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

lactogen
(lak´to-jәn) any substance that enhances lactation. human placental lactogen(HPL) (hPL) a hormone secreted by the placenta, which disappears from the blood immediately after delivery. It has lactogenic, luteotropic, and growth-promoting ac...

lactogenesis
(lak´to-jen´ә-sis) galactopoiesis.

lactogenic
(lak″to-jen´ik) galactopoietic.

lactoglobulin
(lak″to-glob´u-lin) a globulin occurring in milk.

lactone
(lak´tōn) a cyclic organic compound in which the chain is closed by ester formation between a carboxyl and a hydroxyl group in the same molecule.

lactorrhea
(lak″to-re´ә) excessive or spontaneous milk flow; persistent secretion of milk irrespective of nursing; galactorrhea.

lactose
(lak´tōs) a sugar derived from the milk of mammals, which on hydrolysis yields glucose and galactose; used as a tablet and capsule diluent, a powder bulking agent, and as a component of infant feeding formulas. Many persons are intolerant to lactose as a result of hereditary deficiency of lactase.

lactose intolerance
a disaccharide intolerance specific for lactose, usually due to an inherited deficiency of lactase activity in the intestinal mucosa.

lactoside
(lak´to-sīd) glycoside in which the sugar constituent is lactose.

lactosuria
(lak″to-su´re-ә) elevated levels of lactose, as seen in lactose intolerance or during lactation.

lactotrope
(lak´to-trōp) lactotroph.

lactotrope adenoma
lactotroph adenoma prolactinoma.

lactotrope cell
lactotroph celllactotropic cell lactotroph.

lactotroph
(lak´to-trōf) a type of acidophil in the adenohypophysis that secretes prolactin. Called also lactotrope, luteotroph, and mammotroph.

lactovegetarian
(lak″to-vej″ә-tar´e-әn) a vegetarian who besides foods of vegetable origin will also consume milk and milk products. pertaining to such a diet.

lactulose
(lak´tu-lōs) a synthetic disaccharide used as a cathartic and to enhance the excretion of ammonia in treatment of hepatic encephalopathy.

lacuna
(lә-ku´nә) Latin word meaing a small pit or hollow cavity. a defect or gap, as in the field of vision (scotoma). adj., lacu´nar., adj.

lacuna pharyngis
(lә-ku´nә fә-rin´jis) a depression of the pharyngeal end of the eustachian tube.

lacunar amnesia
partial loss of memory; amnesia for certain isolated experiences.

lacunar cell
a variant of the Reed-Sternberg cell, primarily associated with the nodular sclerosis type of Hodgkin disease.

lacunar ligament
Gimbernat ligament.

lacunule
(lә-ku´nūl) a minute lacuna.

lacus
(la´kәs) Latin word meaning lake. lacus lacrimalis lacrimal lake.

Ladd syndrome
(lad) congenital obstruction of the duodenum due to peritoneal bands (Ladd bands) and cecal volvulus.

Laënnec cirrhosis
a type associated with chronic alcoholism. In the early stages, liver enlargement may reflect fatty infiltration of liver cells (fatty cirrhosis) with necrosis and inflammation due to acute alcohol injury; progressive fibrosis extending from portal areas separates uniform small regeneration nodules. Some attribute the condition...

Laetrile
(la´ә-tril) trademark for a semisynthetic derivative of amygdalin, alleged to have antineoplastic properties.

laetrile
(la´ә-tril) amygdalin derived from crushed pits of certain fruits.

Lafora bodies
intracytoplasmic inclusions consisting of a complex of glycoprotein and acid mucopolysaccharide; widespread deposits are found in Lafora disease, a type of epilepsy.

Lafora disease
(lah-fo´rah) a slowly progressive autosomal recessive form of myoclonic epilepsy beginning in childhood and characterized by attacks of intermittent or continuous clonus of muscle groups, resulting in difficulties in voluntary movement; there is mental deterioration, sometimes progressing to complete dementia, and the p...

Lafora sign
picking of the nose regarded as an early sign of cerebrospinal meningitis.

lag
(lag) the time elapsing between application of a stimulus and the resulting reaction. the early period after inoculation of bacteria into a culture medium, in which the growth or cell division is slow. lag of accommodation the extent to which the eyes fail to focus accuratel...

lageniform
(lә-jen´ĭ-form) flask-shaped.

lagophthalmos
(lag″of-thal´mәs) inability to shut the eyes completely.

Lagrange operation
(lah-grahzh´) sclerectoiridectomy.

LAK cells
lymphokine-activated killer cells.

lake
(lāk) to undergo separation of hemoglobin from erythrocytes. a circumscribed collection of fluid in a hollow or depressed cavity; see also lacuna. lacrimal lake the triangular space at the medial angle of the eye, where the tears collect. marginal lakes&n...

lallation
(lә-la´shәn) a babbling, infantile form of speech. a speech disorder consisting of babbling, infantile speech.

lalognosis
(lal″og-no´sis) the understanding of speech.

lalopathy
(lә-lop´ә-the) speech disorder.

lalophobia
(lal″ә-fo´be-ә) irrational fear of speaking.

laloplegia
(lal″ә-ple´jә) logoplegia.

lalorrhea
(lal″ә-re´ә) logorrhea.

Lamarck's theory
the theory that acquired characteristics may be inherited.

Lamaze method
(lә-mahz´) a method of preparation for childbirth developed by the French obstetrician Fernand Lamaze, based on the Russian technique of psychoprophylaxis. This method trains the woman's mind and body to modify the perception of pain during labor and delivery. The Lamaze method includes class sessions for the moth...

LAMB syndrome
a syndrome of familial myxomas with cutaneous, cardiac, and endocrine involvement, manifested as lentigines, atrial myxoma, and blue nevi. Cf. NAME syndrome.

lambda
(lam´dә) the eleventh letter of the Greek alphabet, Λ or λ. the point of union of the lambdoid and sagittal sutures.

lambda waves
electropositive sharp waves of medium amplitude sometimes seen on an electroencephalogram of the occipital region during concentration on a visual stimulus or during saccadic eye movements.

lambdacism
(lam´dә-siz-әm) a speech disorder consisting of inability to utter the l sound, or substitution of l for r..

lambdoid
(lam´doid) shaped like the Greek letter lambda.

lambdoid suture
the line of union between the upper borders of the occipital and parietal bones, shaped like the Greek letter lambda.

Lambert-Eaton syndrome
(lam´bәrt e´ton) Lambert-Eaton myasthenic syndrome(LEMS) Eaton-Lambert syndrome.

lame
(lām) incapable of normal locomotion; deviation from the normal gait. See also claudication.

lamella
(lә-mel´ә) a thin scale or plate, as of bone. a medicated disk or wafer to be inserted under the eyelid. adj., lamel´lar., adj.

lamellar body
one of the spherical granules that form in the skin, migrate to the cytoplasm, and discharge their contents into the intercellular space. The extruded material is then believed to function as a barrier to penetration by foreign substances. Called also lamellar granule and keratinosome.

lamellar bone
the normal type of adult bone, organized in layers (lamellae), which may be parallel (cancellous bone) or arranged in concentric rings (compact bone).

lamellar cataract
a concentric opacity, broad or narrow, usually consisting of powdery white dots, affecting one lamella or zonule of an otherwise clear lens. This is the most common type of congenital cataract, and causes include hypocalcemia, hypoglycemia, galactosemia, and rubella. Called also zonular cataract.

lamellar graft
replacement of the superficial layers of an opaque cornea by a thin layer of clear cornea from a donor eye.

lamellar granule
lamellar body.

lamellar ichthyosis
a chronic inherited form of ichthyosis present at birth; an affected infant is born encased in a collodionlike membrane (see collodion baby). The membrane is soon shed and the skin becomes covered with large, coarse scales, including all the flexures, the palms, and the soles. Universal erythroderma with itching is common...

lamellar sheath
the perineurium.

lamellated bone
one of the two types of bone composing the alveolar bone, with some layers (lamellae) roughly parallel with the marrow spaces and others forming haversian systems.

lamellipodia
(lә-mel″ĭ-po´de-ә) sing. lamellipo´dium Delicate sheetlike extensions of cytoplasm that form transient adhesions with the cell substrate and wave gently, enabling the cell to move along the substrate.

lamina
(lam´ĭ-nә) a thin, flat plate or stratum of a composite structure; called also layer. vertebral lamina.

lamina basalis
(lam´ĭ-nә ba-sa´lis) basal lamina.

lamina basilaris
(lam´ĭ-nә bas″ĭ-lar´is) the posterior wall of the cochlear duct, separating it from the scala tympani.

lamina choroidocapillaris
(lam´ĭ-nә kә-roi″do-kap″ĭ-lar´is) the inner layer of the choroid, composed of a single-layered network of small capillaries.

lamina cribrosa
(lam´ĭ-nә krĭ-bro´sә) fascia cribrosa. (of ethmoid bone) the horizontal plate of ethmoid bone forming the roof of the nasal cavity, and perforated by many foramina for passage of olfactory nerves. (of sclera) the perforated part of the sclera through which pass the axons...

lamina densa
(lam´ĭ-nә den´sә) an electron-dense layer of the basal lamina, consisting mainly of collagen fibrils and proteoglycans; it closely follows the plasma membrane of the basal aspect of the adjacent cell layer, from which it is separated by the lamina lucida (or the lamina rara in the renal glomerulus and p...

lamina dura
(lam´ĭ-nә du´rә) a layer of the alveolar bone that is thin and particularly compact and appears as a line on dental x-rays. Called also bundle bone.

lamina fusca
(lam´ĭ-nә fus´cә) the pigmentary layer of the sclera.

lamina lucida
(lam´ĭ-nә loo´sĭ-dә) an electron-dense layer of the basal lamina lying between the lamina densa and the adjoining cell layer; in the pulmonary alveolus and renal glomerulus it is divided into the internal and external laminae rarae.

lamina of vertebral arch
vertebral lamina.

lamina propria
(lam´ĭ-nә pro´pre-ә) the connective tissue layer of mucous membrane. the middle fibrous layer of the tympanic membrane.

lamina rara
(lam´ĭ-nә rar´ә) in the renal glomerulus and pulmonary alveolus, one of the layers of lamina lucida surrounding the lamina densa; the lamina rara externa is on the epithelial side and the lamina rara interna is on the endothelial side. a term sometimes used as a synonym for lamina lucida.

lamina spiralis
(lam´ĭ-nә spi-ra´lis) spiral lamina.

laminagraphy
(lam″ĭ-nag´rә-fe) a special technique of body-section roentgenography.

laminaplasty
(lam´ĭ-nә-plas″te) incision completely through one lamina of a vertebral arch with creation of a trough in the contralateral lamina; the vertebral arch is then opened like a door, with the trough acting as a hinge; performed to relieve compression of the spinal cord or nerve roots.

laminar
(lam´ĭ-nәr) made up of laminae or layers; pertaining to a lamina.

laminar flow
smooth, uninterrupted flow as of a gas through a tube.

laminar flow hood
a device that separates the air flowing through it into layers, cleansing the air of microorganisms. It is used to protect patients with compromised immune systems and is also used in operating rooms and pharmacies to provide a clean environment.

laminated
(lam´ĭ-nāt″ed) having, composed of, or arranged in layers or laminae.

laminectomy
(lam″ĭ-nek´tә-me) surgical excision of the lamina of a vertebral arch, usually done to relieve the symptoms of a herniated disk by disk excision.

laminotomy
(lam″ĭ-not´ә-me) transection of a vertebral lamina.

lamivudine
(lә-miv´u-dēn) a nucleoside analogue that inhibits reverse transcriptase and is used as an antiviral agent in treatment of hepatitis B infection and, in combination with zidovudine, in treatment of HIV infection and AIDS. Administered orally.

lamotrigine
(lә-mo´trĭ-jēn) an anticonvulsive used in treatment of certain forms of epilepsy.

lamp
(lamp) an apparatus for furnishing heat or light.

lanatoside C
(lә-nat´o-sīd) a glycoside obtained from Digitalis lanata, with cardiotonic uses similar to those of digitalis.

lance
(lans) lancet. to cut or incise with a lancet or similar instrument.

Lancefield classification
(lans´fēld) the classification of hemolytic streptococci into groups on the basis of serologic action; there are currently 18 groups. Most of the infection-causing streptococci are in Group A.

Lancefield precipitation test
a ring precipitation test for identification and classification of streptococci. Group-specific antibody reacts in vitro with group-specific polysaccharide to produce a ring of precipitation where the two reagents react at the interface.

lanceolate
(lan´se-o-lāt) shaped like a small blade or lance.

lancet
(lan´sәt) a small, pointed, two-edged surgical knife. Lancet.

lancinating
(lan´sĭ-nāt″ing) tearing, darting, or sharply cutting; used to describe pain.

lancinating pain
sharp, darting pain.

land fever
a set of symptoms resembling seasickness sometimes experienced when, after an ocean voyage, the ship enters a relatively landlocked body of water.

Landau reflex
when an infant is held in the prone position, the entire body forms a convex upward arc; gentle pressure on the head or gravity flexes the neck and hip, reversing the arc.

Landau-Kleffner syndrome
(lahn´dou klef´nәr) an epileptic syndrome of childhood characterized by partial or generalized seizures, psychomotor abnormalities, and aphasia progressing to mutism. The electroencephalogram from bilateral temporal regions is abnormal, with spikes like those of benign rolandic epilepsy. Called also acquired...

Landolt operation
the formation of a lower eyelid with a double pedicle or bridge flap of eyelid skin taken from the upper lid.

Landouzy-Dejerine atrophy
Landouzy-Dejerine muscular dystrophy facioscapulohumeral muscular dystrophy.

Landry paralysis
Landry syndrome (lah-dre´) Guillain-Barré syndrome.