|Medical Dictionary - Dictionary of Medicine and Human Biology|
An acetylated derivative of aspartate found in the brain. Used as a marker in brain NMR and in neuroimaging.
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.
An intermediate in the synthesis of sulfanilamide; formed in animal bodies by acetylation of sulfanilamide. SYN: p-sulfamylacetanilide.
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.
A condensation product of an organic acid with sphingosine at the amino group of the latter compound.
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.
Heterocyclic derivatives of amino acids from which polypeptides may be synthesized.
SYN: allophanic acid.
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.
A derivative of one-carbon tetrahydrofolate formed via l-histidine catabolism.
N-formylglycinamide ribotide (FGAR)
An intermediate in purine biosynthesis.
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.
A formyl derivative of tetrahydrofolate that serves as a one-carbon source in metabolism.
Misnomer for glycosyl.
n-hexanoic acid (hek-sa-no′ik)
SYN: n-caproic acid.
n-icosanoic acid (i′ko-sa-no′ik)
SYN: arachidic acid.
A one-carbon derivative of tetrahydrofolate; used in purine biosynthesis.
N-methyl d-aspartic acid
SYN: anserine (2) .
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.
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.
An active one-carbon derivative of tetrahydrofolate that participates in the S-methylation of l-homocysteine. N5-methyltetrahydrofolate:homocysteine methyltransferase methionine synthase.
Symbol for seminormal.
Symbol for nitrogen-15.
Symbol for nitrogen-14.
Symbol for nitrogen-13.
Symbol for Avogadro number.
Abbreviation for Loschmidt number.
Abbreviation for Nomina Anatomica.
Abbreviation for numerical aperture.
Symbol for sodium (natrium).
Symbol for sodium-24.
A synthetic cannabinoid used in the treatment of nausea and vomiting associated with cancer chemotherapy.
Martin, German anatomist and physician, 1675–1721. See nabothian cyst, follicle.
Lustrous, like mother-of-pearl; descriptive term for bacterial colonies. [Fr. nacre, mother-of-pearl]
Abbreviation for nicotinamide adenine dinucleotide.
Abbreviation for no appreciable disease; nothing abnormal detected (British).
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.
SYN: NAD+ nucleosidase.
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.
A nicotinamide adenine dinucleotide compound used as an antagonist to alcohol and narcotics.
The lowest value of blood counts after chemotherapy. [M.E., Med. L., lowest point, fr. Arabic nazir, opposite (the zenith)]
See under reaction.
A β-adrenergic blocking agent with actions similar to those of propranolol.
Abbreviation for nicotinamide adenine dinucleotide phosphate.
Abbreviation for nicotinamide adenine dinucleotide phosphate (oxidized form).
An enzyme hydrolyzing NAD(P)+ to release free nicotinamide and adenosinediphosphoribose(phosphate).
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.
Otto, Swiss physician, 1871–1938. See N. type of monocytic leukemia.
Oskar, Swiss physician, 1885–1959. See N. syndrome.
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.
A semisynthetic penicillin derived from 6-aminopenicillanic acid; resistant to penicillinase, and effective against Staphylococcus aureus. n. sodium a penicillinase-resistant penicillin.
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.
Abbreviation for N-acetylglutamate.
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.
Willibald A., German ophthalmologist and physiologist, 1870–1911. See N. test.
Franz K., German obstetrician, 1777–1851. See N. obliquity, N. pelvis, N. rule.
Karl W. von, Swiss botanist, 1817–1891. See micelle.
Jean, French histologist, 1866–1948. See N. cells, under cell.
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