Adverse events of self-expandable metal stent placement for malignant distal biliary obstruction: a large multicenter study.

BACKGROUND AND AIMS: Endoscopic placement of self-expandable metal stents (SEMSs) for malignant distal biliary obstruction (MDBO) may be accompanied by several types of adverse events. The present study analyzed the adverse events occurring after SEMS placement for MDBO. METHODS: The present study retrospectively investigated the incidence and types of adverse events in patients who underwent SEMS placement for MDBO between April 2018 and March 2021 at 26 hospitals. Risk factors for acute pancreatitis, cholecystitis, and recurrent biliary obstruction (RBO) were evaluated by univariate and multivariate analyses. RESULTS: Of the 1425 patients implanted with SEMSs for MDBO, 228 (16.0%) and 393 (27.6%) experienced early adverse events and RBO, respectively. Pancreatic duct without tumor involvement (P = .023), intact papilla (P = .025), and SEMS placement across the papilla (P = .037) were independent risk factors for acute pancreatitis. Tumor involvement in the orifice of the cystic duct was an independent risk factor for cholecystitis (P < .001). Use of fully and partially covered SEMSs was an independent risk factor for food impaction and/or sludge. Use of fully covered SEMSs was an independent risk factor for stent migration. Use of uncovered SEMSs and laser-cut SEMSs was an independent risk factor for tumor ingrowth. CONCLUSIONS: Pancreatic duct without tumor involvement, intact papilla, and SEMS placement across the papilla were independent risk factors for acute pancreatitis, and tumor involvement in the orifice of the cystic duct was an independent risk factor for cholecystitis. The risk factors for food impaction and/or sludge, stent migration, and tumor ingrowth differed among types of SEMSs.

Production of sophorolipids from non-edible jatropha oil by Stamerella bombicola NBRC 10243 and evaluation of their interfacial properties.

To facilitate the development of bio-based chemicals from renewable and inexpensive natural resources, we sought to produce biosurfactants using non-edible jatropha oil. Twenty yeasts known to produce biosurfactants were tested in this study, and Stamerella bombicola NBRC 10243 was found to use jatropha oil efficiently to produce sophorolipids (SLs) as a mixture of lactone-form SL (L-SL) and acid-form SL (A-SL). Under culture conditions using rice bran as the source of organic nutrients, the yield of SLs reached 122.6 g/L in 5-L jar fermentors after 9 d in culture. HPLC analysis of the culture medium showed that the levels of phorbol esters (PEs), major toxic components of the oil, decreased markedly with an increase in culture time, suggesting that the yeast degrades PEs. Although the SLs obtained by solvent extraction of the culture medium contained a small amount of PEs, the sodium salt of A-SL (A-SL-Na) obtained by alkaline treatment (5N NaOH, 80°C) showed no PE peaks upon HPLC analysis. A-SL-Na had excellent surface activity with low CMC (9.0×10⁻4 M) and γ(CMC) (29.6 mN/m), which are lower than that of sodium dodecyl sulfate (SDS). The solubilizing ability of A-SL-Na toward for octanoic acid ([octanoic acid]/[A-SL-Na]) was found to be 2.0, which is half that of SDS. Our findings should help improve SL production from non-edible feedstock and broaden the use of promising bio-based surfactants.