Gyu Seong Choi

The high throughput screening of neuropeptide FF2 receptor ligands from Korean herbal plant extracts.

We have screened 356 libraries of Korean herbal plant extracts to find potential anti-obesity drugs. We employed the recently developed fluorescence polarization high throughput screening (FP HTS) assays of human neuropeptide FF (NPFF) receptors in 384-well microtiter plates. The primary hits were cherry-picked from the libraries and further analyzed by secondary displacement curve assays, in vitro GTPgammaS binding assays and cell-based CRE luciferase reporter assays. Agonists of NPFF receptors showed biphasic affinity curves while the antagonist, BIBP 3226, gave a monophasic affinity curve in competitive binding assays. We isolated and characterized two agonists of human NPFF2 receptor, PC 314 with K(i) of 1.42 microM, and PC 315 with K(i) of 2.17 microM from Schizandra chinensis. PC 314 and PC 315 have been characterized as benzoylgomisin Q (M.W. 552) and gomisin G (M.W. 536). We report that PC 314 and PC 315 are the first non-peptide, natural compounds, which bind to human NPFF2 receptors with good affinity. PC 314 and PC 315 inhibit forskolin-stimulated luciferase expression when CHO cells are co-transfected with NPFF2 receptor and CRE reporter vector. They possess the pharmacological and functional profiles of full agonists. The FP HTS system provides a specific, sensitive and reproducible methodology for studying and screening NPFF receptor ligands.

Surgical Techniques for Totally Laparoscopic Caudate Lobectomy.

OBJECTIVES The purpose of this study is to identify the safety and feasibility of laparoscopic caudate lobectomy. BACKGROUND Caudate lobectomy has been considered as technically difficult because of the deep location of the caudate lobe and its proximity to great vessels. Due to the technical difficulty, laparoscopic caudate lobectomy was not feasible in patients with malignancy in the caudate lobe. METHODS Six consecutive patients with caudate hepatic malignancy received laparoscopic caudate lobectomy at Samsung Medical Center from September 2007 to May 2014. Demographic data, intraoperative parameters, and postoperative outcomes were assessed. RESULTS All procedures for these 6 patients with caudate malignancy were completed with totally laparoscopic technique. Only 1 patient who had hepatocellular carcinoma in the Spiegel lobe underwent partial caudate lobectomy, and others underwent complete caudate lobectomy. The mean tumor size was 2.65 cm (range 0.9-5.1 cm). The mean operative time was 382 minutes (range 168-615 minutes) and none required transfusion. The mean duration of hospital stay was 8 days (range 6-13 days). There was no perioperative complication and patient mortality in this series. The resected margins of the specimens were tumor free (R0 resections, range 0.1-1.2 cm). The mean follow-up period was 56 months (range 12.9-93.7 months). No patient died during the follow-up period. CONCLUSIONS Our experience demonstrated that laparoscopic caudate lobectomy is safe and feasible in selected patients with malignancy in the caudate lobe.

De novo hepatitis b prophylaxis with hepatitis B virus vaccine and hepatitis B immunoglobulin in pediatric recipients of core antibody–positive livers

The use of hepatitis B core antibody–positive (HBcAb+) grafts for liver transplantation (LT) has the potential to safely expand the donor pool, as long as proper prophylaxis against de novo hepatitis B (DNHB) is employed. The aim of this study was to characterize the longterm outcome of pediatric LT recipients of HBcAb+ liver grafts under a prophylaxis regimen against DNHB using hepatitis B virus (HBV) vaccine and hepatitis B immunoglobulin (HBIG). From June 1996 to February 2013, 49 patients receiving pediatric LT at our center were from HBcAb+ donors. Forty‐one patients who received DNHB prophylaxis according to our protocol were included in this analysis. Our DNHB prophylaxis protocol consists of HBV vaccine intramuscular injections given intermittently to maintain anti–hepatitis B surface antibody (HBsAb) titers above 100 IU/L. HBIG was also used during the first posttransplant year with a target anti‐HBsAb titer level above 200 IU/L. There were 19 boys and 22 girls. Median age was 1.0 year (range, 4 months to 16 years). Median follow‐up time was 66 months after transplant. Median annual number of HBV vaccine injections was 0.8 per year (range, 0‐1.8 per year). Four patients did not require any HBV vaccine injections during follow‐up. One patient with DNHB was encountered during the follow‐up period (1/41, 2.4%). DNHB was diagnosed at 3.5 years after transplant, when hepatitis B surface antigen was positive upon routine follow‐up serologic testing. Anti‐HBsAb titer was 101.5 IU/L at the time. No grafts were lost because of DNHB‐related events. Overall survival of the 41 recipients of HBcAb+ grafts who received DNHB prophylaxis was 92.3% at 10 years after transplant. In conclusion, longterm prophylaxis against DNHB with HBV vaccine in pediatric LT recipients of HBcAb+ grafts was safe and effective in terms of DNHB incidence as well as graft and patient survival. Liver Transpl 22:247–251, 2016.

Tissue expander placement and adjuvant radiotherapy after surgical resection of retroperitoneal liposarcoma offers improved local control.

AbstractGiven that retroperitoneal liposarcoma (LPS) is extremely difficult to completely resect, and has a relatively high rate of recurrence, radiotherapy (RT) is the treatment of choice after surgical resection. However, it is difficult to obtain a sufficient radiation field because of the close proximity of surrounding organs. We introduce the use of tissue expanders (TEs) after LPS resection in an attempt to secure a sufficient radiation field and to improve recurrence-free survival.This study is a retrospective review of 53 patients who underwent surgical resection of LPS at Samsung Medical Center between January 1, 2005, and December 31, 2012, and had no residual tumor detected 2 months postoperatively. The median follow-up period was 38.9 months.Patients were divided into 3 groups. Those in group 1 (n = 17) had TE inserted and received postoperative RT. The patients in group 2 (n = 9) did not have TE inserted and received postoperative RT. Finally, those in group 3 (n = 27) did not receive postoperative RT. Multivariate analysis was performed to identify the risk factors associated with recurrence-free survival within 3 years. Younger age, history of LPS treatment, and RT after TE insertion (group 1 vs group 2 or 3) were significantly favorable factors influencing 3-year recurrence-free survival.TE insertion after LPS resection is associated with increased 3-year recurrence-free survival, most likely because it allows effective delivery of postoperative RT.

Outcome of living donor liver transplantation using right liver allografts with multiple arterial supply

A right liver graft with multiple hepatic artery (HA) stumps can be found in approximately 5% of living donor liver transplantation (LDLT) using a right lobe graft. From January 2000 to June 2014, 1149 patients underwent LDLT procedures. Thirty patients with LDLT using a right lobe graft with multiple HA stumps and 149 patients with LDLT using a right lobe graft with a single HA stump were enrolled. These patients were divided into 3 groups: single HA (group 1, n = 149), multiple HAs with total reconstruction (group 2, n = 19), and multiple HAs with selective partial reconstruction (group 3, n = 11). Selective partial reconstruction was performed only when pulsatile back‐bleeding was confirmed after larger HA reconstruction and sufficient intrahepatic arterial flow was confirmed by Doppler ultrasound (DUS). In group 2, the donor HAs were smaller (P < .001), and HA reconstruction took longer (P < .001). However, there was no significant difference among the groups regarding the arterial complication rate, biliary complication rate, and patient and graft survival. In conclusion, selective partial reconstruction of HA stumps for LDLT using a right lobe graft was feasible when intrahepatic arterial communication was confirmed by pulsatile back‐bleeding from the smaller artery and DUS. Liver Transplantation 22 1649–1655 2016 AASLD.