Pablo Evelson

Oxidative stress markers in aqueous humor of glaucoma patients.

PURPOSE Oxidative stress and antioxidant status in eye tissues may be associated with glaucomatous damage. The aim of this study was to establish the antioxidant status of aqueous humor of patients with primary open-angle glaucoma. For this purpose the authors measured the total reactive antioxidant potential (TRAP) and the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase. DESIGN Case control study. METHODS Aqueous humor was obtained at the time of surgery from 24 patients with glaucoma and 24 cataract patients; TRAP was measured by chemiluminescence. Activities of the antioxidant enzymes were measured spectrophotometrically. Superoxide dismutase activity was determined by inhibition of the rate of adrenochrome formation at 480 nm. Catalase activity was evaluated by decrease of H(2)O(2) absorbance at 240 nm. Glutathione peroxidase (GPx) activity was determined following nicotinamide adenine dinucleotide phosphate oxidation at 340 nm. RESULTS Total reactive antioxidant potential value of the cataract group was 124 +/- 5 micromol/l Trolox. This value was significantly decreased, by 64%, in glaucoma patients. An increase of 57% in SOD activity was observed in glaucoma patients when compared with cataract patients (41.7 +/- 2.7 U SOD/ml). Glutathione activity was threefold higher in glaucoma patients than in the cataract group (6.1 +/- 0.6 U/ml). No significant changes were found in catalase levels. CONCLUSIONS Oxidative stress may lead to an induction of antioxidant enzymes and contribute to TRAP decrease. Superoxide dismutase, GPx activities, and TRAP may be useful oxidative stress markers in aqueous humor of glaucoma patients.

Soccer players under regular training show oxidative stress but an improved plasma antioxidant status

Physical activity is known to induce oxidative stress in individuals subjected to intense exercise. In this study, we investigated the lipoprotein profile and the plasma antioxidant status in a group of soccer players engaged in a regular training programme. As was expected for aerobic exercise, high-density lipoprotein-cholesterol (HDL-C) and HDL3-C levels were significantly increased in the sportsmen (P<0.05). Total plasma antioxidant capacity was 25% higher in sportsmen than in controls (P<0.005). Accordingly, plasma hydrosoluble antioxidant levels (ascorbic acid and uric acid) were found to be significantly elevated in the soccer players (P<0.005). In addition, these subjects showed high concentrations of alpha-tocopherol in plasma compared with controls (P<0.005). Furthermore, an increase in plasma superoxide dismutase activity was also observed in relation to exercise (P<0.01). The elevation in plasma activities of antioxidant enzymes and the higher levels of free radical scavengers of low molecular mass may compensate the oxidative stress caused by physical activity. High levels of high-density lipoprotein in plasma may offer additional protection by inhibiting low-density lipoprotein oxidation and thus liposoluble antioxidant consumption. Therefore, soccer players under regular training show an improved plasma antioxidant status in comparison to sedentary controls.

Oxidative stress in muscle and liver of rats with septic syndrome

Sepsis, as infection associated to systemic manifestations, was produced in rats by cecal ligation and double perforation. Sham-operated rats were used as controls. The spontaneous chemiluminescence of rat adductor muscle and liver were measured at 6, 12, 24, and 30 h after the surgical procedure. Muscle chemiluminescence showed a maximal increase of about twofold (control emission 10 +/- 1 cps/cm2) after 6-12 h of sepsis, while liver chemiluminescence increased by about 80% (control emission: 11 +/- 1 cps/cm2) after 24 h of sepsis. The activities of muscle antioxidant enzymes were found maximally diminished after 12 h of sepsis: 46% decrease for Mn-superoxide dismutase, 83% decrease for catalase, and 55% decrease for glutathione peroxidase. In liver, only catalase activity showed a 52% decrease after 24 h of sepsis. State 3 oxygen uptake of muscle mitochondria with either malate-glutamate or succinate as substrates was 40% decreased after 12 h of sepsis in both cases. State 4 oxygen uptake of muscle mitochondria was not affected. The rate of H2O2 production of muscle mitochondria after 12 h of sepsis with either malate-glutamate or succinate as substrates was increased about 2.5 times but was not affected when assayed in the presence of as rotenone and antimycin. The oxygen uptake of liver mitochondria isolated from septic rats did not show differences as compared with those of control rats after 6 to 24 h of sepsis. Oxidative stress appears to occur in skeletal muscle early at the onset of the septic syndrome, with inhibition of active mitochondrial respiration and inactivation of antioxidant enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxidative stress and in vivo chemiluminescence in mouse skin exposed to UVA radiation

Mouse skin was exposed to UVA radiation (320-400 nm). The in vivo chemiluminescence of the skin was measured after irradiation. Chemiluminescence showed a maximum 13-fold increase (control emission, 10 +/- 1 cps cm-2) after 45-60 min of exposure to UVA, with no further increase with 60 min additional exposure. Spectral analysis of the emitted chemiluminescence showed that the principal species emitted in the 400-500 nm range. Topical application with alpha-tocopherol (10% v/w) and beta-carotene (1 mM) greatly reduced the UVA-induced skin chemiluminescence. Thiobarbituric acid reactive substance (TBARS) levels were increased by 130% in skin homogenates after 2 h of exposure to UVA (control value, 77 +/- 14 nmol malonaldehyde equivalents (g tissue)-1). The activities of antioxidant enzymes in skin homogenates were decreased after 2 h of irradiation: the superoxide dismutase (SOD) activity (control value, 181 +/- 10 U SOD (g tissue)-1) was decreased by 40% and the catalase activity (control value, 1.34 +/- 0.14 pmol (g tissue)-1) was decreased by 45%. In vivo chemiluminescence appears to be a suitable method for following the kinetics of the oxidative stress processes and for testing the effect of topical application with antioxidant and photoprotective agents.

Antioxidant levels from different Antarctic fish caught around south Georgia island and Shag Rocks.

Abstract Antarctic fish have been isolated for over several million years in an environment with a very low and constant temperature and high oxygen concentration. In such conditions the oxidative stress might be an important factor affecting their metabolic adaptive strategies. Activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), vitamin E levels and total antioxidant capacity (TRAP) were measured in liver, gill, heart and muscle homogenates of red-blooded (Nototheniidae) and white-blooded (Channichthyidae) Antarctic fish. SOD activity was also measured in blood samples. Gill SOD activity was threefold higher in channichthyids than in nototheniids while CAT and GPx were significantly higher in the gills of channichthyids. The increased SOD activity of channichthyids probably reflects the large PO2 gradient across their gills. The H2O2 produced seems to be preferentially eliminated by diffusion, according to the low levels of CAT and GPx found in the gills of these species. In contrast, blood SOD was about fivefold higher in the latter group, which possesses erythrocytes and thus a much higher oxygen-carrying capacity. CAT activity was always higher in nototheniids except in muscle. However, vitamin E did not show clear differences between families except for the pattern observed in muscle. The higher content of vitamin E in this tissue shown in channichthyids is related to the higher volume density of mitochondria reported for this group, since vitamin E is responsible for preventing membrane lipid peroxidation. Accordingly, TRAP (representative of hydrosoluble antioxidant capacity) was also higher in muscle of channichthyids. This is probably related to the role of ascorbic (a hydrosoluble compound) acid in regenerating vitamin E.

Higher antioxidant defences in plasma and low density lipoproteins from rugby players

Background Even if physical activity constitutes a well‐known antiatherogenic factor, the precise mechanisms underlying this protective effect are not completely clear.

HYDROGEN PEROXIDE METABOLISM AND OXIDATIVE STRESS IN CORTICAL, MEDULLARY AND PAPILLARY ZONES OF RAT KIDNEY

The cortical, medullary and papillary regions of rat kidney were evaluated for a series of parameters related to hydrogen peroxide metabolism and oxidative stress. The rates of oxygen uptake, prostaglandin synthesis and malondialdehyde production by kidney slices were: 47, 0.003 and 0.051 mumol/h g wet wt., respectively, in cortex, 32, 0.023 and 0.035 in medulla and 22, 0.034 and 0.007 in papilla. The activities of superoxide dismutase, catalase and glutathione peroxidase were: 144 +/- 16 U/g wet wt., 880 +/- 100 pmol/g wet wt. and 177 +/- 16 U/g wet wt. in cortex; 97 +/- 9 U/g wet wt., 550 +/- 50 pmol/g wet wt. and 142 +/- 18 U/g wet wt. in medulla; and 23 +/- 2 U/g wet wt., 90 +/- 9 pmol/g wet wt. and 147 +/- 5 U/g wet wt. in papilla. Hydrogen peroxide steady-state concentrations were 0.09 +/- 0.01, 0.07 +/- 0.01 and 0.08 +/- 0.01 microM whereas alpha-tocopherol content was 21 +/- 2, 23 +/- 1 and 34 +/- 3 mumol/g wet wt. and hydroperoxide-initiated chemiluminescence was 22 +/- 2, 33 +/- 2 and 14 +/- 1 cpm. 10(-3)/mg prot for cortex, medulla and papilla, respectively. After 60 min ischemia-30 min reperfusion hydroperoxide-initiated chemiluminescence and hydrogen peroxide steady-state concentration increased by 30% and 60% in cortex and 80% and 60% in medulla, whereas alpha-tocopherol content decreased by 30%, 50% and 2% in cortex, medulla and papilla, respectively. The reperfusion/control ratio of hydroperoxide-initiated chemiluminescence and hydrogen peroxide steady-state concentrations in cortex and medulla indicate the occurrence of oxidative stress after ischemia-reperfusion. The lower sensitivity to oxidative stress found in papilla could be explained by the relatively high relationship of alpha-tocopherol content to hydrogen peroxide production rate in this sub-organ.

The oxidative stress and the mitochondrial dysfunction caused by endotoxemia are prevented by α-lipoic acid

The aims of this work were to study the mitochondrial function and to evaluate (a) the oxidative stress in real time in an acute model of endotoxemia and (b) the effect of α-lipoic acid (LA, 100 mg/kg) as a therapeutic strategy to be considered. In rats treated with lipopolisaccharide (LPS, 10 mg/kg), a 1.4-fold increase was observed in in situ skeletal muscle chemiluminescence. Experimental sepsis increased oxygen consumption in tissue cubes (1 mm3) by 30% for heart and diaphragm and impaired state 3 mitochondrial respiration rate in the three organs (liver, diaphragm and heart) studied. Only complex I activity in heart and diaphragm and complex IV activity in diaphragm were found impaired in this septic model. The production of NO by submitochondrial membranes was found increased by 80% in the diaphragm and by 35% in the heart of septic rats. The treatment with LA prevented the oxidative stress and mitochondrial dysfunction observed in this model.

Hydrogen peroxide increases Na+/K+-ATPase function in alveolar type II cells

We have studied the regulation of Na+/K(+)-ATPase function in alveolar type II cells submitted to oxidative stress. Alveolar type II cells were isolated from Sprague Dawley rats and suspended in Dulbeccos modified Eagles medium. 500 muM xanthine plus 0.5 or 5 mU/ml xanthine oxidase (group 1 and 2, respectively) were added to the cell suspensions. Following various exposure times the reaction was stopped by adding allopurinol and cells were processed to assay H2O2 steady state concentrations, enzymatic activity of catalase and Na+/K(+)-ATPase function. Hydrogen peroxide production by the xanthine-xanthine oxidase system reached maximal values at 30 min of incubation in both groups. H2O2 steady state concentration increased 2- and 10-fold, respectively. Catalase activity was not changed after slight oxidative stress (group 1) but decreased in severe oxidative stress (group 2). Decreases in the Na+/K(+)-ATPase activity (10 and 60% for groups 1 and 2) were found during the first hour of exposure coinciding with the peak in H2O2 steady state concentration. This early inactivation was followed by progressive increases in the activity up to 70% over the control value in group 1, and to the control value in group 2. [3H]Ouabain binding studies showed that the increase in Na+/K(+)-ATPase activity after oxidative stress was due to an increase in the number of phosphorylated pump molecules in the plasma membrane of alveolar type II cells.

Time Course Changes of Oxidative Stress Markers in a Rat Experimental Glaucoma Model

PURPOSE To evaluate the relationship between oxidative stress markers and increased intraocular pressure in experimental glaucoma. METHODS In vivo chemiluminescence (CL), total antioxidant capacity (TRAP), nitrite concentration (NC), and lipid peroxidation markers (TBARS) were evaluated. Wistar rats (n=18 for each time point) underwent operation, and two episcleral veins were cauterized. RESULTS Decreases of 22%, 35%, and 27% at 7, 15, and 30 days and an increase of 22% at 60 days in CL were observed in glaucomatous eyes. In optic nerve, TBARS values were 6.9+/-0.5 nmol/mg protein (7 days), 9.4+/-0.4 nmol/mg protein (15 days), 18.0+/-1.2 nmol/mg protein (30 days), and 43.1+/-5.3 nmol/mg protein (60 days) (control, 6.2+/-0.4 nmol/mg protein; P<0.001). NC was 37.0+/-1.8 microM (7 days), 31.4+/-1.2 microM (15 days), 39.6+/-1.3 microM (30 days), and 40.0+/-1.3 microM (60 days) (control, 21.1+/-1.7 microM; P<0.001). In glaucomatous vitreous humor, TRAP decreased by 42% at 15 days and 78% at 60 days (control, 414+/-29 microM; P<0.001). In glaucomatous aqueous humor, TRAP values were 75+/-7 microM (7 days), 54+/-4 microM (15 days), 25+/-4 microM (30 days), and 50+/-3 microM (60 days) (control, 90+/-10 microM; P<0.001). CONCLUSIONS Reactive species were increased in glaucoma, as evidenced by the increases in CL, TBARS, and NC. The decrease in the antioxidant levels may be a consequence of an increase in oxidative processes.