After Intestinal Transplantation Kidney Function Is Impaired by Downregulation of Epithelial Ion Transporters in the Ileum.

BACKGROUND: Intestinal transplantation is a treatment option for intestinal failure. Although nephrotoxic medication after transplantation is a major cause for posttransplant renal insufficiency, it remains unclear why kidney dysfunction is particularly frequent after intestinal transplantation. METHODS: This study analyzed messenger RNA expression of NHE3, DRA, and CFTR in 404 biopsies obtained between day 2 and 1508 from the terminal ileum of 10 adult intestinal transplant recipients. RESULTS: The time courses of immunosuppression and glomerular filtration rate were correlated. In the first posttransplant year, expression of NHE3 and DRA, which mediate NaCl absorption, was diminished to a greater degree than that of CFTR, which mediates chloride secretion. Reduced NHE3 and DRA expression was associated with high tacrolimus trough levels. Titration of tacrolimus to low levels by year 2 was paralleled by partially restored NHE3 and DRA expression. In cell culture experiments, similar effects of tacrolimus on transporter expression were detected. In patients, both reduced tacrolimus levels and recovery of NHE3 and DRA expression were associated with stabilization of renal function. CONCLUSIONS: Our data strongly suggest that tacrolimus impairs absorption of NaCl and water from the transplanted ileum, leading to volume depletion and impaired renal function. This may be reversible by reduction of tacrolimus to lower levels without increased rates of rejection or chronic graft failure.

[Anti-angiogenic therapy for gastrointestinal tumours]. / Antiangiogene Therapie gastrointestinaler Tumoren.

New therapeutic strategies that notably lack cross resistance with established treatment regimens are much needed in gastroenterological oncology. One such approach is therapeutic anti-angiogenesis which aims at the inhibition of vasculature growth in solid tumours. Since numerous gastrointestinal tumours show strong tumour neoangiogenesis and consequently are highly vascularised, anti-angiogenic therapies will play a pivotal role in tomorrow's gastroenterological oncology. Hence, this review covers (i) basic mechanisms of tumour angiogenesis, (ii) recent anti-angiogenic strategies in the field of gastroenterological oncology as well as (iii) a discussion of their current limitations and perspectives.

Safe treatment of thiopurine S-methyltransferase deficient Crohn's disease patients with azathioprine.

Thiopurine S-methyltransferase (TPMT) deficient patients develop life threatening haematotoxicity (for example, pancytopenia) when treated with a standard dose of azathioprine (AZA) and 6-mercaptopurine (6-MP) due to excessive accumulation of cytotoxic metabolites. At present, it is generally recommended that these patients should not receive AZA or 6-MP treatment for inflammatory bowel disease. We report for the first time that Crohn's disease patients with TPMT deficiency can be successfully treated with AZA. We illustrate this with three cases where treatment has been successful and toxicity has been avoided by carefully titrating the drug dose. Thus very low TPMT activity demands pharmacogenetically guided dosing.

Enhanced suicide gene effect by adenoviral transduction of a VP22-cytosine deaminase (CD) fusion gene.

The low transduction efficiency of viral and nonviral vectors is a major limitation in tumour gene therapy. The HSV-1 tegument protein VP22 has been shown to exhibit a novel intercellular transport property. VP22 wild-type as well as VP22 fusion proteins efficiently spread from the original expressing cell to numerous neighbouring cells, so that protein transport by VP22 chimaeric polypeptides into the surrounding cells offers a possible compensation for the inadequate gene transfer efficiencies. To improve the therapeutic efficacy of the E. coli cytosine deaminase (CD) suicide gene we made use of the VP22 transport property in CD transducing adenoviral (Ad) vectors. C- and N-terminal fusions of CD linked in-frame with VP22 were generated and cloned into recombinant adenoviral vectors. Following in vitro transduction immunofluorescence analysis of Ad-transduced producer cells coplated with naive cells confirmed that the characteristic foci pattern of central producer and adjoining neighbour cells displaying nuclear staining was retained. After transduction of rat hepatoma cells with adenoviral vectors and subsequent incubation with the prodrug 5-FC, we observed enhanced cell cytotoxicity when comparing the CD-VP22 fusion (Ad-CD-VP22) with Ad-vectors expressing the CD gene only (Ad-CD). Thereby employment of Ad-vectors encoding VP22 fusion proteins opens up new possibilities to potentiate the efficiency of suicide gene therapy for the treatment of solid tumours.

Growth characteristics and imaging properties of the morris hepatoma 3924A in ACI rats: a suitable model for transarterial chemoembolization.

PURPOSE: For experimental studies investigating modalities and efficacy of transarterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) an animal model resembling the human situation as closely as possible would be appropriate. Specifically, reproducible tumor growth characteristics with the capability for appropriate in vivo imaging to monitor treatment efficacy are required. METHODS: Morris hepatoma 3924A was implanted into the liver of 30 ACI rats. Tumor growth was followed by angiography (n = 10), ultrasound (US, n = 30), native computed tomography (CT, n = 16), and native magnetic resonance imaging (MRI, n = 30) between day 8 and day 36 after implantation. The radiological morphological characteristics were compared with the macroscopic and microscopic histological findings of the explanted tumors. RESULTS: In all 30 animals a solitary liver tumor was found and macroscopically no signs of metastases, ascites, or peritoneal tumor were visible. On histopathological examination tumor sizes ranged between 27 +/- 3 mm(3) (day 8) and 3468 +/- 79 mm(3) (day 36). The first signs of tumor necrosis occurred at day 16. US allowed tumor visualization from day 8, MRI from day 8, angiography from day 10, and CT from day 14. CONCLUSIONS: The tumor model has the potential to be used for the visualization of tumor growth by MRI and US. The potential for monitoring therapeutic effects of TACE needs to be investigated.

[Animal experiment studies on the effectiveness of permanent occlusion of the hepatic artery in transarterial chemoembolization]. / Tierexperimentelle Untersuchungen zur Effektivität der permanenten Okklusion der Arteria hepatica bei der Transarteriellen Chemoembolisation.

PURPOSE: To evaluate the effect of permanent occlusion of the hepatic artery on the efficacy of transarterial chemoembolization (TACE) in an animal model. MATERIAL AND METHODS: 12 days after inoculation of the Morris hepatoma 3924 A in 15 male ACI rats, TACE with Mitomycin C (0.25 mg/kgBW) + Lipiodol (0.2 ml/kgBW) without (n = 5) and with permanent occlusion of the hepatic artery (n = 5) was performed. Control group consisted of 5 rats. Tumor volume was determined by MRI (1.0 T, T1 [TR/TE, 400/14 ms]) before and 12 days after therapy. RESULTS: Compared to the control group, TACE without and with permanent occlusion of the hepatic artery showed a significant reduced tumor growth after 12 days (p = 0.017 and p = 0.005). However, permanent occlusion did not improve the retarding effect on tumor growth (p = 0.9). CONCLUSION: The effectiveness of TACE in an animal model using a cytostatic-/lipiodol-emulsion is not improved by permanent occlusion of the hepatic artery.

Magnetic cell sorting for parietal cell purification using a new monoclonal antibody without influence on cell function.

Conventional isolation protocols for the parietal type of the gastric mucosal cell population are based on physical criteria such as cell size and cell density. Time-consuming centrifugation techniques are required, which decrease the overall yield and exert a negative influence on the functional integrity of purified cells. As an alternative, we now have developed a phenotype-dependent magnetic selection method. A monoclonal antibody (P1.4D5) was raised against rat parietal cells. After immunohistochemical, biochemical and functional characterization, P1.4D5 was used for rapid antibody-mediated magnetic cell sorting (MACS) of enzymatically dispersed gastric mucosal cells, which resulted in a 2.2- to 3-fold enrichment of parietal cells. Characterization of P1.4D5 demonstrated its applicability for parietal cell-specific immunostaining of formalin treated and paraffin-embedded tissue samples and cryosections from both rat and man. In vitro studies of the 14C-aminopyrine accumulation showed no intrinsic effect of P1.4D5 on the acid production of the parietal cell or on the histamine-stimulated acid production. This absence of negative influence on the parietal cell function qualifies P1.4D5 for immunomagnetic cell sorting procedures.