Intermuscular fat: a review of the consequences and causes

Factors of Muscle Quality and Determinants of Muscle Strength: A Systematic Literature Review

Muscle quality defined as the ratio of muscle strength to muscle mass disregards underlying factors which influence muscle strength. The aim of this review was to investigate the relationship of phase angle (PhA), echo intensity (EI), muscular adipose tissue (MAT), muscle fiber type, fascicle pennation angle (θf), fascicle length (lf), muscle oxidative capacity, insulin sensitivity (IS), neuromuscular activation, and motor unit to muscle strength. PubMed search was performed in 2021. The inclusion criteria were: (i) original research, (ii) human participants, (iii) adults (≥18 years). Exclusion criteria were: (i) no full-text, (ii) non-English or -German language, (iii) pathologies. Forty-one studies were identified. Nine studies found a weak−moderate negative (range r: [−0.26]−[−0.656], p < 0.05) correlation between muscle strength and EI. Four studies found a weak−moderate positive correlation (range r: 0.177−0.696, p < 0.05) between muscle strength and PhA. Two studies found a moderate-strong negative correlation (range r: [−0.446]−[−0.87], p < 0.05) between muscle strength and MAT. Two studies found a weak-strong positive correlation (range r: 0.28−0.907, p < 0.05) between θf and muscle strength. Muscle oxidative capacity was found to be a predictor of muscle strength. This review highlights that the current definition of muscle quality should be expanded upon as to encompass all possible factors of muscle quality.

Long-term treatment with Elamipretide enhances healthy aging phenotypes in mice

Background

Disruption of metabolic and bioenergetic homeostasis related to mitochondrial dysfunction is a key driver of aging biology. Therefore, targeting mitochondrial function would be a rational approach to slowing aging. Elamipretide (Elam, a.k.a. SS-31) is a peptide known to target mitochondria and suppress mammalian signs of aging. The present study was designed to examine the phenotypic effects of long-term Elam treatment on aging in C57BL/6 mice starting at 18 months of age.

Methods

Mice were fed regular chow (RC diet) or a diet high in fat and sugar (HF diet) and treated with 3 mg/kg of Elam or saline subcutaneously 5 days per week for 10 months. Physiological performance assessments were conducted at 28 months of age.

Results

Elam improved the physical performance of males but not females, while in females Elam improved cognitive performance and enhanced the maintenance of body weight and fat mass. It also improved diastolic function in both males and females, but to a greater extent in males. The HF diet over 10 months had a negative effect on health span, as it increased body fat and decreased muscle strength and heart function, especially in females.

Conclusions

Elam enhanced healthy aging and cardiac function in both male and female mice, although the specific effects on function differed between sexes. In females, the treatment led to better cognitive performance and maintenance of body composition, while in males, performance on a rotating rod was preserved. These overall observations have translational implications for considering additional studies using Elam in therapeutic or preventive approaches for aging and age-related diseases.

Design, development and validation of Food Frequency Questionnaires for the diabetic population: protocol for a systematic review and meta-analysis

INTRODUCTION

The Food Frequency Questionnaire is one of the most widely used tools for estimating nutritional intake in epidemiological studies. No study has been systematically performed to comprehensively explore Food Frequency Questionnaires designed, developed and validated specifically for the diabetic population (FFQs-DDV-DiaP). Therefore, a systematic review and meta-analysis will be carried out in order to identify and describe FFQs-DDV-DiaP; to examine their design, development, validity and reproducibility; as well as to estimate the overall degree of correlation and agreement; and to evaluate the factors that affect them.

METHODS AND ANALYSIS

A systematic literature review will be performed in PubMed/MEDLINE, Scopus and Web of Science to find potentially relevant studies. Original studies related to the design, development, as well as the assessment of the validity and reproducibility of FFQs-DDV-DiaP; reported in English or Romance languages will be selected. Independent reviewers will select studies, extract relevant data and assess FFQs-DDV-DiaP quality. Data will be pooled using the generic inverse-variance method with random-effects models and expressed as correlation coefficients or mean differences with 95% CIs to examine the global validity and reproducibility of FFQs-DDV-DiaP. Heterogeneity will be evaluated by the Cochran Q-statistic and quantified by the I² statistic. Stratified analyses and random-effects meta-regressions will be performed to explore heterogeneity and whether any covariate influences the effect sizes. Finally, publication bias will be assessed through the Begg's and Egger's tests.

ETHICS AND DISSEMINATION

This systematic review and meta-analysis will not use confidential personal data. Therefore, the requirement of ethical approval or informed consent is not necessary. The results of this review will be disseminated only in peer-reviewed publications or at relevant scientific conferences.

PROSPERO REGISTRATION NUMBER

CRD42021268575.

A Review of free fatty acid-induced cell signaling, angiopoietin-like protein 4, and skeletal muscle differentiation

Postnatal skeletal muscle differentiation from quiescent satellite cells is a highly regulated process, although our understanding of the contribution of nutritional factors in myogenesis is limited. Free fatty acids (FFAs) are known to cause detrimental effects to differentiated skeletal muscle cells by increasing oxidative stress which leads to muscle wasting and insulin resistance in skeletal muscle. In addition, FFAs are thought to act as inhibitors of skeletal muscle differentiation. However, the precise molecular mechanisms underlying the effects of FFAs on skeletal muscle differentiation remains to be elucidated. There is a clear relationship between dietary FFAs and their ability to suppress myogenesis and we propose the hypothesis that the FFA-mediated increase in angiopoietin-like protein 4 (ANGPTL4) may play a role in the inhibition of differentiation. This review discusses the role of FFAs in skeletal muscle differentiation to-date and proposes potential mechanisms of FFA-induced ANGPTL4 mediated inhibition of skeletal muscle differentiation.

Lactiplantibacillus plantarum fermented barley extracts ameliorate high-fat-diet-induced muscle dysfunction via mitophagy

BACKGROUND

A reduced level of fatty acid oxidation (FAO) by skeletal muscle leads to the accumulation of intermuscular fat (IMF), which is linked to impaired exercise capacity. Previously, we have reported that Lactiplantibacillus plantarum fermented barley extract (LFBE) has effective anti-obesity properties. In this study, the effects of LFBE on muscle were investigated.

RESULTS

LFBE improved running endurance and muscle strength, which was caused by the elevation of FAO in muscle. In addition, LFBE renovated muscle regeneration through the upregulation of paired box 7 and myogenic differentiation 1 expression avoiding the injury of skeletal muscle fibers. Furthermore, total polyphenol isolated from LFBE (FTP) reinforced mobility and showed a significant protective effect on maintaining muscle fiber morphogenesis in Caenorhabditis elegans. Transmission electron microscope observation suggested FTP induced mitophagy in C. elegans body wall muscle, which was strongly connected with enhanced FAO in mitochondria.

CONCLUSIONS

Our findings highlighted the beneficial bioactivities of FTP and its potential application for stimulating mitophagy and muscle function in obese individuals. © 2022 Society of Chemical Industry.

Effect of a Multicomponent Intervention on Hepatic Steatosis Is Partially Mediated by the Reduction of Intermuscular Abdominal Adipose Tissue in Children With Overweight or Obesity: The EFIGRO Project

OBJECTIVE

In adults, there is evidence that improvement of metabolic-associated fatty liver disease (MAFLD) depends on the reduction of myosteatosis. In children, in whom the prevalence of MAFLD is alarming, this muscle-liver crosstalk has not been tested. Therefore, we aimed to explore whether the effects of a multicomponent intervention on hepatic fat is mediated by changes in intermuscular abdominal adipose tissue (IMAAT) in children with overweight/obesity.

RESEARCH DESIGN AND METHODS

A total of 116 children with overweight/obesity were allocated to a 22-week family-based lifestyle and psychoeducational intervention (control group, n = 57) or the same intervention plus supervised exercise (exercise group, n = 59). Hepatic fat percentage and IMAAT were acquired by MRI at baseline and at the end of the intervention.

RESULTS

Changes in IMAAT explained 20.7% of the improvements in hepatic steatosis (P < 0.05). Only children who meaningfully reduced their IMAAT (i.e., responders) had improved hepatic steatosis at the end of the intervention (within-group analysis: responders -20% [P = 0.005] vs. nonresponders -1.5% [P = 0.803]). Between-group analysis showed greater reductions in favor of IMAAT responders compared with nonresponders (18.3% vs. 0.6%, P = 0.018), regardless of overall abdominal fat loss.

CONCLUSIONS

The reduction of IMAAT plays a relevant role in the improvement of hepatic steatosis after a multicomponent intervention in children with overweight/obesity. Indeed, only children who achieved a meaningful reduction in IMAAT at the end of the intervention had a reduced percentage of hepatic fat independent of abdominal fat loss. Our findings suggest that abdominal muscle fat infiltration could be a therapeutic target for the treatment of MAFLD in childhood.

Inflammaging: The ground for sarcopenia?

Sarcopenia is a progressive skeletal muscle disease that occurs most commonly in the elderly population, contributing to increased costs and hospitalization. Exercise and nutritional therapy have been proven to be effective for sarcopenia, and some drugs can also alleviate declines in muscle mass and function due to sarcopenia. However, there is no specific pharmacological treatment for sarcopenia at present. This review will mainly discuss the relationship between inflammaging and sarcopenia. The increased secretion of proinflammatory cytokines with aging may be because of cellular senescence, immunosenescence, alterations in adipose tissue, damage-associated molecular patterns (DAMPs), and gut microbes due to aging. These sources of inflammaging can impact the sarcopenia process through direct or indirect pathways. Conversely, sarcopenia can also aggravate the process of inflammaging, creating a vicious cycle. Targeting sources of inflammaging can influence muscle function, which could be considered a therapeutic target for sarcopenia. Moreover, not only proinflammatory cytokines but also anti-inflammatory cytokines can influence muscle and inflammation and participate in the progression of sarcopenia. This review focuses on the effects of TNF-α, IL-6, and IL-10, which can be detected in plasma. Therefore, clearing chronic inflammation by targeting proinflammatory cytokines (TNF-α, IL-1, IL-6) and the inflammatory pathway (JAK/STAT, autophagy, NF-κB) may be effective in treating sarcopenia.

Prospective Natural History Study in 24 Adult Patients With LGMDR12 Over 2 Years of Follow-up: Quantitative MRI and Clinical Outcome Measures

BACKGROUND AND OBJECTIVES

Limb-girdle muscular dystrophy autosomal recessive type 12 (LGMDR12) is a rare hereditary muscular dystrophy for which outcome measures are currently lacking. We evaluated quantitative MRI and clinical outcome measures to track disease progression to determine which tests could be useful in future clinical trials to evaluate potential therapies.

METHODS

We prospectively measured the following outcome measures in all participants at baseline and after 1 and 2 years: 6-minute walk distance (6MWD), 10-meter walk test (10MWT), the Medical Research Council (MRC) sum scores, Biodex isometric dynamometry, serum creatine kinase, and 6-point Dixon MRI of the thighs.

RESULTS

We included 24 genetically confirmed, adult patients with LGMDR12 and 24 age-matched and sex-matched healthy controls. Patients with intermediate-stage thigh muscle fat replacement at baseline (proton density fat fraction [PDFF] 20%-70%) already showed an increase in PDFF in 8 of the 14 evaluated thigh muscles after 1 year. The standardized response mean demonstrated a high responsiveness to change in PDFF for 6 individual muscles over 2 years in this group. However, in patients with early-stage (<20%) or end-stage (>70%) muscle fat replacement, PDFF did not increase significantly over 2 years of follow-up. Biodex isometric dynamometry showed a significant decrease in muscle strength in all patients in the right and left hamstrings (-6.2 Nm, p < 0.002 and -4.6 Nm, p < 0.009, respectively) and right quadriceps muscles (-9 Nm, p = 0.044) after 1 year of follow-up, whereas the 6MWD, 10MWT, and MRC sum scores were not able to detect a significant decrease in muscle function/strength even after 2 years. There was a moderately strong correlation between total thigh PDFF and clinical outcome measures at baseline.

DISCUSSION

Thigh muscle PDFF imaging is a sensitive outcome measure to track progressive muscle fat replacement in selected patients with LGMDR12 even after 1 year of follow-up and correlates with clinical outcome measures. Biodex isometric dynamometry can reliably capture the loss of muscle strength over the course of 1 year in patients with LGMDR12 and should be included as an outcome measure in future clinical trials as well.

Postprandial triglyceride levels rather than fat distribution may reflect early signs of disturbed fat metabolism in Iraqi immigrants

PURPOSE

Previous studies have shown that at a similar body mass index, Middle Eastern immigrants are more insulin resistant and at higher risk for type 2 diabetes (T2D) than native Europeans. Insulin resistance is strongly associated with disturbed fat metabolism and cardiovascular disease (CVD). However, fat metabolism is poorly investigated comparing Middle Eastern and European ethnicities.

METHODS

This observational study included 26 Iraqi and 16 Swedish-born men without T2D or clinical risk factors for CVD. An oral fat tolerance test (OFTT) was performed, where plasma triglycerides (p-TG) were measured for 6 h. mRNA expression and adipocyte size were measured in subcutaneous adipose tissue biopsies collected prior to OFTT, and magnetic resonance imaging was conducted to assess body fat distribution.

RESULTS

The median p-TG accumulation was higher and the clearance slower among Iraqis than Swedes. None of the groups reached their fasting p-TG (Iraqis 1.55 mmol/l; Swedes 0.95 mmol/l) after 6 h (Iraqis p-TG 3.10 mmol/l; Swedes p-TG 1.50 mmol/l). Adipocyte size, mRNA expression, and fat accumulation in the liver, muscle and abdomen were similar in both groups.

CONCLUSION

Postprandial p-TG levels rather than fat distribution may reflect early signs of disturbed fat metabolism in Iraqi immigrants without CVD risk factors.

The sonographic quantitative assessment of the deltoid muscle to detect type 2 diabetes mellitus: a potential noninvasive and sensitive screening method?

BACKGROUND

In our previous published study, we demonstrated that a qualitatively assessed elevation in deltoid muscle echogenicity on ultrasound was both sensitive for and a strong predictor of a type 2 diabetes (T2DM) diagnosis. This study aims to evaluate if a sonographic quantitative assessment of the deltoid muscle can be used to detect T2DM.

METHODS

Deltoid muscle ultrasound images from 124 patients were stored: 31 obese T2DM, 31 non-obese T2DM, 31 obese non-T2DM and 31 non-obese non-T2DM. Images were independently reviewed by 3 musculoskeletal radiologists, blinded to the patient's category. Each measured the grayscale pixel intensity of the deltoid muscle and humeral cortex to calculate a muscle/bone ratio for each patient. Following a 3-week delay, the 3 radiologists independently repeated measurements on a randomly selected 40 subjects. Ratios, age, gender, race, body mass index, insulin usage and hemoglobin A_1c were analyzed. The difference among the 4 groups was compared using analysis of variance or chi-square tests. Both univariate and multivariate linear mixed models were performed. Multivariate mixed-effects regression models were used, adjusting for demographic and clinical variables. Post hoc comparisons were done with Bonferroni adjustments to identify any differences between groups. The sample size achieved 90% power. Sensitivity and specificity were calculated based on set threshold ratios. Both intra- and inter-radiologist variability or agreement were assessed.

RESULTS

A statistically significant difference in muscle/bone ratios between the groups was identified with the average ratios as follows: obese T2DM, 0.54 (P < 0.001); non-obese T2DM, 0.48 (P < 0.001); obese non-T2DM, 0.42 (P = 0.03); and non-obese non-T2DM, 0.35. There was excellent inter-observer agreement (intraclass correlation coefficient 0.87) and excellent intra-observer agreements (intraclass correlation coefficient 0.92, 0.95 and 0.94). Using threshold ratios, the sensitivity for detecting T2DM was 80% (95% CI 67% to 88%) with a specificity of 63% (95% CI 50% to 75%).

CONCLUSIONS

The sonographic quantitative assessment of the deltoid muscle by ultrasound is sensitive and accurate for the detection of T2DM. Following further studies, this process could translate into a dedicated, simple and noninvasive screening method to detect T2DM with the prospects of identifying even a fraction of the undiagnosed persons worldwide. This could prove especially beneficial in screening of underserved and underrepresented communities.

Shoulder muscle changes in patients with type 2 diabetes mellitus who have a painful shoulder: a quantitative muscle ultrasound study

Background

It is assumed that in patients with diabetic neuropathy, muscle denervation can result in shoulder disorders. Muscle denervation will lead to changes in muscle architecture, which can be assessed by quantitative muscle ultrasound (QMUS). The aim was to investigate whether increased muscle echogenicity, as a sign of neuropathy, is more often present in patients with shoulder pain who have type 2 diabetes mellitus (T2DM) than in those without.

Methods

Sixty-six patients with T2DM and 23 patients without diabetes mellitus (DM) having shoulder pain were included. Quantitative muscle ultrasound images were obtained bilaterally from the biceps brachii, deltoid, and supra- and infraspinatus muscles. The mean echogenicity (muscle ultrasound grey value) was transformed into z-scores and compared to reference values obtained from 50 healthy participants. Associations between muscle echogenicity and clinical variables were explored.

Results

In painful shoulders of both patients with T2DM and patients without DM, mean echogenicity z-scores of all muscles were significantly increased compared to healthy controls. No significant differences in echogenicity between patients with T2DM and those without DM were found. In patients with T2DM, a distal symmetric polyneuropathy was significantly associated with increased echogenicity of all muscles except the infraspinatus muscle.

Conclusions

These findings indicate that patients with painful shoulders, irrespective of having T2DM, seem to have abnormal shoulder muscles. Future studies are needed to elucidate whether neuropathy or other conditions lead to these muscle changes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05627-9.

A need for diet assessment technology for South Asians living in the USA

South Asians are among the fastest growing ethnic group in the USA yet remain understudied in epidemiologic studies. Due to their unique disease profile, identifying risk moderators and mitigators, such as dietary patterns and food intake, will help to determine the diet-disease relationship that is specific to this largely immigrant population group in the USA. The aim of this commentary is to highlight the dietary traditions and acculturated practices experienced by South Asians in the USA with a call for a diet assessment instrument that adequately captures their dietary diversity. Specifically, we call for (i) the inclusion of traditional food items, such as herbs and spices, that individualize diet assessment for participants; and (ii) leveraging technology that will enhance the experience of diet assessment for both researchers and participants, tailoring the collection of habitual dietary intake in this diverse population group.

Bidirectional roles of skeletal muscle fibro-adipogenic progenitors in homeostasis and disease

Sarcopenia and myopathies cause progressive muscle weakness and degeneration, which are closely associated with fat infiltration and fibrosis in muscle. Recently, experimental research has shed light on fibro-adipogenic progenitors (FAPs), also known as muscle-resident mesenchymal progenitors with multiple differentiation potential for adipogenesis, fibrosis, osteogenesis and chondrogenesis. They are considered key regulators of muscle homeostasis and integrity. They play supportive roles in muscle development and repair by orchestrating the regulatory interplay between muscle stem cells (MuSCs) and immune cells. Interestingly, FAPs also contribute to intramuscular fat infiltration, fibrosis and other pathologies when the functional integrity of the network is compromised. In this review, we summarize recent insights into the roles of FAPs in maintenance of skeletal muscle homeostasis, and discuss the underlying mechanisms regulating FAPs behavior and fate, highlighting their roles in participating in efficient muscle repair and fat infiltrated muscle degeneration as well as during muscle atrophy. We suggest that controlling and predicting FAPs differentiation may become a promising strategy to improve muscle function and prevent irreparable muscle damage.

Do Preoperative Vastus Medialis Volume and Quality Affect Functional Outcomes after Total Knee Arthroplasty?

Background: Vastus medialis function has been implicated in the development and progression of knee osteoarthritis; however, studies evaluating the influence of its preoperative volume and quality on functional outcomes following total knee arthroplasty (TKA) remain scarce. This study aimed to determine the association between vastus medialis volume, quality, and clinical outcomes after TKA. Methods: Among the patients who underwent unilateral TKA, 92 who had undergone magnetic resonance imaging (MRI) before TKA were included. Preoperative vastus medialis volume and quality were assessed using the cross-sectional area (CSA) and fat infiltration ratio on MRI. Clinical outcomes were evaluated using the Knee Society knee score (KSKS) and Knee Society function score (KSFS) at baseline and 1 year after surgery. The relationships between preoperative CSA, fatty infiltration ratio, and clinical outcomes were analyzed using univariate and multivariate linear regression. Results: Only the fatty infiltration ratio was significantly associated with postoperative KSFS in the univariate linear regression analysis. In the multivariate linear regression analysis, age and fatty infiltration ratio were significantly associated with postoperative KSFS. Conclusions: Increased vastus medialis fat infiltration is associated with worse functional outcomes after TKA. Preserving vastus medialis quality could improve functional outcomes, and surgeons should encourage patients to perform quadriceps strengthening exercises before surgery.

The Pathological Links between Adiposity and the Carpal Tunnel Syndrome

An association between obesity and carpal tunnel syndrome is found in many epidemiological studies. Therefore, there is a need to evaluate the physiopathological links that could explain the association between these two entities. Ectopic adipose tissue is responsible for metabolic syndrome and inflammation, and is a major risk factor for diabetes and cardiovascular diseases. Taking these elements into consideration, we conducted an extensive literature revision of the subject, considering as ectopic fat-related mechanisms the following: (a) the direct compression and the association with the metabolic syndrome of the fat deposition around the wrist, (b) the insulin resistance, dyslipidemia, inflammatory, and oxidative mechanisms related to the central deposition of the fat, (c) the impaired muscle contraction and metabolism related to myosteatosis. Each section presents the cellular pathways which are modified by the ectopic deposition of the adipose tissue and the impact in the pathogeny of the carpal tunnel syndrome. In conclusion, the experimental and clinical data support the epidemiological findings. Efforts to reduce the obesity epidemics will improve not only cardio-metabolic health but will reduce the burden of the disability-free life expectancy due to the carpal tunnel syndrome.

Effect of Dietary Weight Loss and Macronutrient Intake on Body Composition and Physical Function in Adults with Knee Osteoarthritis: A Systematic Review

Overweight and obesity increase the risk of development and progression of knee osteoarthritis (OA), with higher levels of fat mass and lower levels of lean mass associated with poorer functional status. The aim was to assess changes in weight, body composition and physical function following weight loss or weight maintenance interventions in knee OA. A comprehensive search of four databases was conducted. The risk of bias was assessed using the Quality Criteria Checklist for primary research. Primary outcomes included weight, body composition and physical function; secondary outcomes were lipids, inflammatory biomarkers and muscle strength. Eleven studies were included utilizing diet and exercise (n = 4) or diet-only (n = 7) interventions, two of which were weight maintenance studies. Most studies (n = 10) reported improvements in physical function with significant weight loss, while the change in strength reported in three studies was variable. The diet and exercise studies reported an average reduction in weight of 6.7% and lean mass of 1.6 kg, with greater improvements in physical function. The diet-only studies, including weight maintenance interventions, reported greater average weight loss (7.8%) and reduction in LM (2.0 kg). Overall, better retention of lean mass and muscle strength was observed in participants with higher protein intake (≥37% of energy) and subsequently improved physical function.

Adipose and serum zinc alpha-2-glycoprotein (ZAG) expressions predict longitudinal change of adiposity, wasting and predict survival in dialysis patients

There were limited data on adipose and serum zinc alpha-2-glycoprotein (ZAG) expression and its association with body composition in patients with advanced chronic kidney disease (CKD). This study aimed to quantify adipose and serum ZAG expression and evaluate their association with body composition and its longitudinal change, together with mortality in incident dialysis patients. We performed a single-center prospective cohort study. Patients who were planned for peritoneal dialysis were recruited. ZAG levels were measured from serum sample, subcutaneous and pre-peritoneal fat tissue obtained during peritoneal dialysis catheter insertion. Body composition and functional state were evaluated by bioimpedance spectroscopy and Clinical Frailty Scale respectively at baseline and were repeated 1 year later. Primary outcome was 2-year survival. Secondary outcomes were longitudinal changes of body composition. At baseline, the average adipose and serum ZAG expression was 13.4 ± 130.0-fold and 74.7 ± 20.9 µg/ml respectively. Both adipose and serum ZAG expressions independently predicted adipose tissue mass (ATM) (p = 0.001, p = 0.008, respectively). At 1 year, ATM increased by 3.3 ± 7.4 kg (p < 0.001) while lean tissue mass (LTM) remained similar (p = 0.5). Adipose but not serum ZAG level predicted change in ATM (p = 0.007) and LTM (p = 0.01). Serum ZAG level predicted overall survival (p = 0.005) and risk of infection-related death (p = 0.045) after adjusting for confounders. In conclusion, adipose and serum ZAG levels negatively correlated with adiposity and predicted its longitudinal change of fat and lean tissue mass, whilst serum ZAG predicted survival independent of body mass in advanced CKD patient.

The effect of ageing on fat infiltration of thigh and paraspinal muscles in men

Background

Myosteatosis, skeletal muscle fat infiltration, is associated with inflammation and fibrosis. The age-related increase of myosteatosis is an important characteristic of sarcopenia and contributes to fragility.

Aims

To investigate the impact of healthy aging on intermuscular adipose tissue (IMAT) and muscle fat fraction (FF) in the thigh and the paraspinal muscles in males.

Methods

In 54 healthy males (age 20–70), all active hobby golfers, magnetic resonance imaging was performed to determine volume of IMAT, volume of muscle tissue (MT) and of percentage of FF.

Results

Between ages 20–70, at the thigh, IMAT/MT volume and MT FF increased annually by 2.9% and 1.3%, respectively. At the psoas IMAT/Psoas volume did not change with age. MT FF increased by 1.5% annually. At the erector spinae IMAT/Erector volume decreased by 0.3% and MT FF increased by 2.8% annually.

Discussion

With increasing age, in males, thigh muscle atrophied, muscle tissue was partly replaced by adipose tissue and remaining muscle tissue also contained more fat. Similar effects were observed in the erector spinae. The psoas muscle did not atrophy, although MT FF also increased with age. Overall correlations with age were weak to moderate with higher correlations observed in the paraspinal muscles.

Conclusions

Age-related increases of muscle fat infiltration were observed in the thigh and in the spine. Muscle atrophy did not occur in the psoas. In cross-sectional studies, an adjustment of volumetric parameters by muscle volume is advisable when comparing age-dependent results.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-022-02149-1.

Recommendations for nutritional assessment across clinical practice guidelines: A scoping review

BACKGROUND & AIMS

CPGs propose several methods and criteria to perform nutritional assessment, a key process to determine the type and severity of malnutrition, which generates variability in clinical practice and outcomes. The aim of the study was to describe the criteria considered by clinical practice guidelines (CPGs) for nutritional assessment.

METHODS

We performed a scoping review systematically searching in PubMed, Trip Database, Google Scholar, and Google, until November 5, 2021. We included all CPGs mentioning tools or criteria for nutritional assessment in adults from the general population or with any specific pathology or condition. Two authors independently reviewed and decided on study selection and data extraction.

RESULTS

We included 18 CPGs (12 elaborated in Europe). The CPGs recommended heterogeneous criteria for nutritional assessment: 16/18 CPGs included at least one body composition parameter (e.g., loss of muscle mass, loss of subcutaneous fat), 15/18 included history related to dietary intake, 15/18 included clinical history (e.g., weight loss), 10/18 included anthropometric measurement (e.g., low body mass index [BMI]), 11/18 included biochemical criteria (e.g., albumin, C-reactive protein), 8/18 included physical examination (e.g., fluid retention, sarcopenia, loss of subcutaneous fat), 8/18 included functional test (e.g., decreased handgrip strength), and 1/18 included catabolic state. Also, 9/18 CPGs mentioned a tool for nutritional assessment, the Subjective Global Assessment (SGA) the most common (8/18). None of the CPGs justified the inclusion of any of the tools or criteria they mentioned.

CONCLUSIONS

The CPGs mentioned heterogeneous criteria for nutritional assessment. The most commonly mentioned criteria were decreased food intake, loss of muscle mass, weight loss, and low BMI. The most mentioned tool was the SGA. None of the CPGs provided a clear rationale for using certain criteria or tools for nutritional assessment.

Skeletal muscle and abdominal circumference explain intramuscular fat, independent of exercise frequency, in middle-aged Japanese men

The purpose of this study was to examine how intramuscular adipose tissue (IntraMAT) can be characterized using physical and functional characteristics, muscle size, and/or adipose tissue in four different exercise frequency groups of middle-aged Japanese men. One thousand twenty-eight middle-aged men (age, 47.5 ± 8.1 years; height, 170.5 ± 5.8 cm; body mass, 67.0 ± 9.3 kg; body mass index, 21.9 ± 5.3 kg/m²) were allocated to four groups on the basis of their weekly exercise frequency: Group 1, no exercise, n = 334; Group 2, once a week, n = 271; Group 3, a few days a week, n = 269; and Group 4, every day, n = 154. Their body composition, blood pressure, and handgrip strength were assessed. A single-slice computerized tomography image at the level of the umbilicus was acquired and the CSAs of IntraMAT, muscle tissue, and subcutaneous and visceral adipose tissues (SCAT and VAT) were calculated. The %IntraMAT significantly correlated with physical characteristics, such as age, BMI, abdominal circumference, and muscle tissue CSA. Stepwise multiple regression analysis was performed, with the %IntraMAT as the dependent variable. Muscle tissue CSA and abdominal circumference were the common independent variables across groups to explain the variability of the %IntraMAT. It was also extracted %body fat and age for Group 2, age, handgrip strength, and BMI for Group 3, and smoking category for Group 4. These results suggested that muscle tissue size and abdominal circumference would be the strong predictors to explain %IntraMAT of the trunk muscle across four groups, and that age, %body fat, BMI, and SCAT, handgrip strength and smoking category were also good predictors for each group with different exercise frequency in middle-aged Japanese men.

Gastric tuberculosis presenting as a large gastric ulcer

While gastrointestinal (GI) tuberculosis (TB) accounts for 1%-3% of all TB cases worldwide, TB of the stomach is extremely rare and accounts for 1%-2% of all GI TB. Little is known about this entity, and most data are obtained from case reports. We report a case of a woman in her 60s who presented with a 2-week history of generalised weakness, fatigue and shivering, with severe loss of appetite on background history of dyspepsia and significant weight loss for the preceding 2 years. Upper endoscopy revealed a large gastric ulcer. Biopsy and histopathology revealed caseating granulomas with numerous acid-fast bacilli detected with Ziehl-Neelsen stain. She was diagnosed with gastric TB. Subsequently, she was also diagnosed with pulmonary, adrenal and colonic involvement.

Association between Fat Distribution and Chronic Low Back Pain among 10,606 Adults: Data from the Korean National Health and Nutrition Examination Survey

Obesity is associated with chronic low back pain (CLBP), but the association between fat distribution and CLBP is unclear. This cross-sectional study evaluated the relationship using the Korean National Health and Nutrition Examination Survey data. A total of 10,606 adults (average age: 45.4, female: 57.1%) were included. We estimated the regional fat distribution, waist circumference, and body fat proportion, compared the values in people with and without CLBP, and stratified the estimates by sex and obesity status using a multivariable linear model. There were no statistically significant differences in the average waist circumference between the people with and without CLBP (p = 0.731) and the average fat proportion between those with and without CLBP (p = 0.731). The average regional fat distribution was significantly higher in the people with CLBP than in those without CLBP, in the upper limbs (11.4%, 95% confidence interval [CI]: [11.3, 11.5] vs. 11.2%, 95% CI: [11.1, 11.3], p < 0.05) and in the lower limbs (31.9%, 95% CI: [31.6, 32.2] vs. 31.4%, 95% CI: [31.2, 31.6], p < 0.01). More obvious among men, fat distribution in the lower limbs is higher than in people without obesity (p < 0.001). People with CLBP tend to have a higher fat distribution in the limbs than those without it and obese people with CLBP would need to reduce the fat in the lower limbs.

Effects of Citrus depressa Hayata Fruit Extract on Thigh Muscles Mass and Composition in Subacute Stroke Patients: A Double-Blind, Randomized, Controlled Pilot Trial

Objective: This pilot study evaluated the effects of Citrus depressa Hayata fruit extract (CFEx) on thigh muscle cross-sectional area (CSA) and composition in subacute stroke patients with hemiparesis who were undergoing rehabilitation. Design and Intervention: This double-blinded, placebo-controlled, randomized pilot trial included 40 subacute stroke patients with moderate-to-severe hemiparesis, and they were randomly assigned to receive CFEx or placebo supplements for 12 weeks. The thigh muscle CSA was measured by computed tomography as total muscle area defined by Hounsfield units (HU) values of -29 to 150 HU. The total muscle area was divided into muscle area with fat infiltration and normal muscle area to evaluate muscle composition (-29 to 29 and 30 to 150 HU, respectively). Results: At baseline, the total muscle area and normal muscle area in the paretic thigh were lower than those in the nonparetic thigh. The nonparetic normal muscle area was significantly higher in the CFEx group than in the placebo group at 12 weeks, whereas the total muscle area was not different. Conclusions: The thigh muscle CSA and composition in the paretic side have already deteriorated in patients with moderate-to-severe hemiparesis at the subacute stroke stage. CFEx supplementation during rehabilitation might improve the nonparetic thigh muscle composition in subacute stroke patients. Findings of this study are needed to be verified by a large-scale randomized trial since this study was a pilot study with a small sample size. Trial registration: UMIN Clinical Trial Registry (UMIN ID: UMIN000012902).

Intermuscular adipose tissue in Type 2 diabetes mellitus: Non-invasive quantitative imaging and clinical implications

Intermuscular adipose tissue (IMAT) is an ectopic fat depot found beneath the fascia and within the muscles. IMAT modulates muscle insulin sensitivity and triggers local and systemic chronic low-grade inflammation by producing cytokines and chemokines, which underlie the pathogenesis of Type 2 diabetes mellitus (T2DM). Imaging techniques have been increasingly used to non-invasively quantify IMAT in patients with diabetes in research and healthcare settings. In this study, we systematically reviewed the cell of origin and definition of IMAT, and the use of quantitative and functional imaging technology pertinent to the etiology, risk factors, lifestyle modification, and therapeutic treatment of diabetes. The purpose of this article is to provide important insight into the current understanding of IMAT and future prospects of targeting IMAT for T2DM control.

The combined anti-osteoporotic effects of simvastatin and exercise in ovariectomized mice fed a high-fat diet

BACKGROUND

To evaluate and compare the effects of the combined intervention of simvastatin and exercise on the bone degeneration in a mice model of osteoporosis (OP) induced by obesity and estrogen deficiency.

METHODS

56 female 3-month-old C57BL/6 mice were given a standard diet or a high-fat diet after ovariectomy (OVX) or sham surgery. Drug administration and exercise training were initiated 72 h after surgical operation, which were treated with simvastatin (10 mg/kg/day) or exercise (15 m/min for 30 min/day) or combined with simvastatin and exercise at 72 h for 8 weeks. The pathology of OP was assessed by histomorphology analyses, immunohistochemistry (IHC), micro-computed tomography (Micro-CT), enzyme-linked immunosorbent assay (ELISA) and cell culture.

RESULTS

The coexistence of obesity and estrogen deficiency significantly further exacerbated OP pathology, and combined intervention showed a better significant anti-osteoporosis effect than monotherapy. In details, simvastatin combined with exercise ameliorated the abnormal bone mass, microstructure and bone marrow adipocyte differentiation, significantly increased osteoprotegerin (OPG), type 1 collagen (Col-I), RUNX2 and osteocalcin (OCN) expression, decreased the expression of receptor activator of nuclear factor-kappaB ligand (RANKL) and peroxisome proliferator-activated receptor γ (PPARγ). Furthermore, combined intervention markedly improved abnormal metabolic status, reduced the levels of serum glucose, insulin, triglycerides (TG), low-density lipoprotein (LDL), leptin, CTX-1 and IL-1β, and increased the level of OCN.

CONCLUSIONS

The coexistence of obesity and estrogen deficiency further aggravates bone tissue degeneration and abnormal metabolic pathology, which could be better inhibited by the combination with simvastatin and exercise instead of single intervention, suggesting that combined intervention may be a potential candidate for amelioration of the progression of OP.

Risk Factors for the Incident Decline of Physical Performance in Older Men: The Prospective Strambo Study

Risk factors of physical performance decline in older men remain uncertain. We assessed risk factors of incident physical performance deterioration in older men followed up prospectively. In a cohort of 821 men aged 60-87, physical performance was assessed by four tests (five chair stands, standing with closed eyes, forward and backward tandem walk) at baseline, 4 and 8 years. Various predictive biological measurements were performed at baseline. Serum creatinine/ cystatin C (Cr/CysC) ratio was used as an index of muscle mass. In multivariate models, higher age, higher fat mass index (FMI = fat mass/height²), low physical activity, prior stroke and fracture were associated with poor physical performance at baseline. Higher age, low physical activity, low calcium intake, prior non-vertebral fractures, low apparent free testosterone concentration and poor health status were associated with higher risk of loss to follow-up. Low grip strength, Parkinson's disease and stroke were associated with higher risk of incident inability to do five chair stands. Low Cr/CysC ratio and high FMI were associated with high risk of incident inability to perform forward and backward tandem walk. Sarcopenic obesity (co-occurrence of lower tertile of Cr/CysC and upper tertile of FMI) was associated with higher risk of incident inability to perform forward (OR = 3.31, 95% CI 1.88-5.84, p < 0.001) and backward tandem walk and of incident inability to perform more than one test (OR = 5.82, 95% CI 1.29-26.27, p < 0.001). In conclusion, sarcopenic obesity and poor health are associated with higher risk of incident severe decline of physical performance.

PGL4 syndrome in a patient with synchronous paraganglioma-pheochromocytoma

Pheochromocytoma and paraganglioma (PGL) are rare neuroendocrine tumours, frequently associated with genetic syndromes. We report the case of a man in his 40s with a left anterior neck mass and a history of hypertensive crisis, heavy sweating and constipation. Biochemical tests showed increased plasma and urine normetanephrines. Neck ultrasound suggested left carotid body PGL, but it was mandatory to search for other lesions. Whole-body MIBG failed to show abnormal uptake. Abdominal MRI was suggestive of another PGL, anterior to the right adrenal gland. Abdominal surgery was performed uneventfully under alpha and beta blockers. This intervention proved to be effective, as normetanephrines levels became completely normal after 1 month. Carotid body PGL was successfully excised 4-months later. Genetic study identified a large deletion in exon 1 of the SDHB gene allowing the diagnosis of paraganglioma syndrome type 4 (PGL4). After 19 months of follow-up, he is still on clinical and biochemical remission and will continue life-long surveillance.

Multimodal Diagnostic Approaches to Advance Precision Medicine in Sarcopenia and Frailty

Sarcopenia, defined as the loss of muscle mass, strength, and function with aging, is a geriatric syndrome with important implications for patients and healthcare systems. Sarcopenia increases the risk of clinical decompensation when faced with physiological stressors and increases vulnerability, termed frailty. Sarcopenia develops due to inflammatory, hormonal, and myocellular changes in response to physiological and pathological aging, which promote progressive gains in fat mass and loss of lean mass and muscle strength. Progression of these pathophysiological changes can lead to sarcopenic obesity and physical frailty. These syndromes independently increase the risk of adverse patient outcomes including hospitalizations, long-term care placement, mortality, and decreased quality of life. This risk increases substantially when these syndromes co-exist. While there is evidence suggesting that the progression of sarcopenia, sarcopenic obesity, and frailty can be slowed or reversed, the adoption of broad-based screening or interventions has been slow to implement. Factors contributing to slow implementation include the lack of cost-effective, timely bedside diagnostics and interventions that target fundamental biological processes. This paper describes how clinical, radiographic, and biological data can be used to evaluate older adults with sarcopenia and sarcopenic obesity and to further the understanding of the mechanisms leading to declines in physical function and frailty.

State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions

For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.

Overweight, Obesity, and CVD Risk: a Focus on Visceral/Ectopic Fat

PURPOSE OF REVIEW

Despite its prevalence and well-documented impact on population health, obesity has not emerged as a strong independent risk factor for cardiovascular disease after control for intermediate risk factors. The purpose of this brief narrative review is to highlight results from imaging studies that have not only documented the remarkable heterogeneity of body fat topography but also the importance of visceral adiposity as a key body fat depot associated with cardiovascular disease risk and type 2 diabetes.

RECENT FINDINGS

Simple tools are also discussed in order to refine cardiometabolic risk assessment in persons with overweight/obesity. It is proposed that four lifestyle vital signs should be considered in clinical practice to improve discrimination of health risk in individuals with overweight/obesity: waist circumference as a simple marker of abdominal adiposity, cardiorespiratory fitness, overall diet quality, and level of reported physical activity. Heterogeneity of obesity is proposed as an example of a condition that would benefit from a precision lifestyle medicine approach.

Adipogenic progenitors in different organs: Pathophysiological implications

In physiological conditions, the adipose organ resides in well-defined areas, where it acts providing an energy supply and as an endocrine organ involved in the control of whole-body energy metabolism. Adipose tissue adipokines connect the body's nutritional status to the regulation of energy balance. When it surrounds organs, it provides also for mechanical protection. Adipose tissue has a complex and heterogenous cellular composition that includes adipocytes, adipose tissue-derived stromal and stem cells (ASCs) which are mesenchymal stromal cells, and endothelial and immune cells, which signal to each other and to other tissues to maintain homeostasis. In obesity and in other nutrition related diseases, as well as in age-related diseases, biological and functional changes of adipose tissue give rise to several complications. Obesity triggers alterations of ASCs, impairing adipose tissue remodeling and adipose tissue function, which induces low-grade systemic inflammation, progressive insulin resistance and other metabolic disorders. Adipose tissue grows by hyperplasia recruiting new ASCs and by hypertrophy, up to its expandability limit. To overcome this limitation and to store the excess of nutrients, adipose tissue develops ectopically, involving organs such as muscle, bone marrow and the heart. The origin of ectopic adipose organ is not clearly elucidated, and a possible explanation lies in the stimulation of the adipogenic differentiation of mesenchymal precursor cells which normally differentiate toward a lineage specific for the organ in which they reside. The chronic exposition of these newly-formed adipose depots to the pathological environment, will confer to them all the phenotypic characteristics of a dysfunctional adipose tissue, perpetuating the organ alterations. Visceral fat, but also ectopic fat, either in the liver, muscle or heart, can increase the risk of developing insulin resistance, type 2 diabetes, and cardiovascular diseases. Being able to prevent and to target dysfunctional adipose tissue will avoid the progression towards the complications of obesity and other nutrition-related diseases. The aim of this review is to summarize some of the knowledge regarding the presence of adipose tissue in particular tissues (where it is not usually present), describing the composition of its adipogenic precursors, and the interactions responsible for the development of organ pathologies.

Phase angle from bioelectrical impedance analysis is a useful indicator of muscle quality

BACKGROUND

Methods that facilitate muscle quality measurement may improve the diagnosis of sarcopenia. Current research has focused on the phase angle (PhA) obtained through bioelectrical impedance analysis (BIA) as an indicator of cellular health, particularly cell membrane integrity and cell function. The current study therefore aimed to evaluate the relationship between the PhA and muscle quality and muscle-related parameters and to determine factors associated with the PhA. Moreover, we attempted to determine the cut-off value of PhA for predicting sarcopenia.

METHODS

First-year university students (830 male students, 18.5 ± 0.6 years old; 422 female students, 18.3 ± 0.5 years old) and community-dwelling elderly individuals (70 male individuals, 74.4 ± 5.5 years old; 97 female individuals, 73.1 ± 6.4 years old) were included. PhA and other body composition data were measured using BIA, while muscle quality was calculated by dividing handgrip strength by upper limbs muscle mass. The relationship between PhA and the aforementioned parameters were then analysed, after which the cut-off value of PhA for predicting sarcopenia was examined.

RESULTS

Multiple linear regression analysis revealed that age, skeletal muscle mass index (SMI), and muscle quality were independently associated with PhA in both sexes [male (age: standardized regression coefficient (β) = -0.43, P < 0.001, SMI: β = 0.61, P < 0.001, muscle quality: β = 0.13, P < 0.001) and female (age: β = -0.56, P < 0.001, SMI: β = 0.52, P < 0.001, muscle quality: β = 0.09, P = 0.007)]. Participants with sarcopenia had a significantly lower PhA compared with those without it (sarcopenia vs. non-sarcopenia: young male participants, 5.51 ± 0.41° vs. 6.25 ± 0.50°, P < 0.001; young female participants, 4.88 ± 0.16° vs. 5.37 ± 0.44°, P = 0.005; elderly female participants: 4.14 ± 0.29° vs. 4.63 ± 0.42°, P = 0.009). Although no significant findings were observed in elderly male participants, the same tendency was noted. Receiver operating characteristic (ROC) curve analysis indicated that PhA had good predictive ability for sarcopenia in young male, elderly male, young female, and elderly female participants (area under the ROC curve of 0.882, 0.838, 0.865, and 0.850, with cut-off PhA values of 5.95°, 5.04°, 5.02°, and 4.20° for predicting sarcopenia, respectively).

CONCLUSIONS

The PhA reflected muscle quality and exhibited good accuracy in detecting sarcopenia, suggesting its utility as an index for easily measuring muscle quality, which could improve the diagnosis of sarcopenia.

Reference values for volume, fat content and shape of the hip abductor muscles in healthy individuals from Dixon MRI

Healthy hip abductor muscles are a good indicator of a healthy hip and an active lifestyle, as they are greatly involved in human daily activities. Fatty infiltration and muscle atrophy are associated with loss of strength, loss of mobility and hip disease. However, these variables have not been widely studied in this muscle group. We aimed to characterize the hip abductor muscles in a group of healthy individuals to establish reference values for volume, intramuscular fat content and shape of this muscle group. To achieve this, we executed a cross-sectional study using Dixon MRI scans of 51 healthy subjects. We used an automated segmentation method to label GMAX, GMED, GMIN and TFL muscles, measured normalized volume (NV) using lean body mass, fat fraction (FF) and lean muscle volume for each subject and computed non-parametric statistics for each variable grouped by sex and age. We measured these variables for each axial slice and created cross-sectional area and FF axial profiles for each muscle. Finally, we generated sex-specific atlases with FF statistical images. We measured median (IQR) NV values of 12.6 (10.8-13.8), 6.3 (5.6-6.7), 1.6 (1.4-1.7) and 0.8 (0.6-1.0) cm³ /kg for GMAX, GMED, GMIN and TFL, and median (IQR) FF values of 12.3 (10.1-15.9)%, 9.8 (8.6-11.2)%, 10.0 (9.0-12.0)% and 10.2 (7.8-13.5)% respectively. FF values were significantly higher for females for the four muscles (p < 0.01), but there were no significant differences between the two age groups. When comparing individual muscles, we observed a significantly higher FF in GMAX than in the other muscles. The reported novel reference values and axial profiles for volume and FF of the hip abductors, together with male and female atlases, are tools that could potentially help to quantify and detect early the deteriorating effects of hip disease or sarcopenia.

Fat Is Consistently Present within the Plantar Muscular Space of the Human Foot—An Anatomical Study

Background and Objectives: The foot comprises of active contractile and passive connective tissue components, which help maintain stability and facilitate movement during gait. The role of age- or pathology-related degeneration and the presence of fat within muscles in foot function and pain remains unclear. The existence of fat has to date not been quantified or compared between individuals according to age, sex, side or subregion. Materials and Methods: 18 cadaveric feet (mean age 79 years) were sectioned sagittally and photographed bilaterally. Fat in the plantar muscular space of the foot (PMSF) was quantified through the previously validated manual fat quantification method, which involved observing photographs of each section and identifying regions using OsiriX. Fat volume and percentage was calculated using a modified Cavalieri’s method. Results: All feet had fat located within the PMSF, averaging 25.8% (range, 16.5–39.4%) of the total PMSF volume. The presence of fat was further confirmed with plastination and confocal microscopy. Conclusions: These findings suggest that fat within the PMSF is a consistent but highly variable finding in elderly cohorts. Fat within the foot muscles may need to be considered a norm when comparing healthy and non-healthy subjects, and for therapeutic interventions to the foot. Further work is required to understand in detail the morphological and mechanical presence of fat in the foot, and compare these findings with pathological cohorts, such as sarcopenia. Additionally, future work should investigate if fat may compensate for the degeneration of the intrinsic muscles of the foot, with implications for both the use of orthotics and pain management.

Height and bone mineral content after inhaled corticosteroid use in the first 6 years of life

BACKGROUND

Infants and young children might be particularly susceptible to the potential side effects from inhaled corticosteroid (ICS) on height and bone mineral content (BMC), but this has rarely been studied in long-term prospective studies.

METHODS

Children from two Copenhagen Prospective Studies on Asthma in Childhood cohorts were included. ICS use was registered prospectively from birth to age 6 and the cumulative dose was calculated. Primary outcomes were height and BMC from dual-energy X-ray absorptiometry (DXA) scans at age 6.

RESULTS

At age 6, a total of 930 children (84%) from the cohorts had a valid height measurement and 792 (71%) had a DXA scan. 291 children (31%) received a cumulated ICS dose equivalent to or above 10 weeks of standard treatment before age 6. We found an inverse association between ICS use and height, -0.26 cm (95% CI: -0.45 to -0.07) per 1 year standard treatment from 0 to 6 years of age, p=0.006. This effect was mainly driven by children with ongoing treatment between age 5 and 6 years (-0.31 cm (95% CI: -0.52 to -0.1), p=0.004), while there was no significant association in children who stopped treatment at least 1 year before age 6 (-0.09 cm (95% CI: -0.46 to 0.28), p=0.64). There was no association between ICS use and BMC at age 6.

CONCLUSIONS

ICS use in early childhood was associated with reduced height at age 6 years but only in children with continued treatment in the sixth year of life.

Clinical relevance of the relationship between Trabecular Bone Score and metabolic syndrome

The Trabecular Bone Score (TBS) is an indirect measurement of bone quality, and studies have shown that TBS is an independent predictor of fracture risk. This cross-sectional investigation aimed to explore the relationship between metabolic syndrome (MetS) and TBS using data from the 2005-2006 US National Health and Nutrition Examination Survey. The association between individual MetS components and TBS was examined. There was a significant linear decrease in TBS with an increase in the number of MetS components. The β coefficients of TBS among participants with 3 and ≥4 MetS components were -0.015 and -0.041 (p=0.006 and p<0.001, respectively). Among participants with MetS, high systolic blood pressure, abdominal obesity, and high serum levels of triglycerides and glucose were significantly associated with lower TBS in fully adjusted models (p<0.05). Furthermore, there was a significant linear decrease in TBS with an increase in the number of MetS components in both sexes. TBS significantly decreased with an increasing number of MetS components in a US population. The components of MetS, including systolic blood pressure, waist circumference, and serum levels of triglyceride and glucose, exhibited a negative association with TBS.

Myosteatosis as a novel predictor of urinary incontinence after robot-assisted radical prostatectomy

OBJECTIVES

To evaluate the impact of sarcopenia and myosteatosis on urinary incontinence after prostatectomy.

METHODS

We retrospectively reviewed consecutive patients who underwent robot-assisted radical prostatectomy without nerve sparing between December 2012 and March 2019. Psoas muscle index and average total psoas density, which were measured on preoperative computed tomography images at level L3, were used to evaluate sarcopenia and myosteatosis, respectively. In addition, several magnetic resonance imaging variables associated with pelvic muscles, the urethra and the prostate were measured. Urinary continence was defined as non-use or use of just one incontinence pad per day. Logistic regression analyses aimed to identify the predictors of urinary incontinence 3 and 12 months after surgery.

RESULTS

Overall, 121 patients were included in the analysis. The incidence rates of urinary incontinence 3 and 12 months after surgery were 42% (51/121 cases) and 16% (19/121 cases), respectively. Logistic multivariable analysis showed that low average total psoas density was the only significant independent predictor of urinary incontinence 3 months after surgery (P < 0.01), and low obturator internus muscle thickness (P = 0.01), short membranous urethral length (P = 0.01) and low average total psoas density (P < 0.01) were significant independent predictors of urinary incontinence 12 months after surgery. By contrast, psoas muscle index was not statistically associated with urinary incontinence after surgery.

CONCLUSIONS

Myosteatosis (low average total psoas density) could be a novel predictor of urinary incontinence after robot-assisted radical prostatectomy.

Obesity and Bone: A Complex Relationship

There is a large literature on the relationship between obesity and bone. What we can conclude from this review is that the increase in body weight causes an increase in BMD, both for a mechanical effect and for the greater amount of estrogens present in the adipose tissue. Nevertheless, despite an apparent strengthening of the bone witnessed by the increased BMD, the risk of fracture is higher. The greater risk of fracture in the obese subject is due to various factors, which are carefully analyzed by the Authors. These factors can be divided into metabolic factors and increased risk of falls. Fractures have an atypical distribution in the obese, with a lower incidence of typical osteoporotic fractures, such as those of hip, spine and wrist, and an increase in fractures of the ankle, upper leg, and humerus. In children, the distribution is different, but it is not the same in obese and normal-weight children. Specifically, the fractures of the lower limb are much more frequent in obese children. Sarcopenic obesity plays an important role. The authors also review the available literature regarding the effects of high-fat diet, weight loss and bariatric surgery.

An Exploratory Analysis of the Role of Adipose Characteristics in Fulltime Wheelchair Users' Pressure Injury History

Aim: The goals of this study were 1) to identify the relationship between adipose (subcutaneous and intramuscular) characteristics and pressure injury (PrI) history in wheelchair users and 2) to identify subject characteristics, including biomechanical risk, that are related to adipose characteristics. Materials and Methods: The buttocks of 43 full-time wheelchair users with and without a history of pelvic PrIs were scanned in a seated posture in a FONAR UPRIGHT® MRI. Intramuscular adipose (the relative difference in intensity between adipose and gluteus maximus) and the subcutaneous adipose characteristics (the relative difference in intensity between subcutaneous adipose under and surrounding the ischium) were compared to PrI history and subject characteristics. Results: Participants with a history of PrIs had different subcutaneous fat (subQF) characteristics than participants without a history of PrIs. Specifically, they had significantly darker adipose under the ischium than surrounding the ischium (subQF effect size = 0.21) than participants without a history of PrIs (subQF effect size = 0.58). On the other hand, only when individuals with complete fat infiltration (n = 7) were excluded did individuals with PrI history have more fat infiltration than those without a PrI history. The presence of spasms (μ intramuscular adipose, 95% CI with spasms 0.642 [0.430, 0.855], without spasms 0.168 [-0.116, 0.452], p = 0.01) and fewer years using a wheelchair were associated with leaner muscle (Pearson Corr = -0.442, p = 0.003). Conclusion: The results of the study suggest the hypothesis that changes in adipose tissue under the ischial tuberosity (presenting as darker SubQF) are associated with increased biomechanical risk for pressure injury. Further investigation of this hypothesis, and the role of intramuscular fat infiltration in PrI development, may help our understanding of PrI etiology. It may also lead to clinically useful diagnostic techniques that can identify changes in adipose and biomechanical risk to inform early preventative interventions.

Muscle fat index is associated with frailty and length of hospital stay following transcatheter aortic valve replacement in high-risk patients

BACKGROUND

Aging is associated with progressive loss of muscle mass, as well as replacement of muscle with fat and fibrous tissue. We studied the contribution of muscle fat content, a surrogate marker of biological aging, to frailty and Length of Hospital Stay (LOS) following Transcatheter Aortic Valve Replacement (TAVR).

METHODS

We evaluated 415 patients who underwent TAVR from February 2012 to December 2016 at Mayo Clinic, MN, USA. Densities between -190 to -30 Hounsfield Units within the abdominal muscle area were determined as muscle fat. Muscle Fat Index (MFI) was defined as muscle fat mass divided by height squared. LOS was considered as the primary outcome. Stepwise multivariable linear regression was used to identify the predictors of LOS.

RESULTS

Mean age ± SD of the study population was 81.2 ± 9.6 years and 58.07% were male. Seventy-two patients (17.35%) had frailty. Median (IQR) LOS was 4 (3-6) days. MFI was higher in patients with frailty (median (IQR); 18.1 [13.8-24.2] vs 14.4 [10.6-18.7], p < 0.001) and was positively correlated with LOS (r = 0.129, p = 0.009). In multivariable analysis of predictors of LOS, MFI (β = 0.06, p = 0.022), pre-TAVR atrial fibrillation/flutter (β = 0.5, p = 0.015), and post-TAVR complications (β = 0.91, p < 0.001) were directly, and femoral access route (β = -1.13, p < 0.001) and pre-TAVR hemoglobin (β = -0.35, p = 0.002) were inversely associated with LOS.

CONCLUSIONS

MFI can be determined from pre-TAVR CT scans and is a novel predictor of LOS following TAVR. This objective indicator can potentially be used in a pre-TAVR clinic to plan for rehabilitation programs in selected patients.

Associations between inflammatory markers, body composition, and physical function: the Copenhagen Sarcopenia Study

BACKGROUND

Chronic low-grade inflammation has been suggested as one of the key elements in the development of sarcopenia, but in contrast to disease-related loss of muscle mass, the role of chronic low-grade inflammation in age-related (primary) sarcopenia is still not clear. The aim of this study was to investigate low-grade inflammation in relation to age and the potential association between inflammatory biomarkers and body composition, muscle strength and physical performance in a healthy Danish cohort.

METHODS

There were 1160 generally healthy men and women (range: 22-93 years) included. Appendicular lean mass (ALM) and visceral fat normalized to height (kg/m² ) was assessed by dual-energy X-ray absorptiometry (iDXA, GE Lunar). Muscle strength and physical performance were evaluated by handgrip strength (HGS), 30 s sit-to-stand performance, and maximal gait speed (GS). Systemic levels of TNF-α, IL-6, IL-1β, IL-4, IL-13, and IFN-γ were measured using multiplex bead-based immunoassays (Bio-Rad). hsCRP was assessed using latex particle-enhanced immunoturbidimetric assays (Roche Diagnostics).

RESULTS

With age, ALM/h² , HGS, sit-to-stand performance and GS decreased, whereas visceral fat/h² increased in both men and women (P < 0.05). Systemic levels of hsCRP, TNF-α, IL-4, and IFN-γ increased with age in men and women (P < 0.05), while IL-1β increased in women only (P < 0.01). Higher levels of hsCRP were associated with lower ALM/h² in elderly (≥65 years) men and women (P < 0.001). Higher levels of hsCRP were associated with lower handgrip strength in elderly women (P < 0.05) whereas higher levels of hsCRP was not associated with lower HGS in elderly men (P = 0.056). Higher levels of hsCRP were associated with lower GS (P < 0.05), whereas IFN-γ was positively associated with GS in elderly women (P < 0.05), but not elderly men. Visceral fat index was positively associated with hsCRP in elderly men and women (P < 0.001). Compared with elderly with normal HGS, elderly men and women with low HGS displayed higher levels of TNF-α and hsCRP (P < 0.05).

CONCLUSIONS

With age, systemic levels of hsCRP, TNF-α, IL-4, and IFN-γ increased, with hsCRP and TNF-α being especially elevated in more physically frail elderly supporting the association between low-grade systemic inflammation and poor physical function. In contrast, only high levels of hsCRP were weakly associated with low muscle mass and positively associated with visceral fat and low physical function, suggesting that chronic low-grade inflammation is not the main driver of age-related loss of muscle mass as previously suggested.

Changes in Tissue Composition and Load Response After Transtibial Amputation Indicate Biomechanical Adaptation

Despite the potential for biomechanical conditioning with prosthetic use, the soft tissues of residual limbs following lower-limb amputation are vulnerable to damage. Imaging studies revealing morphological changes in these soft tissues have not distinguished between superficial and intramuscular adipose distribution, despite the recognition that intramuscular fat levels indicate reduced tolerance to mechanical loading. Furthermore, it is unclear how these changes may alter tissue tone and stiffness, which are key features in prosthetic socket design. This study was designed to compare the morphology and biomechanical response of limb tissues to mechanical loading in individuals with and without transtibial amputation, using magnetic resonance imaging in combination with tissue structural stiffness. The results revealed higher adipose infiltrating muscle in residual limbs than in intact limbs (residual: median 2.5% (range 0.2-8.9%); contralateral: 1.7% (0.1-5.1%); control: 0.9% (0.4-1.3%)), indicating muscle atrophy and adaptation post-amputation. The intramuscular adipose content correlated negatively with daily socket use, although there was no association with time post-amputation. Residual limbs were significantly stiffer than intact limbs at the patellar tendon site, which plays a key role in load transfer across the limb-prosthesis interface. The tissue changes following amputation have relevance in the clinical understanding of prosthetic socket design variables and soft tissue damage risk in this vulnerable group.

Skeletal muscle aging, cellular senescence, and senotherapeutics: Current knowledge and future directions

Cellular senescence is a state of cell cycle arrest induced by several forms of metabolic stress. Senescent cells accumulate with advancing age and have a distinctive phenotype, characterized by profound chromatin alterations and a robust senescence-associated secretory phenotype (SASP) that exerts negative effects on tissue health, both locally and systemically. In preclinical models, pharmacological agents that eliminate senescent cells (senotherapeutics) restore health and youthful properties in multiple tissues. To date, however, very little is understood about the vulnerability of terminally-differentiated skeletal muscle fibers and the resident mononuclear cells that populate the interstitial microenvironment of skeletal muscle to senescence, and their contribution to the onset and progression of skeletal muscle loss and dysfunction with aging. Scientific advances in these areas have the potential to highlight new therapeutic approaches to optimize late-life muscle health. To this end, this review highlights the current evidence and the key questions that need to be addressed to advance the field's understanding of cellular senescence as a mediator of skeletal muscle aging and the potential for emerging senescent cell-targeting therapies to counter age-related deficits in muscle mass, strength, and function. This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.

Relative associations of abdominal and thigh compositions with cardiometabolic diseases in African Caribbean men

BACKGROUND

Regional body compositions are differentially associated with cardiometabolic risk factors. Simultaneous inclusion of both upper and lower body composition predictors in models is not often done, and studies which do include both measures (1) tend to exclude some tissue(s) of potential metabolic relevance, and (2) have used study populations with underrepresentation of individuals with African ancestries. Further, most body composition analyses do not employ compositional data analytic approaches, which may result in spurious associations.

OBJECTIVE

The objective of this analysis was to assess associations of abdominal and thigh adipose (AT) and muscle tissues with hypertension and type 2 diabetes using compositional data analytic methods.

RESEARCH DESIGN AND METHODS

This cross-sectional analysis included 610 African Caribbean men (median age: 62 years; mean BMI: 27.8 kg/m2). Abdominal (three components: subcutaneous [ASAT] and visceral [VAT] AT, 'other' abdominal tissue) and mid-thigh (four components: subcutaneous and intermuscular AT, muscle, bone) compositions were measured by computed tomography; additive log ratio transformations were applied to each composition. Regression models were used to simultaneously assess associations of abdominal and thigh component ratios with continuous risk factors (blood pressures, fasting glucose and insulin, HOMA-IR) and disease categories.

RESULTS

A two-fold increase in ASAT:'Other' ratio was associated with higher continuous risk factors and with odds of being in a higher hypertension (OR: 1.77, 95%CI: 1.10-2.84) or diabetes (OR: 1.81, 95%CI: 1.06-3.10) category. A two-fold increased VAT ratio was only associated with higher log-insulin and log-HOMA-IR (β = 0.10, p < 0.05 for both), while a two-fold increased thigh muscle:bone ratio was associated with a lower diabetes category (OR: 0.37, 95%CI: 0.14-1.01).

CONCLUSIONS

These findings support ASAT as a significant driver of cardiometabolic disease in African Ancestry populations, independent of other abdominal and thigh tissues.

Pim1 knockout alleviates sarcopenia in aging mice via reducing adipogenic differentiation of PDGFRα+ mesenchymal progenitors

BACKGROUND

Sarcopenia widely exists in elderly people and triggers numerous age-related events. The essential pathologic change lies in the increased intramuscular adipose tissue after aging with no exception to non-obese objects. Pim1 appears to be associated with adipogenic differentiation in recent studies, inspiring us to explore whether it regulates adipogenesis in aging muscles and affects sarcopenia.

METHODS

Wild-type and Pim1 knockout C57/BL6J mice were randomized into young and old groups. Histo-pathological and molecular biological methods were applied to assess the intramuscular adipose tissue content, the atrophy and regeneration, and the expressions of Pim1 and adipogenic transcription factors. PDGFRα+ mesenchymal progenitors were separated and their replicative aging model were established. Different time of adipogenic induction and different amounts of Pim1 inhibitor were applied, after which the adipogenic potency were evaluated. The expressions of Pim1 and adipogenic transcription factors were measured through western blotting.

RESULTS

The aging mice demonstrated decreased forelimb grip strength (P = 0.0003), hanging impulse (P < 0.0001), exhaustive running time (P < 0.0001), tetanic force (P = 0.0298), lean mass (P = 0.0008), and percentage of gastrocnemius weight in body weight (P < 0.0001), which were improved by Pim1 knockout (P = 0.0015, P = 0.0222, P < 0.0001, P = 0.0444, P = 0.0004, and P = 0.0003, respectively). To elucidate the mechanisms, analyses showed that Pim1 knockout decreased the fat mass (P = 0.0005) and reduced the intramuscular adipose tissue content (P = 0.0008) by inhibiting the C/EBPδ pathway (P = 0.0067) in aging mice, resulting in increased cross-sectional area of all and fast muscle fibres (P = 0.0017 and 0.0024 respectively), decreased levels of MuRF 1 and atrogin 1 (P = 0.0001 and 0.0329 respectively), and decreased content of Pax7 at the basal state (P = 0.0055). In vitro, senescent PDGFRα+ mesenchymal progenitors showed significantly increased the intracellular adipose tissue content (OD510) compared with young cells after 6 days of adipogenic induction (P < 0.0001). The Pim1 expression was elevated during adipogenic differentiation, and Pim1 inhibition significantly reduced the OD510 in senescent cells (P = 0.0040) by inhibiting the C/EBPδ pathway (P = 0.0047).

CONCLUSIONS

Pim1 knockout exerted protective effects in sarcopenia by inhibiting the adipogenic differentiation of PDGFRα+ mesenchymal progenitors induced by C/EBPδ activation and thus reducing the intramuscular adipose tissue content in aging mice. These results provide a potential target for the treatment of sarcopenia.

Quality Matters as Much as Quantity of Skeletal Muscle: Clinical Implications of Myosteatosis in Cardiometabolic Health

Although age-related changes in skeletal muscles are closely associated with decreases in muscle strength and functional decline, their associations with cardiometabolic diseases in the literature are inconsistent. Such inconsistency could be explained by the fact that muscle quality-which is closely associated with fatty infiltration of the muscle (i.e., myosteatosis)-is as important as muscle quantity in cardiometabolic health. However, muscle quality has been less explored compared with muscle mass. Moreover, the standard definition of myosteatosis and its assessment methods have not been established yet. Recently, some techniques using single axial computed tomography (CT) images have been introduced and utilized in many studies, as the mass and quality of abdominal muscles could be measured opportunistically on abdominal CT scans obtained during routine clinical care. Yet, the mechanisms by which myosteatosis affect metabolic and cardiovascular health remain largely unknown. In this review, we explore the recent advances in the assessment of myosteatosis and its changes associated with aging. We also review the recent literature on the clinical implication of myosteatosis by focusing on metabolic and cardiovascular diseases. Finally, we discuss the challenges and unanswered questions that need addressing to set myosteatosis as a therapeutic target for the prevention or treatment of cardiometabolic diseases.

Cachexia Versus Sarcopenia in Clinical Characteristics and Prognostic Value After Radical Gastrectomy for Gastric Cancer: A Large-Scale Prospective Study

BACKGROUND

Sarcopenia and cachexia are two predictors of adverse clinical outcomes, but they are partly overlapping. We aimed to compare the characteristics and prognostic value of cachexia and sarcopenia in patients after gastrectomy.

METHODS

From 2014 to 2019, a total of 1215 gastric cancer patients were enrolled. Cachexia and sarcopenia were diagnosed according to the most recent consensus definitions. Baseline characteristics and clinical outcomes were compared between the two groups. Risk factors of survival were evaluated by Cox regression analysis.

RESULTS

Of all patients, 26.5% were diagnosed with cachexia and 19.8% were diagnosed with sarcopenia. Sarcopenia was more prevalent in elderly patients, while cachexia was prone to occur in patients with TMN stage III. Survival curves showed that sarcopenia had adverse effects in patients with TMN stage I and II-III, while cachexia was only associated with poor survival at stages II-III. For the entire cohort, both cachexia and sarcopenia were adverse factors for prognosis. However, for stage I patients, sarcopenia was an independent predictor for overall survival (OS) (HR = 4.939, P < 0.001) and disease-free survival (DFS) (HR = 4.256, P < 0.001), but not cachexia; for stage II-III patients, cachexia was an independent predictor for OS (HR = 1.538, P < 0.001) and DFS (HR = 1.473, P = 0.001), but not sarcopenia.

CONCLUSIONS

Sarcopenia and cachexia have different clinical characteristics and prognostic values. For patients with early stage gastric cancer, detection for sarcopenia was more meaningful than cachexia. However, the prognostic significance of cachexia exceeded sarcopenia in advanced cancer.

Skeletal muscle-adipose cocultured tissue fabricated using cell-laden microfibers and a hydrogel sheet

The emerging interest in skeletal muscle tissue originates from its unique properties that control body movements. In particular, recent research advances in engineered skeletal muscle tissue have broadened the possibilities of applications in nonclinical models. However, due to the lack of adipose tissue, current engineered skeletal muscle tissue has the limitation of satisfying in vivo-like position and proportion of intermuscular fat. Adipose tissue within the skeletal muscle affects their functional properties. Here, a fabrication method for cocultured tissue composed of skeletal muscle and adipose tissues is proposed to reproduce the functional and morphological characteristics of muscle. By implementing prematured adipose microfibers in a myoblast-laden hydrogel sheet, both the accumulation of large lipid droplets and control of the position of adipose tissue within the skeletal muscle tissue becomes feasible. The findings of this study provide helpful information regarding engineered skeletal muscle, which has strong potential in drug screening models.