The lack of aspirin resistance in patients with coronary artery disease.

BACKGROUND: Aspirin resistance established by different laboratory methods is still a debated problem. Using COX1 specific methods no aspirin resistance was detected among healthy volunteers. Here we tested the effect of chronic aspirin treatment on platelets from patients with stable coronary artery disease. The expression of COX2 mRNA in platelets and its influences on the effect of aspirin was also investigated. METHODS: One hundred and forty four patients were enrolled in the study. The direct measurement of COX1 acetylation was carried out by monoclonal antibodies specific to acetylated and non-acetylated COX1 (acCOX1 and nacCOX1) using Western blotting technique. Arachidonic acid (AA) induced TXB2 production by platelets was measured by competitive immunoassay. AA induced platelet aggregation, ATP secretion and VerifyNow Aspirin Assay were also performed. COX2 and COX1 mRNA expression in platelets were measured in 56 patients by RT-qPCR. RESULTS: In 138 patients only acCOX1 was detected, in the remaining six patients nacCOX1 disappeared after a compliance period. AA induced TXB2 production by platelets was very low in all patients including the 6 patients after compliance. AA induced platelet aggregation, secretion and with a few exceptions the VerifyNow Assay also demonstrated the effect of aspirin. Smoking, diabetes mellitus and inflammatory conditions did not influence the results. The very low amount of COX2 mRNA detected in 39 % of the investigated platelets did not influence the effect of aspirin. CONCLUSIONS: No aspirin resistance was detected among patients with stable coronary artery disease. COX2 expression in platelets did not influence the effect of aspirin.

Plasma homocysteine levels, the prevalence of methylenetetrahydrofolate reductase gene C677T polymorphism and macrovascular disorders in systemic sclerosis: risk factors for accelerated macrovascular damage?

The purpose of this study was to investigate plasma homocysteine (Hcy) levels in patients with systemic sclerosis (SSc) and to study the association between plasma Hcy, C677T polymorphism of 5,10-methylenetetrahydrofolate reductase (MTHFR), and the clinical manifestations in SSc. Associations of Hcy level, C677T MTHFR polymorphism, and macrovascular diseases were investigated in 152 patients with SSc and 58 controls. No significant differences in Hcy levels and MTHFR genotypes were found in SSc patients compared to controls or in SSc patients with limited cutaneous compared to diffuse disease. Significantly higher Hcy concentration was observed in patients with macroangiopathy/thromboembolic events compared to patients without such clinical manifestations (p < 0.05). There was significant correlation between age and macrovascular disorders, between Hcy level and the disease duration (r = 0.164; p < 0.05). Seventy-one percent of patients with macrovascular disorders had MTHFR polymorphism. In addition, 45% of patients with hyperhomocysteinemia had pulmonary hypertension. The presence of MTHFR C677T mutation influences the incidence of macrovascular abnormalities in SSc patients. Elevated Hcy levels may be associated with disease duration and the evolution of macrovascular disorders and pulmonary hypertension in SSc.

[Frequency of hyperhomocysteinemia in hemodialysis patients with folic acid supplementation]. / A hyperhomocysteinaemia gyakorisága, folsavpótlásban részesüló hemodializált betegekben.

BACKGROUND: It is known that hyperhomocystinemia is an independent risk factor for development of atherosclerosis. In end stage renal disease the frequency of hyperhomocystinemia is much greater than in normal populations. AIM: In this study homocystein (Hcy), folic acid and vitamin B12 concentrations were determined in 125 chronic renal failure patients being on folic acid supplementation (3 mg/day). In 107 patients the frequency of C667T polymorphism of methylene tetrahyrofolate reductase (MTHFR) was also determined. The relationships between these parameters were also studied. RESULTS: It was found that in these patients who are under continuous folic acid supplementation the mean level of homocysteine was 16.8 +/- 7.2 mumol/L, a value considerably lower than the homocysteine concentration reported for non-supplemented patients. The elevation of homocysteine concentrations was independent of gender, time spent in renal replacement therapy, and the type of renal replacement therapy (hemodialysis: 17.6 +/- 12.6; hemodiafiltration: 16.6 +/- 12.9 mumol/L). Data showed an inverse relation between plasma homocysteine concentrations and the concentrations of folic acid and vitamin B12. Moderately severe hyperhomocystinemia (Hcy > 20 mumol/L) was found in about 30% of patients. In those the frequency of patients for homozygous T677 allele of MTHFR was about 25-30%. However, in all ESRD patients the frequency of the homozygotes was the same then in the normal population. Homocysteine plasma levels correlated with MTHFR polymorphism: in the wild type group Hcy was 14 +/- 7 mumol/L, in the heterozygous group was 17.2 +/- 6.2 mumol/L, and in the homozygous group was 21 +/- 19 mumol/L. CONCLUSIONS: Long-term folic acid supplementation decreased the homocysteine level in end stage renal disease patients. However, in folic acid resistant group, who were in 30% homozygotes for C667T of MTHFR (suggesting that homocysteine-methionine remethylation cycle is disturbed), instead of the administration of folic acid, methylene tetrahydrofolate supplementation might be considered.