Validation of single-sample doubly labeled water method

1989 ◽  
Vol 256 (2) ◽  
pp. R572-R576 ◽  
Author(s):  
M. D. Webster ◽  
W. W. Weathers
Keyword(s):  
Water Flux ◽  
Passerine Bird ◽  
Single Sample ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Water Turnover ◽  
Sample Technique ◽  
Doubly Labeled Water Method ◽  
The One ◽  
Sample Method

We have experimentally validated a single-sample variant of the doubly labeled water method for measuring metabolic rate and water turnover in a very small passerine bird, the verdin (Auriparus flaviceps). We measured CO2 production using the Haldane gravimetric technique and compared these values with estimates derived from isotopic data. Doubly labeled water results based on the one-sample calculations differed from Haldane values by less than 0.5% on average (range -8.3 to 11.2%, n = 9). Water flux computed by the single-sample method differed by -1.5% on average from results for the same birds based on the standard, two-sample technique (range -13.7 to 2.0%, n = 9).

Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation

1986 ◽  
Vol 251 (6) ◽  
pp. R1137-R1143 ◽  
Author(s):  
D. A. Schoeller ◽  
C. A. Leitch ◽  
C. Brown
Keyword(s):  
Water Loss ◽  
Isotope Fractionation ◽  
Isotopic Fractionation ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Water Turnover ◽  
Evaporative Water ◽  
Equilibrium Control ◽  
Doubly Labeled Water Method

The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO2 excretion. To characterize in vivo isotope fractionation, we collected and isotopically analyzed physiological fluids and gases. Breath and transcutaneous water vapor were isotopically fractionated. The degree of fractionation indicated that the former was fractionated under equilibrium control at 37 degrees C, and the latter was kinetically fractionated. Sweat and urine were unfractionated. By use of isotopic balance models, the fraction of water lost via fractionating routes was estimated from the isotopic abundances of body water, local drinking water, and dietary solids. Fractionated water loss averaged 23% (SD = 10%) of water turnover, which agreed with our previous estimates based on metabolic rate, but there was a systematic difference between the results based on O2 and hydrogen. Corrections for isotopic fractionation of water lost in breath and (nonsweat) transcutaneous loss should be made when using labeled water to measure water turnover or CO2 production.

Flux hydriques et métabolisme énergétique dans un peuplement de Lacertidés des îles Kerkennah (Tunisie)

1988 ◽  
Vol 66 (3) ◽  
pp. 555-561 ◽  
Author(s):  
Roland Vernet ◽  
Claude Grenot ◽  
Saïd Nouira
Keyword(s):  
Energy Expenditure ◽  
Daily Activity ◽  
Water Flux ◽  
Sympatric Species ◽  
Doubly Labeled Water ◽  
Daily Energy Expenditure ◽  
Water Turnover ◽  
Semiarid Environment ◽  
Daily Energy ◽  
Active Forager

Water flux and daily energy expenditure were measured with doubly labeled water (3HH18O) in two insectivorous sympatric species of Lacertidae of Kerkennah islands (Tunisia), Eremias olivieri (mean body mass: 1.1 g) and Acanthodactylus pardalis (4.5 g) in a semiarid environment. Water turnover and field metabolic rate of Eremias olivieri (174 μL H2O g−1 d−1 and 250 J g−1 d−1) were, respectively, 2.5 and 5 times higher than those of Acanthodactylus pardalis (70 μL H2O g−1 d−1 and 52 J g−1 d−1). The water turnover of Eremias olivieri is one of the highest known among insectivorous lizards, and the daily energy expenditure of Acanthodactylus pardalis one of the lowest. The most plausible explanations are the differences in the size of the prey eaten by each species at this time of the season and in the duration of daily activity; the daily activity of Acanthodactylus pardalis is short (4.5 h d−1) although it is a sit-and-wait predator, whereas Eremias olivieri is active regularly every day for a longer period (7.5 h d−1) although it is an active forager. The high values of water turnover in Eremias olivieri suggest that food is not the only source of water for lizards in this particular insular environment.

Measurement of CO2 production by the doubly labeled water technique

1986 ◽  
Vol 61 (3) ◽  
pp. 1200-1202 ◽  
Author(s):  
J. R. Speakman ◽  
P. A. Racey
Keyword(s):  
Isotopic Analysis ◽  
Accurate Estimate ◽  
The Body ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Human Metabolism ◽  
Multiple Sampling ◽  
Final Sample ◽  
Nonsteady State ◽  
Sample Method

Recent applications of the doubly labeled water technique to the study of human metabolism have employed multiple sampling of body water over protracted periods, rather than the more traditional method of taking only an initial and final sample for isotopic analysis. In addition fractional turnovers of the body pools have been estimated by fitting curves to the sequential log-converted isotope enrichment against time. By manipulation of data collected in the field in a study of metabolism of vespertilionid bats, it is shown the curve-fitting technique results in an accurate estimate of CO2 production only when the rate of CO2 production is constant. Biologically realistic nonsteady-state conditions result in errors in estimates of CO2 production of up to 30%. In conditions where CO2 production is known to be temporally variable, the more traditional two-sample method may provide a more accurate estimate of CO2 production.

Total energy expenditure in burned children using the doubly labeled water technique

1990 ◽  
Vol 259 (4) ◽  
pp. E576-E585 ◽  
Author(s):  
M. I. Goran ◽  
E. J. Peters ◽  
D. N. Herndon ◽  
R. R. Wolfe
Keyword(s):  
Energy Expenditure ◽  
Total Energy ◽  
Resting Energy Expenditure ◽  
Total Energy Expenditure ◽  
High Rate ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Water Turnover ◽  
Activity Factor ◽  
Basal Energy Expenditure

Total energy expenditure (TEE) was measured in 15 burned children with the doubly labeled water technique. Application of the technique in burned children required evaluation of potential errors resulting from nutritional intake altering background enrichments during studies and from the high rate of water turnover relative to CO2 production. Five studies were discarded because of these potential problems. TEE was 1.33 +/- 0.27 times predicted basal energy expenditure (BEE), and in studies where resting energy expenditure (REE) was simultaneously measured, TEE was 1.18 +/- 0.17 times REE, which in turn was 1.16 +/- 0.10 times predicted BEE. TEE was significantly correlated with measured REE (r2 = 0.92) but not with predicted BEE. These studies substantiate the advantage of measuring REE to predict TEE in severely burned patients as opposed to relying on standardized equations. Therefore we recommend that optimal nutritional support will be achieved in convalescent burned children by multiplying REE by an activity factor of 1.2.

Validation in sheep of the doubly labeled water method for estimating CO2 production

1994 ◽  
Vol 266 (1) ◽  
pp. R169-R179 ◽  
Author(s):  
A. J. Midwood ◽  
P. Haggarty ◽  
B. A. McGaw ◽  
G. S. Mollison ◽  
E. Milne ◽  
...  
Keyword(s):  
Poisson Model ◽  
Carbon Dioxide Production ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Evaporative Water ◽  
Respiration Chamber ◽  
Direct Measurements ◽  
Doubly Labeled Water Method ◽  
The Mean ◽  
Selection Of

Carbon dioxide production (rCO2) was estimated in four sheep over a period of 10 days using doubly labeled water (2H and 18O) and was compared with simultaneous respiration chamber measurements of CO2. The excess 2H and 18O measurements were corrected for the empirically determined effects of isotope rebreathing within the confines of the chambers. A weighted monoexponential curve was then fitted to the data from which isotope flux rates and ultimately rCO2 and water turnover (rH2O) estimates were made. The curve fits were weighted assuming a Poisson model. Selection of this weighting policy did not bias the results, and curvature in the data also appeared to have little effect on the rCO2 estimates. Fractionated evaporative water loss expressed as a fraction of rH2O (X) was estimated from water balance and breath water production estimates; the mean X was 0.145 and ranged from 0.108 to 0.183. Corrections for 2H loss in fecal solids reduced the mean rH2O (4,746 g/day) by 35.5 g/day and increased the mean rCO2 (332.3 l/day) by 21.2 l/day. Further corrections to account for 2H loss in methane (mean production rate 27.2 l/day) reduced rH2O by 33.8 g/day and increased rCO2 by 20.3 l/day. The final isotopic estimates of rH2O were 14.6 +/- 6.59% (n = 4) lower than direct measurements and the mean rCO2 was 3.5 +/- 14.48% (n = 4) lower than the chamber measured rCO2. However, in one of the animals studied the rCO2 deviated markedly from the chamber-derived value, and this discrepancy has yet to be explained. When this animal was excluded from the comparisons, the standard deviation was greatly reduced (+/- 3.6, n = 3) and the mean overall error on rCO2 was +3.6%.

scholarly journals Energy Requirement Assessment and Water Turnover in Japanese College Wrestlers Using the Doubly Labeled Water Method

2017 ◽  
Vol 63 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Hiroyuki SAGAYAMA ◽  
Emi KONDO ◽  
Keisuke SHIOSE ◽  
Yosuke YAMADA ◽  
Keiko MOTONAGA ◽  
...  
Keyword(s):  
Energy Requirement ◽  
Doubly Labeled Water ◽  
Water Turnover ◽  
Doubly Labeled Water Method

Validation of the doubly labeled water method in growing pigs

1994 ◽  
Vol 267 (6) ◽  
pp. R1574-R1588 ◽  
Author(s):  
P. Haggarty ◽  
M. F. Franklin ◽  
M. F. Fuller ◽  
B. A. McGaw ◽  
E. Milne ◽  
...  
Keyword(s):  
Weight Gain ◽  
Growing Pigs ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Rapid Weight Gain ◽  
Sources Of Error ◽  
True Value ◽  
Significant Bias ◽  
Before And After ◽  
Doubly Labeled Water Method

The CO2 production (rCO2) of eight growing pigs was determined by continuous collection of CO2 over 21 days and simultaneously estimated using the doubly labeled water (DLW) method. The aim was to assess the accuracy of the method before and after correction for known sources of error and to test for any residual discrepancy arising from as yet unidentified sources of error. Mass spectrometer accuracy was verified by analyzing serial dilutions of the dose material in the form of an artificial decay curve; no significant bias was detected. The physiological errors were linearly dependent on weight gain. DLW-derived rCO2 (corrected only for fractionated water loss) underestimated the true value by 0.270 l CO2/g wt gain or -8% in the restricted (group R) and -16% in the ad libitum-fed (group AL) groups. Known sources of error accounted for -0.006 (methane), -0.032 (fecal 2H losses), -0.108 (fat synthesis), and -0.146 (changing pool size) l CO2/g wt gain. After correction for these sources of error the DLW-derived rCO2 differed from the true value by -2 +/- 3% in group R and 0 +/- 3% in group AL. Thus there was no significant bias in the DLW method after correction for known sources of error, even during rapid weight gain or at weight stability with or without correction. The precision estimates include both dose and background errors and uncertainty in the correction factors used. Strategies for optimizing precision are presented.

Revision of calculations in the doubly labeled water method for measurement of energy expenditure in humans

1994 ◽  
Vol 267 (6) ◽  
pp. E805-E807 ◽  
Author(s):  
W. A. Coward ◽  
P. Ritz ◽  
T. J. Cole
Keyword(s):  
Experimental Study ◽  
Energy Expenditure ◽  
Recent Work ◽  
Isotope Dilution ◽  
Rate Constants ◽  
Isotope Fractionation ◽  
Co2 Production ◽  
Doubly Labeled Water ◽  
Doubly Labeled Water Method ◽  
The Difference

In the doubly labeled water (DLW) method for the measurement of energy expenditure in humans, the basis of the calculation for CO2 production is the difference between the products of the rate constants for the disappearance of 18O and 2H from body water (KO, and KD, respectively) and the matching isotope dilution spaces (NO and ND, respectively). Thus, omitting corrections for isotope fractionation, CO2 production = 0.5 (KONO-KDND). In this calculation, it is also customary to normalize observed NO and ND values to a fixed value for ND/NO. The increasing use of the method has resulted in the generation of substantially more information on the normal value for ND/NO than existed at the time the method was first developed, and recent work has suggested that revisions of the originally used value of 1.03 may now be deemed appropriate. Values of 1.034 or 1.0427 have recently been suggested, but when applied in energy expenditure studies these estimates would lead to significantly different expenditure measurements. It can, however, be shown from published work and direct experimental study that ND/NO values are method dependent, and for these reasons the lower revised value of 1.034 appears to be more acceptable. The possibility that particular populations may ultimately be shown to be different from 1.034 should not, however, be dismissed entirely, and for this reason we suggest that information derived in individual experiments could be used in a Bayesian fashion to generate new ND/NO estimates. The appropriate techniques are described.

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