Medical Dictionary

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atrophoderma (at′ro-fo-der′ma)
Atrophy of the skin that may occur either in discrete localized areas or in widespread areas. SEE ALSO: anetoderma. SYN: atrophia cutis. a. albidum stocking-like type of atrophy affecting the extremities, probably congenital; first noted in early childhood on the lower limbs as a symmetric thinning that renders the parts sensitive. a. diffusum diffuse idiopathic cutaneous atrophy. a. maculatum SYN: anetoderma. a. neuriticum SYN: glossy skin. a. of Pasini and Pierini a form of slate-colored atrophy of the skin occurring in discrete, 2-cm or larger lesions, either singly or multiply, and occasionally confluent, increasing in number and size over a period of years and then remaining constant; thought by some to be of two types: one preceded by morphea, and the other appearing with no preceding identifiable pathology. senile a., a. senilis the loss of collagen, with thinning and decreased elasticity of the skin associated with old age. a. striatum SYN: striae cutis distensae, under stria.

atrophodermatosis (at′ro-fo-der-ma-to′sis)
Any cutaneous affection in which a prominent symptom is skin atrophy.

atrophy (at′ro-fe)
A wasting of tissues, organs, or the entire body, as from death and reabsorption of cells, diminished cellular proliferation, decreased cellular volume, pressure, ischemia, malnutrition, lessened function, or hormonal changes. SYN: atrophia. [G. atrophia, fr. a- priv. + trophe, nourishment] acute reflex bone a. SYN: Sudeck a.. acute yellow a. of the liver SYN: acute massive liver necrosis. alveolar a. diminution in size of the supportive tissues of the teeth due to lack of function, reduced blood supply, or unknown causes. arthritic a. a. of muscles rendered inactive by a chronically inflamed or fixed joint. blue a. depressed blue atrophic scars due to injections in the skin of impure substances, as seen in narcotics addicts. brown a. a. of the heart wall, especially in the elderly, in which the muscle is dark reddish brown and reduced in volume; the muscle fibers become pigmented especially about the nuclei, by lipochrome granules. Buchwald a. a progressive form of cutaneous a.. central areolar choroidal a. SYN: areolar choroidopathy. cerebellar a. a degeneration of the cerebellum, particularly the Purkinje cells, as the result of abiotrophy or of toxic agents, as in alcoholism. choroidal vascular a. a. affecting either all choroidal vessels or only the choriocapillaris, occurring either diffusely or confined to the posterior pole of the eye. congenital cerebellar a. familial disorder that causes degeneration of various cells in the cerebellum. Two types are recognized, one in which the granular layer cells degenerate, the other in which the Purkinje cells degenerate. congenital microvillus a. SYN: microvillus inclusion disease. cyanotic a. a. due to destruction of the parenchymatous cells of an organ as a consequence of chronic venous congestion. SYN: red a.. cyanotic a. of the liver a sequela of longstanding hepatic congestion due to high pressure in the right atrium as in chronic constrictive pericarditis and severe, protracted right ventricular failure. dentatorubral cerebellar a. with polymyoclonus SYN: dyssynergia cerebellaris myoclonica. disuse a. muscle wasting caused by immobilization, such as casting. dominant optic a. an autosomal dominant bilateral optic neuropathy characterized by insidious preschool vision loss. SYN: Kjer optic a.. essential progressive a. of iris progressive a. of the iris without inflammatory signs, characterized by patchy loss of all layers of the iris with hole formation, migration of the pupil, degeneration of the corneal endothelium, peripheral anterior synechiae, and secondary glaucoma; usually unilateral, predominantly affecting women in their middle years. SEE ALSO: iridocorneal syndrome. facioscapulohumeral a. SYN: facioscapulohumeral muscular dystrophy. familial spinal muscular a. SYN: spinal muscular a., type I. fatty a. fatty infiltration secondary to an a. of the essential elements of an organ or tissue. geographic retinal a. a pattern of well-demarcated retinal pigment epithelial a. associated with choriocapillary layer and photoreceptor a. leading to vision loss. gingival a. SYN: gingival recession. gyrate a. of choroid and retina [MIM*258870] a slowly progressive a. of the choriocapillaris, pigmentary epithelium, and sensory retina, with irregular confluent atrophic areas and an associated ornithinuria; autosomal recessive inheritance; due to a deficiency of ornithine δ-aminotransferase, caused by mutation in the ornithine δ-aminotransferase gene (OAT) on chromosome 10q. Hoffmann muscular a. SYN: spinal muscular a., type I. horizontal a. a progressive loss of alveolar and supporting bone surrounding the teeth, beginning at the most coronal level of the bone. SYN: horizontal resorption. infantile muscular a. SYN: spinal muscular a., type I. infantile progressive spinal muscular a. SYN: spinal muscular a., type I. ischemic muscular a. Volkmann contracture. juvenile muscular a. SYN: spinal muscular a., type III. juvenile spinal muscular a. SYN: spinal muscular a., type III. Kjer optic a. SYN: dominant optic a.. Leber hereditary optic a. [MIM*535000] degeneration of the optic nerve and papillomacular bundle with resulting loss of central vision and blindness, progressive for several weeks, then usually becoming stationary with permanent central scotoma; the age of onset is variable, most often in the third decade; more males than females are affected. Mitochondrial or cytoplasmic inheritance via the maternal lineage, caused by mutation in the mitochondrial gene(s) acting autonomously or in association with each other. linear a. SYN: striae cutis distensae, under stria. macular a. SYN: anetoderma. marantic a. SYN: marasmus. multiple system a. nonhereditary, neurodegenerative disease of unknown cause, characterized clinically by the development of parkinsonism, ataxia, autonomic failure, or pyramidal track signs, in various combinations. Pathologically there are nerve cell loss, gliosis, and the accumulation of abnormal tubular structures in the cytoplasm and nucleus of oligodendrocytes and neurons in the basal ganglion, cerebellum, and intermediolateral columns of the spinal cord; can present as predominantly parkinsonism, as predominantly ataxia, or as a combination of parkinsonism, ataxia, and autonomic failure; it is a relatively rapidly progressive and fatal disorder. muscular a. wasting of muscular tissue. Cf.:myopathic a.. SYN: myatrophy, myoatrophy. myopathic a. muscular a. caused by a primary disorder of muscle. neurogenic a. SYN: neurotrophic a.. neurotrophic a. abnormalities of the skin, hair, nails, subcutaneous tissues, and bone, caused by peripheral nerve lesions. SYN: neurogenic a., trophoneurotic a.. nutritional type cerebellar a. a restricted type of cerebellar cortical degeneration, affecting particularly the Purkinje cells of the anterior and superior vermis; probably caused by thiamin deficiency; most frequently seen in chronic alcoholics and then called alcoholic cerebellar degeneration. olivopontocerebellar a. a group of genetically distinct, mostly autosomal dominant progressive neurologic diseases characterized by loss of neurons in the cerebellar cortex, basis pontis, and inferior olivary nuclei; results in ataxia, tremor, involuntary movement, and dysarthria; five clinical types (four with dominant, one with recessive inheritance) have been described, each type characterized by additional findings, such as sensory loss, retinal degeneration, ophthalmoplegia, and extrapyramidal signs. Several loci are involved, autosomal dominant [MIM*164400 to *164600] and recessive [MIM*258300]. SEE ALSO: spinocerebellar ataxia. SYN: olivopontocerebellar degeneration. periodontal a. decrease in size and/or cellular elements of the periodontium after it has reached normal maturity. peroneal muscular a. a group of peripheral neuromuscular disorders, sharing the common feature of marked wasting of the distal parts of the extremities, particularly the peroneal muscle groups, resulting in long, thin legs; it usually involves the legs before the arms with pes cavus often the first sign. There are two forms of hereditary sensorimotor polyneuropathies, i.e., a demyelinating type and an axonal loss type. Autosomal dominant [MIM*118200 and MIM*118220], autosomal recessive [MIM*214400], and X-linked recessive [MIM*302800, MIM*302801 and MIM*302802] forms exist. SYN: Charcot-Marie-Tooth disease. Pick a. circumscribed a. of the cerebral cortex. SYN: lobar sclerosis, progressive circumscribed cerebral a.. postmenopausal a. a. following menopause, as of the genital organs. pressure a. the wasting of hard or soft tissue resulting from excessive pressure applied to tissue by a denture base. primary idiopathic macular a. SYN: anetoderma. primary macular a. of skin SYN: anetoderma. progressive choroidal a. SYN: choroideremia. progressive circumscribed cerebral a. SYN: Pick a.. progressive infantile spinal muscular a. SYN: spinal muscular a., type I. progressive muscular a. SYN: amyotrophic lateral sclerosis. progressive spinal muscular a. one of the subgroups of motor neuron disease; a progressive degenerative disorder of the motor neurons of the spinal cord, manifested as progressive, often symmetrical, weakness and wasting, typically beginning in the distal portions of the limbs, particularly in the upper extremities, and spreading proximally; fasciculation potentials are often present, but evidence of corticospinal tract disease ( e.g., increased deep tendon reflexes, Babinski sign) is not. pulp a. diminution in size and/or cellular elements of the dental pulp due to interference with the blood supply. red a. SYN: cyanotic a.. scapulohumeral a. SYN: Vulpian a.. senile a. wasting of tissues and organs with advancing age from decreased catabolic or anabolic processes, at times due to endocrine changes, decreased use, or ischemia. SYN: geromarasmus. spinal muscular a. (SMA) a heterogeneous group of degenerative diseases of the anterior horn cells in the spinal cord and motor nuclei of the brainstem; all are characterized by weakness. Upper motor neurons remain normal. These diseases include Werdnig-Hoffmann disease (SMA type 1), SMA type 2, and Kugelberg-Welander disease (SMA type 3). SEE ALSO: Fazio-Londe disease. spinal muscular a., type I [MIM*253300] the early infantile form, characterized by profound muscle weakness and wasting with onset at or shortly after birth; death occurs usually before 2 years of age. Autosomal recessive inheritance, caused by mutation in the survival motor neuron gene (SMN1) on 5q. About one-half of patients are also missing both homologs of a neighboring gene that encodes neuronal apoptosis inhibitory protein (NAIP), the loss of which is thought to influence the severity of the disease. SYN: familial spinal muscular a., Hoffmann muscular a., infantile muscular a., infantile progressive spinal muscular a., progressive infantile spinal muscular a., Werdnig-Hoffmann disease, Werdnig-Hoffmann muscular a.. spinal muscular a., type II [MIM*253550] a form intermediate in severity between the infantile form (SMA type I) and the juvenile form (SMA type III); characterized by proximal muscle weakness with onset usually between 3 and 15 months and survival until adolescence; autosomal recessive inheritance, caused by mutation in the SMN1 gene on 5q. spinal muscular a., type III [MIM*253400] the juvenile form with onset in childhood or adolescence, characterized by progressive proximal muscular weakness and wasting, primarily in the legs, followed by distal muscle involvement, caused by degeneration of motor neurons in the anterior horns of the spinal cord; autosomal recessive inheritance, caused by mutation in the SMN1 gene on 5q. SYN: juvenile muscular a., juvenile spinal muscular a., Kugelberg-Welander disease, Wohlfart-Kugelberg-Welander disease. striate a. of skin SYN: striae cutis distensae, under stria. Sudeck a. a. of bones, commonly of the carpal or tarsal bones, following a slight injury such as a sprain. SEE ALSO: causalgia, reflex sympathetic dystrophy. SYN: acute reflex bone a., posttraumatic osteoporosis, Sudeck syndrome. traction a. SYN: striae cutis distensae, under stria. transneuronal a. SYN: transsynaptic degeneration. trophoneurotic a. SYN: neurotrophic a.. villous a. abnormality of the small intestinal mucosa with crypt hyperplasia, resulting in flattening of the mucosa and the appearance of a. of villi; clinically seen in malabsorption syndromes such as sprue. Vulpian a. progressive spinal muscular a. beginning in the shoulder. SYN: scapulohumeral a.. Werdnig-Hoffmann muscular a. SYN: spinal muscular a., type I. yellow a. of the liver acute yellow a. of the liver. Zimmerlin a. a variety of hereditary progressive muscular a. in which the a. begins in the upper half of the body.

atropine (at′ro-pen)
A racemic mixture of d- and l-hyoscyamine, alkaloids obtained from the leaves and roots of Atropa belladonna; an anticholinergic, with diverse effects (tachycardia, mydriasis, cycloplegia, constipation, urinary retention, antisudorific) attributable to reversible competitive blockade of acetylcholine at muscarinic type cholinergic receptors; used in the treatment of poisoning with organophosphate insecticides or nerve gases. The (–) form is by far the more active. SYN: dl-hyoscyamine, tropine tropate. a. methonitrate the methylnitrate of a., with the same actions and uses as a., but less lipid-soluble (due to the presence of a quaternary nitrogen atom that limits penetration of the blood-brain barrier) and hence with fewer central nervous system effects; a quaternary compound. a. methylbromide SYN: methylatropine bromide. a. sulfate an anticholinergic; a widely used soluble salt of a..

atropinic (at′ro-pin-ik)
Term used to indicate a sharing of pharmacologic properties with atropine. This means blocking parasympathetic neuroeffector junctions leading to a constellation of effects including tachycardia, urinary retention, dry mouth, constipation, mydriasis, cycloplegia, and other anticholinergic effects.

atropinism (at′ro-pin-izm)
Symptoms of poisoning by atropine or belladonna.

atropinization (at-ro′pin-i-za′shun)
Administration of atropine or belladonna to the point of achieving the pharmacologic effect.

atroscine
dl-Scopolamine. See scopolamine. [atropine + hyoscine]

atrotoxin (at-ro-toks′in)
A component of diamondback rattlesnake (Crotalus atrox) venom that specifically and reversibly increases voltage-dependent calcium ion currents in isolated myocytes.

attachment (a-tach′ment)
1. A connection of one part with another. 2. In dentistry, a mechanical device for the fixation and stabilization of a dental prosthesis. bar clip attachments SYN: bar-sleeve attachments. bar-sleeve attachments fixed bar joints or rigid bar units used for splinting abutments with removable sleeves or clips within the partial denture for supporting and/or retaining the prosthesis. SYN: bar clip attachments. epithelial a. SYN: junctional epithelium. epithelial a. of Gottlieb SYN: junctional epithelium. frictional a. SYN: precision a.. internal a. SYN: precision a.. key a. SYN: precision a.. keyway a. SYN: precision a.. muscle-tendon a. the union of a muscle and tendon fiber in which sarcolemma intervenes between the two; the end of the muscle fiber may be rounded, conical, or tapered. SYN: muscle-tendon junction. parallel a. SYN: precision a.. pericemental a. the tissues surrounding the cementum of the tooth, i.e., the periodontal ligament and alveolar bone. precision a. 1. a frictional or mechanically retained unit used in fixed or removable prosthodontics, consisting of closely fitting male and female parts; 2. an a. that may be rigid in function or may incorporate a movable stress control unit to reduce the torque on the abutment. SYN: frictional a., internal a., key a., keyway a., parallel a., slotted a.. slotted a. SYN: precision a..

attack (a-tak′)
A sudden illness or an episode or exacerbation of chronic or recurrent illness. brain a. SYN: stroke (1) . drop a. an episode of sudden falling that occurs during standing or walking, without warning and without loss of consciousness, vertigo, or postictal behavior. The patients are usually elderly and have normal electroencephalograms; of unknown cause. heart a. SYN: myocardial infarction. panic a. sudden onset of intense apprehension, fear, terror, or impending doom accompanied by increased autonomic nervous system activity and by various constitutional disturbances, depersonalization, and derealization. salaam a. SYN: nodding spasm. transient ischemic a. (TIA) a sudden focal loss of neurological function with complete recovery usually within 24 hours; caused by a brief period of inadequate perfusion in a portion of the territory of the carotid or vertebral basilar arteries. uncinate a. SYN: uncinate epilepsy. vagal a. SYN: Gowers syndrome. vasovagal a. SYN: Gowers syndrome.

attar of rose (at′ar)
SYN: rose oil, oil of rose. [Pers. attara, to smell sweet]

attending (a-tend′ing)
In psychology, an aroused readiness to perceive, as in listening or looking; focusing of sense organs is sometimes involved. [L. attendo, to bend to, notice]

attenuant (a-ten′u-ant)
1. Denoting that which attenuates. 2. An agent, means, or method that attenuates.

attenuate (a-ten′u-at)
To dilute, thin, reduce, weaken, diminish. [L. at-tenuo, pp. -tenuatus, to make thin or weak, fr. tenuis, thin]

attenuation (a-ten-u-a′shun)
1. The act of attenuating. 2. Diminution of virulence in a strain of an organism, obtained through selection of variants that occur naturally or through experimental means. 3. Loss of energy of a beam of radiant energy due to absorption, scattering, beam divergence, and other causes as the beam propagates through a medium. 4. Regulation of termination of transcription; involved in control of gene expression in specific tissues. interaural a. the reduction in intensity the head provides sound presented to one ear canal before it gets to the other ear; for air conduction, the reduction approximates 35 dB, but for bone conduction, it is only about 10 dB.

attenuator (a-ten′u-a-tor, -tor)
1. An electrical system of resistors and capacitors used to reduce the strength of electrical signals as in ultrasonography. 2. The terminator sequence in DNA at which attenuation occurs.

attic (at′ik)
SYN: epitympanic recess. tympanic a. SYN: epitympanic recess.

atticomastoid (at′i-ko-mas′toyd)
Relating to the attic of the tympanic cavity and the mastoid antrum or cells.

atticotomy (at-i-kot′o-me)
Operative opening into the tympanic attic. [attic + G. tome, incision]

attitude (at′i-tood)
1. Position of the body and limbs. 2. Manner of acting. 3. In social or clinical psychology, a relatively stable and enduring predisposition or set to behave or react in a certain way toward persons, objects, institutions, or issues. [Mediev. L. aptitudo, fr. L. aptus, fit] emotional attitudes SYN: passional attitudes. fetal a. SYN: fetal habitus. passional attitudes attitudes expressive of any of the great passions; e.g., anger, lust. SYN: emotional attitudes.

attitudinal (at-i-too′di-nal)
Relating to a posture of the body; e.g., a. (statotonic) reflex.

atto- (a)
Prefix used in the SI and metric systems to signify one quintillionth (10−18). [Danish atten, eighteen]

attollens (a-tol′ens)
Raising up; in anatomy, muscle action that lifts. [L. at- tollo, pres. p. -tollens, to lift up] a. aurem, a. auriculam SYN: auricularis superior (muscle). a. oculi SYN: superior rectus (muscle).

attractin (a-trak′tin)
A glycoprotein of T cell origin involved in T cell clustering and monocyte movement.

attraction (a-trak′shun)
The tendency of two bodies to approach each other. [L. at-traho, pp. -tractus, to draw toward] capillary a. the force that causes fluids to rise up very fine tubes or pass through the pores of a loose material. chemical a. the force impelling atoms of different elements or molecules to unite to form new substances or compounds. magnetic a. the force that draws iron or steel toward a magnet. neurotropic a. the pull of a regenerating axon toward the motor end-plate.

attrahens (at′ra-henz)
Drawing toward, denoting a muscle (a. aurem or auriculam) rudimentary in man, that tends to draw the pinna of the ear forward. See auricularis anterior (muscle). [see attraction]

attrition (a-trish′un)
1. Wearing away by friction or rubbing. 2. In dentistry, physiological loss of tooth structure caused by the abrasive character of food or from bruxism. Cf.:abrasion. [L. at-tero, pp. -tritus, to rub against, rub away]

at. wt.
Abbreviation for atomic weight.

atypia (a-tip′e-a)
State of being not typical. SYN: atypism.

atypical (a-tip′i-kal)
Not typical; not corresponding to the normal form or type. [G. a- priv. + typikos, conformed to a type]

atypism (a-tip′izm)
SYN: atypia.

A.U.
Abbreviation for auris uterque [L.], each ear or both ears.

Au
Symbol for gold (aurum).

Aub
Joseph C., U.S. physician, 1890–1973. See A.-DuBois table.

Auberger blood group, Au blood group
See Blood Groups appendix.

Aubert
Hermann, German physiologist, 1826–1892. See A. phenomenon.

AUC
Area under the plasma drug concentration vs. time curve; a measure of drug exposure. [abbr. area under the curve]

Auchmeromyia (awk′mer-o-mi′ya)
A genus of bloodsucking botflies (family Calliphoridae, order Diptera). [G. auchmeros, without rain, hence unwashed, squalid, + myia, a fly] A. luteola the Congo floor maggot; the bloodsucking larva of this botfly species is found in Africa south of the Sahara, usually in or near human habitations; the resistant larvae or maggots crawl to sleeping humans and suck blood for 15 to 20 minutes, detach, and hide, repeating these nightly attacks during their developmental period; no disease transmission is known from this insect.

198Au colloid
SYN: radiogold colloid.

audile (aw′dil)
1. Relating to audition. 2. Denoting the type of mental imagery in which one recalls most readily that which has been heard rather than seen or read ( i.e., having an auditory representational system). Cf.:motile. 3. SYN: auditive.

audio-
The sense of hearing. [L. audio, to hear]

audioanalgesia (aw′de-o-an-al-je′ze-a)
Use of music or sound delivered through earphones to mask pain during dental or surgical procedures.

audiogenic (awd′e-o-jen′ik)
Caused by sound, especially a loud noise. [audio- + G. genesis, production]

audiogram (aw′de-o-gram)
The graphic record drawn from the results of hearing tests with an audiometer, which charts the threshold of hearing at various frequencies against sound intensity in decibels. [audio- + G. gramma, a drawing] pure tone a. a chart of the threshold for hearing at various frequencies usually expressed in decibels relative to normal threshold and usually covering frequencies from 250–8000 Hz. speech a. the record of thresholds for spondaic word lists and scores for phonetically balanced word lists.

audiologist (aw-de-ol′ojist)
A specialist in evaluation and rehabilitation of those whose communication disorders stem in whole or in part from hearing impairment.

audiology (aw-de-ol′o-je)
The study of hearing disorders through the identification and measurement of hearing impairment as well as the rehabilitation of persons with hearing impairments.

audiometer (aw-de-om′e-ter)
An electronic device used in measuring the threshold of hearing for pure tones of frequencies generally varying from 125–8000 Hz and speech (recorded in terms of decibels). [audio- + G. metron, measure] automatic a. SYN: Békésy a.. Békésy a. an automatic a. in which the tone sweeps the audiometric scale while the patient controls intensity by pressing a button when the tone is heard and releases when tone cannot be heard; may be operated either at a fixed frequency or at steadily changing frequencies. SYN: automatic a.. pure-tone a. an a. that generates pure tones of selected frequencies with varying intensity. The stimuli are delivered by air conduction and bone conduction to differentiate conductive, sensorineural, or mixed hearing loss. speech a. an a. that provides spoken material at controlled sound pressure levels to obtain speech reception thresholds, tolerance for loud speech, and discrimination ability, using either a live voice with a microphone or a recorded voice. It provides a measurement of overall performance in hearing, understanding, and responding to speech and an estimate of the degree of hearing disability.

audiometric (aw′de-o-met′rik)
Related to measurement of hearing levels or to an audiometer.

audiometrist (aw-de-om′e-trist)
A person trained in the use of an audiometer in testing hearing.

audiometry (aw-de-om′e-tre)
1. The measurement of hearing. 2. The use of an audiometer. 3. Rapid measurement of the hearing of an individual or a group against a predetermined limit of normalcy; auditory responses to different frequencies presented at a constant intensity level are tested. SYN: screening a.. automatic a. a. in which the subject controls increases and decreases in intensity at a fixed frequency or more usually as the frequency of the stimulus is gradually changed so that the subject traces back and forth across the threshold of hearing. SYN: Békésy a.. behavioral observation a. a method of observing the motor responses of young children to test sound intensities to determine the hearing threshold. Békésy a. SYN: automatic a.. cortical a. measurement of the potentials that arise in the auditory system above the level of the brainstem. diagnostic a. measurement of hearing threshold levels to determine the nature and degree of hearing impairment ( i.e., conductive, sensorineural, or mixed). screening a. SYN: a. (3) .

audiovisual (aw′de-o-vizh′u-al)
Pertaining to a communication or teaching technique that combines both audible and visible symbols.

audit
An examination or review that establishes the extent to which a condition, process, or performance conforms to predetermined standards or criteria. [L. auditus, a hearing, fr. audio, to hear]

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