Folate depletion and increased glutamation in juvenile idiopathic arthritis patients treated with methotrexate.

OBJECTIVE: Folates exist as a fluctuating pool of polyglutamated metabolites that may serve as a clinical marker of methotrexate (MTX) activity. This study was undertaken to evaluate circulating folate content and folate polyglutamate distribution in juvenile idiopathic arthritis (JIA) patients and in a cell culture model based on MTX exposure and folate supply. METHODS: Blood, plasma, and red blood cell (RBC) measurements of MTX and folates were obtained from previously published data sets and an additional analysis of JIA patients receiving MTX (n = 98) and those not receiving MTX (n = 78). Erythroblastoid cells maintained in culture were exposed to MTX and grown under varying levels of folic acid supplementation. Samples were analyzed for cellular folate and MTX content. RESULTS: Circulating folate levels were lower in JIA patients receiving MTX, with reduced levels of blood, plasma, and RBC 5-methyl-tetrahydrofolate (5mTHF) (P < 0.0001). Average polyglutamate chain length (Gluavg ) of RBC 5mTHF was elevated in JIA patients receiving MTX (median ± interquartile range 5.63 ± 0.15 versus 5.54 ± 0.11 in those not receiving MTX; P < 0.001) and correlated with both RBC MTX accumulation (P = 0.02) and reduced plasma 5mTHF levels (P = 0.008). MTX exposure and folate deprivation in erythroblastoid cells resulted in a depletion of bioactive folate species that was associated with a shift to higher Gluavg values for several species, most notably tetrahydrofolate (THF) and 5,10-methylene-tetrahydrofolate (CH2 THF). Increased Gluavg resulted from the depletion of short-chain and the accumulation of long-chain glutamate species. CONCLUSION: Our findings indicate that folate content and polyglutamate distribution are responsive markers of MTX activity and folate supply in vivo and in vitro, and may provide novel clinical markers of pharmacologic activity of MTX.

Red blood cell folate concentrations and polyglutamate distribution in juvenile arthritis: predictors of folate variability.

OBJECTIVE: Methotrexate (MTX) has several enzymatic targets in the folate pathway. To better understand the variability in response to MTX, we characterized the interindividual variability of intracellular folate pools in children with juvenile arthritis (JA) and determined clinical and genetic contributors to this variability. STUDY DESIGN: This exploratory single-center cross-sectional study evaluated 93 patients with JA not currently receiving MTX. Whole blood, plasma, and erythrocyte folate concentrations were determined after deconjugation and analyzed through reversed-phase separation and stable isotope dilution tandem mass spectrometry. Folate polyglutamates were measured in red blood cell lysates using an ion-pair reversed phase chromatography tandem mass spectrometry method. RESULTS: Intracellular concentrations of 5-methyl-tetrahydrofolate (5-CH3-THF) and 5,10-methenyl-tetrahydrofolate varied approximately 20-fold and 80-fold, respectively. The polyglutamated forms of 5-CH3-THF as a percentage of total 5-CH3-THF (5-CH3-THFGlun) were also measured. Hierarchical clustering of 5-CH3-THFGlun revealed two groups, each with two distinct clusters. There was an inverse relationship between 5-CH3-THFGlun chain length and plasma 5-CH3-THF concentrations. A subgroup of patients with a historical intolerance to MTX had significantly lower cellular folate concentrations (P<0.0001). In univariate analyses, clinical variables including sex, age, and folate supplementation in addition to variations in MTHFR, MTR, and SLC25A32 were associated with differential intracellular folate redox concentrations. Multivariate analysis further supported the association of single nucleotide polymorphisms in SLC25A32, MTHFR, and MTR with variability in intracellular 5-CH3-THF and 5,10-methenyl-tetrahydrofolate concentrations, respectively. CONCLUSION: Measurement of intracellular folate isoforms may contribute toward a better understanding of individual MTX effects in JA. Clinical variables in addition to genotypic differences beyond MTHFR may additionally explain differential intracellular folate concentrations and variable responses to MTX.

Concentración de vitamina B12 en suero en población puberal de la Comunidad de Madrid / Serum vitamin B12 levels in an adolescent population in Madrid

Introducción: Disponer de datos sobre la concentración de vitamina B12 en suero en niños es imprescindible para establecer unos percentiles que permitan realizar comparaciones entre regiones o países y poder plantear la suplementación de la dieta con vitaminas del grupo B como prevención secundaria frente a las enfermedades cardiovasculares. Material y métodos: Se realizó un estudio epidemiológico descriptivo de tipo transversal, con el fin de estimar las concentraciones séricas de vitamina B12 en la población escolar entre 13 y 15 años en la Comunidad de Madrid. Se realizó una determinación de folato y vitamina B12 en las muestras de sangre obtenidas en ayunas. Se determinó el genotipo C677T de la enzima metilentetrahidrofolato reductasa por reacción en cadena de la polimerasa (PCR). Resultados: Las concentraciones medias de vitamina B12 obtenidos en nuestro estudio fueron de 503 pmol/l; intervalo de confianza del 95 % (IC 95 %) (478-528 pmol/l). La mediana fue de 471 pmol/l; rango intercuartílico (337-632 pmol/l). No se encontraron diferencias estadísticamente significativas por edad o genotipo C677T. La concentración sérica de vitamina B12 fue significativamente mayor en las mujeres. La prevalencia de valores deficitarios de vitamina B12 (< 224 pmol/l) fue del 6 % en varones y del 4 % en mujeres. Conclusiones: Se presentan valores de referencia de las concentraciones de vitamina B12 sérica en población adolescente. La prevalencia de déficit de vitamina B12 es mayor en varones (AU)

Introduction: Serum vitamin B12 concentration levels in children are essential to establish values in order to compare different regions or countries, and for considering e the possibility of supplementing diets with group B vitamins as a secondary prevention against cardiovascular diseases. Material and methods: A cross-sectional epidemiological study was carried out to asses serum vitamin B12 levels in school children, 13-15 years of age, in Madrid. Folate and vitamin B12 vitamin determinations were performed on fasting blood samples. Genotype C677T of methylentetrahydrofolate reductase (MTHFR) enzyme was determined by PCR. Results: The mean vitamin B12 level obtained in our study was 503 pmol/l; CI 95 % CI (478-528 pmol/l). The median was 471 pmol/l; interquartile range (IR) (337-632 pmol/l). No statistically significant differences were found by age or C677T genotype for MTHFR. Serum vitamin B12 concentrations were significantly higher in females. Prevalence of vitamin B12 deficiency (< 224 pmol/l) was 6 % in males and 4 % in females. Conclusions: Reference values for serum vitamin B12 concentrations in an adolescent population are presented. Prevalence of vitamin B12 deficiencies is higher in males (AU)

Contribution of methylenetetrahydrofolate reductase (MTHFR) polymorphisms to negative symptoms in schizophrenia.

BACKGROUND: Folate deficiency may contribute to negative symptoms in schizophrenia, but the underlying mechanism remains uncertain. We examined whether the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C functional polymorphisms contribute to negative symptoms. METHODS: Outpatients with schizophrenia (n = 200) were evaluated with the Positive and Negative Syndrome Scale (PANSS). Subjects also provided a blood sample for MTHFR genotype and serum chemistries. Comparisons of PANSS symptoms, folate, and homocysteine status were conducted based on genotype. RESULTS: The 677T allele load was associated with negative symptom severity. Contrary to our expectations, the T allele was also found to be protective against positive symptoms. The A1298C polymorphism did not contribute to negative symptoms, and only weakly to positive symptoms. The specific effects of the C677T polymorphism were confirmed with haplotype analysis. Among patients homozygous for the 667T allele, serum folate levels correlated with negative symptom severity. CONCLUSIONS: Increased MTHFR 677T allele load confers risk for negative symptoms in schizophrenia, while reducing severity of positive symptoms. Further, the biochemical interaction of low serum folate with 677T-variant MTHFR may induce downstream effects salient to the expression of negative symptoms.

2756GG genotype of methionine synthase reductase gene is more prevalent in rheumatoid arthritis patients treated with methotrexate and is associated with methotrexate-induced nodulosis.

OBJECTIVE: To investigate the distribution of the A2756G polymorphism of the methionine synthase reductase (MTR) gene in patients with rheumatoid arthritis (RA) treated with methotrexate (MTX) compared with a healthy control group; and to examine the relationships among the A2756G polymorphism, plasma total homocysteine (tHcy), serum folate and vitamin B12 levels, disease activity, and MTX toxicity in patients with RA. METHODS: A cross-sectional study was performed on 86 MTX-treated RA patients, consisting of a clinical interview and physical examination to determine disease activity and MTX-related adverse reactions. Genotype analysis of the MTR gene was performed. Fasting plasma tHcy, serum folate, and vitamin B12 levels were measured. Allele and genotype distributions were compared to a healthy control group. RESULTS: The frequency of the 2756GG genotype (16.3%) in the RA study group was higher than that expected in the general population (3.6%; p < 0.000001). This genotype was associated with MTX-induced accelerated rheumatoid nodulosis (MIARN). No association of disease activity variables or plasma homocysteine with MTR A2756G polymorphisms was observed. The MTR 2756GG genotype, low plasma vitamin B12 levels, and the presence of rheumatoid nodules predicted MIARN. No association of nodulosis with any other indicator of disease activity or medical treatment was found. CONCLUSION: In our population of MTX-treated RA patients the 2756GG genotype of the MTR gene was more common than expected and was associated with MIARN.

Pharmacogenomic and metabolic biomarkers in the folate pathway and their association with methotrexate effects during dosage escalation in rheumatoid arthritis.

OBJECTIVE: To evaluate the contribution of metabolites (methotrexate [MTX] and folate polyglutamate [PG] levels) and pharmacogenetic biomarkers in the folate pathway to the effects of MTX in patients with rheumatoid arthritis not previously treated with this antifolate. METHODS: Forty-eight MTX-naive adult patients were enrolled in a prospective longitudinal study. MTX therapy was initiated at 7.5 mg/week and was increased every 4-6 weeks until a therapeutic response was achieved. Response was assessed using the Disease Activity Score in 28 joints (DAS28). Red blood cell (RBC) MTX and folate PG levels were measured with 9 common polymorphisms in the folate pathway. Statistical analyses consisted of generalized linear models and multivariate regressions. RESULTS: After 6 months of therapy, the median weekly MTX dosage was 17.5 mg and the median decrease in the DAS28 was 2.0. There was a large interpatient variability in RBC MTXPG levels (median 35 nmoles/liter [interquartile range 28-51] at month 6). Patients with a lesser decrease in the DAS28 (fewer improvements) had lower RBC MTXPG levels (P < 0.05) despite the higher MTX dose administered (P < 0.05). RBC folate PG levels decreased significantly during treatment, and a lesser decrease in RBC folate PGs was associated with a lesser decrease in the DAS28 (P < 0.05). Primary side effects were gastrointestinal and neurologic in nature. Risk genotypes associated with toxicity were in gamma-glutamyl hydrolase (-401CC), 5-aminoimidazole-4-carboxamide ribonucleotide transformylase (347GG), methylenetetrahydrofolate reductase (1298AC/CC), methionine synthase (2756AA), and methionine synthase reductase (66GG). CONCLUSION: RBC MTXPG levels are a useful means by which to monitor therapy. The genetic associations presented generate hypotheses, and confirmation in independent cohorts is warranted.

Do serum and red blood cell folate levels indicate iron response in hemodialysis patients?

The relationship among iron status, ferritin, and folate levels, and the possible contribution of folate measurement in the prediction of iron response in hemodialysis patients, have not been assessed. In addition to serum ferritin and transferrin saturation (TSAT), serum and red blood cell (RBC) folate levels were evaluated as indices for intravenous iron therapy responsiveness in 60 hemodialysis patients. Patients were classified as iron responders or nonresponders depending on whether they exhibited a rise in hemoglobin above 1 g/dl after administration of 1 g of iron sucrose. An inverse relation between serum ferritin concentration and RBC folate levels was found in iron responders (n=26, r=-0.62, p<0.001) but not in nonresponders (n=34, r=0.07, p=nonsignificant). Only serum and RBC folate levels could predict iron response in patients with ferritin levels above 150 microg/l (n=25), with a sensitivity of 83.3% and a specificity of 94.7%. Our findings suggest that RBC folate concentration is inversely related with ferritin levels in iron-responsive but not in non-responsive hemodialysis patients. Serum and RBC folate concentration seems to predict response to iron administration better than serum ferritin or TSAT in patients with ferritin levels above 150 microg/l; therefore, in these patients, it might be used to guide iron management.

Methylenetetrahydrofolate reductase gene polymorphisms in patients with cerebral hemorrhage.

Elevated plasma total homocysteine (HCY) level is a risk factor for coronary heart disease and ischemic stroke. We investigated relationships between polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, and plasma levels of HCY and folate in patients of Mongolian races who suffered from cerebral ischemia (CI, n = 42) or cerebral hemorrhage (CH, n = 20) and in the 24 age-matched controls. The incidences of both homozygous and heterozygous MTHFR gene mutations in CI (26 and 43%) and in CH (25 and 60%) were significantly higher than those in the controls (8 and 25%). Homozygous MTHFR gene mutation was associated with reduced plasma folate levels, but not with increased plasma HCY levels. Among the subjects with homozygous MTHFR gene mutation, plasma folate levels in CH was significantly lower than those in CI and controls. MTHFR gene mutation in CH was found to be as common as that in CI and was associated with reduced plasma folate levels in the both. In homozygous MTHFR gene mutation, the plasma folate level was profoundly reduced in CH as compared with CI and controls, suggesting that subjects with low plasma folate levels have a predisposition to intracerebral bleeding.

Pharmacogenetic and metabolite measurements are associated with clinical status in patients with rheumatoid arthritis treated with methotrexate: results of a multicentred cross sectional observational study.

OBJECTIVE: To investigate the contribution of red blood cell (RBC) methotrexate polyglutamates (MTX PGs), RBC folate polyglutamates (folate PGs), and a pharmacogenetic index to the clinical status of patients with rheumatoid arthritis treated with MTX. METHODS: 226 adult patients treated with weekly MTX for more than 3 months were enrolled at three sites in a multicentred cross sectional observational study. Clinical status was assessed by the number of joint counts, physician's global assessment of disease activity, and a modified Health Assessment Questionnaire (mHAQ). RBC MTX PG and folate PG metabolite levels were measured by high performance liquid chromatography fluorometry and radioassay, respectively. A composite pharmacogenetic index comprising low penetrance genetic polymorphisms in reduced folate carrier (RFC-1 G80A), AICAR transformylase (ATIC C347G), and thymidylate synthase (TSER*2/*3) was calculated. Statistical analyses were by multivariate linear regression with clinical measures as dependent variables and metabolite levels and the pharmacogenetic index as independent variables after adjustment for other covariates. RESULTS: Multivariate analysis showed that lower RBC MTX PG levels (median 40 nmol/l) and a lower pharmacogenetic index (median 2) were associated with a higher number of joint counts, higher disease activity, and higher mHAQ (p<0.09). Multivariate analysis also established that higher RBC folate PG levels (median 1062 nmol/l) were associated with a higher number of tender and swollen joints after adjustment for RBC MTX PG levels and the pharmacogenetic index (p<0.05). CONCLUSION: Pharmacogenetic and metabolite measurements may be useful in optimising MTX treatment. Prospective studies are warranted to investigate the predictive value of these markers for MTX efficacy.

Contribution of the MTHFR gene to the causal pathway for depression, anxiety and cognitive impairment in later life.

Homocysteine (Hcy) is harmful to neurons and blood vessels, including the cerebral microvasculature. It is possible that such effects contribute to the cascade of events that leads to cognitive decline, dementia, and depression in later life. Hcy is produced during the metabolism of the essential amino-acid methionine, which also involves a methyl group transfer derived from folate and choline metabolism. Its plasma level can be influenced by factors such as age, vitamin deficiency, renal function, and a common mutation in the methylenetetrahydrofolate reductase (MTHFR) gene, where cytosine is replaced by thymidine (C-->T) at nucleotide position 677. Subjects with the TT genotype have higher homocysteine levels and may be particularly prone to experiencing depression as a result of high plasma Hcy and dysfunction of methylation metabolic pathways critical to the synthesis of noradrenaline and serotonin. We designed the present study to investigate whether older women with the TT genotype would have higher depression and lower cognitive scores than women with CT and CC genotypes. A total of 240 community-dwelling women aged 70 years or over volunteered to take part in the study - 29 carried the TT genotype, 113 the CT and 98 the CC genotype. The Beck Depression Inventory (BDI) score for subjects with the TT genotype was statistically similar to the other groups (P = 0.609). Plasma Hcy showed a modest and significant correlation with BDI scores (r = 0.21) that was independent from age, B12 and folate levels. There was no association between beck anxiety inventory (BAI) scores and MTHFR genotype or homocysteine levels. The cognitive assessment of participants included measures of verbal memory, memory for faces, verbal fluency, visuo-spatial abilities and the cognitive section of the Cambridge Examination For Mental Disorders Of The Elderly (CAMCOG)-MTHFR genotype had no clear association with cognitive scores. These results indicate that, in isolation, the MTHFR C677T gene variation does not play an important role in the modulation of mood and cognitive performance in later life.

Cerebrospinal fluid concentrations of folate, biogenic amines and pterins in Rett syndrome: treatment with folinic acid.

BACKGROUND: Previous studies in Rett syndrome (RS) patients suggested various abnormalities in biogenic amines, pterins, and folate values in cerebrospinal fluid (CSF). Our aim was to analyse these metabolites in CSF of 16 RS patients (age range: 2 - 23 years). Biogenic amines, pterins, and 5-methyltetrahydrofolate were measured by HPLC with electrochemical and fluorescence detection. RESULTS: CSF values of 5-methyltetrahydrofolate were decreased in 8 out of 16 RS patients (average: 53.6 nmol/L; range: 19 - 92) when compared with our reference values (average: 74.6 nmol/L; range: 45 - 127). These eight patients had epilepsy, while 4 out of 16 RS patients who did not have epilepsy showed normal CSF 5-methyltetrahydrofolate concentrations. Values of biogenic amines or pterins were decreased in four of the patients with low values of 5-methyltetrahydrofolate. No correlation was observed between CSF values of 5-methyltetrahydrofolate and pterins, biogenic amines, or age. Supplementation with folinic acid was applied in six out of the eight patients with CSF 5-methyltetrahydrofolate deficiency. An improvement was noticed in all cases. CONCLUSIONS: An important percentage of RS patients showed 5-methyltetrahydrofolate concentrations under the reference values. Therefore, analysis of CSF 5-methyltetrahydrofolate seems advisable in RS, especially in patients with epilepsy and those resistant to antiepileptic drugs.

Plasma homocysteine, MTHFR C677T, CBS 844ins68bp, and MTHFD1 G1958A polymorphisms in spontaneous cervical artery dissections.

Mild hyperhomocysteinemia is a probable risk factor for atherosclerotic diseases and stroke. Recently, associations of elevated plasma homocysteine concentrations in the acute phase and of MTHFR 677 TT genotype with spontaneous cervical artery dissections (sCAD) have been reported. The purpose of this study was to test this hypothesis in the currently largest sample of patients with sCAD, taking into account known factors influencing plasma homocysteine levels. Ninety-five patients with past sCAD were compared with 95 age- and sex-matched healthy individuals. Homocysteine, vitamin B6, B12, folate, and polymorphisms of methylenetetrahydrofolate reductase (MTHFR C677T), cystathionine beta-synthase (CBS 844ins68bp) and methylenetetrahydrofolate dehydrogenase/methenyltetrahydrofolate cyclohydrolase/formyltetrahydrofolate synthetase (MTHFD1 G1958A) were assessed and any associations were analysed using multivariate statistics. The occurrence of sCAD was associated with elevated homocysteine levels with an odds ratio of 1.327 per 20 % percentile. Homocysteine levels were influenced by gender, smoking status, occurrence of hypertension, vitamin B12 and folate levels, and by the MTHFR TT genotype. MTHFR, CBS 844ins68bp, and MTHFD1 G1958A genotype were not independently associated with the occurrence of sCAD. These data suggest that elevated homocysteine is associated with the occurrence of sCAD. The MTHFR C677T polymorphism is associated with the homocysteine level.

Bioavailability of polyglutamyl folic acid relative to that of monoglutamyl folic acid in subjects with different genotypes of the glutamate carboxypeptidase II gene.

BACKGROUND: Before dietary folate is absorbed, polyglutamate folates are deconjugated to monoglutamates by folylpoly-gamma-glutamyl carboxypeptidase in the small intestine. The 1561T allele of the glutamate carboxypeptidase II gene (GCPII), which codes for folylpoly-gamma-glutamyl carboxypeptidase, may impair intestinal absorption of dietary folates. OBJECTIVE: Our aim was to study the bioavailability of polyglutamyl folic acid relative to that of monoglutamyl folic acid across GCPII 1561 genotypes. DESIGN: In a randomized study, 180 healthy adults aged 50-75 y received 323 nmol monoglutamyl folic acid/d (n = 59), 262 nmol heptaglutamyl folic acid/d (n = 61), or placebo (n = 60) for 12 wk. Genotypes were assessed after the intervention. The bioavailability of heptaglutamyl folic acid relative to that of monoglutamyl folic acid was calculated by using the changes in serum folate concentration in the treatment groups, after correction for changes in the placebo group and for the administered dose. RESULTS: No subjects with the TT genotype were encountered. At baseline, serum and erythrocyte folate concentrations were higher (P < 0.05) in subjects with the CT genotype [16.3 nmol/L (geometric x; 95% CI: 13.7, 19.3 nmol/L) and 863 nmol/L (735, 1012 nmol/L), respectively; n = 19] than in subjects with the CC genotype [13.7 (13.1, 14.3) and 685 (652, 721) nmol/L, respectively; n = 161]. Baseline homocysteine concentrations were not significantly different between genotypes. The bioavailability of heptaglutamyl folic acid relative to that of monoglutamyl folic acid was not significantly different between subjects with the CC (64%; 52%, 76%) and CT genotypes (70%; 49%, 91%). CONCLUSIONS: The 1561T allele of the GCPII gene does not impair the bioavailability of polyglutamyl folic acid. However, the allele is associated with higher folate status. This association may be explained by yet unidentified factors controlling the expression of the GCPII gene.

Association between serum homocysteine, vitamin B12, folate and Thai coronary artery disease patients.

BACKGROUND: Homocysteine is an intermediate compound formed during metabolism of methionine. The plasma level of homocysteine is dependent on the genetically regulated level of essential enzymes and the intake of folic acid, vitamin B6 (pyridoxine), and vitamin B12 (cobalamine). Elevated serum homocysteine levels are a known risk factor for coronary artery disease (CAD). To establish the magnitude of the CAD that is associated with an increased serum homocysteine level, we compared CAD patients with normal healthy Thai controls. METHOD: In a cross-sectional study design we investigated the association between serum homocysteine, vitamin B12 and folate levels and the coronary heart disease in 178 CAD patients and 178 normal healthy controls by age and sex matching. These comprised 266 men and 90 women, mean age 58 +/- 10 years for normal controls and 60 +/- 10 years for CAD patients. Serum homocysteine, vitamin B12 and folate were measured by ELISA method and electrochemiluminescense method respectively. RESULTS: Paired t-test analysis showed that serum homocysteine concentrations were significantly higher in CAD patients (23.83 +/- 11.29 mumol/L) than in control subjects (19.69 +/- 8.51 mumol/L; p < 0.001). Homocysteine levels were also higher in males than in females. These findings were similar in healthy controls (male: 20.37 +/- 8.5 mumol/L, female: 17.77 +/- 8.2 mumol/L, p < 0.05) and in CAD patients (male: 24.91 +/- 11.8 mumol/L, female: 20.73 +/- 8.9 mumol/L, p < 0.05). Homocysteine above 17 mumol/L occurred more common in CAD patients than in control groups (OR = 1.65, 95% CI = 1.09-2.52, p = 0.0249). Low levels of vitamin B12 and folate did not reaching statistical significance when comparing controls and CAD patients. CONCLUSIONS: Serum homocysteine concentrations were significantly higher in CAD patients than in controls. Serum vitamin B12 and serum folate levels were not statistically significantly different between CAD patients and control groups. The data also demonstrated that the serum homocysteine level is almost always higher in men than in women as previously reported. Although serum vitamin B12 and serum folate levels were not below the upper limit of normal, vitamin B12 and folic acid treatment may reduce serum homocysteine concentrations in CAD patients. We hope that the reversible risk factors will be concern to clinicians for the reduction in the risk of myocardial infarction.

Treatment with different doses of folic acid in haemodialysis patients: effects on folate distribution and aminothiol concentrations.

BACKGROUND: Hyperhomocysteinaemia is highly prevalent among haemodialysis patients and may contribute to their increased cardiovascular risk. Treatment with pharmacological doses of folic acid lowers the plasma homocysteine concentration in these patients. The purpose of the present study was to expand the knowledge about such treatment by testing the effects of stepwise increases in the dose of folic acid on the concentrations of plasma and red blood cell folate as well as the total plasma concentrations of homocysteine (tHcy), cysteine (tCys), and glutathione (tGSH) in patients on chronic hemodialysis. METHODS: Fourteen stable haemodialysis patients completed the study which consisted of four consecutive periods, each of 6 weeks duration: (i) no treatment with folic acid (control period); (ii) 5 mg of folic acid three times per week (15 mg/week); (iii) 5 mg of folic acid daily (35 mg/week); (iv) 10 mg of folic acid daily (70 mg/week). RESULTS: Neither plasma or red cell folate nor plasma aminothiol concentrations changed significantly during the control period. The mean red cell folate concentration doubled during the administration of folic acid at the dose of 15 mg/week but at higher doses the further rise was only marginal. The mean folate concentration in plasma increased steeply especially at the higher doses of folic acid. During treatment with 15 mg/week of folic acid, tHcy fell by a mean of 36%, tGSH increased by a mean of 34%, but tCys was unaffected. Increases in the dose of folic acid did not augment these responses. CONCLUSIONS: The maximal effect on tHcy seemed to be obtained already at the lowest given dose of folic acid (15 mg/week). At that dose, the red blood cells approached folate saturation, which may reflect the situation in other cells that participate in homocysteine metabolism and explain why further increases in the dose of folic acid are not effective from a tHcy-lowering point of view.

Whole blood folate, homocysteine in serum, and risk of first acute myocardial infarction.

High level of total homocysteine (tHcy) is a risk factor for coronary artery disease (CAD), but the mechanism is not known. The serum concentration of tHcy, total cholesterol, high density lipoprotein cholesterol (HDL-C), and apolipoprotein A-I (apo A-I) and the concentration of folate in whole blood were measured in 107 patients with first acute myocardial infarction (MI) and 103 controls. The level of whole blood folate was lower and that of tHcy higher in cases than in controls. An increase of 50 nmol/l whole blood folate was associated with an OR for MI of 0.75, and an increase of 5 micromol/l tHcy with an OR for MI of 1.57. Correlations were observed between the levels of whole blood folate and tHcy and between whole blood folate and alcohol intake, and in MI cases, between tHcy, HDL-C, and apo A-I as well as between HDL-C and alcohol intake. The number of cigarette smokers was higher among cases than controls. In smokers, the level of tHcy was higher and that of whole blood folate lower than in non-smokers. After adjustment for smoking, the whole blood folate and tHcy-associated risks of MI became non-significant. We conclude that smoking may affect folate status and tHcy level adversely. The risk of MI in smokers may at least partly be attributed to hyperhomocysteinemia or low folate.

Enzymatic deconjugation of erythrocyte polyglutamyl folates during preparation for folate assay: investigation with reversed-phase liquid chromatography.

Erythrocyte (RBC) folates occur mainly as 5-methyltetrahydrofolate polyglutamates. Determination of RBC folate concentration requires an initial deconjugation of these polyglutamates. In this study, existing HPLC methods were adapted to investigate the rate and extent of this deconjugation process. The action of endogenous plasma pteroyl-polyglutamate hydrolase activity was strongly affected by the conditions of sample preparation, with pH of the incubation mixture more critical to effective deconjugation than incubation time. Dilution of whole blood with 10 g/L ascorbic acid yielded fast hydrolysis of long-chain polyglutamates, and total conversion to 5-methyltetrahydrofolate monoglutamate occurred after 90 min of incubation at 37 degrees C. In contrast, dilution of whole blood with 10 g/L sodium ascorbate, with up to 90 min of incubation at 37 degrees C, yielded a mixture of polyglutamates of 5-methyltetrahydrofolate (glun = 1-8). As documented by direct HPLC analysis and in concurrent assays with Lactobacillus casei, acidification provided by ascorbic acid can have dramatic effects on the measurement of RBC folates.

Folate deficiency, biopterin and monoamine metabolism in depression.

Seven (21%) of 34 patients with a severe DSM-III diagnosis of major depression had red-cell folate levels below 150 ng/ml. This subgroup with folate deficiency had significantly lower CSF 5-hydroxyindoleacetic acid (5HIAA) compared to neurological controls. For all depressed patients red-cell folate was significantly correlated with CSF 5HIAA and homovanillic acid (HVA). CSF tetrahydrobiopterin (BH4) was significantly correlated with CSF 5HIAA and HVA and red-cell folate. Our observations provide further evidence of the links between folate, biopterin and monoamine metabolism in depression.

Teores de folato e vitamina B12 no sangue de nutrizes e lactentes de baixa renda e composição do leite referente a essas vitaminas: estudo de suas possíveis relações / Serum levels of folate and vitamin B12 of low-income nursing mothers and thier concentrations in milk referring to these vitamins: study of their possible relationships

As possíveis relações entre as concentrações séricas de folato e de vitamina B12 em nutrizes de baixa renda e as concentrações dessas vitaminas no soro da criança e no leite foram investigadas. Não foram aqui encontradas correlações significativas consistentes entre elas, exceto no caso do folato sérico da criança, que sofreu uma fraca influência do folato sérico materno no período de 6-280 dias pós-parto. As médias das concentrações séricas dessas vitaminas nas mães e nas crianças encontram-se na faixa de normalidade. Entretanto, este estudo alerta para o fato de que uma parcela considerável das nutrizes de baixa renda (18 por cento) e seus filhos (33 por cento) estão sob risco de deficiência de folato. O tipo de amamentação (mista ou exclusiva) não apresentou qualquer efeito sobre os parâmetros estudados. Com o avanço da lactação, aumentaram as concentrações de vitamina B12 sérica materna, de folato no leite e a saturação da proteína ligante de folato. As proteínas ligantes de vitamina B12 e de folato no leite não influenciaram de forma consistente as concentrações dessas vitaminas no soro das crianças.