VIVA

Question 1

what is oxidative stress

Answer 1

imbalance in ROS production and removal, or inability to repair damage

Question 2

how do ROS cause damage

Answer 2

base damage (superoxide, hydroxyl radical, hydrogen peroxide) and DNA strand break and cellular signalling damage

Question 3

diseases linked with oxidative stress

Answer 3

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)

Question 4

how are ROS good

Answer 4

signalling, used by the immune system to track and kill pathogens, short term oxidative stress prevents aging (mitohormesis)

Question 5

main target for ROS

Answer 5

polyunsaturated fatty acids (arachidonic and linoleic acid)

Question 6

how do ROS come about

Answer 6

leakage of activated oxygen from mitochondria during oxidative phosphorylation

Question 7

what is oxidative phosphorylation

Answer 7

metabolic pathway in which cells oxidise nutrients to release energy to form ATP

Question 8

where does oxidative phosphorylation take place

Answer 8

mitochondria in eukaryotes

Question 9

why is oxidative phosphorylation so successful

Answer 9

uses the double bond of O2 which has more energy than the double bond between CO2 or in organic molecules

Question 10

what happens during oxidative phosphorylation (at the electron scale)

Answer 10

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)

Question 11

what is oxidisation (effect on oxidation state)

Answer 11

loss of electron (increase in oxidation state)

Question 12

what is reduction (effect on oxidation state)

Answer 12

gain of electron (decrease in oxidation state)

Question 13

METHOD how is free iron concentration in plasma measured

Answer 13

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

Question 14

METHOD how is free iron concentration in plasma measured

Answer 14

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

Question 15

METHOD how is nitrite content in plasma measured

Answer 15

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

Question 16

METHOD (STUDY DESIGN) how was this good?

Answer 16

cross sectional study, high compliance (no dropouts)??

Question 17

METHOD (STUDY DESIGN) how was it bad?

Answer 17

sample size

Question 18

STATS whats ANOVA

Answer 18

“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

Question 19

STATS whats tukey’s post hoc analysis

Answer 19

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

Question 20

STATS whats tukey’s post hoc analysis

Answer 20

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

Question 21

STATS what are the independent and dependant variables here?

Answer 21

training level (yes/no) and supplementation (yes/no) (independent) effects on exercise performance (dependant)

Question 22

STATS 6 conditions to use two way ANOVA

Answer 22

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

Question 23

what was the study outcome

Answer 23

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

Question 24

aim of the study

Answer 24

(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.

Question 25

what is L-arginine

Answer 25

semi-essential amino acid (essential in preterm infants, not later). Synthesised from glutamine via citrulline

Question 26

hypothesis used to determine aim

Answer 26

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