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Medical Dictionary


thrombosthenin (throm-bo-sthe′nin)
SYN: platelet actomyosin.

thrombotic (throm-bot′ik)
Relating to, caused by, or characterized by thrombosis.

thrombotonin (throm-bo-to′nin)
SYN: serotonin.

thromboxane (throm-bok′san)
The formal parent of the thromboxanes; prostanoic acid in which the –COOH has been reduced to –CH3 and an oxygen atom has been inserted between carbons 11 and 12.

thromboxanes (throm′bok-zanz)
A group of compounds, included in the eicosanoids, formally based on thromboxane, but with the terminal COOH group present; biochemically related to the prostaglandins and formed from them through a series of steps involving the formation of an endoperoxide (an O–O bridge between carbons 9 and 11 in the prostaglandins) by a cyclooxygenase, followed by a rearrangement (catalyzed by thromboxane synthase) that inserts one of the two oxygen atoms between carbons 11 and 12, leaving the other still bridging carbons 9 and 11. T. are so named from their influence on platelet aggregation and the formation of the oxygen-containing six-membered ring (pyran or oxane). Like the prostaglandins, individual t. (abbreviated TX) are designated by letters (A, B, C, etc.) and subscripts indicating structural features.

thrombozyme (throm′bo-zim)
SYN: thromboplastin.

thrombus, pl .thrombi (throm′bus, -bi)
A clot in the cardiovascular systems formed during life from constituents of blood; it may be occlusive or attached to the vessel or heart wall without obstructing the lumen (mural t.). [L. fr. G. thrombos, a clot] agglutinative t. SYN: hyaline t.. agonal t. a heart clot formed during the act of dying after prolonged heart failure. antemortem t. a clot formed in the circulation during life. ball t. an unattached, spherical antemortem t. found in the left or right atrium usually in certain cases of mitral stenosis. ball-valve t. ball t. intermittently occluding the mitral or tricuspid orifice. bile t. an intracanalicular deposit of bile, usually a result of obstruction to bile drainage. currant jelly t. SYN: postmortem t.. fibrin t. a t. formed by repeated deposits of fibrin from the circulating blood; it usually does not completely occlude the vessel. globular t. one of a number of thrombi of varying size, from a pea to a walnut, within the heart cavity, connected by a delicate fibrinous network. hyaline t. a translucent colorless plug, partly or wholly filling a capillary or small artery or vein, formed by agglutination of red blood corpuscles. SYN: agglutinative t.. infective t. a t. formed in septic phlebitis. laminated t. a t. formed gradually by clotting of the blood in successive layers. marantic t., marasmic t. a t. formed in cases of marasmus or general debility. mixed t. a laminated t., the layers of different ages being of different color or consistency. SYN: stratified t.. mural t. a t. formed on and attached to a diseased patch of endocardium, not on a valve or on one side of a large blood vessel. SEE ALSO: parietal t.. obstructive t. a t. due to obstruction in the vessel from compression or other cause. pale t. SYN: white t.. parietal t. an arterial t. adhering to one side of the wall of the vessel. SEE ALSO: mural t.. postmortem t. a clot formed within the heart or in a blood vessel after death, usually mainly red blood cells. SYN: currant jelly t.. propagated t. creeping thrombosis. red t. a t. formed rapidly by the coagulation of stagnating blood, composed mainly of red blood cells rather than platelets. secondary t. a t. formed about an embolus as a nucleus. stratified t. SYN: mixed t.. valvular t. a parietal t. that projects into the lumen of the vessel. white t. an opaque dull white t. composed essentially of blood platelets. SYN: pale t..

throughput (throo′put)
A term applied to analytic instruments specifying the number of tests that can be performed in a given time.

thrush (thrush)
Infection of the oral tissues with Candida albicans; often an opportunistic infection in humans with AIDS or humans suffering from other conditions that depress the immune system; also common in normal infants who have been treated with antibiotics. [fr. the t. fungus, Candida albicans]

thuja (thoo′ja, -ya)
The fresh tops of T. occidentalis (family Pinaceae), an ornamental evergreen tree of eastern North America, a source of cedar leaf oil; has been used internally as an expectorant, emmenagogue, and anthelmintic, and externally as a mild counterirritant. SYN: thuya. [G. thyia, an African tree with sweet-smelling wood] t. oil SYN: cedar leaf oil.

thujol (thoo′jol)
SYN: thujone.

thujone (thoo′jon)
C10H16O;the chief constituent of cedar leaf oil; a stimulant and convulsant similar to camphor. SYN: absinthol, tanacetol, tanacetone, thujol, thuyol, thuyone.

thulium (Tm) (thoo′le-um)
A metallic element of the lanthanide series, atomic no. 69, atomic wt. l68.93421. [L. Thule, the earliest name for Scandinavia]

thumb (thumb) [TA]
The first digit on the radial side of the hand. SYN: pollex [TA] , digitus (manus) primus&star, first finger. [A.S. thuma] bifid t. a congenital malformed t. where the distal phalanx is divided. gamekeeper's t. chronic radial subluxation of the metacarpophalangeal joint of the t.. hitchhiker t. malposition of the t., which, as a result of shortness of the first metacarpal, stands at right angles to the radial border of the hand and in the same place as it; a characteristic sign of diastrophic dwarfism. tennis t. tendinitis with calcification in the tendon of the long flexor of the t. (flexor pollicis longus) caused by friction and strain as in tennis playing, but also occurring in other exercises in which the t. is subject to repeated pressure or strain.

thumbprinting (thum′print-ing)
A radiographic sign of intestinal ischemia associated with hematoma formation and edema in the bowel wall; the thickened or edematous tissues encroach on the air- or contrast-filled lumen radiographically.

thumps (thumps)
Spasmodic contractions of the diaphragm, or hiccups, occasionally seen in animals.

thus (thus, thoos)
SYN: olibanum. [L. incense]

thuya (thoo′ya)
SYN: thuja.

thuyol, thuyone (thoo′yol, thoo′yon)
SYN: thujone.

Abbreviation for thymine.

Phillips, U.S. ophthalmologist, *1903. See T. disease.

See thymo-.

thyme (tim)
The dried leaves and flowering tops of Thymus vulgaris (family Labiatae), used as a condiment; it contains a volatile oil (t. oil) and is a source of thymol. [G. thymon, t.] t. oil, oil of t. a volatile oil distilled from the flowering plants of Thymus vulgaris or T. zygis; a flavoring agent.

thymectomy (thi-mek′to-me)
Removal of the thymus gland. [thymus + G. ektome, excision] extended t. t. performed via combined sternotomy and a cervical incision to allow removal of all extraglandular thymic tissue. SYN: maximal t.. maximal t. SYN: extended t.. transcervical t. t. performed via a cervical incision only.

thymelcosis (thi-mel-ko′sis)
Obsolete term for suppuration of the thymus gland. [thymus + G. helkosis, ulceration]

See thymo-.

Mind, soul, emotions. SEE ALSO: thymo- (2) . [G. thymos, the mind or heart as the seat of strong feelings or passion]

thymic (thi′mik)
Relating to the thymus gland.

thymic acid
SYN: thymol. [see thyme]

thymicolymphatic (thi′mi-ko-lim-fat′ik)
Relating to the thymus and the lymphatic system.

thymidine (dThd) (thi′mi-den)
1-(2-Deoxyribosyl)thymine;one of the four major nucleosides in DNA (the others being deoxyadenosine, deoxycytidine, and deoxyguanosine). SYN: deoxythymidine, thymine deoxyribonucleoside. t. phosphorylase phosphorylase that catalyzes the phosphorolysis of t.; i.e., t. and Pi react to form thymine and 2-deoxy-d-ribose 1-phosphate. tritiated t. t. containing the hydrogen α-emitting radionuclide, tritium (3H or hydrogen-3); used as a marker to measure and localize by radioautography the synthesis of DNA, into which it is incorporated.

thymidine 5′-diphosphate (dTDP)
Thymidine esterified at its 5′ position with diphosphoric acid.

thymidine 5′-monophosphate (dTMP)
SYN: thymidylic acid.

thymidine 5′-triphosphate (dTTP)
Thymidine esterified at its 5′ position with triphosphoric acid; the immediate precursor of thymidylic acid in DNA.

thymidylate synthase (thi-mi-dil′at)
An enzyme catalyzing conversion of deoxyuridine 5′-monophosphate to thymidine 5′-monophosphate, the methyl group coming from N5,N10-methylenetetrahydrofolate.

thymidylic acid (thi′mi-dil′ik)
A major constituent of DNA. SYN: thymidine 5′-monophosphate, thymine nucleotide.

thymin (thi′min)
See thymopoietin.

thymine (Thy) (thi′men, -min)
5-Methyluracil;a constituent of thymidylic acid and DNA; elevated in hyperuracil thyminuria. t. deoxyribonucleoside SYN: thymidine. t. deoxyribonucleotide SYN: deoxythymidylic acid. t. nucleotide SYN: thymidylic acid.

thyminuria (thi-men-oor′e-a)
See hyperuracil t..

thymitis (thi-mi′tis)
Inflammation of the thymus gland.

thymo-, thym-, thymi-
1. The thymus. [G. thymos] 2. Mind, soul, emotions. [G. thymos, the mind or heart as the seat of strong feelings or passions] 3. Wart, warty. [G. thymos, thymion]

thymocyte (thi′mo-sit)
A cell that develops in the thymus, seemingly from a stem cell of bone marrow and of fetal liver, and is the precursor of the thymus-derived lymphocyte (T lymphocyte) that effects cell-mediated (delayed type) sensitivity. [thymus + G. kytos, cell]

thymogenic (thi-mo-jen′ik)
Of affective origin. [G. thymos, mind, + genesis, origin]

thymokinetic (thi′mo-ki-net′ik)
Activating the thymus gland. [thymus + G. kinesis, movement]

thymol (thi′mol)
A phenol present in the volatile oil of Thymus vulgaris (thyme), Monarda punctata (horsemint), and other volatile oils; used externally and internally as an antiseptic, as a deodorizer of offensive discharges, and as a specific for ancylostomiasis. SYN: thyme camphor, thymic acid. t. blue [C.I. 52025] a dye used as an acid-base indicator, with a pK value at 1.7 and another at 8.9; red at pH values below 1.2, yellow between 2.8 and 8.0, and blue above 9.6. t. iodide a dry powder antiseptic; has been used as a substitute for iodoform in skin diseases, wounds, ulcers, purulent rhinitis, otitis, etc.

thymoma (thi-mo′ma)
A neoplasm in the anterior mediastinum, originating from thymic tissue, usually benign, and frequently encapsulated; occasionally invasive, but metastases are rare; histologically, consists of any type of thymic epithelial cell as well as lymphocytes that are usually abundant. Malignant lymphoma that involves the thymus, e.g., Hodgkin disease, should not be regarded as t.. [thymus + G. -oma, tumor]

thymonuclease (thi-mo-noo′kle-as)
SYN: deoxyribonuclease I.

thymopoietin (thi′mo-poy-e′tin)
Formerly called thymin; a polypeptide hormone that induces differentiation of lymphocytes to thymocytes. SEE ALSO: thymic lymphopoietic factor.

thymoprival, thymoprivic, thymoprivous (thi-mo-pri′val, -priv′ik, -pri′vus)
Relating to or marked by premature atrophy or removal of the thymus. [thymus + L. privus, deprived of]

thymosin (thi′mo-sin)
A polypeptide hormone that restores T cell function in a thymectomized animal. SEE ALSO: thymic lymphopoietic factor.

thymoxamine (thi-mok′sa-men)
SYN: moxisylyte.

thymus, pl .thymithymuses (thi′mus, thi′mi) [TA]
[NA] A primary lymphoid organ, located in the superior mediastinum and lower part of the neck, that is necessary in early life for the normal development of immunologic function. It reaches its greatest relative weight shortly after birth and its greatest absolute weight at puberty; it then begins to involute, and much of the lymphoid tissue is replaced by fat. The t. consists of two irregularly shaped parts united by a connective tissue capsule. Each part is partially subdivided by connective tissue septa into lobules, 0.5 to 2 mm in diameter, which consist of an inner medullary portion, continuous with the medullae of adjacent lobules, and an outer cortical portion. It is supplied by the inferior thyroid and internal thoracic arteries, and its nerves are derived from the vagus and sympathetic nerves. SYN: t. gland. [G. thymos, excrescence, sweetbread]

See thyro-.

See thyro-.

thyro-, thyr-
The thyroid gland. [see thyroid]

thyroacetic acid (thi′ro-a-se′tik)
A degradation product of thyronine (alanine side chain reduced to acetic acid), itself a degradation product (or precursor) of thyroxine.

thyroadenitis (thi′ro-ad-e-ni′tis)
SYN: thyroiditis. [thyro- + G. aden, gland, + -itis, inflammation]

thyroaplasia (thi′ro-a-pla′ze-a)
Anomalies observed in individuals with congenital defects of the thyroid gland and deficiency of its secretion. [thyro- + G. a- priv. + plasis, a molding]

thyroarytenoid (thi′ro-ar′i-te′noyd)
Relating to the thyroid and arytenoid cartilages. See t. (muscle).

thyrocalcitonin (thi′ro-kal-si-to′nin)
SYN: calcitonin.

thyrocardiac (thi-ro-kar′de-ak)
Affecting the heart as a result of hypo- or hyperthyroidism.

thyrocele (thi′ro-sel)
A tumor of the thyroid gland, such as a goiter. [thyro- + G. kele, tumor]

thyrocervical (thi′ro-ser′vi-kal)
Relating to the thyroid gland and the neck, denoting an arterial trunk.

thyrocolloid (thi-ro-kol′oyd)
A colloid substance in the thyroid gland.

thyroepiglottic (thi′ro-ep-i-glot′ik)
Relating to the thyroid cartilage and the epiglottis.

thyrofissure (thi′ro-fish′er)
SYN: laryngofissure.

thyrogenic, thyrogenous (thi-ro-jen′ik, -roj′e-nus)
Of thyroid gland origin. [thyroid + G. -gen, producing]

thyroglobulin (thi-ro-glob′u-lin)
1. A protein that contains precursors of thyroid hormone usually stored in the colloid within the thyroid follicles; biosynthesis of thyroid hormone entails iodination of the l-tyrosyl moieties of this protein and the combination of two iodotyrosines to form thyroxine, the fully iodinated thyronine; secretion of thyroid hormone requires proteolytic degradation of t., with the attendant release of free hormone; a defect in t. metabolism will lead to hypothyroidism. SYN: iodoglobulin, thyroprotein (1) . 2. A substance obtained by the fractionation of thyroid glands from the hog, Sus scrofa, containing not less than 0.7% of total iodine; used as a thyroid hormone in the treatment of hypothyroidism.


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