Effect of genetic polymorphisms involved in folate metabolism on the concentration of serum folate and plasma total homocysteine (p-tHcy) in healthy subjects after short-term folic acid supplementation: a randomized, double blind, crossover study.

Data on the effect of combined genetic polymorphisms, involved in folate metabolism, on the concentration of serum folate after folic acid supplementation are scarce. Therefore, we investigated the impact of seven gene polymorphisms on the concentration of serum folate and p-tHcy in healthy subjects after short-term folic acid supplementation. In a randomized, double blind, crossover study, apparently healthy subjects were given either 0.8 mg folic acid per day (n = 46) or placebo (n = 45) for 14 days. The washout period was 14 days. Fasting blood samples were collected on day 1, 15, 30 and 45. Data on subjects on folic acid supplementation (n = 91) and on placebo (n = 45) were used for the statistical analysis. The concentration of serum folate increased higher in subjects with higher age (53.5 ± 7.0 years) than in subjects with lower age (24.3 ± 3.2 years) after folic acid supplementation (p = 0.006). The baseline concentration of serum folate in subjects with polymorphism combination, reduced folate carrier protein, RFC1-80 GA and methylenetetrahydrofolate reductase, MTHFR677 CT+TT, was lower than RFC1-80 AA and MTHFR677 CT+TT (p = 0.002). After folic acid supplementation, a higher increase in the concentration of serum folate was detected in subjects with polymorphism combination RFC1-80 GA and MTHFR677 CC than RFC1-80 GG and MTHFR CT+TT combination (p < 0.0001). The baseline concentration of plasma total homocysteine (p-tHcy) was altered by combined polymorphisms in genes associated with folate metabolism. After folic acid supplementation, in subjects with combined polymorphisms in methylenetetrahydrofolate dehydrogenase, MTHFD1-1958 and MTHFR-677 genes, the concentration of p-tHcy was changed (p = 0.002). The combination of RFC1-80 and MTHFR-677 polymorphisms had a profound affect on the concentration of serum folate in healthy subjects before and after folic acid supplementation.

Effects of polymorphisms in endothelial nitric oxide synthase and folate metabolizing genes on the concentration of serum nitrate, folate, and plasma total homocysteine after folic acid supplementation: a double-blind crossover study.

OBJECTIVES: A number of studies have explored the effects of dietary nitrate on human health. Nitrate in the blood can be recycled to nitric oxide, which is an essential mediator involved in many important biochemical mechanisms. Nitric oxide is also formed in the body from l-arginine by nitric oxide synthase. The aim of this study was to investigate whether genetic polymorphisms in endothelial nitric oxide synthase (eNOS) and genes involved in folate metabolism affect the concentration of serum nitrate, serum folate, and plasma total homocysteine in healthy individuals after folic acid supplementation. METHODS: In a randomized double-blind, crossover study, participants were given either folic acid 800 µg/d (n = 52) or placebo (n = 51) for 2 wk. Wash-out period was 2 wk. Fasting blood samples were collected, DNA was extracted by salting-out method and the polymorphisms in eNOS synthase and folate genes were genotyped by polymerase chain reaction methods. Measurement of serum nitrate and plasma total homocysteine (p-tHcy) concentration was done by high-performance liquid chromatography. RESULTS: The concentration of serum nitrate did not change in individuals after folic acid supplements (trial 1); however, the concentration of serum nitrate increased in the same individuals after placebo (P = 0.01) (trial 2). The individuals with three polymorphisms in eNOS gene had increased concentration of serum folate and decreased concentration of p-tHcy after folic acid supplementation. Among the seven polymorphisms tested in folate metabolizing genes, serum nitrate concentration was significantly decreased only in DHFR del 19 gene variant. A significant difference in the concentration of serum nitrate was detected among individuals with MTHFR C > T677 polymorphisms. CONCLUSIONS: Polymorphisms in eNOS and folate genes affect the concentration of serum folate and p-tHcy but do not have any effect on the concentration of NO3 in healthy individuals after folic acid supplementation.

A simple high-performance liquid chromatography (HPLC) method for the measurement of pyridoxal-5-phosphate and 4-pyridoxic acid in human plasma.

BACKGROUND: Low concentration of plasma pyridoxal-5-phosphate (PLP) is associated with hyperhomocysteinemia and inflammation. Most methods for the measurement of plasma PLP require large specimen volume and involve the use of toxic reagents. METHODS: We have developed a HPLC method for the measurement of PLP and 4-pyridoxic acid (4-PA) in plasma, which requires small specimen volume. The samples are prepared without adding any toxic reagents. Furthermore, we have examined whether intake of vitamin B6 affects the concentration of plasma PLP and 4-PA. RESULTS: The coefficient of variation of the method was 6% and the recovery of the added vitamin in plasma was about 100%. The concentrations of plasma PLP and 4-PA in 168 healthy subjects were 40.6 (8.4-165.0) nmol/L, median and (range) and 17.5 (3.7-114.79) nmol/L, median and (range) respectively. In the multiple regression analyses, the concentration of plasma PLP was associated with the concentration of plasma 4-PA (p<0.0001), BMI, (p=0.02) and sex, (p=0.0008). The concentration of plasma 4-PA was associated with plasma PLP (p<0.0001), serum folate (p=0.004), smoking (p=0.03) and vitamin B6 intake (p=0.01). CONCLUSION: The present method is suitable for large clinical studies for the measurement of plasma PLP and 4-PA. Our findings demonstrate that plasma 4-PA, BMI and sex are the major determinants of plasma PLP in healthy individuals.

Early biochemical and hematological response to intramuscular cyanocobalamin therapy in vitamin B(12)-deficient patients.

BACKGROUND: Data on early biochemical and hematological responses to cobalamin therapy in vitamin B12-deficient patients are scarce. Therefore, we investigated whether cobalamin injections would include prompt biochemical and hematological responses in vitamin B12-deficient patients. SUBJECTS AND METHODS: Seven female patients (mean age: 69.4 years, range: 61-78) with a mean serum cobalamin level of 104 ± 38 pmol/l mean ± SD and 7 male patients (mean age: 67.0 years, range: 53-78) with a mean serum cobalamin level of 84 ± 40 (±SD) participated in the study. They were administered 1 mg i.m. cyanocobalamin per week for 3 weeks. Blood samples were collected before and 1, 3, 7, 14 and 21 days after cobalamin injection. The concentrations of plasma aminothiols and serum methylmalonic acid (MMA) were measured with high-performance liquid chromatography and gas chromatography/mass spectrometry, respectively, and hematological parameters were determined with a hematological analyzer. RESULTS: Already 1 day after intramuscular Cobalamin injections, the concentrations of serum vitamin B12 and plasma total cysteine were significantly increased while the concentrations of serum folate, plasma total homocysteine and serum MMA were decreased. Mean cell volume was also significantly decreased first after 14 days of therapy. CONCLUSION: Intramuscular cobalamin administration causes swift and significant changes in plasma aminothiols, whereas the first change in hematological parameters was detected only after 14 days.

Higher leukocyte subpopulation counts in healthy smoker industrial workers than in nonsmoker industrial workers: possible health consequences.

OBJECTIVES: Cigarette smoke contains free radicals, which cause injury to endothelial cells and oxidize bioactive components in the blood. Neutrophils, a subpopulation of leukocytes, contain the enzyme myeloperoxidase that mediates production of hypochlorous acid during oxidative stress. In this study, we investigated whether smoker industrial workers had significantly higher neutrophil counts than nonsmoker industrial workers. DESIGN AND METHODS: We collected blood samples from 183 apparently healthy male and 30 female industrial workers. We obtained blood cell counts, measured the concentration of plasma aminothiols and determined the concentration of serum and erythrocyte folate and serum vitamin B12 in the samples. RESULTS: Smoker industrial workers had significantly higher neutrophil, lymphocyte, monocyte, eosinophil and basophil counts than nonsmoker industrial workers (p < 0.0001, p < 0.0001, p < 0.0001, p < 0.0001 and p = 0.01, respectively). Mean corpuscular volume and mean corpuscular hemoglobin in smoker industrial workers were higher than in nonsmoker industrial workers (p = 0.001 and p = 0.03). CONCLUSION: Our study demonstrates that smoker industrial workers have higher neutrophil counts than nonsmoker industrial workers. Therefore, our observations suggest that smokers may become more easily prone to chronic inflammation than nonsmokers. About 84% of the study participants were male subjects; therefore, our findings may be more representative for men than women.

Plasma homocysteine, folate and vitamin B(12) compared between rural Gambian and UK adults.

The disease risk indicator plasma total homocysteine (tHcy) is influenced by genetic and environmental factors, including folate and vitamin B(12) status. Little is known about the determinants of tHcy in rural West Africa. We explored the hypothesis that tHcy in rural Gambian adults might vary between the sexes and physiological groups, and/or with folate and vitamin B(12) status. Comparisons were made with a British national survey. Non-pregnant Gambian women (n 158) had tHcy concentrations (geometric mean 9.0 micromol/l) similar to those of non-pregnant UK women (n 449; 9.4 micromol/l), whereas pregnant Gambian women (n 12) had significantly lower values (6.2 micromol/l). Gambian men (n 22) had significantly higher values (14.7 micromol/l) than British men (n 354; 10.8 micromol/l). Gambian lactating women and British men and women exhibited significant inverse relationships between log(e)(tHcy) and folate status; however, only the British subjects exhibited significant inverse relationships between loge(tHcy) and vitamin B(12) status. In the British sample, and in Gambian lactating women, folate and vitamin B(12) status variations together accounted for 20-25 % of the variation in log(e)(tHcy). Within the UK, black-skinned adults had folate and tHcy levels similar to those of their white-skinned counterparts, but significantly higher vitamin B(12) values. We conclude that, whereas folate and vitamin B(12) status are similar between British and rural Gambian populations, tHcy is higher in Gambian men and lower in pregnant Gambian women, and that serum vitamin B(12) values appear to be higher in black-skinned than white-skinned British subjects. Possible reasons are discussed.

Maternal and fetal variants of genetic thrombophilias and the risk of preeclampsia.

BACKGROUND: A woman's thrombophilic genes may increase her risk of preeclampsia in pregnancy. Vascular conditions of the placenta related to thrombophilic genes of the fetus could also be relevant for preeclampsia. The case-parent triad study design provides separate estimation of maternal and fetal genes. METHODS: We recruited 92 mother-father-child triads of preeclamptic pregnancies from a birth clinic in Stavanger, Norway. All parents were of Norwegian origin. Maternal, paternal, and fetal DNA were genotyped for the methylenetetrahydrofolate reductase (MTHFR) C677T and Factor V Leiden (FVL) G1691A SNPs. Estimation of the relative risk (RR) associated with fetal and maternal genetic variants was performed by log-linear models. RESULTS: There was no indication of an effect of the child's FVL alleles on preeclampsia risk. For case babies with 2 copies of the variant allele, the association with the MTHFR variant was inconclusive (RR = 1.6; 95% confidence interval [CI] = 0.6-4.3). Case mothers who were homozygous for the MTHFR variant had a relative risk of 2.0 (CI = 1.0-4.1) assuming a recessive gene effect. A 2.5-fold risk (CI = 1.1-5.7) of preeclampsia was estimated when the mother carried one copy of the FVL. Among mothers homozygous for the MTHFR variant, the relative risk of the FVL variant was 4.6-fold (CI = 1.0-21). CONCLUSIONS: We found little evidence of an effect of the child's MTHFR or FVL alleles on the risk of preeclampsia. Our estimates of effects of maternal MTHFR and FVL alleles were consistent with estimates from case-control studies. The case-parent triad design may be a useful tool for studies of pregnancy complications such as preeclampsia.