Machine perfusion in abdominal organ transplantation: Current use in the Netherlands

Scarcity of donor organs and the increment in patients awaiting a transplant increased the use of organs from expanded criteria donors or donation after circulatory death. Due to the suboptimal outcomes of these donor organs, there is an increased interest in better preservation methods, such as ex vivo machine perfusion or abdominal regional perfusion to improve outcomes. This state-of-the-art review aims to discuss the available types of perfusion techniques, its potential benefits and the available evidence in kidney, liver and pancreas transplantation. Additionally, translational steps from animal models towards clinical studies will be described, as well as its application to clinical practice, with the focus on the Netherlands. Despite the lack of evidence from randomized controlled trials, currently available data suggest especially beneficial effects of normothermic regional perfusion on biliary complications and ischemic cholangiopathy after liver transplantation. For ex vivo machine perfusion in kidney transplantation, hypothermic machine perfusion has proven to be beneficial over static cold storage in a randomized controlled trial, while normothermic machine perfusion is currently under investigation. For ex vivo machine perfusion in liver transplantation, normothermic machine perfusion has proven to reduce discard rates and early allograft dysfunction. In response to clinical studies, hypothermic machine perfusion for deceased donor kidneys has already been implemented as standard of care in the Netherlands.

Hydroxylated collagen peptide in urine as biomarker for detecting colorectal liver metastases

The clinical efficacy of carcinoembryonic antigen (CEA) as a marker of colorectal liver metastasis is limited, motivating a search for new biomarkers. Recently, urine proteomic analysis revealed AGPP(-OH)GEAGKP(-OH)GEQGVP(-OH)GDLGAP(-OH)GP (AGP), a promising peptide for this application. This study aimed to determine whether combining urine AGP testing with serum CEA analyses improves the sensitivity of detecting colorectal liver metastases. Urine samples from 100 patients with CRLM were collected prospectively and compared to three control groups: healthy kidney donors, patients who were relapse-free for 24 months after curative CRLM surgery, and primary colorectal cancer patients. A stable isotope labeled peptide standard was used to quantify the abundance of AGP in urine samples by selective reaction monitoring. Combined testing of urine AGP levels and serum CEA levels revealed a significantly increased sensitivity compared to CEA alone (85% vs. 68%, P<0.001; specificity 84% and 91%, respectively). No correlation was found between CEA and AGP-positive test results within individual patients (r(2) = 0.08). Urine AGP testing was negative in the three control groups. These results indicate that collagen-derived urine AGP peptide with a specific hydroxylation pattern combined with serum CEA levels may significantly improve the detection of colorectal liver metastases in patients at risk.

Hepatic steatosis is not always a contraindication for cadaveric liver transplantation

BACKGROUND

Macrovesicular steatosis is assumed to be an important risk factor for early allograft dysfunction (EAD) after orthotopic liver transplantation (OLT).

AIM

To evaluate the impact of steatosis in combination with other risk factors on the outcome of OLT.

METHODS

The degree of steatosis was analysed in 165 consecutive OLTs and was classified by histological examination as non (M0), mild (<30%, M1), moderate (30-60%, M2) or severe steatosis (>60%, M3). Recipients were analysed for EAD.

RESULTS

EAD was observed in 28% of patients with M0, 26% with M1, 53% with M2 and 73% with M3 (P < 0.001). Patients with EAD had a significantly shorter graft survival after liver transplantation (P = 0.005) but did not correlate with survival. In multivariate regression analysis, the grade of steatosis, donating after cardiocirculatory death (DCD) grafts and duration of cold ischaemia time were significantly associated with EAD (P < 0.001, P = 0.01 and P = 0.001, respectively).

CONCLUSION

Livers with severe (M3) steatosis from DCD donors, combined with a prolonged CIT have a high risk for developing EAD which is correlated with shorter graft survival. Therefore M3 livers should only be considered for OLT in selected recipients without the presence of additional risk factors.

Immunosuppression should be stopped in patients with renal allograft failure

Patients returning to haemodialysis or peritoneal dialysis after a failed kidney transplantation sometimes have a renal allograft left in situ for some urine production. Low-dose immunosuppressive medication is often continued in such patients. To evaluate the morbidity and mortality between patients in time periods with (group A) or without (group B) low-dose maintenance immunosuppression, the present study was initiated. In a multi-centre cohort study we analysed data from patient files, which showed failure after at least 3 months graft function between 10 August 1972 and 4 April 1996, including 197 kidney transplantations. A total of 1.7 versus 0.51 infections per patient year was found in groups A and B, respectively (odds ratio [OR]: 3.4, 95% confidence interval [CI]: 2.5-4.5). There was an increased mortality in group A compared to group B (OR 3.4, 95% CI: 1.8-6.3), both from infectious disease (OR 2.8, 95% CI: 1.1-7.0), and cardiovascular disease (OR 4.9, 95% CI: 1.8-13.5). Continuation of immunosuppressive medication did not lead to fewer rejections (defined as a painful, tender graft and/or haematuria and/or low-grade non-infectious fever). Transplantectomy-related morbidity and mortality were acceptable. The increase in morbidity and mortality associated with low-dose maintenance immunosuppression argues in favour of stopping these medicaments when failed renal allograft patients return to dialysis.

In vitro cytokine production of TNFalpha and IL-13 correlates with acute liver transplant rejection

Individuals may differ in their capacity to produce cytokines. Since cytokines play a key role in allograft rejection, we investigated whether inter-individual differences in cytokine production by in vitro stimulated PBMC are related to the occurrence of acute liver transplant rejection. Our study group comprised 49 liver transplant recipients and 30 healthy individuals. Rejection, which occurred within one month after liver transplantation, was defined in 22 patients ("rejectors") as biopsy-proven rejection, treated with high dose prednisolone. Patients who never experienced rejection episodes were termed as "nonrejectors" (n=27). PBMC of healthy individuals and of liver transplant recipients, collected late after transplantation (mean 3.5 years), were cultured in the presence and absence of Concanavalin A. The production of TNF-alpha, IFN-gamma, IL-10, and IL-13 was measured in supernatant after 1, 2, 3, 4, and 7 days of cell culture. In cell culture, stimulated PBMC of rejectors were found to produce significantly higher levels of TNF-alpha, while there was a trend towards higher production of IFN-gamma and IL-10 as compared to nonrejectors. After grouping patients into high or low cytokine producers based upon reference levels of the healthy individuals using multivariate analysis it was found that occurrence of acute liver transplant rejection correlated to high production of TNF-alpha and low production of IL-13. After stimulated cell culture PBMC of liver transplant recipients show a differential production of TNF-alpha and IL-13 which is correlated with the occurrence of acute liver transplant rejection.

Contrast in the efficacy of hDAF mouse hearts between ex vivo perfusion and transplantation into primates

In recent experiments, in which we compared hDAF transgenic rat hearts perfused with 15% human serum in the Langendorff device and hDAF rat hearts transplanted into cynomolgus monkeys, we demonstrated that in the ex vivo heart perfusion model both homozygous and heterozygous hDAF hearts survived longer as nontransgenic controls. Surprisingly, we found that only homozygous hDAF hearts were protected against hyperacute rejection in vivo. The first aim of this study was to determine whether perfusion of mouse hearts with higher human serum concentrations or human blood might explain some of the differences found in survival time of the recently performed experiments with rat heart xenografts. Secondly, we investigated whether the observed differences in survival times of rat xenografts between in vivo and ex vivo transplantation would also hold for mouse hearts transgenic for hDAF. An ex vivo model was used to perfuse hDAF mouse hearts and controls with human serum or blood, and hDAF transgenic hearts and controls were transplanted into cynomolgus monkeys. hDAF transgenic mouse hearts survived significantly longer than their controls when perfused with 15% human serum, but no difference was found when 30% human serum was used, or when these hearts were transplanted into cynomolgus monkeys. However, in both the in vivo and ex vivo models the amount of PMNs adhering to the vascular endothelium was significantly lower in hDAF transgenes as compared with their controls. In conclusion, in the ex vivo situation, the efficacy of hDAF transgenesis in preventing HAR is limited by serum complement concentration.

A comparison of the costs and effects of liver transplantation for acute and for chronic liver failure

Little is known about costs and cost-effectiveness of liver transplantation (LTx) for acute liver failure compared to costs and cost-effectiveness of LTx for chronic liver failure. In this study, costs of acute and of chronic LTx patients were determined in a retrospective study. Files of 100 consecutive patients who underwent LTx in 1993-1997 were studied. Costs up to 1 year after LTx were Euro 107,675 (chronic liver failure) and Euro 90,792 (acute liver failure). The difference was mainly caused by higher hospitalisation costs and higher personnel costs for chronic liver failure. Medication costs for acute liver failure were higher, due to a high administration rate of expensive anti-HBs immunoglobulin therapy in patients with viral hepatitis B. LTx for chronic liver failure is more costly and seems to be more cost-effective than LTx for acute liver failure, since 1-year survival is higher in patients who underwent transplantation for chronic liver failure.

Pretransplant donor-specific helper T cell reactivity as a tool for tailoring the individual need for immunosuppression

BACKGROUND

A reliable immunological assay for quantification of donor-specific alloreactivity to identify patients at risk for future allograft rejection would be a helpful tool in organ transplantation. Therefore, we questioned whether the T cell reactivity in patients measured before transplantation was predictive for the occurrence of acute rejection during the first year after kidney transplantation.

METHODS

The pretransplant T cell reactivity of peripheral blood mononuclear cells to donor and third-party antigens was tested in mixed lymphocyte cultures, and to tetanus toxoid. In addition, we measured the frequency of donor and third-party reactive helper T lymphocyte precursor and cytotoxic T lymphocyte precursors using limiting dilution analysis.

RESULTS

Patients who experienced acute rejection had significantly higher donor-specific mixed lymphocyte cultures responses (n=38; median stimulation index): 113 vs. 15, P=0.005) and helper T lymphocyte precursor frequency (n=37; median 194/106 vs. 62/106, P=0.009) measured before transplantation compared to patients without acute rejection. All patients with a low mixed lymphocyte culture response (stimulation index</=20; 13/13 vs. 12/25, P=0.001) and an undetectable helper T lymphocyte precursor frequency (<10/106 peripheral blood mononuclear cells; 7/7 vs. 17/30, P=0.04) before transplantation did not experience acute rejection. The donor-specific cytotoxic T lymphocyte precursor frequency (n=34; median 53/106 vs. 28/106, P=0.58) and tetanus toxoid-reactivity (n=38; median stimulation index: 53 vs.16, P=0.56) measured before transplantation did not correlate with acute rejection. No correlation between third-party reactivity and acute rejection was observed.

CONCLUSIONS

From these results we conclude that despite the current HLA matching criteria, undetectable helper T lymphocyte precursor frequency and low mixed lymphocyte culture responses against donor antigens measured before transplantation are predictive for a rejection-free first posttransplant year. These in vitro assays can be used to identify patients who require less immunosuppression after transplantation.

Indications and long-term outcome of treatment for benign hepatic tumors: a critical appraisal

HYPOTHESIS

The natural history and clinical behavior of benign hepatic tumors during long-term follow-up may not justify primary surgical treatment.

DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

Two hundred eight patients diagnosed as having a benign liver tumor between January 1, 1979, and December 31, 1999.

INTERVENTION

Seventy-four patients underwent hepatic surgery and 134 were managed conservatively by radiological follow-up.

MAIN OUTCOME MEASURES

Symptoms and complications were assessed during management and follow-up.

RESULTS

In the surgically treated population, the liver lesion was symptomatic in 47 patients (64%) and an incidental finding in 27 (36%). The operative morbidity and mortality were 27% (20 of 74 patients) and 3% (2 of 74 patients), respectively. Overall, 28 (80%) of 35 patients with complaints were asymptomatic after surgery. During observation of the tumor in the conservatively managed group, 39 (87%) of 45 patients who presented with complaints were asymptomatic during a mean follow-up of 45 months; 6 patients had mild abdominal pain considered to be unrelated to the tumor.

CONCLUSIONS

Conservative management of solid benign liver lesions such as focal nodular hyperplasia and hemangioma can be performed safely, irrespective of their size. We only advise surgery for liver lesions when there is an inability to exclude malignancy or in the case of severe complaints related to the tumor. Resection is always advocated in the case of a large hepatocellular adenoma (>5 cm) to reduce the risk of rupture and malignant degeneration.

Proteinuria after renal transplantation affects not only graft survival but also patient survival

BACKGROUND

Proteinuria is associated with an increased risk of renal failure. Moreover, proteinuria is associated with an increased death risk in patients with diabetes mellitus or hypertension and even in the general population.

METHODS

One year after renal transplantation, we studied the influence of the presence of proteinuria on the risk of either graft failure or death in all 722 recipients of a kidney graft in our center who survived at least 1 year with a functioning graft. Proteinuria was analyzed both as a categorical variable (presence versus absence) and as a continuous variable (quantification of 24 hr urine). Other variables included in this analysis were: donor/recipient age and gender, original disease, race, number of HLA-A and HLA-B mismatches, previous transplants, postmortal or living related transplantation, and transplantation year. At 1 year after transplantation, we included: proteinuria, serum cholesterol, serum creatinine, blood pressure, and the use of antihypertensive medication.

RESULTS

In the Cox proportional hazards analysis, proteinuria at 1 year after transplantation (both as a categorical and continuous variable) was an important and independent variable influencing all endpoints. The influence of proteinuria as a categorical variable on graft failure censored for death showed no interaction with any of the other variables. There was an adverse effect of the presence of proteinuria on the graft failure rate (RR=2.03). The influence of proteinuria as a continuous variable showed interaction with original disease. The presence of glomerulonephritis, hypertension, and systemic diseases as the original disease significantly increased the risk of graft failure with an increasing amount of proteinuria at 1 year. The influence of proteinuria as a categorical variable on the rate ratio for patient failure was significant, and there was no interaction with any of the other significant variables (RR=1.98). The death risk was almost twice as high for patients with proteinuria at 1 year compared with patients without proteinuria. The influence of proteinuria as a continuous variable was also significant and also without interaction with other variables. The death risk increased with increasing amounts of proteinuria at 1 year. Both the risks for cardiovascular and for noncardiovascular death were increased.

CONCLUSION

Proteinuria after renal transplantation increases both the risk for graft failure and the risk for death.

Metabolic activity and DNA integrity in human hepatic metastases after interstitial laser coagulation (ILC)

BACKGROUND AND OBJECTIVE

For investigations into interstitial laser coagulation (ILC) of solid tumors, tissue whitening is used as a parameter for the extent of coagulation. This obvious demarcation is associated with global thermal denaturation, but it is not clear whether this finding is a good indicator of the exact outer boundary of the lethal tissue effect.

STUDY DESIGN/MATERIALS AND METHODS

ILC with portal inflow occlusion was performed in human hepatic metastases of colorectal carcinoma directly after surgical resection (n = 5) or before surgical resection (n = 5) with laser parameters adapted to tumor diameter. Mitochondrial NADH-diaphorase activity and DNA integrity were assessed by histoenzymatic staining.

RESULTS

In 7 of 10 tumors (mean diameter, 3.7 cm), an area of macroscopic coagulation (mean diameter, 4.2 cm) encircled the tumor in all three axes. Macroscopic coagulation corresponded to absent metabolism and disintegrated DNA. Furthermore, the macroscopic volumes of coagulation produced in tumor were comparable to the dimensions in normal porcine liver with the same laser parameters.

CONCLUSION

ILC with portal inflow occlusion results in areas with complete cell avitality in the zone of tissue whitening in human hepatic liver metastases.

Transplantation of a single kidney per se does not lead to late graft dysfunction

In unraveling the pathogenesis of chronic transplant dysfunction (CTD), non-alloantigen specific factors, as ischemia/reperfusion and renal mass have been suggested to play a role in the process. The aim of the present study was to investigate the effect of the transplantation procedure per se on the development of CTD in a syngeneic kidney transplant model in the rat. Kidney transplantation was performed with the BN rat as donor and recipient, the recipient kidneys having been removed. Unilaterally nephrectomized (UNx) and native BN rats served as controls. Renal function was determined monthly (proteinuria and glomerular filtration rate/100 g body weight; GFR). The follow-up period was until 52 weeks post-transplantation. Histomorphological analysis of CTD according to the BANFF criteria was carried out. Immunohistochemical staining was performed to identify infiltrating cells (CD4, CD8, and ED1) and the expression of MHC class II and ICAM-1. Isografts had a minor, constant proteinuria during follow-up, which did not differ from that of UNx: 27 +/- 10 vs. 29 +/- 2 mg/24 h at week 52. Unilateral nephrectomy led to a significant reduction of the GFR, which was about 80% of that of native rats. The GFR of isografts did not differ from that of UNx rats. Histomorphology of renal isografts was comparable to UNx and native kidneys; some glomerulopathy and tubular atrophy leading to a total BANFF-score of 2.6 +/- 0.5. In native BN kidneys, few CD4+ cells and ED-1+macrophages (mphi) were found; MHC class II was constitutively expressed on the proximal tubules and ICAM-1 on the glomeruli and peritubular capillaries. UNx-kidneys showed a similar pattern. Isografts had significantly more CD4+ cells and Mphi, mainly localized in the glomeruli, and a more intense ICAM-1 expression in the glomeruli and interstitium. Transplantation of one kidney in itself does not lead to CTD.

Mycophenolic acid trough levels after kidney transplantation in a cyclosporine-free protocol

Twenty-seven stable kidney transplant recipients treated with cyclosporine and prednisone were converted to mycophenolate mofetil (MMF) and prednisone 1 year after transplantation. After conversion the patients were treated with a standard daily dose of 1 g MMF b.i.d. and 10 mg prednisone for 4 months. Thereafter, two MMF dose reductions were performed with a 4-month interval. Mycophenolic acid (MPA) trough levels were measured at regular intervals. A relation was found between MPA trough levels and MMF dose. The median MPA trough level for patients treated with 1 g MMF b.i.d. was 4.3 microg/ml (0.95-15.5) and 3.0 microg/ml (0.73-7.8) for patients treated with 750 mg b.i.d. (P = 0.0002). The MPA trough levels further decreased from 3.0 to 2.3 microg/ml (0.6-6.63) in patients treated with 500 mg MMF b.i.d. (P = 0.01). Dose reduction of MMF from 1 g to 750 mg b.i.d. could be performed without acute rejections. A further dose reduction to 500 mg b.i.d. elicited 3 rejections. Patients experiencing an acute rejection had a median MPA trough level of 2.3 microg/ml (1.26-3.38) compared to 3.8 microg/ml (1.48-6.52) in patients without an acute rejection (P = 0.25). We conclude that there is a significant relation between MPA trough levels and MMF dose. MPA trough levels were not predictive of rejection in the present study.

Negligible role for NK cells and macrophages in delayed xenograft rejection

Hyperacute rejection (HAR) of a discordant xenograft can be avoided by complement manipulation, but delayed xenograft rejection (DXR) still leads to graft loss. It is generally assumed that macrophages and NK cells play key roles in DXR. In the present study the survival times and cellular infiltrate following guinea pig to rat heart transplantation was analyzed in the course of DXR, following aspecific and specific manipulation of macrophages and NK cells. HAR was overcome by a single injection of cobra venom factor 1 day before heart transplantation. To aspecifically reduce the inflammatory response dominating DXR, dexamethasone (DEXA) was given. Treatment with DEXA markedly reduced infiltration by NK cells, macrophages, and granulocytes. It also led to prolonged graft survival times (median survival of 0.4 days, n = 10, P < 0.05). In the second series of experiments the specific roles of NK cells and macrophages in DXR were further assessed. Monoclonal antibody 3.2.3 was used to selectively deplete NK cells. Liposome-encapsulated dichloromethylene biphosphonate was given to achieve macrophage depletion. Neither of these specific treatments, alone or combined, led to prolonged graft survival. Immunohistology revealed that at day 2 after transplantation no NK cells or macrophages were present in grafts from the combined treatment group. Only a mild infiltration of granulocytes was observed. Collectively, these results strongly suggest that NK cells and macrophages are not likely to be pivotal cell types in DXR.

Primary nonfunction of islet xenografts: the role of macrophages

Primary nonfunction (PNF) of hamster islets occurs when they are transplanted under the kidney capsule of diabetic Lewis rat recipients. PNF is absent if the islets are grafted into the liver. Previous results have indicated that macrophages might be involved in the phenomenon of PNF. To test this hypothesis, two procedures affecting macrophages were employed. First, recipients were pretreated with liposomes containing dichloromethylene disphosphonate (L-MDP), killing macrophages upon phagocytosis. Second, recipients were pretreated with the arginine analogue, L-NA, in order to inhibit the synthesis of nitric oxide (NO), a molecule believed to mediate beta cell dysfunction. Injection of L-MDP into the peritoneal cavity had no effect on PNF. However, co-transplantation of L-MDP with hamster islets under the kidney capsule reduced PNF significantly. Eradication of Kupffer cells with L-MDP did not prolong the survival of islets transplanted into the liver, indicating that acute xenogeneic rejection in this model is not mediated by macrophages. A single injection of L-NA, 3 h before transplantation resulted in complete annihilation of PNF, all recipients became normoglycemic within 1 day and remained so for 1.4+/-0.5 days. These results confirmed the finding that macrophages and NO play a crucial role in PNF of islet grafts.

Etiology and pathophysiology of chronic transplant dysfunction

Chronic transplant dysfunction (CTD) is the predominant cause of late graft failure. The common histopathological feature in all transplanted organs is intimal hyperplasia accompanied by organ specific lesions. The knowledge about CTD is incomplete, and there is no therapy to prevent or treat it. This review describes the current knowledge on the etiology of CTD, with emphasis on kidney transplants, and postulates a pathophysiologic route through which CTD may develop.

Treatment of ruptured hepatocellular adenoma

BACKGROUND

As the morbidity and mortality rates associated with emergency resection in patients with a ruptured hepatocellular adenoma are high, the authors have favoured initial non-operative management in haemodynamically stable patients.

METHODS

A retrospective study was performed to evaluate the treatment of ruptured hepatocellular adenoma.

RESULTS

Over a 21-year interval, 12 patients presented with a ruptured hepatocellular adenoma. Haemodynamic observation and support was the initial management in all 12 patients. Three underwent urgent laparotomy and gauze packing because of haemodynamic instability; no emergency liver resection was necessary. Eight patients had definitive surgery; three developed postoperative complications but none died. Regression of the tumour was observed in three of four patients treated conservatively.

CONCLUSION

The initial management of a ruptured hepatocellular adenoma should be haemodynamic stabilization. Definitive resection is required for rebleeding or for tumours exceeding 5 cm in diameter. A conservative approach may well be justified in case of regression of an asymptomatic adenoma.

Molecular cytogenetic evaluation of virus-associated and non-viral hepatocellular carcinoma: analysis of 26 carcinomas and 12 concurrent dysplasias

The worldwide incidence of hepatocellular carcinoma (HCC) is approximately one million cases a year. This makes HCC one of the most frequent human malignancies, especially in Asia and Africa, although the incidence is increasing also in the western world. HCC is a complication of chronic liver disease, with cirrhosis as the most important risk factor. Viral co-pathogenesis makes cirrhosis due to hepatitis B (HBV) and hepatitis C virus (HCV) infection a very important factor in the development of HCC. As curative therapy is often ruled out due to the late detection of HCC, it would be attractive to find parameters which predict malignant transformation in HBV- and HCV-infected livers. This study has used comparative genomic hybridization (CGH) to analyse 26 HCCs (11 non-viral, nine HBV, six HCV) and 12 concurrent dysplasias (five non-viral, five HBV, two HCV). Frequent gain (> or =25% of all tumours) was detected, in decreasing order of frequency, on 8q (69%), 1q (46%), 17q (46%), 12q (42%), 20q (31%), 5p (27%), 6q (27%), and Xq (27%). Frequent loss (> or =25% of all tumours) was found, in decreasing order of frequency, on 8p (58%), 16q (54%), 4q (42%), 13q (39%), 1p (35%), 4p (35%), 16p (35%), 18q (35%), 14q (31%), 17p (31%), 9p (27%), and 9q (27%). Minimal overlapping regions could be determined at multiple locations (candidate genes in parentheses). Minimal regions of overlap for deletions were assigned to 4p14-15 (PCDH7), 8p21-22 (FEZ1), 9p12-13, 13q14-31 (RB1), 14q31 (TSHR), 16p12-13.1 (GSPT1), 16q21-23 (CDH1), 17p12-13 (TP53), and 18q21-22 (DPC4, DCC). Minimal overlapping amplified sites could be seen at 8q24 (MYC), 12q15-21 (MDM2), 17q22-25 (SSTR2, GH1), and 20q12-13.2 (MYBL2, PTPN1). A single high level amplification was seen on 5q21 in an HBV-related tumour. Aberrations appeared more frequent in HBV-related HCCs than in HCV-associated tumours (p=0.008). This was most prominent with respect to losses (p=0.004), specifically loss on 4p (p=0.007), 16q (p=0.04), 17p (p=0.04), and 18q (p=0.03). In addition, loss on 17p was significantly lower in non-viral cancers than in HBV-related HCC (p<0.001). Furthermore, loss on 13q was more prevalent in HCCs in non-cirrhotic livers (p=0.02), thus suggesting a different, potentially more aggressive, pathway in neoplastic progression. A tendency (p=0.07) was observed for loss on 9q in high-stage tumours; no specific changes were found in relation to tumour grade. A subset of the HCC-associated genetic changes was disclosed in the preneoplastic stage, i.e. liver cell dysplasia. This group of dysplasias showed frequent gain on 17q (25%) and frequent loss on 16q (33%), 4q (25%), and 17p (25%). The majority of the dysplasias with alterations revealed genetic changes that were also present in the primary tumour. In conclusion, firstly, this study has provided a detailed map of genomic changes occurring in HCC of viral and non-viral origin, and has suggested candidate genes. Loss on 17p, including the TP53 region, appeared significantly more prevalent in HBV-associated liver cancers, whereas loss on 13q, with possible involvement of RB1, was distinguished as a possible genetic biomarker. Secondly, CGH analysis of liver cell dysplasia, both viral and non-viral, has revealed HCC-specific early genetic changes, thereby confirming its preneoplastic nature. Finally, genes residing in these early altered regions, such as CDH1 or TP53, might be associated with hepatocellular carcinogenesis.

Molecular cytogenetic evaluation of virus-associated and non-viral hepatocellular carcinoma: analysis of 26 carcinomas and 12 concurrent dysplasias

The worldwide incidence of hepatocellular carcinoma (HCC) is approximately one million cases a year. This makes HCC one of the most frequent human malignancies, especially in Asia and Africa, although the incidence is increasing also in the western world. HCC is a complication of chronic liver disease, with cirrhosis as the most important risk factor. Viral co-pathogenesis makes cirrhosis due to hepatitis B (HBV) and hepatitis C virus (HCV) infection a very important factor in the development of HCC. As curative therapy is often ruled out due to the late detection of HCC, it would be attractive to find parameters which predict malignant transformation in HBV- and HCV-infected livers. This study has used comparative genomic hybridization (CGH) to analyse 26 HCCs (11 non-viral, nine HBV, six HCV) and 12 concurrent dysplasias (five non-viral, five HBV, two HCV). Frequent gain (> or =25% of all tumours) was detected, in decreasing order of frequency, on 8q (69%), 1q (46%), 17q (46%), 12q (42%), 20q (31%), 5p (27%), 6q (27%), and Xq (27%). Frequent loss (> or =25% of all tumours) was found, in decreasing order of frequency, on 8p (58%), 16q (54%), 4q (42%), 13q (39%), 1p (35%), 4p (35%), 16p (35%), 18q (35%), 14q (31%), 17p (31%), 9p (27%), and 9q (27%). Minimal overlapping regions could be determined at multiple locations (candidate genes in parentheses). Minimal regions of overlap for deletions were assigned to 4p14-15 (PCDH7), 8p21-22 (FEZ1), 9p12-13, 13q14-31 (RB1), 14q31 (TSHR), 16p12-13.1 (GSPT1), 16q21-23 (CDH1), 17p12-13 (TP53), and 18q21-22 (DPC4, DCC). Minimal overlapping amplified sites could be seen at 8q24 (MYC), 12q15-21 (MDM2), 17q22-25 (SSTR2, GH1), and 20q12-13.2 (MYBL2, PTPN1). A single high level amplification was seen on 5q21 in an HBV-related tumour. Aberrations appeared more frequent in HBV-related HCCs than in HCV-associated tumours (p=0.008). This was most prominent with respect to losses (p=0.004), specifically loss on 4p (p=0.007), 16q (p=0.04), 17p (p=0.04), and 18q (p=0.03). In addition, loss on 17p was significantly lower in non-viral cancers than in HBV-related HCC (p<0.001). Furthermore, loss on 13q was more prevalent in HCCs in non-cirrhotic livers (p=0.02), thus suggesting a different, potentially more aggressive, pathway in neoplastic progression. A tendency (p=0.07) was observed for loss on 9q in high-stage tumours; no specific changes were found in relation to tumour grade. A subset of the HCC-associated genetic changes was disclosed in the preneoplastic stage, i.e. liver cell dysplasia. This group of dysplasias showed frequent gain on 17q (25%) and frequent loss on 16q (33%), 4q (25%), and 17p (25%). The majority of the dysplasias with alterations revealed genetic changes that were also present in the primary tumour. In conclusion, firstly, this study has provided a detailed map of genomic changes occurring in HCC of viral and non-viral origin, and has suggested candidate genes. Loss on 17p, including the TP53 region, appeared significantly more prevalent in HBV-associated liver cancers, whereas loss on 13q, with possible involvement of RB1, was distinguished as a possible genetic biomarker. Secondly, CGH analysis of liver cell dysplasia, both viral and non-viral, has revealed HCC-specific early genetic changes, thereby confirming its preneoplastic nature. Finally, genes residing in these early altered regions, such as CDH1 or TP53, might be associated with hepatocellular carcinogenesis.

A comparison of suture repair with mesh repair for incisional hernia

BACKGROUND

Incisional hernia is an important complication of abdominal surgery. Procedures for the repair of these hernias with sutures and with mesh have been reported, but there is no consensus about which type of procedure is best.

METHODS

Between March 1992 and February 1998, we performed a multicenter trial in which we randomly assigned to suture repair or mesh repair 200 patients who were scheduled to undergo repair of a primary hernia or a first recurrence of hernia at the site of a vertical midline incision of the abdomen of less than 6 cm in length or width. The patients were followed up by physical examination at 1, 6, 12, 18, 24, and 36 months. Recurrence rates and potential risk factors for recurrent incisional hernia were analyzed with the use of life-table methods.

RESULTS

Among the 154 patients with primary hernias and the 27 patients with first-time recurrent hernias who were eligible for the study, 56 had recurrences during the follow-up period. The three-year cumulative rates of recurrence among patients who had suture repair and those who had mesh repair were 43 percent and 24 percent, respectively, with repair of a primary hernia (P=0.02; difference, 19 percentage points; 95 percent confidence interval, 3 to 35 percentage points). The recurrence rates were 58 percent and 20 percent with repair of a first recurrence of hernia (P=0.10; difference, 38 percentage points; 95 percent confidence interval, -1 to 78 percentage points). The risk factors for recurrence were suture repair, infection, prostatism (in men), and previous surgery for abdominal aortic aneurysm. The size of the hernia did not affect the rate of recurrence.

CONCLUSIONS

Among patients with midline abdominal incisional hernias, mesh repair is superior to suture repair with regard to the recurrence of hernia, regardless of the size of the hernia.

Randomized study on the conversion of treatment with cyclosporine to azathioprine or mycophenolate mofetil followed by dose reduction

BACKGROUND

The introduction of cyclosporine (CsA) in kidney transplantation has improved early graft survival. However, its long-term use is associated with impairment of renal function and increased cardiovascular risk factors. To avoid CsA-related long-term adverse effects, patients were converted to either azathioprine (AZA) or mycophenolate mofetil (MMF) 1 year after transplantation.

METHODS

Between September 1995 and January 1997, 64 stable renal transplant recipients on CsA and prednisone treatment were included in a prospective, randomized study. Patients were randomized for conversion of CsA to 2 mg/kg AZA (n=30) or 1 g of MMF twice daily (n=34). All patients remained on low-dose steroids. To decrease the total immunosuppressive load, a dose reduction in MMF and AZA was performed at 4 and again at 8 months after conversion. Mycophenolic acid trough levels were measured at regular intervals.

RESULTS

After conversion, a decrease in serum creatinine was found for both groups: for MMF, 132 to 109 micromol/L (P=0.016); and for AZA, 123 to 112 micromol/L (P<0.0001). After conversion, more acute rejections occurred in the AZA group (11/30) compared to the MMF group (4/34) (P=0.04). Dose reduction of MMF to 500 mg twice daily and of AZA to 1.0 mg/kg elicited three rejections in both groups. The incidence of side effects and infections were similar.

CONCLUSION

Discontinuation of CsA spared renal function. In patients converted to MMF significantly less rejections occurred compared to patients converted to AZA. Furthermore, dose reduction of both AZA and MMF is possible in the majority (72%) of the patients.

Importance of portal flow diversion in experimental auxiliary partial orthotopic liver transplantation

BACKGROUND

Auxiliary partial orthotopic liver transplantation (APOLT) has successfully been performed in patients with noncirrhotic metabolic diseases. It remains, however, unclear if intervention in the portal venous inflow is necessary to ensure adequate portal blood flow to graft and host liver. In this experimental study we evaluate the hepatic flow during APOLT.

METHODS

Left lateral/medial segmental grafts were transplanted from beagle to dalmatian dogs. Vascular structures were anastomosed end-to-end. The effect of diversion of the portal flow was studied in three groups: in the ligation group (n=3) the host portal vein was tied off, the free flow group (n=6) had random flow to both livers. In the banding group (n=11) the host portal vein was banded with a adjustable strapband to restore the pretransplantation flow distribution.

RESULTS

After reperfusion the blood flow through the common portal vein decreased from 49 to 36 ml/kg/min (P<0.03) in all animals. Flow through the left portal vein decreased from 26 to 5 ml/kg/min (P<0.0001). Banding restored the flow in the left portal vein to 12 ml/kg/min, although the flow in the free-flow group remained 4 ml/kg/min. In the ligation group the total portal flow was forced toward the graft leading to the highest perfusion: 24 ml/kg/min (P<0.005). Adverse effect of this ligation was the development of portal hypertension.

CONCLUSIONS

This experimental study confirms that diversion of the portal flow is necessary for adequate graft perfusion in APOLT. Banding can restore the pretransplantation flow distribution, without compromising the flow in the common portal vein.

Donor-specific T-cell reactivity identifies kidney transplant patients in whom immunosuppressive therapy can be safely reduced

BACKGROUND

To reduce the side effects of long-term immunosuppressive therapy, stable renal transplant patients were routinely converted from cyclosporine to either azathioprine or mycophenolate mofetil. Thereafter, the azathioprine and mycophenolate mofetil dose was reduced to 75% at 4 months and to 50% at 8 months after conversion. We questioned whether the T-cell reactivity before conversion was able to predict which patients could be safely converted and tapered in their immunosuppressive load, while remaining free from acute rejection.

METHODS

Before conversion, the T-cell reactivity of peripheral blood mononuclear cells against donor and third-party spleen cells were tested in mixed lymphocyte cultures. We measured the frequency of donor and third-party reactive helper T-lymphocyte (HTLpf) and cytotoxic T-lymphocyte (CTLpf) precursors and their avidity for HLA class I antigens using limiting dilution analysis. Peripheral blood mononuclear cells were also stimulated with tetanus toxoid to test the general immune response.

RESULTS

The tetanus toxoid response, reactivity to donor and third-party cells as measured in mixed lymphocyte cultures and HTLpf, and the avidity of cytotoxic T-lymphocyte precursors were not predictive for the development of acute rejection. However, significant differences were found in donor-specific CTLpf before conversion, between patients with and without acute rejection after conversion in immunosuppression. The donor-specific CTLpf was significantly lower in patients without compared to those with acute rejection (P=0.01). Additionally, when no CTLpf was detectable before conversion, acute rejection did not occur after conversion. Acute rejection was only diagnosed in patients with detectable CTLpf before conversion.

CONCLUSION

The number of donor-specific cytotoxic T-lymphocytes identifies patients in whom the immunosuppressive load can be safely reduced.

Heat-resistant cylindrical diffuser for interstitial laser coagulation: comparison with the bare-tip fiber in a porcine liver model

BACKGROUND AND OBJECTIVE

Interstitial laser coagulation is an experimental treatment to eliminate solid tumors such as hepatic metastases. The pattern of light emission from the fiber tip is probably an important factor in determining the size and shape of a lesion. A heat-resistant cylindrical light diffusing tip of 2 cm length was developed for this application. We performed an in vitro study to compare this diffusing-tip with a bare-tip fiber.

STUDY DESIGN/MATERIALS AND METHODS

Fiber ends were positioned between two porcine liver slabs (37 degrees C) and Nd:YAG laser light (1064 nm) was guided through either fiber with an output of 3-9 W and exposure times of 6-18 minutes.

RESULTS

Lesions produced by the cylindrical diffuser tip were significantly larger and more predictable. With the diffuser tip, lesions up to 36/23 mm (length/width) could be produced at 7 W and 9 min without any central charring. The maximum size of lesions produced with the bare-tip fiber was 32/20 mm at 6 W for 9 min with massive charring.

CONCLUSIONS

The results indicate that at optimal laser settings, the diffuser tip produces a larger coagulation volume than a bare-tip fiber. For clinical application, cylindrical diffusing fibers should be used with a diffusing length adapted to the diameter of the tumor.

Cholesterol as an independent predictor of outcome after renal transplantation

BACKGROUND

The debate on the role of high serum cholesterol levels in cardiovascular disease or chronic vascular rejection in kidney-transplanted patients has not yet been settled.

METHODS

We studied the influence of serum cholesterol at 1 year after transplantation on the failure risk in all 676 kidney graft recipients who survived with a functioning graft. Other variables included in this analysis were donor/recipient age and gender, original disease, race, number of HLA-A and -B mismatches, previous transplants, postmortal or living-related transplantation, and transplantation year. At 1 year after transplantation, we included: serum cholesterol, serum creatinine, proteinuria, and hypertension.

RESULTS

In the Cox proportional hazards analysis, serum cholesterol at 1 year after transplantation turned out to be an important, independent variable influencing all end points (adjusted for all other variables in the model). The influence on graft failure censored for death was log-linear, and there was interaction with serum creatinine at 1 year. The adverse effect of elevated serum cholesterol levels on the graft failure rate decreased with increasing serum creatinine levels. The influence of serum cholesterol on the rate ratio (RR) for patient failure was linear too, and here there was interaction with recipient age. The negative influence of serum cholesterol on the RR for patient failure decreased with increasing recipient age. The risk for over-all graft failure was influenced by increasing serum cholesterol levels, and there was interaction with recipient age. Because recipient age had interaction with donor age and serum creatinine, the influence of all four variables together on the RR was estimated. It is shown that whereas the RR for over-all graft failure in young recipients of a renal transplant increases significantly with higher cholesterol levels, there is very little influence on the RR of elderly recipients. The risk increases proportionally with increasing serum creatinine levels.

CONCLUSION

Serum cholesterol levels have an independent influence on graft, patient, and over-all graft failure.

Extracorporeal perfusion for the treatment of acute liver failure

OBJECTIVE AND SUMMARY BACKGROUND DATA

Because of the shortage of available donor organs, death rates from liver failure remain high. Therefore, several temporary liver-assisting therapies have been developed. This article reviews various approaches to temporary liver support as well as immunologic and metabolic developments toward a solution for this problem.

METHODS

A literature review was performed using Medline and additional library searches to obtain further references. Only articles with a well-defined aim of study and methodology and a clear description of the outcome of the experiments were included.

CONCLUSIONS

Renewed interest has developed in old and new methods for an extracorporeal approach to the treatment of acute liver failure. Although temporary clinical improvement has been established, further research is needed to achieve a successful long-term clinical outcome. New developments in the field of genetic modification and tissue engineering await clinical application in the near future.

A longitudinal study of TGF-beta1 protein levels in renal allograft recipients converted from CsA to MMF or AZA

Cyclosporine (CsA) is thought to enhance transforming growth factor (TGF)-beta1 production in vitro and in vivo and this may have a negative effect on long-term graft survival. Therefore, we studied TGF-beta1, plasma levels in 30 patients before kidney transplantation, after transplantation during CsA treatment and after conversion from CsA to azathioprine (AZA) or mycophenolate mofetil (MMF). We questioned whether TGF-beta1 plasma levels would decrease after the discontinuation of CsA and whether the TGF-beta1 plasma levels did correlate with CsA trough levels and kidney function, measured by serum creatinine levels. TGF-beta1 plasma levels measured 1 yr after transplantation were lower compared to levels measured before transplantation, however not significantly (p = 0.08). After conversion from CsA to MMF or AZA, a slight increase was observed in some patients, but in the total group TGF-beta1 levels remained unaffected. No correlation was found between the TGF-beta1 levels and CsA trough levels nor with creatinine levels. In conclusion, we did not observe higher TGF-beta1 plasma levels in plasma levels of patients receiving CsA treatment compared to blood from the same patients while on AZA or MMF.

P53 overexpression in colorectal metastases confined to the liver and outcome of liver resection

BACKGROUND/AIMS

The results of hepatic surgery for colorectal metastases are distorted by the high incidence of recurrence, despite an apparently radical resection. Selection of high-risk patients is a mandatory step towards effective application of neo-adjuvant chemotherapy. In this study, expression of the tumor suppresser gene p53 in colorectal liver metastases was correlated with recurrence after resection.

METHODOLOGY

In a retrospective case-series p53 expression was assessed using standard immunohistochemical methods in the paraffin-embedded specimens of 45 liver resections for colorectal metastases, performed in 43 patients in a single institution between '86 and '96. Hospital and office charts were reviewed and follow-up was completed with a General Physicians' questionnaire in October '97. Relapse-free and cancer-specific survival from diagnosis of hepatic metastases were assessed and compared for p53+ and p53- groups.

RESULTS

Median survival was 36 months with an estimated 5-year cancer-specific survival of 43% (95% confidence interval 35%-51%). Relapse-free and cancer-specific survival were not significantly different between p53+ (n = 24, 53%) and p53- (n = 21) groups (P = 0.86 and P = 0.91 respectively). P53 expression was not associated with other potential predictors, which were not of predictive value either.

CONCLUSIONS

Patients at risk for recurrent disease following partial hepatectomy for colorectal metastases cannot be identified by p53 expression.

Effect of mycophenolate mofetil on erythropoiesis in stable renal transplant patients is correlated with mycophenolic acid trough levels

BACKGROUND

Both mycophenolate mofetil (MMF) and azathioprine (AZA) are immunosuppressive drugs that inhibit purine synthesis. In theory, MMF selectively inhibits lymphocyte proliferation, while AZA has well-known effects on red blood cells and thrombocytes as well. In renal transplant recipients we replaced CsA therapy by MMF in an attempt to reduce the immunosuppressive load 1 year after kidney transplantation. During this study we observed the effect of MMF on haematological parameters such as haemoglobin (Hb), leukocytes, and thrombocytes.

METHODS

One year after kidney transplantation 26 stable patients were converted from cyclosporin A (CsA) to MMF (2 g/day). Thereafter, these patients were tapered twice in their MMF dose from 2 g to 1.5 g (4 months after conversion) and from 1.5 to 1 g (8 months after conversion) per day. The Hb levels, leukocyte and thrombocyte counts, and mycophenolic acid (MPA) trough levels were routinely measured.

RESULTS

After conversion from CsA to MMF not only creatinine levels and the number of leukocytes, but also the haemoglobin (Hb) level significantly decreased in 21/26 patients (P=0.0004). In eight patients the Hb level dropped more than 1 mmol/l (=1.61 g/dl). Only in two of eight patients was an explanation for blood loss found. The effect on Hb level did not ameliorate after the first MMF dose reduction to 1.5 g/day. After tapering the MMF dose to 1 g/day, the Hb approached the pre-conversion level. Not only the MMF dose but also the mycophenolic acid (MPA) trough level correlated with the Hb level.

CONCLUSIONS

After conversion from CsA to MMF 1 year after kidney transplantation, a decrease in Hb level and leukocyte count was observed. The MPA trough level correlated also with the Hb level. The effect on the Hb level was reversible after dose reduction. This finding suggests that MMF exerts a negative effect on erythropoietic cells.

Critical temperature and heating time for coagulation damage: implications for interstitial laser coagulation (ILC) of tumors

BACKGROUND

Interstitial laser coagulation (ILC) is a method of local tissue destruction for solid tumors such as irresectable hepatic metastases from colorectal cancer. With the availability of new magnetic resonance (MR) techniques, which allow real time tissue temperature mapping, it is essential to know the critical temperature and exposure times leading to cell death. MATERIALS AND METHODS/STUDY DESIGN: Samples (8 mm(3)) of solid rat tumor (CC-531, syngenic to the WAG/Rij rat strain), were warmed in tubes for four different temperatures (40, 50, 60 or 80 degrees C) and four different exposure times (3, 6, 12, or 24 minutes). Combinations were replicated in five-fold. Cell viability was assessed with three methods: Trypan blue exclusion test in collagenase/dispase dissociated samples, NADH activity in snap frozen samples and outgrowth for 2 weeks under the renal capsule of WAG/Rij rats.

RESULTS

Results of the three methods revealed that viability was not affected with heating at 40 and 50 degrees C except for 24 minutes at 50 degrees C. At higher temperatures cell death occurred at all exposure times.

CONCLUSION

The temperature range resulting in sufficient tissue coagulation for cell death is between 50 degrees C and 60 degrees C for a short duration (<3 minutes). These data can be used to achieve complete tumor destruction and minimal surrounding tissue damage during real-time MR-controlled ILC.

Long-term effects of interstitial laser coagulation in porcine liver with portal inflow occlusion: central versus peripheral lesions

PURPOSE

Interstitial laser coagulation (ILC) is an attractive modality for local destruction of unresectable hepatic metastases. Portal inflow occlusion considerably increases its destructive capacity, resulting in lesions 5 cm in diameter; however, effects on adjoining major intrahepatic structures are unknown. Therefore, the purpose of this study was to assess the effects of ILC with portal inflow occlusion on the central portion of the liver as compared to the peripheral portions.

MATERIALS AND METHODS

ILC was performed in pigs with portal inflow occlusion. Each animal received a single laser application with Nd:YAG light guided simultaneously through four interstitial fibers with 5 W per fiber during 6 minutes. Location of treatment was randomized to either central (n = 8) or peripheral (n = 8). Follow-up was for 1, 2, or 3 months with evaluation of liver functions and weight, as well as macroscopic and microscopic assessment of coagulated lesions and surrounding parenchyma.

RESULTS

There was no treatment-related morbidity or mortality. No obstructive cholestasis or bile leakage was found. At every moment of evaluation, coagulated volumes in the central group were smaller than in the peripheral lesions (P = .03). Large vessels contiguous to the lesions in the central group were always intact and indications of portal hypertension or thrombosis of hepatic veins were not found. There were no significant differences between the two groups (liver functions [P > or = .15] and weight [P = .69]).

CONCLUSION

ILC with portal inflow occlusion is a safe technique in the vicinity of vital structures in the liver of healthy pigs. These results justify studies to the feasibility and complication rate of portal inflow occlusion in patients with hepatic malignancies.

Genetic susceptibility of the donor kidney contributes to the development of renal damage after syngeneic transplantation

Solitary kidneys, especially in rats, appear vulnerable to develop functional and structural damage. However, differences in susceptibility exist between strains. It is not clear whether this is intrinsic to the kidney or due to environmental factors. Therefore, the aim of the present study was to investigate possible differences in genetic susceptibility for renal damage. By transplanting different rat donor kidneys into a normotensive, histocompatible recipient, the kidneys were exposed to the same blood pressure profiles, metabolic and hormonal environment. Kidneys from young adult hypertensive fawn-hooded (FHH) rats, a strain showing early onset renal damage, normotensive, renal damage-resistant August x Copenhagen-Irish (ACI), and (ACI x FHH) F1 donors were transplanted into male F1 recipients. The native kidneys of the recipients were removed 1 week after transplantation. The results were mutually compared and to their unilaterally nephrectomized littermates. Systolic blood pressure (SBP) and albuminuria (UaV) were determined at the time of transplantation and at 8 and 16 weeks. The histomorphologic analysis included the incidence of focal glomerulosclerosis (FGS), and determination of chronic transplant dysfunction according to the BANFF criteria. A negative impact of the transplantation technique in this syngeneic situation could not be detected as F1 transplants did not differ functionally and morphologically from their UNx controls. Transplanting an ACI kidney did not result in significant changes of SBP, UaV, and incidence of FGS compared to F1 transplants and ACI-UNx. In contrast, FHH kidneys did show a progressive increase of UaV and glomerulosclerosis and a significantly higher BANFF score, whereas the SBP did not differ from F1 transplants. The moderate hypertension seen in FHH did not travel with the kidney. Compared to the FHH-UNx rats, transplantation of a FHH kidney did significantly attenuate the increase of UaV and FGS. The susceptibility of the donor kidney appears to be an important factor in the development of chronic renal damage. This may play a role in the long-term functional changes seen after clinical renal transplantation.

IgG, but not IgM, mediates hyperacute rejection in hepatic xenografting

We reported previously that no classical features of hyperacute rejection (HAR) could be found in liver grafts in the guinea-pig (GP)-to-rat model and that recipients died shortly after transplantation of non-immunologic causes. Thus, the GP-to-rat model is not suitable for studying the mechanisms of discordant liver xenograft rejection. In the hamster to rat model, long-term survival of a liver graft is possible, but extremely low levels of xenoreactive natural antibodies are present. To mimic a discordant situation with pre-formed IgM and IgG antibodies, we sensitized rats 1 or 5 weeks before grafting. Specific anti-hamster IgM antibodies were found in recipients sensitized at week -1 but not week -5. Anti-hamster IgG was present in all recipients, albeit considerably higher in animals sensitized 5 weeks before grafting. In these two models, we examined the mechanism of HAR of liver grafts and compared this with heart xenografts. Control heart and liver grafts were rejected 4 and 7 days after transplantation respectively. Liver grafts in recipients sensitized at week -5 showed venous congestion and bleeding after reperfusion, indicating HAR, however this was not observed after sensitization at week -1. This surprising finding was confirmed by histology. Massive extravasation, edema, and acute liver cell degradation were noticed in grafts subjected to HAR. Liver grafts of recipients sensitized at week -1 showed only minimal changes. Heart grafts were rejected hyperacutely in both sensitization models. IgG antibodies could be detected on liver grafts in the group sensitized at week -5 but not in the group sensitized at week -1. Minimal IgM depositions were found on liver grafts of animals sensitized 1 week before grafting. Rejected heart grafts from similar sensitization groups showed identical antibody depositions; only IgM depositions were massive. Complement depositions were found in all groups. These results indicate that IgG, but not IgM, mediates HAR in hepatic xenografting. Such a predominance of IgG over IgM does not exist for heart grafts.

Atypical mycobacterium infection with dermatological manifestation in a renal transplant recipient

In April 1997, a 58-year-old renal transplant recipient presented with abscess-like nodules in his left calf and on his right foot. Furuncular disease was suspected and the patient was treated with flucloxacillin. However, the lesions increased in size and became ulcerative. In the following 3 months, cultures of punctuated material, blood, and urine remained negative and gram stains did not reveal micro-organisms. In June 1997, acid-fast stains were positive. A diagnosis of a nontuberculous mycobacterium (NTM) infection was made and empirical antimycobacterial therapy was started. The combination of relatively minor symptoms with enlarged purulent lesions, causing severe morbidity, raises the possibility of NTM infection in the immunocompromised patient.

The vanishing importance of age in renal transplantation

BACKGROUND

The growing number of patients awaiting a kidney transplant raises questions about allocation of kidneys to the elderly and about the use of elderly donors. In all reported studies analyzing the influence of age on the outcome after renal transplantation, age is investigated as a categorical variable.

METHODS

We studied age both as a categorical (Kaplan-Meier) and as a continuous (Cox) variable in a total of 509 cyclosporine-treated recipients of a primary cadaveric kidney graft who underwent transplantation between July 1983 and July 1997. For the Kaplan-Meier analysis, the population was divided into three comparably sized age groups: 17-43 years (n=171), 44-55 years (n=169), and 56-75 years (n=169).

RESULTS

Patient survival was better and graft survival censored for death was worse in the younger patients. Overall graft survival (end point was death or graft failure) was not significantly influenced by age. In the Cox proportional hazards analysis, transplantation year turned out to be an important, independent variable influencing all end points. Because the influence was not linear, three periods were defined in which the relative risk remained stable: 1983-1990, 1991-1993, and 1994-1997. In the second period, the relative risk for transplant failure or death was 49% of that in the first period. In the third period, the relative risk had decreased to 22% of that in the first period. Recipient age and donor age were significant predictors of overall transplant failure. There was no interaction between these variables and transplantation year. Within each transplantation period, an increase in recipient age by 1 year increased the relative risk for overall graft failure by only 1.44%. The influence of donor age followed a J-shaped curve with a minimum at 30 years. The influence of increasing either recipient or donor age was counteracted by the improving results over time.

CONCLUSION

Considering the improving results over time, there are, at this moment, no arguments for an age restriction for kidney transplant recipients or donors.

The fourth barrier

At the entrance of a new era, clinical xenotransplantation is a valued and auspicious option in tackling the problem of donor shortage. Because of ethical and anatomical issues, domestic farm animals are considered the most favourable species for organ donation, but transplantation of their organs leads to a complex process of rejection. Mechanistically, three immunological barriers, namely hyperacute rejection, delayed xenograft rejection and a subsequent cellular rejection, are distinguished. A fifth (microbiological) barrier is also being recognised. This review focuses on problems regarding the fourth barrier, i.e. physiology, in possible clinical settings and their corresponding animal models. Besides anatomical differences and posture, biochemical differences may have a severe impact on recipient survival. Differences in blood components and electrolyte and other biochemical concentrations are easily detected throughout the species considered for xenotransplantation. Enzymes and hormones have complex routes of action, activation and inhibition, and their molecular differences can impede function. As infusion or medicine may correct certain imbalances in electrolytes and proteins, problems with complex interactions might be difficult to retrieve and solve. Experimentally, survival of discordant xenografts show promising results, but the first physiological problems have already been detected. So, based upon the few experimental data available and the comparison of veterinary physiology, one might expect differences between the organs grafted, regarding the possible occurrence of physiological problems. Moreover, precautions must be taken to extrapolate long-term survival, because of species specificity.

[Hepatocellular adenoma in 20 patients; recommendations for treatment]

OBJECTIVE

Analysis of the diagnostic approach and management of 20 patients with hepatocellular adenoma, 1979-1996.

SETTING

University Hospital Rotterdam-Dijkzigt, Rotterdam, the Netherlands.

DESIGN

Retrospective and follow-up analysis.

METHOD

Medical records of patients with histologically proven hepatocellular adenoma were analysed with respect to complaints, diagnostic approach and therapeutical management. Follow-up took place at the outpatient department where history-taking, physical examination, ultrasonography and hepatitis B and C serology tests were performed.

RESULTS

In the period 1979-1996, 20 patients with hepatocellular adenoma were treated. Eight patients (mean tumour size 3.2 cm (1.5-5)) were treated conservatively, 12 (mean tumour size 8.1 cm (6-10)) underwent hepatic resection; four because of rupture of the tumour. Serum liver enzyme values did not contribute to the diagnosis. Of the lesions 78% were diagnosed correctly by ultrasonography and 71% by computer tomography. Median follow-up of the patients treated operatively was 73 months (1-204). One patient died three years after an incomplete resection of a hepatocellular adenoma, because of a hepatocellular carcinoma. Ultrasonography did not demonstrate any recurrent tumours in the other patients. In the group of patients conservatively treated (median follow-up 39 months (24-72)) two patients died because of a hepatocellular carcinoma. Ultrasonography demonstrated stable tumour diameters in three patients and regression in three others.

CONCLUSION

Based on the literature and the presented experience surgical treatment is the treatment of choice in patients with large (> or = 5 cm diameter) hepatocellular adenomas because of the risk of malignant transformation and rupture of the tumour. With smaller tumours (< 5 cm) a conservative treatment may suffice in hepatitis virus negative patients, including withdrawal of oral contraceptives followed by thorough ultrasound follow-up of tumour size. In case of tumour growth or complaints a resection of the tumour is indicated.