Glossary

Alcohol Research & Health, Wntr, 2007

Acetaldehyde: A toxic byproduct of alcohol metabolism.

Acetate: A compound produced from the metabolism of acetaldehyde.

Adduct: Product of the addition of one compound (e.g., acetaldehyde) to another compound (e.g., DNA).

Adenoma: A usually benign tumor of tissue lining the internal and external organs of the body (i.e., epithelial tissue) in which the tumor cells are arranged in a gland-like structure.

Adenomatous polyps: A tissue mass that bulges outward from the normal surface and which consists of benign tumor tissue; found, for example, in the colon.

Adenosine triphosphate (ATP): A molecule, generated largely in the mitochondria, that provides the energy needed for many key metabolic reactions.

Affinity: Measure of the strength with which an enzyme (e.g., alcohol dehydrogenase [ADH]) interacts with its target molecule (e.g., ethanol); an enzyme variant with a higher affinity can interact with its target at lower concentrations of the target molecule than an enzyme variant with a lower affinity.

Alcohol dehydrogenase (ADH): An enzyme that breaks down alcohol by oxidation, converting it to acetaldehyde. (See cytochrome P450.)

Aldehyde dehydrogenase (ALDH): An enzyme that converts acetaldehyde to acetate.

Allele: One of two or more variants of a certain gene.

Amine: A type of organic compound that contains nitrogen as a central atom.

Amino acids: The principal building blocks of proteins and enzymes.

Amino group: A group of atoms found in all amines and amino acids.

Antibody: A protein produced by certain immune cells that recognizes and binds to foreign proteins, leading to the destruction of those proteins.

Antibody-dependent cell-mediated cytotoxicity (ADCC): A mechanism of cell-mediated immunity whereby certain immune cells actively break up a target cell that has been bound by specific antibodies.

Antioxidant: A substance, such as glutathione, vitamin E, or an enzyme, that inhibits oxidation and that scavenges free radicals and protects the cell against damage caused by these radicals.

Apoptosis: Cell death in which the affected cell participates by activating a cascade of biochemical reactions that lead to death; also known as programmed cell death or cell suicide.

Aromatic amino acids: A class of amino acids, including phenylalanine and tryptophan, in which some of the constituent atoms form a ring.

Carcinogenesis: The process of initiating and promoting cancer.

Carcinoma: A malignant tumor of the epithelial tissue that tends to invade surrounding tissue and metastasize to other regions of the body.

Case-control study: An epidemiologic approach in which previously existing cases of a condition (e.g., a type of cancer) are compared with a control group of people who have similar characteristics (e.g., gender, age, and alcohol use history) but have not developed the condition under investigation; the two groups are compared to determine which factor (e.g., ALD allele) may account for the increased disease incidence in the case group.

Catalase: An enzyme that catalyzes the decomposition of hydrogen peroxide into water and oxygen.

Central vein: Blood vessel located in the center of each liver lobule through which cleansed blood exits the lobule and which feeds into the hepatic vein; also called hepatic venule.

Coenzyme: A nonprotein substance that combines with an enzyme to form a complete, functional complex.

Cohort study: An epidemiologic approach in which a group of people who share a common characteristic (e.g., who were all born in the same town or who all entered the an alcoholism treatment program) are followed to determine which of them develop a certain condition (e.g., cancer).

Cytochrome P450: A family of cytochromes, one of which (CYP2E1) can oxidize alcohol to form acetaldehyde; high alcohol levels stimulate CYP2E1 activity.

Cytochromes: Specialized enzymes within mitochondria and other cell structures. Different cytochromes play important roles in metabolizing toxic substances, drugs, and other chemicals, as well as in producing adenosine triphosphate (ATP).

Cytokines: A family of molecules, produced primarily by cells of the immune system, that regulate cellular interactions and other functions. Many cytokines play important roles in initiating and regulating inflammation.

Cytoplasm: The substance filling the cell, including the cytosol as well as mitochondria, endoplasmic reticulum, and other cell structures (organelles) but excluding the nucleus.

Cytosol: The fluid portion of the cytoplasm.

Dimer: Compound formed by the combination of two simpler molecules (subunits) that normally are not functional by themselves.

Electron: A subatomic particle with a negative charge.

Endocytosis: Mechanism by which specific molecules are ingested into the cell.

Endoplasmic reticulum: A system of folded membranes that loop back and forth, spreading throughout the cytoplasm and providing a large surface area for cell reactions.

Endothelial cells: Type of cell lining the body cavities and blood vessels; control the passage of materials and the transit of white blood cells into and out of the bloodstream.