Update on liver transplantation using cyclosporine

After the introduction of cyclosporine into liver transplantation in 1983, 1-year patient survival more than doubled. Later, with the improved microemulsified formulation of cyclosporine (Neoral) more stable pharmacokinetics were achieved. Today, C(2) monitoring of cyclosporine blood levels allows a more accurate estimation of the area under the concentration-versus-time curve as the single best indicator of cyclosporine exposure. As a consequence, with better control of side effects as well as desired effects the results of cyclosporine in liver transplantation have been further improved. The introduction of mycophenolate mofetil and basiliximab/daclizumab combination therapy has provided new options for the prevention of allograft rejection. The safety profile of individual immunosuppressive regimens comes more into focus since acute allograft rejection may be controlled successfully with competing strategies. As the focus in liver transplantation is shifting toward greatly improved long-term results, late posttransplant mortality with a functioning graft is a major concern. Prevention of long-term complications associated with highly effective immunosuppressants--posttransplant lymphoproliferative disease, cytomegalovirus infection, diabetes, hypertension, and hyperlipidemia-gains importance. Technical advances in living-related and cadaveric split-liver transplantation have lead to increasing use of segmental liver transplantation with the need to consider the effects of immunosuppression on liver regeneration and metabolism. The individualized orchestration of immunosuppression taking into account the underlying liver disease as well as other individual predispositions remains a future challenge.

[Surgical treatment for hilar cholangiocarcinoma (Klatskin's tumor)]

Surgical treatment of hilar bile duct carcinoma remains difficult, which is due to the inadequate possibilities in assessing tumor extent during the preoperative diagnostic procedure as well as intraoperatively. Radical resection with negative histologic margins offers the best chance for long-term survival. The decision regarding the appropriate surgical approach is challenging due to the complexity of tumor localization and neighboring vascular structures. Aggressive resection demands extended liver resection, which is associated with the risk of postoperative liver failure. However, even limited surgery such as hilar resection can be curative and leads to long-term survival in individual cases. The principles of surgical oncology have led to more aggressive procedures, including the combination of liver transplantation and multivisceral resection, and can be performed with calculable morbidity and mortality. Nevertheless, the high risk of tumor recurrence under long-term immunosuppression, the limited availability of donor organs and the excellent results of liver transplantation in non-malignant diseases do not justify this procedure at present. Neoadjuvant radiochemotherapy has failed to demonstrate major benefit. In patients with irresectable tumor or distant metastases palliative measures are aimed at restoring an unobstructed bile flow with endoscopic placement of metal stents. Palliative treatment with additional radio- or photodynamic therapy may be considered in individual cases.

[Living kidney transplantation. A comparison of Scandinavian countries and Germany]

The discussion of compensating for shortages of cadaveric donation with increased living donation often reveals differences between the Scandinavian countries and Germany. Possible adoption of Scandinavian structures to improve the rate of living donations in Germany warrants analysis of the actual differences between these two regions. Close examination reveals that significantly higher rates of living donation are achieved only in Sweden and Norway. In Norway, a frequently postulated negative effect on cadaveric donation due to very high rates of living donation could not be confirmed. In contrast to Germany and as a consequence of Norwegian geography, kidney transplantation has been regarded in Norway as the first-line therapy for endstage renal disease for more than 35 years. Living donation has since been actively pursued and is traditionally the transplantation of first choice. In Germany, living donation is still regarded as the second choice after cadaveric donation, due to legal regulations. Significant improvements in living donation frequencies could be achieved there by adopting the active Norwegian approach to living donor identification.

Successful outcome of acute graft-versus-host disease in a liver allograft recipient by withdrawal of immunosuppression

BACKGROUND

Graft-versus-host disease (GVHD) after liver transplantation is uncommon, and the outcome is almost always fatal. Since 1987, about 30 cases have been described, and patient survival is mostly exceptional.

METHODS

A 29-year-old man underwent retransplantation due to chronic cholestatic syndrome, 5 years after his first liver transplantation. Indication for the first liver transplantation was acute liver failure caused by exsiccosis. After the second transplantation, the patient had an initially uneventful course, developing thrombocytopenia at day 21 followed by skin rash and septic complications. Diagnosis of acute GVHD was made by using serological techniques for HLA-A and HLA-DRB and subsequently by fluorogenic sequence-specific primed polymerase chain reaction. In addition, donor lymphocytes were marked by immunohistochemical methods via biopsies of the skin. Immunosuppressive therapy was withdrawn to allow the patient's own immune system to eliminate donor cells.

RESULTS

By withdrawing the immunosuppressive therapy, clinical and morphological signs of GVHD vanished. The patient is doing well without recurrence 13 months after transplantation.

CONCLUSION

Withdrawal of immunosuppressive therapy is a promising approach in the treatment of acute GVHD to allow the patient's immune system to reconstitute itself, reject offending lymphocytes, and avoid lethal septic complications.

CMV in kidney transplantation: a single center experience over 22 years

Analysis of a historic renal transplant population for risks of developing CMV disease demonstrated a low mortality (0.2%) and morbidity. In our population of 1,959 patients, 411 (21%) developed subclinical CMV infection and 220 (11%) had CMV disease which was severe in 41 (2%). Important factors for infection were baseline immunosuppression, indicating that triple therapy with the proliferation inhibitors, azathioprine and MMF, had significantly higher infection numbers in comparison to dual, CsA-based immunosuppression. The cumulative dose of steroids correlated strongly with an increased number of CMV infections and disease, as did the addition of ALG/ATG or OKT3 for either steroid-resistant rejections or induction therapy. While CMV serology had an impact on infection in cases of seropositive donors to seronegative recipients, seropositive patients, in general, demonstrated increased infection rates most likely due to reactivation of the virus. Prophylaxis had no impact on the incidence of infection but reduced the severity.

[Perfusion parameters in MRI diagnosis of pancreas transplants]

PURPOSE

Evaluation of the role of perfusion parameters in the detection of circulatory disturbance and chronic rejection in patients after pancreas transplantation.

MATERIALS AND METHODS

70 examinations of 39 patients after pancreas transplantation were performed. Using a dynamic gadolinium-enhanced Turbo-FLASH-sequence, we evaluated the perfusion parameters in a group of patients with chronic rejection, with circulatory disturbance, and in a control group with normal organ function.

RESULTS

There were statistically significant differences of the perfusion parameters in patients with chronic rejection and circulatory disturbance compared to the control group.

CONCLUSION

Dynamic MRI can help detect patients with chronic rejection and circulatory disturbance and should therefore be part of the routine follow-up in patients after pancreas transplantation.

ConStruct: a tool for thermodynamic controlled prediction of conserved secondary structure

A tool for prediction of conserved secondary structure of a set of homologous single-stranded RNAs is presented. For each RNA of the set the structure distribution is calculated and stored in a base pair probability matrix. Gaps, resulting from a multiple sequence alignment of the RNA set, are introduced into the individual probability matrices. These 'aligned' probability matrices are summed up to give a consensus probability matrix emphasizing the conserved structural elements of the RNA set. Because the multiple sequence alignment is independent of any structural constraints, such an alignment may result in introduction of gaps into the homologous probability matrices that disrupt a common consensus structure. By use of its graphical user interface the presented tool allows the removal of such misalignments, which are easily recognized, from the individual probability matrices by optimizing the sequence alignment with respect to a structural alignment. From the consensus probability matrix a consensus structure is extracted, which is viewable in three different graphical representations. The functionality of the tool is demonstrated using a small set of U7 RNAs, which are involved in 3'-end processing of histone mRNA precursors. Supplementary Material lists further results obtained. Advantages and drawbacks of the tool are discussed in comparison to several other algorithms.

The hepatitis B virus post-transcriptional regulatory element contains two conserved RNA stem-loops which are required for function

Human Hepatitis B Virus (HBV) RNAs contain a cis -acting sequence, the post-transcriptional regulatory element (HPRE), which facilitates the cytoplasmic localization of intronless transcripts. Our previous studies have shown that the HPRE is composed of at least two independent sub-elements, HPREalpha and HPREbeta, which co-activate a reporter for RNA export in a greater than additive manner. Utilizing deletion, mutation and co-variational analyses, we have identified three regions important for full HPRE activity. The three separate regions of the HPRE function can function independently in a dose-dependent manner when multimerized. Two of these regions contain stem loops, HSLalpha and HSLbeta1, which are necessary for full HPRE function. These structures are conserved throughout the mammalian Hepadnaviruses. Disruption of either stem-loop structure by mutagenesis decreases HPRE function while compensatory mutations restore activity. The location of the stem-loops in the genome reveal that they are present in all of the HBV transcripts. HSLalpha and HSLbeta1 are likely to contain the binding sites for the cellular factor(s) which mediates HPRE function.

Experience with color-coded duplex sonography after combined kidney/pancreas transplantation--preliminary results

The value of color-coded duplex sonography in the assessment of combined kidney and pancreatic transplantations (KTX/PTX) was studied in 9 patients. In normal graft function the median resistive index (RI) was 0.69 (range 0.60-0.80) for the kidney and 0.61 (range 0.55-0.70) for the pancreas. Ten episodes of graft dysfunction (kidney n = 4; pancreas n = 6) were observed. During renal rejection and hemolytic uremic syndrome the RI was above 0.80. In pancreatic rejection the RI exceeded 0.80 while all other causes of pancreatic dysfunction were not associated with changes in the RI. Color-coded duplex sonography may prove to be a reliable noninvasive diagnostic method in the evaluation of the posttransplant course after combined KTX/PTX, in particular in the diagnosis of pancreatic rejection.

Thermodynamic prediction of conserved secondary structure: application to the RRE element of HIV, the tRNA-like element of CMV and the mRNA of prion protein

An algorithm for prediction of conserved secondary structure of single-stranded RNA is presented. For each RNA of a set of homologous RNAs optimal and suboptimal secondary structures are calculated and stored in a base-pair probability matrix. A multiple sequence alignment is performed for the set of RNAs. The resulting gaps are introduced into the individual probability matrices. These homologous probability matrices are summed to give a consensus probability matrix emphasizing the conserved secondary structure elements of the RNA set. Thus the algorithm combines the advantages of thermodynamic structure prediction by energy minimization with the information obtained from phylogenetic alignment of sequences. The algorithm is applied to three examples. The REV-responsive element of HIV, the structure of which is well known from the literature, was chosen to test the algorithm. The second example is the 3' terminal segment of genomic single-stranded RNAs of cucumber mosaic viruses; a structure similar to that of the related brome mosaic virus was expected and was confirmed. The third example is the prion-protein mRNA from different organisms; the structure of this mRNA is not known. By application of the algorithm highly conserved hairpins were found in the prion-protein mRNA.