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

nimodipine
(ni-mo´dĭ-pēn) a calcium channel blocking agent used as a vasodilator in the treatment of neurologic problems associated with subarachnoid hemorrhage from a ruptured intracranial aneurysm; administered orally.

nine-mile fever
Q fever.

Ninhydrin test
triketohydrindene hydrate test.

niobium
(Nb) (ni-o´be-әm) a chemical element, atomic number 1, atomic weight 92.906.

Nipah virus
a paramyxovirus that is the etiologic agent of Nipah encephalitis.

nipple
(nip´әl) the pigmented projection at the tip of each breast; it is smaller in men than women. In women it gives outlet to the lactiferous ducts. Called also mammary papilla, mammilla, and teat. any structure shaped like the nipple of the breast; see papilla.

nipple adenoma
a benign lesion of the breast, clinically resembling Paget disease of the breast, consisting of ductal and stromal proliferation beneath the nipple; it presents as a mass, ulceration, or erosion, with a serous or bloody discharge.

nisoldipine
(ni-sol´dĭ-pēn) a calcium channel blocking agent used in the treatment of hypertension; administered orally.

Nissen fundoplication
Nissen operationNissen procedure (nis´en) a type of fundoplication in which the fundus is wrapped completely around the distal esophagus. Replication fork, showing simultaneous synthesis of both strands; since synthesis occurs in the 5′ to 3′ direction, one strand, ...

Nissl bodies
large granular bodies that stain with basic dyes, forming the reticular substance of the cytoplasm of neurons, composed of rough endoplasmic reticulum and free polyribosomes; ribonucleoprotein is one of their main constituents. Called also Nissl granules.

Nissl granules
Nissl bodies.

nit
(nit) the egg of a louse.

nitrate
(ni´trāt) any salt or ester of nitric acid; organic nitrates are used in the treatment of angina pectoris and as preservatives in meat products. Some individuals have sensitivity to nitrates and may suffer from headache, diarrhea, or urticaria after ingesting them.

nitrate reduction test
(for bacteriuria or presence of bacteria in other fluids) a type of nitrite test that identifies the reduction of nitrate to nitrite by a bacterial culture. The fluid under investigation is cultured in a broth containing nitrate and the medium is tested for nitrite by mixing with solutions containing sulfanilic acid and alpha-n...

nitric
(ni´trik) pertaining to or containing nitrogen in one of its higher valences.

nitric acid
a highly caustic, fuming acid that has a characteristic choking odor and can be fatal if swallowed. It is sometimes used as a cauterizing agent in the eradication of warts; large amounts of it on the skin can cause necrosis. It is also used in the form of its potassium and sodium salts. The antidote for nitric acid poison...

nitric oxide
NO, a naturally occurring gas that in the body is a short-lived dilator released from vascular epithelial cells in response to the binding of vasodilators to endothelial cell receptors; it causes inhibition of muscular contraction, and thus relaxation. Excesses of nitric oxide are toxic to cells of the central nervous sys...

nitride
(ni´trīd) a binary compound of nitrogen with a metal.

nitrification
(ni″trĭ-fĭ-ka´shәn) the bacterial oxidation of ammonia and organic nitrogen to nitrites and nitrates in the soil.

nitrifying
(ni´trĭ-fi″ing) oxidizing ammonia into nitrites and then into nitrates; said of certain bacteria.

nitrile
(ni´tril) an organic compound containing trivalent nitrogen attached to one carbon atom, sbondCtbondN.

nitrite
(ni´trīt) any salt or ester of nitrous acid or the NO2− anion; organic nitrites, such as amyl nitrite, have been used as coronary vasodilators in treatment of angina pectoris.

nitrite test
(for nitrites in saliva) to the saliva add 1 or 2 drops of sulfuric acid, a few drops of potassium iodide solution, and some starch paste; a blue color indicates nitrites. a test for nitrites in any fluid; see specific tests, including Griess test, nitrate reduction test, and Schaffer test.

Nitro-Dur
(ni´tro-dur″) trademark for a preparation of nitroglycerin, a vasodilator used in treatment of angina pectoris.

nitroaniline poisoning
poisoning by nitroaniline, a dye used in paints, inks, and other products, characterized by intense methemoglobinemia.

nitroblue tetrazolium test
(for neutrophil microbicidal function) neutrophils are incubated with latex particles and nitroblue tetrazolium (NBT). Normally phagocytosis of the particles is accompanied by reduction of NBT to a blue formazan pigment; absence of NBT reduction indicates a defect in some of the metabolic pathways involved in intracellula...

nitrocellulose
(ni″tro-sel´u-lōs) pyroxylin.

Nitrodisc
(ni´tro-disk) trademark for a preparation of nitroglycerin, a vasodilator used in treatment of angina pectoris.

nitrofuran
(ni″tro-fu´ran) any of a group of antibacterials, including nitrofurantoin, nitrofurazone, and others, that are effective against a wide range of bacteria.

nitrofurantoin
(ni″tro-fu-ran´to-in) a broad-spectrum antibacterial agent used in treatment of urinary tract infections.

nitrofurazone
(ni″tro-fu´rә-zōn) an antibacterial agent effective against a wide variety of organisms, used as a topical antiinfective agent for skin lesions including wounds, burns, skin infections, and ulcers and to aid healing and prevent infection of skin grafts and other kinds of infections.

nitrogen
(N) (ni´tro-jәn) a chemical element, atomic number 7, atomic weight 14.007. It is a gas constituting about four-fifths of common air, and is chemically almost inert. It is not poisonous but is fatal if breathed alone because of oxygen deprivation. It is soluble in the blood and body fl...

nitrogen 13
a radioactive isotope of nitrogen having a half-life of 9.97 minutes and decaying by positron emission; it is used as a tracer in positron emission tomography.

nitrogen balance
the state of the body in regard to the rate of protein intake and protein utilization. When protein is metabolized, about 90 per cent of its nitrogen is excreted in the urine in the form of urea, uric acid, creatinine, and other nitrogen end-products. The remaining 10 per cent of the nitrogen is eliminated in the feces. A negat...

nitrogen mustards
a group of toxic, blistering alkylating agents that are cell cycle phase nonspecific; it includes nitrogen mustard itself (mechlorethamine hydrochloride), chlorambucil, cyclophosphamide, ifosfamide, and melphalan. Some have been used as antineoplastic agents in certain forms of cancer; they do not cure these conditions, but ease thei...

nitrogen washout test
a test for vital capacity of lungs; with the patient inhaling pure oxygen, the volume of exhaled nitrogen is obtained for each breath until it falls below 1 per cent of the gas being exhaled (usually about seven minutes' time); the total volume of nitrogen that has been exhaled at this point is assumed to be 0.8 of the vi...

nitrogenous
(ni-troj´ә-nәs) containing nitrogen.

nitrogenous base
an aromatic, nitrogen-containing molecule that serves as a proton acceptor, such as purine or pyrimidine.

nitroglycerin
(ni″tro-glis´әr-in) a chemical well known as an explosive but also having medical uses; it is a vasodilator and is used medically especially in the prophylaxis and treatment of angina pectoris. Called also glyceryl trinitrate.

nitromersol
(ni″tro-mur´sol) a mercurial compound that has been used as a topical antiinfective agent and for disinfection of surgical and dental instruments and equipment.

nitroprusside test
(for cysteine) if a protein containing cysteine is dissolved in water and 2 to 4 drops of a 4 or 5 per cent solution of sodium nitroprusside and then a few drops of ammonia are added, a deep purple-red color appears; called also Mörner test. (for creatinine) see Weyl test (def. 1).

nitroso-indole-nitrate test
(for indole and skatole) acidify the unknown with nitric acid and add a few drops of potassium nitrite; a red color or a red precipitate indicates indole, a white turbidity indicates skatole.

nitrosourea
(ni-tro″so-u´re-ә) any of a group of cell cycle phase nonspecific alkylating agents that cross the blood-brain barrier and are used as antineoplastic agents.

Nitrostat
(ni´tro-stat) trademark for a preparation of nitroglycerin, a vasodilator used in treatment of angina pectoris.

nitrous
(ni´trәs) pertaining to or containing nitrogen in its lowest valence.

nitrous oxide
a colorless, odorless gas that is a weak inhalational anesthetic, usually used in combination with a potent halogenated inhalational anesthetic to produce general anesthesia or briefly for dental surgery. Its use as a sole agent requires high concentrations that may cause hypoxia. Abuse poses the risk of anoxic death from asphy...

nizatidine
(nĭ-za´tĭ-dēn) a histamine H2 receptor antagonist, used to inhibit gastric acid secretion in the treatment of gastric and duodenal ulcer, gastroesophageal reflux disease, and conditions that cause excessive secretions in the stomach; administered orally.

Nizoral
(ni´zor-al) trademark for preparations of ketoconazole, an antifungal agent.

NK cell
a specialized type of lymphocyte capable of recognizing and destroying cancer cells and virus-infected cells. NK cells are important in natural resistance to tumors; when they are exposed to interleukin-2, they are activated and become even more effective in killing tumor cells. Called also natural killer cell.

NKF
National Kidney Foundation.

nm
nanometer.

NMR
nuclear magnetic resonance.

No
nobelium.

no observed adverse effect level
(NOAEL) no observed effect level(NOEL) in studies of the toxicity of chemicals, the highest dosage level at which chronic exposure to the substance shows no adverse effects; usually calculated for laboratory animals.

no-reflow phenomenon
(no re´flo) when cerebral blood flow is restored following prolonged global cerebral ischemia, there is initial hyperemia followed by a gradual decline in perfusion until there is almost no blood flow.

Noack syndrome
(no´ahk) Pfeiffer syndrome.

NOAEL
no observed adverse effect level.

nobelium
(No) (no-bel´e-әm) a chemical element, atomic number 102, atomic weight 253.

noble metal
a metal that is highly resistant to oxidation and corrosion.

Nocardia
(no-kahr´de-ә) a genus of gram-negative, aerobic, spore-forming bacteria, including N. asteroi´des, a species of opportunistic pathogens that cause nocardiosis and actinomycotic mycetoma.

Nocardia
pneumonia the pneumonia seen with severe pulmonary nocardiosis.

nocardial
(no-kahr´de-әl) pertaining to or caused by Nocardia.

Nocardiopsis
(no-kahr″de-op´sis) a genus of gram-positive, aerobic soil bacteria; they resemble Nocardia but differ in cell wall type and are not resistant to lysozymes. They are potential pathogens, causing abscesses and pulmonary lesions.

nocardiosis
(no-kahr″de-o´sis) infection with Nocardia.

nocebo
(no-se´bo) Latin word meaning I will harm; an adverse, nonspecific side effect occurring in conjunction with a medication but not directly resulting from the pharmacologic action of the medication. The term is purposely similar to placebo.

noci-influence
(no″se-in´floo-әns) injurious or traumatic influence.

nociassociation
(no″se-ә-so″se-a´shәn) unconscious discharge of nervous energy under the stimulus of trauma.

nociception
(no″sĭ-sep´shәn) the ability to feel pain, caused by stimulation of a nociceptor. Physiologically, it is composed of four processes: transduction, transmission, modulation, and perception. Called also pain sense, algesia, and algesthesia.

nociceptive reflexes
reflexes initiated by painful stimuli; see also nociceptor and pain.

nociceptor
(no″sĭ-sep´tәr) a receptor for pain, stimulated by various kinds of tissue injury. adj., nocicep´tive., adj.

nociperception
(no″sĭ-pәr-sep´shәn) nociception.

noctalbuminuria
(nok″tәl-bu″mĭ-nu´re-ә) albuminuria in urine secreted at night.

noctiphobia
(nok″tĭ-fo´be-ә) irrational fear of night and darkness.

nocturia
(nok-tu´re-ә) urinary frequency at night; called also nycturia.

nocturnal penile tumescence test
monitoring of erections occurring during sleep; in the differential diagnosis of psychogenic and organic impotence, the former is generally associated with the presence of normal patterns of nocturnal erection while the latter is not. Called also NPT test..

nodal bradycardia
bradycardia in which the stimulus of the heart's contraction arises in the atrioventricular node or common bundle.

nodal cells
P cells.

nodal extrasystole
atrioventricular extrasystole.

nodal points
two points on the axis of an optical system situated so that a ray falling on one will produce a parallel ray emerging through the other.

nodal rhythm
atrioventricular junctional rhythm. junctional rhythm.

nodal tachycardia
junctional tachycardia.

nodding spasm
clonic spasm of the sternomastoid muscles, causing a nodding motion of the head.

node
(nōd) a small mass of tissue in the form of a swelling, knot, or protuberance, either normal or pathological. adj., no´dal., adj.

node of Aschoff and Tawara
atrioventricular node.

node of Tawara
atrioventricular node.

nodes of Ranvier
constrictions of myelinated nerve fibers at regular intervals at which the myelin sheath is absent and the axon is enclosed only by Schwann cell processes.

nodi
(no´di) plural of nodus.

nodose
(no´dōs) having nodes or projections.

nodosity
(no-dos´ĭ-te) a node. the quality of being nodose.

nodular
(nod´u-lәr) marked with, or resembling, nodules.

nodular basal cell carcinoma
the most common type of basal cell carcinoma, usually seen on the face as one or several small, waxy, translucent nodules with rolled edges around a central depression; these may be ulcerated, crusted, or bleeding and may spread laterally or invade deeply. Two subtypes are micronodular and noduloulcerative basal cell carcinoma.

nodular elastosis
Favre-Racouchot syndrome.

nodular hyperplasia of the prostate
benign prostatic hyperplasia.

nodular lymphoma
follicular lymphoma.

nodular melanoma
a type of malignant melanoma without a perceptible radial growth phase, usually seen on the head, neck, or trunk as a uniformly pigmented, elevated, discolored, rapidly enlarging nodule that ulcerates.

nodular regenerative hyperplasia
a rare liver condition characterized by presence of regenerative nodules in the parenchyma that do not cause fibrosis or other major alterations in lobular architecture.

nodular subepidermal fibrosis
benign fibrous histiocytoma. a type of benign fibrous histiocytoma marked by subepidermal formation of fibrous nodules as a result of productive inflammation.

nodulation
(nod″u-la´shәn) the formation of or presence of nodules.

nodule
(nod´ūl) a small node that is solid and can be detected by touch.

nodule of vermis
the part of the vermis of the cerebellum, on the ventral surface, where the inferior medullary velum attaches.