Sarcopenia: definition, epidemiology, and pathophysiology

The Molecular Mechanisms and Prevention Principles of Muscle Atrophy in Aging

Muscle atrophy in aging is characterized by progressive loss of muscle mass and function. Muscle mass is determined by the balance of synthesis and degradation of protein, which are regulated by several signaling pathways such as ubiquitin-proteasome system, autophagy-lysosome systems, oxidative stress, proinflammatory cytokines, hormones, and so on. Sufficient nutrition can enhance protein synthesis, while exercise can improve the quality of life in the elderly. This chapter will discuss the epidemiology, pathogenesis, as well as the current treatment for aging-induced muscular atrophy.

Sarcopenia in Liver Disease: Current Evidence and Issues to Be sResolved

Sarcopenia is a common clinical symptom in aging and patients with wasting diseases, characterized by a decreased skeletal muscle mass. As a consequence of lifestyle change, the nonalcoholic fatty liver disease (NAFLD) presents a rising trend. In the past three decades, increasing evidence has proved that sarcopenia is related to NAFLD. In this chapter, we will summarize the emerging evidence of the predictive role of sarcopenia in NAFLD and review the diagnosis value, feasible mechanism, and therapy strategies of sarcopenia in NAFLD. Sarcopenia is a potential risk factor for NAFLD, and targeting sarcopenia can benefit NAFLD to some extent.

Relative muscle mass and the risk of incident type 2 diabetes: A cohort study

Aims

The association between relative muscle mass (RMM) and incidence of type 2 diabetes (T2DM) is largely unknown. We examined whether RMM predicted development of T2DM in an apparently young healthy population.

Methods

This cohort study was comprised of 113,913 men and 89,854 women, free of T2DM at baseline, who underwent a health checkup examination and were followed-up annually or biennially for an average of 2.9 years. We used skeletal muscle mass index (SMI) as an indicator of RMM. SMI (%) [total skeletal muscle mass (kg)/body weight (kg)×100] was estimated using a bioelectrical impedance analyzer. The study outcome was incident T2DM, defined as fasting serum glucose ≥126 mg/dL, HbA1C ≥6.5%, or use of medication for T2DM.

Results

During 589,098.8 person-years of follow-up, 4,264 individuals developed T2DM (incidence rate, 7.2 per 1000 person-years). Median age (range) at baseline was 39.1 years (18.1–87.1). RMM was negatively associated with incidence of T2DM in a dose-response manner. The multivariate-adjusted hazard ratios (95% CIs) for incident T2DM comparing quartiles 3, 2 and 1 of RMM to the highest quartile were 1.32 (1.14–1.52), 1.63 (1.42–1.86), and 2.21 (1.94–2.51), respectively, for males and 1.18 (0.88–1.58), 1.46 (1.11–1.91), and 1.96 (01.51–2.53) for females (P for trend <0.001; 0.011). This association was stronger in younger or premenopausal subjects.

Conclusions

RMM was negatively associated with development of T2DM in a large sample of young and middle-aged Korean adults. Further research is required to determine whether preservation of muscle mass through intervention affects the risk of T2DM.

Sarcopenia in chronic obstructive pulmonary disease: A study of prevalence and associated factors in the Southeast Asian population

Chronic obstructive pulmonary disease (COPD) has been described as a systemic disease. Sarcopenia is one of the systemic effects that is related to several adverse outcomes. The objectives of this study were to estimate the prevalence of sarcopenia and to determine the factors associated with sarcopenia in COPD patients in Southeast Asia. This was a cross-sectional study of COPD patients who attended a COPD clinic from May 2015 to December 2016. Baseline characteristics were collected and dual-energy X-ray absorptiometry was used to measure skeletal muscle mass. Handgrip strength was used to assess muscle strength, and as a measurement of physical performance, the 6-min walk distance was used. One hundred and twenty-one participants were recruited. Most of them were men (92.6%). Prevalence of sarcopenia was 24% (29 cases). Independent factors associated with sarcopenia were age ≥ 75 years (adjusted odds ratio (AOR) 13.3, severity of COPD (AOR 19.2 and 13.4 for moderate and severe COPD), Modified Medical Research Council (MMRC) scale (AOD 1.9), and obesity (AOR 0.04). Sarcopenia affects about one-quarter of COPD patients. Age, severity of COPD, MMRC scale, and BMI status were the factors associated with sarcopenia.

Epidemiology of Joint Dislocations and Ligamentous/Tendinous Injuries among 2,700 Patients: Five-year Trend of a Tertiary Center in Iran

BACKGROUND

The epidemiology of traumatic dislocations and ligamentous/tendinous injuries is poorly understood. In this study, we aimed to evaluate the prevalence and distribution of various dislocations and ligamentous/tendinous injuries in a tertiary orthopedic hospital in Iran.

METHODS

Musculoskeletal injuries in an academic tertiary health care center in Tehran February 2005 to October 2010 were recorded. The demographic details of patients with pure dislocations and ligamentous/tendinous injuries were extracted and the type and site of injuries were classified according to their specific age/gender groups.

RESULTS

Among 18,890 admitted patients, 628 (3.3%) were diagnosed with dislocations and 2.081 (11%) with ligamentous/tendinous injuries. The total male/female ratio was 4.2:1 in patients with dislocations and 1.7:1 in patients with ligamentous/tendinous injuries. Shoulder was the most prevalent site of dislocation (50.6%), followed by fingers (10.1%), toes (7.6%), hip (7.3%), and elbow (6.5%). Ankle was the most common site of ligamentous/tendinous injury (53.5%), followed by midfoot (12.3%), knee (8.3%), hand (7%), and shoulder (5%). The mean ages of the patients in dislocations and ligamentous/tendinous injuries were 35.0±18.2 and 31.3± 15.1, respectively. There was no seasonal variation.

CONCLUSION

Shoulder dislocation and ankle ligamentous injury are the most frequent injuries especially in younger population and have different distribution patterns in specific age and sex groups. Epidemiologic studies can help develop and evaluate the injury prevention strategies, resource allocation, and training priorities.

Skeletal muscle aging: influence of oxidative stress and physical exercise

Skeletal muscle abnormalities are responsible for significant disability in the elderly. Sarcopenia is the main alteration occurring during senescence and a key public health issue as it predicts frailty, poor quality of life, and mortality. Several factors such as reduced physical activity, hormonal changes, insulin resistance, genetic susceptibility, appetite loss, and nutritional deficiencies are involved in the physiopathology of muscle changes. Sarcopenia is characterized by structural, biochemical, molecular and functional muscle changes. An imbalance between anabolic and catabolic intracellular signaling pathways and an increase in oxidative stress both play important roles in muscle abnormalities. Currently, despite the discovery of new targets and development of new drugs, nonpharmacological therapies such as physical exercise and nutritional support are considered the basis for prevention and treatment of age-associated muscle abnormalities. There has been an increase in information on signaling pathways beneficially modulated by exercise; nonetheless, studies are needed to establish the best type, intensity, and frequency of exercise to prevent or treat age-induced skeletal muscle alterations.

Higher Protein Intake Does Not Improve Lean Mass Gain When Compared with RDA Recommendation in Postmenopausal Women Following Resistance Exercise Protocol: A Randomized Clinical Trial

The aim of this study was to evaluate the effect of a higher protein intake on lean body mass (LBM) gain in postmenopausal women practicing resistance exercise and compare it to the Recommended Dietary Allowance (RDA) recommendation. Twenty-three postmenopausal women (63.2 ± 7.8 years) were randomized into two groups. The group with higher protein intake (n = 11) (HP) received a dietary plan with ~1.2 g·kg^-1·day^-1 of protein, while the normal protein (NP) group (n = 12) was instructed to ingest ~0.8 g·kg^-1·day^-1 of protein (RDA recommendation). Both groups performed the same resistance training protocol, 3 times a week, with progression of the number of sets (from 1 to 6 sets) and 8-12 repetitions. The intervention occurred over 10 weeks. Body composition evaluation was performed by dual-energy X-ray absorptiometry. The diet was evaluated by nine 24-h food recall summaries over the course of the study. During the intervention period, the HP group presented a higher protein (1.18 ± 0.3 vs. 0.87 ± 0.2 g·kg^-1·day^-1, p = 0.008) and leucine (6.0 ± 1.4 vs. 4.3 ± 0.9 g/day, p < 0.001) intake than the NP group, respectively. At the end of the intervention, there were increases in LBM both in HP (37.1 ± 6.2 to 38.4 ± 6.5 kg, p = 0.004) and in NP (37.6 ± 6.2 to 38.8 ± 6.4 kg, p < 0.001), with no differences between the groups (p = 0.572). In conclusion, increased protein intake did not promote higher LBM gain when compared to RDA recommendation in postmenopausal women performing resistance exercise during 10 weeks. This trial was registered at ClinicalTrials.gov as NCT03024125.

Quantification and characterization of grouped type I myofibers in human aging

INTRODUCTION

Myofiber type grouping is a histological hallmark of age-related motor unit remodeling. Despite the accepted concept that denervation-reinnervation events lead to myofiber type grouping, the completeness of those conversions remains unknown.

METHODS

Type I myofiber grouping was assessed in vastus lateralis biopsies from Young (26 ± 4 years; n = 27) and Older (66 ± 4 years; n = 91) adults. Grouped and ungrouped type I myofibers were evaluated for phenotypic differences.

RESULTS

Higher type I grouping in Older versus Young was driven by more myofibers per group (i.e., larger group size) (P < 0.05). In Older only, grouped type I myofibers displayed larger cross-sectional area, more myonuclei, lower capillary supply, and more sarco(endo)plasmic reticulum calcium ATPase I (SERCA I) expression (P < 0.05) than ungrouped type I myofibers.

DISCUSSION

Grouped type I myofibers retain type II characteristics suggesting that conversion during denervation-reinnervation events is either progressive or incomplete. Muscle Nerve 57: E52-E59, 2018.

Obesity as predictor of postoperative outcomes in liver transplant candidates: Review of the literature and future perspectives

BACKGROUND

Current American and European guidelines consider a pre-transplant BMI ≥40kg/m2 as a relative contraindication for liver transplantation but this recommendation is graded as uncertain and requires further research. Moreover, conflicting results are reported on the predictive value of BMI 30-39.9kg/m2 on post-transplant complication and mortality risk.

AIM

This study analyzed the data of the literature on the effect of all three BMI classes of obesity on postoperative outcomes in liver transplantation.

MATERIALS AND METHODS

A PubMed and Cochrane Library search was conducted from inception to October 2015.

RESULTS

Analysis of the literature demonstrates that discrepancies among studies are mainly either due to limitations of BMI per se, the different BMI cut-offs used to select patients with obesity or reference group and the different outcomes considered. Moreover, the evaluation of visceral adipose tissue and the detrimental effect of muscle mass reduction in presence of obesity are never considered.

CONCLUSIONS

BMI assessment should be used as a preliminary method to evaluate obesity. Subsequently, the assessment of visceral adipose tissue and muscle mass should complete the preoperative evaluation of liver transplant candidates. This innovative approach could represent a new field of research in liver transplantation.

Gender difference in the association between lower muscle mass and metabolic syndrome independent of insulin resistance in a middle-aged and elderly Taiwanese population

BACKGROUND

Loss of muscle mass was reported to be associated with metabolic syndrome (MetS), but little is known about the gender difference. Thus, the aim of this study was to evaluate the relationship between lower muscle mass and MetS and determine whether there was any gender difference or not.

METHODS

A total of 394 middle-aged and elderly Taiwanese adults (138 males and 256 females) were enrolled and completed our health survey. They were stratified into three groups according to appendicular skeletal muscle mass divided by weight. Participants distributed into the lower tertile were defined as people having lower muscle mass. MetS was defined using the Adult Treatment Panel III Asian diagnostic criteria. Multivariate logistic regression analysis was performed to assess the association between muscle and MetS.

RESULTS

We found an inverse association between MetS and muscle mass in both males and females. Participants with lower muscle mass had a higher risk of MetS in univariate analysis. The same results were observed when adjusted for age and when also adjusted for living condition factors. However, after additional adjustment for potential confounders and HOMA-IR, we only found it to be statistically significant in the female group (OR in male=3.60; 95% CI=0.62-20.83, p=0.153; OR in female=3.03; 95% CI=1.16-7.94, p=0.024).

CONCLUSIONS

We examined the relationship between lower muscle mass and metabolic syndrome in a middle-aged and elderly Taiwanese population. We found that lower muscle mass was associated with the risk of metabolic syndrome in the aged, particularly in females.

Presence of sarcopenia in asthma-COPD overlap syndrome may be a risk factor for decreased bone-mineral density, unlike asthma: Korean National Health and Nutrition Examination Survey (KNHANES) IV and V (2008-2011)

Background

Sarcopenia and decreased bone-mineral density (BMD) are common in elderly people, and are major comorbidities of obstructive airway disease (OAD). However, the relationship between sarcopenia and BMD in each OAD phenotype, especially asthma–COPD overlap syndrome (ACOS), is not yet clear. We aimed to evaluate differences in BMD according to the presence of sarcopenia in each OAD phenotype.

Materials and methods

Among the research subjects in KNHANES IV and V (2008–2011), 5,562 were ≥50 years old and underwent qualified spirometry and dual-energy X-ray absorptiometry. A total of 947 subjects were included in the study: 89 had asthma, 748 COPD, and 110 ACOS.

Results

In the COPD and ACOS phenotypes, T-scores were lower in the sarcopenia group than the nonsarcopenia group. Prevalence rates of osteopenia and osteoporosis were higher in the sarcopenia group than the nonsarcopenia group. (P<0.001 and P=0.017, respectively). The sarcopenia group had higher risks of developing osteopenia, osteoporosis, and low BMD than the nonsarcopenia group in the ACOS phenotype (OR 6.620, 95% CI 1.129–38.828 [P=0.036], OR 9.611, 95% CI 1.133–81.544 [P=0.038], and OR 6.935, 95% CI 1.194–40.272 [P=0.031], respectively). However, in the asthma phenotype, the sarcopenia group showed no increased risk compared with the nonsarcopenia group.

Conclusion

In the ACOS phenotype, individuals with sarcopenia had a higher prevalence rate and higher risks of osteopenia and osteoporosis than those without sarcopenia among all OAD phenotypes.

Systematic review with meta-analysis: post-operative complications and mortality risk in liver transplant candidates with obesity

BACKGROUND

International guidelines rate class III (morbid) obesity (body mass index [BMI]≥40 kg/m2 ) as a relative contraindication for liver transplantation (LT) requiring further research. Moreover, data on the mortality risk in candidates with a BMI: 30-34.9 and 35-39.9 kg/m2 (class I and class II obesity, respectively) are weak.

AIM

To compare post-operative complications and mortality risks in all obese candidates vs candidates with a BMI: 18.5-29.9 (normal/overweight) assumed as controls.

METHODS

We searched the Cochrane library, PubMed, Scopus, Web-of-Science and article reference lists, restricted to the English language, and selected cohort studies analysing the following outcomes: all-causes mortality (at 30 days, 1-2-3-5 years), post-operative and cardiopulmonary complications, hospital and intensive care unit (ICU) length of stay. Two reviewers independently extracted the studies data and a third one resolved discrepancies.

RESULTS

Twenty-four studies comprising 132 162 patients met the inclusion criteria. As compared to controls, mortality risk was increased at all time-periods (except at 3 years) for a BMI≥40, at 30 days for a BMI: 30-34.9 and in none of the considered time-periods for a BMI: 35-39.9. Post-operative complications were significantly higher for a BMI>30 and 30-34.9. Due to the shortage/absence of data, we evaluated cardiopulmonary complications, hospital and ICU length of stay only in the BMI≥30 category. In these patients, only cardiopulmonary complications were increased as compared to controls.

CONCLUSIONS

Morbid obesity has an impact on patients' survival after LT. However, since even a BMI>30 increases post-transplant complications, new strategies should be included in the LT programme to favour weight loss in all obese candidates.

Targeting NAD+ in Metabolic Disease: New Insights Into an Old Molecule

Nicotinamide adenine dinucleotide (NAD+) is an established cofactor for enzymes serving cellular metabolic reactions. More recent research identified NAD+ as a signaling molecule and substrate for sirtuins and poly-adenosine 5'-diphosphate polymerases; enzymes that regulate protein deacetylation and DNA repair, and translate changes in energy status into metabolic adaptations. Deranged NAD+ homeostasis and concurrent alterations in mitochondrial function are intrinsic in metabolic disorders, such as type 2 diabetes, nonalcoholic fatty liver, and age-related diseases. Contemporary NAD+ precursors show promise as nutraceuticals to restore target tissue NAD+ and have demonstrated the ability to improve mitochondrial function and sirtuin-dependent signaling. This review discusses the accumulating evidence for targeting NAD+ metabolism in metabolic disease, maps the different strategies for NAD+ boosting, and addresses the challenges and open questions in the field. The health potential of targeting NAD+ homeostasis will inform clinical study design to identify nutraceutical approaches for combating metabolic disease and the unwanted effects of aging.

Panoramic ultrasound: a novel and valid tool for monitoring change in muscle mass

BACKGROUND

The strong link between reduced muscle mass and morbidity and mortality highlights the urgent need for simple techniques that can monitor change in skeletal muscle cross-sectional area (CSA). Our objective was to examine the validity of panoramic ultrasound to detect change in quadriceps and gastrocnemius size in comparison with magnetic resonance imaging (MRI) in subjects randomized to 70 days of bed rest (BR) with or without exercise.

METHODS

Panoramic ultrasound and MRI images of the quadriceps and gastrocnemius muscles were acquired on the right leg of 27 subjects (26 male, 1 female; age: 34.6 ± 7.8 years; body mass: 77.5 ± 10.0 kg; body mass index: 24.2 ± 2.8 kg/m² ; height: 179.1 ± 6.9 cm) before (BR-6), during (BR3, 7, 11, 15, 22, 29, 36, 53, 69), and after (BR+3, +6, +10) BR. Validity of panoramic ultrasound to detect change in muscle CSA was assessed by Bland-Altman plots, Lin's concordance correlation coefficient (CCC), sensitivity, specificity, positive predictive value, and negative predictive value.

RESULTS

Six hundred ninety-eight panoramic ultrasound CSA and 698 MRI CSA measurements were assessed. Concordance between ultrasound and MRI was excellent in the quadriceps (CCC: 0.78; P < 0.0001), whereas there was poor concordance in the gastrocnemius (CCC: 0.37; P < 0.0006). Compared with MRI, panoramic ultrasound demonstrated high accuracy in detecting quadriceps atrophy and hypertrophy (sensitivity: 73.7%; specificity: 74.2%) and gastrocnemius atrophy (sensitivity: 83.1%) and low accuracy in detecting gastrocnemius hypertrophy (specificity: 33.0%).

CONCLUSIONS

Panoramic ultrasound imaging is a valid tool for monitoring quadriceps muscle atrophy and hypertrophy and for detecting gastrocnemius atrophy.

Frailty syndrome in ambulatory patients with COPD

Frailty is a state of increased risk of unfavorable outcomes when exposed to stressors, and COPD is one of the several chronic illnesses associated with the condition. However, few studies have been conducted regarding the prevalence of COPD and its related factors in Southeast Asia. The objectives of this study were to determine the prevalence of frailty in COPD patients and to identify the associated factors in these populations. A cross-sectional study of COPD patients who attended a COPD clinic was conducted from May 2015 to December 2016. Baseline characteristics were collected, and the diagnosis of frailty was based on the FRAIL (fatigue, resistance, ambulation, illnesses, and loss of weight) scale. Descriptive statistics were used to analyze baseline data. Factors associated with frailty were analyzed using univariate and multivariate regression analyses. The results showed that the prevalence rates of frailty and pre-frailty were 6.6% (eight out of 121 cases) and 41.3% (50 out of 121 cases), respectively, among COPD patients. Fatigue was the most common component of the FRAIL scale that was found more frequently in frail patients than in non-frail patients (odds ratio [OR] 91.9). Factors associated with frailty according to multivariate analyses were comorbid cancer (adjusted OR [AOR] 45.8), at least two instances of nonelective admission over the past 12 months (AOR 112.5), high waist circumference (WC) (AOR 1.3), and presence of sarcopenia (AOR 29.5). In conclusion, frailty affected 6.6% of stable COPD patients. Cancer, two or more instances of nonelective hospitalization over the past 12 months, high WC, and presence of sarcopenia were associated with frailty. Early identification and intervention in high-risk patients is recommended to prevent or delay the adverse outcomes of frailty.

Impact of sarcopenia in the management of urological cancer patients

INTRODUCTION

Sarcopenia, the degenerative and systemic loss of skeletal muscle mass, develops as a consequence of the progression of cancer cachexia. Recent studies suggest that sarcopenia may be used as a biomarker in the management of patients with several cancers. Areas covered: In this article, the authors review 1) the methods to simply and optimally evaluate and define sarcopenia using computed tomography images in daily clinical practice and 2) the impact of sarcopenia in the management of urological cancers, specifically focusing on the usefulness in predicting treatment-related complications and prognosis. The authors also discuss the prognostic importance of changes in skeletal muscle mass in the course of treatment and the potential roles of nutritional support and exercise to prevent progression of sarcopenia. Expert commentary: Sarcopenia is associated with treatment-related complications and unfavorable prognosis in urological cancer patients. Nutritional support and exercise might be helpful in improving sarcopenia. The impact of these interventions on clinical outcomes would be elucidated by ongoing or future clinical studies.

Clinical impact of sarcopenia on prognosis in pancreatic ductal adenocarcinoma: A retrospective cohort study

OBJECTIVES

To investigate the impact of the body composition such as skeletal muscle, visceral fat and body mass index (BMI) on patients with resected pancreatic ductal adenocarcinoma (PDAC).

METHODS

A total of 265 patients who underwent curative surgery for PDAC were examined in this study. The total skeletal muscle and fat tissue areas were evaluated in a single image obtained at the third lumber vertebra during a preoperative computed tomography (CT) scan. The patients were assigned to either the sarcopenia or non-sarcopenia group based on their skeletal muscle index (SMI) and classified into high visceral fat area (H-VFA) or low VFA (L-VFA) groups. The association of clinicopathological features and prognosis with the body composition were statistically analyzed.

RESULTS

There were 170 patients (64.2%) with sarcopenia. The median survival time (MST) was 23.7 months for sarcopenia patients and 25.8 months for patients without sarcopenia. The MST was 24.4 months for H-VFA patients and 25.8 months for L-VFA patients. However, sarcopenia patients with BMI ≥22 exhibited significantly poorer survival than patients without sarcopenia (MST: 19.2 vs. 35.4 months, P = 0.025). There was a significant difference between patients with and without sarcopenia who did not receive chemotherapy (5-year survival rate: 0% vs. 68.3%, P = 0.003). The multivariate analysis revealed that tumor size, positive dissected peripancreatic tissue margin, and sarcopenia were independent prognostic factors.

CONCLUSIONS

Sarcopenia is an independent prognostic factor in PDAC patients with a BMI ≥22. Therefore, evaluating skeletal muscle mass may be a simple and useful approach for predicting patient prognosis.

Dietary proteins and amino acids in the control of the muscle mass during immobilization and aging: role of the MPS response

Dietary proteins/essential amino acids (EAAs) are nutrients with anabolic properties that may increase muscle mass or attenuate muscle loss during immobilization and aging via the stimulation of muscle protein synthesis (MPS). An EAA's anabolic threshold, capable to maximize the stimulation of MPS has been hypothesized, but during certain conditions associated with muscle loss, this anabolic threshold seems to increase which reduces the efficacy of dietary EAAs to stimulate MPS. Preliminary studies have demonstrated that acute ingestion of dietary proteins/EAA (with a sufficient amount of leucine) was capable to restore the postprandial MPS during bed rest, immobilization or aging; however, whether these improvements translate into chronic increases (or attenuates loss) of muscle mass is equivocal. For example, although free leucine supplementation acutely increases MPS and muscle mass in some chronic studies, other studies have reported no increases in muscle mass following chronic leucine supplementation. In contrast, chronically increasing leucine intake via the consumption of an overall increase in dietary protein appears to be the most effective dietary intervention toward increasing or attenuating lean mass during aging; however, more research investigating the optimal dose and timing of protein ingestion is necessary. Several studies have demonstrated that decreases in postprandial MPS as a result of increased circulating oxidative and inflammatory are more responsible than muscle protein breakdown for the decreases in muscle mass during disuse and health aging. Therefore, nutritional interventions that reduce oxidation or inflammation in conjunction with higher protein intakes that overcome the anabolic resistance may enhance the MPS response to feeding and either increase muscle mass or attenuate loss. In preliminary studies, antioxidant vitamins and amino acids with antioxidant or anti-inflammatory properties show potential to restore the anabolic response associated with protein ingestion. More research, however, is required to investigate if these nutrients translate to increases in MPS and, ultimately, increased lean mass in aging humans. The purpose of the present review is to discuss the role of protein/EAA intake to enhance postprandial MPS during conditions associated with muscle loss, and bring new perspectives and challenges associated nutritional interventions aimed to optimize the anabolic effects of dietary protein/EAAs ingestion.

Decreasing skeletal muscle as a risk factor for mortality in elderly patients with sepsis: a retrospective cohort study

Background

Older patients account for the majority of patients with sepsis. The objective of this study was to determine if decreased skeletal muscle mass is associated with outcomes in elderly patients with sepsis.

Methods

Patients (60 years and older) who were admitted to a tertiary medical center intensive care unit with a primary diagnosis of sepsis between January 2012 and February 2016 were included. Patients who had not undergone abdominal computed tomography on the day of admission, had cardiopulmonary arrest on arrival, or had iliopsoas abscess were excluded from the analyses. Cross-sectional muscle area at the 3rd lumber vertebra was quantified, and the relation to in-hospital mortality was analyzed. Multivariable logistic regression analysis that included sex and APACHE II score as explanatory variables was performed. The optimal cutoff value to define decreased muscle mass (sarcopenia) was calculated using receiver operating characteristic curve analysis, and the odds ratio for in-hospital mortality was determined.

Results

There were 150 elderly patients with sepsis (median age, 75 years) enrolled; in-hospital mortality and median APACHE II score were 38.7 and 24%, respectively. The skeletal muscle area of deceased patients was significantly lower than that of the survival group (P < 0.001). The multivariable logistic regression analysis demonstrated that decreased muscle mass was significantly associated with increased mortality (odds ratio = 0.94, 95% confidence interval = 0.90 to 0.97, P < 0.001). The optimal cutoff value of skeletal muscle area to predict in-hospital mortality was 45.2 cm² for men and 39.0 cm² for women. With these cutoff values, the adjusted odds ratio for decreased muscle area was 3.27 (95% CI, 1.61 to 6.63, P = 0.001).

Conclusions

Less skeletal muscle mass is associated with higher in-hospital mortality in elderly patients with sepsis. The results of this study suggest that identifying patients with low muscularity contributes to better stratification in this population.

Do metabolic syndrome and its components have an impact on bone mineral density in adolescents?

In recent years, there has been growing concern about the occurrence of metabolic syndrome (MetS) at an early age and its effects on bone mass in adolescents. Adolescence is considered a critical period for bone mass gain. Impaired bone acquisition during this phase can lead to “suboptimal” peak bone mass and increase the risk of osteopenia/osteoporosis and fractures in old age. The objective of this review was to perform a critical analysis of articles that specifically focus on this age group, evaluating the influence of MetS and its components on bone mineral density in adolescents. A possible relationship between this syndrome and bone mass has been demonstrated, but the number of studies addressing this topic in adolescents is small. Despite the scarcity of evidence, the results of those studies show that Metabolic Syndrome is negatively correlated with bone mass and also that some components of MetS are negatively correlated with bone mineral density in adolescents. However, the associations between MetS and bone mass development need to be further explored in the age group corresponding to adolescence. Further good-quality studies are necessary to complement the understanding of this relationship.

Sarcopenia predicts reduced survival in patients with hepatocellular carcinoma at first diagnosis

 Background. Sarcopenia is a complication and independent risk factor for mortality in patients with liver cirrhosis.

AIM

To assess the prevalence and influence of sarcopenia on overall survival in a cohort of cirrhotic patients with hepatocellular carcinoma managed in a tertiary center.

MATERIAL AND METHODS

Abdominal computed tomography of 92 consecutive hepatocellular carcinoma cirrhotic patients, enrolled and followed from 2004 to 2014, were retrospectively studied with a software analyzing the cross-sectional areas of muscles at third lumbar vertebra level. Data was normalized for height, skeletal muscle index (SMI) calculated and presence of Sarcopenia measured. Sarcopenia was defined by SMI ≤ 41 cm2/m2 for women and ≤ 53 cm2/m2 for men with body mass index (BMI) ≥ 25, and ≤ 43 cm2/m2 for men and women with BMI < 25, respectively.

RESULTS

Median age at diagnosis was 71.9 years (30.7-86.4) and BMI 24.7 (17.5-36.7), comparable in women 23.1, (17.5-36.7) and men 24.7 (18.4-36.7). A class of CHILD score and BCLC A prevailed (55.4% and 41.3%, respectively); metastatic disease was found in 12% of cases. Sarcopenia was present in 40.2% of cases, mostly in females (62.9%; p = 0.005). Mean overall survival was reduced in sarcopenic patients, 66 (95% CI 47 to 84) vs. 123 (95% CI 98 to 150) weeks (p = 0.001). At multivariate analysis, sarcopenia was a predictor of reduced overall survival, independent of age (p = 0.0027).

CONCLUSIONS

This retrospective study shows high prevalence of sarcopenia among cirrhotic patients with hepatocellular carcinoma. Presence of sarcopenia was identified as independent predictor of reduced overall survival. As easily measurable by CT, sarcopenia should be determined for prognostic purposes in this patient population.

Differentiating Sarcopenia and Cachexia Among Patients With Cancer

Patients with cancer are at an increased risk for muscle loss via 2 distinct mechanisms: sarcopenia, defined as the age-associated decrease in muscle mass related to changes in muscle synthesis signaling pathways, and/or cachexia, defined as cytokine-mediated degradation of muscle and adipose depots. Both wasting disorders are prevalent; among patients with cancer, 15%-50% are sarcopenic and 25%-80% are cachectic. Muscle mass may be difficult to quantify in overweight/obese individuals. Often, overweight/obese patients with cancer are assumed to be normally nourished when in fact severe muscle depletion may be present. No universally accepted treatment exists for preventing or reversing sarcopenia or cachexia in patients with cancer. Current treatment options are limited to nutrition therapy and exercise, which may lead to difficulties in adherence during cancer treatment. Future treatments may provide pharmaceutical therapy that targets muscle degradation and synthesis pathways. There is a need to determine a multimodal treatment plan for muscle depletion to improve quality of life, survival, and therapy complications in patients with cancer.

Age-related sarcopenia and its pathophysiological bases

Age-related loss of the skeletal muscle and its function is known as sarcopenia. Definition and diagnostic criteria for sarcopenia have been outlined as consensus statements from several study groups, including usual gait speed, grip strength, and skeletal muscle mass. Whereas underlying mechanisms and pathophysiology of sarcopenia remains to be clarified, recent studies have suggested that chronic inflammatory status as well as lifestyle-related factors in older individuals might contribute to the process and progress of sarcopenia.

Enhancement of Skeletal Muscle in Aged Rats Following High-Intensity Stretch-Shortening Contraction Training

Exercise is the most accessible, efficacious, and multifactorial intervention to improve health and treat chronic disease. High-intensity resistance exercise, in particular, also maximizes skeletal muscle size and strength-outcomes crucial at advanced age. However, such training is capable of inducing muscle maladaptation when misapplied at old age. Therefore, characterization of parameters (e.g., mode and frequency) that foster adaptation is an active research area. To address this issue, we utilized a rodent model that allowed training at maximal intensity in terms of muscle activation and tested the hypothesis that muscles of old rats adapt to stretch-shortening contraction (SSC) training, provided the training frequency is sufficiently low. At termination of training, normalized muscle mass (i.e., muscle mass divided by tibia length) and muscle quality (isometric force divided by normalized muscle mass) were determined. For young rats, normalized muscle mass increased by ∼20% regardless of training frequency. No difference was observed for muscle quality values after 2 days versus 3 days per week training (0.65 ± 0.09 N/mg/mm vs. 0.59 ± 0.05 N/mg/mm, respectively). For old rats following 3 days per week training, normalized muscle mass was unaltered and muscle quality was 30% lower than young levels. Following 2 days per week training at old age, normalized muscle mass increased by 17% and muscle quality was restored to young levels. To investigate this enhanced response, oxidative stress was assessed by lipid peroxidation quantification. For young rats, lipid peroxidation levels were unaltered by training. With aging, baseline levels of lipid peroxidation increased by 1.5-fold. For old rats, only 2 days per week training decreased lipid peroxidation to levels indistinguishable from young values. These results imply that, appropriately scheduled high-intensity SSC training at old age is capable of restoring muscle to a younger phenotype in terms of lipid peroxidation levels and muscle quality.

Associations between the consumption of carbonated beverages and periodontal disease: The 2008-2010 Korea national health and nutrition examination survey

Consumption of carbonated beverages was reported to be associated with obesity and other adverse health consequences. This study was performed to assess the relationship between the consumption of carbonated beverages and periodontal disease using nationally representative data.The data from the Korea National Health and Nutrition Examination Survey conducted between 2008 and 2010 were used; the analysis in this study was confined to a total of 5517 respondents >19 years old who had no missing values for the consumption of carbonated beverages or outcome variables. The community periodontal index greater than or equal to code 3 was defined as periodontal disease.The odds ratios of the percentage of individuals with periodontal treatment needs tended to increase with the consumption of carbonated beverages. Adjusted odds ratios and their 95% confidence intervals adjusted for various factors including age, sex, body mass index, smoking, drinking, exercise, metabolic syndrome, frequency of tooth brushing per day, use of secondary oral products, dental checkup within a year, consumption of coffee of the individuals with the consumption of carbonated beverages once or less per month, once or less per week and twice or more per week were 1.109(0.804,1.528), 1.404(1.035,1.906), and 1.466(1.059,2.029), respectively. A subgroup analysis revealed that in individuals with body mass index < 25 or waist circumference < 90 cm for males or < 80 cm for females, the prevalence of periodontal disease increased with higher consumption of carbonated beverages (P for trend < 0.05).Consumption of carbonated beverages was positively associated with the risk of periodontal disease in Korean adults. In a subgroup analysis, the individuals consuming carbonated beverages with body mass index < 25 or waist circumference < 90 cm for males or < 80 cm for females were more likely to have periodontal disease. Consumption of carbonated beverages may be considered to be an independent risk indicator for periodontal disease and periodontal health of nonobese individuals may benefit from reduction of carbonated beverage consumption.

Protecting Skeletal Muscle with Protein and Amino Acid during Periods of Disuse

Habitual sedentary behavior increases risk of chronic disease, hospitalization and poor quality of life. Short-term bed rest or disuse accelerates the loss of muscle mass, function, and glucose tolerance. Optimizing nutritional practices and protein intake may reduce the consequences of disuse by preserving metabolic homeostasis and muscle mass and function. Most modes of physical inactivity have the potential to negatively impact the health of older adults more than their younger counterparts. Mechanistically, mammalian target of rapamycin complex 1 (mTORC1) signaling and muscle protein synthesis are negatively affected by disuse. This contributes to reduced muscle quality and is accompanied by impaired glucose regulation. Simply encouraging increased protein and/or energy consumption is a well-intentioned, but often impractical strategy to protect muscle health. Emerging evidence suggests that leucine supplemented meals may partially and temporarily protect skeletal muscle during disuse by preserving anabolism and mitigating reductions in mass, function and metabolic homeostasis.

Rapid skeletal muscle wasting predicts worse survival in patients with liver cirrhosis

AIM

Sarcopenia impairs the outcome of patients with liver cirrhosis independently of liver function reserves. The aim of this study was to investigate whether the rate of skeletal muscle wasting predicts mortality in cirrhotic patients.

METHODS

This retrospective study evaluated 149 cirrhotic patients who visited our hospital between March 2004 and September 2012. The skeletal muscle cross-sectional area at the level of the third lumbar vertebra was measured by computed tomography, from which the skeletal muscle index was obtained for diagnosis of sarcopenia. The relative change in skeletal muscle area per year (ΔSMA/y) was calculated in each patient. Cox proportional hazards regression analysis was performed to evaluate risk factors for mortality.

RESULTS

Of the 149 cirrhotic patients, 94 (63%) were diagnosed with sarcopenia. The median of ΔSMA/y in all patients was -2.2%. For patients in Child-Pugh class A, B and C, ΔSMA/y was -1.3%, -3.5% and -6.1%, respectively. During a median follow-up period of 39 months (range, 1-110), 45 patients (30%) died. The optimal cut-off value of ΔSMA/y for predicting mortality was -3.1%; the survival rate in patients with ΔSMA/y of -3.1% or less was significantly lower than in patients with ΔSMA/y of more than -3.1% (P < 0.0001). The multivariate Cox proportional hazards model found ΔSMA/y of -3.1% or less to be significantly associated with mortality in cirrhotic patients (hazard ratio = 2.73, 95% confidence interval = 1.43-5.44, P < 0.01).

CONCLUSION

ΔSMA/y is useful for predicting mortality in patients with liver cirrhosis. Management of skeletal muscle may contribute toward improving the outcome of cirrhotic patients.

Prolonged Culture of Aligned Skeletal Myotubes on Micromolded Gelatin Hydrogels

In vitro models of skeletal muscle are critically needed to elucidate disease mechanisms, identify therapeutic targets, and test drugs pre-clinically. However, culturing skeletal muscle has been challenging due to myotube delamination from synthetic culture substrates approximately one week after initiating differentiation from myoblasts. In this study, we successfully maintained aligned skeletal myotubes differentiated from C2C12 mouse skeletal myoblasts for three weeks by utilizing micromolded (μmolded) gelatin hydrogels as culture substrates, which we thoroughly characterized using atomic force microscopy (AFM). Compared to polydimethylsiloxane (PDMS) microcontact printed (μprinted) with fibronectin (FN), cell adhesion on gelatin hydrogel constructs was significantly higher one week and three weeks after initiating differentiation. Delamination from FN-μprinted PDMS precluded robust detection of myotubes. Compared to a softer blend of PDMS μprinted with FN, myogenic index, myotube width, and myotube length on μmolded gelatin hydrogels was similar one week after initiating differentiation. However, three weeks after initiating differentiation, these parameters were significantly higher on μmolded gelatin hydrogels compared to FN-μprinted soft PDMS constructs. Similar results were observed on isotropic versions of each substrate, suggesting that these findings are independent of substrate patterning. Our platform enables novel studies into skeletal muscle development and disease and chronic drug testing in vitro.

Impact of sarcopenia on surgical site infection after restorative proctocolectomy for ulcerative colitis

PURPOSE

The coexistence of sarcopenia is associated with postoperative complications, including infection after abdominal surgery. We evaluated the association between sarcopenia and surgical site infection (SSI) after surgery for ulcerative colitis.

METHODS

The subjects of this retrospective study were 69 patients who underwent restorative proctocolectomy with perioperative abdominal computed tomography (CT). Sarcopenia was diagnosed by measuring the cross-sectional area of the right and left psoas muscles as the total psoas muscle area on CT images. We assessed whether sarcopenia was associated with SSI and clinical factors, including nutritional and inflammatory markers.

RESULTS

The lowest quartiles defined as sarcopenia in men and women were 567.4 and 355.8 mm²/m², respectively. According to this classification, 12 men and 6 women had sarcopenia. Patients with sarcopenia had a lower body mass index (p = 0.0004) and a higher C-reactive protein concentration (p = 0.05) than those without sarcopenia. SSIs were identified in 12 patients (17.3 %) and included six pelvic abscesses and seven wound infections. According to multivariate analysis, sarcopenia was an independent risk factor for SSI (odds ratio = 4.91, 95 % confidence interval 1.09-23.5, p = 0.03).

CONCLUSION

Sarcopenia is predictive of SSI after pouch surgery for ulcerative colitis.

Serum Uric Acid Is Positively Associated with Handgrip Strength among Japanese Community-Dwelling Elderly Women

Serum uric acid (UA) has strong anti-oxidant properties. Muscle strength and mass decrease with age, and recently, this decrease has been defined as sarcopenia. Sarcopenia may be triggered by oxidative stress. We investigated whether serum UA is associated with handgrip strength (HGS), which is a useful indicator of sarcopenia, among Japanese community-dwelling elderly persons. The present study included 602 men aged 72 ± 7 years and 847 women aged 71 ± 6 years from a rural village. We examined the cross-sectional relationship between serum UA and HGS. In both genders, HGS increased significantly with increased serum UA levels. A multiple linear regression analysis using HGS as an objective variable and various confounding factors as explanatory variables showed that in men age, drinking status, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and estimated glomerular filtration ratio (eGFRCKDEPI) were independently and significantly associated with HGS, and in women, serum UA as well as age, body mass index, drinking status, diastolic blood pressure, and eGFRCKDEPI were independently and significantly associated with HGS. In women, age and multivariate-adjusted HGS were significantly higher in the Quartile-3 (4.8-5.4 mg/dL) and Quartile-4 groups (5.5-9.3 mg/dL) of serum UA than in the lower groups (0.7-4.7 mg/dL). These results suggest that serum UA may have a protective role in aging-associated decline in muscle strength in community-dwelling elderly women.

Prevalence of Sarcopenia in the Korean Woman Based on the Korean National Health and Nutritional Examination Surveys

Background

The criteria for defining sarcopenia vary among studies and confusion has arisen when defining the cutoff value. As a result, the prevalence of sarcopenia differs markedly depending on the definition. This study used the Asian Working Group for Sarcopenia (AWGS) definition to determine the prevalence of sarcopenia among Korean women.

Methods

This study was based on data obtained from the 2008 to 2011 Korean National Health and Nutrition Examination Surveys IV and V. We used the AWGS recommended cutoff value of 5.4 kg/m² to determine the prevalence of sarcopenia in Korean women.

Results

The prevalence rates of sarcopenia using a cutoff value of 5.4 kg/m² were 385 (19.5%) in women in their 50s, 286 (16.6%) in women in their 60s, 293 (23.7%) in women in their 70s, and 91 (30.8%) in women ≥80 years. The prevalence rates of sarcopenia were 307 (19.0%) in women 65 to 74 years, 194 (27.4%) in women 75 to 84 years, and 32 (40.5%) in women ≥85 years. The overall prevalence among women >50 years was 20.2%. The prevalence of sarcopenia in women >65 years was 22.1%.

Conclusions

The prevalence of sarcopenia among Korean women was within the range of values of previous research about sarcopenia. Furthermore, using 5.4 kg/m² as the cutoff value was useful to compare various studies about sarcopenia in Koreans.

Effect of Low-Magnitude, High-Frequency Vibration Treatment on Retardation of Sarcopenia: Senescence-Accelerated Mouse-P8 Model

Sarcopenia-related falls and fall-related injuries in community-dwelling elderly people garnered more and more interest in recent years. Low-magnitude high-frequency vibration (LMHFV) was proven beneficial to musculoskeletal system and recommended for sarcopenia treatment. This study aimed to evaluate the effects of LMHFV on the sarcopenic animals and explore the mechanism of the stimulatory effects. Senescence-accelerated mouse P8 (SAMP8) mice at month 6 were randomized into control (Ctrl) and vibration (Vib) groups and the mice in the Vib group were given LMHFV (0.3 g, 20 min/day, 5 days/week) treatment. At months 0, 1, 2, 3, and 4 post-treatment, muscle mass, structure, and function were assessed. The potential proliferation capacity of the muscle was also evaluated by investigating satellite cells (SCs) pool and serum myostatin expression. At late stage, the mice in the Vib group showed higher muscle strength (month 4, p = 0.028). Generally, contractibility was significantly improved by LMHFV (contraction time [CT], p = 0.000; half-relaxation time [RT50], p = 0.000). Enlarged cross-sectional area of fiber type IIA was observed in the Vib group when compared with Ctrl group (p = 0.000). No significant difference of muscle mass was observed. The promotive effect of LMHFV on myoregeneration was reflected by suppressed SC pool reduction (month 3, p = 0.000; month 4, p = 0.000) and low myostatin expression (p = 0.052). LMHFV significantly improved the structural and functional outcomes of the skeletal muscle, hence retarding the progress of sarcopenia in SAMP8. It would be a good recommendation for prevention of the diseases related to skeletal muscle atrophy.

The role of cystatin-C in the confirmation of reduced glomerular filtration rate among the oldest old

INTRODUCTION

Current guidelines suggest using cystatin-C to confirm a reduced creatinine-based estimated glomerular filtration rate (eGFRcr) when the latter is thought to be inaccurate. Older adults have reduced muscle mass, which may affect the accuracy of eGFRcr. We evaluated the use of cystatin-C-based eGFR (eGFRcys) to confirm reduced eGFRcr among adults ≥ 80 years of age and, for comparison, younger adults.

MATERIAL AND METHODS

We analyzed data from 3,059 REasons for Geographic And Racial Differences in Stroke (REGARDS) study participants with reduced eGFRcr (< 60 ml/min/1.73 m(2)) enrolled in 2003-2007 who were not on dialysis. eGFRcr and eGFRcys were calculated using age, sex and race-adjusted equations. Confirmed reduced eGFRcr was defined as eGFRcys < 60 ml/min/1.73 m(2). Prevalence of chronic kidney disease complications at baseline and all-cause mortality up to March 2012 were calculated. Analyses were stratified by age: < 65, 65-79 and ≥ 80 years.

RESULTS

Among participants < 65, 65-79 and ≥ 80 years of age, 76.5%, 85.7% and 92.5%, respectively, had reduced eGFRcr confirmed with eGFRcys (p < 0.001). Among participants ≥ 80 years of age, those with reduced eGFRcr confirmed with eGFRcys had higher prevalence of hypertension (79.1% vs. 65.1%, p = 0.03) and albuminuria (38.3% vs. 22.7%, p = 0.04) and higher risk for all-cause mortality (hazard ratio: 2.43; 95% confidence interval: 1.19-5.01) as compared with those in whom reduced eGFRcr was not confirmed by eGFRcys.

CONCLUSIONS

Reduced eGFRcr was confirmed using eGFRcys for the vast majority of adults ≥ 80 years. These results suggest that using cystatin-C to confirm a reduced eGFRcr may not be necessary among the oldest old.

Sarcopenia is a risk factor for the recurrence of hepatocellular carcinoma after curative treatment

BACKGROUND AND AIM

Sarcopenia, initially proposed as decreased of muscle mass and strength, is associated with aging and malignant diseases. The aim of the present study was to determine whether there is a correlation between sarcopenia and the recurrence of hepatocellular carcinoma (HCC) after curative treatment.

METHODS

We conducted a retrospective analysis of consecutive naive patients with HCC who underwent curative resection or radiofrequency ablation. To eliminate the influence of cause or the severity of liver damage, subjects were limited to those with HCC with hepatitis C-related cirrhosis and Child-Pugh class A liver function. Patients were assessed using computed tomographic measurement of muscle mass at the level of the third lumbar (L3) vertebrae, the L3 skeletal muscle index (L3 SMI). Sarcopenia was defined by using previously published, sex-specific cut-off value.

RESULTS

Sarcopenia was present in 61 of 92 patients. Patients' median age was 71.5 years (range, 47-84), and the baseline characteristics of patients were comparable between patients with and without sarcopenia except for sex, serum albumin level, prothrombin time, diabetes mellitus and body mass index. Recurrence rates at 1, 3 and 5 years were 39.1%,77.1%,81.7% for patients with sarcopenia and 23.5%,59.5% and 75.7% for patients without sarcopenia, respectively (P = 0.03). Multivariate Cox analysis revealed that sarcopenia and preoperative α-fetoprotein of more than 40 ng/mL were significant independent factors for recurrence.

CONCLUSION

Sarcopenia is a risk factor for recurrence in patients with HCC who were treated with curative treatment.

The implications of sarcopenia and sarcopenic obesity on cardiometabolic disease

The important changes in body composition associated with aging are a decline in skeletal muscle mass and an increase in body fat. Body fat distribution also changes with age; subcutaneous fat decreases and visceral abdominal fat increase, which contributes to numerous cardiometabolic diseases (CMDs) such as type 2 diabetes, dyslipidemia, and cardiovascular disease (CVD). Sarcopenia often accompanied by an increase in body fat and vice versa, a scenario termed sarcopenic obesity (SO), which might lead to the cumulative risk of both sarcopenia and obesity. However, there is still no consensus regarding the definition and consequences of SO. The lack of a unified definition for SO might contribute to inconsistent findings about the association of SO with CMD. Complex etiologies are associated with development of SO. A vicious cycle between the loss of muscle and the accumulation of ectopic fat might be associated with CMD via an intricate interplay of factors including proinflammatory cytokines, oxidative stress, mitochondrial dysfunction, insulin resistance, dietary energy, physical activity, mitochondrial dysfunction, and other factors that have yet to be identified. Moreover, recent epidemiological studies suggest that SO is related to CVD and mortality. This review focuses on the current literature with regard to the association between sarcopenia, dynapenia, and obesity, as well as their implications for CMD. The ultimate goal of this Prospects is to encourage conduct of well-designed future studies that elucidate the relationship among sarcopenia, SO, and CMD.

Sarcopenic obesity and physical performance in middle aged women: a cross-sectional study in Northeast Brazil

BACKGROUND

Sarcopenia and obesity have been independently associated with physical function decline, however little information is currently available on the relationship between sarcopenic obesity and physical performance, mainly in middle aged women. The present study aims to estimate the prevalence of sarcopenic obesity and to explore the relationship between sarcopenic obesity and physical performance in middle-aged women from Northeast Brazil.

METHODS

A cross-sectional study of women (40-65 years) living in Parnamirim, a city in Northeast Brazil (n = 491). Physical performance was assessed by grip strength, knee extensor and flexor strength (isometric dynamometry), gait speed, and chair stands. Using bioelectrical impedance analysis (BIA), appendicular skeletal muscle mass divided by height squared (kg / m(2)) was used to define sarcopenia. Waist circumference ≥ 88 cm was defined as abdominal obesity. Sarcopenic obesity was defined as the coexistence of obesity and sarcopenia. The physical performance outcomes were regressed in four groups defined by combinations of sarcopenia and obesity, adjusting for potential confounders (age, education and menopausal status).

RESULTS

Prevalence rates of the four obesity-sarcopenia groups were: Sarcopenic obesity (7.1 %), obesity (67.4 %), sarcopenia (12.4 %) and normal (13 %). Women with sarcopenic obesity had significantly lower grip strength, weaker knee extension and flexion and longer time to raise from a chair compared with non-obese and non-sarcopenic women (p.values < 0.001). Except for the chair stands, these statistically significant differences were also found between sarcopenic obese and obese women. There was no significant difference for gait speed across the four groups (p = 0.50).

CONCLUSION

Sarcopenic obesity was present in 7 % of this population of middle-aged women from Northeast Brazil and it was associated with poor physical performance. Sarcopenic obesity may occur in middle-aged women with performance limitations beyond pure sarcopenia-related muscle mass or obesity alone.

Generation and Characterization of a MYF5 Reporter Human iPS Cell Line Using CRISPR/Cas9 Mediated Homologous Recombination

Human iPS cells hold great promise for disease modeling and treatment of degenerative disorders including muscular dystrophies. Although a few research groups have used them for skeletal muscle differentiation, most were based on gene over-expression or long-term mesenchymal differentiation and retrospective identification of myogenic cells. Therefore, this study was aimed to generate a knock-in reporter human iPS cell line for MYF5, as an early myogenic specification gene, to allow prospective identification and purification of myogenic progenitors from human iPS cells. By using a CRISPR/Cas9 double nickase strategy, a 2A-GFP reporter was inserted before the stop codon of the MYF5 gene using homologous recombination. This approach allowed for highly efficient in-frame targeting of MYF5 in human iPS cells. Furthermore, in order to prove the reporter function, endogenous MYF5 expression was induced using a novel dead Cas9-VP160 transcriptional activator. Induced clones demonstrated appropriate MYF5-GFP co-expression. Finally, to confirm the differentiation potential, reporter human iPS clones were differentiated through embryoid body method and MYF5-GFP⁺ myogenic cells were sorted and characterized. These data provides valuable guidelines for generation of knock-in reporter human iPS cell lines for myogenic genes which can be used for disease modeling, drug screening, gene correction and future in vivo applications.

New Predictive Index for Lumbar Paraspinal Muscle Degeneration Associated With Aging

STUDY DESIGN

A cross-sectional imaging study of paraspinal muscle degeneration using a new index for easy evaluation.

OBJECTIVE

To examine the natural progression of age-related changes in the lumbar paraspinal muscles and to verify the validity of our new index for evaluating paraspinal muscle degenerationSUMMARY OF BACKGROUND DATA.: Measurement of paraspinal muscle morphology is an effective method for reflecting atrophy and fat infiltration, but it is complicated to perform. Therefore, we focused on the groove between lumbar paraspinal muscles as a simple index for evaluating paraspinal muscle degeneration.

METHODS

A total of 160 subjects aged 10 to 88 years (10 male and 10 female subjects in each decade) with lumbar lordosis of more than 20° were included. Body mass index (BMI) was calculated. Sagittal T2-weighted magnetic resonance imaging (MRI) was used to measure lumbar lordosis, while axial T2-weighted MRI was used to measure cross-sectional area (CSA) and fat infiltration rate of the paraspinal muscles at the intervertebral disc level from L1 to L5. To quantify the depth of the groove between the paraspinal muscles, our own image index (lumbar indentation value (LIV): equal to the length of the bulge of the muscle to the attachment of the spinous process), also was measured. We then determined the correlation between LIV and paraspinal muscle degeneration.

RESULTS

There were no significant differences in BMI and lumbar lordosis between age groups. CSA of the paraspinal muscles tended to decrease with age, and fat infiltration rate increased with age. There was a negative correlation between CSA and fat infiltration rate at all levels (r = -0.474 to -0.634). LIV decreased significantly with age and strongly correlated with CSA at all levels (r = 0.709-0.789).

CONCLUSION

Our new index is a simple and effective parameter for evaluating paraspinal muscle degeneration associated with aging.

LEVEL OF EVIDENCE

4.