Association between daily walking and antioxidant capacity in patients with symptomatic peripheral artery disease.

OBJECTIVE: The primary aim of the study was to assess whether both the amount and pace of daily walking were associated with circulating antioxidant capacity in symptomatic patients with peripheral artery disease (PAD). METHODS: Community-based walking was measured in 244 men and women who were limited by symptomatic PAD during a 1-week period in which they wore an ankle-mounted step activity monitor. Patients were further characterized by circulating antioxidant capacity with the OxiSelect (Cell Biolabs Inc, San Diego, Calif) hydroxyl radical antioxidant capacity (HORAC) activity assay. RESULTS: To assess the amount of walking, patients were grouped into low (≤2440 strides/d), middle (2441-3835 strides/d), and high (>3835 strides/d) stride tertiles. HORAC was higher in the middle (P = .03) and high (P = .01) stride tertiles than in the low tertile, but there was no difference between middle and high tertiles (P = .44). To assess the pace of walking, patients were grouped into slow (<25.0 strides/min), middle (25.0-31.6 strides/min), and fast (>31.6 strides/min) cadence tertiles. HORAC was higher in the high cadence tertile than in the low (P < .01) and middle (P < .01) tertiles, but there was no difference between low and middle tertiles (P = .48). Similar findings were obtained on group differences in HORAC after adjusting for age, sex, race, and ankle-brachial index for both the amount and pace of daily walking. CONCLUSIONS: Walking >2440 strides each day and walking at a cadence faster than 31.6 strides/min for 30 minutes each day are both associated with greater circulating antioxidant capacity in symptomatic patients with PAD. The clinical significance is that a home-based walking program may be one approach to increase endogenous antioxidant capacity.

[Influence of sodium nitrite exposure on sulfhemoglobin and hydroxyl radicals in mice].

Objective: To investigate the influence of sodium nitrite exposure on sulfhemoglobin and hydroxyl radicals in mice. Methods: A total of 60 mice were randomly divided into low-, middle-, and high-dose groups (the concentrations of sodium nitrite were 0.055 mg/ml, 0.110 mg/ml, and 0.220 mg/ml, respectively) and control group (treated with distilled water) , with 15 mice in each group (male/female ratio=1: 1) . A free-drink model was applied and the duration of exposure was 2 weeks. The body weight of all mice was recorded before exposure and at weeks 1 and 2 of exposure. At the end of exposure, the mice were treated with intraperitoneally injected sodium salicylate to capture the hydroxyl radicals and produce 2, 5-dihydroxybenzoic acid and 2, 3-dihydroxybenzoic acid, and high-performance liquid chromatography was used to measure their content. Spectrophotometry was used to measure the relative content of sulfhemoglobin. Results: At week 2 of exposure, the low-, middle-, and high-dose groups had significantly lower body weight than the control group (22.8±2.8 g/21.6±2.8 g/21.2±3.0 g vs 25.6±2.2 g, P<0.05) . The low-, middle-, and high-dose groups had a significantly higher total content of hydroxyl radicals than the control group[ (0.015 3±0.006 5) µg/ml, (0.016 4±0.017 2) µg/ml, and (0.062 7±0.091 0) µg/ml vs (0.009 ±0.007 3) µg/ml, P<0.05]. The relative content of sulfhemoglobin was 1.54%±0.73%, 2.22%±0.44%, and 2.80%±0.69%, respectively, in the low-, middle-, and high-dose groups, and the middle- and high-dose groups had a significant increase in the relative content of sulfhemoglobin compared with the control group (2.22%±0.44%/2.80%±0.69% vs 1.76%±0.60%, P<0.05) . The content of hydroxyl radicals was positively correlated with the relative content of sulfhemoglobin (r=0.837, P<0.05) . Conclusion: Sodium nitrite exposure can increase the content of sulfhemoglobin and hydroxyl radicals in blood, and there is a positive correlation between them.

Influence of Genista tinctoria L. or methylparaben on subchronic toxicity of bisphenol A in rats.

OBJECTIVE: To evaluate the influence of an extract of Genista tinctoria L. herba (GT) or methylparaben (MP) on histopathological changes and 2 biomarkers of oxidative stress in rats subchronicly exposed to bisphenol A (BPA). METHODS: Adult female Wistar rats were orally exposed for 90 d to BPA (50 mg/kg), BPA+GT (35 mg isoflavones/kg) or BPA+MP (250 mg/kg). Plasma and tissue samples were taken from liver, kidney, thyroid, uterus, ovary, and mammary gland after 30, 60, and 90 d of exposure respectively. Lipid peroxidation and in vivo hydroxyl radical production were evaluated by histological analysis along with malondialdehyde and 2,3-dihydroxybenzoic acid detection. RESULTS: The severity of histopathological changes in liver and kidneys was lower after GT treatment than after BPA or BPA+MP treatment. A minimal thyroid receptor antagonist effect was only observed after BPA+MP treatment. The abnormal folliculogenesis increased in a time-dependent manner, and the number of corpus luteum decreased. No significant histological alterations were found in the uterus. The mammary gland displayed specific estrogen stimulation changes at all periods. Both MP and GT revealed antioxidant properties reducing lipid peroxidation and BPA-induced hydroxyl radical generation. CONCLUSION: GT L. extract ameliorates the toxic effects of BPA and is proved to have antioxidant potential and antitoxic effect. MP has antioxidant properties, but has either no effect or exacerbates the BPA-induced histopathological changes.

Acute reduction of serum 8-iso-PGF2-alpha and advanced oxidation protein products in vivo by a polyphenol-rich beverage; a pilot clinical study with phytochemical and in vitro antioxidant characterization.

BACKGROUND: Measuring the effects of the acute intake of natural products on human biomarker concentrations, such as those related to oxidation and inflammation, can be an advantageous strategy for early clinical research on an ingredient or product. METHODS: 31 total healthy subjects were randomized in a double-blinded, placebo-controlled, acute pilot study with post-hoc subgroup analysis on 20 of the subjects. The study examined the effects of a single dose of a polyphenol-rich beverage (PRB), commercially marketed as "SoZo(®)", on serum anti-inflammatory and antioxidant markers. In addition, phytochemical analyses of PRB, and in vitro antioxidant capacity were also performed. RESULTS: At 1 hour post-intake, serum values for 8-iso-PGF2-alpha and advanced oxidation protein products decreased significantly by 40% and 39%, respectively. Additionally, there was a trend toward decreased C-reactive protein, and increased nitric oxide levels. Both placebo and PRB treatment resulted in statistically significant increases in hydroxyl radical antioxidant capacity (HORAC) compared to baseline; PRB showed a higher percent change (55-75% versus 23-74% in placebo group), but the two groups did not differ significantly from each other. CONCLUSIONS: PRB produced statistically significant changes in several blood biomarkers related to antioxidant/anti-inflammatory effects. Future studies are justified to verify results and test for cumulative effects of repeated intakes of PRB. The study demonstrates the potential utility of acute biomarker measurements for evaluating antioxidant/anti-inflammatory effects of natural products.

Cyclic nucleotides and mitogen-activated protein kinases: regulation of simvastatin in platelet activation.

BACKGROUND: 3-Hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have been widely used to reduce cardiovascular risk. These statins (i.e., simvastatin) may exert other effects besides from their cholesterol-lowering actions, including inhibition of platelet activation. Platelet activation is relevant to a variety of coronary heart diseases. Although the inhibitory effect of simvastatin in platelet activation has been studied; the detailed signal transductions by which simvastatin inhibit platelet activation has not yet been completely resolved. METHODS: The aim of this study was to systematically examine the detailed mechanisms of simvastatin in preventing platelet activation. Platelet aggregation, flow cytometric analysis, immunoblotting, and electron spin resonance studies were used to assess the antiplatelet activity of simvastatin. RESULTS: Simvastatin (20-50 microM) exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen than other agonists (i.e., thrombin). Simvastatin inhibited collagen-stimulated platelet activation accompanied by [Ca2+]i mobilization, thromboxane A2 (TxA2) formation, and phospholipase C (PLC)gamma2, protein kinase C (PKC), and mitogen-activated protein kinases (i.e., p38 MAPK, JNKs) phosphorylation in washed platelets. Simvastatin obviously increased both cyclic AMP and cyclic GMP levels. Simvastatin markedly increased NO release, vasodilator-stimulated phosphoprotein (VASP) phosphorylation, and endothelial nitric oxide synthase (eNOS) expression. SQ22536, an inhibitor of adenylate cyclase, markedly reversed the simvastatin-mediated inhibitory effects on platelet aggregation, PLCgamma2 and p38 MAPK phosphorylation, and simvastatin-mediated stimulatory effects on VASP and eNOS phosphorylation. CONCLUSION: The most important findings of this study demonstrate for the first time that inhibitory effect of simvastatin in platelet activation may involve activation of the cyclic AMP-eNOS/NO-cyclic GMP pathway, resulting in inhibition of the PLCgamma2-PKC-p38 MAPK-TxA2 cascade, and finally inhibition of platelet aggregation.

Ergometry induces systemic oxidative stress in healthy human subjects.

Oxidative stress is an important pathogenic factor of cancer and cardiovascular, metabolic and degenerative diseases. On the other hand, mild oxidative stress, as in case of physical exercise, can increase the antioxidant defense system. However, the mechanisms underlying such desirable effects of mild oxidative stress are not well understood, because the production of hydroxyl radical, the most aggressive oxygen free radical, was not yet evaluated under physiological circumstances. Therefore, in this study, we evaluated the overall production of hydroxyl radical using blood samples of ten healthy male students before and 1 h after ergometry. One h before exercise, they took salicylic acid (1g) orally so that hydroxyl radical was trapped with salicylic acid, yielding a measurable reaction product, 2,3-dihydroxybenzoic acid. Oxidative stress response to exercise was also evaluated in the volunteers without premedication by measuring serum peroxides and total antioxidant capacity of serum. These parameters of oxidative stress were then correlated with physical performance of the subjects. Ergometry caused an increase of the plasma hydroxyl radical level by 37.5% (p < 0.05), whereas the levels of total serum peroxides did not change significantly. Total serum antioxidant capacity, measured as uric acid equivalents, was higher after ergometry by 39.7% (p < 0.05), and was in positive correlation (r = 0.81) with anaerobic threshold, an indicator of physical condition. Hence, ergometry induces hydroxyl radical production and systemic oxidative stress response in the healthy subjects. Egometry could be used to study physiological oxidative stress response and to improve antioxidant defense capacities in humans.

Neonatal and maternal concentrations of hydroxil radical and total antioxidant system: protective role of placenta against fetal oxidative stress.

BACKGROUND: Reactive oxygen species (ROS) may cause peroxydation of lipids, proteins and deoxyribonucleic acids with subsequent cell damage. The hydroxyl radical (OH*) represents a measure of global oxidative stress. Hydroxyl radicals are short-lived; they form an important part of radical chemistry nonetheless. The measure of total antioxidant system (TAS) can give useful information about the extent of defence capable of counteracting the oxidative damage. Pregnancy is an important condition that favors oxidative stress in the fetus. Clinical studies indicate a protective mechanism against O2 toxicity in the human feto-placental unit. AIM: This study reports the OH* and TAS concentrations in mother and fetus at birth to evaluate the role of the placenta against fetal oxidative stress. METHODS: Blood samples were collected at delivery from 45 healthy women at term and from their newborns. The maternal and neonatal OH* and TAS concentrations were compared by paired Student t-test. RESULTS: OH* was higher in maternal blood than in cord blood (573.75+/- 170.0 UCarr/l vs 40.08+/-33.37 UCarr/l) (p<0.01); TAS concentrations did not differ between the two groups (1.11+/-0.09 mmol/l vs 1.17+/-0.12 mmol/l). Multiple regression analyses: maternal and neonatal OH* decreases with maternal age; only maternal TAS and OH* are related to gestational age in a nonlinear fashion. Female infants showed higher values of maternal and neonatal TAS as compared to male infants. CONCLUSION: TA protective role of the placenta against oxidative damage is in keeping with a large enough gradient of ROS (between mother and fetus) and the passage of TAS from mother to fetus.

[The functional properties and oxidative modification of plasma and neutrophil proteins in community-acquired pneumonia].

The functional properties of neutrophils (the activity of myeloperoxidase and the production of hydroxyl radical) were studied in community-acquired pneumonia (CAP) predominantly with the alveolar and interstitial types of lung parenchymal infiltration. Protein oxidative modification was estimated from the content of protein carbonyl derivatives in neutrophilic leukocytes and plasma and from the plasma concentration of bityrosine and oxidized tryptophan in patients with CAP. The production of hydroxyl radical and the activity of myeloperoxidase in the neutrophils of patients with CAP were increased and did not depend on the type of lung tissue infiltration. The development of oxidative stress in CAP was accompanied by the substantiation activation of protein oxidative modification processes in the neutrophilic leukocytes and plasma.

Synthesis and evaluation of lanthanide ion DOTA-tetraamide complexes bearing peripheral hydroxyl groups.

The use of lanthanide-based contrast agents for magnetic resonance imaging has become an integral component of this important diagnostic modality. These inert chelates typically possess high thermodynamic stability constants that serve as a predictor for in vivo stability and low toxicity. Recently, a new class of contrast agents was reported having a significantly lower degree of thermodynamic stability while exhibiting biodistribution profiles indicative of high stability under biological conditions. These observations are suggestive that the nature of contrast agent stability is also dependent upon the kinetics of complex dissociation, a feature of potential importance when contemplating the design of new chelates for in vivo use. We present a study of the kinetics of acid-catalyzed dissociation, thermodynamic stability, serum stability, and biodistribution of a series of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-tetraamide complexes that have been substituted with peripheral hydroxyl groups. The data indicate that these nontraditional contrast agents exhibit in vivo stability comparable to that of agents with much higher log K (ML) values, demonstrating the important contribution of kinetic inertness.

Oxidative stress, antioxidant capacity, biomolecule damage, and inflammation symptoms of sickle cell disease in children.

BACKGROUND: The phenotypic expression of sickle cell disease (SCD) is a complex pathophysiologic condition. However, sickle erythrocytes might be the cause for multiple sources of pro-oxidant processes with consequent linked to chronic and systemic oxidative stress. Herein, we explored the SCD phenomena could be the result in formation of oxidative stress as well as inflammation in children. MATERIAL AND METHODS: Blood samples of 147 SCD subjects were evaluated. A control group was formed of 156 individuals without SCD. Different oxidative stress markers and inflammatory mediators were measured by using various biochemical techniques. Plasma samples were collected from blood for the measurement of antioxidants and reactive oxygen species (ROS). RESULTS: The levels of plasma hydroxyl radical (HO•), and nitric oxide (NO) production were higher in SCD children in compared to control groups. The plasma antioxidants capacities such as superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx) and protein thiol levels were significantly reduced in SCD children. The plasma lipid peroxidation, protein carbonylation, DNA damage markers were significantly altered in different age groups of SCD children. Further, our results showed that SCD children have chronic inflammatory disease due to persistent alteration of haemoglobin content, reticulocyte, total bilirubin, platelet, creatinine, leukocytes, and altered expression of inflammatory mediators in compared to control groups. CONCLUSION: SCD children have high oxidative stress, and conversely, decreased antioxidant activity. Decrease in antioxidant activity might explained the reduction in lipid peroxidation, protein carbonylation and increased inflammation, which in turn intensify the symptoms of SCD in children.

The Antioxidative, Anti-inflammatory, and Liver-Protective Effects of Mycelia Selenium Polysaccharides from the Deep Root Mushroom, Oudemansiella radicata (Agaricomycetes).

In the present work, the mycelia polysaccharides (MPS) and mycelia selenium polysaccharides (MSPS) were obtained from Oudemansiella radicata. Their antioxidative, antiinflammatory, and hepatic-protective effects on lipopolysaccharide-induced liver damage in mice were investigated. The results showed that MSPS had potential effects on relieving liver injury by monitoring the serum levels of hypersensitive C-reactive protein, complement 3, and serum enzyme activities (aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase), enhancing the antioxidant enzymes abilities (superoxide dismutase, glutathione peroxidase, catalase, and total antioxidant capacity), and decreasing the lipid peroxidation (lipid peroxidation and malondialdehyde). Furthermore, the in vitro scavenging results indicated that the inhibition effects of MSPS on hydroxyl radicals and 1,1-diphenyl-2-picrylhydrazyl radicals reached 63.00 ± 3.59% and 68.86 ± 3.97%, respectively, at 1000 mg/L. These conclusions demonstrated that both MPS and MSPS might be suitable for functional foods and natural drugs for preventing acute liver damage.

Lipoic acid ameliorates oxidative stress and renal injury in alloxan diabetic rabbits.

The therapeutic potential of lipoic acid (LA) in diabetes and diabetic nephropathy treatment was elucidated. Alloxan diabetic rabbits were treated daily for three weeks with either 10 or 50 mg of LA per kg body weight (i.p.). The following parameters were measured: 1) serum glucose, urea, creatinine and hydroxyl free radical (HFR) levels; 2) blood glutathione redox state; 3) urine albumin concentration; 4) hepatic and renal HFR levels, GSH/GSSG ratios, cysteine contents and the activities of the enzymes of glutathione metabolism; and 5) the activity of renal NADPH oxidase. Histological studies of kidneys were also performed. The treatment of diabetic rabbits with 50 mg of LA resulted in lethal hypoglycaemia in 50% of animals studied. Although the low dose of LA did not change serum glucose concentration, it decreased serum urea and creatinine concentrations, attenuated diabetes-induced decline in GSH/GSSG ratio and abolished hydroxyl free radicals accumulation in serum, liver and kidney cortex. LA did not change the activities of the enzymes of glutathione metabolism, but it elevated hepatic content of cysteine, which limits the rate of glutathione biosynthesis. Moreover, LA lowered urine albumin concentration and attenuated glomerulopathy characteristic of diabetes. However, it did not affect diabetes-stimulated activity of renal NADPH oxidase. In view of these data, it is concluded that low doses of LA might be useful for the therapy of diabetes and diabetic nephropathy. Beneficial action of LA seems to result mainly from direct scavenging of HFR and restoring glutathione redox state due to elevation of intracellular cysteine levels.

Reactive oxygen species damaged human serum albumin in patients with type 1 diabetes mellitus: biochemical and immunological studies.

The role of hydroxyl radical (.OH) damaged human serum albumin (HSA) in type 1 diabetes has been investigated in the present study. Hydroxyl radical induced modification on HSA has been studied by UV absorption spectroscopy, ANS fluorescence and carbonyl estimation. Hydroxyl radical modified HSA was found to be highly immunogenic in rabbits as compared to native HSA. The binding characteristics of circulating autoantibodies in type 1 diabetes patients against native and modified HSA were assessed. Diabetes patients (n=31) were examined by direct binding ELISA and the results were compared with healthy age-matched controls (n=22). High degree of specific binding by 54.8% of patients sera towards .OH modified HSA, in comparison to its native analogue (p<0.05) was observed. Sera from those type 1 diabetes patients having smoking history, high aging with high degree of disease showed substantially stronger binding to .OH modified HSA over native HSA in particular. Normal human sera showed negligible binding with either antigen. Competitive inhibition ELISA reiterates the direct binding results. Gel retardation assay further substantiated the enhanced recognition of modified HSA by circulating autoantibodies in diabetes patients. The increase in total serum protein carbonyl levels in the diabetes patients was largely due to an increase in oxidized albumin. HSA of diabetes mellitus patients (DM-HSA) and normal subjects (normal-HSA) were purified on a Sephacryl S-200 HR column. Spectroscopic analysis confirmed that the DM-HSA samples contained higher levels of carbonyls than normal-HSA (p<0.001). DM-HSA was conformationally altered, with more exposure of its hydrophobic regions. Collectively, the oxidation of plasma proteins, especially HSA, might enhance oxidative stress in type 1 diabetes mellitus patients.

Hydroxyl radical generation, levels of tumor necrosis factor-alpha, and progression to heart failure after acute myocardial infarction.

OBJECTIVES: We used acetylsalicylic acid (ASA) as a probing agent to quantify hydroxyl radical ((*)OH) in Controls and patients with coronary artery disease and to prospectively investigate (*)OH production in patients with myocardial infarction (MI) complicated by heart failure (HF). BACKGROUND: Oxidative stress status (OSS) is a mechanism for transition to HF in experimental heart injury models, but evidence for its causal role in humans is still limited. METHODS: Thirty healthy subjects (Controls), 12 patients with stable angina (Group 1), and 74 patients with ST-segment elevation MI (Group 2) were enrolled. A dose of 250 mg Flectadol was given intravenously before each blood collection to determine the 2,3-dihydroxybenzoic acid/salicylic acid (DHBA/SA) ratio. We also quantified vitamin E and coenzyme Q(10) to monitor antioxidant reserve, as well as tumor necrosis factor (TNF)-alpha, TNF-soluble receptors, interleukin (IL)-6, and IL-1ra to assess inflammatory status. All measurements were repeated at month 6 in Group 2. RESULTS: There were no differences between Controls and Group 1. Group 2 showed increased (*)OH production, peaking at 24 h, whereas vitamin E and coenzyme Q(10) progressively declined. Group 2 patients developing HF during hospitalization (Group 2Bi) presented with an increase of both (*)OH production at discharge and inflammatory status, as compared with patients without HF (Group 2Ai), persisting at month 6 in post-MI patients with HF (Group 2Bii). CONCLUSIONS: We found a distinct pattern of (*)OH generation in post-MI patients who show progression to HF. The interplay between OSS and inflammatory status should be targeted as a possible mechanism of progression to post-MI left ventricular dysfunction.

Physical activity, plasma antioxidant capacity, and endothelium-dependent vasodilation in young and older men.

BACKGROUND: Sedentary aging is associated with oxidative stress and endothelial dysfunction. The aim of this study was to evaluate the relationship between long-term physical activity, plasma antioxidant status, and conduit artery endothelial function in young and older healthy men. METHODS: In young (n = 16) and older athletes (n = 16) and in matched healthy sedentary subjects, endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent response to glyceryl trinitrate (GTN), 400 microg, were measured in the brachial artery from high-resolution ultrasonography. Plasma malondialdehyde (MDA) and antioxidant capacity as total oxyradical scavenging capacity (TOSC) were also evaluated. RESULTS: We found that FMD was lower (< or =0.01) in sedentary older subjects (2.3% +/- 1.0%) as compared with older athletes (5.3% +/- 3.2%) and both sedentary (5.4% +/- 2.0%) and athletically trained (6.1% +/- 3.2%) young subjects. Sedentary older subjects showed higher (P < or = .05) MDA levels and lower (P < .0001) plasma antioxidant capacity as compared with the other subgroups, whereas in older athletes MDA levels and antioxidant capacity were similar to those observed in the young subgroups. In the whole group, FMD, but not GTN, was negatively related to age (r = -0.31, P < .05) and directly related (P < or = .01) to VO2max (r = 0.49) and TOSC against peroxyl (r = 0.69) and hydroxyl radicals (r = 0.53). In the multivariate analysis, TOSC against peroxyl radicals resulted as the most significant predictor of FMD (R2 = 0.60; P = .003). CONCLUSIONS: These results suggest that regular physical activity is associated with preserved antioxidant defenses and endothelial function in older individuals.

Oxidative stress in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is the most common form of muscular dystrophy affecting adults. The genetic basis of DM1 consists of a mutational expansion of a repetitive trinucleotide sequence (CTG). The number of triplets expansion divides patients in four categories related to the molecular changes (E1, E2, E3, E4). The pathogenic mechanisms of multi-systemic involvement of DM1 are still unclear. DM1 has been suspected to be due to premature aging, that is known to be sustained by increased free radicals levels and/or decreased antioxidants activities in neurodegenerative disorders. Recently, the gain-of-function at RNA level hypothesis has gained great attention, but oxidative stress might act in the disease progression. We have investigated 36 DM1 patients belonging to 22 unrelated families, 10 patients with other myotonic disorders (OMD) and 22 age-matched healthy controls from the clinical, biochemical and molecular point of view. Biochemical analysis detected blood levels of superoxide dismutase (SOD), malonilaldehyde (MDA), vitamin E (Vit E), hydroxyl radicals (OH) and total antioxidant system (TAS). Results revealed that DM1 patients showed significantly higher levels of SOD (+40%; MAL (+57%; RAD 2 (+106%; and TAS (+20%; than normal controls. Our data support the hypothesis of a pathogenic role of oxidative stress in DM1 and therefore confirm the detrimental role played by free radicals in this pathology and suggest the opportunity to undertake clinical trials with antioxidants in this disorder.

Scavenging of hydroxyl radicals generated in human plasma following X-ray irradiation.

There are various antioxidant materials that scavenge free radicals in human plasma. It is possible that the radical-scavenging function causes a radiation protective effect in humans. This study estimated the hydroxyl (OH) radical-scavenging activity induced by X-ray irradiation in human plasma. The test subjects included 111 volunteers (75 males and 36 females) ranging from 22 to 35 years old (average, 24.0). OH radicals generated in irradiated human plasma were measured by electron spin resonance (ESR). The relationships between the amount of the OH radical and chemical and biological parameters [total protein, total cholesterol, triglycerides and hepatitis B surface (HBs) antibodies] were estimated in the plasma of the 111 volunteers by a multivariate analysis. The presence of HBs antibodies had the greatest influence on OH radical-scavenging activity. One volunteer who did not have the HBs antibody was given an inoculation of the hepatitis B vaccine. There was a remarkable decrease in the amount of OH radical generated from plasma after the HBs antibody was produced. The results indicate that the HBs antibody is an important factor for the scavenging of OH radicals initiated by X-ray irradiation in the human body.

Stimuli-responsive electrodes detect oxidative stress and liver injury.

A digital point-of-care biosensor for measuring reactive oxygen species is presented based on novel reactive oxygen species responsive polymer-based electrodes. The biosensor is able to detect a drug-induced liver injury by monitoring the oxidative stress in the blood.

Hydroxyl radical generation in beta-thalassemic red blood cells.

To provide more experimental evidence for the proposed role of oxygen free radicals in red blood cell (RBC) damage in beta-thalassemia, hydroxyl radical generation was studied in thalassemic (Th) vs. normal (N) RBC. .OH fluxes were quantified by the conversion of salicylic acid (SA) into its hydroxylated products, 2,3- and 2,5-dihydroxybenzoic acids (DHBA) and catechol, assayed with HPLC coupled to electrochemical detection. No significant difference in spontaneous .OH generation between N-RBC and Th-RBC was found. Ascorbic acid (0.5-3.0 mM) induced many-fold increases in SA hydroxylation in a dose-dependent manner in both types of cells. In the presence of ascorbate (1.0 mM), the SA hydroxylated products were determined in Th-RBC vs. N-RBC as follows (nmol/ml): 2,5-DHBA, 1.45 +/- 0.06 vs. 1.81 +/- 0.05 (p = 0.001); 2,3-DHBA, 1.89 +/- 0.21 vs. 1.15 +/- 0.08 (p = 0.008) and catechol, 0.87 +/- 0.13 vs. 0.38 +/- 0.05 (p = 0.006). The results showed significant increase in the total SA hydroxylation in Th-RBC as compared to N-RBC with a tendency to form 2,3-DHBA and catechol at the expanse of 2,5-DHBA. The excessive .OH generation in Th-RBC is attributed to the abnormally high content of redox active iron in the cytosolic and/or membrane compartments of these cells.

Oxidative DNA base damage and antioxidant enzyme levels in childhood acute lymphoblastic leukemia.

We have investigated the levels of several antioxidant enzymes and the level of oxidative DNA base damage in lymphocytes of children with acute lymphoblastic leukemia (ALL) and in disease-free children. Children with ALL had just been diagnosed with the disease and had received no therapy prior to obtaining blood samples. A multitude of typical hydroxyl radical-induced base lesions in lymphocyte DNA of children were identified and quantified by gas chromatography-isotope dilution mass spectrometry. Higher levels of DNA base lesions were observed in patients with ALL than in children without the disease. The levels of the antioxidant enzymes glutathione peroxidase, catalase and superoxide dismutase in lymphocytes of ALL patients were lower than in lymphocytes of controls. These findings are in agreement with earlier observations in various types of adulthood cancer. Some of the identified DNA base lesions are known to possess premutagenic properties and may play a role in carcinogenesis. The results may indicate a possible link between decreased activities of antioxidant enzymes and increased levels of DNA base lesions due to oxidative damage, and support the notion that free radical reactions may be increased in malignant cells.