| CIDEP | chemically induced dynamic electron polarization |
|---|---|
| CIDNP | chemically induced dynamic nuclear polarization |
| DEPT | distortionless enhancement by polarization transfer |
| INEPT | insensitive nuclei enhanced by polarization transfer |
| TP | temperature and pressure; temperature probe; temporal peak; temporoparietal; tension pneumothorax; t... |
| ratio imaging fluorescence microscopy | <procedure> A method of measurement of intracellular pH or intracellular calcium levels, using a fluorescent probe molecule (see fura-2), in which the two different excitation wavelengths are used and the emitted light levels compared. If emission at one wavelength is sensitive to the intracellular ion level and emission at the other wavelength is not, then standardisation for intracellular probe concentration, efficiency of light collection, inactivation of probe and thickness of cytoplasm can all be performed automatically. (17 Dec 1997) |
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| microscopy, fluorescence | Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilises antibodies that are labelled with fluorescent dye. (12 Dec 1998) |
| spectrometry, fluorescence | Measurement of the intensity and quality of fluorescence. (12 Dec 1998) |
| Eranko's fluorescence stain | <technique> Exposure of frozen sections to formaldehyde which produces a strong yellow-green fluorescence from cells containing norepinephrine. (05 Mar 2000) |
| fluorescence | <chemistry, physics> The emission of one or more photons by a molecule or atom activated by the absorption of a quantum of electro magnetic radiation. Typically the emission, that is of longer wavelength than the excitatory radiation, occurs within 10exp 8 seconds: phosphorescence is a phenomenon with a longer or much longer delay in re radiation. Note that rays, X-rays, UV, visible light and IR radiations may all stimulate fluorescence. (25 Jun 1999) |
| 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) |
| fluorescence energy transfer | <technique> Transfer of energy from one fluorochrome to another. The emission wavelength of the fluorochrome excited by the incident light must approximately match the excitation wavelength of the second fluorochrome. If light at the second emission wavelength is detected, it implies that the two fluorochromes were physically within a few nanometres. Used as a technique to probe protein or cell interactions. (25 Jun 1999) |
| fluorescence in situ hybridization | <molecular biology, technique> A type of in situ hybridization in which target sequences are stained with fluorescent dye so their location and size can be determined using fluorescence microscopy. This staining is sufficiently distinct that the hybridization signal can be seen both in metaphase spreads and in interphase nuclei. Acronym: FISH (25 Jun 1999) |
| fluorescence microscope | <instrument, microscopy> A microscope illuminated by ultraviolet or blue light so that the object may re-radiate light of longer wavelengths. To protect the eyes, a W-absorbing filter should be provided if not built into the fluorescence microscope. (05 Aug 1998) |
| fluorescence microscopy | <procedure> Any type of microscopy in which intrinsic or applied reagents are visualised. Intrinsic fluorescence is often referred to as auto fluorescence. The applied reagents typically include fluorescently labelled proteins that are reactive with sites in the specimen. In particular, fluorescently labelled antibodies are widely used to detect particular antigens in biological specimens. (18 Nov 1997) |
| fluorescence plus Giemsa stain | <technique> A stain used to demonstrate sister chromatid exchange; cells are grown in 5-bromodeoxyuridine, followed by chromosome preparation, staining in Hoechst 33258, exposure to light, and staining in Giemsa; chromosomes exhibit a "harlequin" appearance. (05 Mar 2000) |
| fluorescence recovery after photobleaching | Many fluorochromes are bleached by exposure to exciting light. If, for example: the cell surface is labelled with a fluorescent probe and an area bleached by laser illumination, then the bleached patch that starts off as a dark area will gradually recover fluorescence. The recovery is due to the re population of the area by unbleached molecules and diffusion of bleached molecules to other areas. The rate and extent of recovery are a measure of the fluidity of the membrane and the proportion of labelled molecules that are free to exchange with adjacent areas. The technique is usually applied to cell surface fluidity or viscosity measurements, but is also applicable to other structures. (18 Nov 1997) |
| fluorescence spectrum | Fluorescence evoked over a range of wavelengths when the excitation wavelength is at a maximum. (05 Mar 2000) |