| nitrogen monoxide | <chemical> Nitrogen oxide (n2o). A colourless, odourless gas that is used as an anaesthetic and analgesic. High concentrations cause a narcotic effect and may replace oxygen, causing death by asphyxia. It is also used as a food aerosol in the preparation of whipping cream. Pharmacological action: aerosol propellants, analgesics, non-narcotic, anaesthetics, inhalation. Chemical name: Nitrogen oxide (N2O) (12 Dec 1998) |
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| nitrogen mustard compounds | <chemical> A group of alkylating agents derived from mustard gas, with the sulfur replaced by nitrogen. They were formerly used as toxicants and vesicants, but now function as antineoplastic agent. These compounds are also powerful mutagens, teratogens, immunosuppressants, and carcinogens. Pharmacological action: antineoplastic agent, alkylating, carcinogens, mutagens, teratogens. (12 Dec 1998) |
| nitrogen mustards | <pharmacology> A series of tertiary amine compounds having vesicant properties similar to those of mustard gas. They have the general formula RN(CH2CH2Cl)2. They can alkylate compounds such as DNA and are used as the basis of cytostatic drugs for cancer chemotherapy. (18 Nov 1997) |
| nitrogen narcosis | Narcosis produced by nitrogenous materials such as occurs in certain forms of uraemia and hepatic coma, the stuporous condition characterised by disorientation and by loss of judgment and skill, attributed to an increased partial pressure of nitrogen in the inspired air of deepsea divers during underwater operations. Commonly referred to as "rapture of the deep." (05 Mar 2000) |
| nitrogen oxides | Inorganic oxides that contain nitrogen. (12 Dec 1998) |
| nitrogen partition | Determination of the distribution of nitrogen in the urine among the various constituents. Synonym: nitrogen distribution. (05 Mar 2000) |
| nitrogen radioisotopes | Unstable isotopes of nitrogen that decay or disintegrate emitting radiation. N atoms with atomic weights 12, 13, 16, 17, and 18 are radioactive nitrogen isotopes. (12 Dec 1998) |
| nonprotein nitrogen | The nitrogen content of other than protein bodies; e.g., about one-half the nonprotein nitrogen in the blood is contained in urea. Synonym: rest nitrogen. (05 Mar 2000) |
| undetermined nitrogen | The nitrogen of blood, urine, etc., other than urea, uric acid, amino acids, etc., that can be directly estimated; in blood it amounts to about 25 mg per 100 ml. Urea nitrogen, the portion of nitrogen in a biological sample, such as blood or urine, that derives from its content of urea. See: blood urea nitrogen. (05 Mar 2000) |
| urinary nitrogen | Nitrogen excreted as urea, amino acids, uric acid, etc., in the urine; 1 g of urinary nitrogen indicates the breakdown in the body of 6.25 g of protein. See: nitrogen equivalent. (05 Mar 2000) |
| filtrate nitrogen | Nonprotein nitrogen in various compounds that normally pass through the glomerular filtration, or through a filter in the laboratory (after proteins are precipitated). (05 Mar 2000) |
| bone scan: falsely negative metastases | <radiology> Anaplastic tumours, reticulum cell sarcoma, renal cell carcinoma, thyroid carcinoma, histiocytosis, neuroblastoma, multiple myeloma (positive scan usually due to recent or impending fracture) (12 Dec 1998) |
| ventilators, negative-pressure | Body ventilators that assist ventilation by applying intermittent subatmospheric pressure around the thorax, abdomen, or airway and periodically expand the chest wall and inflate the lungs. They are relatively simple to operate and do not require tracheostomy. These devices include the tank ventilators ("iron lung"), portalung, pneumowrap, and chest cuirass ("tortoise shell"). (12 Dec 1998) |
| gram-negative | <microbiology> A common class of bacteria normally found in the gastrointestinal tract that can be responsible for disease in man (sepsis). Bacteria are considered to be gram-negative because of their characteristic staining properties under the microscope, where they either do not stain or are decolourised by alcohol during Gram's method of staining. This is a primary characteristic of bacteria that have a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide containing endotoxin. The gram staining characteristics of bacteria have resulted in an important classification system for the identification of bacteria. See: gram-positive (06 Oct 1997) |
| gram-negative aerobic bacteria | <microbiology> A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |