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Kidney transplant patients display decreased muscle mass and increased fat mass. Whether this altered body composition is due to glucocorticoid induced altered fuel metabolism is unclear. To answer this question, 16 kidney transplant patients were examined immediately after kidney transplantation (12 +/- 4 days, mean +/- SEM) and then during months 2, 5, 11 and 16, respectively, by whole body dual energy X-ray absorptiometry (Hologic QDR 1000W) and indirect calorimetry. Results were compared with those of 16 age, sex and body mass index matched healthy volunteers examined only once. All patients received dietary counselling with a step 1 diet of the American Heart Association and were advised to restrict their caloric intake to the resting energy expenditure plus 30%. Immediately after transplantation, lean mass of the trunk was higher by 7 +/- 1% (P < 0.05) and that of the limbs was lower by more than 10% (P < 0.01) in patients than in controls. In contrast, no difference in fat mass and resting energy expenditure could be detected between patients and controls. During the 16 months of observation, total fat mass increased in male (+4.9 +/- 1.5 kg), but not in female patients (0.1 +/- 0.8 kg). The change in fat mass observed in men was due to an increase in all subregions of the body analysed (trunk, arms+legs as well as head+neck), whereas in women only an increase in head+neck by 9 +/- 2% (P = 0.05) was detected. Body fat distribution remained unchanged in both sexes over the 16 months of observation. Lean mass of the trunk mainly decreased between days 11 and 42 (P < 0.01) and remained stable thereafter. After day 42, lean mass of arms and legs (mostly striated muscle) and head+neck progressively increased over the 14 months of observation by 1.6 +/- 0.6 kg (P < 0.05) and 0.4 +/- 0.1 kg (P < 0.01), respectively. Resting energy expenditure was similar in controls and patients at 42 days (30.0 +/- 0.7 vs. 31.0 +/- 0.9 kcal kg-1 lean mass) and did not change during the following 15 months of observation. However, composition of fuel used to sustain resting energy expenditure in the fasting state was altered in patients when compared with normal subjects, i.e. glucose oxidation was higher by more than 45% in patients (P < 0.01) during the second month after grafting, but gradually declined (P < 0.01) over the following 15 months to values similar to those observed in controls. Protein oxidation was elevated in renal transplant patients on prednisone at first measurement, a difference which tended to decline over the study period. In contrast to glucose and protein oxidation, fat oxidation was lower in patients 42 days after grafting (P < 0.01), but increased by more than 100% reaching values similar to those observed in controls after 16 months of study. Mean daily dose of prednisone per kg body weight correlated with the three components of fuel oxidation (r > 0.93, P < 0.01), i.e. protein, glucose and fat oxidation. These results indicate that in prednisone treated renal transplant patients fuel metabolism is r...

Cigarette smoking has been associated with increased upper body fat deposition, as estimated by the waist to hip ratio, which has been shown to be associated with glucose intolerance and dyslipidemia in nonsmoking subjects. Whether smoking is at the origin of central adiposity and its related metabolic disturbances is unclear. Moreover, it is controversial whether smoking influences fuel metabolism. Therefore, young healthy male volunteers smoking more than 10 cigarettes/day for more than 5 yr (n = 14) were compared with nonsmokers (n = 13) matched for age, sex, body mass index, alcohol consumption, physical activity, as well as family history for hypertension, diabetes, obesity, and coronary heart disease. After an overnight fast, blood was drawn for chemistry, body composition was assessed by dual energy x-ray absorptiometry, and fuel metabolism was determined by indirect calorimetry. Nicotine uptake was estimated by 24-h urinary excretion of cotinine. Lean and fat body mass as well as their respective segmental distribution (i.e. arms, trunk, legs, and head), total bone mineral content, resting energy expenditure, and fat, carbohydrate, and protein oxidation were similar between smokers and nonsmokers. In contrast, 24-h urinary cotinine excretion (72.0 +/- 11.4 vs. 0.8 +/- 0.2 mumol/L.24 h; P < 0.001), plasma glucose (4.62 +/- 0.09 vs. 4.25 +/- 0.1 mmol/L; P < 0.01), total cholesterol (4.87 +/- 0.15 vs. 4.27 +/- 0.16 mmol/L; P < 0.02), low density lipoprotein cholesterol (3.05 +/- 0.19 vs. 2.43 +/- 0.16 mmol/L; P < 0.02), and apolipoprotein B concentrations (1.09 +/- 0.11 vs. 0.83 +/- 0.03 mmol/L; P < 0.03) were all higher in smokers than in nonsmokers. In smokers, 24-h urinary cotinine excretion positively correlated with the waist to hip ratio (r = 0.58; P = 0.03) and negatively with hip circumference (r = 0.87; P < 0.001). Moreover, 24-h cotinine excretion positively correlated with fat oxidation (r = 0.57; P = 0.03), but was independent of the other metabolic parameters studied. These results suggest that the dyslipidemia and glucose intolerance observed in smokers are not related to either central obesity or the amount of nicotine inhaled, but, rather, are due to some other component in cigarette smoke. In contrast, in smokers, fat oxidation increases with increasing nicotine uptake, a fact that might account for the often observed weight gain after cessation of smoking, thus suggesting different mechanisms of action of tobacco consumption on cholesterol and glucose metabolism on one side and fat oxidation on the other.

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