Global discovery of colonization determinants in the squid symbiont Vibrio fischeri.

Animal epithelial tissue becomes reproducibly colonized by specific environmental bacteria. The bacteria (microbiota) perform critical functions for the host's tissue development, immune system development, and nutrition; yet the processes by which bacterial diversity in the environment is selected to assemble the correct communities in the host are unclear. To understand the molecular determinants of microbiota selection, we examined colonization of a simplified model in which the light organ of Euprymna scolopes squid is colonized exclusively by Vibrio fischeri bacteria. We applied high-throughput insertion sequencing to identify which bacterial genes are required during host colonization. A library of over 41,000 unique transposon insertions was analyzed before and after colonization of 1,500 squid hatchlings. Mutants that were reproducibly depleted following squid colonization represented 380 genes, including 37 that encode known colonization factors. Validation of select mutants in defined competitions against the wild-type strain identified nine mutants that exhibited a reproducible colonization defect. Some of the colonization factors identified included genes predicted to influence copper regulation and secretion. Other mutants exhibited defects in biofilm development, which is required for aggregation in host mucus and initiation of colonization. Biofilm formation in culture and in vivo was abolished in a strain lacking the cytoplasmic chaperone DnaJ, suggesting an important role for protein quality control during the elaboration of bacterial biofilm in the context of an intact host immune system. Overall these data suggest that cellular stress responses and biofilm regulation are critical processes underlying the reproducible colonization of animal hosts by specific microbial symbionts.

Portal Steal Syndrome After Full-Size Deceased Donor Liver Transplantation.

Successful liver transplantation typically results in an immediate decrease in intrahepatic resistance accompanied by an initial increased hepatopedal portal flow. Within a short period of time, the portal hypertension resolves and the variceal shunts involute. However, in situations in which intrahepatic vascular resistance to venous flow remains elevated, significant hepatofugal portal flow may continue through persistent mesenteric shunts. This situation, portal steal, can result in decreased perfusion of the liver graft leading to graft dysfunction, failure, and potentially recipient death. This report details a case and the surrounding literature to highlight appropriate diagnosis and management in these patients.

Changing paradigms in organ preservation and resuscitation.

PURPOSE OF REVIEW: Shortage of donor organs has increased consideration for use of historically excluded grafts. Ex-vivo machine perfusion is an emerging technology that holds the potential for organ resuscitation and reconditioning, potentially increasing the quality and number of organs available for transplantation. This article aims to review the recent advances in machine perfusion and organ preservation solutions. RECENT FINDINGS: Flow and pressure-based machine perfusion has shown improved kidney graft function and survival, especially among expanded criteria donors. Pressure-based machine perfusion is demonstrating promising results in preservation and resuscitation of liver, pancreas, heart, and also lung grafts. August 2014 marked Food and Drug Administration approval of XPS XVIVO Perfusion System (XVIVO Perfusion Inc., Englewood, Colorado, USA), a device for preserving and resuscitating lung allografts initially considered unsuitable for transplantation. Although there is no consensus among physicians about the optimal preservation solution, adding antiapoptotic and cell protective agents to preservation solutions is an interesting research area that offers potential to improve preservation. SUMMARY: Ex-vivo machine perfusion of solid organs is a promising method that provides the opportunity for resuscitation and reconditioning of suboptimal grafts, expanding the number and quality of donor organs.

Anomalous hepatic vein anatomy of left lateral section grafts and customized unification venoplasty for pediatric living donor liver transplantation.

In liver transplantation, a left lateral section (LLS) graft may have an unusual variant left hepatic vein (LHV) anatomy. This study was designed to analyze the incidence of unusual LHV variants and to determine technical methods for effective reconstruction in infant recipients weighing approximately 10 kg or less. The study comprised 3 parts: an LHV variation analysis, a simulation-based design for the technical modification of graft LHV venoplasty, and its clinical application. The LHV anatomy of 300 potential LLS graft donors was classified into 4 types according to the number and location of the hepatic vein openings: (1) a single opening (n = 218 or 72.7%); (2) 2 large adjacent openings (n = 29 or 9.7%); (3) 2 adjacent openings, 1 large and 1 small (n = 34 or 11.3%); and (4) 2 widely spaced openings (n = 19 or 6.3%). Types 2 and 3 required wedged unification venoplasty, and type 4 required additional vein interposition. In a series of 49 cases using LLS grafts, the graft hepatic vein complication rate was 4.5% at 3 years; stenting was necessary for 1 of the 36 type 1 LHV grafts (2.8%) and for 1 of the 13 type 2-4 LHV grafts (7.7%, P = 0.46). A customized interposition-wedged unification venoplasty technique for coping with type 4 vein variations was developed with a simulation-based approach, and it was successfully applied to a 10-month-old male infant receiving an LLS graft with a type 4 LHV. In conclusion, nearly all LHV variations can be effectively managed with customized unification venoplasty. These venoplasty techniques represent beneficial surgical options as part of graft standardization for hepatic vein reconstruction in pediatric living donor liver transplantation.

Draft genome sequence of Vibrio fischeri SR5, a strain isolated from the light organ of the Mediterranean squid Sepiola robusta.

Here, we describe the draft genome sequence of Vibrio fischeri SR5, a squid symbiotic isolate from Sepiola robusta in the Mediterranean Sea. This 4.3-Mbp genome sequence represents the first V. fischeri genome from an S. robusta symbiont and the first from outside the Pacific Ocean.

Anaphylaxis on reperfusion during liver transplantation with coagulopathy.

We present a case in which anaphylaxis on hepatic reperfusion during liver transplantation presented only with hypotension and coagulopathy. There were no cutaneous manifestations or clinical features distinguishing anaphylaxis from postreperfusion syndrome. The recipient regularly consumed seafood, and the organ donor died of anaphylaxis to shellfish. The trigger for anaphylaxis was postulated to be passive transfer of immunoglobulin to the recipient. Anesthesiologists should be notified of donor factors to anticipate anaphylaxis. In this report, we discuss coagulopathy of anaphylaxis and contrast it with disseminated intravascular coagulation.

Patient access to transplantation with an Internet-identified live kidney donor: a survey of U.S. centers.

BACKGROUND: To investigate legitimate transplantation in the United States with an Internet-identified live donor organ, from the patient's perspective, kidney centers were contacted by a researcher posing as an ideal patient and recipient pair seeking to find a center to perform their transplant. METHODS: Responses were obtained with fewer than three phone calls and within less than 2 wk from 100 of 206 UNOS listed centers; 42 pediatric or inactive centers were excluded. RESULTS: A total of 37% (76 of 100) indicated a willingness to consider such a transplant. Eight centers acknowledged having previously performed one, with 100% (8/8) of these indicating that they would still consider future participation. CONCLUSION: Large numbers of Internet-facilitated transplants are not yet being performed in the United States. Because it was possible to elicit a definite answer with 3 or fewer calls at only 49% of centers, we conclude that a significant proportion of centers are not providing easy access to potential donors and recipients. Agreeable centers were clustered geographically, suggesting that multiple factors may be influencing opinions. 100% of agreeable centers required their own standard evaluation of the donor and recipient and indicated that financial exchange between the pair was illegal. We conclude that Internet-based live donor kidney transplants are occurring and have received cautious acceptance at a significant number of legitimate centers. The utility of asking "How did the recipient-donor pair present to our institution" may no longer be relevant. We suggest that every pair seeking access to legitimate transplantation should undergo standardized evaluation with open acknowledgment of the relationship as a modifier.

Probabilistic risk assessment of accidental ABO-incompatible thoracic organ transplantation before and after 2003.

BACKGROUND: A widely reported ABO-mismatch accident in March of 2003 raised concerns about the reliability of the transplantation system. Because this type of failure is rare and significant, we performed a probabilistic risk assessment (PRA) of the donor-recipient matching processes for thoracic organ transplantation. METHODS: A probabilistic risk assessment was performed. RESULTS: The likelihood of accidental incompatible implantation was already low in 2003. The PRA model indicates that the likelihood of such an event was 1.38x10 per donated organ. This estimate correlates closely with the observed rate of these accidents. Based on this model, process changes put in place shortly after the accident reduced the probability to approximately 3.08x10 and changes put in place in October 2004 further reduced the probability to approximately 2.22x10 per organ donated. CONCLUSIONS: The observed and predicted likelihoods of accidental incompatible thoracic organ transplantation are comparable. These likelihoods are several orders of magnitude smaller than other hazards associated with solid organ transplantation. The PRA model indicates that changes that followed the March 2003 accident further reduced the likelihood of accidental incompatible implantation by roughly two orders of magnitude. Quantitative estimates from PRA can be used to assess risks in healthcare and to gauge the impact of system changes on these risks.

Pre-Hepatectomy Assessment of Bile Transporter Expression by Gadoxetic Acid-Enhanced MRI in a Rat Model of Liver Cirrhosis.

BACKGROUND: Gadoxetic acid is a liver-specific intravenous T1 magnetic resonance (MR) contrast agent that is excreted via the hepatobiliary system. We hypothesize that hepatocyte expressions of bile transporters (OATP1 and MRP2) correlate with dynamic profile of Gadoxetic acid enhanced (GE)-MR imaging (MRI). METHODS: Two groups of rats, control (n = 6) and cirrhosis (n = 12), received gadoxetic acid enhanced MRI followed by 70% hepatectomy. The change in MR signal intensity from the baseline before the contrast injection (ΔSI) was analyzed every minute for 30 min. Dynamic signal intensity retention ratio (DSR) was defined as the mean ΔSI of the third 10-minmin period divided by the first 10-minmin period. Real-time PCR was utilized to quantify mRNA expressions. RESULTS: Compared to the control, cirrhosis group demonstrated lower mRNA levels of OATP1 (0.038 ± 0.020 vs. 0.232 ± 0.0979; p = 0.004), MRP2 (0.201 ± 0.084 vs. 0.7567 ± 0.254; p = 0.002), and OATP1/MRP2 mRNA ratio (0.193 ± 0.065 vs. 0.342 ± 0.206; p = 0.032). DSR was higher in the cirrhosis group (0.678 ± 0.554 vs -0.125 ± 0.839; p = 0.033). In the cirrhosis group, there was an inverse correlation between the ratios of OATP1/MRP2 mRNA and DSR (R = -0.709, p = 0.01). CONCLUSION: Bile transporters OATP1/MRP2 mRNA expression ratio in rat liver tissue decreased with DMN-induced liver injury. The expressions of bile transporters correlated with GE-MRI DSR. The GE-MRI DSR has potential utility in qualifying OATP1/MRP2 mRNA expression.

Living donor liver transplantation for pediatric and adult recipients.

Living donor liver transplantation (LDLT) was initially developed to provide suitable liver grafts for pediatric patients with end-stage liver disease. This innovation was remarkable for the prospective nature of its development and the public discussions that resolved the ethical dilemma of removing a portion of a liver from a healthy donor for the benefit of another person. Since its inception, this procedure has been uniformly adopted by most pediatric transplant centers, with excellent results. Unfortunately, liver grafts obtained from this procedure did not provide sufficient hepatocyte mass for use in adult recipients. An adult donor procedure was, therefore, developed to provide larger liver grafts, which were derived from the right lobe of the liver. Much of the driving force for adult-to-adult LDLT has been in countries that lack the health-care infrastructure for obtaining deceased donors or have cultural objections to deceased donor transplantation. In developed countries, the initial growth of adult-to-adult LDLT has been tempered by notable donor complications, including death, but it continues to have an important role in providing life-saving liver grafts for recipients who are unable to compete for deceased donor grafts in the current organ-allocation system.

Ethical tensions in solid organ transplantation: the price of success.

Solid organ transplantation has rapidly developed into the therapy a choice for end-stage organ failure. The expansion of its use has resulted is a large deficiency in organ supply. To address this, the field of organ transplantation has attempted to develop new strategies that would increase the availability of organs for transplant. Some of these strategies include expansion of the donor pool by increasing the number of living donors or using deceased donor organs that may be marginal or "expanded". The intent is to bring life-saving therapy to individuals in need; however, much of this expansion has been brought forward without clear prospective guidelines. This article focuses on the current disparity between organ supply and demand, and how this has impacted the use of living donors and development of the "expanded donor" concept.

Hydroxocobalamin for Vasoplegic Syndrome in Liver Transplantation: Restoration of Blood Pressure Without Vasospasm.

Systemic vasoplegia is common in patients undergoing liver transplantation. In this report, we present a case in which treatment with conventional vasopressors caused peripheral arterial spasm, rendering arterial blood pressure monitoring impossible. Administration of methylene blue resolved the vasospasm; however, concern for toxic dose requirements limited its use. Hydroxocobalamin administration resolved the vasospasm and increased blood pressure without the potential adverse effects seen with methylene blue. This case represents the first report of hydroxocobalamin use in liver transplantation and may represent a new option for the treatment of vasoplegia and the potential vasospasm that may result from traditional vasopressors.

Human Parechovirus as a Cause of Isolated Pediatric Acute Liver Failure.

Among infants, almost half of acute liver failure cases are classified as indeterminate, whereas only a small number of cases show a documented viral infection. We present the first reported case of isolated acute hepatic failure in an infant in the setting of a human parechovirus (HPeV) infection. HPeV also may have been contributory to the posttransplant complication of 2 intussusceptions. This is a 10-month-old girl who presented with only symptoms of fussiness and was noted to have progressive decline in synthetic liver function as well as worsening coagulopathy requiring a liver transplant. The acute liver failure was in the setting of a positive serum RNA HPeV, subtype 3 (HPeV-3), after extensive diagnostic testing with genetic, autoimmune, and infectious causes otherwise negative. After liver transplantation, the postoperative course was complicated by both an ileal-ileal intussusception as well as a jejunal intussusception. Viral testing in pediatric acute liver failure is often performed, but the workup is frequently incomplete. This case report would support more extensive viral testing in this population of patients. In the setting of HPeV, clinicians could be alerted to the possibility of delayed gastrointestinal pathology in the posttransplant phase. Wider use of routine HPeV testing may more clearly define the variable clinical presentations and outcomes.

Solid-organ transplant recipients treated with drotrecogin alfa (activated) for severe sepsis.

Severe sepsis in immunosuppressed recipients of solid-organ transplants is associated with a high mortality. Conventional management of sepsis in this patient population has not specifically attempted to treat the underlying inflammatory or procoagulant responses that contribute to the development of multisystem organ failure. Drotrecogin alfa (activated, human activated protein C) has been shown to be a safe and effective adjuvant in the treatment of severe sepsis; however, experience in recipients of solid-organ transplants has not been addressed. The treatments and outcomes of three solid-organ transplant recipients (liver, kidney, and kidney-pancreas) who experienced episodes of severe sepsis are presented and demonstrate initial success with the use of drotrecogin alfa (activated).

Recipient death during a live donor liver transplantation: who gets the "orphan" graft?

The limited availability of deceased organ donors, prolongation of waiting time, and increasing number of patients dying awaiting transplantation have contributed to the increased use of adult-to-adult living-donor liver transplant. In the event that the intended recipient dies after the donor graft has been procured but before it has been transplanted, what should be done with the graft? A structured, nine-item oral survey of 26 experts in liver transplantation was conducted in June and July 2003. Respondents were selected primarily because of their extensive experience with liver transplantation, especially adult-to-adult living-donor transplant. All respondents said the surgical team should try to use the available graft for another recipient. Twenty-one respondents believed consent from the donor or the donor's family was required for allocation, whereas 19% believed consent desirable but not required. Nine respondents recommended an allocation organization place the graft, whereas 17 respondents recommended placement within the donor hospital. Two of the respondents had previously encountered this situation, whereas four had experienced an intraoperative recipient death before procurement of a live donor graft. On the basis of the responses, we offer the following recommendations for handling orphan liver grafts: (1) obtain predonation informed consent from all donors that indicates what the donor would want to have done with the "orphan graft" in all cases of living-donor liver transplantation; (2) avoid the premature removal of the donor graft until the recipient hepatectomy and survival are likely; (3) if a live donor graft has been procured and cannot be transplanted into the intended recipient, and if informed consent has been obtained before the donor operation, the organ should be reallocated without delay to minimize cold ischemia time and maximize the utility of the graft.

Initial experience with the modified extracorporeal liver-assist device for patients with fulminant hepatic failure: system modifications and clinical impact.

BACKGROUND: The need to find a safe, effective liver support system for patients with fulminant hepatic failure (FHF) continues to be unmet. A system using immortalized human hepatocytes was originally developed in the early 1990s. A modified version of the initial extracorporeal liver-assist device (ELAD) was recently placed into an initial clinical trial at the University of Chicago. The goal of this study was to determine the safety profile of the device at one center before broadening the study to other sites. METHODS: Patients who were diagnosed with FHF and admitted to the University of Chicago were eligible for the ELAD study. Informed consent was obtained, and patients received continuous ELAD therapy until and throughout transplantation. Data were prospectively collected and subsequently analyzed. RESULTS: Five patients were treated with the device. All patients successfully underwent transplantation. Four of the five patients survived to the 30-day endpoint of the study. There were no biomechanical problems identified. The patients' hemodynamic conditions did not deteriorate during treatment. The adult patients' clinical courses appeared to stabilize while connected to the ELAD (mean arterial pressure range 80-97, mean 88.6; cerebral perfusion pressure range 62-88, mean 76.5). Patient 4 experienced remarkable improvement during ELAD therapy: elimination of phenylephrine, reduction of dopamine from 20 microg/min to 5 microg/min, and reduction of respiratory support from 100% O2, 10 cm positive end-expiratory pressure to 60% O2, and 5 cm H2O positive end-expiratory pressure. The device continued to be metabolically active throughout the study period as documented by oxygen use (mean O2 change from sampling port before cartridge to sampling port after cartridge for all patients treated = 55 mm Hg). CONCLUSIONS: The patients tolerated treatment with the ELAD well. There were no unanticipated safety issues. The cells in the cartridges were metabolically active. All patients successfully underwent transplantation. The results from this single-institution experience indicates that larger randomized multicenter trials should proceed.

Advances in pediatric liver transplantation: continuous monitoring of portal venous and hepatic artery flow with an implantable Doppler probe.

BACKGROUND: Acute vascular thrombosis is a dreaded complication in solid organ transplantation. Pediatric liver transplantation is associated with a high incidence of hepatic artery thrombosis. Graft salvage is dependent upon early recognition and correction of the thrombosis. Current methods of surveillance for vascular thrombosis lack early detection. METHODS: Four consecutive pediatric liver transplantations were performed using the implantable Doppler probe to monitor the patency of the hepatic artery and the portal vein during the early postoperative period. RESULTS: The implantable Doppler probes provided reliable monitoring of vascular patency. Early detection of hepatic artery thrombosis, with subsequent correction and graft salvage, was achieved with the use of the implantable Doppler probe. CONCLUSIONS: The implantable Doppler probe provides real-time surveillance of vascular patency for up to 7 days in the postoperative period. Signal quality and character was easily assessed by physician and nursing staff and reliably reflected intravascular flow.