554 Role of RNA Binding Protein CUGBP2 in Radiation-Mediated Autophagy

Abstract

with increased GER which may allow reflux of small volumes to occur that can be detected by pH-metry but not by MII. Aim: To search for a mechanism that can explain the differences between MII and pH-metry in detecting acid reflux episodes in patients with HH. Methods: 19 patients with GERD symptoms (12 female, 7 male, median age 51yrs (19-65yrs)) were investigated with combined MII-pH. All of the patients were not taking acid suppressive medication for at least 10 days before investigation. Impedance and pH-metry data were analysed separately. The differences in the detection rate of acid reflux between pH-metry and MII were correlated with the presence of HH. Presence of HH was defined endoscopically and classified as present if larger than 1 cm. Additionally we used an In Vitro reflux model. Thereby the impedance probe was flushed with citric acid in plastic tubes (PT) of different size with capillary diameter and diameters of 2,5 mm and 4,5 mm. Citric acid was flushed through the PT repetitively while recording pH and Impedance. Results: HH was present in 6 patients and absent in 13 patients. The mean number of acid reflux episodes in all patients was 24 ± 20 using pH-metry and 18 ± 19 times using MII accounting for a difference of 27% detection rate. In patients with HH in comparison to patients with absent HH the difference of acid reflux detection between pH-metry and MII is significantly higher (26±11; 72% and 5±18; 14% respectively; p<0.01). In Vitro all simulated reflux lead to a fall in pH whereas a corresponding decrease in impedance was only recognizable in the 4.5 mm PT. Simulated reflux using capillaries and the 2.5 mm PT led to a decrease in pH without decrease in impedance. Conclusion: Acid reflux episodes in GERD patients with HH are more frequently detected by pH-metry than by MII. Small volume reflux that does not lead to a decrease in impedance is the likely explanation for this phenomenon.