eNOS Gene Affects Red Cell Deformability: Role of T-786C, G894T, and 4a/4b Polymorphisms

Nitric Oxide Synthase 3 Gene Polymorphisms and Their Association with Acute Myocardial Infarction and Chronic Stable Angina: A Case-Control Study from Northern India

Background

Coronary artery disease (CAD) that encompasses acute myocardial infarction (AMI), chronic stable angina (CSA), and unstable angina (UA) has numerous known risk factors. Genetic predispositions contribute as major risk in the development of CAD and the genes regulating atherosclerosis are important for disease prevention. Nitric oxide synthase 3 (NOS3) gene responsible for nitric oxide (NO) production is of special importance.

Aim

To evaluate the role of three NOS3 polymorphisms (-786C/T, 894G/T, and 4a4b) in patients with CAD, particularly in AMI and CSA and their comparison with healthy controls.

Materials and Methods

One hundred patients in each AMI and CSA group and 100 controls were included and were typed for three NOS3 polymorphisms (-786C/T, 894G/T, and 4a4b) by polymerase chain reaction-restriction fragment length polymorphism. Plasma NO metabolites (NOx) were also evaluated.

Results

A significant association of 894G/T polymorphism with AMI in dominant model (P = 0.052) and with CSA in dominant and codominant models was detected (P = 0.008 and P = 0.006, respectively). Plasma NO levels were found to be significantly higher (P < 0.0001) in healthy controls (43.80 ± 6.28) compared to AMI and CSA patients (37.05 ± 6.75 and 38.67 ± 5.61). No significant association of -786C/T and 4a4b polymorphism with AMI and CSA risk under recessive, dominant, and codominant models was detected.

Conclusion

Our study revealed a significant association of 894G/T polymorphism with AMI and independent association of NOx levels with CAD, indicating high risk of CAD in the North Indian population. Our findings will be helpful in identifying the genetic risk factors associated with CAD and better management of the diagnostic as well as therapeutic measures.

eNOS gene Glu298Asp variant confer risk in sudden sensorineural hearing loss

BACKGROUND

Sudden sensorineural hearing loss (SSNHL) causes the loss of hearing of 30 dB or greater on at least three contiguous frequencies. It is known to be a multifactorial disease which the exact cause is unknown, rendering it as an idiopathic disorder of patients.

AIMS/OBJECTIVES

This study aims to shed further light on pathogenesis of this disease by studying the association between eNOS gene Glu298Asp polymorphism and VDR gene FokI polymorphism with SSNHL in Iranian population.

MATERIAL AND METHODS

This study involves a total of 77 cases and 100 controls, with patients inflicted with SSNHL categorized in case group and healthy subjects as control group. Genotyping of the VDR and eNOS genes was conducted by the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Our results showed a statistically significant association between genotype frequencies of eNOS gene Glu298Asp polymorphism in case group compared to healthy individuals in the control group (p = .01). Also, TT genotype was significantly the most prevalent genotype in case group in comparison to control group (TT vs GT + GG, OR = 3.5; 95% CI = 1.18-11.79). On the other hand, analysis of VDR gene FokI polymorphism frequencies showed no statistically significant association with SSNHL.

CONCLUSIONS AND SIGNIFICANCE

Our findings showed a significant association between the eNOS gene Glu298Asp polymorphism and SSNHL in the Iranian population; and "TT" genotype might be considered as a risk factor for SSNHL.

Randomized trial of inhaled nitric oxide to treat acute pulmonary embolism: The iNOPE trial

BACKGROUND

The study hypothesis is that administration of inhaled nitric oxide (NO) plus oxygen to subjects with submassive pulmonary embolism (PE) will improve right ventricular (RV) systolic function and reduce RV strain and necrosis, while improving patient dyspnea, more than treatment with oxygen alone.

METHODS

This article describes the rationale and protocol for a registered (NCT01939301), nearly completed phase II, 3-center, randomized, double-blind, controlled trial. Eligible patients have pulmonary imaging-proven acute PE. Subjects must be normotensive, and have RV dysfunction on echocardiography or elevated troponin or brain natriuretic peptide and no fibrinolytics. Subjects receive NO plus oxygen or placebo for 24 hours (±3 hours) with blood sampling before and after treatment, and mandatory echocardiography and high-sensitivity troponin posttreatment to assess the composite primary end point. The sample size of N=78 was predicated on 30% more NO-treated patients having a normal high-sensitivity troponin (<14 pg/mL) and a normal RV on echocardiography at 24 hours with α=.05 and β=.20. Safety was ensured by continuous spectrophotometric monitoring of percentage of methemoglobinemia and a predefined protocol to respond to emergent changes in condition. Blinding was ensured by identical tanks, software, and physical shielding of the device display and query of the clinical care team to assess blinding efficacy.

RESULTS

We have enrolled 78 patients over a 31-month period. No patient has been withdrawn as a result of a safety concern, and no patient has had a serious adverse event related to NO.

CONCLUSIONS

We present methods and a protocol for the first double-blinded, randomized trial of inhaled NO to treat PE.

Nitric oxide, vasodilation and the red blood cell

Since the identification of the elusive endothelium-derived relaxing factor as nitric oxide (NO), much attention has been devoted to understanding its physiological effects. NO is a free radical with many roles, and owing to its neutral charge and high diffusion capacity, it appears NO is involved in every mammalian biological system. Most attention has been focused on the NO generating pathways within the endothelium; however, the recent discovery of a NO synthase (NOS)-like enzyme residing in red blood cells (RBC) has increased our understanding of the blood flow and oxygen delivery modulation by RBC. In the present review, pathways of NO generation are summarized, with attention to those residing within RBC. While the bioactivity of RBC-derived NO is still debated due to its generation within proximity of NO scavengers, current theories for NO export from RBC are explored, which are supported by recent findings demonstrating an extracellular response to RBC-derived NO. The importance of NO in the active regulation of RBC deformability is discussed in the context of the subsequent effects on blood fluidity, and the complex interplay between blood rheology and NO are summarized. This review provides a summary of recent advances in understanding the role played by RBC in NO equilibrium and vascular regulation.

Candidate genes of cerebrovascular disease and sudden sensorineural hearing loss

Auditory dysfunction is related to large/small vessel occlusions and hemorrhage. Sudden sensorineural hearing loss (SSNHL) frequently occurs with anterior inferior cerebellar artery occlusion proximal to the internal auditory artery. Moreover, SSNHL has various pathogenetic mechanisms, the main proposed mechanisms being vascular disease, membrane ruptures, infection, and autoimmunity. Tumor necrosis factor (TNF) is an important cytokine in the inflammation process of cerebrovascular diseases. In the current study, the possible effects of polymorphisms in TNF-alpha and TNF-beta genes on SSNHL are evaluated. Two genetic polymorphisms in the TNF locus (TNF-alpha -308 G - ->A and TNF-beta +252 A - ->G) were investigated as risk factors for SSNHL by determining their prevalence in 97 SSNHL patients and in 587 controls. A significant increase was found for the TNF-beta allele 1 in SSNHL patients compared with the controls (chi( 2) = 7.251, P = .007, odds ratio [OR] = 1.534, confidence interval [CI] = 1.12-2.10). These findings suggest that the TNF-beta +252 locus plays an important role in the etiopathogenesis of SSNHL.

eNOS T-786C polymorphism affects atorvastatin-induced changes in erythrocyte membrane fluidity

PURPOSE

Statins have pleiotropic effects, including endothelial nitric oxide synthase (eNOS) upregulation and increased nitric oxide formation, which can be modulated by a genetic polymorphism in the promoter region of the eNOS gene (T-786C). Here, we report our investigation of whether this polymorphism modulates the effects of atorvastatin on the fluidity of erythrocyte membranes.

METHODS

We genotyped 200 healthy subjects (males, 18-60 years of age) and then randomly selected 15 of these with the TT genotype and 15 with the CC genotype to receive placebo or atorvastatin (10 mg/day oral administration) for 14 days. Cell membrane fluidity was evaluated by electron paramagnetic resonance (EPR) and spin-labeling method. The EPR spectra were registered on a VARIAN-E4 spectrometer. Thiobarbituric acid-reactive species (TBA-RS) and plasma membrane cholesterol were determined in the erythrocytes.

RESULTS

Atorvastatin reduced membrane fluidity in CC subjects (P < 0.05) but not in those with the TT genotype (P > 0.05). While no significant differences were found in plasma membrane cholesterol concentrations, higher TBA-RS concentrations were found in the CC subjects than in the TT subjects (P < 0.05).

CONCLUSIONS

These findings suggest that a short treatment with atorvastatin is disadvantageous to subjects with the CC genotype for the T-786C polymorphism compared to those with TT genotype, at least in terms of the hemorheological properties of erythrocytes.

Hemorheologic profile in systemic sclerosis: role of NOS3 -786T > C and 894G >T polymorphisms in modulating both the hemorheologic parameters and the susceptibility to the disease

OBJECTIVE

Microvascular disorders are relevant in systemic sclerosis (SSc). Hyperviscosity, due to alterations of blood cells and plasma components, may play a role in the pathogenesis of microcirculatory disorders. An impaired availability of nitric oxide, related to polymorphisms in NOS3, the gene for endothelial cell nitric oxide synthase, might influence erythrocyte deformability. We undertook this study to investigate the hemorheologic profile in SSc and the role of NOS3 polymorphisms in modulating the hemorheologic status of SSc patients.

METHODS

We studied 113 consecutive SSc patients (75 with limited cutaneous SSc [lcSSc] and 38 with diffuse cutaneous SSc [dcSSc]) and 113 healthy controls. The hemorheologic profile was obtained by assessing whole blood viscosity (WBV; at shear rates of 0.512 and 94.5 seconds(-1)), plasma viscosity (PLV; at a shear rate of 94.5 seconds(-1)), and erythrocyte deformability index (DI). We determined NOS3 polymorphisms by molecular analysis.

RESULTS

A marked alteration of hemorheologic parameters was found both in patients with lcSSc and in those with dcSSc compared with controls (P < 0.0001). In multivariate analysis, rheologic variables were significantly associated with the disease (for WBV at a shear rate of 94.5 seconds(-1), odds ratio [OR] 5.4, 95% confidence interval [95% CI] 1.4-19.9, P = 0.01; for PLV, OR 2.8, 95% CI 1.2-6.5, P = 0.01; for DI, OR 3.9, 95% CI 1.4-10.8, P = 0.007), and NOS3 -786C and 894T alleles significantly affected the DI (for -786C allele, OR 2.3, 95% CI 1.01-5.4, P = 0.04; for 894T allele, OR 2.2, 95% CI 1.01-4.8, P = 0.04). The simultaneous presence of the -786C and 894T alleles represented a susceptibility factor for SSc (OR 2.8, 95% CI 1.4-5.7, P = 0.004).

CONCLUSION

Our findings document an altered rheologic profile in SSc and demonstrate a relationship between this alteration and NOS3 polymorphisms, thus shedding light on a potential novel mechanism influencing the microcirculation in this disease.

Hyperviscosity as a possible risk factor for cerebral ischemic complications in atrial fibrillation patients

Recent studies have suggested that hyperviscosity is frequent in patients with atrial fibrillation (AF). The aims of this study were to evaluate if hemorheologic alterations play a role in the occurrence of cerebral ischemic events in patients with AF and to explore a possible association between inflammation and hyperviscosity in these patients. Sixty-two patients with AF with a history of >or=1 cerebral ischemic event and 94 patients with AF without cerebral ischemic events were studied. A control population included 130 age- and gender-matched healthy volunteers. Hemorheologic variables (whole-blood viscosity, plasma viscosity, the erythrocyte deformability index, and hematocrit), fibrinogen, and high-sensitivity C-reactive protein levels were assayed. An alteration in whole blood viscosity at 94.5 seconds(-1) and the erythrocyte deformability index were found more frequently in patients with previous ischemic events on univariate and multivariate analyses (odds ratio 3.19, p=0.023 and odds ratio 4.26, p=0.002, respectively) adjusted for age, gender, hypertension, diabetes, history of coronary artery disease, left ventricular dysfunction, smoking habit, dyslipidemia, hematocrit, fibrinogen, high-sensitivity C-reactive protein, and hemorheologic parameters. These results should stimulate prospective studies on the role of hemorheologic alterations in the occurrence of cerebral ischemic complications in patients with AF.