Role of oxidative stress in the pathogenesis of acute pancreatitis

Clinical significance of serum thioredoxin 1 levels in patients with acute pancreatitis

OBJECTIVE

Thioredoxin 1 (TRX-1), a redox-regulating protein with antioxidant activity, is induced by oxidative stress, and serum TRX-1 levels are recognized as an oxidative-stress marker. The aim of this study was to clarify the clinical significance of serum TRX-1 levels in patients with acute pancreatitis (AP) and evaluate the usefulness of this measurement in assessing disease severity.

METHODS

Serum TRX-1 levels were determined on admission in 18 patients with severe AP and 36 patients with mild AP. We also investigated the relationship between serum TRX-1 levels and clinical and laboratory data.

RESULTS

The median serum TRX-1 levels on admission were 54.9 ng/mL in mild AP and 118.8 ng/mL in severe AP. When the cutoff value for TRX-1 in predicting severe AP was determined to be 100 ng/mL, its sensitivity, specificity, and accuracy were 83.3%, 94.4%, and 90.7%, respectively. A significant correlation was observed between serum TRX-1 levels and Ranson score (r = 0.674), C-reactive protein (r = 0.718), interleukin 6 (r = 0.712), leukocyte count (r = 0.642), and serum amylase (r = 0.436).

CONCLUSIONS

Serum TRX-1 levels significantly correlate with AP severity. TRX-1 should constitute a reliable oxidative-stress marker for the evaluation of AP severity in relation to oxidative stress.

Fetal hemoglobin induction by histone deacetylase inhibitors involves generation of reactive oxygen species

OBJECTIVE

Several compounds, including butyrate and trichostatin A, have been shown to activate gamma-gene expression via p38 mitogen-activated protein kinase (MAPK) signaling. In eukaryotic cells, reactive oxygen species (ROS) act as signaling molecules to mediate phosphorylation of tyrosine kinases such as p38 MAPK to regulate gene expression. Therefore, we determined the role of the reactive oxygen species hydrogen peroxide (H(2)O(2)) in drug-mediated fetal hemoglobin (HbF) induction.

METHODS

H(2)O(2) levels were measured using 2',7'-dichlorofluorescein-diacetate in K562 cells after drug treatments. To confirm a role for H(2)O(2) in HbF induction, studies were completed with the mitochondrial respiratory chain inhibitor myxothiazole, which prevents ROS generation. The ability of myxothiazole to block gamma-globin mRNA accumulation and HbF induction was measured in K562 cells and burst-forming unit-erythroid colonies respectively using quantitative real-time PCR and alkaline denaturation.

RESULTS

Butyrate and trichostastin A stimulated p38 MAPK phosphorylation via a H(2)O(2)-dependent mechanism. Pretreatment with myxothiazole to inhibit ROS formation or SB203580 to impede p38 MAPK signaling attenuated gamma-gene activation in K562 cells and HbF induction in erythroid progenitors. However, myxothiazole had no effect on the ability of hydroxyurea to induce HbF.

CONCLUSION

The findings presented herein support a ROS-p38 MAPK cell signaling mechanism for HbF induction by butyrate and trichostatin A.

Effect of melatonin on the severity of L-arginine-induced experimental acute pancreatitis in rats

AIM: To determine the effect of melatonin pre- and post-treatment on the severity of L-arginine (L-Arg) -induced experimental pancreatitis in rats.

METHODS: Male Wistar rats (25) were divided into five groups. Those in group A received two injections of 3.2 g/kg body weight L-Arg i.p. at an interval of 1 h. In group MA, the rats were treated with 50 mg/kg body weight melatonin i.p. 30 min prior to L-Arg administration. In group AM, the rats received the same dose of melatonin 1 h after L-Arg was given. In group M, a single dose of melatonin was administered as described previously. In group C the control animals received physiological saline injections i.p. All rats were exsanguinated 24 h after the second L-Arg injection.

RESULTS: L-Arg administration caused severe necrotizing pancreatitis confirmed by the significant elevations in the serum amylase level, the pancreatic weight/body weight ratio (pw/bw), the pancreatic IL-6 content and the myeloperoxidase activity, relative to the control values. Elevation of the serum amylase level was significantly reduced in rats given melatonin following L-Arg compared to rats injected with L-Arg only. The activities of the pancreatic antioxidant enzymes (Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and catalase (CAT)) were significantly increased 24 h after pancreatitis induction. Melatonin given in advance of L-Arg significantly reduced the pancreatic CAT activity relative to that in the rats treated with L-Arg alone. In the liver, L-Arg significantly increased the lipid peroxidation level, and the glutathione peroxidase and Cu/Zn-SOD activities, whereas the Mn-SOD activity was reduced as compared to the control rats. Melatonin pre-treatment prevented these changes.

CONCLUSION: Melatonin is an antioxidant that is able to counteract some of the L-Arg-induced changes during acute pancreatitis, and may therefore be helpful in the supportive therapy of patients with acute necrotizing pancreatitis.

Review of experimental animal models of acute pancreatitis

The underlying mechanisms involved in the pathogenesis of acute pancreatitis are ill understood. The mortality rate of this disease has not significantly improved over the past few decades. Current treatment options are limited, and predominantly aimed at supportive therapy. A key feature of severe acute pancreatitis is the presence of extensive tissue necrosis with both local and systemic manifestations of inflammatory response syndromes. A better understanding of the underlying pathophysiology of severe acute pancreatitis may lead to more targeted therapeutic options, potentially leading to improved survival. Animal models of acute pancreatitis are therefore an essential investigative tool for these aims to be achieved. This review discusses the suitability of recent non-invasive models of acute pancreatitis such as hormone-induced, alcohol-induced, immune-mediated, diet-induced, gene knockout and L-arginine; and invasive models including closed duodenal loop, antegrade pancreatic duct perfusion, biliopancreatic duct injection, combination of secretory hyperstimulation with minimal intraductal bile acid exposure, vascular-induced, ischaemia/reperfusion and duct ligation.

Hyperbaric oxygen-induced changes in bacterial translocation and acinar ultrastructure in rat acute necrotizing pancreatitis

BACKGROUND

We aimed to investigate the effects of hyperbaric oxygen therapy on bacterial translocation and acinar cell ultrastructure in a rat model of acute necrotizing pancreatitis.

METHODS

Forty-eight male Sprague-Dawley rats were randomly divided into three groups. Acute pancreatitis was induced in groups II and III. Groups I and II did not receive any treatment, and group III was treated with hyperbaric oxygen. All surviving animals were killed 48 h after the induction of pancreatitis. Bacterial translocation and histological and ultrastructural changes were determined.

RESULTS

The incidence of bacterial translocation in group III was significantly lower in comparison with group II (P<0.001). Histopathological and ultrastructural injury scores were also significantly lower in group III (P<0.001 and P<0.04, respectively).

CONCLUSIONS

Hyperbaric oxygen therapy displayed beneficial effects on pancreatic superinfection and or histopathological and ultrastructural changes in experimental necrotizing pancreatitis.

Nuclear factor-kappaB activation on the reactive oxygen species in acute necrotizing pancreatitic rats

AIM: To investigate the potential role of nuclear factor kappa-B (NF-κB) activation on the reactive oxygen species in rat acute necrotizing pancreatitis (ANP) and to assess the effect of pyrrolidine dithiocarbamate (PDTC, an inhibitor of NF-κB).

METHODS: Rat ANP model was established by retrograde injection of 5% sodium taurocholate into biliopancreatic duct. Rats were randomly assigned to three groups (10 rats each): Control group, ANP group and PDTC group. At the 6^th h of the model, the changes of the serum amylase, nitric oxide (NO), malondialdehyde (MDA), superoxide dismutase (SOD) and pancreatic morphological damage were observed. The expressions of inducible nitric oxide (iNOS) were observed by SP immunohistochemistry. And the expressions of NF-κB p65 subunit mRNA were observed by hybridization in situ.

RESULTS: Serum amylase and NO level decreased signifi-cantly in ANP group as compared with PDTC administrated group [(7 170.40 ± 1 308.63) U/L vs (4 074.10 ± 1 719.78) U/L, P < 0.05], [(76.95 ± 9.04) mol/L vs (65.18 ± 9.02) mol/L, P < 0.05] respectively. MDA in both ANP and PDTC group rose significantly over that in control group [(9.88 ± 1.52) nmol/L, (8.60 ± 1.41) nmol/L, vs (6.04 ± 1.78) nmol/L, P < 0.05], while there was no significant difference between them. SOD levels in both ANP and PDTC group underwent a significant decrease as compared with that in control [(3 214.59 ± 297.74) NU/mL, (3 260.62 ± 229.44) NU/mL, vs (3 977.80 ± 309.09) NU/mL, P < 0.05], but there was no significant difference between them. Though they were still higher than those in Control group, pancreas destruction was slighter in PDTC group, iNOS expression and NF-κB p65 subunit mRNA expression were lower in PDTC group as compared with ANP group.

CONCLUSION: We conclude that correlation among NF-κB activation, serum amylase, reactive oxygen species level and tissue damage suggests a key role of NF-κB in the pathogenesis of ANP. Inhibition of NF-κB activation may reverse the pancreatic damage of rat ANP and the production of reactive oxygen species.

Oxidative stress and nitric oxide in rats with alcohol-induced acute pancreatitis

AIM: Oxygen free radical mediated tissue damage is well established in pathogenesis of acute pancreatitis (AP). Whether nitric oxide (NO) plays a deleterious or a protective role is unknown. In alcohol-induced AP, we studied NO, lipooxidative damage and glutathione in pancreas, lung and circulation.

METHODS: AP was induced in rats (n = 25) by injection of ethyl alcohol into the common biliary duct. A sham laparatomy was performed in controls (n = 15). After 24 h the animals were killed, blood and tissue sampling were done.

RESULTS: Histopathologic evidence confirmed the development of AP. Marked changes were observed in the pulmonary tissue. Compared with controls, the AP group displayed higher values for NO metabolites in pancreas and lungs, and thiobarbituric acid reactive substances in circulation. Glutathione was lower in pancreas and in circulation. Glutathione and NO were positively correlated in pancreas and lungs of controls but negatively correlated in circulation of experimental group. In the experimental group, plasma thiobarbituric acid reactive substances were negatively correlated with pancreas thiobarbituric acid reactive substances but positively correlated with pancreas NO.

CONCLUSION: NO increases in both pancreas and lungs in AP and NO contributes to the pathogenesis of AP under oxidative stress.

Effect of simultaneous inhibition of TNF-alpha production and xanthine oxidase in experimental acute pancreatitis: the role of mitogen activated protein kinases

OBJECTIVE

To assess the effects of inhibiting both tumor necrosis factor (TNF)-alpha production and xanthine oxidase activity on the inflammatory response, mitogen-activated protein kinase (MAPK) activation and mortality in necrotizing acute pancreatitis in rats.

SUMMARY BACKGROUND DATA

Pancreatic injury triggers 2 major pathways involved in the systemic effects of severe acute pancreatitis: pro-inflammatory cytokines and oxidative stress.

METHODS

Pancreatitis was induced by intraductal infusion of 3.5% sodium taurocholate. We examined whether treatment with oxypurinol, a specific inhibitor of xanthine oxidase, and/or pentoxifylline, an inhibitor of TNF-alpha production, affects pancreatic damage, ascites, lung inflammation, and MAPK phosphorylation.

RESULTS

Oxypurinol prevented p38 phosphorylation in the pancreas and partially avoided the rise in lung myeloperoxidase activity. Pentoxifylline prevented erk 1/2 and JNK phosphorylation in the pancreas, and it partially reduced ascites and the rise in lung myeloperoxidase activity. Combined treatment with oxypurinol and pentoxifylline almost completely abolished ascites, MAPK phosphorylation in the pancreas, and the increase in lung myeloperoxidase activity. Histology revealed a reduction in pancreatic and lung damage. These changes were associated with a significant improvement of survival.

CONCLUSIONS

: Simultaneous inhibition of TNF-alpha production and xanthine oxidase activity greatly reduced local and systemic inflammatory response in acute pancreatitis and decreased mortality rate. These effects were associated with blockade of the 3 major MAPKs.

Effects of octreotide on acute necrotizing pancreatitis in rabbits

AIM: To assess the role of oxygen-derived free radicals and cytokines in the pathogenesis of taurocholic acid-induced acute pancreatitis, and to evaluate the preventive effects of octreotide towards the development of acute pancreatitis.

METHODS: Acute pancreatitis was induced in male New Zealand white rabbits by retrograde injection of 0.8 mL/kg·b.m. of 50 g/L sodium taurocholate (NaTC) in the pancreatic duct. Sham-operated animals served as control. Octreotide 1 mg/kg·b.m. was administered subcutaneously before the induction of pancreatitis. Blood was taken from the jugular vein before and at 1, 3, 6, 12 and 24 h after pancreatitis induction. Serum activities of amylase, IL-6 and TNF-α and levels of malonyl dialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), catalase and superoxide dismutase (Mn-, Cu-, and Zn-SOD) in pancreatic tissue were measured.

RESULTS: Serum TNF-α and IL-6 levels increased significantly 3 h after the onset of pancreatitis, and then returned to control level. The tissue concentration of MDA was significantly elevated at 24 h, while the GSH level and GPx, catalase, Mn-SOD, Cu-, Zn-SOD activities were all significantly decreased in animals with pancreatitis as compared to the control. Octreotide pretreatment significantly reversed the changes in cytokines and reactive oxygen metabolites. Octreotide treatment did not alter the serum amylase activity and did not have any beneficial effects on the development of histopathological changes.

CONCLUSION: Oxygen-derived free radicals and proinflammatory cytokines are generated at an early stage of NaTc-induced acute pancreatitis in rabbits. Prophylactic octreotide treatment can prevent release of cytokines and generation of reactive oxygen metabolites, but does not have any beneficial effects on the development of necrotizing pancreatitis.

Immunohistochemical localization of metallothionein in chronic pancreatitis

Metallothionein (MT) is a low-molecular weight intracellular protein, rich in sulfhydryl residues, and able to bind bivalent metals. MT, like Zn, is a component of the diversified elements of antioxidant system. Recent studies have shown that reactive oxygen species play a role in the pathogenesis and development of chronic pancreatitis. The aim of the study was to identify immunohistochemically (LSAB2-HRP; DAKOCytomation) the localization of metallothionein and to determine MT expression in 9 patients with chronic pancreatitis. Our studies confirm that MT is present in exocrine and endocrine cells of patients with chronic pancreatitis and chronic pancreatitis with concomitant diabetes. They also indicate increased expression of MT, particularly in acinar cells of the pancreas. This suggests that MT is greatly involved in homeostasis of the pancreas and synthesis of pancreatic hormones.

Endothelial nitric oxide synthase is protective in the initiation of caerulein-induced acute pancreatitis in mice

The effect of inhibiting nitric oxide (NO) synthase (NOS) or enhancing NO on the course of acute pancreatitis (AP) is controversial, in part because three NOS isoforms exist: neuronal (nNOS), endothelial (eNOS), and inducible (iNOS). We investigated whether inhibition or selective gene deletion of NOS isoforms modified the initiation phase of caerulein-induced AP in mice and explored whether this affected pancreatic microvascular blood flow (PMBF). We investigated the effects of nonspecific NOS inhibition with N(omega)-nitro-l-arginine (l-NNA; 10 mg/kg ip) or targeted deletion of eNOS, nNOS, or iNOS genes on the initiation phase of caerulein-induced AP in mice using in vivo and in vitro models. Western blot analysis was performed to assess eNOS phosphorylation status, an indicator of enzyme activity, and microsphere studies were used to measure PMBF. l-NNA and eNOS deletion, but not nNOS or iNOS deletion, increased pancreatic trypsin activity and serum lipase during the initiation phase of in vivo caerulein-induced AP. l-NNA and eNOS did not affect trypsin activity in caerulein-hyperstimulated isolated acini, suggesting that nonacinar events mediate the effect of NOS blockade in vivo. The initiation phase of AP in wild-type mice was associated with eNOS Thr(495) residue dephosphorylation, which accompanies eNOS activation, and a 178% increase in PMBF; these effects were absent in eNOS-deleted mice. Thus eNOS is the main isoform influencing the initiation of caerulein-induced AP. eNOS-derived NO exerts a protective effect through actions on nonacinar cell types, most likely endothelial cells, to produce greater PMBF.

The dynamics of the oxidant-antioxidant balance in the early phase of human acute biliary pancreatitis

BACKGROUND/AIM

Reactive oxygen species play an important role in the pathogenesis of acute pancreatitis (AP) in animal models. Data on the oxidant-antioxidant balance in humans are scanty. The present study was undertaken to evaluate the dynamics of changes in the oxidant-antioxidant balance in the early phase of human AP.

METHODS

74 consecutive patients with acute biliary pancreatitis (16 with severe, 58 with mild pancreatitis), treated endoscopically, were included in the study. Serum concentrations of sulfhydryl groups (SH; main nonenzymatic antioxidant; 73 patients) and thiobarbituric acid reactive substances (TBARS; markers of reactive oxygen species-mediated tissue damage; 56 patients) were determined on admission and on each of 10 successive days. The analysis comprised the comparison of results in patients with mild and severe outcome of pancreatitis.

RESULTS

Serum SH dropped by 27%, reaching the trough level on day 4 of hospitalization, whereas serum TBARS rose by 28%, reaching a peak 1 day later. Neither SH nor TBARS returned to initial values at the end of observation. The most dynamic changes in both SH and TBARS concentrations occurred in the first 3 days of hospitalization. The changes were significantly greater in patients with complicated pancreatitis in comparison to patients with mild disease, and were most pronounced in patients who developed infected pancreatic necrosis and who subsequently died.

CONCLUSIONS

The oxidant-antioxidant balance changes rapidly in the early phase of human AP, confirming the role of oxidative stress in the pathogenesis of AP. The degree of changes correlates with the clinical severity of pancreatitis.

Administration of hyaluronic acid and chondroitin-4-sulfate limits endogenous antioxidant depletion and reduces cell damage in experimental acute pancreatitis

Several reports have described a loss of endogenous antioxidants and molecular oxidative damage during acute pancreatitis. Since hyaluronic acid and chondroitin-4-sulfate possess antioxidant properties, the effect of the administration of these glycosaminoglycans in a cerulein-induced acute pancreatitis in rats was investigated. Cerulein administration produced pancreatic edema and a marked increase in serum lipase and amylase activity; induced a severe depletion of reduced glutathione, catalase, and superoxide dismutase levels; primed lipid peroxidation; and promoted neutrophil intervention. Intraperitoneal pretreatment of rats with hyaluronic acid or chondroitin-4-sulfate or with both compounds ameliorated pancreatic cell conditions; restored the endogenous antioxidants reduced glutathione, catalase and superoxide dismutase; limited cell membrane peroxidation; and reduced neutrophil activation. Our data confirm the antioxidant activity of these 2 glycosaminoglycans.

The effect of combination therapy of hyperbaric oxygen, meropenem, and selective nitric oxide synthase inhibitor in experimental acute pancreatitis

Despite the new diagnostic and therapeutic advancements, acute pancreatitis has still high rate of morbidity and mortality. We aimed to evaluate the effects of hyperbaric oxygen (HBO) therapy alone or combined with S-methylisothiourea (SMT), and meropenem (MER) therapy in an experimental rat model of acute necrotizing pancreatitis. Rats were randomly divided into 8 groups, and acute pancreatitis was induced in all groups except group 1. Treatment protocols were saline for group 2, SMT for group 3, SMT + MER for group 4, SMT + HBO for group 5, HBO for group 6, HBO + MER for group 7, and MER for group 8. All surviving animals were killed 48 hours after the induction of pancreatitis, and specimens were collected. Oxidative stress parameters, histopathologic scores and amylase levels were better in treatment groups than in the positive control group (group 2). The most favorable results were obtained in HBO treatment groups, especially in HBO + MER group (group 7). Our results indicate that adding HBO therapy to the antibiotic therapy will decrease oxidative stress parameters, serum amylase levels, and histopathological score. We suggest that adding the HBO therapy as an adjunctive to the treatment protocol of acute necrotizing pancreatitis may yield improvement in the morbidity and mortality of the disease.

Useful markers for predicting severity and monitoring progression of acute pancreatitis

BACKGROUND

The main problem in staging acute pancreatitis is the lack of accurate predictors of disease severity and of markers for progression of acute pancreatitis.

METHODS

We reviewed the literature for all candidate markers of acute pancreatitis and graded their usefulness and practicability for prediction of severe pancreatitis and for monitoring disease progression.

RESULTS

Several markers can differentiate mild and severe cases of acute pancreatitis with a high positive predictive value. Trypsinogen activation peptide and procalcitonin show significant differences in patients with mild and severe disease already on admission. While most parameters peak early and decrease rapidly thereafter, C-reactive protein (CRP), phospholipase A(2), procalcitonin and serum amyloid A are reliable predictors with persistently elevated levels in severe disease. CRP is still the reference parameter of all predictors indicating severe disease and pancreatic necrosis. So far, no single parameter has been developed which is suitable for early prediction of infected pancreatic necrosis.

CONCLUSION

Of all markers available today, CRP is the 'gold standard' in predicting the severity of acute pancreatitis, but procalcitonin seems to be a promising tool to monitor the progression of the disease. CRP has already been established in clinical routine. For procalcitonin, a practicable assay is also available and could easily be adopted into clinical routine.

Attenuated cerulein-induced pancreatitis in nuclear factor-kappaB-deficient mice

Nuclear factor (NF)-kappaB plays a central role in acute pancreatitis. We studied cerulein (CER)-induced pancreatitis in NF-kappaB knockout (KO) mice. NF-kappaB KO mice and normal control littermate wild-type (WT) mice were given four hyperstimulating doses of cerulein every hour to elicit secreatagogue-induced pancreatitis. Malonildialdehyde activity, glutathione levels, myeloperoxidase activity, TNF-alpha, and NF-kappaB binding activity and its inhibitory protein IkappaBalpha were studied in the pancreas. Furthermore, we measured plasma lipase and amylase and the histological damage. KO mice had reduced malonildialdehyde levels (WT + CER = 4.083 +/- 0.95 micromol/g; KO + CER = 1.513 +/- 0.63 microol/g), decreased myeloperoxidase activity (WT + CER = 19.3 +/- 2.39 mU/g; KO + CER = 10.21 +/- 2.05 mU/g), increased glutathione levels (WT + CER 6.22 +/- 2.46 micromol/g; KO + CER = 15. 516 +/- 2.92 micromol/g), and reduced serum levels of amylase (WT + CER = 2519 +/- 656.9 U/L; KO + CER = 916 +/- 280.4 U/L) and lipase (WT + CER = 1420 +/- 170 U/L; KO + CER = 861 +/- 172. 3 U/L). KO mice showed reduced pancreatic NF-kappaB activation, decreased TNF-alpha tissue content, and reduced histologic alterations. Our data suggest that KO mice have an attenuated cerulein-induced pancreatitis and help to define the possible interaction between NF-kappaB activation and oxidative stress in this deleterious event.

Deferoxamine and meropenem combination therapy in experimental acute pancreatitis

INTRODUCTION

Recent data from the experimental clinical studies suggest that antibiotics having good penetration to pancreas may reduce mortality by preventing pancreatic infection, which is the most important prognostic factor in acute pancreatitis (AP). Deferoxamine is an active free oxygen radical scavenger, which has been shown to have a protective role in development of acute pancreatitis.

AIM

To determine the effects of combination of deferoxamine and meropenem in acute necrotizing pancreatitis.

METHODOLOGY

One hundred male Sprague-Dawley rats were randomly divided into 5 groups. All rats underwent laparotomy with cannulation of biliopancreatic duct. Group 1 received intraductal saline injection. Acute necrotizing pancreatitis was induced in group 2, 3, 4, and 5 by intraductal injection of 3% taurocholate. Group 1 (sham operated) and group 2 were injected with saline of 0.3 mL/kg intraperitoneally (i.p). Group 3 was injected with meropenem 60 mg/kg/d i.p, group 4 with deferoxamine 80 mg/kg/d s.c and group 5 with combination of these 2 agents at the same doses. While meropenem was started 2 hours later, all treatments were started immediately after the induction of pancreatitis. All rats were killed at the 48th hour of the treatment and blood and tissue samples were collected for amylase determinations, pathologic examinations, and culture.

RESULTS

There was no difference in serum amylase levels between AP induced groups (P > 0.05). Pancreatic histology scores were significantly low in rats treated with deferoxamine (group 4), and combination regimen (group 5) (P < 0.001). Meropenem significantly reduced the incidence of pancreatic infection. Although combination of deferoxamine with meropenem showed better effects than meropenem alone in terms of pancreatic infection, the difference did not reach to statistical significance.

CONCLUSIONS

Meropenem treatment reduces secondary pancreatic infections in acute pancreatitis. Treatment with deferoxamine and meropenem combination may be more beneficial than single therapies in reducing the severity of pancreatitis. Further studies investigating the effects of this combination on survival are needed.

Elevated protein carbonyls as plasma markers of oxidative stress in acute pancreatitis

BACKGROUND

Experimental studies have demonstrated that protein and lipid oxidation is a feature of acute pancreatitis and that antioxidant pretreatment can ameliorate the severity of the disease. Justification for a clinical trial of antioxidant therapy requires stronger evidence for oxidative stress in patients.

AIMS

To determine if oxidative stress is evident in patients with acute pancreatitis on admission to hospital, if it increases after admission and if it is related to disease severity.

METHODS

Measurement of plasma concentrations of protein carbonyls and malondialdehyde as markers of protein oxidation and lipid peroxidation, respectively, in a consecutive series of 85 patients with acute pancreatitis 0, 2 and 5 days after admission.

RESULTS

Patients with acute pancreatitis had significantly increased concentrations of protein carbonyls in plasma on recruitment (median 27 h after the onset of symptoms) that persisted over 5 days. Protein carbonyls were higher in severe compared with mild disease (median 0.099 and 0.043 nmol/mg protein, respectively, p = 0.0016). They were higher at day 0 in patients recruited with more established pancreatitis than in those presenting early. No increases in malondialdehyde were seen. Receiver operator characteristic curve analysis demonstrated that protein carbonyls at day 0 were comparable with C-reactive protein at predicting pancreatitis severity.

CONCLUSION

Our demonstration of substantial protein oxidation provides further evidence for oxidative stress in patients with severe pancreatitis. Our results suggest that there could be a window for early antioxidant intervention and that protein carbonyls could be a useful plasma marker of oxidative injury.

The role of inducible nitric oxide synthase inhibitor, meropenem, and taurine in experimental acute necrotizing pancreatitis

INTRODUCTION

Translocation of bacteria from the gut is one of the most important factors in the development of septic complications and mortality in acute pancreatitis.

AIMS

To investigate whether S-methylisothiourea (SMT), taurine (TAU), and meropenem (MER) could effect bacterial translocation and the course of acute necrotizing pancreatitis.

METHODOLOGY

Seventy male Sprague-Dawley rats were studied. Rats were randomly allocated into seven groups. Acute pancreatitis was induced in group II (MER), group III (TAU), group IV (TAU + MER), group V (TAU + SMT), group VI (TAU + MER + SMT), and group VII (positive control) by retrograde injection of taurocholate into the common biliopancreatic duct. Group I rats (sham) received normal saline infusion into the common biliopancreatic duct as negative control. Rats were treated with drug combinations intraperitoneally for 48 hours after induction of pancreatitis. At the 48th hour of induction, all animals were killed, and specimens were collected.

RESULTS

Bacterial translocation to peritoneum and pancreas in groups treated with MER were lower than in the other groups. Pancreatic tissue GSHpx and SOD levels were higher in all groups in comparison with levels in group VII. Pancreatic tissue MDA levels were also lower in all treatment groups except group II. The most favorable results were obtained in group VI (TAU + MER + SMT). Also, the lowest pathologic score between the groups in which acute pancreatitis developed was obtained in group VI.

CONCLUSIONS

Addition of TAU and SMT to the treatment protocol for acute pancreatitis seems to improve the pathologic score and oxidative stress parameters. Also, antibiotherapy with MER decreases the risk of bacterial translocation.

Expression of proteinase-activated receptor 2 during taurocholate-induced acute pancreatic lesion development in Wistar rats

BACKGROUND

Proteinase-activated receptor 2 (PAR-2) is a G-protein coupled transmembrane receptor activated by trypsin by site-specific cleavage. Its presence on pancreatic structures was demonstrated in the past. PAR-2 physiologically involves in duct/acinary cells secretion, arterial tonus regulation or capillary liquid turnover. During development of acute pancreatitis/acute pancreatic lesion (APL) these mentioned structures are influenced by very high concentration of trypsin due to its increased basolateral secretion into the interstitium. The aim of our study as presented was to investigate whether PAR-2 is also involved in APL following changes of PAR-2 expression.

METHODS

APL was investigated in Wistar rats after injection of 0.1 mL taurocholate into the ductus choledochus. Anatomy, histology, reverse transcriptase polymerase chain reaction (RT PCR) as well as immunohistochemistry and Western-blot analysis of pancreatic tissue were performed using antibody mapping of the new NH2 terminal of PAR-2 after trypsin cleavage. Results from control rats and d 1 or d 4 rats after taurocholate injection were compared.

RESULTS

Much higher positivity on acinary/duct cells was observed in APL induced animals than in controls. Similar findings were noticed on arterial smooth muscle cells. Surprisingly, parallel to the exocrine pancreas and vessel findings, enhanced Langerhans' islet cell positivity was observed in experimental animals.

CONCLUSIONS

Based on these results, we have demonstrated that during APL development PAR-2 expression increases. This effect is caused by conformational changes after PAR-2 activation, and the new NH2 terminal of activated receptor presentation. We suggest that PAR-2 physiological functions are enhanced during APL development.

Expression of proteinase-activated receptor 2 during taurocholate-induced acute pancreatic lesion development in Wistar rats

BACKGROUND

Proteinase-activated receptor 2 (PAR-2) is a G-protein coupled transmembrane receptor activated by trypsin by site-specific cleavage. Its presence on pancreatic structures was demonstrated in the past. PAR-2 physiologically involves in duct/acinary cells secretion, arterial tonus regulation or capillary liquid turnover. During development of acute pancreatitis/acute pancreatic lesion (APL) these mentioned structures are influenced by very high concentration of trypsin due to its increased basolateral secretion into the interstitium. The aim of our study as presented was to investigate whether PAR-2 is also involved in APL following changes of PAR-2 expression.

METHODS

APL was investigated in Wistar rats after injection of 0.1 mL taurocholate into the ductus choledochus. Anatomy, histology, reverse transcriptase polymerase chain reaction (RT PCR) as well as immunohistochemistry and Western-blot analysis of pancreatic tissue were performed using antibody mapping of the new NH2 terminal of PAR-2 after trypsin cleavage. Results from control rats and d 1 or d 4 rats after taurocholate injection were compared.

RESULTS

Much higher positivity on acinary/duct cells was observed in APL induced animals than in controls. Similar findings were noticed on arterial smooth muscle cells. Surprisingly, parallel to the exocrine pancreas and vessel findings, enhanced Langerhans' islet cell positivity was observed in experimental animals.

CONCLUSIONS

Based on these results, we have demonstrated that during APL development PAR-2 expression increases. This effect is caused by conformational changes after PAR-2 activation, and the new NH2 terminal of activated receptor presentation. We suggest that PAR-2 physiological functions are enhanced during APL development.

Neutrophils and NADPH oxidase mediate intrapancreatic trypsin activation in murine experimental acute pancreatitis

BACKGROUND & AIMS

Intrapancreatic activation of digestive enzymes is a key event in the parenchymal cell injury of pancreatitis. We hypothesized that neutrophils recruited to the pancreas during pancreatitis may contribute to such activation.

METHODS

To cause experimental pancreatitis, rats and mice were treated with high doses of cerulein. Activation of the digestive enzyme, trypsin, was measured in pancreatic homogenates using a fluorogenic assay and localized immunocytochemically with antibody to trypsin-activation peptide (TAP).

RESULTS

Compared with controls, rats depleted of neutrophils with antineutrophil serum exhibited a marked attenuation in intrapancreatic trypsin activation and acinar cell TAP labeling induced by high-dose cerulein. To examine the mechanism, mice deficient in either nicontinamide adenine dinucleotide phosphate (NADPH) oxidase, or myeloperoxidase (MPO) were studied for trypsin activation. Mice deficient in NADPH oxidase exhibited attenuation of the cerulein-induced trypsin activation, but those deficient in MPO did not. Using measurements of Western blot analysis, generation of reactive oxygen species, and immunocytochemistry, we demonstrated the NADPH oxidase activity is in neutrophils and not pancreatic acinar tissue.

CONCLUSIONS

The results demonstrate a novel role for neutrophils infiltrating the pancreas in pathologic activation of digestive enzymes in acute pancreatitis and indicate that this effect is mediated by products of NADPH oxidase.

Expression of inducible nitric oxide synthase contributes to the development of pancreatitis following pancreatic ischaemia and reperfusion

BACKGROUND

Inducible nitric oxide synthase (iNOS) activity is increased in experimentally induced acute pancreatitis. Increased expression of this isoform of nitric oxide synthase has been demonstrated in several organs subjected to ischaemia-reperfusion injury. The present experiment investigated the expression of iNOS and the effect of selective iNOS inhibition in pancreatic ischaemia-reperfusion.

METHODS

Wistar rats (n = 40) were randomly and equally assigned to four groups. Groups 2 and 4 underwent 60 min of total pancreatic ischaemia followed by 6 h of reperfusion (I-R). Groups 1 and 3 underwent sham operation. The selective iNOS inhibitor L-N(6)-(1-iminoethyl)-lysine (L-NIL) was administered to groups 3 and 4. Expression of iNOS was examined by immunohistochemistry. Other investigations included measurement of serum amylase activity and pancreatic wet : dry weight ratio, and histopathological examination.

RESULTS

Eight of ten rats in group 2 (I-R only) expressed iNOS but none of the ten animals in group 1 (sham laparotomy) did so. Group 4 (I-R + L-NIL) animals had significantly lower serum amylase levels and wet : dry weight ratios than those in group 2 (I-R only). Microscopic evidence of pancreatic injury was present only in rats in group 2 (I-R only).

CONCLUSION

Expression of iNOS during reperfusion following pancreatic ischaemia contributes significantly to the development of acute pancreatitis.

Modulation of endogenous nitric oxide synthase in experimental acute pancreatitis: role of anti-ICAM-1 and oxygen free radical scavengers

OBJECTIVE

To evaluate, in an experimental model of acute pancreatitis, the impact of nitric oxide on the disease process and the interaction between nitric oxide and oxygen free radicals.

SUMMARY BACKGROUND DATA

Nitric oxide and oxygen free radicals are involved in the pathophysiology of acute pancreatitis. It is well established that oxygen free radicals play an important role in the development of pancreatic cell damage and remote organ failure, but the impact of nitric oxide on the disease process and the interactions between the two radical species remain controversial.

METHODS

Necrotizing pancreatitis (NP) was induced in Wistar rats by intraductal sodium taurocholate infusion after pretreatment with isotonic saline (NP-S), superoxide dismutase/catalase (NP-SOD/CAT), or an anti-ICAM-1 antibody (aICAM-1). Sham-operated rats received isotonic saline (SHX). After an observation period of 5 minutes and 24 hours, the pancreas was removed for microscopy, glutathione, and myeloperoxidase (MPO) analysis. The inducible NO synthase (NOS-2) was detected by Western blotting or RT-PCR. Serum was analyzed for nitrite/nitrate (NO2-/NO3-) and S-nitrosothioles (RSNO), while plasma was used to assay for trypsinogen activation peptides (TAP).

RESULTS

NP-S animals showed a significant decrease in GSH levels after NP-induction as compared with animals under therapy. Increased MPO levels in the NP-S group were significantly reduced by aICAM-1 while SOD/CAT injection showed no changes. Serum NO-derivatives peaked at 12 hours while TAP levels had a maximum at 6 hours after NP induction, and were lower after aICAM-1 application SOD/CAT treatment increased both parameters. Extended acinar cell damage and inflammatory infiltrate developed in NP-S animals and was significantly improved by SOD/CAT and aICAM-1 treatment. RT-PCR and Western-blot analysis revealed NOS-2 expression in the NP-S group, which was reduced by radical scavengers and aICAM-1.

CONCLUSION

Enhanced nitric oxide synthase expression and increased nitric oxide derivatives are found during severe acute pancreatitis. Oxygen free radicals and neutrophils seem to be potent and important regulation mechanisms for nitric oxide synthase activity and nitric oxide-mediated toxicity but imply only a secondary role for nitric oxide in the local pathologic mechanism of this disease.

Oxidative stress in distant organs and the effects of allopurinol during experimental acute pancreatitis

BACKGROUND

The present study was aimed at an assessment of the role of oxygen-derived free radicals in the development of local and systemic manifestations of L-arginine (Arg)-induced acute pancreatitis and at an evaluation of the protective effect of the xanthine oxidase inhibitor allopurinol.

METHODS

Acute pancreatitis was induced in male Wistar rats by injecting 2 x 250 mg/100 g body weight of Arg intraperitoneally at an interval of 1 h, as a 20% solution in 0.15 M NaCl. Control rats received the same quantity of glycine. In a third group, 200 mg/kg of allopurinol was administered subcutaneously 30 min before the first Arg injection. Rats were killed at 6, 12, 24, or 48 h following Arg administration. Acute pancreatitis was confirmed by a serum amylase level elevation and typical inflammatory features were observed microscopically. Tissue concentrations of malonyl dialdehyde (MDA), superoxide dismutase (Mn- and Cu,Zn-SOD), glutathione peroxidase (GPx), and catalase were measured in the pancreas, liver, and kidney.

RESULTS

The tissue concentration of MDA was significantly elevated in each organ. The activities of Mn-SOD, Cu,Zn-SOD, GPx, and catalase were quickly depleted in the pancreas and kidney, whereas only the Mn-SOD and GPx activities were reduced in the liver after the onset of pancreatitis. Histologic examination revealed acinar cell necrosis in the pancreas, but only mild alterations in the liver and kidney. Allopurinol pretreatment prevented the generation of reactive oxygen metabolites in the pancreas and reduced their formation in the kidney.

CONCLUSION

Oxygen-derived free radicals are generated in the pancreas, liver, and kidney at an early stage of Arg-induced acute pancreatitis. The liver and the kidney, but not the pancreas, are able to defend against oxidative stress. The prophylactic application of allopurinol significantly restrains the generation of free radicals in pancreas and kidney.

Reactive oxygen species activate mitogen-activated protein kinases in pancreatic acinar cells

It has been recently reported that kinases that belong to the mitogen-activated protein kinase (MAPK) family are rapidly activated by cholecystokinin (CCK) in rat pancreas both in vitro and in vivo. It is known that reactive oxygen species (ROS) play an important role in the pathogenesis of acute pancreatitis induced by supraphysiologic stimulation with CCK analogue, cerulein. The aim of our study was to evaluate whether MAPKs are activated by ROS in pancreatic acini. The activity of MAPK, c-Jun amino-terminal kinase (JNK), and p38 MAPK was determined in isolated rat pancreatic acinar cells by means of Western blotting, with the use of specific antibody that recognizes active, dually phosphorylated kinases. Incubation of acini with ROS donors, hydrogen peroxide (H2O2) and/or menadione (MND), strongly activated all three kinases. Activation of these kinases by ROS, but not by CCK, was substantially inhibited by pretreatment of acini with antioxidant N-acetylo-L-cysteine (NAC). Whereas CCK-induced activation of MAPK or JNK was totally or partially blocked by protein kinase C (PKC) inhibitor GF-109203X, ROS-induced activation of MAPK, JNK, and p38 MAPK was PKC independent. In conclusion, ROS strongly activate MAPK, JNK, and p38 MAPK in pancreatic acinar cells. It may be of importance in acute pancreatitis, because ROS are involved in the pathogenesis of this disease.

Severity of acute pancreatitis: a multivariate analysis of oxidative stress markers and modified Glasgow criteria

BACKGROUND

It is unknown whether measurement of markers of oxidative stress can improve the prediction of severity of acute pancreatitis.

METHODS

Consecutive patients admitted with a diagnosis of acute pancreatitis were divided into mild (n = 62) and severe (n = 23) groups based on the Atlanta classification. Plasma oxidative stress markers were measured within 24 h of admission and included ascorbic acid (endogenous antioxidant), protein carbonyl (a marker of protein oxidation), thiobarbituric acid reactive substances (a marker of lipid peroxidation) and myeloperoxidase (a neutrophil enzyme that produces oxidants). Canonical correlation analysis was used to describe the relationship between these markers and the modified Glasgow criteria. Canonical variate analysis was used to define the best variables that could discriminate mild and severe pancreatitis.

RESULTS

There was a significant correlation between markers of oxidative stress and the modified Glasgow criteria (first canonical correlation 0.69, P < 0.0001, Wilk's lambda test). Blood urea, serum albumin and white cell count were the best variables that discriminated mild and severe acute pancreatitis, and all were better than the oxidative stress markers.

CONCLUSION

The markers of oxidative stress were highly correlated with the severity of pancreatitis. They are unlikely to be better than the modified Glasgow criteria in predicting it.

Oxidative stress in distant organs and the effects of allopurinol during experimental acute pancreatitis

BACKGROUND

The present study was aimed at an assessment of the role of oxygen-derived free radicals in the development of local and systemic manifestations of L-arginine (Arg)-induced acute pancreatitis and at an evaluation of the protective effect of the xanthine oxidase inhibitor allopurinol.

METHODS

Acute pancreatitis was induced in male Wistar rats by injecting 2 x 250 mg/100 g body weight of Arg intraperitoneally at an interval of 1 h, as a 20% solution in 0.15 M NaCl. Control rats received the same quantity of glycine. In a third group, 200 mg/kg of allopurinol was administered subcutaneously 30 min before the first Arg injection. Rats were killed at 6, 12, 24, or 48 h following Arg administration. Acute pancreatitis was confirmed by a serum amylase level elevation and typical inflammatory features were observed microscopically. Tissue concentrations of malonyl dialdehyde (MDA), superoxide dismutase (Mn- and Cu,Zn-SOD), glutathione peroxidase (GPx), and catalase were measured in the pancreas, liver, and kidney.

RESULTS

The tissue concentration of MDA was significantly elevated in each organ. The activities of Mn-SOD, Cu,Zn-SOD, GPx, and catalase were quickly depleted in the pancreas and kidney, whereas only the Mn-SOD and GPx activities were reduced in the liver after the onset of pancreatitis. Histologic examination revealed acinar cell necrosis in the pancreas, but only mild alterations in the liver and kidney. Allopurinol pretreatment prevented the generation of reactive oxygen metabolites in the pancreas and reduced their formation in the kidney.

CONCLUSION

Oxygen-derived free radicals are generated in the pancreas, liver, and kidney at an early stage of Arg-induced acute pancreatitis. The liver and the kidney, but not the pancreas, are able to defend against oxidative stress. The prophylactic application of allopurinol significantly restrains the generation of free radicals in pancreas and kidney.

N-acetylcysteine decreases severity of acute pancreatitis in mice

Oxidative stress plays a major role in the early stage of acute pancreatitis. This study assessed the effects of N-acetylcysteine (NAC), a reduced glutathione (GSH) provider and a direct scavenger of reactive oxygen intermediates, in the course of acute pancreatitis in mice. Acute pancreatitis (AP) was induced by intraperitoneal (i.p.) injections of cerulein. Mice received NAC (1,000 mg/kg, i.p.) every 3 h, starting either 1 h before the first cerulein injection (prophylactic group) or 1 h after the first cerulein injection (therapeutic group), or i.p. saline injections for controls. Severity of AP was evaluated by histology, serum hydrolase levels, and serum and intrapancreatic levels of MCP-1 and interleukin 6 (IL-6). Pancreatic conjugated dienes and intrapancreatic and intrahepatic GSH levels were measured to assess the local and systemic oxidative processes. Acute pancreatitis was also induced with a CDE diet in controls and mice receiving either both NAC ad libidum in drinking water and 1,000 mg/kg i.p. injection once daily. The severity of pulmonary lesions was assessed by arterial blood gases (pO2) and intrapulmonary myeloperoxidase (MPO content) measurements as well as the survival of mice. The severity of cerulein-induced AP was significantly decreased in the prophylactic group compared with the therapeutic and control groups. Prophylactic administration of NAC also decreased the intrapancreatic levels of conjugated dienes compared with controls. The intrapancreatic and systemic release of MCP- 1 and IL-6 was also decreased in the prophylactic group 3 and 6 hours after AP induction. In addition, NAC pretreatment also reduced hepatic IL-6 production at 3 and 6 hours after starting cerulein challenge. In CDE-induced AP, the severity of lung injury (hypoxemia, MPO content) was decreased, and survival was improved by NAC. NAC administered in a prophylactic protocol limits the severity of experimental acute pancreatitis in mice, as well as its systemic complications and related mortality.

The pathogenesis of L-arginine-induced acute necrotizing pancreatitis: inflammatory mediators and endogenous cholecystokinin

This study was aimed at an assessment of the role of oxygen-derived free radicals, cytokines and endogenous cholecystokinin (CCK) in the pathogenesis of L-arginine (Arg)-induced acute pancreatitis in rat. We measured the levels of malonyl dialdehyde (MDA), glutathione peroxidase (GPx), catalase and superoxide dismutase (Mn- and Cu, Zn-SOD) in pancreatic tissue, the serum levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and CCK, and evaluated the protective effect of the xanthine oxidase inhibitor allopurinol and a novel CCK receptor antagonist KSG-504. Acute pancreatitis was induced in male Wistar rats by injecting 2x 250 mg/100 g body weight of Arg intraperitoneally in an 1-h interval, as a 20% solution in 0.15 M NaCl. Control rats received the same quantity of glycine. 200 mg x kg(-1) allopurinol 30 min before the first Arg treatment or 50 mg x kg(-1) KSG-504 30 min before and 6, 18 and 36 h after the first Arg injection was administered subcutaneously. Rats were killed at 6, 12, 24 and 48 h following Arg administration, and acute pancreatitis was confirmed by a serum amylase level elevation and typical inflammatory features observed microscopically. The serum level of amylase reached the peak level at 24 h after the Arg injection (30,800 +/- 3,813 versus 6,382 +/- 184 U x L(-1) in the control) and normalized at 48 h. The tissue concentration of MDA was significantly elevated at 24 h, and reached the peak value at 48 h (5.00 +/- 1.75 versus 0.28 +/- 0.05 nM x mg(-1) protein in the control). The catalase and Mn-SOD activities were significantly decreased throughout the study, while the GPx activity was significantly reduced at 6 and 12 h, and the Cu, Zn-SOD activity was significantly lower at 12 h after the Arg injection as compared with the controls. Both the TNF-alpha and the IL-6 levels were already elevated significantly at 12 h and peak at 24 h versus the controls (19.1 +/- 7.9 U x mL(-1) and 57.6 +/- 11.2 pg x mL(-1) versus 3.1 +/- 0.8 U x mL(-1) and 15.2 +/- 3.1 pg x mL(-1), respectively). No significant changes in plasma CCK levels were observed. Allopurinol treatment markedly reduced the serum amylase elevation (12.631 +/- 2.257 U x L(-1) at 24 h), prevented the increase in tissue MDA concentration (0.55 +/- 0.09 nM x mg(-1) protein at 48 h) and significantly ameliorated the pancreatic edema, necrosis and inflammation at 48 h after Arg administration. KSG-504 administration did not exert any beneficial effect on the development of histopathological changes neither modified the serum amylase or cytokine levels. Oxygen-derived free radicals and cytokines are involved, while endogenous CCK does not seem to play a role in the pathogenesis of Arg-induced acute pancreatitis.

Early ascorbic acid depletion is related to the severity of acute pancreatitis

BACKGROUND

Ascorbic acid (AA) is an important endogenous antioxidant in plasma and has been shown to be decreased at the time of hospital admission in patients with acute pancreatitis. The aim of this study was to determine whether plasma AA concentration continues to decrease after admission and whether the extent of decrease is related to the severity of pancreatitis.

METHODS

Consecutive patients with mild (n = 62) and severe (n = 23) acute pancreatitis had plasma AA concentration measured on the day of recruitment and on days 2 and 5 by high-performance liquid chromatography.

RESULTS

The plasma AA concentration in patients with acute pancreatitis was significantly less than that in normal volunteers on days 0, 2 and 5 (P < 0.0001) and this was more marked in those with severe disease. There was a decrease in plasma AA concentration from day 0 to day 2 in patients with mild (P < 0.0001) and severe (P = 0.0005) pancreatitis, and from day 2 to day 5 in patients with severe pancreatitis (P = 0.023).

CONCLUSION

Endogenous plasma AA continues to decrease over the first 5 days in hospital and the extent is related to the severity of acute pancreatitis. Presented to a meeting of the Australasian Surgical Research Society, Auckland, New Zealand, August 1995 and published in abstract form as Aust N Z J Surg 1996; 66: 243

Nutrition supplementation in patients with acute and chronic pancreatitis

Acute pancreatitis is a hypermetabolic state characterized by increased protein catabolism, lipolysis, and glucose intolerance. Most patients presenting with acute pancreatitis are better within 5 to 7 days and can be resume a regular diet. Patients with severe pancreatitis and who are unable to eat within 7 to 10 days should receive nutritional support. The decision to use parenteral or enteral nutrition is controversial. More recent data suggest that jejunal feedings are just as beneficial, if not better, than parenteral nutrition. Marked weight loss and abdominal pain are the features of chronic pancreatitis. Steatorrhea develops when greater than 90% of pancreatic exocrine dysfunction occurs. Treatment focuses on pain control and pancreatic enzyme replacement. Pancreatic enzymes should be given with meals. Patients with refractory steatorrhea may benefit from the addition of an H2 antagonist or proton-pump inhibitor with pancreatic enzyme replacement. Micronutrients, including antioxidants, should be replaced if serum levels suggest a deficiency.

Role of oxidative stress in the pathogenesis of caerulein-induced acute pancreatitis

In the last decade, the role of oxidative stress has been extensively evaluated in different experimental models of acute pancreatitis. This review shows that there is strong evidence that this stress occurs as an early phenomenon in pancreatic tissue in the course of caerulein-induced acute pancreatitis. Oxidative stress was documented in pancreatic tissue by means of methods showing generation of reactive oxygen species (e.g., chemiluminescence) and accumulation of products of reactive oxygen species-mediated lipid peroxidation. with concomitant depletion of enzymatic and low molecular weight antioxidants. Features of acinar cell injury and inflammation, especially pancreatic edema, show a marked improvement following treatment with a broad spectrum of antioxidants, platelet activating factor antagonists, or donors of nitric oxide (NO). Unfortunately, in most cases these beneficial effects are temporary and generally restricted to an early phase of the disease. However, results of well-designed clinical trials should finally evaluate the importance of oxidative stress-oriented treatment in acute pancreatitis in humans.

Acute oxidative stress modulates secretion and repetitive Ca2+ spiking in rat exocrine pancreas

The effects of the oxidant tert-butylhydroperoxide (t-buOOH) on carbachol-stimulated pancreatic secretion in the vascularly perfused rat pancreas have been studied in parallel with [Ca2+]i signalling and amylase output in perifused rat pancreatic acinar cells. Perfusion of the pancreas with t-buOOH (0.1-1 mM) caused a rapid and irreversible inhibition of carbachol-stimulated (3x10-7 M) amylase and fluid secretion. Pre-perfusion of the pancreas with vitamin C and dithiothreitol or a cocktail of GSH and GSH-precursor amino acids provided only marginal protection against the deleterious effects of t-buOOH, even though GSH levels were elevated significantly. In perifused pancreatic acini, repetitive [Ca2+]i spikes evoked by carbachol (3x10-7 M) were sustained for 40 min. t-buOOH (1 mM) acutely increased the amplitude and duration of Ca2+ spikes, then attenuated Ca2+ spiking and subsequently caused a marked and sustained rise in [Ca2+]i. t-buOOH-induced alterations in carbachol-stimulated [Ca2+]i signalling and amylase release in perifused pancreatic acini were prevented by vitamin C. Although vitamin C restored impaired Ca2+ signalling and maintained amylase output in pancreatic acini, it seems likely that oxidative stress inhibits fluid secretion irreversibly in the intact pancreas, resulting in a loss of amylase output. Thus, perturbations in [Ca2+]i signalling may not fully explain the secretory block caused by oxidative stress in acute pancreatitis.

Induction of cystine transport via system x-c and maintenance of intracellular glutathione levels in pancreatic acinar and islet cell lines

The relationship between l-cystine transport and intracellular glutathione (GSH) levels was investigated in cultured pancreatic AR42J acinar and betaTC3 islet cells exposed to diethylmaleate, an electrophilic agent known to activate cellular antioxidant responses. Cystine transport was mediated predominantly by the Na+-independent anionic amino acid transport system x-c, with influx inhibited potently by glutamate and homocysteate but unaffected by cationic or neutral amino acids. Saturable cystine transport was 10-fold higher in AR42J (531 pmol (mg protein)-1 min-1) than in betaTC3 (49 pmol (mg protein)-1 min-1) cells, and GSH levels were higher in AR42J cells. Treatment with 2-mercaptoethanol increased GSH levels in betaTC3 cells from 7.5 to 36 nmol (mg protein)-1, whilst the GSH content in AR42J cells (64 nmol (mg protein)-1) was not altered significantly. Incubation of AR42J or betaTC3 cells with homocysteate (2.5 mM, 0-48 h), a competitive inhibitor of cystine transport via system x-c, reduced intracellular GSH levels and resulted in a time-dependent (6-24 h) induction of system x-c transport activity. Treatment of AR42J cells with diethylmaleate (100 microM, 0-48 h) resulted in a time- (5-10 h) and protein synthesis-dependent induction of cystine transport, with intracellular GSH levels initially decreasing and then increasing 2-fold above control levels after 24 h. Diethylmaleate also depressed GSH levels in betaTC3 cells, but cystine transport was not elevated significantly. In both AR42J and betaTC3 cells, inhibition of gamma-glutamyl cysteine synthetase by buthionine sulphoximine (100 microM, 24 h) reduced GSH levels but had no effect on cystine transport. The present findings establish that induction of system x-c leads to changes in GSH levels in pancreatic AR42J acinar and betaTC3 islet cells, with changes in the intracellular redox state stimulating transporter expression. Induction of activity of system x-c, together with adaptive increases in GSH synthesis in response to oxidative stress, may contribute to cellular antioxidant defences in pancreatic disease.

Alcohol and the pancreas

Alcoholic pancreatitis may be one of the most serious adverse consequences of alcohol abuse. Its diagnosis, as it has for many years, depends primarily on clinical acumen in interpreting properly the symptoms and signs of abdominal distress, buttressed by elevated pancreatic enzymes (amylase and lipase). More recently, the use of computerized tomography (CT) in selected situations has been both of confirmatory and prognostic value. Severity of abnormality by CT correlates reasonably well with a variety of clinical-laboratory clusters (APACHE system, Ranson's criteria, etc.) and aids in therapy. The pathogenesis of alcoholic pancreatitis is not fully defined. The ultimate picture is one of tissue autolysis by activated proteolytic enzymes. The triggers for such activation, however, are still not known. They are represented by three main theories: (1) large duct obstruction and/or increased permeability relative to pancreatic secretion, (2) small duct obstruction due to proteinaceous precipitates, and (3) a direct toxic-metabolic effect of ethanol on pancreatic acinar cells. While not mutually exclusive, we favor the last hypothesis as being most consistent with the effects of ethanol on other organ systems. The direct effects of ethanol and/or its metabolites may be mediated, at least in part, via oxidative stress or the generation of fatty acid ethyl esters. Autolysis (regardless of proximate mechanism(s)) leads to inflammation likely mediated via release of various cytokines. It also should be appreciated that "acute" pancreatitis (the topic of this chapter) likely represents an acute process within a chronic pancreatic exposure and injury from alcoholic abuse. The key question of why pancreatitis develops in only a small number of alcohol abusers is not resolved. Therapy depends on the severity of alcoholic pancreatitis, which is defined by clinical-laboratory and often CT criteria. Mild pancreatitis usually resolves acutely with alcohol abstention and supportive therapy. Severe pancreatitis has a significant morbidity and mortality, mainly related to the degree of pancreatic necrosis and infection. It requires meticulous combined medical-surgical care.

Nutrient antioxidants in gastrointestinal diseases

Oxidative stress appears to play a role in the pathogenesis of a number of gastrointestinal disease states, including pancreatitis; gastric and duodenal ulcer disease; IBD; gastric, esophageal, and colon cancers; and hepatic injury secondary to alcohol, metal storage disorders, hepatitis, and ischemia/reperfusion injury. The nutritional antioxidants are attractive potential therapeutic and chemopreventive agents because they are inexpensive and have a relatively low toxicity profile. A word of caution should be noted: Some antioxidants, such as vitamin C, can be prooxidant under certain conditions, and systemically altering the redox state may have untoward effects on the inflammatory response in certain disease states. Thus, at the current time, antioxidant therapy should be restricted to randomized, controlled clinical trials, in which treatment effects can be closely monitored, and therapeutic efficacy can be determined with scientific accuracy.

Gastric intramucosal pH predicts death in severe acute pancreatitis

BACKGROUND

This study tested the hypothesis that gastric intramucosal pH (pHi) can predict death in severe acute pancreatitis.

METHODS

Seventeen consecutive patients with predicted severe acute pancreatitis were studied prospectively. Four died from complications related to pancreatitis. Gastric pHi was measured by nasogastric tonometry at least every 12 h for the first 48 h after admission and then on a daily basis during the first week.

RESULTS

The lowest pHi recorded during the first 48 h was significantly less in those admitted to the intensive care unit than that in those who remained on the surgical ward (P = 0.0015) and in nonsurvivors compared with the survivors (P = 0.009). A receiver-operator characteristic curve defined a pHi of 7.25 as the optimal cut-off point to predict death (sensitivity 100 per cent, specificity 77 per cent, overall predictive value 82 per cent).

CONCLUSION

These results suggest that splanchnic ischaemia may be an important determinant of outcome in patients with severe acute pancreatitis.

Gastric intramucosal pH predicts death in severe acute pancreatitis

BACKGROUND

This study tested the hypothesis that gastric intramucosal pH (pHi) can predict death in severe acute pancreatitis.

METHODS

Seventeen consecutive patients with predicted severe acute pancreatitis were studied prospectively. Four died from complications related to pancreatitis. Gastric pHi was measured by nasogastric tonometry at least every 12 h for the first 48 h after admission and then on a daily basis during the first week.

RESULTS

The lowest pHi recorded during the first 48 h was significantly less in those admitted to the intensive care unit than that in those who remained on the surgical ward (P = 0.0015) and in nonsurvivors compared with the survivors (P = 0.009). A receiver-operator characteristic curve defined a pHi of 7.25 as the optimal cut-off point to predict death (sensitivity 100 per cent, specificity 77 per cent, overall predictive value 82 per cent).

CONCLUSION

These results suggest that splanchnic ischaemia may be an important determinant of outcome in patients with severe acute pancreatitis.

[Effect of selenium administration on various laboratory parameters in patients with acute pancreatitis]

BACKGROUND

Recent studies presented evidence that activation of oxygen derived free radicals occurs in patients with acute pancreatitis. The purpose of this study was to evaluate the effect of sodium selenite as a possible antioxidant therapy in acute pancreatitis.

PATIENTS AND METHOD

16 patients with moderate form of acute pancreatitis received a high dose of sodium selenite. Selenium in serum and whole blood, zinc, copper, manganese, superoxid dismutase (SOD), glutathione peroxidase (Gpx) and malondialdehyde (MDA) were determined (before selenium substitution, 3 days later, 8 days later, before demission). No selenium deficiency could be detected before selenium substitution.

RESULT

The selenium therapy caused a significant increase in selenium, a moderate increase in activity of Gpx, a significant decrease in activity of MDA, whereas SOD remained unchanged.

CONCLUSION

Concerning the particular point of view of "deficiency management", there is no need of selenium substitution in patients with a moderate form of acute pancreatitis in our region. The highly normal selenium concentration we established by our therapy is possibly connected with a decrease of the oxidative stress in acute pancreatitis. More clinical follow-up studies with more patients, who have different grades of severity of the acute pancreatitis, and besides that a control group of patients without selenium substitution, are necessary for evaluating the clinical relevance of our results.