Balloon enteroscopy-assisted endoscopic retrograde cholangiography and rendezvous procedures in patients with altered gastrointestinal anatomy.

BACKGROUND: Standard endoscopic retrograde cholangiography (ERC) frequently fails to treat biliary obstruction in patients with altered gastrointestinal anatomy. Balloon enteroscopy-assisted ERC (BE-ERC) and combined percutaneous transhepatic endoscopic rendezvous procedures (PTE-RVs) may offer effective rescue approaches. OBJECTIVE: This study aimed to evaluate the efficacy and safety of BE-ERC and PTE-RV for the treatment of biliary obstruction in patients with altered gastrointestinal anatomy. METHODS: In this observational study, all patients with altered gastrointestinal anatomy underwent BE-ERC between 2003 and 2016 at a tertiary referral center. In case of procedural failure, a combined PTE-RV was performed in selected cases. Endpoints included the success and safety of the procedures. RESULTS: A total of 180 BE-ERC performed in 106 patients with altered gastrointestinal anatomy were included. Of the procedures, 76.7% were performed due to benign and 23.3% due to malignant biliary obstruction. BE-ERC was successful in 53% (96/180) of cases. In case of failure, in 23/32 cases a combined PTE-RV was successfully performed, improving the overall success rate of BE-ERC, including PTE-RV, to 66% (119/180). Benign biliary obstruction and repeated procedures were positive predictors of successful BE-ERC (odds ratio 6.8 (95% CI 2.7-17.0), p < .001 and odds ratio 4.1 (2.1-8.2), p < .001). Complications were significantly more frequent in combined PTE-RVs than in BE-ERC procedures alone (34.4% vs. 7.4%; p < .001). CONCLUSIONS: BE-ERC is effective and safe for the endoscopic management of patients with altered gastrointestinal anatomy and percutaneous transhepatic rendezvous procedures can substantially increase success rates in selected cases.

Microbial Degradation Rates of Natural Bitumen.

Microorganisms are present in nearly every oil or bitumen sample originating from temperate reservoirs. Nevertheless, it is very difficult to obtain reliable estimates about microbial processes taking place in deep reservoirs, since metabolic rates are rather low and differ strongly during artificially cultivation. Here, we demonstrate the importance and impact of microorganisms entrapped in microscale water droplets for the overall biodegradation process in bitumen. To this end, we measured degradation rates of heavily biodegraded bitumen from the Pitch Lake (Trinidad and Tobago) using the novel technique of reverse stable isotope labeling, allowing precise measurements of comparatively low mineralization rates in the ng range in microcosms under close to natural conditions. Freshly taken bitumen samples were overlain with artificial brackish water and incubated for 945 days. Additionally, three-dimensional distribution of water droplets in bitumen was studied with computed tomography, revealing a water bitumen interface of 1134 cm2 per liter bitumen, resulting in an average mineralization rate of 9.4-38.6 mmol CO2 per liter bitumen and year. Furthermore, a stable and biofilm-forming microbial community established on the bitumen itself, mainly composed of fermenting and sulfate-reducing bacteria. Our results suggest that small water inclusions inside the bitumen substantially increase the bitumen-water interface and might have a major impact on the overall oil degradation process.

Backdoors for Linear Temporal Logic.

In the present paper, we introduce the backdoor set approach into the field of temporal logic for the global fragment of linear temporal logic. We study the parameterized complexity of the satisfiability problem parameterized by the size of the backdoor. We distinguish between backdoor detection and evaluation of backdoors into the fragments of Horn and Krom formulas. Here we classify the operator fragments of globally-operators for past/future/always, and the combination of them. Detection is shown to be fixed-parameter tractable whereas the complexity of evaluation behaves differently. We show that for Krom formulas the problem is paraNP-complete. For Horn formulas, the complexity is shown to be either fixed parameter tractable or paraNP-complete depending on the considered operator fragment.

Circulating Microparticles Decrease After Cardiac Stress in Patients With Significant Coronary Artery Stenosis.

BACKGROUND: Cardiac stress leads to a dynamic increase of circulating microparticles (MPs) in healthy individuals that is diminished in individuals with vascular disease. The impact of coronary ischemia on circulating MP level is unknown. This study investigates the kinetics of circulating MPs during cardiac stress in patients with coronary artery stenosis. HYPOTHESIS: Patients with significant coronary stenosis show altered circulating MP levels after cardiac stress. METHODS: Eighty patients with stable coronary artery disease underwent dobutamine stress echocardiography (DSE) on the day before coronary angiography. Before, immediately after, at 4 hours, and at 24 hours after DSE, blood was drawn to determine CD144+ endothelial microparticles (EMPs), CD14+ CD16+ monocyte-derived microparticles (MMPs), and CD31+ CD42b+ platelet microparticles. A significant stenosis was defined as stenosis diameter ≥70% in a major native epicardial coronary artery with a diameter of ≥2.5 mm. RESULTS: Significant coronary artery stenoses were found in 41 patients. In these patients, CD144+ -EMP and CD14+ CD16+ -MMP concentrations decreased immediately after DSE. Stimulation of target endothelial cells with sera from patients with significant coronary artery stenoses significantly augmented endothelial capacity to take up EMPs, but not MMPs, in vitro. Serum-induced enhancement of endothelial phosphatidylserine receptor expression was found as a potential mechanism of increased endothelial EMP uptake and subsequently reduced circulating EMP levels after cardiac stress. CONCLUSIONS: Cardiac ischemia leads to reduced circulating MP levels under cardiac stress. Changes of endothelial MP uptake capacities could be one possible mechanism.