2.14. Laboratory Analysis
OXIDATIVE STRESS
Nitrate and Nitrite: The ozone-based chemiluminescence method was used to measure plasma and salivary nitrate and nitrite concentrations, and urinary nitrate concentrations using the Sievers gas-phase chemiluminescence nitric oxide analyser (NOA 280i, Analytix), which has been described elsewhere [Urinary 8-isoprostane: An ELISA Kit was used to analyse the amount of 8-isoprostane in the urine samples as a measure of oxidative stress (abcam UK, Cambridge, UK). The kit was a competitive immuno-enzymatic assay for quantitatively measuring 8-isoprostane in biological samples. Urine samples were diluted 4-fold prior to analysis. The assay’s sensitivity and precision (CV%) were 1 pg/mL and 1.75%, respectively.