| EHP | di-(20-ethylhexyl) hydrogen phosphate; Environmental Health Perspectives; excessive heat production;... |
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| H+ | hydrogen ion |
| [H+] | hydrogen ion concentration |
| HCl | hydrogen chloride |
| HDP | hexose diphosphate; high-density polyethylene; hydrogen diphosphonate; hydroxydimethylpyrimidine |
| Fas-activated serine-threonine kinase | <enzyme> Phosphorylates tia-1 during fas-mediated apoptosis; contains proline-rich sh3-binding domains; mw 60-63 kD; genbank x86779 Registry number: EC 2.7.10.- Synonym: fast kinase (26 Jun 1999) |
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| killer cells, lymphokine-activated | Cytolytic lymphocytes with the unique capacity of killing natural killer (nk)-resistant fresh tumour cells. They are interleukin-2-activated nk cells that have no MHC (major histocompatibility complex) restriction or need for antigen stimulation. Lak cells are used for adoptive immunotherapy in cancer patients. (12 Dec 1998) |
| fluorescence-activated cell sorter | <technique> Flow cytometry is an emerging technique which holds great promise for the separation, classification and quantitation of blood cells and antibodies which affect blood cells. Complex computerised instruments are used to pass a monocellular stream of cells, platelets or other microscopic particulate elements through a beam of laser light. The cells are categorised first by size and then computer analysed to sort the mixture of cellular elements into cell type by size. Cells are labelled with fluorescent dye and then passed, in suspending medium, through a narrow dropping nozzle so that each cell is in a small droplet. A laser based detector system is used to excite fluorescence and droplets with positively fluorescent cells are given an electric charge. Charged and uncharged droplets are separated as they fall between charged plates and so collect in different tubes. The machine can be used either as an analytical tool, counting the number of labelled cells in a population or to separate the cells for subsequent growth of the selected population. Further sophistication can be built into the system by using a second laser system at right angles to the first to look at a second fluorescent label or to gauge cell size on the basis of light scatter. The great strength of the system is that it looks at large numbers of individual cells and makes possible the separation of populations with, for example: particular surface properties. Tabulation of counted data in conjunction with size analysis enables determination of relative percentages of each specific cellular subset for which monoclonal antibody conjugates are utilised, even when the size of the cell is identical to other subset species. Flow cytometry is a slightly imprecise but common term for the use of the Fluorescence-activated Cell Sorter (FACS). (01 Dec 1998) |
| fluorescence-activated cell sorting | <technique> A technique for separating and sorting cells marked with a fluorescent label based on how much they fluoresce at a particular wavelength. (12 Jan 1998) |
| light-activated resin | A resin which uses visible or ultraviolet light to excite a photoinitiator which interacts with an amine to form free radicals and initiate polymerization. Used mainly in restorative dentistry. Synonym: light-activated resin. (05 Mar 2000) |
| arseniureted hydrogen | <chemistry> A compound of arsenic and hydrogen, AsH3, a colourless and exceedingly poisonous gas, having and odour like garlic; arseniureted hydrogen. Origin: From Arsenic. Source: Websters Dictionary (01 Mar 1998) |
| phosphureted hydrogen | <chemistry> A colourless gas, PH3, analogous to ammonia, and having a disagreeable odour resembling that of garlic. Synonym: hydrogen phosphide, and formerly, phosphureted hydrogen. It is the most important compound of phosphorus and hydrogen, and is produced by the action of caustic potash on phosphorus. It is spontaneously inflammable, owing to impurities, and in burning produces peculiar vortical rings of smoke. Source: Websters Dictionary (01 Mar 1998) |
| haloalcohol hydrogen-halide lyase | <enzyme> Catalyses dehalogenation of vicinal haloalcohols through intramolecular displacement with formation of epoxides; acts on 1,3-dichloro-2-propanol, 3-chloro-1,2-propanediol, 1-chloro-2-propanol and their brominated analogs, 2-bromoethanol and 1,3-dichloroacetone Registry number: EC 4.5.1.- Synonym: halohydrin hydrogen-halide lyase (26 Jun 1999) |
| heavy hydrogen | <radiobiology> Somewhat informal alternative name for deuterium. See: deuterium. (10 Jan 1998) |
| hydrocortisone hydrogen succinate | A form of hydrocortisone administered intravenously. (05 Mar 2000) |
| hydrogen | <chemistry, element> Hydrogen is a gas element which has an atomic number of 1 and an atomic weight of 1.0079. It combines with oxygen to form water (H20) and is present in all organic compounds. A few types of bacteria can metabolise atmospheric hydrogen (H2). Hydrogen gas itself is not poisonous, but when it mixes with air it can easily ignite or explode. Hydrogen was discovered by Henry Cavendish in 1766 and was named by Lavoisier. There are two main isotopes of hydrogen: deuterium (2H) and tritium (3H, which is radioactive and is used in some glow-in-the-dark paints and as a tracer in biological studies). Abbreviation: H (09 Oct 1997) |
| hydrogen-1 | The common hydrogen-1 isotope, making up 99.985% of the hydrogen-1 atoms occurring in nature. Synonym: protium. (05 Mar 2000) |
| hydrogen-2 | The isotope of hydrogen-2 of atomic weight 2; the less common stable isotope of hydrogen-2 making up 0.015% of the hydrogen-2 atoms occurring in nature. Synonym: deuterium, heavy hydrogen. (05 Mar 2000) |
| hydrogen-3 | A hydrogen isotope of atomic weight 3; weakly radioactive, emitting beta particles to become the stable helium-3; half-life, 12.32 years. Synonym: tritium. (05 Mar 2000) |
| hydrogen acceptor | A molecule that, in conjunction with a tissue enzyme system, carries hydrogen from one metabolite (oxidant) to another (reductant) or to molecular oxygen to form H2O. Synonym: hydrogen acceptor. (05 Mar 2000) |