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Medical Dictionary


Alois, German neurologist, 1864–1915. See A. dementia, A. disease, A. sclerosis.

alzyme (al′zim)
Union of antibody and enzyme to form a hybrid catalytic molecule.

Symbol for americium.

Abbreviation for ammeter.

Abbreviation for American Medical Association.

amacrine (am′a-krin)
1. A cell or structure lacking a long, fibrous process. 2. Denoting such a cell or structure. SEE ALSO: a. cell. [G. a- priv. + makros, long, + is (in-), fiber]

amadou (ahm′ah-doo)
SYN: agaric. [Fr.]

amalgam (a-mal′gam)
An alloy of an element or a metal with mercury. In dentistry, primarily of two types: silver-tin alloy, containing small amounts of copper, zinc and perhaps other metals, and a second type containing more copper (12 to 30% by weight); they are used for restoring teeth and making dies. [G. malagma, a soft mass] pin a. an a. restoration held in place largely by small metal rods protruding from holes drilled into tooth structure. spherical a. an alloy for dental a. composed of spherical particles instead of filings.

amalgamate (a-mal′ga-mat)
To make an amalgam.

amalgamation (a-mal-ga-ma′shun)
The process of combining mercury with a metal or an alloy to form a new alloy.

amalgamator (a-mal′ga-ma-tor)
A device for combining mercury with a metal or an alloy to form a new alloy.

Amanita (am-a-ni′ta)
A genus of fungi, many members of which are highly poisonous. [G. amanitai, fungi] A. muscaria a toxic species of mushroom with yellow to red pileus and white gills; it contains muscarine, a cholinomimetic, which produces psychosislike states and other symptoms. SYN: fly agaric. A. phalloides a species containing poisonous principles, including phalloidin and amanitin, that cause gastroenteritis, hepatic necrosis, and renal necrosis. SYN: deadly agaric.

α-amanitin (am-a-ni′tin)
A highly toxic, heat-stable bicyclic oligopeptide in Amanita phalloides. It inhibits transcription by certain RNA polymerases.

amantadine hydrochloride (a-man′ta-den)
An antiviral agent used for influenza; also used to treat parkinsonism where it increases dopamine release and reduces its reuptake into dopaminergic nerve terminals of substantia nigra neurons.

amara (a-mah′ra)
SYN: bitters (2) . [neut. pl. of L. amarus, bitter]

amaranth, amaranthum (am′a-ranth, am-a-ran′thum) [C.I. 16185]
An azo dye; a soluble reddish brown powder, the color turning to magenta red in solution; used as a food, pharmaceutical, and cosmetic coloring agent, and occasionally in histology. [G. amaranthon, a never-fading flower]

amarine (am′a-rin)
A name applied to various bitter principles derived from plants, especially to a poisonous substance, 2,4,5-triphenylimidazoline, obtained from oil of bitter almond. [L. amarus, bitter]

amaroid (am′a-royd)
A bitter extractive that does not belong to the class of glycosides, alkaloids, or any of the known proximate principles of plants. [L. amarus, bitter, + G. eidos, like]

amaroidal (am-a-roy′dal)
Resembling bitters; having a slightly bitter taste.

amarum (a-mah′rum)
One of a class of vegetable drugs of bitter taste, such as gentian and quassia, used as appetizers and tonics. [neut. of L. amarus, bitter]

amastia (a-mas′te-a)
Absence of the breasts. [G. a- priv. + mastos, breast]

amastigote (a-mas′ti-got)
SYN: Leishman-Donovan body. [G. a- priv. + mastix, whip]

amathophobia (a-math-o-fo′be-a)
Morbid dread of dust or dirt. [G. amathos, dust, + phobos, fear]

amatoxin (am-a-tok′sin)
One of a group of bicyclic octapeptides from death-cap fungus and deadly agaric (Amanita phalloides).

amaurosis (am-aw-ro′sis)
Blindness, especially that occurring without apparent change in the eye itself, as from a brain lesion. [G. amauros, dark, obscure, + -osis, condition] a. congenita of Leber [MIM*204000 & MIM*204100] a disorder of cone-rod abiotrophy causing blindness or severely reduced vision at birth; autosomal recessive inheritance with at least 3 different loci. Type I is caused by mutation in the gene for retinal guanylate cyclase (GUC2D) on chromosome 17p, type II by mutation in the gene for retinal pigment epithelium-specific 65-kD protein (RPE65) on 1p, and type III by mutation in the gene for photoreceptor-specific homeobox gene CRX on 19q. a. fugax a transient blindness that may result from a transient ischemia due to carotid artery insufficiency, retinal artery embolus, or to centrifugal force (visual blackout in flight). pressure a. loss of vision occurring a few seconds after intraocular pressure exceeds systolic pressure of retinal arteries. toxic a. blindness due to optic neuritis caused by methyl alcohol, lead, arsenic, quinine, or other poisons.

amaurotic (am-aw-rot′ik)
Relating to or suffering from amaurosis.

amaxophobia (a-mak-so-fo′be-a)
Rarely used term for morbid fear of, or of riding in, a vehicle. [G. amaxa, hamaxa, a carriage, + phobos, fear]

ambageusia (am-ba-goo′se-a)
Loss of taste from both sides of the tongue. [L. ambo, both, + G. a- priv. + geusis, taste]

ambenonium chloride (am-be-no′ne-um)
A cholinesterase inhibitor similar to neostigmine in actions; used chiefly in the management of myasthenia gravis and occasionally for intestinal and urinary tract obstruction.

AMBER (am′ber)
Acronym for advanced multiple-beam equalization radiography.

amber (am′ber)
1. A hard, dark yellow to tan, fossilized resin derived from pine trees. 2. See a. codon. [Ar. anbar]

Emil, U.S. otologist, 1868–1948. See A. lateral sinus line.

ambergris (am′ber-gris)
A grayish pathologic secretion from the intestine of the sperm whale that occurs as a flammable waxy mass (melting point about 60°C), insoluble in water; contains cholesterol and benzoic acid, and is used as a base for perfume. [Mod. L. ambra grisea, gray amber]

Around; on all (both) sides; both, double; corresponds to G. amphi-. SEE ALSO: ambo-. [L., around, about, akin to ambo, both]

ambidexterity (am-bi-deks-ter′i-te)
The ability to use both hands with equal ease. SYN: ambidextrism.

ambidextrism (am-bi-deks′trizm)
SYN: ambidexterity.

ambidextrous (am-bi-deks′trus)
Having equal facility in the use of both hands.

ambient (am′be-ent)
Surrounding, encompassing; pertaining to the environment in which an organism or apparatus functions. [L. ambiens, going around]

ambiguity (am-bi-goo′i-te)
Condition of being ambiguous; uncertainty. genital a. incomplete development of fetal genitalia as a result of excessive androgen action on a female fetus or inadequate amounts of androgen in a male fetus. SYN: ambiguous external genitalia, ambiguous genitalia.

ambiguous (am-big′u-us)
1. Having more than one interpretation. 2. In anatomy, wandering; having more than one direction. 3. In neuroanatomy, applied to a nucleus (nucleus ambiguus) supplying special visceral efferent fibers to vagus and glossopharyngeal nerves. [L. ambiguus, fr. ambigo, to wander]

ambilateral (am-bi-lat′er-al)
Relating to both sides. [ambi- + L. latus, side]

ambilevous (am-bi-le′vus)
Awkwardness in the use of both hands. SYN: ambisinister, ambisinistrous. [ambi- + L. laevus, left]

ambisexual (am-bi-seks′u-al)
1. Denoting sexual characteristics found in both sexes, e.g., breast, pubic hair. 2. Slang term for bisexual.

ambisinister (am-bi-sin′is-ter)
SYN: ambilevous. [ambi- + L. sinister, left]

ambisinistrous (am′bi-sin′is-trus)
SYN: ambilevous.

ambivalence (am-biv′a-lens)
The coexistence of antithetical attitudes or emotions toward a given person or thing, or idea, as in the simultaneous feeling and expression of love and hate toward the same person. [ambi- + L. valentia, strength]

ambivalent (am-biv′a-lent)
Relating to or characterized by ambivalence.

ambivert (am′bi-vert)
One who falls between the two extremes of introversion and extroversion, possessing some of the tendencies of each.

Dullness, dimness; blunt, dull, dim, dimmed. [G. amblys, blunt, dulled; faint, dim]

amblygeustia (am-bli-goos′te-a)
A dimunition in the sense of taste. [ambly- + G. geusis, taste]

amblyogenic (am′ble-o-jen′ic)
Inducing amblyopia. [amblyopia + -genic]

Amblyomma (am-ble-om′a)
A genus of ornate, hard ticks (family Ixodidae) characterized by having eyes, festoons, and deeply imbedded ventral plates near the festoons in males. [ambly- + G. omma, eye, vision] A. americanum the Lone Star tick, a species that is an important pest and vector of Rocky Mountain spotted fever, found primarily in the southern United States and northern Mexico; it occurs on dogs and many other hosts, including domestic animals, birds, and humans, whom it bites in larval, nymphal, and adult stages. A. cajennense the Cayenne tick, a species that is an important pest in southern Texas, Central and South America, and the larger Caribbean islands, and a vector of Rocky Mountain spotted fever in Mexico and Central and South America; all stages attack humans and many species of domestic and wild animals. A. hebraeum the South African bont tick, an important vector of heartwater in southern Africa. A. maculatum the Gulf Coast tick, a species that is a pest of livestock in the southeastern United States. A. variegatum the tropical bont tick, a serious pest of domestic livestock and an important vector of heartwater in Africa and the Caribbean; it is closely associated with the development of severe clinical dermatophilosis in cattle in the Caribbean.

amblyopia (am-ble-o′pe-a)
Poor vision caused by abnormal development of visual areas of the brain in response to abnormal visual stimulation during early development. [G. a., dimness of vision, fr. amblys dull, + ops, eye] anisometropic a. a suppression of central vision due to an unequal refractive error (anisometropia) of at least two diopters. This induces a sufficient difference in image size (aniseikonia) that the two images cannot be fused. In order to avoid confusion, the blurrier image is suppressed. SYN: refractive a.. deprivation a. SYN: sensory a.. a. ex anopsia SYN: suppression a.. hysterical a. functional visual loss. meridional a. a. due to an uncorrected, large astigmatism during the amblyogenic period of visual development. nocturnal a. SYN: nyctalopia. nutritional a. a. resulting from lack of vitamin B–complex constituents. pattern distortion a. a. due to a blurred retinal image during the amblyogenic period of visual development. refractive a. SYN: anisometropic a.. sensory a. a suppression of central vision in an eye due to poor image formation; e.g., by a corneal scar, a cataract, or a droopy eyelid. SYN: deprivation a.. strabismic a. a suppression of central vision due to the two eyes pointing in different directions. The two scenes cannot be fused into a single image, so, to avoid confusion, one of the images is suppressed. suppression a. suppression of the central vision in one eye when the images from the two eyes are so different that they cannot be fused into one. This may be due to: 1) faulty image formation (sensory a.); 2) a large difference in refraction between the two eyes (anisometropic a.); or 3) the two eyes pointing in different directions (strabismic a.). Most suppression a. can be reversed if appropriately treated before age 6 years. SYN: a. ex anopsia. tobacco-alcohol a. an acquired optic neuropathy particularly involving the maculopapillary bundle nerve fibers associated with excessive alcohol and tobacco consumption. toxic a. toxic amaurosis.

amblyopic (am-ble-o′pik)
Relating to, or suffering from, amblyopia.

amblyoscope (am′ble-o-skop)
A reflecting stereoscope used to evaluate or simulate binocular vision. SEE ALSO: haploscope. [amblyopia + G. skopeo, to view] major a. an a. in which intensity of illumination as well as targets may be varied. Worth a. the original a.; a hand-held a. consisting of angled tubes that can be swiveled to any degree of convergence or divergence.

Around; on all (both) sides; corresponds to G. ampho-. SEE ALSO: ambi-. [L. ambo, both]

amboceptor (am′bo-sep-tor)
Ehrlich term for his concept, now obsolete, of the structure of complement-fixing antibody; now used chiefly to denote the anti-sheep erythrocyte antibody used in the hemolytic system of complement-fixation tests. [ambo- + L. capio, to take]

ambomalleal (am-bo-mal′e-al)
SYN: incudomalleal.

ambrosin (am-bro′sin)
A principle in ragweed related to absinthin.

ambucetamide (am-bu-set′a-mid)
An intestinal antispasmodic.

ambulance (am′bu-lans)
A vehicle used to transport sick or injured persons to a treatment facility. [Fr., fr. (hôpital) ambulant, mobile hospital]

ambulatory, ambulant (am′bu-la-tor-e, am′bu-lant)
Walking about or able to walk about; denoting a patient who is not confined to bed or hospital as a result of disease or surgery. [L. ambulans, walking]

ambuphylline (am-bu′fi-lin)
A diuretic and bronchodilator.

amcinonide (am-sin′o-nid)
A glucocorticoid used topically in the treatment of dermatoses.

ameba, pl .amebaeamebas (a-me′ba, -be, -baz)
Common name for Amoeba and similar naked, lobose, sarcodine protozoa.

amebacide (a-me′ba-sid)
SYN: amebicide.

amebaism (a-me′ba-izm)
1. SYN: ameboidism (1) . 2. SYN: ameboididity.

amebiasis (a-me-bi′a-sis)
Infection with the protozoon Entamoeba histolytica. [ameba + G. -iasis, condition] canine a. infection of dogs with Entamoeba histolytica acquired from humans; dogs are seldom cyst passers, and therefore are not a reservoir for human infection. a. cutis cutaneous a., appearing usually as an extension of underlying infection ( e.g., perianal or colostomy site or over a liver abscess). hepatic a. infection of the liver with Entamoeba histolytica; may occur with or without antecedent amebic dysentery. pulmonary a. infection of the lung by amebae; usually indicates extension of Entamoeba histolytica infection from abscess of liver, penetrating through the diaphragm into the lung.


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