S. Benz

Impairment of microcirculation in the early reperfusion period predicts the degree of graft pancreatitis in clinical pancreas transplantation.

Background. Graft pancreatitis is thought to be induced by ischemia/reperfusion. Animal experiments have suggested that an impaired microcirculation is crucial in this process. We have therefore studied the relevance of microcirculation in clinical pancreas transplantation. Methods. In 17 patients undergoing pancreas transplantation, tissue pO2 was monitored continuously by an electrode implanted into the pancreatic tail. A catheter was inserted in the distal part of the splenic vein of the pancreas graft. After reperfusion blood samples were taken from this catheter and blood flow was measured by the venous outflow method. The degree of graft pancreatitis was assessed by peak-C-reactive protein (CRP) defined as highest CRP within 3 days after transplantation. Results. Tissue pO2 increased within 5 min after reperfusion. Thereafter, in most patients a transient decrease was noted, indicating impairment of nutritive perfusion. During this period there was an increasing negative correlation between peak-CRP and tissue pO2 which was highly significant at 60 min after reperfusion (r=−0.70, P <0.002). Also donor age correlated significantly with peak-CRP (r=0.64, P <0.005) and to a somewhat lesser extend with tissue pO2 60 min after reperfusion (r=−0.55, P <0.03). Conclusion. These data show that the degree of organ damage in clinical pancreas transplantation is directly related to an impairment of microcirculation in the early reperfusion period. These data also support the idea that grafts from older donors have a higher probability to develop graft pancreatitis and that this might be due to an increased incidence of microcirculatory disturbances in these organs.

Pancreatic Proteases in Serum Induce Leukocyte-Endothelial Adhesion and Pancreatic Microcirculatory Failure

Background: Neutrophil-mediated tissue injury in acute pancreatitis includes a severe reduction of the functional microcirculation via interaction of adhesion molecules on leukocytes (MAC-1) and endothelium (ICAM-1). The hypothesis of the study was that trypsin and elastase in serum alone lead to the expression of these complementary adhesion molecules and result in increased leukocyte-endothelial interaction (LEI). In addition we evaluated the preventative benefit of protease inhibition on these mechanisms. Materials and Methods: In vitro: Cultured endothelial cells (HUVEC) and human leukocytes (PMN) were stimulated with increasing doses of trypsin and elastase. In addition, pre-treatment of PMN or HUVEC was performed with protease inhibitors (Nafamostat mesilate, FUT and gabexate mesilate, FOY). The expression of ICAM-1 or MAC-1 was evaluated by flow cytometry. In vivo: Severe pancreatitis was induced in rats. Microcirculatory disturbances were evaluated by real-time confocal microscopy at 9 h in controls and acute pancreatitis with or without anti-protease treatment. Additionally, the effect of continuous trypsin and elastase infusion on pancreatic microcirculation and LEI were evaluated by intravital fluorescence videomicroscopy. Results: Up-regulation of MAC-1 and ICAM-1 expression requires the presence of serum. The maximal increase of MAC-1 and ICAM-1 expression was found at concentrations of trypsin or elastase characteristic for acute pancreatitis. FUT or FOY significantly reduced protease-induced expression of MAC-1 and ICAM-1. Real-time in-vivo microscopy revealed that functional capillary density in acute pancreatitis was significantly reduced (267.1 ± 2.95/mm2 vs. 91.29 ± 12.81/mm2) and treatment with FUT significantly reduced this effect (134.6 ± 4.6/mm2; p < 0.05 vs. untreated pancreatitis). Infusion of trypsin or elastase alone increased LEI in vivo and reduced pancreatic perfusion. Conclusion: Both trypsin and elastase up-regulate the expression of adhesion molecules on leukocytes and endothelial cells in the presence of serum. Increased LEI and reduced perfusion of the pancreas, characteristic of acute pancreatitis, is induced in vivo by infusion of pancreatic proteases and this effect is partially abrogated by their inhibitors. These results support the role of circulating trypsin and elastase in promoting pancreatic microcirculatory failure in experimental acute pancreatitis.

High levels of C-reactive protein after simultaneous pancreas-kidney transplantation predict pancreas graft-related complications and graft survival

Background. Although pancreas graft-related complications are frequent after simultaneous pancreas-kidney transplantation (SPK), there are no parameters predicting the risk for these complications. Method. A two-center retrospective study was performed in 97 patients who underwent SPK to investigate the peak serum value of c-reactive protein (CRP) during the first 72 hr after SPK in view of graft-related complications and graft survival. Results. Mean peak CRP was 115.6±71.5 mg/L. Mean peak CRP was higher in patients needing relaparotomy (n=31) (136.4 vs. 105.8 mg/L, P =0.048), especially when postoperative bleeding was excluded (P =0.015); in patients with graft pancreatitis (P =0.03); and in patients with graft loss (n=19; P <0.001) compared with patients without these complications. With a cut-off of peak CRP at the level of mean plus 1 SD (187.05 mg/L), there was a significantly higher incidence of relaparotomies (P =0.01; bleedings excluded:P =0.003), graft pancreatitis (P =0.03), and pancreas graft loss (P <0.0001) in patients with high peak CRP compared with patients with low peak CRP. No differences were noticed with regard to rejection rate, mortality, and kidney graft loss. Conclusion. Our findings suggest that peak CRP is a helpful parameter in predicting pancreas graft-related complications and pancreas graft survival after SPK. Our results also stress the importance of early graft damage in pancreas transplantation.

Expression of Connexin26 in Islets of Langerhans Is Associated With Impaired Glucose Tolerance in Patients With Pancreatic Adenocarcinoma

Objectives: Impairment of glucose tolerance is one of the leading clinical presentations in patients with pancreatic carcinoma. The mechanism of disturbed glucose metabolism, however, is still under debate. Using microarray technology, key mechanisms of deregulated molecular functions of cancer cell–specific mRNAs and tumor-induced mRNAs in peritumorous tissue should be identified in pancreatic ductal adenocarcinoma (PDAC) by comparison to chronic pancreatitis and normal pancreas. Methods: Forty-three mRNAs were abundant in tissue specimens of patients operated due to pancreatic carcinoma but absent or of low abundance in chronic pancreatitis and normal pancreas. One of these mRNAs encodes the gap junction protein connexin26, known as a tumor suppressor, which was 10.8- and 6.9-fold more abundant in pancreatic carcinoma than in normal pancreas and chronic pancreatitis, respectively. Quantitative RT-PCR was performed for connexin26, with mRNA being expressed 26.7- and 2.9-fold more than in normal pancreas (n = 6), in pancreatic carcinoma (n = 7), and chronic pancreatitis (n = 8), respectively. Results: By immunohistochemistry, connexin26 was predominantly localized to the islets in the vicinity of the pancreatic carcinoma tissue. Control sections of tissue with chronic pancreatitis and normal pancreas show connexin26 expression in the islets as well. Interestingly, the level of mRNA abundance (fold over normal pancreas) in RT-PCR correlates (r = 0.62) with the 2h value of the pre-operative oral glucose tolerance test of these patients. Conclusion: Whether overexpressed connexin26 in pancreatic cancer is a cause of impaired glucose tolerance remains to be elucidated in further experimental studies.

The nitric oxide donor sodium nitroprusside is protective in ischemia/reperfusion injury of the pancreas

BACKGROUND The role of nitric oxide in the ischemia/reperfusion injury of the pancreas is still unclear. In other organs, protective as well as aggravating effects have been described. We have, therefore, investigated the effect of the nitric oxide donor sodium nitroprusside on pancreatic ischemia/reperfusion injury. METHODS In Landrace pigs, after transsection of the pancreas, complete vascular isolation of the pancreatic tail was performed. The tail was subjected to 3 hr of warm ischemia and thereafter reperfusion (6 hr). The animals were divided into a control group (n=7) and a treatment group (n=7) that received 15 mg of sodium nitroprusside after reperfusion intra-arterially into the splenic artery. RESULTS The morphological tissue damage and lipase activity in the venous effluent of the pancreas were significantly lower in the treatment group. Partial oxygen tension in the tissue after reperfusion was markedly reduced in the control group, indicating an impairment of microcirculation. In the treatment group, however, partial oxygen tension in the tissue was significantly higher (43 vs. 20 mmHg; P<0.014). Furthermore, total blood flow through the pancreatic tail in the treatment group was found to be significantly higher in the late reperfusion period (14 vs. 9.5 ml/min at 5 hr after reperfusion; P<0.05). CONCLUSION There is a marked impairment of pancreatic microcirculation after reperfusion. Sodium nitroprusside counteracts this impairment and has a protective effect on ischemia/reperfusion injury of the pancreas.

Impairment of pancreatic microcirculation in the early reperfusion period during simultaneous pancreas-kidney transplantation

Abstract The most likely cause of graft pancreatitis is the ischemia/reperfusion injury which can be a major problem in simultaneous pancreas‐kidney transplantation. Animal experiments suggest the important role in this process of an impaired microcirculation after reperfusion. We have investigated pancreatic microcirculation in the early reperfusion period during clinical pancreas‐kidney transplantation. Tissue PO2 (PO2ti) was monitored by a PO2‐sensitive electrode. After reperfusion (a. r.) samples were taken from the venous effluent of the pancreas and simultaneously from the radial artery. After an initial peak a transient fall of PO2 was found. Total blood flow and hemoglobin oxygen saturation (sHbO2) in the venous effluent increased until 90 min a. r. (107 ml/min, 97.1%) High venous sHbO2 and high PO2ti correlated with good graft outcome. These findings can be explained by an impairment of capillary perfusion (no reflow) and concomitant shunt perfusion. The data suggest the considerable relevance of pancreatic microcirculation in the early reperfusion period during clinical pancreas transplantation.

Endoscopic management of pancreatic fistulas secondary to intraabdominal operation

Background: Pancreatic fistulas may arise secondary to several disorders of the pancreas. Although ~70% of pancreatic fistulas close with nonoperative management, this course of treatment usually takes several weeks or even months. To reduce this long period, closures with fibrin glue have been attempted in the past. In this study, we describe the course, management, and outcome of eight patients with postoperative external pancreatic fistulas of the pancreatic body and tail that arose after oncologic operations in the upper abdomen. Methods: All eight cases were treated by external drainage, insertion of an endoprosthesis into the pancreatic duct, and closure of the fistula with fibrin glue. Results: Immediately after this intervention, secretion from the fistulas was absent in all cases. None of the patients developed abscesses, recurrent fistulas, or complications associated with the fibrin glue. Conclusion: The early endoscopic management of postoperative pancreatic fistula with an approach combining internal drainage of the pancreatic duct and external occlusion of the fistula with fibrin glue is expeditious and beneficial.

Ischemia/reperfusion-induced pancreatitis in rats: a new model of complete normothermic in situ ischemia of a pancreatic tail-segment

Abstract Ischemia/reperfusion injury plays an important role in the development of graft pancreatitis and thrombosis after pancreas transplantation. Up to now there are few therapeutic options for this severe complication because very little is known about pancreatic ischemia/reperfusion injury. The same pathomechanisms may also be involved in the induction and determination of the course of acute pancreatitis. We observed the effect of 2 h of warm in situ ischemia on the postischemic tissue oxygenation, histological organ damage, and pancreatic enzymes. Experiments were performed in 21 male Wistar rats. In sham-operated animals without ischemia, the pancreas was not dissected. In the ischemic/reperfusion group a pancreatic tail-segment was carefully separated from the head, and ischemia was induced by clamping the splenic vessels for 2 h, after flushing the pancreatic tail-segment with heparinized saline. Animals treated similarly, but with opening of the lamps some seconds after induction of ischemia, served as controls. The animals were observed for 2 h after reperfusion. Tissue oxygenation was monitored by a PO2-sensitive probe (LICOX, GMS, Kiel, Germany) which was implanted into the pancreatic tissue. Blood samples were taken before, 5 min, 60 min, and 120 min after reperfusion. At the end of the experiment the pancreatic tail was excises for histological examination; biopsies from the non-ischemic pancreatic head served as intraindividual control to exclude side effects on the non-ischemic pancreatic head. In the ischemia/reperfusion group, PO2ti was significantly lower 1 h (18.0±1.7 mmHg) and 2 h (16.4±1.6 mmHg) after reperfusion compared with baseline conditions (32.8±5.2 mmHg) and the control group (1 h 30.6±1.9 mmHg, 2 h 32.4±2.4 mmHg). Histological injury score and plasma lipase activity were significantly higher in the ischemia/reperfusion group compared with the control group. Thus we describe a new experimental model of complete normothermic in situ ischemia of a pancreatic tail-segment with the possibility of flushing the pancreatic tail-segment and selective local application of drugs to the pancreas.

Complete pancreatic encasement of the portal vein—surgical implications of an extremely rare anomaly

BackgroundDue to the complex embryologic development, pancreatic anatomy can be very variable.DiscussionThe authors present the second ever reported case in the literature of a complete pancreatic encasement of the portal vein which forced us to alter the standard operative procedure of pancreatic head resection, thus enabling possible dangerous complications.

Effects of Organ Preservation, Ischemia Time and Caspase Inhibition on Apoptosis and Microcirculation in Rat Pancreas Transplantation

This study was undertaken to examine the impact of ischemia‐reperfusion (I/R) injury on microcirculation and apoptosis in experimental pancreas transplantation. Pancreatic grafts were subjected to different preservation solutions and cold ischemia times (CITs): University of Wisconsin (UW), 6‐h CITs (group U6); UW, 18‐h CITs (group U18); normal saline, 6‐h CITs (group S6); and normal saline, 6‐h CITs with Z‐Asp‐2,6‐dichlorobenzoyloxymethylketone (pan‐caspase inhibitor; group S6 & CI). Nontransplanted animals served as controls. At 1‐ and 2‐h reperfusion microcirculation was assessed by means of intravital microscopy. Apoptosis was detected by in situ nick end‐labeling method (TUNEL) at 2‐h reperfusion. Deterioration of microcirculation was lowest in group U6 and highest in groups S6 and S6 & CI compared with controls. The apoptotic index (cells per high power fields) of groups U6, U18 and S6 correlated well with functional capillary density (r=− 0,70, p < 0.0001) and leucocyte sticking (r= 0,69, p < 0.0001) at 1‐h reperfusion. Caspase inhibition had no impact on microcirculation but significantly reduced AI compared with group S6 (p < 0.001). These data suggest that pancreatic I/R injury‐induced apoptotic cell death well predicts the extent microcirculatory impairment. Caspase inhibition might be a promising strategy in reducing I/R injury in pancreas transplantation.