VIVA Flashcards
what is oxidative stress
imbalance in ROS production and removal, or inability to repair damage
how do ROS cause damage
base damage (superoxide, hydroxyl radical, hydrogen peroxide) and DNA strand break and cellular signalling damage
diseases linked with oxidative stress
cancer, atherosclerosis (endothelial damage), neurodegenerative diseases (ALS, MS, alzeihmers), stroke/MI (ischaemic cascade due to oxygen reperfusion injury following hypoxia), gastric cancer (ROS production in the stomach)
how are ROS good
signalling, used by the immune system to track and kill pathogens, short term oxidative stress prevents aging (mitohormesis)
main target for ROS
polyunsaturated fatty acids (arachidonic and linoleic acid)
how do ROS come about
leakage of activated oxygen from mitochondria during oxidative phosphorylation
what is oxidative phosphorylation
metabolic pathway in which cells oxidise nutrients to release energy to form ATP
where does oxidative phosphorylation take place
mitochondria in eukaryotes
why is oxidative phosphorylation so successful
uses the double bond of O2 which has more energy than the double bond between CO2 or in organic molecules
what happens during oxidative phosphorylation (at the electron scale)
electrons are transferred from donors (NADH) to acceptors (like oxygen) in redox reactions, catalysed by a series of 5 main complexes. The whole point is to transfer protons across the inner membrane to create a pH gradient. As they flow back, with their gradient, they go through ATP synthase which turns ADP into ATP (phosphorylation)
what is oxidisation (effect on oxidation state)
loss of electron (increase in oxidation state)
what is reduction (effect on oxidation state)
gain of electron (decrease in oxidation state)
METHOD how is free iron concentration in plasma measured
Goodwin and murphy method: iron released from transferrin in acid, reduced to ferrous state by hydroxylamine, reacts with Ferrozine to produce purple complex, spectrophotometry at 560nm, 37°C
METHOD how is free iron concentration in plasma measured
Goodwin and murphy method: iron released from transferrin in acid, reduced to ferrous state by hydroxylamine, reacts with Ferrozine to produce purple complex, spectrophotometry at 560nm, 37°C
METHOD how is nitrite content in plasma measured
Ding et al method: acidic conditions, nitrite reacts with sulphanilamide to form compound. Reacts with NED to form red compound. Absorbance reading at 550nm, make sodium nitrate curve to see what the relation between absorbance at 550nm and concentration is
METHOD (STUDY DESIGN) how was this good?
cross sectional study, high compliance (no dropouts)??
METHOD (STUDY DESIGN) how was it bad?
sample size
STATS whats ANOVA
“analysis of variance”, testing a hypothesis when dealing with 2 or more groups, two-way ANOVA because they are testing two independent variables on 2 or more groups
STATS whats tukey’s post hoc analysis
provide more insight and comparison after ANOVA
‘post hoc’ means after a multivariate test, go and see if specific groups are similar or different. Tukey’s test compares the means of all treatment to the mean of every other treatment. Considered the best available method in cases when confidence intervals are desired or if sample sizes are unequal
STATS whats tukey’s post hoc analysis
provide more insight and comparison after ANOVA
‘post hoc’ means after a multivariate test, go and see if specific groups are similar or different. Tukey’s test compares the means of all treatment to the mean of every other treatment. Considered the best available method in cases when confidence intervals are desired or if sample sizes are unequal
STATS what are the independent and dependant variables here?
training level (yes/no) and supplementation (yes/no) (independent) effects on exercise performance (dependant)
STATS 6 conditions to use two way ANOVA
dependant variable is continuous,
independant variable consist of 2 categorical independant groups
independance of observation (participants in each group, no participants in more than one group)
dependant variable is more or less normally distributed among the groups of the independent variables
homogeneity of variance for each combination of the groups of the two independent variables
what was the study outcome
training had positive impact on performance and antioxidant system
larginie had positive impact on performance in trained and untrained
in untrained, larginine increase in performance exposed to oxidative damage because mice lacked the positive impact on antioxidant system
best way to improve exercise was larginine AND training
aim of the study
(impact of training, supplementation, both on 3 moderate intensity training)
impact of training, supplementation, both on exhaustion time after maximal exercise performance.
(impact of training, supplementation, both on antioxidant system)
(impact of training, supplementation, both on oxidative stress)
ACTUAL AIM: evaluate the effects of l-arginine supplementation in the performance and oxidative status in untrained and aerobically trained rats submitted to an intense exercise session.
what is L-arginine
semi-essential amino acid (essential in preterm infants, not later). Synthesised from glutamine via citrulline
hypothesis used to determine aim
In this work, we hypothesize that l-arginine supplementation is capable to modulate skeletal muscle redox status, leading to a decrease in oxidative stress and increase exercise performance in aerobically trained rats
