A single bout of breast milk expression does not increase resting metabolic rate.

INTRODUCTION: Breastfeeding women have elevated resting metabolic rate (RMR); however, whether a single bout of lactation increases RMR is unknown. This study aimed to determine if a single bout of lactation acutely increased RMR. METHODS: Twenty-two lactating women (age: 31 ± 0.9 year, body mass index: 27.3 ± 1.2 kg/m2 ) were recruited. RMR was assessed at baseline and at 1- and 2-h following breast milk expression. RESULTS: RMR was unchanged in lactating women following a single bout of lactation (baseline: 1437 ± 39; 1 h: 1425 ± 37 2 h: 1440 ± 31 kcal/day) (p > .05). RMR was not correlated to daily milk produced (r = 0.05, p > .05), but was correlated to body mass (r = 0.74, p < .001), fat-free mass (kg) (r = 0.61, p < .01), and fat mass (kg) (r = 0.71, p < .01). CONCLUSION: RMR in lactating women appears to be more related to body mass or composition in the postpartum period rather than lactation.

The association of moderate-to-vigorous and light-intensity physical activity on static balance in middle-aged and older-aged adults.

BACKGROUND: Falls are the leading cause of injury among adults ≥ 65 years of age. Participation in physical activity (PA) is associated with improved balance, though it is impact in the middle-age population is not well understood. AIM: The purpose of the current study was to examine the influence of PA intensity on static balance in middle-aged and older aged individuals. METHODS: Included were middle-aged adults (40-64 years) and older adults (≥ 65 years) from the 2003-2004 years of the National Health and Nutrition Evaluation Survey. Light physical activity (LPA) and moderate-vigorous physical activity (MVPA) were collected via accelerometer and static balance via the Romberg Test of Standing Balance. RESULTS: No significant odds ratio relationship was found between MVPA or LPA and having good static balance in the middle-aged population; 1.04 (95% CI 0.95, 1.13) p = 0.427 and 1.05 (95% CI 0.97, 1.14) p = 0.182, respectively. Whereas, in older adults, every 60-min increase in LPA was significantly associated with 28% higher odds of good balance (95% CI 1.15, 1.41; p < 0.001), and every 10-min increase in MVPA with 25% higher odds of good balance (95% CI 1.08, 1.45; p = 0.006). DISCUSSION: LPA and MVPA were not associated with good static balance in middle-aged adults, but in older adults LPA was significantly associated with good static balance. CONCLUSION: A significant relationship is found between age and fall risk, which is a major concern in the aging population.

Smoking during pregnancy increases chemerin expression in neonatal tissue.

NEW FINDINGS: What is the central question of this study? Is chemerin, an adipokine implicated in obesity, increased in neonates following in utero cigarette smoke exposure. What is the main finding and its importance? Chemerin mRNA expression was increased and chemerin DNA methylation was decreased in babies born to mothers who smoked during pregnancy. These data provide a potential mechanism that may be mediating the increased obesity risk in individuals that are born to mothers who smoked during pregnancy. ABSTRACT: It has been shown that in utero tobacco exposure increases offspring risk for obesity, but the mechanisms responsible for this increased risk are not well understood. Chemerin is an adipokine that regulates adipocyte differentiation. This chemokine is elevated in obese individuals and with smoke exposure, but its levels have not been measured in neonates exposed to cigarette smoke in utero. We examined chemerin gene expression [n = 31 non-smoker (NS) and 15 smoker (S)] and DNA methylation (n = 28 NS and n = 11 S) in skin collected from babies born to mothers who smoked during pregnancy as compared to non-smoking controls. Quality RNA and DNA were isolated from foreskin tissue following circumcision, and chemerin gene expression and DNA methylation were assessed. Further, in a second cohort, we utilized primary dermal foreskin fibroblasts as a functional measure of adipogenesis in living cells (n = 11 NS and n = 8 S). Cells were stimulated with an adipogenic cocktail, mRNA was isolated from cells after 14 days, and chemerin gene expression assessed via real-time PCR. Chemerin mRNA was elevated in both whole tissue (NS: 2409.20 ± 555.28 counts and S: 2966.72 ± 636.84 counts; P < 0.01) and primary fibroblasts (NS: 1.12 ± 0.55 2 Δ Δ C T and S: 2.13 ± 1.34 2 Δ Δ C T ; P = 0.04) collected from infants born to smoking mothers. Chemerin DNA methylation was reduced in whole tissue of offspring born to smokers (NS: 4.18 ± 1.28 and S: 3.07 ± 1.31%; P = 0.02), which may contribute to the increased gene expression. Neonates born to mothers who smoke during pregnancy exhibit distinct changes in chemerin gene expression in response to in utero tobacco smoke exposure which are regulated in part by epigenetic alterations.

Influence of physical inactivity on arterial compliance during a glucose challenge.

NEW FINDINGS: What is the central question of this study? To understand better the effects of acute hyperglycaemia on arterial stiffness in healthy young individuals, we assessed arterial stiffness in physically active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. What is the main finding and its importance? During an oral glucose tolerance test, we identified an increase in leg arterial stiffness (i.e. reduced femoral artery compliance) only when subjects were inactive for 5 days (<5000 steps day-1 ) and not when they were engaging in regular physical activity (>10,000 steps day-1 ). These results demonstrate the deleterious consequence of acute reductions in daily physical activity on the response of the peripheral vasculature to acute hyperglycaemia. ABSTRACT: Acute hyperglycaemia has been shown to augment indices of arterial stiffness in patients with insulin resistance and other co-morbidities; however, conflicting results exist in healthy young individuals. We examined whether acute hyperglycaemia after an oral glucose tolerance test (OGTT) increases arterial stiffness in healthy active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. High-resolution arterial diameter traces acquired from Doppler ultrasound allowed an arterial blood pressure (BP) waveform to be obtained from the diameter trace within a cardiac cycle. In 24 subjects, this method demonstrated sufficient agreement with the traditional approach for assessing arterial compliance using applanation tonometry. In 10 men, continuous recordings of femoral and brachial artery diameter and beat-to-beat BP (Finometer) were acquired at rest, 60 and 120 min of an OGTT before and after 5 days of reduced activity (from >10,000 to <5000 steps day-1 ). Compliance and ß-stiffness were quantified. Before the reduction in activity, the OGTT had no effect on arterial compliance or ß-stiffness. However, after the reduction in activity, femoral compliance was decreased (rest, 0.10 ± 0.03 mm2  mmHg-1 versus 120 min OGTT, 0.06 ± 0.02 mm2  mmHg-1 ; P < 0.001) and femoral ß-stiffness increased (rest, 8.7 ± 2.7 a.u. versus 120 min OGTT, 15.3 ± 6.5 a.u.; P < 0.001) during OGTT, whereas no changes occurred in brachial artery compliance (P = 0.182) or stiffness (P = 0.892). Insulin sensitivity (Matsuda index) was decreased after the reduction in activity (P = 0.002). In summary, in young healthy men the femoral artery becomes susceptible to acute hyperglycaemia after 5 days of reduced activity and the resultant decrease in insulin sensitivity, highlighting the strong influence of daily physical activity levels on vascular physiology.

Developmental Origins of Health Span and Life Span: A Mini-Review.

BACKGROUND: A vast body of research has demonstrated that disease susceptibility and offspring health can be influenced by perinatal factors, which include both paternal and maternal behavior and environment. Offspring disease risk has the potential to affect the health span and life span of offspring. KEY FINDINGS: Various maternal factors, such as environmental toxicant exposure, diet, stress, exercise, age at conception, and longevity have the potential to influence age-associated diseases such as cardiovascular disease, obesity, diabetes, and cancer risk in offspring. Paternal factors such as diet, age at conception, and longevity can potentially impact offspring health span and life span-reducing traits as well. PRACTICAL IMPLICATIONS: Continued research could go a long way toward defining mechanisms of the developmental origins of life span and health span, and eventually establishing regimens to avoid negative developmental influences and to encourage positive interventions to potentially increase life span and improve health span in offspring.

Physical activity intensity and markers of inflammation in those with non-alcoholic fatty liver disease.

AIMS: To investigate associations between objectively measured light (LPA) and moderate-to-vigorous (MVPA) physical activity on plasma homocysteine and serum C-reactive protein (CRP) in individuals with Non-Alcoholic Fatty Liver Disease (NAFLD). METHODS: This study was a secondary analysis using data from 2003 to 2006 National Health and Nutrition Examination Survey including a total of 983 individuals with NAFLD. Physical activity was assessed over 7 days with accelerometers. Participants were split into tertiles based on average daily minutes of LPA or MVPA and CRP and homocysteine were assessed across tertiles. RESULTS: Adjusted plasma homocysteine and CRP were not different between groups regarding levels of LPA (Homocysteine: 1st tertile - 10.4 ± 0.7 µmol/L; 2nd tertile - 9.6 ± 0.4 µmol/L; 3rd tertile - 9.6 ± 0.4 µmol/L; p = 0.28; CRP: 1st tertile - 0.79 ± 0.12 mg/dL; 2nd tertile - 0.73 ± 0.09 mg/dL; 3rd tertile - 0.73 ± 0.09 mg/dL; p = 0.72). Adjusted CRP was significantly (p = 0.02) different across MVPA tertiles (1st: 0.87 ± 0.13 mg/dL; 2nd: 0.75 ± 0.10 mg/dL; 3rd:0.65 ± 0.09). CONCLUSIONS: LPA does not appear to be effective at improving homocysteine or CRP levels in individuals with NAFLD. However, MVPA may be an effective therapy for decreasing CRP in NAFLD patients.

Short-term removal of exercise impairs glycemic control in older adults: A randomized trial.

Postprandial glycemia (PPG) predicts cardiovascular disease, and short-term physical inactivity increases PPG in young, active adults. Whether this occurs in older, active adults who may be more prone to bouts of inactivity is unknown. This study determined if postprandial interstitial glucose (PPIG) was impaired in active older adults following the removal of exercise for 3 days (NOEX) compared to active young adults. In this randomized, crossover study, 11 older (69.1 ± 1.9 years) and 9 young (32.8 ± 1.8 years) habitually active (≥90 min/week of exercise) adults completed 3-days of NOEX and 3-days of normal habitual exercise (EX), separated by ≥1 week. Diet was standardized across phases. Glycemic control (3-day average) was assessed via continuous glucose monitoring during both phases. Significant main effects of age and phase were detected (p < 0.05), but no interaction was found for steps/day (p > 0.05) (old EX: 6283 ± 607, old NOEX: 2380 ± 382 and young EX: 8798 ± 623, young NOEX: 4075 ± 516 steps/day). Significant main effects of age (p = 0.002) and time (p < 0.001) existed for 1-h PPIG, but no effect of phase or interactions was found (p > 0.05). Significant main effects (p < 0.05) of age (old: 114 ± 1 mg/dl, young: 106 ± 1 mg/dl), phase (NOEX: 112 ± 1 mg/dl, EX: 108 ± 1 mg/dl), and time (0 min: 100 ± 2, 30 min: 118 ± 2, 60 min: 116 ± 2, 90 min: 111 ± 2, 120 min: 108 ± 2 mg/dl) in 2-h PPIG were detected, but no interaction was found (p > 0.05). However, only significant main effects of phase (NOEX: 14 ± 1 and EX:12 ± 1, p > 0.05) were found for 24-h blood glucose standard deviation. Older adults appear to have impaired glycemic control compared to young adults and exercise removal impairs glycemic control in both populations. Yet, the impairment in glycemic control with exercise removal is not different between old and young adults.

Exposure to PCB126 during the nursing period reversibly impacts early-life glucose tolerance.

Polychlorinated biphenyls (PCBs) are persistent environmental organic pollutants known to have detrimental health effects. Using a mouse model, we previously demonstrated that PCB126 exposure before and during pregnancy and throughout the perinatal period adversely affected offspring glucose tolerance and/or body composition profiles. The purpose of this study was to investigate the glucose tolerance and body composition of offspring born to dams exposed to PCB126 during the nursing period only. Female ICR mice were bred, and half of the dams were exposed to either vehicle (safflower oil) or 1 µmole PCB126 per kg of body weight via oral gavage on postnatal days (PND) 3, 10, and 17 (n = 9 per group). Offspring body weight, lean and fat mass, and glucose tolerance were recorded every three weeks. PCB126 treatment did not alter dam nor offspring body weight (p > 0.05). PCB126-exposed male and female offspring displayed normal body composition (p > 0.05) relative to vehicle-exposed offspring. However, both male and female offspring that were exposed to PCB126 during the nursing period had significantly impaired glucose tolerance at 3 and 9 weeks of age (p < 0.05). At 6 and 12 weeks of age, no impairments in glucose tolerance existed in offspring (p > 0.05). Our current study demonstrates that exposure to PCB126 through the mother's milk does not affect short- or long-term body composition but impairs glucose tolerance in the short-term.

The association of physical activity on homocysteine in pregnant women.

INTRODUCTION: Women with high levels of physical activity have improved pregnancy, labor, and delivery outcomes related to cardiovascular health. Hyperhomocysteinemia, which predicts cardiovascular disease risk, is associated with maternal vascular complications during pregnancy, such as placental abruption and preeclampsia. However, studies are lacking on whether physical activity impacts homocysteine in pregnant women, pointing to a potential mechanism behind the improved cardiovascular health in women who exercise during pregnancy. The purpose of this study was to examine if women with high levels of physical activity have lower levels of homocysteine compared to women with low levels of physical activity. METHODS: This study was a secondary analysis using data from the 2003 to 2006 National Health and Nutrition Examination Survey. A total of 257 pregnant women were included. Physical activity was assessed objectively over seven days with accelerometers. High and low groups based on moderate-to-vigorous physical activity (MVPA) and steps/day were defined. Homocysteine and related laboratory biomarkers (vitamin B12, folate, pyridoxal 5'-phosphate) were assessed through blood draws. Data assembly was performed using SAS and analysis via SPSS Complex Samples. RESULTS: Only an estimated 17.7 ± 4.7% of women met guidelines to achieve at least 150 min per week of MVPA. Plasma homocysteine was not different between pregnant women with high and low levels of moderate-to-vigorous physical activity (4.39 ± 0.21 and 4.44 ± 0.17 µmol/L; p > .05) or between those with high and low levels of steps (3.95 ± 0.26 and 4.62 ± 0.27 µmol/L; p > .05) when the data was split into two quantiles by the median. These results were similar when using log-transformed values for homocysteine to normalize the distribution of data. Pregnant women in the group of the high steps tended to have higher vitamin B12, folate, and pyridoxal 5'-phosphate than those in the group of the low steps. Sensitivity analyses revealed that homocysteine was not different between the upper 25% (4.04 ± 0.22 µmol/L) and lower 25% (4.17 ± 0.26 µmol/L) MVPA (p = .716) but that it was statistically higher in the low (<5000 steps/day) (4.99 ± 0.20 µmol/L) steps/day group compared to high (>7500 steps/day) steps/day (3.99 ± 0.23 µmol/L) (p = .003) after excluding individuals with hypertension and thyroid/kidney issues. CONCLUSION: Maternal steps/day, but not MVPA, appear to be associated with homocysteine (albeit weakly) in the present study after excluding potential factors which impact homocysteine. The volume of physical activity appears to be an important indicator as this difference was not revealed until the physical activity was more distinctly separated.

Effects of maternal controlled exercise on offspring adiposity and glucose tolerance.

While metabolic disorders such as obesity and diabetes are costly and deadly to the current population, they are also extremely detrimental to the next generation. Much of the current literature focuses on the negative impact of poor maternal choices on offspring disease, while there is little work examining maternal behaviors that may improve offspring health. Research has shown that voluntary maternal exercise in mouse models improves metabolic function in offspring. In this study, we hypothesized that controlled maternal exercise in a mouse model will effect positive change on offspring obesity and glucose homeostasis. Female mice were separated into three groups: home cage, sedentary, and exercise. The sedentary home cage group was not removed from the home cage, while the sedentary wheel group was removed from the cage and placed in an immobile wheel apparatus. The exercise group was removed from the home cage and run on the same wheel apparatus but with the motor activated at 5-10 m/min for 1 h/d prior to and during pregnancy. Offspring were subjected to oral glucose tolerance testing and body composition analysis. There was no significant difference in offspring glucose tolerance or body composition as a consequence of the maternal exercise intervention compared to the sedentary wheel group. There were no marked negative consequences of the maternal controlled exercise intervention. Further research should clarify the potential advantages of the controlled exercise model and improve experimental techniques to facilitate translation of this research to human applications.

Using neonatal skin to study the developmental programming of aging.

Numerous studies have examined how both negative and positive maternal exposures (environmental contaminants, nutrition, exercise, etc.) impact offspring risk for age-associated diseases such as obesity, type 2 diabetes, hypertension, and others. The purpose of this study was to introduce the foreskin as a novel model to examine developmental programming in human neonates, particularly in regard to adipogenesis and insulin receptor signaling, major contributors to age-associated diseases such as obesity and diabetes. Neonatal foreskin was collected following circumcision and primary dermal fibroblasts were isolated to perform adipocyte differentiation and insulin stimulation experiments. Human neonatal foreskin primary fibroblasts take up lipid when stimulated with a differentiation cocktail and demonstrate insulin signaling when stimulated with insulin. Thus, we propose that foreskin tissue can be used to study developmental exposures and programming that occur in the neonate as it relates to age-associated diseases such as obesity and diabetes.

Obesity, type 2 diabetes, and impaired insulin-stimulated blood flow: role of skeletal muscle NO synthase and endothelin-1.

Increased endothelin-1 (ET-1) and reduced endothelial nitric oxide phosphorylation (peNOS) are hypothesized to reduce insulin-stimulated blood flow in type 2 diabetes (T2D), but studies examining these links in humans are limited. We sought to assess basal and insulin-stimulated endothelial signaling proteins (ET-1 and peNOS) in skeletal muscle from T2D patients. Ten obese T2D [glucose disposal rate (GDR): 6.6 ± 1.6 mg·kg lean body mass (LBM)-1·min-1] and 11 lean insulin-sensitive subjects (Lean GDR: 12.9 ± 1.2 mg·kg LBM-1·min-1) underwent a hyperinsulinemic-euglycemic clamp with vastus lateralis biopsies taken before and 60 min into the clamp. Basal biopsies were also taken in 11 medication-naïve, obese, non-T2D subjects. ET-1, peNOS (Ser1177), and eNOS protein and mRNA were measured from skeletal muscle samples containing native microvessels. Femoral artery blood flow was assessed by duplex Doppler ultrasound. Insulin-stimulated blood flow was reduced in obese T2D (Lean: +50.7 ± 6.5% baseline, T2D: +20.8 ± 5.2% baseline, P < 0.05). peNOS/eNOS content was higher in Lean under basal conditions and, although not increased by insulin, remained higher in Lean during the insulin clamp than in obese T2D (P < 0.05). ET-1 mRNA and peptide were 2.25 ± 0.50- and 1.52 ± 0.11-fold higher in obese T2D compared with Lean at baseline, and ET-1 peptide remained 2.02 ± 1.9-fold elevated in obese T2D after insulin infusion (P < 0.05) but did not increase with insulin in either group (P > 0.05). Obese non-T2D subjects tended to also display elevated basal ET-1 (P = 0.06). In summary, higher basal skeletal muscle expression of ET-1 and reduced peNOS/eNOS may contribute to a reduced insulin-stimulated leg blood flow response in obese T2D patients. NEW & NOTEWORTHY: Although impairments in endothelial signaling are hypothesized to reduce insulin-stimulated blood flow in type 2 diabetes (T2D), human studies examining these links are limited. We provide the first measures of nitric oxide synthase and endothelin-1 expression from skeletal muscle tissue containing native microvessels in individuals with and without T2D before and during insulin stimulation. Higher basal skeletal muscle expression of endothelin-1 and reduced endothelial nitric oxide phosphorylation (peNOS)/eNOS may contribute to reduced insulin-stimulated blood flow in obese T2D patients.

Red wine enhances glucose-dependent insulinotropic peptide (GIP) and insulin responses in type 2 diabetes during an oral glucose tolerance test.

BACKGROUND: Ingestion of ethanol before a glucose challenge enhances the insulin response by an unknown mechanism. In addition, epidemiological studies consistently indicate that moderate alcohol consumption reduces the risk of developing type 2 diabetes (T2D). The purposes of this study were to evaluate the potential involvement of glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide 1 (GLP-1) in alcohol-induced augmentation of the insulin response and to determine if red wine acutely improves glucose tolerance during an oral glucose tolerance test (OGTT). METHODS: Nine subjects (eight T2D and one pre-diabetes) completed two OGTT 30 min after consumption of 263 ml water or red wine (28 g ethanol). Blood samples were obtained for 3 h and analyzed for glucose, insulin, C-peptide, GIP, and GLP-1. RESULTS: Compared with water, consumption of red wine increased the incremental area under the curve (iAUC) for insulin by 50 % (14,837 ± 4759 vs. 9885 ± 2686 µU/ml × min; p < 0.05) and for GIP by 25 % (7729 ± 1548 vs. 6191 ± 1049 pmol/l × min; p < 0.05). Glucose and GLP-1 responses were not affected by red wine. CONCLUSION: Wine consumption before an OGTT augments the insulin response, which may be partially driven by a greater GIP response. Because glucose levels were not reduced, acute wine consumption may not be effective treatment for enhancing glycemic control or may need to be combined with therapy that improves insulin sensitivity.

Acute inactivity impairs glycemic control but not blood flow to glucose ingestion.

PURPOSE: Insulin-stimulated increases in skeletal muscle blood flow play a role in glucose disposal. Indeed, 7 d of aerobic exercise in patients with Type 2 diabetes increased blood flow responses to an oral glucose tolerance test (OGTT) and improved insulin sensitivity. More recent work suggests that reduced daily physical activity impairs glycemic control (GC) in healthy individuals. Herein, we sought to determine whether an acute reduction in daily activity (from >10,000 to <5000 steps per day) for 5 d (RA5) in healthy individuals reduced insulin-stimulated blood flow and GC in parallel and if a 1-d return to activity (RTA1) improved these outcomes. METHODS: OGTT were performed as a stimulus to increase insulin in 14 healthy, recreationally active men (24 ± 1.1 yr) at baseline, RA5, and RTA1. Measures of insulin sensitivity (Matsuda index) and femoral and brachial artery blood flow were made during the OGTT. Free-living measures of GC including peak postprandial glucose (peak PPG) were also made via continuous glucose monitoring. RESULTS: Femoral and brachial artery blood flow increased during the OGTT but neither was significantly impacted by changes in physical activity (P > 0.05). However, insulin sensitivity was decreased by RA5 (11.3 ± 1.5 to 8.0 ± 1.0, P < 0.05). Likewise, free-living GC measures of peak PPG (113 ± 3 to 123 ± 5 mg·dL(-1), P < 0.05) was significantly increased at RA5. Interestingly, insulin sensitivity and GC as assessed by peak PPG were not restored after RTA1 (P > 0.05). CONCLUSIONS: Thus, acute reductions in physical activity impaired GC and insulin sensitivity; however, blood flow responses to an OGTT were not affected. Further, a 1-d return to activity was not sufficient to normalize GC after 5 d of reduced daily physical activity.