| 1-carbamoyl-L-amino acid amidohydrolase | <enzyme> From bacillus stearothermophilus; amino acid sequence given in first source Registry number: EC 3.5.1.- Synonym: carbamoyl l-aa amidohydrolase, n-carbamyl-l-amino acid amidohydrolase (26 Jun 1999) |
|---|---|
| activation | <radiobiology> Activation occurs when a particle interacts with an atomic nucleus, shifting the nucleus into an unstable state, and causing it to become radioactive. In fusion research, where deuterium-tritium is a common fuel mixture, the neutron released when (D + T) combine to form (4He + n) can activate the reactor structure. In this case the 4He is inert, the neutron sticks to another nucleus, and the neutron + nucleus reaction creates an actvation product. Sometimes called radioactivation. See: activation product, activation analysis. (09 Oct 1997) |
| activation analysis | <radiobiology> Method for identifying and measuring chemical elements in a sample of material. Sample is first made radioactive by bombardment with neutrons, charged particles, or gamma rays. Newly formed radioactive atoms in the sample then give off characteristic radiations (such as gamma rays) that tell what kinds of atoms are present, and how many. (09 Oct 1997) |
| activation energy | <chemistry> The amount of energy (expressed in joules) that is needed to convert all the molecules in one mole of a reacting substance from a ground state to the transition state. (06 May 1997) |
| activation product | <radiobiology> The unstable nucleus formed when activation occurs. (See activation above.) (09 Oct 1997) |
| macrophage activation | The process of altering the morphology and functional activity of macrophages so that they become avidly phagocytic. It is initiated by lymphokines, such as the macrophage activation factor (maf) and the macrophage migration-inhibitory factor (mmif), immune complexes, c3b, and various peptides, polysaccharides, and immunologic adjuvants. (12 Dec 1998) |
| gene activation | The process of activation of a gene so that it is expressed at a particular time. This process is crucial in growth and development. (05 Mar 2000) |
| Gibbs energy of activation | The Gibbs energy that must be added to that already possessed by a molecule or molecules in order to initiate a reaction. (05 Mar 2000) |
| virus activation | The mechanism by which latent viruses, such as genetically transmitted tumour viruses or prophages of lysogenic bacteria, are induced to replicate and are released as infectious viruses. It may be effected by various endogenous and exogenous stimuli, including B-cell lipopolysaccharides, glucocorticoid hormones, halogenated pyrimidines, ionizing radiation, ultraviolet light, and superinfecting viruses. (12 Dec 1998) |
| cis activation | <molecular biology> Activation of a gene by an activator located on the same chromosome i.e. Not by a diffusible product. (18 Nov 1997) |
| complement activation | The sequential activation of serum components c1 through c9, initiated by an erythrocyte-antibody complex or by microbial polysaccharides and properdin, and producing an inflammatory response. (12 Dec 1998) |
| platelet activation | A series of progressive, overlapping events triggered by exposure of the platelets to subendothelial tissue. These events include shape change, adhesiveness, aggregation, and release reactions. When carried through to completion, these events lead to the formation of a stable haemostatic plug. (12 Dec 1998) |
| neutron activation analysis | Activation analysis in which the specimen is bombarded with neutrons. Identification is made by measuring the resulting radioisotopes. (12 Dec 1998) |
| neutrophil activation | The process in which the neutrophil is stimulated by diverse substances, resulting in degranulation and/or generation of reactive oxygen products, and culminating in the destruction of invading pathogens. The stimulatory substances, including opsonised particles, immune complexes, and chemotactic factors, bind to specific cell-surface receptors on the neutrophil. (12 Dec 1998) |
| EEG activation | The low voltage, fast pattern of attentive wakefulness. (05 Mar 2000) |