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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


measle (me′zl)
1. The larva (Cysticercus cellulosae) of Taenia solium, the pork tapeworm; C. cellulosae is less frequently used to designate cysticerci of T. solium. 2. The larva (Cysticercus bovis) of Taenia saginata, the beef tapeworm; the term C. bovis is less frequently used to designate cysticerci of T. bovis.

measles (me′zlz)
1. An acute exanthematous disease, caused by m. virus (genus Morbillivirus), a member of the family Paramyxoviridae, and marked by fever and other constitutional disturbances, a catarrhal inflammation of the respiratory mucous membranes, and a generalized maculopapular eruption of a dusky red color; the eruption occurs early on the buccal mucous membrane in the form of Koplik spots, a manifestation utilized in early diagnosis; average incubation period is from 10–12 days. Recovery is usually rapid but respiratory complications and otitis media caused by secondary bacterial infections are common. Encephalitis occurs rarely. Subacute sclerosing parencephalitis may occur later and is associated with chronic infection. SYN: morbilli. 2. A disease of swine caused by the presence of Cysticercus cellulosae, the measle or larva of Taenia solium, the pork tapeworm. 3. A disease of cattle caused by the presence of Cysticercus bovis, the measle or larva of Taenia saginata, the beef tapeworm of humans. [D. maselen] atypical m. sometimes severe, unusual clinical manifestation of natural m. virus infection in persons with waning vaccination immunity, particularly in those who had received formaldehyde-inactivated vaccine; an accelerated allergic reaction apparently resulting from an anamnestic antibody response, characterized by high fever, absence of Koplik spots, a shortened prodromal period, atypical rash, and pneumonia. black m. 1. SYN: hemorrhagic m.. 2. SYN: Rocky Mountain spotted fever. German m. SYN: rubella. hemorrhagic m. a severe form in which the eruption is dark in color due to effusion of blood into affected areas of the skin. SYN: black m. (1) . three-day m. SYN: rubella. tropical m. a disease of uncertain character, somewhat resembling rubella, occurring in southern China.

measly (mez′le)
Pertaining to pork or beef infected with the cysticerci of the tapeworms Taenia solium or Taenia saginata, respectively.

measure (mezh′er)
1. To determine the magnitude or quantity of a substance by comparing it to some accepted standard or by calculation. 2. A specified magnitude of a physical quantity. 3. A graduated instrument used to m. an object or substance. [O.F. mesure, fr. L. mensura, fr. metior, to m.] Geneva lens m. a device for measuring the radii of the curvature of a spectacle lens. SYN: lens clock. [Geneva, Switzerland]

measurement (mezh′ur-ment)
Determination of a dimension or quantity. end-point m. analytical m. at the end of a chemical reaction, as opposed to making the m. while the reaction proceeds. kinetic m. continuous or frequent monitoring of the readings during a chemical reaction to determine its rate. nasion-pogonion m. SYN: facial plane.

measures of central tendency
General term for several characteristics of the distribution of a set of measurements or values around a value or values at or near the middle of the set; the principal m. are mean, median, and mode.

meatal (me-a′tal)
Relating to a meatus.

meato-
Meatus. [L. meatus, passage]

meatometer (me-a-tom′e-ter)
An instrument for measuring the size of a meatus, especially the meatus of the urethra. [meato- + G. metron, measure]

meatoplasty (me′a-to-plas-te)
Enlargement or other surgical reconfiguring of a meatus or canal, e.g., the external auditory meatus or the urethral meatus.

meatorrhaphy (me-a-tor′a-fe)
Closing by suture of the wound made by performing a meatomy. [meato- + G. rhaphe, suture]

meatoscope (me-at′o-skop)
A form of speculum for examining a meatus, especially the meatus of the urethra. [meato- + G. skopeo, to view]

meatoscopy (me-a-tos′ko-pe)
Inspection, usually instrumental, of any meatus, especially of the meatus of the urethra. [meato- + G. skopeo, to view]

meatotome (me-at′o-tom)
A knife with short cutting edge for use in meatotomy.

meatotomy (me-a-tot′o-me)
An incision made to enlarge a meatus, e.g., of the urethra or ureter. [meato- + G. tome, incision]

meatus, pl .meatus (me-a′tus) [TA]
A passage or channel, especially the external opening of a canal. SYN: external opening. [L. a going, a passage, fr. meo, pp. m., to go, pass] acoustic m. SYN: external acoustic m.. m. acusticus externus [TA] SYN: external acoustic m.. m. acusticus internus [TA] SYN: internal acoustic m.. external acoustic m. [TA] the passage leading inward through the tympanic portion of the temporal bone, from the auricle to the tympanic membrane; it consists of a bony (inner) portion and a fibrocartilaginous (outer) portion, the cartilaginous external acoustic m.. SYN: m. acusticus externus [TA] , acoustic m., antrum auris, auditory canal, ear canal, external auditory m.. external auditory m. SYN: external acoustic m.. external urinary m. external urethral orifice. fish-mouth m. a red and swollen condition of the orifice of the urethra (urinary m.) in gonorrhea. internal acoustic m. [TA] a canal beginning at the opening of the internal acoustic m. in the posterior cranial fossa, passing laterally through the petrous portion of the temporal bone to end at the fundus, where a thin plate of bone separates it from the vestibule; it gives passage to the facial and vestibulocochlear nerves together with the labyrinthine artery and veins. SYN: m. acusticus internus [TA] , internal auditory m.. internal auditory m. SYN: internal acoustic m.. nasal m. [TA] any of four passages in the nasal cavity formed by the projection of the conchae: inferior nasal m. [TA] (m. nasi inferior [TA]), lies below the inferior concha; middle nasal m. [TA] (m. nasi medius [TA]), lies between the middle and inferior conchae; superior nasal m. [TA] (m. nasi superior [TA]), lies between the superior and middle conchae; common nasal m. [TA] (m. nasi communis [TA]) is the part of the nasal cavity between the conchae and the nasal septum. SYN: m. nasi [TA] . m. nasi [TA] SYN: nasal m.. nasopharyngeal m. [TA] the posterior part of the nasal cavity from the posterior limits of the conchae to the choanae. SYN: m. nasopharyngeus [TA] , nasopharyngeal passage. m. nasopharyngeus [TA] SYN: nasopharyngeal m.. ureteral m. SYN: ureteric orifice. m. urinarius SYN: external urethral orifice.

mebanazine (me-ban′a-zen)
An antidepressant with inhibitory effect on monoamine oxidase.

mebendazole (me-ben′da-zol)
An effective broad-spectrum nematicidal agent against intestinal nematodes such as pinworm, hookworm, whipworm, and Ascaris.

mebeverine hydrochloride (me-bev′er-en)
An intestinal antispasmodic.

mebrophenhydramine (me-bro-fen-hi′dra-men)
An H1 antihistaminic.

mebutamate (me-bu′ta-mat)
Chemically, it differs only slightly from meprobamate, and possesses similar CNS-depressant properties.

mecamylamine hydrochloride (mek′a-mil′a-men)
A secondary amine that blocks transmission of impulses at autonomic ganglia (similar to but more effective than hexamethonium); used in the management of severe hypertension.

mechanical (me-kan′i-kal)
1. Performed by means of some apparatus, not manually. 2. Explaining phenomena in terms of mechanics. 3. Automatic. [G. mechanikos, relating to a machine, fr. mechane, a contrivance, machine]

mechanicoreceptor (me-kan′i-ko-re-sep′ter, tor)
SYN: mechanoreceptor.

mechanics (me-kan′iks)
The science of the action of forces in promoting motion or equilibrium. [see mechanical] body m. the study of the action of muscles in producing motion or posture of the body.

mechanism (mek′a-nizm)
1. An arrangement or grouping of the parts of anything that has a definite action. 2. The means by which an effect is obtained. 3. The chain of events in a particular process. 4. The detailed description of a reaction pathway. [G. mechane, a contrivance] association m. the cerebral m. whereby the memory of past sensations may be compared or associated with present ones. countercurrent m. a system in the renal medulla that facilitates concentration of the urine as it passes through the renal tubules. See countercurrent exchanger, countercurrent multiplier. defense m. 1. a psychological means of coping with conflict or anxiety, e.g., conversion, denial, dissociation, rationalization, repression, sublimation; 2. the psychic structure underlying a coping strategy; 3. immunologic m. vs. non-specific defense m.. double displacement m. SYN: ping-pong m.. Douglas m. m. of spontaneous evolution in transverse lie; extreme lateral flexion of the vertebral column with birth of the lateral aspect of thorax before the buttocks. Duncan m. passage of the placenta from the uterus with the rough side foremost. gating m. 1. occurrence of the maximum refractory period among cardiac conducting cells approximately 2 mm proximal to the terminal Purkinje fibers in the ventricular muscle, beyond which the refractory period is shortened through a sequence of Purkinje cells, transitional cells, and muscular cells; gating m. may be a cause of ventricular aberration, bidirectional tachycardia, and concealed extrasystoles; 2. a m. by which painful impulses may be blocked from entering the spinal cord. Cf.:gate-control theory. immunologic m. the groups of cells (chiefly lymphocytes and cells of the reticuloendothelial system) that function in establishing active acquired immunity (induced sensitivity, allergy). ordered m. a scheme for substrate binding and product release for multisubstrate enzymes; for a two-substrate two-product enzyme with an ordered m., one particular substrate has to first bind to the enzyme, followed by the other substrate; chemistry then occurs, and products are formed and are released from the enzyme in a distinct order. More complex ordered schemes exist for enzymes having more than two substrates. Some of the dehydrogenases have such a m.. SYN: ordered. ordered on-random off m. a scheme for substrate binding and product release for multisubstrate enzymes; for a two-substrate two-product enzyme with this m., the reactants have to bind to the enzyme in a distinct order; however, once the products are formed they may dissociate from the enzyme in either order. It has been suggested that pyruvate kinase has such a m.. The random on-ordered off m. is simply the reverse of this m.. ping-pong m. a special multisubstrate reaction in which, for a two-substrate, two-product ( i.e., bi-bi) system, an enzyme reacts with one substrate to form a product and a modified enzyme, the latter then reacting with a second substrate to form a second, final product, and regenerating the original enzyme. An example of such a m. is found in the aminotransferases. More complex ping-pong mechanisms exist for enzymes having more than two substrates. SYN: double displacement m.. pressoreceptive m. the pressoreceptor system, especially of the carotid sinuses and aortic arch. proprioceptive m. the m. of sense of position and movement, by which muscular movements can be adjusted to a great degree of accuracy and equilibrium maintained. random m. a scheme for substrate binding and product release for a multisubstrate enzyme; for a two-substrate two-product enzyme with this m., either substrate can bind first and, after the reaction has taken place, either product can be the first to dissociate from the enzyme. Brain hexokinase has a random m.. More complex random mechanisms exist for enzymes having more than two substrates. re-entrant m. the probable basis of most arrhythmias, requiring at least three criteria in the heart: 1. a loop circuit, 2. unidirectional block, 3. slowed conduction. Impulses enter the loop circuit and divide in both directions (blocked in one direction only), negotiate the loop circuit to the area of block where the slowed conduction has allowed the impulse to arrive at a time when the tissue proximal to the unidirectional block has recovered and will permit its passage in the opposite direction. Schultze m. expulsion of the placenta with the fetal surface foremost.

mechanocardiography (mek′a-no-kar-de-og′ra-fe)
Use of graphic tracings reflecting the mechanical effects of the heartbeat, such as the carotid pulse tracing or apexcardiogram; phonocardiography is also usually considered a form of m..

mechanocyte (mek′a-no-sit)
An in vitro tissue culture fibroblast.

mechanophobia (mek′a-no-fo′be-a)
Morbid fear of machinery. [G. mechane, machine, + phobos, fear]

mechanoreceptor (mek′a-no-re-sep′tor)
A receptor which responds to mechanical pressure or distortion; e.g., receptors in the carotid sinuses, touch receptors in the skin. SYN: mechanicoreceptor.

mechanoreflex (mek′a-no-re′fleks)
A reflex triggered by stimulation of a mechanoreceptor.

mechanotherapy (mek′a-no-thar′a-pe)
Treatment of disease by means of apparatus or mechanical appliances of any kind. [G. mechane, machine, + therapeia, treatment]

mèche (mash)
A strip of gauze or other material used as a tent or drain. [Fr. wick]

mechlorethamine hydrochloride (mek′lor-eth′a-men)
It is cytotoxic for all cells, but with a special affinity for bone marrow, lymphatic tissues, and rapidly proliferating cells of certain neoplasms. Used for the palliative treatment of Hodgkin disease, lymphosarcoma, and certain chronic leukemias. SYN: mustine hydrochloride.

mecism (me′sizm)
Abnormal elongation of the body or one or more of its parts. [G. mekos, length, -ismos, condition]

Mecistocirrus (me-sis-to-sir′us)
A monotypic genus of trichostrongylid nematodes (subfamily Mecistocirrinae), with the single species, M. digitatus; it is not grossly distinguished from Haemonchus contortus and has about the same effect on the host. M. is distributed chiefly in Asia in cattle, sheep, buffalo, bison, the stomach of pigs, and occasionally in humans. [G. mekistos, very long, + L. cirrus, curl, the protruding male organ of a nematode]

Meckel
Johann F., the younger, German comparative anatomist and embryologist, 1781–1833. See M. scan, M. syndrome, M. cartilage, M. diverticulum, M. plane, M.-Gruber syndrome.

Meckel
Johann F., the elder, German anatomist and obstetrician, 1714–1774. See M. band, M. cavity, M. ganglion, M. ligament, M. space.

Mecke reagent
See under reagent.

meclastine (me-klas′ten)
SYN: clemastine.

meclizine hydrochloride (mek′li-zen)
An H1 antihistaminic useful in the prevention and relief of motion sickness and symptoms caused by vestibular disorders. SYN: meclozine hydrochloride.

meclofenamate sodium (mek-lo-fen′a-mat)
A nonsteroidal anti-inflammatory agent with analgesic and antipyretic actions.

meclofenamic acid (me-klo-fen-am′ik)
An NSAID used for inflammatory conditions and dysmenorrhea; also antipyretic.

meclofenoxate (mek′lo-fen-ok′sat)
An analeptic.

meclozine hydrochloride (mek′lo-zen)
SYN: meclizine hydrochloride.

mecometer (me-kom′e-ter)
An instrument, such as calipers with a scale attachment, for measurement of newborn infants. [G. mekos, length, + metron, measure]

meconate (mek′o-nat)
A salt or ester of meconic acid. [G. mekon, poppy]

meconic acid (me-kon′ik)
Obtained from opium; it forms soluble salts (meconates) with many of the alkaloids of opium.

meconin (mek′o-nin)
C10H10O4;the lactone of meconic acid, found also in Hydrastis canadensis; a hypnotic. SYN: opianyl.

meconiorrhea (me-ko′ne-o-re′a)
Passage, by the newborn infant, of an abnormally large amount of meconium. [meconium + G. rhoia, flow]

meconium (me-ko′ne-um)
1. The first intestinal discharges of the newborn infant, greenish in color and consisting of epithelial cells, mucus, and bile. 2. SYN: opium. [L., fr. G. mekonion, dim. of mekon, poppy]

medazepam hydrochloride (me-daz′e-pam)
An antianxiety agent.

medfalan (med′fal-an)
SYN: medphalan.

media (me′de-a)
1. SYN: tunica m.. 2. Plural of medium. [L. fem. of medius, middle]

mediad (me′de-ad)
Toward the middle line.

medial (me′de-al) [TA]
Relating to the middle or center; nearer to the median or midsagittal plane. SYN: medialis [TA] . [L. medialis, middle]

medialecithal (me′de-a-les′i-thal)
Denoting an egg with a moderate amount of yolk, as in amphibians. [L. medialis, medial, + G. lekithos, egg yolk]

medialis (me-de-a′lis) [TA]
SYN: medial, medial. [L.]

medialization (med-e-al-i-za′shun)
An operation to move a part toward the midline, such as the arytenoid cartilage or vocal cord in vocal cord paralysis.

median (me′de-an)
1. Central;middle; lying in the midline. SYN: medianus. 2. The middle value in a set of measurements; like the mean, a measure of central tendency. [L. medianus, middle]

medianus (me-de-a′nus)
SYN: median (1) . [L.]

mediastinal (me′de-as-ti′nal)
Relating to the mediastinum.

mediastinitis (me′de-as-ti-ni′tis)
Inflammation of the cellular tissue of the mediastinum. fibrosing m. SYN: mediastinal fibrosis. fibrous m. scarring of mediastinal structures of unknown origin or due to infection. idiopathic fibrous m. SYN: mediastinal fibrosis.

mediastinography (me′de-as-ti-nog′ra-fe)
Radiography of the mediastinum. [mediastinum + G. grapho, to write] gaseous m. radiography of the mediastinum after injection of air (artificial pneumomediastinum), an obsolete procedure.

mediastinopericarditis (me′de-as′tin-o-per′i-kar-di′tis)
Inflammation of the pericardium and of the surrounding mediastinal cellular tissue.

mediastinoscope (me-de-as′tin′-o-skop)
An endoscope for inspection of the mediastinum through a suprasternal incision.




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