The Effects of One Anastomosis Gastric Bypass Surgery on the Gastrointestinal Tract

One anastomosis gastric bypass (OAGB) is an emerging bariatric procedure, yet data on its effect on the gastrointestinal tract are lacking. This study sought to evaluate the incidence of small-intestinal bacterial overgrowth (SIBO) following OAGB; explore its effect on nutritional, gastrointestinal, and weight outcomes; and assess post-OABG occurrence of pancreatic exocrine insufficiency (PEI) and altered gut microbiota composition. A prospective pilot cohort study of patients who underwent primary-OAGB surgery is here reported. The pre-surgical and 6-months-post-surgery measurements included anthropometrics, glucose breath-tests, biochemical tests, gastrointestinal symptoms, quality-of-life, dietary intake, and fecal sample collection. Thirty-two patients (50% females, 44.5 ± 12.3 years) participated in this study, and 29 attended the 6-month follow-up visit. The mean excess weight loss at 6 months post-OAGB was 67.8 ± 21.2%. The glucose breath-test was negative in all pre-surgery and positive in 37.0% at 6 months (p = 0.004). Positive glucose breath-test was associated with lower reported dietary intake and folate levels and higher vitamin A deficiency rates (p ≤ 0.036). Fecal elastase-1 test (FE1) was negative for all pre-surgery and positive in 26.1% at 6 months (p = 0.500). Both alpha and beta diversity decreased at 6 months post-surgery compared to pre-surgery (p ≤ 0.026). Relatively high incidences of SIBO and PEI were observed at 6 months post-OAGB, which may explain some gastrointestinal symptoms and nutritional deficiencies.

Development of Minimally Invasive 13C-Glucose Breath Test to Examine Different Dietary Therapies in Patients with Glycogen Storage Disorders

Objectives The objectives of the current study were: 1) to establish the use of ,13C-Glucose Breath Test (,13C-GBT) and its oxidation to ,13CO2 as a minimally invasive technique to examine in vivo glucose oxidation in healthy adults, and 2) to measure the utilization of uncooked cornstarch (UCCS) and Glycosade® in patients with glycogen storage disease type Ia (GSD-Ia) and healthy controls using ,13C-GBT, based on the natural enrichment of ,13C in UCCS and Glycosade®. Methods Experiment 1- Ten healthy adults (22 – 33y) underwent ,13C-GBT protocols twice as a proof-of-principle, once without oral isotope dose (only D-glucose 75 g/d) and once with isotope (D-glucose 75 g/d + U-,13C-glucose 75 mg/d). Breath samples were collected at baseline and every 20 min for 240 min to measure ,13CO2. Experiment 2- Two patients (12 and 28y) with GSD-Ia and five healthy controls (10 – 32y) underwent ,13C-GBT protocols twice. Subjects received UCCS or Glycosade® orally (based on their current prescribed dose 42 – 100 g) after a 4 hour fast according to GSD-Ia fasting tolerance. Breath samples were collected at baseline and every 30 min for 240 min. ,13CO2 oxidation of glucose from UCCS and Glycosade® were measured using an isotope ratio mass spectrometer and compared using a paired t-test. Blood glucose was measured using a glucometer hourly to test hypoglycemia (≤3.4 mmol/L). Results Results 1- The mean rate of ,13CO2 in all healthy adults from D-glucose without U-,13C-glucose 0.435 ± 0.162 was significantly lower than the mean rate of ,13CO2 in the same group with U-,13C-glucose 3.518 ± 0.988. The peak occurred at 200 minutes in all healthy adults without and with U-,13C-glucose. Results 2- Glucose oxidation from Glycosade® was lower than glucose oxidation from UCCS in the 12y GSD-Ia. Glucose oxidation from UCCS and Glycosade® remained the same in the 28y GSD-Ia. However, oxidation of glucose by the 28y GSD-Ia for both starches displayed a higher rate, compared to age matched controls. Conclusions Our results show that the minimally invasive,13C-GBT test over 4 hours can be useful to examine glucose metabolism from various exogenous carbohydrate sources in GSD. Future studies are needed to use ,13C-GBT in response to different doses to determine optimal glucose management in GSD patients. Funding Sources Saudi Arabian Cultural Bureau, Ottawa and BC Children's Hospital Research Institute.