Thorsten Pohle

Heme oxygenase-1 induction may explain the antioxidant profile of aspirin

Aspirin is known to exert antioxidant effects by as yet unidentified mechanisms. In cultured endothelial cells derived from human umbilical vein, aspirin (30-300 microM) increased heme oxygenase-1 (HO-1) protein levels in a concentration-dependent fashion up to fivefold over basal levels. HO-1 induction was accompanied by a marked increase in catalytic activity of the enzyme as reflected by enhanced formation of both carbon monoxide and bilirubin. Pretreatment with aspirin or bilirubin at low micromolar concentrations protected endothelial cells from hydrogen peroxide-mediated toxicity. HO-1 induction and endothelial protection by aspirin were not mimicked by indomethacin, another inhibitor of cyclooxygenase. The nitric oxide (NO) synthase blocker L-NAME prevented aspirin-dependent HO-1 induction. These findings demonstrate that aspirin targets HO-1, presumably via NO-dependent pathways. Induction of HO-1 expression and activity may be a novel mechanism by which aspirin prevents cellular injury under inflammatory conditions and in cardiovascular disease.

Identification of metastasis-associated receptor tyrosine kinases in non-small cell lung cancer.

Development of distant metastasis after tumor resection is the leading cause of death in early-stage non-small cell lung cancer (NSCLC). Receptor tyrosine kinases (RTK) are involved in tumorigenesis but only few RTKs have been systematically studied in NSCLC. Here, we provide quantitative real-time reverse transcription-PCR expression data of all RTKs (n=56) in primary tumors of 70 patients with early-stage (I-IIIA) NSCLC. Overall, 33 RTKs were expressed in at least 25% of the patients. Several RTKs were significantly expressed higher in tumors that ultimately metastasized. The hazard risk for metastasis development in stage I/II disease was increased at least 3-fold for tumors with high expression levels of insulin receptor, neurotrophic tyrosine receptor kinase 1, epidermal growth factor receptor, ERBB2, ERBB3, platelet-derived growth factor receptor beta, fibroblast growth factor receptor 1, or leukocyte tyrosine kinase. Relative risks were reduced 3-fold by expression of EPHB6 or DKFZ1. Three members of the epidermal growth factor receptor family were associated with a high risk of metastasis, emphasizing the validity of our data. High ERBB3 expression was significantly associated with decreased survival. Taken together, our genome-wide RTK expression map uncovered the previously unknown value of several RTKs as potential markers for prognosis and metastasis prediction in early-stage NSCLC. The identified RTKs represent promising novel candidates for further functional analyses.

Colonic expression of heme oxygenase-1 is associated with a better long-term survival in patients with colorectal cancer

Objective. Heme oxygenase-1 (HO-1) has emerged as a crucial mediator of mucosal defense in the gastrointestinal tract. Its metabolic pathway products, biliverdin/bilirubin and carbon monoxide, can reduce oxidative stress and inflammation, and promote resistance to apoptosis. The role of HO-1 in gastrointestinal malignancies, however, remains to be elucidated. The purpose of this study was to analyze HO-1 expression in human colon adenoma and cancer samples. Material and methods. Fifty-five paraffin-embedded surgical specimens of colorectal cancer and 19 colonic adenoma samples were stained immunhistochemically for HO-1 expression using an anti-HO-1 monoclonal antibody. HO-1 expression was evaluated independently by two different investigators and subsequently correlated to clinical data and patients’ life expectancy. Results. Focal HO-1 expression could be documented in 41.8% (23/55) of patients with colorectal cancer. HO-1 expression in colonic adenoma was detectable in 36.8% (7/19) of cases. The rate of lymphatic tumor invasion was significantly lower in colorectal cancer samples expressing HO-1 (p=0.048). Additionally, fewer lymph node metastases were found in colorectal cancer samples with HO-1 expression, but these differences did not reach statistical significance. Mean observation period was 65.87±3.96 months. Kaplan-Meier analysis showed a significantly better survival for colorectal cancer patients with colonic HO-1 expression (p=0.018). Conclusions. This study demonstrates that colonic HO-1 may be a prognostic marker of colorectal-cancer outcome.

Biological in vitro effects of fibrin glue: fibroblast proliferation, expression and binding of growth factors

Background: Fibrin glue is used in the endoscopic therapy of bleeding ulcerations. Accelerated closure of ulcers has been documented for this treatment in comparison with other injection techniques; the biological reason, however, remains unclear. Methods: In an in vitro model the effects of fibrin glue on the expression and secretion of growth factors by gastric epithelial (AGS, KATO III) and mesenchymal cells (fibroblasts) as well as their proliferative response and their interaction were compared with those of other matrices. Results: Native fibrin glue does not release vascular endothelial growth factor (VEGF) but is able to bind this growth factor in biologically relevant concentrations of 152.6 pg/mL. The addition of fibrin glue to a collagen type I matrix led to an increased proliferation rate of gastric wall fibroblasts. The transcription of VEGF and platelet‐derived growth factor (PDGF) mRNA was significantly increased in epithelial cells. Co‐culture of fibroblasts grown on fibrin glue containing matrix and epithelial cells resulted in an increased secretion of VEGF by both cell lines. Conclusions: Fibrin glue leads to increased proliferation of fibroblasts and local accumulation of VEGF. These findings might at least partly explain the accelerated closure of bleeding ulcers treated by fibrin glue injection.

Fibrin glue, healing of gastric mucosal injury, and expression of growth factors: results from a human in vivo study

BACKGROUND Fibrin glue is used in the endoscopic therapy of bleeding ulcerations. Accelerated closure of ulcers has been attributed to this treatment; the biologic reason, however, remains unclear. METHODS Two artificial gastric lesions were induced in healthy, Helicobacter pylori negative volunteers and were treated by injection of either saline solution or fibrin glue. After 72 hours, resulting ulcers were measured and biopsy specimens were taken for immunohistochemistry (to identify proliferating cells and small vessels) and assessment of growth factor messenger RNA (mRNA) expression (platelet derived growth factor, vascular endothelial growth factor, fibroblast growth factor 2 [FGF-2]) by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS After 72 hours, most lesions exposed to fibrin glue were smaller than the corresponding ones treated with saline solution. The ulcer rim was more pronounced; immunohistochemistry revealed more proliferating cells (p < 0.02 compared with saline solution). The number of microvessels also increased, though this difference did not reach statistical significance (p = 0.10). FGF-2 mRNA expression markedly increased (about 7-fold compared with the control [ p < 0.001], and about 5-fold compared with saline solution [ p < 0.015]); whereas, with respect to platelet derived growth factor and vascular endothelial growth factor mRNAs, only small changes occurred. CONCLUSIONS Fibrin glue positively modulates gastric ulcer healing by causing an increase in the number of proliferating cells in the ulcer margin and also possibly enhances the density of microvessels. These changes are accompanied by an enhanced expression of FGF-2, which is known to exert beneficial effects on ulcer healing.

Minocycline and fulminant hepatic failure necessitating liver transplantation

encephalopathy, severe upper gastrointestinal bleeding, and hypovolemic shock. The diagnosis of drug-induced hepatitis is based on the documentation of the expected temporal relation between drug administration and the appearance of the clinical picture, as well as compatible histopathological findings, and requires a careful exclusion of all other causes of liver injury (6). In our patient, they were extensively excluded, namely, infectious or autoimmune hepatitis as well as alcoholic and metabolic liver disease. Moreover, there was a temporal relationship between drug intake and the onset of symptoms, and the findings of liver biopsy showing an acute hepatitis with confluent necrosis, inflammatory infiltrates containing eosinophils, and cholestasis were highly suggestive of drug hypersensitivity liver injury. None of the four drugs potentially implicated is known to have intrinsic dose-dependent hepatic toxicity and, of these, only ranitidine has been described in association with dose-independent idiosyncratic liver injury. These rare instances consisted of selflimited acute hepatitis with remission of the elevated aminotransferases levels upon discontinuation of the drug (1–3), and only one case of fatal hepatic failure possibly associated with ranitidine has been reported (4). Therapy with ranitidine was not initially stopped in our patient, because it is not usually considered as a cause of drug-induced hepatitis. We admit that continued exposure to the drug, particularly after the appearance of the liver injury, has probably contributed to the severity of the lesion and, ultimately, to its fulminant clinical course. This case represents the second reported case of fatal hepatic failure associated with ranitidine and emphasizes the need to include all drugs as possible candidates, even the one that are extremely rare causes of non dose-dependent liver injury.

Endoluminal gastroplasty (EndoCinch) versus endoscopic polymer implantation (Enteryx) for treatment of gastroesophageal reflux disease: 6-month results of a prospective, randomized trial.

OBJECTIVES:The aim of this study was to compare and determine the efficiency and safety of two newly introduced endoscopic antireflux procedures in the treatment of gastroesophageal reflux disease (GERD).METHODS:In a prospective, randomized trial, endoluminal gastroplasty (EndoCinch™) was compared with polymer injection (Enteryx™) employing 51 consecutive patients dependent on proton pump inhibitor therapy. Follow-up evaluation included drug consumption, symptoms, quality-of-life scoring, endoscopy, pH monitoring, manometry, and documentation of adverse events.RESULTS:Twenty-six patients were assigned to EndoCinch™ treatment, 23 patients received Enteryx™ implantation, and two patients dropped out before applying endoscopic therapy. At 6 months, proton pump inhibitor therapy could be stopped or dosage was reduced by ≥50% in 20 of 26 (77%) EndoCinch-treated patients and in 20 of 23 patients treated by Enteryx™ (87%, P = 0.365), which differed significantly in both groups compared to the pre-interventional status (p < 0.0001). Esophageal acid reflux (pH < 4) decreased from 14.5% to 9.6% in EndoCinch-treated patients (P = 0.071) and from 15.5% to 13.9% in patients treated by Enteryx™ (P = 0.930). Heartburn symptom score, modified DeMeester score, gastrointestinal life quality index, and SF-36 physical health survey score improved significantly in both groups postinterventionally (p < 0.0001). Approximately 25% of the patients in both groups required retreatment in an attempt to achieve symptom control.CONCLUSIONS:This is the first prospective, randomized study directly comparing two endoscopic anti-GERD techniques. EndoCinch™ and Enteryx™ seem to be equally successful in the treatment of GERD significantly reducing the proton pump inhibitor dosages, and also by improving symptoms of patients. Both endoluminal antireflux procedures may be promising therapeutic options; long-term evaluation will have to show if the positive initial results can be maintained.

Duodenal duplication cyst mimicking pancreatic cyst in a patient with pancreatitis.

Pancreatic pseudocyst is a common complication of pancreatitis that often confounds patient management. Reported here is a case of an enteric duplication cyst within the duodenal wall of a 16-year-old boy that lead to recurrent episodes of pancreatitis because of intermittent obstruction of both the bile duct and the pancreatic duct. The cyst was the cause and not the result of pancreatic inflammation.

Expression of type I and IV collagen mRNAs in healing gastric ulcers--a comparative analysis using isotopic and non-radioactive in situ hybridization.

The sensitivity and practicability of in situ hybridization methods utilizing isotopic or non-radioactive labeling were compared. The aim of this study was to determine whether digoxigenin-labeled riboprobes are as sensitive as35S-labeled probes to detect changes in type I and IV procollagen expression in an animal model of rat gastric ulcer. Both labeling and detection methods yielded similar results, with a superimposable signal distribution in the specimens. High levels of procollagen type I and IV transcripts were observed in spindle-shaped cells, presumably fibroblasts or myofibroblasts, localized in the ulcer base and rim. The increased expression of these collagen types suggests a remarkable upregulation of collagen expression during the healing of gastric ulcers. Liver tissue adhering to perforated ulcers displayed signals related to non-parenchymal cells, with hepatocytes demonstrating no detectable transcripts of type I or IV collagen genes. Due to the identical pattern of signal distribution by both hybridization techniques it is concluded that non-radioactive in situ hybridization is of value in monitoring highly expressed genes and yields results similar to those achieved with radioactive probes. In these cases, non-radioactive techniques are preferable because they are performed more rapidly and do not require handling of isotopes.

Evidence of de novo collagen synthesis in healing human gastric ulcers

BACKGROUND The fibrillar collagens, types I and III, have been demonstrated in healthy human gastric mucosa as well as in the submucosa of gastric ulcer edges, where they are remarkably increased. METHODS To verify the occurrence and activity of de novo collagen synthesis, we examined gastric biopsy specimens from six patients with antral ulcers and six normal controls. By means of in situ hybridization, using a 35S-labeled RNA probe, we could localize the specific procollagen mRNA for type-I collagen. RESULTS In normal gastric mucosa this mRNA was expressed by only a very limited number of cells, whereas at the ulcer edges the specific signal could be demonstrated in a large number of submucosal cells. CONCLUSION These results suggest a substantial role of fibroneogenesis in the process of gastric ulcer healing.