Three Different Methods for the Determination of Total Homocysteine in Plasma

Poele-Pothoff, M.T.W.B. te; Berg, M. van den; Franken, D. G.; Boers, G.H.J.; Jakobs, Cornelis; Kroon, Ingrid; Eskes, T.K.A.B.; Trijbels, J. M. F.; Blom, Henk J.

doi:10.1177/000456329503200218

Cited by 138 publications

(64 citation statements)

References 5 publications

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“…Total Hcy levels secreted by hMSCs and MC3T3 cells were determined in the cell culture medium by an automated HPLC method with reverse-phase separation and fluorescent detection as described earlier [28]. MMA concentrations in the culture medium were measured with the use of a liquid chromatography mass spectrometry method (LC-MS-MS).…”

Section: Determination Of Hcy and Mma Levelsmentioning

confidence: 99%

Vitamin B12 Deficiency Stimulates Osteoclastogenesis via Increased Homocysteine and Methylmalonic Acid

et al. 2009

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The risk of nutrient deficiencies increases with age in our modern Western society, and vitamin B 12 deficiency is especially prevalent in the elderly and causes increased homocysteine (Hcy) and methylmalonic acid (MMA) levels. These three factors have been recognized as risk factors for reduced bone mineral density and increased fracture risk, though mechanistic evidence is still lacking. In the present study, we investigated the influence of B 12 , Hcy, and MMA on differentiation and activity of bone cells. B 12 deficiency did not affect the onset of osteoblast differentiation, maturation, matrix mineralization, or adipocyte differentiation from human mesenchymal stem cells (hMSCs). B 12 deficiency caused an increase in the secretion of Hcy and MMA into the culture medium by osteoblasts, but Hcy and MMA appeared to have no effect on hMSC osteoblast differentiation. We further studied the effect of B 12 , Hcy, and MMA on the formation of multinucleated tartrate-resistant acid phosphatase-positive osteoclasts from mouse bone marrow. We observed that B 12 did not show an effect on osteoclastogenesis. However, Hcy as well as MMA were found to induce osteoclastogenesis in a dose-dependent manner. On the basis of these results, we conclude that B 12 deficiency may lead to decreased bone mass by increased osteoclast formation due to increased MMA and Hcy levels.Osteoporosis is a complex multifactorial disease with a strong genetic component, but lifestyle factors are also important for maintenance of bone mass. Nutrition is one of the factors that contributes to bone health. During the first decades of life, adequate intake of calcium and vitamin D is essential to establish peak bone mass (see [1,2] and references therein). It has also been observed that nutritional deficiencies can cause impaired growth and skeletal abnormalities during childhood [3], while in adults inadequate intake of nutrients such as proteins, vitamins, and minerals has been associated with loss of bone quality [2,4]. Nutritional deficiency is very common in the elderly, emphasizing that adequate nutrient intake may slow down the age-related loss of bone mass.A challenge in nutrition research is to identify food components that contribute to the maintenance of bone health. During the last years, vitamin B 12 has gained particular attention since a number of epidemiological studies have reported a correlation between B 12 status and bone quality and fracture risk [5][6][7][8][9]. The micronutrient B 12 is involved as a cofactor in two enzymatic reactions [10]. The enzyme methionine synthase requires B 12 for the remethylation of homocysteine (Hcy) into methionine. The other enzyme dependent on B 12 is methylmalonyl-CoA mutase, which catalyzes the conversion of methylmalonyl-CoA into succinyl-CoA. As a consequence of B 12 deficiency, these

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Section: Determination Of Hcy and Mma Levelsmentioning

confidence: 99%

Vitamin B12 Deficiency Stimulates Osteoclastogenesis via Increased Homocysteine and Methylmalonic Acid

et al. 2009

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“…The following parameters were calculated from the plasma concentrations of [6R] and [6S] 5-MTHF acid stereoisomers obtained up to 12 h after administration of single-dose folic acid or 5-MTHF: C max (ng ml À1 ) (the highest concentration of the diastereoisomer in plasma), t max (h) (the time when C max is achieved), C 0 -12z (ng ml À1 ) (the concentration of the diastereoisomer at sampling time z), AUC 0 -12z (the area under the curve of the plasma concentration versus time up to sampling time z), AUC N (the area under the curve of the plasma concentration versus time using the equation: AUC N ¼ AUC z þ C z l z À1 ) and t 1/2 (h). Plasma homocysteine levels were determined at baseline, 2, 4 and 12 h after taking the vitamins, using HPLC as described by te Poele-Pothoff et al (1995).…”

Section: Analyticsmentioning

confidence: 99%

Pharmacokinetic study on the utilisation of 5‐methyltetrahydrofolate and folic acid in patients with coronary artery disease

Willems

Boers²,

Blom³

et al. 2004

British J Pharmacology

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1 Methylenetetrahydrofolate reductase (MTHFR) is a regulating enzyme in folate-dependant homocysteine remethylation, because it catalyses the reduction of 5,10 methylenetetrahydrofolate to 5-methyltetrahydrofolate (5-MTHF). 2 Subjects homozygous for the 677C-T mutation in the MTHFR enzyme suffer from an increased cardiovascular risk. It can be speculated that the direct administration of 5-MTHF instead of folic acid can facilitate the remethylation of homocysteine in methionine. 5 All pharmacokinetic parameters demonstrate that the bioavailability of 5-MTHF is higher compared to folic acid. The peak concentration of both isomers following the administration of 6[R,S] 5-MTHF is almost seven times higher compared to folic acid, irrespective of the patient's genotype. However, at 1 week after the administration of a single dosage 6[R,S] 5-MTHF, we detected 6[R] 5-MTHF following the administration of folic acid, indicating storage of this isomer in the body. 6 Our results demonstrate that oral 5-MTHF has a different pharmacokinetic profile with a higher bioavailability compared to folic acid, irrespective of the patient's genotype. Detrimental effects of the storage of high levels of the non-natural isomer 6[R] 5-MTHF cannot be excluded.

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“…Cases and controls were subjected to an oral methionine loading test as described by Boers et al 9 Total homocysteine was measured in plasma using high-performance liquid chromatography (HPLC), with reverse phase separation and fluorescence detection, as described by Te Poele-Pothoff et al 22 All homocysteine measurements were conducted at the University Medical Center Nijmegen, The Netherlands. Fasting and post-load plasma homocysteine levels were obtained from 555 and 525 individuals, respectively.…”

Section: Biochemical Parametersmentioning

confidence: 99%

A 31 bp VNTR in the cystathionine β-synthase (CBS) gene is associated with reduced CBS activity and elevated post-load homocysteine levels

Lievers¹,

Kluijtmans²,

Heil³

et al. 2001

Eur J Hum Genet

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Molecular defects in genes encoding enzymes involved in homocysteine metabolism may account for mild hyperhomocysteinaemia, an independent and graded risk factor for cardiovascular disease (CVD). Although heterozygosity for cystathionine b-synthase (CBS) deficiency has been excluded as a major genetic cause of mild hyperhomocysteinaemia in vascular disease, mutations in (non-)coding DNA sequences may lead to a mildly decreased CBS expression and, consequently, to elevated plasma homocysteine levels. We assessed the association between a 31 bp VNTR, that spans the exon 13-intron 13 boundary of the CBS gene, and fasting, post-methionine load and increase upon methionine load plasma homocysteine levels in 190 patients with arterial occlusive disease, and in 381 controls. The 31 bp VNTR consists of 16, 17, 18, 19 or 21 repeat units and shows a significant increase in plasma homocysteine concentrations with an increasing number of repeat elements, in particular after methionine loading. In 26 vascular disease patients the relationship between this 31 bp VNTR and CBS enzyme activity in cultured fibroblasts was studied. The CBS enzyme activity decreased with increasing number of repeat units of the 31 bp VNTR. RT ± PCR experiments showed evidence of alternative splicing at the exon 13-intron 13 splice junction site. The 31 bp VNTR in the CBS gene is associated with post-methionine load hyperhomocysteinaemia that may predispose individuals to an increased risk of cardiovascular diseases.

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Three Different Methods for the Determination of Total Homocysteine in Plasma

Cited by 138 publications

References 5 publications

Vitamin B12 Deficiency Stimulates Osteoclastogenesis via Increased Homocysteine and Methylmalonic Acid

Vitamin B12 Deficiency Stimulates Osteoclastogenesis via Increased Homocysteine and Methylmalonic Acid

Pharmacokinetic study on the utilisation of 5‐methyltetrahydrofolate and folic acid in patients with coronary artery disease

A 31 bp VNTR in the cystathionine β-synthase (CBS) gene is associated with reduced CBS activity and elevated post-load homocysteine levels

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