TNF and acute respiratory distress syndrome: Plasma serotonin, nitrate/nitrite, methyl guanidine, which is an index of free radicals, tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), and interleukin-10 (IL-10) were shown to be significantly elevated in FE-induced ARDS patients4–7, and inhibition of iNOS could significantly attenuate the FE-induced inflammatory response and pulmonary damage7–9.