Determination of the isotope enrichment of one or a mixture of two stable labelled tracers of the same compound using the complete isotopomer distribution of an ion fragment; theory and application toin vivo human tracer studies

Vogt, J.; Chapman, T. E.; Wagner, David; Young, Vernon R.; Burke, John F.

doi:10.1002/bms.1200221008

Cited by 40 publications

(22 citation statements)

References 19 publications

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“…Thus, we can simplify eq 6 to: (9) Note that the negative values of j correspond to M−1 and M−2 in the unlabeled spectrum shifted upward by one and two masses in eq 9 at a 0(−1) and a 0(−2) , respectively. Theoretically, the intensities for these masses should be zero.…”

Section: Definitions Of Terms and Key Equations Of The Methodsmentioning

confidence: 99%

Determination of Complex Isotopomer Patterns in Isotopically Labeled Compounds by Mass Spectrometry

Jennings

Matthews

2005

Anal. Chem.

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A classic problem in analytical chemistry has been determination of individual components in a mixture without availability of the pure individual components. Measurement of the distribution of isotopomers in a labeled compound or mixture of labeled compounds is an example of this problem that is commonly encountered when stable isotopically labeled metabolites are used to determine in vivo kinetics and metabolism. We present a method that uses the measured mass spectral data of the unlabeled material to represent any and all combinations of isotopomer variations of that material and to determine abundances of these isotopomers. Although examples of the method are presented for gas chromatography-mass spectrometry, the method is applicable to any type of mass spectrometry data. The method also accounts for errors induced by mass spectrometer ionization and resolution effects. To demonstrate this method, we determined the isotopomer distributions of samples of 13 C-labeled leucine and glucose for both highly enriched isotopomers and labeled isotopomers present in low abundance against a natural isotopic abundance background. The method accurately and precisely determined isotopomer identity and abundance in the labeled materials without adding noise or error that was not inherent in the original mass spectral data. In examples shown here isotopomer uncertainties were calculated with relative standard errors of <1% from good quality mass spectral data.

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Section: Definitions Of Terms and Key Equations Of The Methodsmentioning

confidence: 99%

Determination of Complex Isotopomer Patterns in Isotopically Labeled Compounds by Mass Spectrometry

Jennings

Matthews

2005

Anal. Chem.

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“…To calculate the mole fraction of the labeled aminoadipic acid in the experimental samples, a linear prediction equation was generated based on theoretical calculations (28). These calculations accounted for the distribution of masses into the unlabeled aminoadipic acid.…”

Section: [ 13 C]aminoadipic Acid Tracer Studiesmentioning

confidence: 99%

Twenty-four–hour intravenous and oral tracer studies with L-[1-13C]-2-aminoadipic acid and L-[1-13C]lysine as tracers at generous nitrogen and lysine intakes in healthy adults

El-Khoury¹,

Basile²,

Beaumier³

et al. 1998

The American Journal of Clinical Nutrition

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“…The origin of this M + 1 ornithine is presumably via the reversible ornithine aminotransferase reaction, during which L-glutamric-y-semialdehyde is formed, resulting in the loss of one 2H atom at the C-5 position (5 The ion clusters of all three tracers determined in the negative ion chemical ionization mode overlapped with the labeled products of the other tracers. Thus, a multiple linear regression approach was used to calculate the isotopic abundances of the amino acids from the mass spectrometry data, as has been explained in detail for isotopologs oftyrosine and leucine as tracers (10). The concentrations of amino acids in the tracer infusates and in blood plasma were determined by high-performance liquid chromatography as described (4).…”

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confidence: 99%

The plasma flux and oxidation rate of ornithine adaptively decline with restricted arginine intake.

Castillo

Sánchez

Chapman

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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We hypothesized recently that arginine ho- established by medical history, physical examination, analysis of blood cell count, routine biochemical profile, and urinalysis. Their daily food and nutrient intakes were calculated to maintain body weight based on a dietary history and an estimate of the subject's usual level of physical activity. Subjects were encouraged to maintain their customary levels of physical activity but did not participate in competitive sports. The experimental protocol was approved by the Advisory Committee of the CRC. Subjects signed consent forms and were paid for their participation in the study.They consumed the arginine-rich (Arg-rich) diet for 6 days and on the morning of day 7 they received primed, constant intravenous tracer infusions of L-[guanidino-'5N2; 5,5-2H]arginine and L- [5-13C]ornithine. This tracer study was followed immediately by a second 6-day experimental period during which an argnine-free (Arg-free) diet was consumed. Again, on the morning of day 7 an intravenous infusion protocol was conducted as described above. The experimental diet was based on isonitrogenous Arg-rich and Arg-free L-amino acid mixtures, as described (4). The major energy source was given in the form of protein-free wheat starch cookies. The daily intake, prior to the tracer infusion studies, was consumed as three separate meals at 0800, 1200, and 1700 h. Meals were prepared in the CRC by the dietary staff.Tracer Infusion Studies. The isotope-infusion protocol lasted for 8 h. During the first 3 h, the subjects remained in the postabsorptive state (fast state), following their 10-to 12-h overnight fast. This phase was followed immediately by a 5-h fed state during which subjects received small, equal meals at 30-min intervals to supply over this period half of the amino acid intake received on the previous days. The details of procedures that were followed immediately before and during the infusion protocol have been presented (4,8).

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Determination of the isotope enrichment of one or a mixture of two stable labelled tracers of the same compound using the complete isotopomer distribution of an ion fragment; theory and application toin vivo human tracer studies

Cited by 40 publications

References 19 publications

Determination of Complex Isotopomer Patterns in Isotopically Labeled Compounds by Mass Spectrometry

Determination of Complex Isotopomer Patterns in Isotopically Labeled Compounds by Mass Spectrometry

Twenty-four–hour intravenous and oral tracer studies with L-[1-13C]-2-aminoadipic acid and L-[1-13C]lysine as tracers at generous nitrogen and lysine intakes in healthy adults

The plasma flux and oxidation rate of ornithine adaptively decline with restricted arginine intake.

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