| slow-reacting substance | Slow-reacting substance of anaphylaxis (SRS-A), a leukotriene of low molecular weight which is released in anaphylactic shock and produces slower and more prolonged contraction of muscle than does histamine; it is active in the presence of antihistamines (but not epinephrine) and seems not to occur preformed in mast cells, but as a result of an antigen-antibody reaction on the granules. Compare: peptidyl leukotrienes. Synonym: slow-reacting factor of anaphylaxis. (05 Mar 2000) |
|---|---|
| slow reacting substance of anaphylaxis | <immunology> Potent bronchoconstrictor and inflammatory agent released by mast cells, an important mediator of allergic bronchial asthma. A mixture of three leukotrienes (LTC4 mainly, LTD4 and LTE4) (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) |
| specific capsular 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) |
| spongy substance | Bone in which the spicules or trabeculae form a three-dimensional latticework (cancellus) with the interstices filled with embryonal connective tissue or bone marrow. Synonym: substantia trabecularis, cancellous bone, spongy bone, spongy substance, trabecular bone. (05 Mar 2000) |
| standard substance | A pure, authentic substance used for identification purposes. (05 Mar 2000) |
| Stilling's gelatinous substance | The central gray matter of the spinal cord surrounding the central canal. Synonym: substantia intermedia centralis et lateralis, anterior gray column, Stilling's gelatinous substance, substantia gelatinosa centralis. (05 Mar 2000) |
| neurosecretory substance | The secretion of nerve cell bodies located in the hypothalamus; the substance is transported by way of hypothalamo-hypophysial tract fibres into the neurohypophysis where the terminals of the nerve fibres contain the secretion. As seen in the fibres and terminals with a light microscope, the substance appears as Herring bodies or hyaline bodies of the pituitary (see under body). See: hyaline bodies of pituitary. (05 Mar 2000) |
| Nissl substance | The material consisting of granular endoplasmic reticulum and ribosomes that occurs in nerve cell bodies and dendrites. Synonym: basophil substance, basophilic substance, chromophil substance, Nissl bodies, Nissl granules, substantia basophilia, tigroid bodies, tigroid substance. (05 Mar 2000) |
| substance | The material constituting an organ or body, also called substantia. Origin: L. Substantia (18 Nov 1997) |
| substance dependence | A pattern of behavioural, physiologic, and cognitive symptoms that develop due to substance use or abuse; usually indicated by tolerance to the effects of the substance and withdrawal symptoms that develop when use of the substance is terminated. (05 Mar 2000) |
| substance-induced organic mental disorders | Mental disorders caused by use of drugs, e.g., cocaine. (05 Mar 2000) |
| substance of lens of eye | That which constitutes the lens of the eye, composed of a nucleus and a cortex and covered by an epithelium. Synonym: substantia lentis. (05 Mar 2000) |
| substance P | A vasoactive intestinal peptide (1348 D) found in the brain, spinal ganglia and intestine of vertebrates. Induces vasodilatation, salivation and increases capillary permeability. Sequence: RPKPQFFGLM. (18 Nov 1997) |
| substance-related disorders | These non-psychotic disorders include those related to the taking of a drug of abuse (including alcohol), to the side effects of a medication, and to toxin exposure. (12 Dec 1998) |