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  • 1
    Electronic Resource
    Electronic Resource
    The contribution of naturally labelled 13C fructose to glucose appearance in humans (1993)
    Springer
    Diabetologia 36 (1993), S. 338-345 
    Details
    ISSN: 1432-0428
    Keywords: Fructose ; glucose ; stable isotopes ; [13C] ; mass spectrometry ; nutrition ; human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Among monosaccharides, fructose has a small hyperglycaemic effect. In order to better explain the mechanisms which cause this metabolic property, we used tracers labelled with stable isotopes (deuterated glucose and naturally 13C labelled fructose) to quantify the overall glucose appearance, the rate of appearance in plasma of the 13C glucose synthesized from fructose, and the fructose oxidation in vivo in man during a 6-h period following ingestion of 0.5 and 1 g · kg−1 fructose. Fructose had a very small effect on overall glucose appearance (NS). During the 6 h of the study, it was found that the overall glucose appearance was 0.87±0.06 and 0.89±0.06 g · kg−1 (NS). The amount of glucose synthesized from fructose was 0.27±0.04 and 0.51±0.03 g · kg−1 (p〈0.01) representing 31% and 57% of overall glucose appearance (p〈0.01); the non-fructose glucose production was 0.60±0.02 and 0.38±0.03 g · kg−1 (p〈0.05) after the 0.5 and 1 g · kg−1 load, respectively. Fructose oxidation was 0.28±0.03 and 0.59±0.07 g · kg−1 after the 0.5 and 1 g · kg−1 load respectively (p〈0.01) representing 56% and 59% of the fructose loads (NS). These data show that the low hyperglycaemic effect of fructose is explained by its very small effect on overall glucose appearance and that fructose has a sparing effect on glucose metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00400238
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of human ketone body kinetics using stable-isotope labelled tracers (1986)
    Springer
    Diabetologia 29 (1986), S. 90-96 
    Details
    ISSN: 1432-0428
    Keywords: Acetoacetate ; β-hydroxybutyrate ; ketogenesis ; ketone body kinetics ; stable isotopes ; mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to avoid the use of radioactive tracers for the determination of human ketone body turnover, we have developed a method using a primed-continuous infusion of 13C-labelled acetoacetate or D-β-hydroxybutyrate. Determination of the mole percent enrichment of blood acetoacetate and D-β-hydroxybutyrate was performed by gas chromatography/mass spectrometry. In the post-absorptive state, the mean total ketone body appearance rate, determined in four subjects, was 3.74 μmol · kg−1 · min−1 using [3,4-13 C2] acetoacetate and 2.76 μmol · kg−1 · min−1 using [3-13C]D-β-hydroxybutyrate, values in agreement with those reported in studies with 14C-labelled tracers. In order to evaluate the usefulness of the method for determination of ketone body kinetics in non steady-state conditions, we infused four subjects with natural sodium acetoacetate and calculated the isotopically determined total ketone body appearance rate using a single compartment model (volume of distribution 0.201/kg; functional pool fraction: 1). During the tests with [3,4-13C2]-acetoacetate, the actual infusion rates of natural acetoacetate were 7.3±0.3, 14.6±0.8, 21.9±1.2 and 10.9 ± 0.6 μ mol · kg−1 · min−1 whereas the corresponding isotopically determined total ketone body appearance rates were respectively 9.2±1.0, 16.3±0.7, 23.1±1.1 and 10.7±0.8 μmol· kg−1 · min−1. During the tests with [3-13C]D-β-hydroxybutyrate, the actual infusion rates were 8.4 ± 0.5, 16.8 ± 0.9, 25.2 ±1.4 and 12.6±0.8 μmol · kg−1 · min−1, and the isotopically determined appearance rates respectively 11.1±0.7, 16.7±0.7, 25.0±1.1 and 11.1 ± 0.7 μmol · kg−1 · min−1. Thus, using either tracer we found a good agreement between acetoacetate infusion rate and tracer-determined appearance rate of ketone bodies. In conclusion, the present method may be used to determine human ketone body kinetics under steady-state and non steady-state conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00456116
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Use of a new gas chromatograph isotope ratio mass spectrometer to trace exogenous 13C labelled glucose at a very low level of enrichment in man (1990)
    Springer
    Diabetologia 33 (1990), S. 449-456 
    Details
    ISSN: 1432-0428
    Keywords: Stable isotope ; [13C] glucose ; mass spectrometry ; human ; oral glucose load ; gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The use of 13C labelled glucose in human metabolic studies has been limited by the high cost of the tracer and the problems of measuring low 13C isotopic abundance in plasma glucose. In the present work we describe a new gas chromatograph-isotope ratio mass spectrometer allowing the measurement of a 0.001 atom % increase in 13C abundance over baseline, on a nanomole glucose sample. Studies were performed in rats and in human subjects. The rate of glucose appearance in 24 h fasted rats using D-[1-13C] glucose as tracer and analysed by this new method was found to be 10.4±0.7 mg·kg−1· min−1, a value 21% lower than that found using D-[6,6-2H2] glucose as tracer (13.1±1.1 mg· kg−1· min−1) analysed by classic gas chromatography-mass spectrometry. The new method was also used to trace, in combination with D-[6,6 2H2] glucose, the metabolic fate in human subjects of two oral glucose loads (0.5 g· kg·−1), 1 g· kg ·−1) labelled with 0.1% D-[U-13C] glucose. During the six hours following the glucose load, it was found that total glucose appearance was 0.97±0.04 g· kg·−1 and 1.2±0.04 g· kg·−1, exogenous glucose appearance was 0.51±0.02 g· kg·−1 and 0.84±0.04 g· kg·−1, endogenous glucose production was 0.44±0.04 g· kg·−1 and 0.35±0.06 g·kg·−1 after the 0.5 and 1 g·kg·−1 load respectively. These values are similar to those reported using glucose labelled with radioactive isotopes. These results show that reliable kinetic parameters of glucose metabolism can be determined, without health hazard, in humans, at low cost, using 13C labelled glucose analysed with a new gas chromatograph-isotope ratio mass spectrometer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00405104
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    Paper (German National Licenses)
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