Citations

AbstractContext:Both training and normal body mass index are associated with high insulin sensitivity, but the mechanism may be different.Objective:The aim of the study was to examine whether lean trained humans may be protected from acute free fatty acid (FFA)-induced insulin resistance compared with lean sedentary humans.Design and Setting:We conducted an interventional trial using either a 6-h lipid (20% Intralipid at 90 ml/h) or glycerol (2.25 g/100 ml at 90 ml/h) infusion along with a concurrent hyperinsulinemic-euglycemic clamp and serial muscle biopsies (0, 120, 360 min) at a clinical research unit at the University of Minnesota.Patients or Participants:The study included lean endurance-trained (n = 14) and sedentary (n = 14) individuals matched for age, gender, and body mass index.Main Outcome Measures:We measured the decline in glucose infusion rate (GIR) during the hyperinsulinemic-euglycemic clamp.Results:The trained group had higher baseline mitochondrial DNA copy number, mRNA of cytochrome C oxidase subunit 3, and insulin sensitivity (as measured by GIR) compared with the sedentary group. When FFA was acutely elevated to the upper physiological range (0.6–0.7 mEq/liter) by lipid infusion, the GIR in both activity groups declined similarly compared with their respective glycerol controls, although insulin signaling, as measured by Ser 473 pAKT/AKT, remained comparable. Specific to the trained group, the stimulatory effect of hyperinsulinemia on mitochondrial mRNA levels during the glycerol infusion was absent during the lipid infusion.Conclusions:Elevated FFA had similar effects in reducing insulin sensitivity in trained and sedentary humans. In trained participants, this decline was associated with alterations in the skeletal muscle mitochondrial mRNA response to hyperinsulinemia.

When consumed separately, whey protein (WP) is more rapidly absorbed into circulation than casein (Cas), which prompted the concept of rapid and slow dietary protein. It is unclear whether these proteins have similar metabolic fates when coingested as in milk. We determined the rate of appearance across the splanchnic bed and the rate of disappearance across the leg of phenylalanine (Phe) from coingested, intrinsically labeled WP and Cas. Either [15N]Phe or [13C- ring C6]Phe was infused in lactating cows, and the labeled WP and Cas from their milk were collected. To determine the fate of Phe derived from different protein sources, 18 healthy participants were studied after ingestion of one of the following: 1) [15N]WP, [13C]Cas, and lactose; 2) [13C]WP, [15N]Cas, and lactose; 3) lactose alone. At 80–120 min, the rates of appearance (Ra) across the splanchnic bed of Phe from WP and Cas were similar [0.068 ± 0.010 vs. 0.070 ± 0.009%/min; not significant (ns)]. At time 220–260 min, Phe appearance from WP had slowed (0.039 ± 0.008%/min, P < 0.05) whereas Phe appearance from Cas was sustained (0.068 ± 0.013%/min). Similarly, accretion rates across the leg of Phe absorbed from WP and Cas were not different at 80–120 min (0.011 ± 0.002 vs. 0.012 ± 0.003%/min; ns), but they were significantly lower for WP (0.007 ± 0.002%/min) at 220–260 min than for Cas (0.013 ± 0.002%/min) at 220–260 min. Early after meal ingestion, amino acid absorption and retention across the leg were similar for WP and Cas, but as rates for WP waned, absorption and assimilation into skeletal muscle were better retained for Cas.

AbstractContext:Hyperandrogenism and oxidative stress are related in polycystic ovary syndrome (PCOS), but it is unknown whether hyperandrogenemia can activate oxidative stress.Objective:The purpose of this study was to determine the effect of oral androgen administration on fasting and glucose-stimulated leukocytic reactive oxygen species (ROS) generation, reduced nicotinamide adenine dinucleotide phosphate oxidase p47phox subunit gene expression, and plasma thiobarbituric acid-reactive substances (TBARS) in lean healthy reproductive-age women.Participants, Design, and Setting:Sixteen lean healthy ovulatory reproductive-age women were treated with 130 mg dehydroepiandrosterone (DHEA) or placebo (n = 8 each) for 5 d in this randomized, controlled, double-blind study that was performed at an an academic medical center.Main Outcome Measures:Leukocytic ROS generation, p47phox gene expression, and plasma TBARS were quantified in the fasting state and 2 h after glucose ingestion, before and after treatment.Results:Before treatment, subjects receiving DHEA or placebo exhibited no differences in androgens or any prooxidant markers while fasting and after glucose ingestion. Compared with placebo, DHEA administration raised levels of testosterone, androstenedione, and DHEA-sulfate, increased the percent change in glucose-challenged p47phox RNA content, and increased the percent change in fasting and glucose-challenged ROS generation from mononuclear cells and polymorphonuclear cells, p47phox protein content, and plasma TBARS.Conclusion:Elevation of circulating androgens comparable to what is present in PCOS increases leukocytic ROS generation, p47phox gene expression, and plasma TBARS to promote oxidative stress in lean healthy reproductive-age women. Thus, hyperandrogenemia activates and sensitizes leukocytes to glucose in this population.

Insulin regulates many cellular processes, but the full impact of insulin deficiency on cellular functions remains to be defined. Applying a mass spectrometry–based nontargeted metabolomics approach, we report here alterations of 330 plasma metabolites representing 33 metabolic pathways during an 8-h insulin deprivation in type 1 diabetic individuals. These pathways included those known to be affected by insulin such as glucose, amino acid and lipid metabolism, Krebs cycle, and immune responses and those hitherto unknown to be altered including prostaglandin, arachidonic acid, leukotrienes, neurotransmitters, nucleotides, and anti-inflammatory responses. A significant concordance of metabolome and skeletal muscle transcriptome–based pathways supports an assumption that plasma metabolites are chemical fingerprints of cellular events. Although insulin treatment normalized plasma glucose and many other metabolites, there were 71 metabolites and 24 pathways that differed between nondiabetes and insulin-treated type 1 diabetes. Confirmation of many known pathways altered by insulin using a single blood test offers confidence in the current approach. Future research needs to be focused on newly discovered pathways affected by insulin deficiency and systemic insulin treatment to determine whether they contribute to the high morbidity and mortality in T1D despite insulin treatment.

Hyperandrogenism and chronic low-grade inflammation are related in polycystic ovary syndrome (PCOS), but it is unknown whether hyperandrogenemia can activate inflammation. We determined the effect of oral androgen administration on fasting and glucose-stimulated nuclear factor-κB (NF-κB) activation and expression and related markers of inflammation in mononuclear cells (MNC) of lean reproductive-age women. Sixteen lean, ovulatory reproductive-age women were treated with 130 mg of DHEA or placebo ( n = 8 each) for 5 days in a randomized, controlled, double-blind fashion. Nuclear activation of NF-κB, p65 and p105 NF-κB subunit RNA, TNFα and IL-1β mRNA, and NF-κB p65 and inhibitory-κB (IκB) protein were quantified from MNC obtained while fasting and 2 h after glucose ingestion, before and after DHEA or placebo administration. Before treatment, subjects receiving DHEA or placebo exhibited no differences in androgens or any inflammatory markers while fasting and after glucose ingestion. Compared with placebo, DHEA administration raised levels of testosterone, androstenedione, and DHEA-S, increased the percent change in fasting and glucose-challenged activated NF-κB, p65, p105, TNFα, and IL-1β RNA and p65 protein, and decreased the percent change in fasting and glucose-challenged IκB protein. We conclude that elevation of circulating androgens to the range observed in PCOS upregulates the NF-κB inflammation pathway in lean reproductive-age women. Thus, hyperandrogenemia activates and sensitizes MNC to glucose in this population.

Background— Although older patients frequently undergo percutaneous coronary interventions (PCI), frailty, comorbidity, and quality of life are seldom part of risk prediction approaches. We assessed their incremental prognostic value over and above the risk factors in the Mayo Clinic risk score. Methods and Results— Patients ≥65 years who underwent PCI were assessed for frailty (Fried criteria), comorbidity (Charlson index), and quality of life [SF-36]. Of the 628 discharged [median follow-up of 35.0 months (interquartile range, 22.7 to 42.9)], 78 died and 72 had a myocardial infarction (MI). Three-year mortality was 28% for frail patients, 6% for nonfrail patients. The respective 3-year rates of death or MI were 41% and 17%. After adjustment, frailty [hazard ratio (HR), 4.19 [95% confidence interval (CI), 1.85, 9.51], physical component score of the SF-36 (HR, 1.59; 95% CI, 1.24 to 2.02), and comorbidity, (HR, 1.10; 95% CI, 1.05, 1.16) were associated with mortality. Frailty was associated with mortality/MI (HR, 2.61, 1.52, 4.50). Models with conventional Mayo Clinic risk score had C-statistics of 0.628, 0.573 for mortality and mortality/MI, respectively. Adding frailty, quality of life, and comorbidity, the C-statistic was (0.675, 0.694, 0.671) for mortality and (0.607, 0.587, 0.576) for mortality/MI, respectively. Including frailty, comorbidities and SF-36, conferred a discernible improvement to predict death and death/MI (integrated discrimination improvement, 0.027 and 0.016, and net reclassification improvement of 43% and 18%, respectively). Conclusions— After PCI, frailty, comorbidity and poor quality of life are prevalent and are associated with adverse long-term outcomes. Their inclusion improves the discriminatory ability of the Mayo Clinic risk score derived from the routine cardiovascular risk factors.