Incorporating a hemodialysis filter into a commercial normothermic perfusion system to facilitate long-term preservation of human split-livers.

BACKGROUND: Normothermic machine perfusion (NMP) allows for the assessment and resuscitation of ex-vivo human livers prior to transplantation. Commercially available NMP systems are closed circuits that accumulate metabolic waste and cytokines over time, potentially limiting organ preservation times. Dialysis has been proposed as a method to remove waste and excess fluid from such systems. This study aimed to demonstrate the utility of integrating dialysis into a commercially available system by quantifying solute removal. METHODS: A dialysis filter was attached in parallel to a commercially available liver perfusion system. Three livers declined for transplantation were split before undergoing long-term NMP with blood using the modified system. During perfusion, dialysate flow rates were set in the range of 100-600 mL/h for short periods of time. At each flow rate, perfusate and spent dialysate samples were collected and analyzed for solute clearance. RESULTS: The addition of dialysis to a commercial NMP system removed water-soluble waste and helped regulate electrolyte concentrations. Interleukin-6 was successfully removed from the perfusate. Solute clearance was proportional to dialysate flow rate. A guide for our perfusion setup was created for the appropriate selection of dialysis flow rates and duration based on real-time perfusate composition. CONCLUSIONS: Dialysis circuits can efficiently remove waste and regulate perfusate composition, and can be easily incorporated to improve the performance of commercially available systems. Quantification of the effect of dialysis on perfusate composition enables refined dialysis control to optimize electrolyte profiles and avoid the over- or under-correction of key solutes.

Indocyanine green: A novel marker for assessment of graft quality during ex situ normothermic machine perfusion of human livers.

BACKGROUND: Ex situ machine perfusion facilitates the assessment of livers prior to transplantation. However, currently available markers of liver function poorly predict long-term graft function. Indocyanine green (ICG) is a liver-specific dye which, although common in vivo, has never been comprehensively evaluated for the assessment of graft quality during ex situ machine perfusion. This study aimed to assess the utility of ICG in the ex situ setting. METHODS: Using a customized long-term perfusion system, human livers that were not suitable for transplantation were perfused using a red cell-based perfusate. ICG was delivered into the perfusate on days 0, 1, and 4 to assess ICG clearance (spectrophotometric absorbance at 805 nm) and ICG fluorescence (near-infrared camera). RESULTS: Sixteen partial livers were perfused for a median duration of 172 h (7.2 days). On day 0, the median ICG perfusate disappearance rate (PDR) was 7.5%/min and the median ICG retention at 15 min was 9.9%. Grafts that survived ≥7 days had a significantly higher median ICG PDR on day 0 (14.5%/min vs. 6.5%/min, p = 0.005) but not on days 1 or 4. ICG perfusion demonstrated that long-surviving grafts had a significantly lower median red-value (89.8 vs. 118.6, p = 0.011) and a significantly lower median blue-value (12.9 vs. 22.6, p = 0.045) than short-surviving grafts. CONCLUSION: ICG is a novel marker for the assessment of liver function during ex situ normothermic machine perfusion. ICG PDR and quantitative ICG perfusion can distinguish between long- and short-surviving grafts and demonstrate the utility of ICG in the assessment of graft quality prior to transplant.

Outcomes of patients with gallbladder cancer presenting with acute cholecystitis.

The main purpose of this study is to explore the outcomes of patients found to have gallbladder cancer during investigation and diagnosis of acute cholecystitis. The incidence of primary gallbladder cancer co-existing in acute cholecystitis is not well defined in the literature, with anecdotal reports suggesting that they experience worse outcomes than patients with gallbladder cancer found incidentally. METHODS: A retrospective review of all patients with gallbladder cancer managed at the Canberra Health Service between 1998 and May 2022 were identified and reviewed. RESULTS: A total of 65 patients were diagnosed with primary gallbladder cancer during the study period with a mean age of 70.4 years (SD 11.4, range 59-81.8 years) and a female preponderance (74% versus 26%) with a ratio of 2.8. Twenty (31%) patients presented with acute calculus cholecystitis and were found to have a primary gallbladder cancer. This group of patients were older and predominantly female, but the difference was not statistically significant. The overall 5-year survival in the cohort was 20% (stage 1 63%, stage 2 23%, stage 3 16%, and stage 4 0%). There was no statistically significant difference in survival between those who presented with acute cholecystitis vs other presentations. CONCLUSIONS: A third of the patients with gallbladder cancer presented with acute cholecystitis. There was no statistically significant difference in survival in those with bile spillage during cholecystectomy as well those presenting with acute cholecystitis.

Safety of laparoscopic repair of incisional hernias in liver transplant recipients.

INTRODUCTION: Incisional hernia is a common complication following liver transplantation occurring in 5%-34% of patients. Traditionally, open repair was standard due to fear of abdominal adhesions, postoperative complications and lack of experience with laparoscopic techniques. Laparoscopic incisional hernia repair (LIHR) has now become routine in non-transplant patients, with improved postoperative outcomes. In this study, we compared outcomes after laparoscopic and open incisional hernia repair after liver transplantation at a high-volume liver transplant center. METHODS: We performed a retrospective cohort study including all incisional hernia repairs performed on post-liver transplant patients at a major liver transplant center in Australia from 2010 to 2021. Donor, recipient, intraoperative and postoperative variables were collected from the electronic medical record focusing on laparoscopic and open repairs. RESULTS: Between January 2010 and March 2021, 138 patients underwent incisional hernia repair: 40 laparoscopic (29%) and 98 open (71%). No difference in wound infection (2.5% vs. 7.7%, p = .243); wound dehiscence (.00% vs. 2.3%, p = .332) or hernia recurrence (16.3% vs. 23.0%, p = .352) was seen between treatment groups. For larger incisional hernias (>5 cm) we found that a laparoscopic repair reduced length of stay compared to open-repair (3.89 vs. 4.57 days, p = .026). CONCLUSION: Laparoscopic repair of larger incisional hernias reduced postoperative length of hospital stay, whilst potential advantages may include reduced wound complications and hernia recurrence. Importantly, laparoscopic repair did not increase postoperative complication rates and represents a safe technique for repair in this demographic.

Liver splitting during normothermic machine perfusion: a novel method to combine the advantages of both in-situ and ex-vivo techniques.

BACKGROUND: Split liver transplantation permits the transplant of two recipients using a single donor liver. Liver splitting can be performed using the ex-vivo technique (more convenient), or the in-situ technique (shorter cold ischaemic time). We aimed to develop a technique for liver splitting during normothermic machine perfusion which combines the advantages of both techniques and permits graft assessment prior to transplant. METHODS: Human livers declined for transplantation were perfused at 36 °C using a modified-commercial perfusion machine. We developed a six-step method to split whole livers into left lateral segment grafts and extended right grafts. Both partial livers were then perfused on separate machines for individual assessment. RESULTS: Using our technique, 10 whole livers were successfully split during normothermic perfusion resulting in 20 partial grafts. Apart from a single graft which failed due to a technical error, all grafts survived for 24-h after splitting. Survival was demonstrated by lactate clearance, bile production and synthesis of coagulation factors. CONCLUSIONS: Liver splitting during normothermic machine perfusion has the potential to revolutionise split liver transplantation. We describe a novel technique that reliably achieves two grafts from a single donor liver. This raises the possibility of semi-elective transplantation, and sophisticated graft assessment prior to implant.

Is it safe to expand the indications for split liver transplantation in adults? A single-center analysis of 155 in-situ splits.

INTRODUCTION: Split liver transplantation (SLT) enables two recipients to be transplanted using a single donor liver; typically, an adult and a child. Despite equivalent long-term outcomes to whole grafts in selected adults, the use of these grafts in high-risk adult recipients with high model for end-stage liver disease (MELD) scores (≥30), a poor pre-transplant clinical status (ICU or hospital-bound), acute liver failure or retransplantation remains controversial. METHODS: We retrospectively analyzed all deceased donor adult liver transplants performed between July 2002 and November 2019 at a single high-volume center and performed a propensity score-matched analysis. A subgroup analysis was performed to assess utility of these grafts for high-risk recipients. RESULTS: A total of 1090 adult liver transplants were performed, including 155 SLT (14%). Graft survival at 1-, 3- and 5-years were comparable between recipients of split and whole liver grafts (82%, 79% and 74% vs. 86%, 81% and 77%, respectively, log rank P = .537), as was patient survival at 1-, 3- and 5-years. Recipients of split grafts were more likely to have biliary complications and hepatic artery thrombosis, but equivalent long-term survival. Recipients with high MELD scores or a poor pre-transplant clinical status had similar patient and graft survival and complication profiles irrespective of whether they received split or whole grafts. CONCLUSIONS: SLT is an important method for addressing donor shortages and provides comparable long-term outcomes in adult recipients despite an increase in short-term complications. SLT use in high-risk recipients should be considered to allow for sickest-first allocation policies.

Long-term normothermic perfusion of human livers for longer than 12 days.

In this case report, we preserved human livers for up to 13 days under normothermic conditions using a modified commercial perfusion system. Two whole livers were split into two left lateral segment grafts and two extended right grafts without interruption to blood flow and then perfused on separate machines. Not only does this provide the basis for a meaningful study of liver function in the long term, but this could also facilitate the development of a model of ex situ liver regeneration.

Are split liver grafts a suitable option in high-risk liver transplant recipients?

PURPOSE OF REVIEW: To assess the outcomes of split liver transplantation (SLT) in adults and children and evaluate its role in high-risk recipients with a high model for end-stage liver disease (MELD) score, an urgent indication or requiring retransplantation. RECENT FINDINGS: Split liver grafts in general have equivalent long-term survival outcomes to whole grafts despite an increase in biliary complications. Recent success and technical advances have encouraged use of these grafts in high-risk recipients. Split liver grafts can be used successfully in recipients with a high MELD score if there is adequate weight-matching. There are mixed results in urgent indication recipients and for retransplantation such that use in this group of patients remains controversial. SUMMARY: SLT addresses donor shortages by facilitating the transplant of two recipients from the same donor liver. By using careful donor and recipient selection criteria, SLT can achieve equivalent long-term outcomes to whole grafts. These grafts have been used successfully in recipients with a high MELD score, but should be used selectively in urgent indication recipients and for retransplantation.

Abdominal wall complications following renal transplantation in adult recipients - factors associated with interventional management in one unit.

BACKGROUND: Abdominal wall surgical site complications following renal transplantation can be challenging to manage. A sub-group of these recipients will require operative management or advanced wound care such as negative pressure wound therapy (NPWT). The aim of this study was to determine if there were any preoperative, intraoperative and postoperative characteristics in our recipients' cohort which were associated with the requirement for such interventions. METHODS: A retrospective review of medical records was performed for all recipients who sustained abdominal wall complications following renal transplantation at our centre from 2006 to 2016. RESULTS: A total of 64/828 recipients (7.7%) had abdominal wall complications. The mean weight for these patients was 84.9 kg (±16.6 kg) and the mean body mass index was 30.2 (±5.1). Forty-five recipients (70%) had a superficial wound dehiscence while nine (14%) had a complete fascial dehiscence. Operative intervention was required in 13/64 patients (20%) and was more likely to be required in the presence of a fascial dehiscence (9/9, 100%) or a wound collection (10/31, 32%) (p < 0.001, p = 0.021). NPWT was used in 17/64 patients (27%) and was more commonly required in patients with diabetes mellitus (10/24, 42%), a complete fascial dehiscence (5/9, 56%) or evidence of infection (16/44, 36%) (p = 0.039, p = 0.034, p = 0.008). CONCLUSIONS: The requirement for either operative management or the use of NPWT in the management of abdominal wall complications following renal transplantation in our experience was more common in recipients with diabetes mellitus, and in the setting of either complete fascial dehiscence, abdominal wall wound collections and/ or infection.

Return of the cold: How hypothermic oxygenated machine perfusion is changing liver transplantation.

Hypothermic Oxygenated machine PErfusion (HOPE) has recently emerged as a preservation technique which can reduce ischemic injury and improve clinical outcomes following liver transplantation. First developed with the advent solid organ transplantation techniques, hypothermic machine perfusion largely fell out of favour following the development of preservation solutions which can satisfactorily preserve grafts using the cheap and simple method, static cold storage (SCS). However, with an increasing need to develop techniques to reduce graft injury and better utilise marginal and donation after circulatory death (DCD) grafts, HOPE has emerged as a relatively simple and safe technique to optimise clinical outcomes following liver transplantation. Perfusing the graft with cold, acellular, oxygenated perfusate either via the portal vein (PV) alone, or via both the PV and hepatic artery (HA), HOPE is generally commenced for a period of 1-2 h immediately prior to implantation. The technique has been validated by multiple randomised control trials, and pre-clinical evidence suggests HOPE primarily reduces graft injury by decreasing the accumulation of harmful mitochondrial intermediates, and subsequently, the severity of post-reperfusion injury. HOPE can also facilitate real time graft assessment, most notably via the measurement of flavin mononucleotide (FMN) in the perfusate, allowing transplant teams to make better informed clinical decisions prior to transplantation. HOPE may also provide a platform to administer novel therapeutic agents to ex situ organs without risk of systemic side effects. As such, HOPE is uniquely positioned to revolutionise how liver transplantation is approached and facilitate optimised clinical outcomes for liver transplant recipients.

Microbial Contamination During Long-term Ex Vivo Normothermic Machine Perfusion of Human Livers.

BACKGROUND: Normothermic machine perfusion permits the ex vivo preservation of human livers before transplantation. Long-term perfusion for days-to-weeks provides the opportunity for enhanced pretransplant assessment and potential regeneration of organs. However, this risks microbial contamination and infection of the recipient if the organ is transplanted. An understanding of perfusate microbial contamination is required to inform infection control procedures and antimicrobial prophylaxis for this technology. METHODS: We modified a liver perfusion machine for long-term use by adding long-term oxygenators and a dialysis filter. Human livers that were not suitable for transplantation were perfused using a red-cell-based perfusate under aseptic and normothermic conditions (36 °C) with a goal of 14 d. Cephazolin was added to the perfusate for antimicrobial prophylaxis. Perfusate and bile were sampled every 72 h for microbial culture. RESULTS: Eighteen partial human livers (9 left lateral segment grafts and 9 extended right grafts) were perfused using our perfusion system. The median survival was 7.2 d. All organs surviving longer than 7 d (9/18) had negative perfusate cultures at 24 and 48 h. Half of the grafts (9/18) became culture-positive by the end of perfusion. Microbial contaminants included Gram-negative ( Pseudomonas species, Proteus mirabilis, Stenotrophomonas maltophilia ) and Gram-positive bacteria ( Staphylococcus epidermidis , Enterococcus faecalis , and Bacillus species) as well as yeast ( Candida albicans ). CONCLUSIONS: Microbial contamination of perfusate is common during long-term perfusion of human livers with both exogenous and endogenous sources. Enhanced infection control practices and review of targeted antimicrobial prophylaxis are likely to be necessary for translation into the clinical arena.

Harnessing whole human liver ex situ normothermic perfusion for preclinical AAV vector evaluation.

Developing clinically predictive model systems for evaluating gene transfer and gene editing technologies has become increasingly important in the era of personalized medicine. Liver-directed gene therapies present a unique challenge due to the complexity of the human liver. In this work, we describe the application of whole human liver explants in an ex situ normothermic perfusion system to evaluate a set of fourteen natural and bioengineered adeno-associated viral (AAV) vectors directly in human liver, in the presence and absence of neutralizing human sera. Under non-neutralizing conditions, the recently developed AAV variants, AAV-SYD12 and AAV-LK03, emerged as the most functional variants in terms of cellular uptake and transgene expression. However, when assessed in the presence of human plasma containing anti-AAV neutralizing antibodies (NAbs), vectors of human origin, specifically those derived from AAV2/AAV3b, were extensively neutralized, whereas AAV8- derived variants performed efficiently. This study demonstrates the potential of using normothermic liver perfusion as a model for early-stage testing of liver-focused gene therapies. The results offer preliminary insights that could help inform the development of more effective translational strategies.

Bouveret syndrome: two approaches one stone.

Bouveret syndrome is a rare cause of gastric outlet obstruction, a consequence of a large impacted gallstone leading to the formation of a bilioenteric fistula. We present a case of a 79-year-old female who presented with a history of persistent nausea and vomiting. Computed tomography of the abdomen revealed a large gallstone impacted in the second part of the duodenum, complicated by a cholecystoduodenal fistula, leading to gastric outlet obstruction. After nasogastric decompression, the patient underwent an upper gastrointestinal endoscopy and attempted stone retrieval which was unsuccessful. Consequently, she underwent laparotomy, gastrotomy, and extraction of the stone. This case highlights the pitfalls of managing Bouveret syndrome via an endoscopic or an open surgical approach.

IgG4-related sclerosing cholangitis mimicking cholangiocarcinoma.

A man in his 70s presented to the emergency department with painless obstructive jaundice. Initial blood test results show a predominantly cholestatic picture with elevated tumour markers, and imaging findings are concerning for a pancreatic head neoplasm or cholangiocarcinoma with involvement of the entire common bile duct. The patient underwent staging laparoscopy and biopsies including peritoneal washing, but did not identify any features of malignancy. Immunoglobulin G and immunoglobulin G4 testing were subsequently tested and shown to be elevated. The provisional diagnosis of immunoglobulin G4-related sclerosing cholangitis was made, and steroid treatment was empirically started. Treatment with steroids was successful, with complete resolution of symptoms and abnormal imaging findings and near complete resolution of liver function test results after 1 month.

Does an Additional Bile Duct Flush With Low-viscosity Preservation Solution Reduce Bile Duct Injury? A Single-blinded Randomized Clinical Trial.

Biliary complications are a common cause of morbidity after liver transplantation and associated with bile duct injury. To reduce injury, a bile duct flush is performed with high-viscosity preservation solution. It has been suggested that an earlier additional bile duct flush with low-viscosity preservation solution may reduce bile duct injury and biliary complications. This study aimed to investigate whether an earlier additional bile duct flush would reduce bile duct injury or biliary complications. Methods: A randomized trial was conducted using 64 liver grafts from brain dead donors. The control group received a bile duct flush with University of Wisconsin (UW) solution after donor hepatectomy. The intervention group received a bile duct flush using low-viscosity Marshall solution immediately after the onset of cold ischemia and a bile duct flush with University of Wisconsin solution after donor hepatectomy. The primary outcomes were the degree of histological bile duct injury, assessed using the bile duct injury score, and biliary complications within 24 mo of transplant. Results: Bile duct injury scores were not different between the 2 groups. Similar rates of biliary complications occurred in the intervention group (31% [n = 9]) and controls (23% [n = 8]) (P = 0.573). No difference between groups was observed for anastomotic strictures (24% versus 20%, P = 0.766) or nonanastomotic strictures (7% versus 6%, P = 1.00). Conclusions: This is the first randomized trial to investigate an additional bile duct flush using low-viscosity preservation solution during organ procurement. The findings from this study suggest that performing an earlier additional bile duct flush with Marshall solution does not prevent biliary complications and bile duct injury.

Intraoperative Cholangiography in Laparoscopic Cholecystectomy: A Systematic Review and Meta-Analysis.

Background/Objectives: Routine intraoperative cholangiography (IOC) for laparoscopic cholecystectomy (LC) remains controversial. The primary outcomes of this meta-analysis were detection rates of choledocholithiasis, bile duct injuries (BDI), and missed stones in LCs. Methods: A systematic literature search was conducted for the time period January 1, 1990 to July 31, 2022. Some studies reported LCs with conversion to open therefore subgroup analysis in BDI rates was performed for studies which included LCs with and without conversion to open. Studies including primary open cholecystectomies were excluded. I2 statistics were used for heterogeneity analysis. Results: Fourteen studies involving 440659 patients were included. In studies comparing routine and selective IOC policies in LC, 61.1% of patients underwent routine IOC; 38.9% underwent selective IOC. In studies comparing IOC to no IOC in LC, 17.3% of patients had IOC; 82.7% did not. Between the selective and routine IOC groups there was no difference in choledocholithiasis detection rate (odds ratio [OR] = 1.33, p = 0.20, 95% confidence interval [CI] = 0.86 - 2.04), no difference in the rate of missed stones (OR = 1.59, p = 0.58; 95% CI = 0.31 - 8.29), and no difference in BDI rates in selective compared to routine IOC (OR = 0.92, p = 0.92; 95% CI = 0.20 - 4.22). There was no difference in the BDI detection rates in LC with and without IOC (OR = 1.12, p = 0.77; 95% CI = 0.52 - 2.38). Conclusion: This is the largest meta-analysis on this topic to date. There was no statistically significant difference in choledocholithiasis detection, missed stones, or BDI rates in the analyzed groups.

Histological Assessment of the Bile Duct before Liver Transplantation: Does the Bile Duct Injury Score Predict Biliary Strictures?

INTRODUCTION: Histological injury to the biliary tree during organ preservation leads to biliary strictures after liver transplantation. The Bile Duct Injury (BDI) score was developed to assess histological injury and identify the grafts most likely to develop biliary strictures. The BDI score evaluates the bile duct mural stroma, peribiliary vascular plexus (PVP) and deep peribiliary glands (DPGs), which were correlated with post-transplant biliary strictures. However, the BDI score has not been externally validated. The aim of this study was to verify whether the BDI score could predict biliary strictures at our transplant centre. METHODS: Brain-dead donor liver grafts transplanted at a single institution from March 2015 to June 2016 were included in this analysis. Bile duct biopsies were collected immediately before transplantation and assessed for bile duct injury by two blinded pathologists. The primary outcome was the development of clinically significant biliary strictures within 24 months post-transplant. RESULTS: Fifty-seven grafts were included in the study which included 16 biliary strictures (28%). Using the BDI score, mural stromal, PVP and DPG injury did not correlate with biliary strictures including Non-Anastomotic Strictures. Severe inflammation (>50 leucocytes per HPF) was the only histological feature inversely correlated with the primary outcome (absent in the biliary stricture group vs. 41% in the no-stricture group, p = 0.001). CONCLUSIONS: The current study highlights limitations of the histological assessment of bile duct injury. Although all grafts had bile duct injury, only inflammation was associated with biliary strictures. The BDI score was unable to predict post-transplant biliary strictures in our patient population.

Long-term ex situ normothermic perfusion of human split livers for more than 1 week.

Current machine perfusion technology permits livers to be preserved ex situ for short periods to assess viability prior to transplant. Long-term normothermic perfusion of livers is an emerging field with tremendous potential for the assessment, recovery, and modification of organs. In this study, we aimed to develop a long-term model of ex situ perfusion including a surgical split and simultaneous perfusion of both partial organs. Human livers declined for transplantation were perfused using a red blood cell-based perfusate under normothermic conditions (36 °C) and then split and simultaneously perfused on separate machines. Ten human livers were split, resulting in 20 partial livers. The median ex situ viability was 125 h, and the median ex situ survival was 165 h. Long-term survival was demonstrated by lactate clearance, bile production, Factor-V production, and storage of adenosine triphosphate. Here, we report the long-term ex situ perfusion of human livers and demonstrate the ability to split and perfuse these organs using a standardised protocol.

The rare case of oesophago-pericardial fistula secondary to pulmonary tuberculosis.

We report the case of a healthy 35-year-old male with two rare pathologies: pneumopericardium and oesophago-pericardial fistula (OPF) secondary to tuberculosis. Purulent pericarditis and cardiac tamponade are known complications with potential for significant morbidity and mortality. Unfortunately, the symptoms of OPF are non-specific often delaying diagnosis. There is no gold standard for treatment or determinant of when nonsurgical versus surgical approach should be considered. Anti-tuberculous therapy alone is often adequate however an oesophageal stent was utilized in this case to rapidly gain control of the fistula and prevent ongoing contamination from mediastinitis.

Current and Potential Applications for Indocyanine Green in Liver Transplantation.

Indocyanine green (ICG) is a fluorescent dye taken up and almost exclusively cleared by the liver. Measurement of its clearance and visualization of its fluorescence make it suitable for a number of potential applications in liver transplantation including assessment of liver function and real-time assessment of arterial, venous, and biliary structures. ICG clearance can be used to assess donor graft quality before procurement and graft metabolic function before transplant using normothermic ex vivo machine perfusion. ICG clearance in the post-liver transplantation period is able to predict recipient outcomes with correlations to early allograft dysfunction and postoperative complications. After absorbing light in the near-infrared spectrum, ICG also emits fluorescence at 835 nm. This allows the assessment of vascular patency after reconstruction and patterns of liver perfusion in real time. ICG perfusion patterns after revascularization are also associated with posttransplant graft function and survival. ICG fluorescence cholangiography is routine in a number of centers and acts as an aid to identifying the optimal point of bile duct division during living donor liver transplantation to optimize safety for both donor and recipient. In summary, ICG is a versatile tool and has a number of useful applications in the liver transplantation journey including assessment of liver function, perfusion assessment, and cholangiography. Further research and clinical trials are required to validate and standardize its routine use in liver transplantation.