| component of complement | Any one of the nine distinct protein units (designated C1 through C9 and distributed in the a, b, and g electrophoretic partitions of normal serum) that effect the immunological activities long associated with complement. C1 is a complex of three subunits: C1q, C1r, and C1s. C1q (overbar indicates "active form") activates proenzyme C1r to C1r which activates C1s to C1s (also known as C1 esterase), which converts proenzyme C2 to C2b and produces C4b from C4. C2b combines with C4b to form "classical-complement-pathway C3/C5 convertase" (also known as C3 convertase, C5 convertase, and C42). This enzyme cleaves C3 to C3a and C3b, and C5 to yield C5a and C5b, as does "alternative-complement-pathway C3/C5 convertase" (also known as proenzyme factor B, properdin factor B, C3 proactivator, and heat-labile factor). Complement factor I (also known as C3b or C3b/C4b inactivator) inactivates C3b and C4b by a different proteolytic cleavage. Several autosomal recessive disorders have been identified in which one or more of the complement components have been deficient or completely absent. (05 Mar 2000) |
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| component of force | One of the factors from which a resultant force may be compounded or into which it may be resolved, one of the vectors into which a force may be resolved. (05 Mar 2000) |
| component S, glutamate mutase | <chemical> Component s of the coenzyme b12-dependent glutamate mutase from clostridium cochlearium; mw 15 kD; amino acid sequence given in first source Synonym: glms gene product, muts gene product (clostridium) (26 Jun 1999) |
| components of mastication | The various jaw movements that are made during the act of mastication, as determined by the neuromuscular system, the temporomandibular articulations, the teeth, and the food being chewed; divided, for purposes of analysis or description, into opening, closing, left lateral, right lateral, and anteroposterior component's. (05 Mar 2000) |
| components of occlusion | The various factors involved in occlusion, such as the temporomandibular joint, the associated neuromusculature, the teeth, and the denture-supporting structures. (05 Mar 2000) |
| compos mentis | Of sound mind; usually used in its opposite form, non compos mentis. Origin: L. Possessed of one's mind; compos, having control, + mens(ment-), mind (05 Mar 2000) |
| composite | A colloquial term for resin materials used in restorative dentistry. Origin: L. Compositus, put together, fr. Compono, to put together (05 Mar 2000) |
| composite dental cement | An organic dental cement modified by the inclusion of inorganic materials treated with a coupling agent to bond them to the polymers. (05 Mar 2000) |
| composite graft | A graft composed of several structures, such as skin and cartilage or a full-thickness segment of the ear. (05 Mar 2000) |
| composite joint | A joint composed of three or more skeletal elements, or in which two anatomically separate joints function as a unit. For example, the telonavicular and calcaneocuboid joints act together as the compound transverse tarsal joint. Synonym: articulatio complexa, articulatio composita, composite joint, compound articulation. (05 Mar 2000) |
| composite resin | A synthetic resin usually acrylic based, to which a glass or natural silica filter has been added. Used mainly in dental restorative procedures. Origin: L. Compositus, put together, fr. Compono, to put together (05 Mar 2000) |
| composite resins | Synthetic resins, usually acrylic based, to which a high percentage (usually about 75% to 80%) of an inert filler has been added. Glass beads or rods, borosilicate glass powder, and natural silica are the most commonly used fillers. Filler particles are coated with a coupling agent that binds the particles to the resin matrix. They are used chiefly in dental restorative procedures. (12 Dec 1998) |
| composite transposon | <molecular biology> A segment of DNA which contains the insertion elements at either end but can contain just about anything in the middle (genes, markers, etc.). These types of transposons tend to be very large, and many of them came about when the inner two insertion elements of two smaller transposons stopped working and only the two at the far ends continue to work, so that when the transposon moves, it takes everything in between the two original transposons with it. Some composite transposons are used in genetics experiments, Tn5 and Tn10 are two such composite transposons which have genes that encode resistance to certain antibiotics. (05 Jan 1998) |
| composition | In chemistry, the kinds and numbers of atoms constituting a molecule. Origin: L. Compono, to arrange (05 Mar 2000) |
| compost | <botany> A mix of different types of organic matter, all of it decaying, such as fallen leaves, bananna peels and/or manure, a mulch. It is used as a fertiliser or to rejuvenate soil. The word can be a noun or verb. (05 Jan 1998) |