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J F Gautier

Publications and source records attributed to J F Gautier.

47 records · Page 3Linked to original sources
PubMed1995

Exogenous glucose oxidation during exercise in relation to the power output.

In order to study the influence of the power output on the oxidation rate of exogenous glucose and on the contribution of the various substrates to the energy demand, we combined the use of artificially enriched 13C-glucose with classical indirect calorimetry during uphill treadmill exercise. Six young male healthy subjects underwent three exercise bouts, in a randomized order and at least two weeks apart, at a low (45% VO2max, 1822 +/- 194 ml O2/min for 4 hours), moderate (60% VO2max, 2582 +/- 226 ml O2/min for 3 hours), and high intensity (75% VO2max, 3036 +/- 287 ml O2/min for 2 hours). After 10 min of exercise, each subject ingested 100 g of artificially 13C-labelled glucose dissolved in 400 ml of water. Over the four hours of the exercise at 45% VO2max, the amount of exogenous glucose oxidized was 89.5 +/- 5.9 g from the 100 g ingested. In all exercise bouts, the oxidation of exogenous glucose already began during the first 30 min after ingestion and peaked at 120 min. The maximum oxidation rates averaged 0.64 +/- 0.07, 0.75 +/- 0.04, and 0.63 +/- 0.08 g/min, and the mean amounts of exogenous glucose oxidized over the first two hours averaged 51.7 +/- 8.0, 61.5 +/- 6.6 and 50.9 +/- 8.45 g, at 45, 60 and 75% VO2max respectively. The contribution of the oxidation of exogenous glucose to the total energy supply progressively decreased when the power output increased, from 19.6 to 12.2%. In the meantime, the contribution of total carbohydrates (exogenous+endogenous) progressively increased from 55.1 to 77.8% while the contribution of lipids decreased from 35.5 to 16.6%. In conclusion, exogenous glucose ingested during exercise is largely oxidized and strongly contributes to the energy supply. The oxidation rate first increases with the power output, but levels off or even decreases at high intensity exercise.

Adult↗
PubMed1994

Availability of glucose ingested during muscle exercise performed under acipimox-induced lipolysis blockade.

This study investigated the percentage of carbohydrate utilization than can be accounted for by glucose ingested during exercise performed after the ingestion of the potent lipolysis inhibitor Acipimox. Six healthy male volunteers exercised for 3 h on a treadmill at about 45% of their maximal oxygen uptake, 75 min after having ingested 250 mg of Acipimox. After 15-min adaptation to exercise, they ingested either glucose dissolved in water, 50 g at time 0 min and 25 g at time 60 and 120 min (glucose, G) or sweetened water (control, C). Naturally labelled [13C]glucose was used to follow the conversion of the ingested glucose to expired-air CO2. Acipimox inhibited lipolysis in a similar manner in both experimental conditions. This was reflected by an almost complete suppression of the exercise-induced increase in plasma free fatty acid and glycerol and by an almost constant rate of lipid oxidation. Total carbohydrate oxidation evaluated by indirect calorimetry, was similar in both experimental conditions [C, 182, (SEM 21); G, 194 (SEM 16) g.3 h-1], as was lipid oxidation [C, 57 (SEM 6); G, 61 (SEM 3) g.3 h-1]. Exogenous glucose oxidation during exercise G, calculated by the changes in 13C:12C ratio of expired air CO2, averaged 66 (SEM 5) g.3 h-1 (19% of the total energy requirement). Consequently, endogenous carbohydrate utilization was significantly smaller after glucose than after placebo ingestion: 128 (SEM 18) versus 182 (SEM 21) g.3 h-1, respectively (P < 0.05). Symptoms of intense fatigue and leg cramps observed with intake of sweet placebo were absent with glucose ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1993

Endogenous substrate oxidation during exercise and variations in breath 13CO2/12CO2.

This study attempted to induce a major shift in the utilization of endogenous substrates during exercise in men by the use of a potent inhibitor of adipose tissue lipolysis, Acipimox, and to see to what extent this affects the 13C/12C ratio in expired air CO2. Six healthy volunteers exercised for 3 h on a treadmill at approximately 45% of their maximum O2 uptake, 75 min after having ingested either a placebo or 250 mg Acipimox. The rise in plasma free fatty acids and glycerol was almost totally prevented by Acipimox, and no significant rise in the utilization of lipids, evaluated by indirect calorimetry, was observed. Total carbohydrate oxidation averaged 128 +/- 17 (placebo) and 182 +/- 21 g/3 h (Acipimox). Conversely, total lipid oxidation was 84 +/- 5 (placebo) and 57 +/- 6 g/3 h (Acipimox; P < 0.01). Under placebo, changes in expired air CO2 delta 13C were minimal, with only a 0.49/1000 significant rise at 30 min. In contrast, under Acipimox, the rise in expired air CO2 delta 13C averaged 1/1000 and was significant throughout the 3-h exercise bout; in these conditions calculation of a "pseudooxidation" of an exogenous sugar naturally or artificially enriched in 13C, but not ingested, would have given an erroneous value of 19.8 +/- 2.6 g/3 h. Thus under conditions of extreme changes in endogenous substrate utilization, an appropriate control experiment is mandatory when studying exogenous substrate oxidation by 13C-labeled substrates and isotope-ratio mass spectrometry measurements on expired air CO2.

Adult↗
PubMed1993

Fructose utilization during exercise in men: rapid conversion of ingested fructose to circulating glucose.

The aim of the present study was to compare the metabolic fate of repeated doses of fructose or glucose ingested every 30 min during long-duration moderate-intensity exercise in men. Healthy volunteers exercised for 3 h on a treadmill at 45% of their maximal oxygen consumption rate. "Naturally labeled" [13C]glucose or [13C]fructose was given orally at 25-g doses every 30 min (total feeding: 150 g; n = 6 in each group). Substrate utilization was evaluated by indirect calorimetry, and exogenous sugar oxidation was measured by isotope ratio mass spectrometry on expired CO2. Results were corrected for baseline drift in 13C/12C ratio in expired air due to exercise alone. Fructose conversion to plasma glucose was measured combining gas chromatography and isotope ratio mass spectrometry. Most of the ingested glucose was oxidized: 81 +/- 4 vs. 57 +/- 2 g/3 h for fructose (2P < 0.005). Exogenous glucose covered 20.8 +/- 1.4% of the total energy need (+/- 6.7 MJ) compared with 14.0 +/- 0.6% for fructose (2P < 0.005). The contribution of total carbohydrates was significantly higher and that of lipids significantly lower with glucose than with fructose. The blood glucose response was similar in both protocols. From 90 to 180 min, 55-60% of circulating glucose was derived from ingested fructose. In conclusion, when ingested repeatedly during moderate-intensity prolonged exercise, fructose is metabolically less available than glucose, despite a high rate of conversion to circulating glucose.

Adult↗
PubMed1990

[Familial pheochromocytoma and Van Hippel-Lindau disease].

The authors report the case of a 41-year old man who presented simultaneously with phaeochromocytoma, paraganglioma and renal carcinoma. The postoperative finding of metaiodobenzylguanidine uptake foci showed that the phaeochromocytoma was malignant. The patient's son had a phaeochromocytoma and a pancreatic cyst. The phaeochromocytoma had no clinical manifestations and had been discovered by systematic assays of urinary catecholamines and their derivatives. These abnormalities are those of Von Hippel-Lindau disease.

Adolescent↗
PubMedDate not supplied

[Physical activity and type 2 diabetes].

Muscular exercise promotes glucose utilisation by the skeletal muscle, independently of insulin action, by activating the AMP-activated protein kinase (AMPK). This process is not altered in patients with obesity and/or type 2 diabetes, despite the presence of insulin resistance. Thus, exercise should play a key role in the management of type 2 diabetic patients. Regular physical activity enhances insulin sensitivity, improves glucose control and corrects some cardiovascular risk factors. This paper briefly presents some practical recommendations about physical activity in obese and/or type 2 diabetic patients.

Blood Glucose↗
PubMedDate not supplied

[Ulcerated necrobiosis lipoidica associated with insulin-dependent diabetes mellitus. Beneficial effect of corticosteroid therapy by oral administration].

OBJECTIVES: Necrobiosis lipoidica is a rare degenerative disease of dermal connective tissue usually observed in young diabetic patients. Several drugs have been suggested to be useful, but none have been shown to be effective in all cases. CASE REPORT: A young patient with insulin-dependent diabetes had a severe invalidating ulcerated necrobiosis lipoidica. Oral corticosteroids led to a satisfactory regression then stabilization with 6 mg/d prednisone. DISCUSSION: Oral corticosteroids would appear to be effective treatment and should be validated by controlled studies. Corticosteroids should only be used in exceptionally severe forms of ulcerated necrobiosis lipoidica after failure of conventional treatments. Diabetes would be an indication under strict metabolic control.

Administration, Oral↗