Impaired Awareness of Hypoglycemia in Older Adults With Type 1 Diabetes: A Post Hoc Analysis of the WISDM Study

OBJECTIVE

Up to one-third of older adults with type 1 diabetes experience impaired awareness of hypoglycemia (IAH), yet the factors associated with IAH remain underexplored in older adults.

RESEARCH DESIGN AND METHODS

This post hoc analysis evaluated the clinical and glycemic correlates of IAH in adults ≥60 years old with type 1 diabetes in the WISDM study. IAH and normal awareness of hypoglycemia (NAH) were defined by a Clarke score of ≥4 or <4, respectively. Demographic, clinical, and glycemic metrics were compared in those with IAH and NAH at baseline and in whom IAH did or did not improve over 26 weeks, using descriptive statistics and a multiple logistic regression variable selection procedure.

RESULTS

Of the 199 participants (age 68.1 ± 5.7 years, 52% female), 30.6% had IAH. At baseline, participants with IAH had a longer diabetes duration and greater daytime hypoglycemia and glycemic variability, and more participants had nondetectable C-peptide levels than those with NAH. Logistic regression associated longer diabetes duration (odds ratio [OR] 1.03, 95% CI 1.01-1.05; P = 0.008) and greater daytime hypoglycemia (OR 1.31, 95% CI, 1.15-1.51; P < 0.0001) with a greater odds of IAH. A similar modeling procedure identified less daytime hypoglycemia (OR per additional percentage point 0.55, 95% CI 0.32-0.94; P = 0.029) and shorter diabetes duration (OR per additional year 0.96, 95% CI 0.91-1.004; P = 0.07) as predictors of restored awareness at 26 weeks, although the effect size for diabetes duration was not statistically significant.

CONCLUSIONS

In older adults with type 1 diabetes, longer diabetes duration and greater daytime hypoglycemia are drivers of IAH. Dedicated research can personalize IAH management.

Assessment of BRCA1 and BRCA2 Germline Variant Data From Patients With Breast Cancer in a Real-World Data Registry

PURPOSE

The emergence of large real-world clinical databases and tools to mine electronic medical records has allowed for an unprecedented look at large data sets with clinical and epidemiologic correlates. In clinical cancer genetics, real-world databases allow for the investigation of prevalence and effectiveness of prevention strategies and targeted treatments and for the identification of barriers to better outcomes. However, real-world data sets have inherent biases and problems (eg, selection bias, incomplete data, measurement error) that may hamper adequate analysis and affect statistical power.

METHODS

Here, we leverage a real-world clinical data set from a large health network for patients with breast cancer tested for variants in BRCA1 and BRCA2 (N = 12,423). We conducted data cleaning and harmonization, cross-referenced with publicly available databases, performed variant reassessment and functional assays, and used functional data to inform a variant's clinical significance applying American College of Medical Geneticists and the Association of Molecular Pathology guidelines.

RESULTS

In the cohort, White and Black patients were over-represented, whereas non-White Hispanic and Asian patients were under-represented. Incorrect or missing variant designations were the most significant contributor to data loss. While manual curation corrected many incorrect designations, a sizable fraction of patient carriers remained with incorrect or missing variant designations. Despite the large number of patients with clinical significance not reported, original reported clinical significance assessments were accurate. Reassessment of variants in which clinical significance was not reported led to a marked improvement in data quality.

CONCLUSION

We identify the most common issues with BRCA1 and BRCA2 testing data entry and suggest approaches to minimize data loss and keep interpretation of clinical significance of variants up to date.

Development and initial validation of a video-based peroral endoscopic myotomy assessment tool

BACKGROUND AND AIMS

Video analysis has emerged as a potential strategy for performance assessment and improvement. We aimed to develop a video-based skill assessment tool for peroral endoscopic myotomy (POEM).

METHODS

POEM was deconstructed into basic procedural components through video analysis by an expert panel. A modified Delphi approach and 2 validation exercises were conducted to refine the POEM assessment tool (POEMAT). Twelve assessors used the final POEMAT version to grade 10 videos. Fully crossed generalizability (G) studies investigated the contributions of assessors, endoscopists' performance, and technical elements to reliability. G coefficients below .5 were considered unreliable, between .5 and .7 as modestly reliable, and above .7 as indicative of satisfactory reliability.

RESULTS

After task deconstruction, discussions, and the modified Delphi process, the final POEMAT comprised 9 technical elements. G analysis showed low variance for endoscopist performance (.8%-24.9%) and high interrater variability (range, 63.2%-90.1%). The G score was moderately reliable (≥.60) for "submucosal tunneling" and "myotomy" and satisfactorily reliable (≥.70) for "active hemostasis" and "mucosal closure."

CONCLUSIONS

We developed and established initial content and response process validity evidence for the POEMAT. Future steps include appraisal of the tool using a wider range of POEM videos to establish and improve the discriminative validity of this tool.

Effects of resveratrol on in vitro circadian clock gene expression in young and older human adipose-derived progenitor cells

Observational studies in preclinical models demonstrate age-related declines in circadian functions. We hypothesized that age would be associated with declines in function of cell-autonomous circadian clocks in human tissue. Accordingly, we cultured adipose progenitor cells (APCs) from previously collected white-adipose tissue biopsies from abdominal subcutaneous depots of young (Age: 23.4 ± 2.1 yrs) vs. older female participants (Age: 70.6 ± 5.9 yrs). Using an in vitro model, we compared rhythmic gene expression profiles of core clock components, as an indicator of circadian oscillatory function. We observed consistent circadian rhythmicity of core clock components in young and older-APCs. Expression analysis showed increased levels of some components in older-APCs (CLOCK, CRY1, NR1D1) vs. young. We also investigated resveratrol (RSV), a well-known longevity-enhancing effector, for its effects on rhythmic clock gene expression profiles. We found that RSV resulted in gained rhythmicity of some components (CLOCK and CRY), loss of rhythmicity in others (PER2, CRY2), and altered some rhythmic parameters (NR1D1 and NR1D2), consistent in young and older-APCs. The observation of detectable circadian rhythmicity retained in vitro suggests that the oscillatory function of the cell-autonomous core clock in APCs is preserved at this stage of the aging process. RSV impacts core clock gene expression in APCs, implicating its potential as a therapeutic agent for longevity by targeting the core clock.

Routine versus no assessment of gastric residual volumes in preterm infants receiving enteral feeding via intermittent feeding tubes: a randomized controlled trial

OBJECTIVE

To evaluate whether eliminating routine gastric residual volume (GRV) assessments would lead to quicker attainment of full feeding volumes in preterm infants.

STUDY DESIGN

This is a prospective randomized controlled trial of infants ≤32 weeks gestation and birthweight ≤1250 g admitted to a tertiary care NICU. Infants were randomized to assess or not assess GRV before enteral tube feedings. The primary outcome was time to attain full enteral feeding volume defined as 120 ml/kg/day. The Wilcoxon rank sum test was used to compare the days to reach full enteral feeds between the two groups.

RESULTS

80 infants were randomized, 39 to the GRV assessing and 41 to the No-GRV assessing group. A predetermined interim analysis at 50% enrollment showed no difference in primary outcome and the study was stopped as recommended by the Data Safety Monitoring Committee. There was no significant difference in median days to reach full enteral feeds between the two groups [GRV assessment: 12d (5) vs. No-GRV assessment:13d (9)]. There was no mortality in either group, one infant in each group developed necrotizing enterocolitis stage 2 or greater.

CONCLUSION

Eliminating the practice of gastric residual volume assessment before feeding did not result in shorter time to attain full feeding.

Host-diet-gut microbiome interactions influence human energy balance: a randomized clinical trial

The gut microbiome is emerging as a key modulator of human energy balance. Prior studies in humans lacked the environmental and dietary controls and precision required to quantitatively evaluate the contributions of the gut microbiome. Using a Microbiome Enhancer Diet (MBD) designed to deliver more dietary substrates to the colon and therefore modulate the gut microbiome, we quantified microbial and host contributions to human energy balance in a controlled feeding study with a randomized crossover design in young, healthy, weight stable males and females (NCT02939703). In a metabolic ward where the environment was strictly controlled, we measured energy intake, energy expenditure, and energy output (fecal and urinary). The primary endpoint was the within-participant difference in host metabolizable energy between experimental conditions [Control, Western Diet (WD) vs. MBD]. The secondary endpoints were enteroendocrine hormones, hunger/satiety, and food intake. Here we show that, compared to the WD, the MBD leads to an additional 116 ± 56 kcals (P < 0.0001) lost in feces daily and thus, lower metabolizable energy for the host (89.5 ± 0.73%; range 84.2-96.1% on the MBD vs. 95.4 ± 0.21%; range 94.1-97.0% on the WD; P < 0.0001) without changes in energy expenditure, hunger/satiety or food intake (P > 0.05). Microbial 16S rRNA gene copy number (a surrogate of biomass) increases (P < 0.0001), beta-diversity changes (whole genome shotgun sequencing; P = 0.02), and fermentation products increase (P < 0.01) on an MBD as compared to a WD along with significant changes in the host enteroendocrine system (P < 0.0001). The substantial interindividual variability in metabolizable energy on the MBD is explained in part by fecal SCFAs and biomass. Our results reveal the complex host-diet-microbiome interplay that modulates energy balance.

Antibodies against Periodontal Microorganisms and Cognition in Older Adults

INTRODUCTION

Markers of poor oral health are associated with impaired cognition and higher risk of Alzheimer disease (AD) and thus may help predict AD.

OBJECTIVES

The aim of this study was to evaluate the cross-sectional association between empirically derived groups of 19 IgG antibodies against periodontal microorganisms and cognition in middle-aged and older adults.

METHODS

The study population consisted of participants of the third National Health and Nutrition Examination Survey (NHANES III) (1988 to 1994), who were 60 y and older, among whom cognition and IgG antibodies against 19 periodontal microorganisms were measured (N = 5,162).

RESULTS

In multivariable quantile regression analyses, the Orange-Red (Prevotella melaninogenica, Prevotella intermedia, Prevotella nigrescens, Porphyromonas gingivalis) and Yellow-Orange (Staphylococcus intermedius, Streptococcus oralis, Streptococcus mutans, Fusobacterium nucleatum, Peptostreptococcus micros, Capnocytophaga ochracea) cluster scores were negatively associated with cognition. A 1-unit higher cluster score for the Orange-Red cluster was associated on average with a lower cognitive score (β for 30th quantile = -0.2640; 95% confidence interval [CI], -0.3431 to -0.1848). Similarly, a 1-unit higher score for the Yellow-Orange cluster was associated with a lower cognitive score (β for 30th quantile = -0.2445; 95% CI, -0.3517 to -0.1372).

CONCLUSION

Groups of IgG antibodies against periodontal microorganisms were associated with lower cognition among free living adults 60 years and older, who were previously undiagnosed with cognitive impairment. Though poor oral health precedes the development of dementia and AD, oral health information is currently not used, to our knowledge, to predict dementia or AD risk. Combining our findings with current algorithms may improve risk prediction for dementia and AD.

KNOWLEDGE TRANSLATION STATEMENT

IgG antibodies against periodontal microorganisms were associated with lower cognition among adults 60 years and older previously undiagnosed with cognitive impairment. Periodontal disease may predict cognition among older adults.

Exercise and ageing impact the kynurenine/tryptophan pathway and acylcarnitine metabolite pools in skeletal muscle of older adults

Exercise-induced perturbation of skeletal muscle metabolites is a probable mediator of long-term health benefits in older adults. Although specific metabolites have been identified to be impacted by age, physical activity and exercise, the depth of coverage of the muscle metabolome is still limited. Here, we investigated resting and exercise-induced metabolite distribution in muscle from well-phenotyped older adults who were active or sedentary, and a group of active young adults. Percutaneous biopsies of the vastus lateralis were obtained before, immediately after and 3 h following a bout of endurance cycling. Metabolite profile in muscle biopsies was determined by tandem mass spectrometry. Mitochondrial energetics in permeabilized fibre bundles was assessed by high resolution respirometry and fibre type proportion was assessed by immunohistology. We found that metabolites of the kynurenine/tryptophan pathway were impacted by age and activity. Specifically, kynurenine was elevated in muscle from older adults, whereas downstream metabolites of kynurenine (kynurenic acid and NAD⁺ ) were elevated in muscle from active adults and associated with cardiorespiratory fitness and muscle oxidative capacity. Acylcarnitines, a potential marker of impaired metabolic health, were elevated in muscle from physically active participants. Surprisingly, despite baseline group difference, acute exercise-induced alterations in whole-body substrate utilization, as well as muscle acylcarnitines and ketone bodies, were remarkably similar between groups. Our data identified novel muscle metabolite signatures that associate with the healthy ageing phenotype provoked by physical activity and reveal that the metabolic responsiveness of muscle to acute endurance exercise is retained [NB]:AUTHOR: Please ensure that the appropriate material has been provide for Table S2, as well as for Figures S1 to S7, as also cited in the text with age regardless of activity levels. KEY POINTS: Kynurenine/tryptophan pathway metabolites were impacted by age and physical activity in human muscle, with kynurenine elevated in older muscle, whereas downstream products kynurenic acid and NAD⁺ were elevated in exercise-trained muscle regardless of age. Acylcarnitines, a marker of impaired metabolic health when heightened in circulation, were elevated in exercise-trained muscle of young and older adults, suggesting that muscle act as a metabolic sink to reduce the circulating acylcarnitines observed with unhealthy ageing. Despite the phenotypic differences, the exercise-induced response of various muscle metabolite pools, including acylcarnitine and ketone bodies, was similar amongst the groups, suggesting that older adults can achieve the metabolic benefits of exercise seen in young counterparts.

Reprogramming the Human Gut Microbiome Reduces Dietary Energy Harvest

The gut microbiome is emerging as a key modulator of host energy balance1. We conducted a quantitative bioenergetics study aimed at understanding microbial and host factors contributing to energy balance. We used a Microbiome Enhancer Diet (MBD) to reprogram the gut microbiome by delivering more dietary substrates to the colon and randomized healthy participants into a within-subject crossover study with a Western Diet (WD) as a comparator. In a metabolic ward where the environment was strictly controlled, we measured energy intake, energy expenditure, and energy output (fecal, urinary, and methane)2. The primary endpoint was the within-participant difference in host metabolizable energy between experimental conditions. The MBD led to an additional 116 ± 56 kcals lost in feces daily and thus, lower metabolizable energy for the host by channeling more energy to the colon and microbes. The MBD drove significant shifts in microbial biomass, community structure, and fermentation, with parallel alterations to the host enteroendocrine system and without altering appetite or energy expenditure. Host metabolizable energy on the MBD had quantitatively significant interindividual variability, which was associated with differences in the composition of the gut microbiota experimentally and colonic transit time and short-chain fatty acid absorption in silico. Our results provide key insights into how a diet designed to optimize the gut microbiome lowers host metabolizable energy in healthy humans.

Evaluation of different pharmacokinetically guided IV busulfan exposure ranges on adult patient outcomes after hematopoietic stem cell transplantation

Conditioning intensity contributes significantly to outcomes in allogeneic hematopoietic stem cell transplantation (allo-HSCT). We evaluated two myeloablative conditioning dosing ranges of intravenous (IV) busulfan (Bu) in combination with fludarabine in 70 patients. In 2015, our practice changed to target busulfan area under the curve (AUC) of ≥ 19.7 mg*h/L. We assessed responses in patients receiving busulfan AUCs of < 19.7 mg*h/L (Low-Bu) and ≥ 19.7 mg*h/L (High-Bu). At 18-month median follow-up, no differences in overall survival (OS) and relapse-free survival (RFS) were found between Low-Bu and High-Bu groups (p = 0.35 and p = 0.29, respectively). Relapses occurred in 25.7% of patients. No differences in median time to relapse were noted. Minimal residual disease (MRD)-positive patients had a shorter median OS and RFS than MRD-negative patients. No differences were found in OS and RFS between Low-Bu and High-Bu groups in MRD-positive patients (p = 0.86 and p = 0.83, respectively), or MRD-negative patients (p = 0.56 and p = 0.38, respectively). Non-relapsed mortality (NRM) at 100 days was 3.4% vs. 4.1% in the Low-Bu vs. High-Bu groups. There were no significant differences in the incidence of acute-graft-versus-host disease (aGVHD) (71.4% vs. 63.4%) or chronic GVHD (cGVHD) (48.3% vs. 43.9%) between the groups. The cumulative incidence of grades III-IV aGVHD was 24.1% in Low-Bu group and 22.4% in High-Bu group. In conclusion, targeting a busulfan AUC of > 19.7 mg*h/L with fludarabine does not appear to add an advantage in OS and RFS.

[Effects of cinepazide maleate injection on blood pressure in patients with acute ischemic stroke and hypertension]

Objective: To investigate the blood pressure change in patients with acute ischemic stroke (AIS) and hypertension treated with cinepazide maleate injection. Methods: This was a subgroup analysis of post-marketing clinical confirmation study of cinepazide maleate injection for acute ischemic stroke: a randomized, double-blinded, multicenter, placebo-parallel controlled trial, which conducted in China from August 2016 to February 2019. Eligible patients fulfilled the inclusive criteria of acute anterior circulation ischemic stroke with National Institutes of Health Stroke Scale (NIHSS) scores of 7-25. The primary endpoints were mean blood pressure of AIS patients treated with cinepazide maleate or control, which were assessed during the treatment period (14 days), and the proportion of the patients with normal blood pressure was analyzed after the treatment period. Furthermore, a subgroup analysis was performed to investigate a possible effect of the history of hypertension on outcomes. Results: This analysis included 809 patients with hypertension. There was no significant difference in patients blood pressure and the proportion of patients with normal blood pressure (60.5% vs. 59.0%,P>0.05) between cinepazide maleate group and control group. Conclusion: Administration of cinepazide maleate injection does not affect the management of clinical blood pressure in patients with AIS.

Aerobic training increases mitochondrial respiratory capacity in human skeletal muscle stem cells from sedentary individuals

The impact of aerobic training on human skeletal muscle cell (HSkMC) mitochondrial metabolism is a significant research gap, critical to understanding the mechanisms by which exercise augments skeletal muscle metabolism. We therefore assessed mitochondrial content and capacity in fully differentiated CD56+ HSkMCs from lean active (LA) and sedentary individuals with obesity (OS) at baseline, as well as lean/overweight sedentary individuals (LOS) at baseline and following an 18-day aerobic training intervention. Participants had in vivo skeletal muscle PCr recovery rate by 31P-MRS (mitochondrial oxidative kinetics) and cardiorespiratory fitness (VO2max) assessed at baseline. Biopsies of the vastus lateralis were performed for the isolation of skeletal muscle stem cells. LOS individuals repeated all assessments post-training. HSkMCs were evaluated for mitochondrial respiratory capacity by high resolution respirometry. Data were normalized to two indices of mitochondrial content (CS activity and OXPHOS protein expression) and a marker of total cell count (quantity of DNA).LA individuals had significantly higher VO2max than OS and LOS-Pre training; however, no differences were observed in skeletal muscle mitochondrial capacity, nor in carbohydrate- or fatty acid-supported HSkMC respiratory capacity. Aerobic training robustly increased in vivo skeletal muscle mitochondrial capacity of LOS individuals, as well as carbohydrate-supported HSkMC respiratory capacity. Indices of mitochondrial content and total cell count were similar among the groups and did not change with aerobic training.Our findings demonstrate that bioenergetic changes induced with aerobic training in skeletal muscle in vivo are retained in HSkMCs in vitro without impacting mitochondrial content, suggesting that training improves intrinsic skeletal muscle mitochondrial capacity.

The Ile191Val Variant of the TAS1R2 Subunit of Sweet Taste Receptors Is Associated With Reduced HbA1c in a Human Cohort With Variable Levels of Glucose Homeostasis

The Ile191Val variant of the TAS1R2 gene of sweet taste receptors causes a partial loss-of-function and is associated with reduced glucose excursions in a healthy lean cohort. However, it is unclear whether this polymorphism contributes to the regulation of glucose homeostasis in metabolically unhealthy individuals. Thus, we used participants with variable glycemic profiles and obesity to assess the effects of the TAS1R2-Ile191Val variant. We found that the Val minor allele carriers had lower HbA1c at all levels of fasting glucose and glucose tolerance. These effects were not due to differences in beta-cell function or insulin sensitivity assessed with a frequently sampled intravenous glucose tolerance test. This study extends our previous findings and provides further evidence that sweet taste receptor function may contribute to glucose regulation in humans.

Weight Loss and Exercise Differentially Affect Insulin Sensitivity, Body Composition, Cardiorespiratory Fitness, and Muscle Strength in Older Adults With Obesity: A Randomized Controlled Trial

BACKGROUND

Aging-related disease risk is exacerbated by obesity and physical inactivity. It is unclear how weight loss and increased activity improve risk in older adults. We aimed to determine the effects of diet-induced weight loss with and without exercise on insulin sensitivity, VO2peak, body composition, and physical function in older obese adults.

METHODS

Physically inactive older (68.6 ± 4.5 years) obese (body mass index 37.4 ± 4.9 kg/m2) adults were randomized to health education control (HEC; n = 25); diet-induced weight loss (WL; n = 31); or weight loss and exercise (WLEX; n = 28) for 6 months. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp, body composition by dual-energy X-ray absorptiometry and MRI, strength by isokinetic dynamometry, and VO2peak by graded exercise test.

RESULTS

WLEX improved (p < .05) peripheral insulin sensitivity (+75 ± 103%) versus HEC (+12 ± 67%); WL (+36 ± 47%) versus HEC did not reach statistical significance. WLEX increased VO2peak (+7 ± 12%) versus WL (-2 ± 24%) and prevented reductions in strength and lean mass induced by WL (p < .05). WLEX decreased abdominal adipose tissue (-16 ± 9%) versus HEC (-3 ± 8%) and intermuscular adipose tissue (-15 ± 13%) versus both HEC (+9 ± 15%) and WL (+2 ± 11%; p < .01).

CONCLUSIONS

Exercise with weight loss improved insulin sensitivity and VO2peak, decreased ectopic fat, and preserved lean mass and strength. Weight loss alone decreased lean mass and strength. Older adults intending to lose weight should perform regular exercise to promote cardiometabolic and functional benefits, which may not occur with calorie restriction-induced weight loss alone.

Skeletal muscle transcriptome response to a bout of endurance exercise in physically active and sedentary older adults

Age-related declines in cardiorespiratory fitness and physical function are mitigated by regular endurance exercise in older adults. This may be due, in part, to changes in the transcriptional program of skeletal muscle following repeated bouts of exercise. However, the impact of chronic exercise training on the transcriptional response to an acute bout of endurance exercise has not been clearly determined. Here, we characterized baseline differences in muscle transcriptome and exercise-induced response in older adults who were active/endurance trained or sedentary. RNA-sequencing was performed on vastus lateralis biopsy specimens obtained before, immediately after, and 3 h following a bout of endurance exercise (40 min of cycling at 60%-70% of heart rate reserve). Using a recently developed bioinformatics approach, we found that transcript signatures related to type I myofibers, mitochondria, and endothelial cells were higher in active/endurance-trained adults and were associated with key phenotypic features including V̇o_2peak, ATP_max, and muscle fiber proportion. Immune cell signatures were elevated in the sedentary group and linked to visceral and intermuscular adipose tissue mass. Following acute exercise, we observed distinct temporal transcriptional signatures that were largely similar among groups. Enrichment analysis revealed catabolic processes were uniquely enriched in the sedentary group at the 3-h postexercise timepoint. In summary, this study revealed key transcriptional signatures that distinguished active and sedentary adults, which were associated with difference in oxidative capacity and depot-specific adiposity. The acute response signatures were consistent with beneficial effects of endurance exercise to improve muscle health in older adults irrespective of exercise history and adiposity.NEW & NOTEWORTHY Muscle transcript signatures associated with oxidative capacity and immune cells underlie important phenotypic and clinical characteristics of older adults who are endurance trained or sedentary. Despite divergent phenotypes, the temporal transcriptional signatures in response to an acute bout of endurance exercise were largely similar among groups. These data provide new insight into the transcriptional programs of aging muscle and the beneficial effects of endurance exercise to promote healthy aging in older adults.

Evaluating "The REST of your Life," a workplace health program to improve employee sleep, health, energy, and productivity

Purpose Sleep is critical for employee health, well-being, and productivity. Our purpose is to evaluate a sleep-focused interactive workplace health promotion program. Design We evaluate sleep and mental health before and after exposure to the program using a pre/post quasi-experimental pilot study design with surveys administered at baseline and 1-, 6-, and 12-months post-exposure (Phase 1). We design program evaluation surveys for dissemination when the program is offered broadly to hospital employees (Phase 2). Setting The study was conducted at a large teaching hospital in the Southeast U.S. in 2016. Subjects Subjects were full-time hospital employees. Intervention The program was presented to subjects in one four-hour interactive session. Measures In Phase 1 (n=55), surveys included the validated Apnea Risk Evaluation System (ARES), Dysfunctional Beliefs About Sleep (DBAS), Generalized Anxiety Disorder-7 (GAD-7), Pittsburgh Sleep Quality Index (PSQI), and Patient Health Questionnaire (PHQ-9). Phase 2 (n=3,935) utilized program evaluation surveys. Analysis We compare survey responses between pre- and post-program using ANOVA with post-hoc tests. Results Statistically significant improvement in all sleep and mental health domains was demonstrated. In Phase 2, 81.9% reported "strongly agree" to willingness to recommend the program to co-workers. Conclusion We demonstrate improvement in employee sleep and mental health after exposure to a novel workplace health promotion program to improve sleep.

[Epidemiology of chronic cough in China: current status and future perspective]

Chronic cough is one of the most common major complaints in medical outpatient. Chronic cough not only seriously affects quality of personal life, but also burdens public health. Large-scale and high-quality epidemiological study on chronic cough has not been carried out in China, and relevant reviews are also lacking. Therefore, based on the studies concerning epidemiology of chronic cough in China, we reviewed the prevalence, risk factors, etiology, quality of life and economic burden. In addition, future perspectives and reasonable suggestions for the development of epidemiology of chronic cough were also proposed.

[Chronic cough in China: progress and perspectives]

Great progress has been made in regard of mechanism, etiological diagnosis and treatment of chronic cough since the beginning of the 20th century, and Chinese guidelines of diagnosis, management of cough was developed. Moreover, Chinese experts also participated in the formulation of international cough guidelines. Through the promotion of the guidelines, the level of diagnosis and treatment of chronic cough has been significantly improved in China. In the future, we should strengthen the studies on the epidemiology of chronic cough, the central regulation of chronic cough, and the treatment of refractory chronic cough, and promote the cough guidelines in primary community hospitals.

The value of soluble suppression of tumorigenesis-2 (sST2) in the maintenance of hemodialysis patients with heart failure

BACKGROUND

Patients with end-stage renal disease are prone to develop heart failure (HF). The N-terminal pro-brain natriuretic peptide (NT-proBNP, BNP) is regarded as the gold standard for diagnosing HF. However, its prognostic sensitivity in patients with end-stage renal disease is sub-optimal. Soluble suppression of tumorigenesis-2 (sST2) has been well studied in HF but rarely in patients with maintenance hemodialysis (MHD). This study aimed to evaluate the value of sST2 in predicting HF in MHD patients.

METHODS

Twenty-three patients with New York Heart Association (NYHA) class III-IV were included in the HF group and 88 NYHA class I-II patients in the non-heart failure (NHF) group. sST2 and laboratory indexes were compared between the two groups.

RESULTS

The HF group, compared with the NHF group, presented with higher sST2, more advanced age, higher incidence of coronary heart disease (CHD), left ventricle end-diastolic diameter (LVEDD), and pulmonary artery pressure (PAP), and unchanged parathyroid hormone (iPTH). The HF group also had lower ejection fraction (EF), uric acid, inorganic phosphorus, 25-OH VitD3, and serum albumin. Multivariate logistic regression indicated that age, BNP, and sST2 were independent risk factors of HF in MHD patients. Spearman analysis defined that sST2 was positively correlated with PAP (r =0.283, p =0.003) and C-reactive protein (r =0.354, p <0.001); and negatively correlated with sex (r =-0.255, p =0.007), albumin (r =-0.366, p <0.001), uric acid (r =-0.213, p =0.025), 25-OH VitD3 (r =-0.216, p =0.04), calcium (r =-0.219, p =0.021), and inorganic phosphorus (r =-0.256, p =0.007). Receiver operating characteristic curve analysis determined a positive association between BNP and sST2 (r =0.373, p <0.001), with the area under the curve (AUC) of BNP being 0.822 (sensitivity: 0.783, specificity: 0.830) and the AUC of sST2 being 0.841 (sensitivity: 0.913, specificity: 0.761). The AUC of sST2 was 0.841, and the cut-value was 42.840 (sensitivity: 0.913, specificity: 0.761).

CONCLUSION

sST2 can predict HF in MHD patients and facilitate early diagnosis and prevention of HF in MHD patients. HIPPOKRATIA 2022, 26 (1):19-24.

National Resident Matching Program Rank Order and Performance in an Internal Medicine Residency

OBJECTIVES

Prospective first-year house staff and residency program leaders spend substantial time, effort, and expense preparing a rank order list for the National Resident Matching Program (NRMP). Previous studies have mostly shown minimal or no relation between rank order and subsequent resident performance, raising questions about the value of this process. Furthermore, no previous studies have been done with Internal Medicine residencies. As such, the purpose of this study was to compare NRMP rank order to multiple objective outcomes of an Internal Medicine residency.

METHODS

A retrospective cohort of Internal Medicine residents from five consecutive graduating classes, trained between July 1, 2013 and July 31, 2020, were evaluated for five objective outcomes: Accreditation Council for Graduate Medical Education (ACGME) milestones, faculty rankings of quality, National In-Training Examination scores, chief resident attainment, and fellowship attainment. Outcomes were analyzed in relation to eight potential predictors: NRMP rank, medical school type and grades, immigration status, added qualifications, sex, age and US Medical Licensing Examination (USMLE) scores, using univariate and multivariate analyses.

RESULTS

From a cohort of 61 residents, 56 were eligible. All eligible residents' data were included, for a participation rate of 100% (56 of 56). There were no statistically significant univariate or multivariate predictors for the endpoint of fellowship attainment. Higher USMLE scores were predictive of chief resident status in univariate analysis only. NRMP rank was significantly correlated with ACGME milestones in the univariate analysis. The multivariate analysis revealed that higher USMLE score was statistically significantly predictive of more favorable milestones, faculty ranking, and National In-Training Examination score.

CONCLUSIONS

Higher USMLE score was statistically significantly associated with multiple favorable objective residency outcomes in an Internal Medicine residency. A better NRMP rank was correlated with favorable ACGME milestones in univariate analysis, but USMLE score emerged as the strongest predictor in multivariate analysis.

The Ile191Val is a partial loss-of-function variant of the TAS1R2 sweet-taste receptor and is associated with reduced glucose excursions in humans

OBJECTIVE

Sweet taste receptors (STR) are expressed in the gut and other extra-oral tissues, suggesting that STR-mediated nutrient sensing may contribute to human physiology beyond taste. A common variant (Ile191Val) in the TAS1R2 gene of STR is associated with nutritional and metabolic outcomes independent of changes in taste perception. It is unclear whether this polymorphism directly alters STR function and how it may contribute to metabolic regulation.

METHODS

We implemented a combination of in vitro biochemical approaches to decipher the effects of TAS1R2 polymorphism on STR function. Then, as proof-of-concept, we assessed its effects on glucose homeostasis in apparently healthy lean participants.

RESULTS

The Ile191Val variant causes a partial loss of function of TAS1R2 through reduced receptor availability in the plasma membrane. Val minor allele carriers have reduced glucose excursions during an OGTT, mirroring effects previously seen in mice with genetic loss of function of TAS1R2. These effects were not due to differences in beta-cell function or insulin sensitivity.

CONCLUSIONS

Our pilot studies on a common TAS1R2 polymorphism suggest that STR sensory function in peripheral tissues, such as the intestine, may contribute to the regulation of metabolic control in humans.

An improvement in skeletal muscle mitochondrial capacity with short-term aerobic training is associated with changes in Tribbles 1 expression

Exercise training and physical activity are known to be associated with high mitochondrial content and oxidative capacity in skeletal muscle. Metabolic diseases including obesity and insulin resistance are associated with low mitochondrial capacity in skeletal muscle. Certain transcriptional factors such as PGC-1α are known to mediate the exercise response; however, the precise molecular mechanisms involved in the adaptation to exercise are not completely understood. We performed multiple measurements of mitochondrial capacity both in vivo and ex vivo in lean or overweight individuals before and after an 18-day aerobic exercise training regimen. These results were compared to lean, active individuals. Aerobic training in these individuals resulted in a marked increase in mitochondrial oxidative respiratory capacity without an appreciable increase in mitochondrial content. These adaptations were associated with robust transcriptome changes. This work also identifies the Tribbles pseudokinase 1, TRIB1, as a potential mediator of the exercise response in human skeletal muscle.

Metabolic adaptation characterizes short-term resistance to weight loss induced by a low-calorie diet in overweight/obese individuals

BACKGROUND

Low-calorie diet (LCD)-induced weight loss demonstrates response heterogeneity. Physiologically, a decrease in energy expenditure lower than what is predicted based on body composition (metabolic adaptation) and/or an impaired capacity to increase fat oxidation may hinder weight loss. Understanding the metabolic components that characterize weight loss success is important for optimizing weight loss strategies.

OBJECTIVES

We tested the hypothesis that overweight/obese individuals who had lower than expected weight loss in response to a 28-d LCD would be characterized by 1) impaired fat oxidation and 2) whole-body metabolic adaptation. We also characterized the molecular mechanisms associated with weight loss success/failure.

METHODS

This was a retrospective comparison of participants who met their predicted weight loss targets [overweight/obese diet sensitive (ODS), n = 23, females = 21, males = 2] and those that did not [overweight/obese diet resistant (ODR), n = 14, females = 12, males = 2] after a 28-d LCD (900-1000 kcal/d). We used whole-body (energy expenditure and fat oxidation) and tissue-specific measurements (metabolic proteins in skeletal muscle, gene expression in adipose tissue, and metabolites in serum) to detect metabolic properties and biomarkers associated with weight loss success.

RESULTS

The ODR group had greater mean ± SD metabolic adaptation (-175 ± 149 kcal/d; +119%) than the ODS group (-80 ± 108 kcal/d) after the LCD (P = 0.030). Mean ± SD fat oxidation increased similarly for both groups from baseline (0.0701 ± 0.0206 g/min) to day 28 (0.0869 ± 0.0269 g/min; P < 0.001). A principal component analysis factor comprised of serum 3-hydroxybutyric acid, citrate, leucine/isoleucine, acetyl-carnitine, and 3-hydroxylbutyrlcarnitine was associated with weight loss success at day 28 (std. β = 0.674, R2 = 0.479, P < 0.001).

CONCLUSIONS

Individuals who achieved predicted weight loss targets after a 28-d LCD were characterized by reduced metabolic adaptation. Accumulation of metabolites associated with acetyl-CoA excess and enhanced ketogenesis was identified in the ODS group.This trial was registered at clinicaltrials.gov as NCT01616082.

Prolonged Glucagon Infusion Does Not Affect Energy Expenditure in Individuals with Overweight/Obesity: A Randomized Trial

OBJECTIVE

The aim of this study was to determine the effects of prolonged (72 hours) glucagon administration at a low dose (LD) (12.5 ng/kg/min) and high dose (HD) (25 ng/kg/min) on energy expenditure (EE) in healthy individuals with overweight or obesity.

METHODS

Thirty-one healthy participants with overweight or obesity (BMI of 27-45 kg/m² , 26-55 years old, 23 females) were randomized into LD, HD, or placebo groups and underwent 72-hour intravenous infusion of glucagon. Whole-room calorimetry was used to assess EE and substrate use during five overnight stays (2 days at baseline, 3 days of infusion) and during two 24-hour stays (baseline vs. day 3). Blood was sampled at regular intervals throughout the inpatient stay and analyzed for glucagon and biomarkers of metabolism.

RESULTS

HD infusion elevated plasma glucagon levels compared with the placebo and LD infusion (P < 0.001). Sleeping, basal, and 24-hour EE was not significantly different among groups at any time point. Those receiving HD had significantly higher basal fat oxidation (Fat Ox) at days 2 and 3 than those receiving the placebo (P < 0.05); however, no differences in 24-hour Fat Ox were observed among groups (baseline vs. day 3).

CONCLUSIONS

An HD plasma glucagon infusion over 72 hours does not increase any aspects of EE in healthy individuals with overweight or obesity.

Reduced long noncoding RNA PGM5-AS1 facilitated proliferation and invasion of colorectal cancer through sponging miR-100-5p

OBJECTIVE

We aimed at investigating the expression of Long non-coding RNA (LncRNA) PGM5-AS1 and its facilitating effects on proliferation and invasion of colorectal cancer by sponging miR-100-5p.

PATIENTS AND METHODS

qRT-PCR was performed to detect the expressions of PGM5-AS1 and SMAD4 in human colorectal cancer tissues and cells. CCK-8 assay was performed to evaluate the SW403 cells proliferation and transwell assay was performed to evaluate the SW403 cells migration. The correlation between miR-100-5p and PGM5-AS1 was detected by statistical analysis. Bioinformatics prediction and Luciferase assay were performed to explore the interaction and binding site of PGM5-AS1 and miR-100-5p, miR-100-5p and SMAD4, respectively.

RESULTS

We found that both PGM5-AS1 and SMAD4 were downregulated in human colorectal cancer tissues and cells. qRT-PCR and CCK-8 assay showed that PGM5-AS1 expression is associated with the proliferation of colorectal cancer cells. Transwell assay showed that PGM5-AS1 regulated the migration ability of colorectal cancer cells. The bioinformatics prediction and Luciferase assay demonstrated that by sponging miR-100-5p, PGM5-AS1 can serve as a molecular sponge to further regulate the expression of SMAD4.

CONCLUSIONS

In this study, we found that lncRNA-PGM5-AS1 was low expressed in human colorectal cancer cells, which could promote tumor proliferation, migration and invasion by serving as a molecular sponge and by modulating the inhibitory effect of miR-100-5p on tumor suppressor gene SMAD4.

High-dose saccharin supplementation does not induce gut microbiota changes or glucose intolerance in healthy humans and mice

BACKGROUND

Non-caloric artificial sweeteners (NCAS) are widely used as a substitute for dietary sugars to control body weight or glycemia. Paradoxically, some interventional studies in humans and rodents have shown unfavorable changes in glucose homeostasis in response to NCAS consumption. The causative mechanisms are largely unknown, but adverse changes in gut microbiota have been proposed to mediate these effects. These findings have raised concerns about NCAS safety and called into question their broad use, but further physiological and dietary considerations must be first addressed before these results are generalized. We also reasoned that, since NCAS are bona fide ligands for sweet taste receptors (STRs) expressed in the intestine, some metabolic effects associated with NCAS use could be attributed to a common mechanism involving the host.

RESULTS

We conducted a double-blind, placebo-controlled, parallel arm study exploring the effects of pure saccharin compound on gut microbiota and glucose tolerance in healthy men and women. Participants were randomized to placebo, saccharin, lactisole (STR inhibitor), or saccharin with lactisole administered in capsules twice daily to achieve the maximum acceptable daily intake for 2 weeks. In parallel, we performed a 10-week study administering pure saccharin at a high dose in the drinking water of chow-fed mice with genetic ablation of STRs (T1R2-KO) and wild-type (WT) littermate controls. In humans and mice, none of the interventions affected glucose or hormonal responses to an oral glucose tolerance test (OGTT) or glucose absorption in mice. Similarly, pure saccharin supplementation did not alter microbial diversity or composition at any taxonomic level in humans and mice alike. No treatment effects were also noted in readouts of microbial activity such as fecal metabolites or short-chain fatty acids (SCFA). However, compared to WT, T1R2-KO mice were protected from age-dependent increases in fecal SCFA and the development of glucose intolerance.

CONCLUSIONS

Short-term saccharin consumption at maximum acceptable levels is not sufficient to alter gut microbiota or induce glucose intolerance in apparently healthy humans and mice.

TRIAL REGISTRATION

Trial registration number NCT03032640 , registered on January 26, 2017. Video abstract.

A Novel Endocrine Role for the BAT-Released Lipokine 12,13-diHOME to Mediate Cardiac Function

BACKGROUND

Brown adipose tissue (BAT) is an important tissue for thermogenesis, making it a potential target to decrease the risks of obesity, type 2 diabetes, and cardiovascular disease, and recent studies have also identified BAT as an endocrine organ. Although BAT has been implicated to be protective in cardiovascular disease, to this point there are no studies that identify a direct role for BAT to mediate cardiac function.

METHODS

To determine the role of BAT on cardiac function, we utilized a model of BAT transplantation. We then performed lipidomics and identified an increase in the lipokine 12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME). We utilized a mouse model with sustained overexpression of 12,13-diHOME and investigated the role of 12,13-diHOME in a nitric oxide synthase type 1 deficient (NOS1^-/-) mouse and in isolated cardiomyocytes to determine effects on function and respiration. We also investigated 12,13-diHOME in a cohort of human patients with heart disease.

RESULTS

Here, we determined that transplantation of BAT (+BAT) improves cardiac function via the release of the lipokine 12,13-diHOME. Sustained overexpression of 12,13-diHOME using tissue nanotransfection negated the deleterious effects of a high-fat diet on cardiac function and remodeling, and acute injection of 12,13-diHOME increased cardiac hemodynamics via direct effects on the cardiomyocyte. Furthermore, incubation of cardiomyocytes with 12,13-diHOME increased mitochondrial respiration. The effects of 12,13-diHOME were absent in NOS1^-/- mice and cardiomyocytes. We also provide the first evidence that 12,13-diHOME is decreased in human patients with heart disease.

CONCLUSIONS

Our results identify an endocrine role for BAT to enhance cardiac function that is mediated by regulation of calcium cycling via 12,13-diHOME and NOS1.

Older adults with sarcopenia have distinct skeletal muscle phosphodiester, phosphocreatine, and phospholipid profiles

The loss of skeletal muscle mass and function with age (sarcopenia) is a critical healthcare challenge for older adults. 31‐phosphorus magnetic resonance spectroscopy (³¹P‐MRS) is a powerful tool used to evaluate phosphorus metabolite levels in muscle. Here, we sought to determine which phosphorus metabolites were linked with reduced muscle mass and function in older adults. This investigation was conducted across two separate studies. Resting phosphorus metabolites in skeletal muscle were examined by ³¹P‐MRS. In the first study, fifty‐five older adults with obesity were enrolled and we found that resting phosphocreatine (PCr) was positively associated with muscle volume and knee extensor peak power, while a phosphodiester peak (PDE2) was negatively related to these variables. In the second study, we examined well‐phenotyped older adults that were classified as nonsarcopenic or sarcopenic based on sex‐specific criteria described by the European Working Group on Sarcopenia in Older People. PCr content was lower in muscle from older adults with sarcopenia compared to controls, while PDE2 was elevated. Percutaneous biopsy specimens of the vastus lateralis were obtained for metabolomic and lipidomic analyses. Lower PCr was related to higher muscle creatine. PDE2 was associated with glycerol‐phosphoethanolamine levels, a putative marker of phospholipid membrane damage. Lipidomic analyses revealed that the major phospholipids, (phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol) were elevated in sarcopenic muscle and were inversely related to muscle volume and peak power. These data suggest phosphorus metabolites and phospholipids are associated with the loss of skeletal muscle mass and function in older adults.

Fat Distribution in Women Is Associated With Depot-Specific Transcriptomic Signatures and Chromatin Structure

BACKGROUND

Preferential accumulation of fat in the upper body (apple shape) is associated with higher risk of developing metabolic syndrome relative to lower body fat (pear shape). We previously discovered that chromatin openness partially defined the transcriptome of preadipocytes isolated from abdominal and gluteofemoral fat. However, the molecular mechanisms underlying interindividual variation in body shape are unknown.

METHODS

Adipocyte fraction was isolated from abdominal and gluteofemoral fat biopsies of premenopausal women (age and body mass index matched) segregated initially only by their waist-to-hip ratio. We evaluated transcriptomic and chromatin accessibility using RNA sequencing and assay for transposase-accessible chromatin using sequencing (ATAC-seq) along with key clinical parameters.

RESULTS

Our data showed that higher lower body fat mass was associated with better lipid profile and free fatty acid decrease after glucose administration. Lipid and glucose metabolic pathways genes were expressed at higher levels in gluteofemoral adipocyte fraction in pears, whereas genes associated with inflammation were higher both in abdominal and gluteofemoral apple adipocyte fraction. Gluteofemoral adipocyte chromatin from pear-shaped women contained a significantly higher number of differentially open ATAC-seq peaks relative to chromatin from the apple-shaped gluteofemoral adipocytes. In contrast, abdominal adipocyte chromatin openness showed few differences between apple- and pear-shaped women. We revealed a correlation between gene transcription and open chromatin at the proximity of the transcriptional start site of some of the differentially expressed genes.

CONCLUSIONS

Integration of data from all 3 approaches suggests that chromatin openness partially governs the transcriptome of gluteofemoral adipocytes and may be involved in the early metabolic syndrome predisposition associated with body shape.

Racial differences in body composition and cardiometabolic risk during the menopause transition: a prospective, observational cohort study

BACKGROUND

Obesity disproportionately affects more women than men. The loss of ovarian function during the menopause transition coincides with weight gain, increases in abdominal adiposity, and impaired metabolic health. Racial differences in obesity prevalence that results from the menopause transition are not well understood.

OBJECTIVE

The purpose of the study was to assess longitudinal changes in body composition and cardiometabolic risk among black and white women during the menopausal transition.

STUDY DESIGN

In a secondary analysis of a prospective, observational cohort study (the Healthy Transitions study), 161 women ≥43 years old with a body mass index of 20-40 kg/m² and who had not yet transitioned through menopause were enrolled at Pennington Biomedical Research Center. Women were seen annually for body composition by dual-energy X-ray absorptiometry, for abdominal adipose tissue distribution by computed tomography, for sex steroid hormones, and for cardiometabolic risk factors that include fasting glucose, insulin, and lipids. Surrogate measures of insulin sensitivity were also calculated.

RESULTS

Ninety-four women (25 black, 69 white) transitioned through menopause and were included within the analyses. At menopause onset, black women weighed more (77.8±3.0 vs 70.8±1.8 kg) and had a higher systolic (125±16 vs 118±14 mm Hg) and diastolic (80±8 vs 74±7 mm Hg) blood pressure compared with white women (all P≤.05). No other differences in body composition, sex steroid hormones, or cardiometabolic risk factors were observed at menopause onset. Before menopause, white women gained significant weight (3 kg), total body adiposity (6% percent body fat, 9% fat mass, 12% trunk fat mass) and abdominal adipose tissue (19% subcutaneous fat, 15% visceral fat, 19% total adipose tissue), which coincided with significant decreases in estradiol, sex hormone-binding globulin, and estrone sulfate and increases in follicle-stimulating hormone, total cholesterol, and low-density lipoprotein cholesterol. Conversely, black women had more abdominal adipose tissue before menopause, which was maintained across the menopause transition. Black women also had significant decreases in estrone sulfate and total testosterone and increases in follicle-stimulating hormone before menopause. In the postmenopausal years, abdominal subcutaneous adipose tissue, total adipose tissue, follicle-stimulating hormone, total cholesterol, and low-density and high-density lipoprotein cholesterol increased only in white women.

CONCLUSION

White women gained more abdominal adiposity during the menopause transition compared with black women, which, in part, may be due to differences in the pattern of sex steroid hormone changes between women of different racial backgrounds. The gains in abdominal adiposity in white women were observed in tandem with increased cardiometabolic risk factors. Future studies should consider comprehensive lifestyle approaches to target these increased gains in abdominal adiposity (ie, nutrition and physical activity coaching), while taking into account the potential interactions of race, body adiposity, sex steroid hormones, and their influence on cardiometabolic risk.

[Menopausal symptoms and quality of life of hormone receptor positive breast cancer patients at different endocrine therapy time]

Objective: To explore the menopausal symptoms and quality of life of hormone receptor positive (HR+ ) breast cancer patients at different endocrine therapy time. Methods: The HR+ breast cancer patients who were pathologically confirmed from 2011 to 2017 in the Sichuan Cancer Hospital were divided into three groups according to endocrine therapy time (<12 months, 12~36 months, >36 months) and analyzed by a cross-sectional study. The Menopausal symptoms and quality of life of these patients were measured using the modified Kupperman scale and the functional assessment of cancer therapy-breast cancer (FACT-B) scale. The differences of menopausal symptoms among different time groups and drug groups were analyzed by Chi-square test. The differences of quality of life and the effects of menopausal symptoms on quality of life were tested by covariance and multiple linear regression analyses. Results: The average score of menopausal symptom of 167 patients was 14.5±7.6 and the prevalence rate was 87.4% (146/167). Among all of the menopausal symptoms, the prevalence rate of insomnia was the highest (73.7%, 123/167). Besides insomnia and excitement, hot flashes was more prevalent in selective estrogen receptor modulator (SERM) users (64.8%, 79/122) , while osteoarthritis was more prevalent in aromatase inhibitor (AI) users (62.2%, 28/45). The total score of FACT-B of Patients was 104.5±15.5, and the compliance rate was up to 89.8% (150/167). However, the condition of each dimension was different, the compliance rates of social/ family and functional dimension were lowest, which were 73.0% (122/167) and 50.9% (85/167), respectively. The menopausal symptoms of patients at different time groups were 15.0±1.3, 14.0±6.9, 14.5±7.4, respectively, and the total score of FACT-B of patients at different time groups were 102.7±17.8, 105.0±12.9, 105.6±16.7, respectively, without significant differences (both P>0.05). Multiple linear regression analysis showed that menopausal symptoms impaired the quality of life of SERM users during the endocrine therapeutic period. The standardized regression coefficients of three time groups were -0.67, -0.30, -0.50, respectively, with the lowest effect on 12~36 months group. Conclusion: HR+ breast cancer patients will have a poor function recovery and social/ family return, who need more attention. Menopausal symptoms are common problems during endocrine therapy, and active measures should be taken to improve patients' quality of life.

Individual Response Variation in the Effects of Weight Loss and Exercise on Insulin Sensitivity and Cardiometabolic Risk in Older Adults

Weight loss induced by decreased energy intake (diet) or exercise generally has favorable effects on insulin sensitivity and cardiometabolic risk. The variation in these responses to diet-induced weight loss with or without exercise, particularly in older obese adults, is less clear. The objectives of our study were to (1) examine the effect of weight loss with or without exercise on the variability of responses in insulin sensitivity and cardiometabolic risk factors and (2) to explore whether baseline phenotypic characteristics are associated with response. Sedentary older obese (BMI 36.3 ± 5.0 kg/m²) adults (68.6 ± 4.7 years) were randomized to one of 3 groups: health education control (HED); diet-induced weight loss (WL); or weight loss and exercise (WL + EX) for 6 months. Composite Z-scores were calculated for changes in insulin sensitivity (C_IS: rate of glucose disposal/insulin at steady state during hyperinsulinemic euglycemic clamp, HOMA-IR, and HbA1C) and cardiometabolic risk (C_CMR: waist circumference, triglycerides, and fasting glucose). Baseline measures included body composition (MRI), cardiorespiratory fitness, in vivo mitochondrial function (ATPmax; P-MRS), and muscle fiber type. WL + EX groups had a greater proportion of High Responders in both C_IS and C_CMR compared to HED and WL only (all p < 0.05). Pre-intervention measures of insulin (r = 0.60) and HOMA-IR (r = 0.56) were associated with change in insulin sensitivity (C_IS) in the WL group (p < 0.05). Pre-intervention measures of glucose (r = 0.55), triglycerides (r = 0.53), and VLDL (r = 0.53) were associated with change in cardiometabolic risk (C_CMR) in the WL group (p < 0.05), whereas triglycerides (r = 0.59) and VLDL (r = 0.59) were associated with C_CMR (all p < 0.05) in WL + EX. Thus, the addition of exercise to diet-induced weight loss increases the proportion of older obese adults who improve insulin sensitivity and cardiometabolic risk. Additionally, individuals with poorer metabolic status are more likely to experience greater improvements in cardiometabolic risk during weight loss with or without exercise.

Endurance training remodels skeletal muscle phospholipid composition and increases intrinsic mitochondrial respiration in men with Type 2 diabetes

The effects of exercise training on the skeletal muscle (SKM) lipidome and mitochondrial function have not been thoroughly explored in individuals with Type 2 diabetes (T2D). We hypothesize that 10 wk of supervised endurance training improves SKM mitochondrial function and insulin sensitivity that are related to alterations in lipid signatures within SKM of T2D (males n = 8). We employed integrated multi-omics data analyses including ex vivo lipidomics (MS/MS-shotgun) and transcriptomics (RNA-Seq). From biopsies of SKM, tissue and primary myotubes mitochondrial respiration were quantified by high-resolution respirometry. We also performed hyperinsulinemic-euglycemic clamps and blood draws before and after the training. The lipidomics analysis revealed that endurance training (>95% compliance) increased monolysocardiolipin by 68.2% (P ≤ 0.03), a putative marker of mitochondrial remodeling, and reduced total sphingomyelin by 44.8% (P ≤ 0.05) and phosphatidylserine by 39.7% (P ≤ 0.04) and tended to reduce ceramide lipid content by 19.8%. Endurance training also improved intrinsic mitochondrial respiration in SKM of T2D without alterations in mitochondrial DNA copy number or cardiolipin content. RNA-Seq revealed 71 transcripts in SKM of T2D that were differentially regulated. Insulin sensitivity was unaffected, and HbA1c levels moderately increased by 7.3% despite an improvement in cardiorespiratory fitness (V̇o_2peak) following the training intervention. In summary, endurance training improves intrinsic and cell-autonomous SKM mitochondrial function and modifies lipid composition in men with T2D independently of alterations in insulin sensitivity and glycemic control.

[Association of plasma leptin levels and soluble leptin receptor with breast cancer]

Objective: To explore the association between plasma leptin (LEP) levels, soluble leptin receptor(SLR), free leptin index and breast cancer. Methods: 245 new female cases of primary breast cancer confirmed by histopathology examination were sequentially recruited into the study. A total of 245 age-matched healthy women were enrolled as controls during the same period. A standardized questionnaire was used to collect the demographic information of the subjects. Blood samples were collected and the levels of LEP and SLR in plasma were measured by enzyme linked immunosorbent assay. The differences of LEP, SLR and FLI expression between control and cases group, as well as different breast cancer subtypes and TNM stages were compared using t-test and ANOVA after stratification by menopause status. Multivariate logistic regression was used to explore the contributions of the three indexes to the risk of breast cancer. Results: Females in both cases and control group were (50.7 ± 9.4) years old. The level of SLR and FLI (P(50)(P(25),P(75))) in premenopausal women were 18.4 (11.2, 28.7), 0.5 (0.4, 0.6) μg/L in case group and 27.7 (19.2, 43.4), 0.3 (0.3, 0.4) μg/L in control group (P<0.001). While the level of postmenopausal women in case group were 20.3 (12.8, 31.8), 0.5 (0.4, 0.6) μ g/L (P<0.001), and 30.1 (18.8, 40.5), 0.3 (0.3, 0.5) μg/L in control group (P<0.001), respectively. After adjustment for confounding factors and BMI, the relationship between FLI and breast cancer remained significant for both pre- and postmenopausal women while the association between SLR and breast cancer was significant only in premenopausal women. Compared with the lowest level of SLR, higer levels of SLR is associated with a reduced risk of breast cancer (premenopausal women, OR=0.10, 95% CI: 0.04-0.29, P(trend)<0.001). Compared with the lowest level of FLI, FLI at higher levels is associated with an increased risk of breast cancer (premenopausal women, OR=7.14, 95% CI: 2.86-17.83, P(trend)<0.001; postmenopausal women, OR=8.10, 95% CI: 2.85-22.98, P(trend)<0.001). No significant association between LEP and breast cancer or association between the three indexes and breast cancer subtypes and TNM stages was found (P>0.05). Conclusion: SLR may be a protective factor for breast cancer while FLI may increase the risk of breast cancer.

Exercise Response Variations in Skeletal Muscle PCr Recovery Rate and Insulin Sensitivity Relate to Muscle Epigenomic Profiles in Individuals With Type 2 Diabetes

OBJECTIVE

Some individuals with type 2 diabetes do not reap metabolic benefits from exercise training, yet the underlying mechanisms of training response variation are largely unexplored. We classified individuals with type 2 diabetes (n = 17) as nonresponders (n = 6) or responders (n = 11) based on changes in phosphocreatine (PCr) recovery rate after 10 weeks of aerobic training. We aimed to determine whether the training response variation in PCr recovery rate was marked by distinct epigenomic profiles in muscle prior to training.

RESEARCH DESIGN AND METHODS

PCr recovery rate as an indicator of in vivo muscle mitochondrial function in vastus lateralis (³¹P-magnetic resonance spectroscopy), insulin sensitivity (M-value; hyperinsulinemic-euglycemic clamp), aerobic capacity (Vo_2peak), and blood profiles were determined pretraining and post-training. Muscle biopsies were performed pretraining in vastus lateralis for the isolation of primary skeletal muscle cells (HSkMCs) and assessments of global DNA methylation and RNA sequencing in muscle tissue and HSkMCs.

RESULTS

By design, nonresponders decreased and responders increased PCr recovery rate with training. In nonresponders, insulin sensitivity did not improve and glycemic control (HbA_1c) worsened. In responders, insulin sensitivity improved. Vo_2peak improved by ∼12% in both groups. Nonresponders and responders were distinguished by distinct pretraining molecular (DNA methylation, RNA expression) patterns in muscle tissue, as well as in HSkMCs. Enrichment analyses identified elevations in glutathione regulation, insulin signaling, and mitochondrial metabolism in nonresponders pretraining, which was reflected in vivo by higher pretraining PCr recovery rate and insulin sensitivity in these same individuals.

CONCLUSIONS

A training response variation for clinical risk factors in individuals with type 2 diabetes is reflected by distinct basal myocellular epigenomic profiles in muscle tissue, some of which are maintained in HSkMCs, suggesting a cell-autonomous underpinning. Our data provide new evidence to potentially shift the diabetes treatment paradigm for individuals who do not benefit from training, such that supplemental treatment can be designed.

Elevated Nicotinamide Phosphoribosyl Transferase in Skeletal Muscle Augments Exercise Performance and Mitochondrial Respiratory Capacity Following Exercise Training

Mice overexpressing NAMPT in skeletal muscle (NamptTg mice) develop higher exercise endurance and maximal aerobic capacity (VO₂max) following voluntary exercise training compared to wild-type (WT) mice. Here, we aimed to investigate the mechanisms underlying by determining skeletal muscle mitochondrial respiratory capacity in NamptTg and WT mice. Body weight and body composition, tissue weight (gastrocnemius, quadriceps, soleus, heart, liver, and epididymal white adipose tissue), skeletal muscle and liver glycogen content, VO₂max, skeletal muscle mitochondrial respiratory capacity (measured by high-resolution respirometry), skeletal muscle gene expression (measured by microarray and qPCR), and skeletal muscle protein content (measured by Western blot) were determined following 6 weeks of voluntary exercise training (access to running wheel) in 13-week-old male NamptTg (exercised NamptTg) mice and WT (exercised WT) mice. Daily running distance and running time during the voluntary exercise training protocol were recorded. Daily running distance (p = 0.51) and running time (p = 0.85) were not significantly different between exercised NamptTg mice and exercised WT mice. VO₂max was higher in exercised NamptTg mice compared to exercised WT mice (p = 0.02). Body weight (p = 0.92), fat mass (p = 0.49), lean mass (p = 0.91), tissue weight (all p > 0.05), and skeletal muscle (p = 0.72) and liver (p = 0.94) glycogen content were not significantly different between exercised NamptTg mice and exercised WT mice. Complex I oxidative phosphorylation (OXPHOS) respiratory capacity supported by fatty acid substrates (p < 0.01), maximal (complex I+II) OXPHOS respiratory capacity supported by glycolytic (p = 0.02) and fatty acid (p < 0.01) substrates, and maximal uncoupled respiratory capacity supported by fatty acid substrates (p < 0.01) was higher in exercised NamptTg mice compared to exercised WT mice. Transcriptomic analyses revealed differential expression for genes involved in oxidative metabolism in exercised NamptTg mice compared to exercised WT mice, specifically, enrichment for the gene set related to the SIRT3-mediated signaling pathway. SIRT3 protein content correlated with NAMPT protein content (r = 0.61, p = 0.04). In conclusion, NamptTg mice develop higher exercise capacity following voluntary exercise training compared to WT mice, which is paralleled by higher mitochondrial respiratory capacity in skeletal muscle. The changes in SIRT3 targets suggest that these effects are due to remodeling of mitochondrial function.

Physical activity unveils the relationship between mitochondrial energetics, muscle quality, and physical function in older adults

BACKGROUND

The concept of mitochondrial dysfunction in ageing muscle is highly controversial. In addition, emerging evidence suggests that reduced muscle oxidative capacity and efficiency underlie the aetiology of mobility loss in older adults. Here, we hypothesized that studying well-phenotyped older cohorts across a wide range of physical activity would unveil a range of mitochondrial function in skeletal muscle and in turn allow us to more clearly examine the impact of age per se on mitochondrial energetics. This also enabled us to more clearly define the relationships between mitochondrial energetics and muscle lipid content with clinically relevant assessments of muscle and physical function.

METHODS

Thirty-nine volunteers were recruited to the following study groups: young active (YA, n = 2 women/8 men, age = 31.2 ± 5.4 years), older active (OA, n = 2 women/8 men, age = 67.5 ± 2.7 years), and older sedentary (OS, n = 8 women/11 men, age = 70.7 ± 4.7 years). Participants completed a graded exercise test to determine fitness (VO₂ peak), a submaximal exercise test to determine exercise efficiency, and daily physical activity was recorded using a tri-axial armband accelerometer. Mitochondrial energetics were determined by (i) ³¹ P magnetic resonance spectroscopy and (ii) respirometry of fibre bundles from vastus lateralis biopsies. Quadriceps function was assessed by isokinetic dynamometry and physical function by the short physical performance battery and stair climb test.

RESULTS

Daily physical activity energy expenditure was significantly lower in OS, compared with YA and OA groups. Despite fitness being higher in YA compared with OA and OS, mitochondrial respiration, maximum mitochondrial capacity, Maximal ATP production/Oxygen consumption (P/O) ratio, and exercise efficiency were similar in YA and OA groups and were significantly lower in OS. P/O ratio was correlated with exercise efficiency. Time to complete the stair climb and repeated chair stand tests were significantly greater for OS. Interestingly, maximum mitochondrial capacity was related to muscle contractile performance and physical function.

CONCLUSIONS

Older adults who maintain a high amount of physical activity have better mitochondrial capacity, similar to highly active younger adults, and this is related to their better muscle quality, exercise efficiency, and physical performance. This suggests that mitochondria could be an important therapeutic target for sedentary ageing associated conditions including sarcopenia, dynapenia, and loss of physical function.

MiR-26a regulates vascular smooth muscle cell calcification in vitro through targeting CTGF

Vascular calcification is one of the most important factors for high morbidity and mortality from cardiovascular and cerebrovascular diseases. The aim of this study is to investigate the effect and mechanism of miR-26a on vascular smooth muscle cell calcification. First, the VSMCs were induced by β-glycerol phosphate (β-GP) for 7d and 14d, and Alizarin Red S staining was performed to examine the mineralized nodule change; then real time RT-PCR and western blotting were performed to explore the expression of miR-26a, CTGF, OPG, RANKL and ALP in un-induced and β-GP-induced VSMCs; next, the VSMCs were transfected with miR-26a mimics, and Alizarin Red S staining was performed to examine the mineralized nodule change; finally, real time RT-PCR and western blotting were performed to explore the expression of miR-26a, CTGF, OPG, RANKL and ALP in un-transfected and miR-26a mimics transfected VSMCs. After β-GP treatment, β-GP promoted clear mineralized nodule changes, and miR-26a and OPG expression were significantly decreased and CTGF, RANKL and ALP expression were increased in VSMCs. Overexpression of miR-26a inhibited VSMCs calcification induced by β-GP, and regulated the expression of CTGF, OPG, RANKL and ALP. Our findings suggested that up-regulation of miR-26a before β-GP treatment inhibits VSMCs calcification through targeting CTGF (Fig. 4, Ref. 18).

Skeletal muscle overexpression of nicotinamide phosphoribosyl transferase in mice coupled with voluntary exercise augments exercise endurance

Objective

Nicotinamide phosphoribosyl transferase (NAMPT) is the rate-limiting enzyme in the salvage pathway that produces nicotinamide adenine dinucleotide (NAD⁺), an essential co-substrate regulating a myriad of signaling pathways. We produced a mouse that overexpressed NAMPT in skeletal muscle (NamptTg) and hypothesized that NamptTg mice would have increased oxidative capacity, endurance performance, and mitochondrial gene expression, and would be rescued from metabolic abnormalities that developed with high fat diet (HFD) feeding.

Methods

Insulin sensitivity (hyperinsulinemic-euglycemic clamp) was assessed in NamptTg and WT mice fed very high fat diet (VHFD, 60% by kcal) or chow diet (CD). The aerobic capacity (VO₂max) and endurance performance of NamptTg and WT mice before and after 7 weeks of voluntary exercise training (running wheel in home cage) or sedentary conditions (no running wheel) were measured. Skeletal muscle mitochondrial gene expression was also measured in exercised and sedentary mice and in mice fed HFD (45% by kcal) or low fat diet (LFD, 10% by kcal).

Results

NAMPT enzyme activity in skeletal muscle was 7-fold higher in NamptTg mice versus WT mice. There was a concomitant 1.6-fold elevation of skeletal muscle NAD⁺. NamptTg mice fed VHFD were partially protected against body weight gain, but not against insulin resistance. Notably, voluntary exercise training elicited a 3-fold higher exercise endurance in NamptTg versus WT mice. Mitochondrial gene expression was higher in NamptTg mice compared to WT mice, especially when fed HFD. Mitochondrial gene expression was higher in exercised NamptTg mice than in sedentary WT mice.

Conclusions

Our studies have unveiled a fascinating interaction between elevated NAMPT activity in skeletal muscle and voluntary exercise that was manifest as a striking improvement in exercise endurance.

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Skeletal muscle NAMPT overexpression increases NAD⁺ via elevated NAMPT activity.

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Elevated NAMPT partially protects against very-high-fat-diet-induced weight gain.

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Elevated NAMPT amplifies exercise-induced improvements in exercise endurance.

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Fascinating interaction between elevated NAMPT activity in muscle and exercise.

Inhibition of sweet chemosensory receptors alters insulin responses during glucose ingestion in healthy adults: a randomized crossover interventional study

Background: Glucose is a natural ligand for sweet taste receptors (STRs) that are expressed on the tongue and in the gastrointestinal tract. Whether STRs directly contribute to the regulation of glucose homeostasis in response to glucose ingestion is unclear.Objective: We sought to determine the metabolic effects of the pharmacologic inhibition of STRs in response to an oral glucose load in healthy lean participants.Design: Ten healthy lean participants with a body mass index (in kg/m²) of 22.4 ± 0.8 were subjected to an oral-glucose-tolerance test (OGTT) on 4 separate days with the use of a randomized crossover design. Ten minutes before the 75-g OGTT, participants consumed a preload solution of either 300 parts per million (ppm) saccharin or water with or without the addition of 500 ppm lactisole, a human-specific inhibitor of STRs. When present, lactisole was included in both the preload and OGTT solutions. We assessed plasma responses of glucose, insulin, C-peptide, glucagon, glucagon-like peptides 1 and 2, gastric inhibitory peptide, acetaminophen, and 3-O-methylglucose. With the use of mathematical modeling, we estimated gastric emptying, glucose absorption, β-cell function, insulin sensitivity and clearance, and the portal insulin:glucagon ratio.Results: The addition of lactisole to the OGTT caused increases in the plasma responses of insulin (P = 0.012), C-peptide (P = 0.004), and the insulin secretory rate (P = 0.020) compared with the control OGTT. The addition of lactisole also caused a slight reduction in the insulin sensitivity index independent of prior saccharin consumption (P < 0.025). The ingestion of saccharin before the OGTT did not alter any of the measured variables but eliminated the effects of lactisole on the OGTT.Conclusion: The pharmacologic inhibition of STRs in the gastrointestinal tract alters insulin responses during an oral glucose challenge in lean healthy participants. This trial was registered at clinicaltrials.gov as NCT02835859.

Reduced skeletal muscle secreted frizzled-related protein 3 is associated with inflammation and insulin resistance

OBJECTIVE

To investigate the role of secreted frizzled-related protein 3 (Sfrp3) in insulin sensitivity (ISi) and β-cell function in humans across a spectrum of glucose homeostasis.

METHODS

Subjects included those with normal glucose homeostasis (NGT; n = 18), prediabetes (PD; n = 11), or type 2 diabetes (T2D; n=12). Serum and skeletal muscle (SkM) Sfrp3 levels were measured by ELISA and qPCR, respectively, and insulin signaling pathway was assessed by Western blot. IS and β-cell function were assessed by indices derived from frequently sampled intravenous glucose tolerance test.

RESULTS

SkM Sfrp3 mRNA levels were significantly reduced in PD and T2D versus NGT. Similarly, serum Sfrp3 levels tended to be decreased in PD and T2D versus NGT. SkM Sfrp3 mRNA levels correlated negatively with circulating proinflammatory cytokines (IL-6, IFN-γ) and positively with IS. In vitro-differentiated myotubes from lean insulin-sensitive subjects treated with either lipopolysaccharide (LPS) or recombinant IL-6 demonstrated a dose-dependent reduction in Sfrp3 gene expression. Treatment of myotubes with recombinant Sfrp3 restored LPS- and IL-6-induced attenuation of insulin-stimulated Akt phosphorylation.

CONCLUSIONS

Inflammation-induced reduction in SkM Sfrp3 expression may contribute to insulin resistance, and this effect may be prevented by addition of exogenous Sfrp3. Thus, Sfrp3 may be a novel target for insulin sensitization.

Effects of 12 Months of Caloric Restriction on Muscle Mitochondrial Function in Healthy Individuals

CONTEXT

The effects of caloric restriction (CR) on in vivo muscle mitochondrial function in humans are controversial.

OBJECTIVE

We evaluated muscle mitochondrial function and associated transcriptional profiles in nonobese humans after 12 months of CR.

DESIGN

Individuals from an ancillary study of the CALERIE 2 randomized controlled trial were assessed at baseline and 12 months after a 25% CR or ad libitum (control) diet.

SETTING

The study was performed at Pennington Biomedical Research Center in Baton Rouge, LA.

PARTICIPANTS

Study participants included 51 (34 female subjects, 25 to 50 years of age) healthy nonobese individuals randomized to 1 of 2 groups (CR or control).

INTERVENTION

This study included 12 months of a 25% CR or ad libitum (control) diet.

MAIN OUTCOMES

In vivo mitochondrial function [maximal ATP synthesis rate (ATPmax), ATPflux/O2 (P/O)] was determined by 31P-magnetic resonance spectroscopy and optical spectroscopy, and body composition was determined by dual-energy X-ray absorptiometry. In a subset of individuals, a muscle biopsy was performed for transcriptional profiling via quantitative reverse transcription polymerase chain reaction and microarrays.

RESULTS

Weight, body mass index (BMI), fat, and fat-free mass (P < 0.001 for all) significantly decreased at month 12 after CR vs control. In vivo ATPmax and P/O were unaffected by 12 months of CR. Targeted transcriptional profiling showed no effects on pathways involved in mitochondrial biogenesis, function, or oxidative stress. A subgroup analysis according to baseline P/O demonstrated that a higher (vs lower) P/O was associated with notable improvements in ATPmax and P/O after CR.

CONCLUSIONS

In healthy nonobese humans, CR has no effect on muscle mitochondrial function; however, having a "more coupled" (versus "less coupled") phenotype enables CR-induced improvements in muscle mitochondrial function.

Effects of 13-Hour Hyperglucagonemia on Energy Expenditure and Hepatic Glucose Production in Humans

Glucagon (GCG) acutely stimulates energy expenditure (EE) and hepatic glucose production (HGP) in humans, but whether these effects persist during hyperglucagonemia of longer duration is unclear. Using a prospective, randomized, single-blind, crossover study design, we therefore measured EE and rates of glucose appearance (glucose RA) during three separate infusion protocols in healthy lean males: A) 10-h overnight GCG infusion (6 ng/[kg × min]) followed by 3-h infusion of GCG, octreotide (OCT), and insulin (INS) for basal replacement; B) overnight saline (SAL) infusion followed by GCG/OCT/INS infusion; and C) overnight SAL infusion followed by SAL/OCT/INS infusion. Sleep EE, measured at 6 to 7 h of the overnight infusion, was increased 65-70 kcal/24 h in A compared with B and C. During the 3-h infusion, mean resting EE remained significantly increased in A versus C by ∼50 kcal/24 h; in B, resting EE increased with a statistical trend but was not significantly greater than in C. Glucose RA increased to comparable levels in A and B. We conclude that in healthy lean males, stimulation of EE and HGP is sustained during hyperglucagonemia of longer duration when insulin secretion is inhibited. The increase in EE at the present GCG dose was of marginal clinical significance.

Differences in Mitochondrial Coupling Reveal a Novel Signature of Mitohormesis in Muscle of Healthy Individuals

CONTEXT

Reduced mitochondrial coupling (ATP/O₂ [P/O]) is associated with sedentariness and insulin resistance. Interpreting the physiological relevance of P/O measured in vitro is challenging.

OBJECTIVE

To evaluate muscle mitochondrial function and associated transcriptional profiles in nonobese healthy individuals distinguished by their in vivo P/O.

DESIGN

Individuals from an ancillary study of Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy phase 2 were assessed at baseline.

SETTING

The study was performed at Pennington Biomedical Research Center.

PARTICIPANTS

Forty-seven (18 males, 26-50 y of age) sedentary, healthy nonobese individuals were divided into 2 groups based on their in vivo P/O.

INTERVENTION

None. Main Outcome(s): Body composition by dual-energy x-ray absorptiometry, in vivo mitochondrial function (P/O and maximal ATP synthetic capacity) by ³¹P-magnetic resonance spectroscopy and optical spectroscopy were measured. A muscle biopsy was performed to measure fiber type, transcriptional profiling (microarray), and protein expressions.

RESULTS

No differences in body composition, peak aerobic capacity, type I fiber content, or mitochondrial DNA copy number were observed between the 2 groups. Compared with the uncoupled group (lower P/O), the coupled group (higher P/O) had higher rates of maximal ATP synthetic capacity (maximal ATP synthetic capacity, P < .01). Transcriptomics analyses revealed higher expressions of genes involved in mitochondrial remodeling and the oxidative stress response in the coupled group. A trend for higher mitonuclear protein imbalance (P = .06) and an elevated mitochondrial unfolded protein response (heat shock protein 60 protein; P = .004) were also identified in the coupled group.

CONCLUSIONS

Higher muscle mitochondrial coupling is accompanied by an overall elevation in mitochondrial function, a novel transcriptional signature of oxidative stress and mitochondrial remodeling and indications of an mitochondrial unfolded protein response.

Exercise Inducible Lactate Dehydrogenase B Regulates Mitochondrial Function in Skeletal Muscle

Lactate dehydrogenase (LDH) catalyzes the interconversion of pyruvate and lactate, which are critical fuel metabolites of skeletal muscle particularly during exercise. However, the physiological relevance of LDH remains poorly understood. Here we show that Ldhb expression is induced by exercise in human muscle and negatively correlated with changes in intramuscular pH levels, a marker of lactate production, during isometric exercise. We found that the expression of Ldhb is regulated by exercise-induced peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α). Ldhb gene promoter reporter studies demonstrated that PGC-1α activates Ldhb gene expression through multiple conserved estrogen-related receptor (ERR) and myocyte enhancer factor 2 (MEF2) binding sites. Transgenic mice overexpressing Ldhb in muscle (muscle creatine kinase (MCK)-Ldhb) exhibited increased exercise performance and enhanced oxygen consumption during exercise. MCK-Ldhb muscle was shown to have enhanced mitochondrial enzyme activity and increased mitochondrial gene expression, suggesting an adaptive oxidative muscle transformation. In addition, mitochondrial respiration capacity was increased and lactate production decreased in MCK-Ldhb skeletal myotubes in culture. Together, these results identified a previously unrecognized Ldhb-driven alteration in muscle mitochondrial function and suggested a mechanism for the adaptive metabolic response induced by exercise training.