Morbidity analysis of left hepatic trisectionectomy for hepatobiliary disease and live donor

BACKGROUND

Despite remarkable advances in surgical techniques and perioperative management, left hepatic trisectionectomy (LHT) remains a challenging procedure with a somewhat high postoperative morbidity rate compared with less-extensive resections. This study aimed to analyze the short- and long-term outcomes of LHT and identify factors associated with the postoperative morbidity of this technically demanding surgical procedure.

METHODS

The medical records of 53 patients who underwent LHT between June 2005 and October 2019 at a single institution were retrospectively reviewed. The independent prognostic factor of postoperative morbidity was analyzed using the logistic regression model.

RESULTS

Hepatocellular carcinoma was the most common indication for surgery (n = 21), followed by hilar cholangiocarcinoma (n = 14), intrahepatic cholangiocarcinoma (n = 10), and other pathologies (including colorectal liver metastasis, hepatolithiasis, gallbladder cancer, living donor, hemangioma, and multilocular biliary cyst; n = 8). The rates of postoperative morbidities of Clavien-Dindo grade 3 or higher and 90-day mortality were 39.6% and 1.9%, respectively. The 1-, 3-, and 5-year overall survival rates were 81.1%, 61.4%, and 44.6%, respectively. Multivariate analysis revealed that preoperative jaundice [hazard ratio (HR) = 6.15, 95% confidence interval (CI): 1.57-24.17, P = 0.009] and operative time > 420 min (HR = 4.66, 95% CI: 1.27-17.17, P = 0.021) were independent predictors of postoperative morbidity.

CONCLUSIONS

The in-hospital mortality of LHT surgery can be minimalized by a reliable preoperative evaluation of liver function and selection of the dominant anatomic features of right posterior sector, active and appropriate preoperative management for obstructive cholangitis and compensatory hypertrophy of the future remnant posterior sector, and the experience of the surgeon.

Non-Renal Risk Factors for Chronic Kidney Disease in Liver Recipients with Functionally Intact Kidneys at 1 Month

Chronic kidney disease (CKD) is a critical complication of liver transplants, of which non-renal risk factors are not fully understood yet. This study aimed to reveal pre- and post-transplant risk factors for CKD (<60 mL/min/1.73 m2), examining liver recipients with functionally intact kidneys one month after grafting using nationwide cohort data. Baseline risk factors were analyzed with multivariable Cox regression analyses and post-transplant risk factors were investigated with the time-dependent Cox model and matched analyses of time-conditional propensity scores. Of the 2274 recipients with a one-month eGFR ≥ 60 mL/min/1.73 m2, 494 (22.3%) developed CKD during a mean follow-up of 36.6 ± 14.4 months. Age, female sex, lower body mass index, pre-transplant diabetes mellitus, and lower performance status emerged as baseline risk factors for CKD. Time-dependent Cox analyses revealed that recurrent hepatocellular carcinoma (HR = 1.93, 95% CI 1.06−3.53) and infection (HR = 1.44, 95% CI 1.12−1.60) were significant post-transplant risk factors for CKD. Patients who experienced one of those factors showed a significantly higher risk of subsequent CKD compared with the matched controls who lacked these features (p = 0.013 for recurrent hepatocellular carcinoma, and p = 0.003 for infection, respectively). This study clarifies pre- and post-transplant non-renal risk factors, which lead to renal impairment after LT independently from patients’ renal functional reserve.

Pediatric living donor liver transplantation for biliary embryonal rhabdomyosarcoma: a case report of a case showing disease-free survival over 2 years

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.

Recent Improvement in Survival Outcomes and Reappraisal of Prognostic Factors in Pediatric Living Donor Liver Transplantation

Living donor liver transplantation (LDLT) is a significant advancement for the treatment of children with end-stage liver disease given the shortage of deceased donors. The ultimate goal of pediatric LDLT is to achieve complete donor safety and zero recipient mortality. We conducted a retrospective, single-center assessment of the outcomes as well as the clinical factors that may influence graft and patient survival after primary LDLTs performed between 1994 and 2020. A Cox proportional hazards model was used for multivariate analyses. The trends for independent prognostic factors were analyzed according to the following treatment eras: 1, 1994 to 2002; 2, 2003 to 2011; and 3, 2012 to 2020. Primary LDLTs were performed on 287 children during the study period. Biliary atresia (BA; 52%), acute liver failure (ALF; 26%), and monogenic liver disease (11%) were the leading indications. There were 45 graft losses (16%) and 27 patient deaths (7%) in this population during the study period. During era 1 (n = 81), the cumulative survival rates at 1 and 5 years after LDLT were 90.1% and 81.5% for patients and 86.4% and 77.8% for grafts, respectively. During era 2 (n = 113), the corresponding rates were 92.9% and 92% for patients and 89.4% and 86.7% for grafts, respectively. During era 3 (n = 93), the corresponding rates were 100% and 98.6% for patients and 98.9% and 95.4% for grafts, respectively. In the multivariate analyses, primary diagnosis ALF, bloodstream infection, posttransplant lymphoproliferative disease, and chronic rejection were found to be negative prognostic indicators for patient survival. Based on generalized care guidelines and center-oriented experiences, comprehensive advances in appropriate donor selection, refinement of surgical techniques, and meticulous medical management may eventually realize a zero-mortality rate in pediatric LDLT.

Social Hypersensitivity in Bipolar Disorder: An ERP Study

Introduction

Bipolar Disorder (BD) is a disorder in which cognitive function is relatively preserved but social functioning is markedly impaired. Interestingly, studies on BD show that the patients have a strong desire for social rewards. Hypersensitivity to social rewards in BD has not yet been sufficiently examined through experimental methods, although recent studies have pointed out that their reward hypersensitivity is the cause of symptoms and dysfunction.

Objectives

The purpose of this study was to investigate whether patients with BD are hypersensitive to social rewards using the social value capture task.

Methods

Groups of 25 BD and healthy control (HC) each completed the social value attention capture task. This task consists of a practice phase in which associative learning of social rewards with specific stimuli occurs, and a test phase in which the stimuli associated with rewards appear as distractors during the participants performing a selective attention task. We also recorded event-related potential (ERP) in the practice phase in order to investigate BDs’ cortical activity for social reward.

Results

showed significantly decreased accuracy rate and increased reaction time in the high social reward-associated distractor trials of the test phase in the BD compared to the HC. As a result of analysis in ERP components, P3 amplitude for social reward was significantly greater in the BD than the HC.

Conclusions

BD patients exhibit behavioral and physiological hypersensitivity to social rewards that might contribute to social dysfunction.

Disclosure

No significant relationships.

Renal safety of tenofovir disoproxil fumarate and entecavir in liver transplant patients: a nationwide Korean registry study

BACKGROUND AND AIMS

Tenofovir disoproxil fumarate (TDF) and entecavir (ETV) have been recommended after liver transplantation to prevent recurrence of hepatitis B virus infection. Despite its proven efficacy, the renal safety of TDF has not been established in liver transplant recipients. We aimed to compare the effects of TDF and ETV on renal function in liver transplant recipients and to evaluate risk factors for renal dysfunction after liver transplantation.

METHODS

This is a retrospective, observational multicenter study of data from the Korean Organ Transplantation Registry. We included adults who underwent liver transplantation for hepatitis B virus-related complications from April 2014 to December 2017 and received TDF or ETV post-transplantation. Renal dysfunction was defined as an estimated glomerular filtration rate decline by at least 20% from baseline (1 month post-transplantation). Median duration of follow-up was 29 months (interquartile range 19-42).

RESULTS

A total of 804 liver transplant patients were included. The cumulative probability of renal dysfunction was significantly higher in the TDF group than in the ETV group. Multivariable analysis confirmed that TDF was independently associated with an increased risk of renal dysfunction (hazard ratio = 1.47, 95% confidence interval 1.12-1.92; p = 0.005). Independent risk factors for renal dysfunction included older age, worse baseline renal function, and low body mass index. Overall survival rate was significantly lower in patients with renal dysfunction than in those without.

CONCLUSIONS

In this nationwide study, the use of TDF was associated with an increased risk of renal dysfunction, when compared with ETV.

Pure laparoscopic versus open left lateral sectionectomy for hepatocellular carcinoma: A propensity score matching analysis

Backgrounds/Aims

Anatomical resection has superior oncologic outcomes over non-anatomical resection in hepatocellular carcinoma, and left lateral sectionectomy is the simplest and easiest perform anatomical resection procedure among liver resections. The purpose of this study was to find out the safety and feasibility of pure laparoscopic left lateral sectionectomy (PLLLS) for hepatocellular carcinoma.

Methods

Patients who underwent left lateral sectionectomy at a tertiary referral hospital, from August 2007 to April 2019 were enrolled in this retrospective study. After matching the 1 : 3 propensity score, 17 open and 51 pure laparoscopic cases were selected out of 102 cases of total left lateral resection for hepatocellular carcinoma. The group was analyzed in terms of patient demographics, preoperative data, and postoperative outcomes.

Results

During the study period, there was no open conversion case. The mean operative time and complication were not statistically significant different between the two groups. There was no statistically significant difference in disease-free survival and overall survival had no statistical between the two groups. There were no mortality cases, and postoperative hospital stay was significantly shorter in the PLLLS group than in the open left lateral sectionectomy (OLLS) group.

Conclusions

The oncologic outcomes and complication rate were the same in the PLLLS and OLLS groups. However, the hospital stay was shorter in the PLLLS group than in the OLLS group. The present study findings demonstrate that the PLLLS is a safe and feasible procedure for hepatocellular carcinoma.

Safety of Tacrolimus Monotherapy within 12 Months after Liver Transplantation in the Era of Reduced Tacrolimus and Mycophenolate Mofetil: National Registry Study

Tacrolimus monotherapy is accepted as a feasible option during early post-liver transplantation as per current international consensus guidelines. However, its effects in the recent era of reduced tacrolimus (TAC) and mycophenolate mofetil (MMF) remain unclear. Liver recipients who either received TAC monotherapy from the treatment onset or switched from TAC/MMF to TAC-mono within 12 months (TAC-mono group; n = 991) were chronologically matched to patients who continued to receive TAC/MMF (TAC/MMF group; n = 991) at the corresponding time points on time-conditional propensity scores. Outcomes within 12 months after matched time points were compared. Biopsy-proven rejection (TAC/MMF: 3.5% vs. TAC-mono: 2.6%; p = 0.381) and graft failure (0.2% vs. 0.7%; p = 0.082) were similar in both groups. However, the decline in eGFR was 3.1 mL/min/1.73 m² (95% CI: 0.8–5.3) greater at six months (p = 0.008) and 2.4 mL/min/1.73 m² (95% CI: −0.05–4.9) greater at 12 months (p = 0.048) after the matched time points in TAC-mono group than that in TAC/MMF group. TAC trough levels were also higher in the TAC-mono group throughout the study period. TAC-mono within 12 months after liver transplantation is immunologically safe. However, it can increase the required TAC dose and the decline in renal function than that in TAC/MMF combination therapy.

Usability of intraoperative cine-portogram during liver transplantation in young pediatric patients with biliary atresia

BACKGROUND

Pediatric patients with biliary atresia (BA) often present liver cirrhosis-associated portal hypertension and portal vein (PV) hypoplasia. For successful liver transplantation (LT), it is essential to maintain sufficient PV inflow through stenosis-free PV reconstruction with effective ligation of collateral veins. The aim of this study was to assess the clinical usability of intraoperative cine-portogram (IOCP) in young pediatric patients who underwent LT for BA.

METHODS

Medical records of pediatric patients younger than 10 years who underwent primary LT for BA from 2018 to 2020 were reviewed.

RESULTS

A total of 31 patients had undergone Kasai portoenterostomy soon after birth. Their median ages at Kasai portoenterostomy and LT were 1 and 11 months, respectively. Types of LT were living-donor LT in 13, deceased-donor split LT in 15, and deceased-donor whole LT in three patients. PV interposition using an iliac vein homograft was performed in 28 patients receiving partial liver grafts. Side-to-side PV unification venoplasty was performed in three patients undergoing whole LT. All patients underwent ligation of collateral veins. IOCP was performed in 6 (19.4%) patients. Four showed no or faint residual venous collaterals. Collateral vein embolization and endovascular stenting were performed in one patient each. PV insufficiency-free survival rate was 100% at 1 year and 93.8% at 3 years. All patients are currently alive with a median follow-up period of 23 months.

CONCLUSIONS

Intraoperative cine-portogram can be a useful method for identification and embolization of residual portosystemic collateral veins in young pediatric patients who undergo LT for biliary atresia.

Living donor liver transplantation in an infant patient with progressive familial intrahepatic cholestasis along with hepatocellular carcinoma: a case report

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.

Twenty-year longitudinal follow-up after liver transplantation: a single-center experience with 251 consecutive patients

Background

The outcomes of liver transplantation (LT) have improved, but actual 20-year survival data have rarely been presented.

Methods

Longitudinal follow-up data of 20-year LT survivors were retrospectively analyzed. The LT database of our institution was searched to identify patients who underwent primary LT from January 2000 to December 2001. The study cohort of 251 patients was divided into three groups 207 adults who underwent living donor LT (LDLT), 22 adults who underwent deceased donor LT (DDLT), and 22 pediatric patients who underwent LT.

Results

Hepatitis B virus-associated liver cirrhosis and biliary atresia were the most common indications for adult and pediatric LT, respectively. Seven patients required retransplantation, including six who underwent DDLT and one who underwent LDLT. Twenty-two patients died within 3 months after LT and 69 died at later intervals. The overall survival rates at 1, 3, 5, 10, and 20 years were 86.4%, 79.6%, 77.7%, 72.8%, and 62.6%, respectively, in the adult LDLT group; 86.4%, 72.7%, 72.7%, 72.7%, and 68.2%, respectively, in the adult DDLT group; and 86.4%, 86.4%, 81.8%, 81.8%, and 77.3%, respectively, in the pediatric LT group (P=0.545). Common immunosuppressive regimens at 20 years included tacrolimus monotherapy, tacrolimus-mycophenolate dual therapy, cyclosporine monotherapy, and mycophenolate monotherapy.

Conclusions

The present study is the first report of actual 20-year survival data from a Korean high-volume LT center. The graft and patient survival outcomes reflected the early experiences of LT in our institution, with long-term outcomes being similar regardless of graft type and patient age.

Assessment of pathogens and risk factors associated with bloodstream infection in the year after pediatric liver transplantation

BACKGROUND

Bloodstream infection (BSI) is one of the most significantly adverse events that can occur after liver transplantation (LT) in children.

AIM

To analyze the profile of BSI according to the postoperative periods and assess the risk factors after pediatric LT.

METHODS

Clinical data, collected from medical charts of children (n = 378) who underwent primary LT, were retrospectively reviewed. The primary outcome considered was BSI in the first year after LT. Univariate and multivariate analyses were performed to identify risk factors for BSI and respective odds ratios (ORs).

RESULTS

Of the examined patients, 106 (28%) experienced 162 episodes of pathogen-confirmed BSI during the first year after LT. There were 1.53 ± 0.95 episodes per children (mean ± SD) among BSI-complicated patients with a median onset of 0.4 mo post-LT. The most common pathogenic organisms identified were Coagulase-negative staphylococci, followed by Enterococcus spp. and Streptococcus spp. About half (53%) of the BSIs were of unknown origin. Multivariate analysis demonstrated that young age (≤ 1.3 year; OR = 2.1, P = 0.011), growth failure (OR = 2.1, P = 0.045), liver support system (OR = 4.2, P = 0.008), and hospital stay of > 44 d (OR = 2.3, P = 0.002) were independently associated with BSI in the year after LT.

CONCLUSION

BSI was frequently observed in patients after pediatric LT, affecting survival outcomes. The profile of BSI may inform clinical treatment and management in high-risk children after LT.

Gα12 overexpression in hepatocytes by ER stress exacerbates acute liver injury via ROCK1-mediated miR-15a and ALOX12 dysregulation

Rationale: Liver injury must be further characterized to identify novel therapeutic approaches. Endoplasmic reticulum (ER) stress may cause hepatocyte death. Gα₁₂ affects cell viability and its expression varies depending on physiological conditions. This study investigated whether hepatocyte-specific Gα₁₂ overexpression affects acute liver injury, and if so, what the underlying mechanisms and treatment strategies are.

Methods: All experiments were performed using human liver, hepatocytes, and toxicant injury models with Gna12 KO and/or hepatocyte-specific Gα₁₂ overexpression. RNA-sequencing, immunoblotting, immunohistochemistry, reporter assays, and mutation assays were conducted.

Results: Hepatic Gα₁₂ was overexpressed in mice challenged with acetaminophen or other ER stress inducers or in patients with acute liver injury or fibrosis/cirrhosis. Several Gα₁₂ and ER-associated pathways were identified using transcriptomic analysis. Acetaminophen intoxication was characterized by lipid peroxide-induced ferroptosis and was less severe in Gα₁₂-deficient animals and cells. Conversely, Gα₁₂ overexpression in wild-type or Gna12 KO hepatocytes increased hepatotoxicity, promoting lipid peroxidation, inflammation, and ferroptosis. IRE1α-dependent Xbp1 transactivated Gna12. Moreover, Gα₁₂ overexpression enhanced the ability of acetaminophen to induce ALOX12, while downregulating GPX4. The level of miR-15a, herein identified as an ALOX12 inhibitor, was decreased. siRNA knockdown or pharmacological inhibition of ROCK1 prevented dysregulation of ALOX12 and GPX4, rescuing animals from toxicant-induced ferroptosis. These changes or correlations among the targets were confirmed in human liver specimens and datasets of livers exposed to other injurious medications.

Conclusions: Gα₁₂ overexpression by ER stress facilitates hepatocyte ferroptosis through ROCK1-mediated dysregulation of ALOX12, and miR-15a, supporting the concept that inhibition of Gα₁₂ overexpression and/or ROCK1 axis may constitute a promising strategy for acute liver injury.

Salvage living donor liver transplantation versus repeat liver resection for patients with recurrent hepatocellular carcinoma and Child-Pugh class A liver cirrhosis: A propensity score-matched comparison

Following curative liver resection (LR), resectable tumor recurrence in patients with preserved liver function leads to deciding between a repeat LR and a salvage liver transplantation (LT), if a donor's liver is available. This retrospective study compared survival outcomes and recurrence pattern following salvage living donor LT (LDLT) and repeat LR in patients with recurrent hepatocellular carcinoma (HCC). We reviewed the medical records of patients who underwent repeat LR (n = 163) or LDLT (n = 84) for recurrent HCC following curative resections, between January 2005 and December 2017 at a single institution. A 1:1 propensity score matching led to 42 patients per group. Disease-specific and recurrence-free survival were significantly better in the salvage LDLT group than in the repeat LR group (p = .042; HR = 2.40; 95% CI, 0.69-6.00 and p < .001; HR = 4.23; 95% CI, 2.05-8.71, respectively). Despite significant differences in recurrence patterns between the two groups (p = .019), the patient death rates, after recurrence, were similar for both groups (p = .760). This study indicates that salvage LDLT is superior to repeat LR for treating patients with transplantable, intrahepatic HCC recurrence, even in patients with Child-Pugh class A liver cirrhosis.

Diagnostic and prognostic impact of fluorodeoxyglucose-positron emission tomography in diagnosing intraductal papillary neoplasms of the bile duct of the liver

Purpose

Malignant intraductal papillary neoplasm of the bile duct of the liver (IPNB-L) cannot readily be diagnosed through preoperative CT or MRI, but fluorodeoxyglucose (FDG)-PET is a viable alternative. This study evaluated the diagnostic and prognostic impacts of FDG-PET in patients with IPNB-L.

Methods

This was a retrospective single-center study of 101 IPNB-L patients who underwent hepatectomy between 2010 and 2019.

Results

Mean age was 64.4 ± 8.3 years and 76 (75.2%) were male. Anatomical hepatic resection was performed in 99 (98.0%). Concurrent bile duct resection and pancreaticoduodenectomy were performed in 41 (40.6%) and 1 (1.0%), respectively. R0 and R1 resections were performed in 88 (87.1%) and 13 (12.9%), respectively. Low-grade intraepithelial neoplasia and high-grade neoplasia/invasive carcinoma were diagnosed in 19 (18.8%) and 82 (81.2%), respectively. Median FDG-PET maximal standardized uptake values (SUVmax) in low-grade neoplasia and high-grade neoplasia/carcinoma were 3.6 (range, 1.7–7.6) and 5.2 (range, 1.5–18.7) (P = 0.019), respectively. Receiver operating characteristic curve analysis of SUVmax showed area under the curve of 0.674, with sensitivity of 84.2% and specificity of 47.4% at SUVmax cutoff of 3.0. This cutoff had no significant influence on tumor recurrence (P = 0.832) or patient survival (P = 0.996) in patients with IPNB-L of high-grade neoplasia or invasive carcinoma.

Conclusion

IPNB-L is a rare type of biliary neoplasm and encompasses a histological spectrum ranging from benign disease to invasive carcinoma. An FDG-PET SUVmax cutoff of 3.0 appears to effectively discern high-grade neoplasia/carcinoma from low-grade neoplasia, which will assist with the surgical strategy for these cases.

Salvage aorto-hepatic jump graft for hepatic artery thrombosis following living donor liver transplantation: a case report with 10-year follow-up

Hepatic artery thrombosis (HAT) following living donor liver transplantation (LDLT) is a lethal complication. We present the case of a patient who underwent salvage redo hepatic artery reconstruction using an aorto-hepatic jump graft because of HAT following LDLT. A 64-year-old female patient diagnosed with hepatitis C virus-associated liver cirrhosis and hepatocellular carcinoma underwent salvage LDLT using a modified right liver graft. Partial graft infarct was identified at posttransplant day 4, and by day 9, it had spread. Celiac arteriography showed complete occlusion of the graft hepatic artery. We performed redo hepatic artery reconstruction using a fresh iliofemoral artery homograft 10 days after the LDLT operation because such a vessel homograft was available at our institutional tissue bank. The infrarenal aorta was dissected and an iliofemoral artery graft was anastomosed. Soon after hepatic artery revascularization, liver function progressively improved, and the infarct area at the liver graft was reduced. The patient has been doing well for 10 years without any vascular complications. In conclusion, our experience with this case suggests that salvage redo hepatic artery reconstruction using an aorto-hepatic jump graft is a feasible option to treat HAT following LDLT, as in deceased donor liver transplantation.

An analysis of the number of liver and kidney transplantations during COVID-19 pandemic in Korea

Background

The severity of the coronavirus disease 2019 (COVID-19) pandemic has discouraged organ donation. However, the prevalence of COVID-19 in Korea was much lower in comparison to Western countries. With this, the authors decided to determine the real-world impact of COVID-19 on organ donation and transplantation in Korea.

Methods

The number of kidney transplantations (KTs) and liver transplantations (LTs) performed in 2020 were compared with those in 2019 using the Korean Network for Organ Sharing database and Asan Medical Center (AMC) database.

Results

The annual number of deceased donors (DDs) was 450 in 2019 compared to 478 in 2020. Monthly DD number was 37.5±5.9 in 2019 and 39.8±4.4 in 2020 (P=0.284). Annual number of DD kidney transplant (DDKT) was 794 in 2019 and 848 in 2020, and monthly number was 66.1±10.4 in 2019 and 70.7±9.8 in 2020 (P=0.285). The annual number of DDLT was 391 in 2019 and 395 in 2020, and the monthly number was 32.6±5.7, 2019 and 32.9±4.7 in 2020 (P=0.877). The annual number of living donor (LD) KT was 2,293 in 2019 and 1,432 in 2020, and the monthly number was 191.1±19.5 in 2019 and 119.3±11.7 in 2020 (P<0.001). Annual number of living donor LDLT was 1,577 in 2019 and 1,146 in 2020, and monthly number was 131.4±18.1 in 2019 and 95.5±8.0 in 2020 (P<0.001). In the AMC, not all types of KT and LT changed significantly.

Conclusions

The results of this study indicate that the number of DD organ transplantations remained stable in Korea in 2020, but the number of LD organ transplantations was significantly reduced. However, the number of organ transplantations did not change in the AMC.

Tunable asymmetric spin wave excitation and propagation in a magnetic system with two rectangular blocks

Asymmetric spin wave excitation and propagation are key properties to develop spin-based electronics, such as magnetic memory, spin information and logic devices. To date, such nonreciprocal effects cannot be manipulated in a system because of the geometrical magnetic configuration, while large values of asymmetry ratio are achieved. In this study, we suggest a new magnetic system with two blocks, in which the asymmetric intensity ratio can be changed between 0.276 and 1.43 by adjusting the excitation frequency between 7.8 GHz and 9.4 GHz. Because the two blocks have different widths, they have their own spin wave excitation frequency ranges. Indeed, the spin wave intensities in the two blocks, detected by the Brillouin light scattering spectrum, were observed to be frequency-dependent, yielding tuneable asymmetry ratio. Thus, this study provides a new path to enhance the application of spin waves in spin-based electronics.