Adaptation of metabolism to multicellular aggregation, hypoxia and obese stromal cell incorporation as potential measure of survival of ovarian metastases.

Ovarian metastases exfoliate from the primary tumor and it is thought that aggregation supports their survival in the peritoneal cavity during dissemination but the underlying mechanisms are not clearly identified. We have previously shown that ovarian cancer cells acquire an increasingly glycolytic and metabolic flexible phenotype during progression. In the present study, we investigated how hypoxia, aggregation, and the incorporation of the obese stromal vascular fraction (SVF) affect cellular metabolism and the response to common anti-cancer and anti-diabetic drugs. Our results show a reduction of glucose uptake, lactate secretion, cellular respiration and ATP synthesis in response to hypoxia and aggregation, suggesting that the observed reduced proliferation of cells aggregated into spheroids is the result of a down-regulation of respiration. Recruitment of SVF to spheroids increased the spheroids invasive capacity but reduced respiration only in the most aggressive cells. Further, aggregation and hypoxia reduced the response to the metabolic drugs AICAR and metformin, and the chemotherapeutic agents cisplatin and paclitaxel. Our results suggest that the adaptation of cellular metabolism may contribute to enhanced survival under non-permissive conditions, and that these metabolic alterations may provide targets for future interventions that aim to enhance the survival of women with metastatic ovarian cancer.

Effects of Seasonal Vitamin D3 Supplementation on Strength, Power, and Body Composition in College Swimmers.

The purpose of this study was to evaluate the impact of fall season vitamin D3 supplementation on strength/power, body composition, and anabolic hormones in swimmers with optimal vitamin D status at summer's end. Male and female National Collegiate Athletic Association Division I swimmers (N = 19) with optimal 25-hydroxyvitamin D [25(OH)D] randomly received 5,000 IU of vitamin D3 (VITD) or placebo (PLA) daily for 12 weeks while participating in swimming and strength and conditioning training (August-November). Before and after the intervention, the participants underwent blood sampling for analysis of serum 25(OH)D, parathyroid hormone, total testosterone, free testosterone, sex hormone-binding globulin, and insulin-like growth factor 1, dual-energy X-ray absorptiometry, and strength/power testing (bench press, squat, dead lift, standing broad jump, vertical jump, and dips and pull-ups). Sex was used as a covariate for analyses. The 25(OH)D was decreased by 44% in PLA (p < .05) and increased by 8% in VITD over the 12 weeks. Fat-free mass increased in VITD (56.4-59.1 kg; p < .05), but not PLA (59.4-59.7 kg; p < .01). Significant Group × Time interaction effects were observed for dead lift (F = 21.577, p < .01) and vertical jump (F = 11.219, p < .01), but no other strength/power tests. Total testosterone decreased similarly in both groups, but free testosterone decreased and sex hormone-binding globulin increased only in PLA (p < .01). There were no group differences or changes in insulin-like growth factor 1 with the intervention. The findings suggest that vitamin D supplementation is an efficacious strategy to maintain 25(OH)D during the fall season training and to enhance some aspects of strength/power and fat-free mass in swimmers. Further research on the relationship between vitamin D and anabolic hormones is needed.

The δ13C Value of Fingerstick Blood Is a Valid, Reliable, and Sensitive Biomarker of Sugar-Sweetened Beverage Intake in Children and Adolescents.

Background: Reliance on self-reported dietary intake methods is a commonly cited research limitation, and dietary misreporting is a particular problem in children and adolescents. Objective indicators of dietary intake, such as dietary biomarkers, are needed to overcome this research limitation. The added sugar (AS) biomarker δ13C, which measures the relative abundance of 13C to 12C, has demonstrated preliminary validity in adults. Objective: The purpose of this investigation was to determine the comparative validity, test-retest reliability, and sensitivity of the δ13C biomarker to detect AS and sugar-sweetened beverage (SSB) intake using fingerstick blood samples in children and adolescents. Methods: Children (aged 6-11 y, n = 126, 56% male, mean ± SD age: 9 ± 2 y) and adolescents (aged 12-18 y, n = 200, 44% male, mean ± SD age: 15 ± 2 y) completed 4 testing sessions within a 3-wk period. Participants' height, weight, demographic characteristics, and health history were determined at the first session; 24-h recalls were obtained at each visit and fingerstick blood samples were collected at visits 1 and 3. Samples were analyzed for δ13C value using natural abundance stable isotope mass spectrometry. δ13C value was compared with dietary outcomes in the full sample, and in child and adolescent subgroups. t Tests and correlational analyses were used to assess biomarker validity and reliability, whereas logistic regression and area under the receiver-operator characteristic curve (AUC) were used to evaluate sensitivity. Results: Reported mean ± SD AS consumption was 82.2 ± 35.8 g/d and 329 ± 143 kcal/d, and SSB consumption was 222 ± 243 mL/d and 98 ± 103 kcal/d. Mean δ13C value was -19.65 ± 0.69‰, and was lower in children than in adolescents (-19.80 ± 0.67‰ compared with -19.56 ± 0.67‰, P = 0.002). δ13C values were similar across sessions (visit 1: -19.66 ± 0.68‰; visit 3: -19.64 ± 0.68‰; r = 0.99, P < 0.001) and were associated (P < 0.001) with intake of total AS (grams, kilocalories: r = 0.29) and SSB (milliliters, kilocalories: r = 0.35). The biomarker was able to better discriminate between high and low SSB consumers than high and low AS consumers, as demonstrated by the AUC (0.75 and 0.62, respectively). Conclusions: The δ13C biomarker is a promising, minimally invasive, objective biomarker of SSB intake in children and adolescents. Further evaluation using controlled feeding designs is warranted. Registered at clinicaltrials.gov as NCT02455388.

Selective overexpression of Toll-like receptor-4 in skeletal muscle impairs metabolic adaptation to high-fat feeding.

Toll-like receptor-4 (TLR-4) is elevated in skeletal muscle of obese humans, and data from our laboratory have shown that activation of TLR-4 in skeletal muscle via LPS results in decreased fatty acid oxidation (FAO). The purpose of this study was to determine whether overexpression of TLR-4 in skeletal muscle alters mitochondrial function and whole body metabolism in the context of a chow and high-fat diet. C57BL/6J mice (males, 6-8 mo of age) with skeletal muscle-specific overexpression of the TLR-4 (mTLR-4) gene were created and used for this study. Isolated mitochondria and whole muscle homogenates from rodent skeletal muscle (gastrocnemius and quadriceps) were investigated. TLR-4 overexpression resulted in a significant reduction in FAO in muscle homogenates; however, mitochondrial respiration and reactive oxygen species (ROS) production did not appear to be affected on a standard chow diet. To determine the role of TLR-4 overexpression in skeletal muscle in response to high-fat feeding, mTLR-4 mice and WT control mice were fed low- and high-fat diets for 16 wk. The high-fat diet significantly decreased FAO in mTLR-4 mice, which was observed in concert with elevated body weight and fat, greater glucose intolerance, and increase in production of ROS and cellular oxidative damage compared with WT littermates. These findings suggest that TLR-4 plays an important role in the metabolic response in skeletal muscle to high-fat feeding.

Ovarian tumor-initiating cells display a flexible metabolism.

An altered metabolism during ovarian cancer progression allows for increased macromolecular synthesis and unrestrained growth. However, the metabolic phenotype of cancer stem or tumor-initiating cells, small tumor cell populations that are able to recapitulate the original tumor, has not been well characterized. In the present study, we compared the metabolic phenotype of the stem cell enriched cell variant, MOSE-LFFLv (TIC), derived from mouse ovarian surface epithelial (MOSE) cells, to their parental (MOSE-L) and benign precursor (MOSE-E) cells. TICs exhibit a decrease in glucose and fatty acid oxidation with a concomitant increase in lactate secretion. In contrast to MOSE-L cells, TICs can increase their rate of glycolysis to overcome the inhibition of ATP synthase by oligomycin and can increase their oxygen consumption rate to maintain proton motive force when uncoupled, similar to the benign MOSE-E cells. TICs have an increased survival rate under limiting conditions as well as an increased survival rate when treated with AICAR, but exhibit a higher sensitivity to metformin than MOSE-E and MOSE-L cells. Together, our data show that TICs have a distinct metabolic profile that may render them flexible to adapt to the specific conditions of their microenvironment. By better understanding their metabolic phenotype and external environmental conditions that support their survival, treatment interventions can be designed to extend current therapy regimens to eradicate TICs.

Control of mitochondrial metabolism and systemic energy homeostasis by microRNAs 378 and 378*.

Obesity and metabolic syndrome are associated with mitochondrial dysfunction and deranged regulation of metabolic genes. Peroxisome proliferator-activated receptor γ coactivator 1ß (PGC-1ß) is a transcriptional coactivator that regulates metabolism and mitochondrial biogenesis through stimulation of nuclear hormone receptors and other transcription factors. We report that the PGC-1ß gene encodes two microRNAs (miRNAs), miR-378 and miR-378*, which counterbalance the metabolic actions of PGC-1ß. Mice genetically lacking miR-378 and miR-378* are resistant to high-fat diet-induced obesity and exhibit enhanced mitochondrial fatty acid metabolism and elevated oxidative capacity of insulin-target tissues. Among the many targets of these miRNAs, carnitine O-acetyltransferase, a mitochondrial enzyme involved in fatty acid metabolism, and MED13, a component of the Mediator complex that controls nuclear hormone receptor activity, are repressed by miR-378 and miR-378*, respectively, and are elevated in the livers of miR-378/378* KO mice. Consistent with these targets as contributors to the metabolic actions of miR-378 and miR-378*, previous studies have implicated carnitine O-acetyltransferase and MED13 in metabolic syndrome and obesity. Our findings identify miR-378 and miR-378* as integral components of a regulatory circuit that functions under conditions of metabolic stress to control systemic energy homeostasis and the overall oxidative capacity of insulin target tissues. Thus, these miRNAs provide potential targets for pharmacologic intervention in obesity and metabolic syndrome.

Metabolic changes during ovarian cancer progression as targets for sphingosine treatment.

Tumor cells often exhibit an altered metabolic phenotype. However, it is unclear as to when this switch takes place in ovarian cancer, and the potential for these changes to serve as therapeutic targets in clinical prevention and intervention trials. We used our recently developed and characterized mouse ovarian surface epithelial (MOSE) cancer progression model to study metabolic changes in distinct disease stages. As ovarian cancer progresses, complete oxidation of glucose and fatty acids were significantly decreased, concurrent with increases in lactate excretion and (3)H-deoxyglucose uptake by the late-stage cancer cells, shifting the cells towards a more glycolytic phenotype. These changes were accompanied by decreases in TCA flux but an increase in citrate synthase activity, providing substrates for de novo fatty acid and cholesterol synthesis. Also, uncoupled maximal respiration rates in mitochondria decreased as cancer progressed. Treatment of the MOSE cells with 1.5 µM sphingosine, a bioactive sphingolipid metabolite, decreased citrate synthase activity, increased TCA flux, decreased cholesterol synthesis and glycolysis. Together, our data confirm metabolic changes during ovarian cancer progression, indicate a stage specificity of these changes, and suggest that multiple events in cellular metabolism are targeted by exogenous sphingosine which may be critical for future prevention trials.

Toll-like receptor 4 modulates skeletal muscle substrate metabolism.

Toll-like receptor 4 (TLR4), a protein integral to innate immunity, is elevated in skeletal muscle of obese and type 2 diabetic humans and has been implicated in the development of lipid-induced insulin resistance. The purpose of this study was to examine the role of TLR4 as a modulator of basal (non-insulin-stimulated) substrate metabolism in skeletal muscle with the hypothesis that its activation would result in reduced fatty acid oxidation and increased partitioning of fatty acids toward neutral lipid storage. Human skeletal muscle, rodent skeletal muscle, and skeletal muscle cell cultures were employed to study the functional consequences of TLR4 activation on glucose and fatty acid metabolism. Herein, we demonstrate that activation of TLR4 with low (metabolic endotoxemia) and high (septic conditions) doses of LPS results in increased glucose utilization and reduced fatty acid oxidation in skeletal muscle and that these changes in metabolism in vivo occur in concert with increased circulating triglycerides. Moreover, animals with a loss of TLR4 function possess increased oxidative capacity in skeletal muscle and present with lower fasting levels of triglycerides and nonesterified free fatty acids. Evidence is also presented to suggest that these changes in substrate metabolism under metabolic endotoxemic conditions are independent of skeletal muscle-derived proinflammatory cytokine production. This report illustrates that skeletal muscle is a target for circulating endotoxin and may provide critical insight into the link between a proinflammatory state and dysregulated metabolism as observed with obesity, type 2 diabetes, and metabolic syndrome.

Exercise and Nutrition Science Students' Perceptions of Blogging as a Required Course Component.

The growth of social media and websites for transmission of health-related information has increased in recent years, and development of online communication skills should be included in exercise science education. Incorporation of blogging into the higher education classroom may serve this professional development purpose, while also increasing student engagement and enhancing learning outcomes. PURPOSE: The purposes of this study were to evaluate exercise and nutrition science students' perceptions of blogging on perceived learning, sense of community, and technical knowledge at the beginning and end of the semester, and to compare the perceptions of undergraduate (UG) and graduate (GRAD) students. METHODS: UG (pre, n = 78; post, n = 50) and GRAD (pre, n = 20; post, n = 17) students were enrolled in semester long seminar courses that required blogging. Perceptions of blogging were assessed using an anonymous Likert-scale survey at the beginning and end of the semester. T-tests were used to determine differences in perception on the survey subscales pre to post and between UG and GRAD students. RESULTS: Agreement that blogging could enhance learning or promote a sense of community was lower at the end of the semester compared with the beginning, but remained relatively high. Agreement with items related to technical knowledge increased from presemester to postsemester. The change in perception in the whole sample was driven by the UG students, as GRAD students' perceptions of blogging, although initially less positive than UG, were mainly unchanged from the start of the semester to the end. CONCLUSIONS: Blogging as a required course component is viewed favorably by exercise and nutrition science students. Future research evaluating course characteristics and structure of blogging requirements that may enhance student' perceptions are warranted.

Angiotensin II suppresses autophagy and disrupts ultrastructural morphology and function of mitochondria in mouse skeletal muscle.

Angiotensin II (ANG II)-induced skeletal muscle wasting is characterized by activation of the ubiquitin-proteasome system. However, the potential involvement of proteolytic system macroautophagy/autophagy in this wasting process remains elusive. Autophagy is precisely regulated to maintain cell survival and homeostasis; thus its dysregulation (i.e., overactivation or persistent suppression) could lead to detrimental outcomes in skeletal muscle. Here we show that infusion of ANG II for 7 days in male FVB mice suppressed autophagy in skeletal muscle. ANG II blunted microtubule-associated protein 1 light chain 3B (LC3B)-I-to-LC3B-II conversion (an autophagosome marker), increased p62/SQSTM1 (an autophagy cargo receptor) protein expression, and decreased the number of autophagic vacuoles. ANG II inhibited UNC-51-like kinase 1 via inhibition of 5'-AMP-activated kinase and activation of mechanistic target of rapamycin complex 1, leading to reduced phosphorylation of beclin-1Ser14 and Autophagy-related protein 14Ser29, suggesting that ANG II impairs autophagosome formation in skeletal muscle. In line with ANG II-mediated suppression of autophagy, ANG II promoted accumulation of abnormal/damaged mitochondria, characterized by swelling and disorganized cristae and matrix dissolution, with associated increase in PTEN-induced kinase 1 protein expression. ANG II also reduced mitochondrial respiration, indicative of mitochondrial dysfunction. Together, these results demonstrate that ANG II reduces autophagic activity and disrupts mitochondrial ultrastructure and function, likely contributing to skeletal muscle wasting. Therefore, strategies that activate autophagy in skeletal muscle have the potential to prevent or blunt ANG II-induced skeletal muscle wasting in chronic diseases. NEW & NOTEWORTHY Our study identified a novel mechanism whereby angiotensin II (ANG II) impairs mitochondrial energy metabolism in skeletal muscle. ANG II suppressed autophagosome formation by inhibiting the UNC-51-like kinase 1(ULK1)-beclin-1 axis, resulting in accumulation of abnormal/damaged and dysfunctional mitochondria and reduced mitochondrial respiratory capacity. Therapeutic strategies that activate the ULK1-beclin-1 axis have the potential to delay or reverse skeletal muscle wasting in chronic diseases characterized by increased systemic ANG II levels.

Physical activity in aging: comparison among young, aged, and nonagenarian individuals.

Physical activity (PA) is known to decline with age; however, there is a paucity of data on activity in persons who are in their nineties and beyond. We used objective and reliable methods to measure PA in nonagenarians (>or=90 yr; n=98) and hypothesized that activity would be similar to that of aged (60-74 yr; n=58) subjects but less than in young (20-34 yr; n=53) volunteers. Total energy expenditure (TEE) was measured by doubly labeled water over 14 days and resting metabolic rate (RMR) by indirect calorimetry. Measures of PA included activity energy expenditure adjusted for body composition, TEE adjusted for RMR, physical activity level (PAL), and activity over 14 days by accelerometry expressed as average daily durations of light and moderate activity. RMR and TEE were lower with increasing age group (P<0.01); however, RMR was not different between aged and nonagenarian subjects after adjusting for fat-free mass, fat mass, and sex. Nonagenarians had a lower PAL and were more sedentary than the aged and young groups (P<0.01); however, the nonagenarians who were more active on a daily basis walked further during a timed test, indicating higher physical functionality. For all measures of activity, no differences were found between young and aged volunteers. PA was markedly lower in nonagenarians compared with young and aged adults. Interestingly, PA was similar between young volunteers and those who were in their 60s and 70s, likely due to the sedentary nature of our society, particularly in young adults.

Aging, resting metabolic rate, and oxidative damage: results from the Louisiana Healthy Aging Study.

BACKGROUND: The aging process occurs at variable rates both among and within species and may be related to the variability in oxygen consumption and free radical production impacting oxidative stress. The current study was designed to test whether nonagenarians have a relatively low metabolic rate and whether it is associated with low levels of oxidative stress relative to age. METHODS: Resting metabolic rate (RMR) and markers of oxidative stress to lipids, proteins, and DNA were measured in three groups of individuals aged 20-34 (n=47), 60-74 (n=49), and>or=90 years (n=74). RESULTS: RMR, adjusted for fat-free mass, fat mass, and sex, was lower in both older groups when compared to the young group (p

Physical activity level and physical functionality in nonagenarians compared to individuals aged 60-74 years.

BACKGROUND: Functional dependence and the risks of disability increase with age. The loss of independence is thought to be partially due to a decrease in physical activity. However, in populations, accurate measurement of physical activity is challenging and may not provide information on functional impairment. METHODS: This study therefore assessed physical functionality and physical activity level in a group of nonagenarians (11 men/11 women; 93+/-1 years, 66.6+/-2.4 kg, body mass index [BMI]=24+/-1 kg/m2) and a group of participants aged 60-74 years (17 men/15 women; 70+/-1 years, 83.3+/-3.0 kg, BMI=29+/-1 kg/m2) from the Louisiana Healthy Aging Study. Physical activity level was calculated from total energy expenditure (TEE) and resting metabolic rate (RMR). Physical functionality was assessed using the Reduced Continuous Scale Physical Functional Performance Test (CS-PFP10). RESULTS: Nonagenarians had lower absolute (p<.001) and adjusted (p<.007) TEE compared to participants aged 60-74 years which was attributed to a reduction in both RMR and physical activity level. Nonagenarians also had reduced functional performance (p<.001) which was correlated with activity level (r=0.68, p<.001). CONCLUSIONS: When compared to individuals aged 60-74 years, 73% of the reduction in TEE in nonagenarians can be attributed to a reduction in physical activity level, the remaining being accounted for by a reduction in RMR. The reduced physical activity in nonagenarians is associated with less physical functionality. This study provides the first objective comparison of physical functionality and actual levels of physical activity in older individuals.

Effect of calorie restriction with or without exercise on insulin sensitivity, beta-cell function, fat cell size, and ectopic lipid in overweight subjects.

OBJECTIVE: The purpose of this article was to determine the relationships among total body fat, visceral adipose tissue (VAT), fat cell size (FCS), ectopic fat deposition in liver (intrahepatic lipid [IHL]) and muscle (intramyocellular lipid [IMCL]), and insulin sensitivity index (S(i)) in healthy overweight, glucose-tolerant subjects and the effects of calorie restriction by diet alone or in conjunction with exercise on these variables. RESEARCH DESIGN AND METHODS: Forty-eight overweight volunteers were randomly assigned to four groups: control (100% of energy requirements), 25% calorie restriction (CR), 12.5% calorie restriction +12.5% energy expenditure through structured exercise (CREX), or 15% weight loss by a low-calorie diet followed by weight maintenance for 6 months (LCD). Weight, percent body fat, VAT, IMCL, IHL, FCS, and S(i) were assessed at baseline and month 6. RESULTS: At baseline, FCS was related to VAT and IHL (P < 0.05) but not to IMCL. FCS was also the strongest determinant of S(i) (P < 0.01). Weight loss at month 6 was 1 +/- 1% (control, mean +/- SE), 10 +/- 1% (CR), 10 +/- 1% (CREX), and 14 +/- 1% (LCD). VAT, FCS, percent body fat, and IHL were reduced in the three intervention groups (P < 0.01), but IMCL was unchanged. S(i) was increased at month 6 (P = 0.05) in the CREX (37 +/- 18%) and LCD (70 +/- 34%) groups (P < 0.05) and tended to increase in the CR group (40 +/- 20%, P = 0.08). Together the improvements in S(i) were related to loss in weight, fat mass, and VAT, but not IHL, IMCL, or FCS. CONCLUSIONS: Large adipocytes lead to lipid deposition in visceral and hepatic tissues, promoting insulin resistance. Calorie restriction by diet alone or with exercise reverses this trend.

Acute low-dose endotoxin treatment results in improved whole-body glucose homeostasis in mice.

BACKGROUND: Obese individuals present with an increased inflammatory tone as compared to healthy, normal-weight individuals, which is associated with insulin resistance. One factor hypothesized to contribute to increased inflammation in obese and diabetic states is elevated blood endotoxin levels, a condition known as metabolic endotoxemia. In non-obese and insulin sensitive individuals, circulating endotoxin concentrations fluctuate over the course of the day with elevations in the post-prandial state that return to baseline levels in the post-absorptive state. Evidence suggests that high-fat feeding alters these fluctuations causing endotoxin levels to remain high throughout the day. The effects of alterations in endotoxin levels on glucose metabolism are not clearly understood. PURPOSE/PROCEDURES: The goal of this study was to determine the effects of both short-term and long-term increases in endotoxin (lipopolysaccharide, LPS) of a low magnitude on the glucose tolerance and insulin signaling in a human primary cell line as well as the effects of short-term endotoxin treatments on glucose homeostasis in a C57/Bl6 mouse model. First, we tested the hypothesis that short-term low-dose endotoxin treatments would augment insulin signaling and glycogen synthesis while long-term treatments would be disruptive in the cell culture model. Second, we examined if these short-term low dose treatments of endotoxin would contribute to similar improvements in whole-body glucose homeostasis in a mouse model. MAIN FINDINGS: Contrary to our initial hypothesis, short-term endotoxin treatment had no effect on insulin signaling or glycogen synthesis, however long-term treatment indeed decreased glycogen synthesis (P<.05). Interestingly, short-term endotoxin treatment resulted in significant improvements in glucose homeostasis in the mouse model (P<.01); which is believed to be at least partly attributed to an inhibitory action of LPS on liver glucose production. CONCLUSIONS: This research shows that low-magnitude, short-term changes in LPS can have significant effects on whole body glucose metabolism and this likely occurs through its direct actions on the liver. Additional studies are necessary to understand the mechanisms responsible for altered glucose metabolism in response to low magnitude changes in LPS levels.

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-Pink1Thr257 and phospho-ParkinS65 (r = 0.64, p < 0.005), and phospo-ParkinSer65 and phospho-Drp1Ser616 (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.

Effect of 6-month calorie restriction on biomarkers of longevity, metabolic adaptation, and oxidative stress in overweight individuals: a randomized controlled trial.

CONTEXT: Prolonged calorie restriction increases life span in rodents. Whether prolonged calorie restriction affects biomarkers of longevity or markers of oxidative stress, or reduces metabolic rate beyond that expected from reduced metabolic mass, has not been investigated in humans. OBJECTIVE: To examine the effects of 6 months of calorie restriction, with or without exercise, in overweight, nonobese (body mass index, 25 to <30) men and women. DESIGN, SETTING, AND PARTICIPANTS: Randomized controlled trial of healthy, sedentary men and women (N = 48) conducted between March 2002 and August 2004 at a research center in Baton Rouge, La. INTERVENTION: Participants were randomized to 1 of 4 groups for 6 months: control (weight maintenance diet); calorie restriction (25% calorie restriction of baseline energy requirements); calorie restriction with exercise (12.5% calorie restriction plus 12.5% increase in energy expenditure by structured exercise); very low-calorie diet (890 kcal/d until 15% weight reduction, followed by a weight maintenance diet). MAIN OUTCOME MEASURES: Body composition; dehydroepiandrosterone sulfate (DHEAS), glucose, and insulin levels; protein carbonyls; DNA damage; 24-hour energy expenditure; and core body temperature. RESULTS: Mean (SEM) weight change at 6 months in the 4 groups was as follows: controls, -1.0% (1.1%); calorie restriction, -10.4% (0.9%); calorie restriction with exercise, -10.0% (0.8%); and very low-calorie diet, -13.9% (0.7%). At 6 months, fasting insulin levels were significantly reduced from baseline in the intervention groups (all P<.01), whereas DHEAS and glucose levels were unchanged. Core body temperature was reduced in the calorie restriction and calorie restriction with exercise groups (both P<.05). After adjustment for changes in body composition, sedentary 24-hour energy expenditure was unchanged in controls, but decreased in the calorie restriction (-135 kcal/d [42 kcal/d]), calorie restriction with exercise (-117 kcal/d [52 kcal/d]), and very low-calorie diet (-125 kcal/d [35 kcal/d]) groups (all P<.008). These "metabolic adaptations" (~ 6% more than expected based on loss of metabolic mass) were statistically different from controls (P<.05). Protein carbonyl concentrations were not changed from baseline to month 6 in any group, whereas DNA damage was also reduced from baseline in all intervention groups (P <.005). CONCLUSIONS: Our findings suggest that 2 biomarkers of longevity (fasting insulin level and body temperature) are decreased by prolonged calorie restriction in humans and support the theory that metabolic rate is reduced beyond the level expected from reduced metabolic body mass. Studies of longer duration are required to determine if calorie restriction attenuates the aging process in humans. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00099151.

Metabolic endotoxemia with obesity: Is it real and is it relevant?

Obesity is associated with metabolic derangements in multiple tissues, which contribute to the progression of insulin resistance and the metabolic syndrome. The underlying stimulus for these metabolic derangements in obesity are not fully elucidated, however recent evidence in rodents and humans suggests that systemic, low level elevations of gut derived endotoxin (lipopolysaccharide, LPS) may play an important role in obesity related, whole-body and tissue specific metabolic perturbations. LPS initiates a well-characterized signaling cascade that elicits many pro- and anti-inflammatory pathways when bound to its receptor, Toll-Like Receptor 4 (TLR4). Low-grade elevation in plasma LPS has been termed "metabolic endotoxemia" and this state is associated with a heightened pro-inflammatory and oxidant environment often observed in obesity. Given the role of inflammatory and oxidative stress in the etiology of obesity related cardio-metabolic disease risk, it has been suggested that metabolic endotoxemia may serve a key mediator of metabolic derangements observed in obesity. This review provides supporting evidence of mechanistic associations with cell and animal models, and provides complimentary evidence of the clinical relevance of metabolic endotoxemia in obesity as it relates to inflammation and metabolic derangements in humans. Discrepancies with endotoxin detection are considered, and an alternate method of reporting metabolic endotoxemia is recommended until a standardized measurement protocol is set forth.

Beverage Choices of Adolescents and Their Parents Using the Theory of Planned Behavior: A Mixed Methods Analysis.

BACKGROUND: Added sugar intake in the form of sugar-sweetened beverages (SSBs) has been considered a contributor to weight gain and cardiometabolic dysfunction in adults and youth. Adolescents are some of the highest consumers of added sugars, taking in ∼16% of their total calories from added sugars with ∼40% of these calories coming from SSBs. Food preferences and self-regulation of dietary intake by youth can be influenced by parents. OBJECTIVE: To evaluate the effectiveness of the Theory of Planned Behavior (TPB) in understanding and predicting adolescents' SSB consumption, identify which constructs are the most important when evaluating SSB consumption in adolescents, and determine whether and how adolescents' beverage choices are influenced by parents' reactions to their beverage choices. DESIGN: Measurements for this cross-sectional study included four record-assisted 24-hour dietary recalls and responses to an SSB-specific TPB questionnaire from 100 adolescents. Consenting parents completed a beverage intake questionnaire, a TPB questionnaire, and the Parent Response to Beverage Choice Questionnaire. RESULTS: The TPB explained 34% of the variance in adolescents' and parents' intention to limit SSBs to <1cup/day. Parents' perceived behavioral control (b=1.35; P=0.002) and adolescents' subjective norms (b=0.57; P=0.001) were the strongest predictors of intention, and intention was the strongest predictor of SSB consumption in both adolescents and parents (b=-37 [P=0.026] and b=-49 [P=0.003], respectively). The TPB explained more variance in parent SSB consumption (R(2)=0.38) than adolescents (R(2)=0.22). Parents did more discouraging of SSBs and encouraging of non-SSBs. Adolescents' intention to limit SSB consumption moderated the relationship between parents' reactions encouraging SSBs and adolescents' predicted SSB consumption (P=0.021). CONCLUSIONS: The TPB explained a small but significant amount of variance in adolescents' SSB consumption. When addressing adolescent SSB intake, people in addition to parents may influence their intentions and SSB consumption.

Resistance exercise training and in vitro skeletal muscle oxidative capacity in older adults.

Whether resistance exercise training (RET) improves skeletal muscle substrate oxidative capacity and reduces mitochondrial production of reactive oxygen species in older adults remains unclear. To address this, 19 older males (≥60 years) were randomized to a RET (n = 11) or to a waitlist control group (n = 8) that remained sedentary for 12 weeks. RET was comprised of three upper body and four lower body movements on resistance machines. One set of 8-12 repetitions to failure of each movement was performed on three nonconsecutive days/week. Improvements in chest press and leg press strength were assessed using a three-repetition maximum (3 RM). Body composition was assessed via dual energy X-ray absorptiometry. Muscle biopsies were obtained from the vastus lateralis muscle at baseline and at both 3 weeks and 12 weeks. Palmitate and pyruvate oxidation rates were measured from the (14)CO2 produced from [1-(14)C] palmitic acid and [U-(14)C] pyruvate, respectively, during incubation of muscle homogenates. PGC-1α, TFAM, and PPARδ levels were quantified using qRT-PCR Citrate synthase (CS) and ß-HAD activities were determined spectrophotometrically. Mitochondrial production of reactive oxygen species (ROS) were assessed using the Amplex Red Hydrogen Peroxide/Peroxidase assay. There were no significant changes in body weight or body composition following the intervention. Chest press and leg press strength (3RM) increased ~34% (both P < 0.01) with RET There were no significant changes in pyruvate or fatty acid oxidation or in the expression of target genes with the intervention. There was a modest increase (P < 0.05) in ßHAD activity with RET at 12 weeks but the change in CS enzyme activity was not significant. In addition, there were no significant changes in ROS production in either group following RET Taken together, the findings of this study suggest that 12 weeks of low volume RET does not increase skeletal muscle oxidative capacity or reduce ROS production in older adults.