A quantitative method was developed for the determination of phosphatidylcholine (PC) species concentration using nanoflow LC-ESI-MS/MS. In this study, a calibration method is developed to determine the effect of PC carbon chain length on MS peak intensity. Using the multiple standard addition method, a relationship between the peak intensities of different PC species from nanoflow LC-MS and carbon chain length is established first using different injection amounts of PC standards. From this relationship, a calibration curve for each carbon chain length can be obtained for the concentration calculation. It was found that the MS peak area of PC species analyzed by nanoflow LC-MS linearly decreased with increased acyl carbon numbers, and that the effect of the degree of acyl chain unsaturation on MS peak intensity was minimized when the injection amount was maintained at less than 1 pmol. The method was applied for the quantitative calculation of 34 PC species from rat liver, which were identified from data-dependent MS/MS analysis during nanoflow LC separation.
Purpose: Several studies have reported that laparoscopic cholecystectomy with percutaneous transhepatic gallbladder drainage (PTGBD) is associated with a reduced duration of surgery and a lower rate of conversion to open laparotomy compared with laparoscopic cholecystectomy without PTGBD and delayed laparoscopic cholecystectomy after conservative therapy. However, these results are contradictory. This retrospective study investigated the safety and usefulness of laparoscopic cholecystectomy combined with pre-operative PTGBD in patients with acute cholecystitis.
Methods:The clinicopathologic data and surgical outcomes of 101 patients who underwent laparoscopic cholecystectomy between January 2010 and September 2015 were reviewed retrospectively.
Results:Patients in the PTGBD group vs. the non-PTGBD group were significantly older (mean age: 65.47±12.2 vs. 56.32±13.7; p=0.001). Underlying diseases were also significantly more common in the PTGBD group (75.4% vs. 45.5%; p=0.002). There were no significant differences between the two groups in terms of operative time, blood loss, rate of open conversion, postoperative oral intake, and postoperative hospital stay. Total hospital day was significantly longer in the PTGBD group (11.14±7.22 vs. 6.23±5.17; p=0.049). There was no significant difference in the postoperative complications between the two groups, and all patients in this study lived.
Conclusion:This study suggested that satisfactory results can be achieved with selective preoperative PTGBD in older and sicker patients with acute cholecystitis.
An isotope dilution liquid chromatography tandem mass spectrometry was developed as a primary method for the quantitative analysis of cholesterol in infant formula. Cholesterol-d 4 was used as an internal standard and spiked into the infant formula sample. In order to release cholesterol out of cholesteryl ester, which is cholesterol bound to fatty acids in infant formula, saponification was carried out. Saponification conditions were optimized with heating temperature, reaction time and the concentration of KOH. The optimum conditions were as follows; heating temperature was 70 o C, reaction time was 180 min and the concentration of KOH was 0.8 mL of 8 M KOH for about 0.1 g infant formula sample. Extraction of cholesterol out of sample solution was carried out with hexane uisng liquid-liquid extraction. Chromatographic analysis was carried out using Phenomenex Kinetex C 18 column. Mobile phase was 0.1% acetic acid in methanol/water (v/v, 99/1) and flow rate was 0.3 mL/min. Cholesterol and cholesterol-d 4 were monitored at mass transfer m/z 369/259 and 373/ 263 respectively. Reproducibility of the method was evaluated to be 0.23% of the measurement result. The expanded uncertainty of the measurement result of cholesterol in infant formula was approximately 1.9% at a 95% confidence level. NIST standard reference material having certified values of cholesterol in infant formula, was analyzed in order to verify this method. The ID-LC/MS/MS results were well agreed with the certified values of NIST SRM within the uncertainty.
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