Diagnostic flexible versus rigid bronchoscopy for the assessment of tracheomalacia in children.

OBJECTIVE: This project compares the degree of tracheal collapse determined by rigid and flexible bronchoscopy in paediatric patients with tracheomalacia. METHODS: A total of nine patients with tracheomalacia underwent both rigid and flexible video bronchoscopy. All patients were breathing spontaneously. Cross-sectional images of the airway were processed using the ImageJ program and analysed via colour histogram mode technique in order to delineate the luminal area. Paired t-tests (conducted using Stata software version 13.0) quantified differences between rigid and flexible bronchoscopes regarding the ratios of luminal pixels at maximum airway collapse to expansion. Correlation between both techniques in terms of airway collapse to expansion ratios was determined by calculating the Pearson correlation coefficient (R). RESULTS: The difference in ratios of maximum collapse to expansion between rigid and flexible bronchoscopy was not statistically significant (p = 0.4656) and was positively correlated (R = 0.523). CONCLUSION: The ratios suggest that rigid and flexible bronchoscopy are equally efficacious in assessing tracheomalacia severity, and may be used interchangeably in a clinical setting.

A novel embryonic poly(A) binding protein, ePAB, regulates mRNA deadenylation in Xenopus egg extracts.

An in vitro system that recapitulates the in vivo effect of AU-rich elements (AREs) on mRNA deadenylation has been developed from Xenopus activated egg extracts. ARE-mediated deadenylation is uncoupled from mRNA body decay, and the rate of deadenylation increases with the number of tandem AUUUAs. A novel ARE-binding protein called ePAB (for embryonic poly(A)-binding protein) has been purified from this extract by ARE affinity selection. ePAB exhibits 72% identity to mammalian and Xenopus PABP1 and is the predominant poly(A)-binding protein expressed in the stage VI oocyte and during Xenopus early development. Immunodepletion of ePAB increases the rate of both ARE-mediated and default deadenylation in vitro. In contrast, addition of even a small excess of ePAB inhibits deadenylation, demonstrating that the ePAB concentration is critical for determining the rate of ARE-mediated deadenylation. These data argue that ePAB is the poly(A)-binding protein responsible for stabilization of poly(A) tails and is thus a potential regulator of mRNA deadenylation and translation during early development.