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Medical Dictionary


tautomerism (taw-tom′er-izm)
A phenomenon in which a chemical compound exists in two forms of different structure (isomers) in equilibrium, the two forms differing, usually, in the position of a hydrogen atom; e.g., keto-enol t., R–CH2–C(O)–R′ ⇆ R–CH&dbond;C(OH)–R′. [G. tautos, the same, + meros, part]

K. Sunao, Japanese pathologist, 1873–1952. See T. node, His-T. system, node of Aschoff and T..

taxa (tak′sa)
Plural of taxon.

taxanes (taks′anz)
A class of antitumor agents derived directly or semisynthetically from Taxus brevifolius, the Pacific yew; examples include paclitaxel and docetaxel.

taxis (tak′sis)
1. Reduction of a hernia or of a dislocation of any part by means of manipulation. 2. Systematic classification or orderly arrangement. 3. The reaction of protoplasm to a stimulus, by virtue of which animals and plants are led to move or act in certain definite ways in relation to their environment; the various kinds of t. are designated by a prefix denoting the stimulus governing them; e.g., chemotaxis, electrotaxis, thermotaxis. [G. orderly arrangement] negative t. the repulsion of protoplasm away from a stimulus. positive t. the attraction of protoplasm toward a stimulus.

taxon, pl .taxa (tak′son, tak′sa)
The name given to a particular level or grouping in a systematic classification of living things or organisms (taxonomy). [G. taxis, order, arrangement, + -on]

taxonomic (tak-so-nom′ik)
Relating to taxonomy.

taxonomy (tak-san′o-me)
The systematic classification of living things or organisms. Kingdoms of living organisms are divided into groups (taxa) to show degrees of similarity or presumed evolutionary relationships, with the higher categories being larger, more inclusive, and more broadly defined, and the lower categories being more restricted, with fewer species more closely related. The divisions below kingdom are, in descending order: phylum, class, order, family, genus, species, and subspecies (variety). Infra- and supra- or sub- and super- categories can be used when needed; additional categories, such as tribe, section, level, group, etc., are also used. [G. taxis, orderly arrangement, + nomos, law] chemical t. an approach to the classification of organisms based on the distribution of natural products. numerical t. an approach to the classification of organisms that strives for objectivity, wherein characteristics of organisms are given equal weight (adansonian classification) and the relationships of the organisms are numerically determined, usually by computer.

Taxus (taks′us)
Genus of plants including the Pacific yew (Taxus brevifolius); its bark yields antitumor agents of the taxane group.

Warren, English physician, 1843–1927. See T. cherry-red spot, T.-Sachs disease.

Hooshang, U.S. pediatrician and radiologist, *1919. See Rubinstein-T. syndrome.

Charles F., U.S. orthopedic surgeon, 1827–1899. See T. back brace, T. apparatus, T. splint.

Robert W., U.S. dermatologist, 1842–1908. See T. disease.

Colloquial abbreviation for tuberculosis.

Symbol for terbium.

Abbreviation for thyroxine-binding globulin.

Abbreviation for tert-butyloxycarbonyl.

Abbreviation for thyroxine-binding protein.

Abbreviation for thyroxine-binding prealbumin.

Abbreviation for total blood volume.

Abbreviation for total body water.

Symbol for technetium.

Abbreviation for T cytotoxic cells, under cell.

Symbol for technetium-99.

Abbreviation for 2,3,7,8-tetrachlorodibenzo[b,e]-[1,4]dioxin. See dioxin (3) .

Abbreviation for time compensation gain.

Abbreviation for tissue culture infectious dose.

Abbreviation for testis-determining factor.

Abbreviation for ribothymidine 5′-diphosphate. The thymidine analog is dTDP.

Abbreviation for terminal deoxynucleotidyl transferase.

In magnetic resonance spin echo pulse sequences, the time to echo, when the magnetization signal is sampled.

Symbol for tellurium.

tea (te)
1. The dried leaves of various genera of the family Theaceae, including Thea (T. senensis), Camellia, and Gordonia, a shrub indigenous to China, southern and southeastern Asia, and Japan. Its chief constituent, upon which its stimulating action largely depends, is the alkaloid caffeine, which is present in the amount of 1–4%; theophylline, a chemically related alkaloid, is also present. 2. The infusion made by pouring boiling water upon t. leaves. 3. Any infusion or decoction made extemporaneously. SEE ALSO: species (2) . SYN: thea. [Chinese (Amoy dial.) t'e, Mod. L. thea] Hottentot t. SYN: buchu. Jesuit t., Mexican t. SYN: chenopodium. Paraguay t. SYN: maté.

Thomas P., English surgeon, 1801–1868.

tear (tar)
A discontinuity in substance of a structure. Cf.:laceration. bucket-handle t. a t. and separation in the central part of a semilunar cartilage with the ends intact that produces a resemblance to the handle of a bucket. Mallory-Weiss t. SYN: Mallory-Weiss syndrome.

tear1 (ter)
The fluid secreted by the lacrimal glands by means of which the conjunctiva and cornea are kept moist. [A.S. teár] artificial tears mixtures of fluid compounds to substitute for naturally produced t's. crocodile tears crocodile tears syndrome.

tearing (ter′ing)
SYN: epiphora.

tease (tez)
To separate the structural parts of a tissue by means of a needle, in order to prepare it for microscopic examination. [A. S. taesan]

teaspoon (te′spoon)
A small spoon, holding about 1 dram (or about 5 mL) of liquid; used as a measure in the dosage of fluid medicines.

teat (tet)
1. SYN: nipple. 2. SYN: breast. 3. SYN: papilla. [A.S. tit]

tebutate (teb′u-tat)
USAN-approved contraction for tertiary butylacetate, (CH3)3C–CH2–CO2−.

technetium (Tc) (tek-ne′she-um)
An artificial radioactive element, atomic no. 43, atomic wt. 99, produced in 1937 by bombardment of molybdenum by deuterons; also a product of the fission of 235U; used extensively as a radiographic tracer in imaging studies of internal organs. [G. technetos, artificial]

technetium-99 (99Tc)
A radioisotope of technetium which is the decay product of technetium-99m and has a weak beta emission and a physical half-life of 213,000 years.

technetium-99m (99mTc)
A radioisotope of technetium that decays by isomeric transition, emitting an essentially monoenergetic gamma ray of 142 keV with a half-life of 6.01 hr. It is usually obtained from a radionuclide generator of molybdenum-99 and is used to prepare radiopharmaceuticals for scanning the brain, parotid, thyroid, lungs, blood pool, liver, heart, spleen, kidney, lacrimal drainage apparatus, bone, and bone marrow. 99mTc diphosphonate a radionuclide complex used for bone scans. 99mTc-DTPA a radionuclide chelate complex used for renal imaging and function testing; also known as 99mTc pentatate. [diethylene triamine pentaacetic acid] 99mTc sestamibi a lipophilic cationic complex of a 99mTc-labeled isonitrite, used as a radionuclide in several organs (e.g., brain, bone, thyroid, breast) for the detection of cancer, or in the heart for identifying coronary artery occlusion. It has superseded Tl-201 in cardiac imaging and in experimental breast imaging. 99mTc sulfur colloid a particulate radionuclide complex taken up by the reticuloendothelial system; used for imaging the liver and spleen.

technic (tek-nik′)
SYN: technique.

technical (tek′ni-kal)
1. Relating to technique. 2. Pertaining to some particular art, science, or trade. 3. In connection with a chemical substance, denoting that the substance contains appreciable quantities of impurities.

technician (tek-nish′un)
SYN: technologist. [G. techne, an art]

technique (tek-nek′)
The manner of performance, or the details, of any surgical operation, experiment, or mechanical act. SEE ALSO: method, operation, procedure. SYN: technic. [Fr., fr. G. technikos, relating to techne, art, skill] airbrasive t. a method of grinding, cutting tooth structure, or roughening the natural tooth surface or the surface of a restoration, by means of a device utilizing a gas-impelled jet of fine Al2O3 particles which, after striking the tooth, are removed by an aspirator. SEE ALSO: microetching t.. air-gap t. chest radiography performed using a space between the subject and film instead of a grid to absorb scattered radiation; usually requires a target-film distance of 10 feet. atrial-well t. an obsolete semiclosed surgical t. for repairing atrial septal defects and other cardiac abnormalities. ballpoint pen t. a t. to measure the induration of intradermal tuberculin tests; a ballpoint pen is used to draw two opposing lines on the skin beginning 1–2 cm away from the dermal reaction site on opposite sides, stopping as the induration edge is felt. The distance between the proximal ends of the lines is the reported extent of induration. Barcroft-Warburg t. Warburg apparatus. Begg light wire differential force t. light wire appliance. cellulose tape t. use of a piece of transparent cellulose tape applied to a glass slide to obtain perianal samples for identification of pinworm eggs. direct t. SYN: direct method for making inlays. Ficoll-Hypaque t. a density-gradient centrifugation t. for separating lymphocytes from other formed elements in the blood; the sample is layered onto a Ficoll-sodium metrizoate gradient of specific density; following centrifugation, lymphocytes are collected from the plasma-Ficoll interface. flicker fusion frequency t. SYN: flicker perimetry. fluorescent antibody t. a t. used to test for antigen with a fluorescent antibody, usually performed by one of two methods: direct, in which immunoglobulin (antibody) conjugated with a fluorescent dye is added to tissue and combines with specific antigen (microbe, or other), the resulting antigen-antibody complex being located by fluorescence microscopy; or indirect, in which unlabeled immunoglobulin (antibody) is added to tissue and combines with specific antigen, after which the antigen-antibody complex may be labeled with fluorescein-conjugated anti-immunoglobulin antibody, the resulting triple complex then being located by fluorescence microscopy. flush t. a t. for determining the systolic blood pressure in infants; the elevated limb is “milked” of blood from the hand or foot proximally; the blood pressure cuff is then inflated above the likely systolic pressure and the limb lowered; the cuff pressure is then gradually released until the blanched limb flushes. Hampton t. obsolete term for atraumatic, nonpalpation, fluoroscopic examination of the upper gastrointestinal tract in peptic ulcer disease with acute hemorrhage. Hartel t. a method of reaching the gasserian ganglion by passing a needle from the mouth, inserting it about the level of the upper midmolar tooth, and passing it inward until the point reaches the bone in front and to the outer side of the foramen ovale, allowing an alcohol injection to be made for the relief of trigeminal neuralgia. high-kV t. chest radiography using a kilovoltage of at least 125 kVp, usually 140–150 kVp, to reduce patient dose and increase latitude. Ilizarov t. a method of promoting controlled osteogenesis to lengthen bone and correct angular and rotational deformities, in which gradually increasing force is applied to the apposed fragments of a surgically divided bone by an external fixation frame (Ilizarov device). immunoperoxidase t. an immunologic test that utilizes antibodies chemically conjugated to the enzyme peroxidase. indirect t. SYN: indirect method for making inlays. Jerne t. a t. for measuring immunocompetence by quantitating the number of splenic antibody-forming cells found in a mouse that has been sensitized to sheep erythrocytes. The number of plaques formed correlates with the number of splenic antibody-forming cells. Judkins t. a method of selective coronary artery catheterization utilizing the standard Seldinger t. through a percutaneous femoral artery puncture. Knott t. concentration procedure using blood and dilute formalin; designed to detect microfilaria. long cone t. the use of a cone distance of 14 inches or more in making oral roentgenographs. McGoon t. plastic reconstruction of an incompetent mitral valve, when the incompetence is due to rupture of chordae to the posterior leaflet, by plication of the redundant leaflet. Merendino t. plastic reconstruction of an incompetent mitral valve using heavy sutures to narrow the annulus in the region of the medial commissure. microetching t. a method of roughening the surface of a natural tooth or a dental restoration utilizing a gas-impelled jet of fine abrasive. It enhances the attachment of resin cements or restorative materials to the surface. SEE ALSO: airbrasive t.. Mohs fresh tissue chemosurgery t. chemosurgery in which superficial cancers are excised after fixation in vivo. Ouchterlony t. a t. in which both reaction partners (antigen and antibody) are allowed to diffuse to each other in a gel in a precipitation reaction. PAP t. an unlabeled antibody peroxidase method that reacts both with the rabbit antihorseradish peroxidase antibody and free horseradish peroxidase to form a soluble complex of peroxidase antiperoxidase or PAP; a uniquely sensitive immunohistochemical method that is applicable to paraffin-embedded tissues. rebreathing t. use of a breathing or anesthesia circuit in which exhaled air is subsequently inhaled either with or without absorption of CO2 from the exhaled air. Rebuck skin window t. an in vivo test of the inflammatory response in which the skin is abraded and a slide applied to the abraded area to permit visualization of leukocyte mobilization. sealed jar t. a t. for producing suspended animation in small experimental animals, consisting of sealing the animal in a jar which is then refrigerated. Seldinger t. a method of percutaneous insertion of a catheter into a blood vessel or space: a needle is used to puncture the structure and a guide wire is threaded through the needle; when the needle is withdrawn, a catheter is threaded over the wire; the wire is then withdrawn, leaving the catheter in place. sterile insect t. a t. used to control or eradicate insect pests or vectors, utilizing induction by irradiation of dominant lethality in the chromosomes of the released insects. vacuum pack t. a temporary closing of the abdomen by using a fenestrated plastic sheet over the intestine but under the anterior abdominal wall followed by the placement of moistened pads with a suction catheter within the wound. The entire defect is then covered by a nonporous plastic sheet; permits drainage of the abdominal cavity by suction while maintaining anterior abdominal wall rigidity. washed field t. the cutting of cavity preparations in teeth utilizing a constant irrigant which is immediately removed from the mouth by means of a vacuum device.

technocausis (tek-no-kaw′sis)
SYN: actual cautery. [G. techne, art, + kausis, a burning]

technologist (tek-nol′o-jist)
One trained in and using the techniques of a profession, art, or science. SYN: technician.

technology (tek-nol′o-je)
The knowledge and use of the techniques of a profession, art, or science. [G. techne, an art, + logos, study] assisted reproductive t. originally, a range of techniques for manipulating eggs and sperm in order to overcome infertility. Encompasses drug treatments to stimulate ovulation; surgical methods for removing eggs ( e.g., laparoscopy and ultrasound-guided transvaginal aspiration) and for reimplanting embryos ( e.g., zygote intrafallopian transfer (or ZIFT); in vitro and in vivo fertilization ( e.g., artificial insemination and gamete intrafallopian transfer (or GIFT); ex utero and in utero fetal surgery; as well as laboratory regimes for freezing and screening sperm and embryos, and micromanipulating and cloning embryos. See eugenics.

teclothiazide (tek-lo-thi′a-zid)
SYN: tetrachlormethiazide.

tectal (tek′tal)
Relating to a tectum.

tectiform (tek′ti-form)

Tectiviridae (tek′te-vi′ra-da)
A name for a family of icosahedral nonenveloped double-stranded DNA bacteriophages that have double capsids. [L. tectum, roof, covering, + virus]

tectocephalic (tek′to-se-fal′ik)
SYN: scaphocephalic. [L. tectum, roof, + G. kephale, head]

tectocephaly (tek′to-sef′a-le)
SYN: scaphocephaly.

tectology (tek-tol′o-je)
Structural morphology. [G. tekton, builder, + -logia]

tectonic (tek-ton′ik)
Relating to variations in structure in the eye, particularly the cornea. [G. tektonikos, relating to building]

tectorial (tek-tor′e-al)
Relating to or characteristic of a tectorium.

tectorium (tek-tor′e-um)
1. An overlaying structure. 2. SYN: tectorial membrane of cochlear duct. [L. an overlaying surface (plaster, stucco), fr. tego, pp. tectus, to cover]

tectospinal (tek-to-spi′nal)
Denoting nerve fibers passing from the mesencephalic tectum to the spinal cord.

tectum, pl .tecta (tek′tum, tek′ta)
Any rooflike covering or structure. [L. roof, roofed structure, fr. tego, pp. tectus, to cover] t. mesencephali [TA] SYN: lamina of mesencephalic t.. t. of midbrain SYN: lamina of mesencephalic t..

Abbreviation for total end-diastolic diameter.

teel oil (tel)
SYN: sesame oil.

teeth (teth)
Plural of tooth. acoustic t. [TA] tooth-shaped formations or ridges occurring on the vestibular lip of the limbus lamina spiralis of the cochlear duct. SYN: dentes acustici [TA] , auditory t., Corti auditory t., Huschke auditory t..


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