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N

1. Symbol for the element nitrogen. 2. normal (no longer in technical use). 3. neuraminidase.

n

1. Symbol for index of refraction. 2. nasal; number. 3. In statistics, sample size. 4. In the TNM system of cancer staging, the number of lymph nodes that have been invaded by a cancer.

15N

The symbol for the isotope of nitrogen with mass number 15; radioactive; atomic mass (weight) 15.

NA

nicotinic acid; Nomina Anatomica; not applicable; numerical aperture; nurse's aide.

Na

[L. natrium] Symbol for the element sodium.

NAACCR

North America Association of Central Cancer Registries.

nab-

(nab) [Acronym of nanoparticle albumin bound] Bound by nanoparticles to albumin. Chemically linking some drugs to albumin increases their uptake by cells. Nanoparticle albumin-bound drugs have been used to increase the effectiveness of several cancer chemotherapeutic drugs.

N-acetyl-p-aminophenol

(ă-mē″nō-fē′nōl″, am″ĭ-nō-) ABBR: APAP. SEE: acetaminophen.

NaCl

Sodium chloride.

nacreous

(nā′krē-ŭs) [L. nacer, mother of pearl] Having an iridescent pearl-like luster, as bacterial colonies.

NAD

nicotinamide adenine dinucleotide; no appreciable disease.

NAD+

nicotinamide adenine dinucleotide, oxidized form.

NADH

nicotinamide adenine dinucleotide, reduced form.

nadir

(nā′dĕr) [Arabic] 1. A low point in any measurement. 2. The lowest concentration of blood cells (esp. white blood cells) found after taking a drug that suppresses the bone marrow. The term is usually used for the low blood cell counts that occur after cancer chemotherapy. When the absolute neutrophil count reaches a nadir below 1000 cells/mm3, the risk of life-threatening infections increases dramatically.

NADP+

nicotinamide adenine dinucleotide phosphate, oxidized form.

NADP

nicotinamide adenine dinucleotide phosphate.

NADPH

nicotinamide adenine dinucleotide phosphate, reduced form.

Naegele, Franz Carl

(nā′gĕ-lē) [German obstetrician, 1777–1851]

N.'s obliquity. Anterior parietal presentation of the fetal head in labor. SYN: anterior asynclitism.

N.'s rule A numerical formula for estimating the date labor will begin; by subtracting 3 months from the first day of the last menstrual period and adding 7 days to that date, a provisional date of delivery is identified.

Naegleria

(nā-glēr′ē-ă) A genus of ameba present in soil, ground water, and sewage. One species, N. fowleri, is the cause of a rapidly lethal form of hemorrhagic meningoencephalitis (brain and ...

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