Randomized, double-blinded, placebo-controlled trial evaluating simethicone pretreatment with bowel preparation during colonoscopy.

BACKGROUND: The presence of small air bubbles and foam are an impediment to a successful colonoscopy. They impair an endoscopist's view and diminish the diagnostic accuracy of the study. This has been particularly noted to be of concern with the switch to lower volume polyethylene glycol (PEG) and bisacodyl combination preparation. AIM: To evaluate the effect of oral simethicone addition to bowel preparation on intraluminal bubbles reduction during colonoscopy. METHODS: Described is a prospective, randomized, multi-center, double-blinded, placebo-controlled study to evaluate the use of premixed simethicone formulation with split-regimen, low-volume PEG-bisacodyl combination bowel preparation for 168 outpatients undergoing screening, surveillance, and diagnostic colonoscopies. Primary outcome includes evaluation of bubbles during colonoscopy graded using the Intraluminal Bubbles Scale. Secondary outcomes include evaluation of the Boston Bowel Preparation Scale (BBPS), total number of polyps, polyp size differentiation, polyp laterality, adenoma detection, mass detection, cecal insertion time, withdrawal time, and patient-reported adverse events. RESULTS: Higher Intraluminal Bubbles grades III and IV (less than 75% of the mucosa cleared of bubbles/foam requiring intervention with simethicone infused wash) were detected in the placebo group [Simethicone n = 4/84 vs Placebo n = 20/84 (P = 0.007)]. BBPS total score was 7.42 [standard deviation (SD) = ± 1.51] in the simethicone group and 7.28 (SD = ± 1.44) in the placebo group (P = 0.542) from a total of 9. Significantly higher number of adenomas were detected in the simethicone group (P = 0.001). CONCLUSION: The addition of simethicone to bowel preparation is well advised for its anti-foaming properties. The results of this study suggest that addition of oral simethicone can improve bowel wall visibility.

Single-molecule fluorescence measurements of ribosomal translocation dynamics.

We employ single-molecule fluorescence resonance energy transfer (smFRET) to study structural dynamics over the first two elongation cycles of protein synthesis, using ribosomes containing either Cy3-labeled ribosomal protein L11 and A- or P-site Cy5-labeled tRNA or Cy3- and Cy5-labeled tRNAs. Pretranslocation (PRE) complexes demonstrate fluctuations between classical and hybrid forms, with concerted motions of tRNAs away from L11 and from each other when classical complex converts to hybrid complex. EF-G⋅GTP binding to both hybrid and classical PRE complexes halts these fluctuations prior to catalyzing translocation to form the posttranslocation (POST) complex. EF-G dependent translocation from the classical PRE complex proceeds via transient formation of a short-lived hybrid intermediate. A-site binding of either EF-G to the PRE complex or of aminoacyl-tRNA⋅EF-Tu ternary complex to the POST complex markedly suppresses ribosome conformational lability.