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PubMed2003

Homocysteine-lowering treatment with folic acid plus vitamin B6 lowers urinary albumin excretion but not plasma markers of endothelial function or C-reactive protein: further analysis of secondary end-points of a randomized clinical trial.

BACKGROUND: Hyperhomocysteinaemia is an independent risk factor for atherosclerosis and is thought to induce its effects through causing endothelial dysfunction. We studied the effect of homocysteine-lowering treatment with folic acid plus vitamin B6 on urinary and plasma markers of endothelial function, and on plasma C-reactive protein, a marker of chronic inflammation. DESIGN: We performed a placebo-controlled 2-year trial among 158 healthy siblings of patients with premature atherosclerotic disease to determine the effect of daily folic acid (5 mg) plus vitamin B6 (250 mg) treatment as compared with placebo medication (n = 80) on markers of endothelial function (urinary albumin-to-creatinine ratio and plasma concentrations of soluble E-selectin, soluble vascular cell adhesion molecule-1, von Willebrand factor, tissue-type plasminogen activator and plasminogen activator inhibitor-1) and inflammation (C-reactive protein). Outcome variables were assessed at baseline and after 1 and 2 years of treatment. RESULTS: Fasting homocysteine concentrations ( micromol L-1) at baseline and after treatment were 14.7 +/- 8.2 and 7.4 +/- 1.9 in the vitamin and 14.7 +/- 8.8 and 12.0 +/- 5.4 for the placebo group, respectively. Vitamin treatment was associated with a decreased urinary albumin-to-creatinine ratio at follow up [regression coefficient (beta) -0.20 mg mmol-1 (CI: -0.43-0.03); P = 0.09]. After adjustment for age, sex, baseline concentrations of postmethionine total homocysteine plus the baseline albumin-to-creatinine ratio, the beta was -0.23 mg mmol-1 (CI: -0.43 to -0.02; P = 0.03), which amounts to a decrease of approximately 20%. There was no apparent effect of vitamin treatment on the other markers. CONCLUSIONS: Homocysteine-lowering vitamin treatment in healthy siblings of patients with premature atherosclerotic disease is associated with a decreased urinary albumin-to-creatinine ratio, but not with other markers of endothelial dysfunction, or in plasma C-reactive protein. The clinical significance of these findings remains to be determined.

Adult↗
PubMed2003

Folic acid, polymorphism of methyl-group metabolism genes, and DNA methylation in relation to GI carcinogenesis.

DNA methylation is the main epigenetic modification after replication in humans. DNA (cytosine-5)-methyltransferase (DNMT) catalyzes the transfer of a methyl group from S-adenosyl-L-methionine (SAM) to C5 of cytosine within CpG dinucleotide sequences in the genomic DNA of higher eukaryotes. There is considerable evidence that aberrant DNA methylation plays an integral role in carcinogenesis. Folic acid or folate is crucial for normal DNA synthesis and can regulate DNA methylation, and through this, it affects cellular SAM levels. Folate deficiency results in DNA hypomethylation. Epidemiological studies have indicated that folic acid protects against gastrointestinal (GI) cancers. Methylene-tetrahydrofolate reductase (MTHFR) and methionine synthase (MS) are the enzymes involved in folate metabolism and are thought to influence DNA methylation. MTHFR is highly polymorphic, and the variant genotypes result in decreased MTHFR enzyme activity and lower plasma folate level. Two common MTHFR polymorphisms, 677CT (or 677TT) and A1298C, and an MS polymorphism, A-->G at 2756, have been identified. Most studies support an inverse association between folate status and the rate of colorectal adenomas and carcinomas. During human GI carcinogenesis, MTHFR is highly polymorphic, and the variant genotypes result in decreased MTHFR enzyme activity and lower plasma folate level, as well as aberrant methylation.

DNA Methylation↗
PubMed1999

Combination of low-dose folic acid and pyridoxine for treatment of hyperhomocysteinaemia in patients with premature arterial disease and their relatives.

Hyperhomocysteinaemia is an independent risk factor for atherosclerotic disease and venous thrombosis. The optimal homocysteine-lowering vitamin dose and target total homocysteine (tHcy) concentration are currently unknown. We prospectively studied the homocysteine-lowering effect after 8 weeks low-dose combination of folic acid (0.5 mg) and pyridoxine (100 mg) in 49 hyperhomocysteinaemic persons (33 patients with documented premature arterial disease and 16 of their first-degree relatives). Hyperhomocysteinaemia was in both sexes defined as fasting tHcy concentration > 12 micromol/l and/or post-methionine load tHcy concentration > 38 micromol/l. Low-dose vitamin therapy significantly reduced fasting tHcy concentration (median 13.9 to 9.3 micromol/l, reduction 32% (95% CI: 27-37%)) and post-load tHcy concentration (median 55.2 to 36.5 micromol/l, reduction 30% (95% CI: 25-35%)). Fasting tHcy reduction was similar in women and men, as well as in patients and relatives. Post-load tHcy reduction was significantly less in men compared to women (P = 0.04) and in relatives compared to patients (P = 0.03). Although low-dose combination of folic acid and pyridoxine results in a substantial reduction of tHcy concentrations (30-32%) in subjects with hyperhomocysteinaemia, the normalisation percentage to predefined criteria was less impressive (49%).

Adult↗
PubMed1997

Folic acid the essential supplement to brain heart infusion broth for cultivation and cloning of Leishmania donovani promastigotes.

Multiplication of virulent and avirulent Leishmania donovani promastigotes was inhibited by brain heart infusion broth (BHI) (3.7%) supplemented with haemolysed or whole blood (2.5-10%) or heat-inactivated foetal bovine serum (HIFBS) (10-20%). Peptone, glutamine, tryptophan, purine bases, ribonucleosides, deoxyribonucleosides, B-vitamins and vitamin C were evaluated for the reversal of this growth inhibition. Supplementation of BHI with folic acid further supplemented with haemolysed rabbit blood or HIFBS and haemin supported propagation in serial subpassages of 2 primary isolates and 3 other virulent strains of L. donovani and 1 strain of L. major. Folic acid supplemented BHI with 3% rabbit blood in solid phase with 0.7% agar also supported the colony formation of L. donovani. This manuscript documents the development of high efficiency media for the cultivation of L. donovani promastigotes in liquid phase and as colonies on agar plates using BHI as a basal medium.

Animals↗
PubMed1991

Use of folic acid for prevention of spina bifida and other neural tube defects--1983-1991.

Neural tube defects--including spina bifida, anencephaly, and encephalocele--are common, serious birth defects that are important causes of infant mortality and disability. Women in the United States who have had a pregnancy resulting in an infant or fetus with a neural tube defect have a 2%-3% risk for having another pregnancy resulting in an infant or fetus with a neural tube defect (i.e., a recurrence) The British Medical Research Council (MRC) Vitamin Study Group recently reported the results of a randomized prevention trial that indicated that daily oral supplementation with folic acid before conception and during early pregnancy substantially reduces the recurrence of neural tube defects. This report summarizes the findings of that study and provides recommendations for supplementation with folic acid to prevent the recurrence of neural tube defects.

Anencephaly↗
PubMed2001

Homocysteine, folic acid, B vitamins and cardiovascular risk.

Although there is considerable epidemiological evidence for a relationship between plasma homocysteine and cardiovascular disease, the role of homocysteine as a causal cardiovascular risk factor remains controversial. While results from high risk population based prospective studies generally support an association of elevated homocysteine levels with increased risk of cardiovascular disease, results from low risk population based prospective studies, however, tend to indicate a weaker association, or none at all. There is not yet any proof of a cardiovascular benefit mediated by folic acid plus B vitamins supplementation; nevertheless, some recent reports focusing on intermediate endpoints support the hypothesis of a benefit. Several interventional trials are underway and the answer of whether there is a cardiovascular benefit through folic acid plus B vitamins supplementation in different populations will be available in the years to come.

Animals↗
PubMed2003

Phase II study of pemetrexed disodium (Alimta) administered with oral folic acid in patients with advanced gastric cancer.

BACKGROUND: The aim of this study was to assess the activity of pemetrexed in patients with advanced gastric cancer. PATIENTS AND METHODS: Thirty-eight eligible patients (median age 60 years) received pemetrexed 500 mg/m(2) every 3 weeks. Since toxicity was considerable in the first six patients, the protocol was amended to supplement subsequent patients with oral folic acid (5 mg/day on days -2 to +2 of every cycle). RESULTS: Among 36 stage IV patients evaluable for efficacy (six non-supplemented\30 supplemented), there were two complete and six partial responses. The response rate was 21% (95% confidence interval 8% to 32%) according to intention-to-treat analysis. All responding patients were in the supplemented group. The median duration of response was 4.6 months and the median survival was 7.8 months. Five of six non-supplemented patients (83%) developed grade 3/4 neutropenia; two (33%) unsupplemented patients discontinued; two (33%) patients died due to toxicity. In the supplemented group, 12 of 32 patients (37%) had grade 3/4 neutropenia. None of the supplemented patients discontinued treatment due to hematological toxicity. Severe non-hematological toxicities were infrequent. CONCLUSIONS: The activity of pemetrexed is promising in light of the tumor burden in these patients (all patients were stage IV and 39% had three or more organs involved). Toxicities were remarkably decreased with folic acid supplementation. Combination studies are warranted.

Adenocarcinoma↗
PubMed2005

[The plasma homocysteine, folic acid and vitamin B12 levels in young people with high risk for cardiovascular disease and its relation to metylentetrahydrofolate reductase (MTHFR) gene polymorphism].

INTRODUCTION: Hyperhomocysteinemia is an independent risk factor for cardiovascular morbidity. AIM: The study was designed to evaluate the total homocysteine level and MTHFR C677T polymorphism frequency of 122, healthy, young adults who had increased risk for cardiovascular disease. The serum levels of folic acid and vitamin B12 were also measured. METHODS: Immunoassay, PCR-RFLP methods were used. The statistical analysis was performed by SPSS program. RESULTS: The frequency of the gene-polymorphism was not different significantly in the study group compared to a Hungarian neonatal sample: although in the increased risk group the frequency of homozygous 677TT polymorphism was higher (14.8%), and heterozygosity was smaller (41%). There was no association between MTHFR gene polymorphism and homocysteine levels. A significant negative correlation was found between the folic acid and homocysteine, and between the vitamin B12 and homocysteine levels correlating with the literature. The mean serum total homocysteine level of the group without vitamin supplementation (n: 86) was 9.8 +/- 3.3 micromol/l, while in the other group with vitamin uptake (n: 36) this level was 7.5 +/- 3.0 micromol/l. There was a significant difference between the homocysteine levels of men and women. CONCLUSION: The results of the study correlate with the literature. It would be useful to call the attention of the Hungarian population to the importance of vitamin supply.

Adult↗