Search results for " STRESS"
showing 10 items of 3936 documents
Exercise as a Model to Study Oxidative Stress
2011
Physical exercise generates free radicals. The major source of radicals in exercise appears to be extracellular. Our experiments show that xanthine oxidase is a key player in the generation of superoxide during exercise. Mitochondrial contribution appears to be less important: during high oxygen utilization by mitochondria in state 3, the proportion of oxygen that is converted to superoxide is on an order of magnitude lower than in resting, state 4 conditions. Exercise-induced radicals constitute a double-edged sword: high intensity exercise causes the generation of relatively high concentrations of radicals that cause oxidative stress and eventually damage. On the other hand, low intensit…
Magnesium and Alzheimer’s Disease
2015
Environmental factors, including nutrition and metal elements, are implicated in the pathophysiology of Alzheimer’s disease (AD). Several in vitro and in vivo data indicate a role for magnesium (Mg) in many biological and clinical aspects of AD. Mg deficiency, aside from having a negative impact on the energy production pathways required by the mitochondria to generate adenosine triphosphate, also affects many biochemical mechanisms vital for neuronal properties and synaptic plasticity, including the response of N-methyl- d -aspartate receptors to excitatory amino acids, stability, and viscosity of the cell membrane. Mg also has an action as a mild calcium antagonist, and as an antioxidant …
Diabetes, oxidative stress and therapeutic strategies.
2014
Abstract Background Diabetes has emerged as a major threat to health worldwide. Scope of Review The exact mechanisms underlying the disease are unknown; however, there is growing evidence that excess generation of reactive oxygen species (ROS), largely due to hyperglycemia, causes oxidative stress in a variety of tissues. Oxidative stress results from either an increase in free radical production, or a decrease in endogenous antioxidant defenses, or both. ROS and reactive nitrogen species (RNS) are products of cellular metabolism and are well recognized for their dual role as both deleterious and beneficial species. In type 2 diabetic patients, oxidative stress is closely associated with ch…
Diabetes mellitus: oxidative stress and wine.
2003
This review focuses on the link between diabetes mellitus and oxidative stress and, in particular, on the role that moderate wine consumption may play in preventing diabetic complications and the onset of diabetes. With this aim, a search of PubMed was carried out for literature published up to March 2003. In diabetes mellitus, oxidative stress results both from exposure to hyperglycaemia through glycoxidation and sorbitol system activation, and from functional limitation of the hexose monophosphate shunt, leading to a decrease in glutathione synthesis. Oxidative stress alters the plasma lipoprotein profile (particularly low-density lipoproteins), the coagulative parameters (with an increas…
Oxidative stress and endothelial dysfunction: therapeutic implications.
2011
In a previous issue of Annals of Medicine, we presented evidence in support of the concept that an abnormally increased production of reactive oxygen species plays a central role in the genesis and progression of cardiovascular disease. While a number of preclinical lines of evidence support this concept, and despite the results of many studies suggesting a beneficial impact of antioxidant drugs on endothelial function, large clinical trials have failed to demonstrate a benefit of antioxidants on cardiovascular outcomes. Studies exploring the possibility that classical antioxidants such as vitamin C, vitamin E, selenium, or folic acid may improve the prognosis of patients with cardiac disea…
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…