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Abstract Background Lake Bonney, which is divided into a west lobe (WLB) and an east lobe (ELB), is a perennially ice-covered lake located in the McMurdo Dry Valleys of Antarctica. Despite previous reports on the microbial community dynamics of ice-covered lakes in this region, there is a paucity of information on the relationship between microbial genomic diversity and associated nutrient cycling. Here, we applied gene- and genome-centric approaches to investigate the microbial ecology and reconstruct microbial metabolic potential along the depth gradient in Lake Bonney. Results Lake Bonney is strongly chemically stratified with three distinct redox zones, yielding different microbial niches. Our genome enabled approach revealed that in the sunlit and relatively freshwater epilimnion, oxygenic photosynthetic production by the cyanobacterium Pseudanabaena and a diversity of protists and microalgae may provide new organic carbon to the environment. CO-oxidizing bacteria, such as Acidimicrobiales, Nanopelagicales, and Burkholderiaceae were also prominent in the epilimnion and their ability to oxidize carbon monoxide to carbon dioxide may serve as a supplementary energy conservation strategy. In the more saline metalimnion of ELB, an accumulation of inorganic nitrogen and phosphorus supports photosynthesis despite relatively low light levels. Conversely, in WLB the release of organic rich subglacial discharge from Taylor Glacier into WLB would be implicated in the possible high abundance of heterotrophs supported by increased potential for glycolysis, beta-oxidation, and glycoside hydrolase and may contribute to the growth of iron reducers in the dark and extremely saline hypolimnion of WLB. The suboxic and subzero temperature zones beneath the metalimnia in both lobes supported microorganisms capable of utilizing reduced nitrogens and sulfurs as electron donors. Heterotrophs, including nitrate reducing sulfur oxidizing bacteria, such as Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), and denitrifying bacteria, such as Gracilimonas (MAG7), Acidimicrobiales (MAG72) and Salinisphaeraceae (MAG109), dominated the hypolimnion of WLB, whereas the environmental harshness of the hypolimnion of ELB was supported by the relatively low in metabolic potential, as well as the abundance of halophile Halomonas and endospore-forming Virgibacillus. Conclusions The vertical distribution of microbially driven C, N and S cycling genes/pathways in Lake Bonney reveals the importance of geochemical gradients to microbial diversity and biogeochemical cycles with the vertical water column.

Abstract X-linked inhibitor of apoptosis protein (XIAP) deficiency causes refractory inflammatory bowel disease. The XIAP protein plays a pivotal role in the pro-inflammatory response through the nucleotide-binding oligomerization domain-containing signaling pathway that is important in mucosal homeostasis. We analyzed the molecular mechanism of non-synonymous pathogenic variants (PVs) of XIAP BIR2 domain. We generated N-terminally green fluorescent protein-tagged XIAP constructs of representative non-synonymous PVs. Co-immunoprecipitation and fluorescence cross-correlation spectroscopy showed that wild-type XIAP and RIP2 preferentially interacted in live cells, whereas all non-synonymous PV XIAPs failed to interact properly with RIP2. Structural analysis showed that various structural changes by mutations, such as hydrophobic core collapse, Zn-finger loss, and spatial rearrangement, destabilized the two loop structures (174–182 and 205–215) that critically interact with RIP2. Subsequently, it caused a failure of RIP2 ubiquitination and loss of protein deficiency by the auto-ubiquitination of all XIAP mutants. These findings could enhance our understanding of the role of XIAP mutations in XIAP-deficient inflammatory bowel disease and may benefit future therapeutic strategies.

Background : Portal vein (PV) interposition can induce various PV-related complications, making more reliable techniques necessary. The present study describes the development of a modified patch venoplasty technique, combining the native PV wall and a vein homograft conduit, called modified patch-conduit venoplasty (MPCV). Methods : The surgical technique for MPCV was optimized by simulation and applied to seven pediatric patients undergoing liver transplantation (LT) for biliary atresia combined with PV hypoplasia. Results : The simulation study revealed that inserting the whole-length native PV wall as a longitudinal rectangular patch was more effective in preventing PV conduit stenosis than the conventional technique using triangular partial insertion. These findings were used to develop the MPCV technique, in which the native PV wall was converted into a long rectangular patch, acting as a backbone for PV reconstruction. A longitudinal incision on the vein conduit converted the cylindrical vein into a large vein patch. The wall of the native PV was fully preserved as the posterior wall of the PV conduit, thus preventing longitudinal redundancy and unwanted rotation of the reconstructed PV. This technique was applied to seven patients with biliary atresia undergoing living-donor and deceased-donor split LT. None of these patients has experienced PV complications for up to 12 months after transplantation. Conclusions: This newly devised MCPV technique can replace conventional PV interposition. MCPV may be a surgical option for reliable PV reconstruction using fresh or cryopreserved vein homografts during pediatric LT.

Background and Aims: Biliary atresia is a rare and devastating bile duct disease that occurs during the neonatal period. Timely identification and prompt surgical intervention is critical for improving the outcome. The aim of the study was to develop a new machine learning–based prediction model for the detection of biliary atresia. Methods: Neonates aged

Purpose This study evaluated the accuracy of attenuation imaging (ATI) for the assessment of hepatic steatosis in pediatric patients, in comparison with the FibroScan vibration-controlled transient elastography controlled attenuation parameter (CAP). Methods Consecutive pediatric patients referred for evaluation of obesity who underwent both ATI and FibroScan between February 2020 and September 2021 were included. The correlation between attenuation coefficient (AC) and CAP values was assessed using the Spearman test. The AC cutoff value for discriminating hepatic steatosis corresponding to a CAP value of 241 dB/m was calculated. Multivariable linear regression analysis was performed to estimate the strength of the association between AC and CAP. The diagnostic accuracy of AC cutoffs was estimated using the imperfect gold-standard methodology based on a two-level Bayesian latent class model. Results Seventy patients (median age, 12.5 years; interquartile range, 11.0 to 14.0 years; male:female, 58:12) were included. AC and CAP showed a moderate-to-good correlation (ρ =0.646, P

Biliary rhabdomyosarcoma is a rare tumor, but it is still the most common tumor of the biliary tract in children. We report a case of a 6-year-old boy with biliary embryonal rhabdomyosarcoma and liver metastasis, which were treated with neoadjuvant and adjuvant chemotherapy combined with living donor liver transplantation (LDLT). Initial imaging studies showed a low-attenuation intraductal mass from the left hepatic duct to the intrapancreatic common bile duct with diffuse upstream dilatation of the intrahepatic duct and liver metastasis. Endoscopic biopsy revealed embryonal rhabdomyosarcoma. After tumor size reduction through neoadjuvant chemotherapy, LDLT was planned to remove the tumor completely. A left lateral section graft weighing 330 g was harvested from his 38-year-old mother and the graft-to-recipient weight ratio was 1.94%. Routine pediatric LDLT operation was performed with deep excavation of intrapancreatic distal bile duct. The explant liver showed minimal residual embryonal rhabdomyosarcoma with no lymph node metastasis. The patient recovered uneventfully from LDLT operation. Scheduled adjuvant chemotherapy was performed for 6 months. The patient is doing well without any evidence of tumor recurrence for 26 months after LDLT. In conclusion, liver transplantation could be an effective treatment for unresectable biliary rhabdomyosarcoma in children according to the location of tumor.

Background/Aims: Although pediatric ulcerative colitis (UC) has a different phenotype and clinical course than adult UC, its clinical features and outcomes are poorly defined, especially in Asian populations. This study investigated the clinical features and long-term outcomes of pediatric UC in a Korean population. Methods: We retrospectively analyzed 208 patients aged

Progressive familial intrahepatic cholestasis (PFIC) is an autosomal recessive inherited disease requiring liver transplantation (LT). Hepatocellular carcinoma (HCC) is very rare in infants. We present a case of living donor LT using a left lateral section graft performed in a 7-month-old female infant diagnosed with PFIC type II and HCC. No mutation on ABCB11 gene was identified. Because of progressive deterioration of liver function, living donor LT with her mother’s left lateral section graft was performed. Pretransplant serum alpha-fetoprotein (AFP) level was increased to 2,740 ng/mL, but HCC was not taken into account because of its rarity. The explant liver showed micronodular liver cirrhosis, multiple infantile hemangiomas and two HCCs of 0.7 cm and 0.3 cm in size. The patient recovered uneventfully from the LT operation. This patient has been regularly followed up with abdomen ultrasonography and AFP measurement every 6 months. The patient has been continually doing well for 8 years after the LT. In conclusion, LT is currently the only effective treatment for PFIC-associated end-stage liver diseases. HCC can develop at the cirrhotic liver of any cause, thus elevation of HCC tumor markers in pediatric patients is an important clue to perform further investigation before LT.

Background & Aims: Bile salt export pump (BSEP) deficiency frequently necessitates liver transplantation in childhood. In contrast to two predicted protein truncating mutations (PPTMs), homozygous p.D482G or p.E297G mutations are associated with relatively mild phenotypes, responsive to surgical interruption of the enterohepatic circulation (siEHC). The phenotype of patients with a compound heterozygous genotype of one p.D482G or p.E297G mutation and one PPTM has remained unclear. We aimed to assess their genotype-phenotype relationship. Methods: From the NAPPED database, we selected patients with homozygous p.D482G or p.E297G mutations (BSEP1/1; n = 31), with one p.D482G or p.E297G, and one PPTM (BSEP1/3; n = 30), and with two PPTMs (BSEP3/3; n = 77). We compared clinical presentation, native liver survival (NLS), and the effect of siEHC on NLS. Results: The groups had a similar median age at presentation (0.7-1.3 years). Overall NLS at age 10 years was 21% in BSEP1/3 vs. 75% in BSEP1/1 and 23% in BSEP3/3 (p

Background/Aims: Recently, the treatment of Crohn’s disease (CD) has changed to a treat-to-target strategy, in which disease progression is prevented with early intervention. We analyzed the long-term evolution of nonstricturing, nonpenetrating (B1) disease at diagnosis and factors related to disease evolution in pediatric CD. Methods: We retrospectively analyzed 402 patients between 2000 and 2013 who were younger than 18 years and had B1 disease at CD diagnosis. The median follow-up was 6.1 years (range, 1 to 13 years). The cumulative probabilities of developing stricturing (B2) or penetrating (B3) disease and associations between risk factors and disease behavior evolution were evaluated. Results: Among the 402 patients, 75 (18.7%) had B2 or B3 disease by the final follow-up. The cumulative probabilities of disease behavior evolution were 18.3%, 34.3%, and 50.9% at 5, 10, and 13 years, respectively. Patients whose disease progressed had an increased risk of intestinal resection (hazard ratio [HR], 3.61; 95% confidence interval [CI], 2.25 to 6.03; p

Background : Some young adults have a long survival period with native liver after Kasai portoenterostomy (KPE) for biliary atresia (BA). However, a considerable proportion of these patients require liver transplantation (LT). This study aimed to analyze the indications and outcomes of LT in young adults after a long survival period with native liver after KPE. Methods : We selected seven patients who were 18 years or older at the time of LT out of 116 BA patients who underwent primary LT from 2008 to 2019 at Asan Medical Center. Results : The mean ages at KPE and LT were 2.1±0.9 months and 22.0±5.1 years, respectively. Mean serum total bilirubin level and model for end-stage liver disease score at LT were 7.91±7.22 mg/dL and 15.3±6.0, respectively. The main reasons for LT were liver cirrhosis with portal hypertension-associated complications in five patients and intractable cholangitis in two patients. There were five cases of living donor LT and two cases of deceased donor LT. All the seven patients are currently alive during the mean follow-up period of 74.7±40.9 months. One patient suffered from outflow graft vein obstruction requiring endovascular stenting. Another patient showed core antibody-positivity-induced de novo hepatitis B virus infection, which was well managed with antiviral therapy. Conclusions: Young adult patients with BA are a unique group of patients requiring specialist care regarding transition from pediatric to adult services. The outcomes of LT in young adult BA patients were excellent. Therefore, LT should be considered in patients showing serious BA-associated complications.

A FAC (flow-accelerated corrosion) test was performed for a straight pipe composed of the SA335 Gr P22 and SA106 Gr B (SA106-SA335-SA106) types of steel with welds as a function of the flow rate in the range of 7–12 m/s at 150 °C and with DO

Nanofluid (NF) pool boiling experiments have been conducted widely in the past two decades to study and understand how nanoparticles (NP) affect boiling heat transfer and critical heat flux (CHF). However, the physical mechanisms related to the improvements in CHF in NF pool boiling are still not conclusive due to the coupling effects of the surface characteristics and the complexity of the experimental data. In addition, the current models for pool boiling CHF prediction, which consider surface microstructure characteristics, show limited agreement with the experimental data and do not represent NF pool boiling CHF. In this scenario, artificial intelligence tools, such as machine learning (ML) regressor models, are a very promising means of solving this nonlinear problem. This study focuses on creating a new model to provide more accurate NF pool boiling CHF predictions based on pressure, substrate thermal effusivity, and NP size, concentration, and effusivity. Three ML models (supporting vector regressor—SVR, multi-layer perceptron—MLP, and random forest—RF) were constructed and showed good agreement with an experimental database built from the literature, with MLP presenting the highest mean R2 score and the lowest variability. A systematic methodology for optimizing the ML models is proposed in this work.

Abstract Background Prognostic factors in hepatoblastoma need to be reevaluated considering the advances in treatment modalities. The study aimed to evaluate current outcomes of hepatoblastoma and reappraise the association of prognostic factors, including pre‐treatment extent of tumor (PRETEXT) stage with annotation factors and Children's Hepatic tumors International Collaboration‐Hepatoblastoma Stratification (CHIC‐HS) system, with survival outcomes. Methods We evaluated 103 consecutive patients with hepatoblastoma retrospectively according to the treatment period based on the introduction of a liver transplantation program. Results The 5‐year overall survival (OS), event‐free survival (EFS), and transplant‐free survival rates were 80.2%, 74.2%, and 61.8%, respectively. EFS and OS were improved significantly from 58.6% to 81.6% (P = 0.024) and from 58.6% to 90.8% (P

Congenital factor X (FX) deficiency is a rare autosomal-recessive disease that induces bleeding disorder. Herein, we present the 10-year posttransplant course of a pediatric patient who underwent liver transplantation (LT) with portal vein (PV) stenting for correction of severe congenital FX deficiency, with focus on long-term maintenance of coagulation function and patency of PV stenting. A 17-month-old infant with recurrent hemorrhagic episodes due to FX deficiency underwent split LT using a left lateral section graft. The graft-recipient weight ratio was 2.2%. The graft implantation procedures were performed by following the standard pediatric split LT procedure. Nevertheless, a wall stent was inserted due to PV anastomotic stenosis on posttransplant day 1. Graft function recovered slowly because of partial parenchyma infarct, and the patient was discharged at 46 days after LT operation. The FX activity started to increase soon after LT and gradually normalized; the coagulation profiles have been maintained well for the past 10 years. The patient has been doing well for the past 10 years after LT without any episodes of abnormal bleeding. Due to the risk of vascular complications owed to PV stenting, life-long follow-up is mandatory with special attention until attainment of complete physical growth to adolescent and adulthood.

Congenital absence of the portal vein (CAPV) is a rare venous malformation in which mesenteric venous blood drains directly into systemic circulation. Herein, we report a case of pediatric deceased donor liver transplantation (DDLT) for symptomatic CAPV with whole liver graft from a hepatitis B surface antigen (HBsAg)-positive donor. A 4-year-old boy suffered from CAPV and secondary portal hypertension. He was also diagnosed with DiGeorge syndrome and heart anomalies. After waiting for 4 months, a 5-year-old donor weighing 19 kg with positive HBsAg was allocated to this 4-year-old patient weighing 15 kg. Recipient operation was performed according to the standard procedures of pediatric DDLT. Portal vein reconstruction was performed using interposition of a vascular homograft conduit to the superior mesenteric vein-splenic vein confluence. The patient recovered uneventfully from DDLT. He has been administered with lamivudine to prevent hepatitis B virus infection. This patient has been doing well for 5 years after DDLT without growth retardation. In conclusion, CAPV patients can have various vascular anomalies, thus combined vascular anomalies should be thoroughly assessed before and during liver transplantation operation. The most effective reconstruction techniques should be used to achieve satisfactory results following liver transplantation.

Conventional integral effect test facilities were constructed to enable the precise observation of thermal–hydraulic phenomena and reactor behaviors under postulated accident conditions to prove reactor safety. Although these facilities improved the understanding of thermal–hydraulic phenomena and reactor safety, applications of new technologies and their performance tests have been limited owing to the cost and large scale of the facilities. Various nuclear technologies converging 4th industrial revolution technologies such as artificial intelligence, drone, and 3D printing, are being developed to improve plant management strategies. Additionally, new conceptual passive safety systems are being developed to enhance reactor safety. A new integral effect test facility having a noticeable scaling ratio, i.e., the (UNIST reactor innovation loop (URI-LO), is designed and constructed to improve the technical quality of these technologies by performance and feasibility tests. In particular, the URI-LO, which is constructed using a transparent material, enables better visualization and provides physical insights on multidimensional phenomena inside the reactor system. The facility design based on three-level approach is qualitatively validated with preliminary analyses, and its functionality as a test facility is confirmed through a series of experiments. The design feature, design validation, functionality test, and future utilization of the URI-LO are introduced.

Background : We investigated the incidence and outcomes of pediatric deceased donor liver transplantation (DDLT) using whole liver grafts in a high-volume liver transplantation (LT) center. Methods : The study was a retrospective single-center analysis of whole LT in pediatric recipients. The study period was set as 20 years between January 2000 and December 2019. We defined pediatric recipients and donors to be aged ≤18 years. Results : During the study period, there were 98 cases of pediatric DDLT, and 34 patients (34.7%) received whole liver grafts. The age range of the deceased donors was 3 months to 56 years and that of pediatric recipients was 7 months to 17 years. Common primary diseases for LT were biliary atresia in 13, acute liver failure in four, Wilson disease in four, congenital portal vein agenesis in three, and genetic metabolic diseases in three. Pediatric-to-pediatric and adult-to-pediatric whole LTs were 22 (64.7%) and 12 (35.3%), respectively. A good correlation was noted between the donor and the recipient’s body weight, and the recipient’s body weight and allograft’s weight. Graft and overall patient survival rates were 91.2% and 91.2% at 1 year, 88.0% and 88.0% at 3 years, and 88.0% and 88.0% at 5 years, respectively. Conclusions: The results of this study revealed that Korean Network for Organ Sharing (KONOS) regulations with donor-recipient body weight matching exhibited good performance. Considering the reciprocal trades of liver organs among pediatric and adult donors and recipients, it is necessary to establish a policy for pediatric donor liver grafts to pediatric recipients on a priority basis.

Biliary atresia (BA)-polysplenia syndrome (PS) is diagnosed in a small proportion of BA patients. We present a case of split liver transplantation (LT) successfully performed in a pediatric recipient with BA-PS. The recipient was 29-month-old boy who underwent Kasai procedure. The coexisting malformations included agenesis of the inferior vena cava with azygos vein continuation, polysplenia, intestinal malrotation, truncated pancreas, and preduodenal portal vein and annular pancreas. With pediatric end-stage liver disease score of 33, the patient was allocated for split LT. Under this condition, the left lateral section graft was equivalent to a graft-recipient weight ratio of 2.6%. The recipient surgery was performed according to the standard procedures of pediatric LT. The graft hepatic vein was directly anastomosed with the suprahepatic confluence of the recipient hepatic veins. An external iliac vein homograft was interposed for portal vein reconstruction. Portal collateral veins were embolized intraoperatively to secure portal vein inflow. No surgical complications were developed. Currently, the patient has been doing well for 4 years after transplantation. Our pediatric patient with BA-PS had various anatomical malformations. Thorough preoperative and intraoperative assessment of these anomalies, adoption of customized reconstruction techniques of LT, and careful posttransplant monitoring are necessary for successful LT.

Laparoscopically harvested left liver (LL) grafts have drawbacks with respect to the size and shape of graft hepatic vein orifices. We present two cases of pediatric living donor liver transplantation (LDLT) using laparoscopically harvested LL grafts and describe refined surgical techniques for graft hepatic vein venoplasty. The first case was a boy aged 4 years and 5 months, with hepatoblastoma. The donor was his 35-year-old mother, and LL graft weighed 315 g. Two separate openings of the graft at the left hepatic vein (LHV) and middle hepatic vein (MHV) were unified through septotomy and septoplasty, and cryopreserved vein homograft patch was attached. Standard procedures of LDLT were performed. This patient recovered uneventfully and has been doing well for 4 years without tumor recurrence. The second case was a 6-year-old girl with ornithine transcarbamylase deficiency. The donor was her 35-year-old mother, and the LL graft weighed 310 g. Two separate openings of graft MHV, with segment III and segment II veins, were unified through septoplasty, and vein patch was attached. Standard procedures of LDLT were performed. This patient has been doing well for 4 years. In conclusion, separate graft hepatic vein openings are a drawback of laparoscopically harvested LL grafts, which thus require unification venoplasty of customized design individually tailored for LL graft and pediatric recipient.

Summary: Background: Few studies have described the aetiologies of neonatal cholestasis, and the overall neonatal cholestasis-related mortality (NCM) rate is unclear. We investigated the aetiology and outcome of neonatal cholestasis in a tertiary hospital and developed an NCM prediction model for these patients. Methods: Patients aged 1.0 mg/dL were retrospectively screened. Diagnostic and laboratory data during the 8-week follow-up period after enrolment between 2005 and 2020 were extracted digitally, and medical charts were reviewed manually by clinicians. Logistic regression was used to derive a prediction model for the 1-year mortality outcome of neonatal cholestasis, and performance evaluation and external validation were conducted for the NCM prediction model. Findings: We enrolled 4028 neonates with DB of >1.0 mg/dL at least once. Prematurity and birth injury (35.4%), complex heart anomalies (18.6%), liver diseases (11.4%), and gastrointestinal anomalies (9.2%) were the most common aetiologies; 398 (9.9%) patients died before one year of age. The peak value of DB was positively correlated to the 1-year mortality rate. In the multivariate analysis, simple laboratory indices, including platelet, prothrombin time, aspartate aminotransferase, albumin, direct bilirubin, creatinine, and C-reactive protein, were independent predictors of 1-year mortality outcome of complete-case subjects. Using these laboratory indices, a logistic regression-based NCM prediction model was constructed. It showed acceptable performances on discrimination (area under the curve, 0.916), calibration (slope, 1.04) and Brier scoring (0.072). The external validation of the sample (n = 920) from two other centres also revealed similar performance profiles of the NCM model. Interpretation: Various aetiologies of neonatal cholestasis were identified in a tertiary hospital, resulting in unfavourable outcomes of a large proportion. The NCM prediction model may have the potential to help clinicians to be aware of high-risk neonatal cholestasis.

We present a case of successful split liver transplantation (LT) using a hyperreduced left lateral segment (LLS) graft in a 106-day-old female infant patient weighing 4 kg. The patient was diagnosed with progressive familial intrahepatic cholestasis. Her general condition and liver function deteriorated progressively and she was finally allocated for a split LT under status 1. The deceased donor was a 20-year-old female weighing 63.7 kg. We performed in situ liver splitting and in situ size reduction sequentially. The weight of the hyperreduced LLS graft was 225 g, with a graft-recipient weight ratio of 5.5%. We performed recipient hepatectomy and graft implantation according to the standard procedures for pediatric living-donor LT. Since the graft was too large for primary abdomen closure, the abdominal wall was closed in three stages to make a prosthetic silo, temporary closure with a xenograft sheet, and final primary repair over 2 weeks. The patient has been doing well for more than 6 years after transplantation. In conclusion, split LT using a hyperreduced LLS graft can be a useful option for treating small infants. However, large-for-size graft-related problems, particularly in terms of graft thickness, still remain to be solved.

Background : The present study intended to investigate the allocation status of pediatric deceased donor liver allografts. We analyzed the incidence of pediatric deceased donors in the Korean Network for Organ Sharing (KONOS) database and single-institutional status of liver transplantation (LT) using pediatric donors. Methods : We assessed the nationwide incidence of pediatric donors aged ≤15 years and conducted single-center analysis of LT using pediatric donors. Results : Between 2010 and 2019, pediatric donors aged ≤15 years accounted for 171 out of 4,395 donors (3.9%) in the KONOS database and 31 out of 640 liver donors (4.8%) in Asan Medical Center (AMC) database. In AMC, 11 (35.5%) and 20 (64.5%) grafts were allocated to pediatric recipients aged ≤15 years and adult recipients aged ≥19 years, respectively. All nine livers from donors aged ≤5 years were implanted in pediatric recipients aged ≤5 years. From 21 donors aged ≥9 years, 16 whole liver grafts and four split extended right liver grafts were implanted in 20 adult recipients and two split left lateral section grafts were implanted in two pediatric recipients. Four split liver grafts were implanted in other institutions. The overall patient survival rates at 1, 3, and 5 years were 90.9%, 80.8%, and 80.8%, respectively in pediatric-to-pediatric LT group and 69.6%, 58.4%, and 58.4%, respectively in pediatric-to-adult LT group (P=0.21). Conclusions: More than half of the pediatric donor livers were allocated to adult patients. Recipient criteria for allocation of liver allografts from pediatric donors need revision for children on pediatric LT waitlist.

Laparoscopically harvested left lateral section (LLS) grafts have drawbacks regarding the size of the graft left hepatic vein (LHV) orifice although they have the merit of cosmetics concerning the donor’s wound. We present a case of pediatric living donor liver transplantation (LDLT) using a laparoscopically harvested LLS graft and describe the refined surgical techniques for graft LHV venoplasty with a circumferential vein patch. The patient was a 46-month-old boy with marked growth retardation who was diagnosed with progressive familial intrahepatic cholestasis type 2. The donor was his 25-year-old mother. The LLS graft weighed 285 g. A circumferential patch of external iliac vein homograft was attached to the graft LHV orifice after incisions were made at the medial wall of the LHV trunk and superficial LHV branch, which made the graft LHV orifice much larger. The recipient’s hepatic vein orifice was also enlarged by unifying the three hepatic vein orifices. Other surgical procedures followed the standard LDLT operation. This patient recovered uneventfully and has been doing well for 1 year. In conclusion, our incision-and-patch venoplasty to enlarge the graft outflow vein orifice was beneficial for reducing the risk of hepatic vein outflow obstruction in LDLT using a laparoscopically harvested LLS graft.

Background Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of autosomal recessive liver diseases that present as neonatal cholestasis. Little is known of this disease in Korea. Methods The records of five patients histologically diagnosed with PFIC, one with PFIC1 and four with PFIC2, by liver biopsy or transplant were reviewed, and ATP8B1 and ABCB11 mutation status was analyzed by direct DNA sequencing. Clinicopathological characteristics were correlated with genetic mutations. Results The first symptom in all patients was jaundice. Histologically, lobular cholestasis with bile plugs was the main finding in all patients, whereas diffuse or periportal cholestasis was identified only in patients with PFIC2. Giant cells and ballooning of hepatocytes were observed in three and three patients with PFIC2, respectively, but not in the patient with PFIC1. Immunostaining showed total loss of bile salt export pump in two patients with PFIC2 and focal loss in two. Lobular and portal based fibrosis were more advanced in PFIC2 than in PFIC1. ATP8B1 and ABCB11 mutations were identified in one PFIC1 and two PFIC2 patients, respectively. One PFIC1 and three PFIC2 patients underwent liver transplantation (LT). At age 7 months, one PFIC2 patient was diagnosed with concurrent hepatocellular carcinoma and infantile hemangioma in an explanted liver. The patient with PFIC1 developed steatohepatitis after LT. One patient showed recurrence of PFIC2 after 10 years and underwent LT. Conclusions PFIC is not rare in patients with neonatal cholestasis of unknown origin. Proper clinicopathologic correlation and genetic testing can enable early detection and management.

Thermal management of mobile electronics has been carried out because performance of the application processor has increased and power dissipation in miniaturized devices is proportional to its functionalities. There have been various studies on thermal analyses related to mobile electronics with the objectives of improving analysis methodologies and cooling strategies to guarantee device safety. Despite these efforts, failure to control thermal energy, especially in smartphones, has resulted in explosions, because thermal behaviors in the device under various operating conditions have not been sufficiently conducted. Therefore, several scenarios that caused the failure in thermal management of smartphone was analyzed to provide improved insight into thermal design deducing the parameters, that affect the thermal management of device. Overcurrent in battery due to malfunction of battery management system or immoderate addition of functionalities to the application processor are considered as reliable causes leading to the recent thermal runaways and explosions. From the analyses, it was also confirmed that the heat generation of the battery, which have not been considered importantly in previous literature, has significant effect on thermal management, and heat spreading could be suppressed according to arrangement of AP and battery. The heat pipe, which is utilized as a cooling device in mobile electronics, was also included in the thermal analyses. Although the heat pipes have been expected to improve the thermal management in mobile electronics, it showed limited heat transfer capacity due to its operating conditions and miniaturization. The demonstrated results of our analysis warn against vulnerabilities of smartphones in terms of safety in design. Keywords: Smartphone, Thermal analysis, Cooling, Lithium ion battery, Heat pipe

Adverse clinical events in primary sclerosing cholangitis (PSC) happen too slowly to capture during clinical trials. Surrogate endpoints are needed, but no such validated endpoints exist for children with PSC. We evaluated the association between gamma glutamyltransferase (GGT) reduction and long‐term outcomes in pediatric PSC patients. We evaluated GGT normalization (< 50 IU/L) at 1 year among a multicenter cohort of children with PSC who did or did not receive treatment with ursodeoxycholic acid (UDCA). We compared rates of event‐free survival (no portal hypertensive or biliary complications, cholangiocarcinoma, liver transplantation, or liver‐related death) at 5 years. Of the 287 children, mean age of 11.4 years old, UDCA was used in 81% at a mean dose of 17 mg/kg/day. Treated and untreated groups had similar GGT at diagnosis (314 versus 300, P= not significant [NS]). The mean GGT was reduced at 1 year in both groups, with lower values seen in treated (versus untreated) patients (99 versus 175, P= 0.002), but 5‐year event‐free survival was similar (74% versus 77%, P= NS). In patients with GGT normalization (versus no normalization) by 1 year, regardless of UDCA treatment status, 5‐year event‐free survival was better (91% versus 67%, P< 0.001). Similarly, larger reduction in GGT over 1 year (> 75% versus < 25% reduction) was also associated with improved outcome (5‐year event‐free survival 88% versus 61%, P= 0.005). Conclusion:A GGT < 50 and/or GGT reduction of > 75% by 1 year after PSC diagnosis predicts favorable 5‐year outcomes in children. GGT has promise as a potential surrogate endpoint in future clinical trials for pediatric PSC.

Background/Aims: The standard guideline for the management Helicobacter pylori infection in Korean children is not present until now. In present study, we conducted the questionnaire survey to investigate the real situation of H. pylori eradication in children. Materials and Methods: Questionnaire concerning the indications of H. pylori eradication, the first choice of treatment modality, the decision method of eradication result, experience of eradication failure, the second choice of treatment modality was sent to doctors who are members of the Korean Society for Pediatric Gastorenterology, Hepatology, and Nutrition. Results: A total of 28 doctors (90.3%) answered the questionnaires among 31 doctors. The most common indication for eradication of H. pylori was peptic ulcer (n=24) followed by chronic abdominal pain (n=17) and positive family history of gastric cancer (n=12). The most common choice of first-line eradication therapy was omeprazole, amoxicillin, clarithromycin triple therapy (n=21) and followed by bismuth subsalicylate, amoxicillin, metronidazole, clarithromycin quadruple therapy (n=7). The results of treatment were judged by C¹³-urea breath test after 2 months later in 19 doctors (67.8%). Twenty four (85.7%) out of 28 doctors had experienced treatment failure. The most common second-line therapy was the sequential therapy (58.3%, 14 doctors among 24). Conclusions: This was the first study for the survey of the treatment of H. pylori infection to Korean pediatricians. The results of this study showed that most pediatric gastroenterologists used to treat H. pylori infection according to the textbook and the common use of bismuth-based quadruple therapy for the first-line treatment was notable.

Because of the recent increase in the demand for fresh produce, contamination of raw food products has become an issue. Foodborne diseases are frequently caused by the infection of leguminous plants by human bacterial pathogens. Moreover, contamination by Vibrio cholerae, closely related with Vibrio vulnificus, has been reported in plants and vegetables. Here, we investigated the possibility of Vibrio vulnificus 96-11-17M, an opportunistic human pathogen, to infect and colonize Arabidopsis thaliana plants, resulting in typical disease symptoms at 5 and 7 days post-inoculation in vitro and in planta under artificial and favorable conditions, respectively. RNA-Seq analysis revealed 5,360, 4,204, 4,916 and 3,741 differentially expressed genes (DEGs) at 12, 24, 48 and 72 h post-inoculation, respectively, compared with the 0 h time point. Gene Ontology analysis revealed that these DEGs act in pathways responsive to chemical and hormone stimuli and plant defense. The expression of genes involved in salicylic acid (SA)-, jasmonic acid (JA)- and ethylene (ET)-dependent pathways was altered following V. vulnificus inoculation. Genetic analyses of Arabidopsis mutant lines verified that common pathogen-associated molecular pattern (PAMP) receptors perceive the V. vulnificus infection, thus activating JA and ET signaling pathways. Our data indicate that the human bacterial pathogen V. vulnificus 96-11-17M modulates defense-related genes and host defense machinery in Arabidopsis thaliana under favorable conditions.

Phylogenetic methods unearth evolutionary history when supported by three starting points of reason: (1) the continuity axiom begs the existence of a “model” of evolutionary change, (2) the singularity axiom defines the historical ground plan (phylogeny) in which biological entities (taxa) evolve, and (3) the memory axiom demands identification of biological attributes (characters) with historical information. Axiom consequences are interlinked, making the retrodiction enterprise an endeavor of reciprocal fulfillment. In particular, establishing direction of evolutionary change (character polarization) roots phylogenies and enables testing the existence of historical memory (homology). Unfortunately, rooting phylogenies, especially the “tree of life,” generally follow narratives instead of integrating empirical and theoretical knowledge of retrodictive exploration. This stems mostly from a focus on molecular sequence analysis and uncertainties about rooting methods. Here, we review available rooting criteria, highlighting the need to minimize both ad hoc and auxiliary assumptions, especially argumentative ad hocness. We show that while the outgroup comparison method has been widely adopted, the generality criterion of nesting and additive phylogenetic change embodied in Weston rule offers the most powerful rooting approach. We also propose a change of focus, from phylogenies that describe the evolution of biological systems to those that describe the evolution of parts of those systems. This weakens violation of character independence, helps formalize the generality criterion of rooting, and provides new ways to study the problem of evolution.

MPV17-related hepatocerebral mitochondrial DNA depletion syndrome (MDS) is a very rare condition, and only a few cases have been reported in East Asian countries. Here, we describe four Korean children affected by hepatocerebral MDS. The DGUOK, POLG1, and MPV17 genes were analyzed, and all patients had MPV17 mutations.

Viruses can be classified into archaeoviruses, bacterioviruses, and eukaryoviruses according to the taxonomy of the infected host. The host-constrained perception of viruses implies preference of genetic exchange between viruses and cellular organisms of their host superkingdoms and viral origins from host cells either via escape or reduction. However, viruses frequently establish non-lytic interactions with organisms and endogenize into the genomes of bacterial endosymbionts that reside in eukaryotic cells. Such interactions create opportunities for genetic exchange between viruses and organisms of non-host superkingdoms. Here, we take an atypical approach to revisit virus-cell interactions by first identifying protein fold structures in the proteomes of archaeoviruses, bacterioviruses, and eukaryoviruses and second by tracing their spread in the proteomes of superkingdoms Archaea, Bacteria, and Eukarya. The exercise quantified protein structural homologies between viruses and organisms of their host and non-host superkingdoms and revealed likely candidates for virus-to-cell and cell-to-virus gene transfers. Unexpected lifestyle-driven genetic affiliations between bacterioviruses and Eukarya and eukaryoviruses and Bacteria were also predicted in addition to a large cohort of protein folds that were universally shared by viral and cellular proteomes and virus-specific protein folds not detected in cellular proteomes. These protein folds provide unique insights into viral origins and evolution that are generally difficult to recover with traditional sequence alignment-dependent evolutionary analyses owing to the fast mutation rates of viral gene sequences.

Untangling the origin and evolution of viruses remains a challenging proposition. We recently studied the global distribution of protein domain structures in thousands of completely sequenced viral and cellular proteomes with comparative genomics, phylogenomics, and multidimensional scaling methods. A tree of life describing the evolution of proteomes revealed viruses emerging from the base of the tree as a fourth supergroup of life. A tree of domains indicated an early origin of modern viral lineages from ancient cells that co-existed with the cellular ancestors. However, it was recently argued that the rooting of our trees and the basal placement of viruses was artifactually induced by small genome (proteome) size. Here we show that these claims arise from misunderstanding and misinterpretations of cladistic methodology. Trees are reconstructed unrooted, and thus, their topologies cannot be distorted a posteriori by the rooting methodology. Tracing proteome size in trees and multidimensional views of evolutionary relationships as well as tests of leaf stability and exclusion/inclusion of taxa demonstrated that the smallest proteomes were neither attracted toward the root nor caused any topological distortions of the trees. Simulations confirmed that taxa clustering patterns were independent of proteome size and were determined by the presence of known evolutionary relatives in data matrices, highlighting the need for broader taxon sampling in phylogeny reconstruction. Instead, phylogenetic tracings of proteome size revealed a slowdown in innovation of the structural domain vocabulary and four regimes of allometric scaling that reflected a Heaps law. These regimes explained increasing economies of scale in the evolutionary growth and accretion of kernel proteome repertoires of viruses and cellular organisms that resemble growth of human languages with limited vocabulary sizes. Results reconcile dynamic and static views of domain frequency distributions that are consistent with the axiom of spatiotemporal continuity that is tenet of evolutionary thinking.

Inflammatory bowel disease (IBD) is a chronic relapsing disorder of unknown etiology, which is believed to be multifactorial. Recently, the incidence of pediatric IBD has steeply increased in Korea since 2000. Poorly controlled disease activity can result in complications such as intestinal fistulae, abscess, and stricture, as well as growth retardation and delayed puberty in children. Because of a lack of confirmative tests, various diagnostic modalities must be used to diagnose IBD. Onset age, location, behavior, and activity are important in selecting treatments. Monogenic IBD must be excluded among infantile and refractory very-early-onset IBD. Early aggressive therapy using biologics has recently been proposed for peripubertal children to prevent growth failure and malnutrition.

Purpose: To assess the feasibility and effectiveness of transperineal ultrasonography (TPUS) for the evaluation of perianal Crohn’s disease (PCD) in pediatric patients. Methods: Between September 2010 and August 2013, 64 TPUS examinations were performed in 43 patients (34 males and 9 females; mean age ± standard deviation, 13.3 ± 2.4 years; age range, 6–17 years) to evaluate the PCD. The pain severity, location and activity of perianal fistula, the presence of an abscess, and anal canal hyperemia was retrospectively evaluated. Spearman’s rank correlation analysis was performed to assess the relationship between the severity of the pain and the fistula activity, the presence of an abscess, and anal canal hyperemia. Results: All examinations were successfully performed Thirty-nine examinations (60.9%) were performed without any pain experienced by the patient, 19 examinations (29.7%) with mild pain, five examinations (7.8%) with moderate pain, and one examination (1.6%) with severe pain. The pain severity was correlated with the fistula activity (P

The archaeal ancestor scenario (AAS) for the origin of eukaryotes implies the emergence of a new kind of organism from the fusion of ancestral archaeal and bacterial cells. Equipped with this “chimeric” molecular arsenal, the resulting cell would gradually accumulate unique genes and develop the complex molecular machineries and cellular compartments that are hallmarks of modern eukaryotes. In this regard, proteins related to phagocytosis and cell movement should be present in the archaeal ancestor, thus identifying the recently described candidate archaeal phylum “Lokiarchaeota” as resembling a possible candidate ancestor of eukaryotes. Despite its appeal, AAS seems incompatible with the genomic, molecular, and biochemical differences that exist between Archaea and Eukarya. In particular, the distribution of conserved protein domain structures in the proteomes of cellular organisms and viruses appears hard to reconcile with the AAS. In addition, concerns related to taxon and character sampling, presupposing bacterial outgroups in phylogenies, and nonuniform effects of protein domain structure rearrangement and gain/loss in concatenated alignments of protein sequences cast further doubt on AAS-supporting phylogenies. Here, we evaluate AAS against the traditional “three-domain” world of cellular organisms and propose that the discovery of Lokiarchaeota could be better reconciled under the latter view, especially in light of several additional biological and technical considerations.

High-throughput sequencing can produce hundreds of thousands of 16S rRNA sequence reads corresponding to different organisms present in the environmental samples. Typically, analysis of microbial diversity in bioinformatics starts from pre-processing followed by clustering 16S rRNA reads into relatively fewer operational taxonomic units (OTUs). The OTUs are reliable indicators of microbial diversity and greatly accelerate the downstream analysis time. However, existing hierarchical clustering algorithms that are generally more accurate than greedy heuristic algorithms struggle with large sequence datasets. To keep pace with the rapid rise in sequencing data, we present CLUSTOM-CLOUD, which is the first distributed sequence clustering program based on In-Memory Data Grid (IMDG) technology-a distributed data structure to store all data in the main memory of multiple computing nodes. The IMDG technology helps CLUSTOM-CLOUD to enhance both its capability of handling larger datasets and its computational scalability better than its ancestor, CLUSTOM, while maintaining high accuracy. Clustering speed of CLUSTOM-CLOUD was evaluated on published 16S rRNA human microbiome sequence datasets using the small laboratory cluster (10 nodes) and under the Amazon EC2 cloud-computing environments. Under the laboratory environment, it required only ~3 hours to process dataset of size 200 K reads regardless of the complexity of the human microbiome data. In turn, one million reads were processed in approximately 20, 14, and 11 hours when utilizing 20, 30, and 40 nodes on the Amazon EC2 cloud-computing environment. The running time evaluation indicates that CLUSTOM-CLOUD can handle much larger sequence datasets than CLUSTOM and is also a scalable distributed processing system. The comparative accuracy test using 16S rRNA pyrosequences of a mock community shows that CLUSTOM-CLOUD achieves higher accuracy than DOTUR, mothur, ESPRIT-Tree, UCLUST and Swarm. CLUSTOM-CLOUD is written in JAVA and is freely available at http://clustomcloud.kopri.re.kr.

Acinetobacter baumannii, a strictly aerobic, non-fermentative, Gram-negative coccobacillary rod-shaped bacterium, is an opportunistic pathogen in humans. We recently isolated a multidrug-resistant A. baumannii strain KBN10P02143 from the pus sample drawn from a surgical patient in South Korea. We report the complete genome of this strain, which consists of 4,139,396 bp (G + C content, 39.08%) with 3,868 protein-coding genes, 73 tRNAs and six rRNA operons. Identification of the genes related to multidrug resistance from this genome and the discovery of a novel conjugative plasmid will increase our understanding of the pathogenicity associated with this species.

This work clarifies the effect of surface modifications on the corrosion rate of Alloy 690, a nickel-based alloy for steam generator tubes, under the simulated test conditions of the primary water chemistry in nuclear power plants. The surface stress was modified by the shot peening and electropolishing methods. The shot peening treatment was applied using ceramic beads with different intensities by varying the air pressure and projection angle. The corrosion rate was evaluated by gravimetric analysis and the surface was analyzed by scanning electron microscopy (SEM). The corrosion rate of Alloy 690 was evaluated from the influence of the stress state on the metal surface. Based on the observation of the surface after the corrosion test, the oxide composition and its structure were affected by the surface modifications. The corrosion behavior of Alloy 690 was distinguished by the shot peening intensity on the surface, and additional electropolishing was effective at reducing the dissolution of nickel ions from the metal surface.

Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome is characterized by a severe idiosyncratic reaction including rash and fever, often with associated hepatitis, arthralgias, lymph node enlargement, or hematologic abnormalities. The mortality rate is approximately 10%, primarily owing to liver failure with massive or multiple disseminated focal necrosis. Here, we report a case of a 14-year-old girl treated with vancomycin because of a wound infection by methicillin-resistant Staphylococcus aureus, who presented with non-specific symptoms, which progressed to acute liver failure, displaying the hallmarks of DRESS syndrome. With the presence of aggravated hepatic encephalopathy and azotemia, the patient was refractory to medical treatments, she received a living-donor liver transplantation, and a cure was achieved without any sign of recurrence. Vancomycin can be a cause of DRESS syndrome. A high index of suspicion and rapid diagnosis are necessary not to miss this potentially lethal disease.

The study of the origin of diversified life has been plagued by technical and conceptual difficulties, controversy, and apriorism. It is now popularly accepted that the universal tree of life is rooted in the akaryotes and that Archaea and Eukarya are sister groups to each other. However, evolutionary studies have overwhelmingly focused on nucleic acid and protein sequences, which partially fulfill only two of the three main steps of phylogenetic analysis, formulation of realistic evolutionary models, and optimization of tree reconstruction. In the absence of character polarization, that is, the ability to identify ancestral and derived character states, any statement about the rooting of the tree of life should be considered suspect. Here we show that macromolecular structure and a new phylogenetic framework of analysis that focuses on the parts of biological systems instead of the whole provide both deep and reliable phylogenetic signal and enable us to put forth hypotheses of origin. We review over a decade of phylogenomic studies, which mine information in a genomic census of millions of encoded proteins and RNAs. We show how the use of process models of molecular accumulation that comply with Weston’s generality criterion supports a consistent phylogenomic scenario in which the origin of diversified life can be traced back to the early history of Archaea.

The origins of diversified life remain mysterious despite considerable efforts devoted to untangling the roots of the universal tree of life. Here we reconstructed phylogenies that described the evolution of molecular functions and the evolution of species directly from a genomic census of gene ontology (GO) definitions. We sampled 249 free-living genomes spanning organisms in the three superkingdoms of life, Archaea, Bacteria, and Eukarya, and used the abundance of GO terms as molecular characters to produce rooted phylogenetic trees. Results revealed an early thermophilic origin of Archaea that was followed by genome reduction events in microbial superkingdoms. Eukaryal genomes displayed extraordinary functional diversity and were enriched with hundreds of novel molecular activities not detected in the akaryotic microbial cells. Remarkably, the majority of these novel functions appeared quite late in evolution, synchronized with the diversification of the eukaryal superkingdom. The distribution of GO terms in superkingdoms confirms that Archaea appears to be the simplest and most ancient form of cellular life, while Eukarya is the most diverse and recent.

Domains are modules within proteins that can fold and function independently and are evolutionarily conserved. Here we compared the usage and distribution of protein domain families in the free-living proteomes of Archaea, Bacteria and Eukarya and reconstructed species phylogenies while tracing the history of domain emergence and loss in proteomes. We show that both gains and losses of domains occurred frequently during proteome evolution. The rate of domain discovery increased approximately linearly in evolutionary time. Remarkably, gains generally outnumbered losses and the gain-to-loss ratios were much higher in akaryotes compared to eukaryotes. Functional annotations of domain families revealed that both Archaea and Bacteria gained and lost metabolic capabilities during the course of evolution while Eukarya acquired a number of diverse molecular functions including those involved in extracellular processes, immunological mechanisms, and cell regulation. Results also highlighted significant contemporary sharing of informational enzymes between Archaea and Eukarya and metabolic enzymes between Bacteria and Eukarya. Finally, the analysis provided useful insights into the evolution of species. The archaeal superkingdom appeared first in evolution by gradual loss of ancestral domains, bacterial lineages were the first to gain superkingdom-specific domains, and eukaryotes (likely) originated when an expanding proto-eukaryotic stem lineage gained organelles through endosymbiosis of already diversified bacterial lineages. The evolutionary dynamics of domain families in proteomes and the increasing number of domain gains is predicted to redefine the persistence strategies of organisms in superkingdoms, influence the make up of molecular functions, and enhance organismal complexity by the generation of new domain architectures. This dynamics highlights ongoing secondary evolutionary adaptations in akaryotic microbes, especially Archaea.

The recent nucleic acid sequencing revolution driven by shotgun and high-throughput technologies has led to a rapid increase in the number of sequences for microbial communities. The availability of 16S ribosomal RNA (rRNA) gene sequences from a multitude of natural environments now offers a unique opportunity to study microbial diversity and community structure. The large volume of sequencing data however makes it time consuming to assign individual sequences to phylotypes by searching them against public databases. Since ribosomal sequences have diverged across prokaryotic species, they can be grouped into clusters that represent operational taxonomic units. However, available clustering programs suffer from overlap of sequence spaces in adjacent clusters. In natural environments, gene sequences are homogenous within species but divergent between species. This evolutionary constraint results in an uneven distribution of genetic distances of genes in sequence space. To cluster 16S rRNA sequences more accurately, it is therefore essential to select core sequences that are located at the centers of the distributions represented by the genetic distance of sequences in taxonomic units. Based on this idea, we here describe a novel sequence clustering algorithm named CLUSTOM that minimizes the overlaps between adjacent clusters. The performance of this algorithm was evaluated in a comparative exercise with existing programs, using the reference sequences of the SILVA database as well as published pyrosequencing datasets. The test revealed that our algorithm achieves higher accuracy than ESPRIT-Tree and mothur, few of the best clustering algorithms. Results indicate that the concept of an uneven distribution of sequence distances can effectively and successfully cluster 16S rRNA gene sequences. The algorithm of CLUSTOM has been implemented both as a web and as a standalone command line application, which are available at http://clustom.kribb.re.kr.

Purpose: To date, there is no region-specific guideline for pediatric endoscopy training. This study aimed to illustrate the current status of pediatric endoscopy training in Asia-Pacific region and identify opportunities for improvement. Methods: A cross-sectional survey, using a standardized electronic questionnaire, was conducted among medical schools in the Asia-Pacific region in January 2024. Results: A total of 57 medical centers in 12 countries offering formal Pediatric Gastroenterology training programs participated in this regional survey. More than 75% of the centers had an average case load of <10 cases per week for both diagnostic and therapeutic endoscopies. Only 36% of the study programs employed competency-based outcomes for program development, whereas nearly half (48%) used volume-based curricula. Foreign body retrieval, polypectomy, percutaneous endoscopic gastrostomy, and esophageal variceal hemostasis, that is, sclerotherapy or band ligation (endoscopic variceal sclerotherapy and endoscopic variceal ligation), comprised the top four priorities that the trainees should acquire in the autonomous stage (unconscious) of competence. Regarding the learning environment, only 31.5% provided formal hands-on workshops/simulation training. The direct observation of procedural skills was the most commonly used assessment method. The application of a quality assurance (QA) system in both educational and patient care (Pediatric Endoscopy Quality Improvement Network) aspects was present in only 28% and 17% of the centers, respectively. Conclusion: Compared with Western academic societies, the limited availability of cases remains a major concern. To close this gap, simulation and adult endoscopy training are essential. The implementation of reliable and valid assessment tools and QA systems can lead to significant development in future programs. [ABSTRACT FROM AUTHOR]

Purpose: Few studies have reported the prevalence of inflammatory bowel disease unclassified (IBDU) among Korean pediatric IBD (PIBD) population. To address this gap, we used two tertiary centers and nationwide population-based healthcare administrative data to estimate the prevalence of Korean pediatric IBDU at the time of diagnosis. Methods: We identified 136 patients aged 2-17 years with newly diagnosed IBD (94 Crohn's disease [CD] and 42 ulcerative colitis [UC]) from two tertiary centers in Korea between 2005 and 2017. We reclassified these 136 patients using the revised Porto criteria. To estimate the population-based prevalence, we analyzed Korean administrative healthcare data between 2005 and 2016, which revealed 3,650 IBD patients, including 2,538 CD and 1,112 UC. By extrapolating the reclassified results to a population-based dataset, we estimated the prevalence of PIBD subtypes. Results: Among the 94 CD, the original diagnosis remained unchanged in 93 (98.9%), while the diagnosis of one (1.1%) patient was changed to IBDU. Among the 42 UC, the original diagnosis remained unchanged in 13 (31.0%), while the diagnoses in 11 (26.2%), 17 (40.5%), and one (2.4%) patient changed to atypical UC, IBDU, and CD, respectively. The estimated prevalences of CD, UC, atypical UC, and IBDU in the Korean population were 69.5%, 9.4%, 8.0%, and 13.1%, respectively. Conclusion: This study is the first in Korea to estimate the prevalence of pediatric IBDU. This prevalence (13.1%) aligns with findings from Western studies. Large-scale prospective multicenter studies on PIBDU are required to examine the clinical features and outcomes of this condition. [ABSTRACT FROM AUTHOR]