Usefulness of daily folic acid supplementation during methotrexate treatment of Japanese patients with rheumatoid arthritis.

OBJECTIVES: We investigated the effect of daily folic acid supplementation on methotrexate (MTX) toxicity and efficacy in Japanese patients with rheumatoid arthritis (RA). METHODS: We followed 19 patients treated with MTX who switched from taking weekly 5 mg folic acid supplementation (weekly regimen) to 1.25 mg daily (daily regimen). White blood cell (WBC) and platelet (PLT) counts, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels were collected for 24 weeks following the change. RESULTS: We observed no significant changes in WBC or PLT counts. AST and ALT levels, which had exceeded the upper limits of their normal ranges at the beginning of the study, were improved significantly at weeks 4 and 8, no subsequent deterioration in liver function was found. Further, no significant changes in ESR and CRP levels were observed. CONCLUSION: Our data indicate that supplementing 1.25 mg of folic acid daily rather than 5 mg weekly reduces toxicity caused by MTX without affecting its efficacy.

Performance of a Predictive Model for Long-Term Hemoglobin Response to Darbepoetin and Iron Administration in a Large Cohort of Hemodialysis Patients.

Anemia management, based on erythropoiesis stimulating agents (ESA) and iron supplementation, has become an increasingly challenging problem in hemodialysis patients. Maintaining hemodialysis patients within narrow hemoglobin targets, preventing cycling outside target, and reducing ESA dosing to prevent adverse outcomes requires considerable attention from caregivers. Anticipation of the long-term response (i.e. at 3 months) to the ESA/iron therapy would be of fundamental importance for planning a successful treatment strategy. To this end, we developed a predictive model designed to support decision-making regarding anemia management in hemodialysis (HD) patients treated in center. An Artificial Neural Network (ANN) algorithm for predicting hemoglobin concentrations three months into the future was developed and evaluated in a retrospective study on a sample population of 1558 HD patients treated with intravenous (IV) darbepoetin alfa, and IV iron (sucrose or gluconate). Model inputs were the last 90 days of patients' medical history and the subsequent 90 days of darbepoetin/iron prescription. Our model was able to predict individual variation of hemoglobin concentration 3 months in the future with a Mean Absolute Error (MAE) of 0.75 g/dL. Error analysis showed a narrow Gaussian distribution centered in 0 g/dL; a root cause analysis identified intercurrent and/or unpredictable events associated with hospitalization, blood transfusion, and laboratory error or misreported hemoglobin values as the main reasons for large discrepancy between predicted versus observed hemoglobin values. Our ANN predictive model offers a simple and reliable tool applicable in daily clinical practice for predicting the long-term response to ESA/iron therapy of HD patients.

Long-term safety and efficacy of a novel iron-containing phosphate binder, JTT-751, in patients receiving hemodialysis.

OBJECTIVE: JTT-751 is a novel phosphate binder containing ferric citrate as the active ingredient. This study investigated long-term safety and efficacy of JTT-751 for hyperphosphatemia in patients receiving hemodialysis. DESIGN AND METHODS: This was 52-week, phase 3, multicenter, open-label, dose titration, long-term study. All patients were receiving thrice-weekly hemodialysis for ≥3 months before the initiation of the study. JTT-751 was given at titrated doses between 1.5 and 6.0 g/day. MAIN OUTCOME MEASURES: Safety endpoints were adverse events and adverse drug reactions. Efficacy outcomes were the change in serum phosphate, corrected serum calcium, and intact parathyroid hormone. Changes in ferritin, transferrin saturation, and doses of erythropoiesis-stimulating agents (ESAs) and intravenous iron formulations were additional outcomes. RESULTS: One hundred and eighty patients were included in the trial. Dose-titrated JTT-751 decreased mean serum phosphate after administration and satisfactorily maintained serum phosphate concentrations throughout the entire duration of the 52-week trial. Mean serum phosphate concentrations were kept lower than 5.5 mg/dL from weeks 5 to 52. The most common adverse events were gastrointestinal disorders, which were mild to moderate in intensity. Serum ferritin concentrations rose to a peak around week 28 and stabilized thereafter. The mean intravenous iron dose decreased from 57.3 mg/4 weeks (weeks 0-12) to 3.6 mg/4 weeks (weeks 28-52); weekly ESA dose declined by 25% over the same time frame, while mean hemoglobin concentrations remained stable. CONCLUSION: JTT-751 1.5-6.0 g/day controls serum phosphorus concentrations and reduces the need for ESAs and intravenous iron in patients receiving hemodialysis.

Comparative bioavailability of ferrous succinate tablet formulations without correction for baseline circadian changes in iron concentration in healthy Chinese male subjects: a single-dose, randomized, 2-period crossover study.

BACKGROUND: Ferrous succinate is used for the treatment of iron deficiency anemia. Determining the bioavailability of iron products is a challenge, because iron is naturally present in the blood and some tissues. Therefore, bioequivalence evaluation of ferrous formulations can be affected by the presence of endogenous iron species. Little information regarding the pharmacokinetics of ferrous supplements is available in the healthy Chinese population. OBJECTIVES: The aim of the study was to assess the comparative bioavailability of 200-mg of a test (ferrous succinate,100 mg × 2, Hunan Huana Pharmaceutical Co., Ltd., Hunan, China) and reference (Sulifei, 100 mg × 2, Nanjing Jinling Pharmaceutical Co., Ltd., Nanjing, China) formulation in healthy Chinese male subjects. The study was conducted to meet Chinese State Food and Drug Administration regulatory requirements for approval of a generic formulation of ferrous succinate. METHODS: This study utilized a single-dose randomized, 2-period, crossover design with alternate assignment of subjects to treatment (a single 200-mg [100 mg × 2]) or reference formulation groups. Both groups underwent a 4-day diet equilibration before 2 days of treatment and, finally, a 4-day washout period for the bioequivalence study. Blood samples were collected at 8:00 am on every diet equilibration day, 0 (baseline), 1, 2, 3, 4, 4.5, 5, 6, 9, 12, 24, and 36 hours after drug administration. Iron concentrations were determined using an inductively coupled plasma mass spectrometry. Subjects in both groups were given a standardized diet, with known amounts of iron and calories. The formulations were assumed to be bioequivalent if the 90% CI ratios for C(max) were within 70% to 143% and AUC(0-last) were within 80% to 125%-criteria established by the Chinese Food and Drug Administration. Tolerability was monitored throughout the study by assessing clinical parameters (vital signs, chemistry laboratory) and subject reports. RESULTS: Twenty healthy Han Chinese male subjects (mean age, 26.8 years [range, 20-39 years]; weight, 61.9 kg [range, 52-72 kg]; body mass index, 21.5 kg/m(2) [range,19.1-23.8 kg/m(2)]; and baseline iron values, 1271 µg/L [range 1113-1429 µg/L]) were enrolled and completed the study. Without baseline correction for endogenous iron compound, the mean C(max) measurements of iron for the test and reference formulations were 2981 [621.1] and 3028 [707.4] µg/L, respectively; AUC(0-last) values were 48,460 [9242] and 48,390 [8420] µg/L/h, respectively; T(max) values were 4.3 [1.6] and 3.7 [1.3] hours. The 90% CIs for the ratios of C(max) and AUC(0-last) were 89.9% to 109.2% and 92.5% to 107.7%. No significant difference was found between groups with regard to pharmacokinetic parameters. Both test and reference formulations were well tolerated, with only 2 (10%) subjects who received the reference formulation complaining of mild heartburn that resolved after approximately 1 hour. Another subject (5%) complained of nausea 10 minutes after the test administration, which resolved within 2 hours. The relative bioavailability of the test-reference preparations was 101.6%. CONCLUSION: In this single-dose crossover study in healthy Chinese male subjects, the test and reference formulations of ferrous succinate 200-mg (100 mg × 2,) tablets met the criteria for assuming bioequivalence as defined by the Chinese Food and Drug Administration. Both formulations were well tolerated. Chinese Clinical Trials registration number: ChiCTR-TRC-11001646.

Therapy-resistant anaemia in congenital nephrotic syndrome of the Finnish type--implication of EPO, transferrin and transcobalamin losses.

Congenital nephrotic syndrome of the Finnish type (CNF) is due to NPHS1 mutation and is responsible for a variety of urinary protein losses. We report the case of a 4-month-old girl with a particularly severe form (proteinuria approximately 150 g/l) of CNF. She developed severe non-regenerative anaemia requiring bi-monthly blood transfusions despite daily EPO (600 UI/kg) and iron supplementation. Epoetin pharmacokinetics revealed a urinary loss of 27% of the given dose within the first 24 h after IV injection. However, plasma levels remained increased after 24 h (228 UI/l). Plasma transferrin and transcobalamin levels were undetectable. Atransferrinaemia and atranscobalaminaemia seem to be responsible for disturbed erythropoiesis.

Maternal folate deficiency affects proliferation, but not apoptosis, in embryonic mouse heart.

Low dietary folate and deficiency of methylenetetrahydrofolate reductase (Mthfr) were reported to increase the risk for congenital heart defects, but contributory mechanisms have not been elucidated. Because low folate and absent MTHFR activity were shown to affect proliferation and apoptosis in developing neural tissue, we examined these processes in the myocardium of embryos from Mthfr +/+ and Mthfr +/- mice fed control diets (CD) or folic acid-deficient diets (FADD). Mice consumed the designated diets for 8 wk, from weaning and through pregnancy until they were killed. Embryos were assessed on gestational day 12.5 for myocardial proliferation by 5-bromo-2'-deoxyuridine (BrdU) labeling and for apoptosis by TdT-mediated dUTP nick end labeling staining and caspase 3/7 activity assays. FADD-treated dams had significantly higher resorption rates than CD-treated dams. Embryonic lengths and weights from FADD-treated dams were significantly lower than those from CD-treated dams; the smallest embryos were those of the Mthfr +/- dams that consumed the FADD, with effect of genotype tending to be significant (P = 0.09). The thickness of cardiac ventricular compact walls of embryos from FADD-treated dams was significantly reduced, and embryonic myocardium from FADD-treated dams had significantly fewer BrdU-labeled cells compared with CD-treated dams, with no differences in apoptosis due to the diets. Genotype did not affect proliferation or apoptosis. Our results suggest that proliferation of embryonic myocardium is sensitive to maternal dietary folate and that folate supplementation during pregnancy is important for normal heart development and prevention of heart defects.

Unmetabolized folic acid in plasma is associated with reduced natural killer cell cytotoxicity among postmenopausal women.

Folic acid (FA) supplements and food fortification are used to prevent neural tube defects and to lower plasma homocysteine. Through exposure to food fortification and vitamin supplement use, large populations in the United States and elsewhere have an unprecedented high FA intake. We evaluated dietary and supplemental intakes of folate and FA in relation to an index of immune function, natural killer cell (NK) cytotoxicity, among 105 healthy, postmenopausal women. Among women with a diet low in folate (<233 microg/d), those who used FA-containing supplements had significantly greater NK cytotoxicity (P = 0.01). However, those who consumed a folate-rich diet and in addition used FA supplements > 400 microg/d had reduced NK cytotoxicity compared with those consuming a low-folate diet and no supplements (P = 0.02). Prompted by this observation, we assessed the presence of unmetabolized FA in plasma as a biochemical marker of excess FA. Unmetabolized folic acid was detected in 78% of plasma samples from fasting participants. We found an inverse relation between the presence of unmetabolized FA in plasma and NK cytotoxicity. NK cytotoxicity was approximately 23% lower among women with detectable folic acid (P = 0.04). This inverse relation was stronger among women >or= 60 y old and more pronounced with increasing unmetabolized FA concentrations (P-trend = 0.002). Because of the increased intake of FA in many countries, our findings highlight the need for further studies on the effect of long-term high FA intake on immune function and health.

Folic acid supplementation for 3 wk reduces pulse pressure and large artery stiffness independent of MTHFR genotype.

BACKGROUND: Folic acid reduces plasma homocysteine and may be an important therapy for preventing cardiovascular disease. A key mechanism may be the reduction of arterial stiffness. OBJECTIVE: The effect of folic acid supplementation on blood pressure and large artery stiffness was examined in relation to methylenetetrahydrofolate reductase (MTHFR) genotype. DESIGN: Forty-one asymptomatic men with normal or high-normal ambulatory blood pressure (systolic: >130 to <145 mm Hg; diastolic: >80 to <90 mm Hg) participated. The study had a randomized, placebo-controlled, double-blind, crossover design that incorporated 3-wk treatments with 5 mg folic acid/d or matching placebo; each treatment was separated by a 4-wk washout phase. RESULTS: Folic acid reduced brachial pulse pressure by 4.7 +/- 1.6 mm Hg (P < 0.05) without changing mean arterial pressure. Systemic arterial compliance increased by 0.15 +/- 0.03 mL/mm Hg (P < 0.05) after folic acid treatment but did not change after placebo treatment. These responses did not significantly correlate with either homocysteine or folate plasma concentrations. MTHFR genotype CC homozygotes (without the 677C-->T polymorphism) with normal blood pressure had a larger reduction in homocysteine concentrations in response to folic acid than did T allele carriers. Blood pressure and arterial stiffness responses were independent of MTHFR genotype. CONCLUSION: Folic acid is a safe and effective supplement that targets large artery stiffness and may prevent isolated systolic hypertension.

Betaine concentration as a determinant of fasting total homocysteine concentrations and the effect of folic acid supplementation on betaine concentrations.

BACKGROUND: Remethylation of homocysteine to methionine can occur through either the folate-dependent methionine synthase pathway or the betaine-dependent betaine-homocysteine methyltransferase pathway. The relevance of betaine as a determinant of fasting total homocysteine (tHcy) is not known, nor is it known how the 2 remethylation pathways are interrelated. OBJECTIVE: The objectives of the study were to examine the relation between plasma betaine concentration and fasting plasma tHcy concentrations and to assess the effect of folic acid supplementation on betaine concentrations in healthy subjects. DESIGN: A double-blind randomized trial of 6 incremental daily doses of folic acid (50-800 microg/d) or placebo was carried out in 308 Dutch men and postmenopausal women (aged 50-75 y). Fasted blood concentrations of tHcy, betaine, choline, dimethylglycine, and folate were measured at baseline and after 12 wk of vitamin supplementation. RESULTS: Concentrations of tHcy were inversely related to the betaine concentration (r = -0.17, P < 0.01), and the association was independent of age, sex, and serum concentrations of folate, creatinine, and cobalamin. Folic acid supplementation increased betaine concentration in a dose-dependent manner (P for trend = 0.018); the maximum increase (15%) was obtained at daily doses of 400-800 microg/d. CONCLUSIONS: The plasma betaine concentration is a significant determinant of fasting tHcy concentrations in healthy humans. Folic acid supplementation increases the betaine concentration, which indicates that the 2 remethylation pathways are interrelated.

Plasma choline and betaine and their relation to plasma homocysteine in normal pregnancy.

BACKGROUND: Plasma concentrations of total homocysteine (tHcy) decrease during pregnancy. This reduction has been investigated in relation to folate status, but no study has addressed the possible role of betaine and its precursor choline. OBJECTIVE: We investigated the courses of plasma choline and betaine during normal human pregnancy and their relations to plasma tHcy. DESIGN: Blood samples were obtained monthly; the initial samples were taken at gestational week (GW) 9, and the last samples were taken approximately 3 mo postpartum. The study population comprised 50 women of West African descent. Most of the subjects took folic acid irregularly. RESULTS: Plasma choline (geometric x; 95% reference interval) increased continuously during pregnancy, from 6.6 (4.5, 9.7) micromol/L at GW 9 to 10.8 (7.4, 15.6) micromol/L at GW 36. Plasma betaine decreased in the first half of pregnancy, from 16.3 (8.6, 30.8) micromol/L at GW 9 to 10.3 (6.6, 16.2) micromol/L at GW 20 and remained constant thereafter. We confirmed a reduction in plasma tHcy, and the lowest concentration was found in the second trimester. From GW 16 onward, an inverse relation between plasma tHcy and betaine was observed. Multiple regression analysis showed that plasma betaine was a strong predictor of plasma tHcy from GW 20 onward. CONCLUSIONS: The steady increase in choline throughout gestation may ensure choline availability for placental transfer with subsequent use by the growing fetus. Betaine becomes a strong predictor of tHcy during the course of pregnancy. Both of these findings emphasize the importance of choline and betaine status during normal human pregnancy.

Sustained homocysteine-lowering effect over time of folic acid-based multivitamin therapy in stroke patients despite increasing folate status in the population.

BACKGROUND AND AIMS: It is uncertain what impact increasing voluntary folate fortification may be having on the statistical power of randomized trials testing the homocysteine hypothesis of atherothrombosis. The objective of this study was to determine whether there has been a change in folate status between 1998 and 2002 in stroke patients randomized into the VITAmins TO Prevent Stroke (VITATOPS) Study at a single center in Perth, Australia, and what impact this may have had on the magnitude of the homocysteine-lowering effect achieved over time with folic acid-based multivitamin therapy. METHODS: We conducted a randomized, double-blind, placebo-controlled study involving 285 patients with stroke or transient ischemic attack who were recruited between 1998 and 2002 and randomized to long-term folic acid 2.0 mg/day, pyridoxine 25 mg/day and cobalamin 0.5 mg/day (active VITATOPS medication) or placebo. Fasting plasma total homocysteine, red cell folate, serum cobalamin and serum pyridoxine levels were measured at baseline and 6 months, and the change in blood levels over 4 time quartiles and differences in levels between the two randomized treatments were examined. RESULTS: Between 1998 and 2002, there was a significant rise in baseline mean red cell folate levels over 4 time quartiles among the entire stroke cohort (723.3, 780.1, 922.6 and 1,023.7 nmol/l in the first, second, third and fourth quartiles, respectively; p < 0.0001), but this was not associated with a spontaneous reduction in mean baseline total homocysteine levels during the same time period (12.7, 14.3, 12.1 and 12.8 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.55). The homocysteine-lowering effect of the active VITATOPS trial medication at 6 months after randomization also did not change significantly between 1998 and 2002 (difference between randomized groups: -4.1, -4.1, -3.1 and -3.6 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.56). CONCLUSIONS: The homocysteine-lowering effect of the active VITATOPS trial medication has not attenuated significantly in the past 5 years despite increasing voluntary fortification of foods with folic acid as reflected by a progressive rise in baseline folate status. These data suggest that in the continuing absence of a program of mandatory folate fortification of food in populations served by centers participating in the VITATOPS trial, the study will remain adequately powered to test the homocysteine-lowering hypothesis for which it was designed.

Folic acid improves endothelial function in children and adolescents with type 1 diabetes.

OBJECTIVE: To evaluate the effect of folate supplementation on endothelial function in children and adolescents with type 1 diabetes. STUDY DESIGN: Thirty-six subjects with type 1 diabetes age 13.6+/-2.6 years completed a randomized, double-blind, placebo-controlled crossover trial. Each subject received 8 weeks of oral folic acid (5 mg/d) and 8 weeks of placebo, with an 8-week washout period. Before and after each intervention, we assessed endothelial function by using brachial artery responses to flow (flow-mediated dilatation [FMD]) and glyceryl trinitrate, von Willebrand factor, glucose, hemoglobin A1c, total plasma homocyst(e)ine (tHcy), vitamin B(12), serum folate, and red cell folate (RCF). RESULTS: Folic acid increased FMD by 2.58 (3.1-5.7) % (95% confidence interval, 1.28-3.88), whereas placebo did not change FMD (-0.42%; 95% confidence interval, -1.67 to 0.83; P<.001). Folic acid increased serum folate by 14 nmol/L (6.2 ng/mL, P<.001) and RCF by 467.2 nmol/L (206 ng/mL, P<.001). Change in FMD was related to change in serum folate (r=0.46, P=.005) and RCF (r=0.39, P=.02). Glyceryl trinitrate responses, von Willebrand factor, tHcy, and hemoglobin A1c were not affected by the intervention. CONCLUSIONS: Short-term high-dose folic acid improves endothelial function in children and adolescents with type 1 diabetes and normal folate status independently of tHcy.

Effect of incremental doses of folate on homocysteine and metabolically related vitamin concentrations in nondiabetic patients on peritoneal dialysis.

The role of folate supplementation in reducing hyperhomocystinemia in patients on dialysis has been reported, but the optimal dose of folate is still unknown. The aim of the present study was to investigate whether greater than 5 mg/day folate supplementation provides any additional effect on plasma homocysteine (HCY) levels. The study was prospective, open, and had no control group. Of the 64 eligible nondiabetic patients on peritoneal dialysis with hyperhomocystinemia (>20 micromol/L), 56 were given oral folate (5 mg/day) for 3 months. When Hcy did not fall below 20 micromol/L, folate doses were increased by 5 mg every 3 months to up to 15 mg/day. With 5 mg/day supplementation, serum folate concentrations increased above the upper confidence limit in 23 patients and erythrocyte folate concentrations in 27 patients. Hcy levels decreased to less than 15 micromol/L in 6 cases and by more than 50% in 12 cases. Nineteen of the remaining patients were given 10 mg/day folate. After increasing the dose, serum and erythrocyte folate levels rose above the upper detection limit. In one patient, plasma Hcy concentrations decreased to less than 15 micromol/L. Ten patients were given 15 mg/day oral folate for an additional 3 months with no effect on homocystinemia. This study confirms that oral folate supplementation may improve hyperhomocystinemia even in patients on dialysis with normal serum or erythrocyte folate concentrations. In fact, serum and erythrocyte levels cannot predict the effect of supplementation on plasma Hcy levels. However, 5 mg/day folate supplementation normalized Hcy in 10% of cases and reduced Hcy levels in another 21%. Increasing the folate dose to greater than 5 mg/day had a minimal (10 mg/day) or no (15 mg/day) additional effect on Hcy concentrations. Despite the minimal effect of increasing folate doses, given the low cost, the absence of side effects, and the high cardiovascular risk for patients on peritoneal dialysis, a careful attempt to increase the dose of oral folate up to 10 mg/day might be suggested.

Treatment of hyperhomocysteinemia in pediatric heart transplant recipients.

BACKGROUND: Graft coronary artery vasculopathy is the main cause of late morbidity and mortality in pediatric cardiac allograft recipients. Growing evidence suggests that elevated plasma homocysteine levels are associated with cardiac allograft vasculopathy following heart transplantation. The purpose of this study was to evaluate the effect of vitamin supplementation as a potential strategy for reducing homocysteine levels in pediatric heart transplant recipients and examine creatinine levels as potential determinants of plasma homocysteine concentration after transplantation. METHODS: We studied 27 pediatric heart transplant patients with homocysteine levels higher than normal. All children received vitamin supplementation (vitamin B(12), vitamin E, vitamin A and folic acid). During treatment, levels of homocysteine, vitamins and creatinine were evaluated after 3, 6, 9 and 12 months. RESULTS: We observed a significant homocysteine concentration decrease after treatment at every determination, whereas no significant change occurred for creatinine. Vitamin B(12) serum level increased markedly, whereas folic acid, vitamin E and vitamin A serum levels showed only minor increases. CONCLUSIONS: We observed a significant increase of mean levels of vitamin B(12) and a moderate increase in the other 3 vitamins. We also observed a significant reduction in homocysteine levels, which returned to normal levels for age. In our patients, there was a correlation, before and after treatment, between homocysteine and creatinine levels, but there was no a direct correlation between creatinine serum levels and homocysteine reduction. We conclude that vitamin supplementation reduces and may normalize homocysteine serum level after pediatric heart transplantation.

Folic acid enhances endothelial function and reduces blood pressure in smokers: a randomized controlled trial.

OBJECTIVE: Cigarette smoking is associated with increased plasma homocysteine concentrations, endothelial dysfunction and arterial stiffening. Homocysteine per se induces endothelial dysfunction and arterial stiffening and might account, at least partly, for the vascular abnormalities observed in smokers. We sought to determine whether folic acid supplementation, by reducing plasma homocysteine concentrations, enhanced endothelial function and reduced arterial stiffness in smokers. DESIGN: Double-blind, randomized controlled, parallel-group, trial. SETTING: Academic medical centre. SUBJECTS: A consecutive sample of 24 healthy cigarette smokers (age 37.8 +/- 2.5 years, mean +/- SEM). INTERVENTION: Subjects were randomly assigned to 4-week folic acid 5 mg day-1 or placebo. MAIN OUTCOME MEASURES: The following were measured before and after treatment: (i) peripheral vasoreactivity (forearm arterial blood flow, FABF) during intra-arterial administration of endothelium-dependent (acetylcholine 1.5, 4.5 and 15 microg min-1) and endothelium-independent (sodium nitroprusside 1, 2 and 4 microg min-1) vasodilators; (ii) carotid-femoral pulse-wave velocity (PWV); (iii) blood pressure (BP). RESULTS: Folic acid reduced homocysteine concentrations (10.8 +/- 0.6 vs. 8.2 +/- 0.5 micromol L-1, P < 0.001) and enhanced endothelium-dependent vasodilatation during each acetylcholine infusion rate (ratio between the FABF in the infused and control arm during increasing infusion rates at baseline 1.09 +/- 0.03 vs. 1.41 +/- 0.09 after treatment, P < 0.01; 1.39 +/- 0.07 vs. 1.83 +/- 0.12, P < 0.01; 1.65 +/- 0.16 vs. 2.72 +/- 0.36, P < 0.05) whilst endothelium-independent vasodilatation was unaffected. A significant fall in BP was also observed (mean BP 88 +/- 2 vs. 83 +/- 1 mmHg, P < 0.01). By contrast, PWV did not significantly change (8.4 +/- 0.3 vs. 7.8 +/- 0.4 m s-1). No significant changes in plasma homocysteine concentrations, FABF, BP, and PWV were observed in the placebo group. A multiple regression analysis showed that changes in folic acid plasma concentrations independently predicted both FABF changes during maximal acetylcholine-mediated vasodilatation (P < 0.01) and BP changes (P = 0.01). CONCLUSIONS: Short-term folic acid supplementation significantly enhanced endothelial function and reduced BP in young chronic smokers. These effects were largely independent from the homocysteine lowering effects. Thus, a simple, nontoxic, and relatively inexpensive vitamin intervention might be useful in primary cardiovascular prevention in this high-risk group.

Distribution of plasma folate forms in hemodialysis patients receiving high daily doses of L-folinic or folic acid.

BACKGROUND: We have previously reported that a daily oral high dose of l-folinic acid for the treatment of hyperhomocysteinemia in hemodialysis patients does not provide significantly greater reduction in fasting total homocysteine (tHcy) levels than an equimolar dose of folic acid. The present study uses the affinity/HPLC method to analyze the distribution of plasma folate forms in patients who received l-folinic acid versus those who received folic acid. This was done to investigate claims that renal insufficiency is associated with impaired folate interconversion, a stance that is supportive of the premise that tHcy lowering in these patients is more efficacious with folinic acid and other reduced folates, than folic acid. METHODS: Forty-eight chronic and stable hemodialysis patients were block-randomized, based on their screening predialysis tHcy levels, sex, and dialysis center, into two groups treated for 12 weeks with oral folic acid at 15 mg/day or an equimolar amount (20 mg/day) of oral l-folinic acid. All 48 subjects also received 50 mg/day of oral vitamin B6 and 1 mg/day of oral vitamin B12. Folate distribution was determined in plasma of 46 participants (Folinic acid group, N = 22; Folic acid group, N = 24) by using the affinity/HPLC method, with electrochemical (coulometric) detection. RESULTS: Both groups had similar baseline geometric means of plasma total folate and similar folate forms distribution. Following treatment, both groups demonstrated similar marked elevation in plasma total folate (geometric mean of the increase: Folinic acid group, +337 ng/mL; Folic acid group, +312 ng/mL; P = 0.796). In the folinic acid-treated group, practically all of the increase in total folate was due to 5-methyltetrahydrofolate. In the folic acid-treated group 5-methyltetrahydrofolate accounted for 35% of the increase in total folate and the remainder was unmethylated folic acid. CONCLUSIONS: Data from the present findings suggest that defects in folate absorption or impairment in folate interconversion are not the cause of the persistent hyperhomocysteinemia in hemodialysis patients.

Low-dose intravenous iron administration in chronic hemodialysis patients treated with recombinant human erythropoietin.

We conducted a prospective study to determine the effect of intravenous low-dose iron administration in chronic hemodialysis patients treated with recombinant human erythropoietin (rHuEPO). Sixteen hemodialysis patients (8 males and 8 females; mean age 63.1+/-9.8 years) on maintenance rHuEPO therapy were included in the study. Patients with <100 ng/ml of ferritin received 50 mg iron during every hemodialysis session. Patients with 100-200 ng/ml of ferritin were given 50 mg iron fortnightly. Iron was not supplemented in patients with ferritin levels >200 ng/ml. Mean hematocrit, serum iron levels and transferrin saturations were significantly higher at 6 and 12 months. There was a significant reduction in weekly rHuEPO doses between the start and the 6th and 12th months. Our study shows intravenous iron administration of 100 mg/month may be sufficient to achieve a satisfactory iron status in dialysis patients on maintenance rHuEPO therapy.