Use of [13C18] Oleic Acid and Mass Isotopomer Distribution Analysis to Study Synthesis of Plasma Triglycerides In Vivo: Analytical and Experimental Considerations

2013 ◽  
Vol 85 (13) ◽  
pp. 6287-6294 ◽  
Author(s):  
David G. McLaren ◽  
Helene L. Cardasis ◽  
Steven J. Stout ◽  
Sheng-Ping Wang ◽  
Vivienne Mendoza ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Distribution Analysis ◽  
Plasma Triglycerides ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
Mass Isotopomer

Measuring gluconeogenesis with [2-13C]glycerol and mass isotopomer distribution analysis of glucose

1995 ◽  
Vol 269 (3) ◽  
pp. E516-E523 ◽  
Author(s):  
O. Peroni ◽  
V. Large ◽  
M. Beylot
Keyword(s):  
Glucose Production ◽  
Distribution Analysis ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
Total Glucose ◽  
Glucose Output ◽  
Total Glycerol ◽  
Mass Isotopomer

We tested the validity of the use of [2-13C]glycerol and of the mass isotopomer distribution analysis of glucose for measuring gluconeogenesis in vitro and in vivo. When isolated rat livers (starved for 48 h) were infused with labeled glycerol without or with lactate+pyruvate, gluconeogenesis accounted for > 90% of glucose production. When glucose was added to the infusate so that glucose produced by the liver represented only 80 or 45% of total glucose output, this dilution could be calculated from the mass isotopomer distribution of glucose. When postabsorptive and starved rats were infused with [2-13C]glycerol, gluconeogenesis accounted for 54 +/- 2 and 89 +/- 1%, respectively, of glucose production. However, accurate measures could be obtained, particularly in postabsorptive rats, only with high tracer infusion rates (representing > or = 50% of endogenous glycerol production rate). In both groups of rats, these infusion rates resulted in an increase in total glycerol turnover rate and gluconeogenesis from glycerol. In addition, hepatic concentration of glycerol 3-phosphate was increased. In conclusion, [2-13C]glycerol infusion and mass isotopomer distribution analysis of glucose appear to be useful methods for studies of gluconeogenesis in vitro and in vivo; however, accurate measurements in vivo can be obtained only at the expense of some perturbation of the metabolic pathway studied.

Mass isotopomer distribution analysis: a technique for measuring biosynthesis and turnover of polymers

1992 ◽  
Vol 263 (5) ◽  
pp. E988-1001 ◽  
Author(s):  
M. K. Hellerstein ◽  
R. A. Neese
Keyword(s):  
Distribution Analysis ◽  
Polymeric Product ◽  
Precursor Pool ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
Fractional Synthesis ◽  
Precursor Molecules ◽  
Isotope Content ◽  
Mass Isotopomer

Mass isotopomer distribution analysis (MIDA) is a technique for measuring biosynthesis and turnover of polymers in vivo. A stable isotopically enriched precursor is administered, and the relative abundances of different mass isotopomers in the polymer of interest are measured by mass spectrometry (MS). By comparison of statistical distributions predicted from the binomial or multinomial expansion to the pattern of excess isotopomer frequencies observed in the polymer, the enrichment of the biosynthetic precursor subunits (p) for newly synthesized polymers is calculated. MIDA thereby provides a solution to the problem of determining the isotope content in the actual precursor molecules that entered a particular polymeric product (the “true” precursor). The fraction of polymer molecules in a mixture that were newly synthesized during an isotopic experiment (fractional synthesis) can then be calculated. We describe some mathematical characteristics of MIDA and point out certain advantageous features. For example, mathematical estimates of p remain valid even if there does not exist a single anatomic or functional precursor pool. The interpretation of decay curves of endogenously labeled polymers may be improved by the use of higher mass isotopomers, which better fulfill the assumption of flash labeling. By combining fractional synthesis values with rate constants of decay, absolute endogenous synthesis rates can be calculated. Thus, by using probability logic combined with MS analysis, MIDA allows dynamic measurements to be made through analyses on a polymer alone during both isotopic incorporation and decay phases. The method has been applied to fatty acids, cholesterol, and glucose and is potentially applicable to nucleic acids, porphyrins, perhaps proteins, and many other classes of polymers.

A critical evaluation of mass isotopomer distribution analysis of gluconeogenesis in vivo

1999 ◽  
Vol 277 (1) ◽  
pp. E154-E160 ◽  
Author(s):  
Stephen F. Previs ◽  
Gary W. Cline ◽  
Gerald I. Shulman
Keyword(s):  
Critical Evaluation ◽  
Glucose Production ◽  
Distribution Analysis ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
Group I ◽  
Total Glucose ◽  
Total Glycerol ◽  
Mass Isotopomer

There are conflicting reports concerning the reliability of mass isotopomer distribution analysis (MIDA) for estimating the contribution of gluconeogenesis to total glucose production (f) during [13C]glycerol infusion. 1 We have evaluated substrate-induced effects on rate of appearance (Ra) of glycerol and glucose and f during [2-13C]glycerol infusion in vivo. Five groups of mice were fasted for 30 h and then infused with [2-13C]glycerol at variable rates and variable 13C enrichments ( group I: 20 μmol ⋅ kg−1 ⋅ min−1, 99% 13C; group II: 60 μmol ⋅ kg−1 ⋅ min−1, 60% 13C; group III: 60 μmol ⋅ kg−1 ⋅ min−1, 99% 13C; group IV: 120 μmol ⋅ kg−1 ⋅ min−1, 40% 13C; or group V: 120 μmol ⋅ kg−1 ⋅ min−1, 99% 13C). The total glycerol Ra increased from ∼104 to ∼157 and to ∼210 μmol ⋅ kg−1 ⋅ min−1as the infusion of [2-13C]glycerol increased from 20 to 60 and to 120 μmol ⋅ kg− 1 ⋅ min−1, respectively. As the amount of 99% enriched [2-13C]glycerol increased from 20 to 60 and to 120 μmol ⋅ kg−1 ⋅ min−1( groups I, III, and V, respectively), plasma glycerol enrichment increased from ∼21 to ∼42 and to ∼57% and the calculated f increased from ∼27 to ∼56 and to ∼87%, respectively. Similar plasma glycerol enrichments were observed in groups I, II, and IV (i.e., ∼21–24%), yet f increased from ∼27 to ∼57 and to ∼86% in groups II and IV, respectively. Estimates of absolute gluconeogenesis increased from ∼14 to ∼33 and ∼86 μmol ⋅ kg−1 ⋅ min−1as the infusion of [2-13C]glycerol increased from 20 to 60 and 120 μmol ⋅ kg−1 ⋅ min−1. Plausible estimates of f were obtained only under conditions that increased total glycerol Ra∼2-fold ( P < 0.001) and increased glucose Ra ∼1.5-fold ( P < 0.01) above basal. We conclude that in 30-h fasted mice, 1) estimates of f by MIDA with low infusion rates of [2-13C]glycerol yield erroneous results and 2) reasonable estimates of f are obtained at glycerol infusion rates that perturb glycerol and glucose metabolism.

Determination of protein synthesis in vivo using labeling from deuterated water and analysis of MALDI-TOF spectrum

2008 ◽  
Vol 104 (3) ◽  
pp. 828-836 ◽  
Author(s):  
Gary Guishan Xiao ◽  
Meena Garg ◽  
Shu Lim ◽  
Derek Wong ◽  
Vay Liang Go ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Enrichment Ratio ◽  
Distribution Analysis ◽  
Deuterated Water ◽  
Isotopomer Distribution ◽  
Maldi Tof ◽  
Mass Isotopomer Distribution Analysis ◽  
In Vivo Labeling ◽  
Mass Isotopomer

This paper describes a method of determining protein synthesis and turnover using in vivo labeling of protein with deuterated water and analysis of matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI-TOF) spectrum. Protein synthesis is calculated using mass isotopomer distribution analysis instead of precursor to product amino acid enrichment ratio. During protein synthesis, the incorporation of deuterium from water changes the mass isotopomer distribution (isotope envelop) according to the number of deuterium atoms (0, 1, 2, 3, etc.) incorporated, and the distribution of the protein with 0, 1, 2, 3,… atoms of deuterium follows a binomial distribution. A mathematical algorithm by which the distribution of deuterium isotopomers can be extracted from the observed MALDI-TOF spectrum is presented. Since deuterium isotopomers are unique to newly synthesized proteins, the quantitation of their distribution provides a method for the quantitation of newly synthesized proteins. The combined use of postsource decay sequence identification and mass isotopomer distribution analysis makes the use of in vivo labeling with deuterated water a precise method to determine specific protein synthesis.

scholarly journals Software LS-MIDA for efficient mass isotopomer distribution analysis in metabolic modelling

2013 ◽  
Vol 14 (1) ◽  
pp. 218 ◽  
Author(s):  
Zeeshan Ahmed ◽  
Saman Zeeshan ◽  
Claudia Huber ◽  
Michael Hensel ◽  
Dietmar Schomburg ◽  
...  
Keyword(s):  
Distribution Analysis ◽  
Metabolic Modelling ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
Mass Isotopomer

Measurement of gluconeogenesis in exercising men by mass isotopomer distribution analysis

2002 ◽  
Vol 93 (1) ◽  
pp. 233-241 ◽  
Author(s):  
Jeff K. Trimmer ◽  
Jean-Marc Schwarz ◽  
Gretchen A. Casazza ◽  
Michael A. Horning ◽  
Nestor Rodriguez ◽  
...  
Keyword(s):  
Rest Period ◽  
Glucose Production ◽  
Moderate Intensity ◽  
Dependent Manner ◽  
Distribution Analysis ◽  
Moderate Intensity Exercise ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
The Difference ◽  
Mass Isotopomer

We evaluated the hypothesis that coordinated adjustments in absolute rates of gluconeogenesis (GNGab) and hepatic glycogenolysis (Gly) would maintain euglycemia and match glucose production (GP) to peripheral utilization during rest and exercise. Specifically, we evaluated the extent to which gradations in exercise power output would affect the contribution of GNGab to GP. For these purposes, we employed mass isotopomer distribution analysis (MIDA) and isotope-dilution techniques on eight postabsorptive (PA) endurance-trained men during 90 min of leg cycle ergometry at 45 and 65% peak O2 consumption (V˙o 2 peak; moderate and hard intensities, respectively) and the preceding rest period. GP was constant in resting subjects, whereas the fraction from GNG (fGNG) increased over time during rest (22.3 ± 0.9% at 11.25 h PA vs. 25.6 ± 0.9% at 12.0 h PA, P < 0.05). In the transition from rest to exercise, GP increased in an intensity-dependent manner (rest, 2.0 ± 0.1; 45%, 4.0 ± 0.4; 65%, 5.84 ± 0.64 mg · kg−1 · min−1, P < 0.05), although glucose rate of disappearance exceeded rate of appearance during the last 30 min of exercise at 65%V˙o 2 peak. Compared with rest, increases in GP were sustained by 92 and 135% increments in GNGab during moderate- and hard-intensity exercises, respectively. Correspondingly, Gly (calculated as the difference between GP and MIDA-measured GNGab) increased 100 and 203% over rest during the two exercise intensities. During moderate-intensity exercise, fGNG was the same as at rest; however, during the harder exercise fGNG decreased significantly to account for only 21% of GP. The highest sustained GNGab observed in these trials on PA men was 1.24 ± 0.3 mg · kg−1 · min−1. We conclude that, after an overnight fast, 1) absolute GNG rates increased with intensity of effort despite a reduced fGNG at 65% V˙o 2 peak, 2) during exercise Gly is more responsible than GNGab for maintaining GP, and 3) in 12-h fasted men, neither increased Gly or GNGab nor was their combination able to maintain euglycemia during prolonged hard (65%V˙o 2 peak) exercise.

Newly synthesized cholesterol in human bile and plasma: quantitation by mass isotopomer distribution analysis

1997 ◽  
Vol 272 (2) ◽  
pp. G367-G373 ◽  
Author(s):  
K. Empen ◽  
K. Lange ◽  
E. F. Stange ◽  
J. Scheibner
Keyword(s):  
De Novo ◽  
Charge Ratio ◽  
Gas Chromatography Mass Spectrometry ◽  
Distribution Analysis ◽  
Biliary Cholesterol ◽  
Human Bile ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
Fractional Synthesis ◽  
Mass Isotopomer

The purpose of this study was to quantitate the contribution of newly synthesized cholesterol to bile and plasma in humans. Eight healthy volunteers were intravenously infused with 0.125 mmol of [1-(13)C]acetate per kilogram per hour for 15 h. During continuous enteral nutrition, plasma aliquots and samples of duodenal bile were collected hourly. The trimethysilylether of unesterified cholesterol was analyzed by gas chromatography-mass spectrometry for quantitation of the mass fragments M(+0) [mass-to-charge ratio (m/z) 368], M(+1) (m/z 369), M(+2) (m/z 370), M(+3) (m/z 371), and M(+4) (m/z 372). The fractional syntheses of plasma and biliary cholesterol were determined using mass isotopomer distribution analysis. After 6 h of infusion, the 13C enrichment of the acetate pool remained constant at 12%. The fractional synthesis increased continuously during [13C]acetate infusion and reached 4.2% and 5.3% in cholesterol of plasma and bile, respectively. Both were highly correlated, but the fractional synthesis of biliary cholesterol exceeded that of plasma (P < 0.05). It may be concluded that the contribution of de novo cholesterol synthesis to bile exceeds that to plasma but is minor in humans.

scholarly journals Limitations of the Mass Isotopomer Distribution Analysis of Glucose to Study Gluconeogenesis

1995 ◽  
Vol 270 (34) ◽  
pp. 19806-19815 ◽  
Author(s):  
Stephen F. Previs ◽  
Charles A. Fernandez ◽  
Dawei Yang ◽  
Maxim V. Soloviev ◽  
France David ◽  
...  
Keyword(s):  
Distribution Analysis ◽  
Isotopomer Distribution ◽  
Mass Isotopomer Distribution Analysis ◽  
Mass Isotopomer
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