4-Nitroquinoline-1-oxideNitroquinolinesTongue Neoplasms4-Hydroxyaminoquinoline-1-oxideCarcinogensNitro CompoundsTongueHesperidinMutagensPronaseNitric Oxide SynthaseAminoquinolinesMouth NeoplasmsQuinolinesPapillomaPolyaminesAnticarcinogenic AgentsCarcinoma, Squamous CellPrecancerous ConditionsDNADNA RepairNitric Oxide Synthase Type IIRats, Inbred F344FibroblastsOxidesGlutathione TransferaseDNA DamageUltraviolet RaysNitric Oxide Synthase Type IIICell Transformation, NeoplasticNitric Oxide Synthase Type IPyridinesCells, CulturedNitrogen OxidesZinc OxideLiverCentrifugation, Density Gradient