| prostate-specific antigen | <tumour marker> A simple blood test used to detect prostate cancer in men. The test measures a specific antigen normally secreted by the prostate. If cancer is developing, the prostate secretes greater amounts of prostate-specific antigen. This test is recommended for men with an enlarged prostate and an increased risk of prostate cancer. It is an enzyme that is produced by epithelial cells of both benign and malignant prostate tissue. It is an important marker for the diagnosis of prostate cancer. It is a single chain 31 kilodalton glycoprotein with 240 amino acid residues and 4 carbohydrate side chains that is a kallikrein protease. It is found in normal seminal fluid and produced by the prostatic epithelial cells. Elevated levels in blood serum are associated with prostatic enlargement and prostatic adenocarcinoma, and this allows early detection of cancer in many cases. In about 70% of cases, the rise is due to a cancerous condition. No large scale clinical studies have been completed to assess the impact of testing on survival from prostate cancer, and the medical and economic value of testing remain uncertain. Acronym: PSA Registry number: EC 3.4.21.77 (22 Sep 2002) |
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| pyrimidine-guanine sequence-specific ribonuclease | <enzyme> From yolk granules of adult rana catesbeiana oocytes Registry number: EC 3.1.27.- Synonym: rc-rnase, rana catesbeiana rnase (26 Jun 1999) |
| site-specific mutagenesis | <cell culture, molecular biology> An in vitro technique in which an alteration is made at a specific site in a DNA molecule, which is then reintroduced into a cell. Various techniques are used, for the cell biologist, a very powerful approach to determining which parts of a protein or nucleotide sequence are critical to function. (18 Nov 1997) |
| site specific mutation | An alteration of the structure of a gene at a specific sequence, usually referring to experimentally produced changes in gene sequence. (05 Mar 2000) |
| site-specific recombination | <molecular biology> A type of recombination that occurs between two specific short DNA sequences present in the same or in different molecules. An example is the integration and excision of _ prophage. (18 Nov 1997) |
| soluble specific substance | A soluble type-specific polysaccharide produced during active growth of virulent pneumococci composing a large part of the capsule. Synonym: pneumococcal polysaccharide, soluble specific substance, specific soluble polysaccharide, specific soluble sugar. (05 Mar 2000) |
| species-specific | Applying only to a particular species, said of effects that vary depending on the species in question. (09 Oct 1997) |
| species-specific antigen | Antigenic components in the tissues and fluids of members of a species of animal, by means of which various species may be immunologically distinguished; e.g., serum albumin of horses is immunologically different from that of man, dogs, sheep, and so on. (05 Mar 2000) |
| specific | 1. Pertaining to a species. 2. Produces by a single kind of microorganism. 3. A remedy specially indicated for any particular disease. 4. <immunology> Pertaining to the special affinity of antigen for the corresponding antibody. Origin: L. Specificus (18 Nov 1997) |
| specific absorbance | Absorbance per unit of concentration. See: specific absorption coefficient. (05 Mar 2000) |
| specific absorption coefficient | Absorbance (of light) per unit path length (usually the centimeter) and per unit of mass concentration. Compare: molar absorption coefficient. Synonym: absorbancy index, absorptivity, extinction coefficient, specific extinction. (05 Mar 2000) |
| specific action | The action of a drug or a method of treatment which has a direct and especially curative effect upon a disease, e.g., the action of vitamin B12 in pernicious anaemia. (05 Mar 2000) |
| specific active immunity | See: acquired immunity. (05 Mar 2000) |
| specific activity | 1. <chemistry> The number of activity units (whatever is appropriate) per unit of mass, volume or molarity. 2. <radiobiology> Total activity of a given nuclide per gram of a compound, element or radioactive nuclide. Perhaps most often usage, in the context of radiochemicals, the number of microcuries per micromole. (16 Dec 1997) |
| specific anergy | A reduction of the normal or usual immunologic response resulting from a reaction to a specific allergen. Synonym: specific anergy. (05 Mar 2000) |