Magnetic resonance imaging of articular cartilage: ex vivo study on normal cartilage correlated with magnetic resonance microscopy

PURPOSE: The purpose of this study was to determine the effects of a school-based, low-volume strength training program on energy expenditure, strength, and physical fitness in obese prepubertal girls. METHODS: A longitudinal, 5-month strength training exercise program was undertaken by healthy, obese (> 95th percentile weight-for-height, N = 11) girls age 7-10 yr. The following were measured: strength by the one-repetition maximum test; fitness (VO2peak) by a treadmill exercise test; resting metabolic rate (RMR), 24-h sedentary energy expenditure (SEE), and sleeping metabolic rate (SMR) by room respiration calorimetry; and total energy expenditure (TEE) by the doubly labeled water method. Physical activity energy expenditure (AEE) was calculated as TEE-(RMR + 0.1.TEE) and physical activity level (PAL) as TEE/RMR. An age-matched, nonoverweight control group was measured for (VO2peak) and RMR over the same time period. RESULTS: Strength increased by 19.6 and 20.0% in the upper and lower body (P < 0.01), respectively. (VO2peak) (mL.min-1) increased in both groups over time (P < 0.05), but not when covaried for fat-free mass (FFM) or weight. After adjusting for FFM or weight, RMR did not change, but SMR and 24-h SEE decreased significantly in the exercise group. There were no changes in nonprotein respiratory quotient or substrate oxidation. No changes in TEE, AEE, and PAL occurred, either unadjusted or adjusted for FFM or weight. CONCLUSION: This long-term, school-based, low-volume strength training program favorably increases strength in obese prepubertal girls but does not increase their daily energy expenditure.     

Total energy expenditure and the level of physical activity correlate with plasma leptin concentrations in five-year-old children

Leptin, the product of the ob gene, is a hormone secreted by adipocytes that is known to decrease food intake and increase energy expenditure in ob/ob mice. In humans, variants in the OB gene have not been detected and very little is known about the action of leptin on food intake and energy expenditure, although circulating leptin concentrations are positively correlated to body fat stores. The purpose of this study was to assess the relationship between fasting plasma leptin concentrations and energy expenditure in 123 5-yr-old Pima Indian children (67 males/76 females). Body composition was assessed by isotopic water dilution (18O) whereas total energy expenditure (TEE) and resting metabolic rate (RMR) were measured using doubly labeled water and indirect calorimetry, respectively. The physical activity level was calculated as the ratio of TEE:RMR. Plasma leptin concentrations were positively correlated to percent body fat (r = 0.84, P < 0.0001), but were similar in boys and girls after adjusting for percent body fat. Most importantly, we found that, independent of the percentage of body fat, plasma leptin concentrations correlated with TEE (in absolute values, r = 0.37, P < 0.0001, or adjusted for body size r = 0.42; P < 0.0001) and with physical activity level (r = 0.26, P < 0.01), but not RMR. These results suggest that, as in animal models, leptin plays a role in energy expenditure in humans.     

Epidemiology and treatment of otitis media with effusion in children in the first year of primary school

Children with acute lymphoblastic leukaemia (ALL) typically gain weight at excessive rates during and after therapy, and a high proportion of young adult survivors are obese. Previous studies have failed to identify the abnormalities in energy balance that predispose these children to obesity. The aim of this study was to determine the cause of excess weight gain in children treated for ALL by testing the hypothesis that energy expenditure is reduced in these patients. Twenty children [9 boys, 11 girls; mean age 10.9 (3.2) y] treated for ALL who had shown excess weight gain, but were not obese [mean body mass index SD score 0.70 (1.04)], were closely and individually matched with 20 healthy control children [9 boys, 11 girls; mean age 10.7 (3.0) y; mean body mass index SD score 0.27 (0.91)]. In each child we measured total energy expenditure by doubly-labeled water method, resting energy expenditure, energy expended on habitual physical activity, and energy intake. Total energy expenditure was significantly higher in control subjects than in patients: mean paired difference 1185 kJ/d (282 kcal/d), 95% confidence interval (CI) 218-2152. This difference was largely due to reduced energy expended on habitual physical activity in the patients. Resting energy expenditure was lower in the patients: mean paired difference 321 kJ/d (76 kcal/d), 95% CI 100-541. Energy intake was also lower in the patients: mean paired difference 1001 kJ/d (238 kcal/d), 95% CI 93-1909. Children treated for ALL are predisposed to excess weight gain, and subsequently obesity, by reduced total energy expenditure secondary to reduced habitual physical activity. Prevention of obesity in ALL should focus on modest increases in habitual physical activity, modest restriction of dietary intake, and monitoring of excess weight gain.     

Traversing the menopause: changes in energy expenditure and body composition

The menopause transition is associated with several physiological changes that may impact women's health outcome. Among the changes associated with the loss of ovarian function is an increased risk of metabolic and cardiovascular disease. The present review focuses on changes in energy expenditure, body composition and body fat distribution during the postmenopausal transition. Previous work indicates that the most important component of total daily expenditure, resting metabolic rate, may be reduced by the menopause, independently of the effects of the normal aging process. This effect is mainly attributable to a decrease in fat-free mass. The energy expenditure associated with physical activity is the most variable component of total daily energy expenditure. However, small changes in this component may have a substantial impact on body composition. Longitudinal data from our laboratory indicate that the menopause transition also leads to significant decreases in physical activity energy expenditure. The changes in body composition that accompany the menopause transition have been studied by several groups and, although some studies suggested increases in body mass index or total body fat mass with the menopause, currently available cross-sectional data preclude a firm conclusion. Nevertheless, results from our longitudinal study showed significant increases in fat mass with the menopause. The accumulation of abdominal fat, which may be a better correlate of the comorbidities associated with obesity, has also been shown to be accelerated by the menopause transition. In this regard, it has been shown that treatment with hormone replacement therapy prevents the increase in the rate of abdominal adipose tissue accumulation that was noted with the menopause. Thus, it appears that the loss of ovarian function induces a reduction in resting metabolic rate, physical activity energy expenditure, fat-free mass, and an increase in fat mass and abdominal adipose tissue accumulation. These modifications probably contribute to the increased risk of cardiovascular disease of postmenopausal women.     

Energy and water metabolism, body composition, and hormonal changes induced by 42 days of enforced inactivity and simulated weightlessness

Inactivity causes profound deleterious changes. We investigated in eight healthy men the impact of a 42-day head-down bed rest (HDBR) on energy and water metabolism and their interrelationships with body composition (BC) and catabolic and anabolic hormones. Total energy expenditure (TEE), total body water, water turnover, and metabolic water formation were assessed by the doubly labeled water method 15 days before and for the last 15 days of HDBR. Resting energy expenditure was determined by indirect calorimetry, and BC was determined by dual energy x-ray absorptiometry. Urinary excretion of cortisol, GH, normetanephrine, metanephrine, urea, and creatinine were measured daily. HDBR resulted in significant reductions in body weight (2%), total body water (5%), metabolic water (17%), and lean body mass (LBM; 4%), but fat mass and water turnover did not change. Segmental BC showed a decreased LBM in legs and trunk, whereas fat mass increased, no significant changes were noted in the arms. The hydration of LBM was unchanged. TEE and energy intake decreased significantly (20% and 13%), whereas resting energy expenditure was maintained. Expenditure for physical activity dropped by 39%. Subjects were in energy balance during HDBR, whereas it was negative during the control period (-1.5 MJ/day). There were decreases in urinary normetanephrine (23%) and metanephrine (23%), but urinary cortisol (28%; weeks 2 and 3), GH (75%; weeks 2-4), and urea (15%; weeks 3 and 4) increased. It was concluded that during prolonged HDBR no relevant modifications in water metabolism were triggered. BC changes occurred in the nonexercised body segments, and the reduction in TEE was due to inactivity, not to LBM loss. Moreover, body weight alone does not accurately reflect the subject's energy state, and energy balance alone could not explain the body weight loss, which involves a transient metabolic stress.     

Daily energy expenditure in free-living conditions in obese and non-obese children: comparison of doubly labelled water (2H2(18)O) method and heart-rate monitoring

OBJECTIVE: To compare the heart-rate monitoring with the doubly labelled water (2H2(18)O) method to estimate total daily energy expenditure in obese and non-obese children. DESIGN: Cross sectional study of obese and normal weight children. SUBJECTS: 13 prepubertal children: six obese (4M, 2F, 9.1 +/- 1.5 years, 47.3 +/- 9.7 kg) and seven non-obese (3M, 4F, 9.3 +/- 0.6 years, 31.8 +/- 3.2 kg). MEASUREMENTS: Total daily energy expenditure was assessed by means of the doubly labelled water method (TEEDLW) and of heart-rate monitoring (TEEHR). RESULTS: TEEHR was significantly (P < 0.05) higher than TEEDLW in obese children (9.47 +/- 0.84 MJ/d vs 8.99 +/- 0.63 MJ/d) whereas it was not different in non-obese children (8.43 +/- 2.02 MJ/d vs 8.42 +/- 2.30 MJ/d, P = NS). The difference of TEE assessed by HR monitoring in the obese group averaged 6.2 +/- 4.7%. At the individual level, the degree of agreement (difference between TEEHR and TEEDLW +/- 2s.d.) was low both in obese (-0.36, 1.32 MJ/d) and in non-obese children (-1.30, 1.34 MJ/d). At the group level, the agreement between the two methods was good in nonobese children (95% c.i. for the bias:-0.59, 0.63 MJ/d) but not in obese children (0.04, 0.92 MJ/d). Duration of sleep and energy expenditure during resting and physical activity were not significantly different in the two groups. Patterns of heart-rate (or derived energy expenditure) during the day-time were similar in obese and non-obese children. CONCLUSION: The HR monitoring technique provides an estimation of TEE close to that assessed by the DLW method in non-obese prepubertal children. In comparison with DLW, the HR monitoring method yields a greater TEE value in obese children.     

Weight loss by increasing energy consumption and thermogenesis

Obesity is caused by a chronic imbalance between energy intake and energy expenditure. The increasing incidence of obesity over the last years is partly caused by the decreased physical activity following industrialization. Weight reduction can be achieved by decreasing energy intake and increasing energy expenditure. The fat loss induced by physical activity, however, is relatively small. Exercise helps to prevent the otherwise inevitable loss of muscle during caloric restriction. Due to the low success rate of conventional weight loss programs, the development of drugs to increase thermogenesis is subject to worldwide research. While in animal experiments stimulation of beta-3 adrenergic receptors leads to a significant weight loss, in humans these drugs fail to stimulate energy expenditure probably due to the lack of significant amounts of brown adipose tissue. The recently identified uncoupling proteins (UCP) 2 and 3 dissipate the protone gradient, thereby releasing stored energy as heat. These proteins might therefore act as potential targets for antiobesity drugs.     

Influence of environmental temperature on in vivo energy expenditure in vitro ouabain-sensitive respiration in duodenal mucosa and liver in rats fed different levels of dietary fiber or protein

Seventy two Wistar rats were used in two repeat studies to investigate the effect of environmental temperature (18 degrees C or 28 degrees C) and increasing levels of dietary fibre (low, 68 g/kg DM; medium 110 g/kg DM; high, 157 g/kg DM) or protein (low, 91 g/kg DM; medium, 171 g/kg DM; high, 262 g/kg DM) on digestive tract, visceral organ size, energy metabolism, and respiration attributable to Na+,K(+)-ATPase activity in duodenal mucosa and liver. Total and ouabain-sensitive (a measure of Na+,K(+)-ATPase activity) O2 consumption in vitro of tissues were measured polarographically using a Clark-style YSI biological O2 monitor. Whole body heat production (in vivo) was measured using open-circuit respiration chambers. The weight of the visceral organs was higher in rats housed at 18 degrees C than at 28 degrees C. The empty weight of the small intestine, caecum, and colon increased as the level of dietary fibre increased (P 0.05). Heat production as a proportion of metabolizable energy was higher (P < 0.05) at 18 degrees C than at 28 degrees C in the first experiment but this difference was significant in the second experiment. Rats fed the low protein diet had significantly higher (P > 0.05) heat production than those fed medium or high protein diets. Compared to 28 degrees C, environmental temperature of 18 degrees C caused an increased total and ouabain-sensitive O2 consumption in duodenal mucosa. There was no significant effect of environmental temperature on total and ouabain-sensitive O2 consumption in the liver. However, ouabain-sensitive O2 consumption in liver was significantly higher (P 0.05) when rats were fed a low protein diet compared to the medium or high protein diet. Total and ouabain-sensitive O2 consumption increased in duodenal mucosa of rats fed low level of dietary fibre compared to the medium or high dietary fibre diets. The in vitro results corresponded with the whole animal energy expenditure and O2 consumption in vivo.     

Energy requirements and physical activity in free-living older women and men: a doubly labeled water study

Determinants of daily energy needs and physical activity are unknown in free-living elderly. This study examined determinants of daily total energy expenditure (TEE) and free-living physical activity in older women (n = 51; age = 67 +/- 6 yr) and men (n = 48; age = 70 +/- 7 yr) by using doubly labeled water and indirect calorimetry. Using multiple-regression analyses, we predicted TEE by using anthropometric, physiological, and physical activity indexes. Data were collected on resting metabolic rate (RMR), body composition, peak oxygen consumption (VO2 peak), leisure time activity, and plasma thyroid hormone. Data adjusted for body composition were not different between older women and men, respectively (in kcal/day): TEE, 2,306 +/- 647 vs. 2,456 +/- 666; RMR, 1,463 +/- 244 vs. 1,378 +/- 249; and physical activity energy expenditure, 612 +/- 570 vs. 832 +/- 581. In a subgroup of 70 women and men, RMR and VO2 peak explained approximately two-thirds of the variance in TEE (R2 = 0.62; standard error of the estimate = +/-348 kcal/day). Crossvalidation of this equation in the remaining 29 women and men was successful, with no difference between predicted and measured TEE (2,364 +/- 398 and 2,406 +/- 571 kcal/day, respectively). The strongest predictors of physical activity energy expenditure (P < 0.05) for women and men were VO2 peak (r = 0.43), fat-free mass (r = 0.39), and body mass (r = 0.34). In summary, RMR and VO2 peak are important independent predictors of energy requirements in the elderly. Furthermore, cardiovascular fitness and fat-free mass are moderate predictors of physical activity in free-living elderly.     

Role of nonexercise activity thermogenesis in resistance to fat gain in humans

Humans show considerable interindividual variation in susceptibility to weight gain in response to overeating. The physiological basis of this variation was investigated by measuring changes in energy storage and expenditure in 16 nonobese volunteers who were fed 1000 kilocalories per day in excess of weight-maintenance requirements for 8 weeks. Two-thirds of the increases in total daily energy expenditure was due to increased nonexercise activity thermogenesis (NEAT), which is associated with fidgeting, maintenance of posture, and other physical activities of daily life. Changes in NEAT accounted for the 10-fold differences in fat storage that occurred and directly predicted resistance to fat gain with overfeeding (correlation coefficient = 0.77, probability < 0.001). These results suggest that as humans overeat, activation of NEAT dissipates excess energy to preserve leanness and that failure to activate NEAT may result in ready fat gain.     

Intrahousehold allocation of energy intake among children under five years and their parents in rural Bangladesh

OBJECTIVE: This study assesses intrahousehold allocation of energy in rural Bangladesh and tests the hypothesis that, when daily energy intake is adjusted for energy expenditure, no age or gender bias will be apparent in intrahousehold energy allocation. DESIGN: Data were collected at two-month intervals over a one year study. SETTING: Four villages in Matlab Thana, rural Bangladesh. SUBJECTS: Two hundred and seven children up to 5 y of age and their 145 mothers and 123 fathers. INTERVENTIONS: Data included six measurements of observed 24 h dietary energy intake and physical activity recorded from waking to sleeping. Total daily energy expenditure was derived using the factorial method. RESULTS: Women's energy intake ranged from 75-88% of the FAO/WHO recommended energy intake over the six periods of data collection, significantly less (P < 0.0001) than the men's (range 89-114%). Although the women had moderate levels of physical activity, frequent pregnancies and long lactation periods increased their energy needs. Among children no longer breast fed, energy consumption, unadjusted for energy expenditure, provided 86-108% of the FAO/WHO recommended energy intake by weight. CONCLUSIONS: Women consistently received less of their energy requirements than either their children or their husbands.     

Role of energy expenditure in the development of pediatric obesity

The role that energy expenditure plays in pediatric obesity was somewhat confused by early research purporting to show that, as a group, obese children have lower energy intakes than do lean children. On the basis of this intake data, the conclusion was drawn that obese persons are somehow energy efficient, leading to weight gain. More recent research examining energy expenditure has shown clearly that, as a group, obese children have higher energy expenditures than do their lean counterparts. With the advent of the doubly labeled water method for determining free-living energy expenditure, it has been shown that obese children underreport intake significantly more than do lean children. When measurements are properly adjusted for differences in body size, there are generally no major differences in energy expenditure between lean and obese groups. However, in some cross-sectional studies, a low level of physical activity has been shown to be related to current body fatness. In addition, longitudinal studies have shown that a low level of energy expenditure, particularly energy expended in physical activity, is associated with both body fatness and weight gain.     

Complicated bone and soft-tissue infections. Imaging with 0.1 T MR and 99mTc-HMPAO-labeled leukocytes. ff

OBJECTIVE: To determine the relationship between resting energy expenditure and body cell mass in a group of children with spastic quadriplegic cerebral palsy (SQCP) in comparison with a group of healthy volunteers. SUBJECTS AND METHODS: Children with SQCP (n = 13) and healthy control subjects (n = 21) participated in the study. Resting energy expenditure (REE) by indirect calorimetry, as well as body composition measurements were obtained. Those included skinfold measurements, isotope dilution methods for total body water and extracellular water (2H2O or H2(18)O and NaBr, respectively), and bioelectrical impedance analysis. Intracellular water was calculated as total body water minus extracellular water. RESULTS: Overall REE in children with SQCP was significantly less than in control subjects or from predicted World Health Organization equations. There was a poor correlation between REE and weight or height for children with SQCP and those for control subjects. Children with SQCP showed a higher variance and small improvement in the correlation between REE and lean body mass or intracellular water in comparison with control subjects. Nine of the thirteen children with SQCP had significantly reduced REE per unit of lean tissue or intracellular water. Furthermore, bioelectrical impedance analysis was validated against dilution methods as a suitable technique for measuring total body water (r2 = 0.90, r = 0.95) and extracellular water (r2 = 0.84, r = 0.92) in children with SQCP. CONCLUSION: REE in children with SQCP is poorly correlated with body cell mass. We postulate that the central nervous system plays a crucial role in energy regulation. In children with SQCP, individual energy expenditure should be measured so that optimal nutritional status can be achieved. Bioelectrical impedance analysis can be used in this population to measure body water spaces.     

Effects of wine on plasma fibrinolytic and coagulation systems

Energy expenditure was estimated using the doubly-labelled water (DLW) method in summer in five free-living adult, non-pregnant, non-lactating, red deer (Cervus elaphus) hinds (weight 107.3 (SE 0.9) kg; age 6 (SE 1) years) on lowland pasture under typical farming conditions. Climatic conditions were monitored throughout the experiment. Errors due to 2H losses in CH4 and faeces were calculated from previous estimates of stoichiometries. CH4 production, fractionated water loss, urinary N and O2 consumption were estimated using an iterative approach. The water flux (rH2O) in these animals consuming only fresh grass was 12 (SE 0.5) kg/d, the CO2 production (rCO2) was 1271 (SE 40) litres/d and the mean energy expenditure was 25 (SE 0.8) MJ/d. There were no significant differences in the isotope distribution spaces and flux rates, rH2O, rCO2 or energy expenditure using the multi-point or two-point approaches to calculation. The DLW-derived energy expenditure of 25 MJ/d is approximately 20% higher than the recommended intake of 21 MJ/d for adult hinds kept outdoors (Adam, 1986) and, at 757 kJ/kg0.75 per d, one third higher than the value of 570 kJ/kg0.75 per d for stags penned indoors (Key et al. 1984).     

Practical, ongoing competency-assessment program for hospital pharmacists and technicians

The bicarbonate-urea method for measuring CO2 production was applied to eight free-living patients (mean age, 68 +/- 10 years; mean weight, 69 +/- 10 kg; mean height, 1.65 +/- 0.10 m) with unresectable small-cell lung cancer for a period of 1 day (n = 5) or 2 days (n = 3). The basal metabolic rate (BMR) was measured in all subjects. The technique was first validated against whole-body indirect calorimetry over an additional 24-hour period in five of these subjects. The bicarbonate-urea method predicted net CO2 production to be 102.1% +/- 3.4% of that measured by whole-body indirect calorimetry, and energy expenditure, 101.5% +/- 3.8% of the measured calorimeter value (8.1 +/- 1.6 MJ/d). The 24-hour recovery of label in CO2 excreted by the body was 95.6% +/- 0.5%. In free-living conditions, the bicarbonate-urea method predicted energy expenditure to be 9.0 +/- 2.6 MJ/d. BMR was elevated by a mean of 6% (P < .05) compared with the Schofield standards. The physical activity level ([PAL] the ratio of total energy expenditure [TEE] to BMR) was variable (1.15 to 1.87), but the mean value was only 1.36 +/- 0.22, considerably less than that of moderately active healthy subjects with estimated PAL values of 1.55 (P < .05) to 1.65 (P < .01) and the mean results obtained by doubly labeled water (previous studies) in healthy age- and sex-matched subjects. This is the first time a tracer method for measuring CO2 production and energy expenditure has been validated against whole-body 24-hour indirect calorimetry in patients with lung cancer or a systemic inflammatory reaction. The agreement between the two methods is similar to that observed in normal subjects. This is also the first time a tracer method has been used to measure energy expenditure in free-living patients with lung cancer. The results suggest that TEE and the energy requirements necessary to maintain energy balance were not increased despite basal hypermetabolism, because of the associated decrease in physical activity.     

Stretching

BACKGROUND: It has recently been reported that total daily energy expenditure (TDE) is increased in patients with chronic obstructive pulmonary disease (COPD) and it was hypothesised that these patients may have a decreased mechanical efficiency during activities. The purpose of the present study was to measure the mechanical efficiency of submaximal leg exercise, and to characterise patients with a potentially low efficiency in terms of body composition, resting energy expenditure, lung function, and symptom limited exercise performance. METHODS: Metabolic and ventilatory variables were measured breath by breath during submaximal cycle ergometry exercise performed at 50% of symptom limited achieved maximal load in 33 clinically stable patients with COPD (23 men) with forced expiratory volume in one second (FEV1) of 40 (12)% predicted. Net mechanical efficiency was calculated adjusting for resting energy expenditure (REE). RESULTS: Median mechanical efficiency was 15.5% and ranged from 8.5% to 22.7%. Patients with an extremely low mechanical efficiency (< 17%, n = 21) demonstrated an increased VO2/VE compared with those with a normal efficiency (median difference 4.7 ml/l, p = 0.005) during submaximal exercise. There was no difference between the groups differentiated by mechanical efficiency in blood gas tensions at rest, airflow obstruction, respiratory muscle strength, hyperinflation at rest, resting energy expenditure or body composition. There was a significant difference in total airways resistance (92% predicted, p = 0.03) between the groups differentiated by mechanical efficiency. CONCLUSIONS: It is concluded that many patients with severe COPD have decreased mechanical efficiency. Furthermore, based on the results of this study it is hypothesised that an increased oxygen cost of breathing during exercise contributes to the decreased mechanical efficiency.     

Energy balance in endurance-trained female cyclists and untrained controls

Reports of low energy intakes in trained female athletes imply they have an increased energetic efficiency. To address this question, we determined how energy balance was achieved in endurance-trained females cyclists and lean controls (n = 5 in each group). Daily energy expenditure was measured by using standardized physical activity protocols in a whole room calorimeter on two separate occasions: a cycling day and a noncycling day. Energy intake for weight maintenance was determined by a period of controlled feeding 5 days before and the day of each energy expenditure measurement. Energy balance was achieved in the cyclists on the cycling day while they consumed 2,900-3,000 kcal (their usual condition) and in controls on the noncycling day while they consumed 2,100-2,200 kcal (their usual condition). Total daily energy expenditure was not significantly different between the cyclists and controls on the noncycling day with both groups performing similar levels of activity. On the cycling day, daily energy expenditure was significantly greater in the cyclists vs. controls (P < 0.03) as a result of their greater amount of cycling activity. Components of daily energy expenditure, i.e., resting metabolic rate and thermic effect of food and activity (noncycling), were not significantly different between groups. Overall, we found no significant increase in the energetic efficiency of endurance-trained female cyclists compared with controls.     

Growth hormone improves body composition, fat utilization, physical strength and agility, and growth in Prader-Willi syndrome: A controlled study

BACKGROUND: Obesity and hypotonia in children with Prader-Willi syndrome (PWS) are accompanied by abnormal body composition and diminished energy expenditure resembling a growth hormone deficient state. Hypothalamic dysfunction in PWS often includes decreased growth hormone (GH) secretion, suggesting a possible therapeutic role for exogenous GH treatment. OBJECTIVES AND METHODS: After 6 months of observation to determine baseline growth rate, and with the use of a 12-month randomized controlled study design, the effects of GH treatment (1 mg/m2/d) on growth, body composition, strength and agility, pulmonary function, resting energy expenditure (REE), and fat utilization were assessed in 54 children with PWS (n = 35 treatment and n = 19 control). Percent body fat and bone mineral density were measured by dual x-ray absorptiometry. Indirect calorimetry was used to determine REE and to calculate respiratory quotients. RESULTS: Stimulated levels of GH in response to clonidine testing were low in all patients (peak, 2.0 ng/mL). After 12 months, GH-treated subjects showed significantly increased height velocity Z scores (mean, 1.0 1.7 to 4.6 2.9; P <.001), decreased percent body fat (mean, 46.3% 8.4% to 38.3% 10.7%; P <.001), and improved respiratory muscle function, physical strength, and agility (sit-ups, weight-lifts, running speed, and coordination). A significant decline in respiratory quotients occurred during GH therapy (0.81 to 0.77, P <.001), but total REE did not change. CONCLUSIONS: GH treatment of children with PWS accelerated growth, decreased percent body fat, and increased fat oxidation but did not significantly increase total REE. Improvements in respiratory muscle strength, physical strength, and agility also occurred, suggesting that GH treatment may have value in reducing some physical disabilities experienced by children with PWS.     

Theophylline improves measurements of respiratory muscle efficiency

To determine the effect of theophylline on respiratory muscle efficiency (RME), 12 normal subjects were given theophylline vs placebo in a double-blind, randomized crossover protocol. Spirometry, resting energy expenditure, minute ventilation, RME and oxygen cost of breathing were measured at baseline, after taking theophylline, and after placebo. RME was calculated by dividing the added work required to breathe through a threshold load by the added energy consumed during loaded breathing. Oxygen cost of breathing was calculated by dividing the increase in oxygen consumption induced by breathing an air/carbon dioxide mixture by the associated increase in minute ventilation. RME increased from 3.3 +/- 1.6% at baseline to 7.9 +/- 3.2% after theophylline (p < 0.01) but did not change significantly after placebo (4.8 +/- 2.4%). Oxygen cost of breathing decreased from 3.9 +/- 2.4 mL O2 per liter at baseline to 1.7 +/- 0.7 mL O2 per liter after theophylline (p < 0.05) but did not change significantly after placebo (2.8 +/- 1.3 mL O2 per liter). Theophylline use was also associated with an 18% increase in minute ventilation (p < 0.01) and a 15.7% increase in resting energy expenditure (p < 0.01). Theophylline improves measured RME and reduces oxygen cost of breathing in normal subjects. These effects are offset by increases in resting energy expenditure and minute ventilation.     

Energy expenditure and physical activity in relation to bone mineral density in women with anorexia nervosa

OBJECTIVES: To assess sleeping metabolic rate (SMR), average daily metabolic rate (ADMR), and total bone mineral density (TBMD) in women with anorexia nervosa, and to evaluate the effect of daily physical activity on TBMD. DESIGN: We compared women with anorexia nervosa and controls using measurements on body composition, and energy expenditure. Relations between these measurements were investigated. SETTING: Daily living environments in The Netherlands, and body composition and energy expenditure laboratory of the Department of Human Biology. SUBJECTS: Twelve adult, non-hospitalized women with anorexia nervosa, and sixteen adult normal weight women. INTERVENTIONS: Average daily metabolic rate was measured with the doubly labeled water method and sleeping metabolic rate in a respiration chamber. TBMD was measured by dual energy X-ray absorptiometry, and percentage body fat was calculated combining the results from underwater weighing and deuterium dilution. RESULTS: TBMD was significantly lower in anorexia than in controls (0.989 +/- 0.081 vs 1.144 +/- 0.054 g/cm2). Also ADMR and SMR were reduced in anorexia. The physical activity index (PAI = ADMR/SMR) was not significantly different from PAI in controls. In anorexia, TBMD was related to the PAI (R2 = 0.35, P < 0.05). Finally, stepwise multiple regression revealed that PAI together with the study groups as dummy variables could explain 69% of the variation in TBMD. CONCLUSION: These findings show that in anorexia TBMD is reduced, but that nonetheless physical activity has a significant positive effect on bone density.