regression analyses were performed considering a significance level of 0.05.

RESULTS

Isometric strength did not correlate with gait kinematics and gait speed. Tibialis anterior thickness correlated with lead limb toe clearance, and vastus lateralis thickness with gait speed and step length. Vastus lateralis echo intensity correlated with step length and gait speed.

SIGNIFICANCE

Tibialis anterior and vastus lateralis muscles deserve attention in physical training to improve gait of older adults. Specifically, tibialis anterior should receive more attention on exercise programs aiming at improvement of obstacle crossing, and knee extensors when aiming at improving gait speed and step length.

Sarcopenia is an effective predictor of difficult-to-wean and mortality among critically ill surgical patients

BACKGROUND

Critically-ill surgical patients are at higher risk for sarcopenia, which is associated with worse survival. Sarcopenia may impair the respiratory musculature, which can subsequently influence the outcome of ventilator weaning. Although there are a variety of weaning parameters predictive of weaning outcomes, none have tried to incorporate "muscle strength" or "sarcopenia". The aim of the current study was to explore the association between sarcopenia and difficult-to-wean (DtW) in critically-ill surgical patients. The influence of sarcopenia on ICU mortality was also analyzed.

METHODS

Ninety-six patients undergoing mechanical ventilation in the surgical intensive care unit (ICU) were enrolled. Demographic data and weaning parameters were recorded from the prospectively collected database, and the total psoas muscle area (TPA) was determined at the level of the 3rd lumbar vertebra by computed tomography. Sarcopenia was defined by previously established cut-off points and its influence on clinical outcomes was examined. Receiver operating characteristic (ROC) curve analysis was conducted to investigate the predictive capability of TPA and weaning parameters for predicting weaning outcomes.

RESULTS

The median age of the studied patients was 73 years. Thirty patients (31.3%) were sarcopenic and 30 (31.3%) were defined as DtW. Eighteen patients (18.8%) had ICU mortality. Multivariate logistic regression analyses revealed that sarcopenia was an independent risk factor for DtW and ICU mortality. The area under the ROC curve (AUC) of TPA for predicting successful weaning was 0.727 and 0.720 in female and male patients, respectively. After combining TPA and conventional weaning parameters, the AUC for DtW increased from 0.836 to 0.911 and from 0.835 to 0.922 in female and male patients, respectively.

CONCLUSION

Sarcopenia is an independent risk factor for DtW and ICU mortality. TPA has predictive value when assessing weaning outcomes and can be used as an effective adjunct predictor along with conventional weaning parameters.

MicroRNAs as modulators of longevity and the aging process

MicroRNAs (miRNAs) are short, non-coding RNAs that post-transcriptionally repress translation or induce mRNA degradation of target transcripts through sequence-specific binding. miRNAs target hundreds of transcripts to regulate diverse biological pathways and processes, including aging. Many microRNAs are differentially expressed during aging, generating interest in their use as aging biomarkers and roles as regulators of the aging process. In the invertebrates Caenorhabditis elegans and Drosophila, a number of miRNAs have been found to both positive and negatively modulate longevity through canonical aging pathways. Recent studies have also shown that miRNAs regulate age-associated processes and pathologies in a diverse array of mammalian tissues, including brain, heart, bone, and muscle. The review will present an overview of these studies, highlighting the role of individual miRNAs as biomarkers of aging and regulators of longevity and tissue-specific aging processes.

Measuring muscle size and symmetry in healthy adult males using a time-efficient analysis of magnetic resonance images

OBJECTIVE

Muscle volume (MV) analysis from magnetic resonance imaging (MRI) is time-intensive, and limited measurement reliability data are available. This study investigated a method to reduce lower limb MV analysis time demands, established reliability of these measurements, and applied the findings to quantify muscle size and symmetry in healthy adult males.

APPROACH

Bilateral MRI images were acquired from 15 healthy males (age: 26.5  ±  4.6 years, height: 1.81  ±  0.09 m, body mass: 80.4  ±  12.4 kg) for the entire lower limb. In two participants, the individual gluteals, quadriceps, hamstrings, and triceps surae were manually outlined every 5 mm and MV calculated using 5, 10, 15, 20, 25, and 30 mm distances between images to determine an appropriate distance for reducing analysis time. For all 15 participants, 35 muscles in each limb were manually outlined every 15 mm for use in MV calculations. Reliability of muscle cross-sectional area (CSA) measurement was determined within- and between-sessions and MV measurement reliability determined between-sessions. Between-limb symmetry was calculated using symmetry indices.

MAIN RESULTS

A 15 mm inter-slice distance was appropriate for measuring MV (mean difference compared to reference method: 0.7%  ±  0.7%). Between-session measurement reliability was good for MV (Typical Error preferred kicking limb (TE_P): 1.2%, non-preferred kicking limb (TE_NP): 0.8%) and CSA (TE_P: 3.4%  ±  2.9%, TE_NP: 3.2%  ±  1.9%) although CSA Typical Error was larger with increased between-session time (TE_P: 4.1%  ±  3.1%, TE_NP: 4.7%  ±  4.0%). Between-limb differences in MV were small (mean symmetry index: 0.4%  ±  4.1%). Absolute differences in individual MV were larger (mean: 12.6%  ±  2.6%), but representing muscles as functional anatomical groups showed smaller absolute between-limb differences (mean: 4.7%  ±  1.8%).

SIGNIFICANCE

MV analysis time demand can be reduced by increasing the distance between analysed MRI slices, although participant height, muscle length and muscle shape require consideration. Small between-limb muscle size differences have been reported in adult males.

A New Threshold for Appendicular Lean Mass Discriminates Muscle Weakness in Women With Hip Fracture: A Cross-Sectional Study

OBJECTIVE

The aim of the study was to investigate the relationship between measures of muscle mass and grip strength in women with subacute hip fracture. Firstly, we aimed to assess the capability of the current thresholds for appendicular lean mass, appendicular lean mass/body mass index ratio and appendicular lean mass/height to separate weak and nonweak women. Secondly, we aimed to explore alternative thresholds for the three measures of muscle mass to discriminate weakness.

DESIGN

This is cross-sectional study of 160 women with hip fracture admitted to a rehabilitation hospital. We assessed appendicular lean mass by dual-energy x-ray absorptiometry and grip strength by a Jamar hand dynamometer. Weakness was defined as grip strength of less than 16 kg.

RESULTS

Weakness was not significantly associated with appendicular lean mass of less than 15.02 kg, appendicular lean mass/body mass index ratio of less than 0.512 or appendicular lean mass/height of less than 5.67 kg/m. For appendicular lean mass (but not for the other 2 measures of muscle mass), an alternative threshold (11.87 kg instead of 15.02 kg) significantly discriminated weakness: χ (1, n = 160) = 10.77 (P = 0.001). The association between appendicular lean mass of less than 11.87 kg and grip strength of less than 16 kg persisted after adjustment for age and body mass index (odds ratio = 2.50, 95% confidence interval = 1.17-5.34, P = 0.018).

CONCLUSIONS

Data suggest that the current thresholds for measures of muscle mass do not discriminate weakness in women with subacute hip fracture. For appendicular lean mass, an alternative cutoff point actually separated weak and nonweak women.

Nutritional status and body fat mass: Determinants of sarcopenia in community-dwelling older adults

BACKGROUND

Sarcopenia is defined as the old age syndrome characterized by profound decline in muscle mass and function. This study aimed to investigate the prevalence of sarcopenia and its risk factors in older adults.

METHODS

Totally, 501 older people aged 65 years and older were recruited. Sarcopenia was defined according to the criteria of the Asian Working Group for Sarcopenia (AWGS). For obtaining Skeletal Muscle mass Index (SMI), body composition was evaluated using Bioelectrical Impedance Analysis (BIA). Muscle strength and physical performance were measured by Handgrip Strength (HGS) and Gait Speed (GS), respectively. Nutritional status, physical activity level, and biochemical indicators were assessed, as well.

RESULTS

The prevalence of sarcopenia was 20.8%. Multiple logistic regression models of the predictors of decline in the components of sarcopenia showed that older age, low Body Mass Index (BMI), and serum albumin level were associated with a higher risk of low SMI. Low serum albumin level and older age were also predictive of low HGS. Besides, old age, high body fat mass, and low BMI were the risk factors of low GS. Conversely, increased Calf Circumference (CC) was protective against low SMI and GS. Finally, older age, male gender, low BMI, decreased mini-nutritional assessment score, low serum albumin level, and high body fat were associated with a higher risk of sarcopenia, whereas higher CC reduced its risk.

CONCLUSION

The prevalence of sarcopenia is high among elderly individuals. This study underlined that sarcopenia might develop in older adults with impaired nutritional status and high body fat mass. Further studies could evaluate the effects of appropriate nutritional interventions on sarcopenia management and prevention.

[Osteosarcopenia: A narrative review]

Osteosarcopenia is a phenotype resulting from the combination of sarcopenia and low bone mineral density. Based on the relationship between bone and muscle, this phenotype is associated with a higher risk of falls, fractures, dependence, and health care costs than its individual components. Given its characteristics, it can be considered as a new geriatric syndrome. Therefore, understanding its pathophysiology and diagnosis, as well as its non-pharmacological and pharmacological management is a task of great importance. The problem in addressing this phenotype arises from the tradition of managing sarcopenia and osteoporosis separately. There is also a lack of consensus on what to call it (sarco-osteopenia, sarco-osteoporosis, osteosarcopenia). The aim of this review is to outline the epidemiology, pathophysiology, diagnoses, adverse events, and management of osteosarcopenia.

Optimal Protein Intake during Weight Loss Interventions in Older Adults with Obesity

Obesity rates in people 60 years and older are increasing. While obesity is linked with detrimental health risks, weight loss in this population has previously been considered controversial due to potential worsening of age-related sarcopenia. Protein intake during energy restriction has been linked to lean body mass preservation. No formal guidelines for optimal protein intake during structured weight loss interventions exist for this population, but it appears that the current Recommended Dietary Allowance of 0.8 grams per kilogram of body weight per day may be inadequate. The purpose of this review is to discuss optimal protein intake during structured weight loss interventions in persons 60 years and older with obesity and to present a framework for guidelines to be used by health professionals focusing on weight loss interventions in older adults. Goals for the amount, source, and timing of protein intake, from both food and supplements, are presented and discussed.

Improved strength prediction combining clinically available measures of skeletal muscle mass and quality

BACKGROUND

Measures of skeletal muscle function decline at a faster rate with ageing than do indices of skeletal muscle mass. These observations have been attributed to age-related changes in muscle quality, another functional determinant separate from skeletal muscle mass. This study tested the hypothesis that improved predictions of skeletal muscle strength can be accomplished by combining clinically available measures of skeletal muscle mass and quality.

METHODS

The participants included 146 healthy adult (age ≥ 18 years, range 18-77 years; X ± SD 47 ± 17 years and body mass index 16.5-51.8 kg/m2 ; 27.7 ± 6.2 kg/m2 ) men (n = 60) and women (n = 86) in whom skeletal muscle mass was estimated as appendicular lean soft tissue (LST) measured by dual-energy X-ray absorptiometry and skeletal muscle quality as bioimpedance analysis-derived phase angle and B-mode-evaluated echogenicity of mid-thigh skeletal muscle. Strength of the right leg and both arms was quantified as knee isokinetic extension and handgrip strength using dynamometers. The statistical significance of adding phase angle or echogenicity to strength prediction multiple regression models that included extremity-specific LST and other covariates (e.g. age and sex) was evaluated to test the study hypothesis.

RESULTS

Right leg LST mass alone was significantly (P < 0.0001) correlated with isokinetic right leg strength (R2  = 0.57). The addition of segmental phase angle measured in the right leg at 50 kHz increased the R2 of this model to 0.66 (P < 0.0001); other phase angle frequencies (5 and 250 kHz) did not contribute significantly to these models. Results were similar for both right and left arm handgrip strength prediction models. Adding age and sex as model covariates increased the R2 values of these models further (e.g. right leg strength model R2 increased to 0.71), but phase angle continued to remain a significant (all P < 0.01) predictor of extremity strength. Similarly, when predicting isokinetic right leg strength, mid-thigh skeletal muscle echogenicity added significantly (P < 0.0001) to right leg LST, increasing R2 from 0.57 to 0.64; age was a significant (P < 0.0001) covariate in this model, increasing R2 further to 0.68.

CONCLUSIONS

The hypothesis of the current study was confirmed, strongly supporting and extending earlier reports by quantifying the combined independent effects of skeletal muscle mass and quality on lower-body and upper-body measures of strength. These observations provide a clinically available method for future research aimed at optimizing sarcopenia and frailty risk prediction models.

The Effect of Age upon the Interrelationship of BMI and Inpatient Health Outcomes

OBJECTIVES

There is growing evidence that the relationship between body mass index (BMI - defined as weight in kilograms divided by height in metres squared) and patient outcomes is age-dependent; specifically, a raised BMI may have a protective effect in older adults. This has been demonstrated clearly in the community setting; less clear is the effect of age on this relationship in the inpatient setting.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

Retrospective analysis of 22,903 electronic records for patients discharged from two large public hospitals in South Australia between January 2015 and September 2018 inclusively. Records were retained if the patient's height and weight had been recorded during the admission, BMI was between 10-99 kg/m2 and it was the patient's first admission during that time. Patients were grouped by BMI (<18.5 kg/m2 ("underweight"), 18.5-24.9 kg/m2 ("normal weight"), 25-29.9 kg/m2 ("overweight"), >30 kg/m2 ("obese")) and age (18-59 years, 60-79 years, > 80 years); for each group we measured the relative stay index (RSI) (actual length of stay divided by predicted length of stay), death in hospital and composite adverse outcome after discharge (unplanned readmission within 30 days and/or death within 30 days).

RESULTS

Underweight patients across all age groups generally experienced significantly poorer outcomes compared to those not underweight. In those aged 18-59 years there were no significant differences in outcomes between the normal weight, overweight and obese groups. In those aged 60-79 years overweight patients had a significantly reduced risk of RSI > 2 compared to those of normal weight (p=0.014), and both overweight and obese patients had a significantly reduced risk of adverse outcome after discharge when compared to those of normal weight (p=0.028 and p=0.009 respectively). In those aged 80 years or older, both overweight and obese patients had a significantly reduced risk of adverse outcome after discharge when compared to those of normal weight (p=0.028 and p=0.013 respectively), and obese patients had a significantly reduced risk of inpatient mortality and RSI >2 when compared to those of normal weight (p=0.027 and p=0.037 respectively).

CONCLUSION

A BMI > 25 kg/m2 in older patients is associated with reduced risk of prolonged admission, inpatient mortality and adverse outcomes following discharge. This adds to growing evidence that age-specific BMI guidelines are required for adults because the healthiest BMI in the older hospital patient is seemingly not in the range 18.5-24.9 kg/m2.

Cellular and molecular mechanisms of sarcopenia: the S100B perspective

Primary sarcopenia is a condition of reduced skeletal muscle mass and strength, reduced agility, and increased fatigability and risk of bone fractures characteristic of aged, otherwise healthy people. The pathogenesis of primary sarcopenia is not completely understood. Herein, we review the essentials of the cellular and molecular mechanisms of skeletal mass maintenance; the alterations of myofiber metabolism and deranged properties of muscle satellite cells (the adult stem cells of skeletal muscles) that underpin the pathophysiology of primary sarcopenia; the role of the Ca²⁺ -sensor protein, S100B, as an intracellular factor and an extracellular signal regulating cell functions; and the functional role of S100B in muscle tissue. Lastly, building on recent results pointing to S100B as to a molecular determinant of myoblast-brown adipocyte transition, we propose S100B as a transducer of the deleterious effects of accumulation of reactive oxygen species in myoblasts and, potentially, myofibers concurring to the pathophysiology of sarcopenia.

Sarcopenia is associated with the neutrophil/lymphocyte and platelet/lymphocyte ratios in operable gastric cancer patients: a prospective study

Purpose

Sarcopenia is distinguished by decreased skeletal muscle plus low muscle strength and/or physical performance. This study was designed to demonstrate the relationship between sarcopenia and systemic inflammatory response (neutrophil/lymphocyte ratio [NLR], platelet/lymphocyte ratio [PLR], and large platelet/lymphocyte ratio [LPLR]) prior to radical gastrectomy for gastric cancer.

Patients and methods

We conducted a prospective study of gastric cancer patients who underwent radical gastrectomy. The clinical utility of the NLR, PLR, and LPLR was evaluated by receiver operating characteristic curves. Sarcopenia components including skeletal muscle index, handgrip strength, and 6 m usual gait speed were measured. Logistic analysis was used to identify the independent indices associated with sarcopenia.

Results

A total of 670 patients were included, representing 504 men and 166 women. Of these, 104 patients (15.5%) were diagnosed with sarcopenia and 567 (84.5%) were non-sarcopenia. PLR has a diagnostic sensitivity of 91.3% for sarcopenia. In addition to the indicators of preoperative age, nutritional risk screening, body mass index, preoperative albumin, and diabetes, the NLR and PLR were independent predictors for sarcopenia (P<0.05).

Conclusion

The present study showed that at-diagnosis sarcopenia was associated with inflammation in patients with operable gastric cancer. Due to the complex assessment of muscle condition, PLR may be used as a primary screening test for sarcopenia. How systemic inflammatory response influences changes in sarcopenia may provide new therapeutic perception toward improving outcomes.

Sarcopenia as a predictor of hospitalization among older people: a systematic review and meta-analysis

Background

Previous cohort studies investigating the association between sarcopenia and the risk of hospitalization have been inconsistent. We performed a meta-analysis to determine if sarcopenia is a predictor of hospitalization.

Methods

Prospective cohort studies that evaluated the association between sarcopenia and hospitalization in older people were identified via a systematic search of four electronic databases (PubMed, EMBASE, Science Citation Index, and the Cochrane Library). A random-effect model was applied to combine the results according to the heterogeneity of the included studies.

Results

Five studies (2832 participants) were included in this meta-analysis. Pooled results demonstrated that older people with sarcopenia were at an increased risk of hospitalization (pooled hazards ratio [HR] = 1.57, 95% confidence interval [CI] = 1.26, 1.94, I² = 4.5%, P = 0.000) compared to those without sarcopenia. Results of subgroup analyses showed that hospitalized patients with sarcopenia had a higher rate of hospitalization (HR = 2.01, 95% CI = 1.41, 2.88, p = 0.000) versus patients without sarcopenia. A similar result was also found in community-dwelling older people with sarcopenia versus those without sarcopenia (HR = 1.40, 95% CI = 1.05, 1.88, p = 0.023). In addition, the subgroup analysis for length of follow-up showed that studies with a follow-up period of 3 years or more (pooled HR = 1.52, 95% CI = 1.19, 1.94, P = 0.001) reported a significantly higher rate of hospitalization among individuals with sarcopenia compared to those without sarcopenia. However, this association was not found in the studies with a follow-up period of less than 3 years (pooled HR = 1.76, 95% CI = 0.90, 3.44, P = 0.099).

Conclusions

Sarcopenia is a significant predictor of hospitalization among older individuals, and the association may not be significantly affected by the characteristics of the population or the definition of sarcopenia.

Electronic supplementary material

The online version of this article (10.1186/s12877-018-0878-0) contains supplementary material, which is available to authorized users.

Developing sarcopenia criteria and cutoffs for an older Caucasian cohort - a strictly biometrical approach

Background

The aim of this strictly statistical approach was to provide a figure discrimination in a homogeneous cohort that is based on a main component, which includes disability, physical performance, and autonomy parameters.

Methods

We used data of 939 community-dwelling men aged ≥70 years, living in the area of Erlangen-Nürnberg, Germany. Briefly, we conducted a scaled principal component analysis based on criteria related to "physical function", "disability", "weakness", and "autonomy" to identify men who are likely to have sarcopenia as per the recognized sarcopenia criteria. Next, we applied fast-and-frugal decision trees, logistic regression, and classification and regression decision trees to classify men with and without sarcopenia, applying the 5% prevalence rate identified for this cohort by recent studies.

Results

In summary, the best fast-and-frugal decision trees included gait velocity, handgrip strength, and two skeletal muscle mass indices (SMI) - appendicular skeletal muscle mass (ASMM)/body mass index (BMI) and ASMM/height². Briefly, men below the cutoff point of 1.012 m/s for gait velocity were directly classified as sarcopenic. Faster men with a handgrip strength of >34.5 kg were excluded from further screening, while their weaker peers were assessed for SMI. Firstly, an ASMM/BMI-based exclusion criterion of >0.886 indicates no sarcopenia; while in men with a lower BMI-based SMI, an ASMM/height² of <7.25 kg/m² indicates sarcopenia. Of importance, about 72% of the participants can be classified without an SMI assessment.

Conclusion

The present approach that applied recognized sarcopenia criteria and was based on a predominately functional understanding of sarcopenia provided a simple and feasible decision rule for sarcopenia discrimination. In summary, we consider our approach as a strictly biometrical contribution within the development of sarcopenia screening methods. However, our tool needs to be further evaluated to validate its appropriateness to discriminate sarcopenia in this relevant cohort.

[Becoming older with axial spondyloarthritis]

The combination of physiological age-related changes (e. g. reduction in muscle mass and function, reduction in organ function and degenerative changes in joints) and disease-specific changes of ankylosing spondylitis (AS), make older AS patients vulnerable for additional diseases. In this patient population various processes lead to a reduction in physical function, changes in posture, osteoporosis and sarcopenia, which then can result in falls and fractures, especially vertebral fractures. Mortality is increased in patients with AS, particularly in men due to an increase in cardiovascular mortality. Although the standardized assessment of cardiovascular risk factors in patients with inflammatory rheumatic diseases (independent of age) has been recommended for years, it is rarely done in clinical practice. Overall, data on comorbidities and risk factors are only available for AS patients and are lacking for other forms of spondyloarthritides.

[Muscle mass measurement by DXA and MRI in non-human primates]

The global population is aging rapidly and, in Japan, the number of elderly has been steadily rising. It is important to shrink the gap between the average lifespan and the number of years people can expect to remain healthy. This links with improving the quality of life for the elderly and reducing social welfare spending. Maintaining motor function is believed to be a key to extending the number of years a person remains healthy, but recent years have seen a rise in locomotive syndrome. Decreases in muscle mass with age, and the deterioration in motor functions leads to sarcopenia. However, there is a dearth of medicines for increasing muscle mass or muscular strength. In this study, we used non-human primates (NHPs), which have similar anatomical features to humans and have advanced functional differentiation between the fore- and hindlimbs, to examine a highly accurate method of measuring muscle mass using Magnetic Resonance Imaging (MRI) and compared it to Dual Energy X-ray Absorptiometry (DXA) usually used in clinical settings. The results showed that both MRI and DXA provided high repeatability. Furthermore, correlation analysis between the amount of excised muscle for measurement and the results from MRI and DXA showed a high correlation at all sites examined, with the correlation coefficient higher for MRI than for DXA. We expect that the establishment of a highly accurate method for measurement of muscle mass using MRI and DXA will give impetus to the development of drugs that target muscle mass.