Search results for "STRESS"

Nitrate Reductase Activity of Mitochondrial Aldehyde Dehydrogenase (ALDH-2) as a Redox Sensor for Cardiovascular Oxidative Stress

2009

In 2002, mitochondrial aldehyde dehydrogenase (ALDH-2) was identified as an organic nitrate bioactivating enzyme. This so-called nitrate reductase activity denitrates nitroglycerin (glycerol trinitrate) to its 1,2-glycerol dinitrate metabolite and nitrite. This reaction relies on reduced thiols at the active site of the enzyme and on the presence of reduced dithiols as the electron source. During bioconversion of nitroglycerin, and also in the presence of reactive oxygen and nitrogen species, the active site thiols of ALDH-2 are oxidized and the enzyme looses its activity. We, therefore, speculated that ALDH-2 activity could be a useful marker for cardiovascular oxidative stress. Indeed, th…

Oxidative stress and enzymatic antioxidant mechanisms in essential hypertension

2001

Molecular response to TBT stress in marine sponge Suberites domuncula: proteolytical cleavage and phosphorylation of KRS_SD protein kinase

2003

Abstract Marine sponges as sessile filter feeders are inevitably under a constant influence of changes in their environment. Mediation of extracellular signals and regulation of cellular response to environmental stress is a key function of cellular protein kinases. Expression, proteolytical cleavage and phosphorylation of stress-responsive KRS_SD protein kinase, in control and tributyl-tin (TBT) treated sponges were investigated. In control sponge, two KRS_SD proteins were expressed: KRS_SD1 (54 kDa) corresponding to KRS_SD calculated molecular weight, and KRS_SD2 (50 kDa). Exposure of sponges to TBT resulted in alteration of KRS_SD1 and KRS_SD2 expression levels and their phosphorylation …

Age-related changes in antioxidant status and oxidative damage to lipids and dna in mitochondria of rat liver

2005

To investigate the correlation between oxidative stress and mitochondrial damage with aging, antioxidant system, levels of oxidative DNA damage and as an index of the loss of plasma membrane integrity lipid peroxidation and membrane potential were studied. Results showed that the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase significantly decreased during aging, however glutathione peroxidase (GSH-PX) increased in the aged mitochondria and glutathione (GSH) did not change during aging. No statistical difference was observed in the lipid peroxidation of mitochondria between young and old animals. The level of oxidative DNA damage (measured as 8oxo-dG) tended to in…

Concentration-Dependent Antioxidant/Pro-Oxidant Activity of Ascorbic Acid in Chickens

2012

С vitamīns piedalās daudzos vielmaiņas procesos. Tas stiprina organisma imūnsistēmu, piedalās bioloģiskās oksidēšanās un reducēšanās procesos. Askorbīnskābe un dehidroaskorbīnskābe veido redoks sistēmu un ir saistītas ar glutationa sistēmu. Dažādu stresu ietekmē askorbīnskābes koncentrācija audos samazinās. Tādēļ barību vajag bagātināt ar šo vitamīnu. Darba mērķis bija pētīt dažādus oksidatīvā stresa biomarķierus cāļu organismā, kadmija akumulāciju orgānos, imūnsistēmas aktivitāti un nieru funkcijas izmaiņas askorbīnskābes ietekmē atkarībā no tās koncentrācijas barībā. Eksperimentos izmantojām vienu dienu vecus Lohmann Brown gailīšus, kurus sadalījām piecās analogās grupās. Cāļi saņēma komb…

Early reductive stress followed by a late onset oxidative stress in acute myocardial infarction

2018

Introduction The idea that the cells might suffer from reductive rather than oxidative stress and that such stress may be relevant in pathophysiology has gained momentum. Aim We aimed at studying markers of oxidative stress and damage as well as the expression of antioxidant enzymes in a swine model of acute myocardial infarction (AMI) followed by reperfusion. Results and Discussion We found an increase in the GSH to GSSG ratio, a decrease in protein glutathionylation and a decrease in p38 MAPK phosphorylation after 90 minutes of ischaemia in heart samples. It was accompanied by an increase in the expression of Thioredoxin (TrX) and Peroxiredoxin (PrX) and a decrease in the expression of Gl…

Mitochondrial Oxidative Stress in Diabetes

2014

Abstract Diabetes is a multifactorial disease associated with serious comorbidities. This condition has been related to oxidative stress and, as a consequence, to overproduction of reactive oxygen species (ROS), which are known to be produced by different sources in diabetes. Excessive production of ROS can be harmful, making antioxidant defenses of vital importance. Dietary antioxidants, such as vitamin E or vitamin C, polyphenols and flavonoids have been used to modulate the oxidative stress created in diabetes, producing contradictory results in clinical trials, perhaps as a consequence of the targets selected and/or the design of the studies in question. This chapter considers the proce…

Exercise as an antioxidant: it up-regulates important enzymes for cell adaptations to exercise

2006

Abstract Aims. – To assess the role of the reactive oxygen species (ROS) in cell signalling and in the regulation of gene expression. Methods. – Exercise causes oxidative stress only when exhaustive. Strenuous exercise causes oxidation of glutathione, release of cytosolic enzymes, and other signs of cell damage. We have tested this hypothesis by studying the effect of inhibition of ROS production by allopurinol (an inhibitor of xanthine oxidase, a free radical generating enzyme) on cell signalling pathways in marathon runners and in rats submitted to exhaustive exercise by running on a treadmill. Results. – Exercise caused an activation of NF-κB in lymphocytes from marathon runners which wa…

Nitroglycerin-Induced Endothelial Dysfunction and Tolerance Involve Adverse Phosphorylation and S -Glutathionylation of Endothelial Nitric Oxide Synt…

2011

Objective— Continuous administration of nitroglycerin (GTN) causes tolerance and endothelial dysfunction by inducing reactive oxygen species (ROS) production from various enzymatic sources, such as mitochondria, NADPH oxidase, and an uncoupled endothelial nitric oxide synthase (eNOS). In the present study, we tested the effects of type 1 angiotensin (AT 1 )-receptor blockade with telmisartan on GTN-induced endothelial dysfunction in particular on eNOS phosphorylation and S -glutathionylation sites and the eNOS cofactor synthesizing enzyme GTP–cyclohydrolase I. Methods and Results— Wistar rats were treated with telmisartan (2.7 or 8 mg/kg per day PO for 10 days) and with GTN (50 mg/kg per d…

Diabetic Retinopathy and Oxidative Stress

2014

Abstract Diabetic retinopathy (DR) is the leading cause of acquired blindness in working age adults worldwide. Biochemical changes in DR contribute to both the microscopic structural and functional changes in the retina. All these alterations result in macroscopic retinal damage that can be assessed by funduscopy. The overproduction of reactive oxygen species (ROS) in the mitochondria is considered a causal link between elevated glucose and biochemical abnormalities in the pathophysiology of DR. Moreover, oxidatively induced pathways also seem to provide positive feedback to ROS production, resulting in a vicious cycle. ROS can directly damage lipids, proteins and DNA, leading to cell death…