Silent Gastroesophageal Reflux Disease in Patients with Morbid Obesity Prior to Primary Metabolic Surgery.

PURPOSE: Long-term follow-up after sleeve gastrectomy (SG) revealed a high incidence of gastroesophageal reflux disease (GERD) frequently caused by preoperative silent pathologic reflux. We aimed to evaluate prevalence and phenotypes of GERD in asymptomatic patients with morbid obesity prior to metabolic surgery according to modern objective testing. MATERIAL AND METHODS: Prospective collection of data including consecutive patients with morbid obesity (body mass index (BMI) ≥ 35 kg/m2) prior to metabolic surgery was applied for this study between 2014 and 2019. Patients underwent clinical examinations, endoscopy, pH metry, and high-resolution manometry and were analyzed according to the Lyon consensus. RESULTS: Of 1379 patients undergoing metabolic surgery, 177 (12.8%, females = 105) asymptomatic individuals with a median age of 42.6 (33.8; 51.6) years and a median BMI of 44.6 (41.3; 50.8) kg/m2 completed objective testing and were included during the study period. GERD was diagnosed in 55 (31.1%), whereas criteria of borderline GERD were met in another 78 (44.1%). GERD was mediated by a structural defective lower esophageal sphincter (p = 0.004) and highlighted by acidic (p = 0.004) and non-acidic (p = 0.022) reflux episodes. Esophageal motility disorders were diagnosed in 35.6% (n = 63) of individuals with a novel hypercontractile disorder found in 7.9% (n = 14) of patients. CONCLUSION: GERD affects a majority of asymptomatic patients with morbid obesity prior to primary bariatric surgery. Future longitudinal trials will have to reveal the clinical significance of esophageal motility disorders in patients with morbid obesity.

Active-passive calibration of optical tweezers in viscoelastic media.

In order to use optical tweezers as a force measuring tool inside a viscoelastic medium such as the cytoplasm of a living cell, it is crucial to perform an exact force calibration within the complex medium. This is a nontrivial task, as many of the physical characteristics of the medium and probe, e.g., viscosity, elasticity, shape, and density, are often unknown. Here, we suggest how to calibrate single beam optical tweezers in a complex viscoelastic environment. At the same time, we determine viscoelastic characteristics such as friction retardation spectrum and elastic moduli of the medium. We apply and test a method suggested [M. Fischer and K. Berg-Sørensen, J. Opt. A, Pure Appl. Opt. 9, S239 (2007)], a method which combines passive and active measurements. The method is demonstrated in a simple viscous medium, water, and in a solution of entangled F-actin without cross-linkers.