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1 LOCUS for Homocysteine and Related Vitamins, University of Bergen, N-5021 Bergen, Norway.
aAddress correspondence to this author at: LOCUS for Homocysteine and Related Vitamins, Department of Pharmacology, University of Bergen, N-5021 Bergen, Norway. Fax 47-55-973115; e-mail per.ueland{at}ikb.uib.no.
Background: The quaternary ammonium compounds, choline and betaine, and dimethylglycine (DMG) reside along a metabolic pathway linked to the synthesis of neurotransmitters and membrane phospholipids and to homocysteine remethylation and, therefore, folate status. Lack of a convenient, high-throughput method for the determination of these compounds has prevented population-based studies of their possible associations with lifestyle, nutrition, and chronic diseases.
Methods: Serum or plasma samples were deproteinized by mixing with three volumes of acetonitrile that contained d9-choline and d9-betaine as internal standards. We used a normal-phase silica column for the separation of choline (retention time, 2.8 min), betaine (1.3 min), DMG (1.15 min), and internal standards, which were detected as positive ions by tandem mass spectroscopy in the multiple-reaction monitoring mode, using the molecular transitions m/z 104
60 (choline), m/z 11369 (d9-choline), m/z 11859 (betaine), m/z 12768 (d9-betaine), and m/z 10458 (DMG).
Results: For all three metabolites, the assay was linear in the range 0.4–400 µmol/L, and the lower limit of the detection (signal-to-noise ratio = 5) was 
0.3 µmol/L. The within- and between-day imprecision (CVs) was 2.1–7.2% and 3.5–8.8%, respectively. The analytical recovery was 87–105%. The fasting plasma concentrations (median, 25th–75th percentiles) were 8.0 (7.0–9.3) µmol/L for choline, 31.7 (27.0–41.1) µmol/L for betaine, and 1.66 (1.30–2.02) µmol/L for DMG in 60 healthy blood donors. In individuals who had eaten a light breakfast, plasma concentrations of all three metabolites were significantly (25–30%) higher than in fasting individuals.
Conclusion: This is the first method for the combined measurement of choline, betaine, and DMG in human plasma or serum. The assay is characterized by simple sample preparation, no derivatization, high throughput, imprecision (CV) <10%, detection limits below the values seen in volunteers, and the high specificity provided by tandem mass spectroscopy.
The following articles in journals at HighWire Press have cited this article:
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  S. V. Konstantinova, G. S. Tell, S. E. Vollset, O. Nygard, O. Bleie, and P. M. Ueland Divergent Associations of Plasma Choline and Betaine with Components of Metabolic Syndrome in Middle Age and Elderly Men and Women J. Nutr., May 1, 2008; 138(5): 914 - 920. [Abstract] [Full Text] [PDF]
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 C. Signore, P. M. Ueland, J. Troendle, and J. L Mills Choline concentrations in human maternal and cord blood and intelligence at 5 y of age Am. J. Clinical Nutrition, April 1, 2008; 87(4): 896 - 902. [Abstract] [Full Text] [PDF]
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 B. Yue, E. Pattison, W. L. Roberts, A. L. Rockwood, O. Danne, C. Lueders, and M. Mockel Choline in Whole Blood and Plasma: Sample Preparation and Stability Clin. Chem., March 1, 2008; 54(3): 590 - 593. [Abstract] [Full Text] [PDF]
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J. M. Wallace, M. P Bonham, J. Strain, E. M Duffy, P. J Robson, M. Ward, H. McNulty, P. W Davidson, G. J Myers, C. F Shamlaye, et al. Homocysteine concentration, related B vitamins, and betaine in pregnant women recruited to the Seychelles Child Development Study Am. J. Clinical Nutrition, February 1, 2008; 87(2): 391 - 397. [Abstract] [Full Text] [PDF]
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O. Midttun, S. Hustad, J. Schneede, S. E Vollset, and P. M Ueland Plasma vitamin B-6 forms and their relation to transsulfuration metabolites in a large, population-based study Am. J. Clinical Nutrition, July 1, 2007; 86(1): 131 - 138. [Abstract] [Full Text] [PDF]
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 P. I. Holm, S. Hustad, P. M. Ueland, S. E. Vollset, T. Grotmol, and J. Schneede Modulation of the Homocysteine-Betaine Relationship by Methylenetetrahydrofolate Reductase 677 C->T Genotypes and B-Vitamin Status in a Large-Scale Epidemiological Study J. Clin. Endocrinol. Metab., April 1, 2007; 92(4): 1535 - 1541. [Abstract] [Full Text] [PDF]
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A. Fardet, C. Canlet, G. Gottardi, B. Lyan, R. Llorach, C. Remesy, A. Mazur, A. Paris, and A. Scalbert Whole-Grain and Refined Wheat Flours Show Distinct Metabolic Profiles in Rats as Assessed by a 1H NMR-Based Metabonomic Approach J. Nutr., April 1, 2007; 137(4): 923 - 929. [Abstract] [Full Text] [PDF]
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S. M. Innis and D. Hasman Evidence of Choline Depletion and Reduced Betaine and Dimethylglycine with Increased Homocysteine in Plasma of Children with Cystic Fibrosis J. Nutr., August 1, 2006; 136(8): 2226 - 2231. [Abstract] [Full Text] [PDF]
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Y. Wang, D. Zhong, J. P. Fawcett, and J. Gu Autosampler Programming for Improved Sample Throughput in Liquid Chromatography/Mass Spectrometry Clin. Chem., November 1, 2005; 51(11): 2216 - 2218. [Full Text] [PDF]
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A. M Molloy, J. L Mills, C. Cox, S. F Daly, M. Conley, L. C Brody, P. N Kirke, J. M Scott, and P. M Ueland Choline and homocysteine interrelations in umbilical cord and maternal plasma at delivery Am. J. Clinical Nutrition, October 1, 2005; 82(4): 836 - 842. [Abstract] [Full Text] [PDF]
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A. Melse-Boonstra, P. I Holm, P. M Ueland, M. Olthof, R. Clarke, and P. Verhoef Betaine concentration as a determinant of fasting total homocysteine concentrations and the effect of folic acid supplementation on betaine concentrations Am. J. Clinical Nutrition, June 1, 2005; 81(6): 1378 - 1382. [Abstract] [Full Text] [PDF]
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F. V Velzing-Aarts, P. I Holm, M R. Fokkema, F. P van der Dijs, P. M Ueland, and F. A Muskiet Plasma choline and betaine and their relation to plasma homocysteine in normal pregnancy Am. J. Clinical Nutrition, June 1, 2005; 81(6): 1383 - 1389. [Abstract] [Full Text] [PDF]
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 P. I. Holm, P. M. Ueland, S. E. Vollset, O. Midttun, H. J. Blom, M. B.A.J. Keijzer, and M. den Heijer Betaine and Folate Status as Cooperative Determinants of Plasma Homocysteine in Humans Arterioscler. Thromb. Vasc. Biol., February 1, 2005; 25(2): 379 - 385. [Abstract] [Full Text] [PDF]
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P. I. Holm, O. Bleie, P. M. Ueland, E. A. Lien, H. Refsum, J. E. Nordrehaug, and O. Nygard Betaine as a Determinant of Postmethionine Load Total Plasma Homocysteine Before and After B-Vitamin Supplementation Arterioscler. Thromb. Vasc. Biol., February 1, 2004; 24(2): 301 - 307. [Abstract] [Full Text]
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