| AAK | allo-activated killer |
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| AC | abdominal circumference; abdominal compression; absorption coefficient; abuse case; acetate; acetylc... |
| ACAC | acetyl-coenzyme A cocarboxylase; activated charcoal artificial cell |
| ACT | achievement through counseling and treatment; actin; actinomycin; activated clotting time; advanced ... |
| A-LAK | adherent lymphokine-activated killer [cell] |
| 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) |
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| 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) |
| aberrant complex | An anomalous electrocardiographic complex, more specifically an abnormal ventricular complex caused by abnormal intraventricular conduction of a supraventricular impulse. (05 Mar 2000) |
| AIDS dementia complex | <immunology> A frequent cerebral condition in people with AIDS that results in the loss of cognitive capacity, affecting the ability to function in a social or occupational setting. Its cause has not been determined exactly, but may result from HIV infection of cells in the brain or an inflammatory reaction to such infection. (09 Oct 1997) |
| aids-related complex | A prodromal phase of infection with the human immunodeficiency virus (HIV). Laboratory criteria separating aids-related complex (arc) from aids include elevated or hyperactive B-cell humoral immune responses, compared to depressed or normal antibody reactivity in aids; follicular or mixed hyperplasia in arc lymph nodes, leading to lymphocyte degeneration and depletion more typical of aids; evolving succession of histopathological lesions such as localization of kaposi's sarcoma, signaling the transition to the full-blown aids. (12 Dec 1998) |
| alpha-keto acid dehydrogenase complex | See: alpha-keto acid dehydrogenase. Anaerobic dehydrogenase, an enzyme (usually a pyridinoenzyme) catalyzing the transfer of hydrogen from some metabolite to some acceptor molecule (e.g., NAD+, cytochrome) other than oxygen; e.g., lactate dehydrogenase's, isocitrate dehydrogenase's, and others in EC class 1, excluding those listed under aerobic dehydrogenase. (05 Mar 2000) |
| alpha-ketoglutarate dehydrogenase complex | alpha-ketoglutarate dehydrogenase |
| amygdaloid complex | Almond-shaped group of basal nuclei anterior to the inferior horn of the lateral ventricle of the brain, within the temporal lobe. The amygdala is part of the limbic system. (12 Dec 1998) |
| anomalous complex | A complex in the electrocardiogram differing significantly from the physiologic type in the same lead. (05 Mar 2000) |
| antennal complex | <cell biology> Light harvesting complexes (LHC) of protein and pigment in or on photosynthetic membranes of bacteria are organised into arrays, called antennae. They transfer photon energy to reaction centres. (18 Nov 1997) |
| antennapedia complex | A set of mutations that cause developmental defects in the limbs and appendages of the fruit fly Drosophila melanogaster, such as the development of legs (-pedia) in the places where antennae are supposed to be. (09 Oct 1997) |
| antigen-antibody complex | The complex formed by the binding of antigen and antibody molecules. The deposition of large antigen-antibody complexes leading to tissue damage causes immune complex diseases. If the antigen is polyvalent the complex may be insoluble. Immune complexes activate complement through the classical pathway. See: glomerulonephritis, Arthus reaction, type III hypersensitivity. (12 Dec 1998) |
| antigenic complex | A composite of different antigenic structures, such as a cell or a bacterium, or, by extension, a molecule containing two or more determinant groups of different antigenic specificities. (05 Mar 2000) |