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.Benzopyrenes: A class of chemicals that contain an anthracene ring with a naphthalene ring attached to it.Methyl n-Butyl Ketone: An industrial solvent which causes nervous system degeneration. MBK is an acronym often used to refer to it.Methylcholanthrene: A carcinogen that is often used in experimental cancer studies.1-Methyl-3-isobutylxanthine: A potent cyclic nucleotide phosphodiesterase inhibitor; due to this action, the compound increases cyclic AMP and cyclic GMP in tissue and thereby activates CYCLIC NUCLEOTIDE-REGULATED PROTEIN KINASESButanols: Isomeric forms and derivatives of butanol (C4H9OH).Technetium Tc 99m Sestamibi: A technetium imaging agent used to reveal blood-starved cardiac tissue during a heart attack.Pyruvate Decarboxylase: Catalyzes the decarboxylation of an alpha keto acid to an aldehyde and carbon dioxide. Thiamine pyrophosphate is an essential cofactor. In lower organisms, which ferment glucose to ethanol and carbon dioxide, the enzyme irreversibly decarboxylates pyruvate to acetaldehyde. EC 126.96.36.199.Xanthines: Purine bases found in body tissues and fluids and in some plants.Keto AcidsPhosphodiesterase Inhibitors: Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.Toxicity Tests: An array of tests used to determine the toxicity of a substance to living systems. These include tests on clinical drugs, foods, and environmental pollutants.Dihydroxydihydrobenzopyrenes: Benzopyrenes saturated in any two adjacent positions and substituted with two hydroxyl groups in any position. The majority of these compounds have carcinogenic or mutagenic activity.Tomography, Emission-Computed, Single-Photon: A method of computed tomography that uses radionuclides which emit a single photon of a given energy. The camera is rotated 180 or 360 degrees around the patient to capture images at multiple positions along the arc. The computer is then used to reconstruct the transaxial, sagittal, and coronal images from the 3-dimensional distribution of radionuclides in the organ. The advantages of SPECT are that it can be used to observe biochemical and physiological processes as well as size and volume of the organ. The disadvantage is that, unlike positron-emission tomography where the positron-electron annihilation results in the emission of 2 photons at 180 degrees from each other, SPECT requires physical collimation to line up the photons, which results in the loss of many available photons and hence degrades the image.Cyclic AMP: An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.Solvents: Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)Environmental Pollutants: Substances or energies, for example heat or light, which when introduced into the air, water, or land threaten life or health of individuals or ECOSYSTEMS.Bucladesine: A cyclic nucleotide derivative that mimics the action of endogenous CYCLIC AMP and is capable of permeating the cell membrane. It has vasodilator properties and is used as a cardiac stimulant. (From Merck Index, 11th ed)Colforsin: Potent activator of the adenylate cyclase system and the biosynthesis of cyclic AMP. From the plant COLEUS FORSKOHLII. Has antihypertensive, positive inotropic, platelet aggregation inhibitory, and smooth muscle relaxant activities; also lowers intraocular pressure and promotes release of hormones from the pituitary gland.DNA Adducts: The products of chemical reactions that result in the addition of extraneous chemical groups to DNA.Ethyl Methanesulfonate: An antineoplastic agent with alkylating properties. It also acts as a mutagen by damaging DNA and is used experimentally for that effect.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.Heart: The hollow, muscular organ that maintains the circulation of the blood.Polycyclic Compounds: Compounds consisting of two or more fused ring structures.Polycyclic Hydrocarbons, Aromatic: A major group of unsaturated cyclic hydrocarbons containing two or more rings. The vast number of compounds of this important group, derived chiefly from petroleum and coal tar, are rather highly reactive and chemically versatile. The name is due to the strong and not unpleasant odor characteristic of most substances of this nature. (From Hawley's Condensed Chemical Dictionary, 12th ed, p96)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.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.Benz(a)Anthracenes: Four fused benzyl rings with three linear and one angular, that can be viewed as a benzyl-phenanthrenes. Compare with NAPHTHACENES which are four linear rings.Stereoisomerism: The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)Chrysenes: 1,2-Benzphenanthrenes. POLYCYCLIC COMPOUNDS obtained from coal tar.Cytochrome P-450 CYP1A1: A liver microsomal cytochrome P-450 monooxygenase capable of biotransforming xenobiotics such as polycyclic hydrocarbons and halogenated aromatic hydrocarbons into carcinogenic or mutagenic compounds. They have been found in mammals and fish. This enzyme, encoded by CYP1A1 gene, can be measured by using ethoxyresorufin as a substrate for the ethoxyresorufin O-deethylase activity.Epoxy Compounds: Organic compounds that include a cyclic ether with three ring atoms in their structure. They are commonly used as precursors for POLYMERS such as EPOXY RESINS.Mutagenicity Tests: Tests of chemical substances and physical agents for mutagenic potential. They include microbial, insect, mammalian cell, and whole animal tests.Pyrenes: A group of condensed ring hydrocarbons.Ethyl EthersPhenanthrenesCarcinogens, Environmental: Carcinogenic substances that are found in the environment.Microsomes, Liver: Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.Aryl Hydrocarbon Hydroxylases: A large group of cytochrome P-450 (heme-thiolate) monooxygenases that complex with NAD(P)H-FLAVIN OXIDOREDUCTASE in numerous mixed-function oxidations of aromatic compounds. They catalyze hydroxylation of a broad spectrum of substrates and are important in the metabolism of steroids, drugs, and toxins such as PHENOBARBITAL, carcinogens, and insecticides.Coal Tar: A by-product of the destructive distillation of coal used as a topical antieczematic. It is an antipruritic and keratoplastic agent used also in the treatment of psoriasis and other skin conditions. Occupational exposure to soots, tars, and certain mineral oils is known to be carcinogenic according to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985) (Merck Index, 11th ed).Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.