Medications

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. Last Editorial Review: 4/27/2011 5:27:15 PM...

Nodding syndrome - Medical

Nodding syndrome: A mysterious disease of children that causes seizures, growth retardation (stunted growth), mental retardation and often, but not invariably, death. Some children with the syndrome appear to recover. Head nodding while eating is the...

Nocturnal enuresis - Medical

Nocturnal enuresis: Bedwetting at night. From the Greek "enourin" meaning "to urinate in." Last Editorial Review: 4/27/2011 5:27:15 PM Medical Author: David Perlstein, MD, MBA, FAAP ...

Nocturnal amblyopia - Medical

Nocturnal amblyopia: Amblyopia refers to blindness so nocturnal amblyopia is, literally, night blindness. Listed in medical dictionaries under "Nyctalopia" from the Greek nyct (night) + aloas (obscure or blind) + opsis (vision), the condition invol...

Nocturia - Medical

Nocturia: Excessive urinating at night. People with nocturia must get up, often two times or more, during the night to urinate. Normally, urine is more concentrated at night and is produced in lower amounts, so that uninterrupted sleep is possible. H...

Nocebo - Medical

Nocebo: A negative placebo effect as, for example, when patients taking medications experience adverse side effects unrelated to the specific pharmacological action of the drug. The nocebo effect is associated with the person's prior expectations of ...

Nocardiosis - Medical

Nocardiosis: An infection with bacteria called Nocardia which tend to strike the lungs, brain and skin, particularly in people with an impaired immune system. The majority (about 80%) of cases of nocardiosis involves lung infection, brain abscess, or...

Nocardia infection - Medical

Nocardia infection: 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 majority (about 80%) of cases of nocardiosis involves lung...

No show - Medical

No show: 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 genetic material.)Last Editorial Review: 7/6/2000 5:51:00 AM...

NMR - Medical

NMR: Nuclear Magnetic Resonance. An imaging technique that does not use radiation. Last Editorial Review: 4/27/2011 5:27:15 PM...

NLM (National Library of Medicine) - Medical

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, organize, and make available biomed...

NLD - Medical

NLD: Necrobiosis lipoidica diabeticorum.Last Editorial Review: 3/16/2004 Necrobiosis lipoidica diabeticorum: A dull red raised area on the skin that evolves into a shiny scar with a violet border, most often on the shin. There is telangiectasi...

NK cell - Medical

NK cell: See Natural killer cell.Last Editorial Review: 10/22/2002 Natural killer cell: A cell that can react against and destroy another cell without prior sensitization to it. Natural killer (NK) cells are part of our first line of defense again...

Nitrous oxide (laughing gas) - Medical

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 concentration of nitrous oxide needed ...

Nitrosoureas - Medical

Nitrosoureas: A group of cancer drugs called alkylating agents because they act by the process of alkylation to inhibit DNA repair. The nitrosoureas can cross the blood-brain barrier and are used to treat brain tumors. The nitrosoureas include carmus...

Nitrogenous base - Medical

Nitrogenous base: 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 nitrogenous bases in RNA are the same with one excep...

Nitrogen, liquid - Medical

Nitrogen, liquid: See: Liquid nitrogen. Last Editorial Review: 5/27/2004 Liquid nitrogen: Nitrogen in a liquid state. Liquid nitrogen is supercool -- about 200 degrees Celsius (320 degrees Fahrenheit) below zero -- and is used for cryopreservation,...

Nitrogen narcosis - Medical

Nitrogen narcosis: A condition similar to intoxication with alcohol with euphoria, loss of balance and manual dexterity, disorientation and impaired reasoning that occurs in divers below 100 feet (30 meters) who breath compressed air because of the h...

Nitrogen - Medical

Nitrogen: Element number 7, a colorless, odorless, tasteless gas that is biologically important. Nitrogen is a constituent of protein and nucleic acids and is present in all living cells. Nitrogen does not support respiration and is fatal if breathed...

Nitric oxide - Medical

Nitric oxide: A compound that is toxic but which, paradoxically, plays a number of important roles in the body, including the following: It acts as a vasodilator (blood vessel relaxant). It therefore controls blood flow to tissues. It regulates ...

Nit - Medical

Nit: 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 yellow to white. Nits take about a week to hatch. All nits mu...

Nirenberg , Marshall W. - Medical

Nirenberg , Marshall W.: (b. 1927) American biochemist who shared the 1968 Nobel Prize in Physiology or Medicine for his work in deciphering the genetic code. Marshall Warren Nirenberg was born in New York City. In 1941, Marshall developed rheumatic...

Nirenberg - Medical

Nirenberg: See: Nirenberg, Marshall W.Last Editorial Review: 10/19/2003 Nirenberg , Marshall W.: (b. 1927) American biochemist who shared the 1968 Nobel Prize in Physiology or Medicine for his work in deciphering the genetic code. Marshall Warren N...

Nipple shield - Medical

Nipple shield: A cap or dome, usually made today of plastic (formerly, rubber), placed over the nipple and areola during nursing to permit the flow of milk, provide a larger surface for the baby to latch onto, and protect the breast if it is sore. H...

Nipple discharge - Medical

Nipple discharge: See: Breast discharge.Last Editorial Review: 10/25/2003 Breast discharge: The spontaneous flow of fluid from the nipple at any time other than during nursing. This can be due to an unrecognized pregnancy, trauma, surgery, overexerc...

Nipple confusion - Medical

Nipple confusion: A problem that may beset a bottlefed baby in which it forgets how to nurse on mother's nipple. Breastfeeding requires far more vigorous mouth and tongue motions and greater muscle coordination than bottlefeeding. On bottle nipples ...

Nipple - Medical

Nipple: 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 area of pigmentation is the areola.Last Editorial Revie...

Nipah virus - Medical

Nipah virus: 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 near Kuala Lumpur in Malaysia. The Nipah virus is similar t...

NIOSH - Medical

NIOSH: 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 disease and injury. Despite its name (which would suggest that...

Ninth cranial nerve - Medical

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 spinal nerves which emerge from the vertebral col...