Serum nitrate and nitrite levels in patients with hypertension and ischemic stroke depend on diet: a multicenter study

In Mild and Moderate Acute Ischemic Stroke, Increased Lipid Peroxidation and Lowered Antioxidant Defenses Are Strongly Associated with Disabilities and Final Stroke Core Volume

In acute ischemic stroke (AIS), there are no data on whether oxidative stress biomarkers have effects above and beyond known risk factors and measurements of stroke volume. This study was conducted in 122 mild-moderate AIS patients and 40 controls and assessed the modified ranking scale (mRS) at baseline, and 3 and 6 months later. We measured lipid hydroperoxides (LOOH), malondialdehyde (MDA), advanced oxidation protein products, paraoxonase 1 (PON1) activities and PON1 Q192R genotypes, high density lipoprotein cholesterol (HDL), sulfhydryl (-SH) groups), and diffusion-weighted imaging (DWI) stroke volume and fluid-attenuated inversion recovery (FLAIR) signal intensity. We found that (a) AIS is characterized by lower chloromethyl acetate CMPAase PON1 activity, HDL and -SH groups and increased LOOH and neurotoxicity (a composite of LOOH, inflammatory markers and glycated hemoglobin); (b) oxidative and antioxidant biomarkers strongly and independently predict mRS scores 3 and 6 months later, DWI stroke volume and FLAIR signal intensity; and (c) the PON1 Q192R variant has multiple effects on stroke outcomes that are mediated by its effects on antioxidant defenses and lipid peroxidation. Lipid peroxidation and lowered -SH and PON1-HDL activity are drug targets to prevent AIS and consequent neurodegenerative processes and increased oxidative reperfusion mediators due to ischemia-reperfusion injury.

Associations of endothelial biomarkers, nitric oxide metabolites and endothelin, with blood pressure and coronary lesions depend on cardiovascular risk and sex to mark endothelial dysfunction on the SCORE scale

OBJECTIVES

Endothelial dysfunction contributes to the onset and progression of cardiovascular diseases. However, direct associations of vasoactive mediators with cardiovascular risk are poorly understood.

METHODS

We have determined associations of circulating levels of stable metabolites of nitric oxide, nitrate and nitrite (NOx), endothelin-1, and the endothelin-1/NOx ratio with blood pressure in 177 asymptomatic subjects without signs of coronary atherosclerosis; associations with blood pressure and with presence of coronary lesions were also evaluated in 457 patients suspected to have coronary heart disease with or without coronary lesions confirmed by coronary angiography. All participants were on a low nitrate diet 24 h prior to blood sampling.

RESULTS

In men, NOx levels were inversely correlated with blood pressure similar to women with low (0-4%) European Systematic Coronary Risk Estimation (SCORE). However, the correlation was not significant in women with high SCORE (5-8%). High systolic blood pressure over 140 mm Hg was negatively associated with NOx levels in asymptomatic men (p=0.05) but not in women. This association is disrupted in male and female patients with coronary atherosclerosis. In male patients, NOx (p=0.05), endothelin (p=0.01), and the endothelin/NOx ratio (p=0.04) were associated with presence of coronary lesions.

CONCLUSIONS

Thus, elevated cardiovascular risk according to SCORE over 4% in asymptomatic women, but not in men, is associated with a shift in markers of endothelial dysfunction. Presence of coronary lesions in patients is associated with significant changes in circulating levels of markers of endothelial dysfunction in men but not in women.

Immune-Inflammatory, Metabolic, Oxidative, and Nitrosative Stress Biomarkers Predict Acute Ischemic Stroke and Short-Term Outcome

Immune-inflammatory, metabolic, oxidative, and nitrosative stress (IMO&NS) pathways and, consequently, neurotoxicity are involved in acute ischemic stroke (IS). The simultaneous assessment of multiple IMO&NS biomarkers may be useful to predict IS and its prognosis. The aim of this study was to identify the IMO&NS biomarkers, which predict short-term IS outcome. The study included 176 IS patients and 176 healthy controls. Modified Rankin scale (mRS) was applied within 8 h after IS (baseline) and 3 months later (endpoint). Blood samples were obtained within 24 h after hospital admission. IS was associated with increased white blood cell (WBC) counts, high sensitivity C-reactive protein (hsCRP), interleukin (IL-6), lipid hydroperoxides (LOOHs), nitric oxide metabolites (NOx), homocysteine, ferritin, erythrocyte sedimentation rate (ESR), glucose, insulin, and lowered iron, 25-hydroxyvitamin D [25(OH)D], total cholesterol, and high-density lipoprotein (HDL) cholesterol. We found that 89.4% of the IS patients may be correctly classified using the cumulative effects of male sex, systolic blood pressure (SBP), glucose, NOx, LOOH, 25(OH)D, IL-6, and WBC with sensitivity of 86.2% and specificity of 93.0%. Moreover, increased baseline disability (mRS ≥ 3) was associated with increased ferritin, IL-6, hsCRP, WBC, ESR, and glucose. We found that 25.0% of the variance in the 3-month endpoint (mRS) was explained by the regression on glucose, ESR, age (all positively), and HDL-cholesterol, and 25(OH)D (both negatively). These results show that the cumulative effects of IMO&NS biomarkers are associated with IS and predict a poor outcome at 3-month follow-up.

Nitric oxide metabolism is impaired by type 1 diabetes and diabetic nephropathy

Diabetes leads to reduced nitric oxide bioavailability, resulting in endothelial dysfunction. However, overproduction of nitric oxide due to hyperglycaemia is associated with oxidative stress and tissue damage. The objective of this study was to characterise nitric oxide production (NO) and added nitrite and nitrate (NO₂ ^-+NO₃ ^-) concentration in the blood and urine of patients with and without diabetic nephropathy. A total of 268 patients with type 1 diabetes and 69 healthy subjects were included. Diabetic nephropathy was defined as macroalbuminuria and/or estimated glomerular filtration rate below 60 ml/min/1.73 cm². NO₂ ^-+NO₃ ^- concentration was measured by Griess reaction. Production of NO was detected by electron paramagnetic resonance spectroscopy. Blood NO was demonstrated to be higher (P<0.001) and serum NO₂ ^-+NO₃ ^- was lower (P=0.003) in patients with type 1 diabetes and no nephropathy vs. healthy subjects. However, serum NO₂ ^-+NO₃ ^- concentration in patients with diabetes and nephropathy did not differ from the levels observed in healthy controls. Urine excretion of NO₂ ^-+NO₃ ^- was significantly decreased in patients with nephropathy, compared with patients without diabetic kidney disease (P=0.006) and healthy subjects (P=0.010). A significant positive correlation was observed between urine NO₂ ^-+NO₃ ^- and estimated glomerular filtration rate in patients with type 1 diabetes (P=0.002) and healthy subjects (P=0.008). Estimated glomerular filtration rate, albuminuria and diabetic nephropathy status were significant predictors of the whole blood NO and NO₂ ^-+NO₃ ^- in serum and urine in patients with type 1 diabetes, as identified by linear regression models. The present study concludes that NO metabolism is impaired by type 1 diabetes and diabetic nephropathy.

Increase in perfused boundary region of endothelial glycocalyx is associated with higher prevalence of ischemic heart disease and lesions of microcirculation and vascular wall

OBJECTIVE

PBR characterizes penetration of red blood cells inside glycocalyx and its thickness can have profound impact on microcirculation and other vascular parameters. The goal of our study was to reliably quantify PBR and assess its potential use as a new marker of cardiovascular pathology.

METHODS

The study included 208 patients (123 men and 85 women from 40 to 65 years of age) with various grades of cardiovascular SCORE risk index and IHD. PBR was quantified by sidestream dark field capillaroscopy with green light excitation. Cutaneous microcirculation was evaluated with laser Doppler fluorometry.

RESULTS

Elevated PBR values over 2 mm were associated with morphological and functional lesions of arterial wall and microcirculation and lowered levels of ApoA1 lipoprotein. Moreover, elevated PBR values were associated with 2.07-fold increase in prevalence of cerebral atherosclerosis (P = .015) and 2.42-fold increase in prevalence of IHD (P = .024). Increase in PBR was associated with elevated systolic blood pressure.

CONCLUSIONS

Thus, PBR can be considered a new highly reproducible and promising marker candidate for non-invasive diagnostics of IHD and cerebral atherosclerosis suggesting important role of microcirculation in development and progression of cardiovascular diseases.

[Cerebral atherosclerosis: a biomarker profile]

AIM

To assess the changes in several biomarkers in patients with atherosclerosis of brachiocephalic arteries and shape a biomarker profile of cerebral atherosclerosis as an integrative index.

MATERIAL AND METHODS

The study included 124 patients with atherosclerotic lesions of internal carotid arteries (82 men and 42 women) aged from 37 to 73 years. The patients were stratified by history of prior stroke into 'asymptomatic' and 'symptomatic'. Along with general clinical and neurological examinations, ultrasound analysis of brachiocephalic arteries, neuroimaging, identification of biomarkers reflecting different stages of atherogenesis and evaluation of pathomorphological parameters of atherosclerotic plaques removed during carotid endarterectomy surgery were performed.

RESULTS

Concentrations of NO₂, NO₃ and NO in blood plasma significantly differed between groups: 58.4, 43.3 and 15 mcmol/l, respectively, in the symptomatic group and 45, 19.2 and 25.8 mcmol/l in the asymptomatic group. The pro-inflammatory character of changes in atherosclerosis was confirmed by the increase in the concentration of lipoprotein-associated phospholipase A2 in patients with stroke (354.72±44.16 ng/ml versus 298.45±54.12 ng/ml). The level of the atheroprotective marker adiponectin decreased significantly in 'symptomatic' patients. Significant changes towards the prothrombotic state of blood were identified via levels of blood markers of fibrinolytic activity: plasminogen tissue activator and plasminogen activator inhibitor-1.

CONCLUSION

Together with other diagnostic methods, identification of biomarkers can increase the accuracy of prognosis and prevention of sudden cardiovascular death. The authors have developed a scale of biomarker 'burdeness' of the patient with cerebral atherosclerosis that may be a first step to individualized prevention of associated ischemic complications.

Nitrate-rich beetroot juice selectively lowers ambulatory pressures and LDL cholesterol in uncontrolled but not controlled hypertension: a pilot study

BACKGROUND

Dietary nitrate has been shown to increase nitrate/nitrite levels in multiple populations, with potential blood pressure lowering effects. However, there are few reports among hypertensives.

AIMS

We aimed to assess the effect of daily nitrate in subjects with controlled hypertension vs. uncontrolled hypertension.

METHODS

On day 0, hypertensives wore an ambulatory BP monitor (ABPM) for 24 h and fasting blood was taken. Subjects then consumed concentrated beetroot juice (12.9 mmol nitrate) for 14 consecutive days. On day 14 subjects consumed their last nitrate dose after fasting blood was drawn and again had an ABPM for 24 h.

RESULTS

According to baseline ABPM, 11 subjects had controlled BP while 8 had uncontrolled BP. There were similar, significant increases in serum nitrate/nitrite in both groups. We observed little change in BP variables among controlled hypertensives. However, there were reductions in BP variables in uncontrolled hypertensives where decreases in nighttime DBP (-6 ± 4.8 mmHg), arterial stiffness (-0.08 ± 0.03 ambulatory arterial stiffness index) and LDL (-0.36 ± 0.42 mmol/L) reached significance (p = 003, 0.05 and 0.046, respectively).

CONCLUSIONS

Our results support the existing data suggesting an anti-hypertensive effect of nitrate-containing beetroot juice, but only among those with uncontrolled hypertension.

Serum nitrite and nitrate levels, NOx, can predict cardiovascular mortality in the elderly in a 3-year follow-up study

Nitric oxide (NO) is an important functional regulator that contributes to progression of various cardiovascular diseases. We studied associations between nitric oxide metabolites, nitrite and nitrate (NOx), and cardiovascular mortality in a prospective 3-year follow-up cohort study in 1,869 elderly patients aged over 55 years. The Cox proportional hazard regression model was adjusted for multiple factors including sex, age, risk corresponding to preexisting cardiovascular conditions, and serum inflammatory markers (C-reactive protein, interleukin-6, fibrinogen, and leucocytes count). During the follow-up period, there were a total of 348 deaths including 216 deaths unrelated to cardiovascular events and 132 cardiovascular deaths. Cox regression adjusted for factors related to cardiovascular disease risks and inflammatory markers showed a significant association between high levels of serum nitric oxide metabolites, NOx, and increased cardiovascular mortality (hazard ratio 2.21; 95% confidence interval 1.13-4.31) but there was no association with non-cardiovascular mortality. Analysis of adjusted hazard ratios demonstrates that association of serum nitric oxide metabolites with cardiovascular mortality was independent of levels of inflammatory markers. Thus, elevated concentrations of serum nitric oxide metabolites are a predictor of cardiovascular mortality and may be used as an integral marker of cardiovascular death. © 2016 BioFactors, 43(1):82-89, 2017.

Dietary L-arginine intake and the incidence of coronary heart disease: Tehran lipid and glucose study

Background

We investigated the association of regular dietary intake of L-arginine and both the incidence of coronary heart disease (CHD) and changes of blood pressure.

Methods

Eligible adults (n = 2284) who participated in the Tehran Lipid and Glucose Study were followed for a mean of 4.7 years. Dietary intake of L-arginine was assessed at baseline (2006–2008); biochemical variables were evaluated at baseline and the follow-up examination. Multivariate Cox proportional hazard regression models adjusted for potential confounders were used to estimate the risk of CHD across tertiles of L-arginine intake. Linear regression models were also used to indicate the association of L-arginine intake with changes of serum lipids and blood pressure during the follow-up.

Results

Mean age of participants (42.8 % men) was 38.2 ± 13.4, at baseline. During a mean 4.7 ± 1.4 y of follow-up, 57 participants experienced CHD events. A significant negative association was observed between plant-derived L-arginine intake and changes of both systolic and diastolic blood pressure, whereas animal-derived L-arginine intake was related to increased levels of diastolic blood pressure (P < 0.01). Participants in the 2^nd tertile (1.45–1.78 g/d) had a significantly increased risk of CHD events compared to the participants in the 1^st tertile (<1.45 g/d) (HR = 1.90, 95 % CI = 1.03–3.58). The risk of CHD had a decreasing trend across increasing plant-derived L-arginine intake (HR = 1.0, HR = 0.91, 95 % CI = 0.51–1.62, HR = 0.72, 95 % CI = 0.39–1.32, P for trend = 0.03).

Conclusion

Higher intake of plant derived L-arginine may have a protective effect whereas animal-derived L-arginine may be a risk factor for development of hypertension and CHD events.