35 results on '"Jéquier, E."'
Search Results
2. Thermogenic effect of thyroid hormones: interactions with epinephrine and insulin.
- Author
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Piolino, V, primary, Acheson, K J, additional, Müller, M J, additional, Jeanprêtre, N, additional, Burger, A G, additional, and Jéquier, E, additional
- Published
- 1990
- Full Text
- View/download PDF
3. Effect of physical exercise on glycogen turnover and net substrate utilization according to the nutritional state.
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SCHNEITER, P., DI VETTA, V., JÉQUIER, E., and TAPPY, L.
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- 1995
- Full Text
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4. Inhibition of Na+-K+-ATPase by digoxin and its relation with energy expenditure and nutrient oxidation rate.
- Author
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SCHUTZ, Y., BUCLIN, T., JÉQUIER, E., and DERIAZ, O.
- Published
- 1995
5. Whole body protein metabolism and resting energy expenditure in pregnant Gambian women.
- Author
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WILLOMMET, L., SCHUTZ, Y., WHITEHEAD, R., JÉQUIER, E., and FERN, E. B.
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- 1992
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6. Thermogenesis in obese women: effect of fructose vs. glucose added to a meal.
- Author
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SCHWARZ, J. -M., SCHUTZ, Y., PIOLINO, V., SCHNEIDER, H., FELBER, J. -P., and JÉQUIER, E.
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- 1992
- Full Text
- View/download PDF
7. Thermogenesis and fructose metabolism in humans.
- Author
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SCHWARZ, J.-M., ACHESON, K. J., TAPPY, L., PIOLINO, V., MÜLLER, M. J., FELBER, J. P., and JÉQUIER, E.
- Published
- 1992
- Full Text
- View/download PDF
8. Free-living energy expenditure measured by two independent techniques in pregnant and nonpregnant Gambian women.
- Author
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HEINI, A., SCHUTZ, Y., DIAZ, E., PRENTICE, A. M., WHITEHEAD, R. G., and JÉQUIER, E.
- Published
- 1991
- Full Text
- View/download PDF
9. Effects of dopamine on total oxygen consumption and oxygen delivery in healthy men.
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RUTTIMANN, Y., CHIOLÉRO, R., JÉQUIER, E., BREITENSTEIN, E., and SCHUTZ, Y.
- Published
- 1989
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10. Impairment of glucose disposal by infusion of triglycerides in humans: role of glycemia.
- Author
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FELLEY, C. P., FELLEY, E. M., VAN MELLE, G. D., FRASCAROLO, P., JÉQUIER, E., and FELBER, J.-P.
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- 1989
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11. Epinephrine sensitivity with respect to metabolic rate and other variables in women.
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SJÖSTRÖM, L., SCHUTZ, Y., GUDINCHET, F., HEGNELL, L., PITTET, P. G., and JÉQUIER, E.
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- 1983
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12. Increased thermal body insulation: relationship to the development of obesity
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A Vannotti, P H Gygax, Jéquier E, and Ph. Pittet
- Subjects
Adult ,Time Factors ,Physiology ,business.industry ,Body Weight ,Energy metabolism ,Skin temperature ,Calorimetry ,medicine.disease ,Body weight ,Obesity ,Cold Temperature ,Physiology (medical) ,medicine ,Humans ,Female ,Food science ,Energy Metabolism ,Skin Temperature ,business ,Body Temperature Regulation ,Skin - Published
- 1974
13. Increased thermal body insulation: relationship to the development of obesity.
- Author
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Jéquier, E, primary, Gygax, P H, additional, Pittet, P, additional, and Vannotti, A, additional
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- 1974
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14. Human calorimeter with a new type of gradient layer.
- Author
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Spinnler, G, primary, Jéquier, E, additional, Favre, R, additional, Dolivo, M, additional, and Vannotti, A, additional
- Published
- 1973
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15. Efficiency of free energy use for muscular work.
- Author
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Jéquier, E.
- Published
- 1986
16. Role of Na+-K+-ATPase in insulin-induced lactate release by skeletal muscle.
- Author
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Novel-Chaté V, Rey V, Chioléro R, Schneiter P, Leverve X, Jéquier E, and Tappy L
- Subjects
- Adult, Blood Glucose analysis, Enzyme Inhibitors pharmacology, Humans, Insulin blood, Lactic Acid antagonists & inhibitors, Lactic Acid blood, Microdialysis, Osmolar Concentration, Ouabain pharmacology, Time Factors, Insulin pharmacology, Lactic Acid metabolism, Muscle, Skeletal metabolism, Sodium-Potassium-Exchanging ATPase physiology
- Abstract
Hyperinsulinemia increases lactate release by various organs and tissues. Whereas it has been shown that aerobic glycolysis is linked to Na+-K+-ATPase activity, we hypothesized that stimulation by insulin of skeletal muscle Na+-K+-ATPase is responsible for increased muscle lactate production. To test this hypothesis, we assessed muscle lactate release in healthy volunteers from the [13C]lactate concentration in the effluent dialysates of microdialysis probes inserted into the tibialis anterior muscles on both sides and infused with solutions containing 5 mmol/l [U-13C]glucose. On one side, the microdialysis probe was intermittently infused with the same solution additioned with 2.10(-5) M ouabain. In the basal state, [13C]lactate concentration in the dialysate was not affected by ouabain. During a euglycemic-hyperinsulinemic clamp, [13C]lactate concentration increased by 135% in the dialysate without ouabain, and this stimulation was nearly entirely reversed by ouabain (56% inhibition compared with values in the dialysate collected from the contralateral probe). These data indicate that insulin stimulates muscle lactate release by activating Na+-K+-ATPase in healthy humans.
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- 2001
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17. Effects of fructose on hepatic glucose metabolism in humans.
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Dirlewanger M, Schneiter P, Jéquier E, and Tappy L
- Subjects
- Adult, Blood Glucose, Carbon Isotopes, Deuterium, Female, Fructose administration & dosage, Glucagon administration & dosage, Glucose Clamp Technique, Glucose-6-Phosphate metabolism, Humans, Hyperglycemia chemically induced, Hyperglycemia metabolism, Infusions, Intravenous, Insulin administration & dosage, Insulin blood, Liver drug effects, Male, Somatostatin administration & dosage, Uridine Diphosphate Glucose metabolism, Fructose metabolism, Glucose metabolism, Liver metabolism
- Abstract
Hepatic and extrahepatic insulin sensitivity was assessed in six healthy humans from the insulin infusion required to maintain an 8 mmol/l glucose concentration during hyperglycemic pancreatic clamp with or without infusion of 16.7 micromol. kg(-1). min(-1) fructose. Glucose rate of disappearance (GR(d)), net endogenous glucose production (NEGP), total glucose output (TGO), and glucose cycling (GC) were measured with [6,6-(2)H(2)]- and [2-(2)H(1)]glucose. Hepatic glycogen synthesis was estimated from uridine diphosphoglucose (UDPG) kinetics as assessed with [1-(13)C]galactose and acetaminophen. Fructose infusion increased insulin requirements 2.3-fold to maintain blood glucose. Fructose infusion doubled UDPG turnover, but there was no effect on TGO, GC, NEGP, or GR(d) under hyperglycemic pancreatic clamp protocol conditions. When insulin concentrations were matched during a second hyperglycemic pancreatic clamp protocol, fructose administration was associated with an 11.1 micromol. kg(-1). min(-1) increase in TGO, a 7.8 micromol. kg(-1). min(-1) increase in NEGP, a 2.2 micromol. kg(-1). min(-1) increase in GC, and a 7.2 micromol. kg(-1). min(-1) decrease in GR(d) (P < 0. 05). These results indicate that fructose infusion induces hepatic and extrahepatic insulin resistance in humans.
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- 2000
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18. Effects of mental stress on insulin-mediated glucose metabolism and energy expenditure in lean and obese women.
- Author
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Seematter G, Guenat E, Schneiter P, Cayeux C, Jéquier E, and Tappy L
- Subjects
- Adrenergic beta-Antagonists administration & dosage, Adult, Blood Pressure drug effects, Blood Pressure physiology, Cardiac Output drug effects, Cardiac Output physiology, Energy Metabolism physiology, Epinephrine blood, Female, Heart Rate drug effects, Heart Rate physiology, Humans, Infusions, Intravenous, Lactic Acid blood, Norepinephrine blood, Oxygen Consumption drug effects, Oxygen Consumption physiology, Propranolol administration & dosage, Sympathetic Nervous System metabolism, Vascular Resistance drug effects, Vascular Resistance physiology, Glucose metabolism, Insulin blood, Obesity blood, Stress, Psychological blood, Thinness blood
- Abstract
The effects of the sympathetic activation elicited by a mental stress on insulin sensitivity and energy expenditure (VO(2)) were studied in 11 lean and 8 obese women during a hyperinsulinemic-euglycemic clamp. Six lean women were restudied under nonselective beta-adrenergic blockade with propranolol to determine the role of beta-adrenoceptors in the metabolic response to mental stress. In lean women, mental stress increased VO(2) by 20%, whole body glucose utilization ([6,6-(2)H(2)]glucose) by 34%, and cardiac index (thoracic bioimpedance) by 25%, whereas systemic vascular resistance decreased by 24%. In obese women, mental stress increased energy expenditure as in lean subjects, but it neither stimulated glucose uptake nor decreased systemic vascular resistance. In the six lean women who were restudied under propranolol, the rise in VO(2), glucose uptake, and cardiac output and the decrease in systemic vascular resistance during mental stress were all abolished. It is concluded that 1) in lean subjects, mental stress stimulates glucose uptake and energy expenditure and produces vasodilation; activation of beta-adrenoceptors is involved in these responses; and 2) in obese patients, the effects of mental stress on glucose uptake and systemic vascular resistance, but not on energy expenditure, are blunted.
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- 2000
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19. Regulation of body weight in humans.
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Jéquier E and Tappy L
- Subjects
- Adult, Animals, Humans, Leptin, Adipose Tissue physiology, Body Weight, Obesity physiopathology, Proteins physiology
- Abstract
The mechanisms involved in body weight regulation in humans include genetic, physiological, and behavioral factors. Stability of body weight and body composition requires that energy intake matches energy expenditure and that nutrient balance is achieved. Human obesity is usually associated with high rates of energy expenditure. In adult individuals, protein and carbohydrate stores vary relatively little, whereas adipose tissue mass may change markedly. A feedback regulatory loop with three distinct steps has been recently identified in rodents: 1) a sensor that monitors the size of adipose tissue mass is represented by the amount of leptin synthesized by adipose cells (a protein encoded by the ob gene) which determines the plasma leptin levels; 2) hypothalamic centers, with specific leptin receptors, which receive and integrate the intensity of the signal; and 3) effector systems that influence the two determinants of energy balance, i.e., energy intake and energy expenditure. With the exception of a few very rare cases, the majority of obese human subjects have high plasma leptin levels that are related to the size of their adipose tissue mass. However, the expected regulatory responses (reduction in food intake and increase in energy expenditure) are not observed in obese individuals. Thus obese humans are resistant to the effect of endogenous leptin, despite unaltered hypothalamic leptin receptors. Whether defects in the leptin signaling cascade play a role in the development of human obesity is a field of great actual interest that needs further research. Present evidences suggest that genetic and environmental factors influence eating behavior of people prone to obesity and that diets that are high in fat or energy dense undermine body weight regulation by promoting an overconsumption of energy relative to need.
- Published
- 1999
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20. Effects of caffeine on energy metabolism, heart rate, and methylxanthine metabolism in lean and obese women.
- Author
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Bracco D, Ferrarra JM, Arnaud MJ, Jéquier E, and Schutz Y
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- Adult, Basal Metabolism drug effects, Body Temperature Regulation drug effects, Catecholamines urine, Cytochrome P-450 CYP1A2, Cytochrome P-450 Enzyme System metabolism, Female, Humans, Oxidoreductases metabolism, Reference Values, Respiration drug effects, Respiratory Function Tests, Saliva metabolism, Caffeine pharmacology, Energy Metabolism drug effects, Heart Rate drug effects, Obesity metabolism, Xanthines metabolism
- Abstract
The magnitude of coffee-induced thermogenesis and the influence of coffee ingestion on substrate oxidation were investigated in 10 lean and 10 obese women, over two 24-h periods in a respiratory chamber. On one occasion the subjects consumed caffeinated coffee and on the other occasion, decaffeinated coffee. The magnitude of thermogenesis was smaller in obese (4.9 +/- 2.0%) than in lean subjects (7.6 +/- 1.3%). The thermogeneic response to caffeine was prolonged during the night in lean women only. The coffee-induced stimulation of energy expenditure was mediated by a concomitant increase in lipid and carbohydrate oxidation. During the next day, in postabsorptive basal conditions, the thermogenic effect of coffee had vanished, but a significant increase in lipid oxidation was observed in both groups. The magnitude of this effect was, however, blunted in obese women (lipid oxidation increased by 29 and 10% in lean and obese women, respectively). Caffeine increased urinary epinephrine excretion. Whereas urinary caffeine excretion was similar in both groups, obese women excreted more theobromine, theophylline, and paraxanthine than lean women. Despite the high levels of urinary methylxanthine excretion, thermogenesis and lipid oxidation were less stimulated in obese than in lean subjects.
- Published
- 1995
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21. Inhibition of Na(+)-K(+)-ATPase by digoxin and its relation with energy expenditure and nutrient oxidation rate.
- Author
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Lyon X, Schutz Y, Buclin T, Jéquier E, and Dériaz O
- Subjects
- Adult, Basal Metabolism drug effects, Blood Glucose metabolism, Blood Pressure drug effects, Calorimetry, Digoxin pharmacokinetics, Fatty Acids, Nonesterified blood, Heart Rate drug effects, Humans, Insulin blood, Lactates metabolism, Male, Oxygen Consumption drug effects, Potassium blood, Reference Values, Regression Analysis, Sodium blood, Digoxin pharmacology, Energy Metabolism drug effects, Sodium-Potassium-Exchanging ATPase antagonists & inhibitors
- Abstract
This study investigates the effects of digoxin, an inhibitor of the Na+ pump (Na(+)-K(+)-ATPase), on resting metabolic rate (RMR), respiratory quotient (RQ), and nutrient oxidation rate. Twelve healthy male subjects followed a double-blind protocol design and received either 1 mg/day digoxin or a placebo 2 days before indirect calorimetry measurements. Digoxin induced a 0.22 +/- 0.07 kJ/min or 3.8 +/- 1.5% (mean +/- SE, P = 0.01) decrease in RMR and a 0.40 +/- 0.13 kJ/min (P = 0.01) decrease in fat oxidation rate, whereas carbohydrate and protein oxidation rates did not change significantly. A dose-response relationship between serum digoxin and RQ was observed. These results suggest that digoxin reduces not only RMR but also fat oxidation rate by mechanisms that remain to be elucidated. Because a linkage and an association between genes coding the Na(+)-K(+)-ATPase and the RQ have been previously observed, the present demonstration of an effect of Na(+)-K(+)-ATPase inhibition on fat oxidation rate strengthens the concept that the activity of this enzyme may play a role in body weight regulation.
- Published
- 1995
- Full Text
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22. Resting metabolic rate and protein turnover in apparently healthy elderly Gambian men.
- Author
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Benedek C, Berclaz PY, Jéquier E, and Schutz Y
- Subjects
- Adult, Aged, 80 and over, Basal Metabolism, Body Composition, Gambia, Humans, Male, Middle Aged, Reference Values, Aged, Aging metabolism, Energy Metabolism, Proteins metabolism
- Abstract
Body composition, resting energy expenditure (REE), and whole body protein metabolism were studied in 26 young and 28 elderly Gambian men matched for body mass index during the dry season in a rural village in The Gambia. REE was measured by indirect calorimetry (hood system) in the fasting state and after five successive meals. Rates of whole body nitrogen flux, protein synthesis, and protein breakdown were determined in the fed state from the level of isotopic enrichment of urinary ammonia over a period of 12 h after a single oral dose of [15N]glycine. Expressed in absolute value, REE was significantly lower in the elderly compared with the young group (3.21 +/- 0.07 vs. 4.04 +/- 0.07 kJ/min, P < 0.001) and when adjusted to body weight (3.29 +/- 0.05 vs. 3.96 +/- 0.05 kJ/min, P < 0.0001) and fat-free mass (FFM; 3.38 +/- 0.01 vs. 3.87 +/- 0.01 kJ/min, P < 0.0001). The rate of protein synthesis averaged 207 +/- 13 g protein/day in the elderly and 230 +/- 13 g protein/day in the young group, whereas protein breakdown averaged 184 +/- 13 g protein/day in the elderly and 203 +/- 13 g protein/day in the young group (nonsignificant). When values were adjusted for body weight or FFM, they did not reveal any difference between the two groups. It is concluded that the reduced REE adjusted for body composition observed in elderly Gambian men is not explained by a decrease in protein turnover.
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- 1995
- Full Text
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23. Effects of lactate on glucose metabolism in healthy subjects and in severely injured hyperglycemic patients.
- Author
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Tappy L, Cayeux MC, Schneiter P, Schindler C, Temler E, Jéquier E, and Chioléro R
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- Adolescent, Adult, Aged, Blood Glucose analysis, Critical Illness, Energy Metabolism, Female, Homeostasis, Humans, Insulin blood, Lactates administration & dosage, Lactates blood, Lactic Acid, Liver metabolism, Male, Middle Aged, Parenteral Nutrition, Total, Reference Values, Glucose metabolism, Hyperglycemia etiology, Hyperglycemia metabolism, Lactates pharmacology, Wounds and Injuries complications
- Abstract
Hepatic glucose production is autoregulated during infusion of gluconeogenic precursors. In hyperglycemic patients with multiple trauma, hepatic glucose production and gluconeogenesis are increased, suggesting that autoregulation of hepatic glucose production may be defective. To better understand the mechanisms of autoregulation and its possible alterations in metabolic stress, lactate was coinfused with glucose in healthy volunteers and in hyperglycemic patients with multiple trauma or critical illness. In healthy volunteers, infusion of glucose alone nearly abolished endogenous glucose production. Lactate increased gluconeogenesis (as indicated by a decrease in net carbohydrate oxidation with no change in total [13C]carbohydrate oxidation) but did not increase endogenous glucose production. In patients with metabolic stress, endogenous glucose production was not suppressed by exogenous glucose, but lactate did not further increase hepatic glucose production. It is concluded that 1) in healthy humans, autoregulation of hepatic glucose production during infusion of lactate is still present when glycogenolysis is suppressed by exogenous glucose and 2) autoregulation of hepatic glucose production is not abolished in hyperglycemic patients with metabolic stress.
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- 1995
- Full Text
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24. Effects of infused fructose on endogenous glucose production, gluconeogenesis, and glycogen metabolism.
- Author
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Tounian P, Schneiter P, Henry S, Jéquier E, and Tappy L
- Subjects
- Adult, Carbohydrate Metabolism, Energy Metabolism, Female, Fructose metabolism, Hormones blood, Humans, Infusions, Intravenous, Oxidation-Reduction, Fructose pharmacology, Gluconeogenesis drug effects, Glucose biosynthesis, Glycogen metabolism
- Abstract
To determine the mechanisms that prevent an increase in gluconeogenesis from increasing hepatic glucose output, six healthy women were infused with [1-13C]fructose (22 mumol.kg-1.min-1), somatostatin, insulin, and glucagon. In control experiment, non-13C-enriched fructose was infused at the same rate without somatostatin, and [U-13C]glucose was infused to measure specifically plasma glucose oxidation. Endogenous glucose production (EGP, [6,6-2H]glucose), net carbohydrate oxidation (CHOox, indirect calorimetry), and fructose oxidation (13CO2) were measured. EGP rate did not increase after fructose infusion with (13.1 +/- 1.2 vs. 12.9 +/- 0.3 mumol.kg-1.min-1) and without (10.3 +/- 0.5 vs. 9.7 +/- 0.5 mumol.kg-1.min-1) somatostatin, despite the fact that gluconeogenesis increased. Nonoxidative fructose disposal, corresponding mainly to glycogen synthesis, was threefold net glycogen deposition, the latter calculated as fructose infusion minus CHOox (14.8 +/- 1.1 and 4.3 +/- 2.0 mumol.kg-1.min-1). It is concluded that 1) the mechanism by which EGP remains constant when gluconeogenesis from fructose increases is independent of changes in insulin and 2) simultaneous breakdown and synthesis of glycogen occurred during fructose infusion.
- Published
- 1994
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25. Effect of ethanol on energy expenditure.
- Author
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Suter PM, Jéquier E, and Schutz Y
- Subjects
- Acetates blood, Adult, Body Temperature Regulation drug effects, Calorimetry, Indirect, Ethanol blood, Fatty Acids, Nonesterified blood, Humans, Male, Osmolar Concentration, Energy Metabolism drug effects, Ethanol pharmacology
- Abstract
The thermogenic response induced by ethanol ingestion in humans has not been extensively studied. This study was designed to determine the thermic effect of ethanol added to a normal diet in healthy nonalcoholic subjects, using indirect calorimetry measurements over a 24-h period in a respiration chamber. The thermic effect of ethanol was also measured when ethanol was ingested in the fasting state, using a ventilated hood system during a 5-h period. Six subjects ingested 95.6 +/- 1.8 (SE) g ethanol in 1 day partitioned over three meals; there was a 5.5 +/- 1.2% increase in 24-h energy expenditure compared with a control day in which all conditions were identical except that no ethanol was consumed. The calculated ethanol-induced thermogenesis (EIT) was 22.5 +/- 4.7% of the ethanol energy ingested. Ingestion of 31.9 +/- 0.6 g ethanol in the fasting state led to a 7.4 +/- 0.6% increase in energy expenditure over baseline values, and the calculated EIT was 17.1 +/- 2.2%. It is concluded that in healthy nonalcoholic adults ethanol elicits a thermogenic response equal to approximately 20% of the ethanol energy. Thus the concept of the apparently inefficient utilization of ethanol energy is supported by these results which show that only approximately 80% of the ethanol energy is used as metabolizable energy for biochemical processes in healthy nonalcoholic moderate ethanol consumers.
- Published
- 1994
- Full Text
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26. Effects of adrenergic and cholinergic blockade on insulin-induced stimulation of calf blood flow in humans.
- Author
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Randin D, Vollenweider P, Tappy L, Jéquier E, Nicod P, and Scherrer U
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- Adult, Blood Glucose analysis, Blood Pressure drug effects, Carbohydrate Metabolism, Catecholamines blood, Cold Temperature, Energy Metabolism, Heart Rate, Humans, Insulin blood, Leg, Male, Potassium blood, Regional Blood Flow drug effects, Vascular Resistance drug effects, Insulin pharmacology, Muscles blood supply, Parasympatholytics pharmacology, Sympatholytics pharmacology
- Abstract
Euglycemic hyperinsulinemia stimulates both sympathetic nerve activity and blood flow to skeletal muscle, but the mechanism is unknown. Possible mechanisms that may stimulate muscle blood flow include neural, humoral, or metabolic effects of insulin. To determine whether such insulin-induced vasodilation is modulated by stimulation of adrenergic or cholinergic mechanisms, we obtained, in eight healthy lean subjects, plethysmographic measurements of calf blood flow during 3 h of hyperinsulinemic (1 mU.kg-1.min-1) euglycemic clamp performed alone or during concomitant beta-adrenergic (propranolol infusion), cholinergic (atropine infusion), or alpha-adrenergic (prazosin administration) blockade. Euglycemic hyperinsulinemia alone increased calf blood flow by 38 +/- 10% (means +/- SE) and decreased vascular resistance by 27 +/- 4% (P < 0.01). The principal new observation is that these insulin-induced vasodilatory responses were not attenuated by concomitant propranolol or atropine infusion, nor were they potentiated by prazosin administration. In conclusion, these findings provide evidence that during euglycemic hyperinsulinemia in lean healthy humans stimulation of muscle blood flow is not mediated primarily by beta-adrenergic or cholinergic mechanisms. Furthermore, alpha-adrenergic mechanisms do not markedly limit insulin-induced stimulation of muscle blood flow.
- Published
- 1994
- Full Text
- View/download PDF
27. Metabolic and respiratory effects of infused sodium acetate in healthy human subjects.
- Author
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Burnier P, Tappy L, Jéquier E, Schneeberger D, and Chioléro R
- Subjects
- Acetic Acid, Adult, Bicarbonates metabolism, Fatty Acids, Nonesterified blood, Female, Hemodynamics drug effects, Humans, Infusions, Intravenous, Male, Oxidation-Reduction drug effects, Pulmonary Gas Exchange drug effects, Reference Values, Acetates pharmacology, Metabolism drug effects, Respiration drug effects
- Abstract
The metabolic and respiratory effects of intravenous 0.5 M sodium acetate (at a rate of 2.5 mmol/min during 120 min) were studied in nine normal human subjects. O2 consumption (VO2) and CO2 production (VCO2) were measured continuously by open-circuit indirect calorimetry. VO2 increased from 251 +/- 9 to 281 +/- 9 ml/min (P < 0.001), energy expenditure increased from 4.95 +/- 0.17 kJ/min baseline to 5.58 +/- 0.16 kJ/min (P < 0.001), and VCO2 decreased nonsignificantly (211 +/- 7 ml/min vs. 202 +/- 7 ml/min, NS). The extrapulmonary CO2 loss (i.e., bicarbonate generation and excretion) was estimated at 48 +/- 5 ml/min. This observation is consistent with 1 mol of bicarbonate generated from 1 mol of acetate metabolized. Alveolar ventilation decreased from 3.5 +/- 0.2 l/min basal to 3.1 +/- 0.2 l/min (P < 0.001). The minute ventilation (VE) to VO2 ratio decreased from 22.9 +/- 1.3 to 17.6 +/- 0.9 l/l (P < 0.005), arterial PO2 decreased from 93.2 +/- 1.9 to 78.7 +/- 1.6 mmHg (P < 0.0001), arterial PCO2 increased from 39.2 +/- 0.7 to 42.1 +/- 1.1 mmHg (P < 0.0001), pH from 7.40 +/- 0.005 to 7.50 +/- 0.007 (P < 0.005), and arterial bicarbonate concentration from 24.2 +/- 0.7 to 32.9 +/- 1.1 (P < 0.0001). These observations indicate that sodium acetate infusion results in substantial extrapulmonary CO2 loss, which leads to a relative decrease of total and alveolar ventilation.
- Published
- 1992
- Full Text
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28. Effects of infused amino acids on glucose production and utilization in healthy human subjects.
- Author
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Tappy L, Acheson K, Normand S, Schneeberger D, Thélin A, Pachiaudi C, Riou JP, and Jéquier E
- Subjects
- Adult, Amino Acids administration & dosage, Analysis of Variance, Carbon Isotopes, Deuterium, Fatty Acids, Nonesterified blood, Female, Gluconeogenesis, Humans, Infusions, Intravenous, Insulin blood, Kinetics, Male, Metabolic Clearance Rate, Reference Values, Time Factors, Amino Acids pharmacology, Blood Glucose metabolism, Glucose metabolism
- Abstract
Amino acids have been reported to increase endogenous glucose production in normal human subjects during hyperinsulinemia: however, controversy exists as to whether insulin-mediated glucose disposal is inhibited under these conditions. The effect of an amino acid infusion on glucose oxidation rate has so far not been determined. Substrate oxidation rates, endogenous glucose production, and [13C]glucose synthesis from [13C]bicarbonate were measured in six normal human subjects during sequential infusions of exogenous glucose and exogenous glucose with (n = 5) or without (n = 5) exogenous amino acids. Amino acids increased endogenous glucose production by 84% and [13C]glucose synthesis by 235%. Glucose oxidation estimated from indirect calorimetry decreased slightly after amino acids, but glucose oxidation estimated from [13C]glucose-13CO2 data was increased by 14%. It is concluded that gluconeogenesis is the major pathway of amino acid degradation. During amino acid administration, indirect calorimetry underestimates the true rate of glucose oxidation, whereas glucose oxidation calculated from the 13C enrichment of expired CO2 during [U-13C]glucose infusion does not. A slight stimulation of glucose oxidation during amino acid infusion, concomitant with an increased plasma insulin concentration, indicates that amino acids do not inhibit glucose oxidation.
- Published
- 1992
- Full Text
- View/download PDF
29. Decreased thermal conductance during the luteal phase of the menstrual cycle in women.
- Author
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Frascarolo P, Schutz Y, and Jéquier E
- Subjects
- Adult, Body Temperature, Calorimetry, Female, Follicular Phase physiology, Humans, Mathematics, Progesterone blood, Regional Blood Flow, Skin blood supply, Skin Temperature, Body Temperature Regulation, Luteal Phase physiology
- Abstract
To study the influence of the menstrual cycle on whole body thermal balance and on thermoregulatory mechanisms, metabolic heat production (M) was measured by indirect calorimetry and total heat losses (H) were measured by direct calorimetry in nine women during the follicular (F) and the luteal (L) phases of the menstrual cycle. The subjects were studied while exposed for 90 min to neutral environmental conditions (ambient temperature 28 degrees C, relative humidity 40%) in a direct calorimeter. The values of M and H were not modified by the phase of the menstrual cycle. Furthermore, in both phases the subjects were in thermal equilibrium because M was similar to H (69.7 +/- 1.8 and 72.1 +/- 1.8 W in F and 70.4 +/- 1.9 and 71.4 +/- 1.7 W in L phases, respectively). Tympanic temperature (Tty) was 0.24 +/- 0.07 degrees C higher in the L than in the F phase (P less than 0.05), whereas mean skin temperature (Tsk) was unchanged. Calculated skin thermal conductance (Ksk) was lower in the L (17.9 +/- 0.6 W.m-2.degrees C-1) than in the F phase (20.1 +/- 1.1 W.m-2.degrees C-1; P less than 0.05). Calculated skin blood flow (Fsk) was also lower in the L (0.101 +/- 0.008 l.min-1.m-2) than in the F phase (0.131 +/- 0.015 l.min-1.m-2; P less than 0.05). Differences in Tty, Ksk, and Fsk were not correlated with changes in plasma progesterone concentration. It is concluded that, during the L phase, a decreased thermal conductance in women exposed to a neutral environment allows the maintenance of a higher internal temperature.
- Published
- 1990
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30. Nutritional influences on lipogenesis and thermogenesis after a carbohydrate meal.
- Author
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Acheson KJ, Schutz Y, Bessard T, Ravussin E, Jéquier E, and Flatt JP
- Subjects
- Adult, Calorimetry, Energy Intake, Energy Metabolism, Fasting, Glucose metabolism, Humans, Male, Palmitic Acid, Palmitic Acids metabolism, Body Temperature Regulation, Dietary Carbohydrates, Lipids biosynthesis
- Abstract
In vivo lipogenesis and thermogenesis were studied for 24 h after ingestion of 500 g of carbohydrate (CHO) in subjects who had consumed either a high-fat, a mixed, or a high-CHO diet during the 3-6 days preceding the test. CHO oxidation and conversion to fat was significantly less in the high-fat diet group (222 +/- 5 g) than in the mixed (300 +/- 13 g) or high-CHO diet (331 +/- 7 g) groups, resulting in a greater glycogen storage in the high-fat (278 +/- 6 g) than in the other two groups (197 +/- 11 and 170 +/- 2 g). Net lipogenesis occurred sooner and lasted longer in the high-CHO group, amounting to 0.8 +/- 0.5, 3.4 +/- 0.6, and 9 +/- 1 g of lipid synthesized in the high-fat, mixed, and high-CHO groups, respectively. The thermic effect of the CHO load was 5.2 +/- 0.5% on the high-fat, 6.5 +/- 0.4% on the mixed diet, and 8.6 +/- 0.4% on the high-CHO diet. Significant relationships were demonstrated between the postabsorptive nonprotein respiratory quotient and net lipogenesis after the CHO load (r = 0.82) and between net lipogenesis and the increase in energy expenditure (r = 0.71). It is concluded that the antecedent diet influences the amount of net lipogenesis and the magnitude of thermogenesis after a large CHO test meal. However, lipogenesis remains too limited even after such large CHO intakes to cause an increase in the body's fat content.
- Published
- 1984
- Full Text
- View/download PDF
31. Heat storage regulation in exercise during thermal transients.
- Author
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Chappuis P, Pittet P, and Jéquier E
- Subjects
- Adult, Body Temperature, Humans, Male, Oxygen Consumption, Skin Physiological Phenomena, Sweating, Body Temperature Regulation, Calorimetry, Calorimetry, Indirect, Physical Exertion
- Abstract
Rate of heat storage (S) was measured by using direct and indirect calorimetry simultaneously in 11 subjects during rest and exercise at three ambient temperatures (Ta of 20, 25, and 30 degrees C), and at two work intensities (40 and 90 W). At rest, the mean value of S was -64.9 W at 20 degrees C, -26.1 W at 25 degrees C, and +9.9 W at 30 degrees C. After 50 min of exercise at 40 or 90 W, S tended toward zero at the three ambient temperatures. This indicates that thermal equilibrium was reached. In addition, at the end of the exercise periods total heat losses (R + C + E) measured at a Ta of 20, 25, and 30 degrees C were similar, i.e., independent of Ta. During the thermal transients and the steady state of exercise, the calorimetric method allows immediate measurement of S to be made, since all the physical terms of the body heat balance equation are determined. The changes in mean body temperature (delta Tb) measured by thermometry showed a delay of 5-10 min when compared with delta Tb measured by calorimetry. Thus, determination of delta Tb by thermometry is not directly applicable during thermal transients, unless the observed delay is taken into account. Our results also support the concept that Tb may be the regulated variable of the thermoregulatory system, since we obtained a very significant and uniform correlation between Esk and delta Tb at the three Ta and the two work intensities which were studied.
- Published
- 1976
- Full Text
- View/download PDF
32. Energy expenditure by doubly labeled water: validation in humans and proposed calculation.
- Author
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Schoeller DA, Ravussin E, Schutz Y, Acheson KJ, Baertschi P, and Jéquier E
- Subjects
- Adult, Carbon Dioxide biosynthesis, Deuterium, Humans, Male, Mathematics, Oxygen Isotopes, Pulmonary Gas Exchange, Energy Metabolism, Water
- Abstract
To further validate the doubly labeled water method for measurement of CO2 production and energy expenditure in humans, we compared it with near-continuous respiratory gas exchange in nine healthy young adult males. Subjects were housed in a respiratory chamber for 4 days. Each received 2H2(18)O at either a low (n = 6) or a moderate (n = 3) isotope dose. Low and moderate doses produced initial 2H enrichments of 5 and 10 X 10(-3) atom percent excess, respectively, and initial 18O enrichments of 2 and 2.5 X 10(-2) atom percent excess, respectively. Total body water was calculated from isotope dilution in saliva collected at 4 and 5 h after the dose. CO2 production was calculated by the two-point method using the isotopic enrichments of urines collected just before each subject entered and left the chamber. Isotope enrichments relative to predose samples were measured by isotope ratio mass spectrometry. At low isotope dose, doubly labeled water overestimated average daily energy expenditure by 8 +/- 9% (SD) (range -7 to 22%). At moderate dose the difference was reduced to +4 +/- 5% (range 0-9%). The isotope elimination curves for 2H and 18O from serial urines collected from one of the subjects showed expected diurnal variations but were otherwise quite smooth. The overestimate may be due to approximations in the corrections for isotope fractionation and isotope dilution. An alternative approach to the corrections is presented that reduces the overestimate to 1%.
- Published
- 1986
- Full Text
- View/download PDF
33. Short-term, mixed-diet overfeeding in man: no evidence for "luxuskonsumption".
- Author
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Ravussin E, Schutz Y, Acheson KJ, Dusmet M, Bourquin L, and Jéquier E
- Subjects
- Adult, Body Weight, Humans, Male, Motor Activity, Time Factors, Diet, Eating, Energy Metabolism
- Abstract
After 13 days of weight maintenance diet (13,720 +/- 620 kJ/day, 40% fat, 15% protein, and 45% carbohydrate), five young men (71.3 +/- 7.1 kg, 181 +/- 8 cm; means +/- SD) were overfed for 9 days at 1.6 times their maintenance requirements (i.e., +8,010 kJ/day). Twenty-four-hour energy expenditure (24-h EE) and basal metabolic rate (BMR) were measured on three occasions, once after 10 days on the weight-maintenance diet and after 2 and 9 days of overfeeding. Physical activity was monitored throughout the study, body composition was measured by underwater weighing, and nitrogen balance was assessed for 3 days during the two experimental periods. Overfeeding caused an increase in body weight averaging 3.2 kg of which 56% was fat as measured by underwater weighing. After 9 days of overfeeding, BMR increased by 622 kJ/day, which could explain one-third of the increase in 24-h EE (2,038 kJ/day); the remainder was due to the thermic effect of food (which increased in proportion with excess energy intake) and the increased cost of physical activity, related to body weight gain. This study shows that approximately one-quarter of the excess energy intake was dissipated through an increase in EE, with 75% being stored in the body. Under our experimental conditions of mixed overfeeding in which body composition measurements were combined with those of energy balance, it was possible to account for all of the energy ingested in excess of maintenance requirements.
- Published
- 1985
- Full Text
- View/download PDF
34. Continuous versus single bolus enteral nutrition: comparison of energy metabolism in humans.
- Author
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Nacht CA, Schutz Y, Vernet O, Christin L, and Jéquier E
- Subjects
- Adult, Blood Glucose metabolism, Body Temperature Regulation, Energy Intake, Fatty Acids, Nonesterified blood, Female, Heart Rate, Humans, Insulin blood, Intubation, Gastrointestinal, Kinetics, Male, Oxygen Consumption, Energy Metabolism, Enteral Nutrition
- Abstract
Continuous respiratory exchange measurements were performed on five women and five men for 1 h before and 6 h after the administration of a milkshake (53% carbohydrates, 30% lipid, and 17% protein energy) given either as a single bolus dose or continuously during 3 h using a nasogastric tube. The energy administered corresponded to 2.3 times the postabsorptive resting energy expenditure. Resting energy expenditure, respiratory quotient, plasma glucose, and insulin concentrations increased sooner and steeper, and plasma free fatty acids levels decreased earlier with the meal ingested as a single dose than with continuous administration. The magnitude of nutrient-induced thermogenesis was greater (P less than 0.01) with the single dose (means +/- SE, 10.0 +/- 0.6%) than with the continuous administration (8.1 +/- 0.5%). The overall (6 h) substrate balances were not significantly different between the two modes of administration. It is concluded that the mode of enteral nutrient administration influences the immediate thermogenic response as well as changes in respiratory quotient, glycemia, and insulinemia; however, the overall nutrient balance was not affected by the mode of enteral nutrient administration.
- Published
- 1986
- Full Text
- View/download PDF
35. Thermic effect of food: possible implication of parasympathetic nervous system.
- Author
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Nacht CA, Christin L, Temler E, Chioléro R, Jéquier E, and Acheson KJ
- Subjects
- Adult, Atropine, Basal Metabolism, Blood Glucose metabolism, Blood Pressure, Energy Intake, Energy Metabolism, Heart Rate, Humans, Insulin blood, Kinetics, Male, Oxygen Consumption, Propranolol, Body Temperature, Food, Parasympathetic Nervous System physiology
- Abstract
To investigate the effect of the autonomic nervous system on the thermic response to food ingestion, respiratory exchange measurements were performed on seven healthy young men for 1 h and 45 min before and 6 h after ingestion of a mixed meal, approximately 560 kcal, 53% carbohydrate, 30% fat, and 17% protein (control) and under the same conditions during infusion of either propranolol (80 micrograms/kg bolus and 1 microgram.kg-1.min-1), atropine (10 micrograms/kg and 10 micrograms.kg-1.min-1), or atropine plus propranolol. The postabsorptive resting metabolic rates were the same on each occasion and were slightly altered by drug treatment. The thermic responses to the meal were the same with the control and propranolol tests (9.3 +/- 0.9 and 9.2 +/- 0.5%, respectively) and were greater (P less than 0.001) than with atropine 3.6 +/- 0.6% and atropine plus propranolol 3.3 +/- 0.8%. Blockade of the sympathetic nervous system does not decrease the thermic response to food taken orally, whereas muscarinic receptor blockade does. Although some confounding effects of atropine might explain some of this decrease, our results suggest that the parasympathetic nervous system is involved in the thermic effect of food.
- Published
- 1987
- Full Text
- View/download PDF
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