New variant Creutzfeldt-Jakob disease
Abbreviated nvCJD. A human disease thought due to the same infectious agent as bovine spongiform encephalopathy (BSE), or mad cow disease. Both the human and bovine disorders ...
New, fear of the
An irrational fear of anything new, of innovation, of new situations, places, or things. Also called neophobia. In animal behavior, neophobia refers to the tendency of an ...
The trihydrate of magnesium hydrogen phosphate; found in some renal calculi. Cf.:bobierrite, struvite. [J. Cosmo Newberry, Australian mineralogist, + -ite]
Newborn hearing screen
Testing of the newborn baby's ability to hear. Newborn screening of hearing is done with automated auditory brainstem response tests or, less often, with what are called ...
Tests of newborns to detect those at increased risk for disorders such as phenylketonuria (PKU) and hypothyroidism.
Newborn test, Brazelton
A widely used test of the newborn baby as to their neurologic status and developmental progress. The Brazelton newborn test is formally called the Neonatal Behavioral ...
Sir Isaac, English physicist, 1642–1727. See n., newtonian aberration, Newtonian constant of gravitation, newtonian flow, newtonian viscosity, N. disk, N. law.
Derived unit of force in the SI system, expressed as meters-kilograms per second squared (m kg s−2); equivalent to 105 dynes in the CGS system. [I. N.]
A unit of the MKS system, expressed as energy expended, or work done, by a force of 1 N acting through a distance of 1 m; equal to 1 J = 107 ergs.
Proteins that bridge adjacent microtubule doublets of the axoneme of cilia and flagella. [L. nexus, a binding, fr. necto, to bind + -in]
A connection or link. A causal connection. A connected series. "Nexus" comes from the Latin "nectere" meaning "to bind." The same Latin root gave rise to "connect" and "annex." ...
C., French pathologist, *1922. See N. syndrome, N. type of thymic alymphoplasia.
Abbreviation for National Formulary.
Abbreviation for nanogram.
An NG (nasogastric) tube is one that is passed through the nose (via the nasopharynx and esophagus) down into the stomach. An NG tube is a flexible tube made of rubber or ...
Abbreviation for nerve growth factor.
Stands for National Human Genome Research Institute, one of the National Institutes of Health (NIH) in the U.S. NHGRI’s mission is to “support the NIH component of the ...
Abbreviation for non- Hodgkin lymphoma.
Stands for the National Heart, Lung, and Blood Institute, one of the National Institutes of Health in the U.S. The NHLBI’s mission is to “provide leadership for a national ...
NIA (National Institute on Aging)
One of the US National Institutes of Health (NIH). The mission of the National Institute on Aging is to “lead a national program of research on the biomedical, social, and ...
Nicotinic acid, one of the water-soluble B vitamins.
* * *
SYN: nicotinic acid.
A lack of niacin, one of the B-complex vitamins, causes pellagra. Pellagra was known as the "disease of the four D's" — dermatitis, diarrhea, dementia and death. The disease ...
Niacin for high cholesterol
Niacin or nicotinic acid, one of the water-soluble B vitamins, improves all lipoproteins when given in doses well above the vitamin requirement. Nicotinic acid lowers the total ...
A monoamine oxidase inhibitor used in the treatment of depressive disorders.
Stands for National Institute of Arthritis and Musculoskeletal and Skin Diseases, one of the National Institutes of Health in the U.S. NIAMS’s mission is “conduct and support ...
In dentistry, the portion of a condensing instrument that comes into contact with the restorative material being condensed; its end, the face, is smooth or serrated.
A calcium channel blocker of the dihydropyridine series; used as an antihypertensive and antianginal agent.
The National Institute of Child Health and Human Development, one of the US National Institutes of Health. NICHD is in a sense the NIH for kids in that it is concerned with ...
1. In contrast radiography, an eroded or ulcerated area, especially gastrointestinal or vascular, which can be detected when it fills with contrast medium. 2. An ecologic term ...
In molecular biology, a hydrolytic cleavage of a phosphodiester bond in one strand of a double-stranded polynucleic acid. Cf.:cut.
A metallic bioelement, atomic no. 28, atomic wt. 58.6934, closely resembling cobalt and often associated with it. Protects ribosome structure against heat denaturation. A ...
Localized constrictions in retinal blood vessel s.
- arteriovenous n. constriction of a retinal vein at an artery-vein crossing.
A teniacide effective against intestinal cestodes.
William, Scottish physicist, 1768–1851. See N. prism.
Joseph, French physician, *1878. See N.- Favre disease.
Charles J.H., French microbiologist and Nobel laureate, 1866–1936. See N. stain for capsules.
: A South American herb whose leaves contain 2-8% nicotine and serve as the source of smoking and smokeless tobacco. Nicotiana tabacum presents a huge health problem. Disease ...
The biologically active amide of nicotinic acid, used in the prevention and treatment of pellagra. SYN: niacinamide, nicotinic acid amide.
nicotinamide adenine dinucleotide
Ribosylnicotinamide 5′-phosphate (NMN) and adenosine 5′-phosphate (AMP) linked by phosphoanhydride linkage between the two phosphoric groups; binds as a coenzyme to proteins, ...
A condensation product of nicotinamide and ribose 5-phosphate, linking the N of nicotinamide to the (β) C-1 of the ribose; in NAD+, the ring is linked by the 5′-phosphoryl ...
Salt or ester of nicotinic acid; some nicotinates are used in ointments as rubefacients.
1-Methyl-2-(3-pyridyl)pyrrolidine; a poisonous volatile alkaloid derived from tobacco (Nicotiana spp.) and responsible for many of the effects of tobacco; it first stimulates ...
nicotinehydroxamic acid methiodide
An effective cholinesterase reactivator, with actions that are most marked at the skeletal neuromuscular junction; antidotal effects are less striking at autonomic effector ...
Relating to the stimulating action of acetylcholine and other nicotine-like agents on autonomic ganglia, adrenal medulla, and the motor end-plate of striated muscle.
Deficiency of nicotinic acid (also known as niacin), one of the B-complex vitamins, causes pellagra. Pellagra was known as the "disease of the four D's" — dermatitis, ...
A relatively weak peripheral vasodilator related to nicotinic acid; used in peripheral vascular disorders such as Raynaud disease, acrocyanosis, and chilblains.
To wink. Nictitating spasm is spasm of the eyelid with continuous winking. "Nictitate" and the older verb "nictate" both come from the Latin word for winking, "nictare."
* * ...
Spasm of the eyelid with continuous winking. To nictitiate is to wink. " Nictitate" and the older verb "nictate" both come from the Latin word for winking, "nictare."
Winking. SYN: nictation. [L. nicto, pp. -atus, to wink, fr. nico, to beckon]
Stands for the National Institute on Drug Abuse, one of the National Institutes of Health in the U.S., whose mission is to “lead the nation in bringing the power of science to ...
Relating to a nidus, or nest.
Embedding of the early embryo in the uterine endometrium. [L. nidus, nest]
Stands for National Institute on Deafness and Other Communication Disorders, one of the US National Institutes of Health (the NIH). The mission of the National Institute on ...
Abbreviation for non-insulin-dependent diabetes mellitus.
SYN: entactin. [L. nidus, nest, + -gen 1.]
The Latin word for "nest", nidus is used in medicine to refer to any structure that resembles a nest in appearance or function. Just as a nest is a repository for the eggs of ...
Stands for National Institute of Environmental Health Sciences, one of the National Institutes of Health in the U.S., whose mission is to “reduce the burden of human illness ...
Albert, German physician, 1880–1921. See N.- Pick cell, N.- Pick disease, N. disease, N. splenomegaly.
A disorder of the metabolism of a lipid (fat) called sphingomyelin that usually causes the progressive development of enlargement of the liver and spleen (hepatosplenomegaly), ...
Gaston H., 19th century French scientist. See N. rays, under ray.
A calcium channel-blocking agent of the dihydropyridine type; coronary vasodilator.
A furan derivative, principally effective against Candida albicans.
A disaccharide obtained by the hydrolysis of amylopectins, consisting of two d-glucose residues bound in an α1–3 linkage. [fr. nigeran, a polysaccharide synthesized by ...
Impaired vision in dim light and in the dark, due to impaired function of specific vision cells (namely, the rods) in the retina. The ability of our eyes to quickly view objects ...
Severe hot flashes which occur at night and result in a drenching sweat. Night sweats can have many different causes including medications, infections, and cancers.
A disorder occurring in children, in which the child awakes screaming with fright, the distress persisting for a time during a state of semiconsciousness. SYN: pavor nocturnus, ...
A device used to stabilize the teeth and reduce the traumatic effects of bruxism.
Florence, 1820-1910. English nurse; founder of modern nursing.
A terrifying dream, as in which one is unable to cry for help or to escape from a seemingly impending evil. SEE ALSO: incubus, succubus. [A.S. nyht, night, + mara, a demon] ...
Any of a number of plants of the genus Solanum (family Solanaceae) and of some other genera of the family Solanaceae.
- deadly n. SYN: belladonna.
Stands for the National Institute of General Medical Sciences, one of the National Institutes of Health in the U.S., whose mission is to “support basic biomedical research that ...
In neuroanatomy, the substantia n.. [L. fr. niger, black]
A black pigmentation. [L. blackness, fr. niger, black]
- n. linguae SYN: black tongue.
A variable mixture of blue-black aniline dyes; used as a histologic stain for nervous tissue and as a negative stain for studying bacteria and spirochetes; also used to ...
A genus of rapidly growing fungi that produces shiny, black conidia in cultures; it is a common contaminant in laboratory cultures and is nonpathogenic for humans.
Referring to the efferent connection of the substantia nigra with the striatum. See substantia nigra.
The National Institutes of Health. The NIH is an important U.S. health agency. It is devoted to medical research. Administratively under the Department of Health and Human ...
1. In psychiatry, the delusion of the nonexistence of everything, especially of the self or part of the self. 2. Engagement in acts that are totally destructive to one's own ...
Nijmegen breakage syndrome
: A genetic disease named for the city of Nijmegen (in The Netherlands) with increased chromosome breakage, immunodeficiency and an increased risk of malignancy. Children with ...
Drug that acts mainly on the central nervous system, as a respiratory and cardiovascular stimulant.
Mikhail, Russian dermatologist, 1858–1915. See N. method.
Pyotr V., Russian dermatologist, 1858–1940. See N. sign.
Nile blue A
A basic oxazin dye, used as a fat and vital stain, and in Kittrich stain; as an indicator, it changes from blue to purplish red at pH 10–11.
Stands for the National Institute of Mental Health, one of the National Institutes of Health in the U.S., whose mission is to “provide national leadership dedicated to ...
A calcium channel blocking drug of the dihydropyridine series used as a vasodilator.
A nitrosourea antineoplastic similar to carmustine ( BCNU)
Stands for the National Institute of Neurological Disorders and Stroke, one of the National Institutes of Health in the U.S., whose mission is to ”support and conduct research ...
An acute highly contagious viral disease with fever, runny nose, cough, red eyes, and a spreading skin rash. the measles, also known as rubeola, is a potentially disastrous ...
Reacts with free amino acid s to yield CO2, NH3, and an aldehyde, the NH3 produced yielding a colored product (diketohydrindylidene-diketohydrinamine, a bi-indanedione ...
Stands for the National Institute of Nursing Research, one of the National Institutes of Health, whose mission is to “sponsor research that focuses on the clinical care of ...
Ninth cranial nerve
The ninth cranial nerve is the glossopharyngeal nerve. The 12 cranial nerves, the glossopharyngeal nerve included, emerge from or enter the skull (the cranium), as opposed to the ...
A rare metallic element, atomic no. 41, atomic wt. 92.90638, usually found with tantalum. [Niobe, daughter of Tantalus]
The National Institute for Occupational Safety and Health, a US Federal agency responsible for conducting research and making recommendations for the prevention of work-related ...
A virus that infects pigs and people in whom it causes a sometimes fatal form of viral encephalitis (brain inflammation). Nipah is the name of the first village the virus struck ...
The pigmented projection on the surface of the breast. Ducts that conduct milk from the mammary glands to the surface of the breast exit through the nipple. The surrounding flat ...
Medically called athelia, this is a rare condition but it is common in certain conditions. Athelia tends to occurs on one side (unilaterally) in children with the Poland ...
An extra nipple. Supernumerary nipples are usually smaller than normal and vestigial (nonfunctional, without accompanying mammary glands). They tend to occur on along a ...
Used for the treatment of schistosomiasis, amebiasis, and dracontiasis.
A polypeptide antibiotic produced by Streptococcus lactis; active against certain streptococci, Mycobacterium tuberculosis, Clostridium difficile, and other bacteria.
A calcium channel blocker of the dihydropyridine series; used as an antihypertensive and antianginal agent.
Rudolf, Swiss surgeon, 1896–1981. See Collis-N. fundoplication, N. fundoplication, N. operation.
Franz, German neurologist, 1860–1919. See N. bodies, under body, N. degeneration, N. granules, under granule, N. substance, N. stain.
Nits are lice eggs. They are hard to see and are often confused with dandruff or hair spray droplets. Nits are found firmly attached to the hair shaft. They are oval and usually ...
Raissa, 19th century German physician. See N. layer, N. membrane, N. stria.
SYN: potassium nitrate. [G. nitron, soda, formerly not distinguished from potash]
- cubic n. SYN: sodium nitrate.
Archaic term for radon.
A hypnotic and sedative of the benzodiazepine class.
A calcium channel blocker of the dihydropyridine series; used as an antihypertensive.
A strong acid oxidant and corrosive.
- fuming n. contains about 91% n.; used as a caustic.
A colorless, radical-free gas that reacts rapidly with O2 to form other nitrogen oxides (e.g., NO2, N2O3, and N2O4) and ultimately is converted to nitrite (NO2−) and nitrate ...
Formation of nitrides; formation of nitrogen compounds through the action of ammonia ( analogous to oxidation).
A compound of nitrogen and one other element, e.g., magnesium n., Mg3N2.
1. Bacterial conversion of nitrogenous matter into nitrates. 2. Treatment of a material with nitric acid.
An alkyl cyanide. Individual nitriles are named for the acid formed on hydrolysis; e.g., CH3CN is acetonitrile rather than methyl cyanide.
Prefix indicating a tervalent nitrogen atom attached to three identical groups; e.g., nitrilotriacetic acid, N(CH2COOH)3.
The presence of nitrites in the urine, as a result of the action of Escherichia coli, Proteus vulgaris, and other microorganisms that may reduce nitrates.
Prefix denoting the group –NO2. [G. nitron, sodium carbonate.]
Antimicrobials ( e.g., nitrofurazone) effective against Gram-positive and Gram-negative organisms.
A urinary antibacterial agent with a wide range of activity against both Gram-positive and Gram-negative organisms; also available as n. sodium for injection.
A topical bacteriostatic and bactericidal agent often used in burns.
1. A gaseous element, atomic no. 7, atomic wt. 14.00674; N2 forms about 78.084% by volume of the dry atmosphere. 2. The molecular form of n., N2. 3. Pharmaceutical grade N2, ...
Five trivalent or quinquivalent elements whose hydrogen compounds are basic and whose oxyacids vary from monobasic to tetrabasic : nitrogen, phosphorus, arsenic, antimony, ...
The length of time after the ingestion of a given protein before the amount of nitrogen equal to that in the protein has been excreted in the urine.
Determination of the distribution of nitrogen in the urine among the various constituents. SYN: nitrogen distribution.
A cyclotron-produced, positron-emitting radioisotope of nitrogen with a half-life of 9.97 minutes; used in protein metabolism studies and in positron-emission tomography.
The common nitrogen isotope, making up 99.63% of natural nitrogen.
The less common stable nitrogen isotope, making up 0.37% of natural nitrogen. SYN: heavy nitrogen.
Formerly a general term used to describe enzyme systems that catalyze the reduction of molecular nitrogen to ammonia in nitrogen-fixing bacteria; now specifically applied to ...
A molecule that contains nitrogen and has the chemical properties of a base. The nitrogenous bases in DNA are adenine (A), guanine (G), thymine (T), and cytosine (C). The ...
An explosive yellowish oily fluid formed by the action of sulfuric and nitric acid s on glycerin; used as a vasodilator, especially in angina pectoris; generates nitric oxide. ...
An extremely caustic mixture that contains 18 parts nitric acid and 82 parts hydrochloric acid. SYN: aqua regia, aqua regalis, nitrimuriatic acid.
The anhydride of 4-nitro-3-hydroxymercuriorthocresol; a synthetic organic mercurial compound, used as an antiseptic for skin and mucous membranes.
A device for collecting and measuring the nitrogen set free in a chemical reaction. [nitrogen + G. metron, measure]
A reagent for the determination of nitric acid, perchlorate, and rhenium, as it is one of the few substances to form an insoluble nitrate.
O2N–C6H4–S–; nitrophenylthio; a radical easily attached to amino groups; used in peptide synthesis and protein chemistry.
The anion [Fe(CN)5NO]=; as in sodium n.; used as a vasodilator by the intravenous route.
Amines substituted by a nitroso (NO) group, usually on a nitrogen atom, to yield N-n. (R–NH–NO or R2N–NO); can be formed by direct combination of an amine and nitrous acid ...
Prefix denoting a compound containing nitrosyl. [L. nitrosus]
Alkylating agent used in the treatment of many neoplasms; an example is BCNU [N,N′-bis(2-chloroethyl)-N-n.; carmustine].
: A group of anticancer drugs that can cross the blood-brain barrier. Carmustine (BCNU) and lomustine (CCNU) are nitrosoureas.
A univalent radical or atom group, –N=O, forming the nitroso compounds.
Denoting a nitrogen compound containing one less atom of oxygen than the nitric compounds; one in which the nitrogen is present in its trivalent state.
HNO2; a standard biologic and clinical laboratory reagent.
N2O; a nonflammable, nonexplosive gas that will support combustion; widely used as a rapidly acting, rapidly reversible, nondepressant, and nontoxic inhalation analgesic to ...
Nitrous oxide (laughing gas)
A gas that can cause general anesthesia. Nitrous oxide is sometimes given in the company of other anesthetic agents but it is not used today as the only anesthetic agent because ...
The –O–NO2 radical. [contraction of nitryloxy]
The radical –NO2 of the nitro compounds.
A histamine H2 antagonist used to treat active duodenal ulcers.
A nonvenereal disease of children in Zimbabwe, indistinguishable from syphilis, due to an organism apparently identical with Treponema pallidum; probably the same as bejel. ...
Abbreviation for nanokatal.
Abbreviation for norleucine.
NLM (National Library of Medicine)
The world's largest medical library, the U.S. National Library of Medicine (NLM) is part of the National Institutes of Health (NIH). The NLM has as its mission to collect, ...
Abbreviation for National League for Nursing.
Abbreviation for nanomolar.
Abbreviation for nanometer.
Abbreviation for N-methyl d-aspartate; excitotoxic amino acid used to identify a specific subset of glutamate (an excitatory amino acid) receptors. SYN: N-methyl d-aspartic ...
Abbreviation for nicotinamide mononucleotide.
Abbreviation for nucleoside 5′-monophosphate.
Nuclear Magnetic Resonance. An imaging technique that does not use radiation.
* * *
Abbreviation for nuclear magnetic resonance.
Symbol for nitric oxide.
Term used in the US for a patient who missed an appointment. (In the UK, a patient who failed an appointment "did not attend." This is abbreviated DNA, not to be confused with the ...
M., 20th century German physician. See N. syndrome.
An unstable transuranium element, atomic no. 102, prepared by bombardment of curium with carbon-12 nuclei and similar heavy ions on other elements of the transuranium series. ...
Charles P., U.S. gynecologist, 1863–1935. See N. position.
Robert L., Canadian physiologist, *1910. See N.- Collip procedure.
Edmund I.E., French veterinarian, 1850–1903. See Nocardia, Nocardiaceae.
A genus of aerobic actinomycetes (family Nocardiaceae, order Actinomycetales), higher bacteria, containing weakly acid-fast, slender rods or filaments, frequently swollen and ...
A vernacular term used to refer to any member of the genus N..
Also called nocardiosis, infection with bacteria called Nocardia which tend to strike the lungs, brain and skin, particularly in people with an impaired immune system. The ...
A family of acid-fast, Gram-positive, aerobic bacteria (order Actinomycetales) that includes the genus Nocardia. [E. Nocard]
Denoting an organism that morphologically and culturally resembles members of the genus Nocardia.
A genus of higher bacteria living in soil that cause subacute or chronic pneumonia, subcutaneous infection, or disseminated disease, usually in immunosuppressed patients.
- N. ...
A generalized disease in humans and other animals caused by Nocardia asteroides, N. otitidiscaviarum, N. transvalensis, and N. brasiliensis and characterized by primary pulmonary ...
An unpleasant effect attributable to administration of a placebo; jargon. [L. I shall harm, fr. noceo, to harm, by analogy with placebo, I shall please]
Hurt, pain, injury. [L. noceo]
Capable of appreciation or transmission of pain. [see nociceptor]
A peripheral nerve organ or mechanism for the reception and transmission of painful or injurious stimuli. [ noci- + L. capio, to take]
Denoting processes or mechanisms that act to protect the body from injury; specifically, a system of nerves in the skin and mucous membranes that react to adjacent injury by ...
Nocturnal. SEE ALSO: nycto-. [L. nox, night]
Abbreviation for L. nocte maneque, at night and in the morning.
A pathologic increase of albumin in urine excreted during the evening, a rarely observed event. [L. nox, night, + albuminuria]
Morbid dread of night and its darkness and silence. [ noct- + phobia]
SYN: scotograph. [ noct- + G. grapho, to write]
Purposeful urination at night, after waking from sleep; typically caused by increased nocturnal secretion of urine resulting from failure of suppression of urine production ...
Pertaining to the hours of darkness; opposite of diurnal (1). [L. nocturnus, of the night]
Amblyopia refers to blindness so nocturnal amblyopia is, literally, night blindness. Listed in medical dictionaries under "Nyctalopia" from the Greek nyct (night) + aloas ...
Relating to any node.
Literally a knot, a node is a collection of tissue. For example a lymph node, is a collection of lymphoid tissue. A nodule is a small node, a little collection of tissue.
* * *
The atrioventricular (AV) node is an electrical relay station between the atria (the upper) and the ventricles (the lower chambers of the heart). Electrical signals from the ...
AV node: The AV node (AV stands for atrioventricular) is an electrical relay station between the atria (the upper) and the ventricles (the lower chambers of the heart). ...
A small fixed bump on the finger, usually at the last joint of the finger, Heberden’s node is a calcified spur of the joint (articular) cartilage and is a sign of ...
The SA node (SA stands for sinoatrial) is one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system ...
Node, sentinel lymph
The first lymph node ("gland") to receive lymphatic drainage from a tumor. Which lymph node is the sentinel node for a given tumor is determined by injecting around the tumor a ...
The sinoatrial is one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system generates electrical ...
The sinus node is one of the major elements in the cardiac conduction system, the system that controls the heart rate. This stunningly designed system generates electrical ...
A diagnostic sign of bacterial infection of the heart (subacute bacterial endocarditis). These are small (the size of split peas), tender, transient nodules in the pads of ...
Plural of nodus. [L.]
Having nodes or knotlike swellings. [L. nodosus]
Nodular hyperplasia of the prostate
: Nonmalignant (noncancerous) enlargement of the prostate gland, a common occurrence in older men. It is also known as benign prostatic hyperplasia or hypertrophy (abbreviated ...
The formation or the presence of nodules.
A small solid collection of tissue, a nodule is palpable (can be felt). It may range in size from greater than 1.0 cm (3/8 inch) to somewhat less than 2 cm (13/16 inch) in ...
A small hard fixed bump on the finger, usually at the last joint of the finger. A Heberden nodule is a calcified spur of the joint (articular) cartilage. It serves as a useful ...
1. SYN: nodule. 2. The posterior extremity of the inferior vermis of the cerebellum, forming with the posterior medullary velum the central portion of the flocculonodular ...
SYN: node. [L. a knot]
- n. atrioventricularis [TA] SYN: atrioventricular node.
- n. buccinatorius SYN: buccal lymph node.
- n. sinuatrialis [TA] SYN: sinuatrial node.
- n. ...
lymph node. [lympho- + L. nodus, node]
- nodi lymphatici colici SYN: colic lymph node s, under lymph node.
- nodi lymphatici comitantes nervi accessorii SYN: accessory lymph ...
SYN: lymph node.
- nodi lymphoidei abdominis [TA] SYN: abdominal lymph node s, under lymph node.
- nodi lymphoidei accessorii [TA] SYN: accessory lymph node s, under lymph ...
Abbreviation for nuclear Overhauser effect.