Homocysteine, vitamin B(6), and lipid in cardiovascular disease

Homocystein as a risk factor for developing complications in chronic renal failure

Aim:

Cardiovascular diseases are leading cause of death in patients with chronic renal failure. The aim of our study was to establish connection between levels of homocysteine and traditional and nontraditional risk factors for developing cardiovascular diseases in dialysis and pre dialysis patients.

Methods:

We included 33 pre dialysis (23 in stage three and 10 in stage four of chronic kidney disease) and 43 patients receiving hemodialysis longer than six months. Besides standard laboratory parameters, levels of homocysteine and blood pressure were measured in all patients. Glomerular filtration rate was measured in pre dialysis patients and dialysis quality parameters in dialysis patients.

Results:

Homocysteine levels were elevated in all patients (19±5.42mmol/l). The connection between homocysteine levels and other cardiovascular diseases risk factors was not established in pre dialysis patients. In patients treated with hemodialysis we found negative correlation between homocysteine levels and patients’ age (p<0.05) and positive correlation between homocysteine levels and length of dialysis (p<0.01) as well as between homocysteine and anemia parameters (erythrocytes, hemoglobin), (p<0.01). Homocysteine and LDL (and total cholesterol) were in negative correlation (p<0.01).

Conclusion:

Homocysteine, as one of nontraditional cardiovascular diseases risk factors, is elevated in all patients with chronic renal failure and it’s positive correlation with some other risk factors was found.

Folate, vitamin B12, vitamin B6 and homocysteine: impact on pregnancy outcome

Good clinical practice recommends folic acid supplementation 1 month prior to pregnancy and during the first trimester to prevent congenital malformations. However, high rates of fetal growth and development in later pregnancy may increase the demand for folate. Folate and vitamins B12 and B6 are required for DNA synthesis and cell growth, and are involved in homocysteine metabolism. The primary aim of this study was to determine if maternal folate, vitamin B12, vitamin B6 and homocysteine concentrations at 18-20 weeks gestation are associated with subsequent adverse pregnancy outcomes, including pre-eclampsia and intrauterine growth restriction (IUGR). The secondary aim was to investigate maternal B vitamin concentrations with DNA damage markers in maternal lymphocytes. A prospective observational study was conducted at the Women's and Children's Hospital, Adelaide, South Australia. One hundred and thirty-seven subjects were identified prior to 20 weeks gestation as at high or low risk for subsequent adverse pregnancy outcome by senior obstetricians. Clinical status, dietary information, circulating micronutrients and genome damage biomarkers were assessed at 18-20 weeks gestation. Women who developed IUGR had reduced red blood cell (RBC) folate (P < 0.001) and increased plasma homocysteine concentrations (P < 0.001) compared with controls. Maternal DNA damage, represented by micronucleus frequency and nucleoplasmic bridges in lymphocytes, was positively correlated with homocysteine (r = 0.179, P = 0.038 and r = 0.171, P = 0.047, respectively). Multivariate regression analysis revealed RBC folate was a strong predictor of IUGR (P = 0.006). This study suggests that low maternal RBC folate and high homocysteine values in mid pregnancy are associated with subsequent reduced fetal growth.

Serum folate is a reliable indicator of hyperhomocysteinemia and borderline hyperhomocysteinemia in young adults

Serum folate has been shown to correlate well with fasting plasma homocysteine; however, erythrocyte folate concentration is a better index of tissue folate stores and probably could be a more reliable indicator for reflecting long-term supply of the vitamin and homocysteine status. The present study was undertaken to test the hypothesis that serum folate and erythrocyte folate levels had a different degree of correlation to fasting plasma homocysteine in young Taiwanese adults. This study had a cross-sectional design. Healthy young adults were divided into either a hyperhomocysteinemia (HHcy; > or =14.9 micromol/L; n = 13), borderline HHcy (BHcy; fasting homocysteine, 14.9-10.2 micromol/L; n = 52), or normohomocysteinemia (fasting homocysteine, <10.2 micromol/L; n = 65) groups based on fasting homocysteine levels. The concentrations of plasma fasting homocysteine, serum folate, erythrocyte folate, vitamin B(12), and plasma pyridoxal 5'-phosphate were measured. Fasting homocysteine was only significantly and inversely affected by serum folate (beta = -0.21, P < .05) concentration after adjusting for potential confounders. Only serum folate concentration remained to decrease the risk of fasting HHcy (odds ratio, 0.73; confidence interval, 0.56-0.95) after the other B vitamins were additionally adjusted. Serum folate also had the highest area under the receiver operating characteristic (AUC) curve to predict the risk of HHcy (AUC, 0.81) and BHcy (AUC, 0.77). Serum folate is a reliable indicator of fasting hyperhyperhomocysteinemia and BHcy in young adults.

Plasma pyridoxal 5'-phosphate and high-sensitivity C-reactive protein are independently associated with an increased risk of coronary artery disease

OBJECTIVE

Whether vitamin B6 exerts an independent or a synergic effect in combination with inflammation for the risk of coronary artery disease (CAD) is unclear. The purpose of this study was to investigate whether plasma pyridoxal 5'-phosphate (PLP) is dependent on or independent of the inflammation marker C-reactive protein (CRP) to associate with the risk of CAD.

METHODS

This was a hospital-based case-control. Patients were identified with cardiac catheterization as having at least 70% stenosis of one major coronary artery were assigned to the case group (n = 184). The control group (n = 516) was comprised of healthy individuals with normal blood biochemical values. All subjects' height, weight, blood pressure, plasma PLP, homocysteine, high-sensitivity CRP (hs-CRP), and lipid profiles were measured.

RESULTS

Plasma PLP concentration was only negatively associated with hs-CRP level in the control group (beta = -0.001, P = 0.03) but not in the CAD or pooled groups. The magnitude of the risk of CAD for low plasma PLP (odds ratio [OR] 2.39) and high hs-CRP (OR 3.37) was very similar. Low plasma PLP concentration combined with low hs-CRP level (OR 2.34) and high plasma PLP concentration combined with high hs-CRP level (OR 3.61) were independently associated with risk for CAD. However, the combined presence of low PLP and higher hs-CRP levels enhanced the risk of CAD and the magnitude was substantially greater (OR 4.35).

CONCLUSION

Plasma PLP and hs-CRP are independently associated with an increased risk of CAD, the combined presence of low PLP and high hs-CRP enhanced the risk of CAD, and the magnitude was almost double.

Multianalyte quantification of vitamin B6 and B2 species in the nanomolar range in human plasma by liquid chromatography-tandem mass spectrometry

BACKGROUND

Homocysteine, a risk factor of cardiovascular disease, cognitive disorders, and pregnancy complications, exists at a point of metabolic convergence of several B vitamins, including vitamins B(6) and B(2) (riboflavin). Measurement of the various forms of these vitamins may be useful for the study of hyperhomocysteinemia as well as for the assessment of vitamin status.

METHODS

Plasma (60 microL) was deproteinized by mixing with an equal volume of 50 g/L trichloroacetic acid that contained d(2)-pyridoxal 5'-phosphate, d(3)-pyridoxal, and d(8)-riboflavin as internal standards. Pyridoxal (PL), pyridoxal 5'-phosphate (PLP), pyridoxine (PN), pyridoxine 5'-phosphate, pyridoxamine (PM), pyridoxamine 5'-phosphate, 4-pyridoxic acid (PA), riboflavin, flavin mononucleotide (FMN), and FAD were separated on a C(8) reversed-phase column, which was developed with an acetonitrile gradient in a buffer containing acetic acid and heptafluorobutyric acid. The analytes were detected by tandem mass spectrometry in the positive-ion mode.

RESULTS

The chromatographic run lasted 8 min. Within- and between-day CVs were 3%-20% and 6%-22%, respectively, and recoveries were 78%-163%. Limits of detection (signal-to-noise ratio = 5) were in the range 0.1-4.0 nmol/L, and the response was linear over several orders of magnitude. In samples from 94 healthy persons, we obtained median concentrations (nmol/L) of 35.4 for PLP, 16.9 for PL, 22.4 for PA, 10.3 for riboflavin, 7.5 for FMN, and 63.1 for FAD. PN and PM were also detected in some cardiovascular patients taking B(6) supplements.

CONCLUSIONS

This method based on liquid chromatography-tandem mass spectrometry measures all known plasma forms of vitamins B(6) and B(2), which span a wide range of polarity. The assay is characterized by simple sample processing with no derivatization, low sample volume requirement, and a short run time.

Folic acid and vitamin B12 are more effective than vitamin B6 in lowering fasting plasma homocysteine concentration in patients with coronary artery disease

OBJECTIVE

To investigate whether vitamin B(6) supplementation had a beneficial effect on lowering fasting plasma homocysteine concentrations in coronary artery disease (CAD) patients.

DESIGN

A single-blind intervention study.

SETTING

The study was performed at the Taichung Veterans General Hospital, the central part of Taiwan.

SUBJECTS

A total of 50 subjects were identified by cardiac catheterization to have at least 70% stenosis of one major coronary artery. In all, 42 patients successfully completed this study.

INTERVENTIONS

Patients were randomly assigned to one of five groups and treated with a daily dose of placebo (n=8), 5 mg vitamin B(6) (n=8), 10 mg vitamin B(6) (n=8), 50 mg vitamin B(6) (n=9), or 5 mg folic acid combined with 0.25 mg vitamin B(12) (n=9) for 12 weeks.

MAIN OUTCOME MEASURES

Nutrient intakes were recorded by using 24-h diet recalls when patients returned to the cardiology clinic before the intervention (week 0) and at week 12. Vitamin B(6) status was assessed by direct measures (plasma pyridoxal 5'-phosphate) and indirect measures (erythrocyte alanine and aspartate aminotransaminase activity coefficient). Fasting plasma homocysteine, serum folic acid, and vitamin B(12) were measured.

RESULTS

Fasting plasma homocysteine concentration did not respond to high or low doses of vitamin B(6) when compared with a placebo treatment after 12 weeks of supplementation. The mean fasting plasma homocysteine concentration, however, decreased significantly after 12 weeks of folic acid combined with vitamin B(12) supplementation (P=0.047). Further, within group, mean fasting plasma homocysteine concentration was nonsignificantly increased by 25.5, 16.2, and 18.3% in placebo, 10 mg/day and 50 mg/day vitamin B(6) supplemented groups, respectively; whereas folic acid combined with vitamin B(12) supplementation significantly reduced fasting plasma homocysteine concentration by 32% (P<0.001).

CONCLUSIONS

Our results indicate that vitamin B(6) supplementation alone is less effective than folic acid combined with vitamin B(12) in lowering plasma homocysteine concentrations in CAD patients.

SPONSORSHIP

This study was supported by the National Science Council, Taiwan, Republic of China (NSC-91-2320-B-040-023).

The role of plasma thiol compounds and antioxidant vitamins in patients with cardiovascular diseases

BACKGROUND

Increased levels of homocysteine (Hcy) and cysteine (Cys) are associated with risk of cardiovascular diseases (CVD). These thiol compounds can generate various free radicals and so cause endothelial dysfunction. Antioxidant vitamins are effective scavengers of reactive oxygen species (ROS) and prevent endothelial dysfunction. In this study, we investigated the plasma homocysteine, cysteine, vitamins E, C and A, and beta-carotene (BC) levels in cardiovascular patients to compare with controls. We also investigated whether there is a correlation between the plasma thiol compounds and antioxidant vitamins.

METHODS

Blood samples were collected from 47 patients with cardiovascular disease (16 women and 31 men) and 21 healthy subjects (8 women and 13 men) in the overnight fasting state. Serum thiol compound and antioxidant vitamin levels were measured by high-pressure liquid chromatography (HPLC) methods.

RESULTS

The plasma homocysteine and cysteine levels were significantly higher in patients than those of controls. While vitamin C (VC), vitamin A (VA) and beta-carotene levels were significantly lower in patients than in controls, vitamin E (VE) levels did not change in both groups. There is a positive correlation between homocysteine and cysteine levels (r=0.622, p=0.000) in all study population. We found that the plasma level of homocysteine was significantly correlated in negative manner with vitamins E and A levels (r=-0.260, p=0.033 and r=-0.255, p=0.036, respectively) of all study population. Plasma cysteine levels were negatively correlated with only vitamin C levels (r=-0.320, p=0.008) in all study populations.

CONCLUSIONS

Our data suggest that Hcy and Cys are associated with cardiovascular disease and there is negative but weak correlation's between thiol compounds and antioxidant vitamins.

Lipoprotein oxidation, plasma total antioxidant capacity and homocysteine level in patients with multiple sclerosis

Free radical-mediated peroxidation of biological molecules, especially of lipids, is implicated in the pathogenesis of a number of diseases like multiple sclerosis. Low concentration of antioxidant vitamins: beta carotene, retinol, alpha tocopherol and ascorbic acid have been observed in serum or cerebrospinal fluid of multiple sclerosis patients. On the basis of these observations, we studied the potential lipoprotein oxidation and total antioxidant capacity in the pathogenesis of multiple sclerosis. Lipoprotein oxidizability for plasma in vitro, serum levels of autoantibodies against oxidized low-density lipoproteins, plasma total homocysteine levels with vitamin B12 and folate, and plasma total antioxidant capacity were measured in twenty four patients with multiple sclerosis and twenty four healthy sex- and age-matched person as control. In multiple sclerosis patients during an attack, a significant increase in both in vitro lipid oxidizability for plasma and in the levels of autoantibodies against oxidized low-density lipoproteins, and a strong decrease in plasma total antioxidant capacity were detected. Plasma total homocysteine levels were significantly higher in multiple sclerosis patients whose plasma vitamin B12 and folate levels were lower but not statistically significant, than controls. The present study indicates that lipoprotein oxidation may be important factor in the course of multiple sclerosis and in vitro measurements of plasma oxidation kinetics as an indication for lipoprotein oxidation might be useful as an additional tool for the clinical diagnosis of multiple sclerosis.