Blood samples were analysed for pro- and anti-inflammatory cytokines : tumour-necrosis factor ( TNF ) - alpha , soluble TNF receptors ( sTNF-R ) -1 and -2 , interleukin ( IL ) -1 beta , IL-1 receptor antagonist ( IL-1Ra ) , IL-6 , and IL-10 as well as YKL-40 and the oxidative stress markers malondialdehyde ( MDA ) , ascorbic acid ( AA ) and dehydroascorbic acid ( DHA ) before and at 2 , 4 , 6 and 8 hours after LPS administration .