Assessment of serum levels of asymmetric dimethylarginine, symmetric dimethylarginine andl-arginine in coronary artery disease

Short-Term Effects of Supplemental L-Arginine, Diosmin, Troxerutin, and Hesperidin in Diabetic Patients: A Pilot Study

Background and Aims

Inflammatory, oxidative stress, and endothelial dysfunction play a key role in the pathogenesis of long-term cardiovascular complications in patients with diabetes. The present observational prospective study is aimed at evaluating the effects of micronutrients and phytochemicals contained in the dietary supplement Flebotrofine® (AMNOL Chimica Biologica) on biochemical markers of inflammation, endothelial dysfunction, and glycemic control in patients with diabetes.

Methods

105 type 1 or type 2 diabetes patients regularly took a daily dose of the dietary supplement Flebotrofine® for three consecutive months, and haematological and biochemical parameters were checked at baseline, after three months of treatment, and one month after its suspension. Statistical comparison of the laboratory parameters was performed using the two-tailed ANOVA test for repeated samples with a statistical significance level set at p < 0.05.

Results

The daily use of Flebotrofine® did not change the glycemic metabolic compensation of enrolled patients. After three months of regular Flebotrofine® intake, the plasma levels of the antioxidant β-carotene and of arginine were significantly higher compared with the baseline values, with a decrease in the ADMA/arginine ratio. In contrast, apolipoprotein B, ApoB/ApoA1 ratio, and platelet and leukocyte counts significantly dropped.

Conclusion

The daily use of Flebotrofine® might be a valid supplement of arginine, the precursor of NO, and essential in the prevention of endothelial dysfunction. The regular intake of arginine and phytochemicals also improved the antioxidant and antithrombotic profile of enrolled patients. Therefore, Flebotrofine® could be a useful dietary supplement to prevent long-term complications in patients with diabetes.

T-786C variation in the promoter sequence of human eNOS gene markedly influences its expression level

This study investigated the role of the T-786C polymorphism (SNP) in the 5'-flanking sequence of the endothelial nitric oxide synthase gene (eNOS) on its expression level in vascular endothelium with the ultimate goal of shedding more light on the mechanisms by which genetic variations of eNOS might affect the vascular level of nitric oxide (NO). Sequences in the 5'-flanking region of eNOS gene were PCR-amplified using genomic DNA templates isolated from blood samples collected from cardiovascular disease (CVD) patients. Two sequence-versions carrying the same SNP site were used; a short (345 bp) and an extended one (1,594 bp), numbered relative to the translational start site. All sequences were cloned into a promoter-less vector (pGL3-basic), which carries the firefly luciferase gene as a reporter. Genotyping of the T-786C polymorphism was performed using Sanger sequencing of the insert region. Luminescence levels were then recorded 24-48 h after transfecting human endothelial cell line (EA.hy926). Three genotypes were identified in the subject samples; TT, TC, or CC. The highest expression levels associated with the TT genotype, followed by the TC genotype, then the CC genotype. The extended sequence version produced higher expression levels compared to the shorter version. Our results provide evidence that the T allele at the T-786C SNP site of the eNOS gene results in increased expression of the enzyme, and consequently might provide a protective mechanism from CVD. The extended promoter sequence of eNOS resulted in higher expression of the gene, suggesting the presence of some essential binding sites for transcription enhancing proteins.

Effect of amino-acid intake on physical conditions and skin state: a randomized, double-blind, placebo-controlled, crossover trial

The objective of this study is to elucidate the effect of a supplement enriched with l-leucine, l-arginine, and l-glutamine on body compositions/skin conditions. Healthy young women (n = 29) were allocated to a group (n = 14) receiving an amino-acid supplement (600 mg l-leucine, 250 mg l-arginine, and 300 mg l-glutamine) and a placebo group (n = 15) receiving a supplement not-containing the amino acids. The amino-acid supplement and placebo were given twice/day for 6 weeks. After a wash-out (2 months) from the 1st test, the amino-acid group received the placebo and the placebo group the amino-acid supplement. The body compositions/skin conditions were measured 4 times (day 1 and weeks 2, 4, and 6) in each test. Percentage-change of muscle mass in the amino-acid group increased up to 4 weeks (p = 0.05) and was higher than that in the placebo group (p = 0.09). Skin texture estimated by the image processing of neck skin replica tended to increase in the amino-acid group at 6 weeks compared with that at 0 week, though there was no significant intergroup difference. In conclusion, the young adult women having no fitness habit showed the significant increase of the muscle amount and improvement tendency of the skin texture by the continuous intake of the amino-acid supplement.

AGXT2 and DDAH-1 genetic variants are highly correlated with serum ADMA and SDMA levels and with incidence of coronary artery disease in Egyptians

Dimethylarginine aminodehydrolase (DDAH1) and alanine glyoxylate aminotransferase2 (AGXT2) are two enzymes that contribute in asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) metabolism. Hence they affect production and bioavailability of eNOS-derived nitric oxide (NO) and consequently healthy blood vessels. The major aims of the current study were to investigate the association of genetic variants of AGXT2 rs37369, AGXT2 rs16899974 and DDAH1 rs997251 SNPs with incidence of coronary artery disease (CAD) in Egyptians and to correlate these variants with the serum levels of ADMA and SDMA. The study included 150 subjects; 100 CAD patients and 50 healthy controls. Genotyping was performed by qPCR while the ADMA and SDMA concentrations were assayed by ELISA. Both serum ADMA and SDMA concentrations were significantly higher in CAD patients compared to controls (both p < 0.0001). Genotype distributions for all studied SNPs were significantly different between CAD patients and controls. Carriers of AGXT2 rs37369-T allele (CT + TT genotypes) and AGXT2 rs16899974-A allele (CA + AA genotypes) had 2.4- and 2.08-fold higher risk of having CAD than CC genotype in both SNPs (p = 0.0050 and 0.0192, respectively). DDAH1 rs997251 TC + CC genotypes were associated with 2.3-fold higher risk of CAD than TT genotype (p = 0.0063). Moreover, the AGXT2 rs37369 TT and AGXT2 rs16899974 AA genotypes were associated with the highest serum ADMA and SDMA while DDAH1 rs997251 CC genotype was associated with the highest ADMA. AGXT2 rs37369-T, AGXT2 rs16899974-A, and DDAH1 rs997251-C alleles represent independent risk factors for CAD in the Egyptians.

Elevated Levels of Asymmetric Dimethylarginine (ADMA) in the Pericardial Fluid of Cardiac Patients Correlate with Cardiac Hypertrophy

Background

Pericardial fluid (PF) contains several biologically active substances, which may provide information regarding the cardiac conditions. Nitric oxide (NO) has been implicated in cardiac remodeling. We hypothesized that L-arginine (L-Arg) precursor of NO-synthase (NOS) and asymmetric dimethylarginine (ADMA), an inhibitor of NOS, are present in PF of cardiac patients and their altered levels may contribute to altered cardiac morphology.

Methods

L-Arg and ADMA concentrations in plasma and PF, and echocardiographic parameters of patients undergoing coronary artery bypass graft (CABG, n = 28) or valve replacement (VR, n = 25) were determined.

Results

We have found LV hypertrophy in 35.7% of CABG, and 80% of VR patients. In all groups, plasma and PF L-Arg levels were higher than that of ADMA. Plasma L-Arg level was higher in CABG than VR (75.7±4.6 μmol/L vs. 58.1±4.9 μmol/L, p = 0.011), whereas PF ADMA level was higher in VR than CABG (0.9±0.0 μmol/L vs. 0.7±0.0 μmol/L, p = 0.009). L-Arg/ADMA ratio was lower in the VR than CABG (VR_plasma: 76.1±6.6 vs. CABG_plasma: 125.4±10.7, p = 0.004; VR_PF: 81.7±4.8 vs. CABG_PF: 110.4±7.2, p = 0.009). There was a positive correlation between plasma L-Arg and ADMA in CABG (r = 0.539, p = 0.015); and plasma and PF L-Arg in CABG (r = 0.357, p = 0.031); and plasma and PF ADMA in VR (r = 0.529, p = 0.003); and PF L-Arg and ADMA in both CABG and VR (CABG: r = 0.468, p = 0.006; VR: r = 0.371, p = 0.034). The following echocardiographic parameters were higher in VR compared to CABG: interventricular septum (14.7±0.5 mm vs. 11.9±0.4 mm, p = 0.000); posterior wall thickness (12.6±0.3 mm vs. 11.5±0.2 mm, p = 0.000); left ventricular (LV) mass (318.6±23.5 g vs. 234.6±12.3 g, p = 0.007); right ventricular (RV) (33.9±0.9 cm² vs. 29.7±0.7 cm², p = 0.004); right atrial (18.6±1.0 cm² vs. 15.4±0.6 cm², p = 0.020); left atrial (19.8±1.0 cm² vs. 16.9±0.6 cm², p = 0.033) areas. There was a positive correlation between plasma ADMA and RV area (r = 0.453, p = 0.011); PF ADMA and end-diastolic (r = 0.434, p = 0.015) and systolic diameter of LV (r = 0.487, p = 0.007); and negative correlation between PF ADMA and LV ejection fraction (r = -0.445, p = 0.013) in VR.

Conclusion

We suggest that elevated levels of ADMA in the PF of patients indicate upregulated RAS and reduced bioavailability of NO, which can contribute to the development of cardiac hypertrophy and remodeling.

Levels of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, and risk of coronary artery disease: A meta-analysis based on 4713 participants

BACKGROUND

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide synthase by competing with L-arginine. As a result, the expression of nitric oxide decreases and endothelial dysfunction occurs. Studies have evaluated the association between the serum ADMA level and risk of coronary artery disease. However, conflicting results have been obtained.

METHODS

Pubmed, Web of Science, Embase, Ovid, Cochrane databases were searched to identify eligible studies published in English until December 2014. Association was assessed on the basis of weighted mean differences (WMD) with 95% confidence intervals (CIs). Publication bias was analysed using Begg's and Egger's tests. Sensitivity analysis was performed to evaluate result stability.

RESULTS

A total of 16 case-control studies with 2939 patients and 1774 controls were included in the meta-analysis. Pooled result indicated that patients with coronary artery disease yielded a higher ADMA level than healthy controls (WMD: 0.248, 95% CI: 0.156-0.340; p = 1.16 e-7). Sensitivity analysis suggested that our meta-analysis result was stable. Subgroup analysis found a similar pattern in patients with myocardial infarction (WMD: 0.397, 95% CI: 0.112-0.683; p = 0.0106), stable angina pectoris (WMD: 0.197, 95% CI: 0.031-0.364; p = 0.02) and unstable angina pectoris (WMD: 0.857, 95% CI: 0.293-1.420; p = 0.003).

CONCLUSIONS

Meta-analysis results indicated that an increased ADMA level is associated with an increased risk of coronary artery disease.

Association study of dimethylarginine dimethylaminohydrolase 2 gene polymorphisms and coronary heart disease

While a number of genetic and environmental risk factors for coronary heart disease (CHD) have been identified, the list of potential risk factors remains long. One candidate is dimethylarginine dimethylaminohydrolase (DDAH2), which is known to be polymorphic in humans. The gene product indirectly increases the endogenous production of nitric oxide, an anti-atherogenic molecule. Therefore, alterations in DDAH2 activity may indirectly result in an increased risk of CHD. We studied allele and genotype distributions for two polymorphic loci of DDAH2, rs805305 and rs2272592, in 180 patients with CHD and 180 healthy controls. Disease history and other clinical data were recorded. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine the genotype at rs805305, and ligase detection reaction (LDR) was used to determine the genotype at rs2272592. Systolic blood pressure and blood triglyceride and glucose levels were higher, and history of hypertension, diabetes, smoking and alcohol use was more common in the patients with CHD (P<0.05). However, the genotype and allele frequencies at the two polymorphic loci of DDAH2 were not statistically different between the two groups. Therefore, no association was observed between the DDAH2 polymorphisms at rs805305 and rs2272592 and CHD.

Changes in ADMA and TAFI levels after stenting in coronary artery disease patients

The aim of this study was to examine the contribution of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS) and a novel marker of vascular endothelial dysfunction, and thrombin-activatable fibrinolysis inhibitor (TAFI), a risk factor for venous thrombosis, to the predisposition of coronary restenosis following stent implantation in coronary artery disease (CAD) patients. Thirty-seven patients with CAD were recruited from the Kobry El Obba Military Hospital, Cairo, Egypt. The patients were hospitalized for coronary angiography and coronary stenting (CS). Overnight fasting blood samples were collected from patients prior to CS and four months later for the determination of plasma ADMA and TAFI levels. The patients underwent follow-up coronary angiography to reveal in-stent restenosis. The results showed that plasma ADMA levels in CAD patients were significantly higher than those reported for healthy subjects. ADMA levels were significantly increased by 30% in CAD patients four months following CS. CAD patients who developed in-stent restenosis had a 35% increase in ADMA levels following CS. TAFI levels were not significantly changed after CS in CAD patients or in any of the subgroups. In conclusion, ADMA, but not TAFI, is linked to the predisposition of in-stent restenosis following CS.

Cardiac biomarkers in acute myocardial infarction

Each year, a large number of patients are seen in the Emergency Department with presentations necessitating investigation for possible acute myocardial infarction. Patients can be stratified by symptoms, risk factors and electrocardiogram results but cardiac biomarkers also have a prime role both diagnostically and prognostically. This review summarizes both the history of cardiac biomarkers as well as currently available (established and novel) assays. Cardiac troponin, our current "gold standard" biomarker criterion for the diagnosis of myocardial infarction has high sensitivity and specificity for this diagnosis and therapies instituted in patients with elevated troponin have been shown to influence outcomes. Other markers of myocardial necrosis, inflammation and neurohormonal activity have also been shown to have either diagnostic or prognostic utility, but none have been shown to be superior to troponin. The measurement of multiple biomarkers and the use of point of care markers may accelerate current diagnostic protocols for the assessment of such patients.