Document Detail

Use of isotopically labelled octanoic acid to assess the effect of meal size on gastric emptying.
MedLine Citation:
PMID:  15150821     Owner:  NLM     Status:  MEDLINE    
It has been proposed that the (13)C-octanoic acid breath test (OBT) provides a safe, non-radioactive means of measuring gastric emptying. However, deuterated octanoic acid provides a better marker when compared with scintigraphy, as the kinetics are less complex than those of the (13)C label. The appearance of (2)H in saliva is modelled as a two-compartment body water system, using an asymmetric triangular gastric emptying function. This study compared the (2)H-octanoic acid saliva test (OST) with the OBT in measuring altered states of gastric emptying in the nutritional context of diet manipulation. Gastric emptying was measured using the OST and OBT in a three-way crossover study involving 12 healthy male and female subjects (mean BMI = 23.4 kg/m(2), aged 24-57 years). Following an overnight fast, subjects were given an egg meal, labelled with 10 microL/kg body weight (2)H-octanoic acid and 100 microL (13)C-octanoic acid. The meal was nutritionally manipulated to provide a 1 MJ, 2 MJ or 3 MJ meal. Breath and saliva samples were collected at regular intervals for 6 h, with further saliva samples being collected over four subsequent days. (2)H isotopic enrichment in saliva and (13)C isotopic enrichment in breath were analysed using isotope ratio mass spectrometry and the data fitted to the respective gastric emptying models. The half excretion time (T(1/2) (D)), time to maximum emptying rate (T(1) (D)) and time when emptying is complete (T(2) (D)) were calculated from the (2)H saliva test data, and the lag time (T(lag) (C)), half excretion time (T(1/2) (C)), latency phase (T(lat) (C)) and ascension time (T(asc) (C)) were calculated from the (13)C breath test data. Overall, the OBT correlated well with the OST, with a significant relationship between T(1/2) (C) and T(1/2) (D), a significant relationship between T(lat) (C) and T(1) (D) and finally a significant relationship between T(asc) (C) and T(2) (D). Gastric emptying measured using the OST was significantly faster with the 1 MJ meal (DeltaT(1/2) (D) = -0.77 h vs. 2 MJ, p = 0.004). Increases were also seen when the meal size was increased from 2 MJ to 3 MJ (DeltaT(1/2) (D) = +0.44 h vs. 2 MJ), but these were not significant. These trends were mirrored in the OBT data, with significant differences between 1 MJ and 2 MJ (DeltaT(1/2) (C) = -0.63 h vs. 2 MJ, p = 0.013) and non-significant increases with the larger 3 MJ meal (DeltaT(1/2) (C) = +0.10 h vs. 2 MJ). Total meal calorie content was shown to have an effect on gastric emptying using both the OBT and the OST. The deuterium method allows the direct calculation of the gastric emptying function and could be used as an alternative to gamma scintigraphy, allowing further validation of the (13)C-octanoic acid breath test.
Sarah J Jackson; Leslie J C Bluck; W Andrew Coward
Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Rapid communications in mass spectrometry : RCM     Volume:  18     ISSN:  0951-4198     ISO Abbreviation:  Rapid Commun. Mass Spectrom.     Publication Date:  2004  
Date Detail:
Created Date:  2004-05-19     Completed Date:  2004-07-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8802365     Medline TA:  Rapid Commun Mass Spectrom     Country:  England    
Other Details:
Languages:  eng     Pagination:  1003-7     Citation Subset:  IM    
Copyright Information:
Copyright 2004 John Wiley & Sons, Ltd.
MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK.
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MeSH Terms
Breath Tests / methods
Carbon Isotopes
Cross-Over Studies
Gastric Emptying / physiology*
Mass Spectrometry / methods
Middle Aged
Octanoic Acids / diagnostic use*
Saliva / metabolism
Reg. No./Substance:
0/Carbon Isotopes; 0/Octanoic Acids; 124-07-2/caprylic acid; 7782-39-0/Deuterium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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