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

Leriche disease
(lә-rēsh´) posttraumatic osteoporosis.

Leriche syndrome
(lĕ-rēsh´) fatigue in the hips, thighs, or calves on exercising, absence of femoral pulsations, impotence, and often pallor and coldness of the lower limbs, usually affecting males and due to chronic obstruction of the aortic bifurcation.

Lermoyez syndrome
(ler″mwah-ya´) tinnitus and hearing loss preceding an attack of vertigo and then subsiding after the vertigo has become established. Cf. Meniere disease.

lesbian
(lez´be-әn) pertaining to lesbianism. a female homosexual.

lesbianism
(lez´be-әn-iz″әm) homosexuality between women.

Lesch-Nyhan syndrome
(lesh´ ni´әn) an inherited abnormality of purine metabolism, caused by a recessive gene located on the X chromosome, marked by physical and mental retardation, compulsive self-mutilation of fingers and lips by biting, choreoathetosis, spastic cerebral palsy, and impaired renal function.

Leser-Trélat sign
sudden appearance and rapid increase in size and number of seborrheic keratoses, which may be a sign of internal malignancy, especially of the gastrointestinal tract.

lesion
(le´zhәn) any pathological or traumatic discontinuity of tissue or loss of function of a part. Lesion is a broad term, including wounds, sores, ulcers, tumors, cataracts, and any other tissue damage. They range from the skin sores associated with eczema to the changes in lung tissue that occur in tuberculosi...

lesser curvature of stomach
the right or medial border of the stomach, marking the superior junction of the anterior and posterior surfaces.

lesser horn of hyoid bone
a small cone-shaped projection passing upward on either side of the hyoid bone at the angle where the main part of the bone (body) meets the greater horn.

lesser occipital nerve
origin, superficial cervical plexus (C2–C3); distribution, ascends behind the auricle and supplies some of the skin on the side of the head and on the cranial surface of the auricle; modality, general sensory.

lesser omentum
a peritoneal fold joining the lesser curvature of the stomach and the first part of the duodenum to the porta hepatis.

lesser palatine arteries
origin, descending palatine artery; branches, none; distribution, soft palate, tonsil.

lesser palatine foramina
the openings of the lesser palatine canals behind the palatine crest and the greater palatine foramina.

lesser palatine nerves
origin, pterygopalatine ganglion; distribution, emerge through the lesser palatine foramen and supply the soft palate and tonsil; modality, parasympathetic, sympathetic, and general sensory.

lesser pelvis
pelvis minor.

lesser petrosal nerve
origin, tympanic plexus; distribution, parotid gland via otic ganglion and auriculotemporal nerve; modality, parasympathetic.

lesser splanchnic nerve
origin, ninth and tenth thoracic ganglia of sympathetic trunk; branches, renal branch; distribution, pierces the diaphragm, joins the aorticorenal ganglion and celiac plexus, and communicates with the renal and superior mesenteric plexuses; modality, preganglionic sympathetic and visceral afferent.

Lesser triangle
(les´әr) a triangle formed by the hypoglossal nerve above, and the two bellies of the digastricus on the two sides.

lesser vestibular glands
small mucous glands in females that open upon the vestibular mucous membrane between the urethral and the vaginal orifice.

let-down
(let´doun) the transport of milk from the alveoli of the breast to the ducts; called also milk let-down.

let-down reflex
the ejection or release of milk from the alveoli of the breast into the ducts, caused by a combination of neurogenic and hormonal reflexes involving the hormone oxytocin and, to a lesser extent, vasopressin; called alsomilk ejection reflex and milk let-down reflex.

lethal
(le´thәl) fatal.

lethal dose
(LD) the amount of an agent that can cause death. See also median lethal dose and minimum lethal dose.

lethal gene
one whose expression brings about the death of the organism.

lethal midline granuloma
a rare disease of unknown etiology, characterized by granulomatous lesions of the nasal mucosa, sinuses, palate, and pharynx. Massive, progressive, erosive lesions that destroy the involved soft tissue, cartilage, and bone and sometimes extend to the brain are typical. Untreated cases are fatal (lethal midline granuloma).

lethal multiple pterygium syndrome
a lethal autosomal recessive disorder characterized by multiple pterygia, lung hypoplasia, flexion contractures of the limbs, characteristic facies, and other abnormalities.

lethality rate
case fatality r.

lethargic encephalitis
a form of epidemic encephalitis that was observed in various parts of the world between 1915 and 1926, characterized by increasing languor, apathy, and drowsiness, passing into lethargy. Called also encephalitis A and Economo encephalitis or disease.

lethargy
(leth´әr-je) a lowered level of consciousness marked by listlessness, drowsiness, and apathy. a condition of indifference. adj., lethar´gic., adj.

letrozole
(let´rә-zōl) a nonsteroidal aromatase inhibitor used in treatment of advanced breast cancer in postmenopausal women; administered orally.

Letterer-Siwe disease
(let´әr-әr se´vә) a hereditary type of Langerhans cell histiocytosis seen in young children; characteristics include skin lesions resembling those of seborrheic dermatitis; hemorrhagic tendencies; enlargement of the liver, spleen, and lymph nodes; and progressive anemia. If untreated it is rapidly fata...

leucine
(loo´sēn) a naturally occurring essential amino acid that is necessary for growth in infants and for nitrogen equilibrium in adults.

leucovorin
(loo″ko-vo´rin) folinic acid. leucovorin calcium the calcium salt of folinic acid, used as an antidote for folic acid antagonists (such as methotrexate) when there is need to reverse the toxic effects of the latter, in the treatment of megaloblastic anemias due to folic acid deficie...

leukapheresis
(loo″kә-fә-re´sis) the selective removal of leukocytes from withdrawn blood, which is then retransfused into the donor.

leukemia
(loo-ke´me-ә) a progressive, malignant disease of the blood-forming organs, characterized by distorted proliferation and development of leukocytes and their precursors in the blood and bone marrow. It is accompanied by a reduced number of erythrocytes and platelets, resulting in anemia and increased susceptibility...

leukemia cutis
(loo-ke´me-ә ku´tis) leukemia with leukocytic invasion of the skin marked by pink, reddish brown, or purple macules, papules, and tumors.

leukemic retinopathy
a condition occurring in leukemia, with paleness of the fundus resulting from infiltration of the retina and choroid with leukocytes, and swelling of the disk with blurring of its margin.

leukemid
(loo-ke´mid) any of the polymorphic skin eruptions associated with leukemia; clinically, they may be nonspecific (papular, macular, purpuric, etc.), but histopathologically they may represent true leukemic infiltrations.

leukemogen
(loo-ke´mo-jәn) any substance that produces leukemia. adj., leukemogen´ic., adj.

leukemogenesis
(loo-ke″mo-jen´ә-sis) the induction or development of leukemia.

leukemoid
(loo-ke´moid) having blood counts and sometimes other clinical findings resembling those of leukemia but not due to uncontrolled proliferation of leukocytes. leukemoid reaction a peripheral blood picture resembling that of leukemia or indistinguishable from it on the basis of morpho...

Leukeran
(loo´kәr-әn) trademark for a preparation of chlorambucil, an antineoplastic agent.

leukoagglutinin
(loo″ko-ә-gloo´tĭ-nin) an agglutinin that acts upon leukocytes.

leukoblastosis
(loo″ko-blas-to´sis) abnormal proliferation of leukocytes, as seen in leukemia.

leukocidin
(loo″ko-si´din) a substance toxic to leukocytes, killing the cells with or without lysis. a type of exotoxin produced by pathogenic bacteria such as staphylococci or streptococci; it destroys leukocytes and may also damage monocytes and macrophages.

leukocyte
(loo´ko-sīt) a type of blood cell that lacks hemoglobin and is therefore colorless. Leukocytes are larger in size and fewer in number than erythrocytes; normally the blood has about 8000 of them per mm3. In contrast to erythrocytes, leukocytes can move about under their own power with ameboid movement. Their chief functi...

leukocyte adhesion protein
(LAP) β2 integrin.

leukocyte count
determination of the number of leukocytes in a unit volume of blood, usually after the erythrocytes have been lysed and the blood has been diluted; it may be done either manually with a hemacytometer or electronically. See total leukocyte count and differential leukocyte count. Called also white blood cell or white cell count.

leukocyte inhibitory factor
(LIF) a lymphokine that prevents polymorphonuclear leukocytes from migrating.

leukocytogenesis
(loo″ko-si″to-jen´ә-sis) leukopoiesis.

leukocytolysin
(loo″ko-si-tol´ә-sin) a lysin that leads to disruption of leukocytes.

leukocytolysis
(loo″ko-si-tol´ә-sis) disintegration of leukocytes. Called also leukolysis. adj., leukocytolyt´ic., adj.

leukocytoma
(loo″ko-si-to´mә) a tumorlike mass of leukocytes.

leukocytopenia
(loo″ko-si″to-pe´ne-ә) leukopenia.

leukocytoplania
(loo″ko-si″to-pla´ne-ә) wandering of leukocytes; passage of leukocytes through a membrane.

leukocytopoiesis
(loo″ko-si″to-poi-e´sis) leukopoiesis.

leukocytosis
(loo″ko-si-to´sis) a transient increase in the number of leukocytes in the blood, due to various causes.

leukocytotaxis
(loo″ko-si″to-tak´sis) leukotaxis.

leukocyturia
(loo″ko-si-tu´re-ә) the discharge of leukocytes in the urine, such as in kidney disease or urinary tract infections.

leukoderma
(loo″ko-dur´mә) any of various acquired types of hypomelanosis; called also leukopathia. adj., leukoder´matous, leukoder´mic., adj. syphilitic leukoderma a ring of indistinct, coarsely mottled hypopigmentation on the front and sides of the neck, seen in late secondary...

leukodystrophy
(loo″ko-dis´trә-fe) disturbance of the white substance of the brain. See also adrenoleukodystrophy and leukoencephalopathy. metachromatic leukodystrophy a hereditary leukoencephalopathy, marked by accumulation of a sphingolipid (sulfatide) in tissues, with diffuse loss of myel...

leukoedema
(loo″ko-ә-de´mә) a nonpathologic filmy opalescence of the buccal mucosa, consisting of an increase in thickness of the epithelium, with intracellular edema of the malpighian layer.

leukoencephalitis
(loo″ko-әn-sef″ә-li´tis) inflammation of the white substance of the brain.

leukoencephalopathy
(loo″ko-әn-sef″ә-lop´ә-the) any of a group of diseases affecting the white matter of the brain, especially the white matter of the cerebral hemispheres. It occurs most often in infants and children. When the disorder is caused by a defect in the formation and maintenance of myelin, th...

leukoerythroblastic anemia
leukoerythroblastosis.

leukoerythroblastosis
(loo″ko-ә-rith″ro-blas-to´sis) anemia due to destruction or crowding out of hematopoietic tissues in the bone marrow by a space-occupying lesion; reduction in normal marrow cells induces release of immature hematopoietic cells, especially nucleated erythrocytes, into the bloodstream. Called also ...

leukokeratosis
(loo″ko-ker″ә-to´sis) leukoplakia.

leukokoria
(loo″ko-kor´e-ә) any condition marked by the appearance of a whitish reflex or mass in the pupillary area behind the lens.

leukolysin
(loo-kol´ә-sin) leukocytolysin.

leukolysis
(loo-kol´ә-sis) leukocytolysis.

leukoma
(loo-ko´mә) pl. leuko´mata A dense, white corneal opacity. Causes include untreated syphilis, corneal inflammation or ulceration, and trachoma. Called also walleye. adherent leukoma a white tumor of the cornea enclosing a prolapsed adherent iris.

leukomyelitis
(loo″ko-mi″ә-li´tis) inflammation of white matter of the spinal cord.

leukomyelopathy
(loo″ko-mi″ә-lop´ә-the) disease of the white matter of the spinal cord.

leukonecrosis
(loo″ko-nә-kro´sis) gangrene with formation of a white slough.

leukonychia
(loo″ko-nik´e-ә) abnormal whiteness of the nails; it has a variety of causes. It may be total (leukonychia totalis) or only in spots (leukonychia punctata) or streaks (leukonychia striata).

leukopathia
(loo″ko-path´e-ә) leukoderma. any disease of the leukocytes. leukopathia unguium leukonychia.

leukopedesis
(loo″ko-pә-de´sis) leukocyte emigration.

leukopenia
(loo″ko-pe´ne-ә) reduction of the number of leukocytes in the blood below about 5000 per mm3. Called also aleukemia, aleukocytosis, and leukocytopenia. adj., leukope´nic., adj. malignant leukopenia , pernicious leukopenia agranulocytosis.

leukopenic leukemia
aleukemic leukemia.

leukoplakia
(loo″ko-pla´ke-ә) a disease marked by the development of white thickened patches on the mucous membranes of the cheeks (leukoplakia buccalis), gums, or tongue (leukoplakia lingualis); the patches often form fissures or become malignant. They may grow into larger patches or form ulcers. Those in the mouth may in ti...

leukopoiesis
(loo″ko-poi-e´sis) the production of leukocytes; called also leukocytogenesis and leukocytopoiesis.

leukorrhagia
(loo″ko-ra´jә) profuse leukorrhea.

leukorrhea
(loo″ko-re´ә) a thick white to yellow discharge from the vagina or uterine cavity, which may be a symptom of a disorder either in the reproductive organs or elsewhere in the body. Frequent causes are trichomoniasis, candidiasis, bacterial vaginosis, and infection of the cervix during childbirth. Sexually transmitt...

leukosis
(loo-ko´sis) proliferation of leukocyte-forming tissue.

leukostasis
(loo″ko-sta´sis) increased blood viscosity and tendency to clotting, seen in leukemia that is accompanied by hyperleukocytosis.

leukotaxis
(loo″ko-tak´sis) cytotaxis of leukocytes; the tendency of leukocytes to collect in regions of injury and inflammation. adj., leukotac´tic., adj.

leukotomy
(loo-kot´ә-me) prefrontal lobotomy; see lobotomy.

leukotoxic
(loo´ko-tok″sik) destructive to leukocytes.

leukotoxin
(loo´ko-tok″sin) a toxin that destroys leukocytes.

leukotrichia
(loo″ko-trik´e-ә) whiteness of the hair in a circumscribed area. See also canities and poliosis.

leukotriene
(loo″ko-tri´ēn) any of a group of compounds derived from unsaturated fatty acids, primarily arachidonic acid, that are extremely potent mediators of immediate hypersensitivity reactions and inflammation, producing smooth muscle contraction, especially bronchoconstriction, increased vascular permeability...

leuprolide
(loo-pro´līd) a synthetic analogue of gonadotropin-releasing hormone, used in the form of the acetate ester as an antineoplastic agent, treatment for endometriosis, and gonadotropin inhibitor. Administered subcutaneously or intramuscularly.

Leustatin
(loo-stat´in) trademark for a preparation of cladribine, an antineoplastic agent.

Lev disease
(lev) acquired complete heart block due to sclerosis of the cardiac skeleton.

levalbuterol
(lev″al-bu´tәr-ol) R-albuterol; a β-adrenergic agent used as the hydrochloride salt as a bronchodilator for treatment and prophylaxis of bronchospasm in reversible obstructive airway disease.

levallorphan
(lev″ә-lor´fan) an analogue of levorphanol, which acts as an antagonist to opioid analgesics; used in the treatment of respiratory depression produced by opioid analgesics.

levamisole
(le-vam´ĭ-sōl) an oral imidazole that enhances the immune response and is used as the hydrochloride salt as an adjuvant to fluorouracil in antineoplastic therapy after surgery in patients with Dukes stage C colon cancer.

levarterenol
(lev″ahr-tēr´ә-nol) the levorotatory form of norepinephrine, a much more potent pressor agent than the natural dextrorotatory isomer.

levator
(lә-va´tor) a muscle that elevates an organ or structure. an instrument for raising depressed osseous fragments in fractures.