| Symmers' fibrosis | A characteristic pipe-shaped fibrosis formed around hepatic portal veins in some cases of long-continued heavy infection with Schistosoma mansoni; thought to be induced by the presence of large numbers of schistosome eggs in the hepatic tissues. Synonym: Symmers' clay pipestem fibrosis, Symmers' fibrosis. (05 Mar 2000) |
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| Symmers, Douglas | <person> U.S. Pathologist, 1879-1952. See: Brill-Symmers disease. (05 Mar 2000) |
| Symmers, W | <person> British pathologist, 1863-1937. See: Symmers' clay pipestem fibrosis. (05 Mar 2000) |
| symmetric adenolipomatosis | Accumulation and progressive enlargement of collections of adipose tissue in the subcutaneous tissue of the head, neck, upper trunk, and upper portions of the upper extremities; seen primarily in adult males and of unknown cause. Synonym: Launois-Bensaude syndrome, Madelung's disease, symmetric adenolipomatosis. (05 Mar 2000) |
| symmetric asphyxia | <syndrome> Idiopathic paroxysmal bilateral cyanosis of the digits due to arterial and arteriolar contraction; caused by cold or emotion. See: Raynaud's phenomenon. Synonym: Raynaud's disease, symmetric asphyxia. (05 Mar 2000) |
| symmetric distal neuropathy | <neurology> A disease process involving a number of peripheral nerves. Origin: Gr. Pathos = disease (14 Oct 1997) |
| symmetric disulfide | Disulfide that is symmetric on both sides of the -s-s- linkage; i.e., disulfide formed from identical thiol-containing compounds; e.g., cystine, glutathione disulfide. (05 Mar 2000) |
| symmetrical | 1. Involving or exhibiting symmetry; proportional in parts; having its parts in due proportion as to dimensions; as, a symmetrical body or building. 2. <biology> Having the organs or parts of one side correspponding with those of the other; having the parts in two or more series of organs the same in number; exhibiting a symmetry.See Symmetry. 3. <botany> Having an equal number of parts in the successive circles of floral organs; said of flowers. Having a likeness in the form and size of floral organs of the same kind; regular. 4. <mathematics> Having a common measure; commensurable. Having corresponding parts or relations. A curve or a plane figure is symmetrical with respect to a given line, and a line, surface, or solid with respect to a plane, when for each point on one side of the line or plane there is a corresponding point on the other side, so situated that the line joining the two corresponding points is perpendicular to the line or plane and is bisectad by it. Two solids are symmetrical when they are so situate dwith the respect to an intervening plane that the several points of their surfaces thus correspond to each other in position and distance. In analysis, an expression is symmetrical with respect to several letters when any two of them may change places without affecting the expression; as, the expression a^2b + ab^2 + a^2c + ac^2 + b^2c + bc^2, is symmetrical with respect to the letters a, b, c. Symmet"rically, Symmet"ricalness. Origin: Cf. F. Symetrique. See Symmetry. Source: Websters Dictionary (01 Mar 1998) |
| symmetrical gangrene | Gangrene affecting the extremities of both sides of the body; it is seen particularly in severe arteriosclerosis, myocardial infarction, and ball-valve thrombus. (05 Mar 2000) |
| symmetry | 1. A due proportion of the several parts of a body to each other; adaptation of the form or dimensions of the several parts of a thing to each other; the union and conformity of the members of a work to the whole. 2. <biology> The law of likeness; similarity of structure; regularity in form and arrangement; orderly and similar distribution of parts, such that an animal may be divided into parts which are structurally symmetrical. Bilateral symmetry, or two-sidedness, in vertebrates, etc, is that in which the body can be divided into symmetrical halves by a vertical plane passing through the middle; radial symmetry, as in echinoderms, is that in which the individual parts are arranged symmetrically around a central axis; serial symmetry, or zonal symmetry, as in earthworms, is that in which the segments or metameres of the body are disposed in a zonal manner one after the other in a longitudinal axis. This last is sometimes called metamerism. 3. <botany> Equality in the number of parts of the successive circles in a flower. Likeness in the form and size of floral organs of the same kind; regularity. Axis of symmetry. <geometry> See Axis. Respective symmetry, that disposition of parts in which only the opposite sides are equal to each other. Origin: L. Symmetria, Gr.; with, together + a measure: cf. F. Symetrie. See Syn-, and Meter rhythm. Source: Websters Dictionary (01 Mar 1998) |
| symmetry axis | <radiobiology> The straight line (usually vertical) through the centre of a configuration, when the configuration is symmetric to all (axisymmetric, like the tokamak) or some (periodic, like the stellarator) rotations about this line. Usually the z-axis. (09 Oct 1997) |
| sympath- | Sympatheto-sympathico-sympatho- The sympathetic part of the autonomic nervous system. Origin: see sympathetic (05 Mar 2000) |
| sympathectomy | <procedure, surgery> Excision of a sympathetic nerve. Occasionally used for the treatment of reflex sympathetic dystrophy. (27 Sep 1997) |
| sympathectomy, chemical | Sympathectomy using chemicals (e.g., 6-hydroxydopamine or guanethidine) which selectively and reversibly destroy adrenergic nerve endings while leaving cholinergic nerve endings intact. (12 Dec 1998) |
| sympathetectomy | <procedure, surgery> Excision of a sympathetic nerve. Occasionally used for the treatment of reflex sympathetic dystrophy. (27 Sep 1997) |