Claudia Reides

Oxidative stress in blood of HIV infected patients

The oxidative stress in human erythrocytes was studied in asymptomatic and symptomatic patients infected by the human immunodeficiency virus (HIV), and patients with the acquired immunodeficiency syndrome (AIDS). tert-Butyl hydroperoxide initiated chemiluminescence, superoxide dismutase and catalase activities, and total glutathione were evaluated in the erythrocytes and the total antioxidant capacity in the plasma of control, patients infected with HIV that have not yet developed acquired immunodeficiency syndrome, and patients in the later stage of AIDS. tert-Butyl hydroperoxide initiated chemiluminescence was increased by 33% in asymptomatic (stage A1) and symptomatic patients (stage B2) infected with HIV and 82% for patients with AIDS (stage B3) (P < 0.05). While catalase activity did not show any difference between patients and controls, other indices showed differences that, in some cases, reached statistical significance. Superoxide dismutase activity was increased by 24% in stages A1 and B2 of HIV infection and 65% in patients in stage B3 (P < 0.05). Glutathione was decreased by 20% in stages A1 and B2, and by 32% in stage B3 patients (P < 0.05). Total plasma antioxidant capacity was increased in 30 and 57% for the asymptomatic and AIDS patients groups, respectively (P < 0.05). The data indicate that erythrocytes oxidative stress is associated with the progressive development of HIV disease. Parameters indicating oxidative stress could be an interesting form to screen the evolution of these patients and their response to anti-oxidant therapies.

The antioxidant enzymatic blood profile in Alzheimer's and vascular diseases. Their association and a possible assay to differentiate demented subjects and controls

A study of several elements of the antioxidative system: Cu-Zn superoxide dismutase (SOD), catalase (CAT), glutathione system (GLU), chemiluminescence (CHE), and antioxidant capacity (AOX), was conducted in 20 demented probable Alzheimers (DAT), and 15 vascular demented (VD) patients, 19 control (C) subjects, and 11 relatives (F) of one DAT patient. A significant association was found between the variables of the antioxidant system, measured in blood samples, and the neurological pathologies VD and DAT: Kruskal-Wallis test; p = 0.0006 (p = 0.014 when the analysis did not include SOD). This demonstrated that VD and DAT diseases are accompanied by oxidative disorders. The VD and DAT diseases are differentially distinguishable by changes in blood profiles. A graphical method for classification, the Principal Components Analysis (PCA), distinguished between demented and non-demented subjects on the basis of their laboratory variables. A numerical method, Discriminant Functions (DF), constructed to separate the clinical groups on the basis of the same variables, obtained relatively high percentages of success: 92% of demented were detected against healthy subjects; of the latter 82% have been correctly identified as non-demented. Discrimination between VD and DAT patients was achieved for 100% of VD and 86% of DAT patients. DF were similarly successful in detecting the healthy condition of DAT relatives. Possible different mechanisms involved in H2O2 elimination in DAT and VD patients are proposed, where CAT is the responsible enzyme of this reaction in DAT patients, while in VD this function would be achieved mainly through the action of GLU. It seems that SOD levels are stable, at least, within one year. Variations appear to be linked with clinical changes.

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.

Aqueous Extracts of Lippia turbinata and Aloysia citriodora (Verbenaceae): Assessment of Antioxidant Capacity and DNA damage

The aim of the present work was to make a contribution to the knowledge of aqueous extracts of Lippia turbinata and Aloysia citriodora (Verbenaceae; infusion and decoction) in relation with the establishment of its antioxidant activity and lack of DNA damage, for its potential use in therapeutics. The cytogenotoxic profile was evaluated through genotoxic biomarkers such as mitotic index, cellular proliferation kinetics, sister chromatid exchanges, single-cell gel electrophoresis assay, and micronucleus test in human peripheral blood lymphocyte cultures. No statistical differences were found (P > .05) between control and exposed cultures, even between both aqueous extracts. The total antioxidant capacity was shown to be higher in the decoction than in the infusion and both aqueous extracts protected against protein carbonylation and lipid peroxidation, the decoction being more efficient than the infusion (P < .005). These results suggest the safe use of these medicinal plants as chemoecologic agents in therapeutics.

Evaluation of Oxidative Stress Markers in Human Conjunctival Epithelial Cells Exposed to Diesel Exhaust Particles (DEP).

PURPOSE The aim of this study was to evaluate oxidative stress markers in human conjunctival epithelial cells (IOBA-NHC) exposed to diesel exhaust particles (DEP). METHODS Reactive oxygen (ROS) and nitrogen (RNS) species production; hydrogen peroxide (H2O2) levels; protein oxidation; antioxidant enzymes activities (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPx], glutathione S-transferase [GST], and glutathione reductase [GR]); total reactive antioxidant potential (TRAP); reduced (GSH) and oxidized glutathione (GSSG) were evaluated. Transmission electron microscopy was performed to evaluate DEP uptake. RESULTS Diesel exhaust particles were entrapped by membrane protrusions developed by IOBA-NHC. Cells exposed to DEP 50 and 100 μg/mL showed a significant increase in ROS, RNS, H2O2 levels, SOD, GPx, and GST compared with the control group. A significant decay in GR was observed in both groups, meanwhile CAT levels remained unchanged. The group exposed to DEP 100 μg/mL displayed a significant increase in protein oxidation. In both groups, TRAP was significantly reduced as well as the GSH/GSSG ratio. CONCLUSIONS The decrease in nonenzymatic antioxidants and the compensatory increase of SOD, GPX, and GST activities are consequence of the increase in ROS and RNS production due to DEP exposure and its accumulation inside the cells. The decay in GR activity leads to the decrease in GSH/GSSG recycling. These results suggest that oxidative stress could play an important role in the development of DEP effects on human conjunctival epithelial cells.

Oxidative stress in rodent closed duodenal loop pancreatitis

SummaryConclusionsProduction of excited oxygen species is earlier in the liver than in the pancreas and could contribute to damage in a reflux model. Treatment with SOD could attenuate 59% light emission in pancreas, but did not modify serum enzyme levels or pancreatic edema, resulting as an insufficient isolated therapy. Unexpectedly, it was found an increased plasma antioxidant capacity that was related to total bilirubin levels, and declined at late stages probably denoting other circulating antioxidant consumption.BackgroundOxidative stress has been shown to play a role in different models of acute pancreatitis, although it has not been studied in the severe necrohemorrhagic model produced by closed duodenal loop pancreatitis.MethodsWe studied Sprague Dawley female rats in two groups: a closed duodenal loop pancreatitis group and a control, sham-operated group. In order to evidence the oxygen excited species production,in situ spontaneous chemiluminescence from living and naturally perfused pancreas and liver was measured at 0, 0.5, 1.5, 3, 6, 12, and 24 h after the duodenal ligature. Blood pancreatic amylase and aminotransferases levels were determined as expression of tissue damage in pancreas and liver. At the same time, plasma antioxidant capacity was measured by the peroxyl radical trapping capability of plasma samples compared to that of Trolox (synthetic analog of vitamin E), and results are expressed as Trolox equivalence. Bovine superoxide dismutase (SOD) was administered to attenuate oxygen free radicals activity at the beginning of the peroxidation chain and also as a therapeutic tool.ResultsThe experimental procedure induced a severe pancreatitis, as evidenced by pancreatic enzymes that rose markedly in the early hours of disease and remained heightened throughout the experiment. The results show early light emission from the liver at 3 h and peak levels at 12 h, whereas in the pancreas, luminescence increased at 6 h and doubled later at 12 h, both returning to control levels at 24 h.

Brain antioxidant status in a high pressure-induced rat model of glaucoma.

Purpose:  The goal of the present study is to establish the antioxidant status in the brain of a high pressure–induced rat model.

Evidence of Oxidative Stress Damage in Glaucoma

Oxidative stress has been implicated as a risk factor at several levels in the pathophysiology of glaucoma (Ferreira et al., 2004, 2009, 2010) as well as neurodegenerative diseases (Famulari et al., 1996); growing evidence supports the role of oxidative stress in glaucomatous neurodegeneration (Tezel, 2006). Reactive oxygen species are involved in signalling pathways during retinal ganglion cells death by acting as second messengers and/or modulating protein functions (Neufeld et al., 1999). Evidence of oxidative and nitrative processes was found in glaucoma in terms of activity of antioxidant enzymes, levels of low-molecular weight antioxidants and markers of lipid peroxidation (Aslan et al., 2008). Moreover it has been reported that nitric oxide may be an important mediator in retinal ganglion cells death in glaucoma (Neufeld et al., 1997). In the glaucoma eye, an altered oxidant/antioxidant balance may result in a number of molecular changes that contribute to the development of this ocular disease. Glaucoma is a disease characterized by a specific pattern of optic nerve head and visual field damage in which if it is not controlled may lead to blindness. Although it has been traditionally associated with high intraocular pressure (IOP), glaucoma is now considered as a multifactorial disease. In this context, IOP is the most important known risk factor for the development of glaucomatous optic nerve damage. Even in normal-pressure glaucoma, reducing IOP can be beneficial in terms of halting visual field damage progression. However, lowering IOP may not be enough in every case, since different mechanisms that may or may not depend on the IOP level could contribute to this damage. Proposed mechanisms include ischemia (Lander, 1982), obstruction of axoplasmic flow (Anderson & Hendrickson 1974) and deprivation of one or more trophic factors (Quigley et al., 1995), excitoxicity (Vorwerk et al., 1997) and oxidative stress damage (Ferreira et al., 2004, 2009, 2010). IOP is not elevated in all the eyes that exhibit characteristics of glaucomatous neurodegeneration but experimental elevation of IOP induces oxidative stress in the retina. Aqueous humor is known to contain several active oxidative agents such as hydrogen peroxide and superoxide anion. Low molecular weight antioxidants, such as glutathione (GSH), and ascorbate, together with molecules with free radicals scavenging properties like cysteine and tyrosine, have been identified in the aqueous. Ascorbate is present at high concentrations in it (1-2 mM) (Richer & Rose, 1998) and antioxidant enzymes such as

Diesel exhaust particles (DEP) induce an early redox imbalance followed by an IL-6 mediated inflammatory response on human conjunctival epithelial cells

Abstract The aim of this study was to evaluate the time course of oxidative stress markers and inflammatory mediators in human conjunctival epithelial cells (IOBA‐NHC) exposed to diesel exhaust particles (DEP) for 1, 3, and 24 h. Reactive oxygen species (ROS) production, lipid and protein oxidation, Nrf2 pathway activation, enzymatic antioxidants, glutathione (GSH) levels and synthesis, as well as cytokine release and cell proliferation were analyzed. Cells exposed to DEP showed an increase in ROS at all time points. The induction of NADPH oxidase‐4 appeared later than mitochondrial superoxide anion production, when the cell also underwent a proinflammatory response mediated by IL‐6. DEP exposure triggered the activation of Nrf2 in IOBA‐NHC, as a strategy for increasing cellular antioxidant capacity. Antioxidant enzyme activities were significantly increased at early stages except for glutathione reductase (GR) that showed a significant decrease after a 3‐h‐incubation. GSH levels were found increased after 1 and 3 h of incubation with DEP, despite the increase in its consumption by the antioxidant enzymes as it works as a cofactor. GSH recycling and the de novo synthesis were responsible for the maintenance of its content at these time points, respectively. After 24 h, the decrease in GR and glutamate cysteine ligase as wells as the enhanced activity of glutathione peroxidase and glutathione S‐transferase produced a depletion in the GSH pool. Lipid‐peroxidation was found increased in cells exposed to DEP after 1‐h‐incubation, whereas protein oxidation was found increased in cells exposed to DEP after a 3‐h‐incubation that persisted after a longer exposure. Furthermore, DEP lead IOBA‐NHC cells to hyperplasia after 1 and 3 h of incubation, but a decrease in cell proliferation was found after longer exposure. ROS production seems to be an earlier event triggered by DEP on IOBA‐NHC, comparing to the proinflammatory response mediated by IL‐6. Despite the fact that under short periods of exposure to DEP lipids and then proteins are targets of oxidative damage, the viability of the cells is not affected at early stages, since cell hyperplasia was detected as compensatory mechanism. Although after 24 h Nrf2 pathway is still enhanced, the epithelial cell capacity to maintain redox balance is exceeded. The antioxidant enzymes activation and the depleted GSH pool are not capable of counteracting the increased ROS production, leading to oxidative damage. HighlightsROS production is an earlier event triggered by DEP on human conjunctival epithelial cells followed by IL‐6 release.Mitochondria and then NADPH oxidase‐4 have been identified as two sources of ROS production.Nrf2 pathway is activated by DEP, attempting to enhance the cellular antioxidant capacity since early stages.At early time points, GSH pool and antioxidant enzymes are increased, as an adaptive response to oxidative environment.After 24 h, depleted GSH pool and antioxidant enzymes are not capable of counteracting the increased ROS production.