Joan M. Braganza

Antioxidant therapy for recurrent pancreatitis: placebo‐controlled trial

Oxidant stress has been proposed as the initiating pathogenetic mechanism in pancreatitis, hence micronutrient antioxidant therapy has been assessed in patients with recurrent attacks and/or constant pancreatic pain. In a 20‐week double‐blind double‐dummy crossover trial active treatment was given as two types of tablets providing daily doses of 600 μg organic selenium, 9000 IU β carotene, 0.54 g vitamin C, 270 IU vitamin E and 2 g methionine. Of 28 patients enrolled, 20 adhered to the full protocol (idiopathic chronic 8, alcoholic chronic 7, idiopathic acute 5). Six patients had an attack whilst on placebo but none whilst on active treatment (P= 0.032). Analysis of visual analogue scoresheets to compare background pain in the 10‐week period before entry and during each phase of the trial, using a 10‐cm scale for each of 11 best descriptors, endorsed the beneficial effect of active treatment (placebo v baseline, P= 0.073; active v baseline, P < 0.001; active v placebo, P= 0.049). The same trend emerged from analysis of pain‐score diaries by conventional and time series methods. Micronutrient antioxidant therapy thus offers a new approach to the treatment of recurrent (non‐gallstone) pancreatitis and/or pancreatic pain.

Heightened free radical activity in pancreatitis

Three markers of free radical oxidation of lipids--9 cis, 11 trans isomer of linoleic acid, conjugated dienes and ultraviolet fluorescence products--were measured in the phospholipid fraction of duodenal juice collected in the first 10 min after an intravenous injection of secretin. The volume of aspirate was similar in 11 controls and in 25 patients who had sustained an attack of pancreatitis 6 weeks earlier--acute pancreatitis (AP) 10, chronic pancreatitis (CP) 15. The concentration of each marker was very significantly higher in the patients; the output of the isomer gave the best discrimination from controls; and ultraviolet fluorescence products were substantially higher in the subgroup with CP than with AP. The serum % molar ratio of the isomer to linoleic acid was measured in 25 controls, 14 AP and 17 CP patients: the highest levels were found in the CP group. Heightened hepatic free radical activity involving lipid isomerization as well as lipid peroxidation pathways is a feature of pancreatitis--probably antedating the attack and persisting well after clinical recovery--the difference between CP and AP being in the degree of abnormality. We argue that these hepatic changes mirror changes in pancreatic-acinar cells and that increased free radical activity in both organs is due to a shortfall of antioxidants in the face of cytochromes P450 induction by xenobiotics. Therefore, a combination of preventive and chain-breaking antioxidants may be useful in preventing further attacks of pancreatitis and controlling background pain in chronic disease.

The nature of diene conjugation in human serum, bile and duodenal juice

Diene‐conjugated lipids have been located by HPLC in serum, bile and duodenal juice. Whether esterified or not the same predominant fatty acid is responsible for most of the diene conjugation in all of these biological fluids. Initial attempts to generate this fatty acid in pure lipid by classical lipid peroxidation in vitro were unsuccessful. Ultraviolet irradiation of free fatty acids in the presence of protein produced diene‐conjugated lipids similar to those found in vivo. The predominant diene‐conjugated fatty acid in vivo is an isomerised C18:2 compound.

Evidence for early oxidative stress in acute pancreatitis

SummaryPancreatic oxidative stress with depletion of pancreatic glutathione is an early feature in all tested models of acute pancreatitis, and sooner or later the problem extends to the lung, irrespective of disease severity, whether toward spontaneous recovery or death from multisystem organ failure. We, therefore, sought evidence of oxidative stress in the human disease by analyzing admission blood samples. We found it from high concentrations of oxidatively altered linoleic acid in serum and vitamin C in plasma (p<0.001 vs controls or a group of other acute abdominal crises where the proportion of patients with admission Apache II scores 8 was similar). These changes were accompanied by subnormal levels of ascorbic acid in plasma (p<0.001); selenium (p<0.001), β-carotene (p<0.001), and α-tocopherol in serum (p=0.005 for its molar ratio to cholesterol). Paradoxically, the plasma concentration ofS-adenosylmethionine was elevated (p=0.02), suggesting that this proximate bioactive metabolite of the essential amino acid had backtracked because its intracellular metabolism down the methionine trans-sulfuration pathway toward glutathione synthesis was disrupted. The aberrations transcended putative etiological factor, duration of symptoms, or disease severity. We conclude: (1) that oxidative stress has pervaded the vascular compartment by the time of admission in patients with acute pancreatitis, and, (2) that blood micronutrient antioxidant profiles at this stage are consistent not only with compromised intracellular capacity to synthesize/refurbish glutathione, but also vulnerability of intra- and extracellular lipid targets.

Antioxidant therapy for recurrent pancreatitis : biochemical profiles in a placebo-controlled trial

The usefulness of micronutrient antioxidant therapy for recurrent (non‐gallstone) pancreatitis has recently been endorsed by a 20‐week double‐blind double‐dummy cross‐over trial in 20 patients. Treatment was delivered as two types of tablets, providing daily doses of 600 μ g organic selenium, 9000 i.u. β ‐carotene, 0.54 g vitamin C, 270 i.u. vitamin E and 2 g methionine. We report antioxidant profiles in blood samples collected before entry, at the cross‐over stage and upon completion of trial. Baseline serum concentrations of selenium, β ‐carotene and vitamin E in the patients were significantly lower than in healthy controls, were unaltered by placebo and normalized by active treatment, but reverted to basal values in the subgroup that received placebo subsequently. The baseline serum concentration of a free radical marker—the 9‐cis, II‐trans isomer of linoleic acid—was significantly higher in the patients than in controls, fell inexplicably in the placebo phase and fell further upon active treatment. Discriminant analysis eliminated the overlap in free radical marker and selenium concentrations between control sera on the one hand and baseline or post‐placebo samples from the patients on the other: antioxidant treatment normalized the relationship between these biochemical parameters. Subnormal baseline serum levels of S‐adenosylmethionine drifted downwards upon active treatment whereas a sharp rise was noted when a relapse of pancreatitis occurred during the placebo phase. The results confirm that adequate exposure to antioxidants in the active treatment phase was associated with amelioration of oxidative stress, and that there was no residual effect 10 weeks after switching over to placebo treatment. Furthermore, the paradoxical behaviour of S‐adenosylmethionine may imply that the beneficial effect of micronutrient antioxidants in recurrent pancreatitis is linked with preservation of the methionine trans‐sulfuration pathway in pancreatic acinar cells.

Micronutrient Antioxidant Status in Tropical Compared with Temperate-Zone Chronic Pancreatitis

Micronutrient antioxidants interact with glutathione in tissues to facilitate the disposal of reactive oxygen species and xenobiotic metabolites derived via cytochromes P450. Published evidence linking cytochrome P450I induction with chronic pancreatitis therefore led us to compare antioxidant status in patients at Manchester in the northwest of England and at Madras in the southeast of India. Serum studies in healthy volunteers showed that the biologic availabilities of selenium and alpha-tocopherol were equally high in the two zones but that the availabilities of beta-carotene and ascorbic acid were lower in the tropical area (p < 0.001), where the ratio of ascorbic acid to total vitamin C concentration in serum was substantially reduced (p < 0.001). The serum antioxidant profiles of the chronic pancreatitis groups reflected these indigenous differences: a decrement in selenium and alpha-tocopherol was evident in both zones, whereas beta-carotene and ascorbic acid values were subnormal only in the Manchester group. The concentration of inorganic sulphate in urine--an index of long-term intake of sulphur amino acids for synthesis of glutathione and other detoxifiers--was similar in controls and patients from Manchester, but levels were lower than in their Madras counterparts (p < 0.02, p < 0.01, respectively). The results suggest that culinary practices that erode the biologic availabilities of ascorbic acid and beta-carotene may predispose to pancreatic oxidative stress and thereby to the changes leading to chronic pancreatitis at an early age in south India. These findings have implications for treatment and prophylaxis.

A Framework for the Aetiogenesis of Chronic Pancreatitis

The traditional ductal model for the development of chronic pancreatitis leaves many questions unanswered and it has not facilitated management. An alternate philosophy centres on the acinar cell as the site of mounting oxidant stress, usually as a result of steady exposure to xenobiotics that induce cytochrome P450 mono-oxygenases while depleting glutathione: ductal changes are regarded as secondary, disease-compounding manifestations of the oxidant environment. Within this framework each burst of oxidant stress jeopardises exocytosis, to trigger an attack of pancreatitis by interfering with the methionine-to-glutathione transsulphuration pathway, which interacts closely with ascorbate and selenium. The resulting diversion of free radical oxidation products into the pancreatic interstitium causes mast cells to degranulate, thereby provoking inflammation, the activation of nociceptive axon reflexes, and profibrotic interactions.

LIPID-PEROXIDATION (FREE-RADICAL-OXIDATION) PRODUCTS IN BILE FROM PATIENTS WITH PANCREATIC DISEASE

Serial samples of bile or duodenal or pancreatic secretions from patients with and without pancreatic disease were examined for lipid-peroxidation (free-radical-oxidation) products. Peroxidation products were found in the phospholipid fraction of bile and the free-fatty-acid fraction of duodenal juice but not in pancreatic juice. There was a highly significant difference in the concentration and excretion pattern of these products between the group of patients with pancreatic disease and the control group of patients with miscellaneous abdominal disorders.

Computed tomography in pancreatic disease.

Computed tomography (CT) of the pancreas has been evaluated in 50 patients with established exocrine pancreatic disease and 20 patients without pancreatic disease. Increase in size, irregularity in outline and heterogeneity of composition of the pancreas implied disease but were in no way specific to any particular disease entity. In acute pancreatitis, following complete resolution, the pancreas appeared normal whereas incomplete resolution was associated with non-specific swelling and heterogeneity of density. The extent and location of pseudocysts could be accurately delineated. In chronic pancreatitis, duct calculi, duct dilatation and large intrapancreatic cysts aided the differentiation between focal enlargement due to chronic pancreatitis and expansion due to cancer. Hepatic metastases and abnormalities of the biliary system seen in association with cancer further aided this differentiation.

Occupational exposure to hydrocarbons and chronic pancreatitis: a case-referent study.

OBJECTIVES--To investigate the hypothesis that hydrocarbon exposure is a risk factor for chronic pancreatitis. METHODS--102 cases of chronic pancreatitis and 204 age and sex matched referents were interviewed about their occupational histories, alcohol and cigarette consumption, and diet. Exposure to hydrocarbons was inferred from interview responses by four assessors who were blind to disease state, and these data were then summarised by a cumulative hydrocarbon exposure (CHE) score. RESULTS--After adjustment for alcohol, cigarettes, dietary antioxidants, and social class, odds ratios for low CHE scores were 1.20 (90% CI: 0.62-2.35) and 2.67 (90% CI: 1.22-5.87) for high scores. A test for trend with level of exposure among only those who had exposure scores > 0 gave p = 0.09. Analysis by type of hydrocarbon was limited to four exposures for each of which there were at least 20 exposed patients. The adjusted OR for paint solvents (any level) was 0.96 (90% CI: 0.48-1.93); for diesel exhaust fumes OR = 2.66 (90% CI: 1.05-6.73); for petrochemicals OR = 1.82 (90% CI: 0.80-4.11); and for chlorinated solvents OR = 1.49 (90% CI: 0.58-3.81). CONCLUSIONS--These results support the original hypothesis. Further studies are needed to confirm or refute the findings here and to clarify the types of hydrocarbon involved.