Cholestanes: Derivatives of the saturated steroid cholestane with methyl groups at C-18 and C-19 and an iso-octyl side chain at C-17.Research Report: Detailed account or statement or formal record of data resulting from empirical inquiry.Databases, Protein: Databases containing information about PROTEINS such as AMINO ACID SEQUENCE; PROTEIN CONFORMATION; and other properties.Internet: A loose confederation of computer communication networks around the world. The networks that make up the Internet are connected through several backbone networks. The Internet grew out of the US Government ARPAnet project and was designed to facilitate information exchange.User-Computer Interface: The portion of an interactive computer program that issues messages to and receives commands from a user.Software: Sequential operating programs and data which instruct the functioning of a digital computer.ArchivesProteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Anthozoa: A class in the phylum CNIDARIA, comprised mostly of corals and anemones. All members occur only as polyps; the medusa stage is completely absent.CyclopropanesDiterpenes: Twenty-carbon compounds derived from MEVALONIC ACID or deoxyxylulose phosphate.Pennisetum: A plant genus of the family POACEAE. The seed is one of the millets used in EDIBLE GRAIN. It contains vitexin. The common name of buffelgrass is also used for CENCHRUS.Mycolic AcidsChenopodium: A plant genus in the CHENOPODIACEAE family.Panicum: A plant genus of the family POACEAE. The seed is one of the EDIBLE GRAINS used in millet cereals and in feed for birds and livestock (ANIMAL FEED). It contains diosgenin (SAPONINS).StigmasterolPhytosterols: A class of organic compounds known as STEROLS or STEROIDS derived from plants.Sitosterols: A family of sterols commonly found in plants and plant oils. Alpha-, beta-, and gamma-isomers have been characterized.Hemibody Irradiation: Irradiation of one half or both halves of the body in the treatment of disseminated cancer or widespread metastases. It is used to treat diffuse metastases in one session as opposed to multiple fields over an extended period. The more frequent treatment modalities are upper hemibody irradiation (UHBI) or lower hemibody irradiation (LHBI). Less common is mid-body irradiation (MBI). In the treatment of both halves of the body sequentially, hemibody irradiation permits radiotherapy of the whole body with larger doses of radiation than could be accomplished with WHOLE-BODY IRRADIATION. It is sometimes called "systemic" hemibody irradiation with reference to its use in widespread cancer or metastases. (P. Rubin et al. Cancer, Vol 55, p2210, 1985)Cholestadienols: Cholestadiene derivatives containing a hydroxy group anywhere in the molecule.Absorption: The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.Nasal Mucosa: The mucous lining of the NASAL CAVITY, including lining of the nostril (vestibule) and the OLFACTORY MUCOSA. Nasal mucosa consists of ciliated cells, GOBLET CELLS, brush cells, small granule cells, basal cells (STEM CELLS) and glands containing both mucous and serous cells.Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)X-Ray Diffraction: The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.European Union: The collective designation of three organizations with common membership: the European Economic Community (Common Market), the European Coal and Steel Community, and the European Atomic Energy Community (Euratom). It was known as the European Community until 1994. It is primarily an economic union with the principal objectives of free movement of goods, capital, and labor. Professional services, social, medical and paramedical, are subsumed under labor. The constituent countries are Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain, Sweden, and the United Kingdom. (The World Almanac and Book of Facts 1997, p842)Blood Volume: Volume of circulating BLOOD. It is the sum of the PLASMA VOLUME and ERYTHROCYTE VOLUME.Sterols: Steroids with a hydroxyl group at C-3 and most of the skeleton of cholestane. Additional carbon atoms may be present in the side chain. (IUPAC Steroid Nomenclature, 1987)Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Plants, Genetically Modified: PLANTS, or their progeny, whose GENOME has been altered by GENETIC ENGINEERING.Exobiology: The interdisciplinary science that studies evolutionary biology, including the origin and evolution of the major elements required for life, their processing in the interstellar medium and in protostellar systems. This field also includes the study of chemical evolution and the subsequent interactions between evolving biota and planetary evolution as well as the field of biology that deals with the study of extraterrestrial life.Space Flight: Travel beyond the earth's atmosphere.Extraterrestrial Environment: The environment outside the earth or its atmosphere. The environment may refer to a closed cabin (such as a space shuttle or space station) or to space itself, the moon, or other planets.Search Engine: Software used to locate data or information stored in machine-readable form locally or at a distance such as an INTERNET site.Earth (Planet): Planet that is the third in order from the sun. It is one of the four inner or terrestrial planets of the SOLAR SYSTEM.Evolution, Chemical: Chemical and physical transformation of the biogenic elements from their nucleosynthesis in stars to their incorporation and subsequent modification in planetary bodies and terrestrial biochemistry. It includes the mechanism of incorporation of biogenic elements into complex molecules and molecular systems, leading up to the origin of life.Cosmic Dust: Finely divided solid matter with particle sizes smaller than a micrometeorite, thus with diameters much smaller than a millimeter, moving in interplanetary space. (NASA Thesaurus, 1994)Dioscorea: A plant genus best known for edible underground tubers. Yam may also refer to a moist variety of sweet potato, IPOMOEA BATATAS.Diosgenin: A spirostan found in DIOSCOREA and other plants. The 25S isomer is called yamogenin. Solasodine is a natural derivative formed by replacing the spiro-ring with a nitrogen, which can rearrange to SOLANINE.Rhizome: Root-like underground horizontal stem of plants that produces shoots above and roots below. Distinguished from true roots which don't have buds and nodes. Similar to true roots in being underground and thickened by storage deposits.Breast Neoplasms: Tumors or cancer of the human BREAST.PakistanTrillium: A plant genus of the family LILIACEAE that is a short plant with a distinct whorl of 3 broad leaves.Plant Tubers: An enlarged underground root or stem of some plants. It is usually rich in carbohydrates. Some, such as POTATOES, are important human FOOD. They may reproduce vegetatively from buds.Cholestanols: Cholestanes substituted in any position with one or more hydroxy groups. They are found in feces and bile. In contrast to bile acids and salts, they are not reabsorbed.Hydroxylation: Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)Lanosterol: A triterpene that derives from the chair-boat-chair-boat folding of 2,3-oxidosqualene. It is metabolized to CHOLESTEROL and CUCURBITACINS.Desmosterol: An intermediate in the synthesis of cholesterol.Cholestanetriol 26-Monooxygenase: An NAPH-dependent cytochrome P450 enzyme that catalyzes the oxidation of the side chain of sterol intermediates such as the 27-hydroxylation of 5-beta-cholestane-3-alpha,7-alpha,12-alpha-triol.Steroid Hydroxylases: Cytochrome P-450 monooxygenases (MIXED FUNCTION OXYGENASES) that are important in steroid biosynthesis and metabolism.