Hyperhomocystinemia in patients with coronary artery disease

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview

Aging is defined as the accumulation of progressive organ dysfunction. There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. With increasing age, susceptibility to the development of diseases related to lipid peroxidation and tissue injury increases, due to chronic inflammatory processes, and production of reactive oxygen species (ROS) and free radicals. The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. The most studied member product is PON1, a protein associated with high-density lipoprotein with paraoxonase/esterase activity. Nevertheless, all the three proteins prevent oxidative stress. The major aim of this review is to highlight the importance of the role of PON enzymes in the aging process, and in the development of the main diseases present in the elderly: cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer.

[Study of cardiovascular risk factors in Tunisian patients with recent type 2 diabetes]

OBJECTIVE

To study the frequency of silent myocardial ischemia (SMI) in Tunisian patients with recent type 2 diabetes and identify cardiovascular risk factors directly in relation with SMI.

PATIENTS AND METHODS

One hundred and twenty diabetics and sixty healthy people have benefited from blood sampling, electrocardiogram and exercise test.

RESULTS

The frequency of SMI was 21% in diabetics and 3% in healthy people (P=0.01). Obesity and hypertension were higher in diabetics than in healthy people (P=0.001 and P<10(-4)). Using unvaried analysis for risk factors with the presence of SMI in diabetics, we found that age greater than 60 yrs, male sex, sedentary and smoking were significantly correlated with SMI; respectively P=0.004, 0.01, 0.009 and 0.03. The SMI was found in 37% of diabetics with high blood pressure vs 8% in diabetics with normal blood pressure and was correlated with hypertriglyceridemia, hypoHDLemia and microalbuminuria. Patients with SMI had at least two cardiovascular risk factors apart from diabetes among those: age greater or equal to 60 yrs, male sex, smoking, hypertension, dyslipidemia and family history of early coronaropathy. Chronic inflammation and hyperhomocysteinemia were significantly correlated to SMI; OR=4.2 and 3.8. In addition, SMI was found in one diabetic over three who had bad glycemic control. Using multivariate analysis, only age greater or equal to 60 yrs, smoking, hypertension, hyperhomocysteinemia and hypertriglyceridemia were risk factors directly in relation with SMI in type 2 diabetes.

CONCLUSION

The assessment of global cardiovascular risk from the moment of discovering type 2 diabetes and the early screening of SMI should be necessary.

Serum adiponectin is associated with homocysteine in elderly men and women, and with 5,10-methylenetetrahydrofolate reductase (MTHFR) in a sex-dependent manner

Plasma homocysteine associates positively with cardiovascular disease. C-to-T substitution at base 677 of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene associates with increased plasma homocysteine. The association of adiponectin with cardiovascular disease is unclear. This study of survivors of a 30-year cohort of the Jewish Israeli population, 310 men and 273 women (mean age, 70.5 ± 7.0 years for both), investigated the relationship between adiponectin and homocysteine, and between adiponectin and the MTHFR C677T genotype. Serum adiponectin associated positively with total homocysteine in both men (r = 0.27, P < .001) and women (r = 0.22, P < .001). In women, the TT MTHFR genotype associated with lower median adiponectin levels, 8.98 mg/L, compared with 9.88 and 10.57 mg/L for TC and CC, respectively (P = .05; CC vs TT, P = .01). In men, the trend was opposite, but not statistically significant: 7.90, 7.03, and 6.88 mg/L for TT, TC, and CC genotypes, respectively (P = .5). This study demonstrated a positive association between homocysteine and adiponectin in both elderly men and women and a statistically significant association between adiponectin and MTHFR C677T genotypes in women only.

Homocysteine predicts adverse clinical outcomes in unstable angina and non-ST elevation myocardial infarction: implications from the folate intervention in non-ST elevation myocardial infarction and unstable angina study

BACKGROUND

Unstable angina and non-ST elevation myocardial infarction (NSTEMI) are common acute coronary events. Homocysteine is a novel risk factor for coronary heart diseases. Together with the conventional risk factors, they may affect the outcome of non-ST coronary events.

OBJECTIVE

This study aims to determine the effect of clinical risk factors that are responsible for the occurrence of mortality, and the composite outcome of mortality, nonfatal myocardial infarction and serious rehospitalization within 6 months after the onset of non-ST acute coronary syndromes.

METHODS

A total of 124 Filipino patients were interviewed and tested for blood homocysteine levels and lipid profiles. Outcomes were assessed after 6 months.

RESULTS

Homocysteinemia (>16 micromol/l) is associated with increased mortality and composite outcomes (mortality, nonfatal reinfarction, and serious rehospitalization), even if adjusted for conventional risk factors. No association was detected for the conventional risk factors. Earlier acute coronary syndrome was found to be positively associated with mortality and the composite outcomes. Early stroke is associated with increased composite outcomes, whereas greater mortality and adverse outcomes were observed in NSTEMI compared with intermediate-risk unstable angina.

CONCLUSION

Increased homocysteine level is associated with mortality and serious nonfatal outcomes in patients with unstable angina and NSTEMI.

[Effect of polymorphisms on key enzymes in homocysteine metabolism, on plasma homocysteine level and on coronary artery-disease risk in a Tunisian population]

BACKGROUND

Hyperhomocysteinemia is known as an independent-risk factor for coronary-artery disease (CAD). However, the effect of homocystein metabolic enzymes polymorphisms on CAD is still controversed. We investigated the relation between homocystein metabolic key enzymes polymorphisms, homocystenemia and coronary stenosis in a Tunisian population.

METHODS

Samples were collected from 251 CAD patients documented by angiography. Genotyping were performed for C677T methylene-tetrahydrofolate reductase (MTHFR), A2756G methionine-synthase (MS) and 844ins 68 cystathionine-beta-synthase (CBS). We measured fasting plasma tHcy, folate and vitamin B12.

RESULTS

There was significant increase in homocysteinemia for homozygous genotypes of C677T MTHFR (p<0.001) and A2756G MS (p=0.01), but not for 844ins68 CBS (p=0.105). Potential confounders adjusted odds-ratios for significant coronary stenosis, associated with MTHFR TT, MS GG and CBS insertion, were respectively 1.78 (p=0.041); 2.33 (p=0.036) and 0.87 (p=0.823). The effect of mutated MTHFR genotype was more pronounced on homocysteinemia (21.4+/-9.1 micromol/L; p<0.001) and coronary stenosis (OR=2.73; p=0.033) at low folatemia (< or =6.1 ng/mL).

CONCLUSION

MTHFR TT and MS GG genotypes increase tHcy concentration and coronary stenosis risk, especially with low folatemia.

Gene-gene interactions in the folate metabolic pathway influence the risk for acute lymphoblastic leukemia in children

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer. Genetic polymorphisms in the folate metabolic pathway may contribute to the susceptibility to childhood ALL because they affect the DNA synthesis, methylation and repair. We analysed common genetic polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR), thymidylate synthase (TS), methionine synthase (MS) and methionine synthase reductase (MTRR) in 68 children with ALL and 258 healthy controls to investigate their influence on the risk for ALL. No significant differences in frequencies of separate polymorphisms were observed between both groups. Combined MTHFR 677CT/TT and MS 2756AG/GG genotypes showed a nonsignificant tendency to reduce the risk for ALL 2.24-fold (CI: 0.191 - 1.037, P: 0.061). The risk was significantly reduced in carriers of combined MTHFR 677CT/TT, MS 2756AG/GG and MTRR 66AG/GG genotypes (OR: 0.312; CI: 0.107 - 0.907; P: 0.032). Our results suggest that gene - gene interactions that may decrease the methylation capacity might have a protective effect on the risk for childhood ALL.