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Medical Dictionary


catalyst (kat′a-list)
A substance that accelerates a chemical reaction but is not consumed or changed permanently thereby. SYN: catalyzer. inorganic c. a c. such as a finely divided metal (Pt, Rh), carbon, etc. negative c. a c. that retards a reaction. organic c. 1. SYN: enzyme, ribozyme. 2. a c. that is an organic molecule. Raney c. SYN: Raney Nickel.

catalytic (kat-a-lit′ik)
Relating to or effecting catalysis.

catalyze (kat′a-liz)
To act as a catalyst.

catalyzer (kat′a-liz-er)
SYN: catalyst.

catamnesis (kat-am-ne′sis)
The medical history of a patient after an illness; the follow-up history. [cata- + G mneme, memory]

catamnestic (kat-am-nes′tik)
Related to catamnesis.

catapasm (kat′a-pazm)
A dusting powder applied to raw surfaces or ulcers. [G. katapasma, a powder; katapasso, to sprinkle over]

cataphoresis (kat′a-fo-re′sis)
Movement of positively charged particles (cations) in a solution or suspension toward the cathode in electrophoresis. Cf.:anaphoresis. [cata- + G. phoresis, a being carried]

cataphoretic (kat′a-fo-ret′ik)
Relating to cataphoresis.

cataplasia, cataplasis (kat-a-pla′se-a, -pla′sis)
A degenerative change in cells or tissues that is the reverse of the constructive or developmental change; a return to an earlier or embryonic stage. SYN: retrograde metamorphosis (1) , retrogression, retromorphosis. [cata- + G. plasis, a molding]

cataplasm (kat′a-plazm)
SYN: poultice. [G. kataplasma, poultice, fr. kataplasso, to spread over]

cataplectic (kat-a-plek′tik)
1. Developing suddenly. 2. Pertaining to cataplexy.

cataplexy (kat′a-plek-se)
A transient attack of extreme generalized weakness, often precipitated by an emotional response, such as surprise, fear, or anger; one component of the narcolepsy quadrad. [cata- + G. plexis, a blow, stroke]

cataract (kat′a-rakt)
Complete or partial opacity of the ocular lens. SYN: cataracta. [L. cataracta, fr. G. katarrhaktes, a downrushing, a waterfall, fr. katarrhegnymi, to break down, rush down] anular c. congenital c. in which a central white membrane replaces the nucleus. SYN: disk-shaped c., life-belt c., umbilicated c.. atopic c. a c. associated with atopic dermatitis. axial c. a lenticular opacity in the visual axis of the lens. black c. a c. in which the lens is hardened and a dark brown. In the 19th century, German black c. meant gutta serena (q.v.). SYN: cataracta brunescens, cataracta nigra. blue c. coronary c. of bluish color. SYN: cataracta cerulea. capsular c. a c. in which the opacity affects the capsule only. capsulolenticular c. a c. in which both the lens and its capsule are involved. SEE ALSO: membranous c.. central c. congenital c. limited to the embryonic nucleus. cerulean c. [MIM*115660] a congenetal c. with bluish coloring and radial lesions; autosomal dominant inheritance in some cases. complete c. SYN: mature c.. complicated c. SYN: secondary c. (1) . concussion c. traumatic c. occurring with or without a hole in the lens capsule. congenital c. c., usually bilateral, present at birth. It occurs as an autosomal recessive condition in calves of the Jersey breed. In humans approximately 25% of bilateral congenital cataracts are autosomal dominant [MIM*116200, *116700]; X-linked forms also exist [MIM*302200, *302300]. Most congenital cataracts are sporadic, some the result of prematurity, intrauterine infection, drug-related toxicity, injury, or chromosomal or metabolic disorders. copper c. SYN: chalcosis lentis. coralliform c. congenital c. with round or elongated processes radiating from the center of the lens. coronary c. peripheral cortical developmental c. occurring just after puberty; transmitted as a hereditary dominant characteristic. cortical c. a c. in which the opacity affects the cortex of the lens. SYN: peripheral c.. crystalline c. a hereditary c. with a coralliform or needle-shaped accumulation of crystals in the axial region of an otherwise clear lens. cuneiform c. cortical c. in which the opacities radiate from the periphery like spokes of a wheel. cupuliform c. a common form of senile c. often confined to a region just within the posterior capsule. SYN: saucer-shaped c.. dendritic c. a congenital sutural c. with complicated branching. diabetic c. c. occurring in insulin-dependent diabetes mellitus. disk-shaped c. SYN: anular c.. electric c. a c. caused by contact with a high-power electric current, or a lightning bolt. SYN: cataracta electrica. embryonic c. [MIM*115650] a congenital c. situated near the anterior Y suture of the fetal lens nucleus. Inheritance heterogeneous. embryopathic c. congenital c. as a result of intrauterine infection, e.g., rubella. fibroid c., fibrinous c. a sclerotic hardening of the capsule of the lens, following exudative iridocyclitis. floriform c. a congenital c. with opacities arranged like the petals of a flower. furnacemen's c. SYN: infrared c.. fusiform c. SYN: spindle c.. galactose c. a neonatal c. associated with intralenticular accumulation of galactose alcohol. See galactosemia. glassworker's c. SYN: infrared c.. glaucomatous c. a nuclear opacity usually seen in absolute glaucoma. gray c. a c. of gray color, usually seen in senile, mature, or cortical c.. hard c. SYN: nuclear c.. hook-shaped c. congenital c. with hooklike figures between the fetal and embryonic nuclei. hypermature c. a c. in which the lens cortex becomes liquid, with the nucleus gravitating within the capsule (Morgagni c.). SYN: overripe c.. hypocalcemic c. a c. occurring with low serum calcium. immature c. a stage of partial lens opacification. infantile c. a c. affecting a very young child. infrared c. a c. secondary to absorption of heat by the lens, or by transmission from the adjacent iris. SYN: furnacemen's c., glassworker's c.. intumescent c. a c. swollen because of fluid absorption. juvenile c. a soft c. occurring in a child or young adult. lamellar c. a c. in which the opacity is limited to the cortex. SYN: zonular c.. life-belt c. SYN: anular c.. mature c. a c. in which both the nucleus and cortex are opaque. SYN: complete c., ripe c.. membranous c. a secondary c. composed of the remains of the thickened capsule and degenerated lens fibers. Morgagni c. a hypermature c. in which the nucleus gravitates within the capsule. SYN: sedimentary c.. myotonic c. c. occurring in myotonic dystrophy. nuclear c. a c. involving the nucleus. SYN: hard c.. overripe c. SYN: hypermature c.. perinuclear c. a lamellar c. in which the nucleus is clear but is surrounded by a ring of opacity. peripheral c. SYN: cortical c.. pisciform c. a hereditary c. with bilateral fish-shaped opacities in the axial region of the fetal nucleus. polar c. a capsular c. limited to an area of the anterior or posterior pole of the lens. posterior subcapsular c. a c. involving the cortex at the posterior pole of the lens. progressive c. a c. in which the opacification process progresses to involve the entire lens. punctate c. an incomplete c. in which there are opaque dots scattered through the lens. pyramidal c. a cone-shaped, anterior polar c.. radiation c. a c. caused by excessive or prolonged exposure to ultraviolet rays, x-rays, radium, gamma rays, heat, or radioactive isotopes. reduplicated c. a type of congenital c. with opacities situated at various levels in the lens. ripe c. SYN: mature c.. rubella c. embryopathic c. secondary to intrauterine rubella infection. saucer-shaped c. SYN: cupuliform c.. secondary c. 1. a c. that accompanies or follows some other eye disease such as uveitis; SYN: complicated c.. 2. a c. occurring in the retained lens or capsule after a c. extraction. sedimentary c. SYN: Morgagni c.. senile c. a c. occurring spontaneously in the elderly; mainly a cuneiform c., nuclear c., or posterior subcapsular c., alone or in combination. siderotic c. a c. resulting from deposition of iron from an iron-containing intraocular foreign body. soft c. an advanced or mature c. in which the nucleus is not well developed. spindle c. a c. in which the opacity is fusiform, extending from one pole to the other. SYN: fusiform c.. stationary c. a c. that does not progress. stellate c. congenital c. with lens opacities radiating toward the periphery, with subcapsular and cortical changes. subcapsular c. a c. in which the opacities are concentrated beneath the capsule. sugar c. any c. associated with intralenticular accumulation of pentose or hexose alcohols. sunflower c. SYN: chalcosis lentis. sutural c. a congenital type of c. with opacities along the Y sutures of the fetal lens nucleus; usually does not affect vision. tetany c. a c. that develops in hypocalcemia. total c. a c. involving the entire lens. toxic c. a c. caused by drugs or chemicals. traumatic c. a c. caused by contusion, rupture, or a foreign body. umbilicated c. SYN: anular c.. vascular c. congenital c. in which the degenerated lens is replaced with mesodermal tissue. SYN: cataracta adiposa, cataracta fibrosa. zonular c. SYN: lamellar c..

cataracta (kat-a-rak′ta)
SYN: cataract. [L.] c. adiposa SYN: vascular cataract. c. brunescens SYN: black cataract. c. cerulea SYN: blue cataract. c. electrica SYN: electric cataract. c. fibrosa SYN: vascular cataract. c. nigra SYN: black cataract.

cataractogenesis (kat′a-rak-to-jen′e-sis)
The process of cataract formation. [cataract + G. genesis, production]

cataractogenic (kat′a-rak-to-jen′ik)

cataractous (kat-a-rak′tus)
Relating to a cataract.

cataria (ka-ta′re-a)
The dried flowering tops of Nepeta c. (family Labiatae); an emmenagogue and antispasmodic; also reported to produce psychic effects. SYN: catnep, catnip. [L. cattus, male cat (post-class)]

catarrh (ka-tahr′)
Inflammation of a mucous membrane with increased flow of mucus or exudate. [G. katarrheo, to flow down] nasal c. SYN: rhinitis. vernal c. SYN: vernal conjunctivitis.

catarrhal (ka-tah′ral)
Relating to or affected with catarrh.

catastalsis (kat-a-stal′sis)
A contraction wave resembling ordinary peristalsis but not preceded by a zone of inhibition. [G. kata-stello, to put in order, check]

catastaltic (kat-a-stal′tik)
Inhibitory, restricting, or restraining. [cata- + G. staltos, contracted, fr. stello, to contract]

catastasis (ka-tas′ta-sis)
1. A condition or state. 2. Restoration to a normal condition or a normal place. [G.]

catatonia (kat-a-to′ne-a)
A syndrome of psychomotor disturbances characterized by periods of physical rigidity, negativism, or stupor; may occur in schizophrenia, mood disorders, or organic mental disorders. [G. katatonos, stretching down, depressed, fr. kata, down, + tonos, tone] excited c. c. in which the patient is excited, impulsive, hyperactive, and combative. periodic c. regularly reappearing phases of catatonic excitement. stuporous c. c. in which the patient is subdued, mute, and negativistic, accompanied by varying combinations of staring, rigidity, and cataplexy.

catatonic, catatoniac (kat-a-ton′ik, -to′ne-ak)
Relating to, or characterized by, catatonia.

catatrichy (kat′a-tri-ke) [MIM*116850]
Presence of a forelock of hair that is separate or different in appearance; may be inherited as an autosomal dominant. See Waardenburg syndrome. [cata- + G. thrix, hair]

catatricrotic (kat′a-tri-krot′ik)
Denoting a pulse tracing with three minor elevations interrupting the downstroke.

catatricrotism (kat-a-tri′kro-tizm)
A condition of the pulse marked by three minor expansions of the artery following the main beat, producing three secondary upward waves on the downstroke of the pulse tracing. [cata- + G. tri-, three, + krotos, beat]

catechase (kat′e-kas)
SYN: catechol 1,2-dioxygenase.

catechin (kat′e-kin)
Derived from catechu, and used as an astringent in diarrhea and as a stain. SYN: catechinic acid, catechuic acid, cyanidol.

catechinic acid (kat-e-kin′ik)
SYN: catechin.

catechol (kat′e-kol)
1. SYN: pyrocatechol. 2. Term loosely used for catechin, which contains an o-c. moiety, and as the root of catecholamines, which are pyrocatechol derivatives. c.-O-methyltransferase a transferase that catalyzes the methylation of the hydroxyl group at the 3 position of the aromatic ring of catechols, including the catecholamines norepinephrine and epinephrine (thus, converting to normetanephrine and metanephrine, respectively), the methyl group coming from S-adenosyl-l-methionine. An important step in the catabolism of the catecholamines. c. oxidase an enzyme oxidizing catechols to 1,2-benzoquinones, with O2. SEE ALSO: monophenol monooxygenase. SYN: diphenol oxidase, o-diphenolase. c. oxidase (dimerizing) an enzyme oxidizing a c., with O2, to a diphenylenedioxide quinone ( e.g., 4 c. + 3O2 → 2 dibenzo[1,4]-2,3-dione + 6H2O).

catecholamines (kat-e-kol′a-menz)
Pyrocatechols with an alkylamine side chain; examples of biochemical interest are epinephrine, norepinephrine, and l-dopa. C. are major elements in responses to stress.

catechol 1,2-dioxygenase
An oxidoreductase catalyzing oxidation of pyrocatechol, with O2, to cis-cis-muconate. SYN: catechase, pyrocatechase.

catechol 2,3-dioxygenase
An oxidoreductase oxidizing catechol, with O2, to 2-hydroxymuconate semialdehyde. SYN: metapyrocatechase.

catechuic acid (kat-e-choo′ik, -koo′ik)
SYN: catechin.

catechu nigrum
Black catechu, an extract of the heart wood of Acacia catechu (family Leguminosae), used as an astringent in diarrhea. SYN: cutch.

catelectrotonus (kat′e-lek-trot′o-nus)
The changes in excitability and conductivity in a nerve or muscle in the neighborhood of the cathode during the passage of a constant electric current. [cathode + electrotonus]

catenate (kat′en-at)
To connect in a series of links like a chain; for example, two rings of mitochondrial DNA are often catenated. [L. catenatus, chained together, fr. catena, chain]

catenating (kat′en-at-ing)
Occurring in a chain or series. [L. catenatus, chained]

catenin (ka-ten′in)
Cytoplasmic molecule that serves as a link between cadherins and the cytoskeleton of cells, allowing the formation of adherent junctions. There are two types: β-c., which is linked to the cadherin itself and α-c., which associates with actin microfilaments. [L. catena, chain, + -in]

catenoid (kat′e-noyd)
1. Like a chain, such as a chain of fungus spores or a colony of protozoa in which the individuals are joined end to end. SYN: catenulate. 2. Surface of net zero curvature generated by the rotation of a catenary (curve of repose of a suspended chain); the interventricular septum of the heart in idiopathic hypertrophic subaortic stenosis resembles a c., which makes it ineffective in increasing intracavity pressure or in reducing its volume as defined in Laplace law. [L. catena, chain, + G. eidos, resemblance]

catenulate (ka-ten′u-lat)
SYN: catenoid (1) .

caterpillar (kat′er-pil′er)
The wormlike larval stage of a butterfly or a moth. [M.E. catirpeller, fr. O.Fr. cate, cat, + pelose, hairy] dermatitis-causing c.. one of several species whose hairs can cause an allergic dermatitis; the saddleback c. (Sabine stimulea) and the brown-tail moth (Euproctis chrysorrhoea) are common examples. saddleback c. Sabine stimulea, a cause of c. dermatitis. stinging c. c. with urticarious hairs or spines that cause allergic dermatitis, e.g., the Io moth and the puss c..

catgut (kat′gut)
An absorbable surgical suture material made from the collagenous fibers of the submucosa of certain animals (usally from sheep or cows); misnamed c.. [probably from kit, a small violin, through confusion with kit, a small cat] chromic c. c. impregnated with chromium salts to prolong its tensile strength and retard its absorption. silverized c. c. prepared by immersion in a 2% solution of colloidal silver for 1 week and then in 95% alcohol for 15 to 30 minutes.

Catha edulis (kath′a ed′u-lis)
A plant of Ethiopia and Arabia (family Celastraceae), cultivated for use as a stimulant; khat (the fresh leaves and twigs) is chewed or used in the preparation of a beverage; the active principle is pharmacologically related to the amphetamines, probably d-norisoephedrine. [Ar. khat]

Catharanthus alkaloids (kath-ar-ran′thus)
SYN: Vinca alkaloids, under alkaloid.

catharsis (ka-thar′sis)
1. SYN: purgation. 2. The release or discharge of emotional tension or anxiety by psychoanalytically guided emotional reliving of past, especially repressed, events. SYN: psychocatharsis. [G. katharsis, purification, fr. katharos, pure]

cathartic (ka-thar′tik)
1. Relating to catharsis. 2. An agent having purgative action.

cathectic (ka-thek′tik)
Pertaining to cathexis.

cathemoglobin (ka-them-o-glo′bin)
An artificial derivative of hemoglobin in which the globin is denatured and the iron oxidized.

cathepsin (ka-thep′sin)
One of a number of intracellular proteinases and peptidases (all endopeptidases) of animal tissues of varying specificities.

catheter (kath′e-ter)
1. A tubular instrument to allow passage of fluid from or into a body cavity or blood vessel. SEE ALSO: line (4) . 2. Especially a c. designed to be passed through the urethra into the bladder to drain it of retained urine. [G. katheter, fr. kathiemi, to send down] acorn-tipped c. a c. used in ureteropyelography to occlude the ureteral orifice and prevent backflow from the ureter during and following the injection of an opaque medium. angiography c. a thin-walled tube suitable for percutaneous insertion and power injection of contrast media for radiography; c. diameter is measured on the French scale. See Seldinger technique. balloon c. a c. used in arterial embolectomy or to float into the pulmonary artery. balloon-tip c. a single- or double-lumen tube with a balloon at its tip that can be inflated or deflated without removal after installation; the balloon may be inflated to facilitate passage of the tube through a blood vessel (propelled by the bloodstream) or to occlude the vessel in which the tube alone would allow free flow; such catheters are used to enter the pulmonary artery to facilitate hemodynamic measurements. SEE ALSO: Swan-Ganz c.. bicoudate c., c. bicoudé (bi-koo-da′) an elbowed c. with a double bend. [bi + Fr. coudé, bent] Bozeman-Fritsch c. a slightly curved double-channel uterine c. with several openings at the tip. Braasch c. a bulb-tipped c. used for dilation and calibration. SYN: Braasch bulb. Broviac c. a type of long-term central venous c. with an external port for administration of medication. brush c. a ureteral c. with a finely bristled brush tip that is endoscopically passed into the ureter or renal pelvis and by gentle to-and-fro movement brushes cells from the surface of suspected tumors. cardiac c. SYN: intracardiac c.. central venous c. a c. passed through a peripheral or central vein, ending in the superior vena cava or right atrium, for measurement of central venous pressure or for infusion of hyperosmolar solutions. conical c. a c. with a cone-shaped tip designed to dilate the ureter. c. coudé (koo-da′) a c. with an angular bend near the beak; used to rise over prostatic obstruction. SYN: elbowed c., prostatic c.. [Fr. coudé, bent] c. à demeure (a-dem-ër′) an obsolete term for a c. that is retained for a considerable period in the urethra. [Fr. demeurer, to dwell] de Pezzer c. a self-retaining c. with a bulbous extremity. double-channel c. a c. with two lumens, allowing irrigation and aspiration or injection and pressure measurement. SYN: two-way c.. elbowed c. SYN: c. coudé. eustachian c. a c. for the middle ear through the eustachian tube. female c. a short, nearly straight c. for passage into the female urethra. Fogarty embolectomy c. a c. with an inflatable balloon near its tip; used to remove emboli and thrombi from blood vessels or to remove stones from the biliary ducts. Foley c. urethral c. with a retaining balloon. Gouley c. a solid curved steel instrument grooved on its inferior surface so that it can be passed over a guide through a urethral stricture. Hickman c. long-term, central venous indwelling c. with external port(s). indwelling c. a c. left in place in the bladder, usually a balloon c.. intracardiac c. a c. that can be passed into the heart through a vein or artery, to withdraw samples of blood, measure pressures within the heart's chambers or great vessels, and inject contrast media; used mainly in the diagnosis and evaluation of congenital, rheumatic, and coronary artery lesions and to evaluate systolic and diastolic cardiac function. SYN: cardiac c.. Malecot c. a two- or four-winged c.. Nélaton c. a flexible c. of red rubber. olive-tipped c. a ureteral c. with an olive-shaped tip, used to dilate a constricted ureteral orifice; larger sizes are also used for dilating or calibrating urethral strictures. pacing c. a cardiac c. with one or more electrodes at its tip which can be used to artificially pace the heart. Pezzer c. de Pezzer c.. Phillips c. a c. with a filiform guide for the urethra. pigtail c. a c. with a tightly curled end and multiple side holes to reduce the impact of the injectant on the vessel wall or to remain in a chamber or space for drainage. prostatic c. SYN: c. coudé. pulmonary artery c. SYN: Swan-Ganz c.. Robinson c. a straight urethral c. with two to six holes to facilitate drainage, especially in the presence of blood clots which may occlude one or more openings. self-retaining c. a c. so constructed that it remains in urethra and bladder until removed, e.g., indwelling c.; Foley c.. spiral tip c. a c. with a helical filiform tip. Swan-Ganz c. a balloon-tipped flexible c. commonly used in the treatment of critically ill patients; introduced via a major peripheral vein, usually jugular or subclavian, and floated under pressure waveform guidance, with or without fluoroscopy, sequentially through the right atrium, right ventricle, and pulmonary artery, ultimately to wedge, when the balloon is inflated, in a small arterial branch where the tip measures pressure-transmitted retrograde from the left side of the heart, which is assumed to represent left ventricular end-diastolic pressure; side holes allow measurement of central venous pressure; with the balloon deflated, c. measures pulmonary artery systolic, diastolic, and mean pressures; also allows infusion via c.; some catheters are fitted with pacing electrodes. SYN: pulmonary artery c.. two-way c. SYN: double-channel c.. vertebrated c. a c. made of several segments moving on each other like the links of a chain. whistle-tip c. a c. with an opening at the end and side. winged c. a soft rubber c. with little flaps at each side of the beak to retain it in the bladder.


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