| gap junctions | Connections between cells which allow passage of small molecules and electric current. Gap junctions were first described anatomically as regions of close apposition between cells with a narrow (1-2 nm) gap between cell membranes. The variety in the properties of gap junctions is reflected in the number of connexins, the family of proteins which form the junctions. (12 Dec 1998) |
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| gap mutant | <molecular biology> A fruit fly of the genus Drosophila which is missing a number of adjacent segments because the segments failed to develop. (09 Oct 1997) |
| gap phenomenon | A short period in the cycle of the atrioventricular or intraventricular conduction allowing passage of an impulse which at other times would be blocked in transit. Synonym: excitable gap. (05 Mar 2000) |
| GAP protein | <molecular biology> Originally purified as a 125 kD protein from bovine brain (1044 amino acids), stimulates the GTPase activity of ras p21 and thereby switches it to the inactive state. GAP may itself be regulated by phospholipids and by phosphorylation on a tyrosine residue by growth factor receptors (PDGF R, EGF R). The neurofibromatosis type 1 gene NF1) codes for a protein homologous to GAP. GAP has both SH2 and SH3 domains. Another example is sar 1 (from yeast). (18 Nov 1997) |
| chromosomal gap | A localised area of thinning in a chromatid which may simulate a complete break. (05 Mar 2000) |
| silent gap | The period during which Korotkoff sounds indicating true systolic pressure fade away and reappear at a lower pressure point; responsible for errors made in recording falsely low systolic blood pressure, especially in hypertensive patients, of up to 25 mm Hg, and avoided by pumping the cuff 30 mm Hg beyond palpable systolic pressure. Synonym: silent gap. (05 Mar 2000) |
| DNA gap | A localised loss of one of the two strands in the double helix of DNA. (05 Mar 2000) |
| interocclusal gap | The space between the occluding surfaces of the maxillary and mandibular teeth when the mandible is in physiologic resting position. Synonym: interocclusal clearance, interocclusal distance, interocclusal gap, interocclusal rest space. (05 Mar 2000) |
| excitable gap | A short period in the cycle of the atrioventricular or intraventricular conduction allowing passage of an impulse which at other times would be blocked in transit. Synonym: excitable gap. (05 Mar 2000) |
| afferent loop syndrome | <syndrome> A complication of gastrojejunostomy, caused by acute or chronic obstruction of the afferent loop due to hernia, intussusception, kinking, volvulus, etc. It is characterised by pain and vomiting of bile-stained fluid and includes acute afferent loop obstruction and bilious vomiting. (12 Dec 1998) |
| arch-loop-whorl system | See: Galton's system of classification of fingerprints. (05 Mar 2000) |
| Biebl loop | A continuous loop of small intestine brought through the abdominal wall to a subcutaneous location, for observation of motility. (05 Mar 2000) |
| blind loop syndrome | <syndrome> Malabsorption, especially of vitamin b12 or folic acid, due to metabolic competition by bacteria proliferating in a segment of small intestine excluded from normal peristaltic movement; it may occur as a postoperative complication of side-to-side anastomosis of intestine, as a result of intestinal diverticula, fistula, etc. (12 Dec 1998) |
| bulboventricular loop | The portion of the early-somite embryonic cardiac tube that evolves into the ventricle and bulbus cordis. Synonym: ventricular loop. (05 Mar 2000) |
| gamma loop | The reflex arc consisting of small anterior horn cells and neuroma, their small fibres projecting to the intrafusal bundle producing its contraction, which initiates the afferent impulses that pass through the posterior root to the anterior horn cells, inducing a stretch reflex. Synonym: gamma motor neurons, gamma motor system, Granit's loop. (05 Mar 2000) |