Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 143
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 143
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 209
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 994
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3134
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 574
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 488
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
Oxidative/nitrosative stress contributes to the etiology of the neurological disorders, including ischemic stroke and chronic neurodegeneration. Neurotoxic modifications mediated by reactive oxygen species (ROS) or reactive nitrogen species (RNS) are closely associated with the destruction of key macromolecules and inactivation of antioxidant enzymes, which compromises antioxidant defenses. Approaches to expel ROS/RNS and alleviate toxic oxidative/nitrosative stress in neurons have not completely been defined. Here, we aimed to evaluate the efficacy of various antioxidants that serve as the neuroprotectors under a toxic stress created by ROS plus nitric oxide (NO). Sublytic concentrations of hydrogen peroxide (H2O2) plus NO donor S-nitroso-N-acetyl-D, L-penicillamine (SNAP) enabled to induce a toxic oxidative/nitrosative stress through activating both p38 MAPK and p53 cascades, and cause DNA damage and protein tyrosine nitration in primary neuronal cultures. After comparing six antioxidants, including superoxide dimutase (SOD), catalase, 2,2,6,6-tetramethyl-1-piperidinoxyl (TEMPO), N-acetylcysteine, dimethylthiourea, and uric acid, TEMPO was the superior antioxidant that comprehensively and efficaciously decreased H2O2 plus SNAP-evoked activation of stress cascades of p38 MAPK and p53, production of NO, ROS, and peroxynitrite, double-strand breaks of DNA, and nitration of protein tyrosine residues. SOD increased the peroxynitrite formation and was unable to reduce the level of protein nitration. All antioxidants tested, except SOD, effectively reduced neuronal damage and DNA breakage caused by the toxic H2O2/SNAP combination. In conclusion, these results suggest that TEMPO ensures excellent ROS/RNS clearance and stress-signaling inhibition, thus effectively rescuing neurons from ROS/H2O2 plus NO/SNAP-induced insult. This study reveals a potential strategy for nitroxide antioxidants as a therapeutic agent against oxidative/nitrosative neurotoxicity.
Download full-text PDF |
Source |
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http://dx.doi.org/10.1016/j.niox.2016.02.001 | DOI Listing |
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