| TW | tap water; terminal web; test weight; total body water; travelling wave |
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| TWE | tap water enema; tepid water enema |
| WS | Waardenburg syndrome; ward secretary; Warkany syndrome; Warthin-Starry [stain]; water soluble; water... |
| ABC | absolute basophil count; absolute bone conduction; acalculous biliary colic; acid balance control; a... |
| NK cell | Natural Killer cell |
natural purification (자정 작용
acute angle
| natural history | A former branch of knowledge embracing the study, description, and classification of natural objects (as animals, plants, and minerals) and thus including the modern sciences of zoology, botany, and mineralogy insofar as they existed at that time. In the 17th, 18th, and 19th centuries it was much used for the generalised pursuit of certain areas of science. (webster, 3d ed; from dr. James h. Cassedy, nlm history of medicine division) (12 Dec 1998) |
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| natural immunity | This includes local barriers to infection such as skin, stomach acid, mucous, the cough reflex, enzymes in tears and saliva and skin oils. (27 Sep 1997) |
| natural killer cell | <haematology, immunology> A certain type of white blood cell that attacks tumour cells and infected body cells by binding to a tumour cell and releasing lethal chemicals. Natural killer cells are thought to play a key role in cancer prevention by killing abnormal cells before they multiply and grow. (16 Dec 1997) |
| natural killer cells | Large granular lymphocytes which do not express markers of either T or B-cell lineage. These cells do possess Fc receptors for IgG and can kill target cells using antibody-dependent cell-mediated cytotoxicity. NK cells can also use perforin to kill cells in the absence of antibody. Killing may occur without previous sensitization. Synonym: NK cells. (05 Mar 2000) |
| natural killer cell stimulating factor | <cytokine> A 75 kD heterodimeric cytokine composed of disulfide-bonded 40 kD and 35 kD subunits that was originally identified by its ability to induce cytotoxic effector cells in synergy with less than optimal concentrations of interleukin-2. It is released by macrophages in response to infection and promotes the activation of cell-mediated immunity. Specifically, IL-12 triggers the maturation of Thl CD4 cells, specific cytotoxic T-lymphocyte responses and an increase in the activity of NK cells and consequently, it is the initiator of cell-mediated immunity. It enhances the lytic activity of NK cells, induces interferon production, stimulates the proliferation of activated T-cells and NK cells. Is secreted by human B lymphoblastoid cells (NC 37). May play a role in controlling immunoglobulin isotype selection as it also inhibits IgE synthesis (even in the presence of anti-IFN monoclonal antibody) and as a growth factor for activated CD4+ and CD8+ T-cells independently of interleukin-2, and for CD56+ NK cells but not resting peripheral blood mononuclear cells or resting or activated tonsillar B-cells. It is likely that interleukin 12 has a major role in protective immunity against viruses and is under study as an immunotherapy in HIV infection. Formerly referred to as cytotoxic lymphocyte maturation factor. Acronym: IL-12 (12 Dec 1998) |
| natural language processing | Computer processing of a language with rules that reflect and describe current usage rather than prescribed usage. (12 Dec 1998) |
| natural mutation | A mutation which occurs by itself without first being affected by a mutagen, for example during the process of DNA replication. Spontaneous mutations arise at a remarkably constant rate. The rate that spontaneous mutations arise has been used as an evolutionary clock to estimate how closely related two (or more) separate species are to each other. (09 Oct 1997) |
| natural passive immunity | Immunity conferred by the mother on the foetus or newborn. (14 Nov 1997) |
| natural pigment | A naturally occurring coloured compound; absorbs light in the visible range of the electromagnetic spectrum. Compare: structural colour. Synonym: biochrome. (05 Mar 2000) |
| natural products | Naturally occurring compounds that are end products of secondary metabolism; often, they are unique compounds for particular organisms or classes of organisms. (05 Mar 2000) |
| natural selection | The hypothesis that genotype environment interactions occurring at the phenotypic level lead to differential reproductive success of individuals and hence to modification of the gene pool of a population. (18 Nov 1997) |
| immunity, natural | The capacity of a normal organism to remain unaffected by microorganisms and their toxins. It results from non-specific mechanisms such as genetic endowment, naturally occurring antiviral and bactericidal substances, phagocytosis, and constitutional factors such as body temperature, oxygen tension, and age. (12 Dec 1998) |
| killer cells, natural | Cells responsible for spontaneous cytotoxicity of a variety of tumour cells without prior immunization. These natural killer cells are found in non-immune humans and experimental animals and are thought by some to be the same as killer cells (killing by antibody-dependent cell cytotoxicity), but they can also kill in the absence of antibody. (12 Dec 1998) |
| alkaline water | A water that contains appreciable amounts of the bicarbonates of calcium, lithium, potassium, or sodium. (05 Mar 2000) |
| aromatic water | 1. To wet or supply with water; to moisten; to overflow with water; to irrigate; as, to water land; to water flowers. "With tears watering the ground." (Milton) "Men whose lives gilded on like rivers that water the woodlands." (Longfellow) 2. To supply with water for drink; to cause or allow to drink; as, to water cattle and horses. 3. To wet and calender, as cloth, so as to impart to it a lustrous appearance in wavy lines; to diversify with wavelike lines; as, to water silk. Cf. Water. 4. To add water to (anything), thereby extending the quantity or bulk while reducing the strength or quality; to extend; to dilute; to weaken. To water stock, to increase the capital stock of a company by issuing new stock, thus diminishing the value of the individual shares. Cf. Water. Origin: AS. Waeterian, gewaeterian. 1. The fluid which descends from the clouds in rain, and which forms rivers, lakes, seas, etc. "We will drink water." ."Powers of fire, air, water, and earth." . Pure water consists of hydrogen and oxygen, H2O, and is a colourless, odorless, tasteless, transparent liquid, which is very slightly compressible. at its maximum density, 39 deg Fahr. Or 4 deg C, it is the standard for specific gravities, one cubic centimeter weighing one gram. It freezes at 32 deg Fahr. Or 0 deg C. And boils at 212 deg Fahr. Or 100 deg C. (see Ice, Steam). It is the most important natural solvent, and is frequently impregnated with foreign matter which is mostly removed by distillation; hence, rain water is nearly pure. It is an important ingredient in the tissue of animals and plants, the human body containing about two thirds its weight of water. 2. A body of water, standing or flowing; a lake, river, or other collection of water. "Remembering he had passed over a small water a poor scholar when first coming to the university, he kneeled." (Fuller) 3. Any liquid secretion, humor, or the like, resembling water; especially, the urine. 4. <pharmacology> A solution in water of a gaseous or readily volatile substance; as, ammonia water. 5. The limpidity and luster of a precious stone, especially a diamond; as, a diamond of the first water, that is, perfectly pure and transparent. Hence, of the first water, that is, of the first excellence. 6. A wavy, lustrous pattern or decoration such as is imparted to linen, silk, metals, etc. See Water, 3, Damask, and Damaskeen. 7. An addition to the shares representing the capital of a stock company so that the aggregate par value of the shares is increased while their value for investment is diminished, or "diluted." Water is often used adjectively and in the formation of many self-explaining compounds; as, water drainage; water gauge, or water-gauge; waterfowl, water-fowl, or water fowl; water-beaten; water-borne, water-circled, water-girdled, water-rocked, etc. Hard water. See Hard. Inch of water, a unit of measure of quantity of water, being the quantity which will flow through an orifice one inch square, or a circular orifice one inch in diameter, in a vertical surface, under a stated constant head; also called miner's inch, and water inch. The shape of the orifice and the head vary in different localities. In the Western United States, for hydraulic mining, the standard aperture is square and the head from 4 to 9 inches above its center. In Europe, for experimental hydraulics, the orifice is usually round and the head from 1/12 of an inch to 1 inch above its top. Mineral water, waters which are so impregnated with foreign ingredients, such as gaseous, sulphureous, and saline substances, as to give them medicinal properties, or a particular flavor or temperature. Soft water, water not impregnated with lime or mineral salts. To hold water. See Hold, To keep one's head above water, to keep afloat; fig, to avoid failure or sinking in the struggles of life. To make water. To pass urine. <medicine> Hydrothorax. Other phrases, in which water occurs as the first element, will be found in alphabetical order in the Vocabulary. Origin: AS. Waeter; akin to OS. Watar, OFries. Wetir, weter, LG. & D. Water, G. Wasser, OHG. Wazzar, Icel. Vatn, Sw. Vatten, Dan. Vand, Goth. Wat, O. Slav. & Russ. Voda, Gr, Skr. Udan water, ud to wet, and perhaps to L. Unda wave. Cf. Dropsy, Hydra, Otter, Wet, Whisky. Source: Websters Dictionary (01 Mar 1998) |