Serum nitric oxide metabolite levels in a general healthy population: Relation to sex and age

Antiaging in a Bottle: Bioactive Competency of Plasma-Generated Nitric Oxide Water for Modulation of Aging-Related Signature in Human Dermal Cells

Nitric oxide (NO), a potential therapeutic antiaging molecule, modulates various physiological and cellular processes. However, alterations in endogenous NO levels brought on by aging impact multiple organ systems and heighten susceptibility to age-related skin diseases. This correlation underscores the importance of investigating NO-based antiaging interventions. Nonthermal plasma-generated NO is a promising avenue for cosmetic and regenerative medicine due to its capacity to stimulate cellular growth. Herein, we examine the potential of plasma-generated nitric oxide water (NOW) as a bioactive agent in human dermal fibroblasts, emphasizing gene expression patterns linked to extracellular matrix (ECM) breakdown and cellular senescence. The findings of our study indicate that administering NOW at lower dosages enhances cell migration and proliferation. Moreover, the genetic signatures associated with ECM synthesis, antioxidant defense, and antisenescence pathways have been analyzed in NOW-exposed cells. Notably, the downregulation of ECM-degrading enzyme transcripts─collagenase, elastase, and hyaluronidase─suggests NOW's potential in mitigating the intrinsic skin aging phenomena, emphasizing the promise of NO-based interventions in advancing antiaging strategies within regenerative medicine.

Functional polymorphisms of NOS3 and GUCY1A3 affect both nitric oxide formation and association with hypertensive disorders of pregnancy

Impaired nitric oxide (NO) formation may be associated with endothelial dysfunction and increased cardiovascular disease risk in preeclampsia (PE). Functional single-nucleotide polymorphisms (SNPs) of nitric oxide synthase 3 (NOS3) (rs3918226) and guanylate cyclase 1, soluble, alpha 3 (GUCY1A3) (rs7692387) increase susceptibility to the adverse consequences due to inadequate generation of NO by the endothelium. However, no previous study has examined whether these SNPs affect NO formation in healthy pregnancy and in gestational hypertension (GH) and PE. Here, we compared the alleles and genotypes of NOS3 (rs3918226) and GUCY1A3 (rs7692387) SNPs in normotensive pregnant women (NP, n = 153), in GH (n = 96) and PE (n = 163), and examined whether these SNPs affect plasma nitrite concentrations (a marker of NO formation) in these groups. We further examined whether the interaction among SNP genotypes is associated with GH and PE. Genotypes were determined using TaqMan allele discrimination assays, and plasma nitrite concentrations were determined by an ozone-based chemiluminescence assay. Multifactor dimensionality reduction was used to examine the interactions among SNP genotypes. Regarding NOS3 rs3918226, the CT genotype (p = 0.046) and T allele (p = 0.020) were more frequent in NP than in GH, and GH patients carrying the CT+TT genotypes showed lower nitrite concentrations than NP carrying the CT+TT genotypes (p < 0.05). Regarding GUCY1A3 rs7692387, the GA genotype (p = 0.013) and A allele (p = 0.016) were more frequent in PE than in NP, and NP women carrying the GG genotype showed higher nitrite concentrations than GH or PE patients carrying the GG genotype (p < 0.05). However, we found no significant interactions among genotypes for these functional SNPs to be associated with GH or PE. Our novel findings suggest that NOS3 rs3918226 and GUCY1A3 rs7692387 may affect NO formation and association with hypertensive disorders of pregnancy.

Treatment of leishmaniasis with chemotherapy and vaccine: a mathematical model

Leishmaniasis, an infectious disease, manifests itself mostly in two forms, cutaneous leishmaniasis (CL) and, a more severe and potentially deadly form, visceral leishmaniasis (VL). The current control strategy for leishmaniasis relies on chemotherapy drugs such as sodium antimony gluconate (SAG) and meglumine antimoniate (MA). However, all these chemotherapy compounds have poor efficacy, and they are associated with toxicity and other adverse effects, as well as drug resistance. While research in vaccine development for leishmaniasis is continuously progressing, no vaccine is currently available. However, some experimental vaccines such as LEISH-F1+MPL-SE (V) have demonstrated some efficacy when used as drugs for CL patients. In this paper we use a mathematical model to address the following question: To what extent vaccine shots can enhance the efficacy of standard chemotherapy treatment of leishmaniasis? Starting with standard MA treatment of leishmaniasis and combining it with three injections of V , we find, by Day 84, that efficacy increased from 29% to 65-91% depending on the amount of the vaccine. With two or just one injection of V , efficacy is still very high, but there is a definite resurgence of the disease by end-time.

Microbial metabolites in the pathogenesis of periodontal diseases: a narrative review

The purpose of this narrative review is to highlight the importance of microbial metabolites in the pathogenesis of periodontal diseases. These diseases, involving gingivitis and periodontitis are inflammatory conditions initiated and maintained by the polymicrobial dental plaque/biofilm. Gingivitis is a reversible inflammatory condition while periodontitis involves also irreversible destruction of the periodontal tissues including the alveolar bone. The inflammatory response of the host is a natural reaction to the formation of plaque and the continuous release of metabolic waste products. The microorganisms grow in a nutritious and shielded niche in the periodontal pocket, protected from natural cleaning forces such as saliva. It is a paradox that the consequences of the enhanced inflammatory reaction also enable more slow-growing, fastidious, anaerobic bacteria, with often complex metabolic pathways, to colonize and thrive. Based on complex food chains, nutrient networks and bacterial interactions, a diverse microbial community is formed and established in the gingival pocket. This microbiota is dominated by anaerobic, often motile, Gram-negatives with proteolytic metabolism. Although this alternation in bacterial composition often is considered pathologic, it is a natural development that is promoted by ecological factors and not necessarily a true "dysbiosis". Normal commensals are adapting to the gingival crevice when tooth cleaning procedures are absent. The proteolytic metabolism is highly complex and involves a number of metabolic pathways with production of a cascade of metabolites in an unspecific manner. The metabolites involve short chain fatty acids (SCFAs; formic, acetic, propionic, butyric, and valeric acid), amines (indole, scatole, cadaverine, putrescine, spermine, spermidine) and gases (NH₃, CO, NO, H₂S, H₂). A homeostatic condition is often present between the colonizers and the host response, where continuous metabolic fluctuations are balanced by the inflammatory response. While it is well established that the effect of the dental biofilm on the host response and tissue repair is mediated by microbial metabolites, the mechanisms behind the tissue destruction (loss of clinical attachment and bone) are still poorly understood. Studies addressing the functions of the microbiota, the metabolites, and how they interplay with host tissues and cells, are therefore warranted.

Lack of association between the eNOS rs1800779 (A/G) polymorphism and the myocardial infarction incidence among the Iraqi Kurdish population

OBJECTIVES

The genetic polymorphisms of the endothelial nitric oxide synthase (eNOS) gene are strongly associated with several cardiovascular diseases (CVDs) in various populations. The current study aimed to investigate the association of the eNOS rs1800779 (A/G) polymorphism with the progress of myocardial infarction (MI).

METHODS

Eighty-five healthy subjects and 80 patients with MI admitted to the Erbil Cardiac Centre in the Kurdistan Region of Iraq were enrolled in the study. All participants were Kurdish from the same ethnic group. The amplification refractory mutation system polymerase chain reaction (ARMS-PCR) was used to determine the rs1800779 (A/G) polymorphism of eNOS, and the nitric oxide (NO) serum level was detected by spectrophotometer.

RESULTS

The genotypic frequencies of the eNOS rs1800779 AA (wild type), AG, and GG were 58.75%, 33.75%, and 7.50%, respectively, in the MI patients, and 49.41%, 43.53%, and 7.06%, respectively, for the control group. The frequencies of the A and the G alleles were 75.6% and 24.4%, respectively, in the MI group, and 71.2% and 28.8%, respectively, in the control subjects. The results revealed a lack of association of the rs1800779 genotype distribution with the level of NO serum and increased risk of MI.

CONCLUSION

The study concluded that there is a lack of association between the genotypes and alleles of the rs1800779 eNOS and susceptibility to MI in the studied population.

N-Acetyl-L-cysteine in human rheumatoid arthritis and its effects on nitric oxide (NO) and malondialdehyde (MDA): analytical and clinical considerations

N-Acetyl-L-cysteine (NAC) is an endogenous cysteine metabolite. The drug is widely used in chronic obstructive pulmonary disease (COPD) and as antidote in acetaminophen (paracetamol) intoxication. Currently, the utility of NAC is investigated in rheumatoid arthritis (RA), which is generally considered associated with inflammation and oxidative stress. Besides clinical laboratory parameters, the effects of NAC are evaluated by measuring in plasma or serum nitrite, nitrate or their sum (NOx) as measures of nitric oxide (NO) synthesis. Malondialdehyde (MDA) and relatives such as 4-hydroxy-nonenal and 15(S)-8-iso-prostaglandin F_2α serve as measures of oxidative stress, notably lipid peroxidation. In this work, we review recent clinico-pharmacological studies on NAC in rheumatoid arthritis. We discuss analytical, pre-analytical and clinical issues and their potential impact on the studies outcome. Major issues include analytical inaccuracy due to interfering endogenous substances and artefactual formation of MDA and relatives during storage in long-term studies. Differences in the placebo and NAC groups at baseline with respect to these biomarkers are also a serious concern. Modern applied sciences are based on data generated using commercially available instrumental physico-chemical and immunological technologies and assays. The publication process of scientific work rarely undergoes rigorous peer review of the analytical approaches used in the study in terms of accuracy/trueness. There is pressing need of considering previously reported reference concentration ranges and intervals as well as specific critical issues such as artefactual formation of particular biomarkers during sample storage. The latter especially applies to surrogate biomarkers of oxidative stress, notably MDA and relatives. Reported data on NO, MDA and clinical parameters, including C-reactive protein, interleukins and tumour necrosis factor α, are contradictory in the literature. Furthermore, reported studies do not allow any valid conclusion about utility of NAC in RA. Administration of NAC patients with rheumatoid arthritis is not recommended in current European and American guidelines.

A Whiff of Sulfur: One Wind a Day Keeps the Doctor Away

Reactive Sulfur Species (RSS), such as allicin from garlic or sulforaphane from broccoli, are fre-quently associated with biological activities and possible health benefits in animals and humans. Among these Organic Sulfur Compounds (OSCs) found in many plants and fungi, the Volatile Sulfur Compounds (VSCs) feature prominently, not only because of their often-pungent smell, but also because they are able to access places which solids and solutions cannot reach that easily. Indeed, inorganic RSS such as hydrogen sulfide (H₂S) and sulfur dioxide (SO₂) can be used to lit-erally fumigate entire rooms and areas. Similarly, metabolites of garlic, such as allyl methyl sulfide (AMS), are formed metabolically in humans in lower concentrations and reach the airways from inside the body as part of one’s breath. Curiously, H₂S is also formed in the gastrointestinal tract by gut bacteria, and the question of if and for which purpose this gas then crosses the barriers and enters the body is indeed a delicate matter for equally delicate studies. In any case, nature is surprisingly rich in such VSCs, as fruits (for instance, the infamous durian) demonstrate, and therefore these VSCs represent a promising group of compounds for further studies.

Ratio of Nitric Oxide Metabolite Levels in Cerebrospinal Fluid and Serum, and Their Correlation with Severity and Outcome in Patients with Subarachnoid Haemorrhage

BACKGROUND

Nitric oxide (NO) is involved in a multitude of physiological processes in the central nervous system (CNS). Given the ubiquitous nature of NO and its involvement in various vital processes, nitric oxide metabolite (NOx) has been investigated as a biomarker in CNS diseases. This study aims to investigate the ratio of NOx levels and serum in cerebrospinal fluid (CSF) in patients with spontaneous subarachnoid haemorrhage (SAH). The associations among these markers with clinical outcomes were also studied.

METHODS

A prospective cohort study was conducted over a 2-year period (May 2013-May 2015) to investigate the levels of NOx in the CSF and serum of patients with radiologically confirmed aneurysmal SAH. NOx samples and all relevant data were collected from the patients on admission and serially over 5 days. On admission, NOx levels were compared between the groups of patients, who were divided as per the World Federation Neurosurgeons Score (WFNS) grading scale, Fisher scale, occurrence of vasospasm on transcranial doppler (TCD), and Glasgow outcome scale (GOS) upon discharge and at 6 months follow-up. The ratios of CSF-to-serum were calculated and correlated with SAH severity and the outcome parameters listed above.

RESULTS

The patients (N = 40) had a mean (SD) age of 58.2 (11.8) years old. The majority (65%) had a higher severity of SAH (WFNS score 3-5). On evaluation of the CT scan findings, 74% had outcomes equivalent to 4 on the Fisher scale. Vasospasm was detected via TCD in nearly half (45%) of the cohort during the study period; 80% were noted to have a poor outcome (GOS 1-3) at discharge; this persisted at 6 months follow-up. Comparison of NOx levels in the CSF/serum ratio was based on the incidence of vasospasm and severity of outcome (GOS) for day-1 and day-4. Statistically significant results were evident for patients with better outcomes, high severity grading, and the presence of vasospasm (P-values: 0.031, 0.034 and 0.043, respectively).

CONCLUSION

Elevated NOx levels in CSF and serum and reductions in the ratio of NOx in CSF/serum were found to be associated with severity, occurrence of vasospasm and clinical outcome in aneurysmal SAH patients. This indicates the possible role of NOx as a biomarker to assess severity and prognosis in patients with SAH.

Novel Insights on the Role of Nitric Oxide in the Ovary: A Review of the Literature

Nitric oxide (NO) is formed during the oxidation of L-arginine to L-citrulline by the action of multiple isoenzymes of NO synthase (NOS): neuronal NOS (nNOS), endotelial NOS (eNOS), and inducible NOS (iNOS). NO plays a relevant role in the vascular endothelium, in central and peripheral neurons, and in immunity and inflammatory systems. In addition, several authors showed a consistent contribution of NO to different aspects of the reproductive physiology. The aim of the present review is to analyse the published data on the role of NO within the ovary. It has been demonstrated that the multiple isoenzymes of NOS are expressed and localized in the ovary of different species. More to the point, a consistent role was ascribed to NO in the processes of steroidogenesis, folliculogenesis, and oocyte meiotic maturation in in vitro and in vivo studies using animal models. Unfortunately, there are few nitric oxide data for humans; there are preliminary data on the implication of nitric oxide for oocyte/embryo quality and in-vitro fertilization/embryo transfer (IVF/ET) parameters. NO plays a remarkable role in the ovary, but more investigation is needed, in particular in the context of human ovarian physiology.

Urine Nitric Oxide Is Lower in Parents of Autistic Children

Parents raising children with autism spectrum disorder (ASD) usually carry on their daily life under tremendous stress, but limited empirical research has been devoted to this population. It is known that parents' health status directly impacts therapeutic outcome of ASD children. As an important regulator in cardiovascular, nervous and immune systems, nitric oxide (NO) levels haven't been reported in parents of ASD children yet. In this study, we measured urine nitrite and nitrate from 43 ASD parents (ASD-P), and 43 healthy adults in the same range of age (Control) who didn't have any ASD descendants. Comparison between the ASD-P and Control groups showed that NO 2 - , NO 3 - , and NO 2 - / NO 3 - were all significantly lower in the ASD-P group. Analysis on the interaction effect of sex and group indicated that urine NO 3 - of mothers in ASD-P was lower than that in females of the Control group, but no significant difference was observed between males in both groups. It is for the first time that urine nitric oxide metabolites (nitrite, nitrate) levels were precisely reported to differentiate parents of autistic children from other adults without ASD descendants. This phenomenon suggests that parents (especially mothers) of autistic children might have experienced more mental and physical stressors, which led to decreased NO levels during metabolism. Further investigations are necessary to uncover the etiology of low urine NO among parents of autistic children.

Palm Kernel Cake Oligosaccharides Acute Toxicity and Effects on Nitric Oxide Levels Using a Zebrafish Larvae Model

One of the beneficial effects of non-digestible oligosaccharides (NDOs) is their anti-inflammatory effects on host animals. While conventional animal studies require that analysis be done after samples have been taken from the host, zebrafish larvae are optically transparent upon hatching and this provides an opportunity for observations to be made within the living zebrafish larvae. This study aimed to take advantage of the optical transparency of zebrafish larvae to study the nitric oxide (NO) reducing effects of NDOs through the use of lipopolysaccharide (LPS) from Salmonella enterica serovar (ser.) Enteritidis (S. Enteritidis) to induce cardiac NO production. Prior to running the above experiment, an acute toxicity assay was conducted in order to determine the appropriate concentration of oligosaccharides to be used. The oligosaccharides tested consisted of oligosaccharides which were extracted from palm kernel cake with a degree of polymerization (DP) equal to or less than six (OligoPKC), commercial mannanoligosaccharide (MOS) and commercial fructooligosaccharide (FOS). Acute toxicity test results revealed that the OligoPKC has a LC₅₀ of 488.1 μg/ml while both MOS and FOS were non-toxic up to 1,000 μg/ml. Results of the in vivo NO measurements revealed that all three NDOs were capable of significantly reducing NO levels in LPS stimulated zebrafish embryos. In summary, at 250 μg/ml, OligoPKC was comparable to MOS and better than FOS at lowering NO in LPS induced zebrafish larvae. However, at higher doses, OligoPKC appears toxic to zebrafish larvae. This implies that the therapeutic potential of OligoPKC is limited by its toxicity.

Salivary Redox Biomarkers in the Course of Caries and Periodontal Disease

Caries are a pathological process of extracorporeal nature, characterized by demineralization of inorganic substances as well as proteolysis triggered by acids produced by bacteria present in dental plaque, as a result of metabolism of sugars of both external and internal origin. Periodontal disease, on the other hand, is a multifactorial degenerative disease associated with inflammation, involving a group of tissues that surround the dental cervix and root of the tooth. It is believed that one of the mechanisms in the etiopathogenesis of caries and periodontitis are disorders of local and/or general oxidative stress (OS) parameters. Numerous clinical studies have confirmed the relationship between oxidative stress markers and oral diseases. In most analyzed studies, technical and biological variability was so high that none of the markers so far has proven suitable for routine clinical use. The aim of systematic reviews of the literature is to present the existing studies on OS parameters, mainly concerning the activity of antioxidant enzymes in saliva of patients with caries and periodontitis.

Dietary Nitrate Supplementation and Exercise-Related Performance

Over the last decade, there has been a growing interest in the utility of nitrate (NO3^-) supplementation to improve exercise-related performance. After consumption, dietary NO3^- can be reduced to nitric oxide, a free radical gas involved in numerous physiological actions including blood vessel vasodilation, mitochondrial respiration, and skeletal muscle contractile function. Emerging evidence indicates that dietary NO3^- supplementation has a small but nevertheless significant beneficial effect on endurance performance through the combined effects of enhanced tissue oxygenation and metabolic efficiency in active skeletal muscle. There is further evidence to suggest that dietary NO3^- exerts a direct influence on contractile mechanisms within the skeletal muscle through alterations in calcium availability and sensitivity. Response heterogeneity and sizeable variability in the nitrate content of beetroot juice products influence the effectiveness of dietary NO3^- for exercise performance, and so dosing and product quality, as well as training history, sex, and individual-specific characteristics, should be considered.

The role of nitric oxide (NO) levels in patients with obstructive sleep apnea-hypopnea syndrome: a meta-analysis

PURPOSE

The pathogenesis of cardiovascular disease (CVD) in patients with obstructive sleep apnea (OSA) is unclear. Several studies have suggested that CVD may be caused by oxidative stress from chronic intermittent hypoxia and associated vascular endothelial dysfunction. Oxidative stress in patients with OSA can induce endothelial cell apoptosis, aggravate vascular endothelial damage, and promote the expression of redox-sensitive genes and adhesion molecules. No meta-analysis has explored whether or not OSA is related to nitric oxide (NO).

METHOD

To assess the association between serum/plasma NO levels and OSA, we performed a meta-analysis of the literature on the subject to grade the strength of evidence.

RESULTS

OSA was significantly related to decreased serum or plasma NO levels (WMD = - 11.66, 95% CI - 17.21 to - 6.11; P < 0.01). Among the studies analyzed, there was high degree of heterogeneity (I² = 79%, P < 0.01). Sensitivity analysis showed that after omitting any single study or converting a random effects model (REM) to a fixed effects model (FEM), the main results still held.

CONCLUSIONS

This meta-analysis suggests a strong correlation between OSA and serum or plasma NO levels which may explain the link between intermittent hypoxia of OSA and risk of CVD. The strength of this finding may spur further basic and clinical research into vascular endothelial dysfunction in patients with OSA.

Nitric oxide (NO) levels in patients with polycystic ovary syndrome (PCOS): a meta-analysis

Objective

The pathogenesis of polycystic ovarian syndrome (PCOS) remains unclear, but is known to be related to increased insulin resistance, diabetes, obesity, oxidative stress, inflammation, and cardiovascular disease. No meta-analyses have examined whether PCOS is associated with nitric oxide (NO). Therefore, we aimed to evaluate the association between serum/plasma nitrite levels and PCOS.

Methods

We performed a meta-analysis. To identify eligible original articles, we searched online computerized databases, including EMBASE, Medline, and Web of Science. The characteristics of each single study, as well as the standard mean difference (SMD) with corresponding confidence intervals (CIs), were calculated and subgroup analysis was performed to examine heterogeneity.

Results

We included 12 articles with 16 studies and a total of 895 patients were included in the meta-analysis. We found a significant association between PCOS and serum or plasma nitrite levels, with a pooled SMD of −0.61 (95% CI: −1.05 to −0.16). The final pooled data were determined by the random effects model because significant high heterogeneity (I² = 89%) was found.

Conclusions

Our meta-analysis shows that decreased serum or plasma nitrite levels are associated with PCOS. The pathogenesis of PCOS may be due to endothelial dysfunction; however, further research to confirm this possibility is required.

Exploring the role of body mass index in relationship of serum nitric oxide and advanced glycation end products in apparently healthy subjects

This study aimed to identify any association of serum nitric oxide (NO) and advanced glycation end products (AGEs) with body mass index (BMI) in apparently healthy subjects. In this cross-sectional study, participants were 90 apparently healthy subjects, categorized into three BMI groups as follows: BMI≤19.5 (n = 21), 19.6≤BMI≤24.9 (n = 35), and BMI≥25 (n = 34). Serum levels of NO were measured by griess reaction method. Determination of serum pentosidine and carboxymethyllysine (CML) was done using ELISA. Median (95% confidence interval [CI]: lower- upper) of serum NO in subjects with BMI≥25 were 68.94 (CI: 55.01–70.56) μmol/L, which was higher compared with 19.6≤BMI≤24.9 and BMI≤19.5 groups (22.65 (CI: 19.29–28.17) μmol/L and 8.00 (CI: 9.12–29.58) μmol/L, respectively). Serum NO positively correlated with BMI in total subjects (r = 0.585, p<0.001), which this correlation was significant in both male and female groups (r = 0.735, p<0.001 and r = 0.476, p = 0.001, respectively). Serum pentosidine and CML were significantly lower in subjects with higher BMI. Further, BMI showed negative correlations with pentosidine and CML (r = -0.363, p<0.001 and r = -0.484, p<0.001, respectively). There were not any significant differences in serum NO, pentosidine, and CML levels between sex groups. After adjusting the effects of confounders (BMI, sex, age, and waist to hip ratio), serum NO significantly correlated with serum pentosidine and CML (r = -0.319, p = 0.003 and r = -0.433, p<0.001, respectively). It is concluded that higher BMI is accompanied by increased serum NO and suppressed pentosidine and CML.

Circulating markers of nitric oxide homeostasis and cardiometabolic diseases: insights from population-based studies

Emerging data suggest that impaired nitric oxide (NO) homeostasis has a key role in development of cardiometabolic disorders. The association between circulating levels of NO metabolites, i.e. nitrate and nitrite (NOx), and risk of chronic diseases has not yet been fully clarified. This work aims to address epidemiologic aspects of NO metabolism and discusses different physiologic and pathophysiologic conditions influencing circulating NOx. Further, cross-sectional associations of serum NOx with metabolic disorders are described and along the way, potential short-term and long-term power of serum NOx for predicting cardiometabolic outcomes are reviewed. Results from population-based studies show that circulating NOx is affected by aging, smoking habits, pregnancy, menopause status, thyroid hormones, and various pathologic conditions including type 2 diabetes, insulin resistance, hypertension, and renal dysfunction. Lifestyle factors, especially dietary habits, but also smoking habits and the degree of physical activity influence NO homeostasis and the circulating levels of NOx. Elevated serum NOx, due to increased iNOS activity, is associated with increased incidence of metabolic syndrome, different obesity phenotypes, and cardiovascular events.

Dietary nitrate-induced increases in human muscle power: high versus low responders

Maximal neuromuscular power is an important determinant of athletic performance and also quality of life, independence, and perhaps even mortality in patient populations. We have shown that dietary nitrate (NO₃⁻), a source of nitric oxide (NO), improves muscle power in some, but not all, subjects. The present investigation was designed to identify factors contributing to this interindividual variability. Healthy men (n = 13) and women (n = 7) 22–79 year of age and weighing 52.1–114.9 kg were studied using a randomized, double‐blind, placebo‐controlled, crossover design. Subjects were tested 2 h after ingesting beetroot juice (BRJ) either containing or devoid of 12.3 ± 0.8 mmol of NO₃⁻. Plasma NO₃⁻ and nitrite (NO₂⁻) were measured as indicators of NO bioavailability and maximal knee extensor speed (V_max), power (P_max), and fatigability were determined via isokinetic dynamometry. On average, dietary NO₃⁻ increased (P < 0.05) P_max by 4.4 ± 8.1%. Individual changes, however, ranged from −9.6 to +26.8%. This interindividual variability was not significantly correlated with age, body mass (inverse of NO₃⁻ dose per kg), body mass index (surrogate for body composition) or placebo trial V_max or fatigue index (in vivo indicators of muscle fiber type distribution). In contrast, the relative increase in Pmax was significantly correlated (r = 0.60; P < 0.01) with the relative increase in plasma NO₂⁻ concentration. In multivariable analysis female sex also tended (P = 0.08) to be associated with a greater increase in Pmax. We conclude that the magnitude of the dietary NO₃⁻‐induced increase in muscle power is dependent upon the magnitude of the resulting increase in plasma NO₂⁻ and possibly female sex.

Influence of Active Exposure to Tobacco Smoke on Nitric Oxide Status of Pregnant Women

Smoking tobacco can impair proper vascular endothelial functioning. This is exhibited through reduced nitric oxide synthesis as well as activity due to accompanying oxidative stress. We examined the relationship between nitric oxide and markers of oxidative stress/antioxidant defense in serum of smoking and non-smoking pregnant women. Subjects included 99 healthy pregnant women, who were tested for nitric oxide (NO), endothelial (eNOS) and inducible (iNOS) nitric oxide synthase, total oxidant capacity (TOC), and total antioxidant capacity (TAC). NO, eNOS, and TAC serum concentrations were significantly lower (p < 0.005), but iNOS (p < 0.05) and TOC (p < 0.001) were higher in smokers than in non-smokers. Multivariate regression analysis showed associations between NO concentration and eNOS, TAC, and smoking status in the whole group of patients. In the model estimated separately for smokers, the highest impact of eNOS (β = 0.375; p = 0.021) and cotinine (β = −0.323; p = 0.037) was indicated for NO concentration. In the model of non-smokers, eNOS (β = 0.291, p = 0.030) and TAC (β = 0.350; p = 0.015) were important for NO level. Smoking during pregnancy could exacerbate oxidative stress, impair the action of nitric oxide synthases, and adversely affect the balance of oxygen and nitrogen metabolism. Relationships between NO concentrations and TAC in the studied women’s blood can confirm the antioxidant nature of nitric oxide.

Relation of smoking and endothelial dysfunction markers in systemic hypertension

Aim. Assessment of the markers levels of endothelial dysfunction (ED): stable metabolites of nitric oxide (NOx), endothelin-1 (E1), homocysteine (HC), von Willebrand factor (vWF) and tissue plasminogen activator (tPA) in blood plasma of smoker and nonsmoker patients with arterial hypertension (AH) of low and moderate risk, not taking antihypertension therapy regularly.

Material and methods. Totally, 124 AH patients included, 45 males and 79 females, mean age 51,4±6,5 y.o., mean AH duration 7,9±7,3 y. Controls included 35 healthy volunteers (20 males, 15 females). Concentration of NOx in plasma was measured with spectrophotometry, and of vWF, HC, E1 and tPA — with immune enzyme assay.

Results. To evaluate the relation of smoking and ED markers levels, AH patients and controls were selected to subgroups according to smoking status: smoker (35,5%) and non-smoker (64,5%) AH patients; smoker (38%) and non-smoker (62%) controls. In smoker AH patients comparing to non-smoking there were significantly higher concentrations of NOx — 48,2±18,8 mcM/L and 40,3±21,2 mcM/L, respectively (р<0,05), E1 — 1,2±0,16 and 0,6±0,2 fM/L, resp. (р<0,05), HC — 25,7±6,04 and 16,2±6,5 mcM/L, resp. (р<0,05), vWF — 1,39±0,7 and 1,1±0,6 mg/dL, resp (р<0,05) and tPA — 13,05±6,2 and 8,5±6,2 mcM/L, resp. (р<0,05). There was correlation in the AH group, of NOx concentration and smoking (r=0,46, р<0,05), and tobacco smoking duration (r=0,83, р<0,05). Also, there were positive correlations of HC and smoking (r=0,4, p<0,05). In control group smokers had higher HC — 20,7±5,3 and 17,2±4,7 mcM/L, resp. (р<0,05), vWF — 1,3±0,8 and 0,8±0,6 mg/dL, resp. (р<0,05) and tPA — 11,1±6,5 and 6,6±5,2 mcM/L, resp. (р<0,05). There were no significant changes in NOx and E1.

Conclusion. In smokers of both AH and control groups the levels of HC, vWF and tPA were significantly higher in comparison with nonsmokers. In smoker AH patients the mean concentrations of NOx and E1 are higher than in non-smoker patients. Levels of ED are related with not only the fact of smoking itself (р<0,05), but smoking duration (р<0,05).

The Nitrate-Nitrite-Nitric Oxide Pathway: Findings from 20 Years of the Tehran Lipid and Glucose Study

CONTEXT

We describe here the contributions of the Tehran lipid and glucose study (TLGS) to understanding different aspects of the nitrate (NO3)-nitrite (NO2)-nitric oxide (NO) pathway in health and disease.

EVIDENCE ACQUISITION

All English-language documents from the TLGS, focused on NO pathway were searched using the PubMed, Scopus, and Embase databases.

RESULTS

Reference values of serum concentrations of NO metabolites (nitrate+nitrite or NOx) were 11.5 - 76.4, 10.1 - 65.6, and 10.3 - 66.8 μmol/L in men, women, and the total population, respectively. Circulating NOx was affected by age, smoking habits, menopause status, thyroid hormones, and various pathologic conditions. Elevated serum NOx was related to increased incidence of metabolic syndrome (odds ratio (OR) = 1.75, 95% confidence interval (CI) = 1.19 - 2.59), hypertriglyceridemic-waist phenotype (OR = 1.39, 95% CI = 1.05 - 1.93), chronic kidney disease (OR = 1.86, 95% CI = 1.10 - 3.14) in women, and cardiovascular disease (hazard ratio (HR) = 1.35, 95% CI = 1.01 - 1.80] in the total population. In participants with low vitamin C intake, higher intakes of NO2 (≥ 8.77 mg/d) were accompanied with increased risk of diabetes (HR = 2.43, 95% CI = 1.45 - 4.05). A decreased risk of hypertension (OR = 0.58, 95% CI = 0.33 - 0.98) and chronic kidney disease (OR = 0.50, 95% CI = 0.24 - 0.89) was observed in response to higher intakes of NO2.

CONCLUSIONS

Circulating NOx is associated with and could predict the risk of metabolic disorders in a general population. Moreover, dietary NO3/NO2 exposure from usual diets seems to contribute to development of noncommunicable diseases.

Association of plasma nitrite levels with obesity and metabolic syndrome in the Old Order Amish

OBJECTIVES

Plasma nitrite is a metabolite of nitric oxide and reflects endogenous nitric oxide synthase (NOS) activity. Although plasma nitrites were previously linked with obesity and metabolic syndrome (MetS), the direction of association remains inconsistent, possibly due to sample heterogeneity. In a relatively homogeneous population, we hypothesized that nitrite levels will be positively associated with overweight/obesity and MetS.

METHODS

Fasting nitrite levels were measured in 116 Old Order Amish (78% women). We performed age-and-sex-adjusted ancovas to compare nitrite levels between three groups (a) overweight/obese(-)MetS(-), (b) overweight/obese(+)MetS(-) and (c) overweight/obese(+)MetS)(+). Multivariate linear regressions were conducted on nitrite associations with continuous metabolic variables, with successive adjustments for demographics, body mass index, C-reactive protein and neopterin.

RESULTS

Nitrite levels were higher in the obese/overweight(+)MetS(+) group than in the other two groups (p < 0.001). Nitrites were positively associated with levels of triglycerides (p < 0.0001), total cholesterol (p = 0.048), high-density lipoprotein/cholesterol ratio (p < 0.0001) and fasting glucose (p < 0.0001), and negatively correlated with high-density lipoprotein-cholesterol (p < 0.0001). These associations were robust to adjustments for body mass index and inflammatory markers.

CONCLUSION

Further investigation of the connection between obesity/MetS and plasma nitrite levels may lead to novel dietary and pharmacological approaches that ultimately may contribute to reducing the increasing burden of obesity, MetS and cardiovascular morbidity and mortality.

Plasma Nitrate and Incidence of Cardiovascular Disease and All-Cause Mortality in the Community: The Framingham Offspring Study

BACKGROUND

Nitrate is a dietary component as well as an endogenously formed metabolite and source of the signaling molecule nitric oxide. Harmful as well as beneficial effects of nitrate have been advocated. Data regarding the prognostic relevance of plasma nitrate are limited. The aim of this study was to evaluate the prospective association of plasma nitrate with cardiovascular disease (CVD) and all-cause mortality.

METHODS AND RESULTS

We assayed plasma nitrate in 2855 Framingham Offspring Study participants (mean age 59 years, 54% women) by gas chromatography-mass spectrometry and evaluated its association with all-cause mortality and incident CVD. On follow-up (median 17.3 years), 775 participants died and 522 developed new-onset CVD (of 2546 participants free of CVD at baseline). In multivariable models adjusting for standard risk factors, plasma nitrate was associated with an increased risk of death in participants (hazard ratio per unit increase in log-nitrate 1.21; 95% confidence interval, 1.04-1.40 [P=0.015]). The strength of the association was attenuated by additional adjustment for estimated glomerular filtration rate (hazard ratio, 1.16; 95% confidence interval, 1.00-1.35 [P=0.057]). In contrast, no evidence was found for an association of plasma nitrate with incident CVD (multivariable-adjusted hazard ratio per unit increase log-nitrate 1.08; 95% confidence interval, 0.89-1.31 [P=0.42]).

CONCLUSIONS

In our prospective community-based investigation, a higher plasma nitrate concentration was associated with all-cause mortality but not with incident CVD. The association of nitrate with mortality may at least in part be attributable to its association with renal function.

Inducible Nitric Oxide Synthase Polymorphisms and Nitric Oxide Levels in Individuals with Chronic Periodontitis

This study aimed to investigate whether the -1026(A>C)(rs2779249) and +2087(A>G)(2297518) polymorphisms in the NOS2 gene were associated with chronic periodontitis (CP) and with salivary levels of nitrite (NO₂^-) and/or nitrate + nitrite (NOx). A group of 113 mixed-race patients were subjected to periodontal, genetic, and biochemical evaluations (65 CP/48 periodontally healthy subjects). DNA was extracted from oral epithelial cells and used for genotyping by polymerase chain reaction (real-time). Salivary NOx concentrations were determined using an ozone-based chemiluminescence assay. Association of CP with alleles and genotypes of the -1026(A>C) polymorphism was found (X² test, p = 0.0075; 0.0308), but this was not maintained after multiple logistic regression, performed to estimate the effect of covariates and polymorphisms in CP. This analysis demonstrated, after correction for multiple comparisons, that only the female gender was significantly associated with CP. Polymorphisms analyzed as haplotypes were not associated with CP. NOx levels were significantly higher in the control group of heterozygous individuals for both polymorphisms. In conclusion, the female gender was significantly associated with CP, and higher levels of salivary NOx were found in control subjects and associated with the heterozygous state of the NOS2 polymorphisms, reinforcing the potential of NO metabolites as markers of periodontitis status.

Serum levels of nitric oxide and cytokines in smokers at the beginning and after 4months of treatment for smoking cessation

INTRODUCTION

Nitric oxide (NO) modulates inflammatory reactions, having beneficial or toxic effects depending on the concentration. Its elevation can cause proinflammatory effects amplifying the inflammatory process with the participation of cytokines. Smoking has a negative impact on health and is considered one of the risk factors that influence disease development facilitating inflammatory processes.

AIM

To compare the serum concentration of NO and cytokines in smokers at baseline and after 4months of abstinence treatment.

METHODS

Blood samples which were collected to obtain the serum, at baseline and after 4months, were stored at -80°C until analysis. NO was measured by the total dose of nitrite determined by the Greiss method. CBA was the used technique to determine the concentration of cytokines in supernatants serum. The initial and final results of NO, TNF-α, IL-1, IL-6, IL-8, IL-10 and IL-12 that remained after 4months treatment were compared. Wilcoxon test was used to compare the data and Spearman test for correlations between NO and other variables. A significance level of p<0.05 was adopted.

RESULTS

The analysis of NO observed a significant reduction (p=0.001) of the initial median value of 18.80 (3.55-80.01) μmol/L to 8.10 (2.85-14.97) μmol/L after 4months of treatment. There were no significant differences in cytokines from baseline to the end of treatment.

CONCLUSION

The results may not mean harm to the body, but an adaptive process, decreasing the metabolism of abstinents due to the reduction of the use of nicotine.

Nitric oxide production by peritoneal macrophages from aged rats: A short term and direct modulation by citrulline

Citrulline has anti-inflammatory properties and exerts beneficial effects on various impaired functions in aging. However, there are few data on citrulline action on immune function in aged populations. The objective of the study was to evaluate citrulline ability, after in vivo and in vitro administration, to modulate macrophage functions in aged rats and the possible pathways involved. Twenty-one-month-old Sprague-Dawley rats (n = 27) received a citrulline supplementation at 5 g/kg/d for 5 days, or an isonitrogenous diet, and peritoneal macrophages were cultured with or without LPS. In the in vitro study, macrophages from 22-month-old rats (n = 16) were cultured with or without LPS, citrulline and inhibitors of different inflammatory pathways (n = 8/conditions). Nitric oxide (NO) and tumor necrosis factor α (TNFα) production were measured in both in vivo and in vitro studies. Citrulline decreased NO production variability by peritoneal macrophages after in vivo administration (p = 0.0034) and downregulated NO production by 22% after in vitro administration (95% CI: [6%; 35%]; p = 0.0394), without any direct effect on TNFα production. None of the transductional pathways explored seem to be involved. Citrulline slightly modulates NO production in vivo and in vitro, suggesting a possible action through modulation of arginine metabolism in macrophages rather than a direct transductional effect. The pleiotropic effects of citrulline in aging could be due, at least in part, to the anti-inflammatory effect of citrulline.

Solute carrier protein family 11 member 1 (Slc11a1) activation efficiently inhibits Leishmania donovani survival in host macrophages

Visceral leishmaniasis (kala-azar), a life threatening disease caused by L. donovani, is a latent threat to more than 147 million people living in disease endemic South East Asia region of the Indian subcontinent. The therapeutic option to control leishmanial infections are very limited, and at present comprise only two drugs, an antifungal amphotericin B and an antitumor miltefosine, which are also highly vulnerable for parasitic resistance. Therefore, identification and development of alternate control measures is an exigent requirement to control leishmanial infections. In this study, we report that functionally induced expression of solute carrier protein family 11 member 1 (Slc11a1), a transmembrane divalent cationic transporter recruited on the surface of phagolysosomes after phagocytosis of parasites, effectively inhibits Leishmania donovani growth in host macrophages. Further, the increased Slc11a1 functionality also resulted in increased production of NOx, TNF-α and IL-12 by activated macrophages. The findings of this study signify the importance of interplay between Slc11a1 expression and macrophages activation that can be effectively used to control of Leishmania growth and survival.

Association between serum nitric oxide metabolites and thyroid hormones in a general population: Tehran Thyroid Study

Nitric oxide participates in the regulation of thyroid function.

AIMS

The purpose of this study was to determine whether there is an association between serum nitric oxide metabolites (NOx) and free thyroxine (free T4), anti-thyroid peroxidase (anti-TPO), and thyroid-stimulating hormone (TSH) levels.

METHODS

Study subjects were adults, aged ≥20 years, who participated in the Tehran Thyroid Study (TTS). In a cross-sectional study, in the third phase of TTS, serum NOx concentrations were measured in 1974 adult participants; pregnant women and subjects who had chronic diarrhea, cancer, weight loss, and hospitalization within the past 3 months were excluded, as were those taking medicines that affect thyroid function; the remaining 1771 subjects were grouped according to tertiles of free T4, anti-TPO, and TSH. Spearman's correlation coefficients and multivariable linear regression analysis were used to determine the relationship between serum NOx levels and free T4, anti-TPO, and TSH.

RESULTS

Serum NOx levels were negatively correlated with free T4 in men (r = -0.083; p = 0.029). An inverse association between the third tertile of free T4 and NOx levels was found in both non-adjusted (β = -0.095, p = 0.031) and multivariable-adjusted (β = -0.094, p = 0.039) analyses, only in men. After multivariable adjustment, the third tertile of anti-TPO was significantly associated with NOx levels in women (β = -0.067, p = 0.050).

CONCLUSIONS

Based on the result, serum NOx concentration was found to be associated with free T4 in men and anti-TPO in women.

Classification-based data mining for identification of risk patterns associated with hypertension in Middle Eastern population: A 12-year longitudinal study

Hypertension is a critical public health concern worldwide. Identification of risk factors using traditional multivariable models has been a field of active research. The present study was undertaken to identify risk patterns associated with hypertension incidence using data mining methods in a cohort of Iranian adult population.Data on 6205 participants (44% men) age > 20 years, free from hypertension at baseline with no history of cardiovascular disease, were used to develop a series of prediction models by 3 types of decision tree (DT) algorithms. The performances of all classifiers were evaluated on the testing data set.The Quick Unbiased Efficient Statistical Tree algorithm among men and women and Classification and Regression Tree among the total population had the best performance. The C-statistic and sensitivity for the prediction models were (0.70 and 71%) in men, (0.79 and 71%) in women, and (0.78 and 72%) in total population, respectively. In DT models, systolic blood pressure (SBP), diastolic blood pressure, age, and waist circumference significantly contributed to the risk of incident hypertension in both genders and total population, wrist circumference and 2-h postchallenge plasma glucose among women and fasting plasma glucose among men. In men, the highest hypertension risk was seen in those with SBP > 115 mm Hg and age > 30 years. In women those with SBP > 114 mm Hg and age > 33 years had the highest risk for hypertension. For the total population, higher risk was observed in those with SBP > 114 mm Hg and age > 38 years.Our study emphasizes the utility of DTs for prediction of hypertension and exploring interaction between predictors. DT models used the easily available variables to identify homogeneous subgroups with different risk pattern for the hypertension.

Lipid peroxidation, nitric oxide metabolites, and their ratio in a group of subjects with metabolic syndrome

Our aim was to evaluate lipid peroxidation, expressed as thiobarbituric acid-reactive substances (TBARS), nitric oxide metabolites (nitrite + nitrate) expressed as NOx, and TBARS/NOx ratio in a group of subjects with metabolic syndrome (MS). In this regard we enrolled 106 subjects with MS defined according to the IDF criteria, subsequently subdivided into diabetic (DMS) and nondiabetic (NDMS) and also into subjects with a low triglycerides/HDL-cholesterol (TG/HDL-C) index or with a high TG/HDL-C index. In the entire group and in the four subgroups of MS subjects we found an increase in TBARS and NOx levels and a decrease in TBARS/NOx ratio in comparison with normal controls. Regarding all these parameters no statistical difference between DMS and NDMS was evident, but a significant increase in NOx was present in subjects with a high TG/HDL-C index in comparison with those with a low index. In MS subjects we also found a negative correlation between TBARS/NO x ratio and TG/HDL-C index. Considering the hyperactivity of the inducible NO synthase in MS, these data confirm the altered redox and inflammatory status that characterizes the MS and suggest a link between lipid peroxidation, inflammation, and insulin resistance, evaluated as TG/HDL-C index.

The correlation of serum levels of leptin, leptin receptor and NO x (NO 2 (-) and NO 3 (-)) in patients with obstructive sleep apnea syndrome

The aim of this study was to investigate the relations between nitric oxide (NO) and leptin levels in a cohort of untreated adult Obstructive sleep apnea syndrome (OSAS) patients. Between June 1, 2012, and January 1, 2013, we evaluated a total of 58 subjects including 36 OSAS patients and 22 healthy controls, both polysomnographically confirmed. Following the completion of polysomnographic evaluation, serum samples were taken at 08:00. Leptin, leptin receptor, NO2 (-) and NO3 (-) levels were analyzed by commercial ELISA kits. Data analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 16.0 (SPSS Inc., Chicago, IL, USA). There was no statistically significant difference between the OSAS patients and control groups with relation to the demographic parameters and body mass index (p > 0.05). Significantly higher serum leptin and plasma NO levels were found in OSAS patients compared to the controls (p < 0.001). In this study, higher leptin levels which were positively correlated with NO levels in OSAS group may indicate a possible link with increased incidence of airway pathologies in these patients.

Nitric oxide production, systemic inflammation and lipid metabolism in periodontitis patients: possible gender aspect

AIM

Nitric oxide (NO) plays a crucial role in vascular tone regulation and is involved in pathogenesis of periodontitis. In this cross-sectional study, we investigated the serum and saliva levels of NO metabolites in periodontal disease and their relationship with serum C-reactive protein (CRP) levels, lipids metabolism and periodontal disease severity.

MATERIAL AND METHODS

Serum and saliva were collected from non-smoking patients with generalized severe periodontitis (n = 89) and healthy controls (n = 56). Serum and salivary levels of NO metabolites, serum levels of high density lipoproteins (HDL), low density lipoproteins (LDL), triglycerides, cholesterol and CRP were measured. Data were analysed in whole population and in different gender groups.

RESULTS

Periodontitis patients exhibited significantly lower serum and saliva levels of NO metabolites and significantly higher LDL, cholesterol and CRP levels than control group. Similar findings were observed within male but not within female population. Serum NO metabolites levels exhibited significant negative correlation with CRP in whole population and in male population. Significant positive correlation of serum NO metabolite levels with HDL levels was observed in whole population.

CONCLUSION

NO production is reduced in periodontitis, especially in male population. Gender might be an important factor in assessing risk of cardiovascular disease in periodontitis.

Circulating nitrite and nitrate are associated with job-related fatigue in women, but not in men

A recent study indicated that serum nitrite and nitrate (NOx) is inversely associated with general fatigue. The purpose of this study was to confirm the negative association between nitric oxide (NO) and fatigue and to examine whether NO can prevent fatigue caused by job strain. The subjects, 570 workers (272 men and 298 women), answered self-administered questionnaires and underwent a medical examination. Job strain was measured using the Job Content Questionnaire. Fatigue was evaluated using the Profile of Mood States. Venous blood samples were collected after overnight fasting. Plasma NOx concentration was determined by the ozone-based chemiluminescence assay. Plasma NOx levels were significantly (p < 0.05) negatively associated with fatigue even after adjustment for job strain and potential confounders in women, but not in men. Significant (p < 0.05) interactions showed that, in women, as the level of the job strain worsened, fatigue was exacerbated, but the plasma NOx seemed to buffer the association, even after adjustment for potential confounders and the interaction between job strain and vegetable intake. In women, NO seemed to be inversely associated with fatigue and to buffer the association between job strain and fatigue, but not in men.

Reactive nitrogen and oxygen species in anticoagulated blood of healthy sheep

BACKGROUND

Little or no study has been done to compare the indices of 'nitrosative' and 'oxidative' stresses, especially in terms of correlation and the possible differential effects of the chelating agents.

OBJECTIVE

This preliminary study investigated possible correlations between the indices of reactive nitrogen species (RNS) and reactive oxygen species (ROS) in blood, effect of anticoagulated-blood tubes, and impact of blood-clotting pathways.

METHODS

Thirty blood samples from sheep were collected into ethylenediamine tetraacetic acid (EDTA) and citrate tubes at the Berrima Veterinary Laboratory using their standard protocol. Nitrosative and oxidative stress indices were then measured and correlation analyses performed.

RESULTS

The ROS and RNS indices were weakly correlated (r > 0.2; p < 0.05) with each other from the EDTA sample, but not from citrated blood. None of the nitrosative or oxidative stress biomarkers was significantly associated with changes in the prothrombin time. The activated partial thromboplastin time showed statistically significant association with some oxidative stress indices (catalase and malondialdehyde), but with none of the nitrosative stress indices. Further, all measured parameters were higher in EDTA than in citrate blood (p < 0.0001).

CONCLUSION

The choice of anticoagulated blood tube could affect the measures of nitrosative stress indices and may impact on the potential correlations between nitrosative versus oxidative stress biomarkers. Perhaps the suggestion that EDTA is better than citrate for hematological anticoagulant studies should be considered for nitrosative and oxidative stress studies.

High serum nitric oxide metabolites and incident metabolic syndrome

BACKGROUND

Endothelial dysfunction, synonymous with reduced biological activity of nitric oxide, is related to all cardiovascular risk factors. Association between metabolic syndrome and nitric oxide metabolites (nitrite + nitrate = NO(x)) has been previously shown in cross-sectional studies. The aim of this study was to determine the ability of serum NO(x) levels in predicting the incidence of metabolic syndrome in a population-based study.

METHODS

Serum NO(x) levels measured in 2098 adult subjects, participants of Tehran Lipid and Glucose Study, without metabolic syndrome at baseline. After 3.3 years follow-up, logistic regression analysis was used to calculate the odds ratio (OR) and 95% confidence interval for developing metabolic syndrome, with serum NO(x) quartiles as independent variables.

RESULTS

Incident metabolic syndrome was diagnosed in 23.0% of men and 16.3% of women after 3.3 years. Age-adjusted risk for developing metabolic syndrome in women who had higher NO(x) values (above 75th percentile vs. lower 75th percentile) at baseline, was significantly higher [OR: 1.59 (1.11-2.27), p = 0.011]; OR remained significant after multivariable-adjustment including adjustment for components of metabolic syndrome [OR: 1.75 (1.19-2.59), p = 0.005]. Serum NO(x) could not predict the incidence of metabolic syndrome in men.

CONCLUSIONS

High serum NO(x) level is an independent predictor of incident metabolic syndrome in women, but not in men, a finding which presents serum NO(x) level as a potential biomarker for assessing cardiometabolic disturbances.

Evaluation of nitric oxide metabolites in a group of subjects with metabolic syndrome

AIM

To evaluate the concentration of metabolites (NO(2)(-), NO(3)(-)) of nitric oxide (NO) in metabolic syndrome (MS).

MATERIALS AND METHODS

We enrolled 106 subjects (45 women and 61 men) with MS of which 43 (14 women and 27 men) with diabetes mellitus and 63 (31 women and 32 men) without diabetes mellitus, and 54 subjects (19 women and 35 men) as control group. The nitric oxide metabolites (nitrite+nitrate=NOx) were evaluated employing the Griess reagent.

RESULTS

In the whole group of MS subjects was evident, in comparison with control group, a significant increase in NOx. The same finding was also present between control group and diabetic subjects with MS and between control group and nondiabetic subjects with MS. No difference was observed between the two subgroups (diabetic and nondiabetic subjects with MS) about NOx. Contrasting information were obtained examining the linear regression among NOx, age, anthropometric profile, blood pressure values and glycometabolic pattern of subjects with MS.

CONCLUSIONS

In MS subjects we found a significant increase in NOx not influenced by diabetes mellitus. The NOx is a parameter that must be considered in MS keeping in mind that its behavior is related to chronic inflammation that accompanies this clinical condition.

Plasma and exhaled breath condensate nitrite-nitrate level in relation to environmental exposures in adults in the EGEA study

This study evaluated the associations between biological markers in the nitrate-nitrite-NO pathway and four environmental exposures among subjects examined in the second survey (2003-2007) of the French Epidemiological study on Genetics and Environment of Asthma (EGEA). Total nitrite and nitrate (NO(2)(-) /NO(3)(-)) levels were measured both in plasma and in exhaled breath condensate (EBC) in 949 adults. Smoking, diet and exposure to chlorine products were assessed using standardized questionnaires. Exposure to air pollutants was estimated by using geostatistical models. All estimates were obtained with generalized estimating equations for linear regression models. Median levels of NO(2)(-)/NO(3)(-) were 36.3 μM (1st-3rd quartile: 25.7, 51.1) in plasma and 2.0 μmol/mg proteins (1st-3rd quartile 0.9, 3.9) in EBC. After adjustment for asthma, age, sex and menopausal status, plasma NO(2)(-)/NO(3)(-) level increased with leafy vegetable consumption (above versus below median=0.04 (95%CI: 0.001, 0.07)) and decreased in smokers (versus non/ex-smokers=-0.08 (95%CI: -0.11, -0.04). EBC NO(2)(-)/NO(3)(-) level decreased in smokers (-0.08 (95%CI: -0.16, -0.001)) and with exposure to ambient O(3) concentration (above versus below median=-0.10 (95%CI: -0.17, -0.03)). Cured meat, chlorine products, PM(10) and NO(2) concentrations were not associated with NO(2)(-)/NO(3)(-) levels. Results suggest that potential modifiable environmental and behavioral risk factors may modify NO(2)(-)/NO(3)(-) levels in plasma and EBC according to the route of exposure.

Endothelial nitric oxide synthase (G894T) gene polymorphism in a random sample of the Egyptian population: comparison with myocardial infarction patients

AIM

The aim of this study was to detect endothelial nitric oxide synthase (eNOS) Glu298Asp gene variants in a random sample of the Egyptian population, compare it with those from other populations, and attempt to correlate these variants with serum levels of nitric oxide (NO). The association of eNOS genotypes or serum NO levels with the incidence of acute myocardial infarction (AMI) was also examined.

METHODS

One hundred one unrelated healthy subjects and 104 unrelated AMI patients were recruited randomly from the 57357 Hospital and intensive care units of El Demerdash Hospital and National Heart Institute, Cairo, Egypt. eNOS genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Serum NO was determined spectrophotometrically.

RESULTS

The genotype distribution of eNOS Glu298Asp polymorphism determined for our sample was 58.42% GG (wild type), 33.66% GT, and 7.92% TT genotypes while allele frequencies were 75.25% and 24.75% for G and T alleles, respectively. No significant association between serum NO and specific eNOS genotype could be detected. No significant correlation between eNOS genotype distribution or allele frequencies and the incidence of AMI was observed.

CONCLUSION

The present study demonstrated the predominance of the homozygous genotype GG over the heterozygous GT and homozygous TT in random samples of Egyptian population. It also showed the lack of association between eNOS genotypes and mean serum levels of NO, as well as the incidence of AMI.

Sex differences in salt sensitivity to nitric oxide dependent vasodilation in healthy young adults

Dietary sodium and blood pressure regulation differs between normotensive men and women, an effect which may involve endothelial production of nitric oxide (NO). Therefore, we tested the hypothesis that differences in the NO component of endothelium-dependent vasodilation between low and high dietary sodium intake depend on sex. For 5 days prior to study, healthy adults consumed a controlled low-sodium diet (10 mmol/day, n = 30, mean age ± SE: 30 ± 1 yr, 16 men) or high-sodium diet (400 mmol/day, n = 36, age 23 ± 1 yr, 13 men). Forearm blood flow (FBF, plethysmography) responses to brachial artery administration of acetylcholine (ACh, 4 μg·100 ml tissue(-1)·min(-1)) were measured before and after endothelial NO synthase inhibition with N(G)-monomethyl-l-arginine (l-NMMA, 50 mg bolus + 1 mg/min infusion). The NO component of endothelium-dependent dilation was calculated as the response to ACh before and after l-NMMA accounting for changes in baseline FBF: [(FBF ACh - FBF baseline) - (FBF ACh(L-NMMA) - FBF baseline(L-NMMA))]. This value was 5.7 ± 1.3 and 2.5 ± 0.8 ml·100 ml forearm tissue(-1)·min(-1) for the low- and high-sodium diets, respectively (main effect of sodium, P = 0.019). The sodium effect was larger for the men, with values of 7.9 ± 2.0 and 2.2 ± 1.4 for men vs. 3.1 ± 1.3 and 2.7 ± 1.0 ml·100 ml forearm tissue(-1)·min(-1) for the women (P = 0.034, sex-by-sodium interaction). We conclude that the NO component of endothelium-dependent vasodilation is altered by dietary sodium intake based on sex, suggesting that endothelial NO production is sensitive to dietary sodium in healthy young men but not women.

Level of serum IL-12 and its correlation with endothelial dysfunction, insulin resistance, proinflammatory cytokines and lipid profile in newly diagnosed type 2 diabetes

AIM

This study was an attempt to evaluate and correlate serum interleukin-12 (IL-12) with different circulating markers in newly diagnosed type-2 diabetes mellitus (T2DM) for possible progression of atherosclerosis.

METHODS

For this study, we recruited 1968 family members of diabetics and 349 had abnormal glucose. Out of 349 subjects, 197 were T2DM as per American Diabetes Association guidelines and further investigated for cardiovascular abnormalities. 63 T2DM have high sensitive C-reactive protein (hsCRP)>3.0mg/l and cardiovascular complications. Overall, 150 subjects, 50 healthy, 50 T2DM (D1) and 50 T2DM with cardiovascular complications (D2) were enrolled and investigated for soluble markers.

RESULTS

The levels of serum glucose, proinflammatory cytokines (IL-6, IL-12, tumor necrosis factor), endothelial dysfunction markers [vascular cell adhesion molecule-1 (VCAM-1), inter-cellular adhesion molecule-1 (ICAM-1), nitric oxide] and lipid abnormality were highest in D2 group. Correlation and regression study showed that IL-12 was dependent on hsCRP, insulin resistance, VCAM-1, ICAM-1 and lipids. The multivariate stepwise regression analysis demonstrates that hsCRP contributes significantly for variance of IL-12.

CONCLUSION

This study reveals that, even first-time diagnosis of T2DM, subjects with higher insulin resistance and abnormal lipids have elevated IL-12, endothelial dysfunction and proinflammatory markers. Further increased hsCRP enhance IL-12 which up-regulate cardiovascular disease progression.

Serum nitric oxide concentrations in patients with multiple sclerosis and patients with epilepsy

Nitric oxide (NO), a neurotransmitter and a free radical, has been purported to be involved in numerous neurological diseases. We investigated the serum nitric oxide concentration in 30 patients with multiple sclerosis (MS), in 30 patients with epilepsy and in 30 control subjects. The aim was also to determine whether a statistically significant difference in serum NO concentrations exists between the groups of interest. The total serum nitric oxide concentration was measured using the Griess reaction after reducing nitrates to nitrites with elemental zinc. In the group multiple sclerosis, the mean NO concentrations were X ± SEM = 31.02 ± 1.79 μmol/l, in the control group X ± SEM = 25.31 ± 1.44 μmol/l and in the group epilepsy X ± SEM = 22.51 ± 1.28 μmol/l. Student's t test showed a statistically significant difference between subjects with multiple sclerosis and the control group (p = 0.013), as well as between the groups multiple sclerosis and epilepsy (p = 0.0002). This data confirms that NO may play an important role in the pathogenesis of multiple sclerosis, whereas its role in epilepsy still remains unclear.