International journal of pancreatology : official journal of the International Association of Pancreatology最新文献

Background: Phospholipase A2 (PLA2) may play a central role in the pathogenesis of pancreatic acinar cell necrosis. Several questions, however, are unsolved: Is acinar cell necrosis caused by PLA2 derived from infiltrating leukocytes or from pancreatic PLA2 itself? Does PLA2 cause cellular lysis by the release of lysolecithin from lecithin or by generation of free radicals? The aims of this study were to determine which form of PLA2 is responsible for cellular damage and how to inhibit its action.

Methods: Isolated rat pancreatic acini were prepared by collagenase digestion. Newly synthesized proteins were labeled by 35S-methionine. Acini were incubated in buffer to which various factors, such as porcine pancreatic PLA2 or bee venom PLA2, homogenates of either leukocytes or pancreatic homogenates, all with or without lecithin and with or without potential inhibitors (aprotinin, 4-bromophenacylbromide, BM 16.2115, quinacrine, various analogs of arachidonic acid), or free radicals (hydrogen peroxide, xanthine/ xanthine oxidase) with or without allo-purinol or dismutase/catalase were added. Cellular destruction was measured by the release of radiolabeled proteins.

Results: PLA2 alone, free radicals, and granulocytes were not harmful to acini within 30 min of incubation. Free radicals caused significant release of radiolabeled proteins only after 3 h of incubation; this release could be inhibited by scavengers. Incubation of pancreatic acini with PLA2 in combination with lecithin caused rapid release of radiolabeled proteins. Addition of high concentrations of enterokinase activated pancreatic homogenates both alone and with lecithin caused release of cellular proteins, suggesting that pancreatic PLA2 uses lecithin from pancreatic membranes as substrate. Almost all tested potential inhibitors of PLA2 were unable to prevent the destruction caused by either pancreatic or bee venom PLA2 and lecithin. However, HK 42, a polyunsaturated fatty acid analog, was able to reduce dose dependently the release of acinar proteins caused by pancreatic PLA2 and lecithin.

Conclusion: Pancreatic PLA2 and not PLA2 from infiltrating leukocytes may play a role in pancreatic acinar cell necrosis. Cellular lysis is caused upon the action of lysolecithin and probably not via the action of free radicals.

Background: The tetra-acetate ester of 2-deoxy-D-glucose was recently found to either inhibit or augment insulin secretion, depending on the concentration of the ester. Both the positive and negative insulinotropic actions of the ester display anomeric specificity.

Methods: The effects of the alpha- and beta-anomer of 2-deoxy-D-glucose tetra-acetate (5.0 mM) on the metabolism of D-[5-3H]glucose and D-[U-14C]glucose (8.3 mM) were investigated in isolated rat pancreatic islets.

Results: Both the alpha- and beta-anomers of 2-deoxy-D-glucose tetra-acetate inhibited the generation of 3HOH from D-[5-3H]glucose and that of 14CO2, as well as radioactive acidic metabolites and amino acids, from D-[U-14C]glucose. They also lowered the paired ratio between D-[U-14C]glucose oxidation and D-[5-3H]glucose utilization. No significant anomeric difference could be detected, however, in these experiments.

Conclusions: The effects of the alpha- and beta-anomer of 2-deoxy-D-glucose tetra-acetate on the metabolism of D-glucose in isolated rat pancreatic islets reinforce the view that the insulinotropic action of monosaccharide esters involves a dual mode of action, linked to both the metabolic effects of their glucidic moiety and a direct interaction of the esters themselves with a stereospecific receptor system.

Background: Severity of pancreatitis seems to be aggravated by impairment of vascular perfusion of the gland. Early mortality occurs within the first few days from the acute consequences of pancreatic injury with subsequent inflammatory response. Because vasoactive substances, including endothelin, seem to contribute to early mortality in acute pancreatitis, we tested the hypothesis that the inhibition of endothelin action could alter the outcome after severe experimental pancreatitis.

Methods: In two groups of rats, pancreatitis was induced by intraductal infusion into the pancreatic duct of 1 microL/g body weight (b.w.) of either a 4% or a 5% sodium taurocholate solution. The mixed endothelin A and endothelin B receptor antagonist bosentan (20 mg/kg b.w.) or vehicle was injected intravenously in 12-h intervals for 3 d starting 1 h after induction of bile acid pancreatitis. This dose of bosentan is known to completely inhibit the effect of exogenous endothelin. The survival rate was monitored for 7 d. Thereafter, the surviving rats were sacrificed and the pancreas was prepared for histological and biochemical evaluation.

Results: Irrespective of the treatment protocol (bosentan versus saline), survival was not different in animals challenged with either 4% or 5% sodium taurocholate. The corresponding survival rates were 62% with bosentan and 77% without bosentan in the 4% sodium taurocholate group. In the 5% sodium taurocholate group, the survival rates were 20% with and 27% without bosentan. Morphological and biochemical alterations were identical in control as well as in endothelin-antagonist-treated rats.

Conclusion: Therapy with the mixed endothelin A and endothelin B receptor antagonist bosentan does not influence the outcome after severe experimental pancreatitis. Therefore, blockade of endothelin A and B receptor subtypes may not be of major importance as a therapeutic principle in this model of experimental pancreatitis.

Background: The interaction between immunocompetent cells and tumor endothelium is essential for an effective immunological response. In the present study, we evaluated resting and CD11b/CD18-mediated leukocyte adhesion in tumor vessels of experimental pancreatic cancer and in healthy pancreatic venules in the rat.

Methods: Solid tumor fragments (1 mm3) were interposed intrapancreatically between inert transparent polymethylmetacrylate plates for intravital microscopy (n = 12) by which tumor microcirculation, leukocyte-tumor-endothelium interaction, and the effect of the chemoattractants N-formyl-methioninleucylphenylalanine (fMLP) and platelet-activating factor (PAF) on leukocyte adherence was investigated.

Results: Leukocyte adhesion in pancreatic tumor vessels was significantly reduced compared to healthy pancreatic venules. Both fMLP and PAF dramatically increased leukocyte adherence in normal pancreatic venules. No change in leukocyte adhesion was present in tumor vessels after exposure to these chemotactic substances.

Conclusion: Resting and stimulated integrin-dependent leukocyte adhesion is strongly reduced in malignant vessels of experimental pancreatic cancer, which may be an important mechanism to escape immune control.

Background: Diagnosis of pancreatic cancer is usually made by endoscopic retrograde cholangiopancreatography (ERCP) and corresponding findings in computed tomography (CT) or magnetic resonance imaging. Kaposi's sarcoma, a frequent tumor in individuals with a late-stage HIV infection, can be located in the gastrointestinal tract and cause identical symptoms to carcinoma of the same site. A close correlation of this tumor to human herpes virus 8 (HHV 8) has been known for several years and there are reports of successful antiproliferative therapy.

Methods: Aspirated pancreatic juice and bile was investigated for the presence of HHV 8 by polymerase chain reaction. The clinical course of the patient under antiviral therapy and treatment with paclitaxel was studied.

Results: A 47-yr-old HIV-infected man with a history of Kaposi's sarcoma of skin and lungs caused by obstructive jaundice in the years before was admitted. ERCP showed a typical double-duct sign and CT revealed a tumorous infiltration of the pancreatic head, highly suspicious for pancreatic adenocarcinoma. A mutation of the ki-ras gene could be ruled out and molecular analysis of bile identified HHV 8 by PCR. Intensive antiviral therapy, including foscarnet and treatment with paclitaxel led to a complete remission within 8 m.o.

Conclusion: Kaposi's sarcoma of the pancreas possibly mimics pancreatic cancer in HIV-infected subjects. Diagnosis may be made by identification of HHV 8 in pancreatic juice or bile, and successful clinical outcome is possible by intensive antiviral and cytostatic treatment with paclitaxel.

Objectives: Given the appearance of pancreatitis attributed to tetracycline, as described in the literature, we have investigated its effect on the enzymatic content of pancreas and duodenal fluid and on pancreatic ultrastructure. We have evaluated possible differences between sexes and the relation of our findings with those described in the initial phases of acute pancreatitis, in the context of the acinar hypothesis.

Methods: With 128 Wistar rats (63 male and 65 female), 3 groups were established: control (group I) experimental animals treated with oxytetracycline intramuscularly, 15 and 30 mg/kg/d (groups II and III, respectively). Before sacrifice, half of the rats in each group were stimulated with cholecystokinin. Blood, pancreatic tissue (for enzyme dosage and morphological study), and duodenal fluid were extracted following anesthesia.

Results: The stimulated males of group III presented lower amylase levels in pancreatic tissue and duodenal fluid (P < 0.003). Just the opposite occurred in female rats. A similar tendency was observed with other enzymes (lipase and trypsin). Zymogen granule counts, appearance of immature granules, and dilation of ergastoplasm were more frequent in the stimulated animals.

Conclusions: Oxytetracycline seems to induce morphofunctional changes in rat pancreas, which differ according to sex. In the female, enzyme accumulation that could predispose intracellular activation seems to exist, as well as the ultrastructural findings described in initial phases of acute experimental pancreatitis. This agrees with the greater frequency of pancreatitis in women undergoing tetracycline treatment described in the literature. In contrast, for males the findings were more compatible with decrease of protein synthesis. This would make them less susceptible to crinophagy phenomena and, thus, to acute pancreatitis in the context of the acinar or lysosome hypothesis.

Background: It has been suggested that early localization of both necrosis and extrapancreatic fluid collections by contrast-enhanced computed tomography (CT) can predict the outcome in severe acute pancreatitis. These two assumptions were evaluated.

Patients and methods: This study comprises 228 patients with a first attack of acute pancreatitis admitted to our clinic from 1987 to 1995 and for whom the prognostic value of a contrast-enhanced CT obtained within 72 h of admission was prospectively evaluated. These CTs were retrospectively re-evaluated for the localization of pancreatic necrosis and extrapancreatic fluid collections. The indication for dialysis and artificial ventilation, the development of pancreatic pseudocysts, the necessity for surgery (necrosectomy), and mortality were used as clinical parameters.

Results: There was a significant correlation between the presence of pancreatic necrosis and extrapancreatic fluid collections versus the clinical parameters. The localization of pancreatic necrosis was of no importance for the outcome of the disease, whereas the increasing amount of extrapancreatic fluid collections paralleled the severity of acute pancreatitis.

Conclusion: Pancreatic necrosis and extrapancreatic fluid collections are indicators for severe acute pancreatitis. Whereas the localization of pancreatic necrosis is not important for the outcome of the disease, the extent of extrapancreatic fluid collections is significantly correlated with a severe course.

Background: Recent data provide evidence of a systemic inflammatory response in severe acute pancreatitis; in contrast, the exact immune mechanisms underlying chronic pancreatitis remain unclear.

Methods: To investigate the immune response in the clinical features of chronic pancreatitis, we investigated the gene expression of tumor necrosis factor-alpha (TNF-alpha), tumor necrosis factor receptor (TNFR)-p55 and -p75 and inducible nitric oxide synthase (iNOS) in peripheral blood mononuclear cells (PBMC) of 18 patients with late-stage alcoholic chronic pancreatitis of different disease activity (Balthazar criteria).

Results: Semiquantitative reverse transcriptase-polymerase chain reaction revealed a significantly enhanced gene expression of TNF-alpha (P < 0.05), TNFR-p55 (P < 0.05) and TNFR-p75 (P < 0.01) in unstimulated PBMC of patients with advanced chronic pancreatitis (11/18 with calcifications) compared to healthy controls (n = 8). No significant difference was found between patients with mild acute pancreatitis and patients with an inactive quiescent pancreatitis. Moreover, no expression of inducible nitric oxide synthase was detectable.

Conclusions: The enhanced gene expression of TNFR-p75, TNFR-p55 and TNF-alpha in unstimulated PBMC demonstrates an enhanced leucocyte activation in patients with late-stage chronic pancreatitis and suggests a pathogenetic role of the cytotoxic TNF-alpha pathway in the clinical features of alcoholic chronic pancreatitis. The pathogenetic role of nitric oxide in chronic pancreatitis remains to be fully elucidated.

Background: Neural invasion is known to be one of the aggressive characteristics of pancreatic adenocarcinoma. However, there have been no systematic studies on intraoperative examination of neural invasion of pancreatic carcinomas after wide dissection of the retroperitoneum, particularly at the surgical margin.

Methods: We performed intraoperative immunostaining on the frozen sections of several excised plexus specimens, using peroxidase-labeled anti-cytokeratin 19 antibody in 17 cases of resectable pancreatic carcinoma. Postoperatively, we also tried to detect occult micrometastasis by direct sequencing of the K-ras gene in the same samples.

Results: Intraoperative staining for cytokeratin 19 was positive in 4 of 17 (23.5%) cases. Patients with margin-positive neural invasion had significantly worse prognosis than patients who were margin negative (P < 0.05). One patient had micrometastasis in the nerve plexus, revealed by K-ras mutation, whereas neither cytokeratin 19 staining nor postoperative pathological investigation detected involvement of the analyzed portion. In the four patients margin-positive for cytokeratin 19 staining, the diagnosis of neural invasion by cytokeratin 19 staining was in agreement with the K-ras gene analysis.

Conclusion: Intraoperative staining for cytokeratin 19 is useful for detecting pancreatic cancer involvement of the neural plexus margin. The results can be also utilized as a prognostic indicator during the follow-up period.