ascorbic-acid and 3-nitrotyrosine
ascorbic-acid has been researched along with 3-nitrotyrosine* in 45 studies
Trials
3 trial(s) available for ascorbic-acid and 3-nitrotyrosine
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Ascorbic acid supplementation diminishes microparticle elevations and neutrophil activation following SCUBA diving.
Predicated on evidence that diving-related microparticle generation is an oxidative stress response, this study investigated the role that oxygen plays in augmenting production of annexin V-positive microparticles associated with open-water SCUBA diving and whether elevations can be abrogated by ascorbic acid. Following a cross-over study design, 14 male subjects ingested placebo and 2-3 wk later ascorbic acid (2 g) daily for 6 days prior to performing either a 47-min dive to 18 m of sea water while breathing air (∼222 kPa N2/59 kPa O2) or breathing a mixture of 60% O2/balance N2 from a tight-fitting face mask at atmospheric pressure for 47 min (∼40 kPa N2/59 kPa O2). Within 30 min after the 18-m dive in the placebo group, neutrophil activation, and platelet-neutrophil interactions occurred, and the total number of microparticles, as well as subgroups bearing CD66b, CD41, CD31, CD142 proteins or nitrotyrosine, increased approximately twofold. No significant elevations occurred among divers after ingesting ascorbic acid, nor were elevations identified in either group after breathing 60% O2. Ascorbic acid had no significant effect on post-dive intravascular bubble production quantified by transthoracic echocardiography. We conclude that high-pressure nitrogen plays a key role in neutrophil and microparticle-associated changes with diving and that responses can be abrogated by dietary ascorbic acid supplementation. Topics: Ascorbic Acid; Biomarkers; Blood Platelets; Cell-Derived Microparticles; Cross-Over Studies; Decompression Sickness; Dietary Supplements; Diving; Embolism, Air; Humans; Male; Neutrophil Activation; Neutrophils; Syndecan-1; Time Factors; Treatment Outcome; Tyrosine; Ultrasonography | 2015 |
Vitamin C further improves the protective effect of GLP-1 on the ischemia-reperfusion-like effect induced by hyperglycemia post-hypoglycemia in type 1 diabetes.
It has been reported that hyperglycemia following hypoglycemia produces an ischemia-reperfusion-like effect in type 1 diabetes. In this study the possibility that GLP-1 has a protective effect on this phenomenon has been tested.. 15 type 1 diabetic patients underwent to five experiments: a period of two hours of hypoglycemia followed by two hours of normo-glycemia or hyperglycemia with the concomitant infusion of GLP-1 or vitamin C or both. At baseline, after 2 and 4 hours, glycemia, plasma nitrotyrosine, plasma 8-iso prostaglandin F2alpha, sCAM-1a, IL-6 and flow mediated vasodilation were measured.. After 2 h of hypoglycemia, flow mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine and IL-6 significantly increased. While recovering with normoglycemia was accompanied by a significant improvement of endothelial dysfunction, oxidative stress and inflammation, a period of hyperglycemia after hypoglycemia worsens all these parameters. These effects were counterbalanced by GLP-1 and better by vitamin C, while the simultaneous infusion of both almost completely abolished the effect of hyperglycemia post hypoglycemia.. This study shows that GLP-1 infusion, during induced hyperglycemia post hypoglycemia, reduces the generation of oxidative stress and inflammation, improving the endothelial dysfunction, in type 1 diabetes. Furthermore, the data support that vitamin C and GLP-1 may have an additive protective effect in such condition. Topics: Adult; Antioxidants; Ascorbic Acid; Biomarkers; Blood Glucose; Diabetes Mellitus, Type 1; Dinoprost; Female; Glucagon-Like Peptide 1; Humans; Hyperglycemia; Hypoglycemia; Hypoglycemic Agents; Inflammation; Inflammation Mediators; Infusions, Parenteral; Intercellular Adhesion Molecule-1; Interleukin-6; Male; Oxidative Stress; Reperfusion Injury; Time Factors; Treatment Outcome; Tyrosine; Vasodilation; Young Adult | 2013 |
Ascorbate attenuates atrial pacing-induced peroxynitrite formation and electrical remodeling and decreases the incidence of postoperative atrial fibrillation.
Atrial fibrillation (AF), the most common chronic arrhythmia, increases the risk of stroke and is an independent predictor of mortality. Available pharmacological treatments have limited efficacy. Once initiated, AF tends to self-perpetuate, owing in part to electrophysiological remodeling in the atria; however, the fundamental mechanisms underlying this process are still unclear. We have recently demonstrated that chronic human AF is associated with increased atrial oxidative stress and peroxynitrite formation; we have now tested the hypothesis that these events participate in both pacing-induced atrial electrophysiological remodeling and in the occurrence of AF following cardiac surgery. In chronically instrumented dogs, we found that rapid (400 min(-1)) atrial pacing was associated with attenuation of the atrial effective refractory period (ERP). Treatment with ascorbate, an antioxidant and peroxynitrite decomposition catalyst, did not directly modify the ERP, but attenuated the pacing-induced atrial ERP shortening following 24 to 48 hours of pacing. Biochemical studies revealed that pacing was associated with decreased tissue ascorbate levels and increased protein nitration (a biomarker of peroxynitrite formation). Oral ascorbate supplementation attenuated both of these changes. To evaluate the clinical significance of these observations, supplemental ascorbate was given to 43 patients before, and for 5 days following, cardiac bypass graft surgery. Patients receiving ascorbate had a 16.3% incidence of postoperative AF, compared with 34.9% in control subjects. In combination, these studies suggest that oxidative stress underlies early atrial electrophysiological remodeling and offer novel insight into the etiology and potential treatment of an enigmatic and difficult to control arrhythmia. The full text of this article is available at http://www.circresaha.org. Topics: Aged; Animals; Antioxidants; Ascorbic Acid; Atrial Fibrillation; Cardiac Pacing, Artificial; Coronary Artery Bypass; Dogs; Electrophysiology; Female; Heart Atria; Humans; Male; Middle Aged; Multivariate Analysis; Nitrates; Time Factors; Treatment Outcome; Tyrosine | 2001 |
Other Studies
42 other study(ies) available for ascorbic-acid and 3-nitrotyrosine
Article | Year |
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Trimethylamine-N-Oxide Promotes Age-Related Vascular Oxidative Stress and Endothelial Dysfunction in Mice and Healthy Humans.
Topics: Acetylcholine; Adolescent; Adult; Aged; Aging; Animals; Antioxidants; Ascorbic Acid; Brachial Artery; Carotid Arteries; Cyclic N-Oxides; Dietary Supplements; Endothelium, Vascular; Gastrointestinal Microbiome; Humans; Methylamines; Mice; Mice, Inbred C57BL; Middle Aged; Nitric Oxide; Nitric Oxide Synthase Type III; Oxidative Stress; Spin Labels; Superoxides; Tyrosine; Vasodilation; Young Adult | 2020 |
Effects of epidural compression on stellate neurons and thalamocortical afferent fibers in the rat primary somatosensory cortex.
A number of neurological disorders such as epidural hematoma can cause compression of cerebral cortex. We here tested the hypothesis that sustained compression of primary somatosensory cortex may affect stellate neurons and thalamocortical afferent (TCA) fibers. A rat model with barrel cortex subjected to bead epidural compression was used. Golgi-Cox staining analyses showed the shrinkage of dendritic arbors and the stripping of dendritic spines of stellate neurons for at least 3 months post-lesion. Anterograde tracing analyses exhibited a progressive decline of TCA fiber density in barrel field for 6 months post-lesion. Due to the abrupt decrease of TCA fiber density at 3 days after compression, we further used electron microscopy to investigate the ultrastructure of TCA fibers at this time. Some TCA fiber terminal profiles with dissolved or darkened mitochondria and fewer synaptic vesicles were distorted and broken. Furthermore, the disruption of mitochondria and myelin sheath was observed in some myelinated TCA fibers. In addition, expressions of oxidative markers 3-nitrotyrosine and 4-hydroxynonenal were elevated in barrel field post-lesion. Treatment of antioxidant ascorbic acid or apocynin was able to reverse the increase of oxidative stress and the decline of TCA fiber density, rather than the shrinkage of dendrites and the stripping of dendritic spines of stellate neurons post-lesion. Together, these results indicate that sustained epidural compression of primary somatosensory cortex affects the TCA fibers and the dendrites of stellate neurons for a prolonged period. In addition, oxidative stress is responsible for the reduction of TCA fiber density in barrels rather than the shrinkage of dendrites and the stripping of dendritic spines of stellate neurons. Topics: Acetophenones; Afferent Pathways; Aldehydes; Animals; Antioxidants; Ascorbic Acid; Biotin; Brain Injuries; Dendrites; Dextrans; Disease Models, Animal; Electron Transport Complex IV; Epidural Space; Functional Laterality; Male; Neurons; Oxidative Stress; Rats; Somatosensory Cortex; Thalamus; Time Factors; Tyrosine | 2017 |
Associations between Specific Redox Biomarkers and Age in a Large European Cohort: The MARK-AGE Project.
Oxidative stress and antioxidants play a role in age-related diseases and in the aging process. We here present data on protein carbonyls, 3-nitrotyrosine, malondialdehyde, and cellular and plasma antioxidants (glutathione, cysteine, ascorbic acid, uric acid, Topics: Adult; alpha-Tocopherol; Antioxidants; Ascorbic Acid; Biomarkers; Carotenoids; Female; Glutathione; Humans; Lipid Peroxidation; Lycopene; Male; Malondialdehyde; Middle Aged; Oxidation-Reduction; Oxidative Stress; Tyrosine; Uric Acid | 2017 |
Vascular endothelial function and oxidative stress are related to dietary niacin intake among healthy middle-aged and older adults.
We tested the hypothesis that vascular endothelial function and oxidative stress are related to dietary niacin intake among healthy middle-aged and older adults. In 127 men and women aged 48-77 yr, brachial artery flow-mediated dilation (FMD) was positively related to dietary niacin intake [%change (Δ): r = 0.20, P < 0.05; mmΔ: r = 0.25, P < 0.01]. In subjects with above-average dietary niacin intake (≥ 22 mg/day, NHANES III), FMD was 25% greater than in subjects with below-average intake (P < 0.05). Stepwise linear regression revealed that dietary niacin intake (above vs. below average) was an independent predictor of FMD (%Δ: β = 1.8; mmΔ: β = 0.05, both P < 0.05). Plasma oxidized low-density lipoprotein, a marker of systemic oxidative stress, was inversely related to niacin intake (r = -0.23, P < 0.05) and was lower in subjects with above- vs. below-average niacin intake (48 ± 2 vs. 57 ± 2 mg/dl, P < 0.01). Intravenous infusion of the antioxidant vitamin C improved brachial FMD in subjects with below-average niacin intake (P < 0.001, n = 33), but not above-average (P > 0.05, n = 20). In endothelial cells sampled from the brachial artery of a subgroup, dietary niacin intake was inversely related to nitrotyrosine, a marker of peroxynitrite-mediated oxidative damage (r = -0.30, P < 0.05, n = 55), and expression of the prooxidant enzyme, NADPH oxidase (r = -0.44, P < 0.01, n = 37), and these markers were lower in subjects with above- vs. below-average niacin intake [nitrotyrosine: 0.39 ± 0.05 vs. 0.56 ± 0.07; NADPH oxidase: 0.38 ± 0.05 vs. 0.53 ± 0.05 (ratio to human umbilical vein endothelial cell control), both P < 0.05]. Our findings support the hypothesis that higher dietary niacin intake is associated with greater vascular endothelial function related to lower systemic and vascular oxidative stress among healthy middle-aged and older adults. Topics: Aged; Antioxidants; Ascorbic Acid; Brachial Artery; Diet; Endothelial Cells; Endothelium, Vascular; Female; Humans; Lipoproteins, LDL; Male; Middle Aged; NADPH Oxidases; Niacin; Oxidative Stress; Regional Blood Flow; Tyrosine; Vasodilation; Vasodilator Agents; Vitamin B Complex | 2014 |
Oxidative and nitrosative stress induced in myofibrillar proteins by a hydroxyl-radical-generating system: impact of nitrite and ascorbate.
Understanding the chemistry behind the redox properties of nitrite and ascorbate is essential to identify the impact of curing agents on food quality and optimize the formulation of cured meat products. This study was designed to gain insight into the interactions between curing agents and myofibrillar proteins (MPs) during in vitro oxidation by a hydroxyl-radical-generating system. MPs (4 mg/mL) were oxidized for 4 days at 37 °C under constant stirring with 25 μM iron(III) and 2.5 mM hydrogen peroxide. Dependent upon the addition of nitrite (0, 75, and 150 mg/L) and ascorbate (0, 250, and 500 mg/L), nine different reaction units were prepared in triplicate (n = 3) according to a total factorial design. Upon completion of the oxidation assay, samples were analyzed for the concentration of tryptophan (TRP), α-aminoadipic semialdehyde (AAS), Schiff bases (SBs), and 3-nitrotyrosine (3NT). Ascorbate at 250 mg/L significantly inhibited the depletion of TRP (∼20% inhibition) and the formation of AAS and SBs (>90% inhibition) in MP suspensions. Nitrite, alone, had a negligible effect on protein oxidation but induced the formation of a specific marker of nitrosative stress, namely, 3NT. Ascorbate was also efficient at inhibiting the formation of 3NT by a dose-dependent anti-nitrosative effect and enabled the antioxidant action of nitrite. Topics: Ascorbic Acid; Dose-Response Relationship, Drug; Hydrogen Peroxide; Hydroxyl Radical; Myofibrils; Nitrites; Oxidation-Reduction; Oxidative Stress; Proteins; Schiff Bases; Tryptophan; Tyrosine | 2014 |
Supplemental L-arginine and vitamins E and C preserve xanthine oxidase activity in the lung of broiler chickens grown under hypobaric hypoxia.
The effects of l-Arg, vitamin C (VC), and vitamin E (VE) on xanthine- (XO) and NAD(P)H-oxidase (NOX) activities, and nitric oxide (NO) availability of hypoxic broilers were evaluated. Chickens were kept in wire cages with free access to feed and water. One-day-old chicks were assigned to 1 of 3 diets: control (CTL; ME 3,200 kcal/kg, CP 23%), high Arg (HA; CTL + Arg 0.8%), or high Arg plus VE and VC (AEC; HA + 200 IU of VE/kg of feed + 500 mg of VC/L of water), and grown under hypobaric hypoxia (HYP) from d 7 to 30. A fourth group of birds was fed the CTL diet and grown under normoxia (CTL-NOR). At d 30, chickens were euthanized, their lungs fixed in vivo, excised, and processed for cyto- and histochemistry. The enzymes XO and NOX were localized and activities assessed histochemically and in lung homogenates. The NO depletion was assessed through nitrotyrosine immunocytochemistry colloidal gold particles (NTY). The XO and NOX localized in cell membranes and within vesicles of pulmonary vessel endothelial cells. The XO activity was higher in CTL-NOR birds (586 ± 43 reflectance units) than in both AEC-HYP (456 ± 39) and HA-HYP birds (394 ± 31), whereas CTL-HYP birds had the lowest XO activity (313 ± 27). The NO depletion was not affected by dietary or hypoxia conditions in clinically healthy birds; nevertheless, hypoxic birds that developed pulmonary hypertension had higher NTY levels (less NO, 145 ± 19) than hypoxic but clinically healthy birds (56 ± 11). Thus, the concurrent supplementation of Arg, VE, and VC restored XO activity without affecting NOX activity or NO availability. The dual role of XO, which produces superoxide and uric acid, may have buffered the effects of superoxide in broiler chickens grown under hypobaric hypoxia. Topics: Animal Feed; Animals; Arginine; Ascorbic Acid; Avian Proteins; Biomarkers; Chickens; Diet; Dietary Supplements; Histocytochemistry; Hydrogen Peroxide; Lung; Microscopy, Confocal; NADPH Oxidases; Nitric Oxide; Oxidative Stress; Oxygen; Tyrosine; Vitamin E; Xanthine Oxidase | 2014 |
Ascorbate protects against vascular leakage in cecal ligation and puncture-induced septic peritonitis.
Vascular leakage in multiple organs is a characteristic pathological change in sepsis. Our recent study revealed that ascorbate protects endothelial barrier function in microvascular endothelial cell monolayers through inhibiting serine/threonine protein phosphatase 2A (PP2A) activation (Han M, Pendem S, Teh SL, Sukumaran DK, Wu F, Wilson JX. Free Radic Biol Med 48: 128-135, 2010). The present study addressed the mechanism of protection by ascorbate against vascular leakage in cecal ligation and puncture (CLP)-induced septic peritonitis in mice. CLP caused NADPH oxidase activation and endothelial nitric oxide synthase (eNOS) uncoupling to produce superoxide, increased NO production by inducible NOS (iNOS) and neuronal NOS (nNOS) activity, and elevated 3-nitrotyrosine (a product of peroxynitrite) formation and PP2A activity in the hindlimb skeletal muscles at 12 h after CLP. The increase in PP2A activity was associated with decreased levels of phosphorylated serine and threonine in occludin, which was immunoprecipitated from freshly harvested endothelial cells of the septic skeletal muscles. Moreover, CLP increased the vascular permeability to fluorescent dextran and Evans blue dye in skeletal muscles. An intravenous bolus injection of ascorbate (200 mg/kg body wt), given 30 min prior to CLP, prevented eNOS uncoupling, attenuated the increases in iNOS and nNOS activity, decreased 3-nitrotyrosine formation and PP2A activity, preserved the phosphorylation state of occludin, and completely inhibited the vascular leakage of dextran and Evans blue. A delayed ascorbate injection, given 3 h after CLP, also prevented the vascular permeability increase. We conclude that ascorbate injection protects against vascular leakage in sepsis by sequentially inhibiting excessive production of NO and superoxide, formation of peroxynitrite, PP2A activation, and occludin dephosphorylation. Our study provides a scientific basis for injection of ascorbate as an adjunct treatment for vascular leakage in sepsis. Topics: Animals; Antioxidants; Ascorbic Acid; Capillary Permeability; Cecum; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; Muscle, Skeletal; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Occludin; Peritonitis; Protein Phosphatase 2; Sepsis; Superoxides; Tyrosine | 2012 |
Transforming growth factor β suppresses glutamate-cysteine ligase gene expression and induces oxidative stress in a lung fibrosis model.
The concentration of glutathione (GSH), the most abundant intracellular free thiol and an important antioxidant, is decreased in the lung in both fibrotic diseases and experimental fibrosis models. The underlying mechanisms and biological significance of GSH depletion, however, remain unclear. Transforming growth factor β (TGF-β) is the most potent and ubiquitous profibrogenic cytokine and its expression is increased in almost all fibrotic diseases. In this study, we show that increasing TGF-β1 expression in mouse lung to a level comparable to those found in lung fibrotic diseases by intranasal instillation of AdTGF-β1(223/225), an adenovirus expressing constitutively active TGF-β1, suppressed the expression of both catalytic and modifier subunits of glutamate-cysteine ligase (GCL), the rate-limiting enzyme in de novo GSH synthesis, decreased GSH concentration, and increased protein and lipid peroxidation in mouse lung. Furthermore, we show that increasing TGF-β1 expression activated JNK and induced activating transcription factor 3, a transcriptional repressor involved in the regulation of the catalytic subunit of GCL, in mouse lung. Control virus (AdDL70-3) had no significant effect on any of these parameters, compared to saline-treated control. Concurrent with GSH depletion, TGF-β1 induced lung epithelial apoptosis and robust pulmonary fibrosis. Importantly, lung GSH levels returned to normal, whereas fibrosis persisted at least 21 days after TGF-β1 instillation. Together, the data suggest that increased TGF-β1 expression may contribute to the GSH depletion observed in pulmonary fibrosis diseases and that GSH depletion may be an early event in, rather than a consequence of, fibrosis development. Topics: Activating Transcription Factor 3; Animals; Apoptosis; Ascorbic Acid; Bronchoalveolar Lavage Fluid; Disease Models, Animal; Epithelial Cells; Gene Expression Regulation, Enzymologic; Glutamate-Cysteine Ligase; Glutathione Disulfide; JNK Mitogen-Activated Protein Kinases; Lipid Peroxidation; Lung; Mice; Oxidation-Reduction; Oxidative Stress; Pulmonary Fibrosis; Respiratory Mucosa; Transcription, Genetic; Transforming Growth Factor beta1; Tyrosine | 2012 |
Carotid body and cardiorespiratory alterations in intermittent hypoxia: the oxidative link.
Intermittent hypoxia, a feature of obstructive sleep apnoea, potentiates ventilatory hypoxic responses, alters heart rate variability and produces hypertension, partially owing to an enhanced carotid body responsiveness to hypoxia. Since oxidative stress is a potential mediator of both chemosensory and cardiorespiratory alterations, we hypothesised that an antioxidant treatment may prevent these alterations. Accordingly, we studied the effects of ascorbic acid (1.25 g.L(-1) drinking water) on plasma lipid peroxidation, nitrotyrosine and inducible nitric oxide synthase (iNOS) immunoreactivity in the carotid body, ventilatory and carotid chemosensory responses to acute hypoxia, heart rate variability and arterial blood pressure in male Sprague-Dawley rats exposed to 5% O(2); 12 episodes.h(-1); 8 h.day(-1) or sham condition for 21 days. Intermittent hypoxia increased plasma lipid peroxidation, nitrotyrosine and iNOS expression in the carotid body, enhanced carotid chemosensory and ventilatory hypoxic responses, modified heart rate variability and produced hypertension. Ascorbic acid prevented the increased plasma lipid peroxidation and nitrotyrosine formation within the carotid body, and the enhanced carotid chemosensory and ventilatory responses to hypoxia, as well as heart rate variability alterations and hypertension. The present results support an essential role for oxidative stress in the generation of carotid body chemosensory potentiation and systemic cardiorespiratory alterations induced by intermittent hypoxia. Topics: Animals; Antioxidants; Ascorbic Acid; Carotid Body; Chemoreceptor Cells; Heart Rate; Hypertension; Hypoxia; Lipid Peroxidation; Lipids; Male; Malondialdehyde; Nitric Oxide Synthase Type II; Nitrosamines; Oxidative Stress; Pulmonary Ventilation; Rats; Sleep Apnea, Obstructive; Tyrosine | 2010 |
Ascorbic acid protects the newborn rat brain from hypoxic-ischemia.
Ascorbic acid (AA) is a potent antioxidant, and its neuroprotective effect has not been established yet. Using the Rice-Vannucci model, we examined the effect of AA on hypoxic-ischemic (HI) injury in the immature rat brain. Under isoflurane anesthesia, 7-day-old rat pups received 750 mg/kg of AA by intraperitoneal injection just before hypoxic exposure; 8% oxygen for 90 min. Vehicle controls received an equal volume of saline. AA decreased a macroscopic brain injury score at 48 and 168 h post-HI compared with vehicle controls (48 h post-HI, AA 1.38+/-0.45 vs. controls 2.94+/-0.24, p<0.05; 168 h post-HI, 1.13+/-0.44 vs. 2.50+/-0.25, p<0.05). AA injection significantly decreased the number of both necrotic and apoptotic cells in cortex, caudate putamen, thalamus and hippocampus, and also seemed to reduce the number of TUNEL-positive cells. Western blot analysis showed that AA significantly suppressed 150/145 kDa subunits of alpha-fodrin breakdown products (FBDP) in cortex, striatum, thalamus and hippocampus at 24 and 48 h post-HI, and also 120 kDa subunit of FBDP in all examined regions except for thalamus, which indicated that AA injection inhibited both calpain and caspase-3 activation. Western blot analysis of nitrotyrosine failed to show inhibition of free radical production by AA, however, our results show that AA inhibits both necrotic and apoptotic cell death and that AA is neuroprotective after HI in immature rat brain. Topics: Analysis of Variance; Animals; Animals, Newborn; Antioxidants; Apoptosis; Ascorbic Acid; Blotting, Western; Brain; Brain Ischemia; Calpain; Carrier Proteins; Caspase 3; Enzyme Activation; In Situ Nick-End Labeling; Microfilament Proteins; Microscopy, Electron; Necrosis; Neurons; Neuroprotective Agents; Rats; Tyrosine | 2009 |
Vitamin C intake attenuates the degree of experimental atherosclerosis induced by periodontitis in the rat by decreasing oxidative stress.
Periodontitis has been causally linked to cardiovascular disease, which is mediated through the oxidative stress induced by periodontitis. Since vitamin C has been suggested to limit oxidative damage, we hypothesized that vitamin C intake may reduce endothelial oxidative stress induced by periodontitis in the aorta. The aim of this study was to investigate the effects of vitamin C intake on the initiation of atherosclerosis in a ligature-induced rat periodontitis model.. Eighteen 8-week-old-male Wistar rats were divided into three groups of six rats and all rats received daily fresh water and powdered food through out the 6-week study. In the vitamin C and periodontitis groups, periodontitis was ligature-induced for the first 4 weeks. In the vitamin C group, rats were given distilled water containing 1 g/L vitamin C for the 2 weeks after removing the ligature.. In the periodontitis group, there was lipid deposition in the descending aorta and significant increases of serum level of hexanoyl-lysine (HEL), and aortic levels of nitrotyrosine expression, HEL expression and 8-hydroxydeoxyguanosine (8-OHdG) compared to the control group. Vitamin C intake significantly increased plasma vitamin C level and GSH:GSSG ratio (178% and 123%, respectively), and decreased level of serum HEL and aortic levels of nitrotyrosine, HEL and 8-OHdG (23%, 87%, 84%, and 38%, respectively).. These results suggest that vitamin C intake attenuates the degree of experimental atherosclerosis induced by periodontitis in the rat by decreasing oxidative stress. Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Aorta, Thoracic; Aortic Diseases; Ascorbic Acid; Atherosclerosis; Deoxyguanosine; Endothelium, Vascular; Glutathione; Lysine; Male; Oxidative Stress; Periodontitis; Random Allocation; Rats; Rats, Wistar; Tyrosine; Vitamins | 2009 |
Inhibition of retinopathy and retinal metabolic abnormalities in diabetic rats with AREDS-based micronutrients.
To investigate whether the micronutrients that were shown to reduce the risk of development of age-related macular degeneration in the Age-Related Eye Disease Study (AREDS) can have the same effect on the development of diabetic retinopathy in rats, and to understand the possible mechanisms.. Streptozotocin-induced diabetic rats received a powdered diet with or without supplemental micronutrients (ascorbic acid, vitamin E, beta-carotene, zinc, and copper). The retina was used after the rats had diabetes for 12 months to detect vascular histopathology and to measure the biochemical parameters and messenger RNA levels of the genes involved in oxidative and nitrative stress.. The AREDS-based micronutrients prevented a diabetes-induced increase in the number of retinal acellular capillaries. In the same rats, micronutrients inhibited increases in retinal oxidatively modified DNA and nitrotyrosine and decreases in manganese superoxide dismutase. Diabetes-induced alterations in the messenger RNA expression of mitochondrial electron transport complex III (coenzyme Q cytochrome-c reductase) and inducible nitric oxide synthase were also prevented.. Age-Related Eye Disease Study-based micronutrients inhibit the development of diabetic retinopathy in rodents by inhibiting oxidative and nitrative stress.. Micronutrients that slow down the onset and progression of age-related macular degeneration have the potential to inhibit the development of diabetic retinopathy. Topics: Animals; Ascorbic Acid; beta Carotene; Body Weight; Copper; Deoxyadenosines; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Diet; Eating; Electron Transport Complex III; Glycated Hemoglobin; Immunoenzyme Techniques; Male; Micronutrients; Nitric Oxide Synthase Type II; Oxidative Stress; Polymerase Chain Reaction; Rats; Rats, Inbred Lew; Retinal Vessels; RNA, Messenger; Superoxide Dismutase; Tyrosine; Vitamin E; Zinc Oxide | 2008 |
H2O2/nitrite-induced post-translational modifications of human hemoglobin determined by mass spectrometry: redox regulation of tyrosine nitration and 3-nitrotyrosine reduction by antioxidants.
Covalent modifications of proteins by endogenous reactive nitrogen oxide species lead to cytotoxic effects that are implicated in diseases associated with chronic infections and inflammation. Tyrosine nitration is a major post-translational modification of proteins by reactive nitrogen oxide species. Recent studies suggest that nitrotyrosine is not a permanent protein modification. We previously demonstrated that lipoyl dehydrogenase is capable of converting 3-nitrotyrosine into 3-aminotyrosine in the presence of certain reducing agents. In this study, we compared the abilities of various hemoproteins, hemin, and the cobalt-containing cofactor cyanocobalamin to mediate H(2)O(2)/nitrite-dependent tyrosine nitration and found that these hemoproteins and metal-containing cofactors also catalyzed the reduction of 3-nitrotyrosine to various extents in the presence of thiol reducing agents or ascorbate. The H(2)O(2)/nitrite-induced post-translational modifications of human hemoglobin identified by nanoLC/nanospray ionization tandem mass spectrometric analysis of the tryptic digest include nitration of tyrosine and tryptophan, as well as oxidation of methionine and cysteine residues. Nitration of human hemoglobin by H(2)O(2)/nitrite was detected on Tyr24 and Tyr42 (alpha-chain) and on Tyr130 and Trp15 (beta-chain) in the alphabeta-dimer. Oxidation of methionine and cysteine residues was also observed. Furthermore, hemoglobin also catalyzed nitro reduction of 3-nitrotyrosine to form 3-aminotyrosine, at Tyr24 in the alpha-chain peptide of human Hb in the presence of ascorbate. The enhanced peroxidase activity of nitrated hemoglobin can be reversed by the antioxidant ascorbate. These results suggest a possible in vivo pathway for hemoglobin contributing to denitration of nitrated proteins through redox regulation. Topics: Amino Acid Sequence; Antioxidants; Ascorbic Acid; Cysteine; Hemin; Hemoglobins; Humans; Hydrogen Peroxide; Methionine; Molecular Sequence Data; Nitrates; Nitrites; Oxidation-Reduction; Peroxidase; Protein Processing, Post-Translational; Reactive Nitrogen Species; Spectrometry, Mass, Electrospray Ionization; Trypsin; Tyrosine; Vitamin B 12 | 2008 |
Novel inhibitors of glycation and AGE formation.
Accelerated formation of advanced glycation/lipoxidation and endproducts (AGEs/ALEs) has been implicated in the pathogenesis of various diabetic complications. Several natural and synthetic compounds have been proposed and tested as inhibitors of AGE/ALE formation. We have previously reported the therapeutic effects of several new AGE/ALE inhibitors on the prevention of nephropathy and dyslipidemia in streptozotocin (STZ)-induced diabetic rats. In this study, we investigated the effects of various concentrations of a compound, LR-90, on the progression of renal disease and its effects on AGE and receptor for AGE (RAGE) protein expression on the kidneys of diabetic STZ-rats. Diabetic male Sprague-Dawley rats were treated with or without LR-90 (0, 5, 20, 25, and 50 mg/l of drinking water). After 32 weeks, body weight, glycemic status, renal function, and plasma lipids were measured. Kidney histopathology and AGE/ALE accumulation and RAGE protein expression in tissues were also determined. In vitro studies were also performed to determine the possible mechanism of action of LR-90 in inhibiting AGE formation and AGE-protein cross-linking. LR-90 protected the diabetic kidneys by inhibiting the increase in urinary albumin-to-creatinine ratio and ameliorated hyperlipidemia in diabetic rats in a concentration-dependent fashion without any effects on hyperglycemia. LR-90 treatment also reduced kidney AGE/ALE accumulation and RAGE protein expression in a concentration-dependent manner. In vitro, LR-90 exhibited general antioxidant properties by inhibiting metal-catalyzed reactions and reactive oxygen species (OH radical) and reactive carbonyl species (methlyglyoxal, glyoxal) generations without any effect on pyridoxal 5' phosphate. The compound also prevents AGE-protein cross-linking reactions. These findings demonstrate the bioefficacy of LR-90 in treating nephropathy and hyperlipidemia in diabetic animals by inhibiting AGE accumulation, RAGE protein expression, and protein oxidation in the diabetic kidney. Additionally, our study suggests that LR-90 may be useful also to delay the onset and progression of diabetic atherosclerosis as the compound can inhibit the expression of RAGE and inflammation-related pathology, as well as prevent lipid peroxidation reactions. Topics: Animals; Ascorbic Acid; Body Weight; Butyrates; Cholesterol; Creatinine; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Dyslipidemias; Glycation End Products, Advanced; Glycosylation; Hydroxyl Radical; Hypoglycemic Agents; Kidney; Lipid Metabolism; Lipoproteins, LDL; Male; Molecular Structure; Oxidation-Reduction; Pyridoxal Phosphate; Rats; Rats, Sprague-Dawley; Receptor for Advanced Glycation End Products; Receptors, Immunologic; Triglycerides; Tyrosine | 2007 |
Salivary uric acid at the acidic pH of the stomach is the principal defense against nitrite-derived reactive species: sparing effects of chlorogenic acid and serum albumin.
A complex antioxidant system is present in human saliva, with uric acid being the most concentrated component. Ascorbic acid, present at low concentrations in saliva, is actively secreted into the gastric lumen. We report that ascorbic acid added to human saliva at pH 2 was consumed within a few minutes, regenerating HNO(2), whereas uric acid was consumed relatively slowly in a nitrite-dependent manner. The consumption of uric acid was (i) rapid under normoxic conditions and slower at low oxygen tensions, (ii) coupled to *NO release, (iii) linked to the decrease in nitrite consumption and in nitrate formation, and (iv) unaffected by the nitrosation catalyst thiocyanate. Both chlorogenic acid and bovine serum albumin, representative of a phenol- and a protein-rich meal, respectively, were able to spare uric acid, although chlorogenic acid increased, whereas bovine serum albumin inhibited, *NO release. We hypothesize that the major role of uric acid in saliva at pH 2 could be to preserve the stomach from the formation of toxic nitrogen species and that low levels of uric acid, together with ascorbic acid consumption, may contribute to the high occurrence of tumors at the gastroesophageal junction and cardia. The sparing effects of dietary compounds may therefore be an important not fully appreciated effect. Topics: Animals; Ascorbic Acid; Chlorogenic Acid; Humans; Hydrogen-Ion Concentration; Nitric Oxide; Nitrogen Dioxide; Oxygen; Reactive Nitrogen Species; Saliva; Serum Albumin, Bovine; Stomach; Tyrosine; Uric Acid | 2006 |
Effects of antioxidant vitamin supplements on Helicobacter pylori-induced gastritis in Mongolian gerbils.
Epidemiological studies show that high intake of food-bound vitamin C and E reduces the risk of gastric cancer. Whether dietary supplementation with antioxidant micronutrients interferes with Helicobacter pylori infection and associated diseases is unclear. The aim of this study was to investigate if dietary vitamin C or E supplementation influences the progression of gastritis, gastric mucosal nitrosative and oxidative protein damage, gastric mucosal lipid peroxidation, or gastric mucosal oxidative DNA damage in H. pylori-infected Mongolian gerbils.. Gerbils were divided into four groups: H. pylori-infected animals fed with vitamin C- or vitamin E-supplemented food, and infected and uninfected animals given standard rodent food. Subgroups of animals were killed at different time-points until 52 weeks postinfection. Concentrations of 3-nitrotyrosine and thiobarbituric acid-reactive substances (TBARS) in the gastric mucosa were determined with an immunodot blot and a fluorometric method, respectively. Mucosal concentrations of carbonyl carbons on proteins and 8-hydroxydeoxyguanosine were determined by enzyme-linked immunosorbent assay. Gastritis was scored semiquantitatively.. Vitamin supplements had no effect on the colonization with H. pylori. Vitamin C as well as vitamin E supplements reduced mucosal 3-nitrotyrosine concentrations to normal levels in infected animals. Vitamin E supplements decreased mucosal protein carbonyls and TBARS in short-term gastritis. In addition, vitamin C supplements caused attenuated mucosal oxidative DNA damage and milder mucosal inflammation in short-term gastritis.. Vitamin C or vitamin E supplementation leads to some short-term protective effects on H. pylori-induced gastritis in Mongolian gerbils. These effects seem to subside over time when the infection persists. Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Antioxidants; Ascorbic Acid; Deoxyguanosine; Dietary Supplements; Disease Models, Animal; Gastric Mucosa; Gastritis; Gerbillinae; Helicobacter Infections; Helicobacter pylori; Male; Stomach Neoplasms; Thiobarbituric Acid Reactive Substances; Tyrosine; Vitamin E; Vitamins | 2005 |
Potential involvement of oxidative stress in cartilage senescence and development of osteoarthritis: oxidative stress induces chondrocyte telomere instability and downregulation of chondrocyte function.
Oxidative stress leads to increased risk for osteoarthritis (OA) but the precise mechanism remains unclear. We undertook this study to clarify the impact of oxidative stress on the progression of OA from the viewpoint of oxygen free radical induced genomic instability, including telomere instability and resulting replicative senescence and dysfunction in human chondrocytes. Human chondrocytes and articular cartilage explants were isolated from knee joints of patients undergoing arthroplastic knee surgery for OA. Oxidative damage and antioxidative capacity in OA cartilage were investigated in donor-matched pairs of intact and degenerated regions of tissue isolated from the same cartilage explants. The results were histologically confirmed by immunohistochemistry for nitrotyrosine, which is considered to be a maker of oxidative damage. Under treatment with reactive oxygen species (ROS; 0.1 micromol/l H2O2) or an antioxidative agent (ascorbic acid: 100.0 micromol/l), cellular replicative potential, telomere instability and production of glycosaminoglycan (GAG) were assessed in cultured chondrocytes. In tissue cultures of articular cartilage explants, the presence of oxidative damage, chondrocyte telomere length and loss of GAG to the medium were analyzed in the presence or absence of ROS or ascorbic acid. Lower antioxidative capacity and stronger staining of nitrotyrosine were observed in the degenerating regions of OA cartilages as compared with the intact regions from same explants. Immunostaining for nitrotyrosine correlated with the severity of histological changes to OA cartilage, suggesting a correlation between oxidative damage and articular cartilage degeneration. During continuous culture of chondrocytes, telomere length, replicative capacity and GAG production were decreased by treatment with ROS. In contrast, treatment with an antioxidative agent resulted in a tendency to elongate telomere length and replicative lifespan in cultured chondrocytes. In tissue cultures of cartilage explants, nitrotyrosine staining, chondrocyte telomere length and GAG remaining in the cartilage tissue were lower in ROS-treated cartilages than in control groups, whereas the antioxidative agent treated group exhibited a tendency to maintain the chondrocyte telomere length and proteoglycan remaining in the cartilage explants, suggesting that oxidative stress induces chondrocyte telomere instability and catabolic changes in cartilage matrix structure and composition. Our f Topics: Aged; Antioxidants; Ascorbic Acid; Cartilage, Articular; Cell Division; Cells, Cultured; Cellular Senescence; Chondrocytes; Disease Progression; DNA Replication; Female; Free Radicals; Genomic Instability; Glycosaminoglycans; Humans; Middle Aged; Organ Culture Techniques; Osteoarthritis, Knee; Oxidative Stress; Reactive Oxygen Species; Telomere; Tyrosine | 2005 |
Plasma nitrotyrosine levels, antioxidant vitamins and hyperglycaemia.
Studies on plasma nitrotyrosine (NT) levels, a measure of oxidative injury, in diabetes are limited and discordant; the amount of antioxidants might represent a possible explanation for the discordant results. The aim of this paper is to evaluate the association between plasma NT levels and glucose tolerance status, according to antioxidant vitamin intakes.. In three hundred men randomly selected from a population-based cohort, NT levels were measured and dietary intake assessed by a food-frequency questionnaire. Results NT values were similar in patients with diabetes (n = 34), impaired fasting glucose (n = 77) and normoglycaemic subjects (n = 189). However, in subjects with lower than recommended daily intakes of antioxidant vitamins C and A, NT levels were significantly higher in the diabetic patients. In a multiple regression model, after adjustments for age, body mass index (BMI) and smoking habits, NT levels were significantly associated with fasting glucose in patients with lower intakes of vitamin C (beta = 11.4; 95% CI 1.3-21.5) and vitamin A (beta = 14.9; 95% CI 3.9-25.9), but not in subjects with lower intake of vitamin E.. A significant positive correlation between NT levels and fasting glucose is evident only in the presence of a reduced intake of some antioxidant vitamins. These findings might explain, at least in part, the discrepant results of previous studies and, if confirmed by further studies, suggest a simple measure (a balanced diet) to alleviate the increased oxidative stress of diabetes. Topics: Age Factors; Antioxidants; Ascorbic Acid; Blood Glucose; Body Mass Index; Cohort Studies; Diabetes Mellitus; Diet; Humans; Hyperglycemia; Male; Middle Aged; Smoking; Tyrosine; Vitamin A; Vitamin E; Vitamins | 2005 |
Antioxidant intervention attenuates myocardial neovascularization in hypercholesterolemia.
Hypercholesterolemia (HC) and atherosclerosis can elicit oxidative stress, coronary endothelial dysfunction, and myocardial ischemia, which may induce growth-factor expression and lead to myocardial neovascularization. We tested the hypothesis that chronic antioxidant intervention in HC would attenuate neovascularization and preserve the expression of hypoxia-inducible factor (HIF)-1alpha and vascular endothelial growth factor (VEGF).. Three groups of pigs (n=6 each) were studied after 12 weeks of normal or 2% HC diet or HC+antioxidant supplementation (100 IU/kg vitamin E and 1 g vitamin C daily). Myocardial samples were scanned ex vivo with a novel 3D micro-CT scanner, and the spatial density and tortuosity of myocardial microvessels were determined in situ. VEGF mRNA, protein levels of VEGF and VEGF receptor-1, HIF-1alpha, nitrotyrosine, and superoxide dismutase (SOD) were determined in myocardial tissue. The HC and HC+antioxidant groups had similar increases in serum cholesterol levels. HC animals showed an increase in subendocardial spatial density of microvessels compared with normal (160.5+/-11.8 versus 95.3+/-8.2 vessels/cm2, P<0.05), which was normalized in HC+antioxidant (92.5+/-20.5 vessels/cm2, P<0.05 versus HC), as was arteriolar tortuosity. In addition, HC induced upregulation of VEGF, HIF-1alpha, and nitrotyrosine expression and decreased SOD expression and activity, all of which were preserved by antioxidant intervention.. Changes in myocardial microvascular architecture invoked by HC are accompanied by increases in HIF-1alpha and VEGF expression and attenuated by antioxidant intervention. This underscores a role of increased oxidative stress in modulating myocardial microvascular architecture in early atherogenesis. Topics: Animals; Antioxidants; Arteriosclerosis; Ascorbic Acid; Cardiotonic Agents; Coronary Circulation; Diet, Atherogenic; Dinoprost; Enzyme Induction; Female; Gene Expression Profiling; Gene Expression Regulation; Heart; Hypercholesterolemia; Hypoxia-Inducible Factor 1, alpha Subunit; Imaging, Three-Dimensional; Myocardial Ischemia; Neovascularization, Pathologic; Oxidative Stress; Superoxide Dismutase; Swine; Tomography, X-Ray Computed; Transcription Factors; Tyrosine; Vascular Endothelial Growth Factor A; Vitamin E | 2004 |
The nitric oxide synthase inhibitor N(G)-nitro-L-arginine decreases defibrillation-induced free radical generation.
to demonstrate that nitric oxide (NO) contributes to free radical generation after epicardial shocks and to determinethe effect of a nitric oxide synthase (NOS) inhibitor, N(G)-nitro-L-arginine (L-NNA), on free radical generation.. Free radicals are generated by direct current shocks for defibrillation. NO reacts with the superoxide (O2*-) radical to for peroxynitrite (O = NOO-), which is toxic and initiates additional free radical generation. The contribution of NO to free radical generation after defibrillation is not fully defined.. Fourteen open chest dogs were studied. In the initial eight dogs, 40 J damped sinusoidal monophasic epicardial shocks was administered. Using electron paramagnetic resonance, we monitored the coronary sinus concentration of ascorbate free radical (Asc*-), a measure of free radical generation (total oxidative flux). Epicardial shocks were repeated after L-NNA, 5 mg/kg IV. In six additional dogs, immunohistochemical staining was done to identify nitrotyrosine, a marker of reactive nitrogen species-mediated injury, in post-shock myocardial tissue. Three of these dogs received L-NNA pre-shock. After the initial 40 J shock, Asc*- rose 39 +/- 2.5% from baseline. After L-NNA infusion, a similar 40 J shock caused Asc*- to increase only 2 +/- 3% form baseline (P < 0.05, post-L-NNA shock versus initial shock). Nitrotyrosine staining was more prominent in control animals than dogs receiving L-NNA, suggesting prevention of O = NOO- formation.. NO contributes to free radical generation and nitrosative injury after epicardial shocks; NOS inhibitors decrease radical generation by inhibiting the production of O = NOO-. Topics: Animals; Ascorbic Acid; Dogs; Electric Countershock; Electron Spin Resonance Spectroscopy; Enzyme Inhibitors; Free Radicals; Histocytochemistry; Myocardium; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Peroxynitrous Acid; Superoxides; Tyrosine | 2004 |
Characterization of antioxidant and antiglycation properties and isolation of active ingredients from traditional chinese medicines.
There is considerable interest in the isolation of more potent antioxidant compounds to treat diseases involving oxidative stress. Thirty-three traditional Chinese medicine (TCM) extracts were examined for their antioxidant activity using the 2,2'-azinobis[3-ethylbenzothiazoline-6-sulfonate] (ABTS) assay. Five extracts with high activity (Cratoxylum cochinchinense, Cortex magnoliae officinalis, Psoralea corylifolia L, Curculigo orchioides Gaertn, and Glycyrrhiza uralensis Fisch.) were selected for further characterization. C. cochinchinense outperformed other extracts in most of the assays tested except phospholipid peroxidation inhibition, where P. corylifolia L showed higher activity. C. cochinchinense was particularly potent in inhibiting the formation of advanced glycation end products on proteins and strongly inhibited hypochlorous acid-induced DNA damage. We attempted to isolate the active ingredients from C. cochinchinense and obtained an extract (YCT) containing at least 90% mangiferin as identified by HPLC and mass spectrometry. However, YCT showed significantly higher activity in assays of phospholipid peroxidation, inhibition of protein glycation, and superoxide (O(2)(?-)) and peroxynitrite (ONOO(-)) scavenging, as compared with mangiferin, suggesting that the nonmangiferin constituents of YCT contribute to its additional antioxidant activities. Topics: Antioxidants; Ascorbic Acid; Benzothiazoles; Chromatography, High Pressure Liquid; Clusiaceae; DNA Damage; Dose-Response Relationship, Drug; Hypochlorous Acid; Lipid Peroxidation; Lipids; Mass Spectrometry; Medicine, Chinese Traditional; Models, Chemical; Nitrogen; Peroxynitrous Acid; Phenol; Phospholipids; Sulfonic Acids; Superoxides; Tyrosine; Xanthine Oxidase; Xanthones | 2004 |
Long-term vitamin C treatment increases vascular tetrahydrobiopterin levels and nitric oxide synthase activity.
In cultured endothelial cells, the antioxidant, L-ascorbic acid (vitamin C), increases nitric oxide synthase (NOS) enzyme activity via chemical stabilization of tetrahydrobiopterin. Our objective was to determine the effect of vitamin C on NOS function and tetrahydrobiopterin metabolism in vivo. Twenty-six to twenty-eight weeks of diet supplementation with vitamin C (1%/kg chow) significantly increased circulating levels of vitamin C in wild-type (C57BL/6J) and apolipoprotein E (apoE)--deficient mice. Measurements of NOS enzymatic activity in aortas of apoE-deficient mice indicated a significant increase in total NOS activity. However, this increase was mainly due to high activity of inducible NOS, whereas eNOS activity was reduced. Significantly higher tetrahydrobiopterin levels were detected in aortas of apoE-deficient mice. Long-term treatment with vitamin C restored endothelial NOS activity in aortas of apoE-deficient mice, but did not affect activity of inducible NOS. In addition, 7,8-dihydrobiopterin levels, an oxidized form of tetrahydrobiopterin, were decreased and vascular endothelial function of aortas was significantly improved in apoE-deficient mice. Interestingly, vitamin C also increased tetrahydrobiopterin and NOS activity in aortas of C57BL/6J mice. In contrast, long-term treatment with vitamin E (2000 U/kg chow) did not affect vascular NOS activity or metabolism of tetrahydrobiopterin. In vivo, beneficial effect of vitamin C on vascular endothelial function appears to be mediated in part by protection of tetrahydrobiopterin and restoration of eNOS enzymatic activity. Topics: Animals; Aorta; Apolipoproteins E; Arteriosclerosis; Ascorbic Acid; Biopterins; Cyclic AMP; Cyclic GMP; Dietary Supplements; Disease Models, Animal; Endothelium, Vascular; Enzyme Activation; In Vitro Techniques; Lipids; Male; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Superoxides; Time; Tyrosine; Vasomotor System; Vitamin E | 2003 |
Influence of epithelial lining fluid lipids on NO(2)-induced membrane oxidation and nitration.
Within the pulmonary epithelial lining layer (ELF), antioxidants such as ascorbic acid (AH(2)) and glutathione (GSH) react with inhaled nitrogen dioxide ((*)NO(2)) to produce reactive oxygen species (ROS) that induce cellular oxidation. Because the ELF contains unsaturated fatty acids (UFA), which potentially react with (*)NO(2) and/or the antioxidant-derived ROS, we studied the influence of aqueous phase model UFA [egg phosphatidylcholine (EggPC) liposomes] on exposure-induced oxidation and nitration of membranes. Our lung surface model used gas phase (*)NO(2) exposures of immobilized red cell membranes (RCM) overlaid with defined aqueous phases. Acetyl cholinesterase (AChE) activity, TBARS, and 3-nitrotyrosine (3-NT) were used to assess protein and lipid oxidation and RCM nitration, respectively. During (*)NO(2) exposure, AH(2) and GSH induced AChE loss and TBARS, which were unchanged with buffer only. Exposures of EggPC generated extensive TBARS but not AChE loss; addition of AH(2)/GSH to EggPC resulted in smaller AChE declines and fewer TBARS. 3-NT formation occurred with or without EggPC, low concentration antioxidants, SOD, catalase, or DTPA, but was inhibitable by desferrioxamine or high antioxidant concentrations. The data suggest that reaction/diffusion limitations govern (*)NO(2) distribution, that (*)NO(2) per se directly nitrates tyrosine residues within hydrophobic regions, and that the induction of secondary oxidative processes is dependent on nonlinear relationships among (*)NO(2) flux rates, antioxidant concentrations, and diffusivity of secondary reactive species. Topics: Acetylcholinesterase; Animals; Antioxidants; Ascorbic Acid; Blotting, Western; Bronchoalveolar Lavage Fluid; Catalase; Cell Membrane; Chelating Agents; Epithelial Cells; Erythrocytes; Glutathione; Humans; Liposomes; Lung; Male; Nitrogen Dioxide; Ovum; Oxidation-Reduction; Pentetic Acid; Phosphatidylcholines; Rats; Rats, Sprague-Dawley; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances; Tyrosine | 2003 |
C-reactive protein decreases prostacyclin release from human aortic endothelial cells.
In addition to being a risk marker for cardiovascular disease, much recent data suggest that C-reactive protein (CRP) promotes atherogenesis. Decreased endothelial NO and prostacyclin (PGI2) contribute to a proatherogenic and prothrombotic state. We have shown that CRP decreases endothelial NO synthase expression and bioactivity in human aortic endothelial cells (HAECs). PGI2 is a potent vasodilator and inhibitor of platelet aggregation. Hence, the aim of this study was to examine the effect of CRP on PGI2 release from HAECs and human coronary artery endothelial cells (HCAECs).. HAECs and HCAECs were incubated with human CRP (0 to 50 microg/mL for 24 hours). The release of PGF-1alpha, a stable product of PGI2, was also assayed in the absence and presence of a potent agonist, A23187. CRP significantly decreased PGF-1alpha release from HAECs under basal (48% decrease, P<0.001; n=5) and stimulated (26% decrease, P<0.01; n=5) conditions. CRP had no effect on PGI2 synthase (PGIS) mass. By increasing both superoxide and inducible NO synthase, CRP resulted in increased nitration of PGIS by peroxynitrite. The increased nitration and decreased activity of PGIS by CRP was reversed with peroxynitrite scavengers.. Thus, CRP decreases PGI2 release from HAECs by inactivating PGIS via nitration, additionally contributing to its atherogenicity. Topics: Aorta; Ascorbic Acid; C-Reactive Protein; Cells, Cultured; Coronary Vessels; Cytochrome P-450 Enzyme System; Endothelium, Vascular; Epoprostenol; Free Radical Scavengers; Humans; Intramolecular Oxidoreductases; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Peroxynitrous Acid; Prostaglandins F; Tyrosine; Uric Acid | 2003 |
Diabetes-induced activation of nuclear transcriptional factor in the retina, and its inhibition by antioxidants.
Oxidative stress is increased in the retina in diabetes, and long-term administration of antioxidants inhibits the development of retinopathy in diabetic rats. The purpose of this study is to determine how diabetes affects the activation of a redox-sensitive nuclear transcriptional factor in the retina, NF-kappaB, and its inhibition by antioxidants. Alloxan diabetic rats were assigned to receive standard diet or the diet supplemented with multiple antioxidants, including ascorbic acid, Trolox, dl alpha-tocopherol acetate, N-acetyl cysteine, beta-carotene, and selenium for up to 14 months. NF-kappaB activation, oxidative stress and nitric oxides were measured in the retina at 2, 8 and 14 months of diabetes. Retinal NF-kappaB was activated by about 60% at two months after induction of diabetes, remained activated for up to 14 months of diabetes, and the duration of diabetes had no effect on the intensity of NF-kappaB activation. Similarly, oxidative stress and nitric oxides were elevated by over 50% in the retina of rats diabetic for 14 months, and nitrotyrosine levels were elevated by over two folds. Administration of the antioxidants to the rats for the entire duration of diabetes inhibited activation of NF-kappaB and elevations in oxidative stress, nitric oxides and nitrotyrosine formation without ameliorating the severity of hyperglycemia. These in vivo results were confirmed by in vitro studies showing that high glucose activates NF-kappaB and elevates NO and lipid peroxides in both retinal endothelial cells and pericytes that can be inhibited by antioxidants. Thus, the results suggest that the activation of retinal NF-KB in diabetes is an early event in the development of retinopathy, and it remains active when the retinal capillary cell death is accelerating, and histopathology is developing. Beneficial effects of antioxidants on the development of diabetic retinopathy might involve inhibition of NF-kappaB activation and its downstream pathways in the retina. Topics: alpha-Tocopherol; Animals; Antioxidants; Ascorbic Acid; beta Carotene; Chromans; Cysteine; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Glucose; Lipid Peroxides; Male; NF-kappa B; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Rats; Rats, Sprague-Dawley; Retina; Selenium; Tyrosine | 2003 |
Comparison of uric acid and ascorbic acid in protection against EAE.
Serum levels of uric acid (UA), an inhibitor of peroxynitrite- (ONOO-) related chemical reactions, became elevated approximately 30 million years ago in hominid evolution. During a similar time frame, higher mammals lost the ability to synthesize another important radical scavenger, ascorbic acid (AA), leading to the suggestion that UA may have replaced AA as an antioxidant. However, in vivo treatment with AA does not protect against the development of experimental allergic encephalomyelitis (EAE), a disease that has been associated with the activity of ONOO- and is inhibited by UA. When compared in vitro, UA and AA were found to have similar capacities to inhibit the nitrating properties of ONOO-. However UA and AA had different capacities to prevent ONOO- -mediated oxidation, especially in the presence of iron ion (Fe3+). While UA at physiological concentrations effectively blocked dihydrorhodamine-123 oxidation in the presence of Fe3+, AA did not, regardless of whether the source of ONOO- was synthetic ONOO-, SIN-1, or RAW 264.7 cells. AA also potentiated lipid peroxidation in vivo and in vitro. In conclusion, the superior protective properties of UA in EAE may be related to its ability to neutralize the oxidative properties of ONOO- in the presence of free iron ions. Topics: Albumins; Animals; Antioxidants; Ascorbic Acid; Blood-Brain Barrier; Cell Line; Encephalomyelitis, Autoimmune, Experimental; Free Radicals; Immunohistochemistry; Iron; Lipid Peroxidation; Mice; Molsidomine; Myelin Sheath; Nitric Oxide; Oxygen; Peroxynitrous Acid; Rhodamines; Time Factors; Tyrosine; Uric Acid | 2002 |
Gamma-tocopherol supplementation inhibits protein nitration and ascorbate oxidation in rats with inflammation.
Gamma-tocopherol (gammaT) complements alpha-tocopherol (alphaT) by trapping reactive nitrogen oxides to form a stable adduct, 5-nitro-gammaT [Christen et al., PNAS 94:3217-3222; 1997]. This observation led to the current investigation in which we studied the effects of gammaT supplementation on plasma and tissue vitamin C, vitamin E, and protein nitration before and after zymosan-induced acute peritonitis. Male Fischer 344 rats were fed for 4 weeks with either a normal chow diet with basal 32 mg alphaT/kg, or the same diet supplemented with approximately 90 mg d-gammaT/kg. Supplementation resulted in significantly higher levels of gammaT in plasma, liver, and kidney of control animals without affecting alphaT, total alphaT+gammaT or vitamin C. Intraperitoneal injection of zymosan caused a marked increase in 3-nitrotyrosine and a profound decline in vitamin C in all tissues examined. Supplementation with gammaT significantly inhibited protein nitration and ascorbate oxidation in the kidney, as indicated by the 29% and 56% reduction of kidney 3-nitrotyrosine and dehydroascorbate, respectively. Supplementation significantly attenuated inflammation-induced loss of vitamin C in the plasma (38%) and kidney (20%). Zymosan-treated animals had significantly higher plasma and tissue gammaT than nontreated pair-fed controls, and the elevation of gammaT was strongly accentuated by the supplementation. In contrast, alphaT did not significantly change in response to zymosan treatment. In untreated control animals, gammaT supplementation lowered basal levels of 3-nitrotyrosine in the kidney and buffered the starvation-induced changes in vitamin C in all tissues examined. Our study provides the first in vivo evidence that in rats with high basal amounts of alphaT, a moderate gammaT supplementation attenuates inflammation-mediated damage, and spares vitamin C during starvation-induced stress without affecting alphaT. Topics: alpha-Tocopherol; Animals; Ascorbic Acid; Chromatography, High Pressure Liquid; gamma-Tocopherol; Inflammation; Kidney; Male; Nitrogen; Oxygen; Proteins; Rats; Rats, Inbred F344; Tissue Distribution; Tyrosine; Vitamin E; Zymosan | 2002 |
Oxidative stress in bacterial meningitis in humans.
To study reactive nitrogen species-mediated oxidative brain damage and antioxidant defenses in patients with acute bacterial meningitis.. Nitrotyrosine (a widely used marker for the formation of reactive nitrogen species, such as peroxynitrite) and the lipid peroxidation product 4-hydroxynonenal were detected by immunohistochemistry in brain specimens obtained at autopsy. CSF concentrations of nitrotyrosine were quantified by ELISA. CSF and serum concentrations of ascorbic acid, uric acid, and its oxidation product allantoin were determined by high-pressure liquid chromatography.. Tyrosine nitration was strongly increased during meningitis. It was most evident in inflammatory cells and blood vessels in the subarachnoid space. The same cell types stained positive for the lipid peroxidation marker 4-hydroxynonenal, suggesting that reactive nitrogen species contribute to oxidative brain damage during meningitis. High CSF nitrotyrosine concentrations were associated with an unfavorable outcome according to the Glasgow Outcome Score. In the CSF, the increase of nitrotyrosine was accompanied by a depletion of the antioxidant ascorbic acid and an increased oxidation of the natural peroxynitrite scavenger uric acid to allantoin.. These findings indicate that oxidative stress due to reactive nitrogen species and altered antioxidant defenses are involved in the pathophysiology of bacterial meningitis in humans. Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aldehydes; Allantoin; Ascorbic Acid; Brain; Cysteine Proteinase Inhibitors; Female; Free Radical Scavengers; Glasgow Outcome Scale; Humans; Immunohistochemistry; Male; Meningitis, Bacterial; Middle Aged; Neurons; Oxidative Stress; Reactive Nitrogen Species; Statistics as Topic; Treatment Outcome; Tyrosine; Uric Acid | 2002 |
Enhancement of glutathione cardioprotection by ascorbic acid in myocardial reperfusion injury.
The present experiment determined the effects of glutathione and ascorbic acid, the two most important hydrophilic antioxidants, on myocardial ischemia-reperfusion injury and evaluated their relative therapeutic values. Isolated rat hearts were subjected to ischemia (30 min) and reperfusion (120 min) and treated with ascorbic acid, glutathione monoethyl ester (GSHme), or their combination at the onset of reperfusion. Administration of 1 mM GSHme alone, but not 1 mM ascorbic acid alone, significantly attenuated postischemic injury (P < 0.05 versus vehicle). Most interestingly, coadministration of ascorbic acid with GSHme markedly enhanced the protective effects of GSHme (P < 0.01 versus vehicle). The protection exerted by the combination of GSHme and ascorbic acid at 1 mM each was significantly greater than that observed with 1 mM GSHme alone (P < 0.05). Moreover, treatment with GSHme alone or GSHme plus ascorbic acid markedly reduced myocardial nitrotyrosine levels, suggesting that these treatments attenuated myocardial peroxynitrite formation. These results demonstrated that 1) GSHme, but not ascorbic acid, exerted protective effects against ischemia-reperfusion injury; and 2) the protective effects of GSHme were further enhanced by coadministration with ascorbic acid, suggesting a synergistic effect between GSHme and ascorbic acid. Topics: Animals; Antioxidants; Ascorbic Acid; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Glutathione; Heart; Heart Rate; Incidence; Lipid Peroxidation; Myocardial Reperfusion Injury; Myocardium; Protective Agents; Rats; Reperfusion Injury; Tachycardia; Tyrosine; Ventricular Fibrillation | 2002 |
Lecithin-cholesterol acyltransferase activity during maturation of human preovulatory follicles with different concentrations of ascorbate, alpha-tocopherol and nitrotyrosine.
The enzyme lecithin-cholesterol acyltransferase (LCAT) transfers an acyl chain from lecithin to cholesterol or oestradiol, thus playing a crucial role in reverse cholesterol transport and follicular synthesis of potent long-lived oestrogens. The mechanism of catalysis is biphasic, as it is based on a phospholipase and an esterifying activity. Sulfhydryl groups were previously reported to be required for the esterification step. Lecithin-cholesterol acyltransferase has previously been shown to be inhibited by thiol oxidants such as peroxynitrite. Peroxynitrite also converts tyrosine to nitrotyrosines. In the present study, high levels of nitrotyrosine associated with low LCAT activity, and vice versa, were found in human preovulatory follicular fluids. Follicular fluids were also analysed for oestradiol (E) and progesterone (P) concentrations. The E/P ratio, which decreases as ovulation approaches, was used to evaluate the maturation status of each follicle. Enzyme activity was negatively correlated with the E/P ratio. Ascorbate (Asc) and alpha-tocopherol (Toc) were titrated in follicular fluid and plasma to evaluate their accumulation or consumption in the follicle. High LCAT activity was found in follicular fluids where Asc and Toc had accumulated, whereas lower activity was associated with Asc and Toc consumption. The consumption of both antioxidants was positively correlated with the E/P ratio. The results suggest that as follicle maturation progresses, Toc and Asc concentrations increase in follicular fluid, thus protecting LCAT from oxidative damage and loss of activity. Topics: alpha-Tocopherol; Ascorbic Acid; Cells, Cultured; Estradiol; Female; Follicular Fluid; Humans; Ovarian Follicle; Ovulation; Phosphatidylcholine-Sterol O-Acyltransferase; Progesterone; Titrimetry; Tyrosine | 2002 |
Is ceruloplasmin an important catalyst for S-nitrosothiol generation in hypercholesterolemia?
Nitric oxide (NO) reacts with thiol-containing biomolecules to form S-nitrosothiols (RSNOs). RSNOs are considered as NO reservoirs as they generate NO by homolytic cleavage. Ceruloplasmin has recently been suggested to have a potent catalytic activity towards RSNO production. Considering that NO activity is impaired in hypercholesterolemia and that RSNOs may act as important NO donors, we investigated the relation between concentrations of ceruloplasmin and RSNOs in plasma of hypercholesterolemic (HC) patients compared to normolipidemic (N) controls. Concentrations of ceruloplasmin (0.36 +/- 0.07 x 0.49 +/- 0.11 mg/dl, N x HC), nitrate (19.10 +/- 12.03 x 40.19 +/- 18.70 microM, N x HC), RSNOs (0.25 +/- 0.20 x 0.54 +/- 0.26 microM, N x HC), nitrated LDL (19.51 +/- 6.98 x 35.29 +/- 17.57 nM nitro-BSA equivalents, N x HC), and cholesteryl ester-derived hydroxy/hydroperoxides (CEOOH, 0.19 +/- 0.06 x 1.46 +/- 0.97 microM) were increased in plasma of HC as compared to N. No difference was found for nitrite levels between the two groups (1.01 +/- 0.53 x 1.02 +/- 0.33 microM, N x HC). The concentrations of RSNOs, nitrate, and nitrated LDL were positively correlated to those of total cholesterol, LDL cholesterol, and apoB. Ceruloplasmin levels were directly correlated to apoB and apoE concentrations. Data suggest that: (i) ceruloplasmin may have a role in the enhancement of RSNOs found in hypercholesterolemia; (ii) the lower NO bioactivity associated with hypercholesterolemia is not related to a RSNOs paucity or a defective NO release from RSNOs; and (iii) the increased nitrotyrosine levels found in hypercholesterolemia indicate that superoxide radicals contribute to inactivation of NO, directly generated by NO synthase or originated by RSNO decomposition. Topics: Apolipoproteins B; Ascorbic Acid; Catalysis; Ceruloplasmin; Cholesterol; Cholesterol Esters; Cholesterol, LDL; Humans; Hydrogen Peroxide; Hypercholesterolemia; Lipoproteins, LDL; Mercaptoethanol; Nitrates; Nitrites; Nitroso Compounds; S-Nitrosothiols; Tyrosine; Uric Acid; Vitamin E | 2001 |
Antioxidative properties of phenolic antioxidants isolated from corn steep liquor.
With the immersion of corn into dilute sulfur oxide during starch-manufacturing processes, corn steep liquor (CSL) remains as leftover material. CSL is often used for fermentation, but its components are not fully understood. To determine the properties of CSL, 12 p-coumaric acid-related compounds were isolated from an ethyl acetate extract of CSL with the guidance of antioxidative activity on the rabbit erythrocyte membrane ghost system. The activity of these compounds was compared against oxidative damages, and it was elucidated that the activity of p-coumaric acid derivatives was mainly affected by their functional groups at the 3-position and less by the conjugated side chain. Moreover, p-coumaric acid derivatives exhibited inhibitory activity stronger than that of tocopherols and ascorbic acid on peroxynitrite-mediated lipoprotein nitration. These findings that p-coumaric acid derivatives, which might play a beneficial role against oxidative damage, exist in CSL suggest this byproduct might be a useful resource of phenolic antioxidants. Topics: Acetates; Animals; Antioxidants; Ascorbic Acid; Chromatography, High Pressure Liquid; Coumaric Acids; Erythrocyte Membrane; Fermentation; Lipoproteins; Magnetic Resonance Spectroscopy; Nitrates; Phenols; Rabbits; Tyrosine; Vitamin E; Zea mays | 2001 |
Nitric oxide synthase inhibitors decrease coronary sinus-free radical concentration and ameliorate myocardial stunning in an ischemia-reperfusion model.
Our objective was to determine the effect of a nitric oxide synthase inhibitor, NG-nitro-L-arginine (L-NNA) on free radical generation and myocardial contractility after ischemia-reperfusion.. Cardiotoxic free radicals are generated by ischemia-reperfusion sequences. Nitric oxide reacts with superoxide radical to form peroxynitrite, which generates additional free radicals. Our hypothesis was that by inhibiting NO production, free radical formation will be diminished, which should be cardioprotective.. We studied 32 dogs. Coronary occlusion-reperfusion (20 min each) sequences were created by intracoronary balloon angioplasty inflation-deflation. Using electron paramagnetic resonance, we monitored the coronary sinus concentration of ascorbate free radical (Asc*-), a measure of total oxidative flux. The L-NNA (4.8 mg/kg total) was infused intravenously during occlusion-reperfusion; control dogs received saline. Immunohistochemical staining demonstrated the peroxynitration product nitrotyrosine.. In the control dogs Asc*- rose from 3.2 +/- SD 0.5 nmol/l to 4.8 +/- 1.1 nmol/l with reperfusion, a 50% rise. With L-NNA the Asc*- rose from 3.2 +/- 0.9 nmol/l to 4.0 +/- 1.2 nmol/l, a 25% rise (p < 0.01, L-NNA vs. control). Echocardiographic left ventricular fractional area shortening (FAS) in the control dogs declined from 38 +/- 19% (baseline) to 26 +/- 14% (ischemia), and to 22 +/- 11% with reperfusion (p < 0.01 vs. baseline). With L-NNA, FAS declined from 36 +/- 13% (baseline) to 27 +/- 12% (ischemia) but then rose to 33 +/- 14 with reperfusion (p = NS vs. baseline). Nitrotyrosine was present in the myocardium subjected to ischemia-reperfusion, but almost absent in dogs receiving L-NNA. Myocardial perfusion was not altered by L-NNA.. The NO synthase inhibitors decrease coronary sinus free radical concentration and ameliorate myocardial stunning after ischemia-reperfusion. Topics: Animals; Ascorbic Acid; Dogs; Electron Spin Resonance Spectroscopy; Enzyme Inhibitors; Hemodynamics; Myocardial Contraction; Myocardial Reperfusion Injury; Myocardial Stunning; Myocardium; Nitric Oxide Synthase; Nitroarginine; Superoxides; Tyrosine | 2001 |
Augmented oxidative stress of platelets in chronic smokers. Mechanisms of impaired platelet-derived nitric oxide bioactivity and augmented platelet aggregability.
We investigated whether impaired platelet-derived nitric oxide (PDNO) bioactivity and augmented platelet aggregability in chronic smokers are related to the imbalance of the intraplatelet redox state through increased oxidative stress.. Chronic smoking impairs PDNO release and augments platelet aggregability. However, their mechanisms are unknown.. Collagen-induced PDNO release, platelet aggregation, plasma and intraplatelet vitamin C and reduced glutathione (GSH), intraplatelet cyclic guanosine 3',5'-monophosphate (cGMP) and intraplatelet nitrotyrosine production, which is a marker of the peroxynitrite formation, were measured in 11 chronic smokers and 10 age-matched nonsmokers.. Release of PDNO and levels of intraplatelet cGMP were lower, and platelet aggregation was greater, in smokers than in nonsmokers. Intraplatelet vitamin C and GSH levels were lower in smokers than in nonsmokers. Intraplatelet nitrotyrosine production was greater in smokers than in nonsmokers. Next, we investigated the effects of oral vitamin C administration (2 g). After vitamin C administration, intraplatelet vitamin C levels were increased and not different at 2 h between the two groups. Then, PDNO release, intraplatelet cGMP levels and platelet aggregation in smokers were restored to the levels of nonsmokers. In smokers, PDNO release and consumption of GSH during platelet aggregation were inversely correlated, and consumption was much less after vitamin C administration. Vitamin C administration decreased intraplatelet nitrotyrosine production in smokers.. Impaired PDNO bioactivity and augmented platelet aggregability may be caused by an imbalance of the intraplatelet redox state through increased oxidative stress in smokers. Topics: Administration, Oral; Adult; Antioxidants; Ascorbic Acid; Biological Availability; Blood Platelets; Case-Control Studies; Chronic Disease; Cyclic GMP; Free Radical Scavengers; Glutathione; Humans; Male; Nitric Oxide; Oxidation-Reduction; Oxidative Stress; Peroxynitrous Acid; Platelet Aggregation; Smoking; Time Factors; Tyrosine | 2001 |
Synthesis of ascorbate and urate in the ovary of water buffalo.
Blood flow interruption is associated with oxygen depletion and loss of factors for function and survival in downstream tissues or cells. Hypoxia and absence of gonadotropins trigger apoptosis and atresia in the ovary. We studied the antioxidant response of follicular cells to plasma deprivation in ovaries dissected from water buffalo. Aliquots of follicular fluid were aspirated from each antral follicle, before and during incubation of the ovaries at 39 degrees C. Urate, ascorbate, retinol and alpha-tocopherol in the fluid were, titrated by High Performance Liquid Chromatography (HPLC) with spectrophotometric or spectrofluorimetric detection. The total antioxidant capacity of follicular fluid was determined as absorbance decrease, following addition of a source of radical chromophores. The more the incubation progressed, the higher levels of urate, ascorbate and total antioxidant capacity were found. Conversely, changes in concentration of the liposoluble antioxidants were not observed. Ascorbate synthesizing activity in the follicle was demonstrated by detecting the enzyme L-gulono-gamma-lactone oxidase in microsomes prepared from granulosa cells. These cells were also analyzed for the expression of the enzyme CPP32. The enzyme level, measured as DEVD-p-nitroanilide cleaving activity, was found related with the immunoreactivity to anti-CPP32 antibodies. Negative correlation between the enzyme activity (which is known to be induced by peroxynitrite) and the follicular level of urate (which scavenges peroxynitrite) was also observed. The amount of nitrotyrosine, a product of peroxynitrite attack on proteins, was measured in follicular fluids by Enzyme Linked ImmunoSorbent Assay (ELISA). This amount was found positively correlated with the CPP32 activity, and negatively correlated with the urate level in follicular fluid. Alterations in concentrations of ascorbate or urate may be associated with oxidative stress during follicular atresia. Topics: Animals; Antioxidants; Ascorbic Acid; Buffaloes; Caspase 3; Caspases; Chromatography, High Pressure Liquid; Enzyme-Linked Immunosorbent Assay; Female; Follicular Fluid; Granulosa Cells; L-Gulonolactone Oxidase; Microsomes; Ovary; Rats; Sugar Alcohol Dehydrogenases; Tyrosine; Uric Acid | 2001 |
Regulation of taurine transporter expression by NO in cultured human retinal pigment epithelial cells.
Taurine is actively transported at the retinal pigment epithelial (RPE) apical membrane in an Na(+)- and Cl(-)-dependent manner. Diabetes may alter the function of the taurine transporter. Because nitric oxide (NO) is a molecule implicated in the pathogenesis of diabetes, we asked whether NO would alter the activity of the taurine transporter in cultured ARPE-19 cells. The activity of the transporter was stimulated in the presence of the NO donor 3-morpholinosydnonimine. The stimulatory effects of 3-morpholinosydnonimine were not observed during the initial 16-h treatment; however, stimulation of taurine uptake was elevated dramatically above control values with 20- and 24-h treatments. Kinetic analysis revealed that the stimulation was associated with an increase in the maximal velocity of the transporter with no significant change in the substrate affinity. The NO-induced increase in taurine uptake was inhibited by actinomycin D and cycloheximide. RT-PCR analysis and nuclear run-on assays provided evidence for upregulation of the transporter gene. This study provides the first evidence of an increase in taurine transporter gene expression in human RPE cells cultured under conditions of elevated levels of NO. Topics: Animals; Antioxidants; Ascorbic Acid; Carrier Proteins; Cell Line; Diabetes Mellitus; Dose-Response Relationship, Drug; Glutathione; Humans; Immunohistochemistry; Membrane Glycoproteins; Membrane Transport Proteins; Methylene Blue; Mice; Mice, Inbred ICR; Molsidomine; Nitric Oxide; Nitric Oxide Donors; Nitroprusside; Pigment Epithelium of Eye; Protein Synthesis Inhibitors; Taurine; Time Factors; Tyrosine | 2001 |
Scavenging of peroxynitrite by oxyhemoglobin and identification of modified globin residues.
Peroxynitrite is a strong oxidant involved in cell injury. In tissues, most of peroxynitrite reacts preferentially with CO(2) or hemoproteins, and these reactions affect its fate and toxicity. CO(2) promotes tyrosine nitration but reduces the lifetime of peroxynitrite, preventing, at least in part, membrane crossing. The role of hemoproteins is not easily predictable, because the heme intercepts peroxynitrite, but its oxidation to ferryl species and tyrosyl radical(s) may catalyze tyrosine nitration. The modifications induced by peroxynitrite/CO(2) on oxyhemoglobin were determined by mass spectrometry, and we found that alphaTyr42, betaTyr130, and, to a lesser extent, alphaTyr24 were nitrated. The suggested nitration mechanism is tyrosyl radical formation by long-range electron transfer to ferrylhemoglobin followed by a reaction with (*)NO(2). Dityrosine (alpha24-alpha42) and disulfides (beta93-beta93 and alpha104-alpha104) were also detected, but these cross-linkings were largely due to modifications occurring under the denaturing conditions employed for mass spectrometry. Moreover, immunoelectrophoretic techniques showed that the 3-nitrotyrosine content of oxyhemoglobin sharply increased only in molar excess of peroxynitrite, thus suggesting that this hemoprotein is not a catalyst of nitration. The noncatalytic role may be due to the formation of the nitrating species (*)NO(2) mainly in molar excess of peroxynitrite. In agreement with this hypothesis, oxyhemoglobin strongly inhibited tyrosine nitration of a target dipeptide (Ala-Tyr) and of membrane proteins from ghosts resealed with oxyhemoglobin. Erythrocytes were poor inhibitors of Ala-Tyr nitration on account of the membrane barrier. However, at the physiologic hematocrit, Ala-Tyr nitration was reduced by 65%. This "sink" function was facilitated by the huge amount of band 3 anion exchanger on the cell membrane. We conclude that in blood oxyhemoglobin is a peroxynitrite scavenger of physiologic relevance. Topics: Ascorbic Acid; Carbon Dioxide; Dipeptides; Erythrocytes; Free Radical Scavengers; Globins; Humans; Immunoelectrophoresis; Mass Spectrometry; Nitrates; Oxyhemoglobins; Tyrosine | 2000 |
How urine analysis reflects oxidative stress--nitrotyrosine as a potential marker.
Enhanced oxidant stress involved in the pathogenesis of cardiovascular (heart failure, atherosclerosis, ischemia-reperfusion injury), neurodegenerative (M. Alzheimer), metabolic (hypercholesterolemia, diabetes) and inflammatory disorders is mimicked by non-intermittent therapy with nitrovasodilators. We used this latter therapy model to study urinary 3-nitrotyrosine (n-tyr) excretion as a potential biomarker that may reflect the enhanced generation of reactive oxygen species. Namely, free or protein-bound n-tyr is formed in the organism by nitration of tyrosine (residues) via peroxynitrite (reaction product of NO&z.ccirf; and O(2)(-)&z. ccirf;). Free n-tyr content was analyzed by gas chromatography in urine obtained from healthy human subjects under a nitrite-limited diet during a two-day non-intermittent transdermal administration of glyceroltrinitrate (GTN; 0.4 mg/h) with or without vitamin C (Vit-C; 55 microg/kg/min) as antioxidant. Concomitant with the development of complete vascular tolerance (loss of dilator action), a progressive increase in urinary n-tyr excretion (up to 186+/-9 microg/day) was demonstrated in volunteers given GTN only. In contrast, when Vit-C was added, the GTN-induced increases in urinary n-tyr content were significantly suppressed (up to 130.20+/-6.91 microg/day), whereas Vit-C alone even decreased urinary n-tyr content (down to 34.00+/-5.66 microg/day), which was below control values (56.0+/-3.4 microg/day). Thus, urinary n-tyr may serve as a biomarker to detect changes in oxidant stress and thereby to evaluate the efficacy of therapeutic interventions aimed at reducing oxidant stress under various pathophysiological conditions. Topics: Adult; Ascorbic Acid; Biomarkers; Chromatography, Gas; Enzyme-Linked Immunosorbent Assay; Female; Humans; Male; Middle Aged; Nitroglycerin; Oxidative Stress; Reference Values; Tyrosine; Urinalysis | 2000 |
Effect of beta-carotene on the transformation of tyrosine by nitrogen dioxide and peroxynitrous acid.
In the NO2-exposure of tyrosine in 70% dioxane/phosphate buffer (pH 7.4), beta-carotene enhanced the degradation of tyrosine and/or 3-nitrotyrosine produced, whereas alpha-tocopherol and ascorbyl palmitate inhibited the transformation of tyrosine into 3-nitrotyrosine. Generation of certain active species in the interaction of beta-carotene with NO2 was suggested. Ascorbyl palmitate effectively and alpha-tocopherol slightly inhibited the transformation of tyrosine in the NO2-exposure in the presence of beta-carotene. In the reaction of tyrosine with ONOO-/ONOOH, beta-carotene enhanced the degradation of 3-nitrotyrosine produced suggesting generation of certain active species, whereas alpha-tocopherol and ascorbyl palmitate completely suppressed the transformation of tyrosine into 3-nitrotyrosine. Topics: Ascorbic Acid; beta Carotene; Dioxanes; Dose-Response Relationship, Drug; Free Radical Scavengers; Nitrogen Dioxide; Nitrous Acid; Peroxynitrous Acid; Time Factors; Tyrosine; Vitamin E | 1999 |
Low toxicity of nitric oxide against endothelial cells under physiological oxygen partial pressures.
Cultured rat liver endothelial cells were incubated with 1 and 2 mM spermineNONOate at different O2 concentrations in the incubation atmosphere. (Z)-1-{N-[3-Aminopropyl]-N-[4-(3-aminopropylammonio) butyl]-amino}diazen-1-ium-1,2- diolate (spermineNONOate), at 2 mM, was highly cytotoxic at 21% and 95% O2 (as measured by lactate dehydrogenase release); more than 80% of the cells were damaged after 6 h of incubation. Cytotoxicity induced by 2 mM spermineNONOate was significantly decreased at 10%, 5% and 0% O2; cell death was 54%, 36% and 25% respectively after 6 h of incubation. In contrast, 1 mM spermineNONOate was almost non-toxic towards the cells. Only at 95% O2 was a slight damaging effect, of 25%, observed. The nitric oxide (.NO) concentrations released from 1 and 2 mM spermineNONOate were determined as varying between 5 and 12 microM and between 12 and 22 microM respectively as measured by the oxyhaemoglobin and the NO cheletropic spin-trapping methods. The decomposition rate of spermineNONOate and the resulting .NO concentrations were independent of O2 at all applied concentrations. Likewise, the steady-state concentrations of H2O2 remained at approx. 1 nM at all O2 concentrations, as measured with the fluorescent dye scopoletin. L-Tyrosine and L-ascorbate, both of which are known to scavenge reactive nitrogen species, markedly diminished spermineNONOate-induced cytotoxicity at 95% O2. The formation of 3-nitrotyrosine, indicating the reaction of L-tyrosine with nitrogen dioxide (.NO2) and/or peroxynitrite anions, was enhanced in incubations with spermineNONOate at 21% and 95% O2. The results demonstrate that at O2 partial pressures typically found under physiological conditions and at .NO concentrations that can occur in vivo, .NO alone is almost non-toxic towards cultured rat liver endothelial cells. .NO at these concentrations in vivo, however, exerts toxic effects at supraphysiological O2 partial pressures, owing to its oxidation to reactive nitrogen species such as .NO2. Topics: Animals; Ascorbic Acid; Cells, Cultured; Endothelium; Hydrogen Peroxide; Iron Chelating Agents; Liver; Nitric Oxide; Nitrogen Oxides; Oxygen; Rats; Spermine; Tyrosine | 1998 |
Protection against peroxynitrite-dependent tyrosine nitration and alpha 1-antiproteinase inactivation by ascorbic acid. A comparison with other biological antioxidants.
Peroxynitrite, formed by reaction of superoxide and nitric oxide, appears to be an important tissue-damaging species generated at sites of inflammation. In this paper, we compare the abilities of several biological antioxidants to protect against peroxynitrite-dependent inactivation of alpha 1-antiproteinase, and to inhibit tyrosine nitration upon addition of peroxynitrite. GSH and ascorbate protected efficiently in both systems. Uric acid inhibited tyrosine nitration but not alpha 1-antiproteinase inactivation. The possibility that ascorbic acid is an important scavenger of reactive nitrogen species in vivo is discussed. Topics: alpha 1-Antitrypsin; Antioxidants; Arthritis, Rheumatoid; Ascorbic Acid; Humans; Lipid Peroxidation; Nitrates; Oxidation-Reduction; Oxidative Stress; Pancreatic Elastase; Synovial Fluid; Tyrosine | 1996 |
Nitro-tyrosine as promoter of free radical damage in a DNA model system.
Nitro-tyrosine considerably promotes the degradation of DNA, when incubated with Cu2+ and ascorbate in oxygenated aqueous solution. This deleterious process requires oxygen and can be inhibited with catalase, indicating that H2O2 is involved, via the reduction of oxygen. Menadione and 2,4,6-trinitrobenzenesulfonate, known to catalyze particularly fast such reduction of oxygen, were only slightly more active than nitro-tyrosine. Degradation of DNA can be explained by a site-specific Fenton type reaction of H2O2 with the DNA-Cu+ complex, DNA-Cu+ + H2O2----DNA...OH + Cu2+ + OH- Copper-chelating agents (EDTA and penicillamine) prevent DNA degradation, whereas .OH-scavengers (t-butanol) are ineffective. The deleterious activity of nitro-tyrosine (and of other nitroaromatics) in the DNA model system may indicate important toxicological implications, since aromatic nitration is a significant mode of action of nitrogen dioxide. Topics: Ascorbic Acid; Cations, Divalent; Copper; DNA Damage; Free Radicals; Oxidation-Reduction; Tyrosine | 1986 |