| tachyphylaxis | 1. <immunology> The rapid immunisation against the effect of toxic doses of an extract or serum by previous injection of small doses. 2. <pharmacology> The rapidly decreasing response to a drug or physiologically active agent after administration of a few doses. Origin: Gr. Phylaxis = protection (16 Dec 1997) |
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| tachypnea | An abnormally rapid (usually shallow) respiratory rate. The normal resting adult respiratory rate is 12-20 breaths/minute. (27 Sep 1997) |
| tachyrhythmia | Synonym: tachycardia. Origin: tachy-+ G. Rhythmos, rhythm (05 Mar 2000) |
| tachysterol | Sterol(s) formed by ultraviolet irradiation of any 5,7-diene-3b-sterol, which breaks the 9,10 bond, but usually from either or both of ergosterol and lumisterol to produce tachysterol2 (ertacalciol, (6E,22E)-9,10-secoergosta-5(10),6,8,22-tetraen-3b-ol) and from 7-dehydrocholesterol to produce tachysterol3 (tacalciol,(6E,3S)-9,10-secocholesta-5(10),6,8-trien-3b-ol). When reduced to the 5,7-diene (or 5,7,22-triene) form, dihydrotachysterol3 (10,19-dihydrocalciol) or dihydrotachysterol2 (10,19-dihydroercalciol), antirachitic action appears. This property has been of therapeutic interest, but tachysterol is being replaced by the true vitamin D hormone (calcitriol) and its derivatives. (05 Mar 2000) |
| tachysystole | Synonym: tachycardia. Origin: tachy-+ G. Systole, contracting (05 Mar 2000) |
| tachyzoite | A rapidly multiplying stage in the development of the tissue phase of certain coccidial infections, as in Toxoplasma gondii development in acute infections of toxoplasmosis. Origin: tachy-+ G. Zoon, animal (05 Mar 2000) |
| tackle | 1. Apparatus for raising or lowering heavy weights, consisting of a rope and pulley blocks; sometimes, the rope and attachments, as distinct from the block. 2. Any instruments of action; an apparatus by which an object is moved or operated; gear; as, fishing tackle, hunting tackle; formerly, specifically, weapons. "She to her tackle fell." In Chaucer, it denotes usually an arrow or arrows. 3. The rigging and apparatus of a ship; also, any purchase where more than one block is used. Fall and tackle. See the Note under Pulley. Fishing tackle. See Fishing, Ground tackle, a board, frame, or post, at the end of a ropewalk, for supporting the spindels, or whirls, for twisting the yarns. Origin: OE. Takel, akin to LG. & D. Takel, Dan. Takkel, Sw. Tackel; perhaps akin to E. Taw, v.t, or to take. Source: Websters Dictionary (01 Mar 1998) |
| tackling | 1. Furniture of the masts and yards of a vessel, as cordage, sails, etc. 2. Instruments of action; as, fishing tackling. 3. The straps and fixures adjusted to an animal, by which he draws a carriage, or the like; harness. Source: Websters Dictionary (01 Mar 1998) |
| taconic | <geology> Designating, or pertaining to, the series of rocks forming the Taconic mountains in Western new England. They were once supposed to be older than the Cambrian, but later proved to belong to the Lower Silurian and Cambrian. Source: Websters Dictionary (01 Mar 1998) |
| tacrine | <chemical> A cholinesterase inhibitor that crosses the blood-brain barrier. Tacrine has been used to counter the effects of muscle relaxants, as a respiratory stimulant, and in the treatment of alzheimer's disease and other central nervous system disorders. Pharmacological action: cholinesterase inhibitor, nootropic agents, parasympathomimetic. Chemical name: 9-Acridinamine, 1,2,3,4-tetrahydro- (12 Dec 1998) |
| tacrolimus | <chemical> A macrolide isolated from the culture broth of a strain of streptomyces tsukubaensis that has strong immunosuppressive activity in vivo and prevents the activation of T-lymphocytes in response to antigenic or mitogenic stimulation in vitro. Pharmacological action: immunosuppressive agents. Chemical name: 15,19-Epoxy-3H-pyrido(2,1-c)(1,4)oxaazacyclotricosine-1,7,20,21(4H,23H)-tetrone, 5,6,8,11,12,13,14,15,16,17,18,19,24,25,26,26a-hexadecahydro-5,19-dihydroxy-3-(2-(4-hydroxy-3-methoxycyclohexyl)-1-methylethenyl)-14,16-dimethoxy-4,10,12,18-tetramethyl-8-(2-propenyl)-, monohydrate, (3S-(3R*(E(1S*,3S*,4S*)),4S*,5R*,8S*,9E,12R*,14R*,15S*,16R*,18S*,19S*,26aR*))- (12 Dec 1998) |
| tactile | Of or pertaining to the organs, or the sense, of touch; perceiving, or perceptible, by the touch; capable of being touched; as, tactile corpuscles; tactile sensations. "Tactile sweets." . "Tactile qualities." . <physiology> Tactile sense, the sense of touch, or pressure sense. See Touch. "The delicacy of the tactile sense varies on different parts of the skin; it is geatest on the forehead, temples and back of the forearm." (H. N. Martin) Origin: L. Tactilis, fr. Tangere, tactum, to touch: cf. F. Tactile. Source: Websters Dictionary (01 Mar 1998) |
| tactile agnosia | The inability to recognise objects by touch, in the presence of intact cutaneous and proprioceptive hand sensation; caused by lesion in the contralateral parietal lobe. Synonym: astereognosis, stereoagnosis, stereoanesthesia. (05 Mar 2000) |
| tactile anaesthesia | Loss or impairment of the sense of touch. (05 Mar 2000) |
| tactile cell | One of the epithelioid cell's of a corpusculum tactus. Synonym: touch cell. (05 Mar 2000) |