2-Acetylaminofluorene: A hepatic carcinogen whose mechanism of activation involves N-hydroxylation to the aryl hydroxamic acid followed by enzymatic sulfonation to sulfoxyfluorenylacetamide. It is used to study the carcinogenicity and mutagenicity of aromatic amines.Hydroxyacetylaminofluorene: A N-hydroxylated derivative of 2-ACETYLAMINOFLUORENE that has demonstrated carcinogenic action.Acetoxyacetylaminofluorene: An alkylating agent that forms DNA ADDUCTS at the C-8 position in GUANINE, resulting in single strand breaks. It has demonstrated carcinogenic action.Fluorenes: A family of diphenylenemethane derivatives.Carcinogens: Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.Liver Neoplasms, Experimental: Experimentally induced tumors of the LIVER.Rats, Inbred F344Diethylnitrosamine: A nitrosamine derivative with alkylating, carcinogenic, and mutagenic properties.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.DNA Adducts: The products of chemical reactions that result in the addition of extraneous chemical groups to DNA.Biotransformation: The chemical alteration of an exogenous substance by or in a biological system. The alteration may inactivate the compound or it may result in the production of an active metabolite of an inactive parent compound. The alterations may be divided into METABOLIC DETOXICATION, PHASE I and METABOLIC DETOXICATION, PHASE II.gamma-Glutamyltransferase: An enzyme, sometimes called GGT, with a key role in the synthesis and degradation of GLUTATHIONE; (GSH, a tripeptide that protects cells from many toxins). It catalyzes the transfer of the gamma-glutamyl moiety to an acceptor amino acid.Precancerous Conditions: Pathological processes that tend eventually to become malignant. (From Dorland, 27th ed)Mutagens: Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.Benzopyrene Hydroxylase: A drug-metabolizing, cytochrome P-448 (P-450) enzyme which catalyzes the hydroxylation of benzopyrene to 3-hydroxybenzopyrene in the presence of reduced flavoprotein and molecular oxygen. Also acts on certain anthracene derivatives. An aspect of EC 1.14.14.1.p-Dimethylaminoazobenzene: A reagent used mainly to induce experimental liver cancer. According to the Fourth Annual Report on Carcinogens (NTP 85-002, p. 89) published in 1985, this compound "may reasonably be anticipated to be a carcinogen." (Merck, 11th ed)DNA: A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).Nitroanisole O-Demethylase: Oxidative enzyme which transforms p-nitroanisole into p-nitrophenol.Benzo(a)pyrene: A potent mutagen and carcinogen. It is a public health concern because of its possible effects on industrial workers, as an environmental pollutant, an as a component of tobacco smoke.Methyldimethylaminoazobenzene: A very potent liver carcinogen.Microsomes, Liver: Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.Hepatectomy: Excision of all or part of the liver. (Dorland, 28th ed)Lipotropic Agents: Endogenous factors or drugs that increase the transport and metabolism of LIPIDS including the synthesis of LIPOPROTEINS by the LIVER and their uptake by extrahepatic tissues.4-Hydroxyaminoquinoline-1-oxide: A potent mutagen and carcinogen. It is a reduction product of 4-NITROQUINOLINE-1-OXIDE. It binds with nucleic acids and inactivates both bacteria and bacteriophage.Aldrin: A highly poisonous substance that was formerly used as an insecticide. The manufacture and use has been discontinued in the U.S. (From Merck Index, 11th ed)Benzopyrenes: A class of chemicals that contain an anthracene ring with a naphthalene ring attached to it.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Liver Regeneration: Repair or renewal of hepatic tissue.Deoxyguanosine: A nucleoside consisting of the base guanine and the sugar deoxyribose.Polydeoxyribonucleotides: A group of 13 or more deoxyribonucleotides in which the phosphate residues of each deoxyribonucleotide act as bridges in forming diester linkages between the deoxyribose moieties.DNA Repair: The reconstruction of a continuous two-stranded DNA molecule without mismatch from a molecule which contained damaged regions. The major repair mechanisms are excision repair, in which defective regions in one strand are excised and resynthesized using the complementary base pairing information in the intact strand; photoreactivation repair, in which the lethal and mutagenic effects of ultraviolet light are eliminated; and post-replication repair, in which the primary lesions are not repaired, but the gaps in one daughter duplex are filled in by incorporation of portions of the other (undamaged) daughter duplex. Excision repair and post-replication repair are sometimes referred to as "dark repair" because they do not require light.Aminobiphenyl Compounds: Biphenyl compounds substituted in any position by one or more amino groups. Permitted are any substituents except fused rings.Sulfuric Acids: Inorganic and organic derivatives of sulfuric acid (H2SO4). The salts and esters of sulfuric acid are known as SULFATES and SULFURIC ACID ESTERS respectively.Mutagenicity Tests: Tests of chemical substances and physical agents for mutagenic potential. They include microbial, insect, mammalian cell, and whole animal tests.Hydroxylation: Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)DNA Replication: The process by which a DNA molecule is duplicated.Amines: A group of compounds derived from ammonia by substituting organic radicals for the hydrogens. (From Grant & Hackh's Chemical Dictionary, 5th ed)Methylcholanthrene: A carcinogen that is often used in experimental cancer studies.DNA Damage: Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.Nitrophenols