Search results for "STRESS"
showing 10 items of 6278 documents
The Activation Pattern of the Antioxidant Enzymes in the Right Ventricle of Rat in Response to Pressure Overload is of Heart Failure Type
2003
In the left ventricle subjected to pressure overload activity, the antioxidant enzymes increased at the hyperfunctional stage. During the transition to heart failure, these enzymes are down-regulated, oxidative stress increases, and apoptosis progresses. Maladaptative activation of the antioxidant enzymes at an early stage may contribute to the intrinsic vulnerability of right ventricle to pressure overload. The authors studied changes in expression and activity of the enzymes manganese and copper-zinc superoxide dismutases, glutathione peroxidase, and catalase in the right ventricle of rat following induction of pulmonary hypertension by injection of monocrotaline. Increase in the manganes…
Janus-faced role of endothelial NO synthase in vascular disease: uncoupling of oxygen reduction from NO synthesis and its pharmacological reversal
2006
Endothelial NO synthase (eNOS) is the predominant enzyme responsible for vascular NO synthesis. A functional eNOS transfers electrons from NADPH to its heme center, where L-arginine is oxidized to L-citrulline and NO. Common conditions predisposing to atherosclerosis, such as hypertension, hypercholesterolemia, diabetes mellitus and smoking, are associated with enhanced production of reactive oxygen species (ROS) and reduced amounts of bioactive NO in the vessel wall. NADPH oxidases represent major sources of ROS in cardiovascular pathophysiology. NADPH oxidase-derived superoxide avidly interacts with eNOS-derived NO to form peroxynitrite (ONOO(-)), which oxidizes the essential NOS cofactor…
Pentaerithrityl tetranitrate improves angiotensin II induced vascular dysfunction via induction of heme oxygenase-1
2010
The organic nitrate pentaerythritol tetranitrate is devoid of nitrate tolerance, which has been attributed to the induction of the antioxidant enzyme heme oxygenase (HO)-1. With the present study, we tested whether chronic treatment with pentaerythritol tetranitrate can improve angiotensin II–induced vascular oxidative stress and dysfunction. In contrast to isosorbide-5 mononitrate (75 mg/kg per day for 7 days), treatment with pentaerythritol tetranitrate (15 mg/kg per day for 7 days) improved the impaired endothelial and smooth muscle function and normalized vascular and cardiac reactive oxygen species production (mitochondria, NADPH oxidase activity, and uncoupled endothelial NO synthase)…
Vitamin E Paradox in Alzheimer's Disease: It Does Not Prevent Loss of Cognition and May Even Be Detrimental
2009
There is controversy as to whether vitamin E is beneficial in Alzheimer's disease (AD). In this study, we tested if vitamin E prevents oxidative stress and loss of cognition in AD. Fifty-seven AD patients were recruited and divided in two groups: placebo or treated with 800 IU of vitamin E per day for six months. Of these 57 patients, only 33 finished the study. We measured blood oxidized glutathione (GSSG) and used the following cognitive tests: Mini-Mental State Examination, Blessed-Dementia Scale, and Clock Drawing Test. Of those patients treated with vitamin E, we found two groups. In the first group, "respondents" to vitamin E, GSSG levels were lower after the treatment and scores on t…
Prevention of apoptosis by deferoxamine during 4 hours of cold cardioplegia and reperfusion: in vitro study of isolated working rat heart model.
2002
INTRODUCTION: Heart transplantation is often accompanied by multiple functional alterations, especially in reperfusion period. These are probably related to the reactive oxygen species (ROS) formation catalyzed by transition metals such as iron and copper, and thus the preservation time of the donor hearts is limited. Metabolic protection of the heart grafts is a permanent objective of numerous experiments. Recently, an iron chelator deferoxamine (DFX) was proposed as antioxidant agent for storage solutions in heart grafts. Oxidative stress is also known to mediate the apoptotic cell death in different tissues during ischemia-reperfusion. METHODS: The aim of this study was to evaluate a pos…
Effect of a Diet Supplemented with alpha-Tocopherol and beta-Carotene on ATP and Antioxidant Levels after Hepatic Ischemia-Reperfusion.
2008
Ischemia-reperfusion injury associated with liver transplantation remains a serious complication in clinical practice. In the present study the effect of intake of alpha-tocopherol or beta-carotene to limit liver injury by oxidative stress in ischemia and reperfusion was explored. Wistar rats were fed with diets enriched with alpha-tocopherol (20 mg/day) or beta-carotene (3 mg/day) for 21 days. After 21 days, their livers were subjected to 15 and 30 min of ischemia and afterwards were reperfused for 60 min. The recovery of levels of ATP during reperfusion was better in the group of rats whose diets were supplemented with alpha-tocopherol or beta-carotene than in the group control. The suppl…
Evaluation of the Possible Contribution of Antioxidants Administration in Metabolic Syndrome
2011
The metabolic syndrome (MetS) is common, and its associated risk burdens of diabetes and cardiovascular disease (CVD) are a major public health problem. The hypothesis that main constituent parameters of the MetS share common pathophysiologic mechanisms provides a conceptual framework for the future research. Exercise and weight loss can prevent insulin resistance and reduce the risk of diseases associated with the MetS. Interrupting intracellular and extracellular reactive oxygen species (ROS) overproduction could also contribute to normalizing the activation of metabolic pathways leading to the onset of diabetes, endothelial dysfunction, and cardiovascular (CV) complications. On the other…
Redox modulation of mitochondriogenesis in exercise. Does antioxidant supplementation blunt the benefits of exercise training?
2015
Physical exercise increases the cellular production of reactive oxygen species (ROS) in muscle, liver, and other organs. This is unlikely due to increased mitochondrial production but rather to extramitochondrial sources such as NADPH oxidase or xanthine oxidase. We have reported a xanthine oxidase-mediated increase in ROS production in many experimental models from isolated cells to humans. Originally, ROS were considered as detrimental and thus as a likely cause of cell damage associated with exhaustion. In the past decade, evidence showing that ROS act as signals has been gathered and thus the idea that antioxidant supplementation in exercise is always recommendable has proved incorrect.…
Biochemical adaptations in middle-distance runners: an assessment of blood and anthropometric parameters
2014
In order to understand the mechanism underlying the physiological adaptation of purely aerobic workout, we investigated the effect of 2 months of training on nine males (17-22 year-old) middle distance running agonistic athletes. Blood sample was collected in the morning to analyze: hematological parameters, lipid profile, liver function enzymes [glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, gamma-glutamyl transferase (γ-GT)] and skeletal and myocardial markers of muscle damage [creatin kinase (CK) and creatin kinase MB (CK-MB)]. Endurance training, as it implies high oxygen consumption, should increase reactive oxygen species, but it has been shown that exercise lea…
Oxidative stress in vascular disease and its pharmacological prevention
2013
Cardiovascular risk factors lead to enhanced production of reactive oxygen species (ROS) generated by NADPH oxidase, xanthine oxidase (XO), the mitochondrial electron-transport chain (ETC), and dysfunctional endothelial nitric oxide synthase (eNOS). When the capacity of antioxidant defense systems [e.g., superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), heme oxygenase (HO), paraoxonase (PON)] is exceeded, this results in oxidative stress, which can promote atherogenesis. Therefore, pharmacological means to prevent oxidative stress are of major therapeutic interest. Some established drugs and novel therapeutic approaches can prevent oxidative stress and, presumably, vascula…