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

neurotrophic atrophy
atrophy attributed to destruction of the peripheral neurons that maintain the nutrition of a tissue.

neurotrophy
(ndbobr-rot´rә-fe) nutrition and maintenance of tissues as regulated by nervous influence. adj., neurotroph´ic., adj.

neurotropic virus
one that has a preference for and causes infection in nerve tissue, for example, the rabies virus.

neurotropism
(ndbobr-rot´ro-piz″әm) the quality of having a special affinity for nerve tissue. the alleged tendency of regenerating nerve fibers to grow toward specific portions of the periphery. adj., neurotrop´ic., adj.

neurotubule
(noor″o-too´būl) any of the long, straight, parallel tubules within neurons, which along with neurofilaments form neurofibrils.

neurovaccine
(noor″o-vak-sēn´) vaccine virus prepared by growing the virus in the brain of a rabbit.

neurovascular
(noor″o-vas´ku-lәr) pertaining to both nervous and vascular elements, or to nerves controlling the caliber of blood vessels.

neurovisceral
(noor″o-vis´әr-әl) neurosplanchnic.

neurula
(noor´u-lә) the early embryonic stage following the gastrula, marked by the first appearance of the nervous system.

neurulation
(noor″u-la´shәn) formation in the early embryo of the neural plate and neural folds, followed by its closure with development of the neural tube.

neutral
(noo´trәl) neither basic nor acid.

neutral fat
fat (def. 2).

neutral zone
the potential space between the lips and cheeks on one side and the tongue on the other, natural or artificial teeth in this zone being subject to equal and opposite forces from the surrounding musculature.

neutral zone of His
a thickening of the dorsal portion of the embryonic spinal cord projecting into the central canal.

neutralization test
a test for the power of an antiserum, antibiotic, antitoxin, antiviral, or other substance to antagonize the pathogenic properties of a microorganism, virus, bacteriophage, or toxic substance.

neutralize
(noo´trәl-īz) to render neutral.

neutralizing antibody
one that reduces or destroys infectivity of a homologous infectious agent by partial or complete destruction of the agent.

neutrino
(noo-tre´no) a subatomic particle with an extremely small mass and no electric charge.

neutrocyte
(noo´tro-sīt) neutrophil (def. 2).

neutron
(noo´tron) an electrically neutral or uncharged particle of matter existing along with protons in the atoms of all elements except the mass 1 isotope of hydrogen.

neutron radiography
that in which a narrow beam of neutrons from a nuclear reactor is passed through tissues; especially useful in visualizing bony tissue.

neutropenia
(noo″tro-pe´ne-ә) diminished numbers of neutrophils in the blood.

neutropenic fever of unknown origin
a fever of at least 38.3°C occurring on several occasions in a patient whose neutrophil level is lower than 500/mm3 or is expected to fall below that level within one or two days, and for which a cause cannot be determined after three days of investigation, including two days of incubation of cultures.

neutrophil
(noo´tro-fil) any cell, structure, or histologic element readily stainable with neutral dyes. a granular leukocyte having a nucleus with three to five lobes connected by threads of chromatin, and cytoplasm containing very fine granules; called also polymorphonuclear leukocyte and neutrophilic leukocyte. Se...

neutrophilia
(noo″tro-fil´e-ә) increase in the number of neutrophils in the blood; called also neutrophilic leukocytosis.

neutrophilic
(noo″tro-fil´ik) pertaining to neutrophils. stainable by neutral dyes.

neutrophilic cell
a cell, particularly a leukocyte, stainable by neutral dyes; called also neutrophil.

neutrophilic leukocyte
neutrophil (def. 2).

neutrophilic leukocytosis
neutrophilia.

nevirapine
(nә-vir´ә-pēn) a nonnucleoside human immunodeficiency virus-1 (HIV-1) reverse transcriptase inhibitor that acts by interfering with the ability of the virus to replicate; used in combination with other antiretroviral agents in treatment of HIV-1 infection, administered orally.

nevocellular nevus
melanocytic nevus.

nevoid
(ne´void) resembling a nevus.

nevus
(ne´vәs) pl. ne´vi a circumscribed malformation of the skin, or sometimes the oral mucosa, not due to external causes; the excess (or deficiency) of tissue may involve epidermal, connective tissue, adnexal, nervous, or vascular elements. Most are discolored, pink or red or dark; they may appear on any part of...

nevus cell
a type of modified melanocyte found in clusters in the epidermis, sometimes reaching the dermis by a kind of extrusion; these are the main constituent of a melanocytic nevus.

nevus cell nevus
melanocytic nevus.

nevus comedonicus
(ne´vәs kom″ә-don´ĭkәs) comedo nevus.

nevus flammeus
(ne´vәs flam´e-әs) a common congenital vascular malformation involving mature capillaries, present at birth. It consists of a reddish purple lesion that is flat or barely elevated and does not fade with age. It is a benign condition but may be associated with other syndromes such as Sturge-Weber syndro...

nevus lipomatosus
(ne´vәs lĭ-po″mә-to´sәs) a nevus that contains much fibrofatty tissue.

nevus of Ito
a type that has the same features as nevus of ota except for being located on the shoulder or adjacent areas of the trunk or arm, in the areas of distribution of the posterior supraclavicular and lateral cutaneous brachial nerves.

nevus of Ota
a persistent lesion resembling a mongolian spot, involving the conjunctiva, skin around the eye, and adjacent structures; it is seen primarily in babies and in young people around the time of puberty, and in East Asians and people of African descent much more than in light-skinned people. The skin lesions are manifested a...

nevus sebaceus
(ne´vәs sә-ba″she-әs) sebaceous nevus.

nevus sebaceus syndrome
sebaceous nevus syndrome.

nevus simplex
(ne´vәs ) salmon patch.

nevus spilus
(ne´vәs spi´lәs) a type of melanocytic nevus that is tan to brown, has a smooth surface, and is speckled with smaller, darker macules.

nevus unius lateris
(ne´vәs u´ne-әs lat″әr-a´lis) a wartlike epidermal nevus that may be flesh colored or darkened, found in a linear, unilaterally distributed pattern. On the limbs the lesions usually follow the long axis, and on the trunk they usually run horizontally.

newborn
(noo´born) recently born; called also neonatal. newborn infant. postmature newborn postmature infant. postterm newborn postterm infant. premature newborn premature infant. preterm newborn ...

newborn infant
a human infant from the time of birth through the 28th day of life. Called also neonate and newborn.

newborn pneumonitis virus
human parainfluenza virus 1.

Newcastle disease
(noo´kas-әl) a viral disease of birds, including domestic fowl, characterized by respiratory, gastrointestinal, and central nervous system symptoms; it is also transmissible to humans.

Newcastle disease virus
a virus of the family Paramyxoviridae that causes Newcastle disease in birds and humans.

newton
(N) (noo´tәn) the SI unit of force, being that when applied in a vacuum to a body having a mass of 1 kilogram accelerates it at the rate of 1 meter per second squared.

nexus
(nek´sәs) a bond, as between members of a series or group. gap junction.

Nezelof syndrome
(nĕ-zә-lof´) any of a heterogeneous group of immunodeficiency disorders characterized by profoundly deficient cellular immunity and varying degrees of humoral immunodeficiency. Immunoglobulin levels may be normal or increased, but antibody response to immunization may be absent. Patients are highly susc...

NF
National Formulary.

ng
nanogram.

NH region
[nodal-His region] the area where the atrioventricular node becomes the bundle of His.

Ni
nickel.

niacin
(ni´ә-sin) a water-soluble member of the vitamin B complex that is required by the body for synthesis of the coenzymesnicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), essential components of many oxidation-reduction reactions. It also appears to act in enzyme systems for ut...

niacin test
(for Mycobacterium tuberculosis) either of two tests to distinguish strains of M. tuberculosis by adding aniline, ethanol, and cyanogen bromide to a culture; this will turn human M. tuberculosis yellow because of its niacin content.

niacinamide
(ni″ә-sin´ә-mīd) the amide of niacin, occurring naturally in the body and interconvertible with niacin; used in prophylaxis and treatment of pellagra, administered orally, intravenously, or intramuscularly. Called also nicotinamide.

nicardipine
(ni-kahr´dĭ-pēn) a calcium channel blocking agent that acts as a vasodilator; administered orally as the hydrochloride salt in the treatment of angina pectoris and hypertension.

niche
(nich) a small recess, depression or indentation, especially a recess in the wall of a hollow organ that tends to retain contrast media, as revealed by radiographs.

niche sign
Haudek sign.

nickel
(Ni) (nik´әl) a chemical element, atomic number 28, atomic weight 58.71. It is a major component of some alloys used in dentistry and is also found in stainless steel. Prolonged exposure to nickel, such as in jewelry, can cause nickel dermatitis.

nickel dermatitis
a type of contact dermatitis from prolonged exposure to nickel, such as in jewelry.

Nickerson-Kveim test
Kveim test.

nicking
(nik´ing) localized constriction of the retinal blood vessels.

niclosamide
(nĭ-klo´sә-mīd) one of the most effective anthelmintic agents for use against tapeworm infections, including most species that infect humans; it acts by inhibiting anaerobic metabolism.

Nicoladoni sign
Branham sign.

Nicolas-Favre disease
(ne-ko-lah´ fahv´rә) lymphogranuloma venereum.

Nicolau syndrome
(nik´o-lo) a severe cutaneous reaction after intramuscular administration of medications, often in the gluteal region, because of ischemia from accidental arterial obliteration or vasculitis. Manifestations include severe local pain, swelling, livedoid changes, and increased skin temperature; there may also be fev...

nicotinamide
(nik″o-tin´ә-mīd) niacinamide. nicotinamide adenine dinucleotide(NAD) a coenzyme that is involved in many biochemical oxidation-reduction reactions. The symbols for the oxidized and reduced forms are NAD and NADH. nicotinamide ade...

nicotine
(nik´o-tēn) (nik´o-tin) a very poisonous alkaloid that in its pure state is a colorless, pungent, oily liquid with an acrid, burning taste. It is a constituent of tobacco and can also be produced synthetically. Preparations are administered orally, intranasally, or by inhalation to help people ...

nicotine poisoning
poisoning by nicotine, such as in children who eat cigarettes, workers who handle wet tobacco leaves, or persons who overuse nicotine gums or patches. Symptoms include stimulation followed by depression of the central and autonomic nervous systems and occasionally death due to respiratory paralysis. Called also nicotinism.

nicotinic
(nik″o-tin´ik) pertaining to the transmission of nerve impulses mediated by nicotinic receptors.

nicotinic acid
(nik″o-tin´ik) niacin.

nicotinic receptor
cholinergic receptors of autonomic ganglion cells and motor end-plates of skeletal muscle that are stimulated by low doses of nicotine and blockaded by high doses of nicotine or by tubocurarine.

nicotinism
(nik´o-tin-iz″әm) nicotine poisoning.

nictitation
(nik″tĭ-ta´shәn) winking.

NICU
neonatal intensive care unit.

nidation
(ni-da´shәn) implantation (def. 1).

nidus
(ni´dәs) Latin word meaning nest. In pathology, it us used to denote the point of origin or focus of a disease process.

Niemann disease
(ne´mahn) Niemann-Pick disease (ne´mahn pik´) a lysosomal storage disease due to a deficiency of sphingomyelin phosphodiesterase with sphingomyelin accumulation in the reticuloendothelial system. There are five types distinguished by age of onset and by the amount of central nervous system (CNS) in...

Niemann-Pick cells
round, oval, or polyhedral cells present in the bone marrow and spleen in Niemann-Pick disease; they have foamy, lipid-containing cytoplasm, in the form of sphingomyelin, which gives a positive reaction with Sudan III and other fat stains. Called also Pick cells.

nifedipine
(ni-fed´ĭ-pēn) a calcium channel blocking agent administered orally as a coronary vasodilator in the treatment of angina pectoris; also used in the treatment of hypertension.

night blindness
inability or a reduced ability to see in dim light, and slowness at adjusting from brightness to dimness. Dim light produces a change in a pigment called rhodopsin in the rods of the retina, causing nerve impulses to travel to the brain and make visual impressions. Night blindness occurs when the rods lack rhodopsin; a co...

night vision
visual perception in the darkness of night or under conditions of reduced illumination.

nightmare
(nīt´mār″) a terrifying dream; an anxiety attack during dreaming, accompanied by mild autonomic reactions and usually awakening the dreamer, who recalls the dream but is oriented.

nightmare disorder
a sleep disorder of the parasomnia group, consisting of repeated episodes of nightmares that awaken the sleeper, who rapidly becomes fully oriented and alert and can vividly recall the dreams. Onset is usually in childhood or adolescence, and children often outgrow the disorder. Called also dream anxiety d.

nigra
(ni´grә) substantia nigra. adj., ni´gral., adj.

nigrities
(ni-grish´e-ēz) blackness.

nigrostriatal
(ni″gro-stri-a´tәl) projecting from the substantia nigra to the corpus striatum; said of a bundle of nerve fibers.

nigrostriatal tract
a bundle of nerve fibers extending from the substantia nigra to the globus pallidus and putamen in the corpus striatum; injury to it may be a cause of parkinsonism.

NIH
National Institutes of Health.

NIH catheter
one used for coronary arteriography; it has a closed end and several side holes for rapid injection of large volumes of contrast material.

nihilism
(ni´il-iz″әm) an attitude of skepticism regarding traditional values and beliefs or their frank rejection. a delusion of nonexistence of part or all of the self or the world. adj., nihilis´tic., adj.

nihilistic delusion
delusion of negation.

Nikolsky sign
(nĭ-kol´ske) in pemphigus vulgaris and some other bullous diseases, the outer epidermis separates easily from the basal layer on exertion of firm sliding manual pressure.

nil disease
minimal change disease.

nilutamide
(ni-loo´tә-mīd) a nonsteroidal antiandrogen used as an antineoplastic, in combination with measures to lower testosterone levels such as bilateral orchiectomy, in treatment of prostatic carcinoma; administered orally.