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N F Butte

Publications and source records attributed to N F Butte.

At least 55 records · Page 3Linked to original sources
PubMed1996

Combined heart rate and activity improve estimates of oxygen consumption and carbon dioxide production rates.

Oxygen consumption (VO2) and carbon dioxide production (VCO2) rates were measured by electronically recording heart rate (HR) and physical activity (PA). Mean daily VO2 and VCO2 measurements by HR and PA were validated in adults (n = 10 women and 10 men) with room calorimeters. Thirteen linear and nonlinear functions of HR alone and HR combined with PA were tested as models of 24-h VO2 and VCO2. Mean sleep VO2 and VCO2 were similar to basal metabolic rates and were accurately estimated from HR alone [respective mean errors were -0.2 +/- 0.8 (SD) and -0.4 +/- 0.6%]. The range of prediction errors for 24-h VO2 and VCO2 was smallest for a model that used PA to assign HR for each minute to separate active and inactive curves (VO2, -3.3 +/- 3.5%; VCO2, -4.6 +/- 3%). There were no significant correlations between VO2 or VCO2 errors and subject age, weight, fat mass, ration of daily to basal energy expenditure rate, or fitness. VO2, VCO2, and energy expenditure recorded for 3 free-living days were 5.6 +/- 0.9 ml.min-1.kg-1, 4.7 +/- 0.8 ml. min-1.kg-1, and 7.8 +/- 1.6 kJ/min, respectively. Combined HR and PA measured 24-h VO2 and VCO2 with a precision similar to alternative methods.

Adult↗
PubMed1996

Are basal metabolic rate prediction equations appropriate for female children and adolescents?

The basal metabolic rate (BMR), which accounts for 50-70% of total energy expenditure, is essential for estimation of patient and population energy needs. Numerous equations have been formulated for prediction of human BMR. Most equations in current use are based on measurements of Caucasians performed more than four decades ago. We evaluated 10 prediction equations commonly used for estimation of BMR in 76 Caucasian and 42 African-American girls between 8 and 17 yr of age against BMR measured by whole-body calorimetry. The majority of the prediction equations (9 of 10) overestimated BMR by 60 +/- 46 kcal/day (range, 15-176 kcal/day). This overestimation was found to be significantly greater (P < 0.05) for African-American (77 +/- 17 kcal/day) than for Caucasians (25 +/- 17 kcal/day) in six equations, controlling for age, weight, and sexual maturity. We conclude that ethnicity is an important factor in estimation of the BMR and that the current prediction equations are not appropriate for accurate estimation of the BMR of individual female children and adolescents.

Adolescent↗
PubMed1995

Energy requirements from infancy to adulthood.

To investigate how age and body composition affect energy requirements, the sedentary daily expenditure (SDE) and basal metabolic rate (BMR) of 101 infants, 82 girls, and 27 adults were measured. Energy expenditure was scaled for differences in body size to test the effects of age and body fatness. A power function was superior to linear models. For all subjects, WT0.63 (where WT is weight) or FFM0.63 (where FFM is fat-free mass) explained 94% of the variability in BMR, and WT0.70 or FFM0.70 explained 97% of the variability in SDE. The effects of height and fat mass (kg or % body wt) on BMR and SDE scaled for weight or fat-free mass were age dependent. Best-fitted exponents relating BMR or SDE to body size differed between children (0.40-0.52) and infants (1.04-1.30) (P = 0.001). Human energy requirements from infancy to adulthood appear to be a power, not a linear, function of body weight and composition.

Adolescent↗
PubMed1995

Closed-loop control of carbon dioxide concentration and pressure improves response of room respiration calorimeters.

Large room calorimeters are capable of rapid measurements that are usually made in hoods or small rooms. We evaluated the performance gains of four calorimeters constructed with modern control systems, sample gas preparation and data processing. Calibration of the calorimeters and instruments was performed in place, with traceability to international standards. Performance was evaluated by infusion of N2-CO2 gas and 243 24-h studies of individuals. Our subjects included children weighing 20 kg and adults engaged in heavy exercise. Errors for 24-h infusion measurements (n = 23) were -0.34 +/- 1.24% for oxygen consumption rate and 0.11 +/- 0.98% for carbon dioxide production rate. Calorimeter 90% response times were 2 to 6 min over a range of oxygen consumption rates from 100 to > 4000 mL/min. Closed-loop control of supply and exhaust air flows provided consistent 24-h mean CO2 levels (0.39 +/- 0.015%) and pressures (13.2 +/- 4.4 Pa). Room calorimeters operated with closed-loop control can be used for accurate measurement of energy expenditure rate dynamics for a wide range of individuals.

Adolescent↗
PubMed1995

Influence of early feeding mode on body composition of infants.

To determine the effect of infant feeding mode on body composition, a cross-sectional study was designed in which 10 breast-fed and 10 formula-fed infants were studied at 1 month of age, and another 10 breast-fed and 10 formula-fed infants at 4 months of age. Anthropometric measurements included body weights, lengths, selected diameters, circumferences and skinfold thicknesses. Total body water (TBWO) was measured by 18O dilution. A dose equivalent to 300 mg 18O/kg body weight was administered orally to the infants. Fat-free mass (FFMO) was calculated from TBWO using reference hydration constants of 0.805 and 0.798 at 1 and 4 months, respectively. Body fatO was taken as the difference between weight and FFMO. Total-body electrical conductivity (TOBEC) measurements were used to estimate FFMT and FATT. ANOVA was used to analyze the anthropometric and body composition data using feeding mode and age as grouping factors. Anthropometric measurements did not differ by feeding mode. TBW (kg) and FFM (kg) and body fat (kg) derived from 18O dilution or TOBEC did not differ by feeding mode. TBWO,T (%wt), FFMO,T (%wt), and body fatO,T (%wt) derived from 18O dilution and TOBEC differed significantly between the breast-fed and formula-fed infants at 4 months of age (p < 0.05). Expressed as a percentage of body weight, TBWO and FFMO,T were higher and body fatO,T was lower among the 4-month formula-fed infants.

Adipose Tissue↗
PubMed1994

Energy metabolism during pregnancy: influence of maternal energy status.

Additional energy requirements for term pregnancies are traditionally estimated as 1200 kJ/d or 325 MJ. These estimates approximate measured energy costs for well-nourished women, but non-Western populations subsisting on limited diets have much lower expenditures. Based on recent studies of energy expenditure during pregnancy, this paper reviews the 1) association between gestational weight gain and fat gain, 2) the influence of maternal energy status on basal metabolic energy expenditure in late pregnancy, and 3) potential energy metabolism adaptations available to pregnant women and how adaptations vary with energy status. Available data suggest that additional energy requirements during pregnancy vary from 0 to 500 MJ and depend on maternal energy status. If energy supplies are limited, adaptations spare energy for fetal growth; if energy is abundant, energy balance may be achieved in different ways depending on individual behavioral changes in food intake or activity patterns and on adjustments in basal metabolism or fat deposition.

Adipose Tissue↗
PubMed1994

Caltrac versus calorimeter determination of 24-h energy expenditure in female children and adolescents.

The purpose of this study was to determine the validity of the Caltrac accelerometer for estimating 24-h energy expenditure (EE) in children and adolescents. EE for 40 girls (13.0 +/- 1.8 yr) was assessed for 24 h via indirect calorimetry in whole-room calorimeters. EE and activity level were estimated concurrently by two Caltrac accelerometers placed on the subjects at each hip. Significant correlations (P < 0.001) resulted between Caltrac estimates and calorimeter values for 24-h total EE (TEE, r = 0.80), sedentary daily EE (SDEE, r = 0.84), and waking EE (WEE, r = 0.85). Nonetheless, the Caltrac significantly (P < 0.001) underestimated EE in all experimental conditions (TEE: -13.3 +/- 8.6%; SDEE: -6.8 +/- 7.3%; WEE: -30.4 +/- 8.5%). A significant multiple correlation between calorimeter values and a combination of Caltrac activity counts and body weight (R = 0.86, P < 0.001) suggested these variables could be useful for daily EE estimation. Additional analyses indicated that as EE increased, the absolute difference between Caltrac and calorimeter values also increased. The significant correlations between Caltrac and calorimeter values suggest the Caltrac may be useful for assessing daily caloric expenditure for groups of children.

Acceleration↗
PubMed1993

Higher total energy expenditure contributes to growth faltering in breast-fed infants living in rural Mexico.

To investigate the energy requirements of infants living under unfavorable environmental conditions in rural Mexico, we measured the total energy expenditure (TEE) of 40 Otomi infants at approximately 4 or approximately 6 mo of age. Total energy expenditure was estimated by the doubly labeled water method: 100 mg 2H2O/kg and 250 mg 18O/kg were administered orally, after which urine was collected serially for 7 or 10 d. Isotopic enrichment of urine samples was analyzed by gas-isotope-ratio mass spectrometry. Weight and length were measured monthly from birth to 6 mo. Fat free mass was estimated from 18O dilution spaces. Total energy expenditures (mean +/- SD) were 310 +/- 58 and 318 +/- 29 kJ.kg-1 x d-1 at approximately 4 and approximately 6 mo, respectively. Total energy expenditure was higher than that previously observed for breast-fed infants reared under more protected environments (268 +/- 29 kJ.kg-1 x d-1). Weight, length and weight gain were 5.9 +/- 0.8 kg, 60 +/- 2 cm and 2.9 +/- 2.4 g.kg-1 x d-1 at 4.25 mo and 7.1 +/- 0.8 kg, 65 +/- 2 cm and 1.0 +/- 1.2 g.kg-1 x d-1 at 6.27 mo. Growth faltering was evident at 6 mo by clinically significant declines in growth velocities and National Center for Health Statistics Z-scores. Body fat of the Otomi infants averaged 21 +/- 6 and 18 +/- 5 g/100 g at approximately 4 and approximately 6 mo, respectively. Higher rates of TEE narrowed the margin of energy available for growth and thereby contributed to growth faltering in the Otomi infants.

Adolescent↗
PubMed1993

Fast-response whole body indirect calorimeters for infants.

Portable whole body indirect calorimeters were constructed for full-term (2.5- to 8-kg) and preterm (1- to 2.5-kg) infants. A new calibration system significantly increased the accuracy of flowmeters and gas analyzers. Performance tests with N2 and CO2 infusions and butane combustion demonstrated that the error of individual measurements of O2 consumption and CO2 production were within +/- 2%. The measured error was close to the theoretical uncertainty of approximately +/- 1% calculated from test results of the flowmeters and gas analyzers. System response to a step change in butane combustion rate exceeded 90% within 2 min. Error of +/- 2% and response of 2 min are likely to be the practical lower limits for whole body infant indirect calorimeters with current technology. The calorimeters demonstrated a rapid increase in O2 consumption after feeding (preterm infants) and in the transition from non-rapid-eye-movement to rapid-eye-movement sleep stages (full-term infants).

Butanes↗
PubMed1992

Human milk intake and growth faltering of rural Mesoamerindian infants.

To determine whether growth faltering during early infancy was attributable to inadequate intake of human milk, the nutrient intakes and growth of 30 Otomi infants from Capulhuac, Mexico, were studied at 4 or 6 mo of age. Growth was monitored monthly from 1 through 6 mo of age. The 2H dose-to-the-mother method was used to measure human milk intake. Energy, protein, lactose, and fat concentrations in milk were analyzed by standard techniques. Mean (+/- SD) human milk intakes were 885 +/- 145 and 869 +/- 150 g/d at 4 and 6 mo, respectively. Protein and lactose concentrations in milk were normal but fat and consequently energy concentrations were abnormally low. Energy intakes averaged 81 +/- 14 kcal.kg-1.d-1 at 4 mo and 72 +/- 14 kcal.kg-1.d-1 at 6 mo. Growth faltering by 6 mo was evidenced by the significant decline in growth velocities and National Center for Health Statistics Z scores. Weight gain at 6 mo was 8.1 +/- 3.5 g/d and length gain was 1.0 +/- 0.34 cm/mo. Weight-for-age and length-for-age Z scores were -0.81 +/- 0.94 and -1.51 +/- 0.83, respectively. Growth velocities were not significantly correlated with nutrient intakes. Growth faltering among the Otomi infants despite energy intakes comparable to those of breast-fed infants in more protected environments may have resulted from an increase in the need for nutrients or from a growth-limiting nutrient, other than energy, in their diet.

Adult↗
PubMed1992

Determining energy expenditure in preterm infants: comparison of 2H(2)18O method and indirect calorimetry.

The doubly labeled water (2H(2)18O) method used to estimate total energy expenditure (EETotal) is particularly sensitive to analytic error in preterm infants, because of their high percentage of body water and the high ratio of water flux to CO2 production. To evaluate further use of this method, the EE of 12 preterm infants was measured by indirect calorimetry and 2H(2)18O simultaneously and continuously for 5 days. Initial infant weight, age, and postconceptional age were (means +/- SD) 1,674 +/- 173 g, 4.4 +/- 2.6 wk, and 34.6 +/- 1.6 wk, respectively. The indirect calorimeter system included an air-temperature-controlled chamber and heart rate monitor. EE was measured by indirect calorimetry for 85.6 +/- 4.7% of study time and estimated from the linear regression of heart rate on EE for 14.4 +/- 4.7% of study time. The 2H(2)18O method entailed an initial dose of 100 mg 2H2O and 250 mg 18O/kg and a final dose of 75 mg 18O/kg; urine was collected twice daily. 2H and 18O enrichments were measured by gas-isotope-ratio mass spectrometry. EE was calculated from measured 2H and 18O dilution spaces (NH, NO), turnover rates (kH, kO), and measured respiratory quotient. The ratio of 2H to 18O dilution spaces was 1.01 +/- 0.01 and the ratio of kO to kH was 1.16 +/- 0.04. Estimation of EE from 2H(2)18O and indirect calorimetry agreed within 1%, although individual variability in methods was large.

Anthropometry↗
PubMed1992

Sleep organization and energy expenditure of breast-fed and formula-fed infants.

Sleep organization of infants may be influenced by differences in nutrient intakes from human milk and formula. Because sleep/awake and sleep stage patterns affect energy expenditure, we hypothesized that differences in sleep organization between breast-fed and formula-fed infants might account in part for differences in energy expenditure between feeding groups. Sleep stages and cycling of 4-mo-old breast-fed (n = 10) formula-fed (n = 10) infants were studied with simultaneous measurements of energy expenditure. EEG, electrooculogram, body movement by triaxial accelerometry, heart rate, and oxygen saturation were monitored during an overnight sleep session. Sleep stages, nonrapid eye movement (NREM), and rapid eye movement (REM) were determined. Behavioral observations were recorded by video tape and by a technologist. Oxygen consumption and carbon dioxide production were measured with an indirect calorimeter. Total number and duration of sleep cycles, REM latency, number of NREM and REM epochs, and duration of NREM epochs did not differ between feeding groups. Sleep latency was shorter (p < 0.05) and duration of REM epochs longer (p < 0.01) in the formula-fed group. Formula-fed infants spent a higher percentage of sleep time in REM compared with the breast-fed infants (42 versus 34%) (p < 0.003). Conversely, breast-fed infants spent a higher percentage of sleep time in NREM sleep and their heart rates during sleep were lower (114 versus 126 bpm; p < 0.01). Energy expenditure during REM sleep was 13.0 +/- 4.4% higher than during NREM sleep (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Feeding↗
PubMed1992

Lactation performance of rural Mesoamerindians.

Anthropometry, body composition and dietary intake of 30 lactating Otomi Indians of Capulhuac, Mexico, were studied to identify maternal factors which potentially limit lactation and thereby infant growth. Human milk production, milk composition, and maternal dietary intake, body weight, skinfold thicknesses, and body composition were measured at 4 and 6 months postpartum. The 2H2O dose-to-mother method was used to estimate milk production and maternal total body water (TBW). Fat-free mass (FFM) was calculated as TBW/0.73. Body fat was computed as body weight minus FFM. Human milk samples were analyzed for energy, nitrogen, lactose and fat using standard analytical methods. Maternal diet was assessed by three 24-h intake recalls. Mean (SD) milk production was 885 (146) and 869 (150) g/d at 4 and 6 months, respectively. Milk concentrations of protein nitrogen (1.23 (0.17) mg/g) and lactose (66.6 (2.8) mg/g) were comparable to, but the concentrations of fat (22.2 (6.7) mg/g) and energy (0.54 (0.06) kcal/g) were lower than, values observed in economically privileged populations. Maternal height, weight, and BMI were 1.47 (0.06) m, 50.3 (6.0) kg, and 23.4 (3.1) kg/m2, respectively. Maternal TBW, FFM and body fat were 55.8 (4.6)%, 76.4 (6.3)%, and 23.6 (6.4)%, expressed as a percentage of body weight, respectively. Maternal energy and protein intakes averaged 1708 (338) kcal/d and 40 (10) g/d, respectively. Milk production was negatively correlated with maternal body fat (P = 0.006). Energy and fat concentrations in the milk of the Otomi women were positively related to their weight (P = 0.002), BMI (P = 0.05), and body fat (P = 0.004). Energy concentrations in milk were not related to rates of milk production (r = 0.24; P = 0.23). Nor was milk production or composition significantly associated with maternal dietary intake. Lactation performance of these Otomi women correlated significantly with maternal body size and composition, but not current dietary intake.

Adipose Tissue↗
PubMed1991

Measurement of milk intake: tracer-to-infant deuterium dilution method.

The tracer-to-infant deuterium dilution method for the measurement of milk intake was evaluated in twenty breast-fed and twenty formula-fed infants. The isotope method was compared with conventional direct-weighing techniques. Human milk intake was assessed by 5 d test-weighing. Intakes of formula, supplemental foods, and water were determined by pre- and post-weighing of feeding bottles. An oral dose of 200 mg 2H2O/kg body-weight was given to each infant, and urine was sampled daily for 14 d. 2H enrichment of the urine was measured by gas-isotope-ratio mass spectrometry. Milk intakes estimated from the deuterium dilution method were consistently higher than those from direct-weighing; the mean difference between methods was 106 (SD 47) g/d or 14% for the breast-fed group and 70 (SD 155) g/d or 8% for the formula-fed group. Estimates of intake for some infants varied substantially between the two methods of measurement. When the estimated values of human milk intake were corrected for environmental water influx and insensible water loss during breast-feeding, the relative bias decreased to 5%. Correction of the estimated values of formula intake for environmental water influx decreased the relative bias to 1-2%. The acceptability of the deuterium dilution method to determine milk intake depends on the goals and the tolerance for error in group and individual intake estimates of a given study.

Body Height↗
PubMed1991

Energy requirements of breast-fed infants.

Current recommendations for energy intake are reviewed in light of emerging data on energy intakes of breast-fed infants and on total daily energy expenditure of infants. For determination of energy requirements, the historical approach based on observed intakes of healthy infants is compared with a newly proposed approach based on energy expenditure and deposition. A data set of exclusively breast-fed infants is used to illustrate the circuity of either approach. Energy intake, expenditure, and stores must be evaluated in an assessment of dietary adequacy. Ultimately, energy requirements of infants should reflect growth rate, body composition, and level of physical activity conducive to optimal health and neurobehavioral development.

Basal Metabolism↗