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

amebic (a-me′bik)
Relating to, resembling, or caused by amebas.

amebicidal (a-me-bi-si′dal)
Destructive to amebas.

amebicide (a-me′bi-sid)
Any agent that causes the destruction of amebas. SYN: amebacide. [ameba + L. caedo, to kill]

amebiform (a-me′bi-form)
Of the shape or appearance of an ameba. [ameba + L. forma, shape]

amebiosis (a-me-bi-o′sis)
Obsolete term for amebiasis.

amebism (a-me′bizm)
Obsolete term for amebiasis.

amebocyte (a-me′bo-sit)
1. A wandering cell found in invertebrates. 2. Obsolete term for leukocyte. 3. An in vitro tissue culture leukocyte. [ameba, + kytos, cell]

ameboid (a-me′boyd)
1. Resembling an ameba in appearance or characteristics. 2. Of irregular outline with peripheral projections; denoting the outline of a form of colony in plate culture. [ameba + G. eidos, appearance]

ameboididity (a-me-boy-did′i-te)
The power of locomotion after the manner of an ameboid cell. SYN: amebaism (2) .

ameboidism (a-me′boyd-izm)
1. The performance of movements similar to those of an ameba. SYN: amebaism (1) . 2. Denoting a condition sometimes seen in certain nerve cells.

ameboma (a-me-bo′ma)
A nodular, tumorlike focus of proliferative inflammation sometimes developing in chronic amebiasis, especially in the wall of the colon. SYN: amebic granuloma. [ameba + G. -oma, tumor]

amebula, pl .amebulae (a-me′bu-la, -le)
Term applied to the excysted young amebas of Entamoeba species that emerge from the cyst in the human or vertebrate gut and their immediate progeny, usually totalling eight, prior to their localization in the large intestine. [fr. G. amoibe, a change, alteration]

amebule (a-me′bul)
A minute ameba.

ameburia (am-e-bu′re-a)
The presence of amebas in the urine. [ameba + G. ouron, urine]

amelanotic (a-mel-a-not′ik)
Lacking in melanin. [G. a- priv. + melas, black]

amelia (a-me′le-a)
Congenital absence of a limb or limbs. Autosomal dominant, autosomal recessive, and X-linked forms have been reported, but most cases are sporadic. [G. a- priv. + melos, a limb]

amelioration (a-mel-yo-ra′shun)
Improvement; moderation in the severity of a disease or the intensity of its symptoms. [L. ad, to, + melioro, to make better]

ameloblast (a-mel′o-blast, am-e-lo′blast)
One of the columnar epithelial cells of the inner layer of the enamel organ of a developing tooth, concerned with the formation of enamel matrix. SYN: enamel cell, enameloblast, ganoblast. [Early E. amel, enamel, + G. blastos, germ]

ameloblastoma (am′e-lo-blas-to′ma)
A benign odontogenic epithelial neoplasm that histologically mimics the embryonal enamel organ but does not differentiate to the point of forming dental hard tissues; it behaves as a slowly growing expansile radiolucent tumor, occurs most commonly in the posterior regions of the mandible, and has a marked tendency to recur if inadequately excised. [ameloblast + G. -oma, tumor] pigmented a. SYN: melanotic neuroectodermal tumor of infancy. pituitary a. SYN: craniopharyngioma.

amelodentinal (am′e-lo-den′ti-nal)
SYN: dentinoenamel.

amelogenesis (am′e-lo-jen′e-sis)
The deposition and maturation of enamel. SYN: enamelogenesis. a. imperfecta a group of hereditary ectodermal disorders in which the enamel is defective in structure or deficient in quantity. Three major groups are recognized: hypoplastic types, with defective enamel matrix deposition but normal mineralization; hypomineralization types, with normal matrix but defective mineralization; and hypomaturation type, in which the enamel crystallites remain immature. The several types may be inherited as autosomal dominant [MIM*104500, 104510, 104530], recessive [MIM*204650, 204690, 204700] or X-linked [MIM*301100, 301200, 301201]. SYN: enamel dysplasia, enamelogenesis imperfecta.

amelogenins (am′el-o-jen′inz)
A class of proteins that form much of the organic matrix during the early development of tooth enamel. [amelogenesis + -in]

amenia (a-me′ne-a)
Rarely used term for amenorrhea. [G. a- priv. + men, month]

amenorrhea (a-men-o-re′a)
Absence or abnormal cessation of the menses. [G. a- priv. + men, month, + rhoia, flow] dietary a. loss of menstrual function due to severe weight loss or gain. emotional a. a. caused by a strong emotional disturbance, e.g., fright, grief. exercise-induced a. temporary cessation of menstrual function due to strenuous, daily exercise, as in jogging, increased endorphins inhibiting hypothalamic function. hyperprolactinemic a. a. associated with abnormally high levels of serum prolactin; may be accompanied by unphysiological lactation. hypophysial a. a. due to inadequate gonadotrophic secretions by the anterior lobe of the hypophysis. hypothalamic a. secondary a. arising from defective hypothalamic stimulation of the anterior lobe of the pituitary. lactation a. physiological suppression of menses while nursing. ovarian a. a. due to deficiency of estrogenic hormone production by ovary. often referred to menopause if permanent. pathologic a. a. due to organic disease, either uterine or other, e.g., ovarian or pituitary failure. physiologic a. a. of pregnancy or the menopause, not associated with an organic disorder. postpartum a. permanent a. following childbirth resulting from Sheehan syndrome. See Sheehan syndrome. primary a. a. in which the menses have never occurred. secondary a. a. in which the menses appeared at puberty but subsequently ceased. traumatic a. absence of menses because of endometrial scarring or cervical stenosis resulting from injury or disease. SYN: Asherman syndrome.

amenorrheal, amenorrheic (a-men-o-re′al, -re′ik)
Relating to, accompanied by, or due to amenorrhea.

amentia (a-men′she-a)
1. SYN: mental retardation. 2. SYN: dementia. [L. madness, fr. ab, from, + mens, mind] nevoid a. SYN: Brushfield-Wyatt disease. phenylpyruvic a. a. accompanied by the appearance of phenylpyruvate in the urine.

amential (a-men′she-al)
Pertaining to amentia.

American Law Institute formulation
Used in certain jurisdictions to determine criminal responsibility in legal proceedings. See criminal insanity.

American Law Institute rule
See under rule.

American National Standards Institute (ANSI)
Organization that sets standards for physical measures in the United States.

American Red Cross
The national Red Cross society of the United States, established by Congress to assist in caring for the sick and wounded, serving as a communications link between members of the U.S. armed forces and their families, conducting disaster relief and prevention programs, and furnishing other humanitarian services, the largest of which is a network of regional blood centers providing blood and blood products.

americium (Am) (am′e-ris′e-um)
An element obtained by the bombardment of uranium with neutrons or β decay of plutoniums 241, 242, and 243; atomic no. 95; atomic weight 243.06. 241Am (half-life of 432.2 years) has been used in the diagnosis of bone disorders. 243Am has a half-life of 7370 years. [the Americas]

amerism (am′er-izm)
The condition or quality of not dividing into parts, segments, or merozoites. [G. a- priv. + meros, part]

ameristic (am-e-ris′tik)
Endowed with amerism; not dividing into parts or segments.

Ames
Bruce N., U.S. molecular geneticist, *1928. See A. assay, A. test.

amethopterin (a-meth-o-ter′in, am-e-thop′te-rin)
SYN: methotrexate.

ametria (a-me′tre-a)
Congenital absence of the uterus; the genetics is obscure. [G. a- priv. + metra, uterus]

ametriodinic acid (a′me-tri-o-din′ik)
SYN: iodamide.

ametropia (am-e-tro′pe-a)
The optic condition in which there is an error of refraction so that with the eye at rest the retina is not in conjugate focus with light rays from distant objects, i.e., only less distant objects are focused on the retina. [G. ametros, disproportionate, fr. a- priv. + metron, measure, + ops, eye] axial a. that resulting from a shortening or lengthening of the eyeball on the optic axis, causing hyperopia or myopia, respectively. index a. that resulting from alteration in the refractive index of the lens of the eye. SYN: refractive a.. refractive a. SYN: index a..

ametropic (am-e-tro′pik)
Relating to, or suffering from, ametropia.

amiantaceous (am′i-an-ta′shus)
Asbestos-like; describing thin plates of inflammatory crusting of a cutaneous lesion. [G. amiantus, asbestos]

amianthoid (am-i-an′thoyd)
Having a crystalline appearance like asbestos. SYN: asbestoid. [G. amianthus, asbestos]

-amic
Chemical suffix denoting the replacement of one COOH group of a dicarboxylic acid by a carboxamide group (&cbond;CONH2); applied only to trivial names ( e.g., succinamic acid).

amicrobic (a-mi-kro′bik)
Not microbic; not related to or caused by microorganisms.

amicroscopic (a′mi-kro-skop′ik)
SYN: submicroscopic.

amidase (am′i-das)
An enzyme that catalyzes the hydrolysis of monocarboxylic amides to free acid plus NH3; ω-a. acts on amides such as α-ketoglutaramic acid and α-ketosuccinamic acid.

amidases
SYN: amidohydrolases.

amide (am′id, am′id)
A substance formally derived from ammonia through the substitution of one or more of the hydrogen atoms by acyl groups, R&cbond;CO&cbond;NH2, or from a carboxylic acid by replacement of a carboxylic OH by NH2. Replacement of one hydrogen atom constitutes a primary a.; that of two hydrogen atoms, a secondary a.; and that of three atoms, a tertiary a.. substituted a. a secondary or tertiary a.; peptide linkages are substituted amides.

amidine (am′i-din)
The monovalent radical —C(NH)-NH2.

amidinohydrolases (am′i-din-o-hi′dro-las-ez) [EC 3.5.3.x]
Enzymes cleaving linear amidines; e.g., arginase, creatinase.

amidinotransferases (am′i-din-o-trans′fer-as-ez) [EC 2.1.4.x]
Enzymes catalyzing a transamidination reaction ( e.g., glycine amidinotransferase). SYN: transamidinases.

amido-
Prefix denoting the amide radical, R&cbond;CO&cbond;NH&cbond; or R&cbond;SO2&cbond;NH&cbond;, etc. [am(monia) + -id(e) + -o-]

amido black 10B (am′i-do) [C.I. 20470]
An acid diazo dye, C12H14N6O9S2Na2, used as a connective tissue stain, for staining protein in paper chromatography, and in electrophoresis.

amidohydrolases (am′i-do-hi′dro-la-sez) [EC 3.5.1.x and 3.5.2.x]
Enzymes hydrolyzing C&cbond;N bonds of amides and cyclic amides; e.g., asparaginase, barbiturase, urease, amidase. SYN: amidases, deamidases, deamidizing enzymes.

amidonaphthol red (am′i-do-naf′thol) [C.I. 18050]
An azo dye, C18H13N3S2Na2, used in light and fluorescence microscopy as a real acid counterstain. SYN: azophloxin.

amidopyrine (am-i-do-pi′ren)
SYN: aminopyrine.

Amidostomum anseris (am-i-dos′to-mum an′ser-is)
A species of bloodsucking nematodes, similar to those of the genus Trichostrongylus, that parasitizes the gizzard and sometimes also the proventriculus and esophagus of domestic and wild ducks and geese; it causes heavy mortality in young birds. [amido- + G. stoma, mouth, + L. anser, goose]

amidoximes (am-i-doks′imz, -dok′semz)
The oximes of amides with the general formula, R&cbond;C(NH2)&cbond;NOH. SYN: amide oximes.

amidoxyl (am-i-dok′sil)
The radical of an amide oxime (amidoxime), the terminal H (of the NOH) having been lost.

amikacin sulfate (am-i-ka′sin)
An aminoglycoside antibiotic agent with antimicrobial activity similar to that of kanamycin; also effective against Pseudomonas aeruginosa.

amiloride hydrochloride (a-mil′o-rid)
A nonsteroidal compound exerting an effect similar to that of an aldosterone inhibitor, i.e., urinary sodium excretion is enhanced and potassium excretion is reduced; a potassium sparing diuretic.

amimia (a-mim′e-a)
1. Inability to express ideas by nonverbal communication, such as gestures or signs. 2. Asymbolia; the inability to comprehend the meaning of gestures, signs, symbols, or pantomime. [G. a- priv. + minos, a mimic]

aminacrine hydrochloride (am′i-nak′rin)
Bactericidal agent for external use. SEE ALSO: acridine yellow. SYN: 5-aminoacridine hydrochloride, 9-aminoacridine hydrochloride.

aminate (am′i-nat)
To combine with ammonia.

amination (a-me-na′shun)
The introduction of an amine moiety into a compound.

amine (a-men′, am′in)
A substance formally derived from ammonia by the replacement of one or more of the hydrogen atoms by hydrocarbon or other radicals. The substitution of one hydrogen atom constitutes a primary a., e.g., NH2CH3; that of two atoms, a secondary a., e.g., NH(CH3)2; that of three atoms, a tertiary a., e.g., N(CH3)3; and that of four atoms, a quaternary ammonium ion, e.g., +N(CH3)4, a positively charged ion isolated only in association with a negative ion. The amines form salts with acids. adrenergic a. SYN: sympathomimetic a.. adrenomimetic a. SYN: sympathomimetic a.. biogenic amines a class of compounds, each containing an a. group, produced by a living organism. This class normally does not include amino acids. a. oxidase (copper-containing) an oxidoreductase containing copper, and perhaps pyridoxal phosphate, and carrying out the same reaction as a. oxidase (flavin-containing). SYN: diamine oxidase, histaminase. a. oxidase (flavin-containing) an oxidoreductase containing flavin and oxidizing amines with the aid of O2 and water to aldehydes or ketones with the release of NH3 and H2O2. Acted upon by antidepressants. SYN: adrenaline oxidase, diamine oxidase, monoamine oxidase, tyraminase, tyramine oxidase. pressor a. SYN: pressor base. sympathetic a. SYN: sympathomimetic a.. sympathomimetic a. an agent that evokes responses similar to those produced by adrenergic nerve activity ( e.g., epinephrine, ephedrine, isoproterenol). SYN: adrenergic a., adrenomimetic a., sympathetic a.. vasoactive a. a substance, such as histamine or serotonin, that contains amino groups and is pharmacologically characterized by its action on the blood vessels (altering vascular caliber or permeability).

aminergic (a-men′er-gik)
Relating to nerve cells or fibers.

amino-
Prefix denoting a compound containing the radical, &cbond;NH2. [am(monia) + in(e) + -o-]

amino acid (AA, aa) (a-me′no)
An organic acid in which one of the hydrogen atoms on a carbon atom has been replaced by NH2. Usually refers to an aminocarboxylic acid. However, taurine is also an a.. SEE ALSO: α-a.. acidic a. an A. with a second acid moiety, e.g., glutamic acid, aspartic acid, cysteic acid. activated a. SYN: aminoacyl adenylate. basic a. an a. containing a second basic group (usually an amino group); e.g., lysine, arginine, ornithine. SYN: dibasic a.. a. dehydrogenases enzymes catalyzing the oxidative deamination of amino acids to the corresponding oxo (keto) acids; two relatively nonspecific varieties exist, l and d, for which l-amino acids and d-amino acids are the respective substrates; the products include NH3 and a reduced hydrogen acceptor (NADH in the l case); a. dehydrogenases of greater specificity exist ( e.g., glycine dehydrogenase). Cf.:a. oxidases. dibasic a. SYN: basic a.. essential amino acids α-amino acids nutritionally required by an organism and which must be supplied in its diet ( i.e., cannot be synthesized by the organism) either as free a. or in proteins. nonessential amino acids those amino acids that may be synthesized by an organism and are thus not required as such in its diet. nonpolar a. an α-a. in which the functional group attached to the α-carbon ( I.E., R in RCH(NH2)COOH) has hydrophobic properties; E.G., valine, leucine, α-aminobutyrate. a. oxidases flavoenzymes oxidizing, with O2 and H2O, either l- or d-amino acids specifically, to the corresponding 2-keto acids, NH3 and H2O2. Cf.:a. dehydrogenases, yellow enzyme. polar a. an α-a. in which the functional group attached to the α-carbon ( i.e., R in RCH(NH2)COOH) has hydrophilic properties; e.g., serine, cysteine, homocysteine.

α-amino acid
Typically, an amino acid of the general formula R&cbond;CHNH2&cbond;COOH ( i.e., the NH2 in the α position); the l forms of these are the hydrolysis products of proteins. In rarer usages, this class of molecules also includes α-amino phosphoric acids and α-aminosulfonic acids.

aminoacidemia (a-me′no-as-i-de′me-a, am′i-no-)
The presence of excessive amounts of specific amino acids in the blood. [amino acid + G. haima, blood]

aminoacid-tRNA ligases
Recommended name for aminoacyl-tRNA synthetases, e.g., tyrosine-tRNA ligase for tyrosyl-tRNA synthetase.

aminoaciduria (am′i-no-as-i-doo′re-a)
Excretion of amino acids in the urine, especially in excessive amounts. SYN: hyperaminoaciduria. [amino acid + G. ouron, urine] hyperbasic a. an inherited disorder associated with a deficiency of a dibasic amino acid transport. Individuals do not typically display protein intolerance. Cf.:lysinuric protein intolerance.

9-aminoacridine (a-me-no-ak′ri-den)
One of the acridine group of antiseptics (flavins); highly fluorescent in solution; used topically as an antiseptic.

5-aminoacridine hydrochloride, 9-aminoacridine hydrochloride
SYN: acridine yellow, aminacrine hydrochloride.

aminoacyl (AA, aa) (a-me′no-as′il)
The radical formed from an amino acid by removal of OH from a COOH group.

aminoacyl adenylate (a-me′no-as-il-a-den′i-lat)
The product formed by the condensation of the acyl radical of an amino acid and adenosine 5′-monophosphate (originally in the form of adenosine 5′-triphosphate, with elimination of a pyrophosphoric group). Formed in the first step of protein biosynthesis. SYN: activated amino acid.

aminoacylase (a-me′no-as′i-las)
An enzyme catalyzing hydrolysis of a wide variety of N-acyl amino acids to the corresponding amino acid and an acid anion. SYN: hippuricase, histozyme.

aminoacyl-tRNA
Generic term for those compounds in which amino acids are esterfied through their COOH groups to the 3′- (or 2′-) OH's of the terminal adenosine residues of transfer RNA's ( e.g., alanyl-tRNA, glycyl-tRNA); each compound involves one, or a small number, of tRNA's of specific chemical structure. Used in protein biosynthesis. aminoacyl-tRNA ligases SYN: aminoacyl-tRNA synthetases. aminoacyl-tRNA synthetases enzymes catalyzing the formation of a specific aminoacyl-tRNA from an amino acid and adenosine 5′-triphosphate with the concomitant formation of adenosine 5′-monophosphate and pyrophosphate. SYN: amino acid activating enzyme, aminoacyl-tRNA ligases.

aminoadipic δ-semialdehyde synthase
A bifunctional enzyme used in lysine degradation; it has a lysine:α-ketoglutarate reductase activity as well as a saccharopine dehydrogenase activity. A deficiency of this enzyme results in familial hyperlysinemia.

α-aminoadipic acid (Aad) (a-me′no-a-dip′ik)
2-amino-1,6-hexanedioic acid;an intermediate of lysine biosynthesis in higher fungi and bacteria, but not in algae and higher plants. Also found in the degradation of lysine in mammals.

aminobenzene (a-me′no-ben′zen)
SYN: aniline.

aminocaproic acid (a-me′no-ca-pro′ik)
An antifibrinolytic agent, used to prevent bleeding in hemophilia, and after heart and prostate surgery when plasminogen or urokinase may be activated.

aminocarbonyl (am-i-no-kar′bon-il)
SYN: carboxamide.

aminocitric acid (a-me′no-sit′rik)
Found in acid hydrolysates of ribonucleoprotein in human spleen.

2-amino-2-deoxy-d-galactose
See galactosamine.

aminoglutethimide (a-me′no-gloo-teth′i-mid)
An aromatase inhibitor used in the treatment of breast cancer; blocks the synthesis of estrogen; formerly tried as an anticonvulsant but no longer used for that purpose.

aminoglycoside (am′i-no-gli′ko-sid)
Any one of a group of bacteriocidal antibiotics derived from species of Streptomyces or Micromonosporum and characterized by two or more amino sugars joined by a glycoside linkage to a central hexose; aminoglycosides act by causing misreading and inhibition of protein synthesis on bacterial ribosomes and are effective against aerobic Gram-negative bacilli and Mycobacterium tuberculosis. Some commonly used aminoglycosides are streptomycin, neomycin, and gentamycin.

5-aminoimidazole ribose 5′-phosphate (AIR) (a-me′no-im-id-az′ol)
An intermediate in the biosynthesis of purines. SYN: 5-aminoimidazole ribotide.

5-aminoimidazole ribotide (AIR) (a-me′n′o-im-id-az′ol)
SYN: 5-aminoimidazole ribose 5′-phosphate.

5-aminoimidazole-4-N-succinocarboxamide ribonucleotide (a-me′no-im-id-az′ol)
An intermediate in purine biosynthesis.

α-aminoisobutyric acid (a-me′no-i-so-bu-ter′ik)
2-amino-2-methylpropionic acid;a synthetic amino acid useful in the study of amino acid transport across cell membranes and in the study of cytokine effects; it is not metabolized by the cell.

α-amino-β-ketoadipic acid
An intermediate of porphobilinogen synthesis formed by δ-aminolevulinic acid synthase from succinyl-CoA and glycine; it rapidly decarboxylates to δ-aminolevulinic acid.

aminolysis (am-i-nol′i-sis)
Replacement of a halogen in an alkyl or aryl molecule by an amine radical, with elimination of hydrogen halide.

aminometradine (a-me′no-met′ra-den)
SYN: aminometramide.

aminometramide (a-me′no-met′ra-mid)
Synthetic uracil derivative; an orally effective diuretic that is believed to act by inhibiting the reabsorption of sodium by the renal tubules; used in the treatment of edema due to congestive heart failure, liver disease, pregnancy, and certain drugs. SYN: aminometradine.

6-aminopenicillanic acid (6-APS) (a-me′no-pen-i-sil-an′ik)
An important precursor in the synthesis of penicillin derivatives. By itself, it has no antibiotic activity.For structure, see under penicillin in which R = H. SYN: penicin.

aminopenicillins (a-me′no-pen-i-sil′inz)
A class of penicillin-like antibiotics that chemically contain an amine group; this class includes ampicillin and amoxicillin; used in upper respiratory infections, urinary tract infections, meningitis, Salmonella infections.

aminopeptidase (cytosol)
An enzyme of broad specificity, containing zinc, and catalyzing the hydrolysis of the N-terminal amino acid of a peptide ( i.e., an exopeptidase).

aminopeptidase (microsomal)
An aminopeptidase of broad specificity, but preferring alanine and discriminating against proline.

aminopeptidases (a-me′no-pep′ti-das-ez) [EC 3.4.11.x]
Enzymes catalyzing the breakdown of a peptide, removing the amino acid at the amino end of the chain ( i.e., an exopeptidase); found in intestinal secretions.

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