| constitutive mutant | An organism with a mutation in a regulatory gene, so that the genes which its flawed regulatory product are supposed to suppress become constitutive genes, or impossible to turn off. Thus, the products of the uncontrolled genes are produced to excess. (09 Oct 1997) |
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| constriction | The act of constricting. (12 Dec 1998) |
| constriction ring | The equatorial ring of microfilaments that diminishes in diameter probably both by contraction and disassembly as cytokinesis proceeds. (18 Nov 1997) |
| constriction, pathologic | The condition of an anatomical structure's being constricted beyond normal dimensions. (12 Dec 1998) |
| constrictions of ureter | Normal physiological narrowings of the ureter observable in a pyelogram; the uppermost occurs at the origin of the ureter from the renal pelvis; a second occurs as the ureter crosses the iliac vessels and pelvic brim; the inferiormost occurs as the ureter penetrates the wall of the urinary bladder. (05 Mar 2000) |
| constrictive bronchiolitis | Obliteration of bronchioles by scarring following bronchiolitis obliterans. Compare: proliferative bronchiolitis. (05 Mar 2000) |
| constrictive endocarditis | Thickening of the endocardium due to inflammation of any origin that restricts the diastolic relaxation of one or both ventricles producing diastolic ventricular failure. (05 Mar 2000) |
| constrictive pericarditis | <pathology> Chronic inflammation of the pericardial sac (pericarditis) can lead to scarring and fibrosis of the pericardium. Due to this process, the pericardium can interfere with the hearts ability to pump blood into the systemic circulation. Causes include tuberculosis infection, radiation therapy, cardiac surgery, viral infection or autoimmune disease. Symptoms are those of right-sided congestive heart failure. Surgery to cut the pericardium may be necessary. Complications include cardiac tamponade and pulmonary oedema. See: pericardial sac. (27 Sep 1997) |
| constrictor | 1. Anything that binds or squeezes a part. 2. A muscle, the action of which is to narrow a canal; a sphincter. Origin: L. Fr. Constringo, to draw together (05 Mar 2000) |
| construct | (noun) The combination of a bone graft, metal instrumentation, prosthetic devices and/or bone cement applied to a specific level of the spinal column in the setting of segmental spinal instability. (05 Mar 2000) |
| construct validity | The extent to which a test or procedure appears to measure a higher order, inferred theoretical construct, or trait in contrast to measuring a more limited, specific dimension; e.g., a sychrony in the scores on the Stanford-Binet Test, on a test of information processing, and the rate of glucose metabolism in the brain all are indices of intelligence. (05 Mar 2000) |
| constructional agraphia | An aghraphia in which letters and words can be written correctly, but not arranged appropriately on the writing surface. (05 Mar 2000) |
| constructional apraxia | Apraxia manifested as an impairment in activity such as building, assembling, and drawings; caused by parietal lobe lesions. Synonym: apractagnosia. (05 Mar 2000) |