Impaired skeletal muscle mitochondrial function in morbidly obese patients is normalized one year after bariatric surgery

A pilot study of the effects of supervised exercise training on body composition, cardiometabolic risk factors, muscle strength and functional capacity in individuals with bariatric surgery

The main objective of this pilot study was to evaluate the effects of functional exercise training (FET) and home exercise training (HET) on body composition, cardiometabolic risk factors, muscle strength, and functional capacity in individuals with bariatric surgery. The sample of the study included 30 individuals who underwent bariatric surgery. The FET group had functional exercise training consisting of stretching, aerobic, strengthening, and balance exercises assigned by a physiotherapist (n = 15), and the HET group had the same exercises under supervision (n = 15). The training sessions were planned as × 3 per week for a period of 8 weeks. Body composition, cardiometabolic risk factors, cardiometabolic risk status, muscle strength, and functional capacity of all individuals were evaluated before and after training. According to the measurements, body weight (BW), body mass index (BMI), body fat mass (BFM), C-reactive protein, glycated hemoglobin, insulin resistance, cardiovascular risk total score, and ten-year cardiovascular percentage risk decreased significantly (p < 0.05), while HDL-C, leg, back, and hand grip strength (right-left), and walking distance increased significantly (p < 0.05) in the FET group. In the HET group, there were significant increases in body fat percentage (BFM %), BFM, and body muscle mass percentage (BMM %) (p < 0.05), while body muscle mass (BMM), right hand grip strength, leg and back muscle strength, and walking distance scores significantly decreased (p < 0.05). It was concluded that personalized and supervised FET has a positive effect on body composition, cardiometabolic risk factors, muscle strength, and functional capacity, and it can be recommended as a safe exercise model for bariatric surgery patients.

Mitochondrial adaptations to calorie restriction and bariatric surgery in human skeletal muscle: a systematic review with meta-analysis

OBJECTIVE

We performed a meta-analysis to determine the changes induced by calorie restriction (CR) and bariatric surgery on human skeletal muscle mitochondria.

METHODS

A systematic search of Medline and Web of Science was conducted. Controlled trials exploring CR (≥14 days) and mitochondrial function and/or content assessment were included. Moreover, studies analyzing weight loss following gastric surgery were included for comparison purposes. Human muscle data from 28 studies assessing CR (520 muscle samples) and from 10 studies assessing bariatric surgery (155 muscle samples) were analyzed in a random effect meta-analysis with three a priori chosen covariates.

MAIN RESULTS

We report a decrease (p < 0.05) (mean (95 % CI)) in maximal mitochondrial state 3 respiration in response to CR (-0.44 (-0.85, -0.03)) but not in response to surgery (-0.33 (-1.18, 0.52)). No changes in mitochondrial content were reported after CR (-0.05 (-0.12, 0.13)) or in response to surgery (0.23 (-0.05, 0.52)). Moreover, data from CR subjects showed a reduction in complex IV (CIV) activity (-0.29 (-0.56, -0.03)) but not in CIV content (-0.21 (-0.63, 0.22)). Similar results were obtained when the length of the protocol, the initial body mass index, and the estimated energy deficit were included in the model as covariates.

CONCLUSION

The observation of reduced maximal mitochondrial state 3, uncoupled respiration, and CIV activity without altering mitochondrial content suggests that, in human skeletal muscle, CR mainly modulates intrinsic mitochondrial function.

Impairment of Mitochondrial Respiration in Metabolic Diseases: An Overview

Mitochondrial dysfunction has emerged as a central pathomechanism in the setting of obesity and diabetes mellitus, linking these intertwined pathologies that share insulin resistance as a common denominator. High-resolution respirometry (HRR) is a state-of-the-art research method currently used to study mitochondrial respiration and its impairment in health and disease. Tissue samples, cells or isolated mitochondria are exposed to various substrate-uncoupler-inhibitor-titration protocols, which allows the measurement and calculation of several parameters of mitochondrial respiration. In this review, we discuss the alterations of mitochondrial bioenergetics in the main dysfunctional organs that contribute to the development of the obese and diabetic phenotypes in both animal models and human subjects. Herein we review data regarding the impairment of oxidative phosphorylation as integrated mitochondrial function assessed by means of HRR. We acknowledge the critical role of this method in determining the alterations in oxidative phosphorylation occurring in the early stages of metabolic pathologies. We conclude that there is a mutual two-way relationship between mitochondrial dysfunction and insulin insensitivity that characterizes these diseases.

Effects of a 3-Month Physical Training on Cortisol and Testosterone Responses in Women After Bariatric Surgery

PURPOSE

Although it is well established that physical activity (PA) may partially correct the metabolic and hormonal alterations observed in patients with obesity, knowledge of its impact after bariatric surgery (BS) remains poor. The purpose of this study was to assess the repercussions of physical training on cortisol and testosterone responses in post-BS women.

MATERIALS AND METHODS

According to a randomized clinical trial, a PA group (11 women) started a 3-month physical training 6 weeks after BS, whereas no specific activity was proposed to a control group (9 women). Submaximal exercise (i.e., 30 min at 60% VO₂peak) was performed by all subjects just before and after the 3-month period. Blood samples were taken at rest, after 10, 20, and 30 min of exercise and 10 min of passive recovery for cortisol and testosterone analyses. Blood glucose, blood lactate, and heart rate were assessed at the same time.

RESULTS

Before the program, a significant increase in cortisol, blood lactate, and heart rate was observed in all subjects during the submaximal exercise vs. rest, with no change in blood glucose and testosterone. After vs. before the 3-month period, no modification in any parameter was noted at rest in either group. However, during exercise, lack of cortisol increase and lower heart rate were found in the PA group only, with disappearance of the increase in blood lactate in both groups.

CONCLUSION

Our results show some beneficial effects of physical training on hormonal and physical parameters. Further studies are needed to determine the biological and clinical significance of these adaptations induced by physical training in women after BS.

Effects of bariatric surgery on cardiorespiratory fitness: A systematic review and meta-analysis

Although bariatric surgery (BS) is recognized as an effective strategy for body weight loss, its impact on cardiorespiratory fitness (CRF) is still unclear. We aimed to examine postoperative changes in CRF (VO_2max/peak ) and its relationship with weight loss among adults undergoing BS. We systematically searched the WoS, PubMed, MEDLINE, and Scopus databases. Observational and intervention studies were selected reporting the presurgery and postsurgery CRF, measured by breath-by-breath VO₂ or its estimation. Eleven articles (312 patients) revealed that BS leads to a reduction in absolute VO_2max/peak in the short term (effect size, ES = -0.539; 95%CI = -0.708, -0.369; p < 0.001), and those patients who suffered a more significant decrease in BMI after BS also had a greater loss of absolute VO_2max/peak . However, VO_2max/peak relative to body weight increased after surgery (ES = 0.658; 95%CI = 0.473, 0.842; p < 0.001). An insufficient number of studies were found investigating medium and long-term changes in CRF after BS. This study provides moderate-quality evidence that the weight loss induced by BS can reduce CRF in the short term, which represents a therapeutic target to optimize BS outcomes. More high-quality studies are needed to evaluate the impact of BS on VO_2max/peak in the short, medium, and long term including normalized values for fat-free mass.

Effect of very large body mass loss on energetics, mechanics and efficiency of walking in adults with obesity: mass-driven versus behavioural adaptations

Abstract

Understanding the mechanisms involved in the higher energy cost of walking (NC_w: the energy expenditure above resting per unit distance) in adults with obesity is pivotal to optimizing the use of walking in weight management programmes. Therefore, this study aimed to investigate the mechanics, energetics and mechanical efficiency of walking after a large body mass loss induced by bariatric surgery in individuals with obesity. Nine adults (39.5 ± 8.6 year; BMI: 42.7 ± 4.6 kg m^–2) walked at five fixed speeds before (baseline) and after the bariatric surgery (post 1 and post 2). Gas exchanges were measured to obtain NC_w. A motion analysis system and instrumented treadmill were combined to assess total mechanical work (W_tot). Mechanical efficiency (W_tot NC_w^–1) was also calculated. Participants lost 25.7 ± 3.4% of their body mass at post 1 (6.6 months; P < 0.001) and 6.1 ± 4.9% more at post 2 (12 months; P = 0.014). Mass‐normalized NC_w was similar between baseline and post 1 and decreased at post 2 compared to that at baseline (−6.2 ± 2.7%) and post 1 (−8.1 ± 1.9%; P ≤ 0.007). No difference was found in mass‐normalized W_tot during follow‐up (P = 0.36). Mechanical efficiency was similar at post 1 and post 2 when compared to that at baseline (P ≥ 0.19), but it was higher (+14.1 ± 4.6%) at post 2 than at post 1 (P = 0.013). These findings showed that after a very large body mass loss, individuals with obesity may reorganize their walking pattern into a gait more similar to that of lean adults, thus decreasing their NC_w by making their muscles work more efficiently.

Key points

A higher net (above resting) energy cost of walking (lower gait economy) is observed in adults with obesity compared to lean individuals.

Understanding the mechanisms (i.e. mass driven, gait pattern and behavioural changes) involved in this extra cost of walking in adults with obesity is pivotal to optimizing the use of walking to promote daily physical activity and improve health in these individuals.

We found that very large weight loss induced by bariatric surgery significantly decreased the energy cost of walking per kg of body mass after 1 year with similar total mechanical work per kg of body mass, resulting in an increased mechanical efficiency of walking.

Individuals with obesity may reorganize their walking pattern into a gait more similar to that of adults of normal body mass, thus decreasing their energy cost of walking by making their muscles work more efficiently.

Skeletal muscle mitochondrial network dynamics in metabolic disorders and aging

With global demographics trending towards an aging population, the numbers of individuals with an age-associated loss of independence is increasing. A key contributing factor is loss of skeletal muscle mitochondrial, metabolic, and contractile function. Recent advances in imaging technologies have demonstrated the importance of mitochondrial morphology and dynamics in the pathogenesis of disease. In this review, we examine the evidence for altered mitochondrial dynamics as a mechanism in age and obesity-associated loss of skeletal muscle function, with a particular focus on the available human data. We highlight some of the areas where more data are needed to identify the specific mechanisms connecting mitochondrial morphology and skeletal muscle dysfunction.

How Does Fat Mass Change in the First Year After Bariatric Surgery? A Systemic Review and Meta-Analysis

This systematic review and meta-analysis investigated the time-course effect of different type of bariatric surgeries (BS) up to 1 year post-surgery on fat mass (FM) and body fat percentage (BFP) in patients with morbid obesity. We searched PubMed, Scopus, EMBASE, ISI web of science, and Cochrane databases from October 2002 until May 2020 with no restriction in the English language, to find studies examining the effect of BS on FM (kg) and BFP (%) in morbid obese patients. Meta-analysis of 103 studies carried out on data of 18,166 and 14,575 morbid obese patients following BS, showed that BS was associated with a substantial decrease in FM and BFP, respectively, in 1 month (- 8.17 kg [95% CI - 9.07, - 7.27] and - 1.51% [95% CI - 2.56, - 0.46]), 3 months (- 15.75 [95% CI - 17.49, - 14.0] and - 4.90 [95% CI - 5.97, - 3.83]), 6 months (- 22.51 [95% CI - 23.93, - 21.09] and - 8.56% [95% CI - 9.63, - 7.49]), and 12 months (- 29.69 [95% CI - 31.3, - 28.09] and - 13.49% [95% CI - 14.52, - 12.40]) after the surgery. In conclusion, BS was associated with sustained declines in FM and BFP, from 1 to 12 months, with no indication of plateau phase post-surgery post-operatively. The present study emphasizes that post-bariatric care should have more focus on FM loss during 1-year post-surgery to identify the patients at risk for fat loss plateau.

Comparison of the Improvement Effect of Deep Ocean Water with Different Mineral Composition on the High Fat Diet-Induced Blood Lipid and Nonalcoholic Fatty Liver Disease in a Mouse Model

Accumulated lipid droplets in liver cause nonalcoholic fatty liver disease (NAFLD). Deep ocean water (DOW) containing high levels of magnesium, calcium, and potassium, etc. was proven to suppress hepatic lipid in obese rats fed high fat diet in the previous study. However, the effect of mineral compositions of DOW on the prevention of NAFLD is still unclear. This study removed calcium and potassium from DOW for modulating the mineral composition, and further compared the effects of DOW (D1(Mg + Ca + K)), DOW with low potassium (D2(Mg + Ca)), and DOW with low calcium and potassium (D3(Mg)) on the prevention of NAFLD in the mice model fed with high fat diet. In these results, DOW with high magnesium levels reduced serum and liver triglyceride and cholesterol levels and serum AST and ALT activities. However, when the calcium and/or potassium minerals were removed from DOW, the effects of reduction of triglyceride level, inhibition of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and peroxisome proliferator-activated receptor-alpha (PPAR-α) expressions, and activation of superoxide dismutase, catalase, and glutathione reductase activities would be weaker. In conclusion, DOW including magnesium, calcium and potassium minerals has the strongest preventive effect on NAFLD in a mouse model by increasing the antioxidant system and inhibiting fatty acid biosynthesis.

The lifecycle of skeletal muscle mitochondria in obesity

Skeletal muscle possesses dramatic metabolic plasticity that allows for the rapid adaptation in cellular energy transduction to meet the demands of the organism. Obesity elicits changes in skeletal muscle structure and function, resulting in the accumulation of intramuscular lipids. The accumulation of intramuscular lipids in obesity is associated with impaired skeletal muscle mitochondrial content and function. Mitochondria exist as a dynamic network that is regulated by the processes of biogenesis, fusion, fission, and mitophagy. In this review, we outline adaptations in molecular pathways that regulate mitochondrial structure and function in obesity. We highlight the emerging role of dysregulated skeletal muscle macroautophagy and mitochondrial turnover in obesity. Future research should further elucidate the role of mitophagy in observed reductions in mitochondrial content and function during obesity.

Type 2 Diabetes Modifies Skeletal Muscle Gene Expression Response to Gastric Bypass Surgery

INTRODUCTION

Roux-en-Y gastric bypass (RYGB) is an effective treatment for type 2 diabetes mellitus (T2DM) that can result in remission of clinical symptoms, yet mechanisms for improved skeletal muscle health are poorly understood. We sought to define the impact of existing T2DM on RYGB-induced muscle transcriptome changes.

METHODS

Vastus lateralis biopsy transcriptomes were generated pre- and 1-year post-RYGB in black adult females with (T2D; n = 5, age = 51 ± 6 years, BMI = 53.0 ± 5.8 kg/m²) and without (CON; n = 7, 43 ± 6 years, 51.0 ± 9.2 kg/m²) T2DM. Insulin, glucose, and HOMA-IR were measured in blood at the same time points. ANCOVA detected differentially expressed genes (p < 0.01, fold change < |1.2|), which were used to identify enriched biological pathways.

RESULTS

Pre-RYGB, 95 probes were downregulated with T2D including subunits of mitochondrial complex I. Post-RYGB, the T2D group had normalized gene expression when compared to their non-diabetic counterparts with only three probes remaining significantly different. In the T2D, we identified 52 probes upregulated from pre- to post-RYGB, including NDFUB7 and NDFUA1.

CONCLUSION

Black females with T2DM show extensive downregulation of genes across aerobic metabolism pathways prior to RYGB, which resolves 1 year post-RYGB and is related to improvements in clinical markers. These data support efficacy of RYGB for improving skeletal muscle health, especially in patients with T2DM.

Pre-operative aerobic exercise on metabolic health and surgical outcomes in patients receiving bariatric surgery: A pilot trial

Objective

Examine if adding aerobic exercise to standard medical care (EX+SC) prior to bariatric surgery improves metabolic health in relation to surgical outcomes.

Methods

Fourteen bariatric patients (age: 42.3±2.5y, BMI: 45.1±2.5 kg/m²) met inclusion criteria and were match-paired to pre-operative SC (n = 7) or EX+SC (n = 7; walking 30min/d, 5d/wk, 65–85% HR_peak) for 30d. A 120min mixed meal tolerance test was performed pre- and post-intervention (~2d prior to surgery) to assess insulin sensitivity (Matsuda Index) and metabolic flexibility (indirect calorimetry). Aerobic fitness (VO₂peak), body composition (BodPod), and adipokines (adiponectin, leptin) were also measured. Omental adipose tissue was collected during surgery to quantify gene expression of adiponectin and leptin, and operating time and length of hospital stay were recorded. ANOVA and Cohen’s d effect size (ES) was used to test group differences.

Results

SC tended to increase percent body fat (P = 0.06) after the intervention compared to EX+SC. Although SC and EX+SC tended to raise insulin sensitivity (P = 0.11), EX+SC enhanced metabolic flexibility (P = 0.01, ES = 1.55), reduced total adiponectin (P = 0.01, ES = 1.54) with no change in HMW adiponectin and decreased the length of hospital stay (P = 0.05) compared to SC. Albeit not statistically significant, EX+SC increased VO₂peak 2.9% compared to a 5.9% decrease with SC (P = 0.24, ES = 0.91). This increased fitness correlated to shorter operating time (r = -0.57, P = 0.03) and length of stay (r = -0.58, P = 0.03). Less omental total adiponectin (r = 0.52, P = 0.09) and leptin (r = 0.58, P = 0.05) expression correlated with shorter operating time, and low leptin expression was linked to shorter length of stay (r = 0.70, P = 0.01), and low leptin expression was linked to shorter length of stay (r = 0.70, P = 0.01).

Conclusion

Adding pre-operative aerobic exercise to standard care may improve surgical outcomes through a fitness and adipose tissue derived mechanism.

Metabolic bariatric surgery as a treatment for obstructive sleep apnea hypopnea syndrome: review of the literature and potential mechanisms

Obstructive sleep apnea hypopnea syndrome (OSAHS) is closely related to obesity and can cause multiple organs and systems damage. Metabolic bariatric surgery (MBS) is presently the only long-term effective treatment and an important strategy for severely obese population, which also provides a novel therapeutic for obese patients with OSAHS, especially in patients with poor continuous positive air pressure (CPAP) adherence. To date, the resolution mechanism of OSAHS in obese patients after MBS has not been fully clarified. In addition, there is no specific metabolic bariatric surgical treatment of OSAHS guidelines. Therefore, this review provides an update on the relationship between OSAHS and MBS for highlighting the importance of weight loss strategies for obese patients with OSAHS.

Association of the serum irisin level with obstructive sleep apnea: a body mass index- and physical activity-matched study

Obesity is strongly correlated with the pathogenesis of obstructive sleep apnea (OSA); myokines may play important roles in this condition. We performed a body mass index- (BMI) and physical activity- (PA) matched study to explore the relationship between the irisin level and OSA. Ninety-six consecutive participants were recruited. After matching in terms of BMI and PA, 28 OSA patients and 28 healthy controls were finally included. Whole-night laboratory-based polysomnography was used to identify OSA. The Recent Physical Activity Questionnaire and Epworth Sleepiness Scale Questionnaire were employed to assess PA over the past 4 weeks, and daytime sleepiness. We measured serum irisin, fasting blood glucose, and insulin levels in blood samples. The serum irisin concentrations differed significantly between the control, mild OSA, moderate OSA, and severe OSA groups (p < 0.001) and correlated significantly with the apnea/hypopnea index (AHI) (r = -0.787, p < 0.001). All of age, BMI, neck, waist and hip circumferences, fasting blood glucose level, and the Epworth Sleepiness Scale and PA scores were associated with irisin levels (p < 0.05). After adjustment for these factors, the serum irisin level was independently correlated with the AHI (r = -0.428, p = 0.002). On forward logistic regression analysis, the association remained significant in the final multiple regression model (β = -0.107, p < 0.001). The serum irisin concentration was significantly correlated with OSA severity, independently of BMI and PA. Further studies are needed to determine the molecular mechanisms in play.

Effects of 3-month high-intensity interval training vs. moderate endurance training and 4-month follow-up on fat metabolism, cardiorespiratory function and mitochondrial respiration in obese adults

PURPOSE

The purpose of this study was to investigate, in obese adults, changes in body composition, physical capacities, fat oxidation and ex vivo mitochondrial respiration induced by a 3-month either moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT); afterwards, the patients were followed for four months.

METHODS

Thirty-two patients (mean age 39 years; mean body mass index [BMI] 36 kg∙m^-2) participated in this study attending ~ 34 sessions of training. At baseline (PRE), at the end of the program (POST) and after follow-up, body composition, peak O₂ uptake (V'O₂peak) and fat oxidation rate were measured. Vastus lateralis biopsies for the evaluation of mitochondrial respiration were performed only at PRE and POST.

RESULTS

At POST, body mass (BM) and fat mass (FM) decreased (- 6 and - 14%, respectively, P < 0.05) in MICT and HIIT; V'O₂peak increased in both groups (+ 6 and + 16%, respectively, P < 0.05). Maximal fat oxidation rate increased only after HIIT (P < 0.001). Maximal ADP-stimulated mitochondrial respiration normalized by citrate synthase increased (P < 0.05) by 67% and 36% in MICT and HIIT, respectively, without significant difference. After follow-up, BM and FM were still lower (- 4 and - 20%, respectively, P < 0.050) compared with baseline in both groups. Only after HIIT, V'O₂peak (+ 8%) and maximal fat oxidation rate were still higher (P < 0.05).

CONCLUSIONS

HIIT was more effective in improving and maintaining V'O₂peak and fat oxidation. These results may be relevant for an appropriate prescription of training programs designed to optimize aerobic fitness in obese subjects.

Hepatocyte p53 ablation induces metabolic dysregulation that is corrected by food restriction and vertical sleeve gastrectomy in mice

P53 has been implicated in the pathogenesis of obesity and diabetes; however, the mechanisms and tissue sites of action are incompletely defined. Therefore, we investigated the role of hepatocyte p53 in metabolic homeostasis using a hepatocyte-specific p53 knockout mouse model. To gain further mechanistic insight, we studied mice under two complementary conditions of restricted weight gain: vertical sleeve gastrectomy (VSG) or food restriction. VSG or sham surgery was performed in high-fat diet-fed male hepatocyte-specific p53 wild-type and knockout littermates. Sham-operated mice were fed ad libitum or food restricted to match their body weight to VSG-operated mice. Hepatocyte-specific p53 ablation in sham-operated ad libitum-fed mice impaired glucose homeostasis, increased body weight, and decreased energy expenditure without changing food intake. The metabolic deficits induced by hepatocyte-specific p53 ablation were corrected, in part by food restriction, and completely by VSG. Unlike food restriction, VSG corrected the effect of hepatocyte p53 ablation to lower energy expenditure, resulting in a greater improvement in glucose homeostasis compared with food restricted mice. These data reveal an important new role for hepatocyte p53 in the regulation of energy expenditure and body weight and suggest that VSG can improve alterations in energetics associated with p53 dysregulation.

Roux-en-Y gastric bypass surgery restores insulin-mediated glucose partitioning and mitochondrial dynamics in primary myotubes from severely obese humans

Background/Objectives:

Impaired insulin-mediated glucose partitioning is an intrinsic metabolic defect in skeletal muscle from severely obese humans (BMI ≥ 40 kg/m²). Roux-en-Y gastric bypass (RYGB) surgery has been shown to improve glucose metabolism in severely obese humans. The purpose of the study was to determine the effects of RYGB surgery on glucose partitioning, mitochondrial network morphology, and markers of mitochondrial dynamics skeletal muscle from severely obese humans.

Subject/Methods:

Human skeletal muscle cells were isolated from muscle biopsies obtained from RYGB patients (BMI = 48.0 ± 2.1, n=7) prior to, 1-month and 7-months following surgery and lean control subjects (BMI = 22.4 ± 1.1, n=7). Complete glucose oxidation, non-oxidized glycolysis rates, mitochondrial respiratory capacity, mitochondrial network morphology and regulatory proteins of mitochondrial dynamics were determined in differentiated human myotubes.

Results:

Myotubes derived from severely obese humans exhibited enhanced glucose oxidation (13.5%; 95%CI [7.6, 19.4], P = 0.043) and reduced non-oxidized glycolysis (−1.3%; 95%CI [−11.1, 8.6]) in response to insulin stimulation at 7-months after RYGB when compared to the pre-surgery state (−0.6%; 95%CI [−5.2, 4.0] and 19.5%; 95%CI [4.0, 35.0], P =0.006), and were not different from the lean controls (16.7%; 95%CI [11.8, 21.5] and 1.9%; 95%CI [−1.6, 5.4], respectively). Further, number of fragmented mitochondria and Drp1(Ser⁶¹⁶) phosphorylation and were trended to reduced/reduced (0.0104, 95%CI [0.0085, 0.0126], P = 0.091 and 0.0085, 95%CI [0.0068, 0.0102], P = 0.05) in myotubes derived from severely obese humans at 7-months after RYGB surgery in comparison to the pre-surgery state. Finally, Drp1(Ser⁶¹⁶) phosphorylation was negatively correlated with insulin-stimulated glucose oxidation (r = −0.49, P = 0.037).

Conclusion/Interpretation:

These data indicate that an intrinsic metabolic defect of glucose partitioning in skeletal muscle from severely obese humans is restored by RYGB surgery. The restoration of glucose partitioning may be regulated through reduced mitochondrial fission protein Drp1 phosphorylation.

Dynamic changes of muscle insulin sensitivity after metabolic surgery

The mechanisms underlying improved insulin sensitivity after surgically-induced weight loss are still unclear. We monitored skeletal muscle metabolism in obese individuals before and over 52 weeks after metabolic surgery. Initial weight loss occurs in parallel with a decrease in muscle oxidative capacity and respiratory control ratio. Persistent elevation of intramyocellular lipid intermediates, likely resulting from unrestrained adipose tissue lipolysis, accompanies the lack of rapid changes in insulin sensitivity. Simultaneously, alterations in skeletal muscle expression of genes involved in calcium/lipid metabolism and mitochondrial function associate with subsequent distinct DNA methylation patterns at 52 weeks after surgery. Thus, initial unfavorable metabolic changes including insulin resistance of adipose tissue and skeletal muscle precede epigenetic modifications of genes involved in muscle energy metabolism and the long-term improvement of insulin sensitivity.

Surgical weight-loss interventions improve insulin sensitivity via incompletely understood mechanisms. Here the authors assess skeletal muscle epigenetic changes in individuals with obesity following metabolic surgery and compare them with data from individuals without obesity.

Bariatric Surgery Reduces Elevated Urinary Mitochondrial DNA Copy Number in Patients With Obesity

OBJECTIVE

Obesity is an independent risk factor for chronic kidney disease. Recently, urinary mitochondrial DNA (mtDNA) has been used as a surrogate marker of mitochondrial damage in various kidney diseases. However, there are no data regarding its use in patients with obesity or the change in urinary mtDNA copy number after surgery.

DESIGN

We prospectively recruited age- and sex-matched healthy volunteers and patients with obesity (n = 22 in each group: nine men and 13 women). The copy number of urinary and serum mtDNA nicotinamide adenine dinucleotide dehydrogenase subunit-1 (mtND-1) and cytochrome-c oxidase 3 (mtCOX-3) was measured using quantitative PCR. We measured urinary mtDNA and body weight and carried out laboratory tests, 6 months after surgery.

RESULTS

Urinary mtND-1 copy number was significantly higher in the obese group than in healthy volunteers. However, urinary mtCOX-3 and serum ND-1 copy numbers in the obese group did not differ from that in the healthy volunteers. When patients with obesity were divided into two groups, according to their baseline mtND-1 copy number, bariatric surgery reduced the mtND-1 copy number (P = 0.006) in the high baseline mtDNA copy-number group. The change in urinary mtND-1 copy number was correlated with a change in urinary albumin (r = 0.478, P = 0.025).

CONCLUSIONS

Obesity is associated with elevated urinary mtND-1 copy number. Bariatric surgery reduces the elevated urinary mtND-1 copy number in patients with obesity. This suggests that bariatric surgery could attenuate mitochondrial damage in the kidney cells of patients with obesity.

From Normal to Obesity and Back: The Associations between Mitochondrial DNA Copy Number, Gender, and Body Mass Index

Mitochondrial DNA (mtDNA) encodes core subunits of oxidative phosphorylation complexes and, as a result of intricate regulatory crosstalk between nuclear and mitochondrial genomes, the total number of mtDNA copies fits the requirements of each cell type. Deviations from the physiological number of mtDNA copies are expected to be deleterious and might cause some inherited diseases and normal ageing. We studied 46 obese patients with type 2 diabetes (T2DM) one year after a laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (RYGB). The results were compared with normal-weight patients without T2DM (control group 1) (body mass index (BMI) = 22.5 ± 3.01 kg/m²) and patients with obesity without T2DM (control group 2) (BMI = 36 ± 3.45 kg/m²). We detected an increase of mtDNA copy number in the cells of the buffy coat obtained from peripheral blood, sampled one year after bariatric surgery. We also found that average mtDNA copy number as well as its dynamics (before and after the surgery) are gender-specific. To the best of our knowledge, this is the first evidence for the restoration of mtDNA copy number in obese patients after LSG and RYGB.

Influence of exercise amount and intensity on long-term weight loss maintenance and skeletal muscle mitochondrial ROS production in humans

Sustaining a weight loss after a lifestyle intervention is challenging. The objective of the present study was to investigate if mitochondrial function is associated with the ability to maintain a weight loss. Sixty-eight former participants in an 11-12-week lifestyle intervention were recruited into 2 groups; weight loss maintenance (WLM; body mass index (BMI): 32 ± 1 kg/m²) and weight regain (WR; BMI: 43 ± 2 kg/m²) based on weight loss measured at a follow-up visit (WLM: 4.8 ± 0.4; WR: 7.6 ± 0.8 years after lifestyle intervention). Maximal oxygen consumption rate, physical activity level, and blood and muscle samples were obtained at the follow-up experiment. Mitochondrial respiratory capacity and reactive oxygen species (ROS) production were measured. Fasting blood samples were used to calculate glucose homeostasis index. WR had impaired glucose homeostasis and decreased maximal oxygen uptake and physical activity level compared with WLM. The decreased physical activity in WR was due to a lower activity level at vigorous and moderate intensities. Mitochondrial respiratory capacity and citrate synthase (CS) activity was higher in WLM, but intrinsic mitochondrial respiratory capacity (mitochondrial respiratory capacity corrected for mitochondrial content (CS activity)) was similar. ROS production was higher in WR compared with WLM, which was accompanied by a decreased content of antioxidant proteins in WR. Intrinsic mitochondrial respiratory capacity in skeletal muscle is not associated with the ability to maintain a long-term weight loss. WLM had a higher maximal oxygen uptake, physical activity level, mitochondrial respiratory capacity and CS activity compared with WR. The reduced glucose tolerance was concurrent with increased ROS production per mitochondria in WR, and could also be associated with the lower physical activity level in this group.

Mitochondrial respiratory capacity remains stable despite a comprehensive and sustained increase in insulin sensitivity in obese patients undergoing gastric bypass surgery

AIM

It has been proposed, but not yet demonstrated by convincing evidence in published articles, that insulin resistance and mitochondrial respiratory function are causally related physiological phenomena. Here, we tested the prediction that weight loss-induced increase in insulin sensitivity will correlate with a corresponding change in mitochondrial respiratory capacity over the same time period.

METHODS

Insulin sensitivity was evaluated using the hyperinsulinaemic-euglycaemic clamp technique, and skeletal muscle mitochondrial respiratory capacity was evaluated by high-resolution respirometry in 26 patients with obesity. Each experiment was performed ~2 months and 1-2 weeks before, and ~4 and ~19 months after Roux-en-Y gastric bypass (RYGB) surgery.

RESULTS

A substantial weight loss was observed in all patients, and insulin sensitivity increased in all patients over the 21-months time period of the study. In contrast, skeletal muscle mitochondrial respiratory capacity, intrinsic mitochondrial respiratory capacity and mitochondrial content remained unchanged over the same time period.

CONCLUSION

Among obese patients with and without type 2 diabetes undergoing RYGB surgery, intrinsic mitochondrial respiratory capacity in skeletal muscle is not correlated with insulin sensitivity before or after the surgical intervention. Mitochondrial respiratory function may not be germane to the pathophysiology and/or aetiology of obesity and/or type 2 diabetes.

Associations of Mitochondrial Fatty Acid Oxidation with Body Fat in Premenopausal Women

Higher in vivo fatty acid (FA) oxidation rates have been reported in obese individuals compared to lean counterparts; however whether this reflects a shift in substrate-specific oxidative capacity at the level of the skeletal muscle mitochondria has not been examined. The purpose of this study was to test the hypothesis that in situ measures of skeletal muscle mitochondria FA oxidation would be positively associated with total body fat. Participants were 38 premenopausal women (BMI = 26.5 ± 4.3 kg/m²). Total and regional fat were assessed by dual-energy X-ray absorptiometry (DXA). Mitochondrial FA oxidation was assessed in permeabilized myofibers using high-resolution respirometry and a palmitoyl carnitine substrate. We found positive associations of total fat mass with State 3 (ADP-stimulated respiration) (r = 0.379, p < 0.05) and the respiratory control ratio (RCR, measure of mitochondrial coupling) (r = 0.348, p < 0.05). When participants were dichotomized by high or low body fat percent, participants with high total body fat displayed a higher RCR compared to those with low body fat (p < 0.05). There were no associations between any measure of regional fat and mitochondrial FA oxidation independent of total fat mass. In conclusion, greater FA oxidation in obesity may reflect molecular processes that enhance FA oxidation capacity at the mitochondrial level.

Physical Fitness and Body Composition Two Years after Roux-En-Y Gastric Bypass in Adolescents

BACKGROUND

We have previously shown promising results 2 years after Roux-en-Y gastric bypass surgery, within the Adolescence Morbid Obesity Surgery study (AMOS). The aim of the current study was to describe the 2-year outcome in cardiorespiratory fitness, body composition, and functional capacity in the Stockholm subset of the AMOS study.

METHODS

Forty-one adolescents (10 male, 31 female, age 14-18 years, body mass index 35-69 kg·m^-2) were included. In addition to anthropometric measurements, participants performed a submaximal bicycle test, 6-min walk test, dual-energy X-ray absorptiometry, and a short interview at baseline, 1 and 2 years after surgery.

RESULTS

Relative improvements in maximal oxygen consumption (VO₂max) per kilogram body mass (+62 %) and per kilogram fat-free mass (+21 %), as well as walking distance (+13 %) were observed after 1 year, and persisted 2 years after surgery. Despite a reduction of fat-free mass (-15 %), absolute VO₂max was maintained across the full group (+8 %, p = ns) and significantly increased in non-smokers. Body mass and fat mass were significantly decreased (-45.4 and -33.3 kg, respectively). Self-reported physical activity was significantly increased, and pain associated with movement was reduced.

CONCLUSIONS

In adolescents with obesity, Roux-en-Y gastric bypass improved VO₂max more than could be explained by fat mass loss alone. In combination with improved functional capacity and body composition, these results suggest that surgery in adolescence might add specific benefits of importance for future health.

Unchanged mitochondrial phenotype, but accumulation of lipids in the myometrium in obese pregnant women

KEY POINTS

Obesity during pregnancy and childbirth is associated with labour dystocia leading to instrumental or operative delivery, but the underlying pathophysiological mechanisms remain unclear and insufficient uterine contractility has been suggested. This study examined whether reduced myometrial mitochondrial capacity or quantity could contribute as a pathophysiological mechanism to labour dystocia. Data did not support reduced myometrial mitochondrial capacity or quantity in the myometrium at term in obese women, but a reduced myocyte density with increased triglyceride content was demonstrated, which could lead to poorer uterine contractility. These results add to the understanding of systemic effects of obesity, placing also the myometrium at term as an affected non-adipose tissue.

ABSTRACT

Obesity is known to increase the risk of labour dystocia and insufficient energy supply, due to reduced mitochondrial capacity or quantity, could be a possible mechanism leading to reduced efficiency of uterine contractility during labour. In the present study of 36 women having an elective Caesarean section at term, obesity did not change mitochondrial phenotype in the myometrial myocyte obtained from uterine biopsies taken at delivery. Respiration rates in isolated mitochondria were unaffected by obesity. No indication of reduced content, investigated by quantification of the complexes of the respiratory chain, or altered regulation, examined by myometrial mRNA levels of genes related to mitochondrial biogenesis and inflammation, was detected. Yet we found increased myometrial triglyceride content in the obese group (2.39 ± 0.26 vs. 1.56 ± 0.20 mm, P = 0.024), while protein content and citrate synthase activity per gram wet weight myometrium were significantly lower in the obese (109.2 ± 7.2 vs. 139.4 ± 5.6 mg g^-1 , P = 0.002, and 24.8 ± 1.0 vs. 29.6 ± 1.4 U g^-1 wet wt, P = 0.008, respectively). These differences were substantiated by our histological findings where staining for nuclei, cytoplasm, glycogen and collagen supported the idea of a smaller muscle content in the myometrium in obese women. In conclusion no indication of myometrial mitochondrial dysfunction in the isolated state was found, but the observed increase of lipid content might play a role in the pathophysiological mechanisms behind labour dystocia in obese women.

Skeletal muscle autophagy and mitophagy in endurance-trained runners before and after a high-fat meal

Objective

We tested the hypothesis that skeletal muscle of endurance-trained male runners would exhibit elevated autophagy and mitophagy markers, which would be associated with greater metabolic flexibility following a high-fat meal (HFM).

Methods

Muscle biopsies were collected to determine differences in autophagy and mitophagy protein markers and metabolic flexibility under fasting conditions and 4 h following a HFM between endurance-trained male runners (n = 10) and sedentary, non-obese controls (n = 9).

Results

Maximal oxygen consumption (ml·kg·min⁻¹) was approximately 50% higher (p < 0.05) in endurance-trained runners compared with sedentary controls (65.8 ± 2.3 and 43.1 ± 3.4, respectively). Autophagy markers were similar between groups. Mitophagy and mitochondrial dynamics protein markers were significantly higher in skeletal muscle of endurance-trained runners compared with sedentary controls in the fasted state, although unaffected by the HFM. Skeletal muscle metabolic flexibility was similar between groups when fasted (p > 0.05), but increased in response to the HFM in endurance-trained athletes only (p < 0.005). Key mitophagy markers, phospho-Pink1^Thr257 and phospho-Parkin^S65 (r = 0.64, p < 0.005), and phospo-Parkin^Ser65 and phospho-Drp1^Ser616 (r = 0.70, p < 0.05) were correlated only within the endurance-trained group. Autophagy and mitophagy markers were not correlated with metabolic flexibility.

Conclusion

In summary, mitophagy may be enhanced in endurance-trained runners based on elevated markers of mitophagy and mitochondrial dynamics. The HFM did not alter autophagy or mitophagy in either group. The absence of a relationship between mitophagy markers and metabolic flexibility suggests that mitophagy is not a key determinant of metabolic flexibility in a healthy population, but further investigation is warranted.

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Basal autophagy is similar in skeletal muscle of endurance-trained and sedentary males.

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Trained and sedentary skeletal muscle autophagy is unaltered following high-fat meal.

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Mitophagy activity is greater in endurance-trained than sedentary skeletal muscle.

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Greater mitophagy is related to increased metabolic flexibility after high-fat meal.

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Trained and sedentary skeletal muscle mitophagy is unaltered following high-fat meal.

Bariatric surgery as a treatment for heart failure: review of the literature and potential mechanisms

Heart failure due to severe obesity is a complex disease due to multiple mechanisms, including increased body mass, inflammation, and impaired cardiac metabolism that is complicated by obesity-associated co-morbidities, such as type 2 diabetes and obstructive sleep apnea. Bariatric surgery significantly improves cardiac geometry, function, and symptoms related to obesity cardiomyopathy. There is a consistently positive impact of bariatric surgery on diastolic function with the potential to significantly improve systolic function as measured by ejection fraction in patients with advanced heart failure. For end-stage heart failure patients, including those requiring mechanical circulatory support who are ineligible for organ transplant due to morbid obesity, bariatric surgery has been successfully used for weight loss as a bridge to cardiac transplantation.

Microbe-mitochondrion crosstalk and health: An emerging paradigm

Human mitochondria are descendants of microbes and altered mitochondrial function has been implicated in processes ranging from ageing to diabetes. Recent work has highlighted the importance of gut microbial communities in human health and disease. While the spotlight has been on the influence of such communities on the human immune system and the extraction of calories from otherwise indigestible food, an important but less investigated link between the microbes and mitochondria remains unexplored. Microbial metabolites including short chain fatty acids as well as other molecules such as pyrroloquinoline quinone, fermentation gases, and modified fatty acids influence mitochondrial function. This review focuses on the known direct and indirect effects of microbes upon mitochondria and speculates regarding additional links for which there is circumstantial evidence. Overall, while there is compelling evidence that a microbiota-mitochondria link exists, explicit and holistic mechanistic studies are warranted to advance this nascent field.

The effect of very-low-calorie diet on mitochondrial dysfunction in subcutaneous adipose tissue and peripheral monocytes of obese subjects with type 2 diabetes mellitus

Mitochondrial dysfunction is a potentially important player in the development of insulin resistance and type 2 diabetes mellitus (T2DM). We investigated the changes of mRNA expression of genes encoding main enzymatic complexes of mitochondrial respiratory chain in subcutaneous adipose tissue (SCAT) and peripheral monocytes (PM) of 11 subjects with simple obesity (OB), 16 obese patients with T2DM and 17 healthy lean subjects (C) before and after very low-calorie diet (VLCD) using quantitative real time PCR. At baseline in SCAT, both T2DM and OB group had decreased mRNA expression of all investigated mitochondrial genes with the exception of 2 complex I (NDUFA 12) and complex IV (COX 4/1) enzymes in OB subjects. In contrast, in PM only the expression of complex I enzymes NDUFA 12 and MT-ND5 was reduced in both T2DM and OB subjects along with decreased expression of citrate synthase (CS) in T2DM group. Additionally, T2DM subjects showed reduced activity of pyruvate dehydrogenase and complex IV in peripheral blood elements. VLCD further decreased mRNA expression of CS and complex I (NT-ND5) and II (SDHA) enzymes in SCAT and complex IV (COX4/1) and ATP synthase in PM of T2DM group, while increasing the activity of complex IV in their peripheral blood elements. We conclude that impaired mitochondrial biogenesis and decreased activity of respiratory chain enzymatic complexes was present in SCAT and PM of obese and diabetic patients. VLCD improved metabolic parameters and ameliorated mitochondrial oxidative function in peripheral blood elements of T2DM subjects but had only minor and inconsistent effect on mitochondrial gene mRNA expression in SCAT and PM.

Does Bariatric Surgery Improve Obesity Associated Comorbid Conditions

Obesity is a constantly growing health problem which reduces quality of life and life expectancy. Bariatric surgery for obesity is taken into account when all other conservative treatment modalities have failed. Comparison of the multidisciplinary programs with bariatric surgery regarding to weight loss showed that substantial and durable weight reduction have been achieved only with bariatric surgical treatments. However, the benefits of weight loss following bariatric procedures are still debated regarding the pro-inflammatory and metabolic profile of obesity.

Metabolic Flexibility in Health and Disease

Metabolic flexibility is the ability to respond or adapt to conditional changes in metabolic demand. This broad concept has been propagated to explain insulin resistance and mechanisms governing fuel selection between glucose and fatty acids, highlighting the metabolic inflexibility of obesity and type 2 diabetes. In parallel, contemporary exercise physiology research has helped to identify potential mechanisms underlying altered fuel metabolism in obesity and diabetes. Advances in "omics" technologies have further stimulated additional basic and clinical-translational research to further interrogate mechanisms for improved metabolic flexibility in skeletal muscle and adipose tissue with the goal of preventing and treating metabolic disease.

Monocyte bioenergetic function is associated with body composition in virologically suppressed HIV-infected women

Women living with HIV may present with high levels of body fat that are associated with altered bioenergetic function. Excess body fat may therefore exacerbate the bioenergetic dysfunction observed with HIV infection. To determine if body fat is associated with bioenergetic function in HIV, we conducted a cross-sectional study of 42 women with HIV who were virologically suppressed on antiretroviral therapy. Body composition was determined via dual-energy x-ray absorptiometry. Oxygen consumption rate (OCR) of monocytes was sorted from peripheral blood mononuclear cells obtained from participants in the fasting state. Differences in bioenergetic function, as measured by OCR, was assessed using Kruskal-Wallis tests and Spearman correlations adjusted for age, race, and smoking status. Participants were 86% Black, 45.5 years old, 48% current smokers, and 57% were obese (body mass index ≥30). Nearly all women (93%) had >30% total fat mass, while 12% had >50% total fat mass. Elevated levels of total fat mass, trunk fat, and leg fat were inversely correlated with measures of bioenergetic health as evidenced by lower maximal and reserve capacity OCR, and Bioenergetic Health Index. Measures of extracellular acidification (ECAR) in the absence (basal) or maximal (with oligomycin) were positively correlated with measures of bioenergetics, except proton leak, and were negatively correlated with fat mass. Despite virological suppression, women with HIV present with extremely high levels of adiposity that correlate with impaired bioenergetic health. Without effective interventions, this syndemic of HIV infection and obesity will likely have devastating consequences for our patients, potentially mediated through altered mitochondrial and glycolytic function.

Relationship among physical activity, sedentary behaviors, and cardiometabolic risk factors during gastric bypass surgery-induced weight loss

BACKGROUND

The impact of daily physical activity (PA) on the cardiometabolic risk of bariatric surgery patients is not known.

OBJECTIVE

We examined the influence of physical activity and sedentary behavior on modifying cardiometabolic risk after Roux-en-Y gastric bypass (RYGB) surgery.

SETTING

University of Pittsburgh Medical Center and East Carolina University bariatric surgery centers.

METHODS

Data from 43 women and 7 men who completed testing at 1-3 months after RYGB surgery and again at 9 months postsurgery were analyzed. Outcomes measured included PA level (min/d), steps/d, sedentary time, and body composition. Insulin sensitivity was determined with an intravenous glucose tolerance test. Weight and blood lipid profiles also were obtained.

RESULTS

Patients reduced body mass index by a mean of -8.0±3.4 kg/m² (P<.001), increased moderate-to-vigorous PA by 17.0±47.0 min/d (P = .014), and decreased sedentary time (-47.9±101.0 min/d, P = .002). However, 24% of patients decreased overall PA (P<.001), and 39% increased sedentary behavior (P<.001). Changes in overall PA (rho = -.33, P = .006) and steps/d (rho = -.31, P = .0106) were related to weight loss. Insulin sensitivity was associated with light PA before (rho = .37, P<.001) and after (rho = .37, P = .015) intervention. Increasing overall PA also was related to higher levels of high-density lipoprotein cholesterol (rho = .33, P<.01). Decreasing sedentary time was related to decreased fat mass (rho = .35, P = .012) but not to other cardiometabolic risk factors.

CONCLUSIONS

The majority of patients increased PA (76%) and decreased sedentary time (61%) after RYGB surgery, but the amount of PA and sedentary time varied substantially. Higher PA, even at low intensity levels, was related to beneficial outcomes in body composition, insulin sensitivity, and high-density lipoprotein cholesterol.

A role for exercise after bariatric surgery?

Obesity predisposes an individual to develop numerous comorbidities, including type 2 diabetes, and represents a major healthcare issue in many countries worldwide. Bariatric surgery can be an effective treatment option, resulting in profound weight loss and improvements in metabolic health; however, not all patients achieve similar weight loss or metabolic improvements. Exercise is an excellent way to improve health, with well-characterized physiological and psychological benefits. In the present paper we review the evidence to determine whether there may be a role for exercise as a complementary adjunct therapy to bariatric surgery. Objectively measured physical activity data indicate that most patients who undergo bariatric surgery do not exercise enough to reap the health benefits of exercise. While there is a dearth of data on the effects of exercise on weight loss and weight loss maintenance after surgery, evidence from studies of caloric restriction and exercise suggest that similar adjunctive benefits may be extended to patients who perform exercise after bariatric surgery. Recent evidence from exercise interventions after bariatric surgery suggests that exercise may provide further improvements in metabolic health compared with surgery-induced weight loss alone. Additional randomized controlled exercise trials are now needed as the next step to more clearly define the potential for exercise to provide additional health benefits after bariatric surgery. This valuable evidence will inform clinical practice regarding much-needed guidelines for exercise after bariatric surgery.

Exercise and Weight Loss Improve Muscle Mitochondrial Respiration, Lipid Partitioning, and Insulin Sensitivity After Gastric Bypass Surgery

Both Roux-en-Y gastric bypass (RYGB) surgery and exercise can improve insulin sensitivity in individuals with severe obesity. However, the impact of RYGB with or without exercise on skeletal muscle mitochondria, intramyocellular lipids, and insulin sensitivity index (SI) is unknown. We conducted a randomized exercise trial in patients (n = 101) who underwent RYGB surgery and completed either a 6-month moderate exercise (EX) or a health education control (CON) intervention. SI was determined by intravenous glucose tolerance test. Mitochondrial respiration and intramyocellular triglyceride, sphingolipid, and diacylglycerol content were measured in vastus lateralis biopsy specimens. We found that EX provided additional improvements in SI and that only EX improved cardiorespiratory fitness, mitochondrial respiration and enzyme activities, and cardiolipin profile with no change in mitochondrial content. Muscle triglycerides were reduced in type I fibers in CON, and sphingolipids decreased in both groups, with EX showing a further reduction in a number of ceramide species. In conclusion, exercise superimposed on bariatric surgery-induced weight loss enhances mitochondrial respiration, induces cardiolipin remodeling, reduces specific sphingolipids, and provides additional improvements in insulin sensitivity.

Comprehensive assessment of physical functioning in bariatric surgery candidates compared with subjects without obesity

BACKGROUND

Obesity appears to be associated with reduced physical performance, but comprehensive assessments of physical functioning are lacking in subjects with severe obesity, in particular in comparison with subjects without obesity. This precludes an objective assessment of the degree of impairment.

OBJECTIVE

To compare motor skills and cardiopulmonary fitness between subjects with severe obesity (OB) (i.e., candidates for bariatric surgery) and control subjects without obesity (non-OB).

SETTING

Cantonal Hospital, Switzerland.

METHODS

Flexibility, movement speed, balance, maximal isometric strength, and cardiopulmonary fitness were tested in 45 OB (body mass index: 42.6±.9 kg/m(2); age: 35±1.7 years; 33 women) and 32 non-OB (body mass index: 23±.4 kg/m(2); age: 38.5±2.1 years; 25 women) subjects.

RESULTS

In comparison with the non-OB group, the OB group showed reduced shoulder flexibility (P<.001) but comparable hamstrings flexibility (P = .3). Speed-related tasks (i.e., timed up-and-go test and timed lying-to-standing test) indicated that the OB group was slower than the non-OB group (all P<.007). Strength-related tasks indicated a greater absolute back muscle and knee-extensor strength (all P<.002) in the OB group with no difference in knee-flexor strength (both P>.8). However, when related to weight, the OB group showed reduced maximal strength (all P<.002). Bicycle spiroergometry indicated that absolute oxygen consumption at peak exercise and at the anaerobic threshold did not differ between groups (both P>.06). Related to weight, however, values were lower in the OB than in the non-OB group (both P< .001).

CONCLUSION

Data indicate a differential pattern of functional impairment in bariatric surgery candidates compared with subjects without obesity. These findings might help to establish tailored intervention protocols to improve physical performance in such subjects.

Relationships between mitochondrial content and bioenergetics with obesity, body composition and fat distribution in healthy older adults

Background

Mitochondrial function declines with age; however, the relationship between adiposity and mitochondrial function among older adults is unclear. This study examined relationships between skeletal muscle mitochondrial content and electron transport chain complex 2 driven respiration with whole body and thigh composition, body fat distribution, and insulin sensitivity in older adults.

Methods

25 healthy, sedentary, weight-stable men (N = 13) and women (N = 12) >65 years of age, with a BMI range of 18-35 kg/m², participated in this study. Vastus lateralis biopsies were analyzed for citrate synthase (CS) activity and succinate mediated respiration of isolated mitochondria. Whole body and thigh composition were measured by DXA and CT. HOMA-IR was calculated using fasting glucose and insulin as an estimate of insulin sensitivity.

Results

Similar to reports in middle-aged adults, skeletal muscle CS activity was negatively correlated with BMI (R = −0.43) in our cohort of older adults. Higher total and thigh adiposity were correlated with lower CS activity independent of BMI (R = −0.50 and −0.71 respectively). Maximal complex 2 driven mitochondrial respiration was negatively correlated with lower body adiposity in males (R = −0.66). In this cohort of non-diabetic older adults, both HOMA-IR and insulin were positively correlated with CS activity when controlling for BMI (R = 0.57 and 0.66 respectively).

Conclusions

Adiposity and body composition are correlated with skeletal muscle mitochondrial content and electron transport chain function in healthy, sedentary, community dwelling, older adults. Specific relationships of mitochondrial bioenergetics with gender and insulin sensitivity are also apparent.

Trial registration

ClinicalTrials.gov identifier NCT01049698

Electronic supplementary material

The online version of this article (doi:10.1186/s40608-015-0070-4) contains supplementary material, which is available to authorized users.

Stimulatory Effects of Balanced Deep Sea Water on Mitochondrial Biogenesis and Function

The worldwide prevalence of metabolic diseases, including obesity and diabetes, is increasing. Mitochondrial dysfunction is recognized as a core feature of these diseases. Emerging evidence also suggests that defects in mitochondrial biogenesis, number, morphology, fusion, and fission, contribute to the development and progression of metabolic diseases. Our previous studies revealed that balanced deep-sea water (BDSW) has potential as a treatment for diabetes and obesity. In this study, we aimed to investigate the mechanism by which BDSW regulates diabetes and obesity by studying its effects on mitochondrial metabolism. To determine whether BDSW regulates mitochondrial biogenesis and function, we investigated its effects on mitochondrial DNA (mtDNA) content, mitochondrial enzyme activity, and the expression of transcription factors and mitochondria specific genes, as well as on the phosphorylation of signaling molecules associated with mitochondria biogenesis and its function in C₂C₁₂ myotubes. BDSW increased mitochondrial biogenesis in a time and dose-dependent manner. Quantitative real-time PCR revealed that BDSW enhances gene expression of PGC-1α, NRF1, and TFAM for mitochondrial transcription; MFN1/2 and DRP1 for mitochondrial fusion; OPA1 for mitochondrial fission; TOMM40 and TIMM44 for mitochondrial protein import; CPT-1α and MCAD for fatty acid oxidation; CYTC for oxidative phosphorylation. Upregulation of these genes was validated by increased mitochondria staining, CS activity, CytC oxidase activity, NAD⁺ to NADH ratio, and the phosphorylation of signaling molecules such as AMPK and SIRT1. Moreover, drinking BDSW remarkably improved mtDNA content in the muscles of HFD-induced obese mice. Taken together, these results suggest that the stimulatory effect of BDSW on mitochondrial biogenesis and function may provide further insights into the regulatory mechanism of BDSW-induced anti-diabetic and anti-obesity action.