Search results for "nitrate"
showing 10 items of 580 documents
Risk assessment and monitoring programme of nitrates through vegetables in the Region of Valencia (Spain)
2017
This study was carried out to determine current levels of nitrate in vegetables marketed in the Region of Valencia (Spain) and to estimate the toxicological risk associated with their intake. A total of 533 samples of seven vegetable species were studied. Nitrate levels were derived from the Valencia Region monitoring programme carried out from 2009 to 2013 and food consumption levels were taken from the first Valencia Food Consumption Survey, conducted in 2010. The exposure was estimated using a probabilistic approach and two scenarios were assumed for left-censored data: the lower-bound scenario, in which unquantified results (below the limit of quantification) were set to zero and the up…
Nitric Oxide Production and Arachidonic Acid Metabolism in Platelet Membranes of Coronary Heart Disease Patients with and without Diabetes
2001
<i>Aim:</i> To evaluate the levels of nitrite (NO<sup>–</sup><sub>2</sub>) and nitrate (NO<sup>–</sup><sub>3</sub>) ions and the incorporation of [<sup>3</sup>H]arachidonic acid (AA) into phospholipids of platelet membranes from coronary artery disease (CAD) patients with and without diabetes (NIDDM). <i>Subjects and Methods:</i> Eighteen CAD patients (group A), 18 CAD patients with NIDDM (group B), and 20 healthy controls (group C) without dyslipidemia, peripheral vascular disease and hypertension were included in the study. The groups were matched for age, sex and body mass index. The diagnosis of CAD was …
Correlation of nitric oxide and atrial natriuretic peptide changes with altered cGMP homeostasis in liver cirrhosis.
2005
: Background: Cyclic GMP (cGMP) concentration is increased in plasma of patients with liver cirrhosis. Three possible mechanisms may contribute: increased cGMP synthesis by soluble (activated by nitric oxide), or particulate (activated by atrial natriuretic peptide (ANP)) guanylate cyclase or increased release from cells. Aim: The aim of this work was to analyze the possible contributors to increased plasma cGMP and to assess whether changes in the parameters of the system vary with the degree of liver disease (Child Pugh score) or by the presence of ascites. Methods: We measured cGMP in plasma and lymphocytes, soluble guanylate cyclase activation by nitric oxide in lymphocytes, nitrates an…
Lipid Peroxidation, Nitric Oxide Metabolites, and Their Ratio in a Group of Subjects with Metabolic Syndrome
2014
Our aim was to evaluate lipid peroxidation, expressed as thiobarbituric acid-reactive substances (TBARS), nitric oxide metabolites (nitrite + nitrate) expressed asNOx, and TBARS/NOxratio 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 andNOxlevels and a decrease in TBARS/NOxratio in comparison with normal controls. Regarding all these …
Pentaerythrityl Tetranitrate and Nitroglycerin, but not Isosorbide Mononitrate, Prevent Endothelial Dysfunction Induced by Ischemia and Reperfusion
2007
Background— Short term exposure to nitroglycerin (GTN) has protective properties that are similar to ischemic preconditioning. Whether other organic nitrates such as pentaerithrityl tetranitrate (PETN) and isosorbide mononitrate (ISMN) have similar protective effects has not been explored. Methods and Results— In a randomized, parallel, double blind, controlled trial, 37 healthy young volunteers received no therapy (n=10), transdermal GTN 1.2 mg for 2 hours (n=9), PETN 80 mg (n=9), or ISMN 40 mg (n=9). Twenty-four hours later, endothelium-dependent flow-mediated vasodilation (FMD) was measured before and after local exposure to ischemia and reperfusion (IR). In the no therapy group, IR blu…
Nitric oxide metabolites (nitrite and nitrate) in young patients with recent acute myocardial infarction
2008
Nitric oxide (NO) has a role in the pathophysiology of acute and chronic cardiovascular events. We studied the plasma concentration of NO stable end products (nitrite and nitrate - NO x ) in 43 patients aged <46 years, with recent acute myocardial infarction (AMI). The evaluation was effected at the initial stage, after 3 and 12 months. We subdivided the patients into subgroups according to the number of the main cardiovascular risk factors and to the extent of coronary disease. In the whole group the NO x concentration was initially increased and progressively decreased after 3 and 12 months, remaining at both times significantly higher than in control subjects. The patients with more risk…
Nitric oxide metabolites and erythrocyte deformability in a group of subjects with obstructive sleep apnea syndrome
2014
Our aim was to evaluate nitric oxide metabolites (nitrite and nitrate), expressed as NOx, and erythrocyte deformability, expressed as elongation index, in a group of subjects with obstructive sleep apnea syndrome (OSAS). We enrolled 48 subjects (36 men and 12 women; mean age 50.3 ± 14.68 yrs) with OSAS diagnosed after a 1-night cardiorespiratory sleep study. OSAS severity was assessed evaluating the apnea/hypopnea index (AHI) and subjects were subdivided in two subgroups: Low (L = AHI 30). NOx was examined converting nitrate into nitrite with a nitrate reductase and then assessing nitrite with spectrophotometry after the addition of Griess reagent. The elongation index was obtained using th…
Simultaneous assessment of endothelial function, nitric oxide synthase activity, nitric oxide-mediated signaling, and oxidative stress in individuals…
2007
Abstract Background: Endothelial function is impaired in hypercholesterolemia and atherosclerosis. Based on mostly indirect evidence, this impairment is attributed to reduced synthesis or impaired biological activity of endothelium-derived nitric oxide (NO). It was the aim of this study to directly estimate and compare whole-body NO production in normo- and hypercholesterolemia by applying a nonradioactive stable isotope dilution technique in vivo. Methods: We enrolled 12 normocholesterolemic and 24 hypercholesterolemic volunteers who were all clinically healthy. To assess whole-body NO synthesis, we intravenously administered l-[guanidino-(15N2)]-arginine and determined the urinary excreti…
Behaviour of nitric oxide metabolites in unprofessional athletes before and after a cardiopulmonary test.
2010
Physical training causes an increase in nitric oxide (NO) production [2, 3, 8, 9] and this datum explains the link between exercise and endothelium and seems to demonstrate how regular training upregulates eNOS expression, although it is not sure if this upregulation is due to shear stress or metabolic factors [3]. However, it must be underlined that besides to be directly influenced by exogenous NO, erythrocytes express a functional NOS [5, 6, 11, 13] that raises the circulation NO pool. The literature data describe that an 8-week exercise training induced an increase in plasma levels of NO metabolites (NOx), that persisted four weeks after interruption of training [8]. A similar trend was…
Tolerance to nitroglycerin-induced preconditioning of the endothelium: a human in vivo study
2009
Damage and dysfunction of the vascular endothelium critically influence clinical outcomes after ischemia and reperfusion (I/R). Brief exposure to organic nitrates can protect the vascular endothelium from I/R injury via a mechanism that is similar to ischemic preconditioning and is independent of hemodynamic changes. The clinical relevance of these protective effects clearly depends on whether they can be sustained over time. Twenty-four healthy (age 25–32) male volunteers were randomized to receive 1) transdermal nitroglycerin (GTN; 0.6 mg/h) administered for 2 h on 1 day only, 2) transdermal GTN for 2 h/day for 7 days, or 3) continuous therapy with transdermal GTN for 7 days. Eight volunt…