Medical Dictionary

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argipressin (ar-ji-pres′in)
SYN: arginine vasopressin.

argon (Ar) (ar′gon)
A gaseous element, atomic no. 18, atomic wt. 39.948, present in the dry atmosphere in the proportion of about 0.94%; one of the noble gases. [G. ntr. of argos, lazy, inactive, fr. a- priv. + ergon, work]

Argyll Robertson
Douglas, Scottish ophthalmologist, 1837–1909.

argyria (ar-jir′e-a, -ji′re-a)
A slate-gray or bluish discoloration of the skin and deep tissues, due to the deposit of insoluble albuminate of silver, occurring after the medicinal administration for a long period of a soluble silver salt; formerly fairly common from use of proprietary preparations of silver-containing materials in the nose and sinuses. SYN: argyrism, silver poisoning. [G. argyros, silver]

argyric (ar-jir′ik)
1. SYN: argentic (1) . 2. Relating to argyria.

argyrism (ar′ji-rizm)
SYN: argyria.

argyrol
SYN: mild silver protein.

argyrophil, argyrophile (ar-ji′ro-fil, -fil)
Pertaining to tissue elements that are capable of impregnation with silver ions and being made visible after an external reducing agent is used. SYN: argentophil, argentophile. [G. argyros, silver, + philos, fond]

arhinia (a-rin′e-a)
Congenital absence of the nose. SYN: arrhinia.

Arias-Stella
Javier, Peruvian pathologist, *1924. See Arias-Stella effect, Arias-Stella phenomenon, Arias-Stella reaction.

ariboflavinosis (a-ri′bo-fla-vi-no′sis)
Properly hyporiboflavinosis: a nutritional condition produced by a deficiency of riboflavin in the diet, characterized by cheilosis and magenta tongue and usually associated with other manifestations of B vitamin deficiency.

aristolochic acid (a-ris-to-lo′kik)
An aromatic bitter derived from plants of the genus Aristolochia.

aristotelian (ar′is-to-te′le-an, ar′i-sto-tel′yan)
Attributed to or described by Aristotle.

Aristotle
Of Stagira, Greek philosopher and scientist, 384–322 B.C. See A. anomaly, aristotelian method.

arithmomania (a-rith-mo-ma′ne-a)
A morbid impulse to count. [G. arithmeo, to count, fr. arithmos, number, + mania, madness]

Arizona (ar′i-zo′na)
Former name for Salmonella enterica, subspecies arizonae. A. hinshawii former name for Salmonella enterica subsp. arizonae.

Arlt
Carl Ferdinand von, Austrian ophthalmologist, 1812–1887. See A. operation, A. sinus.

arm [TA]
1. A., specifically the segment of the upper limb between the shoulder and the elbow; commonly used to mean the whole superior limb. SYN: brachium (1) [TA] , brachio-. 2. An anatomic extension resembling an a.. 3. A specifically shaped and positioned extension of a removable partial denture framework. 4. One set of cases or persons in an epidemiologic study, especially a randomized controlled trial, in which comparisons or contrasts are being made between sets. [L. armus, forequarter of an animal; G. harmos, a shoulder joint] bar clasp a. a clasp a. which has its origin in the denture base or major connector; it consists of the a. which traverses but does not contact the gingival structures, and a terminal end which approaches its contact with the tooth in a gingivo-occlusal direction. brawny a. a swollen a. caused by lymphedema, can be seen after ipsilateral radical mastectomy. circumferential clasp a. a clasp a. which has its origin in a minor connector and which follows the contour of the tooth approximately in a plane perpendicular to the path of insertion of the partial denture. clasp a. a portion of a clasp of a removable partial denture which projects from the clasp body and helps retain the partial denture in position in the mouth. See clasp (2) . dynein a. a structure extending clockwise from one tubule of each of the 9 doublet microtubules toward the adjacent doublet seen in the axoneme of cilia or flagella (including human sperm tails); congenital absence of dynein, reflected structurally by absence of dynein arms, can account for symptoms seen in Kartagener syndrome, an immotile cilia syndrome. nuchal a. situation in vaginal breech delivery during which one or both arms are found around the back of the neck, interfering with delivery. reciprocal a. a clasp a. or other extension used on a removable partial denture to oppose the action of some other part or parts of the appliance. retentive a., retention a. a flexible segment of a removable partial denture that engages an undercut on an abutment and is designed to retain the denture. retentive circumferential clasp a. an a. that is flexible and engages the infrabulge at the terminal end of the a.. stabilizing circumferential clasp a. an a. that is relatively rigid and embraces the height of contour of the tooth.

armamentarium (ar′ma-men-tar′e-um)
All the therapeutic means available to the health practitioner for professional practice. [L. an arsenal, fr. armamenta, implements, tackle, fr. arma, armor, arms]

Armanni
Luciano, Italian pathologist, 1839–1903. See A.-Ebstein kidney, A.-Ebstein change.

armarium (ar-mar′e-um)
Rarely used term for the physician's library, as part of her or his armamentarium. [L. a closet, chest, fr. arma, armor]

Armillifer (ar-mil′i-fer)
A genus of Pentastomida (order Porocephalida, family Porocephalidae); adults are found in the lungs of reptiles and the young in many mammals, including humans. [O. Fr. armille, fr. L. armilla, a bracelet] A. armillatus species occurring in the python, the larva or nymph being occasionally found in humans. SYN: Porocephalus armillatus.

Armitage
Peter, British statistician, (1924-). See A.-Doll model.

armpit
SYN: axilla.

Armstrong
Arthur Riley, Canadian physician, *1904. See King-A. unit.

Armstrong
Henry E., British physician.

ARN
Acronym for acute retinal necrosis.

Arndt
Rudolph G., German psychiatrist, 1835–1900. See A. law.

Arneth
Joseph, German physician, 1873–1956. See A. classification, A. count, A. formula, A. index, A. stages, under stage.

arnica (ar′ni-ka)
The dried flower heads of A. montana (family Compositae); Obsolete cardiac sedative seldom given internally; used externally for sprains and bruises; formerly widely used as a counterirritant liniment. SYN: leopard's bane. [Mod. L.]

Arnold
Julius, German pathologist, 1835–1915. See A. bodies, under body, A.-Chiari deformity, A.-Chiari malformation, A.-Chiari syndrome.

Arnold
Friedrich, German anatomist, 1803–1890. See A. bundle, A. canal, A. ganglion, A. nerve, A. tract, foramen of A..

aromatic (ar-o-mat′ik)
1. Having an agreeable, somewhat pungent, spicy odor. 2. One of a group of vegetable drugs having a fragrant odor and slightly stimulant properties. 3. See a. compound. [G. aromatikos, fr. aroma, spice, sweet herb]

aromatic d-amino acid decarboxylase
An enzyme that catalyzes the decarboxylation of l-dopa to dopamine, of l-tryptophan to tryptamine, and of l-hydroxytryptophan to serotonin; important in the biosynthetic pathway of catecholamines and melanin. SYN: dopa decarboxylase, hydroxytryptophan decarboxylase, tryptophan decarboxylase.

arotinoid (a-rot′in-oyd)
A synthetic polyaromatic retinoid derivative of vitamin A. SEE ALSO: retinoid, retinoic acid. [aromatic + retinoid]

aroyl (a′ro-il)
The radical of an aromatic acid ( e.g., benzoyl); analogous to acyl, the more general term.

arrack (a-rak′)
A strong alcoholic liquor distilled from dates, rice, sap of the coconut palm, and other substances. [Ar. sweet juice]

arrector, pl .arrectores (a-rek′tor, a-rek-to′rez)
SYN: erector. [L. that which raises, fr. ar-rigo, pp. -rectus, to raise up]

arrest (a-rest′)
1. To stop, check, or restrain. 2. A stoppage; interference with, or checking of, the regular course of a disease, a symptom, or the performance of a function. 3. Inhibition of a developmental process, usually at the ultimate stage of development; premature a. may lead to a congenital abnormality. [O. Fr. arester, fr. LL. adresto, to stop behind] cardiac a. (CA) complete cessation of cardiac activity either electric, mechanical, or both; may be purposely induced for therapeutic reasons. SYN: heart a.. cardioplegic a. temporary intentional stoppage of electrical and mechanical cardiac activity, usually by potassium-containing solutions, used to protect heart muscle by decreasing its metabolic demand during open-heart surgery with cardiopulmonary bypass. cardiopulmonary a. an a. resulting in absence of cardiac and pulmonary activity. circulatory a. 1. cessation of the circulation of blood as a result of ventricular standstill or fibrillation. 2. intentional cessation of circulation by temporarily stopping cardiopulmonary bypass flow during certain thoracic aortic operations; used with intentional profound total-body hypothermia to protect vital organs. deep hypothermic a. stoppage of electrical and mechanical cardiac activity that occurs when the heart is cooled. epiphysial a. early and premature fusion between epiphysis and diaphysis. heart a. SYN: cardiac a.. a. of labor absence of progress of active labor (as defined by cervical dilation and descent of the presenting part) for 2 hr or longer. maturation a. cessation of complete differentiation of cells at an immature stage; in spermatogenic maturation a., the seminiferous tubules contain spermatocytes, but no spermatozoa develop. sinus a. cessation of sinus activity; the ventricles may continue to beat under ectopic atrial, A-V junctional, or idioventricular control. SEE ALSO: sinus standstill, atrial standstill.

arrhaphia
SYN: status dysraphicus.

arrhenic (a-ren′ik)
Relating to arsenic. [G. arrhenikon (var.), arsenic]

Arrhenius
Svante, Swedish chemist and Nobel laureate, 1859–1927. See A. doctrine, A. equation, A. law, A.-Madsen theory.

arrhenoblastoma (a-re′no-blas-to′ma)
SYN: Sertoli-Leydig cell tumor. [G. arrhen, male, + blastos, germ, + -oma, tumor]

arrhinencephaly, arrhinencephalia, arhinencephaly (a-rin-en-sef′a-le, -se-fa′le-a)
Congenital absence or rudimentary state of the rhinencephalon, or olfactory lobe of the brain, on one or both sides, with a corresponding lack of development of the external olfactory organs. [G. a- priv. + rhis (rhin-), nose, + enkephalos, brain]

arrhinia (a-rin′e-a)
SYN: arhinia. [G. a- priv. + rhis (rhin-), nose]

arrhythmia (a-rith′me-a)
Loss or abnormality of rhythm; denoting especially an irregularity of the heartbeat.rhythm. Cf.:dysrhythmia. [G. a- priv. + rhythmos, rhythm] cardiac a. cardiac dysrhythmia. continuous a. obsolete term for atrial fibrillation. juvenile a. SYN: sinus a.. nonphasic sinus a. sinus a. in which variations in rhythm are not related to the phases of respiration. phasic sinus a. sinus a. in which the irregularity is related to the phases of respiration, the rate being faster in inspiration and slower in expiration. respiratory a. phasic sinus a. or any other rhythm fluctuation induced by respiratory fluctuation. sinus a. rhythmic, repetitive irregularity of the heartbeat, the heart being under the control of its normal pacemaker, the sinoatrial node. SYN: juvenile a..

arrhythmic (a-ridh′mik, a-)
Marked by loss of rhythm; pertaining to arrhythmia.

arrhythmogenic (a-ridh-mo-jen′ik)
Capable of inducing cardiac arrhythmias. [G. a- priv. + rhythmos, rhythm, + -gen, production]

arrowroot (ar′o-root)
The rhizome of Maranta arundinacea, a plant of tropical America, which is the source of a form of starch formerly used as a dietary supplement.

Arruga
Count Hermenegildo, Spanish ophthalmologist, 1886–1972. See A. forceps.

arsacetin (ar-sa-se′tin)
Formerly used as an antisyphilitic agent.

arsenamide (ar-sen′a-mid)
Used in the treatment of filariasis.

arsenate (ar′se-nat)
A salt of arsenic acid.

arseniasis (ar-sen-i′a-sis)
Chronic arsenical poisoning. SYN: arsenicalism.

arsenic1 (ar-sen′ik)
Denoting the element a. or one of its compounds, especially a. acid.

arsenic (As) (ar′se-nik)
A metallic element, atomic no. 33, atomic wt. 74.92159; forms a number of poisonous compounds, some of which are used in medicine. SYN: arsenium, ratsbane. [L. arsenicum, G. arsenikon, fr. Pers. zarnik] a. acid the hydrate of a. oxide or a. pentoxide which forms arsenates with certain bases. a. trihydride SYN: arsine. a. trioxide As2O3;dissolves in water to give arsenous acid, H3AsO3; used in the treatment of skin diseases and malaria, and as a tonic; also used externally as a caustic. SYN: arsenous oxide, white a.. white a. SYN: a. trioxide.

arsenical (ar-sen′i-kal)
1. A drug or agent, the effect of which depends on its arsenic content. 2. Denoting or containing arsenic.

arsenicalism (ar-sen′i-kal-izm)
SYN: arseniasis.

arsenic-fast
Resistant to the poisonous action of arsenic; denoting especially spirochetes and other protozoan parasites, which acquire resistance after repeated administration of the drug.

arsenide (ar′se-nid)
A compound of arsenic with a metal or other positively charged atoms or groups in which the arsenic is not bound to any atoms of oxygen. SYN: arseniuret.

arsenious (ar-sen′e-us)
Arsenic (adj.).

arsenium (ar-se′ne-um)
SYN: arsenic.

arseniuret (ar-se′nu-ret)
SYN: arsenide.

arsenotherapy (ar′sen-o-thar′a-pe)
Therapeutic treatment with arsenic.

arsenous (ar′-sen-us)
1. Denoting a compound of arsenic with a valence of +3. 2. Arsenic (adj.).

arsenous acid
See arsenic trioxide.

arsenous hydride
SYN: arsine.

arsenous oxide
SYN: arsenic trioxide.

arsenoxides (ar-se-nok′i-des)
Oxidation products in the body of arsphenamines; believed to be the agents active against spirochetes.

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