Antiviral therapy for hepatitis C virus recurrence after liver transplantation in HIV-infected patients: outcome in the Bonn cohort.

Recurrent hepatitis C is a major cause of mortality in HIV/hepatitis C virus (HCV)-co-infected patients after orthotopic liver transplantation. We report sustained viral clearance in all four transplanted HIV/HCV-positive patients treated with pegylated interferon/ribavirin. Early therapy after HCV recurrence, tailoring treatment duration to the individual decline in HCV-RNA and the management of side effects are key factors for improved efficacy. At experienced centres interferon treatment is a valuable option for recurrent hepatitis C in HIV-positive patients.

Polyclonal evolution of multiple secondary KIT mutations in gastrointestinal stromal tumors under treatment with imatinib mesylate.

Gastrointestinal stromal tumors (GIST) are characterized by a strong KIT receptor activation most often resulting from KIT mutations. In a smaller subgroup of tumors without KIT mutations, analogous activating mutations are found in the platelet-derived growth factor receptor alpha (PDGFRalpha) gene. Both PDGFRalpha and KIT receptors are targets of the tyrosine kinase inhibitor imatinib (Glivec) which has improved the treatment of advanced GISTs significantly. However, a subgroup of tumors show a secondary progress under therapy with imatinib after initial response. One possible mechanism of secondary resistance is the development of newly acquired KIT mutations. In the present study, we evaluated the frequency of such secondary KIT mutations in a series of GIST patients in which tumor tissue was resected under treatment. We examined one to seven different tumor areas in 32 cases (total of 104 samples) and found up to four newly acquired KIT mutations in 14 patients (43.8%). These were always located in exons encoding the first or second tyrosine kinase domain (exon 13, 14, or 17). Mutations were found only in a subset of samples analyzed from each case whereas others retained the wild-type sequence in the same region. There was never more than one new mutation in the same sample. Consistent with a secondary clonal evolution, the primary mutation was always detectable in all samples from each tumor. According to our results, the identification of newly acquired KIT mutations in addition to the primary mutation is dependent on the number of tissue samples analyzed and has high implications for further therapeutic strategies.

Inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) expression in fulminant hepatic failure.

BACKGROUND/AIMS: Inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) have important functions in inflammation and vasoregulation but their role in fulminant hepatic failure (FHF) is not well understood. METHODS: Intrahepatic in situ staining and semi-quantification of iNOS and eNOS by immunohistochemistry in 25 patients with FHF, in 40 patients with chronic liver diseases (CLD) and in ten normal controls (NC). RESULTS: Expression patterns of iNOS and eNOS differed. While in NC only faint iNOS expression was found in some Kupffer cells/macrophages and hepatocytes, eNOS was expressed constitutively in sinusoidal and vascular endothelial cells. In CLD, iNOS expression was induced in Kupffer cells/macrophages and hepatocytes, representing the main iNOS expressing cell types. Additionally, bile ducts, vascular endothelial cells and lymphocytes also expressed iNOS (P = 0.001). In contrast, no differences were found between eNOS expression in CLD and NC (P = 0.64). The same cell types expressed eNOS and iNOS in FHF but numbers of both were significantly enhanced, exceeding the levels seen in CLD (P < 0.001, P = 0.017). CONCLUSIONS: Our data demonstrate that iNOS and eNOS are differently regulated in physiologic conditions and in liver disease. While eNOS seems to be involved in the physiological regulation of hepatic perfusion, strong upregulation of iNOS might contribute to inflammatory processes in FHF.

c-kit mutations in gastrointestinal stromal tumors occur preferentially in the spindle rather than in the epithelioid cell variant.

Gastrointestinal stromal tumors (GISTs) coexpress CD34 and the Kit tyrosine-kinase receptor (CD117). A subset of GISTs carry gain-of-function mutations of the c-kit proto-oncogene in its juxtamembrane domain. The relationship between the mutational status and histological as well as immunohistochemical features has not been assessed in detail. 36 GISTs and 14 other gastrointestinal mesenchymal tumors were investigated for their morphology and immunophenotype as well as for the presence of c-kit mutations. DNA was extracted from formalin-fixed, paraffin-embedded tissue. Exons 9, 11, 13, and 17 of c-kit were analyzed by SSCP. Bands with altered mobility were excised, reamplified, and sequenced. C-kit mutations in Exon 11 encoding the juxtamembrane domain were identified in 19 cases (52.8%), with deletions in 12 cases, insertions in 3 cases (2 of these as duplications), and point mutations in 4 cases. The mutations clustered between Codons 553 and 561, pinpointing the critical region for deregulated Kit receptor activation. In both Exons 9 and 13, single mutations could be identified, whereas no mutations were found in Exon 17. There were c-kit mutations in 66.6% of benign GISTs (14/21), 83.3% of the malignant (5/6), and 40% of the cases of intermediate malignancy (2/5). A low frequency of mutations in benign GISTs, as reported previously by other researchers, could not be observed in our panel. Interestingly, all GISTs with c-kit mutations displayed a spindle cell phenotype, whereas mutations were absent in all 7 tumors with an epithelioid component (P =.03). This finding suggests a relationship between c-kit mutation and histological subtype in GISTs.

Selective jejunal manipulation causes postoperative pan-enteric inflammation and dysmotility.

BACKGROUND AND AIMS: Small bowel manipulation initiates an intense molecular and cellular inflammatory response within the jejunal muscularis, which causes ileus. The current objective was to investigate pan-enteric inflammatory molecular and functional motility alterations of the muscularis from the unmanipulated stomach and colon initiated by selective jejunal manipulation. METHODS: Rat jejunum was manipulated, and animals sacrificed between 0-24 hours. In vivo gastric emptying, gastrointestinal transit, and in vitro colonic circular muscle recordings were measured. Reverse-transcriptase polymerase chain reaction (RT-PCR) and electromobility shift assay (EMSA) of gastric, jejunal, and colonic muscularis extracts were performed. Whole mounts were histochemically stained for myeloperoxidase leukocytes. RESULTS: Surgical manipulation suppressed jejunal contractions that were significantly prevented by dexamethasone pretreatment. Selective jejunal manipulation also suppressed in vivo gastric emptying, gastrointestinal transit, and in vitro colonic circular muscle contractility. Nuclear factor interleukin-6 (NF-IL-6) was activated within the gastric and colonic muscularis. RT-PCR showed a 14.9-, 8.1-, and 11.4-fold up-regulation of IL-6 messenger RNA within the jejunal, gastric, and colonic muscularis, respectively. EMSA showed a 30.6-, 14.2-, and 20.8-fold increased activation of signal transducer and activator of transcription (STAT) proteins in jejunal, gastric, and colonic muscularis extracts, respectively. Tumor necrosis factor-alpha, cyclooxygenase-2, and inducible nitric oxide synthase showed a significant up-regulation in the manipulated jejunum, as well as the unmanipulated gastric and colonic muscularis. Neutrophils were significantly recruited into all gastrointestinal regions. CONCLUSION: Selective small bowel manipulation leads to a molecular, cellular, and functional pan-enteric "field effect" phenomenon in the unmanipulated gastric and colonic muscularis.

Deletion of Trp-557 and Lys-558 in the juxtamembrane domain of the c-kit protooncogene is associated with metastatic behavior of gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GISTs) typically express high levels of the Kit-receptor. The majority of GISTs carry mutations in the c-kit protooncogene clustering in exon 11. The significance of c-kit mutations for the biological behavior of GISTs is still under discussion. We evaluated 55 sporadic GISTs with available follow-up data for c-kit mutations in the juxtamembrane domain and detected mutations in 35 cases (63.6%). We found a mutational hotspot in codons 557 (tryptophan) and 558 (lysine) preferentially in histomorphologically malignant tumors. In the group of GISTs carrying c-kit mutations, 16 of 21 malignant, but only 3 of 8 benign GISTs and 3 of 6 lesions with uncertain malignant potential, carried mutations of Trp-557 and/or Lys-558. We investigated whether mutations in these 2 amino acids had an impact on biological behavior. Trp-557 and/or Lys-558 were mutated in all 15 metastatic GISTs carrying c-kit mutations but only in a minority of nonmetastatic tumors. A combined deletion of Trp-557 and Lys-558 occurred exclusively in 8 metastatic GISTs. We conclude that in addition to histomorphological evaluation determination of mutations in exon 11 may be an additional parameter for predicting the metastatic risk of GISTs and may be important for the decision that patients will need close clinical follow-up or further adjuvant treatment with kit antagonists.