The Functional Consequence of the Glu298Asp Polymorphism of the Endothelial Nitric Oxide Synthase Gene in Young Healthy Volunteers

Relation of nitric oxide synthase gene (NOS3) polymorphisms to varicocele risk and post-varicocelectomy seminal oxidative stress reduction

The pathophysiology of varicocele remains to be unknown. Several genetic factors have been implicated in varicocele etiopathogenesis. We studied the relationship between NOS3 c.894G>T, c.786T>C and 4b/a polymorphisms to varicocele risk and their prognostic value as regards improvement of the post-operative seminal parameters &/or seminal malonaldehyde levels. The three NOS3 polymorphisms were evaluated in 100 patients with varicocele and 100 healthy subjects by RT-PCR. Seminal plasma MDA level was measured pre-operatively and 3 months after varicocelectomy by the thiobarbituric acid method. The GT, TT, TC and bb genotypes of NOS3 polymorphism were more commonly observed in varicocele patients (30%, 9%, 28% and 70% respectively) compared to normal controls (12%, 0%, 10% and 50% respectively). The mean percentage of post-varicocelectomy seminal MDA reduction was highest with the GT genotype (p < .001). Genotypes GT+TT, TC and bb were associated with varicocele occurrence in our patients. The T (c.894G>T), C (c.786T>C) and b (NOS3 intron 4 VNTR) alleles were significantly associated with varicocele occurrence in our cohort of patients. We also report a better response regarding the reduction of seminal MDA after varicocelectomy with the GT and ba genotypes.

Association of endothelial nitric oxide synthase (NOS3) gene polymorphisms with primary open-angle glaucoma in a Saudi cohort

Aim

To investigate the association of endothelial nitric oxide synthase (NOS3) gene polymorphisms in patients with primary open-angle glaucoma (POAG) of Saudi origin.

Methods

This case-control study included 173 patients with POAG (94 men and 79 women) and 171 controls (98 men and 73 women). Genotyping of rs2070744 (T-786C) and rs1799983 (G894T) variants of the NOS3 gene was performed using TaqMan^® assay.

Results

Rs1799983 genotypes showed a significant association with POAG but did not survive Bonferroni correction (p_correction = 0.01). The minor ‘T’ allele was significantly associated with the risk of POAG among men (p = 0.025, odds ratio (OR) = 1.77, 95% confidence interval (CI) = 1.07–2.94). Likewise, the genotypes were significantly associated with POAG among men in dominant (p = 0.030, OR = 1.92, 95% CI = 1.06–3.48) and log-additive models (p = 0.022, OR = 1.82, 95% CI = 1.08–3.07), and after adjustment for age and smoking. Genotype and allele frequencies of rs2070744 were not significantly different between POAG cases and controls, and after sex stratification. CG haplotype was significantly protective (p = 0.011, OR = 0.52, 95% CI = 0.32–0.87) and CT haplotype conferred significantly increased risk of POAG (p = 0.016, OR = 2.60, 95% CI = 1.16–5.82) among men. Rs1799983 showed trend (p = 0.054) towards risk of POAG independent of age, gender, smoking, and rs2070744 polymorphism in logistic regression analysis. Both the polymorphisms showed no association with POAG phenotypes such as intraocular pressure and cup/disc ratio.

Conclusion

Our results suggest that the polymorphism rs1799983 and the haplotypes of rs20707440 and rs1799983 in the NOS3 gene may significantly modulate the risk of POAG in Saudi’s, particularly among men. Further larger studies are needed to confirm these findings.

Endothelial nitric oxide synthase c.-813C>T predicts for proteinuria in metastatic breast cancer patients treated with bevacizumab-based chemotherapy

PURPOSE

To investigate the association between single nucleotide polymorphisms (SNPs) in endothelial nitric oxide synthase (eNOS) and interleukin-8 (IL-8) genes and risk of developing bevacizumab-related adverse events in metastatic breast cancer (mBC) patients.

PATIENTS AND METHODS

mBC patients candidate to receive bevacizumab-based chemotherapy were enrolled in this pharmacogenetic study. eNOS c.-813C>T and c.894G>T, and IL-8 c.-251A>T were analyzed by real time PCR on genomic DNA extracted from peripheral blood. Univariate analysis was performed to test the association between each SNP and treatment-related toxicities.

RESULTS

Seventy-six mBC patients were enrolled in the present study. Patients carrying the homozygous variant eNOS c.-813TT genotype showed a statistically significant occurrence of any grade proteinuria when compared to CT or CC genotypes (p = 0.004). No significant association of proteinuria with IL-8 SNP or hypertension with selected eNOS and IL-8 SNPs was found.

CONCLUSIONS

These findings suggest an association between the eNOS c.-813C>T polymorphism and the development of proteinuria in mBC patients receiving a bevacizumab-based chemotherapy.

Pharmacogenetic Implications of eNOS Polymorphisms (Glu298Asp, T786C, 4b/4a) in Cardiovascular Drug Therapy

Endothelial nitric oxide synthase (NOS3 or eNOS) is the enzyme responsible for the highest production of nitric oxide, with the greatest impact on the cardiovascular system, encoded by the eNOS gene, which presents various polymorphisms. ENOS gene polymorphisms play an important role in the response to drugs affecting nitric oxide (NO) signaling. This review discusses the pharmacogenetic impact of eNOS polymorphisms on the response to drugs affecting NO activity: angiotensin converting enzyme inhibitors, angiotensin II receptor antagonists, calcium blockers, beta-blockers, diuretics, phosphodiesterase inhibitors, and statins. The identification of biomarkers that accurately predict particular phenotypes is a challenge that needs additional large studies, in different populations. Efforts should be oriented towards a more accurate evaluation of the effects of eNOS genetic variants on biochemical parameters reflecting eNOS gene expression and enzymatic activity, in different diseases, as well as following drug treatment. This approach will allow for a better understanding of the role of eNOS genetic variants in cardiovascular disease progression and for cardiovascular drug therapy optimization.

Maternal/fetal eNOS-Glu298Asp genotypes and their influence on the severity, prognosis, and lipid profile of preeclampsia

OBJECTIVES

To analyze the contribution of maternal eNOS-Glu298Asp genotypes and also the association with fetal genotypes to the development of preeclampsia, prognosis, and maternal dyslipidemia.

METHODS

Sixty-nine pairs of preeclamptic mothers/newborns and 94 pairs of normotensive mothers/newborns were genotyped for eNOS-Glu298Asp using PCR-RFLP methods.

RESULTS

Women carriers of at least one Asp298 allele had a 1.53-fold (p = NS), 1.88-fold (p = NS), and 2.08-fold (p = .05), respectively, increased risk to develop PIH, mild, or severe preeclampsia. If both the mother and the newborn were carriers of the Asp298 allele, the risk for preeclampsia was 5.09-fold higher (p < .001). Preeclamptic women with severe preeclampsia had significantly higher cholesterol (mg/dl, 287.23 ± 43.01 versus 235.36 ± 45.01, p = .02) and LDL (mg/dl, 194.9 ± 42.8 versus 144.98 ± 54.84, p = .04) levels and lower HDL levels (mg/dl, 32.12 ± 5.48 versus 57.84 ± 20.59, p = .02) compared to noncarriers. Also, higher LDL levels (mg/dl, 188.76 ± 46.61 versus 136.75 ± 41.85, p = .03) and lower HDL levels (mg/dl, 32.8 ± 5.64 versus 61.06 ± 22.45, p = .02) were found in preeclamptic women with severe preeclampsia whose newborns were carriers of the Asp298 allele.

CONCLUSIONS

The eNOS-Glu298Asp variant (in mothers and newborns) in association with dyslipidemia could affect bioavailability of NO and could represent an increased risk for preeclampsia.

Association of Common Variants in eNOS Gene with Primary Open Angle Glaucoma: A Meta-Analysis

Purpose. To clarify the association of endothelial nitric oxide synthase (eNOS) polymorphisms and primary open angle glaucoma (POAG). Methods. After a systematic literature search in the MEDLINE, EMBASE, and ISI Web of Science databases, all relevant studies evaluating the association between the polymorphisms (rs2070744 and rs1799983) of eNOS gene and POAG were screened and included. The pooled odds ratios (ORs) and the 95% confidence interval (CI) of each single-nucleotide polymorphism (SNP) in five genetic models were estimated using fixed-effect model if I (2) < 50% in the test for heterogeneity; otherwise the random-effects model was used. Results. Thirty-one records were obtained, with five being suitable for meta-analysis. The overall results showed that both TT genotype in rs2070744 and GG genotype in rs1799983 are associated with decreased risk of POAG susceptibility. Stratified analysis based on ethnicity showed that the association of rs2070744 with POAG remained only in Caucasians. Results of subgroup analysis by sex indicated association between both polymorphisms and POAG in female group, but not in male group. Conclusions. TT genotype and/or T-allele in rs2070744, as well as GG genotype and/or G-allele in rs1799983, was associated with decreased risk for POAG overall and in female group.

Endothelial nitric oxide synthase: From biochemistry and gene structure to clinical implications of NOS3 polymorphisms

Nitric oxide (NO) is an important vasodilator with a well-established role in cardiovascular homeostasis. While mediator is synthesized from L-arginine by neuronal, endothelial, and inducible nitric oxide synthases (NOS1,NOS3 and NOS2 respectively), NOS3 is the most important isoform for NO formation in the cardiovascular system. NOS3 is a dimeric enzyme whose expression and activity are regulated at transcriptional, posttranscriptional,and posttranslational levels. The NOS3 gene, which encodes NOS3, exhibits a number of polymorphic sites including single nucleotide polymorphisms (SNPs), variable number of tandem repeats (VNTRs), microsatellites, and insertions/deletions. Some NOS3 polymorphisms show functional effects on NOS3 expression or activity, thereby affecting NO formation. Interestingly, many studies have evaluated the effects of functional NOS3 polymorphisms on disease susceptibility and drug responses. Moreover, some studies have investigated how NOS3 haplotypes may impact endogenous NO formation and disease susceptibility. In this article,we carried out a comprehensive review to provide a basic understanding of biochemical mechanisms involved in NOS3 regulation and how genetic variations in NOS3 may translate into relevant clinical and pharmacogenetic implications.

Associations of the eNOS G894T gene polymorphism with target organ damage in children with newly diagnosed primary hypertension

BACKGROUND

The endothelial nitric oxide synthase (eNOS) G894T gene polymorphism is associated with the risk of primary hypertension (PH) and vascular complications in adults with PH.

METHODS

We explored the associations of the G894T polymorphism with 24-h ambulatory blood pressure, left ventricular mass (LVM), carotid intima media thickness (cIMT), urinary albumin excretion, oxidative stress and inflammatory parameters in 126 children with newly diagnosed PH and in 83 healthy children.

RESULTS

Among the 126 children with PH 92 (73%) had ambulatory hypertension and 34 (27%) had severe ambulatory hypertension. Left ventricular hypertrophy (LVH) was detected in 39 (31%) patients, cIMT of >2 standard deviation scores in 21 (16.6%) patients, albuminuria of >30 mg/24 h in 18 (14.3%) patients and metabolic syndrome (MS) in 22 (17.5%) patients. The frequency of the T allele was 52.4% in the PH group and 54.2% in the control group (not significant), and in both groups the frequency of the T allele was consistent with the Hardy-Weinberg equilibrium. Compared with G allele carriers, hypertensive T allele carriers had increased cIMT (p < 0.05) and more severe albuminuria (not significant, p = 0.1); there was no difference between the groups in hypertension severity and LVM. T and G allele distribution did not differ between patients with and without metabolic syndrome. No significant correlations between the assessed parameters and the eNOS G894T gene polymorphism were found in the controls, although T allele carriers tended to have an increased cIMT (p = 0.09).

CONCLUSION

The eNOS T allele is not more prevalent among hypertensive children than among healthy ones, but it is associated with early vascular damage in children with PH, independent of metabolic abnormalities. No associations between the eNOS G894T polymorphism and metabolic abnormalities were found.

Analysis of nitric oxide synthase gene polymorphisms in neonatal respiratory distress syndrome among the Chinese Han population

AIM

To evaluate the association of NOS1 and NOS3 gene polymorphisms with the risk/severity of neonatal respiratory distress syndrome (RDS) among preterm infants.

METHODS

The patient group was 189 preterm infants diagnosed with RDS. The control group was 227 preterm neonates who did not develop RDS. NOS genotyping was performed using an improved multiplex ligation detection reaction (iMLDR) technique based on LDR.

RESULTS

It was found that genotype and allele frequencies of rs2682826 of the NOS1 gene and rs1799983 of the NOS3 gene were not significantly different between the RDS group and the control group. However, when the preterm infants were divided into two and three groups based on gestational age and birth weight, a study of the SNP rs1799983 of the NOS3 gene showed that the GG genotype and G allele frequencies were significantly increased in the RDS groups, the GT genotype and A allele were less frequent among the RDS groups in 26-32.9 weeks of gestational age and in a birth weight subgroup of <1.5 Kg.

CONCLUSION

Our study raises the possibility that a genetic variation of NOS3 could be implicated in the pathophysiology of RDS in the Chinese Han population, especially in very preterm and very low birth weight infants.

Endothelial NOS gene Glu298Asp polymorphism in preterm neonates with respiratory distress syndrome

RATIONALE

Respiratory Distress Syndrome (RDS) due to prematurity is one of the most important causes of morbidity and mortality in Neonatal Intensive Care Units. According to few studies in recent years, endothelial nitric oxide synthase (eNOS) gene polymorphisms are found to be partially responsible for liability to RDS. The purpose of this study was to determine the association between eNOS gene polymorphism and RDS in preterm neonates.

PATIENTS AND METHODS

The patient group consisted of 152 premature neonates born before 37 weeks of gestation and diagnosed as RDS. The control group consisted of 125 premature neonates born before 37 weeks of gestation, but was not diagnosed as RDS. Genomic DNA from patients and controls was analyzed by polymerase chain reaction.

RESULTS

It was found that Glu/Glu, Glu/Asp, and Asp/Asp genotype frequencies of the eNOS gene polymorphism were 35.2%, 59.2%, and 5.6% of the control group, and 32.9%, 65.1%, and 2.0% of the patient group, respectively (P > 0.05). However, significant increases in Glu/Glu genotype and Glu allele frequencies were noted in the RDS groups when the preterm neonates were divided into two groups (24-30 weeks and 31-36 weeks) by gestational age. Additionally, Glu/Asp genotype and Asp allele were markedly less frequent among the RDS groups (P < 0.05). Asp allele frequency in boys and Glu allele frequency in girls were significantly high in RDS group (P < 0.05).

CONCLUSIONS

These data suggest that there were significant gestational age-related differences between RDS and control groups in terms of Glu298Asp polymorphism. Therefore, RDS seems to develop with alterations in eNOS Glu298Asp genotype frequencies in the Turkish population.

Effect of eNOS polymorphisms on salbutamol evoked endothelium dependent vasodilation in South Indian healthy subjects

BACKGROUND

The model of pulse plethysmograph using inhalational salbutamol 400 mcg is studied well to assess endothelium dependent vasodilation. Endothelial nitric oxide synthase (eNOS) gene polymorphism may influence the response to salbutamol in healthy subjects.

AIM

To find the effect of polymorphisms 894G>T and -786T>C of eNOS gene on endothelium dependent vasodilation in healthy subjects.

MATERIALS AND METHODS

One hundred and two south Indian healthy subjects of either sex, aged between 18 to 35 years were recruited for the study. The digital volume pulse (DVP)was measured by pulse plethysmograph before and after salbutamol 400mcg inhalation. Three predose and five postdose recordings of DVP were measured. The average change in the DVP parameters namely reflection index (RI) and stiffness index (SI) were determined. The eNOS894G>T and -786T>C gene polymorphism were genotyped using polymerase chain reaction followed by restriction fragment length polymorphism. The percentage changes in RI and SI from predose baseline recordings were calculated and compared between the genotype groups.

RESULTS

The genotype and allele frequency of study subjects were in Hardy-Weinberg equilibrium. The changes in DVP parameters were not significantly different between the genotype groups.

CONCLUSION

eNOS polymorphism do not affect salbutamol evoked endothelium dependent vasodilation in the model of pulse plethysmograph in healthy subjects.

Effects of polymorphisms of NOS3 and GNB3 genes on skin microvascular reactivity in normal pregnancy

We studied the relationship between endothelial NO-synthase gene (NOS3) and G protein β3 subunit gene (GNB3) polymorphisms and reactivity of skin microvessels during physiological gestation. T-786C NOS3 polymorphism influenced the maximum blood flow rate in skin microvessels and the severity of postocclusive reactive hyperemia during the third trimester of pregnancy. The relationship between G894T NOS3 polymorphism and the duration of postocclusive reactive hyperemia was revealed. C825T GNB3 polymorphism affects the duration and severity of postocclusive reactive hyperemia during the first and third trimesters of pregnancy. Thus, NOS3 and GNB3 polymorphisms affect blood flow in the skin microvessels during physiological gestation.

Endothelial nitric oxide synthase gene polymorphisms and renal responsiveness to RAS inhibition therapy in type 2 diabetic Asian Indians

AIM

To investigate the association of functional single nucleotide polymorphisms (SNPs) of the endothelial nitric oxide synthase gene (eNOS) gene (T-786C, G894T) and one variable number tandem repeat polymorphism (aa 27VNTR bb) with reno-protective response to angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) therapy in North Indian type 2 diabetic mellitus (T2DM) subjects with cases having diabetic nephropathy (DN) and controls without DN.

METHOD

We genotyped three polymorphisms of eNOS (two SNPs: T-786C, G894T and one 27 VNTR) in T2DM patients with overt nephropathy (cases: n=320) and T2DM patients without overt nephropathy (controls: n=490), using validated PCR-RFLP assays. These 810 North Indian T2DM patients treated with ACEI or ARB after diagnosis were followed up for 3 years. Percent changes in eGFR, urinary albumin excretion (UAE), serum creatinine at the end of 3 years of treatment were taken as end points of renoprotective response.

RESULT

We observed that in normoalbuminuric patients, eNOS -786 CC genotype and haplotypes C-b-G and C-b-T were associated with lesser renoprotective response to ACEI. While, in macroalbuminurics, eNOS -786 CC genotype, haplotypes C-b-G and C-b-T and 27VNTR aa were associated with better renoprotective response to ACEI/ARB.

CONCLUSION

Our results showed that eNOS T-786C CC genotype and 27VNTR individually and in interaction with other eNOS SNPs modulate renoprotective efficacy of ACEI and ARB in T2DM patients, depending on the status of proteinuria.

Association between Glu298Asp/677C-T single nucleotide polymorphism in the eNOS/MTHRF gene and blood stasis syndrome of ischemic stroke

Blood stasis syndrome of ischemic stroke (BSS-IS) is a common clinical phenotype that may be affected by certain mutagenic environmental factors or chemotherapeutic drugs; however, the role of susceptibility genes remains unclear. Previous studies have shown that ischemic stroke (IS) was closely associated with the Glu298Asp polymorphism in the eNOS gene and the 677C-T (Ala→Val) polymorphism in methylenetetrahydrofolate reductase (MTHRF) gene. Therefore, these two single nucleotide polymorphisms (SNPs) were selected to detect their associations with BSS-IS in this study. A SNP chip was employed to screen the SNP variation between both groups, and the results were verified using denaturing high-performance liquid chromatography (DHPLC) and restriction fragment length polymorphism (RFLP). The results confirmed that the TT genotype of Glu298Asp in the eNOS gene may be one of the risk factors associated with BSS-IS, while the genotype of 677C-T (Ala→Val) in the MTHRF gene may not be relevant to BSS-IS.

eNOS [Glu298Asp] polymorphism, erectile function and ocular pressure in type 2 diabetes

BACKGROUND

  Imbalance in nitric oxide (NO), an atheroprotective vasodilator, is associated with endothelial dysfunction, cardiovascular diseases (CVD) and diabetic complications. Various endothelial NO synthase (eNOS) polymorphisms may affect NO bioavailability, thereby promoting adverse cardiovascular milieu.

MATERIALS AND METHODS

  To analyze glucose homeostasis, cardiometabolic phenotype, and micro- and macroangiopathies associated with eNOS G894T gene polymorphism in type 2 diabetes (T2DM). 210 T2DM outpatients (mean age (1SD) 70 (12); diabetes duration 19 (9) years; males:females 64:36%; metabolic syndrome 87%) had insulin sensitivity and b-cell function modelled with HOMA, alongside routine laboratory and endothelin measurements.

RESULTS

  GG, GT and TT genotypes represented 48% (n = 100), 39% (n = 83) and 13% (n = 27). Overall microangiopathy (retinopathy, neuropathy and/or nephropathy) was present in 74%, and overall macroangiopathy (CAD, PAD and/or TIA/stroke) in 45%. The TT genotype did not translate into a more severe vascular phenotype, as TT patients carrying the proposed risk genotype did not suffer a higher rate of micro- and macrovascular complications. On the other hand, erectile dysfunction, present in 60% of males (n = 135), was much more prevalent in TT males: 57% [GG & GT] vs. 93% in TT (p 0.0088). Ocular hypertension/glaucoma frequency (18% of the whole group) was also markedly different, albeit in opposing directions, between eNOS G894T gene polymorphism subgroups: 21% [GG & GT] vs. 0% prevalence (TT; p 0.0057).

CONCLUSIONS

  eNOS G894T gene polymorphism in homozygous TT carriers translates into opposing effects on erectile function (detrimental) and ocular hypertension/glaucoma (protective) in T2DM, without affecting glucose homeostasis determinants or the presence of micro- and macrovascular complications.

The Glu298Asp single nucleotide polymorphism in the endothelial nitric oxide synthase gene differentially affects the vascular response to acute consumption of fruit and vegetable puree based drinks

SCOPE

Diets low in fruits and vegetables (FV) are responsible for 2.7 million deaths from cardiovascular diseases (CVD) and certain cancers annually. Many FV and their juices contain flavonoids, some of which increase endothelial nitric oxide synthase (eNOS) activity. A single nucleotide polymorphism in the eNOS gene, where thymine (T) replaces guanine (G) at position 894 predicting substitution of glutamate for aspartate at codon 298 (Glu298Asp), has been associated with increased CVD risk due to effects on nitric oxide synthesis and subsequently vascular reactivity. Individuals can be homozygous for guanine (GG), thymine (TT) or heterozygous (GT).

METHODS AND RESULTS

We investigated the effects of acute ingestion of a FV-puree-based-drink (FVPD) on vasodilation and antioxidant status in subjects retrospectively genotyped for this polymorphism. Healthy volunteers (n = 24; 11 GG, 11 GT, 2 TT) aged 30-70 were recruited to a randomized, controlled, crossover, acute study. We showed that acute consumption of 400 mL FVPD differentially affected individuals depending on their genotype. There was a significant genotype interaction for endothelium-dependent vasodilation measured by laser Doppler imaging with iontophoresis (P < 0.05) and ex vivo low-density lipoproteins (LDL) oxidation (P = 0.002). GG subjects had increased endothelium-dependent vasodilation 180 min (P = 0.028) and reduced ex vivo LDL oxidation (P = 0.013) after 60 min after FVPD compared with control, no differences were observed in GT subjects.

CONCLUSION

eNOS Glu298Asp genotype differentially affects vasodilation and ex vivo LDL oxidation after consumption of FV in the form of a puree-based drink.

Association of polymorphisms of endothelial nitric oxide synthase (eNOS) gene with the risk of primary open angle glaucoma in a Brazilian population

The present study aimed to investigate the association of endothelial nitric oxide synthase (eNOS) gene polymorphisms with primary open angle glaucoma (POAG). We conducted a case-control study that included 90 patients with POAG and 127 healthy controls whose blood samples were genotyped for the functional polymorphisms T-786C and Glu298Asp of the eNOS gene by Taqman fluorescent allelic discrimination assay. The T-786C polymorphism was significantly associated as a risk factor for POAG among women (OR: 2.28; 95% CI: 1.11 to 4.70, p=0.024) and marginally associated to the risk of POAG in the patients ≥52 years of age at diagnosis (OR: 2.11; 95% CI: 0.98 to 4.55, p=0,055). However, these results was not confirmed after adjustments for gender, age, self-declared skin color, tobacco smoking and eNOS genotypes by multivariate logistic regression model (OR: 2.08; 95% CI: 0.87 to 5.01, p=0.101 and OR: 2.20; 95% CI: 0.95 to 5.12, p=0.067, respectively). The haplotype CG of T-786C and Glu298Asp showed a borderline association with risk of POAG in the overall analysis (OR: 1.76; 95% CI: 0.98 to 3.14, p=0.055) and among women (OR: 2.02; 95% CI: 0.98 to 4.16, p=0.052). Furthermore, the CG haplotype was significantly associated with the development of POAG for the age at diagnosis group ≥52 years (OR: 3.48; 95% CI: 1.54 to 7.84, p=0.002).We suggested that haplotypes of the polymorphisms T-786C and Glu298Asp of eNOS may interact with gender and age in modulating the risk of POAG.

Endothelial nitric oxide synthase gene polymorphism (Glu298Asp) and acute pulmonary hypertension post cardiopulmonary bypass in children with congenital cardiac diseases

BACKGROUND

Intra-cardiac repair of congenital cardiac diseases in children with left-right shunt is often associated with acute elevation of pulmonary artery pressure following cardiopulmonary bypass. We studied the correlation between the Glu298Asp polymorphism of the endothelial nitric oxide synthase gene and pulmonary hypertension in children with congenital cardiac diseases.

METHODS AND RESULTS

A total of 80 children with congenital cardiac diseases at a median age of 3.8 years, ranged 0.1-36.2 years, and 136 controls were enrolled. Most patients presented with significant left-to-right shunt - pulmonary-to-systemic blood flow of 2.8, with a range from 0.6 to 7.5. In all, 40 out of 80 children showed pulmonary hypertension with mean pressure of 42, ranged 26-82, millimetres of mercury. Thirty-one out of 40 children underwent intra-cardiac repair and 15 out of 31 operated patients were found to have an acute elevation of pulmonary artery pressure after cardiopulmonary bypass. The Glu298Asp polymorphism was identified using polymerase chain reaction and restriction fragment length polymorphism. Both in patients and in controls, the genotype distribution corresponded to the Hardy-Weinberg equilibrium. The gene frequency for Glu298Glu, Glu298Asp and Asp298Asp was not different in the control group compared to the patients (Armitage trend test: p = 0.37). The endothelial nitric oxide synthase polymorphism was related to acute post-operative elevation of pulmonary artery pressure (genotypic frequency 53.3 versus 25%; Armitage trend test: p = 0.038). In addition, the allelic frequency of the Glu298Asp was related to post-operative pulmonary hypertension (Fischer's exact test: p = 0.048). The positive predictive value was 71.43%.

CONCLUSION

Patients with left-to-right shunt are more likely to develop acute elevation of pulmonary artery pressure after cardiopulmonary bypass when presenting with the Glu298Asp polymorphism of the gene endothelial nitric oxide synthase. This could be used as a genetic marker for the predisposition for the development of pulmonary hypertension after intra-cardiac repair.

Effect of the 894G>T polymorphism of the endothelial nitric oxide synthase on vascular reactivity following maximal dynamic exercise

BACKGROUND

Considering that the role of nitric oxide as a vasodilator is increased after an acute bout of exercise and that the 894G>T polymorphism of the endothelial nitric oxide synthase seems to reduce the nitric oxide release in response to shear stress, the present study investigated the 894G>T polymorphism in relation to vascular reactivity following maximal dynamic exercise.

METHOD

We studied 110 healthy volunteers (wild-type group 45.5% and polymorphic group 54.5%). The protocol included vascular reactivity assessment at baseline and during reactive hyperemia, before, 10, 60 and 120 min after a maximal cardiopulmonary exercise test. Genomic DNA was extracted from blood samples to determine the 894G>T polymorphism.

RESULTS

There were no differences between the wild-type and polymorphic groups concerning anthropometric, metabolic and hemodynamic characteristics. Blood flow, before maximal exercise, was similar between the wild-type and the polymorphic groups. The polymorphic group presented lower vascular reactivity regardless of time (P = 0.019 for group main effect), and posthoc analysis revealed that polymorphic patients had lower values than wild-type only at the 120 min measurement (P = 0.002). Concerning within-group analysis, vascular reactivity increased at 10 min after exercise (P = 0.029) returning to baseline at 120 min (P = 0.005) in the polymorphic group.

CONCLUSION

Patients with the 894G>T polymorphism had lower vascular reactivity after a single bout of exercise.

A pharmacogenetics-based approach to reduce cardiovascular mortality with the prophylactic use of statins

Nitric oxide (NO) is the main endothelial-derived relaxation factor and plays a major role in cardiovascular homeostasis. This key signalling molecule is synthesised by a family of nitric oxide synthases (NOS), and the endothelial isoform (eNOS) is the most important for nitric oxide formation in the cardiovascular system. Cardiovascular drugs including statins increase eNOS expression and up-regulate NO formation, and this effect may be responsible for protective, pleiotropic effects produced by statins. However, the genetic background may also affect NO formation in the cardiovascular system, and recent studies have shown that genetic polymorphisms in the eNOS gene modify endogenous NO formation and the risk of developing cardiovascular diseases. For example, cases with the CC genotype for the T(-786)C polymorphism in the eNOS gene are at increased cardiovascular risk when compared with those with the TT genotype. Interestingly, pharmacogenetic studies have recently indicated that atorvastatin improves NO formation more clearly in these individuals. However, it is not known whether this polymorphism really increases cardiovascular morbidity and mortality, and whether atorvastatin or other statins attenuate the morbidity and mortality rates in cases with the CC genotype. If proved true, then statins-induced up-regulation of eNOS and increased NO formation could compensate for a genetic 'disadvantage' in cases with the CC genotype. This could be a significant advance in the prevention of cardiovascular events. It is necessary although to validate this hypothesis with clinical trials which will require a long follow-up to assess relevant clinical events and not only surrogate biomarkers.

Strong and persistent microbial and inflammatory stimuli overcome the genetic predisposition to higher matrix metalloproteinase-1 (MMP-1) expression: a mechanistic explanation for the lack of association of MMP1-1607 single-nucleotide polymorphism genotypes with MMP-1 expression in chronic periodontitis lesions

AIMS

Our objective was to evaluate the association between the MMP1-1607 single-nucleotide polymorphism (SNP), periodontopathogens and inflammatory cytokines with matrix metalloproteinase-1 (MMP-1) mRNA levels in vitro and in vivo.

MATERIALS AND METHODS

This study investigated the influence of genetic (MMP1-1607 SNP), microbial (Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Actinobacillus actinomycetemcomitans) and inflammatory [tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta)] factors on the determination of MMP-1 mRNA levels in periodontal tissues of non-smoker chronic periodontitis (CP, N=178) and control (C, N=190) groups. The effects of single and repeated lipopolysaccharide (LPS) and inflammatory cytokine stimulation of macrophages with distinct MMP1-1607 SNP genotypes were also investigated.

RESULTS

In healthy tissues, the MMP1-1607 2G allele was associated with higher MMP-1 levels while in CP MMP-1 levels were associated with the presence and load of periodontopathogens, and also with TNF-alpha and IL-1beta expression irrespective of the MMP1-1607 genotype. In vitro data demonstrate that in 2G macrophages low- and intermediate-dose LPS and TNF-alpha+IL-1beta stimulation was associated with increased MMP-1 expression, while strong and repeated stimulation resulted in higher MMP-1 levels irrespective of the MMP1-1607 genotype.

CONCLUSION

Our data demonstrate a limited role for MMP1-1607 SNP in periodontitis, where the extensive chronic antigenic challenge exposure overcomes the genetic control and plays a major role in the determination of MMP-1 expression.

Is Polymorphism within eNOS Gene Associated With the Late Onset of Myocardial Infarction? A Pilot Study

Introduction

Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) is a potent vasodilator. Several polymorphisms in the eNOS gene have been described, some of them being linked with the increased risk of cardiovascular disease, coronary heart disease (CHD), and coronary spasm.

Methods and Results

We studied 3 polymorphisms within the gene of eNOS (-786T/C, G10T, and 894 G/T) in patients with their first myocardial infarction (MI) younger than 45 years and in healthy volunteers. We found the relation between the occurrence of eNOS 894G allele and the Gensini score, which describes the severity of CHD ( P = .020).

Conclusions

The fact that first clinical manifestation of MI occurred in G carriers when the atherosclerotic plaque was much more advanced than in T carriers may suggest that wild-type genotype provided a better compensatory mechanisms due to NO synthesis and/or release. The polymorphisms within eNOS gene G10T, 894G/T, and −786T/C were not associated with the increased risk of MI.

Role of urate, xanthine oxidase and the effects of allopurinol in vascular oxidative stress

Oxidative stress plays an important role in the progression of vascular endothelial dysfunction. The two major systems generating vascular oxidative stress are the NADPH oxidase and the xanthine oxidase pathways. Allopurinol, a xanthine oxidase inhibitor, has been in clinical use for over 40 years in the treatment of chronic gout. Allopurinol has also been shown to improve endothelial dysfunction, reduce oxidative stress burden and improve myocardial efficiency by reducing oxygen consumption in smaller mechanistic studies involving various cohorts at risk of cardiovascular events. This article aims to explain the role of xanthine oxidase in vascular oxidative stress and to explore the mechanisms by which allopurinol is thought to improve vascular and myocardial indices.

Effects of chronic and acute consumption of fruit- and vegetable-puree-based drinks on vasodilation, risk factors for CVD and the response as a result of the eNOS G298T polymorphism

The average UK adult consumes less than three portions of fruit and vegetables daily, despite evidence to suggest that consuming five portions daily could help prevent chronic diseases. It is recommended that fruit juice should only count as one of these portions, as juicing removes fibre and releases sugars. However, fruit juices contain beneficial compounds such as vitamin C and flavonoids and could be a useful source of dietary phytochemicals. Two randomised controlled cross-over intervention studies investigating the effects of chronic and acute consumption of commercially-available fruit- and vegetable-puree-based drinks (FVPD) on bioavailability, antioxidant status and CVD risk factors are described. Blood and urine samples were collected during both studies and vascular tone was measured using laser Doppler imaging. In the chronic intervention study FVPD consumption was found to significantly increase dietary carotenoids (P=0.001) and vitamin C (P=0.003). Plasma carotenoids were increased (P=0.001), but the increase in plasma vitamin C was not significant. There were no significant effects on oxidative stress, antioxidant status and other CVD risk factors. In the acute intervention study FVPD were found to increase total plasma nitrate and nitrite (P=0.001) and plasma vitamin C (P=0.002). There was no effect on plasma lipids or uric acid, but there was a lower glucose and insulin peak concentration after consumption of the FVPD compared with the sugar-matched control. There was a trend towards increased vasodilation following both chronic and acute FVPD consumption. All volunteers were retrospectively genotyped for the eNOS G298T polymorphism and the effect of genotype on the measurements is discussed. Overall, there was a non-significant trend towards increased endothelium-dependent vasodilation following both acute and chronic FVPD consumption. However, there was a significant time x treatment effect (P<0.05) of acute FVPD consumption in individuals with the GG variant of the eNOS gene.