The Contribution of Advanced Glycation End product (AGE) accumulation to the decline in motor function

Advanced Glycation End Products and Mobility Decline: A Novel Perspective on Aging

Background/Objectives: Advanced Glycation End Products (AGEs) are high-molecular-weight compounds formed through non-enzymatic reactions between sugars and proteins, lipids, or nucleic acids. This study aimed to comprehensively analyze the association between the accumulation of AGEs and lower-limb muscle strength, gait speed, and balance abilities related to mobility in elderly individuals. Methods: This cross-sectional correlational study included 552 community-dwelling older adults. AGE accumulation was assessed using skin autofluorescence (SAF) measured using an AGE reader. Mobility decline factors were evaluated using the sit-to-stand (STS), gait speed (4 m walk tests), single-leg stance (SLS), and Timed Up and Go (TUG) tests. Results: A comparison of the physical function across the quartile groups revealed that the group with the highest SAF values, Q4, exhibited a general decline in STS, gait speed, SLS, and TUG performance when compared with the other groups (p < 0.001). Spearman's correlation analysis revealed that the SAF-AGEs demonstrated significant negative correlations with STS (r = -0.211, p < 0.001), gait speed (r = -0.243, p < 0.001) and SLS (r = -0.201, p < 0.001). Additionally, TUG showed a significant positive correlation (r = 0.239, p < 0.001). In the logistic regression analysis, compared with the Q1 group, the Q4 group had significantly higher odds of low STS performance (odds ratio (OR) = 2.43, p = 0.006), slow gait speed (OR = 2.28, p = 0.002), low SLS performance (OR = 2.52, p = 0.001), and slow TUG (OR = 2.00, p = 0.035). The optimal cutoff value of the SAF for mobility decline was 3.15 (area under the curve 0.694; 95% confidence interval: 0.618-0.771). Conclusions: This study has demonstrated that higher SAF values were associated with decreased lower-limb strength, gait speed, and balance, thereby suggesting that SAF may be a useful screening tool for predicting mobility decline in older adults.

Effects of different types of Tai Chi intervention on motor function in older adults: a systematic review

BACKGROUND

Tai Chi (TC) is widely acknowledged for its positive impact on improving motor function in older adults. Nevertheless, limited research has directly compared the effects of different TC styles on older adults with functional impairments.

OBJECTIVE

This study aimed to assess the impact of different TC styles on motor function in older adults with functional impairments.

METHOD

We searched five databases-PubMed, Scopus, Chinese National Knowledge Infrastructure (CNKI), Web of Science, and Wiley Online Library-including studies published up to September 2024. The selection of literature adhered to PRISMA guidelines, with quality assessment independently carried out by two researchers.

RESULTS

Fourteen studies met the inclusion criteria for this review. The analysis revealed that TC interventions for functionally impaired older adults primarily employed Yang-style, Sun-style, Chen-style, and simplified-style TC. The populations studied included individuals with mild cognitive impairment (MCI), nonspecific low back pain (NS-LBP), preclinical disabilities, chronic diseases, poor balance, osteoarthritis (OA), Parkinson's disease (PD), sarcopenia, and those at risk of falls. The findings indicated that motor function in functionally impaired older adults were closely linked to balance, gait, mobility, strength, and fall rates. Among the various TC styles, Yang-style was the most frequently utilised intervention.

CONCLUSION

This review examined four types of TC interventions and found strong evidence supporting the effectiveness of Yang-style TC in improving motor function in older adults with functional impairments. Additionally, five assessment methods-Single-Leg Stance (SL), Six-Minute Walk Test (6MWT), Timed Up and Go Test (TUGT), Chair Stand Test (CST), and Fall Efficacy Scale (FES)-were identified as suitable for evaluating this population. Based on the findings, it is recommended that individuals with functional impairments engage in Yang-style 24-movement TC, with an intervention duration of 12 weeks, practicing two to five times a week for 60 min each session.

Advanced glycation end products consumption and the decline of functional capacity in patients with Parkinson's disease: Cross-sectional study

INTRODUCTION

Advanced Glycation End-Products (AGEs) are a diverse group of highly reactive molecules that play a vital role in the development of neurodegenerative disorders, such as Parkinson's Disease (PD), leading to a decline in functional and cognitive capacity. The objective of this study was to assess the intake and quantification of AGEs in individuals with PD and to correlate them with their functional and cognitive abilities.

METHODS

This was a cross-sectional study involving 20 PD patients and 20 non-PD individuals as the Control group (C). The autofluorescence reader was used to evaluate skin AGEs, while food recall was used to quantify AGEs consumed for three different days. The Montreal Cognitive Assessment, Short Physical Performance Battery, and handgrip tests were used. PD patients demonstrated greater impairment in functional capacity compared to the control group.

RESULTS

Dominant Handgrip (p = 0.02) and motor performance, in the sit and stand test (p = 0.01) and Short Physical Performance Battery (SPPB) (p = 0.01) were inferior in PD patients than the control group. Although PD patients tended to consume less AGEs than the control group, AGE intake was negatively correlated with handgrip strength in individuals with PD (r = -0.59; p < 0.05).

CONCLUSION

PD patients had lower strength and functional capacity, suggesting that the effects of AGEs might be exacerbated during chronic diseases like Parkinson's.

Advanced glycation end products in skeletal muscle health and sarcopenia: A systematic review of observational studies

BACKGROUND

Advanced glycation end products (AGEs) and AGEs receptor (RAGE) may play a role in sarcopenia. This systematic review evaluated the associations between AGEs measured in tissues (skin) by autofluorescence (SAF) and/or circulation (blood, urine) and muscle health outcomes (strength, mass, function) and sarcopenia in observational studies.

METHODS

MEDLINE, Embase, Scopus and Web of Science were searched for studies reporting associations between AGEs and muscle-related outcomes in community-dwelling adults aged ≥ 30 years (until March 2022).

RESULTS

Fourteen cross-sectional and one prospective study were included in the narrative summary. SAF was negatively associated with muscle strength, mass, and physical functioning in adults aged ≥ 30 years (four studies), and muscle mass (three studies), strength, and sarcopenia (one study) in adults aged ≥ 65 years. Circulating AGEs were negatively associated with muscle strength and physical functioning (four studies) and predicted the risk of walking disability (one prospective study), and sarcopenia (one study) in older adults. The role of RAGE in muscle health was inconclusive.

CONCLUSIONS

SAF and circulating AGEs were negatively associated with muscle-related outcomes in adults aged ≥ 30 years in cross-sectional studies. This finding should be confirmed in well-designed prospective studies investigating sarcopenia, as AGEs represent a potentially modifiable target for intervention.

Influenza infection is not associated with phenotypical frailty in older patients, a prospective cohort study

Background and Aims

Influenza is a challenging infectious illness for older adults. It is not completely clear whether influenza is associated with frailty or functional decline. We sought to determine the association between incident influenza infection and frailty and prefrailty in community patients over 50 years of age. We also investigated the association between influenza vaccination and frailty and prefrailty as a secondary aim.

Methods

This was a prospective community cohort study from October 2019 to November 2020 in participants over 50 years. The primary outcome was the development of frailty as defined by three of five frailty criteria (slow gait speed, low grip strength, 5% weight loss, low energy, and low physical functioning). The primary predictor was a positive polymerase chain reaction (PCR) for influenza infection. Influenza vaccination was based on electronic health record reviewing 1 year before enrollment. We reported the relationship between influenza and frailty by calculating odds ratios (OR) with 95% confidence intervals (CI) after adjustment for age, sex, socioeconomic status, Charlson Comorbidity Index (CCI), influenza vaccine, and previous self-rated frailty from multinomial logistic regression model comparing frail and prefrail to nonfrail subjects.

Results

In 1135 participants, the median age was 67 years (interquartile range  60-74), with 41% men. Eighty-one participants had PCR-confirmed influenza (7.1%). Frailty was not associated with influenza, with an OR of 0.50 (95% CI 0.17-1.43) for frail participants compared to nonfrail participants. Influenza vaccination is associated with frailty, with an OR of 1.69 (95% CI 1.09-2.63) for frail compared to nonfrail. Frailty was associated with a higher CCI with an OR of 1.52 (95% CI 1.31-1.76).

Conclusion

We did not find a relationship between influenza infection and frailty. We found higher vaccination rates in participants with frailty compared to nonfrail participants While influenza was not associated with frailty, future work may involve longer follow-up.

Effect of Cirsium japonicum Flower Extract on Skin Aging Induced by Glycation

Advanced glycation end products (AGEs) have recently been increasingly discussed as one factor of skin aging. In this study, we investigated the effects of Cirsium japonicum flower (CFE) extract on glycation in relation to skin aging and skin elasticity. Moreover, we learned the main active constituent of CFE that has effects against glycation. To demonstrate the effects of CFE on glycation, we carried out an in vitro glycation study, 3-dimensional culture, and clinical study. As a result, CFE inhibited formation of AGEs in both bovine serum albumin (BSA)/glucose glycation system and aldehyde-derived glycation system. Moreover, CFE reduced Nε-(carboxymethyl), lysine (CML), and carbonylated proteins that increased by glycation. Furthermore, CFE broke crosslinks of collagen–AGEs and inhibited the increase of matrix metalloproteinase-1 (MMP-1) gene expression by AGEs. In the 3D culture condition, CFE restored the reduction of collagen gel contraction by glycation. Moreover, apigenin was detected as the main active constituent in CFE that has anti-glycation effects. In the clinical study, we confirmed that CFE has effects on skin wrinkles and skin elasticity. Our findings suggest that CFE can be used as a cosmetic or cosmeceutical ingredient for improving skin elasticity and wrinkles. Regulation of AGEs can be an interesting target for anti-aging.

Association Between the Accumulation of Pentosidine at the Sciatic Nerve and Cutaneous Hindpaw Hypersensitivity in a Rat Ovariectomy Model

Introduction

Advanced glycation end-products (AGEs) have the potential to serve as biomarkers of aging and metabolic diseases; however, how their expression relates to clinical symptoms is not well defined. In this study, we sought to determine whether the accumulation of pentosidine, one type of AGE, at the peripheral nerve is associated with cutaneous pain or hypersensitivity caused by ovariectomy (OVX).

Methods

We assigned 12-week-old female Sprague Dawley rats into either the OVX group (n = 6) or the sham group (n = 6). Cutaneous hindpaw sensitivity to mechanical stimuli was measured with von Frey filaments, using Chaplan’s adapted method, and the 50% withdrawal threshold was calculated. Then, the accumulation of pentosidine, which represents AGEs, was measured in sciatic nerve fibers after staining with an anti-pentosidine antibody.

Results

OVX rats showed significantly increased plantar hypersensitivity to mechanical stimuli compared to sham rats 8 weeks after OVX (P = 0.017). Pentosidine-positive sciatic nerves were detected at a higher rate in OVX rats than in sham rats (P = 0.035). The pentosidine positivity rate in sciatic nerve fibers showed a negative correlation with withdrawal threshold (P < 0.001).

Conclusions

This study showed that higher levels of pentosidine in sciatic nerve fibers are associated with higher plantar hypersensitivity. Accumulation of pentosidine at the sciatic nerve, caused by OVX, may result in cutaneous hindpaw hypersensitivity.

Anti-glycation activities of methyl gallate in vitro and in human explants

BACKGROUND

The build-up of advanced glycation end products (AGEs) is one of important factor of skin aging. Natural compounds with anti-glycation activities might have great anti-aging potential.

AIMS

The objective of this study was to evaluate an anti-glycation effects of methyl gallate as a potent ingredient for anti-aging.

METHODS

We first evaluated the AGEs inhibitory ability of methyl gallate in BSA/glucose system. Levels of Nε-CML and carbonyl contents were also measured in BSA/glucose system. To further investigate if methyl gallate could prevent glycation in full-thickness human skin explants. Glycation action was determined by the observation of the general morphology of dermis and epidermis structures and FBN-1 and of CML immunostaining. In an in-vivo study, primary irritation test was also performed to ensure the safety of methyl gallate for human skin.

RESULTS

It is known that methyl gallate can suppress glycation reaction between BSA and glucose. Methyl gallate also has a remarkable potential to reduce the oxidation of proteins. Furthermore, the anti-glycation activity of methyl gallate has been confirmed in a human skin ex-vivo model. Methyl gallate decreased the expression of CML but stimulated the expression of FBN-1 compared with MGO treatment. In an in-vivo study, methyl gallate (0.1%) did not cause any skin irritation, suggesting that methyl gallate could be used as an active ingredient in cosmetics.

CONCLUSION

Our results showed that methyl gallate could protect against glucose-mediated glycation in vitro. Furthermore, methyl gallate significantly prevented glycation in living human skin explants. Due to these beneficial effects, methyl gallate can be used to prevent or manage AGE-mediated skin aging.

AGEs accumulation is related to muscle degeneration and vascular calcification in peritoneal dialysis patients

BACKGROUND

Patients with chronic kidney disease (CKD) are affected by dynapenia, sarcopenia, and vascular calcification. Advanced glycation end products (AGEs) may accumulate in peritoneal dialysis (PD) patients and favor sarcopenia via changes in collagen cross-linking, muscle protein breakdown, and the calcification of arterial smooth muscle cells via p38-MAPK activation. The aim of this study is to explore the relationships between AGEs, muscle degeneration, and coronary artery calcification.

METHODS

This was a clinical observational study in patients with CKD undergoing PD, in which serum and skin AGEs (AGEs-sAF), cumulative glucose load, muscle strength and functional tests, muscle ultrasounds with elastography, coronary artery calcium (CAC) quantification, and muscle density by multislice computed tomography were measured.

RESULTS

27 patients aged 48±16 years, dialysis vintage of 27±17 months, had AGEs-sAF levels of 3.09±0.65 AU (elevated in 13 [87%] patients), grip strength levels of 26.2±9.2 kg (11 [42%] patients with dynapenia), gait speed of 1.04±0.3 m/s (abnormal in 14 [58%] patients) and "timed-up-and-go test" (TUG) of 10.5±2.2s (abnormal in 7 [26%] patients). Correlations between AGEs-sAF levels and femoral rectus elastography (R=-0.74; p=0.02), anterior-tibialis elastography (R= -0.68; p=0.04) and CAC (R=0.64; p=0.04) were detected. Cumulative glucose load correlated with femoral rectal elastography (R=-0.6; p=0.02), and serum glycated hemoglobin concentrations correlated with psoas muscle density (R= -0.58; p=0.04) and CAC correlated with psoas muscle density (R=0.57; p=0.01) and lumbar square muscle density (R=-0.63; p=0.005).

CONCLUSIONS

The study revealed associations between AGEs accumulation and lower muscle stiffness/density. Associations that linked muscle degeneration parameters with vascular calcification were observed.

Application of ultrasound for muscle assessment in sarcopenia: 2020 SARCUS update

PURPOSE

In 2018, the SARCUS working group published a first article on the standardization of the use of ultrasound to assess muscle. Recommendations were made for patient positioning, system settings and components to be measured. Also, shortcomings in knowledge were mentioned. An important issue that still required standardization was the definition of anatomical landmarks for many muscles.

METHODS

A systematic search was performed in Medline, SCOPUS and Web of Sciences looking for all articles describing the use of ultrasound in the assessment of muscle not described in the first recommendations, published from 01/01/2018 until 31/01/2020. All relevant terms used for older people, ultrasound and muscles were used.

RESULTS

For 39 muscles, different approaches for ultrasound assessment were found that likely impact the values measured. Standardized anatomical landmarks and measuring points were proposed for all muscles/muscle groups. Besides the five already known muscle parameters (muscle thickness, cross-section area, pennation angle, fascicle length and echo-intensity), four new parameters are discussed (muscle volume, stiffness, contraction potential and microcirculation). The former SARCUS article recommendations are updated with this new information that includes new muscle groups.

CONCLUSIONS

The emerging field of ultrasound assessment of muscle mass only highlights the need for a standardization of measurement technique. In this article, guidelines are updated and broadened to provide standardization instructions for a large number of muscles.

Percutaneously-quantified advanced glycation end-products (AGEs) accumulation associates with low back pain and lower extremity symptoms in middle-aged low back pain patients

Advanced glycation end-products (AGEs) have been reported as a possible biomarker of ageing and metabolic diseases; however, its role in the clinical progression of these diseases remains unclear. We aimed to evaluate how AGEs are associated with clinical symptoms and comorbidities in lower back pain (LBP) patients. This prospective cohort study enrolled 636 LBP patients. They were subjected to quantified AGE (qAGE) analysis using skin autofluorescence, and their clinical symptoms and comorbidities, such as diabetes, renal failure with haemodialysis treatment, and osteoporosis, were measured. LBP, lower extremity pain, and numbness were evaluated using a visual analogue scale (VAS). The measured qAGE was significantly higher in subjects with any comorbidity. Age also showed a strong positive correlation with qAGE. qAGE and VAS for leg numbness were positively correlated. Furthermore, in LBP patients under 50-years-old, qAGE was positively correlated with VAS for LBP, lower extremity pain, and numbness. In conclusion, qAGE, as measured by skin autofluorescence measurement, was significantly higher in LBP patients with diabetes and dialysis, as well as in osteoporosis patients. Furthermore, qAGE showed potential as a biomarker for LBP, lower extremity pain, and numbness in patients under 50-years-old. If accumulated AGEs are identified at a young age, researchers should be vigilant for the development of osteoporosis and LBP-related clinical symptoms later in life.

The potential role of dietary advanced glycation endproducts in the development of chronic non-infectious diseases: a narrative review

Increasing clinical and experimental evidence accumulated during the past few decades supports an important role for dietary advanced glycation endproducts (AGE) in the pathogenesis of many chronic non-infectious diseases, such as type 2 diabetes, CVD and others, that are reaching epidemic proportions in the Western world. Although AGE are compounds widely recognised as generated in excess in the body in diabetic patients, the potential importance of exogenous AGE, mostly of dietary origin, has been largely ignored in the general nutrition audience. In the present review we aim to describe dietary AGE, their mechanisms of formation and absorption into the body as well as their main mechanisms of action. We will present in detail current evidence of their potential role in the development of several chronic non-infectious clinical conditions, some general suggestions on how to restrict them in the diet and evidence regarding the potential benefits of lowering their consumption.

Effect of Advanced Glycation End Products on the Progression of Alzheimer's Disease

BACKGROUND

Shared links between type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) have been well-known. A high concentration of advanced glycation end products (AGEs) has been reported to contribute to impaired mobility in patients with AD, but there is limited understanding regarding the longitudinal impact of AGEs on cognitive performance.

OBJECTIVE

This study aims to explore whether the concentrations of AGEs mediate the clinical progression of cognitive performance in patients with AD and T2DM.

METHODS

Twenty-five patients aged 79.0±5.8 years who were diagnosed with probable AD with a Clinical Dementia Rating (CDR) of 0.5 or 1 and T2DM were enrolled in this study. When patients participated in the study, the concentration of plasma AGEs was tested. A series of neuropsychological tests, namely the Mini-Mental Status Examination (MMSE), Cognitive Assessment Screening Instrument (CASI), and CDR, were performed annually during follow-up. The association between the concentration of AGEs and changes in overall cognition and cognition related daily living performance was analyzed.

RESULTS

After the mean 48.6±2.1 months of follow-up, AGEs were found to be significantly associated with a change in CDR. A total of 12 (48%) patients experienced a decline in CDR; they had a significantly higher concentration of AGEs than did those whose CDR did not deteriorate (100.5 ± 14.2 versus 81.5 ± 17.7; p = 0.007). This difference in CDR remained significant after adjustment for age, sex, education level, and apolipoprotein E4 status (adjusted p = 0.023).

CONCLUSION

In conclusion, this study indicates that a high concentration of AGEs may be a predictor of a long-term decline in cognition related daily living performance in patients with AD and T2DM.

The role of inflammaging and advanced glycation end products on paratonia in patients with dementia

Impaired motor function is a prominent characteristic of aging. Inflammatory processes and oxidative stress from advanced glycation end-products are related to impaired motor function and could plausibly be a contributing factor to the pathogenesis of paratonia, a specific motor disorder in people with dementia. Severe paratonia results in a substantial increase of a caretaker's burden and a decrease in the quality of life. The pathogenesis of paratonia is not well understood, and no effective interventions are available to combat it. Intensive glycaemic control, reducing oxidative stress, possibly combined with a low AGE diet and AGE targeting medication may be the key method for preventing advanced glycation end-product accumulation and reducing the inflammatory burden as well as possibly postponing or preventing paratonia.

Advanced glycation end products are associated with sarcopenia in older women: aging marker dynamics

The aim of this study was to determine whether advanced glycation end products (AGEs) revealed by skin autofluorescence (SAF), serum and urine pentosidine level, and serum homocysteine level can serve as a biomarker for sarcopenia in older women. The participants were 70 elderly women. The AGEs pentosidine, homocysteine, and SAF were measured as aging markers. This study shows that among the biomarkers for aging, serum pentosidine correlates with a loss of appendicular lean mass and can serve as a biomarker for sarcopenia. Moreover, SAF and homocysteine values exhibited a positive correlation with age and correlated with each other.Abbreviations: AGEs: advanced glycation end products; BIA: bioelectrical impedance analyzer; BMD: bone mineral density; DLS: degenerative lumbar scoliosis; DXA: dual-energy X-ray absorptiometry; ELISA: enzyme-linked immunoassay; HHcy: hyperhomocysteinemia; RIA: radioimmunoassay; SAF: skin autofluorescence; SMI: skeletal muscle mass index; T2DM: type 2 diabetes patients.

Advanced Glycation End Products Are Associated With Physical Activity and Physical Functioning in the Older Population

Background

Decline in physical activity and functioning is commonly observed in the older population and might be associated with biomarkers such as advanced glycation end products (AGEs). AGEs contribute to age-related decline in the function of cells and tissues in normal aging and have been found to be associated with motor function decline. The aim of this study is to investigate the association between the levels of AGEs, as assessed by skin autofluorescence, and the amount of physical activity and loss of physical functioning in older participants.

Methods

Cross-sectional data of 5,624 participants aged 65 years and older from the LifeLines Cohort Study were used. Linear regression analyses were utilized to study the associations between skin autofluorescence/AGE levels (AGE Reader), the number of physically active days (SQUASH), and physical functioning (RAND-36). A logistic regression analysis was used to study the associations between AGE levels and the compliance with the Dutch physical activity guidelines (SQUASH).

Results

A statistical significant association between AGE levels and the number of physically active days (β = -0.21, 95% confidence interval: -0.35 to -0.07, p = .004), physical functioning (β = -1.60, 95% confidence interval: -2.64 to -0.54, p = .003), and compliance with the Dutch physical activity guidelines (odds ratio = 0.76, 95% confidence interval: 0.62 to 0.94, p = .010) was revealed.

Conclusions

This study indicates that high AGE levels may be a contributing factor as well as a biomarker for lower levels of physical activity and functioning in the older population.

Association of accumulated advanced glycation end-products with a high prevalence of sarcopenia and dynapenia in patients with type 2 diabetes

AIMS/INTRODUCTION

Advanced glycation end-products (AGEs), which are a major cause of diabetic vascular complications, accumulate in various tissues under chronic hyperglycemic conditions, as well as with aging in patients with diabetes. The loss of muscle mass and strength, so-called sarcopenia and dynapenia, has recently been recognized as a diabetic complication. However, the influence of accumulated AGEs on muscle mass and strength remains unclear. The present study aimed to evaluate the association of sarcopenia and dynapenia with accumulated AGEs in patients with type 2 diabetes.

MATERIALS AND METHODS

We recruited 166 patients with type 2 diabetes aged ≥30 years (mean age 63.2 ± 12.3 years; body mass index 26.3 ± 4.9 kg/m2 ; glycated hemoglobin 7.1 ± 1.1%). Skin autofluorescence as a marker of AGEs, limb skeletal muscle mass index, grip strength, knee extension strength and gait speed were assessed.

RESULTS

Sarcopenia and dynapenia were observed in 7.2 and 13.9% of participants, respectively. Skin autofluorescence was significantly higher in patients with sarcopenia and dynapenia. Skin autofluorescence was the independent determinant for skeletal muscle mass index, grip strength, knee extension strength, sarcopenia and dynapenia.

CONCLUSIONS

Accumulated AGEs could contribute to reduced muscle mass and strength, leading to sarcopenia and dynapenia in patients with type 2 diabetes.

Exercise-Induced Mitohormesis for the Maintenance of Skeletal Muscle and Healthspan Extension

Oxidative damage is one mechanism linking aging with chronic diseases including the progressive loss of skeletal muscle mass and function called sarcopenia. Thus, mitigating oxidative damage is a potential avenue to prevent or delay the onset of chronic disease and/or extend healthspan. Mitochondrial hormesis (mitohormesis) occurs when acute exposure to stress stimulates adaptive mitochondrial responses that improve mitochondrial function and resistance to stress. For example, an acute oxidative stress via mitochondrial superoxide production stimulates the activation of endogenous antioxidant gene transcription regulated by the redox sensitive transcription factor Nrf2, resulting in an adaptive hormetic response. In addition, acute stresses such as aerobic exercise stimulate the expansion of skeletal muscle mitochondria (i.e., mitochondrial biogenesis), constituting a mitohormetic response that protects from sarcopenia through a variety of mechanisms. This review summarized the effects of age-related declines in mitochondrial and redox homeostasis on skeletal muscle protein homeostasis and highlights the mitohormetic mechanisms by which aerobic exercise mitigates these age-related declines and maintains function. We discussed the potential efficacy of targeting the Nrf2 signaling pathway, which partially mediates adaptation to aerobic exercise, to restore mitochondrial and skeletal muscle function. Finally, we highlight knowledge gaps related to improving redox signaling and make recommendations for future research.

Mitochondria as a Target for Mitigating Sarcopenia

Sarcopenia is the loss of muscle mass, strength, and physical function that is characteristic of aging. The progression of sarcopenia is gradual but may be accelerated by periods of muscle loss during physical inactivity secondary to illness or injury. The loss of mobility and independence and increased comorbidities associated with sarcopenia represent a major healthcare challenge for older adults. Mitochondrial dysfunction and impaired proteostatic mechanisms are important contributors to the complex etiology of sarcopenia. As such, interventions that target improving mitochondrial function and proteostatic maintenance could mitigate or treat sarcopenia. Exercise is currently the only effective option to treat sarcopenia and does so, in part, by improving mitochondrial energetics and protein turnover. Exercise interventions also serve as a discovery tool to identify molecular targets for development of alternative therapies to treat sarcopenia. In summary, we review the evidence linking mitochondria and proteostatic maintenance to sarcopenia and discuss the therapeutic potential of interventions addressing these two factors to mitigate sarcopenia.

Elevated Levels of Serum Pentosidine Are Associated with Dropped Head Syndrome in Older Women

STUDY DESIGN

A retrospective observational study was performed.

PURPOSE

We investigated the prevalence of sarcopenia in dropped head syndrome (DHS), and the relationship between biochemical markers, including major advanced glycation end products (AGEs), pentosidine, and DHS in older women.

OVERVIEW OF LITERATURE

AGEs have been implicated in the pathogenesis of sarcopenia.

METHODS

We studied 13 elderly women with idiopathic DHS (mean age, 77.2 years) and 20 healthy volunteers (mean age, 74.8 years). We used a bioelectrical impedance analyzer to analyze body composition, including appendicular skeletal muscle mass index (SMI; appendicular lean mass [kg]/[height (m)]2). Cervical sagittal plane alignment, including C2-C7 sagittal vertical axis (C2-C7SVA), C2-C7 angle, and C2 slope (C2S), was measured. Biochemical markers, such as serum and urinary pentosidine, serum homocysteine, 1, 25-dihydroxyvitamin D, and 25-hydroxyvitamin D, were measured. The level of each variable was compared between DHS and controls. The relationship between biochemical markers and DHS was examined.

RESULTS

Sarcopenia (SMI <5.75) was observed at a high prevalence in participants with DHS (77% compared to 22% of healthy controls). Height, weight, femoral bone mineral density, appendicular lean mass, total lean mass, and SMI all had significantly lower values in the DHS group. Serum and urinary pentosidine, and serum homocysteine were significantly higher in the DHS group compared to controls. Analysis of cervical alignment revealed a significant positive correlation of serum pentosidine with C2-C7SVA and C2S.

CONCLUSIONS

Sarcopenia was involved in DHS, and high serum pentosidine levels are associated with severity of DHS in older women.

Dietary advanced glycation end products and their relevance for human health

Due to their bioactivity and harmful potential, advanced glycation end products (AGEs) are discussed to affect human health. AGEs are compounds formed endogenously in the human body andexogenously, especially, in foods while thermal processing. In contrast to endogenous AGEs, dietary AGEs are formed in much higher extent. However, their risk potential is also depending on absorption, distribution, metabolism and elimination. For over 10 years an intense debate on the risk of dietary AGEs on human health is going on. On the one hand, studies provided evidence that dietary AGEs contribute to clinical outcomes. On the other hand, human studies failed to observe any association. Because it was not possible to draw a final conclusion, the call for new interdisciplinary approaches arose. In this review, we will give an overview on the current state of scientific knowledge in this field. In particular, we focus on (I) the occurrence of AGEs in foods and the daily uptake of AGEs, (II) contribution to endogenous levels and (III) the effect on health-/disease-related biomarkers in humans.

Targeting mitochondrial function and proteostasis to mitigate dynapenia

Traditionally, interventions to treat skeletal muscle aging have largely targeted sarcopenia-the age-related loss of skeletal muscle mass. Dynapenia refers to the age-related loss in skeletal muscle function due to factors outside of muscle mass, which helps to inform treatment strategies for aging skeletal muscle. There is evidence that mechanisms to maintain protein homeostasis and proteostasis, deteriorate with age. One key mechanism to maintain proteostasis is protein turnover, which is an energetically costly process. When there is a mismatch between cellular energy demands and energy provision, inelastic processes related to metabolism are maintained, but there is competition for the remaining energy between the elastic processes of somatic maintenance and growth. With aging, mitochondrial dysfunction reduces ATP generation capacity, constraining the instantaneous supply of energy, thus compromising growth and somatic maintenance processes. Further, with age the need for somatic maintenance increases because of the accumulation of protein damage. In this review, we highlight the significant role mitochondria have in maintaining skeletal muscle proteostasis through increased energy provision, protein turnover, and substrate flux. In addition, we provide evidence that improving mitochondrial function could promote a cellular environment that is conducive to somatic maintenance, and consequently for mitigating dynapenia. Finally, we highlight interventions, such as aerobic exercise, that could be used to improve mitochondrial function and improve outcomes related to dynapenia.

Frailty and Sarcopenia as Predictors of Adverse Health Outcomes in Persons With Diabetes Mellitus

OBJECTIVES

Diabetes mellitus is associated with premature aging, and chronic diabetes is associated with significant physical and cognitive complications. We aimed to examine frailty and sarcopenia rates and 6-month health outcomes in a clinic-based sample of patients with diabetes.

DESIGN

This study was an observational study. Participants were recruited from June 2014 to August 2014, and follow-up was conducted 6 months after day of screening.

SETTING

Participants were recruited at outpatient endocrinology, geriatric, and internal medicine clinics affiliated with Saint Louis University in St. Louis, Missouri.

PARTICIPANTS

Participants were persons with diabetes mellitus ages 50 to 90.

MEASUREMENTS

Frailty and sarcopenia were identified using the FRAIL and SARC-F screens, respectively. A chart review of the patient's health record was performed on day of screening and at follow-up. A 6-month phone questionnaire was performed to evaluate health outcomes. Logistic regressions were used to evaluate health outcomes.

RESULTS

A total of 198 persons with diabetes were recruited. Of the sample, 32.3% of sample was nonfrail, 38.9% was prefrail, and 28.8% was frail; 29.3% of the sample was identified to have sarcopenia. Prefrail [odds ratio (OR) 2.92, 95% confidence interval (CI) 1.15-7.42; P = .025] and frail (OR 4.70, 95% CI 1.67-13.19; P = .003) participants were more likely to be hospitalized overnight at 6-month follow-up. Frail (OR 3.57 95% CI 1.27-10.04; P = .016) participants were more likely to have a new activities of daily living (ADL) disability at follow-up; this association was not present for prefrail participants (OR 1.30, 95% CI .50-3.37; P = .59). Participants with sarcopenia were more likely to be hospitalized (OR 3.80, 95% CI 1.67-8.61; P = .001) and to have a new ADL disability (OR 4.24, 95% CI 1.76-10.18; P = .001) at 6-month follow-up.

CONCLUSIONS

Among clinic patients with diabetes mellitus ages 50-90 year old, frailty and sarcopenia prevalence is high, and both syndromes are predictors of being hospitalized overnight and new ADL disability after 6 months.

Association between advanced glycation end-products and functional performance in Alzheimer's disease and mixed dementia

BACKGROUND

People with Alzheimer's disease (AD) experience, in addition to the progressive loss of cognitive functions, a decline in functional performance such as mobility impairment and disability in activities of daily living (ADL). Functional decline in dementia is mainly linked to the progressive brain pathology. Peripheral biomechanical changes by advanced glycation end-products (AGEs) have been suggested but have yet to be thoroughly studied.

METHODS

A multi-center, longitudinal, one-year follow-up cohort study was conducted in 144 people with early stage AD or mixed Alzheimer's/Vascular dementia. Linear mixed model analyses was used to study associations between AGE-levels (AGE reader) and mobility (Timed Up and Go), and ADL (Groningen Activity Restriction Scale and Barthel index), respectively.

RESULTS

A significant association between AGE levels and mobility (β = 3.57, 95%CI: 1.43-5.73) was revealed; however, no significant association between AGE levels and ADL was found. Over a one-year time span, mean AGE levels significantly increased, and mobility and ADL performance decreased. Change in AGE levels was not significantly correlated with change in mobility.

CONCLUSIONS

This study indicates that high AGE levels could be a contributing factor to impaired mobility but lacks evidence for an association with ADL decline in people with early stage AD or mixed dementia. Future research is necessary on the reduction of functional decline in dementia regarding the effectiveness of interventions such as physical activity programs and dietary advice possibly in combination with pharmacologic strategies targeting AGE accumulation.