Medical Dictionary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

columnella, pl .columnellae (ko-lum-nel′a, -nel′e)
SYN: columella (1) . [L. dim. of columna, a column; another form of columella]

colypeptic (ko-le-pep′tik)
Rarely used term for retarding digestion. [G. kolyo, to hinder, + pepsis, digestion]

com-
See con-.

coma (ko′ma)
1. A state of profound unconsciousness from which one cannot be roused; may be due to the action of an ingested toxic substance or of one formed in the body, to trauma, or to disease. [G. koma, deep sleep, trance] 2. An aberration of spherical lenses; occurring in cases of oblique incidence ( e.g., the image of a point becomes comet-shaped). [G. kome, hair] 3. SYN: c. aberration. delayed c. after hypoxia c. that develops a few days to 3 weeks after an acute hypoxic insult; the latter was usually severe enough to cause an initial bout of c., which cleared, and was followed by a transient interval of apparent normality. SYN: severe postanoxic encephalopathy. diabetic c. c. that develops in severe and inadequately treated cases of diabetes mellitus and is commonly fatal, unless appropriate therapy is instituted promptly; results from reduced oxidative metabolism of the central nervous system that, in turn, stems from severe ketoacidosis and possibly also from the histotoxic action of the ketone bodies and disturbances in water and electrolyte balance. SYN: Kussmaul c.. hepatic c. c. that occurs with advanced hepatic insufficiency and portal-systemic shunts, caused by elevated blood ammonia levels; characteristic findings include asterixis in the precoma stage and paroxysms of bilaterally synchronous triphasic waves on EEG examination. hyperosmolar (hyperglycemic) nonketotic c. (hi′per-os-mo-lar) a complication seen in diabetes mellitus in which very marked hyperglycemia occurs (such as levels over 800 mg/dL) causing osmotic shifts in water in brain cells and resulting in c.. It can be fatal or lead to permanent neurologic damage. Ketoacidosis does not occur in these cases. SYN: nonketotic hyperglycemia. hypoglycemic c. a metabolic encephalopathy caused by hypoglycemia; usually seen in diabetics, and due to exogenous insulin excess. hypoventilation c. c. seen with advanced lung failure and resultant hypoventilation. SYN: CO2 narcosis, hypoxic-hypercarbic encephalopathy, pulmonary encephalopathy. Kussmaul c. SYN: diabetic c.. metabolic c. c. resulting from diffuse failure of neuronal metabolism, caused by such abnormalities as intrinsic disorders of neuron or glial cell metabolism, or extracerebral disorders that produce intoxication or electrolyte imbalances. thyrotoxic c. c. preceding death in severe hyperthyroidism, as in thyroid storm or thyrotoxic crisis. trance c. SYN: lethargic hypnosis. uremic c. a metabolic encephalopathy caused by renal failure.

comatose (ko′ma-tos)
In a state of coma.

combination (kom-bi-na′shun)
1. The act of combining ( i.e., by joining, uniting, or otherwise bringing into close association) separate entities. 2. The state of being so combined. binary c. the name of a species of bacteria consisting of two parts: a generic name and a specific epithet. new c. the new name that results from the transfer of a microorganism from one genus to another; the generic name changes but, in most cases, the specific epithet remains the same.

combinatorial (kom′bin-a-tor′e-al)
Any system using a random assortment of components at any positions in the linear arrangement of atoms, i.e., a c. library of mutations could contain positions where all four bases have been randomly inserted.

combustible (kom-bus′ti-bl)
Capable of combustion.

combustion (kom-bus′chun)
Burning, the rapid oxidation of any substance accompanied by the production of heat and light. [L. comburo, pp. -bustus, to burn up] slow c. decay. spontaneous c. the ignition of a mass of material by heat developed within it by the oxidation of the substances composing it without external ignition.

Comby
Jules, French pediatrician, 1853–1947. See C. sign.

comedo, pl .comedoscomedones (kom′e-do, ko-me′do; kom′e-doz; kom-e-do′nez)
A dilated hair follicle infundibulum filled with keratin squamae, bacteria, particularly Propionibacterium acnes, and sebum; the primary lesion of acne vulgaris. [L. a glutton, fr. com-edo, to eat up] closed c. a c. with a narrow or obstructed opening on the skin surface; closed comedos may rupture, producing a low-grade dermal inflammatory reaction. SYN: whitehead (2) . open c. a c. with a wide opening on the skin surface capped with a melanin-containing blackened mass of epithelial debris. solar c. SYN: Favre-Racouchot disease.

comedocarcinoma (ko-me′do-kar-si-no′ma)
Form of carcinoma of the breast or other organ in which plugs of necrotic malignant cells may be expressed from the ducts.

comedogenic (kom′e-do-jen′ik)
Tending to promote the formation of comedones. [comedo + G. genesis, production]

comedonecrosis (kom′e-do-nek-ro′sis)
A type of necrosis occurring with glands in which there is central luminal inflam- mation with devitalized cells, usually occurring in the breast in intraductal carcinoma. [comedo + necrosis]

comes, pl .comites (ko′mez, kom′i-tez)
A blood vessel accompanying another vessel or a nerve; the veins accompanying an artery, often two in number, are called venae comitantes or venae comites. [L. a companion, fr. com-, together, + eo, pp. itus, to go]

comitance (kom′e-tans)
A characteristic of strabismus in which the misalignment of the eyes is maintained in all directions of gaze.

comitant (komitant)
Having comitance; in a c. strabismus the same angle of misalignment of the eyes is maintained in all directions of gaze. SYN: concomitant.

commensal (ko-men′sal)
1. Pertaining to or characterized by commensalism. 2. An organism participating in commensalism.

commensalism (ko-men′sal-izm)
A symbiotic relationship in which one species derives benefit and the other is unharmed; e.g., Entamoeba coli in the human large intestine. Cf.:metabiosis, mutualism, parasitism. [L. con-, with, together, + mensa, table] epizoic c. SYN: phoresis (2) .

comminuted (kom′i-noo-ted)
Broken into several pieces; denoting especially a fractured bone. [L. com-minuo, pp. -minutus, to make smaller, break into pieces, fr. minor, less]

comminution (kom-i-noo′shun)
A breaking into several pieces.

commissura, gen. and pl. commissurae (kom-i-sur′a, -sur′e) [TA]
SYN: commissure. [L. a joining together, seam, fr. com- mitto, to send together, combine] c. alba anterior [TA] SYN: white commissure. c. alba posterior [TA] SYN: white commissure. c. anterior [TA] SYN: anterior commissure. c. anterior grisea substantia intermedia centralis. c. bulborum [TA] SYN: commissure of bulbs. c. cinerea SYN: interthalamic adhesion. c. colliculorum inferiorum [TA] See commissure of inferior colliculus. c. colliculorum superiorum [TA] See commissure of superior colliculus. c. epithalamica SYN: c. posterior. c. fornicis [TA] the triangular subcallosal plate of commissural fibers resulting from the converging of the right and left fornix bundles which exchange numerous fibers and which curve back in the contralateral fornix to end in the hippocampus of the opposite side. SYN: commissure of fornix [TA] , c. hippocampi, delta fornicis, hippocampal commissure, psalterium, transverse fornix. c. grisea posterior [TA] See gray commissure. c. grisea 1. SYN: interthalamic adhesion. 2. See substantia intermedia centralis. c. grisea anterior See gray commissure. c. habenularum [TA] the connection between the right and left habenular nuclei; the decussation of fibers of the two striae medullares, forming the dorsal portion of the peduncle of the pineal body. SYN: habenular commissure [TA] , commissure of habenulae. c. hippocampi SYN: c. fornicis. c. labiorum [TA] SYN: commissure of lips. c. labiorum anterior [TA] SYN: anterior labial commissure. c. labiorum posterior [TA] SYN: posterior labial commissure. c. lateralis palpebrum [TA] SYN: lateral palpebral commissure. c. medialis palpebrum [TA] SYN: medial palpebral commissure. c. palpebrarum lateralis SYN: lateral palpebral commissure. c. palpebrarum medialis SYN: medial palpebral commissure. c. posterior [TA] a thin band of white matter, crossing from side to side beneath the habenula of the pineal body and over the aditus ad aqueductum cerebri; it is largely composed of fibers interconnecting the left and right pretectal region and related cell groups of the midbrain; dorsally, it marks the junction of the diencephalon and mesencephalon. SYN: c. epithalamica, posterior commissure. c. supraoptica dorsalis [TA] the commissural fibers that lie above and behind the optic chiasm. SYN: dorsal supraoptic commissure, Ganser commissure, Gudden commissure, Meynert commissure. c. ventralis alba SYN: white commissure.

commissural (kom-i-sur′al)
Relating to a commissure.

commissure (kom′i-shur) [TA]
1. Angle or corner of the eye, lips, or labia. 2. A bundle of nerve fibers passing from one side to the other in the brain or spinal cord. SYN: commissura [TA] . anterior c. [TA] a round bundle of nerve fibers that crosses the midline of the brain near the anterior limit of the third ventricle. It consists of a smaller anterior part (pars anterior commissurae anterioris [TA]), the fibers of which pass in part to the olfactory bulbs, and a larger posterior part (pars posterior commissurae anterioris [TA]), which interconnects the left and right temporal lobes. SYN: commissura anterior [TA] . anterior gray c. [TA] See gray c.. anterior labial c. [TA] the junction of the labia majora anteriorly at the mons pubis. SYN: commissura labiorum anterior [TA] . anterior c. of the larynx the junction of the vocal cords anteriorly in the larynx. anterior white c. [TA] SYN: white c.. c. of bulbs [TA] a narrow median band that connects the two masses of erectile tissue (the bulbus vestibuli) on either side of the vaginal orifice. SYN: commissura bulborum [TA] , c. of vestibular bulb, intermediate part of vestibular bulb, pars intermedia commissurae bulborum. c. of cerebral hemispheres SYN: corpus callosum. dorsal supraoptic c. SYN: commissura supraoptica dorsalis. c. of fornix [TA] SYN: commissura fornicis. Ganser c. SYN: commissura supraoptica dorsalis. gray c. [TA] narrow bands of gray substance spanning the midline dorsal to the central canal (posterior gray c. [TA], commissura griesa posterior [TA]) and ventral to the central canal (anterior gray c. [TA], commissura grisea anterior [TA]) Gudden c. SYN: commissura supraoptica dorsalis. c. of habenulae SYN: commissura habenularum. habenular c. [TA] SYN: commissura habenularum. hippocampal c. SYN: commissura fornicis. c. of inferior colliculus [TA] nerve fibers on the midline between the two inferior colliculi connecting the colliculi and containing some fibers originating from nontectal nuclei. labial c. [TA] junction of upper and lower lip which occurs at corner of mouth. SEE ALSO: angle of mouth. lateral palpebral c. [TA] the union of the upper and lower eyelids adjacent to the lateral angle. SYN: commissura lateralis palpebrum [TA] , commissura palpebrarum lateralis. c. of lips the junction of the lips lateral to the angle of the mouth. SYN: commissura labiorum [TA] , junction of lips. medial palpebral c. [TA] the union of the upper and lower eyelids adjacent to the medial angle. SYN: commissura medialis palpebrum [TA] , commissura palpebrarum medialis. Meynert c. SYN: commissura supraoptica dorsalis. posterior c. SYN: commissura posterior. posterior gray c. [TA] See gray c.. posterior labial c. [TA] a slight fold uniting the labia majora posteriorly in front of the anus. SYN: commissura labiorum posterior [TA] . posterior c. of the larynx SYN: interarytenoid fold. c. of superior colliculus [TA] nerve fibers interconnecting corresponding and noncorresponding portions of the two superior colliculi across the midline; may contain fibers originating outside the tectum. SYN: brachium colliculi superioris [TA] . ventral white c. [TA] SYN: white c.. c. of vestibular bulb SYN: c. of bulbs. Wernekinck c. the decussation of the brachia conjunctiva before their entrance into the red nucleus of the tegmentum. white c. a narrow band of white matter that crosses the midline of the spinal cord dorsal to the central canal and posterior gray c. (posterior white c. [TA]) and ventral to the central canal and the anterior gray c. (anterior white c. [TA]). SYN: anterior white c. [TA] , commissura alba anterior [TA] , commissura alba posterior [TA] , ventral white column [TA] , ventral white c. [TA] , commissura ventralis alba.

commissurotomy (kom′i-sur-ot′o-me)
1. Surgical division of any commissure, fibrous band, or ring via an incision or disruption e.g., balloon inflation. 2. SYN: midline myelotomy. mitral c. opening the narrowed mitral orifice for the relief of mitral stenosis.

commitment (ko-mit′ment)
Legal consignment, by certification, or voluntarily, of an individual to a mental hospital or institution. [L. com-mitto, to deliver, consign]

common vehicle spread
Spread of disease agent from a source that is common to those who acquire the disease, e.g., water, milk, air, syringe contaminated by infectious or noxious agents.

commotio (ko-mo′she-o)
SYN: concussion (2) . [L. a moving, commotion, fr. commoveo, pp. -motus, to set in motion, agitate] c. cerebri SYN: brain concussion. c. retinae concussion of the retina that may produce a milky edema in the posterior pole that clears up after a few days.

communicable (ko-mun′i-ka-bl)
Capable of being communicated or transmitted; said especially of disease.

communicans, pl .communicantes (ko-mu′ni-kans, ko-mu-ni-kan′tez)
Communicating; connecting or joining. [L. pres. p. of communico, pp. -atus, to share with someone, make common]

communication (ko-mu-ni-ka′shun)
1. An opening or connecting passage between two structures. 2. In anatomy, a joining or connecting, said of fibrous, solid structures, e.g., tendons and nerves. Anastomosis is incorrectly used as a synonym. 3. Information or ideas transmitted from one party to another. [L. communicatio] human c. the production and reception of oral, written, signed, or gestured information among human beings; involves the use of symbols known as language received through the auditory, tactile, proprioceptive, and visual systems and generated through voice and speech, writing, manual signs, and gestures; c. among humans may at times involve the vestibular, olfactory, and gustatory senses. simultaneous c. SYN: total c.. total c. an approach to the education of deaf children that uses a combination of sign language, finger spelling, and oral c.. SEE ALSO: oral auditory method, manual visual method, combined methods, under method. SYN: simultaneous c..

community (ko-mu′ni-te)
A given segment of a society or a population. biotic c. SYN: biocenosis. therapeutic c. a specially structured mental hospital or c. health center milieu that provides an effective environment for behavioral changes in patients through resocialization and rehabilitation.

community mental health center
A mental health treatment center located in a neighborhood catchment area close to the homes of patients, introduced in the 1960s via new federal legislation designed to replace the large state hospitals, which usually were located in remote rural areas; features include offering a series of comprehensive services by one or more members of the four mental health professions, provision of continuity of care, participation of consumers in the centers, community location to provide accessibility, a combination of indirect or preventive and direct services, the use of program-centered as well as case-centered consultation, a requirement for program evaluation, and various linkages to a variety of health and human services.

comorbidity (ko-mor-bid′i-te)
A concomitant but unrelated pathologic or disease process; usually used in epidemiology to indicate the coexistence of two or more disease processes. [co- + L. morbidus, diseased]

compacta (kom-pak′ta)
SYN: stratum compactum.

compages thoracis (kom-pa′jez tho-ra′sis)
SYN: thoracic cage.

comparascope (kom-par′a-skop)
A microscope accessory by means of which an observer may directly compare simultaneously the findings in two microscopic preparations. [L. comparo, to compare, + G. skopeo, to view]

compartimentum
SYN: compartment. c. antebrachii anterius [TA] SYN: anterior compartment of forearm. c. antebrachii extensorum posterior compartment of forearm. c. antebrachii flexorum anterior compartment of forearm. c. antebrachii posterius [TA] SYN: posterior compartment of forearm. c. brachii anterius [TA] SYN: anterior compartment of arm. c. brachii extensorum posterior compartment of arm. c. brachii flexorum [TA] SYN: anterior compartment of arm. c. brachii posterius [TA] SYN: posterior compartment of arm. c. cruris SYN: lateral compartment of leg. c. cruris anterius [TA] SYN: anterior compartment of leg. c. cruris extensorum anterior compartment of leg. c. cruris fibularium lateral compartment of leg. c. cruris flexorum posterior compartment of leg. c. cruris laterale peroneorum [TA] SYN: lateral compartment of leg. c. cruris posterius [TA] SYN: posterior compartment of leg. c. femoris adductorum medial compartment of thigh. c. femoris anterius [TA] SYN: anterior compartment of thigh. c. femoris extensorum [TA] SYN: anterior compartment of thigh. c. femoris flexorum posterior compartment of thigh. c. femoris mediale [TA] SYN: medial compartment of thigh. c. femoris posterius [TA] SYN: posterior compartment of thigh.

compartment
1. Partitioned off portion of a larger bound space; a separate section or chamber; the compartments of the limbs are bound deeply by bones and intermuscular septa and superficially by deep fascia and generally are not in communication with the other compartments, and thus infection or increased pathologic pressure may be limited to a c.; muscles contained within the compartments of the limbs share similar functions and innervation. 2. A separate division; specifically, a structural or biochemical portion of a cell that is separated from the rest of the cell. SYN: compartimentum. adductor c. of thigh medial c. of thigh. anterior c. of arm [TA] anterior portion of the space enclosed by the brachial fascia, separated from the posterior c. by the humerus and the lateral and medial intermuscular septa that extend from it; contains muscles that produce flexion, all innervated by the musculocutaneous nerve. SYN: compartimentum brachii anterius [TA] , compartimentum brachii flexorum [TA] , flexor c. of arm&star. anterior c. of forearm [TA] anterior portion of the space enclosed by the antebrachial fascia, separated from the posterior c. by the radius and ulna and by the intervening interosseous membrane; the spaces are demarcated superficially by the subcutaneous border of the ulna and the (pulse of the) radial artery; contains the pronators of the forearm, flexors of the wrist, and long flexors of the digits, innervated by the median (mostly) and ulnar nerves; is unusual among limb compartments since it communicates via the carpal tunnel with the midpalmar space. SYN: compartimentum antebrachii anterius [TA] , compartimentum antebrachii flexorum&star, flexor c. of forearm&star. anterior c. of leg [TA] anterior portion of space enclosed by the deep fascia of the leg, separated from the posterior c. by the tibia and fibula by the intervening interosseous membrane, and from the lateral c. by the anterior intermuscular septum; contains the dorsiflexors of the foot and long extensors of the toes, all innervated by the deep fibular (peroneal) nerve. SYN: compartimentum cruris anterius [TA] , compartimentum cruris extensorum&star, extensor c. of leg&star, dorsiflexor c. of leg. anterior c. of thigh [TA] anterior portion of the space enclosed by the fascia lata, separated from the medial and lateral compartments by the medial and lateral intermuscular septa, respectively; contains the shaft of the femur and the muscles that produce flexion at hip and/or extension at the knee, innervated by the femoral nerve. SYN: compartimentum femoris anterius [TA] , compartimentum femoris extensorum [TA] , extensor c. of thigh&star, c. of thigh for extensors of knee, c. of thigh for flexors of hip. dorsiflexor c. of leg SYN: anterior c. of leg. extensor c. of arm posterior c. of arm. extensor c. of forearm posterior c. of forearm. extensor c. of leg anterior c. of leg. extensor c. of thigh anterior c. of thigh. fibular c. of leg lateral c. of leg. flexor c. of arm anterior c. of arm. flexor c. of forearm anterior c. of forearm. flexor c. of leg posterior c. of leg. flexor c. of thigh posterior c. of thigh. lateral c. of leg [TA] lateral portion of space enclosed by the deep fascia of the leg, separated from the anterior and posterior compartments by the anterior and posterior intermuscular septa of leg, respectively; contains evertors of the foot, innervated by the superficial fibular (peroneal) nerve. SYN: compartimentum cruris laterale peroneorum [TA] , compartimentum cruris fibularium&star, fibular c. of leg&star, peroneal c. of leg&star, compartimentum cruris. medial c. of thigh [TA] medial portion of the space enclosed by the fascia lata, separated from the anterior and posterior compartments by the medial and posterior femoral intermuscular septa, respectively; contains muscles that adduct the thigh at the hip joint, all of which are innervated by the obturator nerve. SYN: compartimentum femoris mediale [TA] , adductor c. of thigh&star, compartimentum femoris adductorum&star. nonplasmatic c. c. surrounded by a single biomembrane ( E.G., vacuoles, lysosomes). peroneal c. of leg lateral c. of leg. plantarflexor c. of leg SYN: posterior c. of leg. plasmatic c. c. surrounded by a double biomembrane and containing polynucleotides ( E.G., mitochondria). posterior c. of arm [TA] posterior portion of the space enclosed by the brachial fascia, separated from the anterior c. by the humerus and the lateral and medial intermuscular septa that extend from it; contains the triceps muscles that extend the forearm at the elbow joint and are innervated by the radial nerve. SYN: compartimentum brachii posterius [TA] , compartimentum brachii extensorum&star, extensor c. of arm&star. posterior c. of forearm [TA] posterior portion of the space enclosed by the antebrachial fascia, separated from the anterior c. by the radius and ulna and by the intervening interosseous membrane; the spaces are demarcated superficially by the subcutaneous border of the ulna and the (pulse of the) radial artery; contains a supinator of the forearm, extensors of the hand at the wrist, and long extensors of the digits, all innervated by the radial nerve. SYN: compartimentum antebrachii posterius [TA] , compartimentum antebrachii extensorum&star, extensor c. of forearm&star. posterior c. of leg [TA] posterior portion of space enclosed by the deep fascia of the leg, separated from the anterior c. by the tibia and fibula by the intervening interosseous membrane, and from the lateral c. by the posterior intermuscular septum of the leg; contains the plantarflexors of the foot and long flexors of the toes, all innervated by the tibial nerve. SYN: compartimentum cruris posterius [TA] , compartimentum cruris flexorum&star, flexor c. of leg&star, plantarflexor c. of leg. posterior c. of thigh [TA] posterior portion of the space enclosed by the fascia lata, separated from the medial and anterior compartments by the posterior and lateral intermuscular septa, respectively; contains the hamstring muscles (extensor of the thigh at the hip joint and flexors of the leg at the knee joint) and the short head of the biceps; all innervated by the sciatic nerve (the former by the tibial nerve portion, the latter by the fibular nerve portion). SYN: compartimentum femoris posterius [TA] , compartimentum femoris flexorum&star, flexor c. of thigh&star, c. of thigh for extensors of hip joint, c. of thigh for flexors of knee. c. of thigh for extensors of hip joint SYN: posterior c. of thigh. c. of thigh for extensors of knee SYN: anterior c. of thigh. c. of thigh for flexors of hip SYN: anterior c. of thigh. c. of thigh for flexors of knee SYN: posterior c. of thigh.

compartmentation (kom-part′ment-a′shun)
The division of a cell into different regions, either structurally or biochemically.

compatibility (kom-pat-i-bil′i-te)
The condition of being compatible.

compatible (kom-pat′i-bl)
1. Capable of being mixed without undergoing destructive chemical change or exhibiting mutual antagonism; said of the elements in a properly constructed pharmaceutical mixture. 2. Denoting the ability of two biologic entities to exist together without nullification of, or deleterious effects on, the function of either; e.g., blood, tissues, or organs that cause no reaction when transfused or no rejection when transplanted. 3. Denoting satisfactory relationships between two or more people as in work or in marriage or in sexual activities. [L. con-, with, + patior, to suffer]

compensation (kom-pen-sa′shun)
1. A process in which a tendency for a change in a given direction is counteracted by another change so that the original change is not evident. 2. An unconscious mechanism by which one tries to make up for fancied or real deficiencies. [L. com-penso, pp. -atus, to weigh together, counterbalance] attenuation c. SYN: time-gain c.. depth c. SYN: time-gain c.. gene dosage c. the putative mechanism that adjusts the X-linked phenotypes of males and females to compensate for the haploid state in males and the diploid state in females. It is now largely ascribed to lyonization which compensates the mean of the dose but not its variance, which is greater in females. time-gain c. (TGC) in ultrasonography, an increase in receiver gain with time to compensate for loss in echo amplitude with depth, usually due to attenuation. SYN: attenuation c., depth c., time c. gain, time-compensated gain, time-varied gain control, time-varied gain.

compensatory (kom-pen′sa-tor-e)
Providing compensation; making up for a deficiency or loss.

competence (kom′pe-tens)
1. The quality of being competent or capable of performing an allotted function. 2. The normal tight closure of a cardiac valve. 3. The ability of a group of embryonic cells to respond to an inducer. 4. The ability of a (bacterial) cell to take up free DNA, which may lead to transformation. 5. In psychiatry, the mental ability to distinguish right from wrong and to manage one's own affairs, or to assist one's counsel in a legal proceeding. 6. The state of reactivity of a cell, tissue, or organism that allows it to respond to certain stimuli. [Fr. c., fr. L.L. competentia, congruity] cardiac c. ability of the ventricles to pump the blood returning to the atria, so that atrial pressure does not rise abnormally. immunologic c. capability of mounting an immunologic response.

competition (kom-pe-tish′un)
The process by which the activity or presence of one substance interferes with, or suppresses, the activity of another substance with similar affinities. antigenic c. c. that occurs when two different antigens, each of which can evoke an immunologic response when inoculated alone, are mixed and inoculated together; the response may be to only one, that to the other being largely or entirely suppressed.

complaint (kom-plant′)
A disorder, disease, or symptom, or the description of it. [O.Fr. complainte, fr. L. complango, to lament] chief c. the primary symptom that a patient states as the reason for seeking medical care.

complement (kom′ple-ment)
Ehrlich term for the thermolabile substance, normally present in serum, that is destructive to certain bacteria and other cells sensitized by a specific c.-fixing antibody. C. is a group of at least 20 distinct serum proteins, the activity of which is affected by a series of interactions resulting in enzymatic cleavages and which can follow one or the other of at least two pathways. In the case of immune hemolysis (classical pathway), the complex comprises nine components (designated C1 through C9) that react in a definite sequence and the activation of which is usually effected by the antigen-antibody complex; only the first seven components are involved in chemotaxis, and only the first four are involved in immune adherence or phagocytosis or are fixed by conglutinins. An alternative pathway (see properdin system) may be activated by factors other than antigen-antibody complexes and involves components other than C1, C4, and C2 in the activation of C3. SEE ALSO: component of c.. [L. complementum, that which completes, fr. com-pleo, to fill up] heparin c. the protein component of heparin in blood. c. pathways 1. the classical c. pathway (initiated usually by binding of C1 to IgG or IgM antibody to C1)is a complex of three subunits: C1q, C1r, and C1s. After C1q is bound, C1r (an overbar indicates enzymatic activity) cleaves C1s to C1s. C1s cleaves both C4 into C4a and C4b as well as C2 into C2a and C2b. C2b combines with C4b to form C4b2b, which is a C3 convertase. C3 convertase cleaves C3 into C3a and C3b. C3b joins C4bC2b to form a C5 convertase (also known as C4b2b3b), which cleaves C5 into C5a and C5b. Once C5b is bound to the cell surface the remainder of the c. components (C6–C9) as well as C5b form the membrane attack complex (MAC). MAC causes a hole in the cell membrane. 2. in the alternative c. pathway, surface-bound C3b binds Factor B, which is cleaved by Factor D into Ba and Bb. C3bBb is an unstable C3 convertase unless properdin (P) binds to it to form C3bBbP. The stable C3 convertase generates more C3b. When a complex of C3bBbC3b is formed, this is the alternative pathway C5 convertase. From C5b through C9, the classical and alternative pathways are the same. 3. In the lectin-binding pathway, mannose-binding protein (MBP) initiates the pathway, which then uses components of the classical c. pathway. Some of the “a” components of both pathways have various biologic activities, i.e., C3a is an anaphylatoxin.

complementarity (kom-ple-men-tar′i-te)
1. The degree of base-pairing (A opposite U or T, G opposite C) between two sequences of DNA and/or RNA molecules. 2. The degree of affinity, or fit, of antigen- and antibody-combining sites.

complementation (kom′ple-men-ta′shun)
1. Functional interaction between two defective viruses permitting replication under conditions inhibitory to the single virus. 2. Interaction between two genetic units, one or both of which are defective, permitting the organism containing these units to function normally, whereas it could not do so if either unit were absent. intergenic c. c. between pieces of genetic material that regulate the same function, such as a multienzyme pathway, but have defects in regions of separate genetic function; such c. permits synthesis of a normal end-product. intragenic c. c. between pieces of genetic material, each of which has a different defect within the same locus; the resultant product of each is defective and nonfunctional, but the defective products may associate to produce a product which has some activity.

complex (kom′pleks)
1. An organized constellation of feelings, thoughts, perceptions, and memories that may be in part unconscious and may strongly influence associations and attitudes. 2. In chemistry, the relatively stable combination of two or more compounds into a larger molecule without covalent binding. 3. A composite of chemical or immunologic structures. 4. A structural anatomic entity made up of three or more interrelated parts. 5. An informal term used to denote a group of individual structures known or believed to be anatomically, embryologically, or physiologically related. [L. complexus, woven together] aberrant c. an anomalous electrocardiographic c., more specifically an abnormal ventricular c. caused by abnormal intraventricular conduction of a supraventricular impulse. AIDS dementia c. (ADC) a subacute or chronic HIV-1 encephalitis, the most common neurologic complication in the later stages of HIV infection; manifested clinically as a progressive dementia, accompanied by motor abnormalities. SYN: AIDS dementia, HIV encephalopathy. AIDS-related c. (ARC) manifestations of AIDS in persons who have not yet developed major deficient immune function, characterized by fever with generalized lymphadenopathy, diarrhea, weight loss, minor opportunistic infections, cytopenias. amygdaloid c. [TA] SYN: amygdaloid body. anomalous c. a c. in the electrocardiogram differing significantly from the physiologic type in the same lead. antigen-antibody c. immune c.. antigenic c. a composite of different antigenic structures, such as a cell or a bacterium, or, by extension, a molecule containing two or more determinant groups of different antigenic specificities. apical c. a set of anterior structures that characterize one or several developmental stages of members of the protozoan phylum Apicomplexa; includes the following structures, visible by electron microscopy: polar ring, conoid, rhoptries, micronemes, and subpellicular tubules. atrial c. p wave in the electrocardiogram. SYN: auricular c.. auricular c. SYN: atrial c.. binary c. a noncovalent c. of two molecules; often referring to the enzyme-substrate c. in an enzyme-catalyzed reaction. Cf.:central c., Michaelis c.. SYN: enzyme-substrate c.. brain wave c. a specific combination of fast and slow electroencephalographic activity that recurs frequently enough to be identified as a discrete phenomenon. brother c. SYN: Cain c.. Cain c. a rarely used term for extreme envy or jealousy of a brother, leading to hatred. SYN: brother c.. [Cain, biblical personage] Carney c. an autosomal dominant condition of Cushing syndrome due to immunoglobulin-mediated ACTH receptor inhibition, cardiac and cutaneous myxomas, lentigines, melanotic schwannomas, and pituitary and testicular tumors. castration c. 1. a child's fear of injury to the genitals by the parent of the same sex as punishment for unconcious guilt over oedipal feelings; 2. fantasied loss of the penis by a female or fear of its actual loss by a male; 3. unconscious fear of injury from those in authority. SYN: castration anxiety. caudal pharyngeal c. the ultimobranchial body associated with the embryonic fourth and transitory fifth pharyngeal pouches. central c. in an enzyme-catalyzed reaction, the structural c. of the enzyme and all of the enzyme's substrates (or the enzyme with all of the enzyme's products) equivalent to the binary c. for a one-substrate enzyme. Cf.:binary c., Michaelis c.. charge transfer c. 1. a c. between two organic molecules in which an electron from one (the donor) is transferred to the other (the acceptor), becoming generally distributed throughout the latter; subsequent transfer of a hydrogen atom completes the reduction of the acceptor; such complexes are generally highly colored and may be so observed; 2. a network of hydrogen bridges at the catalytic center of certain proteases. SYN: charge transfer system. Diana c. a rarely used term for ideas leading to the adoption of masculine traits and behavior in a female. [Diana, L. myth. char.] diphasic c. a c. consisting of both positive and negative deflections. EAHF c. a combination of allergies consisting of eczema, asthma and hay fever. Eisenmenger c. the combination of ventricular septal defect with pulmonary hypertension and consequent right-to-left shunt through the defect, with or without an associated overriding aorta. SYN: Eisenmenger defect, Eisenmenger disease, Eisenmenger tetralogy. Electra c. female counterpart of the Oedipus c. in the male; a term used to describe unresolved conflicts during childhood development toward the father which subsequently influence a woman's relationships with men. SYN: father c.. [Electra, daughter of Agamemnon] electrocardiographic c. a deflection or group of deflections in the electrocardiogram. enzyme-substrate c. SYN: binary c.. equiphasic c. SYN: isodiphasic c.. father c. SYN: Electra c.. femininity c. in psychoanalysis, the unconscious fear, in boys and men, of castration at the hands of the mother with resultant identification with the aggressor and envious desire for breasts and vagina. Ghon c. SYN: Ghon tubercle. Golgi c. SYN: Golgi apparatus. H-2 c. term that denotes genes of the major histocompatibility c. in the mouse. histocompatibility c. a family of fifty or more genes on the sixth human chromosome that code for cell surface proteins and play a role in the immune response.Histocompatibility genes control the production of proteins on the outer membranes of tissue and blood cells, especially lymphocytes, and are essential elements in cell-cell recognition and interaction. Surface proteins also determine the level and type of immune response, are involved in the presentation of antigens to the immune system, and may serve other biochemical and immunologic functions. In the case of allografts, the greater the histocompatibility (i.e., the closer the match between donor and recipient cell surface antigens), the less the likelihood of rejection. The major histocompatibility determinants are the human leukocyte antigens (HLA). HLA typing of a potential marrow donor and a potential transplant recipient is used to predict graft rejection and graft-versus-host disease. HLA c. the major histocompatibility c. in humans. SEE ALSO: human leukocyte antigens, under antigen. immune c. antigen combined with specific antibody, to which complement may also be fixed, and which may precipitate or remain in solution. Frequently associated with autoimmune disease. inferiority c. a sense of inadequacy which is expressed in extreme shyness, diffidence, or timidity, or as a compensatory reaction in exhibitionism or aggressiveness. inferior olivary c. [TA] the three nuclei that collectively form what is commonly called the inferior olivary nucleus. These are the principal olivary nucleus (with its dorsal, ventral, and lateral lamellae) and the medial accessory and posterior (dorsal) accessory olivary nuclei. SEE ALSO: principal olivary nucleus. SYN: complexus olivaris inferior [TA] . iron-dextran c. a colloidal solution of ferric hydroxide in c. with partially hydrolyzed dextran; used in the treatment of iron deficiency anemias by intramuscular injection. isodiphasic c. a diphasic c. whose positive and negative deflections are approximately equal. SYN: equiphasic c.. j-g c. SYN: juxtaglomerular c.. Jocasta c. a rarely used term for a mother's libidinous fixation on a son. [Jocasta, mother and wife of Oedipus] junctional c. the attachment zone between epithelial cells, typically consisting of the zonula occludens, the zonula adherens, and the macula adherens (desmosome). juxtaglomerular c. a c. consisting of the juxtaglomerular cells, which are modified smooth muscle cells in the wall of the afferent glomerular arteriole and sometimes also the efferent arteriole; extraglomerular mesangium lacis cells, which are located in the angle between the afferent and efferent glomerular arterioles; the macula densa of the distal convoluted tubule; and granular epithelial peripolar cells located at the angle of reflection of the parietal to the visceral capsule of the renal corpuscle; believed to provide some feedback control of extracellular fluid volume and glomerular filtration rate. SYN: j-g c., juxtaglomerular apparatus. K c. high amplitude, diphasic frontocental slow waves in the electroencephalogram related to arousal from sleep by a sound; characteristic of sleep stages 2, 3, and 4. α-keto acid dehydrogenase c. See α-keto acid dehydrogenase. α-ketoglutarate dehydrogenase c. SYN: α-ketoglutarate dehydrogenase. Lear c. a rarely used term for a father's libidinous fixation on a daughter. [Lear, Shakespearean character] MAC c. SYN: membrane attack c.. major histocompatibility c. (MHC) a group of linked loci, collectively termed H-2 c. in the mouse and HLA c. in humans, that codes for cell-surface histocompatibility antigens and is the principal determinant of tissue type and transplant compatibility. SEE ALSO: human leukocyte antigens, under antigen. mediator c. co-activation proteins involved in RNA polymerase transcription of DNA segments. membrane attack c. (MAC) a c. of complement components (C5–C9) that, when activated, bind to the membrane of a target cell, penetrating it with a hydrophobic residue exteriorly and a hydrophilic residue in the interior of the cell; this allows passage of ions and water, swelling of the cell and subsequent lysis. SYN: MAC c.. Meyenburg c. clusters of small bile ducts occurring in polycystic livers, separate from the portal areas. Michaelis c. binary c. of an enzyme. minor histocompatibility c. (MHC) genes outside of MHC that are present on various chromosomes that encode antigens contributing to graft rejection. monophasic c. a c. in the electrocardiogram that is entirely negative or entirely positive. multienzyme c. a structurally distinct and ordered collection of enzymes, often catalyzing successive steps in a metabolic pathway ( E.G., pyruvate dehydrogenase c.). Oedipus c. a developmentally distinct group of associated ideas, aims, instinctual drives, and fears generally observed in male children 3 to 6 years old: coinciding with the peak of the phallic phase of psychosexual development, the child's sexual interest is attached primarily to the parent of the opposite sex and is accompanied by aggressive feelings toward the parent of the same sex; in psychoanalytic theory, it is replaced by the castration c.. [Oedipus, G. myth. char.] ostiomeatal c. point where the frontal and maxillary sinuses normally drain into the nasal cavity; obstruction produces inflammation of affected sinus cavities. SYN: ostiomeatal unit. persecution c. a feeling that others have evil designs against one's well-being. primary c. SYN: Ranke c.. pyruvate dehydrogenase c. pyruvate dehydrogenase. QRS c. portion of electrocardiogram corresponding to the depolarization of ventricular cardiac cells. Ranke c. the typical lesions of primary pulmonary tuberculosis, consisting of a small peripheral focus of infection (Ghon focus), with hilar or paratracheal lymph node involement. SYN: primary c.. ribosome-lamella c. a cylindric cytoplasmic inclusion composed of concentrically arranged sheets of membranes alternating with rows of ribosomes; characteristic of the hairy cell in leukemic reticuloendotheliosis. Shone c. an obstructive lesion of the mitral valve c. with left ventricular outflow obstruction and coarctation of the aorta. sicca c. dryness of the mucous membranes, as of the eyes and mouth, in the absence of a connective tissue disease such as rheumatoid arthritis. spike and wave c. a generalized, synchronous pattern seen on the electroencephalogram, consisting of a sharply contoured fast wave followed by a slow wave; particularly found in patients with generalized epilepsies. Spike and wave complexes are often characterized by their frequency, e.g., slow spike and wave, fast spike and wave. superiority c. term sometimes given to the compensatory behavior, e.g., aggressiveness, self-assertion, associated with inferiority c.. superior olivary c. superior olivary nucleus. symptom c. 1. See syndrome. 2. See c. (1) . synaptinemal c. a submicroscopic structure interposed between the homologous chromosome pairs during synapsis. SYN: synaptonemal c.. synaptonemal c. SYN: synaptinemal c.. Tacaribe c. of viruses a group of arenaviruses (New World) that includes the antigenically related arboviruses Amapari, Junin, Latino, Machupo, Parana, Pichinde, Tacaribe, and Tamiami. ternary c. term used to describe the tripartite combination of, for example, enzyme-cofactor-substrate or enzyme-substrate1-substrate2 for a multisubstrate enzyme, the active form involved in many enzyme-catalyzed reactions. triple symptom c. SYN: Behçet syndrome. VATER c. a constellation of vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, and renal and radial anomalies; associated with Fanconi anemia. ventricular c. the continuous QRST waves of each beat in the electrocardiogram. ventrobasal c. [TA] the large posterior part of the ventral nucleus of the thalamus receiving the somatic sensory lemnisci (medial lemniscus, spinothalamic tract, trigeminal lemniscus) and the ascending gustatory (taste) lemniscus and projecting in turn by way of the internal capsule to the cortex of the postcentral gyrus. This c. of nuclei is somatotopically organized and subdivided into a ventral posterolateral nucleus [TA] (nucleus ventralis posterolateralis [TA]) representing the leg, a ventral posterior intermediate nucleus representing the arm, and a ventral posteromedial nucleus [TA] (nucleus ventralis posteromedialis [TA]) representing the face and an arcuate nucleus of thalamus receiving the gustatory lemniscus. SYN: nuclei ventrobasales [TA] , ventrobasal nuclei (c.) [TA] , nucleus ventralis posterior thalami.

complexion (kom-plek′shun)
The color, texture, and general appearance of the skin of the face. [L. complexio, a combination, (later) physical condition]

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