| masked messenger RNA | <molecular biology> Long lived and stable mRNA found originally in the oocytes of echinoderms and constituting a store of maternal information for protein synthesis that is unmasked (derepressed) during the early stages of morphogenesis. In these early stages the rate of cell division is so rapid that transcription from the embryonic genome cannot occur. Undoubtedly not restricted to oocytes and the term can be applied to any mRNA which is present in inactive form. (18 Nov 1997) |
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| masked virus | A virus ordinarily occurring in the host in a noninfective state, but which may be activated and demonstrated by special procedures such as blind passage in experimental animals. (05 Mar 2000) |
| masking | 1. The use of noise of any kind to interfere with the audibility of another sound. For any given intensity, low pitched tones have a greater masking effect than those of a high pitch. 2. In audiology, the use of a noise applied to one ear while testing the hearing acuity of the other ear. 3. The hiding of smaller rhythms in the brain wave record by larger and slower ones whose wave form they distort. 4. In dentistry, an opaque covering used to camouflage the metal parts of a prosthesis. 5. In radiography, superimposition of an altered positive image on the original negative to produce an enhanced copy photographically. See: subtraction. (05 Mar 2000) |
| masklike face | The expressionless or masklike facies characteristic of parkinsonism. Synonym: masklike face. (05 Mar 2000) |
| masks | Protective coverings for the face, particularly the mouth and nose, to maintain antiseptic conditions, to protect the wearer from contamination and to prevent droplets from the wearer's nose and mouth from spreading in the air. It includes surgical masks worn in the operating room and dentists' offices. It refers also to devices designed to cover the mouth and nose for administration of inhalation anaesthetics, oxygen, or other gases. (12 Dec 1998) |
| maslach | <medicine> An excitant containing opium, much used by the Turks. Origin: Ar. Maslaq: cf. F. Masloc. Source: Websters Dictionary (01 Mar 1998) |
| Maslow | Abraham H., U. S. Psychologist, 1908-1970. See: Maslow's hierarchy. (05 Mar 2000) |
| Maslow's hierarchy | A ranking of needs which man presumably fills successively in the order of lowest to highest: physiological needs, love and belonging, self-esteem, and self-actualization. (05 Mar 2000) |
| masochism | Pleasure from one's own pain. Named after the 19th-century austrian writer leopold von sacher-masoch (masoch-ism). (12 Dec 1998) |
| masochist | The passive party in the practice of masochism. (05 Mar 2000) |
| masochistic personality | A personality disorder in which the individual accepts exploitation and sacrifices self-interest while at the same time feeling morally superior or feigning moral superiority, attempting to elicit sympathy, and inducing guilt in others. (05 Mar 2000) |
| mason | 1. One whose occupation is to build with stone or brick; also, one who prepares stone for building purposes. 2. A member of the fraternity of Freemasons. See Freemason. <zoology> Mason bee, any wasp that constructs its nest, or brood cells, of hardened mud. The female fills the cells with insects or spiders, paralysed by a sting, and thus provides food for its larvae Origin: F. Maon, LL. Macio, machio, mattio, mactio, marcio, macerio; of uncertain origin. Source: Websters Dictionary (01 Mar 1998) |
| Mason operation | Surgical procedure in which the stomach is transected high on the body. The resulting proximal remnant is joined to a loop of the jejunum in an end-to-side anastomosis. This procedure is used frequently in the treatment of morbid obesity. (12 Dec 1998) |
| mason's lung | Silicosis occurring in stone masons. (05 Mar 2000) |
| mason-pfiser monkey virus | The type species of type d retroviruses (retroviruses, type d) isolated from mammary carcinoma and normal tissues in rhesus monkeys. It appears to have evolved from a recombination between a murine b oncovirus and a primate c oncovirus related to the baboon endogenous virus. Mpmv induces simian aids (saids). (12 Dec 1998) |