An AIE-based fluorescent probe to detect peroxynitrite levels in human serum and its cellular imaging

An AIE-based fluorescent probe was designed to evaluate peroxynitrite levels in complex biological samples. The newly synthesized hydrazone-conjugated probe fluoresces strongly in the presence of peroxynitrite. Clinically, the peroxynitrite levels can be measured in human serum and cellular mitochondria with an LOD of 6.5 nM by fluorescence imaging in vitro.

Reduction of peroxynitrite by some manganoporphyrins of AEOL series: DFT approach with dispersion correction and NBO analysis

The AEOL series of manganoporphyrins (MnP; AEOL compounds were named by US Aeolus pharmaceuticals) designed as superoxide dismutase mimic are well-known for their powerful catalytic activity to neutralize reactive oxygen and nitrogen species. Reductive oxygen atom cleavage from peroxynitrite (ONOO^-) to form NO₂ in aqueous solution by some AEOL compounds (AEOL-10113, AEOL-10150, AEOL-11114 and AEOL-11203) was studied by DFT/M06-2X computations with D3 dispersion correction and gCP (geometrical counterpoise correction) for basis set superposition error. DFT computation showed that AEOL-10150 can form the most stable association complex {MnP^…OONO} among four AEOL models. AEOL-10150 complex with ONOO^- has the lowest deformation energy. In AEOL compounds and their association complexes with ONOO^-, Mn atom prefered the high spin state (S = 2) to the intermediate spin state (S = 1). Natural bond orbital analysis showed that electron transfer from the most negative oxygen atom in ONOO^- to Mn atom in MnP has the biggest interaction energy among all kinds of donor-acceptor interactions between ONOO^- and MnP.

The changes in dynamics of ornithine cycle components levels during the acute period of Polytrauma

OBJECTIVE

Introduction: Polytrauma or multiple organ damage is associated with shock and lead to systemic inflammation, oxidative stress and endothelial dysfunction. A severe mechanical injury causes an increased proinflammatory mediators and cytokines levels. Among them, the overproduction of nitric oxide and its oxidation products play a key role in tissue damage. The aim: To evaluate the changes in dynamics of some ornithine cycle components levels during acute period of polytrauma.

PATIENTS AND METHODS

Materials and methods: We measured standard biomechanical parameters and serum levels of NO, sum of nitrite and nitrate (NOx), L-arginine, arginase, and peroxynitrite. According to the ISS, the study included patients with moderate (n=15) to severe (n=15) polytrauma.

RESULTS

Results: In 24 hours after polytrauma on the background of intensive care, it was observed significant increasing of NO, NOx, and arginase levels (severe cases) with decreasing of L-arginine and peroxynitrite levels.

CONCLUSION

Conclusions: Elevated NO and NOx serum levels in patients with polytrauma is associated with increasing of arginase activity with decreasing of L-arginine and peroxynitrite levels on the background of intensive care.

Low SOD activity is associated with overproduction of peroxynitrite and nitric oxide in patients with acute coronary syndrome

OBJECTIVE

The present study was undertaken to evaluate the variation of the oxidative/nitrosative stress status in a population of subjects; with acute coronary syndrome (ACS), and examine its possible implication in plaque rupture which is the main mechanism in the pathophysiology of ACS.

PATIENTS AND METHODS

We made this study on 50 men with ACS and 50 age and sex matched healthy controls. Nitrosative/oxidative stress markers including; nitric oxide, superoxide anion levels, superoxide dismutase (SOD) activity and peroxynitrite levels were evaluated in blood samples of patients and controls.

RESULTS

Compared with healthy subjects, coronary patients had significantly higher nitric oxide, peroxynitrite and superoxide anion concentrations in both plasma and erythrocytes associated to significant decrease of SOD activity. Erythrocytes peroxynitrite concentration was negatively correlated with the antioxidant enzyme activity (SOD).

CONCLUSION

Our results show a significant accumulation of both intracellular and plasma pro-oxidants with a concomitant decrease in the SOD scavenging activity in ACS patients. Both seem to be associated with plaque rupture and ischemia observed in ACS.

The effect of pre-dive ingestion of dark chocolate on endothelial function after a scuba dive

OBJECTIVE

The aim of the study was to observe the effects of dark chocolate on endothelial function after scuba diving.

METHODS

Forty-two male scuba divers were divided into two groups: a control (n=21) and a chocolate group (n=21). They performed a 33-metres deep scuba-air dive for 20 minutes in a diving pool (Nemo 33, Brussels). Water temperature was 33⁰C. The chocolate group ingested 30 g of dark chocolate (86% cocoa) 90 minutes before the dive. Flow-mediated dilatation (FMD), digital photoplethysmography and nitric oxide (NO) and peroxynitrites (ONOO-) levels were measured before and after the scuba dive in both groups.

RESULTS

A significant decrease in FMD was observed in the control group after the dive (91±7% (mean±95% confidence interval) of pre-dive values; P<0.001) while it was increased in the chocolate group (105±5% of pre-dive values; P<0.001). No difference in digital photoplethysmography was observed between before and after the dives. No variation of circulating NO level was observed in the control group whereas an increase was shown in the chocolate group (154±73% of pre-dive values; P=0.04). A significant reduction in ONOO- was observed in the control group (84±12% of pre-dive values; P=0.003) whereas no variation was shown after the dive with chocolate intake (100±28% of pre-dive values; ns).

CONCLUSIONS

Ingestion of 30 g of dark chocolate 90 minutes before scuba diving prevented post-dive endothelial dysfunction, as the antioxidants contained in dark chocolate probably scavenge free radicals.

Increased oxidative stress and altered levels of nitric oxide and peroxynitrite in Tunisian patients with chronic obstructive pulmonary disease: correlation with disease severity and airflow obstruction

This study was aimed to evaluate the oxidant-antioxidant imbalance in the pathogenesis of chronic obstructive pulmonary disease (COPD) in Tunisians. We assessed 16 parameters related to the oxidative status that include malondialdehyde (MDA), total protein carbonyls (PCs), and advanced oxidation protein products (AOPP). We also examined the activity of glutathione peroxydase (GSH-Px), catalase, and superoxide dismutase (SOD) in the plasma and erythrocytes. Levels of total thiols, reduced glutathione (GSH), total antioxidant status (TAS), hydrogen peroxide, ascorbic acid, iron, and protein sulfhydryls were determined using spectrophotometry. We also evaluated the level of nitric oxide (NO) and peroxynitrite in plasma from COPD patients and healthy controls. Estimation of DNA damage was determined using the comet assay. Pulmonary functional tests were performed by body plethysmography. Levels of MDA, PC, DNA damage, and AOPP were significantly increased while total thiols, GSH, and TAS were decreased in COPD patients. GSH-Px activity was higher in COPD patients while no difference was found for catalase and SOD. We also observed a lower level of NO and peroxynitrite in COPD patients. Decreased levels of peroxynitrite were found to correlate with disease progression, as well as with forced expiratory volume in 1 s/forced vital capacity among COPD patients. Multivariate analysis revealed that NO is associated with pathological pathways that help to predict patient outcome independently of the degree of airflow obstruction. These results indicate the presence of a systemic oxidative stress and highlight the importance of NO and peroxynitrite as major effectors in COPD development and airflow obstruction.

Bioluminescent detection of peroxynitrite with a boronic acid-caged luciferin

Peroxynitrite, a highly reactive biological oxidant, is formed under pathophysiologic conditions from the diffusion-limited reaction of nitric oxide and superoxide radical anion. Peroxynitrite has been implicated as the mediator of nitric oxide toxicity in many diseases and as an important signaling disrupting molecule (L. Liaudet et al., Front. Biosci.14, 4809-4814, 2009) [1]. Biosensors effective at capturing peroxynitrite in a specific and fast enough manner for detection, along with readouts compatible with in vivo studies, are lacking. Here we report that the boronic acid-based bioluminescent system PCL-1 (peroxy-caged luciferin-1), previously reported as a chemoselective sensor for hydrogen peroxide (G.C. Van de Bittner et al., Proc. Natl. Acad. Sci. USA107, 21316-21321, 2010) [2], reacts with peroxynitrite stoichiometrically with a rate constant of 9.8±0.3×10(5)M(-1)s(-1) and a bioluminescence detection limit of 16nM, compared to values of 1.2±0.3M(-1)s(-1) and 231nM for hydrogen peroxide. Further, we demonstrate bioluminescent detection of peroxynitrite in the presence of physiological competitors: carbon dioxide, glutathione, albumin, and catalase. We also demonstrate the utility of this method to assess peroxynitrite formation in mammalian cells by measuring peroxynitrite generated under normal culture conditions after stimulation of macrophages with bacterial endotoxin lipopolysaccharide. Thus, the PCL-1 method for measuring peroxynitrite generation shows superior selectivity over other oxidants under in vivo conditions.

[Oxygen-binding capacities of hemoglobin and nitric oxide]

The analysis of the literature and our own results indicates that a nitric oxide carries out a role the allosteric effector of hemoglobin, changing its affinity to oxygen and defining a condition of oxygen transport blood function. It is important point for modification of functional properties of hemoglobin and its participation in the flow of oxygen in tissues, which plays an important role in development of disadaption reactions at stress and decreased bioactivity of the nitric oxide at the endothelial dysfunction. These findings give possiblity to creat the new ways to correct hypoxical conditions through influence on oxygen-binding properties of the blood and activity of L-arginin-NO system.

Nitric oxide and peroxynitrite serum levels in Parkinson's disease: correlation of oxidative stress and the severity of the disease

BACKGROUND

Nitric oxide (NO) and its toxic product peroxynitrite contribute to oxidative stress and neurodegeneration in Parkinson's disease (PD). The relationship of serum levels of these oxidants with the severity of the disease [evaluated by the Unified Parkinson's Disease Rating Scale (UPDRS)] is not established.

AIM

This study was designed to evaluate whether patients with PD had higher NO and peroxynitrite serum level or not.

PATIENTS AND METHODS

Fifty eight patients with PD and 15 healthy volunteers entered this study. The concentrations of serum NO and peroxynitrite were assayed and their correlation with the UPDRS score was assessed.

RESULTS

Mean serum NO levels in patient group was 29.8 ± 21.631 versus 7.49 ± 2.573 in control group, which was significantly higher in patients (p ≤ 0.0001). Peroxynitrite levels in patient and control groups were 7.37±3.501 µmol/L and 3.94 ±1.389 µmol/L respectively. Patients had a significantly higher peroxynitrite level (p = 0.0004).

CONCLUSIONS

Higher levels of NO and peroxynitrite leads to higher UPDRS scores. It seems since current PD treatments do not affect the pathology of the disease, using drugs that exert neuroprotective properties should be considered for the treatment of PD in order to prevent further neuronal cell loss.  

Increased oxidized low-density lipoprotein causes blood-brain barrier disruption in early-onset preeclampsia through LOX-1

Early-onset preeclampsia (EPE) is a severe form of preeclampsia that involves life-threatening neurological complications. However, the underlying mechanism by which EPE affects the maternal brain is not known. We hypothesized that plasma from women with EPE increases blood-brain barrier (BBB) permeability vs. plasma from women with late-onset preeclampsia (LPE) or normal pregnancy (NP) and investigated its underlying mechanism by perfusing cerebral veins from nonpregnant rats (n=6-7/group) with human plasma from women with EPE, LPE, or NP and measuring permeability. We show that plasma from women with EPE significantly increased BBB permeability vs. plasma from women with LPE or NP (P<0.001). BBB disruption in response to EPE plasma was due to a 260% increase of circulating oxidized LDL (oxLDL) binding to its receptor, LOX-1, and subsequent generation of peroxynitrite (P<0.001). A rat model with pathologically high lipid levels in pregnancy showed symptoms of preeclampsia, including elevated blood pressure, growth-restricted fetuses, and LOX-1-dependent BBB disruption, similar to EPE (P<0.05). Thus, we have identified LOX-1 activation by oxLDL and subsequent peroxynitrite generation as a novel mechanism by which disruption of the BBB occurs in EPE. As increased BBB permeability is a primary means by which seizure and other neurological symptoms ensue, our findings highlight oxLDL, LOX-1, and peroxynitrite as important therapeutic targets in EPE.

Improvement of intradialytic hypotension in diabetic hemodialysis patients using vitamin E-bonded polysulfone membrane dialyzers

Currently, there are no detailed reports on the effects of vitamin E-bonded polysulfone (PS) membrane dialyzers on intradialytic hypotension (IDH) in diabetic hemodialysis (HD) patients. This study was designed to evaluate changes in intradialytic systolic blood pressure (SBP) using "VPS-HA" vitamin E-bonded super high-flux PS membrane dialyzers. The subjects were 62 diabetic HD patients whose intradialytic SBP fell by more than 20%. Group A comprised patients who required vasopressors to be able to continue treatment or who had to discontinue therapy due to their lowest intradialytic SBP being observed at 210 min (28 patients). Group B comprised patients who showed no symptoms and required no vasopressors but showed a gradual reduction in blood pressure, with the lowest intradialytic SBP seen at the end of dialysis (34 patients). The primary outcome was defined as the lowest intradialytic SBP after 3 months using VPS-HA. Secondary outcomes included changes in the following: lowest intradialytic diastolic blood pressure, pulse pressure, pulse rate, plasma nitric oxide and peroxynitrite, serum albumin, and hemoglobin A1c. Group A's lowest intradialytic SBP had significantly improved at 3 months (128.0 ±  25.1 mm Hg vs. 117.1 ± 29.2 mm Hg; P = 0.017). Group B's lowest intradialytic SBP had significantly improved at 1 month (134.4 ± 13.2 mm Hg vs. 121.5 ± 25.8 mm Hg; P =  0.047) and 3 months (139.1 ± 20.9 mm Hg vs. 121.5 ±  25.8 mm Hg; P = 0.011). We conclude that VPS-HA may improve IDH in diabetic HD patients.

Assessment of nitrogen radicals and their scavenging activity in patients with end-stage renal failure

Reactive oxygen species are implicated in cardiovascular disease in patients with chronic renal failure (CRF). This study is aimed to assess the nitrogen radicals in patients with end-stage renal failure (ESRF) referred for peritoneal dialysis. A total of 36 patients with estimated creatinine clearance ≤ 15 mL/min were recruited from the Dialysis Unit at Al-Yarmouk Teaching Hospital in Baghdad, Iraq during 2009, and enrolled into the study. The main causes of CRF were hypertension and diabetes mellitus. The median levels of serum nitric oxide and peroxynitrite were 300 and 152 μmol, respectively. Nitric oxide was not detected in the sera of 10 patients. The sera of 12 patients showed ability to scavenge in vitro, the nitric oxide released by sodium nitroprusside. Significant inverse correlation was found between serum peroxynitrite and either systolic (r = -0.402) or diastolic (r = -0.387) blood pressure. Our study shows that production of nitrogen radicals is enhanced in ESRF and it is accompanied by limited activity of scavenging nitric oxide.

[Nitric oxide system in blood of newborn infants at elevated risk of perinatal pathology]

The study was designed to evaluate activity of the blood nitric oxide (NO) system in newborns at high risk of perinatal pathology. The observed rise in NO production should be regarded as a compensatory and adaptive reaction facilitating the maintenance of microcirculation and hemodynamics in organs and their systems of newborn infants. The inter-relation and inter-dependence between NO levels and enzymatic activities (NOS, HP, O2-, ONOO-, and SOD) make up an integral pathogenetic mechanism determining severity and progress of affection of vitally important organs and systems as well as associated clinical symptoms in full-term and premature infants at high perinatal risk.

Endothelial nitric oxide synthase is up-regulated in the umbilical cord in pregnancies complicated with intrauterine growth retardation

BACKGROUND

NO and NO synthases (NOS) play an important role in the physiology of the fetomaternal blood circulation, although their expression in pathological conditions is unclear. Intrauterine growth retardation (IUGR) is a disorder most probably caused by abnormality of the fetomaternal bloodflow.

MATERIALS AND METHODS

The expression of endothelial NOS (ecNOS) from arteria umbilicalis and the nitrite and peroxynitrite level of umbilical blood were determined. Major consequences of peroxynitrite toxicity are lipid peroxidation and glutathione depletion; these parameters were also measured. Finally, superoxide dismutase (SOD) activity was assayed to evaluate the level of superoxide anions.

RESULTS

Elevated expression of ecNOS was found to be coupled with significantly lower SOD activity and glutathione level, and increased lipid peroxidation in IUGR neonates.

CONCLUSION

The increased NO indices could represent a compensatory effort to improve placental bloodflow, but in IUGR neonates it is coupled with inadequate antioxidant defence, resulting in significant oxidative stress.

The protective effects of selenoorganic compounds against peroxynitrite-induced changes in plasma proteins and lipids

Many selenoorganic compounds play an important role in biochemical processes and act as antioxidants, enzyme inhibitors or drugs. The effects of a new selenocompound — bis(2-aminophenyl)-diselenide on oxidative/nitrative changes in human plasma proteins induced by peroxynitrite (ONOO⁻) were studied in vitro and compared with the those of ebselen, a well-known antioxidant. We also studied the role of the tested selenocompounds in peroxynitrite-induced plasma lipid peroxidation. Exposure of the plasma to peroxynitrite (0.1 mM) resulted in an increase in the level of carbonyl groups and nitrotyrosine residues in plasma proteins (estimated using the ELISA method and Western blot analysis). In the presence of different concentrations (0.025–0.1 mM) of the tested selenocompounds, 0.1 mM peroxynitrite caused a distinct decrease in the level of carbonyl group formation and tyrosine nitration in plasma proteins. Moreover, these selenocompounds also inhibited plasma lipid peroxidation induced by ONOO⁻¹ (0.1 mM). The obtained results indicate that in vitro bis(2-aminophenyl)-diselenide and ebselen have very similar protective effects against peroxynitrite-induced oxidative/nitrative damage to human plasma proteins and lipids.

Peroxynitrite mild nitration of albumin and LDL–albumin complex naturally present in plasma and tyrosine nitration rate–albumin impairs LDL nitration

In blood, peroxynitrite (ONOO- ) and CO2 react to form NO2* and CO3* through the short-lived adduct ONOOCO2-, leading to protein-bound tyrosine nitration. ONOO(-) -modified LDL is atherogenic. Oxidatively modified LDL generally appears in the vessel wall surrounded by antioxidants. Human serum albumin (HSA) is one of them, partly associated to LDL as a LDL-albumin complex (LAC). The purpose was to study the effect of a mild nitration on LAC and whether albumin may interfere with LDL nitration. To do so, SIN-1 was used as ONOO- generator in the presence or absence of 25 mM HCO3-. The human serum albumin (HSA)-bound tyrosine nitration rate was found to be 4.4 x 10(-3) mol/mol in the presence of HCO3-. HSA decreased the LAC-tyrosine nitration rate from 2.5 x 10(-3) to 0.6 x 10(-3) mol/mol. It was concluded that HSA impaired the apoB-bound tyrosine nitration. These findings raise the question of the patho-physiological significance of these nitrations and their interactions which may potentially prevent both atheromatous plaque formation and endothelium dysfunction in particular and appear to be beneficial in terms of atherogenic risk.

Altered Circadian Relationship Between Serum Nitric Oxide, Carbon Dioxide, and Uric Acid in Multiple Sclerosis

The free radical nitric oxide (NO*) is involved in a variety of diverse biological processes from acting as a vasodilator in the cardiovascular system to being the rate-limiting component in the production of peroxynitrite (ONOO-), a contributor to neurodegenerative disorders such as multiple sclerosis (MS). Uric acid (UA), the end product of purine metabolism in humans and a selective inhibitor of toxic reactions attributed to radicals formed by the interaction of ONOO- and CO2, is generally low in MS patients. We investigated the relationship between serum ONOO-, CO2, and UA in MS patients and normal controls by comparing the circadian characteristics of the NO* metabolites nitrite/ nitrate (NO), CO2, and UA. In this preliminary study, we found the functional relationship ascribed to the circadian timing of the peak and trough levels of NO, CO2, and UA in healthy subjects to be clearly altered in MS patients. These findings suggest that alterations in the temporal relationship between the 24h pattern in serum ONOO- formation and UA may either contribute to or reflect the disease processes in MS.

Comparison of total antioxidant capacity of salivary, capillary and venous samplings: interest of the salivary total antioxidant capacity on triathletes during training season

AIM

Total antioxidant capacity (TAC) is an essential parameter to watch over defense system of athletes exposed to an oxidant stress during intensive periods of training. To control this parameter throughout the training period, repetitive biological samples are required. The TAC is usually investigated in venous blood which needs invasive withdrawings. Thus, we proposed to find alternatives to venous blood analysis by venepuncture, which is invasive, stressful and not allow a regular follow-up on athletes during annual training season.

METHODS

We measured capillary and salivary TAC in 65 physically active subjects at rest and compared them to the venous TAC. We followed the evolution of venous and salivary TAC in 7 triathletes throughout an annual training period (March and June) corresponding to two different types of training.

RESULTS

There was a good correlation between plasma venous and capillary TAC values (r=0.77; P<0.0001), but salivary TAC were significantly lower than the plasma ones and did not correlate. Venous and saliva TAC of triathletes were significantly higher in March compared to June. The variations of plasma and salivary TAC between the two periods of training were correlated (r=0.96; P<0.01).

CONCLUSION

The capillary sampling can replace the venous one for TAC evaluation in routine assays for the follow-up of athletes. Even if saliva TAC did not reflect plasma TAC, it could be used in the follow-up of athletes since a strong correlation is found between the variation of saliva and plasma TAC during the training season.

Reactive oxygen species plasmatic levels in ischemic stroke

Oxidative stress is probably one of the mechanisms involved in neuronal damage induced by ischemia-reperfusion, and the antioxidant activity of plasma may be an important factor providing protection from neurological damage caused by stroke-associated oxidative stress. The aim of this study was to investigate the status of oxidative stress, NO and ONOO(-) levels in patients with atherothrombotic and lacunar acute ischemic stroke and iNOS, eNOS and nitrotyrosine expression in the same patients. Plasma ONOO(-) levels were significantly higher in patients than in controls while NO decreases in patients in respect to controls. Densitometric analysis of bands indicated that iNOS and N-Tyr protein levels were significantly higher in patients in respect to controls. This study has highlighted a significant NO decrease in our patients compared with controls and this is most probably due to the increased expression of inducible NO synthase by the effect of thrombotic attack. In fact, the constitutive NO isoforms, which produce small amounts of NO, are beneficial, while activation of the inducible isoform of NO, which produces much more NO, causes injury, being its toxicity greatly enhanced by generation of peroxynitrite. The significant ONOO(-) increase observed in our patients, compared to controls, is most probably due to reaction of NO with O(2)(*-) . These findings suggest that free radical production and oxidative stress in ischemic stroke might have a major role in the pathogenesis of ischemic brain injury. Peroxynitrite might be the main marker of brain damage and neurological impairment in acute ischemic stroke.

N-acetylcysteine exerts protective effects and prevents lung redox imbalance and peroxynitrite generation in endotoxemic rats

The aim of this study was to determine in endotoxemic rats the effects of N-acetylcysteine on lung redox imbalance and plasma peroxynitrite generation. Eighty male Wistar rats were divided in two sets of five experimental groups. Six hours after vehicle (Control group: isotonic NaCl sterile solution i.p.; n=7), lipopolysaccharide (LPS group: 1 mg/Kg i.p.; n=8), N-acetylcysteine plus LPS (NAC+LPS group, n=8), NAC plus the nitric oxide synthesis inhibitor N(w)-nitro-L-arginine methyl ester plus LPS (NAC+NAME+LPS group; n=8), or NAME plus LPS (NAME+LPS group; n=9), arterial blood and lung samples were taken from each animal under sodium pentobarbital anesthesia. In five additional groups treated as described above, in vivo plasma oxidation of dihydrorhodamine (DRH) 123 to rhodamine (RH)123 was measured as index of peroxynitrite formation. LPS treated rats presented increased plasma lactate, thrombocytopenia and both, decreased reduced thiols and increased lipid peroxidation in lung tissue. Moreover, LPS produced increments in plasma concentration of nitrites/nitrates and DRH 123 oxidation. Pretreatment with NAC prevented all these changes induced by LPS except the increment in plasma concentration of nitrites/nitrates. The protective effects seen in LPS rats pretreated with NAC were not observed in the NAC+NAME+LPS group. In conclusion, the results of this study show that in endotoxemia induced by LPS in rats, NAC produces protective effects on lung redox balance and prevents peroxynitrite anion generation.

Evaluation of Pharmacological Modulation of Nitroglycerin-Induced Impairment of Nitric Oxide Bioavailability by a Catheter-Type Nitric Oxide Sensor

BACKGROUND

The present study aimed to elucidate the effect of long-term treatment with nitroglycerin (NTG) on the bioavailability of nitric oxide (NO) examined by a catheter-type NO sensor. The study also examined whether these effects could be modified by an antioxidant, an angiotensin converting enzyme inhibitor, or an angiotensin II type 1 receptor antagonist (ARB).

METHODS AND RESULTS

Male New Zealand rabbits were treated for 7 days with NTG patches, either alone or in combination with tempol, enalapril, or valsartan (ARB). The plasma NO concentration was measured with the catheter-type NO sensor. The plasma peroxynitrite concentration was measured by enzyme-linked immunosorbent assay. An increase in plasma NO concentration in response to acetylcholine (ACh) were significantly attenuated in the NTG-treated group as compared with the control. Plasma peroxynitrite concentration in NTG-treated group was significantly higher as compared with the control. The negative effects of NTG were significantly suppressed by the co-treatment with tempol, enalapril or valsartan.

CONCLUSIONS

Chronic treatment of rabbits with NTG elicits the impairment of the ACh-stimulated NO production. In addition, the negative effects of NTG might be prevented by the co-treatment with drugs attenuating nitrosative stress.

Proteomic Analysis of Nitrated and 4-Hydroxy-2-Nonenal-Modified Serum Proteins During Aging

Using proteomic techniques, we investigated peroxynitrite (ONOO-) and 4-hydroxy-2-nonenal (HNE) modified serum proteins from young and old Fischer 344 rats. Two-dimensional gel electrophoresis/western blot analysis of nitrotyrosine and HNE-histidine revealed that serum proteins were differentially modified by ONOO- and HNE. Among them, 16 of the modified proteins, identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS), are involved in blood coagulation, lipid transport, blood pressure regulation, and protease inhibition. Furthermore, nitration and HNE adduction were found to increase with age, lending support to the oxidative stress hypothesis of aging. Our data showed that proteomic techniques can be valuable tools in the study of protein profiling modifications during aging.

Beneficial effects of aminoguanidine on the cardiovascular system of diabetic rats

BACKGROUND

The study focused on investigating the effect of aminoguanidine on cardiovascular damages in diabetes and the possible mechanisms of its action.

METHODS

Aminoguanidine (AMNG) was used to treat streptozotocin-induced diabetic rats, and the effects were compared to those obtained under insulin treatment. Blood metabolic parameters, *NO and ONOO- as well as protein carbonyl levels and cardiac hypertrophy were determined.

RESULTS

Diabetic animals showed increased *NO levels and markedly increased ONOO- generation in the aorta, along with a significant hypertrophy and protein carbonylation in the cardiac tissue. Both AMNG and insulin treatment suppressed the levels of overproduced *NO or ONOO- in the vasculature, but only AMNG was able to prevent hypertrophic alterations and reduce protein carbonylation in the cardiac tissue.

CONCLUSIONS

Oxidative protein modification, together with cardiac hypertrophy and high generation of *NO and ONOO-, are important early events in the development of cardiovascular complications in diabetes. Aminoguanidine could prevent hypertrophy through inhibition of production of nonenzymatic glycation products rather than via inhibition of *NO production.

Peroxynitrite in reperfusion arrhythmias and its whole blood chemiluminescence results

The aims of the present study were to investigate the effects of exogenous peroxynitrite (ONOO(-)) on reperfusion arrhythmias in anaesthetized rats, and to detect endogenous and exogenous ONOO(-)-induced chemiluminescence (CL) signals in rat whole blood, which was collected during baseline and in the first minute of reperfusion. ONOO(-) infusion in ischemia/reperfusion (I/R) applied groups caused significant decreases in mean arterial pressure (MAP) and heart rate (HR). Ventricular fibrillation (VF) incidences in the vehicle, ONOO(-), and dec-ONOO(-) infused groups were 63, 100, and 20%, respectively. In control group CL signal was 136+/-34mV during the resting period and was increased to 336+/-57mV with reperfusion. Also, the effects of SOD+CAT, L-NAME and urate were investigated. Ventricular tachycardia (VT) incidence was decreased significantly in SOD+CAT and urate; VF incidence was decreased significantly in SOD+CAT applied groups. CL signals were inhibited with SOD+CAT, L-NAME, and urate. Exogenous ONOO(-) infusion during I/R was also investigated. CL signal in exogenously ONOO(-) infused group is increased 423% during reperfusion. Only urate infused group VF incidence was decreased significantly. CL signals of ONOO(-) infused groups were inhibited by SOD+CAT, L-NAME, and urate. Based on the results of the current study, ONOO(-) seems to be one of the key mediators of reperfusion arrhythmias in anaesthetized rats.

INDUCIBLE NITRIC OXIDE SYNTHASE INHIBITOR REVERSES EXACERBATING EFFECTS OF HYPERTONIC SALINE ON LUNG INJURY IN BURN

The use of hypertonic saline (HTS) resuscitation in major trauma patients is still controversial. The objective of this study is to determine if inhibition of inducible nitric oxide synthase (iNOS) to stabilize the endothelial permeability and to retain HTS in the vascular space will reverse its exacerbating effect on burn-induced lung damage. In Experiment 1, specific pathogen-free (SPF) rats underwent 35% total body surface area (TBSA) burn and were resuscitated with 7.5 mL/kg HTS (7.5% NaCl), 7.5 mL/kg saline, or 50 mL/kg saline (nearly equal sodium load as HTS) via femoral veins for 15 min immediately after the burn. In Experiment 2, S-methylisothiourea (SMT) (7.5 mg/kg, i.p.) was given immediately after the burn to rats from the different groups of Experiment 1. At 8 h after the burn, the permeability and myeloperoxidase (MPO) activity of lung tissues were determined, and plasma samples were assayed for peroxynitrite levels. Burn significantly induced lung MPO activity, lung permeability, and blood dihydrorhodamine 123 (DHR 123) oxidation in rats. HTS administration after burn significantly increased the blood DHR 123 oxidation level, lung MPO activity, lung permeability, and inflammatory cell infiltration in comparison with those of burn plus 7.5 mg/kg saline and burn plus 50 mL/kg saline rats. In contrast, burn plus SMT rats with HTS injection showed significant 54%, 11%, and 35% decreases in blood DHR 123 oxidation level, lung MPO activity, and lung permeability, respectively, in comparison with burn plus SMT plus 7.5 mg/kg saline rats. In conclusion, restoration of extracellular fluid in early burn shock with HTS supplementation significantly exacerbates burn-induced lung neutrophil deposition, lung hyperpermeability, and blood peroxynitrite production. Inhibition of iNOS before HTS supplementation reverses the deteriorating effects of HTS on thermal injury-induced lung damage to beneficial ones. Using HTS in thermal injury resuscitation without the inhibition of iNOS is dangerous.

Nicotine induces human neutrophils to produce IL-8 through the generation of peroxynitrite and subsequent activation of NF-kappaB

Leukocytosis in tobacco smokers has been well recognized; however, the exact cause has not been elucidated. To test the hypothesis that tobacco nicotine stimulates neutrophils in the respiratory tract to produce IL-8, which causes neutrophilia in vivo, we examined whether nicotine induces neutrophil-IL-8 production in vitro; the causative role of NF-kappaB in its production, in association with the possible production of reactive oxygen intermediates that activate NF-kappaB; and the nicotinic acetylcholine receptors (nAChRs) involved in IL-8 production. Nicotine stimulated neutrophils to produce IL-8 in both time- and concentration-dependent manners with a 50% effective concentration of 1.89 mM. A degradation of IkappaB-alpha/beta proteins and an activity of NF-kappaB p65 and p50 were enhanced following nicotine treatment. The synthesis of superoxide and the oxidation of dihydrorhodamine 123 (DHR) were also enhanced. The NOS inhibitor, nomega-Nitro-l-arginine methyl ester, prevented nicotine-induced IL-8 production, with an entire abrogation of DHR oxidation, IkappaB degradation, and NF-kappaB activity. Neutrophils spontaneously produced NO whose production was not increased, but rather decreased by nicotine stimulation, suggesting that superoxide, produced by nicotine, generates peroxynitrite by reacting with preformed NO, which enhances the NF-kappaB activity, thereby producing IL-8. The nAChRs seemed to be involved in IL-8 production. In smokers, blood IL-8 levels were significantly higher than those in nonsmokers. In conclusion, nicotine stimulates neutrophil-IL-8 production via nAChR by generating peroxynitrite and subsequent NF-kappaB activation, and the IL-8 appears to contribute to leukocytosis in tobacco smokers.

Disruption of thiol homeostasis and nitrosative stress in the cerebrospinal fluid of patients with active multiple sclerosis: evidence for a protective role of acetylcarnitine

Recent studies suggest that NO and its reactive derivative peroxynitrite are implicated in the pathogenesis of multiple sclerosis (MS). Patients dying with MS demonstrate increased astrocytic inducible nitric oxide synthase activity, as well as increased levels of iNOS mRNA. Peroxynitrite is a strong oxidant capable of damaging target tissues, particularly the brain, which is known to be endowed with poor antioxidant buffering capacity. Inducible nitric oxide synthase is upregulated in the central nervous system (CNS) of animals with experimental allergic encephalomyelitis (EAE) and in patients with MS. We have recently demonstrated in patients with active MS a significant increase of NOS activity associated with increased nitration of proteins in the cerebrospinal fluid (CSF). Acetylcarnitine is proposed as a therapeutic agent for several neurodegenerative disorders. Accordingly, in the present study, MS patients were treated for 6 months with acetylcarnitine and compared with untreated MS subjects or with patients noninflammatory neurological conditions, taken as controls. Western blot analysis showed in MS patients increased nitrosative stress associated with a significant decrease of reduced glutathione (GSH). Increased levels of oxidized glutathione (GSSG) and nitrosothiols were also observed. Interestingly, treatment of MS patients with acetylcarnitine resulted in decreased CSF levels of NO reactive metabolites and protein nitration, as well as increased content of GSH and GSH/GSSG ratio. Our data sustain the hypothesis that nitrosative stress is a major consequence of NO produced in MS-affected CNS and implicate a possible important role for acetylcarnitine in protecting brain against nitrosative stress, which may underlie the pathogenesis of MS.

Oxidative stress-related factors in Bartter's and Gitelman's syndromes: relevance for angiotensin II signalling

BACKGROUND

Bartter's and Gitelman's syndromes (BS/GS) have a blunted Gq protein-mediated cell signalling despite high circulating angiotensin II (Ang II) levels. This is associated with reduced Galphaq gene expression, intracellular inositol trisphosphate and Ca(++) release, PKC activity and cell reactivity. Ang II is a powerful stimulator of vascular oxidases but BS/GS patients show reduced total volatile LDL oxidation products and reduced LDL susceptibility to oxidation suggesting low level of oxidative stress. Therefore, we evaluated oxidative stress-related proteins in plasma and monocytes of patients with BS/GS, at baseline and after Ang II stimulation.

METHODS

In two BS and seven GS patients, biochemically and genetically characterized, and in 10 age- and sex-matched control subjects, we measured total plasma antioxidant power (AOP), plasma peroxynitrite level and gene expression of the NADH/NADPH oxidase subunit p22(phox), TGFbeta and haeme oxygenase-1 (HO-1) in circulating monocytes in basal condition and after stimulation with Ang II. Furthermore, we investigated the C(242)T polymorphism of p22(phox), whose topography in a potential haeme-binding site suggests a role in the regulation of oxidative stress.

RESULTS

AOP was higher in BS/GS patients than in controls (3.27 +/- 0.95 mmol/l vs 1.05 +/- 0.16, P = 0.002), together with higher plasma renin activity and aldosterone level (9.88 +/- 4.64 vs 0.95 +/- 0.08 nmol Ang I/h/ml, P < 0.0001; and 0.73 +/- 0.13 vs 0.18 +/- 0.01 nmol/l, P < 0.0001, respectively). The plasma peroxynitrite level was undetectable both in patients and controls. mRNA expression of p22(phox) and TGFbeta was reduced in BS/GS patients compared to controls [0.35 +/- 0.08 vs 0.53+/-0.05 densitometric units (d.u.), P = 0.005, and 0.82 +/- 0.07 vs 1.15 +/- 0.25 d.u., P = 0.006, respectively]. HO-1 mRNA was increased in BS/GS patients in comparison to controls (0.88 +/- 0.07 vs 0.78 +/- 0.11 d.u., P = 0.037). After acute Ang II exposure, p22(phox), TGFbeta and HO-1 gene expression significantly increased only in controls (from 0.59 +/- 0.12 to 0.96 +/- 0.11, P < 0.001, from 0.97 +/- 0.1 to 1.27 +/- 0.22, P < 0.008, and from 0.62 +/- 0.1 to 0.82 +/- 0.09, P < 0.001, respectively). Finally, C(242)T polymorphism of p22(phox) was undetectable.

CONCLUSIONS

The intracellular responses to Ang II mediated by reactive oxygen species are reduced in BS/GS patients. This may contribute to their vascular hyporeactivity.

Peroxynitrite is an important mediator in thermal injury-induced lung damage

OBJECTIVE

Intestinal ischemia and reperfusion injury was known to cause postinjury multiple organ failure by neutrophil and unclear nonneutrophil factors. Peroxynitrite formed by the rapid reaction between superoxide and nitric oxide, is a toxic substance that contributes to tissue injury in a number of biological systems. In this study, the role of nitric oxide and neutrophils on lung damage after burn was investigated.

DESIGN

Prospective, experimental study.

SETTING

Research laboratory at a university hospital.

SUBJECTS

Thermal injury models in the rat.

INTERVENTIONS

In experiment 1, specific pathogen-free Sprague-Dawley rats underwent 35% total body surface area burn. At 4, 8, 16, and 24 hrs after burn, intestinal mucosa and lung tissue were harvested for myeloperoxidase (MPO) assay, blood was collected for measurement of peroxynitrite-mediated oxidation of dihydrorhodamine 123, and pulmonary microvascular dysfunction was quantified by measuring the extravasation of Evans blue dye. In experiment 2, polymorphonuclear granulocyte antibody (0.12 mL/100 g administered intraperitoneally 16 hrs before burn), S-methylisothiourea (7.5 mg/kg, intraperitoneally, immediately after burn), a specific inducible nitric oxide synthase inhibitor, and sterile saline (15 mL/kg, intraperitoneally, immediately after burn) were given to different groups of thermally injured animals individually. The plasma dihydrorhodamine 123 oxidation level, intestinal and lung MPO activity, lung permeability, and lung histology were evaluated at 8 hrs after burn. The cellular localization of nitrotyrosine, a marker for peroxynitrite reactivity, was also examined by immunostaining. In experiment 3, 3-morpholinosydnonimine (10 mM, intraperitoneally), a peroxynitrite donor, was given to nonburned rats to examine the peroxynitrite effect on lung inducible nitric oxide synthase expression.

MEASUREMENTS AND MAIN RESULTS

The level of MPO activity in intestine and lung, blood dihydrorhodamine 123 oxidation, and lung permeability were increased up to 2-fold, 2.5-fold, 2-fold, and 2-fold of normal, respectively, at 8 hrs after burn. S-methylisothiourea injection significantly decreased (p <.05) 31% of the lung MPO activity, 41% of the blood peroxynitrite level, 54% of the lung permeability, and the lung peroxynitrite production in burned rats. Polymorphonuclear granulocyte antibody pretreatment significantly decreased 60% of the intestinal MPO, 92% of the blood peroxynitrite level, and 56% the lung MPO activity in burned rats, but the lung permeability was only slightly decreased by polymorphonuclear granulocyte antibody pretreatment. Furthermore, 3-morpholinosydnonimine increased the lung inducible nitric oxide synthase messenger RNA levels.

CONCLUSIONS

Thermal injury induces blood dihydrorhodamine 123 oxidation, intestinal and lung neutrophil deposition, lung nitrotyrosine production, and lung damage. Both specific inhibition of inducible nitric oxide synthase and polymorphonuclear granulocyte antibody pretreatment decrease blood dihydrorhodamine 123 oxidation and intestinal and lung neutrophil deposition, but only inducible nitric oxide synthase inhibition with S-methylisothiourea reduces lung peroxynitrite production and thermal injury-induced lung damage. Nitric oxide and the ensuing peroxynitrite production in lung play a more important role than neutrophil in contributing to thermal injury-induced lung damage.

Tetrahydrobiopterin and antioxidants reverse the coronary endothelial dysfunction associated with left ventricular hypertrophy in a porcine model

OBJECTIVE

Endothelium-dependent G-protein mediated relaxations of epicardial coronary arteries is impaired with left ventricular hypertrophy. The objective of this study was to assess the effect of L-arginine, BH(4) and the combination of two antioxidants, superoxide dismutase and catalase, on endothelium-dependent relaxations in a swine left ventricular hypertrophy model.

METHODS

Aortic banding was performed 3 cm above the coronary ostia. Vascular reactivity studies were performed in standard organ chamber experiments to assess the NO pathway in the presence of methyltetrahydropterin (a BH(4) analogue), L-arginine, superoxide dismutase and catalase.

RESULTS

There was a statistically significant increase in endothelium-dependent relaxation to serotonin and to bradykinin with methyltetrahydropterin and with superoxide dismutase plus catalase (P<0.05) but not with L-arginine compared to untreated coronary arteries from left ventricular hypertrophy animals. Plasma 3-nitrotyrosine level increased significantly from 918+/-122 to 1844+/-300 microM (P<0.05 vs. control) after 60 days of aortic banding. Endothelial dysfunction was not associated with a reduced expression of endothelial nitric oxide synthase 2 months after pressure overload left ventricular hypertrophy.

CONCLUSIONS

Treatment with BH(4) and antioxidants constitutes an interesting approach for the prevention of endothelial dysfunction in epicardial coronary arteries associated with left ventricular hypertrophy.

[Clinical study on the antioxidant effect of methylene blue in vivo]

OBJECTIVE

To investigate the relationship of oxygen free radical (OFR) with per-oxidative injury of erythrocyte induced by intravenous procaine in vivo and the effect of methylene blue (MB) in removal of nitric oxide (NO) and peroxynitrite (ONOO(-)).

METHODS

Forty patients undergoing elective surgery were divided randomly into intravenous procaine anesthesia (IPA) group and fentanyl group. Blood sample was taken before anesthesia (T0), 120 minutes (T1) and 180 minutes (T2) after IPA and 30 minutes after treatment with MB (1-2 mg/kg, T3) to determine the changes in the levels of NO, OFR, lipid peroxide (LPO), superoxide dismutase (SOD), catalase (CAT), NADH-Cyt b5-reductase (Cyt b5-R) and methemoglobin (MHb).

RESULTS

Compared with T0, the levels of NO, OFR, LPO, MHb in IPA group were significantly increased at T1,T2. At same time SOD, CAT and Cyt b5-R were significantly decreased. NO, OFR, MHb, SOD, CAT and Cyt b5-R were all reduced to the normal levels at T3. No changes in any determined parameters in fentanyl group during anesthesia.

CONCLUSION

It is indicated that the metabolites of procaine consist of a large quantity of NO:ONOO(-), producing per-oxidative injury to erythrocyte. MB is effective in eliminating OFR in vivo, protecting tissue cells. It may act as an antioxidant drug in the treatment of critical illness.

Coenzyme Q10-containing composition (Immugen) protects against occupational and environmental stress in workers of the gas and oil industry

The manual workers of the gas-and-oil extraction industry are exposed to hostile environmental and occupational conditions, resulting in elevated mortality and disability, due to chronic neurological and cardiovascular diseases. We evaluated the degree of oxidative stress, often associated with these pathological features, in the blood of manual and office employees of Russian Siberian extraction plants, and their psycho-physiological conditions. Results showed increased levels of spontaneous (p < 0.05) and PMA-activated (p < 0.01) luminol-dependent chemiluminescence (LDCL) in the white blood cells (WBC), and decreased peroxynitrite levels (p < 0.05) in the group of manual workers, and less markedly in the clerks and technicians working on spot, vs. a control group of city clerks. Superoxide release by WBC, and plasma/WBC membrane ubiquinol levels did not display major differences in the three groups. A relevant percentage of manual/office workers of extraction platforms presented impaired cardiovascular and neurological functions. The short term administration of a nutraceutical formulation based on coenzyme10, vitamin E, selenium, methionine and phospholipids led to significant improvement of cardiovascular parameters and psycho-emotional status, consistent with the normalization of LDCL and peroxynitrite production by WBC, with a good compliance to treatment confirmed by the increased blood levels of ubiquinol.

EPR detection of glutathiyl and hemoglobin-cysteinyl radicals during the interaction of peroxynitrite with human erythrocytes

Peroxynitrite, which is formed by the fast reaction between nitric oxide and superoxide anion, has been receiving increasing attention as a mediator of human diseases. An initial controversy about the possibility of free radical production from peroxynitrite in test tubes has been resolved, and presently it is important to establish whether peroxynitrite produces radicals in cells. Here we employed the EPR spin trapping methodology with 5,5-dimethylpyrroline N-oxide (DMPO) to study the interaction of peroxynitrite with human erythrocytes. The results confirmed previous findings in demonstrating that oxyhemoglobin is the main target of peroxynitrite in erythrocytes. As we first show here, the produced ferryl-hemoglobin oxidizes its own amino acids and, most probably, amino acids from other hemoglobin monomers to produce hemoglobin-tyrosyl and hemoglobin-cysteinyl radicals. In parallel, ferryl-hemoglobin also oxidizes intracellular glutathione to produce the glutathiyl radical. The EPR spectrum of both DMPO/(*)cysteinyl-hemoglobin (a(beta)(H) = 15.4 G) and DMPO/(*)tyrosyl-hemoglobin (a(beta)(H) = 8.8 G) radical adducts was characterized. It is proposed that erythrocytes can be efficient peroxynitrite scavengers in vivo through the coupled action of oxyhemoglobin and glutathione. Overall, the results indicate that, through the intermediacy of carbon dioxide and/or hemoproteins, oxidation of glutathione to the glutathiyl radical is likely to be an important consequence of peroxynitrite production in vivo.

[Active forms of oxygen and nitrogen in blood cells of patients with rheumatoid arthritis: effect of laser therapy]

Infrared pulse laser therapy was studied for its impact on the production of active forms of oxygen and nitrogen by neutrophils from patients with rheumatoid arthritis (RA). The authors determined the non-activated and PMA-activated production of superoxide anion-radical, peroxynitrite, peripheral neurophilic NAD.PH-oxidase and superoxide dismutase activities, and the red blood cell concentrations of reduced glutathione. Before therapy, non-activation RA neurophilic production of superoxide was much higher than in donors. Laser therapy made this parameter normal. Similarly, neutrophilic peroxynitrite production (defined by dihydrorhodamine oxidation) in RA patients was 1.7 times higher than the normal values. IF-laser therapy decreased peroxynitrite production to the values observed in donors. It is important that the therapy caused increased SOD activity (that was lower in RA patients prior to therapy) up to apparently control values. Thus, IF-laser therapy has a certain antioxidative effect by increasing SOD activity in RA patients' blood cells and reducing the production of highly reactive oxygen and nitrogen forms.

The nitration of proteins in platelets

Nitric oxide has many important physiological functions, but it may also form an important oxidant, peroxynitrite, as a consequence of its reaction with superoxide anions. Peroxynitrite is capable of nitrating the aromatic amino acids in proteins, particularly tyrosine. Nitrated proteins are found in tissues of a variety of diseases where inflammation occurs. However, our recent work suggests that more selective nitration of specific proteins may occur during normal physiological processes, such as platelet activation by collagen. It is not yet clear what role this may play in the normal cell biology, but there is potential to be a role in signal transduction mechanisms, possibly by influencing tyrosine phosphorylation or dephosphorylation.