| external base of skull | External aspect of the base of skull Synonym: norma basilaris, basis cranii externa, norma inferior, norma ventralis. (05 Mar 2000) |
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| lacunar skull | <radiology> Also known as: craniolacunia, mesenchymal dysplasia, may appear normal after several yrs associated with: Chiari malformation (almost always !), myelomeningocele, encephalocele in contrast, increased intracranial pressure has: beaten-silver appearance, closed sutures, with or without abnormal skull size (Lueckenschaedel) (12 Dec 1998) |
| lateral skull radiograph | A true lateral projection radiograph of facial bones and calvarium, showing bone structures and air-containing passages. (05 Mar 2000) |
| longitudinal arc of skull | The line carried over the skull in the midline from the nasion to the opisthion. (05 Mar 2000) |
| acetone compound | <biochemistry> Any of the three compounds created by acetyl coenzyme A (acetoacetate, hydroxybutyrate, and acetone) which are water-soluble cellular fuels normally exported by the liver. They can build up in the blood and body tissues because of starvation, untreated diabetes mellitus, or other disorders that interfere with carbohydrate metabolism. The body rids itself of ketones mainly through urine, but it rids itself of acetone through the lungs, which gives the breath a characteristic fruity odour. If ketones build up in the body long enough, they cause serious illness and coma (see ketoacidosis.) (09 Oct 1997) |
| acyclic compound | An organic compound in which the chain does not form a ring. Synonym: aliphatic compound, open chain compound. (05 Mar 2000) |
| addition compound | Strictly, a complex of two or more complete molecules in which each preserves its fundamental structure and no covalent bonds are made or broken (e.g., hydrates of salts, adducts), loosely, association of acids with basic organic compound's (e.g., amines with HCl), more loosely, addition of two molecules without loss of any atom, but forming new covalent bonds (e.g., CH2==CH2 + Br2 → BrCH2-CH2Br). (05 Mar 2000) |
| aliphatic compound | An organic compound in which the chain does not form a ring. Synonym: aliphatic compound, open chain compound. (05 Mar 2000) |
| APC compound | An analgesic tablet drug combination containing aspirin, phenacetin and caffeine. Very widely used in the 1940's through 1960's; original constituents of popular over-the-counter pain remedies. Use currently much diminished due to concerns about potential renal injury due to the phenacetin. (05 Mar 2000) |
| aromatic compound | Any compound in which the constituent atoms, or any part of them, form a ring. Used mainly in organic chemistry where: 1) numerous compound's contain rings of carbon atoms (carbocyclic compound's) or carbon atoms plus one or more atoms of other types (heterocyclic compound's), usually nitrogen, oxygen, or sulfur; 2) where the atoms in the ring are all of the same element (homocyclic or isocyclic compound); 3) where the ring is saturated or contains nonconjugated double bonds (alicyclic compound), the compound is similar in properties to the corresponding acyclic compound (e.g., cyclohexane resembles hexane); 4) where the ring contains conjugated double bonds in a closed loop in which there are 4n + 2 (where n is an integer) delocalised π electrons (Huckel's rule) (aromatic compound; e.g., benzene, pyridine), it is more stable than the corresponding saturated ring and exhibits unusual chemical properties characteristic of itself and not of other types of rings or of acyclic compound's. These aromatic compounds have the ability to sustain an induced ring current. Synonym: closed chain compound, ring compound. (05 Mar 2000) |
| binary compound | <chemistry> This refers to any compound that is composed of only two elements. (09 Oct 1997) |
| calcium compound | Inorganic compounds that contain calcium as an integral part of the molecule. (12 Dec 1998) |
| carbamino compound | Any carbamic acid derivative formed by the combination of carbon dioxide with a free amino group to form an N-carboxy group, -NH-COOH, as in haemoglobin forming carbaminohemoglobin. (05 Mar 2000) |
| carbocyclic compound | See: cyclic compound. (05 Mar 2000) |
| genetic compound | In medical genetics, the presence of two different mutant alleles at the same loci. Synonym: genetic compound. (05 Mar 2000) |