|Medical Dictionary - Dictionary of Medicine and Human Biology|
3-methylcholanthrene, 20-methylcholanthrene (meth′il-kol-an′thren)
A highly carcinogenic hydrocarbon that can be formed chemically from deoxycholic or cholic acids, or from cholesterol; it induces the synthesis of cytochrome P-450 mRNA; the choice between 3- or 20- for the methyl group depends upon whether hydrocarbon (inner) or steroid (outer) numbering is chosen; in the latter case, the formal relationship to the cholic acids and cholesterol is clear.
A minor metabolite that accumulates in individuals with propionic acidemia.
SYN: vitamin B12.
An intermediate in the degradation of l-leucine; accumulates in a deficiency of M. carboxylase. 3-methylcrotonyl-CoA carboxylase a biotin-dependent enzyme in the pathway of l-leucine degradation that catalyzes the reaction of M. with CO2, ATP, and water to form ADP, orthophosphate, and 3-methylglutaconyl-CoA; a deficiency of this enzyme causes episodes of severe metabolic acidosis.
A minor base that is present in both bacterial and human DNA.
methyldichloroarsine (MD) (meth′il-di-klor-o-ar′sen)
A vesicant; irritating to the respiratory tract and will produce lung injury and eye injury; has been used in certain military operations.
An antihypertensive agent, also used as the ethyl ester hydrochloride, with the same action and uses. SYN: alpha methyl dopa.
The moiety, &cbond;CH2&cbond;.
SYN: azure I.
methylene blue [C.I. 52015]
A basic dye easily oxidized to azure, with dye mixtures; used in histology and microbiology, to stain intestinal protozoa in wet mount preparations, to track RNA and RNase in electrophoresis, and as an antidote for methemoglobinemia; its redox indicator properties are useful in milk bacteriology. Kühne m. m. in absolute alcohol and phenol solution. Loeffler m. a stain for diphtheria organisms that contains m. in dilute ethanol plus a slight amount of potassium hydroxide; dye solution gives best results when aged to a polychrome state. new m. [C.I. 52030] a basic thiazin dye used for supravital staining of reticulocytes in blood smears. polychrome m. an alkaline solution of m. that undergoes progressive oxidative demethylation with aging (ripening) to produce a mixture of m., azures, and methylene violet; boiling with sodium carbonate or other oxidizing agents accomplishes this result quickly, although it is not as highly regarded.
Mobile liquid with a pungent odor; harmful vapor. Organic solvent used for cellulose acetate plastic; degreasing and cleaning fluids; and in food processing. Pharmaceutical aid (solvent).
methylenesuccinic acid (meth′il-en-suk′sin-ik)
SYN: itaconic acid.
SYN: leucomethylene blue.
methylenophil, methylenophile (meth-i-len′o-fil, -fil)
Staining readily with methylene blue; denoting certain cells and histologic structures. SYN: methylenophilic, methylenophilous. [methylene + G. philos, fond]
methylenophilic, methylenophilous (meth′i-le-no-fil′ik, meth′il-e-nof′i-lus)
methylergometrine maleate (meth′il-er-go-met′ren)
SYN: methylergonovine maleate.
methylergonovine maleate (meth′il-er-go-no′ven)
A partially synthesized derivative of lysergic acid with oxytocic action, used to prevent or treat postpartum uterine atony and hemorrhage. SYN: methylergometrine maleate.
Cation commonly used in water-soluble iodinated radiographic contrast media. SYN: N-m.. m. diatrizoate SYN: meglumine diatrizoate.
3-methylglutaconic aciduria (meth-il-gloo-ta-kon′ik)
Elevated levels of 3-methylglutaconic acid in the urine. An inherited disorder whose mild form is a result of a deficiency of 3-methylglutaconyl-CoA hydratase, leading to delayed speech development.
An enzyme that catalyzes the reaction of trans-3-methylglutaconyl-CoA and water to form 3-hydroxy-3-methylglutaconyl-CoA; this enzyme participates in the pathway for l-leucine degradation; a deficiency of this enzyme will result in 3-methylglutaconic aciduria.
Pyruvaldehyde;the aldehyde of pyruvic acid; an intermediate of carbohydrate metabolism in certain organisms. SYN: pyruvic aldehyde. m. bis(guanylhydrazone) an antineoplastic agent.
SYN: lactoylglutathione lyase.
methyl green [C.I. 42585]
A basic triphenylmethane dye used as a chromatin stain and, in combination with pyronin, for differential staining of RNA (red) and DNA (green); also used as a tracking dye for DNA in electrophoresis.
methylhexaneamine (meth′il-hek-san′a-men, -min)
A volatile sympathetic amine base, used as an inhalant nasal decongestant.
methylmalonate semialdehyde (meth′il-ma-lon-at)
An intermediate in l-valine catabolism; elevated in certain inborn disorders.
methylmalonic acid (meth′il-ma-lon′ik)
2-Methylpropanedioic acid, an important intermediate in fatty acid metabolism; seen in elevated levels in cases of vitamin B12 deficiency. Note that methylmalonate is not methyl malonate, which is the dimethyl ester of malonate. SYN: isosuccinic acid.
SYN: ketotic hyperglycinemia.
Excretion of excessive amounts of methylmalonic acid in urine owing to deficient activity of methylmalonyl-CoA mutase or deficient cobalamin reductase. Two types occur: 1) an inborn error of metabolism resulting in severe ketoacidosis shortly after birth, with long-chain urinary ketones; autosomal recessive inheritance, caused by mutations in the methylmalonyl-CoA mutase gene (MCM) on chromosome 6p [MIM*251000]; 2) acquired, a type due to vitamin B12 deficiency [MIM*251110] due to defective synthesis of adenosylcobalamin.
An intermediate in the degradation of several metabolites ( e.g., valine, methionine, odd-chain fatty acids, theronine); elevated in cases of pernicious anemia. methylmalonyl-CoA epimerase an enzyme that catalyzes the interconversion of d-methylmalonyl-CoA and l-methylmalonyl-CoA. methylmalonyl-CoA mutase an enzyme that catalyzes a reversible interconversion of l-methylmalonyl-CoA and succinyl-CoA; a cobalamin-dependent enzyme; deficiency of this enzyme will result in methylmalonic acidemia.
Hydroxymethyl; the moiety, &cbond;CH2OH.
A weakly acid dye used as a pH indicator (red at 3.2, yellow at 4.4). SYN: helianthine.
A sugar in which the carbon atom farthest from the carbonyl group is a methyl (CH3).
An antifungal preservative. SYN: methyl hydroxybenzoate.
A hexose (a 6-deoxyhexose) in which carbon-6 is part of a methyl group; e.g., rhamnose, fucose.
methylphenidate hydrochloride (meth-il-fen′i-dat)
A central nervous system stimulant used to produce mild cortical stimulation in various types of depressions; commonly used in the treatment of hyperkinetic or hyperactive (attention deficit disorder) children.
An anti-inflammatory glucocorticoid. m. acetate has the same actions and uses as m.; aqueous suspensions are suitable for intrasynovial and soft tissue injection. sodium m. succinate it has the same metabolic and anti-inflammatory actions as the parent compound, m.; because of its solubility it can be administered in small volumes.
A weakly acid dye used as a pH indicator (red at 4.8, yellow at 6.0); easily reduced with loss of color, and pH readings must be made rapidly.
methylrosaniline chloride (meth′il-ro-zan′i-len, -lin)
SYN: crystal violet.
The methyl ester of salicylic acid, produced synthetically or distilled from Gaultheria procumbens (family Ericaceae) or from Betula lenta (family Betulaceae); used externally and internally for the treatment of various forms of rheumatism. SYN: checkerberry oil, gaultheria oil, sweet birch oil, wintergreen oil.
methyl-tert-butyl ether (MTBE)
Used to dissolve gallbladder stones.
A methyl derivative of testosterone, with the same actions and uses, except that it is active when given orally or sublingually. Used in the treatment of hypogenitalism. SYN: 17α-m..
Adenosine carrying an –SCH3 group in place of OH at position 5′; the –SCH3 group is transferred to α-aminobutyric acid to form l-methionine in some bacteria. M. is formed from S-adenosyl-l-methionine in the course of spermidine synthesis by loss of the alanine moiety. SYN: thiomethyladenosine.
An antithyroid compound with the same action as propylthiouracil, but with a smaller dose required.
A methylated tocol; e.g., tocotrienol, the tocopherols.
Any enzyme transferring methyl groups from one compound to another. SYN: demethylase, methylkinase, transmethylase.
methyl violet [C.I. 42535]
Mixtures of tetra-, penta-, or pararosanilin which vary in shade of violet depending on the extent of methylation (designated R for reddish shades, B for bluish shades); the hexamethyl compound is known as crystal violet, the pentamenthyl compound as m. 6B. As stains, m. has many bacteriological, histological, and cytological applications.
A chemical group of drugs derived from xanthine (a purine derivative); members of the group include theophylline, caffeine, and theobromine.
SYN: butter yellow.
methyprylon, methyprylone (meth-i-pri′lon, -lon)
A sedative and hypnotic.
methysergide maleate (meth-i-ser′jid)
A serotonin antagonist, weakly adrenolytic, chemically related to methylergonovine; used in the prophylactic treatment of vascular headache (migraine); untoward effects are common.
The root of Piper m. (family Piperaceae), a plant of the Pacific islands, used by the natives as an intoxicant. It has been used in diarrhea and in inflammatory affection of the urogenital tract. SYN: kava (1) .
Abbreviation for metmyoglobin.
metmyoglobin (metMb) (met′mi-o-glo′bin)
Myoglobin in which the ferrous ion of the heme prosthetic group is oxidized to ferric ion; ferrimyoglobin.
metoclopramide hydrochloride (met′o-klo-pram′id)
An antiemetic agent.
metocurine iodide (met-o-kur′en)
A nondepolarizing neuromuscular blocking agent used to provide relaxation during surgical operations. SYN: dimethyl d-tubocurarine, dimethyl tubocurarine iodide.
A diuretic with antihypertensive activity.
Conjoined twins united at the forehead. See conjoined twins, under twin. [G. metopon, forehead, + pagos, something fixed]
metopic (me-to′pik, me-top′ik)
Relating to the forehead or anterior portion of the cranium. [G. metopon, forehead]
A craniometric point midway between the frontal eminences. SYN: metopic point. [G. metopon, forehead]
Persistence of the frontal suture in the adult. [G. metopon, forehead]
metopoplasty (met′o-po-plas-te, me-top′o-plas-te)
Plastic surgery of the skin or bone of the forehead. [G. metopon, forehead, + plastos, formed]
The study of physiognomy. [G. metopon, forehead, + skopeo, to view]
metoprolol tartrate (me-to′pro-lol)
A β-adrenergic blocking agent used in the treatment of hypertension; exhibits some cardioselectivity.
A genus of opisthorchid fish-borne flukes parasitic in the gallbladder of fish-eating mammals and birds, common in north temperate regions. M. conjunctus is a species that occurs in dogs and cats, and occasionally in humans, in North America. [G. meta, behind, + orchis, testicle]
SYN: heterecious. [G. meta, beyond, + xenos, host]
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