Mechanism of increased risk of insulin resistance in aging skeletal muscle

Unraveling the role of muscle mass and strength in predicting type 2 diabetes risk: a systematic review

INTRODUCTION

Skeletal muscle is the largest insulin-sensitive tissue in the human body, alteration in muscle mass and strength substantially impact glucose metabolism. This systematic review aims to investigate further the relationship between muscle mass and strength towards type 2 diabetes mellitus (T2DM) incidence.

METHODS

This systematic review included cohort studies that examinedthe relationship between muscle mass and/or muscle strength on T2DM incidence. A comprehensive search was conducted across PubMed, EBSCO, ProQuest, and Google scholar employing specific Medical Subject Headings (MeSH) and relevant keywords related to or synonymous with "muscle mass", "muscle strength", and "Type 2 Diabetes Mellitus incidence".

RESULTS

Twenty-five cohort studies were included, 11 studies on muscle mass and 16 studies on muscle strength. Participants included were 278,475 for muscle mass and 400,181 for muscle strength. Skeletal muscle mass normalized to body weight (SMM/BW), appendicular skeletal musce mass normalized to body weight (ASM/BW), and handgrip strength normalized to body mass index (HGS/BMI) consistently demonstrate significant inverse association with T2DM even after sex and/or BMI stratification. Handgrip strength normalized to body weight (HGS/BW) demonstrates a strong inverse association with T2DM incidence, however, adiposity should be considered.

CONCLUSION

Muscle mass and strength demonstrate strong association with T2DM incidence. Adiposity, a key T2DM risk factor, should also be assessed through a simple BMI or a sophisticated technique with BIA or CT-scan. The combination of muscle variables and adiposity could further enhance T2DM risk assessment. However, T2DM risks are multifactorial, with various contributing factors, further large-scale studies are needed to validate these findings.

Plant-Derived Treatments for Different Types of Muscle Atrophy

With the development of medicine and chemistry, an increasing number of plant-derived medicines have been shown to exert beneficial therapeutic on the treatment of various physical and psychological diseases. In particular, by using physical chemistry methods, we are able to examine the chemical components of plants and the effects of these substances on the human body. Muscle atrophy (MA) is characterized by decreased muscle mass and function, is caused by multiple factors and severely affects the quality of life of patients. The multifactorial and complex pathogenesis of MA hinders drug research and disease treatment. However, phytotherapy has achieved significant results in the treatment of MA. We searched PubMed and the Web of Science for articles related to plant-derived substances and muscle atrophy. After applying exclusion and inclusion criteria, 166 and 79 articles met the inclusion criteria, respectively. A total of 173 articles were included in the study after excluding duplicates. The important role of phytoactives such as curcumin, resveratrol, and ginsenosides in the treatment of MA (e.g., maintaining a positive nitrogen balance in muscles and exerting anti-inflammatory and antioxidant effects) has been extensively studied. Unfortunately, MA dose not have to a single cause, and each cause has its own unique mechanism of injury. This review focuses on the therapeutic mechanisms of active plant components in MA and provides insights into the personalized treatment of MA.

Handgrip strength and diabetes in postmenopausal women: insights from the Korean National Health and Nutrition Examination Survey 2014-2019

OBJECTIVE

This study aimed to investigate the association between handgrip strength (HGS) and diabetes mellitus (DM) in postmenopausal women in Korea relative to the menopausal duration.

METHODS

Data from the Korean National Health and Nutrition Examination Survey conducted between 2014 and 2019 were analyzed. A total of 4,098 postmenopausal women aged 45 to 65 years were included in the study. Handgrip strength was measured using a digital hand dynamometer. Participants were categorized into quartiles based on HGS with Q1 representing the weakest strength and Q4 the greatest strength. The association between DM and HGS was assessed using logistic regression analysis while adjusting for relevant covariates.

RESULTS

Postmenopausal women aged 45 to 65 years with stronger HGS were less likely to have DM ( P < 0.001). This association persisted even after adjusting for age, body mass index, and comorbidities ( P < 0.001). The inverse relationship between HGS and DM prevalence was more pronounced in women who had been postmenopausal for >10 years than in those who had been postmenopausal for a shorter duration (P-interaction <0.001). In addition, compared to their nondiabetic counterparts, women with DM were less likely to be categorized into the Q4 group ( P < 0.001).

CONCLUSIONS

The findings suggest that weaker HGS was associated with likelihood of having DM among postmenopausal women in Korea. Owing to the inherent limitation to the cross-sectional study design, further research is warranted to elucidate the underlying mechanisms of the association between DM and HGS in postmenopausal women.

Associations of long-term nitrogen dioxide exposure with a wide spectrum of diseases: a prospective cohort study of 0·5 million Chinese adults

BACKGROUND

Little evidence is available on the long-term health effects of nitrogen dioxide (NO2) in low-income and middle-income populations. We investigated the associations of long-term NO2 exposure with the incidence of a wide spectrum of disease outcomes, based on data from the China Kadoorie Biobank.

METHODS

This prospective cohort study involved 512 724 Chinese adults aged 30-79 years recruited from ten areas of China during 2004-08. Time-varying Cox regression models yielded adjusted hazard ratios (HRs) for the associations of long-term NO2 exposure with aggregated disease incidence endpoints classified by 14 ICD-10 chapters, and incidences of 12 specific diseases selected from three key ICD-10 chapters (cardiovascular, respiratory, and musculoskeletal diseases) found to be robustly associated with NO2 in the analyses of aggregated endpoints. All models were stratified by age-at-risk (in 1-year scale), study area, and sex, and were adjusted for education, household income, smoking status, alcohol intake, cooking fuel type, heating fuel type, self-reported health status, BMI, physical activity level, temperature, and relative humidity.

FINDINGS

The analysis of 512 709 participants (mean baseline age 52·0 years [SD 10·7]; 59·0% female and 41·0% male) included approximately 6·5 million person-years of follow-up. Between 5285 and 144 852 incident events were recorded for each of the 14 aggregated endpoints. Each 10 μg/m3 higher annual average NO2 exposure was associated with higher risks of chapter-specific endpoints, especially cardiovascular (n=144 852; HR 1·04 [95% CI 1·02-1·05]), respiratory (n=73 232; 1·03 [1·01-1·05]), musculoskeletal (n=54 409; 1·11 [1·09-1·14]), and mental and behavioural (n=5361; 1·12 [1·05-1·21]) disorders. Further in-depth analyses on specific diseases found significant positive supra-linear associations with hypertensive disease (1·08 [1·05-1·11]), lower respiratory tract infection (1·03 [1·01-1·06]), arthrosis (1·15 [1·09-1·21]), intervertebral disc disorders (1·13 [1·09-1·17]), and spondylopathies (1·05 [1·01-1·10]), and linear associations with ischaemic heart disease (1·03 [1·00-1·05]), ischaemic stroke (1·08 [1·06-1·11]), and asthma (1·15 [1·04-1·27]), whereas intracerebral haemorrhage (1·00 [0·95-1·06]), other cerebrovascular disease (0·98 [0·96-1·01]), acute upper respiratory infection (1·03 [0·96-1·09]), and chronic lower respiratory disease (0·98 [0·95-1·02]) showed no significant association. NO2 exposure showed robust null association with external causes (n=32 907; 0·98 [0·95-1·02]) as a negative control.

INTERPRETATION

In China, long-term NO2 exposure was associated with a range of diseases, particularly cardiovascular, respiratory, and musculoskeletal diseases. These associations underscore the pressing need to implement the recently tightened WHO air quality guidelines.

FUNDING

Wellcome Trust, UK Medical Research Council, Cancer Research UK, British Heart Foundation, National Natural Science Foundation of China, National Key Research and Development Program of China, Sino-British Fellowship Trust, and Kadoorie Charitable Foundation.

New insight on the potential detrimental effect of metabolic syndrome on the Alzheimer disease neuropathology: Mechanistic role

The metabolic syndrome or syndrome X is a clustering of different components counting insulin resistance (IR), glucose intolerance, visceral obesity, hypertension and dyslipidemia. It has been shown that IR and dysregulation of insulin signalling play a critical role in the development of metabolic syndrome by initiating the pathophysiology of metabolic syndrome through induction of glucolipotoxicity, impairment of glucose disposal and triggering of pro-inflammatory response. Furthermore, metabolic syndrome unfavourably affects the cognitive function and the development of different neurodegenerative diseases such as Alzheimer disease (AD) by inducing oxidative stress, neuroinflammation and brain IR. These changes together with brain IR impair cerebrovascular reactivity leading to cognitive impairment. In addition, metabolic syndrome increases the risk for the development of AD. However, the central mechanisms by which metabolic syndrome amplify AD risk are not completely elucidated. Consequently, this narrative review aims to revise from published articles the association between metabolic syndrome and AD regarding cellular and subcellular pathways. In conclusion, metabolic syndrome is regarded as a potential risk factor for the induction of AD neuropathology by different signalling pathways such as initiation of brain IR, activation of inflammatory signalling pathways and neuroinflammation.

Prognostic Impact and Prevalence of Cachexia in Patients With Heart Failure: A Systematic Review and Meta-Analysis

BACKGROUND

Cachexia, defined as the combination of weight loss, weakness, fatigue, anorexia and abnormal biochemical markers based on Evans' criteria, is known to exacerbate the prognosis of heart failure (HF) patients. This systematic review and meta-analysis investigates the prognostic impact and prevalence of cachexia, as defined by Evans' criteria, in patients with HF.

METHODS

PubMed, Cochrane Library, Scopus and Web of Science were searched from inception until December 2023, including HF patients for whom the Evans' criteria were applied to explore the prevalence and prognostic impact of cachexia. This study employed a meta-analyses using the random-effects model and inverse-variance method that was adhered to the revised 2020 PRISMA guidelines for systematic reviews and meta-analyses (CRD42023446443).

RESULTS

Six prospective or retrospective studies of 2252 patients with HF were included, whereby all-cause mortality was significantly greater in patients with cachexia with low heterogeneity among studies (HR: 1.60, 95% CI 1.31-1.95, p < 0.001; I2 = 0%). For the studies that used full, uniformly defined Evans' criteria, among 1844 patients, mortality remained greater in patients with cachexia (HR: 1.58, 95% CI 1.27-1.97, p < 0.001; I2 = 0%). In a subgroup analysis among 1714 of HF with reduced ejection fraction, the results were consistent (HR: 1.57, 95% CI 1.28-1.92, p < 0.001; I2 = 0%). Additionally, 10 studies comprising 2862 patients indicated a 31% risk of cachexia in HF (95% CI 21-43%, I2 = 94%).

CONCLUSIONS

Cachexia is an independent predictor for increased all-cause mortality among patients with HF with a notable prevalence of 31%. Interventions aiding in improving fatigue, anorexia and exercise capacity could help improve the quality of life of this clinical population.

Glucose metabolism and radiodensity of abdominal adipose tissue: A 5-year longitudinal study in a large PET cohort

OBJECTIVE

18F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) allows noninvasive assessment of glucose metabolism and radiodensity in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). We aimed to address the effects of ageing and metabolic factors on abdominal adipose tissue.

DESIGN, PATIENTS AND MEASUREMENTS

We retrospectively analyzed data from 435 healthy men (mean 42.8 years) who underwent a health check-up programme twice, at baseline and the 5-year follow-up. The mean standardized uptake value (SUV) was measured using SAT and VAT and divided by the liver SUV. The mean Hounsfield units (HU) of the SAT and VAT were measured from the CT scans. The effects of clinical variable clusters on SUVR were investigated using Bayesian hierarchical modelling; metabolic cluster (BMI, waist-to-hip ratio, fat percentage, muscle percentage*-1, HOMA-IR), blood pressure (systolic, diastolic), glucose (fasting plasma glucose level, HbA1c) and C-reactive protein.

RESULTS

All the clinical variables changed during the 5-year follow-up period. The SUVR and HU of the VAT increased during follow-up; however, those of the SAT did not change. SUVR and HU were positively correlated with both VAT and SAT. SAT and VAT SUVR were negatively associated with metabolic clusters.

CONCLUSIONS

Ageing led to increased glucose metabolism and radiodensity in VAT, but not in SAT. VAT may reflect the ageing process more directly than SAT. Glucose metabolism was higher and radiodensity was lower in VAT than in SAT, probably owing to differences in gene expression and lipid density. Both glucose metabolism and radiodensity of VAT and SAT reflect metabolic status.

Dietary Intake of Polyunsaturated Fatty Acids Is Associated with Blood Glucose and Diabetes in Community-Dwelling Older Adults

OBJECTIVES

The present study was conducted to examine the cross-sectional associations between the dietary intake of polyunsaturated fatty acids (PUFAs) and cardiometabolic risk factors in a large sample of Italian community-dwelling older adults.

METHODS

This is a cross-sectional study. Longevity Check-up 8+ (Lookup 8+) is an ongoing project that started in June 2015. The project is conducted in unconventional settings (e.g., exhibitions, malls, and health promotion campaigns) across Italy with the aim of fostering the adoption of healthy lifestyles in the general population. For the present study, participants were eligible if they were 65+ years and provided written informed consent. Systolic blood pressure (SBP) and diastolic blood pressure (DBP), and blood glucose and cholesterol levels were assessed. A 12-item food frequency questionary was used to estimate the dietary intake of PUFAs, which included omega-3 (α-linolenic acid [ALA], eicosapentaenoic acid [EPA], and docosahexaenoic acid [DHA]) and omega-6 fatty acids.

RESULTS

Data of 4461 older adults (♀56%, mean age: 72.9 years, mean body mass index [BMI]: 26.1 kg/m2, blood glucose: 109 mg/dL, total blood cholesterol: 198.5 mg/dL, ALA: 8.8%, EPA: 16.0%, and DHA: 26.1%) were cross-sectionally analyzed. Multilinear regression results indicated that a high consumption of EPA, DHA, and DHA+EPA was negatively and significantly associated with glucose levels. Furthermore, binary regression analysis indicated that the dietary intake of ALA and omega-6 PUFAs was inversely and significantly associated with the prevalence of diabetes. In contrast, BMI values were positively associated with ALA and omega-6 PUFAs, and negatively with the consumption of EPA and DHA+EPA.

CONCLUSIONS

Findings of the present study indicate that the dietary intake of PUFAs was cross-sectionally, inversely, and significantly associated with blood glucose levels and the prevalence of diabetes in a large sample of Italian community-dwelling older adults.

Fasting plasma glucose trends in the elderly living with HIV/AIDS on combination antiretroviral therapy regimens

BACKGROUND

With the ageing of people living with HIV/AIDS (PLWHA), the prevalence of chronic comorbidities, especially hyperglycaemia, is increasing among elderly PLWHA. Antiretroviral therapy (ART) is associated with fasting plasma glucose (FPG) levels. This study aimed to investigate both short-term and long-term FPG characteristics and trends across different ART regimens in elderly Chinese PLWHA.

METHODS

This retrospective cohort study, based on hospital treatment information, classified ART regimens as this retrospective cohort study used hospital treatment data. ART regimens are classified into three categories: non-nucleoside reverse transcriptase inhibitors (NNRTIs) based, protease inhibitors (PIs) based and integrase strand transfer inhibitor (INSTIs) based. Propensity score matching was applied to control for confounding factors. Follow-up FPG characteristics were then described, and a generalised linear mixed model was employed to estimate FPG trends under different regimens within 1-year and 5-year periods following ART initiation.

RESULTS

Participants had an average age of 58.28 years, with 75.02% male. FPG increased following ART initiation, with the most significant rise within 1 year of ART, followed by stabilisation. The FPG increase within 1 year was slower in the PIs-based group compared with the NNRTIs-based group (β=-0.08, 95% CI -0.15 to -0.01), while there was a higher prevalence of diabetes within 5 years of ART (31.55% vs 22.33%, standardised difference=0.357). The FPG increase within 1 year of ART did not differ between NNRTIs-based and INSTIs-based groups (β=-0.01, 95% CI -0.20, 0.18).

CONCLUSION

Our study highlights that elderly Chinese PLWHA experience an increase in FPG levels, particularly during the first year of ART, with variations observed across different ART regimens. The higher long-term prevalence of diabetes in the PIs-based regimen group emphasises the need for tailored glucose management strategies. Routine glucose monitoring and proactive management are crucial for preventing and controlling diabetes in this population, particularly given the long-term metabolic risks associated with ART.

Association of Body Composition Changes with the Development of Diabetes Mellitus: A Nation-Wide Population Study

BACKGRUOUND

We investigated the association between body composition changes and new-onset diabetes mellitus (DM) development according to the body mass index (BMI) in a longitudinal setting in the general Korean population.

METHODS

From 2010 to 2011 (1st) and 2012 to 2013 (2nd), we included 1,607,508 stratified random sample participants without DM from the National Health Insurance Service-Health Screening dataset of Korean. The predicted appendicular skeletal muscle mass index (pASMMI), body fat mass index (pBFMI), and lean body mass index (pLBMI) were calculated using pre-validated anthropometric prediction equations. A prediction equation was constructed by combining age, weight, height, waist circumference, serum creatinine levels, alcohol consumption status, physical activity, and smoking history as variables affecting body composition.

RESULTS

Decreased pASMMI (men: hazard ratio [HR], 0.866; 95% confidence interval [CI], 0.830 to 0.903; P<0.001; women: HR, 0.748; 95% CI, 0.635 to 0.881; P<0.001), decreased pLBMI (men: HR, 0.931; 95% CI, 0.912 to 0.952; P<0.001; women: HR, 0.906; 95% CI, 0.856 to 0.959; P=0.007), and increased pBFMI (men: HR, 1.073; 95% CI, 1.050 to 1.096; P<0.001; women: HR, 1.114; 95% CI, 1.047 to 1.186; P=0.007) correlated with the development of new-onset DM. Notably, only in the overweight and obese BMI categories, decreases in pASMMI and pLBMI and increases in pBFMI associated with new-onset DM, regardless of gender.

CONCLUSION

Decreased pASMMI and pLBMI, and increased pBFMI with excess fat accumulation may enhance the risk of newonset DM. Therefore, appropriate changes in body composition can help prevent new-onset DM.

A novel treatment strategy targeting cellular pathways with natural products to alleviate sarcopenia

Sarcopenia is a condition marked by a significant reduction in muscle mass and strength, primarily due to the aging process, which critically impacts muscle protein dynamics, metabolic functions, and overall physical functionality. This condition leads to increased body fat and reduced daily activity, contributing to severe health issues and a lower quality of life among the elderly. Recognized in the ICD-10-CM only in 2016, sarcopenia lacks definitive treatment options despite its growing prevalence and substantial social and economic implications. Given the aging global population, addressing sarcopenia has become increasingly relevant and necessary. The primary causes include aging, cachexia, diabetes, and nutritional deficiencies, leading to imbalances in protein synthesis and degradation, mitochondrial dysfunction, and hormonal changes. Exercise remains the most effective intervention, but it is often impractical for individuals with limited mobility, and pharmacological options such as anabolic steroids and myostatin inhibitors are not FDA-approved and are still under investigation. This review is crucial as it examines the potential of natural products as a novel treatment strategy for sarcopenia, targeting multiple mechanisms involved in its pathogenesis. By exploring natural products' multi-targeted effects, this study aims to provide innovative and practical solutions for sarcopenia management. Therefore, this review indicates significant improvements in muscle mass and function with the use of specific natural compounds, suggesting promising alternatives for those unable to engage in regular physical activity.

Age-related differences in fluctuations in insulin resistance evaluated with HOMA-IR and triglyceride and glucose-based indices during the menstrual cycle, as determined using the NHANES cross-sectional dataset

OBJECTIVES

To determine how age affects insulin resistance during the menstrual cycle and insulin resistance-associated indices: the Triglyceride-glucose and Triglyceride-glucose-BMI indexes.

METHODS

This prospective observational study used fasting plasma glucose, fasting insulin, triglycerides, body mass index (BMI), and days since the start of the menstrual period collected from the NHANES dataset (1999-2006). Insulin resistance was determined using the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). The participants were categorized as young (16-34 years) or older (>35 years). Rhythmicity during the menstrual cycle was analyzed using the Cosinor and Cosinor2 packages for R.

MAIN OUTCOME MEASURES

Cosine fit curves for insulin resistance during the menstrual cycle and age-associated effects on rhythmicity.

RESULTS

Using 1256 participants, rhythmicity was observed for fasting insulin and HOMA-IR (p < 0.05) but not for fasting plasma glucose, the Triglyceride-glucose index, or the Triglyceride-glucose-BMI index. Significant amplitudes for fasting insulin and HOMA-IR were observed when age was considered. Acrophases for fasting insulin and HOMA-IR were significant only for the younger group, and the differences between these groups were significant, suggesting that the changes in scores for insulin resistance for the younger and older groups occur at different times of their menstrual cycle.

CONCLUSIONS

Insulin resistance does fluctuate during the menstrual cycle, and it is at a maximum at different times for younger and older women. Since these results are unadjusted, this study is preliminary and further investigation is required.

Differential impacts of fat and muscle mass on cardiovascular and non-cardiovascular mortality in individuals with type 2 diabetes

BACKGROUND

The distribution of fat and muscle mass in different regions of the body can reflect different pathways to mortality in individuals with diabetes. Therefore, we investigated the associations between whole-body and regional body fat and muscle mass with cardiovascular disease (CVD) and non-CVD mortality in type 2 diabetes (T2D).

METHODS

Within the National Health and Nutrition Examination Survey 1999-2006, 1417 adults aged ≥50 years with T2D were selected. Dual-energy X-ray absorptiometry was used to derive whole-body, trunk, arm, and leg fat mass and muscle mass indices (FMI and MMI). Mortality data until 31 December 2019 were retrieved from the National Death Index. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated from Cox proportional hazard models.

RESULTS

A total of 1417 participants were included in this study (weighted mean age [standard error]: 63.7 [0.3] years; 50.5% female). Over a median follow-up of 13.6 years, 797 deaths were recorded (371 CVD-related and 426 non-CVD deaths). Higher FMI in the arm was associated with increased risk of non-CVD mortality (fourth quartile [Q4] vs. first quartile [Q1]: HR 1.82 [95% CI 1.13-2.94]), whereas higher FMI in the trunk or leg was not significantly associated with CVD or non-CVD mortality. Conversely, higher arm MMI was associated with a lower risk of both CVD (Q4 vs. Q1: HR 0.51 [95% CI 0.33-0.81]) and non-CVD (Q4 vs. Q1: HR 0.56 [95% CI 0.33-0.94]) mortality. There was a significant interaction between smoking status and arm FMI on non-CVD mortality (P for interaction = 0.007). Higher arm FMI was associated with a higher risk of non-CVD mortality among current or former smokers (Q4 vs. Q1: HR 2.67 [95% CI 1.46-4.88]) but not non-smokers (Q4 vs. Q1: HR 0.85 [95% CI 0.49-1.47]).

CONCLUSIONS

Fat mass and muscle mass, especially in the arm, are differently associated with CVD and non-CVD mortality in people with T2D. Our findings underscore the predictive value of body compositions in the arm in forecasting mortality among older adults with T2D.

Effects of night-to-night variations in objectively measured sleep on blood glucose in healthy university students

STUDY OBJECTIVES

We examined associations between daily variations in objectively measured sleep and blood glucose in a sample of non-diabetic young adults to complement laboratory studies on how sleep affects blood glucose levels.

METHODS

119 university students underwent sleep measurement using an Oura Ring 2 and continuous glucose monitoring (CGM) for up to 14 days. In 69 individuals who consumed a standardised diet across the study, multilevel models examined associations between sleep duration, timing and efficiency and daily CGM profiles. Separately, in 58 individuals, multilevel models were used to evaluate postprandial glycaemic responses to a test meal challenge on 7 days. Participants also underwent oral glucose tolerance testing once after a night of ad libitum sleep, and again following a night of sleep restriction by 1-2 hours relative to that individual's habitual sleep duration. Between-condition glucose and insulin excursions, HOMA-IR and Matsuda index were compared.

RESULTS

Nocturnal sleep did not significantly influence following-day CGM profiles, postprandial glucose, or nocturnal mean glucose levels (all Ps>0.05). Longer sleep durations were associated with lower same-night glucose variability (all Ps<0.001). However, the range of variation of sugar levels was small and unlikely to be of functional significance. Considering naps in the analysis did not alter the findings. Sleep restriction by an average of 1.73 hours (SD=0.97) did not significantly impact excursions in glucose or insulin or insulin sensitivity the following morning (all Ps>0.05).

CONCLUSIONS

Glucose handling in young, healthy adults may be more resilient to real-life fluctuations in sleep patterns than previously thought.

Reliability of In Vivo Creatine-Weighted Chemical Exchange Saturation Transfer (CrCEST) MRI in Calf Skeletal Muscle of Healthy Volunteers at 3 T

BACKGROUND

Skeletal muscle mitochondrial oxidative phosphorylation (mtOXPHOS) is important for ATP generation and its dysfunction leads to exercise intolerance. Phosphorus magnetic resonance spectroscopy (31P-MRS) is a useful, noninvasive technique for mtOXPHOS assessment but has limitations. Creatine-weighted chemical exchange saturation transfer (CrCEST) MRI is a potential alternative to assess muscle bioenergetics.

PURPOSE

To evaluate the interscan repeatability, intra- and interobserver reproducibility of CrCEST during mild plantar flexion exercise.

STUDY TYPE

Retrospective.

SUBJECTS

Twenty healthy volunteers (age 37.6 ± 12.4 years, 11 females).

FIELD STRENGTH/SEQUENCE

3 T/CEST imaging using gradient echo readout.

ASSESSMENT

τCrCEST (postexercise Cr recovery time) was assessed in two scans for each participant, following mild plantar flexion exercises targeting the medial gastrocnemius (MG), lateral gastrocnemius (LG), and soleus (Sol) muscles. Three observers measured τCrCEST for interobserver reproducibility. Three readings by one observer were used to measure intraobserver reproducibility. Two scans were used for within-participant interscan repeatability.

STATISTICAL TESTS

Paired t tests, intraclass correlation coefficient (ICC), and Pearson correlation were conducted. Bland-Altman plots were used to analyze the interobserver variability. A P-value of 0.05 was considered statistically significant.

RESULTS

There was excellent intra- (ICC∈ 0.94 - 0.98 $$ \in \left[0.94-0.98\right] $$ ) and interobserver (ICC∈ 0.9 - 0.98 $$ \in \left[0.9-0.98\right] $$ ) reproducibility, with moderate interscan repeatability for τCrCEST in LG and MG (ICC∈ 0.54 - 0.74 $$ \in \left[0.54-0.74\right] $$ ) and poor-to-moderate interscan repeatability in Sol (ICC∈ 0.24 - 0.53 $$ \in \left[0.24-0.53\right] $$ ). Excellent interobserver reproducibility was confirmed by Bland-Altman plots (fixed bias P-value∈ 0.08 - 0.87 $$ \in \left[0.08-0.87\right] $$ ).

DATA CONCLUSION

CrCEST MRI shows promise in assessing muscle bioenergetics by evaluating τCrCEST during mild plantar flexion exercise with reasonable reliability, particularly in LG and MG.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY: Stage 1.

Nitric oxide in modulating oxidative stress mediated skeletal muscle insulin resistance

Insulin resistance (IR) being the major cause behind different metabolic disorders, has attracted a lot of attention. Epidemiological data shows marked rise in the cases over a period of time. Nitric oxide (NO), produced from nitric oxide synthases (NOS), is involved in a variety of biological functions, alteration in which causes various disorders like hypertension, atherosclerosis, and angiogenesis-associated disorders. IR has been found to be a contributing factor, which is associated with abnormal NO signalling. Skeletal muscle is essential for metabolism, both for its role in glucose uptake and its importance in metabolic disease. In this article, we give an overview of the significance of NO in oxidative stress (OS) mediated IR, describing its role in different conditions that are associated with skeletal muscle IR. NO is found to be involved in the activation of insulin receptor downstream pathway, which suggests absence of NO could lead to reduced glucose uptake, and may ultimately result in IR.

Sex difference in the association between creatinine-to-cystatin C ratio and metabolic syndrome among Chinese adults

Background

Metabolic syndrome (MetS), characterized by central obesity, insulin resistance, dyslipidemia, and hypertension, affects 20-25% of the global population. The creatinine-to-cystatin C ratio (CCR) is an indicator of skeletal muscle mass. While CCR may play a role in MetS development, sex differences in these associations are not fully understood. Therefore, this study aimed to investigate how CCR levels are associated with MetS in a Chinese adult population, focusing on possible sex disparities.

Method

We conducted a retrospective cross-sectional analysis of 9,376 adults from Xiamen Chang Gung Hospital between 2014 to 2016. We examined the relationship between CCR and MetS, adjusting for cardiometabolic risk factors.

Results

The prevalence of MetS was 24.7% in males and 18.0% in females. Interestingly, we observed significant sex differences in the association between CCR quartiles and MetS. Females in the lowest CCR quartile had a significantly higher risk of MetS (odds ratio=1.84). Receiver operating characteristic curve analysis revealed acceptable diagnostic power of CCR for MetS in females (area under the curve=0.65) but not in males.

Conclusion

Our findings suggest that CCR is an independent risk factor for MetS in females, highlighting the importance of sex-specific assessments when evaluating MetS risk.

The SIRT3/GSK-3β/GLUT4 axis might be involved in maternal hypoxia-induced skeletal muscle insulin resistance in old male rat offspring

Maternal hypoxia is strongly linked to insulin resistance (IR) in adult offspring, and altered insulin signaling for muscle glucose uptake is thought to play a central role. However, whether the SIRT3/GSK-3β/GLUT4 axis is involved in maternal hypoxia-induced skeletal muscle IR in old male rat offspring has not been investigated. Maternal hypoxia was established from Days 5 to 21 of pregnancy by continuous infusion of nitrogen and air. The biochemical parameters and levels of key insulin signaling molecules of old male rat offspring were determined through a series of experiments. Compared to the control (Ctrl) old male rat offspring group, the hypoxic (HY) group exhibited elevated fasting blood glucose (FBG) (∼30%), fasting blood insulin (FBI) (∼35%), total triglycerides (TGs), and low-density lipoprotein cholesterol (LDL-C), as well as results showing impairment in the glucose tolerance test (GTT) and insulin tolerance test (ITT). In addition, hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM) revealed impaired cellular structures and mitochondria in the longitudinal sections of skeletal muscle from HY group mice, which might be associated with decreased SIRT3 expression. Furthermore, the expression of insulin signaling molecules, such as GSK-3β and GLUT4, was also altered. In conclusion, the present results indicate that the SIRT3/GSK-3β/GLUT4 axis might be involved in maternal hypoxia-induced skeletal muscle IR in old male rat offspring.

Trends in diabetic ketoacidosis in Victoria, Australia 2002-2016

BACKGROUND

International longitudinal studies have indicated an increasing incidence of diabetic ketoacidosis (DKA). We aim to examine the incident trends, demographic differences, length of stay and mortality for DKA in adults with type 1 diabetes (T1D) and type 2 diabetes (T2D) in Victoria, Australia from 2002 to 2016.

METHODS

Age and sex adjusted incident trends, length of stay and mortality for DKA was retrospectively obtained using the Victorian Admitted Episode Dataset between 2002 and 2016. Data for adults with T1D and T2D was obtained from the National Diabetes Services Scheme (NDSS). Joinpoint regression analysis was used to identify changes in linear trends that were described as average annual percentage change (AAPC).

RESULTS

There were 23,628 DKA presentations in Victoria between 2002 and 2016. For T1D there was an increase in DKA presentations (AAPC + 6.8%) from 2003 to 2016 and for T2D there was a decline from 2003 to 2011 (APC - 3.5%), increase from 2011 to 2014 (APC + 38.5%), and a decrease from 2014 to 2016 (APC - 20.9%). Length of stay was longer for people with T2D than T1D (P < 0.001) and the mortality rate was 0.51% for the study period.

CONCLUSIONS

DKA rates increased for T2D from 2011 to 2014 which correlates with the introduction of sodium glucose-linked transport protein 2 inhibitors. However, the aetiology for the observed increase in T1D from 2002 to 2016 remains unknown.

Role of Decreased Expression of miR-155 and miR-146a in Peripheral Blood of Type 2 Diabetes Mellitus Patients with Diabetic Peripheral Neuropathy

Objective

To Study the Correlations of microRNA-155 (miR-155) and microRNA-146a (miR-146a) Expression in Peripheral Blood of Type 2 Diabetes Mellitus (T2DM) Patients with Diabetic Peripheral Neuropathy (DPN), and Explore the Clinical Value of miR-155 and miR-146a in the Diagnosis and Treatment Outcomes of DPN.

Methods

The study included 51 T2DM patients without DPN (T2DM group), 49 T2DM patients with DPN (DPN group), and 50 normal controls (NC group). Quantitative real-time PCR was utilized to determine the expression levels of miR-155 and miR-146a. Clinical features and risk factors for DPN were assessed. Multivariate stepwise logistic regression analysis was conducted to confirm whether the expressions of miR-155 and miR-146a could independently predict the risk of DPN. ROC curve analysis evaluated their diagnostic value.

Results

The T2DM group exhibited significantly lower expression levels of miR-155 and miR-146a compared to the NC group (P < 0.05). Moreover, the DPN group exhibited a significantly decreased expression level of miR-155 and miR-146a compared to the T2DM group (P < 0.01). Multivariate logistic regression analysis indicated that higher levels of miR-155 and miR-146a might serve as protective factors against DPN development. ROC curve analysis revealed that miR-155 (sensitivity 91.8%, specificity 37.3%, AUC 0.641,) and miR-146a (sensitivity 57.1%, specificity 84.3%, AUC 0.722) possess a strong ability to discriminate between T2DM and DPN. Their combined use further enhanced the diagnostic potential of DPN (sensitivity 83.7%, specificity 60.8%, AUC 0.775). A multi-index combination can improve DPN diagnostic efficiency.

Conclusion

The decreased expression of miR-155 and miR-146a in the peripheral blood of T2DM patients is closely related to the occurrence of DPN, highlighting their potential as valuable biomarkers for diagnosing and prognosticating DPN.

Aging and "Age-Related" Diseases - What Is the Relation?

The study explores the intricate relationship between aging and the development of noncommunicable diseases [NCDs], focusing on whether these diseases are inevitable consequences of aging or primarily driven by lifestyle factors. By examining epidemiological data, particularly from hunter-gatherer societies, the study highlights that many NCDs prevalent in modern populations are rare in these societies, suggesting a significant influence of lifestyle choices. It delves into the mechanisms through which poor diet, smoking, and other lifestyle factors contribute to systemic physiological imbalances, characterized by oxidative stress, insulin resistance and hyperinsulinemia, and dysregulation of the sympathetic nervous system, the renin-angiotensin-aldosterone system, and the immune system. The interplay between this pattern and individual factors such as genetic susceptibility, biological variability, epigenetic changes and the microbiome is proposed to play a crucial role in the development of a range of age-related NCDs. Modified biomolecules such as oxysterols and advanced glycation end products also contribute to their development. Specific diseases such as benign prostatic hyperplasia, Parkinson's disease, glaucoma and osteoarthritis are analyzed to illustrate these mechanisms. The study concludes that while aging contributes to the risk of NCDs, lifestyle factors play a crucial role, offering potential avenues for prevention and intervention through healthier living practices. One possible approach could be to try to restore the physiological balance, e.g. through dietary measures [e.g. Mediterranean diet, Okinawan diet or Paleolithic diet] in conjunction with [a combination of] pharmacological interventions and other lifestyle changes.

Curcumin-Rich Diet Mitigates Non-Alcoholic Fatty Liver Disease (NAFLD) by Attenuating Fat Accumulation and Improving Insulin Sensitivity in Aged Female Mice under Nutritional Stress

BACKGROUND

The high incidence of metabolic syndrome in the elderly poses a significant challenge to the healthcare system, emphasizing the need for interventions tailored to geriatric patients. Given the limited focus on females in previous studies, this research aimed to evaluate the effects of dietary curcumin on obesity and NAFLD outcomes in naturally aged (18-month-old) female mice.

METHODS

Female C57BL/6 mice aged 18 months were fed a normal chow diet (NCD) and a HFHSD, with or without curcumin (0.4% w/w), for an 8-week period. Parameters included food intake, body weight, insulin tolerance test (ITT), glucose tolerance test (GTT), percentage fat mass, hepatic triglyceride, and cholesterol levels, and a histological examination for NAFLD detection, qPCR, and immunoblotting analyses were performed.

RESULTS

The cumulative body weight gain after 8 weeks in the aged female mice supplemented with curcumin and fed an HFHSD was significantly lower (10.84 ± 1.09 g) compared to those fed a HFHSD alone (15.28 ± 1.26 g). Curcumin supplementation also resulted in reduced total body fat (HFHSD group 50.83 ± 1.71% vs. HFHSD+CUR 41.46 ± 3.21%), decreased epidydimal fat mass (HFHSD: 3.79 ± 0.29 g vs. HFHSD+CUR: 2.66 ± 0.30 g), and repaired adipogenic signaling in the white adipose tissue. Furthermore, curcumin lowered triglyceride and cholesterol deposition in the liver, preventing hepatic steatosis and improving hepatic insulin sensitivity.

CONCLUSIONS

Curcumin demonstrates the ability to ameliorate the deleterious effects of HFHSD in aged female mice by reducing body fat composition, modulating adipogenic signaling in the white adipose tissue, and improving insulin homeostasis and non-alcoholic fatty deposition in the liver.

Bioinformatics and systems biology approaches to identify potential common pathogeneses for sarcopenia and osteoarthritis

Sarcopenia, a geriatric syndrome characterized by progressive loss of muscle mass and strength, and osteoarthritis, a common degenerative joint disease, are both prevalent in elderly individuals. However, the relationship and molecular mechanisms underlying these two diseases have not been fully elucidated. In this study, we screened microarray data from the Gene Expression Omnibus to identify associations between sarcopenia and osteoarthritis. We employed multiple statistical methods and bioinformatics tools to analyze the shared DEGs (differentially expressed genes). Additionally, we identified 8 hub genes through functional enrichment analysis, protein-protein interaction analysis, transcription factor-gene interaction network analysis, and TF-miRNA coregulatory network analysis. We also discovered potential shared pathways between the two diseases, such as transcriptional misregulation in cancer, the FOXO signalling pathway, and endometrial cancer. Furthermore, based on common DEGs, we found that strophanthidin may be an optimal drug for treating sarcopenia and osteoarthritis, as indicated by the Drug Signatures database. Immune infiltration analysis was also performed on the sarcopenia and osteoarthritis datasets. Finally, receiver operating characteristic (ROC) curves were plotted to verify the reliability of our results. Our findings provide a theoretical foundation for future research on the potential common pathogenesis and molecular mechanisms of sarcopenia and osteoarthritis.

Sex difference in skeletal muscle mass in relation to metabolic dysfunction-associated steatotic liver disease: a propensity score matching study

BACKGROUND

While low muscle mass is considered a risk factor for metabolic dysfunction-associated steatotic liver disease (MASLD), whether the relationship is independent of fat mass remains unclear.

OBJECTIVES

This study aims to clarify the association between the sex-specific height-adjusted low skeletal muscle mass index (LSMI) and MASLD.

METHODS

Data from the 2008-2010 Korean National Health and Nutrition Examination Survey were analyzed. LSMI was defined using the 2019 Asian Working Group for Sarcopenia. The non-alcoholic fatty liver disease-liver fat score was used to assess MASLD. Gender-specific 1:1 propensity score matching (PSM) was performed to mitigate the confounding effects of anthropometric variables and lifestyles. Conditional logistic analysis was used on the dataset after PSM to estimate the odds ratio (OR) with a 95% confidence interval (CI).

RESULTS

After PSM, the prevalence of MASLD was significantly higher in men with LSMI than in those without LSMI (37.4% vs. 29.6%). No significant difference was observed in the prevalence of MASLD between groups after PSM in women (20.4% vs. 20.3%). Conditional logistic analysis revealed that the odds of having MASLD were significantly higher in men with LSMI compared to those without LSMI (OR = 1.38, 95% CI: 1.09-1.75), while no significant association was found in women with LSMI (OR = 1.10, 95% CI: 0.87-1.40).

CONCLUSION

Height-adjusted LSMI is an independent factor associated with MASLD in the condition of the same level of fat mass in men. Further prospective studies in diverse populations are needed to confirm our findings.

Biomarkers of frailty

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

Clinical outcomes of multidimensional association of type 2 diabetes mellitus, COVID-19 and sarcopenia: an algorithm and scoping systematic evaluation

BACKGROUND

The aim of this study was to provide a scoping and comprehensive review for the clinical outcomes from the cross-link of Type 2 diabetes mellitus (T2DM), COVID-19, and sarcopenia.

METHODS

By using PRISMA guidelines and searching through different databases that could provide findings of evidence on the association of T2DM, COVID-19, and sarcopenia.

RESULTS

Thirty-three studies reported a relationship between sarcopenia with T2DM, twenty-one studies reported the prognosis COVID-19 in patients with T2DM, ten studies reported the prognosis of COVID-19 in patients with sarcopenia, five studies discussed the outcomes of sarcopenia in patients with COVID-19, and one study reported sarcopenia outcomes in the presence of T2DM and COVID-19.

CONCLUSION

There is an obvious multidimensional relationship between T2DM, COVID-19 and sarcopenia which can cause prejudicial effects, poor prognosis, prolonged hospitalisation, lowered quality of life and a higher mortality rate during the current COVID-19 pandemic.

Renin angiotensin system-induced muscle wasting: putative mechanisms and implications for clinicians

Renin angiotensin system (RAS) alters various mechanisms related to muscle wasting. The RAS system consists of classical and non-classical pathways, which mostly function differently. Classical RAS pathway, operates through angiotensin II (AngII) and angiotensin type 1 receptors, is associated with muscle wasting and sarcopenia. On the other hand, the non-classical RAS pathway, which operates through angiotensin 1-7 and Mas receptor, is protective against sarcopenia. The classical RAS pathway might induce muscle wasting by variety of mechanisms. AngII reduces body weight, via reduction in food intake, possibly by decreasing hypothalamic expression of orexin and neuropeptide Y, insulin like growth factor-1 (IGF-1) and mammalian target of rapamycin (mTOR), signaling, AngII increases skeletal muscle proteolysis by forkhead box transcription factors (FOXO), caspase activation and muscle RING-finger protein-1 transcription. Furthermore, AngII infusion in skeletal muscle reduces phospho-Bad (Ser136) expression and induces apoptosis through increased cytochrome c release and DNA fragmentation. Additionally, Renin angiotensin system activation through AT1R and AngII stimulates tumor necrosis factor-α, and interleukin-6 which induces muscle wasting, Last but not least classical RAS pathway, induce oxidative stress, disturb mitochondrial energy metabolism, and muscle satellite cells which all lead to muscle wasting and decrease muscle regeneration. On the contrary, the non-classical RAS pathway functions oppositely to mitigate these mechanisms and protects against muscle wasting. In this review, we summarize the mechanisms of RAS-induced muscle wasting and putative implications for clinical practice. We also emphasize the areas of uncertainties and suggest potential research areas.

A first trimester prediction model and nomogram for gestational diabetes mellitus based on maternal clinical risk factors in a resource-poor setting

BACKGROUND

The implementation of universal screening for Gestational Diabetes Mellitus (GDM) is challenged by several factors key amongst which is limited resources, hence the continued reliance on risk factor-based screening. Effective identification of high-risk women early in pregnancy may enable preventive intervention. This study aimed at developing a GDM prediction model based on maternal clinical risk factors that are easily assessable in the first trimester of pregnancy in a population of Nigerian women.

METHODS

This was a multi-hospital prospective observational cohort study of 253 consecutively selected pregnant women from which maternal clinical data was collected at 8-12 weeks gestational age. Diagnosis of GDM was made via a one-step 75-gram Oral Glucose Tolerance Test (OGTT) at 24-28 weeks of gestation. A GDM prediction model and nomogram based on selected maternal clinical risk factors was developed using multiple logistic regression analysis, and its performance was assessed by Receiver Operator Curve (ROC) analysis. Data analysis was carried out using Statistical Package for Social Sciences (SPSS) version 25 and Python programming language (version 3.0).

RESULTS

Increasing maternal age, higher body mass index (BMI), a family history of diabetes mellitus in first-degree relative and previous history of foetal macrosomia were the major predictors of GDM. The model equation was: LogitP = 6.358 - 0.066 × Age - 0.075 × First trimester BMI - 1.879 × First-degree relative with diabetes mellitus - 0.522 × History of foetal macrosomia. It had an area under the receiver operator characteristic (ROC) curve (AUC) of 0.814 (95% CI: 0.751-0.877; p-value < 0.001), and at a predicted probability threshold of 0.745, it had a sensitivity of 79.2% and specificity of 74.5%.

CONCLUSION

This first trimester prediction model reliably identifies women at high risk for GDM development in the first trimester, and the nomogram enhances its practical applicability, contributing to improved clinical outcomes in the study population.

Sarcopenic obesity in older adults: a clinical overview

Sarcopenic obesity is characterized by a concurrent decline in muscle mass and function, along with increased adipose tissue. Sarcopenic obesity is a growing concern in older adults owing to significant health consequences, including implications for mortality, comorbidities and risk of developing geriatric syndromes. A 2022 consensus statement established a new definition and diagnostic criteria for sarcopenic obesity. The pathophysiology of this condition involves a complex interplay between muscle, adipose tissue, hormonal changes, inflammation, oxidative stress and lifestyle factors, among others. Sarcopenic obesity is treated with a range of management approaches, such as lifestyle interventions, exercise, nutrition and medical therapies. Emerging therapies that were developed for treating other conditions may be relevant to sarcopenic obesity, including novel pharmacological agents and personalized approaches such as precision medicine. In this Review, we synthesize the current knowledge of the clinical importance of sarcopenic obesity, its assessment and diagnosis, along with current and emerging management strategies.

Preventing obesity, insulin resistance and type 2 diabetes by targeting MT1-MMP

Obesity is one of the predominant risk factors for type 2 diabetes. Despite all the modern advances in medicine, an effective drug treatment for obesity without overt side effects has not yet been found. The discovery of growth and differentiation factor 15 (GDF15), an appetite-regulating hormone, created hopes for the treatment of obesity. However, an insufficient understanding of the physiological regulation of GDF15 has been a major obstacle to mitigating GDF15-centric treatment of obesity. Our recent studies revealed how a series of proteolytic events predominantly mediated by membrane-type 1 matrix metalloproteinase (MT1-MMP/MMP14), a key cell-surface metalloproteinase involved in extracellular remodeling, contribute to the pathogenesis of metabolic disorders, including obesity and diabetes. The MT1-MMP-mediated cleavage of the GDNF family receptor-α-like (GFRAL), a key neuronal receptor of GDF15, controls the satiety center in the hindbrain, thereby regulating non-homeostatic appetite and bodyweight changes. Furthermore, increased activation of MT1-MMP does not only lead to increased risk of obesity, but also causes age-associated insulin resistance by cleaving Insulin Receptor in major metabolic tissues. Importantly, inhibition of MT1-MMP effectively protects against obesity and diabetes, revealing the therapeutic potential of targeting MT1-MMP for the management of metabolic disorders.

Epicardial fat and insulin resistance in healthy older adults: a cross-sectional analysis

Insulin resistance (IR) and cardiovascular diseases (CVD) are relevant concerns in the elderly population; as the world's population ages, IR and CVD are two universal public health problems. While a link between IR a CVD has been established, the mediating mechanisms are uncertain and rigorous investigations are needed to fully elucidate them. The study aimed at assessing the relationship between epicardial fat (EF), an indicator of cardiovascular risk, and IR in Italian free-living elderly (n = 89). Baseline data from a previous cohort was used. Anthropometric measurements, EF, and IR-related variables, including the HOMA-IR index and other biochemical parameters were obtained. The correlation between EF and IR was explored. Further analysis was conducted to identify significant differences regarding IR variables among EF quartiles. EF correlated positively with glucose levels in females, males and the total population. The pairwise comparison among EF quartiles showed significant differences in glucose levels, HOMA-IR index, triglycerides, and total cholesterol levels. To our knowledge, this is the only study assessing the relationship between EF and IR in healthy elderly, while most of the studies have investigated EF and IR in diseased populations. Further research with a longitudinal approach should be conducted to design concrete conclusions about this relationship.

Mechanism of traditional Chinese medicine in elderly diabetes mellitus and a systematic review of its clinical application

Objective: Affected by aging, the elderly diabetes patients have many pathological characteristics different from the young people, including more complications, vascular aging, cognitive impairment, osteoporosis, and sarcopenia. This article will explore their pathogenesis and the mechanism of Traditional Chinese medicine (TCM) intervention, and use the method of systematic review to evaluate the clinical application of TCM in elderly diabetes. Method: Searching for randomized controlled trials (RCTs) published from January 2000 to November 2023 in the following databases: Web of Science, Pubmed, Embase, Cochrane Library, Sinomed, China National Knowledge Internet, Wanfang and VIP. They were evaluated by three subgroups of Traditional Chinese Prescription, Traditional Chinese patent medicines and Traditional Chinese medicine extracts for their common prescriptions, drugs, adverse reactions and the quality of them. Results and Conclusion: TCM has the advantages of multi-target and synergistic treatment in the treatment of elderly diabetes. However, current clinical researches have shortcomings including the inclusion of age criteria and diagnosis of subjects are unclear, imprecise research design, non-standard intervention measures, and its safety needs further exploration. In the future, the diagnosis of elderly people with diabetes needs to be further clarified. Traditional Chinese patent medicines included in the pharmacopoeia can be used to conduct more rigorous RCTs, and then gradually standardize the traditional Chinese medicine prescriptions and traditional Chinese medicine extracts, providing higher level evidence for the treatment of elderly diabetes with traditional Chinese medicine.

LPS-Induced Modifications in Macrophage Transcript and Secretion Profiles Are Linked to Muscle Wasting and Glucose Intolerance

Macrophages are versatile immune cells that play crucial roles in tissue repair, immune defense, and the regulation of immune responses. In the context of skeletal muscle, they are vital for maintaining muscle homeostasis but macrophage-induced chronic inflammation can lead to muscle dysfunction, resulting in skeletal muscle atrophy characterized by reduced muscle mass and impaired insulin regulation and glucose uptake. Although the involvement of macrophage-secreted factors in inflammation-induced muscle atrophy is well-established, the precise intracellular signaling pathways and secretion factors affecting skeletal muscle homeostasis require further investigation. This study aimed to explore the regulation of macrophage-secreted factors and their impact on muscle atrophy and glucose metabolism. By employing RNA sequencing (RNA-seq) and proteome array, we uncovered that factors secreted by lipopolysaccharide (LPS)-stimulated macrophages upregulated markers of muscle atrophy and pro-inflammatory cytokines, while concurrently reducing glucose uptake in muscle cells. The RNA-seq analysis identified alterations in gene expression patterns associated with immune system pathways and nutrient metabolism. The utilization of gene ontology (GO) analysis and proteome array with macrophage-conditioned media revealed the involvement of macrophage-secreted cytokines and chemokines associated with muscle atrophy. These findings offer valuable insights into the regulatory mechanisms of macrophage-secreted factors and their contributions to muscle-related diseases.

Skeletal Muscle Evaluation in Patients With Acromegaly

Context

Patients with acromegaly are characterized by chronic exposure to high growth hormone (GH) and insulin-like growth factor-1 levels, known for their anabolic effect on skeletal muscle. Therefore, an increased skeletal muscle mass could be hypothesized in these individuals. Herein, we have performed a systematic revision of published evidence regarding skeletal muscle mass, quality, and performance in patients with acromegaly.

Evidence Acquisition

A systematic review of the literature in the PubMed database up to September 1, 2023, was conducted with the following query: acromegaly AND ("muscle mass" OR "skeletal muscle"). We excluded studies that did not compare different disease states or used nonradiological methods for the skeletal muscle analyses, except for bioelectrical impedance analysis.

Evidence Synthesis

Fifteen studies met the inclusion criteria. A total of 360 patients were evaluated for skeletal muscle mass, 122 for muscle fatty atrophy, and 192 for muscle performance. No clear evidence of increased skeletal muscle mass in patients with active disease compared to control or healthy individuals emerged. As for skeletal muscle quality, we observed a trend toward higher fatty infiltration among patients with acromegaly compared to healthy participants. Likewise, patients with active disease showed consistently worse physical performance compared to control or healthy individuals.

Conclusion

Skeletal muscle in acromegaly has lower quality and performance compared to that of healthy individuals. The small number of published studies and multiple confounding factors (eg, use of different radiological techniques) contributed to mixed results, especially regarding skeletal muscle mass. Well-designed prospective studies are needed to investigate skeletal muscle mass in patients with acromegaly.

Changes in Cells Associated with Insulin Resistance

Insulin is a polypeptide hormone synthesized and secreted by pancreatic β-cells. It plays an important role as a metabolic hormone. Insulin influences the metabolism of glucose, regulating plasma glucose levels and stimulating glucose storage in organs such as the liver, muscles and adipose tissue. It is involved in fat metabolism, increasing the storage of triglycerides and decreasing lipolysis. Ketone body metabolism also depends on insulin action, as insulin reduces ketone body concentrations and influences protein metabolism. It increases nitrogen retention, facilitates the transport of amino acids into cells and increases the synthesis of proteins. Insulin also inhibits protein breakdown and is involved in cellular growth and proliferation. On the other hand, defects in the intracellular signaling pathways of insulin may cause several disturbances in human metabolism, resulting in several chronic diseases. Insulin resistance, also known as impaired insulin sensitivity, is due to the decreased reaction of insulin signaling for glucose levels, seen when glucose use in response to an adequate concentration of insulin is impaired. Insulin resistance may cause, for example, increased plasma insulin levels. That state, called hyperinsulinemia, impairs metabolic processes and is observed in patients with type 2 diabetes mellitus and obesity. Hyperinsulinemia may increase the risk of initiation, progression and metastasis of several cancers and may cause poor cancer outcomes. Insulin resistance is a health problem worldwide; therefore, mechanisms of insulin resistance, causes and types of insulin resistance and strategies against insulin resistance are described in this review. Attention is also paid to factors that are associated with the development of insulin resistance, the main and characteristic symptoms of particular syndromes, plus other aspects of severe insulin resistance. This review mainly focuses on the description and analysis of changes in cells due to insulin resistance.

The serum small non-coding RNA (SncRNA) landscape as a molecular biomarker of age associated muscle dysregulation and insulin resistance in older adults

Small noncoding RNAs (sncRNAs) are implicated in age-associated pathologies, including sarcopenia and insulin resistance (IR). As potential circulating biomarkers, most studies have focussed on microRNAs (miRNAs), one class of sncRNA. This study characterized the wider circulating sncRNA transcriptome of older individuals and associations with sarcopenia and IR. sncRNA expression including miRNAs, transfer RNAs (tRNAs), tRNA-associated fragments (tRFs), and piwi-interacting RNAs (piRNAs) was measured in serum from 21 healthy and 21 sarcopenic Hertfordshire Sarcopenia Study extension women matched for age (mean 78.9 years) and HOMA2-IR. Associations with age, sarcopenia and HOMA2-IR were examined and predicted gene targets and biological pathways characterized. Of the total sncRNA among healthy controls, piRNAs were most abundant (85.3%), followed by tRNAs (4.1%), miRNAs (2.7%), and tRFs (0.5%). Age was associated (FDR < 0.05) with 2 miRNAs, 58 tRNAs, and 14 tRFs, with chromatin organization, WNT signaling, and response to stress enriched among gene targets. Sarcopenia was nominally associated (p < .05) with 12 tRNAs, 3 tRFs, and 6 piRNAs, with target genes linked to cell proliferation and differentiation such as Notch Receptor 1 (NOTCH1), DISC1 scaffold protein (DISC1), and GLI family zinc finger-2 (GLI2). HOMA2-IR was nominally associated (p<0.05) with 6 miRNAs, 9 tRNAs, 1 tRF, and 19 piRNAs, linked with lysine degradation, circadian rhythm, and fatty acid biosynthesis pathways. These findings identify changes in circulating sncRNA expression in human serum associated with chronological age, sarcopenia, and IR. These may have clinical utility as circulating biomarkers of ageing and age-associated pathologies and provide novel targets for therapeutic intervention.

Antidiabetic Effect of Urolithin A in Cultured L6 Myotubes and Type 2 Diabetic Model KK-Ay/Ta Mice with Glucose Intolerance

Diabetes is caused by abnormal glucose metabolism, and muscle, the largest tissue in the human body, is largely involved. Urolithin A (UroA) is a major intestinal and microbial metabolite of ellagic acid and ellagitannins and is found in fruits such as strawberry and pomegranate. In this present study, we investigated the antidiabetic effects of UroA in L6 myotubes and in KK-Ay/Ta, a mouse model of type 2 diabetes (T2D). UroA treatment elevated the glucose uptake (GU) of L6 myotubes in the absence of insulin. This elevation in GU by UroA treatment was partially inhibited by the concurrent addition of LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K) which activates Akt (PKB: protein kinase B) or Compound C, an inhibitor of 5'-adenosine monophosphate-activated protein kinase (AMPK). Moreover, UroA was found to activate both pathways of Akt and AMPK, and then to promote translocation of glucose transporter 4 (GLUT4) from the cytosol to the plasma membrane in L6 myotubes. Based on these in vitro findings, an intraperitoneal glucose tolerance test (IPGTT) was performed after the oral administration of UroA for 3 weeks to KK-Ay/Ta mice with glucose intolerance. UroA was demonstrated to alleviate glucose intolerance. These results suggest that UroA is a biofactor with antihyperglycemic effects in the T2D state.

The effects of combined exercise training on glucose metabolism and inflammatory markers in sedentary adults: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to determine the magnitude of the effect of combined exercise training on glucose metabolism markers, adipokines, and inflammatory cytokines in non-diabetic sedentary adults. PubMed, Web of Science, Scopus, Cochrane Library electronic databases and reference lists of included studies were explored for randomized controlled trials (RCTs) that included physically inactive adults and provided combined training interventions (aerobic plus resistance exercise). Effects on fasting glucose and insulin, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), HbA1c, adiponectin, leptin, IL-6, TNF-α, and C-reactive protein (CRP) in exercise vs control groups were analyzed using random effects meta-analysis. The Cochrane Risk of Bias Tool for Randomized Trials 2.0 (RoB 2) was used to assess the risk of bias. A total of 24 RCTs were included in the quantitative analysis. Combined exercise training significantly decrease fasting glucose (standardized mean difference, SMD: - 0.474, 95% CI [- 0.829, - 0.120], p = 0.009, 35 study arms), fasting insulin (SMD: - 1.024, 95% CI [- 1.502, - 0.545], p < 0.001, 27 study arms), HOMA-IR (SMD: - 0.946, 95% CI [- 1.450, - 0.442], p < 0.001, 23 study arms), TNF-α (SMD: - 0.972, 95% CI [- 1.361, - 0.582], p < 0.001, 10 study arms), and CRP (SMD: - 0.507, 95% CI [- 0.818, - 0.196], p = 0.001, 14 study arms). No significant effects were observed for HbA1c, adiponectin, leptin, and IL-6 levels. Random effects meta-regression models by age, sex, and intervention length were not able to explain any of the variation in the effect size of HOMA-IR. Findings from this systematic review and meta-analysis suggest that combined exercise training improves some glucose metabolism markers and inflammatory parameters in sedentary adults without diabetes.

Beta-Hydroxybutyrate: A Supplemental Molecule for Various Diseases

β-hydroxybutyrate (BHB) is a ketone body that serves as an alternative energy source for various tissues, including the brain, heart, and skeletal muscle. As a metabolic intermediate and signaling molecule, BHB plays a crucial role in modulating cellular and physiological processes. Notably, BHB supplementation offers a novel and promising strategy to induce nutritional ketosis without the need for strict dietary adherence or causing nutritional deficiencies. This review article provides an overview of BHB metabolism and explores its applications in age-related diseases. This review conducted a comprehensive search of PubMed, ScienceDirect, and other relevant English-language articles. The main findings were synthesized, and discussed the challenges, limitations, and future directions of BHB supplementation. BHB supplementation holds potential benefits for various diseases and conditions, including neurodegenerative disorders, cardiovascular diseases, cancers, and inflammation. BHB acts through multiple mechanisms, including interactions with cell surface receptors, intracellular enzymes, transcription factors, signaling molecules, and epigenetic modifications. Despite its promise, BHB supplementation faces several challenges, such as determining the optimal dosage, ensuring long-term safety, identifying the most effective type and formulation, establishing biomarkers of response, and conducting cost-effectiveness analyses. BHB supplementation opens exciting avenues for research, including investigating molecular mechanisms, refining optimization strategies, exploring innovation opportunities, and assessing healthspan and lifespan benefits. BHB supplementation represents a new frontier in health research, offering a potential pathway to enhance well-being and extend lifespan.

Acetobacter and lactobacillus alleviate the symptom of insulin resistance by blocking the JNK-JAK/STAT pathway in Drosophila melanogaster

The dysregulation of intestinal microbiota is well-known to be one of the main causes of insulin resistance in both vertebrates and invertebrates. Specially, the acetobacter and lactobacillus have been identified as potentially capable of alleviating insulin resistance. However, the molecular mechanism underlying this effect requires further elucidation. In this study, we employed Drosophila melanogaster (fruit fly) as a model organism to delineate how intestinal microbiota disrupts the host intestinal signaling pathway, contributing to insulin resistance. Our findings demonstrate that a long-term high-sugar diet lead to a reduction in the general diversity of intestinal microbiota in flies, as well as a marked decrease in the abundances of acetobacter and lactobacillus. Furthermore, we observed that symptoms of insulin resistance were alleviated by feeding flies with acetobacter or lactobacillus, indicating that these microorganisms play an essential role in maintaining blood sugar homeostasis in flies. Conversely, when all intestinal microbiota was removed, flies show severe symptoms of insulin resistance, confirming that the critical role of intestinal microbiota in maintaining host blood sugar homeostasis. Our studies suggested that the intestinal but not fat body JNK pathway mediates the communication of intestinal microbiota and host insulin pathway. In flies, downregulation of JNK activity alleviates symptoms of insulin resistance by decreasing the activity of the JAK/STAT pathway. However, this offsets the therapeutic effects of supplying flies with acetobacter or lactobacillus, suggesting that the therapeutic function of these microorganisms is based on their interaction with JNK-JAK/STAT axis. Taken together, our study reveals that acetobacter and lactobacillus alleviate insulin resistance symptoms in a JNK-JAK/STAT pathway-dependent manner, indicating the therapeutic potential of probiotic supplementation and regulation of the activities of JNK-JAK/STAT pathway for diabetes control.

Overnutrition during Pregnancy and Lactation Induces Gender-Dependent Dysmetabolism in the Offspring Accompanied by Heightened Stress and Anxiety

Maternal obesity and gestational diabetes predispose the next generation to metabolic disturbances. Moreover, the lactation phase also stands as a critical phase for metabolic programming. Nevertheless, the precise mechanisms originating these changes remain unclear. Here, we investigate the consequences of a maternal lipid-rich diet during gestation and lactation and its impact on metabolism and behavior in the offspring. Two experimental groups of Wistar female rats were used: a control group (NC) that was fed a standard diet during the gestation and lactation periods and an overnutrition group that was fed a high-fat diet (HF, 60% lipid-rich) during the same phases. The offspring were analyzed at postnatal days 21 and 28 and at 2 months old (PD21, PD28, and PD60) for their metabolic profiles (weight, fasting glycemia insulin sensitivity, and glucose tolerance) and euthanized for brain collection to evaluate metabolism and inflammation in the hypothalamus, hippocampus, and prefrontal cortex using Western blot markers of synaptic dynamics. At 2 months old, behavioral tests for anxiety, stress, cognition, and food habits were conducted. We observed that the female offspring born from HF mothers exhibited increased weight gain and decreased glucose tolerance that attenuated with age. In the offspring males, weight gain increased at P21 and worsened with age, while glucose tolerance remained unchanged. The offspring of the HF mothers exhibited elevated levels of anxiety and stress during behavioral tests, displaying decreased predisposition for curiosity compared to the NC group. In addition, the offspring from mothers with HF showed increased food consumption and a lower tendency towards food-related aggression. We conclude that exposure to an HF diet during pregnancy and lactation induces dysmetabolism in the offspring and is accompanied by heightened stress and anxiety. There was sexual dimorphism in the metabolic traits but not behavioral phenotypes.

What matters in aging is signaling for responsiveness

Biological responsiveness refers to the capacity of living organisms to adapt to changes in both their internal and external environments through physiological and behavioral mechanisms. One of the prominent aspects of aging is the decline in this responsiveness, which can lead to a deterioration in the processes required for maintenance, survival, and growth. The vital link between physiological responsiveness and the essential life processes lies within the signaling systems. To devise effective strategies for controlling the aging process, a comprehensive reevaluation of this connecting loop is imperative. This review aims to explore the impact of aging on signaling systems responsible for responsiveness and introduce a novel perspective on intervening in the aging process by restoring the compromised responsiveness. These innovative mechanistic approaches for modulating altered responsiveness hold the potential to illuminate the development of action plans aimed at controlling the aging process and treating age-related disorders.

The yield of early-pregnancy homeostasis of model assessment -insulin resistance (HOMA-IR) for predicting gestational diabetes mellitus in different body mass index and age groups

BACKGROUND

Early prediction of gestational diabetes mellitus(GDM) can be beneficial for lifestyle modifications to prevent GDM. The aim of this study was to investigate the predictive values of Homeostasis of Model Assessment -Insulin Resistance (HOMA-IR) in early pregnancy to predict GDM development in different body mass index (BMI) and age risk categories.

MATERIALS AND METHODS

This study is part of the Qazvin Maternal and Neonatal Metabolic Study (QMNMS) in Iran (2018-2021). In this prospective longitudinal study, pregnant women with a gestational age ≤ 14 weeks were enrolled in the study using convenience sampling method and were followed up until delivery to investigate risk factors for maternal and neonatal complications. Data collection was done using questionnaires. Serum sampling was done at a gestational age ≤ 14 weeks and sera were frozen until the end of study. GDM was diagnosed at 24-28 weeks of pregnancy using 75gr oral glucose tolerance test. Fasting blood glucose and insulin were measured in sera taken during early pregnancy in 583 participants. The Mann-Whitney U test, independent t-test, and Chi-square test were used for comparing variables between groups. The logistic regression analysis was used to examine the independent association of HOMA-IR with GDM development and receiver operating characteristic analysis was used for finding the best cut-off of HOMA-IR for predicting GDM.

RESULTS

GDM was developed in 90 (15.4%) of the participants. The third HOMA-IR tertile was independently associated with 3.2 times higher GDM occurrence (95% CI:1.6-6.2, P = 0.001). Despite the high prevalence of GDM in advanced maternal age (GDM rate = 28.4%), HOMA-IR had no association with GDM occurrence in this high-risk group. In both normal BMI and overweight/obese groups, HOMA-IR was a moderate predictor of GDM development (AUC = 0.638, P = 0.005 and AUC = 0.622, P = 0.008, respectively). However, the best cut-off for predicting GDM was 2.06 (sensitivity 67.5%, specificity 61.1%) in normal BMI and 3.13 (sensitivity 64.6%, specificity61.8%) in overweight/obese BMI.

CONCLUSION

The present study revealed the necessity of considering the BMI and age risk groups when using the HOMA-IR index to predict GDM. Using lower cut-offs is more accurate for women with a normal BMI. In the advanced maternal age, there is no yield of HOMA-IR for predicting GDM.

Role of Fish Oil in Preventing Paternal Obesity and Improving Offspring Skeletal Muscle Health

This study investigates the effects of fish oil supplementation during the periconceptional period in male mice. Specifically, it examines the impact of fish oil on intergenerational health, as determined by skeletal muscle markers. To mimic paternal obesity, thirty mice were separated into three groups with distinct dietary regimes for 10 weeks: a high-fat diet (HF), a high-fat diet supplemented with fish oil (FO), and a low-fat diet (LF). Then, these mice mated with control female mice. Dams and offspring consumed a chow diet during gestation and lactation, and the offspring continued on a chow diet. To study short-term (8 weeks) and long-term (16 weeks) effects of FO, skeletal muscle was isolated at the time of sacrifice, and gene analyses were performed. Results suggest that offspring born to FO-supplemented sires exhibited a significant, short-term upregulation of genes associated with insulin signaling, fatty acid oxidation, and skeletal muscle growth with significant downregulation of genes involved in fatty acid synthesis at 8 weeks. Prominent differences in the above markers were observed at 8 weeks compared to 16 weeks. These findings suggest the potential benefits of FO supplementation for fathers during the periconceptional period in reducing the health risks of offspring due to paternal obesity.

A Korean Nationwide Cross-Sectional Study Investigating Risk Factors, Prevalence, and Characteristics of Sarcopenia in Men in Early Old Age

The present study investigated the risk factors, prevalence, and characteristics of sarcopenia among men aged 50-64 years. A total of 2868 participants were enrolled in this study. Of these, 328 individuals were classified into a sarcopenia group; the remaining 2540 were assigned to a control group. This study examined several variables, including skeletal muscle mass index, age, height, weight, body mass index, waist circumference, systolic and diastolic blood pressure, fasting glucose, triglyceride and total cholesterol levels, alcohol consumption, and tobacco use. It employed a stratified, clustered, and multistage probability sampling design. Complex sampling was used for the data analysis. The prevalence of sarcopenia was 10.25% (95% CI: 8.98-11.69). All anthropometric measures, including height, weight, BMI, and waist circumference, were significantly different between the two groups (p < 0.05). In terms of blood pressure, only systolic blood pressure (SBP) was significant (p < 0.05), and fasting glucose and triglyceride levels were risk factors for sarcopenia (p < 0.05). Tobacco use differed significantly between the two groups (p < 0.05). This study reported the specific prevalence of sarcopenia and identified its risk factors among men in early old age.

NAD+: An Old but Promising Therapeutic Agent for Skeletal Muscle Ageing

More than a century after the discovery of nicotinamide adenine dinucleotide (NAD+), our understanding of the molecule's role in the biology of ageing continues to evolve. As a coenzyme or substrate for many enzymes, NAD+ governs a wide range of biological processes, including energy metabolism, genomic stability, signal transduction, and cell fate. NAD+ deficiency has been recognised as a bona fide hallmark of tissue degeneration, and restoring NAD+ homeostasis helps to rejuvenate multiple mechanisms associated with tissue ageing. The progressive loss of skeletal muscle homeostasis with age is directly associated with high morbidity, disability and mortality. The aetiology of skeletal muscle ageing is complex, involving mitochondrial dysfunction, senescence and stem cell depletion, autophagy defects, chronic cellular stress, intracellular ion overload, immune cell dysfunction, circadian clock disruption, microcirculation disorders, persistent denervation, and gut microbiota dysbiosis. This review focuses on the therapeutic potential of NAD+ restoration to alleviate the above pathological factors and discusses the effects of in vivo administration of different NAD+ boosting strategies on skeletal muscle homeostasis, aiming to provide a reference for combating skeletal muscle ageing.

DNA methylation of insulin signaling pathways is associated with HOMA2-IR in primary myoblasts from older adults

BACKGROUND

While ageing is associated with increased insulin resistance (IR), the molecular mechanisms underlying increased IR in the muscle, the primary organ for glucose clearance, have yet to be elucidated in older individuals. As epigenetic processes are suggested to contribute to the development of ageing-associated diseases, we investigated whether differential DNA methylation was associated with IR in human primary muscle stem cells (myoblasts) from community-dwelling older individuals.

METHODS

We measured DNA methylation (Infinium HumanMethylationEPIC BeadChip) in myoblast cultures from vastus lateralis biopsies (119 males/females, mean age 78.24 years) from the Hertfordshire Sarcopenia Study extension (HSSe) and examined differentially methylated cytosine phosphate guanine (CpG) sites (dmCpG), regions (DMRs) and gene pathways associated with HOMA2-IR, an index for the assessment of insulin resistance, and levels of glycated hemoglobin HbA1c.

RESULTS

Thirty-eight dmCpGs (false discovery rate (FDR) < 0.05) were associated with HOMA2-IR, with dmCpGs enriched in genes linked with JNK, AMPK and insulin signaling. The methylation signal associated with HOMA2-IR was attenuated after the addition of either BMI (6 dmCpGs), appendicular lean mass index (ALMi) (7 dmCpGs), grip strength (15 dmCpGs) or gait speed (23 dmCpGs) as covariates in the model. There were 8 DMRs (Stouffer < 0.05) associated with HOMA2-IR, including DMRs within T-box transcription factor (TBX1) and nuclear receptor subfamily-2 group F member-2 (NR2F2); the DMRs within TBX1 and NR2F2 remained associated with HOMA2-IR after adjustment for BMI, ALMi, grip strength or gait speed. Forty-nine dmCpGs and 21 DMRs were associated with HbA1c, with cg13451048, located within exoribonuclease family member 3 (ERI3) associated with both HOMA2-IR and HbA1c. HOMA2-IR and HbA1c were not associated with accelerated epigenetic ageing.

CONCLUSIONS

These findings suggest that insulin resistance is associated with differential DNA methylation in human primary myoblasts with both muscle mass and body composition making a significant contribution to the methylation changes associated with IR.

Hispidin-enriched Sanghuangporus sanghuang mycelia SS-MN4 ameliorate disuse atrophy while improving muscle endurance

BACKGROUND

Disuse atrophy is a frequent cause of muscle atrophy, which can occur in individuals of any age who have been inactive for a prolonged period or immobilization. Additionally, acute diseases such as COVID-19 can cause frequent sequelae and exacerbate muscle wasting, leading to additional fatigue symptoms. It is necessary to investigate potent functional nutrients for muscle reinforcement in both disuse atrophy and fatigue to ensure better physical performance.

METHODS

The effects of Sanghuangporus sanghuang SS-MN4 mycelia were tested on two groups of 6-week-old male mice-one with disuse atrophy and the other with fatigue. The disuse atrophy group was divided into three sub-groups: a control group, a group that underwent hind limb casting for 7 days and then recovered for 7 days and a group that was administered with SS-MN4 orally for 14 days, underwent hind limb casting for 7 days and then recovered for 7 days. The fatigue group was divided into two sub-groups: a control group that received no SS-MN4 intervention and an experimental group that was administered with SS-MN4 orally for 39 days and tested for exhaustive swimming and running on Day 31 and Day 33, respectively. RNA sequencing (RNA-seq) and western blot analysis were conducted on C2C12 cell lines to identify the therapeutic effects of SS-MN4 treatment.

RESULTS

In a disuse atrophy model induced by hind limb casting, supplementing with 250 mg/kg of SS-MN4 for 14 days led to 111.2% gastrocnemius muscle mass recovery and an 89.1% improvement in motor function on a treadmill (P < 0.05). In a fatigue animal model, equivalent SS-MN4 dosage improved swimming (178.7%) and running (162.4%) activities (P < 0.05) and reduced blood urea nitrogen levels by 18% (P < 0.05). SS-MN4 treatment also increased liver and muscle glycogen storage by 34.36% and 55.6%, respectively, suggesting a higher energy reserve for exercise. RNA-seq and western blot studies from the C2C12 myotube showed that SS-MN4 extract upregulates Myh4 and helps sustain myotube integrity against dexamethasone damage.

CONCLUSIONS

Supplementation of SS-MN4 (250-mg/kg body weight) with hispidin as active compound revealed a potential usage as a muscle nutritional supplement enhancing muscle recovery, fast-twitch fibre regrowth and fatigue resistance.

Sedentary Behavior Impacts on the Epigenome and Transcriptome: Lessons from Muscle Inactivation in Drosophila Larvae

The biological mechanisms linking sedentary lifestyles and metabolic derangements are incompletely understood. In this study, temporal muscle inactivation in Drosophila larvae carrying a temperature-sensitive mutation in the shibire (shi1) gene was induced to mimic sedentary behavior during early life and study its transcriptional outcome. Our findings indicated a significant change in the epigenetic profile, as well as the genomic profile, of RNA Pol II binding in the inactive muscles relative to control, within a relatively short time period. Whole-genome analysis of RNA-Pol II binding to DNA by muscle-specific targeted DamID (TaDa) protocol revealed that muscle inactivity altered Pol II binding in 121 out of 2010 genes (6%), with a three-fold enrichment of genes coding for lncRNAs. The suppressed protein-coding genes included genes associated with longevity, DNA repair, muscle function, and ubiquitin-dependent proteostasis. Moreover, inducing muscle inactivation exerted a multi-level impact upon chromatin modifications, triggering an altered epigenetic balance of active versus inactive marks. The downregulated genes in the inactive muscles included genes essential for muscle structure and function, carbohydrate metabolism, longevity, and others. Given the multiple analogous genes in Drosophila for many human genes, extrapolating our findings to humans may hold promise for establishing a molecular link between sedentary behavior and metabolic diseases.

MicroRNA-155 mediates endogenous angiotensin II type 1 receptor regulation: implications for innovative type 2 diabetes mellitus management

Type 2 diabetes mellitus (T2DM) is a lifelong condition and a threat to human health. Thorough understanding of its pathogenesis is acutely needed in order to devise innovative, preventative, and potentially curative pharmacological interventions. MicroRNAs (miRNA), are small, non-coding, one-stranded RNA molecules, that can target and silence around 60% of all human genes through translational repression. MiR-155 is an ancient, evolutionarily well-conserved miRNA, with distinct expression profiles and multifunctionality, and a target repertoire of over 241 genes involved in numerous physiological and pathological processes including hematopoietic lineage differentiation, immunity, inflammation, viral infections, cancer, cardiovascular conditions, and particularly diabetes mellitus. MiR-155 Levels are progressively reduced in aging, obesity, sarcopenia, and T2DM. Thus, the loss of coordinated repression of multiple miR-155 targets acting as negative regulators, such as C/EBPβ, HDAC4, and SOCS1 impacts insulin signaling, deteriorating glucose homeostasis, and causing insulin resistance (IR). Moreover, deranged regulation of the renin angiotensin aldo-sterone system (RAAS) through loss of Angiotensin II Type 1 receptor downregulation, and negated repression of ETS-1, results in unopposed detrimental Angiotensin II effects, further promoting IR. Finally, loss of BACH1 and SOCS1 repression abolishes cytoprotective, anti-oxidant, anti-apoptotic, and anti-inflammatory cellular pathways, and promotes β-cell loss. In contrast to RAAS inhibitor treatments that further decrease already reduced miR-155 Levels, strategies to increase an ailing miR-155 production in T2DM, e.g., the use of metformin, mineralocorticoid receptor blockers (spironolactone, eplerenone, finerenone), and verapamil, alone or in various combinations, represent current treatment options. In the future, direct tissue delivery of miRNA analogs is likely.