arNOX activity is assayed from measurements of superoxide production based on the standard method where reduction of ferricytochrome c by superoxide is monitored from the increase in absorbance at 550 nm with reference at 540 nm. As a further check for the specificity of the arNOX activity, superoxide dismutase (SOD) is added near the end of the assay to ascertain that the rate returned to base line. The assay consists of 150 μl (2 mg/ml) oxidized ferricytochrome c solution and 200 μl of saliva added to 2.5 ml assay buffer (8.06 g NaC1, 0.2 g KC1, 0.18 g Na 2HPO4, 0.26 g KH2PO4, 0.13 g CaCl2, 0.1 g MgCl2, 1.35 g glucose dissolved in 1000 ml deionized water, adjusted to pH 7.4, filtered and stored at 4◦C). Rates are determined using a spectrophotometer in the dual wavelength mode with continuous measurements (over 1 min every 1.5 min). After 45 min, 60 μl (containing 60 units) SOD is added and the assay is continued for an additional 45 min.