Changes Of Acute Pancreatitis Research Articles

760 Confocal Endomicroscopy Demonstrates Increased Intestinal Permeability and Gut Dysfunction in Patients With Acute and Chronic Pancreatitis

Introduction Increased intestinal permeability and endotoxaemia occur in acute pancreatitis (AP) but have yet to be confirmed in chronic pancreatitis (CP). Confocal endomicroscopy (CEM) is a novel technology that has identified epithelial gaps and leakage of intravenously administered fluorescein from small intestinal mucosa in inflammatory bowel diseases. We aimed to determine intestinal permeability changes in AP and CP using CEM, assessing associations with endotoxaemia, circulating cytokines and alterations in duodenal flora. Method 182 patients were recruited: 35 mild AP; 11 moderate AP; 8 severe AP (Determinant Based Classification); 47 CP (27 surgically managed, 20 conservatively managed); 33 chronic liver disease and 48 non-ulcer dyspepsia (from whom 14 healthy H. pylorinegative controls were identified). Blood was sampled and duodenal fluid aspirated for culture. CEM was performed in consenting patients and fluorescein leakage scored by two independent blinded investigators. Plasma endotoxin antibodies, serum cytokine concentrations and lactulose:mannitol ratios were measured; D-amino oxidase concentrations were assayed in AP patients undergoing CEM. Results Fluorescein leakage from epithelial villi at CEM and lactulose:mannitol ratios were significantly higher in AP patients (p = 0.0346 and p = 0.046 respectively) and surgically managed CP (p = 0.032, p = 0.030) compared to healthy controls. Patients with AP more frequently showed positive duodenal bacterial cultures than controls (p = 0.004); positive duodenal cultures were associated with fluorescein leakage (p = 0.035). Plasma IgM and IgG concentrations were decreased in AP compared to controls, most markedly in severe AP, and multiple cytokines showed significantly increased concentrations in severe AP. D-amino oxidase enzyme concentrations were significantly increased in those AP patients who showed fluorescein leakage at CEM (p = 0.035). Conclusion CEM identified increased intestinal permeability in AP and surgically managed CP, associated with endotoxaemia, increased serum inflammatory cytokines and D-amino oxidase. These changes were most marked in severe AP. The association of fluorescein leakage with duodenal bacterial proliferation in AP indicates major gut dysfunction that may account for bacterial translocation via epithelial gaps, contributing to AP severity. Disclosure of interest None Declared.

A rare entity of acute bilateral cortical renal necrosis following acute pancreatitis

Acute bilateral renal cortical necrosis following acute pancreatitis is extremely rare condition. Among all cases of acute renal failure, the incidence of renal cortical necrosis was 3.8% in one of the study in North India. Till date, only eight cases of bilateral cortical necrosis following acute pancreatitis were reported in the literature. We report a case of a 27-year-old male patient with abdominal pain, nausea and vomiting since 2 days duration and anuria since 24 h. Serum amylase and lipase were raised, and elevated serum creatinine was noted on admission. Contrast-enhanced computed tomography scan of the abdomen revealed changes of acute pancreatitis with hypoenhancement of renal cortex compared to medulla on both sides (reverse rim sign-stronger enhancement of the renal medulla compared to cortex), suggest an acute renal cortical necrosis.

Diastolic dysfunction, prolonged QTc interval and pericardial effusion as predictors of mortality in acute pancreatitis

The cardiac changes in acute pancreatitis have been earlier studied but the data on their prognostic significance is limited. This study was done to determine electrocardiographic (ECG) and echocardiographic changes in acute pancreatitis and determine their prognostic significance. Fifty-two consecutive patients (mean age 36.5 ± 11 years (44 males)) with acute pancreatitis and without prior cardiovascular comorbidites were prospectively enrolled and subjected to clinical, laboratory and radiological investigation. ECG and echocardiography was done at admission and during follow up. Seventeen patients (32.7%) had mild pancreatitis and 35 (67.3%) patients had severe pancreatitis. Sinus tachycardia was the most common ECG abnormality. QTc prolongation was seen in 30/52 (57.7%) patients. On echocardiography, no patient had systolic dysfunction but 31/52 (59.6%) patients had diastolic dysfunction. All 22 patients with QTc interval < 440 ms survived compared with 8/30 patients with QTc interval ≥ 440 ms who died (P = 0.01). All eight patients who died had evidence of diastolic dysfunction (100%). None of the patients without diastolic dysfunction succumbed to illness (P = 0.02). Pericardial effusion was present in 6/52 (11.5%) patients. Of the eight patients who died, pericardial effusion was present in three (37.5%) patients and this frequency was significantly higher than that in patients who recovered (3/44 [6.8%]; P = 0.04). Electrocardiographic and echocardiographic changes are seen in more than 50% of patients with acute pancreatitis. Prolonged QTc interval, pericardial effusion and diastolic dysfunction are associated with higher mortality.

Experimental Evidence Supporting the Lack of Primary Stem Cells in Adult Pancreatic Tissue

Purpose: To investigate the origin and localization of pancreatic stem cells in adult pancreatic tissues and to determine the primary mechanism underlying the participation of these cells in repairing pancreatic injuries. Methods: Sprague-Dawley rats were divided into experimental and control groups. The experimental group was given intraperitoneal injections of cerulein to induce acute pancreatitis. At 6 h, 1, 2, 3, 5 and 7 days, 5 rats from the experimental group and 2 rats from the control group were sacrificed; all sacrificed animals were intraperitoneally injected with 5-bromo-2′-deoxyuracil nucleotides (BrdU) 6 and 3 h prior to sacrifice. The pathological changes of pancreatic tissue were observed. The stem cell marker nestin and the cell proliferation marker BrdU were detected with immunohistochemistry. Pancreatic duodenal homeobox-1 (PDX-1) was determined by real-time PCR. Results: (1) The pathological changes of acute pancreatitis can be divided into three phases: the edema and apoptosis phase, the hemorrhagic necrosis phase, and the reconstruction phase. (2) Nestin-positive cells mainly appeared in the interlobular vascular lumen after cerulein injection, and they peaked at day 3 when the positive cells spread all over the pancreatic tissues. (3) BrdU-positive cells began to appear in the area surrounding the interlobular region, and the number of positive cells peaked on day 7. (4) The expression of PDX-1 mRNA initially increased, then decreased and gradually got close to a normal level. Conclusion: Primary pancreatic stem cells may not exist in the adult pancreatic tissues. The so-called pancreatic stem cells may actually originate from bone marrow stem cells. When pancreatic tissue is injured, bone marrow stem cells may participate in the repair.

Fundamental and intensive care of acute pancreatitis

Patients who have been diagnosed as having acute pancreatitis should be, on principle, hospitalized. Crucial fundamental management is required soon after a diagnosis of acute pancreatitis has been made and includes monitoring of the conscious state, the respiratory and cardiovascular system, the urinary output, adequate fluid replacement and pain control. Along with such management, etiologic diagnosis and severity assessment should be conducted. Patients with a diagnosis of severe acute pancreatitis should be transferred to a medical facility where intensive respiratory and cardiovascular management as well as interventional treatment, blood purification therapy and nutritional support are available. The disease condition in acute pancreatitis changes every moment and even symptoms that are mild at the time of diagnosis may become severe later. Therefore, severity assessment should be conducted repeatedly at least within 48 h following diagnosis. An adequate dose of fluid replacement is essential to stabilize cardiovascular dynamics and the dose should be adjusted while assessing circulatory dynamics constantly. A large dose of fluid replacement is usually required in patients with severe acute pancreatitis. Prophylactic antibiotic administration is recommended to prevent infectious complications in patients with severe acute pancreatitis. Although the efficacy of intravenous administration of protease inhibitors is still a matter of controversy, there is a consensus in Japan that a large dose of a synthetic protease inhibitor should be given to patients with severe acute pancreatitis in order to prevent organ failure and other complications. Enteral feeding is superior to parenteral nutrition when it comes to the nutritional support of patients with severe acute pancreatitis. The JPN Guidelines recommend, as optional continuous regional arterial infusion and blood purification therapy.

Effects of octreotide in acute hemorrhagic necrotizing pancreatitis in rats

Octreotide is considered to reduce exocrine pancreatic secretion in acute hemorrhagic necrotizing pancreatitis decreasing pancreatic autodigestion. The aim of this study was to determine whether octreotide also has antioxidative effects in acute pancreatitis. Additionally time and dose of application were of interest. Ninety male Sprague-Dawley rats were randomized into six groups (n = 15). Group 1 underwent a laparotomy, and animals in groups 2-6 received intraductal glycodeoxycholic acid followed by intravenous cerulein. Groups 3 and 4 were injected with 0.5 mg octreotide, while groups 5 and 6 received continuous intravenous infusion of 0.05 mg octreotide/h for 10 h. Treatment was initiated 6 hours after induction of pancreatitis (IP) in groups 3 and 5, and 14 h after IP in groups 4 and 6. At 24 h after IP all animals were killed and each pancreas was analyzed histopathologically. In addition, levels of pancreatic lipid peroxidation protective enzymes glutathione-peroxidase (GSH-Px) and superoxide dismutase (SOD) as well as lipid peroxidation via thiobarbituric acid reactive substances (TBARS) were determined. Early bolus application of octreotide reduced severity of histopathological changes in acute pancreatitis and decreased lipid peroxidation in pancreatic tissue samples; however, late bolus application and continuous intravenous infusion did not influence pancreatitis or lipid peroxidation. Octreotide seems to have a dose- and time-dependent effect on histopathology and lipid peroxidation in a model of pancreatitis in rats.

Regulating effects of arsenic trioxide on cell death pathways and inflammatory reactions of pancreatic acinar cells in rats

It is accepted that inflammatory cytokines play a key role in the development of acute pancreatitis, so blocking the initiation of inflammatory reactions may alleviate pathological changes of acute pancreatitis. We studied the regulatory effect of arsenic trioxide (As(2)O(3)) on apoptosis and oncosis of pancreatic acinar cells in vitro and in vivo and its therapeutic effect on acute pancreatitis. Pancreatic acinar cells were isolated by collagenase digestion method. Apoptosis and oncosis of isolated pancreatic acinar cells were detected with Hoechst 33258 + PI or Annexin V + PI double fluorescent staining. Amylase and lactate dehydrogenase release were measured. Acute pancreatitis was induced in Wistar rats by intraperitoneal injections of caerulein, and apoptosis was detected with terminal dUTP nick-end labeling method. Tumor necorsis factor alpha (TNF-alpha) mRNA, myeloperoxidase, nuclear factor-kappaB and histological grading of pancreatic damage were measured. There was an increased apoptosis but a decreased oncosis of pancreatic acinar cell after the treatment with As(2)O(3). The levels of lactate dehydrogenase and amylase release were markedly decreased in As(2)O(3) treated group. Myeloperoxidase content, TNF-alpha mRNA level, nuclear factor-kappaB activation and pathological score in As(2)O(3) treated group were significantly lower than in the untreated group. As(2)O(3) can induce apoptosis and reduce oncosis of pancreatic acinar cell, thus resulting in reduced release of endocellular enzyme of acinar cells, reduced inflammatory cell infiltration and decreased the production of inflammatory cytokines, so that the outcome of alleviated pathological changes was finally achieved.

Three-dimensional morphological study of the pancreatic microvasculature in caerulein-induced experimental pancreatitis

A morphological study of the pancreatic microvasculature in experimental pancreatitis was performed in dogs, using three-dimensional scanning electron microscopy vascular casting and transmission electron microscopy. Animals with pancreatitis were characterized by a marked reduction in the number of capillaries outlined by the cast and by distortion of those that were outlined, with irregularity of the capillary lumen, abruptly terminating capillary buds and leakage of the cast material through the capillary membrane. The study provides convincing morphological evidence that one of the earliest changes in acute pancreatitis is distortion of the capillary circulation.

Ultrastructural clues for the protective effect of melatonin against oxidative damage in cerulein‐induced pancreatitis

The role of oxidative stress has been evaluated in experimental models of acute pancreatitis (AP). The aim of this study is to investigate the effect of melatonin on the ultrastructural changes in cerulein-induced AP in rats. Acute pancreatitis was induced by two i.p. injections of cerulein at 2-hr intervals (50 microg/kg BW). One group received additionally melatonin (20 mg/kg BW) i.p. before each injection of cerulein. The rats were sacrificed 12 hr after the last injection. Pancreatic oxidative stress markers were evaluated by changes in the amount of lipid peroxides and changes in the antioxidant enzyme levels, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and total glutathione (GSH) levels. Ultrastructural examination was performed using a transmission electron microscope. Formation of numerous, large autophagosomes, mitochondrial damage, dilatation of rough endoplasmic reticulum (RER) and Golgi apparatus, margination and clumping of nuclear chromatin were the major ultrastructural alterations observed in the AP group. Melatonin administration prevented mitochondrial and nuclear changes and dilatation of RER and Golgi apparatus. Rare, small autophagosomes were present within the cytoplasm of some of the acinar cells. Pancreatic damage was accompanied by a significant increase in tissue MDA levels (P < 0.05) and a significant decrease in CAT, SOD, GPx activities and GSH levels (P < 0.005). Melatonin administration significantly reduced MDA levels but increased CAT, SOD, GPx activities and GSH levels (P < 0.005). Melatonin also reduced serum amylase and lipase activities, which were significantly elevated in AP (P < 0.05 and P < 0.005 respectively). These results suggest that oxidative injury is important in the pathogenesis of AP. Melatonin is potentially capable of limiting pancreatic damage produced during AP by protecting the fine structure of acinar cells and tissue antioxidant enzyme activities.

N−3, n−6, and n−9 polyunsaturated fatty acids—which composition in parenteral nutrition decreases severity of acute hemorrhagic necrotizing pancreatitis in rats?

Acute pancreatitis often requires parenteral nutrition. Thus, we analyzed, using a randomized trial, whether different fatty acids in parenteral nutrition influence lipidperoxidation and histopathology in acute pancreatitis in rats. Seventy-five male Sprague-Dawley rats were randomized into five groups (gr.) (n=15). Gr. 1 underwent a laparotomy followed by saline infusion, gr. 2-5 received intraductal glycodeoxycholic acid (GDOC) followed by intravenous cerulein. Six hours after induction of pancreatitis (IOP), gr. 2 received saline infusion, while gr. 3 was infused with standard lipovenous (rich in [n-6] polyunsaturated fatty acids (PUFA)), gr. 4 received ClinOleic (rich in [n-9] PUFA), while gr. 5 was infused with Omegaven (rich in [n-3] PUFA) for 18 h. After 24 h, all animals were sacrificed and the pancreas was determined histopathologically according to the severity of pancreatitis. Furthermore, pancreatic lipidperoxidation (TBARS) and activity of lipid production protective enzymes superoxide dismutase (SOD) and gluthationperoxidase (GSHPx) were analyzed. Omegaven infusion reduced the severity of histopathologic changes in acute pancreatitis and decreased lipidperoxidation (TBARS) in pancreatic tissue samples. Furthermore, pancreatic activity of SOD was increased. However, standard PUFA and ClinOleic infusion did not influence the severity of pancreatitis and lipidperoxidation. Parenteral nutrition high in n-3 PUFA seems to be superior to compositions of n-6 or n-9 PUFA in the treatment of acute hemorrhagic pancreatitis in rats.

Pituitary adenylate cyclase activating-peptide and its receptor antagonists in development of acute pancreatitis in rats

Pituitary adenylate cyclase activating-peptide (PACAP) is a late member of the secretin/glucagon/vasoactive intestinal peptide (VIP) family of brain-gut peptides. It is unknown whether PACAP takes part in the development of acute pancreatitis and whether PACAP or its antagonists can be used to suppress the progression of acute pancreatitis. We investigated the actions of PACAP and its receptor antagonists in acute pancreatitis on rats. Acute pancreatitis was induced in rats with caerulein or 3.5% sodium taurocholate. The rats were continuously infused with 5-30 microg/kg PACAP via jugular vein within the first 90 min, while 10-100 microg/kg PACAP6-27 and (4-Cl-D-Phe6, Leu17) VIP (PACAP receptor antagonists) were intravenously infused for 1 h. Biochemical and histopathological assessments were made at 4 h after infusion. Pancreatic and duodenal PACAP concentrations were determined by enzyme-linked immunosorbent assay (ELISA). Chinese ink-perfused pancreas was fixed, sectioned and cleared for counting the functional capillary density. PACAP augmented caerulein-induced pancreatitis and failed to ameliorate sodium taurocholate-induced pancreatitis. ELISA revealed that relative concentrations of PACAP in pancreas and duodenum were significantly increased in both sodium taurocholate- and caerulein-induced pancreatitis compared with those in normal controls. Unexpectedly, PACAP6-27 and (4-Cl-D-Phe6, Leu17) VIP could induce mild acute pancreatitis and aggravate caerulein-induced pancreatitis with characteristic manifestations of acute hemorrhagic/necrotizing pancreatitis. Functional capillary density of pancreas was interpreted in the context of pancreatic edema, and calibrated functional capillary density (calibrated FCD), which combined measurement of functional capillary density with dry weight/wet weight ratio, was introduced. Hyperemia or congestion, rather than ischemia, characterized pancreatic microcirculatory changes in acute pancreatitis. PACAP may take part in the pathogenesis of acute pancreatitis in rats. The two PACAP receptor antagonsits might act as partial agonists. Calibrated functional capillary density can reflect pancreatic microcirculatory changes in acute pancreatitis.

Expression of early growth response factor-1 in rats with cerulein-induced acute pancreatitis and its significance

To observe the expressions of early growth response factor-1 (Egr-1) and tissue factor (TF) in rats with cerulein-induced acute pancreatitis and to explore its significance. A large dose of cerulein was used to create the experimental acute pancreatitis model in rats. The changes of Egr-1 mRNA and protein in rats were observed during 30 min to 4 h after the treatment and immunohistochemical method was used to observe the localized expression of Egr-1 in tissues. In addition to the mRNA expression of Egr-1 target gene, TF was also observed. A blank control group, and a bombesin-administered group were used for comparison. After the stimulation of a large dose of cerulein, the rats showed typical inflammatory changes of acute pancreatitis. Thirty minutes after the stimulation, the mRNA expression of Egr-1 in the pancreatic tissue reached its peak and then declined, while the expression of Egr-1 protein reached its peak 2 h after the stimulation. Histologically, 2 h after the stimulation, almost all pancreatic acinar cells had the expression of Egr-1 protein, which was focused in the nuclei. The mRNA expression of TF occurred 1 h after the stimulation and gradually increased within 4 h. However, a large dose of bombesin only stimulated the pancreatic tissue to produce a little mRNA expression of Egr-1 and no mRNA expression of Egr-1 protein and TF. Egr-1 as a pro-inflammatory transcription factor may play an important role in the pathogenesis of acute pancreatitis by modulating the expression of TF.

Potential harmful effect of iodinated intravenous contrast medium on the clinical course of mild acute pancreatitis.

A worse clinical outcome might be expected in patients with acute pancreatitis (AP) who receive intravenous contrast medium for a nondynamic contrast-enhanced computed tomographic (CECT) study early during hospital admission. Cohort analytic study. Tertiary care center. Of 126 patients with mild AP, 52 patients underwent CECT to establish AP diagnosis (group 1), and the remaining 74 did not (group 2). Survival and development of local or systemic complications during the hospital stay. Potential confounders were demographic, clinical, and biochemical data, as well as therapeutic measures. The Atlanta classification was used to define local and systemic complications. Mean age, etiology of AP, prognostic score on admission, and pharmacologic treatment were similar between groups. Local and systemic complications were more frequently observed in patients who underwent CECT (odds ratio, 11.4; 95% confidence interval, 2.0-64.8; P =.008). Six patients, all in group 1, developed a pancreatic abscess (odds ratio, 20.8; P =.004). In 5 of them, a second CECT showed more severe AP changes. The association between CECT and abscess development was more apparent in patients with a body mass index of 25 or more and/or nasogastric suction. Six patients in group 1 and 1 in group 2 had systemic complications (odds ratio, 9. 5; P =.01). There were no deaths. The observed increased incidence of local and systemic complications in patients with mild AP who undergo CECT, particularly in those with a body mass index of 25 or more, suggests a potentially harmful effect of intravenous contrast medium. Until this issue is clarified, it seems reasonable to restrict the use of dynamic CECT to patients with severe AP, protracted clinical course, or suspected local septic complication.

Early events in acute pancreatitis

Studies using experimental models indicate that the earliest changes in acute pancreatitis involve intra-acinar cell events including the co-localization of lysosomal hydrolases with digestive enzyme zymogens. This co-localization phenomenon leads to trypsinogen activation and subsequent cell injury. Following acinar cell injury, a series of extra-acinar cell changes determine the severity of pancreatitis by promoting or reducing the inflammatory response and by influencing cell death events. Most patients with pancreatitis are diagnosed when acinar cell injury has already occurred. Therapies designed to modify the subsequent extra-acinar cell inflammatory process may prove useful in the management of clinical pancreatitis.

Pancreatic microcirculation in acute pancreatitis.

We present a review of the microvascular morphology of the pancreas and microstructure of the pancreatic lobule, and report our experimental results of the investigation of pancreatic microcirculation following acute pancreatitis. Impairment of pancreatic microcirculation in the early phase of acute pancreatitis may play a key role in the progression of this disease. Possible contributory mechanisms include increased vascular permeability, reduced blood flow, leukocyte-endothelial cell interaction and intravascular thrombus formation. Using an in-vivo microscope system and off-line computer analysis, we achieved direct visualization and quantification of changes in microvascular permeability and leukocyte behavior in pancreas with acute pancreatitis. Bradykinin and oxygen radicals have been demonstrated to be involved in the increase of vascular permeability in the early stage of caerulein pancreatitis. Leukocyte adherence to the vessels in the pancreatic microcirculation is a secondary event following permeability changes in acute pancreatitis. Leukocyte infiltration during exacerbation of acute pancreatitis is mediated by leukocyte-endothelial cell interaction via leukocyte integrin CD11b/18.

Noninvasive monitoring of hemodynamic changes in acute pancreatitis in rabbits.

Hemodynamic parameters of experimental acute necrotizing pancreatitis (AP) were monitored by means of echocardiography in rabbits. Left ventricular (LV) systolic and diastolic parameters were determined before and 1, 3, 6, 12, 18, and 24 hr after injection of taurocholic acid in the pancreatic duct in AP animals. Temporary LV dilatation was observed 6 hr after the AP induction [LV end-diastolic (ED) diameter from 1.16 +/- 0.04 to 1.22 +/- 0.04 cm, P < 0.05, ED volume from 2.98 +/- 0.34 to 3.57 +/- 0.75 ml, P < 0.05] without decrease in systolic function. Cardiac output (CO) and stroke volume (StV) was increased in both groups 3 hr after the operation (from 0.53 +/- 0.15 to 0.71 +/- 0.06 L/min, P < 0.05 in AP), but in the AP animals it remained high. However, 24 hr after AP induction, both the CO and the StV were decreased significantly. The LV diastolic function was impaired 1 hr after AP induction, but had recovered after 12 hr. In conclusion, an early diastolic impairment followed by LV enlargement could be noninvasively observed in experimental AP in rabbits.

Complement Component C5 Deficiency Reduces Edema Formation in Murine Ligation-Induced Acute Pancreatitis

The complement cascade is activated in humans and animals with acute pancreatitis. Activation of complement component C5 liberates C5a, C5a-desarg, and terminal complement complexes (TCCs) that increase capillary permeability, edema, and leukocyte chemotaxis at injured sites. Complement activation plays a major role in pathogenesis of capillary leak and edema formation in severe acute pancreatitis; however, the contribution of C5(C5a/C5a-desarg, TCCs) has not been defined. UsingHcgene mutant mice lacking circulating C5, the role of C5 in ligation-induced acute pancreatitis was evaluated. We performed the following experiments: C5-sufficient (Hc1/Hc1) and C5-deficient (Hc0/Hc0) mice had bile and pancreatic ducts ligated. Sham-operated mice had ducts dissected but not ligated. Mice were killed at 4, 8, and 24 hr after bile–pancreatic duct ligation. Serologic and morphologic evidences of acute pancreatitis were evaluated. Pancreatic edema was assessed using analysis of pancreatic water content, histologic edema score, and determination of wet weight ratio. After 4, 8, and 24 hr of bile–pancreatic duct ligation, hyperamylasemia and histologic changes of acute pancreatitis were observed in both C5-deficient and C5-sufficient mice. Edema developed in all mice with acute pancreatitis. However, when compared to C5-sufficient mice, mice deficient in C5 developed significantly less pancreatic edema at both 8 and 24 hr of bile–pancreatic duct ligation. This difference was not observed 4 hr after induction of acute pancreatitis. We conclude that C5 contributes to edema formation in murine ligation-induced acute pancreatitis. The presence of an early C5-independent phase, in conjunction with the observation of significant edema in mice deficient in C5, suggests there are other mediators of edema formation in this acute pancreatitis model.

Ligation-Induced Acute Pancreatitis Increases Pancreatic and Circulating Trypsinogen Activation Peptides

Ligation of the common bile–pancreatic duct induces hyperamylasemia and acute pancreatitis in rats. Pancreatic morphologic changes include edema, acinar cell damage, and mild inflammation. The pathogenesis of acute pancreatitis in this model is not understood, but may involve altered secretion and intrapancreatic activation of acinar proteases. We hypothesized that trypsinogen activation, measured by the production of plasma and pancreatic trypsinogen activation peptides (TAP), occurs early in this model. We performed the following experiments: rats were prepared with (1) bile–pancreatic ducts ligated and (2) ducts dissected but not ligated (sham). Rats were killed after 6, 24, and 48 hr. Serum amylase was measured and histologic sections were analyzed for morphologic changes. TAP was measured in both serum and pancreatic tissue homogenates using a specific polyclonal anti-TAP antibody in an enzyme-linked immunosorbant assay. After 6, 24, and 48 hr of bile–pancreatic duct ligation, hyperamylasemia and acute morphologic changes of acute pancreatitis were observed. Evidence of acinar cell destruction was not evident until 48 hr after ligation. Levels of serum and pancreatic tissue TAP were significantly elevated at both 24 and 48 hr after ligation compared to those of sham. We conclude that increased intrapancreatic trypsinogen activation occurs early in this form of experimental acute pancreatitis and that it occurs prior to evidence of acinar cell destruction. These data and observations support the possibility that intrapancreatic protease activation contributes to the pathogenesis of ligation-induced acute pancreatitis.

Amelioration of the physiologic and biochemical changes of acute pancreatitis using an anti-TNF-α polyclonal antibody

Tumor necrosis factor (TNF) is an inflammatory cytokine that may be an important mediator in the development of the systemic sequelae associated with severe acute pancreatitis. The purpose of this study was to determine whether the neutralization of TNF-α with a polyclonal antibody could ameliorate selected biochemical parameters of severe pancreatitis in a rat model. Pancreatitis was induced by an antegrade injection of artificial bile into the bile duct. Forty rats were randomized into 4 groups: no surgery (controls), saline infusion to bile duct (sham), placebo treatment in animals with pancreatitis (placebo + Px), and pretreatment with a polyclonal antibody (PAb) in animals with pancreatitis (PAb + Px). Serum TNF-α, amylase, calcium, hematocrit, glucose, and ascites volume were measured 2 hours after bile duct infusion. Pretreatment with the PAb produced a significant improvement in all parameters when compared with pancreatitis animals treated with placebo (p < 0.001). In addition, TNF-α, which was elevated in animals with pancreatitis, was reduced significantly in treated animals (p < 0.001). These results suggest that TNF-α may be an important mediator in the evolution of the systemic manifestations of severe acute pancreatitis.

Effect of naloxone on the haemodynamics and the outcome of experimental acute pancreatitis in dogs.

Endogenous opioid peptides may play a role in the genesis of pancreatic damage in acute pancreatitis. The effects of naloxone on the haemodynamic changes in acute pancreatitis were investigated by inducing it in dogs with pancreatic ductal injection of fresh trypsin-bile mixture. In the control group (n = 8), acute pancreatitis was characterized haemodynamically by falls in the maximum positive and negative dP/dt (+/- dP/dt), cardiac output (CO) and cardiac index (CI), and increases in the pulmonary vascular resistance (PVR) and systemic vascular resistance (SVR) as well as an early reduction of pancreatic blood flow (PBF). In another set of eight dogs (naloxone group), naloxone was given intravenously 10 min after the induction of acute pancreatitis (80 micrograms/kg as a bolus + 80 micrograms/kg/h for 3 h). Compared with untreated dogs, naloxone significantly increased PBF and the +/- dP/dtmax; prevented the significant decreases in CO and CI and increases in PVR and SVR, and reduced significantly the severity of pancreatitis, as assessed by both the histological staging and the mortality rate. These results suggest that naloxone limits the progression of acute pancreatitis from oedematous to haemorrhagic form. It is proposed that endogenous opioid peptides may play a role in the pathophysiology of acute pancreatitis.