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

lysogen
(li´so-jәn) an antigen causing the formation of lysin; called also lysinogen. an agent that causes lysis.

lysogenic bacterium
any bacterial cell harboring in its genome the genetic material (prophage) of a temperate bacteriophage and thus reproducing the bacteriophage in cell division; occasionally the prophage develops into the mature form, replicates, lyses the bacterial cell, and is free to infect other cells.

lysogenicity
(li″so-jә-nis´ĭ-te) the ability to produce lysins or cause lysis. the potentiality of a bacterium to produce bacteriophage. the specific association of the phage genome (prophage) with the bacterial genome in such a way that only a few, if any, phage genes are transcribed.

Lysol
(li´sol) trademark for a solution containing phenol derivatives, used as a disinfectant and antiseptic.

lysosomal storage disease
any inborn error of metabolism in which the deficiency of one of the enzymes normally stored in the lysosomes of certain cells results in accumulation of the substance normally degraded by the enzyme. These diseases are further classified, depending on the nature of the stored substance, as glycogen storage diseases (glycogenos...

lysosome
(li´so-sōm) one of the minute bodies occurring in many types of cells, containing various hydrolytic enzymes and normally involved in the process of localized intracellular digestion. adj., lysoso´mal., adj.

lysozyme
(li´so-zīm) a crystalline, basic protein present in saliva, tears, egg white, and many animal fluids, which functions as an antibacterial enzyme.

lysozymuria
(li″so-zi-mu´re-ә) urinary excretion of elevated levels of lysozyme.

lyssa bodies
minute, red staining masses seen in rabies, somewhat resembling Negri bodies, but less sharply defined and with less internal structure.

Lyssavirus
(lis´ә-vi″rәs) a genus of viruses of the family Rhabdoviridae that includes the rabies virus and related viruses.

lytic
(lit´ik) pertaining to lysis or a lysin.

lytic virus
one that is replicated in the host cell and causes death and lysis of the cell.

lyze
(līz) lyse.

MA
Master of Arts; mental age; meter angle.

mA
milliampere.

Maalox
(ma´loks) any of various trademark preparations of magnesium and aluminum salts (usually magnesium hydroxide and aluminum hydroxide) used as antacids.

MAC
membrane attack complex; minimal alveolar concentration; Mycobacterium avium complex (disease).

MAC disease
Mycobacterium avium complex disease.

Mace
(mās) trademark for an aerosol mixture of CS, a common tear gas.

macerate
(mas´әr-āt) to soften by wetting or soaking.

maceration
(mas″әr-a´shәn) the softening of a solid by soaking. In histology, the softening of a tissue by soaking, especially in acids, until the connective tissue fibers are dissolved so that the tissue components can be teased apart. In obstetrics, the degenerative changes with discoloration and softenin...

Macewen sign
(mә-ku´әn) a more than normal resonant note on percussion of the skull behind the junction of the frontal, temporal, and parietal bones in internal hydrocephalus and cerebral abscess.

Macewen triangle
(mә-ku´әn) mastoid fossa.

Machado-Guerreiro test
(for Chagas disease) a complement fixation test, using as antigen an extract of the spleen of puppies infected with Trypanosoma cruzi.

Machado-Joseph disease
(MJD) (mah-shah´do zho-sef´) an autosomal dominant neurodegenerative disease first described in families of Portuguese-Azorean descent, having a variety of forms but characterized principally by ataxia, spasticity, distal muscular atrophy, and ocular movement abnormalities. It is a type of s...

machinery murmur
Gibson murmur.

Machupo virus
an arenavirus of the Tacaribe complex that is the etiologic agent of Bolivian hemorrhagic fever, transmitted by contact with infected rodents of the species Calomys callosus. Called also Bolivian hemorrhagic fever virus.

Mackenzie syndrome
(mә-ken´ze) Jackson syndrome.

MacLean-Maxwell disease
(mә-klān´ maks´wәl) a chronic condition of the calcaneus marked by enlargement of its posterior third and attended by pain on pressure.

Macleod syndrome
(mә-kloud´) Swyer-James syndrome.

macrencephalia
(mak-ren″sә-fa´le-ә) hypertrophy of the brain.

macro-orchidism
(mak″ro-or´kĭ-diz-әm) abnormal enlargement of the testis.

macro-ovalocyte
(mak″ro-o´vә-lo-sīt) an enlarged, oval erythrocyte seen in megaloblastic anemia.

macroamylase
(mac″ro-am´ә-lās) a complex in which normal serum amylase is bound to a variety of specific binding proteins, forming a complex too large for renal excretion. It is not correlated with any specific disease state; however, in hyperamylasemia or pancreatitis, it can result in urinary amylase levels ...

macroamylasemia
(mak″ro-am″әl-ә-se´me-ә) the presence of macroamylase in the blood. adj., macroamylase´mic., adj.

macroangiopathy
(mak″ro-an″je-op´ә-the) angiopathy involving the large blood vessels, as seen in diabetes mellitus and other conditions.

macrobiotic diet
a diet theory based on a Japanese variation of the yin/yang principle and popularized in the United States; there are several different diets, ranging from a severe form that includes only cereal products to more moderate ones in which a wide variety of foods are kept balanced between those with 'yin' energy and those wit...

macroblast
(mak´ro-blast″) an abnormally large, nucleated erythrocyte; a large young erythroblast with megaloblastic features. Called also macronormoblast.

macroblepharia
(mak″ro-blә-far´e-ә) abnormal largeness of the eyelid.

macrocardius
(mak″ro-kahr´de-әs) a fetus with an extremely large heart.

macrocephaly
(mak″ro-sef´ә-le) unusually large size of the head; called also megalocephaly. adj., macrocephal´ic., adj.

macrocheilia
(mak″ro-ki´le-ә) excessive size of the lip.

macrocheiria
(mak″ro-ki´re-ә) megalocheiria.

macrocolon
(mak´ro-ko″lәn) megacolon.

macrocrania
(mak″ro-kra´ne-ә) abnormal increase in size of the skull in relation to the face.

macrocyte
(mak´ro-sīt″) an abnormally large erythrocyte. adj., macrocyt´ic., adj.

macrocythemia
(mak″ro-si-the´me-ә) the presence of macrocytes in the blood, as in macrocytic anemia and some types of liver disease. Called also macrocytosis.

macrocytic anemia
anemia characterized by macrocytes (erythrocytes much larger than normal).

macrocytosis
(mak″ro-si-to´sis) macrocythemia.

macrodactyly
(mak″ro-dak´tә-le) megalodactyly.

Macrodantin
(mak″ro-dan´tin) trademark for a preparation of nitrofurantoin, an antibacterial agent.

macrodontia
(mak″ro-don´shә) abnormal increase in size of one or more teeth. adj., mac´rodont, macrodon´tic., adj.

macroelement
(mak″ro-el´ә-mәnt) a chemical element that has a minimal daily requirement greater than 100 mg; calcium, phosphorus, magnesium, potassium, sodium, and chloride are macroelements.

macrofollicular adenoma
a follicular adenoma composed of large follicles filled with colloid and lined with flat epithelium.

macrogamete
(mak″ro-gam´ēt) the larger, less active female gamete in sexual reproduction, which is fertilized by the smaller male gamete (microgamete). the larger of two types of malarial parasites; see gamete (def. 2).

macrogametocyte
(mak″ro-gә-me´to-sīt) a cell that produces macrogametes. the female gametocyte of certain Sporozoa, such as malarial plasmodia, which matures into a macrogamete.

macrogenitosomia
(mak″ro-jen″ĭ-to-so´me-ә) excessive bodily development, with unusual enlargement of the genital organs. macrogenitosomia praecox macrogenitosomia occurring at an early age due to excessive androgens. In the female, pseudohermaphroditism is apparent and in the male t...

macroglia
(mak-rog´le-ә) neuroglia cells of ectodermal origin; the astrocytes and oligodendrocytes considered together.

macroglobulin
(mak″ro-glob´u-lin) a protein (globulin) of high molecular weight, in the range of 1,000,000; observed in the blood in a number of diseases.

macroglobulinemia
(mak″ro-glob″u-lĭ-ne´me-ә) increased levels of macroglobulins in the blood. Waldenström macroglobulinemia a type of plasma cell dyscrasia with cells having lymphocytic, plasmacytic, or intermediate morphology and secreting immunoglobulin M (IgM) M-component. There i...

macroglossia
(mak″ro-glos´e-ә) excessive size of the tongue.

macrognathia
(mak″ro-na´the-ә) abnormal overgrowth of the jaw. adj., macrognath´ic., adj.

macrogyria
(mak″ro-ji´re-ә) moderate reduction in the number of sulci of the cerebrum, sometimes with increase in the brain substance, resulting in excessive size of the gyri.

macrolide
(mak´ro-līd) a chemical compound characterized by a large lactone ring containing multiple keto and hydroxyl groups. any of a group of antibacterial antibiotics containing such a ring linked to one or more sugars.

macromastia
(mak″ro-mas´te-ә) excessive size of the breasts.

macromelia
(mak″ro-me´le-ә) abnormal largeness of one or more limbs; called also megalomelia.

macromelus
(mak-rom´ә-lәs) a fetus with abnormally large or long limbs.

macromere
(mak´ro-mēr″) one of the large blastomeres formed by unequal cleavage of a zygote as the result of asymmetric positioning of the mitotic spindle; see also micromere.

macromineral
(mak´ro-min″әr-әl) macroelement.

macromolecule
(mak″ro-mol´ә-kūl) a very large molecule having a polymeric chain structure, as in proteins, polysaccharides, and certain other substances. adj., macromolec´ular., adj.

macromonocyte
(mak″ro-mon´o-sīt) an abnormally large monocyte.

macromyeloblast
(mak″ro-mi´ә-lo-blast) an abnormally large myeloblast.

macronodular cirrhosis
a type that follows subacute hepatic necrosis due to toxic or viral hepatitis. The reticulin framework of normal lobules collapses and may be replaced by broad bands of fibrous tissue, so that the liver becomes small and shrunken.

macronormoblast
(mak″ro-nor´mo-blast) macroblast.

macronutrient
(mak″ro-noo´tre-әnt) an essential nutrient that has a large minimal daily requirement, including proteins, fats, carbohydrates, and water. The term sometimes specifically includes, and sometimes specifically excludes, minerals required in amounts greater than 100 mg daily: calcium, chloride, magnesium,...

macronychia
(mak″ro-nik´e-ә) the condition of having unusually large nails; called also megalonychia.

macropenis
(mak″ro-pe´nis) abnormal largeness of the penis; called also macrophallus and megalopenis.

macrophage
(mak´ro-fāj″) any of the large, mononuclear, highly phagocytic cells derived from monocytes, occurring in the walls of blood vessels (adventitial cells) and in loose connective tissue (histiocytes, phagocytic reticular cells). They are components of the reticuloendothelial system. Macrophages have their origi...

macrophage chemotactic factor
(MCF) a lymphokine that attracts macrophages to the invasion site.

macrophage inhibition factor
macrophage inhibitory factor migration inhibitory factor.

macrophage-activating factor
(MAF) interferon-α.

macrophage-derived growth factor
a substance released by macrophages below the surface of a wound that induces the proliferation of fibroblasts.

macrophallus
(mak″ro-fal´әs) macropenis.

macrophthalmia
(mak″rof-thal´me-ә) megalophthalmos.

macropodia
(mak″ro-po´de-ә) megalopodia.

macropolycyte
(mak″ro-pol´e-sīt) a hypersegmented polymorphonuclear leukocyte of greater than normal size.

macroprosopia
(mak″ro-pro-so´pe-ә) excessive size of the face.

macropsia
(mә-krop´se-ә) an illusion in which objects appear larger than their actual size.

macroreentry
(mak″ro-re-en´tre) reentry involving a circuit of electrical current that uses the bundle branches to rapidly activate the heart, causing ventricular tachycardia with a pattern like bundle branch block and a relatively narrow QRS component.

macrorrhinia
(mak″ro-rin´e-ah) excessive size of the nose.

macroscopic
(mak″ro-skop´ik) gross (def. 2).

macroscopic anatomy
gross anatomy.

macroscopy
(mә-kros´kә-pe) examination with the unaided eye.

macroshock
(mak´ro-shok″) a strong electric shock resulting from current that has passed through the trunk, with contact to the source through intact skin.

macrosomatia
(mak″ro-so-ma´she-ә) macrosomia.

macrosomia
(mak″ro-so´me-ә) great bodily size; see also gigantism. Called also macrosomatia. neonatal macrosomia excessive birth weight in a neonate, seen most often in children of diabetic mothers or those with cerebral gigantism.

macrostomia
(mak″ro-sto´me-ә) excessive width of the mouth.

macrotia
(mak-ro´shә) abnormal enlargement of the pinna of the ear.

macula
(mak´u-lә) Latin word meaning stain or macule (def. 1). in anatomy, an area distinguishable by color or otherwise from its surroundings. a corneal scar that can be seen without special optical aids; it presents as a gray spot intermediate between a nebula and a leukoma. macula l...

macula cribrosa
a perforated spot or area; one of three perforated areas (inferior, medial, and superior) in the wall of the vestibule of the ear through which branches of the vestibulocochlear nerve pass to the saccule, utricle, and semicircular canals.