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

Abstract

The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO/sub 2/ 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/sup 0/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 O/sub 2/ 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 CO/sub 2/ production.

Authors:
; ;
Publication Date:
Research Org.:
Univ. of Chicago, IL
OSTI Identifier:
6928931
Alternate Identifier(s):
OSTI ID: 6928931
Resource Type:
Journal Article
Resource Relation:
Journal Name: Am. J. Physiol.; (United States)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; DOUBLE LABELLING; ACCURACY; WATER; CARBON DIOXIDE; EXCRETION; HEAVY WATER; IN VIVO; METABOLISM; OXYGEN ISOTOPES; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; CLEARANCE; HYDROGEN COMPOUNDS; ISOTOPES; LABELLING; OXIDES; OXYGEN COMPOUNDS 551001* -- Physiological Systems-- Tracer Techniques

Citation Formats

Schoeller, D.A., Leitch, C.A., and Brown, C.. Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation. United States: N. p., 1986. Web.
Schoeller, D.A., Leitch, C.A., & Brown, C.. Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation. United States.
Schoeller, D.A., Leitch, C.A., and Brown, C.. Mon . "Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation". United States. doi:.
@article{osti_6928931,
title = {Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation},
author = {Schoeller, D.A. and Leitch, C.A. and Brown, C.},
abstractNote = {The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO/sub 2/ 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/sup 0/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 O/sub 2/ 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 CO/sub 2/ production.},
doi = {},
journal = {Am. J. Physiol.; (United States)},
number = ,
volume = ,
place = {United States},
year = {Mon Dec 01 00:00:00 EST 1986},
month = {Mon Dec 01 00:00:00 EST 1986}
}
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  • Experimental investigation of the reaction of light and heavy water vapors with a metallic alloy and the release of hydrogen by batch-mode conversion with a Zr(V{sub 0.5}Fe{sub 0.5}){sub 2} getter is presented. The dependence of cracking of water vapor on the alloy temperature and water vapor pressure is studied. The roles of initial as well as increasing concentrations of hydrogen and oxygen in the alloy are delineated. The conversion rate constant is observed to shift from being surface dissociation process-dependent to bulk diffusion process-dominated during the conversion process. Hydrogen sorption in the alloy and its release during the batch conversionmore » of water vapor, which assumes considerable significance from the perspective of recovering tritium as fuel gas from tritiated water waste, are discussed based on the studies performed that maintained the getter at various temperatures in the range of 100 to 400{degree}C and over a water vapor pressure range of 50 to 500 Pa, with various hydrogen and oxygen concentrations in the getter alloy. 28 refs., 13 figs., 1 tab.« less