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Medical Dictionary


titration (ti-tra′shun)
Volumetric analysis by means of the addition of definite amounts of a test solution to a solution of the substance being assayed. [Fr. titre, standard] colorimetric t. a t. in which the end point is marked by a color change. formol t. a method of titrating the amino groups of amino acids, by adding formaldehyde to the neutral solution; the formaldehyde reacts with the NH3+ group, liberating an equivalent quantity of H+, which may then be estimated by t. with NaOH. potentiometric t. a t. during which the pH is continually measured with some value of the pH serving as end point.

titubation (tit-u-ba′shun)
1. A staggering or stumbling in trying to walk. 2. A tremor or shaking of the head, of cerebellar origin. [L. titubo, pp. -atus, to stagger]

Guido, Italian physician, 1853–1932. See T. stain.

Symbol for thallium.

Abbreviation for thallium-201.

Abbreviation for thin-layer chromatography; total lung capacity.

Abbreviation for thin-layer electrophoresis.

Abbreviation for threshold limit value.

Abbreviation for transcendental meditation.

Symbol for thulium; transport maximum or tubular maximum.

Abbreviation for temporomandibular joint dysfunction.

Colloquial abbreviation for temporomandibular joint dysfunction.

SYN: M-mode.

Abbreviation for ribothymidylic acid; trimethoprim; sometimes for deoxyribothymidylic acid.

SYN: Ureaplasma.

Abbreviation for ocular tension.

Abbreviation for tumor necrosis factor.

Acronym for Tumor-Node-Metastasis. See T. staging.

An angiogenesis inhibitor used in the treatment of cancer to reduce blood vessel formation in tumors.

Abbreviation for trinitrotoluene.

tobacco (to-bak′o)
A South American herb, Nicotiana tabacum, that has large ovate to lanceolate leaves and terminal clusters of tubular white or pink flowers. T. leaves contain 2–8% of nicotine and are the source of smoking and chewing t.. T. smoke contains nicotine, carbon monoxide (4%), nitric oxide, and numerous aromatic hydrocarbons and other substances known to be carcinogens, including benzo[a]pyrene, β-naphthylamine, and nitrosamines.Cigarette smoking is the leading preventable cause of disease and death in the U.S., being responsible for approximately 434,000 deaths (20% of all deaths) each year. Smoking 2 packages of cigarettes a day reduces life span by 8.3 years. Smoking t. in any form (cigarettes, cigars, pipe) is a strong independent risk factor for atherosclerosis, acute myocardial infarction, unstable angina, stroke, and sudden death. It is responsible for 45% of all deaths due to coronary artery disease in men under 65 and more than 50% of all strokes in both sexes before age 65. Smoking lowers HDL cholesterol and raises LDL and VLDL cholesterol, and increases the risk of intermittent claudication and aortic aneurysm. It may cause as much as a 30-fold increase in the risk of thromboembolic disease in women taking oral contraceptives. Smoking is responsible for 100,000 deaths each year due to lung cancer, and markedly increases the risk of other cancers, particularly those of the oral cavity, larynx, esophagus, kidney, bladder, uterine cervix, and pancreas. Cigarette smoking is the principal cause of chronic bronchitis and emphysema. Passive smoking (inhalation by nonsmokers of second-hand or sidestream smoke) causes 53,000 deaths annually, 37,000 of them due to coronary artery disease. Maternal smoking during pregnancy is associated with increased risk of miscarriage, stillbirth, and low birth weight. Children of smokers are at increased risk of sudden infant death syndrome and meningococcal meningitis. Use of smokeless t. (chewing t., snuff) greatly increases the risk of cancer and premalignant lesions of the oral cavity. Nicotine use is powerfully addictive, leading to habituation, tolerance, and dependency. In the U.S., 90% of smokers become habituated to t. before age 21; 3000 children begin smoking each day. The likelihood of becoming and remaining a smoker increases in inverse proportion to the number of years of education completed. Quitting smoking decreases the risk of death from all causes by 30%. Effective strategies for smoking cessation include behavior modification therapy, nicotine replacement (gum, skin patches, inhaler), hypnosis, and drug therapy (bupropion), but the relapse rate 3 months after smoking cessation is 60%. wild t. SYN: lobelia.

tobramycin (to-bra-mi′sin)
An aminoglycoside antibiotic produced by Streptomyces tenebrarius, having bactericidal effects and used mainly in the treatment of Pseudomonas infections.

tocainide hydrochloride (to-ka′nid)
An oral antiarrhythmic agent, similar in action to lidocaine, used in the treatment of ventricular arrhythmias.

Childbirth. [G. tokos, birth]

tocochromanol-3 (to′ko-kro′ma-nol)
An α-tocotrienol. See tocotrienol.

tocodynagraph (to-ko-di′na-graf, tok-o-)
A recording of the force of uterine contractions. SYN: tocograph. [toco- + G. dynamis, force, + graphe, a writing]

tocodynamometer (to′ko-di-na-mom′e-ter, tok′o-)
An instrument for measuring the force of uterine contractions. SYN: tocometer. [toco- + G. dynamis, force, + metron, measure]

tocograph (to′ko-graf)
SYN: tocodynagraph.

tocography (to-kog′ra-fe)
The process of recording uterine contractions. [toco- + G. grapho, to write]

tocol (to′kol)
Fundamental unit of the tocopherols; 6-phytylhydroquinone is in equilibrium with, in the chromanol form, 2-methyl-2-(4,8,12-trimethyltridecyl)chroman-6-ol.

tocology (to-kol′o-je)
SYN: obstetrics. [toco- + G. logos, study]

tocolytic (to-ko-lit′ik)
Denoting any pharmacologic agent used to arrest uterine contractions; often used in an attempt to arrest premature labor contractions, e.g., ritodrine or terbutaline. [G. tokos, childbirth, labor, + lysis, loosening]

tocometer (to-kom′e-ter)
SYN: tocodynamometer.

tocopherol (T) (to-kof′er-ol)
1. Name given to vitamin E by its discoverer, but now a generic term for vitamin E and compounds chemically related to it, with or without biological activity; similar in chemical structure and properties to vitamins K and coenzyme Q. 2. A methylated tocol or methylated tocotrienol. mixed tocopherols concentrate a source of vitamin E, obtained by vacuum distillation of edible vegetable oils or their by-products.

tocopherolquinone (TQ) (to-kof′er-ol-kwi′non)
An oxidized tocopherol, formed from the isomeric 2-methyl-2-phytyl-6-chromenol with methyl groups in one or more of positions 5, 7, and 8, by migration of an H atom from 6-OH to C-4, which yields a 1,4-benzoquinone. Abbreviated TQ and preceded by α-, β-, etc., as in the tocopherols, to indicate degree of methylation. SYN: tocopherylquinone.

tocopherylquinone (to-kof′er-il-kwi′non)
SYN: tocopherolquinone.

tocophobia (to′ko-fo′be-a, tok′o-)
Morbid dread of childbirth. [toco- + G. phobos, fear]

tocoquinone (to-ko-kwi′non)
Class name for the 2,3,5-trimethyl-6-multiprenyl-1,4-benzoquinones.

tocotrienol (to-ko-tri′en-ol)
A tocol with three double bonds in the side chain, i.e., with three additional double bonds in the phytyl chain. The natural products carry methyls at one or more of positions 5, 7, and 8 of the chromanol and are thus identical, except for the unsaturation in the phytyl-like side chain, to the tocopherols; also analogous is the cyclization to form a chromanol derivative and oxidation to form the tocotrienolquinones (or chromenols). Abbreviated T-n (hydroquinone form) or TQ-n (quinone form) and preceded by α-, β-, etc., as in the tocopherols, to indicate degree of methylation (the n indicates the number of intact isoprene or prenyl units remaining in the chromanol or chromenol form). T. terminology is used to indicate relationships to tocols and tocoenols (vitamin E-like), the chromanol terminology to indicate relationship to the isoprenoidal compounds of the vitamin K and coenzyme Q series.

tocotrienolquinone (to-ko-tri′en-ol-kwi′non)
A tocotrienol in which the hydroquinone has been oxidized to a quinone (the chromanol has become a chromenol); the tocotrienolquinones carry α, β, γ, and δ prefixes in accordance with the degree of methylation, as do the tocotrienols.

Abbreviation for triorthocresyl phosphate.

David, British surgeon, 1794–1856. See T. muscle.

Francesco, Italian anatomist, 1839–1918. See T. tendon.

Robert B., English physician, 1809–1860. See T. paralysis, T. postepileptic paralysis.

toe (to) [TA]
One of the digits of the feet. SYN: digitus pedis [TA] , digits of foot&star. [A.S. ta] fourth t. [IV] [TA] fourth digit of foot. SYN: digitus (pedis) quartus [IV] [TA] . great t. I [TA] the first digit of the foot. SYN: hallux [TA] , digitus pedis primus I&star, hallex, hallus, pollex pedis, primary digit of foot. hammer t. permanent flexion at the midphalangeal joint of one or more of the toes. little t. [V] [TA] fifth digit of the foot. SYN: digitus (pedis) minimus [V] [TA] , digitus (pedis) quintus [V]&star. Morton t. a particular form of metatarsalgia caused by enlargement of the digital nerve. Cf.:Morton syndrome. painful t. SYN: hallux dolorosus. second t. [II] [TA] second digit of foot. SYN: digitus (pedis) secundus [II] [TA] . stiff t. SYN: hallux rigidus. third t. [III] [TA] third digit of foot. SYN: digitus (pedis) tertius [III] [TA] . webbed toes syndactyly involving the toes.

toe-drop (to′drop)
Inability to dorsiflex the toes, usually due to paralysis of the toe extensor muscles.

toenail (to′nal)
See nail. ingrowing t. SYN: ingrown nail.

tofenacin hydrochloride (to-fen′a-sin)
An anticholinergic drug.

Togaviridae (to-ga-vir′i-de)
A family of viruses that includes two genera: Alphavirus, which includes eastern equine encephalitis, western equine encephalitis, and Venezuelan equine encephalitis virus, and Rubivirus, the rubella virus. Virions are 70 nm in diameter, enveloped, and ether-sensitive; the capsid is of icosahedral symmetry, containing single-stranded positive sense RNA.

togavirus (to′ga-vi′rus)
Any virus of the family Togaviridae. [L. toga, garment covering, + virus]

toilet (toy-let′)
1. Cleansing of the obstetric patient after childbirth. 2. Cleansing of the surface of a wound after an operation preparatory to the application of the dressing. 3. In dentistry, cavity debridement, the final step before placing a restoration in a tooth whereby the cavity is cleaned and all debris is removed. [Fr. toilette] pulmonary t. attempts to clear mucus and secretions from the trachea and bronchial tree by deep breathing, insentive spiratomy, postural drainage, and percussion.

J., French histologist, 1858–1950. See T. stain.

Cyril, U.S. pathologist, *1930. See T. cell.

See toco-.

tolazamide (to-laz′a-mid)
An oral hypoglycemic agent similar in use to tolbutamide.

tolazoline hydrochloride (to-laz′o-len)
An adrenergic α-receptor blocking agent used to augment blood flow in peripheral vascular disorders.

tolbutamide (tol-bu′ta-mid)
An orally active hypoglycemic agent used in the management of adult-onset diabetes mellitus; it appears to stimulate the synthesis and release of endogenous insulin from functional islets; available as t. sodium for injection.

tolcyclamide (tol-si′kla-mid)
SYN: glycyclamide.

Karl, Austrian anatomist, 1840–1920. See T. fascia, T. membrane, white line of T..

tolerance (tol′er-ans)
1. The ability to endure or be less responsive to a stimulus, especially over a period of continued exposure. 2. The power of resisting the action of a poison or of taking a drug continuously or in large doses without injurious effects. [L. tolero, pp. -atus, to endure] acoustic t. the maximum sound pressure level that can be experienced without producing pain or permanent hearing threshold shift in a normal individual. cross t. the resistance to one or several effects of a compound as a result of t. developed to a pharmacologically similar compound. frustration t. the level of an individual's ability to withstand frustration without developing inadequate modes of response, such as “going to pieces” emotionally. high dose t. the induction of t. by exposure to high doses of antigen. immunologic t. lack of immune response to antigen. Theories of t. induction include clonal deletion and clonal anergy. In clonal deletion, the actual clone of cells is eliminated whereas in clonal anergy the cells are present but nonfunctional. SYN: immunotolerance, nonresponder t.. immunologic high dose t. induction of t. by exposure to large amounts of protein antigens. impaired glucose t. excessive levels of blood glucose developing after a carbohydrate-rich meal or test dosage of glucose (usually 75 g). Not necessarily diagnostic of diabetes mellitus. individual t. t. to a drug that the person has never received before. nonresponder t. SYN: immunologic t.. pain t. the greatest intensity of painful stimulation that an individual is able to tolerate. species t. the insensitivity to a particular drug exhibited by a particular species. split t. reaction to one (or more) antigen on a cell surface but no reaction to others. SYN: immune deviation. vibration t. the maximum vibratory or oscillatory movements that an individual can experience and bear without pain; the limit of t. is a function of amplitude and frequency of the vibration and varies with the direction of application.

tolerant (tol′er-ant)
Having the property of tolerance.

tolerize (tol′er-iz)
To induce tolerance.

tolerogen (tol′er-o-jen)
A substance that produces immunological tolerance.

tolerogenic (tol′er-o-jen′ik)
Producing immunologic tolerance.

tolhexamide (tol-hek′sa-mid)
SYN: glycyclamide.

tolmetin (tol′met-in)
An anti-inflammatory drug used in the treatment of rheumatoid arthritis.

tolnaftate (tol-naf′tat)
A topical antifungal agent.

tolonium chloride (to-lo′ne-um)
The medicinal grade of toluidine blue O, used as an antiheparin compound.

Eduardo, 20th century Spanish neurosurgeon. See T.-Hunt syndrome.

tolpropamine (tol-pro′pa-men)
A topical antipruritic agent.


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