Obesity-Related Metabolic Risk in Sedentary Hispanic Adolescent Girls with Normal BMI.

Hispanic adolescent girls with normal BMI frequently have high body fat %. Without knowledge of body fat content and distribution, their risk for metabolic complications is unknown. We measured metabolic risk indicators and abdominal fat distribution in post-pubertal Hispanic adolescent girls with Normal BMI (N-BMI: BMI < 85th percentile) and compared these indicators between girls with Normal BMI and High Fat content (N-BMI-HF: body fat ≥ 27%; = 15) and Normal BMI and Normal Fat content (N-BMI-NF: body fat < 27%; = 8).

Can metabolic function and physical fitness improve without weight loss for inactive, obese, Hispanic adolescents? A feasibility study.

Introduction: A case series that examines the effects of a 12-week combined resistance and aerobic training program for four sedentary obese, Hispanic adolescents without weight loss.

Subjects/methods: Baseline and post-intervention anthropometric, metabolic and physical fitness measures were obtained. Body composition, hepatic, visceral, and intramuscular fat contents were analyzed via imaging.

Measurements of Gluconeogenesis and Glycogenolysis: A Methodological Review.

Gluconeogenesis is a complex metabolic process that involves multiple enzymatic steps regulated by myriad factors, including substrate concentrations, the redox state, activation and inhibition of specific enzyme steps, and hormonal modulation. At present, the most widely accepted technique to determine gluconeogenesis is by measuring the incorporation of deuterium from the body water pool into newly formed glucose. However, several techniques using radioactive and stable-labeled isotopes have been used to quantitate the contribution and regulation of gluconeogenesis in humans.

Precursors of hexoneogenesis within the human mammary gland.

The human mammary gland is capable of de novo synthesis of glucose and galactose (hexoneogenesis); however, the carbon source is incompletely understood. In this study, we investigated the role of acetate, glutamine, lactate and glycerol as potential carbon sources for hexoneogenesis. Healthy breastfeeding women were studied following a 24-h fast on two occasions separated by 1-3 wk.

De novo synthesis of milk triglycerides in humans.

Unlabelled: Mammary gland (MG) de novo lipogenesis contributes significantly to milk fat in animals but little is known in humans.

Objective: To test the hypothesis that the incorporation of (13)C carbons from [U-(13)C]glucose into fatty acids (FA) and glycerol in triglycerides (TG) will be greater: 1) in milk than plasma TG, 2) during a high-carbohydrate (H-CHO) diet than high-fat (H-FAT) diet, and 3) during feeding than fasting. Seven healthy, lactating women were studied on two isocaloric, isonitrogenous diets.

Effect of ghrelin on glucose regulation in mice.

Improvement of glucose metabolism after bariatric surgery appears to be from the composite effect of the alterations in multiple circulating gut hormone concentrations. However, their individual effect on glucose metabolism during different conditions is not clear. The objective of this study was to determine whether ghrelin has an impact on glycogenolysis, gluconeogenesis, and insulin sensitivity (using a mice model).

Gluconeogenesis is not regulated by either glucose or insulin in extremely low birth weight infants receiving total parenteral nutrition.

Objective: To determine potential factors regulating gluconeogenesis (GNG) in extremely low birth weight infants receiving total parenteral nutrition.

Study Design: Seven infants (birth weight, 0.824 ± 0.

Galactose promotes fat mobilization in obese lactating and nonlactating women.

Background: Galactose consumption as the only carbohydrate source results in little increase in plasma glucose and insulin concentrations when compared with fasting. Lower insulin might promote endogenous lipolysis during meal absorption, which may facilitate fat loss.

Objective: The objective was to test the hypothesis that consumption of an isocaloric, isonitrogenous galactose drink will result in higher rates of lipolysis and fat oxidation than consumption of a glucose drink in obese lactating and nonlactating women.

Gluconeogenesis continues in premature infants receiving total parenteral nutrition.

Objective: To determine the contribution of total gluconeogenesis to glucose production in preterm infants receiving total parenteral nutrition (TPN) providing glucose exceeding normal infant glucose turnover rates.

Study Design: Eight infants (0.955±0.

Strength exercise improves muscle mass and hepatic insulin sensitivity in obese youth.

Introduction: Data on the metabolic effects of resistance exercise (strength training) in adolescents are limited.

Purpose: The objective of this study was to determine whether a controlled resistance exercise program without dietary intervention or weight loss reduces body fat accumulation, increases lean body mass, and improves insulin sensitivity and glucose metabolism in sedentary obese Hispanic adolescents.

Methods: Twelve obese adolescents (age = 15.

Twelve weeks of moderate aerobic exercise without dietary intervention or weight loss does not affect 24-h energy expenditure in lean and obese adolescents.

Background: Exercise might have a persistent effect on energy expenditure and fat oxidation, resulting in increased fat loss. However, even without weight loss, exercise results in positive metabolic effects. The effect of an aerobic exercise program on 24-h total energy expenditure (TEE) and its components-basal (BEE), sleep (SEE), and awake sedentary (SEDEE) energy expenditure and substrate oxidation-has not been studied in lean and obese adolescents.

Aerobic exercise increases peripheral and hepatic insulin sensitivity in sedentary adolescents.

Context: Data are limited on the effects of controlled aerobic exercise programs (without weight loss) on insulin sensitivity and glucose metabolism in children and adolescents.

Objective: To determine whether a controlled aerobic exercise program (without weight loss) improves peripheral and hepatic insulin sensitivity and affects glucose production (GPR), gluconeogenesis and glycogenolysis in sedentary lean and obese Hispanic adolescents.

Patients And Design: Twenty-nine post-pubertal adolescents (14 lean: 15.

A 12-week aerobic exercise program reduces hepatic fat accumulation and insulin resistance in obese, Hispanic adolescents.

The rise in obesity-related morbidity in children and adolescents requires urgent prevention and treatment strategies. Currently, only limited data are available on the effects of exercise programs on insulin resistance, and visceral, hepatic, and intramyocellular fat accumulation. We hypothesized that a 12-week controlled aerobic exercise program without weight loss reduces visceral, hepatic, and intramyocellular fat content and decreases insulin resistance in sedentary Hispanic adolescents.

Mechanisms to conserve glucose in lactating women during a 42-h fast.

Little is known about how lactating women accommodate for their increased glucose demands during fasting to avoid maternal hypoglycemia. The objective of this study was to determine whether lactating women conserve plasma glucose by reducing maternal glucose utilization by increasing utilization of FFA and ketone bodies and/or increasing gluconeogenesis and mammary gland hexoneogenesis. Six healthy exclusively breastfeeding women and six nonlactating controls were studied during 42 h of fasting and 6 h of refeeding.

Contribution of galactose and fructose to glucose homeostasis.

To determine the contributions of galactose and fructose to glucose formation, 6 subjects (26 +/- 2 years old; body mass index, 22.4 +/- 0.2 kg/m(2)) (mean +/- SE) were studied during fasting conditions.

Effect of dietary macronutrient composition under moderate hypocaloric intake on maternal adaptation during lactation.

Background: No evidence-based recommendations exist concerning what dietary macronutrient composition optimizes weight loss during lactation while maintaining milk production.

Objectives: The study was designed to test the following hypotheses: compared with a reduced-calorie, high-carbohydrate (H-CHO) diet, an isonitrogenous, isocaloric high-fat (H-F) diet will decrease milk production and carbohydrate oxidation, increase gluconeogenesis and hexoneogenesis, and not affect energy balance.

Design: Seven healthy lactating mothers and their infants were studied on 2 occasions in random order for 8 d separated by 1-2 wk.

beta-Cell function and insulin sensitivity in adolescents from an OGTT.

Given the increase in the incidence of insulin resistance, obesity, and type 2 diabetes in children and adolescents, it would be of paramount importance to assess quantitative indices of insulin secretion and action during a physiological perturbation, such as a meal or an oral glucose-tolerance test (OGTT). A minimal model method is proposed to measure quantitative indices of insulin secretion and action in adolescents from an oral test. A 7 h, 21-sample OGTT was performed in 11 adolescents.

Gene expression in the human mammary epithelium during lactation: the milk fat globule transcriptome.

The molecular physiology underlying human milk production is largely unknown because of limitations in obtaining tissue samples. Determining gene expression in normal lactating women would be a potential step toward understanding why some women struggle with or fail at breastfeeding their infants. Recently, we demonstrated the utility of RNA obtained from breast milk fat globule (MFG) to detect mammary epithelial cell (MEC)-specific gene expression.

Short-term high dietary fructose intake had no effects on insulin sensitivity and secretion or glucose and lipid metabolism in healthy, obese adolescents.

Unlabelled: There is virtually no information on the metabolic impact of dietary fructose intake in adolescents despite their high fructose consumption, particularly via sweetened beverages.

Aim: To determine the short-term metabolic effects of dietary fructose intake in obese adolescents.

Methods: Six volunteers (3 M/3 F; 15.

Short-term effects of recombinant human growth hormone and feeding on gluconeogenesis in humans.

After a short-term fast, lactating women have increased rates of glucose production but not gluconeogenesis (GNG) despite relative hypoinsulinemia. We explored the effects of non-insulin-dependent increase in glucose utilization and recombinant human growth hormone (rhGH) on glucose production, glycogenolysis, and GNG in both the fed and overnight-fasted condition. Six controls and 7 lactating women were studied twice, in random order, after 7 days of saline or rhGH.

Glucose fluxes during OGTT in adolescents assessed by a stable isotope triple tracer method.

Unlabelled: Virtually no information is available on glucose fluxes during a meal or glucose ingestion in adolescents.

Aim: To use a triple tracer approach to measure rates of appearance of ingested glucose (Ra(ogtt)), endogenous glucose production (EGP) and glucose disappearance (Rd) following an oral glucose bolus in adolescents.

Methods: Eleven adolescents (4 M/7 F, 15 +/- 1 yr; 67.

Measurement of gluconeogenesis using glucose fragments and mass spectrometry after ingestion of deuterium oxide.

We report a new method to measure the fraction of glucose derived from gluconeogenesis using gas chromatography-mass spectrometry and positive chemical ionization. After ingestion of deuterium oxide by subjects, glucose derived from gluconeogenesis is labeled with deuterium. Our calculations of gluconeogenesis are based on measurements of the average enrichment of deuterium on carbon 1, 3, 4, 5, and 6 of glucose and the deuterium enrichment in body water.

Regulation of gene expression in human mammary epithelium: effect of breast pumping.

Little is known of the molecular regulation of human milk production because of limitations in obtaining mammary tissue from lactating women. Our objectives were to evaluate whether RNA isolated from breast milk fat globules (MFGs) could be an alternative to mammary biopsies and to determine whether intense breast pumping, which increases prolactin (PRL) secretion, will upregulate alpha-lactalbumin (alpha-LA, a major determinant of lactose synthesis) transcription. RNA was isolated from MFG and transcripts of interest were identified and quantitated by real-time RT-PCR using an external standard for normalization.

Dietary glutamate is almost entirely removed in its first pass through the splanchnic bed in premature infants.

Breast milk glutamate is a potential gluconeogenic substrate. However, in piglets, most dietary glutamate undergoes first pass extraction by the gut, limiting its contribution to glucose formation. The objectives of the study were to determine in preterm infants, whether dietary glutamate increases plasma [glutamate] in a dose-dependent fashion and whether glutamate carbon appears in plasma glucose to an appreciable extent.

Methionine transmethylation and transsulfuration in the piglet gastrointestinal tract.

Methionine is an indispensable sulfur amino acid that functions as a key precursor for the synthesis of homocysteine and cysteine. Studies in adult humans suggest that splanchnic tissues convert dietary methionine to homocysteine and cysteine by means of transmethylation and transsulfuration, respectively. Studies in piglets show that significant metabolism of dietary indispensable amino acids occurs in the gastrointestinal tissues (GIT), yet the metabolic fate of methionine in GIT is unknown.