Mara da Silveira Benfato

Lipid peroxidation in hippocampus early and late after status epilepticus induced by pilocarpine or kainic acid in Wistar rats

Oxidative stress has been implicated in a variety of acute and chronic neurologic conditions, including epilepsy. Both the kainic acid and pilocarpine are useful models of temporal lobe epilepsy in rodents. As an index of lipid peroxidation the level thiobarbituric acid reactive substances (TBARS) was measured after the status epileticus induced by pilocarpine or kainic acid. In hippocampus there was a slight enhancement in the TBARS levels measured 12-14 h after the end of status epileticus induced by pilocarpine and kainic acid. The TBARS levels in pilocarpine treated animals was significantly decreased late after status epileticus and in kainic acid model the TBARS returned to basal levels. These results indicating a putative role of reactive oxygen species in kainic acid and pilocarpine induced epilepsy.

Espécies reativas de oxigênio e de nitrogênio, antioxidantes e marcadores de dano oxidativo em sangue humano: principais métodos analíticos para sua determinação

We review here the chemistry of reactive oxygen and nitrogen species, their biological sources and targets; particularly, biomolecules implicated in the redox balance of the human blood, and appraise the analytical methods available for their detection and quantification. Those biomolecules are represented by the enzymatic antioxidant defense machinery, whereas coadjutant reducing protection is provided by several low molecular weight molecules. Biomolecules can be injured by RONS yielding a large repertoire of oxidized products, some of which can be taken as biomarkers of oxidative damage. Their reliable determination is of utmost interest for their potentiality in diagnosis, prevention and treatment of maladies.

Retinol supplementation induces oxidative stress and modulates antioxidant enzyme activities in rat sertoli cells.

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol caused cellular oxidative stress and modulated superoxide dismutase, catalase and glutathione peroxidase activities. Retinol (7 μM) significantly increased TBARS, conjugated dienes, and hydroperoxide-initiated chemiluminescence in cultured Sertoli cells. In response to retinol treatment superoxide dismutase, catalase and glutathione peroxidase activities increased. TBARS content and catalase activities were decreased by a free radical scavenger. These findings suggest that retinol may induce oxidative stress and modulate antioxidant enzyme activities in Sertoli cells.

Retinol supplementation induces DNA damage and modulates iron turnover in rat Sertoli cells.

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol caused cellular DNA damage probably involving cellular iron accumulation. Retinol (7μM) significantly induced DNA single strands breaks, DNA fragmentation and production of 8-oxo-7, 8-dihydro-2′-deoxyguanosine in cultured Sertoli cells. In contrast, lower doses seemed not to induce single-strands break in this experimental model. The breaks in DNA were inhibited by an iron scavenger; and 7μM retinol treatment modulated iron turnover leading to iron accumulation, suggesting that iron ions were required for the retinol cellular effects. These findings suggest that retinol-induced DNA damage was associated with the modulation of iron turnover, and these characteristics could be responsible for the increased incidence of lung cancer associated with retinoids supplementation.

Stress protein response and catalase activity in freshwater planarian Dugesia (Girardia) schubarti exposed to copper.

The hsp60 expression pattern and catalase activity in the freshwater planarian Dugesia schubarti exposed to copper under laboratory conditions were investigated. In the hsp60 induction experiments, planarians were exposed to a range of copper concentrations (0-960 microgCu/L) for 4 or 24h, to concentrations of 50 or 100 microgCu/L for 2, 4, 8, and 24h at 19 degrees C, and to heat shock at 27 degrees C for 24h. The concentrations of hsp60 in whole-body homogenates were determined immunochemically by Western blotting. Stress protein induction was detected only after 24h treatment at 27 degrees C. The tissue concentration of hsp60 remained unaltered in Cu-exposed planarians under the experimental conditions used. Catalase activity was significantly induced at concentrations of 40, 80, and 160 microgCu/L after 24h exposure. Our results suggest that catalase levels in planarians could represent biomarkers of interest for the estimation of copper effects in freshwater ecosystems.

Blood Antioxidant Parameters in Sickle Cell Anemia Patients in Steady State

Sickle cell anemia (SCA) is a hereditary disorder with higher potential for oxidative damage due to chronic redox imbalance in red cells. We measured antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). We also determined oxidative damage of proteins in hemolysate of red blood cells (RBCs) and plasma (carbonyl assay). We characterized the membrane damage in terms of lipid peroxidation by accumulation of malonaldehyde (MDA) by HPLC in 30 healthy controls and 20 SCA patients in steady-state condition. Twenty (9 males/11 females) adult SCA patients and 30 healthy controls were studied. All patients and control subjects had antioxidant (CAT, GPx, SOD, carbonyl and MDA) and hematological parameters done. Our data show that SCA patients had significant higher GPx and SOD activities than healthy controls. Carbonyl assay was noted in plasma but not in hemolysate. An enhanced production of MDA was observed in the serum of SCA patients. Our data support the growing evidence that patients with SCA are subjected to chronic oxidative stress and are able to oxidative damage in biological macromolecules such as proteins and lipids.

Antioxidant enzymes activities and protein damage in rat brain of both sexes

The theory of free radicals and accumulation of damages suggests that the reactive species of oxygen play a key role in the context of aging. Thus, for the best understanding of the aging process, the study of antioxidant defenses has to be considered as part of gerontology. The present work evaluated the enzymatic activity of the enzymes catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), and measured the amount of oxidative damage in proteins (carbonyl groups) in brains of rats of both sexes in the ages of 3-, 6-, 12- and 20-months. The results suggest that the patterns of activity and accumulation of damages can be sex-specific and related to the cycle of reproductive life of the organism.

Alpha-lipoic acid modifies oxidative stress parameters in sickle cell trait subjects and sickle cell patients

BACKGROUND & AIMS Oxidative stress plays a crucial role in the sickle cell disease. Alpha-lipoic acid (ALA) is a potent antioxidant that is employed in the treatment of several diseases. The objective of this study was to test the ALA effect in the sickle cell disease (SCD) treatment. METHODS Sixty subjects were selected and divided into groups according to the hemoglobin profile: AA (normal), AS (SCD trait subject) and SS (SCD patient). Patients were randomized into a placebo-controlled trial and treated with either ALA (200 mg) or vehicle. Blood samples were collected before supplementation and after 3 months of treatment. Catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) activities and total antioxidant status (TAS) were evaluated as measure of antioxidant defense. Lipid and protein damages were quantified by malondialdehyde (MDA) and carbonyl assays, respectively. RESULTS CAT activity significantly increased in the AS group after ALA treatment and GPx activity presented significant decrease in all groups. SOD activity was not different in any group. Data on MDA and carbonyl levels showed significant reduction in the AA group with ALA treatment. TAS decreased in the same group. CONCLUSION ALA treatment protected AA individuals from oxidative damage to lipids and proteins. In SCD subjects, the dose applied was not effective to prevent the oxidative damage.

Retinol-induced elevation of ornithine decarboxylase activity in cultured rat Sertoli cells is attenuated by free radical scavenger and by iron chelator

We investigated retinol effects in ornithine decarboxylase activity in Sertoli cells. We also tested the hypothesis that free radical scavengers and iron chelators may attenuate the effect of retinol. Sertoli cells isolated from 15-day-old Wistar rats were previously cultured for 48 h and then treated with retinol by 24 h with or without mannitol (1 mM) or 1,10 phenanthroline (100 μM). We measured ornithine decarboxylase and catalase activities and malondialdehyde concentrations in response to retinol treatment. In response to 7 μM retinol treatment ornithine decarboxylase activity increased 30%. Retinol-induced ornithine decarboxylase activity was significantly decreased by addition of free radical scavenger (mannitol) or iron chelator (1,10 phenanthroline). In addition the same effect was observed in catalase increased activity and in malondialdehyde concentrations. These results suggest that retinol treatment induced ornithine decarboxylase and catalase activity and increased malondialdehyde concentration. These effects appear to be mediate by ROS.

Carbonyl groups: Bridging the gap between sleep disordered breathing and coronary artery disease.

Abstract Sleep disordered breathing (SDB) is related to coronary artery disease (CAD), but the mechanisms are uncertain. SDB is characterized by periods of intermittent hypoxia and free radical formation. This study tested the hypothesis that carbonylation can be the link between SDB and CAD. It included 14 cases with CAD and 33 controls with <50% coronary narrowing. CAD cases have higher erythrocyte carbonyl levels than controls (p = 0.012). Positive correlation was observed between apnea-hypopnea index (AHI) and erythrocyte carbonyl concentration (ρ = 0.310; p = 0.027). To predict CAD, including as regressors: AHI, erythrocyte carbonyl, gender, age and body mass index, the significant variables in the Poisson multiple regression model were AHI and erythrocytes carbonyl. An increase of 1 pmol/gHb in erythrocyte carbonyl levels increases by 1.8% the risk of CAD and one unit of AHI increases by 3.8% the risk of CAD. The present findings represent the first evidence in humans that SDB may cause CAD through protein carbonylation.