 Blood samples will be obtained on Days 1,2, 5, 10 and 14 of the ICU stay. Peripheral whole blood will be sampled from an indwelling arterial line and plasma will be separated for analysis of plasma zinc using atomic absorption spectroscopy. Plasma interleukin-6 IL-6 and pentraxin-3 PTX3 will be measured using enzyme immunoassay and total antioxidant capacity and lipid hydroperoxides will be measured colourimetrically 17. Peripheral blood mononuclear cells MNC will be separated using single density gradient centrifugation, RNA extracted and metallothionein mRNA measured using qPCR 21. Nuclear extracts of MNC will be prepared and nuclear factor kappa B NFκBactivation measured using an enzyme immunoassay 17. 