Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

metalloenzyme
(mә-tal″o-en´zīm) any enzyme containing tightly bound metal atoms, such as the cytochromes.

metalloid
(met´әl-oid) any element with both metallic and nonmetallic properties. any metallic element that does not have all the characters of a typical metal.

metallophil cells
cells in which the cytoplasm has a great affinity for metal salts; these are cells of the reticuloendothelial system, and also a series of related cells that are not selectively stained by vital staining.

metalloporphyrin
(mә-tal″o-por´fә-rin) a combination of a metal with porphyrin, such as heme.

metalloprotein
(mĕ-tal″o-pro´tēn) a protein molecule bound to a metal ion, such as hemoglobin.

metallurgy
(met´әl-ur″je) the science and art of using metals.

metamere
(met´ә-mēr) one of a series of homologous segments of the body of an animal. Cf. antimere.

metameric syndrome
segmentary syndrome.

metamorphopsia
(met″ә-mor-fop´se-ә) defective vision, with distortion of the shape of objects seen.

metamorphosis
(met″ә-mor´fә-sis) change of structure or shape; particularly, transition from one developmental stage to another, as from larva to adult form. adj., metamor´phic., adj. fatty metamorphosis any normal or pathologic transformation of fat, including fatty in...

Metamucil
(met″ә-mu´sil) trademark for preparations of psyllium hydrophilic mucilloid, a bulk laxative.

metamyelocyte
(met″ә-mi´ә-lo-sīt″) a precursor in the granulocytic series, being a cell intermediate in development between a promyelocyte and the mature, segmented (polymorphonuclear) granular leukocyte, and having a U-shaped nucleus.

metanephric tubules
the tubules comprising the permanent kidney of amniotes.

metanephrine
(met″ә-nef´rin) a urinary metabolite of epinephrine.

metanephros
(met″ә-nef´ros) pl. metaneph´roi the permanent embryonic kidney. It develops later than the mesonephros and in a lower position. adj., metaneph´ric., adj.

metaphase
(met´ә-fāz″) the stage of cell division following prometaphase, during which the chromosomes move to the center of the cell and line up to form the equatorial plate.

Metaphen
(met´ә-fәn) trademark for preparations of nitromersol, a disinfectant used as a topical antiinfective agent and for sterilizing instruments and other equipment.

metaphyseal dysostosis
a skeletal abnormality in which the epiphyses are normal or nearly so, and the metaphyseal tissues are replaced by masses of cartilage, producing interference with endochondral bone formation and expansion and thinning of the metaphyseal cortices.

metaphyseal dysplasia
a disturbance in enchondral bone growth, failure of modeling causing the ends of the shafts to remain larger than normal in circumference.

metaphysis
(mә-taf´ә-sis) the wider part at the end of the shaft of a long bone. adj., metaphys´eal., adj.

metaplasia
(met″ә-pla´zhә) the change in the type of adult cells in a tissue to a form abnormal for that tissue. adj., metaplas´tic., adj. agnogenic myeloid metaplasia the primary or idiopathic form of myeloid metaplasia, which is often accompanied by myelofibrosis; it is ...

metaplastic ossification
the development of bony substance in normally soft body structures.

metapneumonic
(met″ә-noo-mon´ik) succeeding or following pneumonia.

Metapneumovirus
(met″ә-noo´mo-vi″rәs) a genus of viruses of the family Paramyxoviridae that cause respiratory infections in humans and other animals.

metaproterenol
(met″ah-pro-ter´ĕ-nol) a beta2-adrenergic receptor agonist which also has significant beta1-adrenergic activity; used in the form of the sulfate salt as a bronchodilator.

metapsychology
(met″ә-si-kol´ә-je) the branch of psychology that deals with the theoretical or speculative aspects of a particular subject of psychology, and the significance of mental processes that are beyond empirical verification.

metaraminol
(met″ah-ram´ĭ-nol) a sympathomimetic agent acting mainly as an α-adrenergic agonist but also stimulating the β1-adrenergic receptors of the heart and having potent vasopressor activity; administered intravenously, intramuscularly, or subcutaneously as the bitartrate salt for prevention and treatment ...

metarubricyte
(met″ә-roo´brĭ-sīt) orthochromatic erythroblast.

metastasis
(mә-tas´tә-sis) the transfer of disease from one organ or part to another not directly connected with it. It may be due to transfer of either pathogenic microorganisms (such as tubercle bacilli) or of cells, as in malignant tumors. See also cancer. a growth of pathogenic microorganisms or of ab...

metastasize
(mә-tas´tә-sīz) to form new foci of disease in a distant part by metastasis.

metastatic pneumonia
suppurative pneumonia due to bloodborne infection in bacteremia.

metasternum
(met″ә-stur´nәm) the xiphoid process.

metatarsal
(met″ә-tahr´sәl) pertaining to the metatarsus. one of the metatarsal bones.

metatarsal bones
metatarsals; the five bones extending from the tarsal bones to the phalanges of the toes, being numbered in sequence (1–5) from the most medial to the most lateral.

metatarsalgia
(met″ә-tahr-sal´jә) pain and tenderness in the metatarsal region.

metatarsectomy
(met″ә-tahr-sek´tә-me) excision or resection of a metatarsal bone.

metatarsophalangeal
(met″ә-tahr″so-fә-lan´je-әl) pertaining to the metatarsus and the phalanges of the toes.

metatarsus
(met″ә-tahr´sәs) the part of the foot between the ankle and the toes, its skeleton being the five bones (metatarsal bones) extending from the tarsus to the phalanges. metatarsus primus varus angulation of the first metatarsal bone toward the midline of the body, producin...

metathalamus
(met″ә-thal´ә-mәs) the part of the diencephalon inferior to the caudal end of the dorsal thalamus, comprising the lateral and medial geniculate bodies.

metathesis
(mә-tath´ә-sis) artificial transfer of a morbid process. a chemical reaction in which an element or radical in one compound exchanges places with another element or radical in another compound.

metatrophic
(met″ә-tro´fik) utilizing organic matter for food.

metatrophic therapy
administration of a diet that acts as an adjunct to the drug taken.

metatypical cell carcinoma
basosquamous cell carcinoma.

metaxalone
(mә-taks´ә-lōn) a centrally acting skeletal muscle relaxant used for relief of painful musculoskeletal conditions; administered orally.

Metazoa
(met″ә-zo´ә) the division of the animal kingdom that includes the multicellular animals, in other words all animals except the Protozoa. adj., metazo´al, metazo´an., adj.

metazoan disease
a disease caused by metazoan parasites, such as nematodes, cestodes, trematodes, or arthropods.

metazoon
(met″ә-zo´on) pl. metazo´a an individual organism of the Metazoa.

Metchnikoff theory
(mech´nĭ-kof) the theory that bacteria and other harmful elements in the body are attacked and destroyed by cells called phagocytes, and that the contest between such harmful elements and the phagocytes produces inflammation.

metencephalon
(met″en-sef´ә-lon) the anterior part of the rhombencephalon; it is made up of the pons and cerebellum. the anterior of two brain vesicles formed by specialization of the rhombencephalon in the developing embryo.

meteorotropism
(me″te-ә-rot´rә-piz″әm) the response to influence by meteorologic factors noted in certain biologic events, such as sudden death, attacks of angina, joint pain, insomnia, and traffic accidents. adj., meteorotrop´ic., adj.

meter
(me´tәr) the base SI unit of linear measure, approximately equivalent to 39.37 inches. Symbol m. an apparatus for measuring the quantity of something passing through it, such as a gas or an electric current.

meter angle
the angle formed by intersection of the visual axis and the perpendicular bisector of the line joining the centers of rotation of the two eyes when viewing a point one meter distant (small meter angle) or the angle formed by intersection of the visual axes of the two eyes in the midline at a distance of one meter (large m...

meter-kilogram-second system
(MKS) a system of measurements in which the units are based on the meter as the unit of length, the kilogram as the unit of mass, and the second as the unit of time.

metformin
(mәt-for´min) a hypoglycemic agent that potentiates the action of insulin; used in treatment of type 2 diabetes mellitus.

methacetin breath test
a breath test of liver function: the fasting patient is administered a dose of methacetin labeled with heavy carbon (carbon 13) and breath levels of carbon dioxide are measured at regular intervals; low levels of carbon dioxide indicate liver dysfunction such as cirrhosis.

methacholine
(meth″ә-ko´lēn) a cholinergic agonist, having a longer duration of action than acetylcholine and predominantly muscarinic effects; it has vasodilator and cardiac vagomimetic effects but has largely been replaced by other drugs. It is also used in bronchial challenge tests.

methacrylic acid
(meth″ә-kril´ik) an organic acid that polymerizes easily to form a ceramic-like mass. Its esters, methyl and polymethyl methacrylate, are used in the manufacture of acrylic resins and plastics.

methadone
(meth´ә-dōn) a synthetic opioid analgesic with pharmacologic properties similar to those of morphine and heroin and equal potential for addiction; used as an analgesic and as a substitute opiate in the treatment of heroin addiction.

methadone block
see narcotic blockade.

methamphetamine
(meth″am-fet´ә-mēn) a central nervous system stimulant and pressor drug, used as the hydrochloride salt in the treatment of attention-deficit/hyperactivity disorder. Abuse may lead to dependence. See also amphetamine.

methane
(meth´ān) a flammable, explosive gas from decomposition of organic matter. Methane.

methanol
(meth´ә-nol) a poisonous colorless liquid used as a solvent and fuel; ingestion may cause blindness or death. Called also methyl or wood alcohol.

methantheline
(mĕ-than´thĕ-lēn) an anticholinergic and antimuscarinic, used in the form of the bromide salt as an antispasmodic to depress gastrointestinal activity.

methaqualone
(mә-thak´wә-lōn) a nonbarbiturate compound formerly used as a sedative and hypnotic; now found only as a drug of abuse. See drug abuse.

methazolamide
(meth″ә-zo´lә-mīd) a carbonic anhydrase inhibitor used in the treatment of glaucoma.

methdilazine
(mәth-di´lә-zēn) an antihistamine used as the base or the hydrochloride salt to relieve itching in various dermatoses; administered orally.

methemalbumin
(met″he-mal-bu´min) a brownish pigment formed in the blood by the binding of albumin with heme; indicative of intravascular hemolysis.

methemalbuminemia
(met″hēm-al-bu″min-e´me-ә) the presence of methemalbumin in the blood.

methemoglobin
(met-he´mo-glo″bin) a pigment formed in the blood from hemoglobin by oxidation of the iron atom from the ferrous to the ferric state; it does not function as an oxygen carrier. A small amount is found in the blood normally, but injury or toxic agents cause more hemoglobin to change to methemoglobin (see methemoglo...

methemoglobinemia
(met″he-mo-glo″bĭ-ne´me-ә) the presence of excessive methemoglobin in the blood, resulting in cyanosis and headache, dizziness, fatigue, ataxia, dyspnea, tachycardia, nausea, vomiting, and drowsiness, which can progress to stupor, coma, and occasionally death. It may be either chemical- or drug-in...

methemoglobinuria
(met″he-mo-glo-bĭ-nu´re-ә) methemoglobin in the urine, as in methemoglobinemia.

methenamine
(meth-en´ә-mēn) a urinary antiseptic, administered orally as the hippurate and mandelate salts.

methicillin
(meth″ĭ-sil´in) a semisynthetic penicillin that is highly resistant to inactivation by penicillinase; its sodium salt is used parenterally as an antibacterial.

methimazole
(meth-im´ә-zōl) a thyroid inhibitor used in treatment of hyperthyroidism.

methionine
(mә-thi´o-nēn) a sulfur-containing essential amino acid that furnishes both methyl groups and sulfur necessary for metabolism.

methionine malabsorption syndrome
an autosomal recessive disorder of methionine absorption in which the urine has a characteristic odor resembling that of the interior of an oasthouse (room where tobacco, hops, and malt are dried). It is due to alpha-hydroxybutyric acid formed by bacterial action on the unabsorbed methionine. Characteristics include white hair,...

methocarbamol
(meth″o-kahr´bә-mol) a compound used as a skeletal muscle relaxant administered orally, intramuscularly, or intravenously in the treatment of painful musculoskeletal conditions.

method
(meth´әd) a manner of performing something; these can also be called maneuvers, operations, procedures, surgery, or techniques.

methohexital
(meth″o-hek´si-tal) an ultrashort-acting barbiturate; its sodium salt is used as a general anesthetic, a general and local anesthesia adjunct, and a sedative for certain diagnostic procedures in children.

methotrexate
(meth″o-trek´sāt) an antimetaboliteantineoplastic agent that inhibits the conversion of folic acid to tetrahydrofolic acid by binding the enzyme dihydrofolate reductase, thus inhibiting DNA synthesis; it is specific for the S phase of the cell cycle. Used as the base and the sodium salt in the treatment of le...

methoxamine
(mә-thok´sә-mēn) a sympathomimetic amine used as a vasopressor in the treatment of acute hypotensive states, particularly to maintain blood pressure during anesthesia, and also to treat paroxysmal supraventricular tachycardia; administered intramuscularly or intravenously.

methoxsalen
(mә-thok´sә-lәn) an acrylic acid compound that induces melanin production on exposure of the skin to ultraviolet radiation; used orally and topically in the treatment of idiopathic vitiligo, mycosis fungoides, and psoriasis.

methoxyflurane
(mә-thok″se-floo´rān) a highly potent inhalational anesthetic agent, used primarily to produce analgesia during the first stage of labor; its use in surgery is limited by a dose-related nephrotoxicity to procedures of short duration.

methoxyphenamine
(mĕ-thok″se-fen´ah-mēn) a sympathomimetic drug used as a bronchodilator.

methsuximide
(meth-suk´sĭ-mīd) an anticonvulsant used in the treatment of absence epilepsy; administered orally.

methyclothiazide
(meth″ĭ-klo-thi´ә-zīd) a thiazide diuretic used for the treatment of hypertension and edema.

methyl
(meth´әl) the chemical group or radical sbondCH3.

methyl alcohol
methanol.

methyl red test
(for differentiation of Enterobacteriaceae) the organism is inoculated into a buffered glucose-peptone broth containing methyl red. In a positive reaction, the medium remains red after incubation owing to acid metabolic products. Most Enterobacteriaceae are positive; the Klebsielleae are negative and Erwinieae are variabl...

methyl salicylate
a natural or synthetic oil with a characteristic wintergreen odor and taste; used as a counterirritant in ointments or liniments for muscle pain and also as a flavoring agent. Called also wintergreen oil.

methylate
(meth´әl-āt) a compound of methyl alcohol and a base. to add a methyl group to a substance.

methylation
(meth″әl-a´shәn) the addition of methyl groups. DNA methylation the postsynthetic addition of methyl groups to specific sites on DNA molecules; the reaction is catalyzed by enzymes called DNA methyltransferases that are specific for nucleotide and position of me...

methylbenzethonium
(meth″әl-ben″zә-tho´ne-әm) an ammonium compound used in the form of the chloride salt as a disinfectant and local antiinfective agent; it is applied topically to skin coming in contact with urine, feces, or perspiration, and used in a rinse for diapers and linens of babies and inconti...

methylcellulose
(meth″әl-sel´u-lōs) a methyl ester of cellulose, used as a bulk laxative, as a suspending agent for drugs, and applied topically to the cornea during certain ophthalmic procedures to protect and lubricate the cornea.

methylcytosine
(meth″әl-si´to-sēn) a pyrimidine occurring in deoxyribonucleic acid.

methyldopa
(meth″әl-do´pә) a phenylalanine derivative administered orally or intravenously as an antihypertensive agent.

methyldopate
(meth″il-do´pāt) an ethyl ester of methyldopa; its hydrochloride salt is given by intravenous infusion for acute hypertensive crisis.

methylene blue
(meth´ĭ-lēn) a synthetic organic compound, in dark green crystals or lustrous crystalline powder, used in treatment of methemoglobinemia, as a stain in pathology and bacteriology, and as a diagnostic aid in the detection of the premature rupture of fetal membranes.

methylenedioxyamphetamine
(MDA) (meth″ә-lēn-di-ok″se-am-fet´ә-mēn) a hallucinogenic compound chemically related to amphetamine and mescaline; it is widely abused and causes dependence.

methylergonovine
(meth″il-er″go-no´vin) an oxytocic used as the maleate salt especially to prevent or combat postpartum hemorrhage or atony.