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Medical Dictionary - Dictionary of Medicine and Human Biology


Medical Dictionary


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ν
  • Nu, the 13th letter of the Greek alphabet
  • Symbol for kinematic viscosity
  • frequency
  • stoichiometric number
  • the position of a substituent located on the thirteenth atom from the carboxyl or other functional group.
N
  • asparagine
  • nasal
  • newton
  • nitrogen
  • nucleoside
  • normal solution
  • haploid chromsome number
  • Designation for an inherited blood factor
  • refraction index
n
  • antigen of human blood that shares a common genetic locus with the M antigen
  • haploid or gametic number of chromosomes
  • nano-
  • reaction order.
  • normal concentration
  • number in a scientific study
  • Sample size
  • refractive index.
N-acetylaspartate (as′-e-til-as-par′tat)
An acetylated derivative of aspartate found in the brain. Used as a marker in brain NMR and in neuroimaging.

N-acetylglucosamine (as′e-til-glu-cos′a-men)
An acetylated amino sugar that is an important moiety of glycoproteins.

N-acetylglutamate (NAG) (a-se′til-gloo′ta-mat)
The salt of N-acetylglutamic acid. An activator of carbamoyl phosphate synthetase I during urea synthesis; this amino acid causes a configurational change in the enzyme, increasing the activity of that enzyme. The inability to synthesize acetylglutamate results in a defect in urea biosynthesis.

N-acetylneuraminic acid (NeuAc) (as′e-til-nur-a-min′ik-as′id)
The most common form of sialic acid in mammals.

N4-acetylsulfanilamide (as′e-til-sul-fa-nil′a-mid)
An intermediate in the synthesis of sulfanilamide; formed in animal bodies by acetylation of sulfanilamide. SYN: p-sulfamylacetanilide.

N1-acetylsulfanilamide
An antibacterial sulfa drug used topically and in the eye.

n-acylamino acid (as-il-am′i-no)
An amino acid that has an acyl group attached to its N, as in hippuric acid (N-benzoylglycine) or phenaceturic acid.

N-acylsphingosine (as-il-sfing′go-sen)
A condensation product of an organic acid with sphingosine at the amino group of the latter compound.

N-allylnormorphine (al′il-nor-mor′fen)
SYN: nalorphine.

n-capric acid (kap′rik)
A fatty acid found among the hydrolysis products of fat in goat's milk, cow's milk, and other substances. Cf.:n.caproic acid, caprylic acid. SYN: n-decanoic acid.

n-caproic acid (kap-ro′ik)
A fatty acid found among the hydrolysis products of fat in butter, coconut oil, and some other substances. SYN: n-hexanoic acid.

N-carbamoylaspartic acid (kar′ba-mo-il-as-par′tik)
SYN: ureidosuccinic acid.

N-carbamoylglutamic acid (kar′ba-mo-il-gloo-tam′ik)
An intermediate in the carbamoylation of ornithine to citrulline in the urea cycle; used in the treatment of individuals having a deficiency of the enzyme that synthesizes N-acetylglutamate.

N-carboxyanhydrides (kar-bok′se-an-hi′dridz)
Heterocyclic derivatives of amino acids from which polypeptides may be synthesized.

N-carboxyurea (kar-bok′se-u-re′a)
SYN: allophanic acid.

n-decane (dek′an)
A paraffin hydrocarbon, CH3&cbond;(CH2)8&cbond;CH3.

n-decanoic acid (dek-a-no′ik)
SYN: n-capric acid.

N,N-dimethyltryptamine (DMT) (di-meth′il-trip′ta-men)
A psychotomimetic agent present in several South American snuffs ( e.g., cohoba snuff) and in the leaves of Prestonia amazonica (family Apocynaceae). Effects are similar to those of LSD, but with more rapid onset, greater likelihood of a panic reaction, and a shorter duration (1 to 2 hours, “businessman's trip”); it produces pronounced autonomic effects, including a marked increase in blood pressure.

n-docosanoic acid (do′ko-san-o′ik)
SYN: behenic acid.

n-dodecanoic acid (do-dek′a-no-ik)
SYN: lauric acid.

n-eicosanoic acid (i′ko-sa-no′ik)
SYN: arachidic acid.

N-formiminotetrahydrofolate (for-mim′i-no-tet′ra-hi-dro-fo′lat)
A derivative of one-carbon tetrahydrofolate formed via l-histidine catabolism.

N-formylglycinamide ribotide (FGAR)
An intermediate in purine biosynthesis.

N-formylkynurenine (en-for′mil-ki-noor′e-nen)
The product of the oxidative cleavage of the indole ring in l-tryptophan; the intermediate first formed in l-tryptophan catabolism.

N-formylmethionine (fMet) (for′mil-me-thi′o-nen)
Methionine acylated on the NH2 group by a formyl (–CHO) group. This is the starting amino acid residue for virtually all bacterial polypeptides. It is also observed in mitochondria and chloroplasts of eukaryotes. SEE ALSO: initiating codon.

N10-formyltetrahydrofolate
A formyl derivative of tetrahydrofolate that serves as a one-carbon source in metabolism.

N-glycoside
Misnomer for glycosyl.

n-heptylpenicillin (hep′til-pen-i-sil′in)
Penicillin K.

n-hexanoic acid (hek-sa-no′ik)
SYN: n-caproic acid.

n-icosanoic acid (i′ko-sa-no′ik)
SYN: arachidic acid.

N5,N10-methenyltetrahydrofolic acid
SYN: anhydroleucovorin.

N5,N10-methenyltetrahydrofolate
A one-carbon derivative of tetrahydrofolate; used in purine biosynthesis.

N-methyl d-aspartic acid
SYN: NMDA.

N-methylcarnosine (meth-il-kar′no-sen)
SYN: anserine (2) .

N5,N10-methylenetetrahydrofolate reductase
An enzyme that converts N5,N10-methylenetetrahydrofolate to N5,N10-methenyltetrahydrofolate using NADP+; a deficiency of this enzyme results in an accumulation of l-homocysteine and severe neurological disturbances.

N-methylglucamine
SYN: methylglucamine.

N-methylhistidine (meth′il-his′ti-den)
A methylated derivative of histidine found in actin; in the breakdown of actin and myosin, N-methylhistidine is released into the urine; urinary output of N-methylhistidine is a reliable index of the rate of myofibrillar protein breakdown in musculature.

N5-methyltetrahydrofolate (meth-il-tet′ra-hi-dro-fol-at)
An active one-carbon derivative of tetrahydrofolate that participates in the S-methylation of l-homocysteine. N5-methyltetrahydrofolate:homocysteine methyltransferase methionine synthase.

N/2
Symbol for seminormal.

15N
Symbol for nitrogen-15.

14N
Symbol for nitrogen-14.

13N
Symbol for nitrogen-13.

NA
Symbol for Avogadro number.

n0
Abbreviation for Loschmidt number.

NA
Abbreviation for Nomina Anatomica.

N.A.
Abbreviation for numerical aperture.

Na
Symbol for sodium (natrium).

24Na
Symbol for sodium-24.

nabilone (nab′i-lon)
A synthetic cannabinoid used in the treatment of nausea and vomiting associated with cancer chemotherapy.

Naboth
Martin, German anatomist and physician, 1675–1721. See nabothian cyst, follicle.

nacreous (na′kre-us)
Lustrous, like mother-of-pearl; descriptive term for bacterial colonies. [Fr. nacre, mother-of-pearl]

NAD
Abbreviation for nicotinamide adenine dinucleotide.

N.A.D.
Abbreviation for no appreciable disease; nothing abnormal detected (British).

NAD+
Abbreviation for nicotinamide adenine dinucleotide (oxidized form). NAD+ nucleosidase an enzyme hydrolyzing NAD+ to nicotinamide and adenosine diphosphoribose. SYN: NADase. NAD+ pyrophosphorylase an enzyme that participates in the synthesis of NAD+; it reacts nicotinamide mononucleotide with ATP to produce NAD+ and pyrophosphate; it will also act on nicotinate mononucleotide. NAD+ synthetase an enzyme that catalyzes the reaction of ATP, l-glutamine, and nicotinate adenine dinucleotide to form NAD+, ADP, and l-glutamate.

NADase
SYN: NAD+ nucleosidase.

NADH
Abbreviation for nicotinamide adenine dinucleotide (reduced form). N. dehydrogenase an iron-sulfur–containing flavoprotein reversibly oxidizing N. to NAD+; an inherited deficiency of this complex results in overwhelming acidosis. SYN: cytochrome c reductase. N. dehydrogenase (quinone) an enzyme oxidizing N. with quinones ( e.g., menaquinone) as acceptors. N.-hydroxylamine reductase an enzyme catalyzing the reaction of hydroxylamine and N. to form ammonia, NAD+, and water; used in a number of clinical assays.

nadide (na′did)
A nicotinamide adenine dinucleotide compound used as an antagonist to alcohol and narcotics.

nadir (na′der)
The lowest value of blood counts after chemotherapy. [M.E., Med. L., lowest point, fr. Arabic nazir, opposite (the zenith)]

Nadi reaction
See under reaction.

nadolol (na′do-lol)
A β-adrenergic blocking agent with actions similar to those of propranolol.

NADP
Abbreviation for nicotinamide adenine dinucleotide phosphate.

NADP+
Abbreviation for nicotinamide adenine dinucleotide phosphate (oxidized form).

NAD(P)+ nucleosidase
An enzyme hydrolyzing NAD(P)+ to release free nicotinamide and adenosinediphosphoribose(phosphate).

NADPH
Abbreviation for nicotinamide adenine dinucleotide phosphate (reduced form). N.-cytochrome c2 reductase an enzyme catalyzing the reduction of 2ferricytochrome c2 to 2ferrocytochrome c2 at the expense of N.. SYN: cytochrome c2 reductase. N. dehydrogenase a flavoprotein oxidizing N. to NADP+. SYN: N. diaphorase, old yellow enzyme, Warburg old yellow enzyme. N. dehydrogenase (quinone) a flavoprotein oxidizing NADH or N. to NAD+ or NADP+ with quinones ( e.g., menadione) as hydrogen acceptors. SYN: DT-diaphorase, menadione reductase, phylloquinone reductase, quinone reductase. N. diaphorase SYN: N. dehydrogenase. N.-ferrihemoprotein reductase (fer′i-he-mo-pro′ten, fer′e-) an enzyme catalyzing the reduction of 2 ferricytochrome by N. to 2 ferrocytochrome; the physiologic acceptor is probably cytochrome P-450; hence, it has a role in steroid hydroxylations. SYN: cytochrome reductase.

Naegeli
Otto, Swiss physician, 1871–1938. See N. type of monocytic leukemia.

Naegeli
Oskar, Swiss physician, 1885–1959. See N. syndrome.

Naegleria (na-gle′re-a)
A genus of free-living soil, water, and sewage ameba (order Schizopyrenida, family Vahlkampfiidae) one species of which, N. fowleri, has been implicated as the causative agent of the rapidly fatal primary amebic meningoencephalitis. Infection has been traced to swimming pools (including indoor chlorinated pools); entry is by the nasal mucosa, from which the amebae reach the meninges and brain through the cribriform plate and olfactory nerves. Other soil amebae that have been implicated, although of far less epidemiologic significance, include the genera Acanthamoeba and Hartmanella, the latter being a suspected but unproved causative agent.

nafcillin (naf′sil′in)
A semisynthetic penicillin derived from 6-aminopenicillanic acid; resistant to penicillinase, and effective against Staphylococcus aureus. n. sodium a penicillinase-resistant penicillin.

Naffziger
Howard C., U.S. surgeon, 1884–1961. See N. operation, N. syndrome.

naftifine hydrochloride (naf′ti-fen)
A broad-spectrum antifungal agent used in the topical treatment of tinea infections.

NAG
Abbreviation for N-acetylglutamate.

nagana (nah-gah′nah)
An acute or chronic disease of cattle, dogs, pigs, horses, sheep, and goats in sub-Saharan Africa; marked by fever, anemia, and cachexia, varying in severity with the parasite and the host. A collective term for diseases caused by the protozoan parasites Trypanosoma brucei brucei, T. congolense, and T. vivax.

Nagel
Willibald A., German ophthalmologist and physiologist, 1870–1911. See N. test.

Nägele
Franz K., German obstetrician, 1777–1851. See N. obliquity, N. pelvis, N. rule.

Nägeli
Karl W. von, Swiss botanist, 1817–1891. See micelle.

Nageotte
Jean, French histologist, 1866–1948. See N. cells, under cell.

nail (nal)
  • One of the thin, horny, translucent plates covering the dorsal surface of the distal end of each terminal phalanx of fingers and toes. A n. consists of corpus or body, the visible part, and radix or root at the proximal end concealed under a fold of skin. The underpart of the n. is formed from the stratum germinativum of the epidermis, the free surface from the stratum lucidum, the thin cuticular fold overlapping the lunula representing the stratum corneum, aka unguis, n. plate, onyx.
  • A slender rod of metal, bone, or other solid substance, used in operations to fasten together the fragments of a broken bone. [A.S. naegel]
  • egg shell n.: hapalonychia.
  • half and half n.: division of the n. by a transverse line into a proximal dull white part and a distal pink or brown part; seen in uremia.
  • Hippocratic nails: the coarse, curved nails capping clubbed digits.
  • ingrown n.: a toenail, one edge of which is overgrown by the nailfold, producing a pyogenic granuloma; due to faulty trimming of the toenails or pressure from a tight shoe, aka ingrowing toenail, onychocryptosis, unguis aduncus, unguis incarnatus.
  • Küntscher n.: an intramedullary n. used for internal fixation of a fracture.
  • parrot-beak n.: a markedly curved fingernail.
  • pincer n.: transverse overcurvature of the n. that increases distally, causing the lateral borders of the n. to pinch the soft tissue with resulting tenderness; may result from a developmental anomaly or subungual exostosis.
  • racket n.: a broad flat thumbnail resulting from a congenital shorter and wider distal phalanx of the thumb.
  • reedy n.: a n. marked by longitudinal ridges and furrows.
  • shell n.: n. dystrophy accompanying clubbing of digits in bronchiectasis, with excessive longitudinal curvature of the n. plate and atrophy of the n. bed and underlying bone.
  • Smith-Petersen n.: a triflanged n. for internal fixation of a fracture of the neck of the femur.
  • spoon n.: koilonychia.
  • yellow n.: the complete or almost complete cessation of all n. growth, with thickening of the nails, increase in the convexity, loss of cuticles, and yellowing; the resulting onycholysis can cause loss of some of the nails; the condition is often associated with pulmonary disease but differs from clubbing in that the soft tissues are not hypertrophic. Lymphatic drainage may be reduced, even in the absence of lymphedema, aka yellow n. syndrome.




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