| double thymidine block | <cell culture, procedure> A lab technique used to synchronise the cell cycles of all the cells in a culture. This is done by adding excessive amounts of thymidine (a deoxynucleoside) to the culture so that DNA replication is blocked. Eventually, all of the cells will reach the same point in the cell cycle and stop. (09 Oct 1997) |
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| double track sign | In paediatric radiology, a less common sign of congenital pyloric stenosis, when barium is caught between mucosal folds in the hypertrophied pylorus. (05 Mar 2000) |
| double vision | <ophthalmology, symptom> The perception of two images of a single object. Synonym: ambiopia, double vision, binocular polyopia. (18 Nov 1997) |
| double-voided specimen | This refers to a urine specimen which is collected after first emptying the bladder and then waiting until another specimen can be collected. These double-voided urine specimens are more accurate for purposes of glucose testing (urinalysis). If you test a urine specimen that has been held in the bladder for an extended period of time, it will not accurately reflect the glucose content in the bloodstream. A freshly, double voided specimen is preferred. (27 Sep 1997) |
| Traube's double tone | A double sound heard on auscultation over the femoral vessels in cases of aortic and tricuspid insufficiency. (05 Mar 2000) |