Liver transplantation: current status and novel approaches to liver replacement

Current management of severe homozygous hypercholesterolaemias

PURPOSE OF REVIEW

This review focuses on recent advances in the management of patients with homozygous familial hypercholesterolaemia, autosomal recessive hypercholesterolaemia and familial defective apolipoprotein B.

RECENT FINDINGS

Autosomal recessive hypercholesterolaemia has been described as a 'phenocopy' of homozygous familial hypercholesterolaemia. Although the clinical phenotypes are similar, autosomal recessive hypercholesterolaemia seems to be less severe, more variable within a single family, and more responsive to lipid-lowering drug therapy. The cardiovascular complications of premature atherosclerosis are delayed in some individuals and involvement of the aortic root and valve is less common than in homozygous familial hypercholesterolaemia. Apheresis is still the treatment of choice in homozygous familial hypercholesterolaemia and in autosomal recessive hypercholesterolaemia patients in whom maximal drug therapy does not achieve adequate control. In addition to the profound cholesterol-lowering effects of apheresis, other potentially beneficial phenomena have been documented: improved vascular endothelial function and haemorheology, reduction in lipoprotein (a) and procoagulatory status, and a decrease in adhesion molecules and C-reactive protein.

SUMMARY

Patients with severe homozygous hypercholesterolaemia illustrate the natural history of atherosclerosis within a condensed timeframe. Effective cholesterol-lowering treatment started in early childhood is essential to prevent onset of life-threatening atherosclerotic involvement of the aortic root and valve, and the coronary arteries. Noninvasive methods for regular monitoring of the major sites involved in the atherosclerotic process are necessary in patients with no symptoms or signs of ischaemia. Management of patients with severe homozygous hypercholesterolaemia continues to be a major challenge.

Older age and liver transplantation: a review

Patients older than 60 are undergoing transplantation with increasing frequency. Reports from several transplant centers document that overall short-term patient survival rates in seniors undergoing liver transplantation are comparable to survival rates of younger adults. However, specific subgroups of older patients may not fare as well. Seniors with far-advanced end-stage liver disease are high-risk for liver transplantation and have poor survival rates. In addition, seniors older than 65 have worse outcomes than those who are 60 to 65, and studies have shown increased mortality with increasing age as a continuous variable. On the other hand, the majority of seniors who survive liver transplantation have full or only minimally limited functional status. Preoperative evaluation of older patients for transplantation requires careful screening to exclude cardiopulmonary disease, malignancy, and other diseases of the aged. Paradoxically, seniors may benefit from a senescent immune system, which results in decreased requirements for immunosuppressive drugs, and possibly a lower rate of acute allograft rejection. Despite good overall short-term survival in the elderly, long-term survival may be worse because of an increased rate of long-term complications, such as malignancy and heart disease. In conclusion, although advanced age is a negative risk factor, advanced age alone should not exclude a patient from liver transplantation; however, it mandates thorough pretransplant evaluation and careful long-term follow-up with attention to usual health maintenance issues in the elderly.

Role of cytokine gene polymorphism and hepatic transforming growth factor β1 expression in recurrent hepatitis C after liver transplantation

Recurrent hepatitis C virus (HCV) infection after orthotopic liver transplantation (OLT) is nearly universal. Cytokines play an important role in the immune response to viral infection, and cytokine gene polymorphism affects the overall expression and secretion of cytokines. The objective of this study was to define the relationship between cytokine polymorphism and recurrent hepatitis C after OLT. Blood samples were collected from 36 patients at a mean of 44.6+/-30.4 months after OLT for chronic HCV infection. DNA was extracted from peripheral blood mononuclear cells, and polymerase chain reaction-sequence specific primers (PCR-SSP) analysis was performed on promoter sequences of transforming growth factor beta1 (TGF-beta1), interleukin 6 (IL-6) interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-alpha) and interferon gamma (INF-gamma). Liver biopsies performed at diagnosis of recurrent disease were graded with the Knodell score, and hepatic TGF-beta1 expression was determined semiquantitatively by immunohistochemistry. The gene polymorphism of TGF-beta1 was correlated with its expression on hepatocytes and sinusoids. Polymorphism in all studied cytokine genes was correlated with recurrence, and interval to recurrence (>12 or < or =12 months post-OLT), and clinical (ascites, Child-Pugh score and death), biochemical parameters of recurrent HCV (serum alanine aminotransferase (ALT)), INR, albumin, bilirubin), and virological parameters (HCV genotype and load). Biopsies revealed recurrent HCV in 31 patients (86.1%); in 21 (67.7%), the interval to recurrence was 12 months. There was a statistically significant correlation between TGF-beta1 gene polymorphism, i.e., the genetic ability to produce high levels of TGF-beta1, and the intensity of TGF-beta1 staining on hepatocytes (p=0.003) and sinusoids (p=0.003), and the degree of fibrosis (p=0.02). A borderline correlation was found with the presence of ascites (p=0.007), but not with Child-Pugh score, synthetic liver function tests or HCV genotype and load. The genetic ability to produce low levels of IFN-gamma was correlated with recurrent disease (p=0.015). No such correlation was found for TGF-beta1 gene polymorphism. In conclusion, polymorphism in the TGF-beta1 gene correlates with its in situ hepatic expression in patients with recurrent HCV after liver transplantation. INF-gamma, but not TGF-beta1 gene polymorphism, correlates with early recurrent hepatitis C after transplantation. These findings might help to design preemptive prevention therapy in selected patients at risk.

Liver transplantation for hepatocellular carcinoma: lessons from the first year under the Model of End-Stage Liver Disease (MELD) organ allocation policy

We examined the impact of the Model for End-Stage Liver Disease (MELD) organ allocation scheme on 44 patients with hepatocellular carcinoma (HCC) awaiting orthotopic liver transplantation (OLT) between February 2002 and January 2003, and compared the outcome with 58 patients listed in the 4 years before MELD implementation. Patients undergoing living-donor liver transplantation were excluded. The Kaplan-Meier probabilities for OLT at 3, 6, and up to 8.5 months were 22.5%, 64.0%, and 88.0%, respectively, under MELD versus 17.2%, 24.7%, and 35.8% at 3, 6 and 9 months, respectively, in the pre-MELD group (P =.0006). In Cox regression analysis, non-O blood group (hazard ratio 2.5; P =.047 versus blood group O) and 3 tumor nodules (hazard ratio 5.5; P =.005) were associated with a significantly higher probability for OLT under MELD. The probabilities of dropout were 5.6% at 6 and 8.5 months under MELD versus 7.2% and 37.8% at 6 and 12 months, respectively, in the pre-MELD group (P =.74). The lack of a significant difference in dropout may be due to low dropout rates in the first 6 months in either group. No HCC was found in the explant in 1 patient from each group. In conclusion, the HCC-adjusted MELD system significantly improved the probability of timely OLT, albeit a significant disadvantage for blood group O was evident. Compared with preliminary UNOS data, in which 90% of patients with HCC have received OLT within 3 months, our results reflect the wide regional variation in the impact of MELD.

Role of NADPH oxidase-derived superoxide in reduced size liver ischemia and reperfusion injury

Hepatic resection with concomitant periods of ischemia and reperfusion (I/R) is required to perform reduced size liver transplantation such as split liver or liver donor transplantation. Although great progress has been made using these types of surgeries, there remains substantial risk to both donors and recipients, with a significant number of patients developing liver injury and failure. The objective of this study was to assess the roles of superoxide (O(2)(-)) and tumor necrosis factor-alpha (TNF-alpha) in the pathophysiology of a mouse model of reduced size liver combined with ischemia and reperfusion (RSL+I/R). We found that all male mice subjected to RSL+I/R died within 3-5 days following surgery. Mortality was always preceded by dramatic increases in liver injury and TNF-alpha expression in the absence of neutrophil infiltration. Using a long-lived, polycationic form of human manganese superoxide dismutase (pcMnSOD), NADPH oxidase-deficient mice (gp91(-/-)) or a monoclonal antibody directed against mouse TNF-alpha, we demonstrated that hepatocellular injury (and mortality) were significantly attenuated. In addition, we found that pcMnSOD administration or NADPH deficiency reduced expression of TNF-alpha. Taken together, our data suggest that NADPH oxidase-derived O(2)(-) plays an important role in the pathophysiology of RSL+I/R-induced liver injury via its ability to enhance expression of TNF-alpha. We propose that therapies directed toward scavenging of O(2)(-), inhibiting NADPH oxidase, and/or immuno-neutralizing TNF-alpha may prove useful in limiting the liver injury induced by surgical procedures that require resection and I/R such as split liver or living donor liver transplantation.

Estrogen receptor-alpha, sexual dimorphism and reduced-size liver ischemia and reperfusion injury in mice

Estrogen (E(2)) exerts its effect on target organs principally by interacting with specific estrogen receptors (ER) such as ER-alpha or ER-beta. The role that these E(2) receptors play in mediating the protective effects observed in RSL+I/R induced injury remains to be defined. To study the role of ER-alpha, we anesthetized female and male wild type (wt; C57Bl/6) and ER-alpha-deficient (alphaERKO) mice and subjected them to 70% liver ischemia for 45 min followed by resection of the remaining 30% nonischemic lobes and reperfusion of the ischemic tissue. For some experiments, wt and alphaERKO male mice were injected with E(2). Survival was monitored on a daily basis while liver injury was assessed by quantifying serum alanine aminotransferase (ALT) levels and histopathology. Hepatic eNOS mRNA levels were evaluated using semi-quantitative RT-PCR. Our data showed that untreated females or males treated with E(2) survived RSL+I/R surgery indefinitely whereas all male mice given vehicle died within 3-5 days following surgery. This protective effect was diminished in alphaERKO female mice such that only 40% of alphaERKO females survived 7 d following RSL+I/R. Furthermore, liver injury was significantly higher in alphaERKO females compared with their wt counterparts and similar to those seen in wild type males and alphaERKO males. The protective effect observed in wild type females or E(2) treated males correlated well with increases in hepatic eNOS message whereas both male and female alphaERKO mice exhibited significantly lower levels of eNOS mRNA. We conclude that this protection may in part be due to the E(2)/ER-alpha-mediated activation of eNOS.

Steatosis and hepatitis C virus: mechanisms and significance for hepatic and extrahepatic disease

Nonalcoholic fatty liver disease (NAFLD) and hepatitis C virus (HCV)-related liver disease are common in the general population, but their concurrence is 2- to 3-fold higher than would be expected by chance alone. In patients with chronic HCV infection, steatosis is attributable to a variable combination of the mechanisms considered to play a role in the pathogenesis of NAFLD--insulin resistance in the obese and in the lean subject--along with a direct effect of HCV on hepatic lipid metabolism that leads to triglyceride accumulation through inhibition of export proteins that are required for very low density lipoprotein (VLDL) assembly and secretion. Accumulating evidence suggests that steatosis contributes to the progression of fibrosis in HCV-related disease in a pattern similar to that observed in NAFLD. Potential mechanisms of this effect include the increased sensitivity of steatotic livers to oxidative stress and cytokine-mediated injury. Steatosis-related hepatic insulin resistance may also play a role through the profibrogenic effects of the compensatory hyperinsulinemia and provides a potential explanation for the association between HCV and type 2 diabetes mellitus. Indeed, an appreciation of the importance of fat in HCV has recently led to trials of adjuvant therapy for HCV directed at steatosis-associated disease mechanisms, with encouraging results reported for various modalities, including weight loss and antioxidants. Future therapy should be aimed at exploiting the interactions of HCV with host insulin and lipid metabolism, particularly in nonresponders to standard antiviral schedules.

Influence of flow conditions and matrix coatings on growth and differentiation of three-dimensionally cultured rat hepatocytes

Maintenance of liver-specific function of hepatocytes in culture is still difficult. Improved culture conditions may enhance the cell growth and function of cultured cells. We investigated the effect of three-dimensional culture under flow conditions, and the influence of surface modifications in hepatocyte cultures. Hepatocytes were harvested from Lewis rats. Cells were cultured on three-dimensional polymeric poly-lactic-co-glycolic acid (PLGA) matrices in static culture, or in a pulsatile flow-bioreactor system. Different surface modifications of matrices were investigated: coating with collagen I, collagen IV, laminin, or fibronectin; or uncoated matrix. Hepatocyte numbers, DNA content, and albumin secretion rate were assessed over the observation period. Culture under flow condition significantly enhanced cell numbers. An additional improvement of this effect was observed, when matrix coating was used. Cellular function also showed a significant increase (4- to 5-fold) under flow conditions when compared with static culture. Our data showed that culture under flow conditions improves cell number, and strongly enhances cellular function. Matrix modification by coating with extracellular matrix showed overall an additive stimulatory effect. Our conclusion is that combining three-dimensional culture under flow conditions and using matrix modification significantly improves culture conditions and is therefore attractive for the development of successful culture systems for hepatocytes.

Liver-specific gene expression in cultured human hematopoietic stem cells

Hematopoietic and hepatic stem cells share characteristic markers such as CD34, c-kit, and Thy1. Based on the recent observations that hepatocytes may originate from bone marrow, we investigated the potential of CD34(+) bone marrow cells to differentiate into hepatocytic cells in vitro. CD34(+) and CD34(-) human bone marrow cells were separated by magnetic cell sorting. Cells were cultured on a collagen matrix in a defined medium containing hepatocyte growth factor. Cell count and size were measured by flow cytometry, and reverse transcription polymerase chain reaction was carried out for the liver-specific markers CK-19 and albumin. During cell culture, CD34(+) cells showed an increasing cell number and proliferative activity as assessed by Ki-67 staining. Under the specified culture conditions, CD34(+) cells expressed albumin RNA and CK-19 RNA after 28 days, whereas CD34(-) cells did not show liver-specific gene expression. The results indicate that CD34(+) adult human bone marrow stem cells can differentiate into hepatocytic cells in vitro.

Treatment strategies for hepatitis C: intervention prior to liver transplant, pre-emptively or after established disease

Cirrhosis secondary to chronic hepatitis C virus (HCV) infection accounts for most liver transplants performed in the United States and European transplant centers. Given the high prevalence of HCV infection in the general population, the lack of consistently effective antiviral therapy, and the eventual progression to cirrhosis of a subset of those infected, predictions for the future are that the number of patients in need of transplantation will increase in the coming decade. In addition, viral infection recurs nearly universally leading to the development of chronic HCV in most recipients and progression to cirrhosis after a median of 9 to 12 years in a significant proportion of these recipients.

Validation and refinement of survival models for liver retransplantation

Orthotopic liver retransplantation (re-OLT) is highly controversial. The objectives of this study were to determine the validity of a recently developed United Network for Organ Sharing (UNOS) multivariate model using an independent cohort of patients undergoing re-OLT outside the United States, to determine whether incorporation of other variables that were incomplete in the UNOS registry would provide additional prognostic information, to develop new models combining data sets from both cohorts, and to evaluate the validity of the model for end-stage liver disease (MELD) in patients undergoing re-OLT. Two hundred eighty-one adult patients undergoing re-OLT (between 1986 and 1999) at 6 foreign transplant centers comprised the validation cohort. We found good agreement between actual survival and predicted survival in the validation cohort; 1-year patient survival rates in the low-, intermediate-, and high-risk groups (as assigned by the original UNOS model) were 72%, 68%, and 36%, respectively (P <.0001). In the patients for whom the international normalized ratio (INR) of prothrombin time was available, MELD correlated with outcome following re-OLT; the median MELD scores for patients surviving at least 90 days compared with those dying within 90 days were 20.75 versus 25.9, respectively (P =.004). Utilizing both patient cohorts (n = 979), a new model, based on recipient age, total serum bilirubin, creatinine, and interval to re-OLT, was constructed (whole model chi(2) = 105, P <.0001). Using the c-statistic with 30-day, 90-day, 1-year, and 3-year mortality as the end points, the area under the receiver operating characteristic (ROC) curves for 4 different models were compared. In conclusion, prospective validation and use of these models as adjuncts to clinical decision making in the management of patients being considered for re-OLT are warranted.

Hepatobiliary scintigraphy in liver transplant patients: the "blind end sign" and its differentiation from bile leak

PURPOSE

Hepatobiliary scintigraphy is commonly performed on liver transplant patients to exclude biliary complications such as obstruction or leak. Biliary reconstruction in these patients is performed using either a direct duct-to-duct anastomosis (choledochocholedochostomy) or a biliary-enteric anastomosis (Roux-en-Y hepaticojejunostomy). The authors have observed a finding in scans performed on the latter group of patients that often simulates a bile leak. They postulate this finding to represent retention of activity in the blind end of the Roux limb (the "blind end sign"). The purpose of this study was to determine characteristics of this blind end activity, which may help differentiate it from true bile leaks.

METHODS

Two nuclear medicine physicians reviewed 36 Tc-99m mebrofenin hepatobiliary scans (31 patients). Biliary reconstruction was performed in 25 patients with a Roux-en-Y hepaticojejunostomy, and in 6 patients with a choledochocholedochostomy. Each scan was evaluated regarding whether there was focal, persistent retention of activity in the anastomotic region, and, if so, various features of the activity were noted. Activity was concluded to represent a true bile leak based on subsequent surgical confirmation, and if there was no such confirmation, the activity was concluded to represent blind end retention in patients with Roux-en-Y hepaticojejunostomies.

RESULTS

There were 8 total examples of blind end activity and 3 examples of bile leak activity. Useful discriminators between the 2 types of activity included the following: fluctuation in size and/or intensity with time (8 of 8 blind end cases vs. 0 of 3 bile leak cases); size comparable with bowel (8 of 8 vs. 1 of 3); tubular (4 of 8 vs. 0 of 3), round (4 of 8 vs. 1 of 3), or irregular (0 of 8 vs. 2 of 3) shape; and movement into bowel (3 of 8 vs. 0 of 3). Delayed imaging was performed in 3 cases at 1.5 hours, but was only conclusive in 1 case in which diffuse extravasation was seen consistent with bile leak.

CONCLUSION

Retention of activity in the blind end of the Roux limb in patients with Roux-en-Y hepaticojejunostomies may simulate bile leak, but certain typical features, as well as delayed imaging, may aid in distinguishing the two.

A follow-up analysis of the pattern and predictors of dropout from the waiting list for liver transplantation in patients with hepatocellular carcinoma: implications for the current organ allocation policy

Since our interim report of the intention-to-treat outcome of orthotopic liver transplantation (OLT) for hepatocellular carcinoma (HCC), we have performed a follow-up analysis of an expanded cohort of 70 patients to further assess whether the observed pattern and predictors of dropout are consistent with the rationale behind current HCC-adjusted Model for End Stage Liver Disease (MELD) organ allocation scheme. All except one patient had pretransplantation staging meeting our proposed expanded criteria-a single lesion < or =6.5 cm, or three or fewer lesions none >4.5 cm and total tumor diameter < or =8 cm. Thirty-eight patients received OLT. The cumulative probabilities of dropout at 6, 12, and 18 months were 7.2%, 37.8%, and 55.1%, respectively. The respective dropout probabilities would have been 11.0%, 57.4%, and 68.7% if the United Network for Organ Sharing (UNOS) criteria for exclusion (single lesion < or =5 cm or three or fewer lesions none >3 cm) were applied. Predictors of dropout with either criteria included three tumor nodules and a single lesion >3 cm at initial presentation, whereas preoperative chemoembolization or ablation therapies were associated with a lower risk for dropout only when applying the UNOS criteria for patient exclusion. In the subgroup with two or three lesions or a solitary tumor >3 cm, the cumulative probabilities of dropout were nine-fold higher than those with a single lesion < or =3 cm (P =.004). In conclusion, the low dropout rate in the first 6 months and the differing dropout risks based on tumor characteristics support further refinements in the HCC-adjusted MELD organ allocation scheme.

Changes in the spectrum and risk factors for invasive candidiasis in liver transplant recipients: prospective, multicenter, case-controlled study

BACKGROUND

This study determines whether the spectrum, risk factors, and outcome of invasive candidiasis in liver transplant recipients have changed.

METHODS

Thirty-five consecutive liver transplant recipients with invasive candidiasis were prospectively studied in a case-controlled, multicenter study. One control was matched with the case for duration of hospitalization and the other for antibiotic use so that risk factors unique in liver transplantation could be elicited.

RESULTS

In matched-pair analysis, antibiotic prophylaxis for spontaneous bacterial peritonitis (odds ratio [OR] 8.3, P=0.002), posttransplant dialysis (OR 7.6, P=0.0009), and retransplantation (OR 16.4, P=0.0018) were independently significant predictors of invasive candidiasis. Candida spp. included C. albicans in 65% of patients, C. glabrata in 21%, C. tropicalis in 9%, C. parapsilosis in 3%, and C. guilliermondii in 3%. Patients with C. albicans infections were less likely to have received antifungal prophylaxis than those with non-albicans Candida infections (13.6% vs. 50%, P=0.04). The mortality rate was 36.1% for the cases and 2.8% for the controls (OR 25.0, 95% confidence interval, 6.2-100.5, P=0.0002). Non-albicans Candida infections (P=0.04) and prior antifungal prophylaxis (P=0.05) correlated with poorer outcome in the cases.

CONCLUSIONS

Our study has identified predictors for Candida infections in the current era that have implications relevant for targeting the prophylaxis toward the high-risk patients. Routine use of antifungal prophylaxis warrants concern given the emergence of non-albicans Candida spp. as significant pathogens after liver transplantation and higher mortality in patients with these infections.

Isolation of human hepatocytes from livers rejected for liver transplantation on a national basis: results of a 2-year experience

The offer of liver transplantation to many patients affected by liver failure is limited by organ shortage. Clinical application of human-based liver cell therapies, such as bioartificial liver and hepatocyte transplantation, might support liver transplantation, allowing more patients to be treated and decreasing mortality in the waiting list. The development of a standardized method of hepatocyte isolation is a mainstay for large-scale application of liver cell therapy. The aim of this study is to analyze retrospectively a 2-year experience of human hepatocyte isolation from livers rejected from transplantation at organ harvesting, performed on a national basis in Italy. All the livers judged unsuitable for transplantation were considered for hepatocyte isolation. Macrosteatosis greater than 60% was the most common reason of refusal, followed by nonviral cirrhosis. Fifty-four organs were used. Human hepatocyte isolation resulted in more that 7 million liver cells/g of tissue digested with 73% +/- 14% viability. Steatotic organs gave better results in terms of cell yield than cirrhotic livers. Isolated hepatocytes were able to perform specific liver functions, and evidence of factor IX and albumin messenger RNA (mRNA) production was reported when cells were plated in culture. Modifications of the traditional method of hepatocyte isolation, aimed at reducing ischemia-reperfusion damage and improving post-isolation cell conditions, showed improvements in post-isolation viability. In conclusion, we show that it is possible to use the vast majority of livers not suitable for transplantation on a national basis for human hepatocyte isolation, obtaining a large amount of viable functioning human hepatocytes that might be used for cell transplantation and therapy.

Liver transplantation

Liver transplantation has evolved from an experimental procedure to an acceptable therapy for end-stage liver disease. The major challenges now faced are donor organ shortage, long-term complications related to immunosuppressive therapy, and the prevention and treatment of disease recurrence.

Severe recurrent hepatitis C after liver retransplantation for hepatitis C virus-related graft cirrhosis

An increase in the number of hepatitis C virus (HCV)-infected transplant recipients at need for repeated liver transplantation is anticipated. To date, there is a certain reluctance to accept these patients because of an increased organ shortage, early reports suggesting a poor outcome, and uncertainty regarding the natural history of recurrent hepatitis C in the second graft. The aim of this study is to determine the outcome of patients undergoing retransplantation for HCV-related graft cirrhosis. Of 49 transplant recipients with HCV-related allograft cirrhosis, 31 patients developed decompensation with criteria for retransplantation. Thirteen patients were denied this option. Of the 18 patients accepted, 6 patients died while on the waiting list (5 patients died of graft cirrhosis at a median of 3.2 months of listing), and 12 patients have undergone retransplantation (median, 10 months since HCV cirrhosis). After retransplantation, 8 patients (67%) died at a median of 8 months, and 4 patients (33%) remain alive after 1.9 years of follow-up. Causes and times of death from retransplantation were: surgical complications, n = 3 (perioperative period); HCV cirrhosis of the second graft, n = 2 (at 9 and 54 months); fibrosing cholestatic hepatitis, n = 1 (at 2 years); lymphoproliferative disorder, n = 1 (at 7 months); and endocarditis, n = 1 (at 3.5 years, with underlying cirrhosis). Of the 4 patients alive, fibrosis stages in the last biopsy specimens are stage 1 (n = 1), stage 3 (n = 1), and stage 4 or cirrhosis (n = 1; one patient has not undergone biopsy), despite antiviral therapy. The outcome of retransplantation for HCV cirrhosis of the first graft is very poor because of multiple complications. The severity of recurrent HCV disease in the second graft seems to be related to that observed in the first graft.

Fungal infections in the recipients of solid organ transplantation

The advent of effective antibacterial and antiviral prophylatic and therapeutic strategies has led to the emergence of opportunistic mycoses as a principal cause of infection-related mortality in organ transplant recipients. Candida and Aspergillus species have accounted for most invasive fungal infections in organ transplant recipients. Epidemiologic trends within the last decade, however, are notable for the emergence of mycelial fungi other than Aspergillus as increasingly important pathogens in these patients. This article reviews the epidemiology, clinical manifestations, pathogenetic basis, diagnosis, and management of invasive fungal infections after organ transplantation in context of emerging trends and new developments in these areas.

Oxygenated machine perfusion mitigates surface antigen expression and improves preservation of predamaged donor livers

The aim of the present study was to evaluate the potential benefit of machine preservation with the Belzer MPS or HTK solution, compared to standard cold storage, after procurement of marginal livers from non-heart beating donors in an experimental pilot study. Livers from male Wistar rats (250-300 g bw) were harvested after 60 min of cardiac arrest, flushed via the portal vein and cold stored submerged in HTK for 24 h at 4 degrees C while other organs were subjected to oxygenated machine perfusion with HTK or Belzer's MPS at 5 ml/min at 4 degrees C. Cold perfusion of livers with the non-colloidal HTK was not compromised by the lack of oncotic agents and there was no rise in vascular resistance during the 24 h of machine preservation with HTK or the colloidal Belzer MPS. Viability of the livers was assessed after the cold preservation period by warm reperfusion in vitro. Oxygenated machine perfusion was found to significantly increase viability of the livers vs simple cold storage with respect to portal vascular resistance upon reperfusion, enzyme release as well as functional recovery of oxygen utilization or bile production. Moreover, tissue antigen expression of ICAM-1 or histocompatibility antigen class II could be markedly reduced by oxygenated perfusion preservation as compared to cold storage. It is concluded that predamaged organs should preferably be preserved by oxygenated machine perfusion thus minimizing functional alterations and immunogenicity of the graft. In this setup HTK appeared equally effective as Belzer's MPS for machine preservation.

Sexual dimorphism in reduced-size liver ischemia and reperfusion injury in mice: role of endothelial cell nitric oxide synthase

We have recently reported that female mice are protected to a much greater extent from the injurious effects of reduced-size liver ischemia and reperfusion (RSL+I/R) than are males by an estrogen-dependent mechanism. The objective of this study was to examine the possibility that the protective effect observed in female mice depends on the up-regulation and/or activation of endothelial cell NO synthase (eNOS). Anesthetized female and male wild-type or eNOS-deficient C57BL/6 mice were subjected to 70% liver ischemia for 45 min followed by resection of the remaining 30% nonischemic lobes and reperfusion of ischemic tissue. Survival was monitored daily, whereas liver injury was quantified by using serum alanine aminotransferase determinations and histopathology. Hepatic eNOS mRNA, protein, and enzymatic activity were determined in male and female mice subjected to RSL+I/R. We found that liver injury was reduced and survival increased in female mice compared with males. This protective effect correlated with significant increases in hepatic eNOS message levels and enzyme activity but not protein expression compared with males subjected to the surgery. Furthermore, N(omega)-nitro-L-arginine methyl ester-treated or eNOS-deficient female mice responded to RSL+I/R with dramatic increases in liver injury and 100% mortality within 2 days of surgery. Finally, we found that pravastatin pretreatment significantly attenuated hepatocellular injury and increased survival of male mice, which was associated with enhanced expression of eNOS message. We conclude that the protective effect afforded female mice is due to the activation of hepatic eNOS activity and enhanced NO production.

Transfer of the interleukin-1 receptor antagonist gene into rat liver abrogates hepatic ischemia-reperfusion injury

BACKGROUND

The anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1Ra) is known to reduce hepatic ischemia-reperfusion injury. Therefore, we wished to examine the effect of IL-1Ra gene delivery into the rat liver on hepatic ischemia-reperfusion injury.

METHODS

IL-1Ra cDNA was delivered into the rat liver by a single injection of the transgene vector into the portal vein using either the plasmid-cationic liposome or the recombinant adenoviral vector. At 24 hours after the gene delivery, rats were subjected to partial liver ischemia for 90 minutes followed by reperfusion. Liver tissue and serum samples were taken at 180 minutes of reperfusion, and the degree of the liver injury as well as the expression level of pro-inflammatory cytokines in the serum and tissue were investigated. In addition, we assessed the effect of IL-1Ra gene delivery on the 7-day survival rate when the nonischemic liver lobe was partially excised immediately following reperfusion.

RESULTS

In both cases of delivery methods, gene transfer of IL-1Ra resulted in significant elevation of serum IL-1Ra concentration, which reached maximal levels at 24 hours following the delivery. However, the highest serum concentration with the adenoviral vector was 1,000-fold of that in the liposome-treated animals. In the IL-1Ra delivered rats, liver damage, as well as production of pro-inflammatory cytokines, at 180 minutes of reperfusion was significantly reduced in a concentration-dependent manner of the circulating IL-1Ra protein. Rats subjected to the adenoviral vector gene delivery had higher 7-day survival rates compared with control animals.

CONCLUSIONS

IL-1Ra gene delivery into the liver may be of therapeutic use for abrogating hepatic ischemia-reperfusion injury after transplantation.

Evolution of hepatitis C viral quasispecies after liver transplantation

BACKGROUND & AIMS

To determine whether HCV quasispecies diversity correlated positively with liver disease progression after orthotopic liver transplantation (OLT).

METHODS

We studied 11 patients undergoing OLT for HCV-related cirrhosis with recurrent hepatitis C in 2 groups according to the stage of hepatic fibrosis on follow-up. The mild group had stage 1 or 2 fibrosis; the severe group, stage 3 or 4 fibrosis. HCV quasispecies diversity was assessed by cloning and sequencing in pretransplantation and posttransplantation serum samples.

RESULTS

In the mild fibrosis group, intrasample hypervariable region 1 (HVR1) genetic distance and nonsynonymous substitutions increased after OLT, whereas in the severe fibrosis group, these parameters decreased in follow-up. In contrast, intrasample diversity progressed similarly in both groups in the adjacent sequences flanking HVR1. There was an inverse correlation between the stage of hepatic fibrosis and amino acid complexity after OLT. Among all patients, the estimated rate of amino acid change was greater initially and became more constant after 36 months.

CONCLUSIONS

After OLT, a more complex HCV HVR1 quasispecies population was associated with mild disease recurrence. Among those patients with severe recurrent hepatitis C, HCV appeared to be under greater immune pressure. The greatest change in viral amino acid sequences occurred in the first 36 months after OLT.

Syngeneic living-donor liver transplantation without the use of immunosuppression

Transplantation between monozygotic twins has been successfully performed using the kidney, small intestine, and pancreas. Identical HLA matching has enabled these individuals to be transplanted without the need for immunosuppressive medication. Liver transplantation without immunosuppression would lessen the risk of recurrent viral hepatitis and eliminate much of the morbidity associated with long-term use of immunosuppressive medication. Living-donor liver transplantation (LDLT) has been performed with increasing success in recent years without an opportunity arising to use a monozygotic twin as a donor. We report 2 cases of LDLT between identical twins wherein perfect haploidentity has allowed these recipients to be transplanted without the need for immunosuppression. Although HLA matched genotypically, there may be differences in anatomy between donor and recipient. Mild liver chemistry test abnormalities may occur after transplant despite the absence of immunosuppression.

Hepatitis C in the liver transplant recipient: current understanding and treatment

Hepatitis C virus (HCV)-related liver disease is the leading indication for orthotopic liver transplantation worldwide. Recurrent HCV infection as defined by viremia after transplantation is nearly universal, with histologic evidence of recurrent hepatitis present in the majority. Although short-term survival appears to be similar to that in other causes of liver failure, it has recently been demonstrated that approximately 20-30% of HCV-positive patients develop allograft cirrhosis by 5 years. Therefore, it is possible to define disease outcomes within a relatively short period of follow-up. Identification of patients who are likely to develop progressive HCV-related allograft injury is important to optimize results of current antiviral therapy.

Engineering liver therapies for the future

Treatment of liver disease has been greatly improved by the advent and evolution of liver transplantation. However, as demand for donor organs continues to increase beyond their availability, the need for alternative liver therapies is clear. Several approaches including extracorporeal devices, cell transplantation, and tissue-engineered constructs have been proposed as potential adjuncts or even replacements for transplantation. Simultaneously, experience from the liver biology community have provided valuable insight into tissue morphogenesis and in vitro stabilization of the hepatocyte phenotype. The next generation of cellular therapies must therefore consider incorporating cell sources and cellular microenvironments that provide both a large population of cells and strategies to maintain liver-specific functions over extended time frames. As cell-based therapies evolve, their success will require contribution from many diverse disciplines including regenerative medicine, developmental biology, and transplant medicine.

Phase I clinical trial with the AMC-bioartificial liver

Recently a bio-artificial liver (BAL) system has been developed at the Academic Medical Center (AMC) of Amsterdam to bridge patients with acute liver failure (ALF) to orthotopic liver transplantation (OLT). After successful testing of the AMC-BAL in rodents and pigs with ALF, a phase I study in ALF patients waiting for (OLT) was started in Italy. We present the safety outcome of the first 7 patients aged 21-56 years with coma grade III or IV The total AMC-BAL treatment time ranged from 8 to 35 hours. Three patients received 2 treatments with two different BAL's within three days. Six of the 7 patients were successfully bridged to OLT. One patient showed improved liver function after two treatments and did not need OLT. No severe adverse events of the BAL treatment were noted.

CONCLUSION

Treatment of ALF patients with the AMC-BAL is a safe and feasible technique to bridge the waiting time for an adequate liver-graft.

Artificial mimicking of physiological active transport by a membrane co-cultured with two different cells: hepatic origin HepG2 and renal origin PCTL-MDR

We designed a membrane culture unit on which 2 different cell lines were co-cultured to achieve selective and active transport of toxins. Hepatic origin HepG2 and renal origin multidrug-resistant gene-transduced proximal convoluted tubular cell line (PCTL-MDR) were cultured on the opposite sides of an expanded polytetrafluoroethylene membrane. The activity of testosterone hydroxylation by original HepG2 was very low; however, the cytochrome p450 (CYP) 3A4-transduced recombinant HepG2 metabolized the substrate efficiently. Testosterone added into the outer medium was hydrolyzed by HepG2, and the metabolites were preferentially transported to the inner medium by PCTL-MDR. [3H]-digoxin and [14C]-inulin were added to the outer medium; the digoxin was transported from the outer to inner space through the cell monolayer but the inulin was not, suggesting that the membrane actively transported only the substrate of the channel protein, MDR. The cells were irradiated (10 Gy) to prevent a membrane leak due to overgrowth. The irradiation did not induce apoptosis but resulted in long-lasting membrane function without leakage. The membrane co-cultured with hepatic and renal origin cells will enable a novel hemofiltration system with selective and active transport activities.

External validation of a prognostic model for predicting survival of cirrhotic patients with refractory ascites

OBJECTIVE

Cirrhotic patients with refractory ascites (RA) have a poor prognosis, although individual survival varies greatly. A model that could predict survival for patients with RA would be helpful in planning treatment. Moreover, in cases of potential liver transplantation, a model of these characteristics would provide the bases for establishing priorities of organ allocation and the selection of patients for a living donor graft. Recently, we developed a model to predict survival of patients with RA. The aim of this study was to establish its generalizability for predicting the survival of patients with RA.

METHODS

The model was validated by assessing its performance in an external cohort of patients with RA included in a multicenter, randomized, controlled trial that compared large-volume paracentesis and peritoneovenous shunt. The values for actual and model-predicted survival of three risk groups of patients, established according to the model, were compared graphically and by means of the one-sample log-rank test.

RESULTS

The model provided a very good fit to the survival data of the three risk groups in the validation cohort. We also found good agreement between the survival predicted from the model and the observed survival when patients treated with peritoneovenous shunt and with paracentesis were considered separately.

CONCLUSION

Our survival model can be used to predict the survival of patients with RA and may be a useful tool in clinical decision making, especially in deciding priority for liver transplantation.

Influence of marginal donors on liver preservation injury

PURPOSE

The purpose of this study was to assess the accumulated effects of marginal donor quality factors on liver preservation injury (LPI).

METHODS

The most recent 400 consecutive liver transplantations at our institution were reviewed. Marginal liver donor criteria included the following: older than 60 years, an intensive care unit stay under ventilatory support for more than 4 days, a cold ischemia time more than 14 hr, high inotropic drug use, prolonged hypotensive episodes for more than 1 hr and less than 60 mm Hg, a peak serum sodium more than 155 mEq/L, and high levels of bilirubin, alanine transferase, or amino transferase. The type of steatosis (macrovesicular or microvesicular) was quantified in four categories: no steatosis, mild (<30%), moderate (30-60%), and severe (> 60%). LPI was stratified histologically in four levels: no damage, mild, moderate, and severe injury. These variables were included in a logistic regression analysis for prediction of the probability of the appearance of LPI.

RESULTS

Five variables showed an independent influence on LPI: high inotropic drug use (odds ratio [OR]=1.56), donor age (OR=1.017 per year), moderate to severe macrovesicular steatosis (OR=3.63), cold ischemia time (OR=1,109 per hour), and prolonged stay in an intensive care unit (OR=1.79). Severe LPI was present in 32.7% of the grafts from donors without any factor of the model; in 46.8% from donors with one factor (P =0.09); in 66.2% from donors with two factors (P =0.006); and in 78.3% from donors with at last three factors (P =0.002) (global P=0.0001; chi2 =21.8).

CONCLUSIONS

LPI can be potentially predicted based on donor and graft conditions. Accumulation of factors is correlated with an increased effect on LPI.

Reduced use of intensive care after liver transplantation: influence of early extubation

Postoperative ventilation and admission to the intensive care unit (ICU) is the standard of care in liver transplantation and comprises a significant proportion of transplantation costs. Because immediate postoperative extubation has been reported previously in a selected group of liver transplant recipients, we questioned whether this protocol could be extended to a larger group of patients. We also sought to determine the proportion of patients extubated immediately after surgery that could be transferred to the surgical ward without intervening ICU care. Of 147 patients studied in a prospective trial of sequential liver transplant recipients (who were not second-transplant recipients, United Network for Organ Sharing status 1, living donor transplant recipients, or dead before the end of surgery), 13 patients did not meet postsurgical criteria for early extubation and 111 patients were successfully extubated. Eighty-three extubated patients were transferred to the surgical ward after a routine admission to the postoperative care unit. Only 3 patients who were transferred to the surgical ward experienced complications that required a greater intensity of nursing care. A learning curve detected during the 3-year study period showed that attempts to extubate increased from 73% to 96% and triage to the surgical ward increased from 52% to 82% without compromising patient safety. The use of this protocol in our institution resulted in a 1-day reduction in ICU use in 75.5% of study subjects. We therefore conclude that the majority of liver transplant recipients can be extubated safely and admitted to the surgical ward after liver transplantation surgery, thus decreasing the cost associated with ICU care.

Potential impact of in situ liver splitting on the number of available grafts

BACKGROUND

The potential increase in the number of liver grafts gained from systematically using the technique of splitting optimal organs is still unknown. This study investigates the proportion of donors that should be considered for in situ split-liver harvesting according to strict criteria on which a consensus could be reached easily.

METHODS

The records of 407 consecutive donors during a 4-year period in Switzerland were analyzed. Non-heart-beating donors and donors with missing data were excluded, leaving 338 donors as the study population. Liver splitting was considered feasible when the following criteria were met: age> or =14 and < or =50 years; weight> or =45 kg; body mass index< or =26 kg/m2; intensive care stay< or =3 days; mean arterial pressure> or =60 mm Hg; Na< or =160 mmol/L; serum glutamic pyruvic transaminase< or =60 U/L; gamma-glutamyl transpeptidase< or =50 U/L; no steatosis at ultrasonography. Organs from donors> or =70 kg were considered suitable for a split, producing organs for two adults.

RESULTS

Fifty-two (15%) donors fulfilled all the conditions for a split-liver procedure, of whom 29 (8.6%) were donors for 2 adults. The number of donors suitable for splitting increased to 145 (43%) if donors with only one missing criterion were included (77 [23%] for 2 adults).

CONCLUSION

Even if the technique is restricted to optimal donors, splitting could appreciably increase the number of liver grafts. A wider use of the technique could reduce the patient's time on the waiting list and the need for living-donor procedures, and should be encouraged.

Hepatic stem cells

The liver in an adult healthy body maintains a balance between cell gain and cell loss. Though normally proliferatively quiescent, hepatocyte loss such as that caused by partial hepatectomy, uncomplicated by virus infection or inflammation, invokes a rapid regenerative response to restore liver mass. This restoration of moderate cell loss and 'wear and tear' renewal is largely achieved by hepatocyte self-replication. Furthermore, hepatocyte transplants in animals have shown that a certain proportion of hepatocytes can undergo significant clonal expansion, suggesting that hepatocytes themselves are the functional stem cells of the liver. More severe liver injury can activate a potential stem cell compartment located within the intrahepatic biliary tree, giving rise to cords of bipotential so-called oval cells within the lobules that can differentiate into hepatocytes and biliary epithelial cells. A third population of stem cells with hepatic potential resides in the bone marrow; these haematopoietic stem cells can contribute to the albeit low renewal rate of hepatocytes, make a more significant contribution to regeneration, and even completely restore normal function in a murine model of hereditary tyrosinaemia. How these three stem cell populations integrate together to achieve a homeostatic balance is not known. This review focuses on two major aspects of liver stem cell biology: firstly, the identity of the liver stem cells, and secondly, their potential value in the treatment of major liver disease.

Liver preservation with HTK: salutary effect of hypothermic aerobiosis by either gaseous oxygen or machine perfusion

The aim of the present study was to improve the viability of marginal livers from non-heart beating donors upon cold preservation using two different techniques for the provision of tissue aerobiosis. Livers from male Wistar rats (250-300 g bw) were harvested after 60 min of cardiac arrest, flushed via the portal vein with 20 mL of heparinized Ringer's solution and 60 mL of histidine-tryptophan-ketoglutarate (HTK) preservation solution. Control livers were then stored submerged in HTK for 24 h at 4 degrees C while other organs were subjected to aerobic conditions by either insufflation of gaseous oxygen via the venous vascular system of the cold stored organ (VSOP) or pulsatile machine perfusion (MP) with oxygenated HTK at 5 mL/min at 4 degrees C. Superoxide dismutase (SOD) (7500 IU) was added to the last 10 mL of HTK in order to prevent adverse effects of high oxygen tensions at hypothermia. Viability of the livers was assessed upon isolated perfusion in vitro with oxygenated Krebs-Henseleit buffer at constant flow. VSOP or MP, both significantly improved vascular conductivity upon reperfusion as evaluated by portal venous pressure, reduced hepatic enzyme release and led to a rise in hepatic bile production upon reperfusion. Induction of apoptosis was also looked for in tissue homogenates by Western analysis for cleavage of poly(ADP-ribose)polymerase (PARP). Expression of cleaved PARP fragment could be found in reperfused control livers but also, though to a lesser extend, after VSOP or MP. In conclusion, provision of oxygen during cold preservation significantly contributes to improve organ viability upon reperfusion and must be regarded as a useful adjunct for marginal or pre-damaged livers. HTK has been shown for the first time to be also suitable for long-term MP preservation of the liver, but, as inferred from these data, simple insufflation of gaseous O2 may be considered a feasible alternative.

Extracorporeal support of the failing liver

Successes in machine-based extracorporeal support for different organ functions stimulated research in the field of liver support approximately 50 years ago. Initial failure to improve outcome using detoxification methods like dialysis, blood and plasma exchange, or plasmapheresis over sorbents fueled interest in biologic liver support concepts using bioreactors or combined methods. New device configurations, technical improvement of existing detoxification methods, and the refinement in cell culture techniques led to a boost in research on biologic and nonbiologic approaches. Currently, many systems are in the preclinical phase or have entered clinical studies. A number of completed clinical trials have reported a favorable therapeutic impact of the most advanced solutions on the course and outcome of liver failure. Often, findings must be reconfirmed. However, current knowledge suggests that extracorporeal liver support can successfully stabilize liver function, improve the clinical condition of patients, and considerably improve survival in certain subgroups of patients with fulminant hepatic failure and acute decompensation of chronic hepatic failure. Although the initial focus of liver support methods was bridging to liver transplantation, bridging to recovery of organ function and treatment of intractable pruritus are now valuable indications.

Update on the Management of Hepatitis C in Liver Transplant Recipients

Hepatic failure due to hepatitis C is the leading indicator for orthotopic liver transplantation (OLT) in the United States. Unfortunately, recurrent hepatitis C virus infection is essentially universal following orthotopic liver transplantation. Although significant advances have been made in the past decade for the treatment of hepatitis C, a similar level of success has not yet been achieved for most hepatitis C virus-infected liver transplant recipients. In addition, deleterious side effects of the currently available antiviral agents continue to significantly hamper their use. Several recent reports, however, indicate that newer immunosuppressive regimens combined with novel modifications of existing treatment paradigms will likely lead to improved clinical outcomes for the hepatitis C virus-infected liver transplant recipient.

Retransplantation for hepatic allograft failure: prognostic modeling and ethical considerations

Retransplantation already accounts for 10% of all liver transplants performed, and this percentage is likely to increase as patients live long enough to develop graft failure from recurrent disease. Overall, retransplantation is associated with significantly diminished survival and increased costs. This review summarizes the current causes of graft failure after primary liver transplant, prognostic models that can identify the subset of patients for retransplantation with outcomes comparable to primary transplantation, and ethical considerations in this setting, i.e., outcomes-based versus urgency-based approaches.

Trends in invasive fungal infections in liver transplant recipients: correlation with evolution in transplantation practices

BACKGROUND

The incidence of invasive fungal infections, particularly invasive candidiasis, after liver transplantation is strongly influenced by surgical factors and technical complexity of the surgery. We assessed the temporal trends in invasive fungal infections in the context of evolution in liver transplantation practices, technical developments, and other risk factors.

METHODS

Demographic and clinical characteristics of the patients, transplantation-related variables, and rates of infection were longitudinally analyzed over the last 10 years in 190 consecutive liver transplant recipients at our institution. Trends for categorical data were evaluated using the Cochran-Armitage trend test and for continuous variables using analysis of variance with linear contrast.

RESULTS

A decrease in the length of operation (P=0.03), intraoperative transfusion requirements (P=0.0001), cold ischemic time (P<0.0001), use of roux-en-Y biliary anastomosis (P=0.0015), rate of biopsy proven rejection (P<0.0001), and retransplantation (P=0.056) was documented over the successive years. A significant decline in Child-Pugh score (P=0.02) and in the proportion of patients transplanted as UNOS 2a occurred (P=0.0001). Although the incidence of cytomegalovirus infection remained unchanged, a significant increase in the frequency of primary cytomegalovirus infection (P=0.045), and a decrease in cytomegalovirus disease (P=0.0006) was documented. Over the same time period, a significant decrease in the incidence of invasive candidiasis (P=0.015), and an insignificant increase in the rate of invasive aspergillosis (P=0.20) occurred.

CONCLUSION

Notable technical developments in liver transplantation practices and risk profiles of patients have occurred over the decade. These variables may have a role in influencing the evolving trends in invasive fungal infections in liver transplant recipients.

Non-surgical treatment of hepatocellular carcinoma

Primary hepatocellular cancer is a disease with a poor prognosis for which there is little consensus on treatment and a paucity of comparative trials. The coexistence of cancer with cirrhosis complicates treatment, and also confers a high risk for the development of further tumours. Surgery, either by hepatic resection or orthotopic liver transplantation, is only a feasible option in a minority of patients. This article surveys the non-surgical approaches to the treatment of hepatocellular cancers-local ablation techniques, arterial embolization with and without chemotherapy, conventional chemotherapy and hormonal modulation, and targeted and external irradiation.

Selected contribution: Effects of gender on reduced-size liver ischemia and reperfusion injury

Hepatic resection with concomitant periods of ischemia and reperfusion (I/R) is a common occurrence in resectional surgery as well as reduced-size liver transplantation (e.g., split liver or living donor transplantation). However, the I/R induced by these types of surgical manipulations may impair liver regeneration, ultimately leading to liver failure. The objectives of the study were to develop a murine model of reduced-size liver I/R and assess the role of gender in this model of hepatocellular injury. We found that 100% of female mice survived the surgery indefinitely, whereas all male mice had greater initial liver injury and died within 5 days after surgery. The protective effect observed in females appeared to be due to ovarian 17beta-estradiol, as ovariectomy of females or administration of a selective estrogen antagonist to female mice resulted in enhanced liver injury and greater mortality following reduced-size liver I/R. Conversely, 17beta-estradiol-treated male mice exhibited less hepatocellular damage and survived indefinitely. Taken together, these data demonstrate an estrogen-mediated protective pathway(s) that limits or attenuates hepatocellular injury induced by reduced-size liver I/R.

Trends in the epidemiology of opportunistic fungal infections: predisposing factors and the impact of antimicrobial use practices

In the past decade, the frequency of opportunistic fungal infections has increased, and the spectrum of fungal pathogens has changed. The increasing number of susceptible hosts, the introduction of newer modalities for hematopoietic stem cell transplantation, the evolution of organ transplantation practices, the use of novel immunosuppressive agents, and current antimicrobial prophylactic strategies have likely contributed to the changing epidemiology of invasive mycoses. The introduction of azoles more than a decade ago has had a profound impact on curtailing candidal infections. However, a dramatic increase in azole-resistant Candida species and mold infections has been documented. The trends in time of onset, spectrum, and frequency of infections due to invasive molds and opportunistic yeasts are unique for different fungi and vary between subsets of immunocompromised hosts. This review discusses the implications of these trends for guiding judicious use of antimicrobial prophylactics and for unraveling the pathophysiological basis of fungal infections.

Hepatitis B and C in the liver transplant recipient: current understanding and treatment

1. Liver disease related to chronic viral hepatitis is the leading indication for orthotopic liver transplantation (OLT) worldwide. 2. The natural history of hepatitis B virus infection has been dramatically modified, and outcome has improved substantially in the last decade with the use of hepatitis B immunoglobulin and lamivudine. 3. Hepatitis C virus (HCV) recurrence, defined by histological injury, is almost universal, and a subset of patients (20% to 30%) develops allograft cirrhosis by the fifth year post-OLT. 4. Unfortunately, antiviral therapy for hepatitis C post-OLT, even when initiated preemptively before the development of histological recurrence in the first few weeks post-OLT, has failed to alter the natural history of HCV disease recurrence. 5. HCV-related allograft cirrhosis is associated with a high rate of decompensation and mortality.