Towards a novel treatment strategy for acute pancreatitis. 2. Principles and potential practice.

In part 1 it was argued that a 'free radical-mast cell' template for the aetiogenesis of acute pancreatitis accommodates the evidence, whereas the prevailing 'trypsin-cytokine' template does not. In this sequel I examine the ramifications of the new philosophy in relation to speedier diagnosis, prognostic aids and, above all, a programme of active treatment which - once validated in experimental studies - could be implemented by the first medical respondent.

Towards a novel treatment strategy for acute pancreatitis. 1. Reappraisal of the evidence on aetiogenesis.

Despite more than a century of research endeavour, there is no specific medical treatment for acute pancreatitis and early mortality is high - 20% of fatalities by the day after admission. I do not see any realistic prospect that today's focus on immunomodulation will provide a breakthrough either. The signs are that the outcome of acute pancreatitis is determined almost at its inception, and that those unfortunate individuals in whom the seeds for a precipitous course are sewn do not declare themselves until it is too late. This reappraisal of the evidence on disease aetiogenesis has been undertaken in an effort to fathom why this might be.

A double-blind placebo-controlled trial of antioxidant therapy in limited cutaneous systemic sclerosis.

OBJECTIVE: To evaluate the effects of a combination of micronutrient antioxidants (selenium, beta-carotene, vitamin C, vitamin E and methionine) with allopurinol in patients with limited cutaneous systemic sclerosis (SSc). METHODS: The study was designed as a placebo-controlled double-blind crossover study. A carryover effect was detected retrospectively for some of the prescribed antioxidants, and so the data were analysed as: (a) a between group comparison of the first 10 week treatment period; and (b) a within group comparison of the first and second 10-week periods in those who received placebo treatment first. Study end-points were plasma von Willebrand factor (vWF), thermographic response to a standard cold challenge, frequency and duration of Raynaud's attacks, patient opinion, and specialised biochemical parameters (fatty acid profiles, antioxidants and markers of free radical injury). RESULTS: Thirty-three patients were recruited. The median duration of Raynaud's phenomenon was 10 years (range 2 to 50 years) in the active-first group and 10 years (range 4 to 53 years) in the placebo-first group. In the 10-week study, there were no differences between the active and placebo groups in the change from baseline for vWF, for the parameters of the rewarming curve, or for patients' symptoms. Despite a rise in circulating antioxidant levels, there was no fall in markers of free radical mediated injury. In the 20-week cross-over study, patients did not experience any clinical benefit from active treatment compared to placebo. CONCLUSION: No clinical benefit could be demonstrated from active treatment. There are several possible explanations for this negative result, including the short duration of therapy. It is possible that antioxidant therapy, to be effective, needs to be given early in the SSc disease process, before the onset of irreversible tissue damage.

Prevention of recurrent pancreatitis in familial lipoprotein lipase deficiency with high-dose antioxidant therapy.

We describe a dramatic response to antioxidant therapy in three patients with familial lipoprotein lipase deficiency complicated by frequent severe episodes of pancreatitis who had failed to respond to other dietary and pharmacological measures. Antioxidant therapy may be an important advance in the management of this type of patient.

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.

Antibiotic accumulation and membrane trafficking in cystic fibrosis cells.

Cystic fibrosis (CF) results from mutations in the gene encoding the CF transmembrane conductance regulator (CFTR) which is a regulated chloride channel. The deltaF508 mutation prevents the post-translational glycosylation and membrane insertion of the protein. Severe disease follows, with the formation of a viscous mucus and subsequent chronic bacterial infection of the lungs, necessitating frequent, and often long, periods of antibiotic treatment. The pharmacokinetics of antibiotics in CF patients are abnormal, with lower blood serum levels and higher clearance rates which have never been satisfactorily explained. We found that accumulation of gentamicin in nasal polyp tissue non-CF cells was subject to regulation by the effectors and inhibitors of CFTR function; regulation was lost in deltaF508 CF cells and accumulation was more than doubled because of the inhibition of exocytosis.

A pilot study of antioxidant intake in patients with cholesterol gallstones.

Whereas macronutrient intake has been extensively investigated in an attempt to unravel the pathogenesis of human cholesterol gallstones, theoretical considerations and animal models suggest that deficits in micronutrient antioxidants may be more relevant. We report a pilot study of this aspect. The plan was to obtain 7-d weighed food inventories over a 6-mo period from equal numbers of patients who had not consciously changed their diets, patients who were on low-fat diets and age- and gender-matched controls. Food tables would be used to derive daily intakes of 16 known antioxidants, essential amino acids, and essential fatty acids. Under-reporting of food intake, a recognized drawback of this dietary method, would be sought retrospectively by reference to a key publication giving minimum cut-off limits for ratios of energy intakes to basal metabolic rates. There were 18 pairs for study. Analysis of data for the 9 pairs involving patients on their normal diets showed no differences in the intakes of energy macronutrients, and cholesterol, but the patients ingested lower amounts of 10 among 16 antioxidants (P < 0.05 for methionine, alpha-tocopherol, manganese, and vitamin D; 0.05 < P < 0.10 for cysteine, beta-carotene, vitamin C, selenium, zinc, and phosphorus). Both subsets of patients ingested lower amounts of linoleic acid (diet unchanged P = 0.009, changed P = 0.026) and several essential amino acids than did matched controls. Institution of a low-fat diet caused the expected fall in intakes of energy and saturated fatty acids such that the deficit in alpha-tocopherol was amplified, but substitution of fruit and vegetables by the patients resulted in a fortuitous increase in vitamin C, beta-carotene, and manganese intake. Retrospective analysis confirmed under-reporting of food intake by all four subsets of subjects but there was no significant difference in the mean ratio of energy intake to estimated basal metabolic rate in the subset of patients who had not consciously altered their diets and the subset of matched controls. Furthermore, the lower daily intake of alpha-tocopherol and linoleic acid by these patients persisted when results were expressed relative to total fat consumption. The results support the hypothesis that insufficiency of dietary antioxidants, particularly alpha-tocopherol, may be germane to human gallstone disease; they also suggest that low intakes of linoleic acid and essential amino acids may be relevant. Because of the small sample sizes, however, these deductions should be regarded as tentative, pending confirmation by biochemical analysis of blood and especially of hepatic bile.

A pilot study of blood antioxidant and free radical marker profiles in patients awaiting coronary artery bypass grafting.

Coronary artery bypass grafting (CABG) carries a high risk of acute pancreatitis. We report a pilot study to investigate whether pre-existing oxidative stress might underlie this susceptibility, in that a burst of free radical activity not only accompanies the reperfusion stage of CABG but seems to be a pivotal step in the pathogenesis of pancreatitis. Samples of peripheral venous blood were obtained on the morning of surgery from 8 consecutive patients (age, median and range, 62, 35-70 years) with > 75% stenosis in at least three coronary vessels and a further 8 (64, 49-70 years) who had received 1200 mg allopurinol in divided doses in the previous 48 h: the results were compared with profiles of 8 healthy controls (56, 50-60 years) with normal exercise ECG. None of the patients or controls currently smoked cigarettes and the majority drank alcohol on a social basis. Compared with controls, untreated patients had lower levels of glutathione (P < 0.001) and ascorbate (P < 0.05) in plasma, alpha-tocopherol (vitamin E as molar ratio of cholesterol, P < 0.025 and beta-carotene (P < 0.05) in serum. There was no difference in serum selenium levels, but values in patients and controls were lower than in younger controls from this area (P < 0.02). Samples from the patients contained higher concentrations of lipid peroxides than control samples (P < 0.25) but there was no evidence of excessive isomerisation of linoleic acid or oxidation of ascorbate and erythrocytes showed normal ATP and energy charge with no increase in membrane lipid peroxidisability. Treatment with allopurinol did not alter this pattern, such that the ratio of oxidised to total glutathione in plasma was higher among the 16 patients than 8 controls (P < 0.025). Habitually inadequate intakes are the best explanation for the patients' deficits in aqueous phase antioxidants; prescribed low cholesterol diets would exacerbate any prior insufficiency of lipid-phase antioxidants. Correction of these deficits during the months leading up to surgery should reduce the risk of CABG-induced acute pancreatitis.

Dietary intake of micronutrient antioxidants in relation to blood levels in patients with systemic sclerosis.

OBJECTIVE: To document habitual intakes of micronutrient antioxidants in patients with systemic sclerosis (SSc) in light of studies reporting subnormal levels of ascorbate and selenium in this patient group. METHODS: Dietary intakes of vitamin C, selenium, alpha-tocopherol, beta-carotene, and sulfur amino acid precursors of glutathione were assessed using the 7 day weighed record in 12 patients with SSc and in 12 healthy control subjects. The intakes of the first 4 substances were examined in relation to plasma/serum levels, while intakes of sulfur amino acids were examined in relation to urinary inorganic sulfate. RESULTS: Antioxidant and sulfur amino acid intakes were similar in patients and controls, although the patients had lower levels of selenium (median 74 compared to 87 milligrams in controls; p = 0.014) and of vitamin C in plasma (median 6.0 compared to 11.1 milligrams/l in controls; p = 0.08). Inorganic sulfate concentration in urine was similar in patients and controls. CONCLUSION: Our results suggest that reduced blood levels of the water soluble antioxidants selenium and ascorbic acid in patients with SSc are not due to dietary deficiency. Other explanations must therefore be sought.

Iron, ascorbate and copper status of Sowetan Blacks with calcific chronic pancreatitis.

Vitamin C can be used to overcome oxidative stress and ease pain in chronic pancreatitis. But its use is deprecated in conditions of tissue iron overload, because its bioactive form, ascorbate, can accelerate free-radical reactions that are driven by transition metals. We measured iron, ascorbate and copper in Sowetan Blacks (RSA) with chronic pancreatitis, obtaining serum/plasma from 14 consecutive patients and 15 controls. Compared with data from corresponding groups in Manchester, African samples had less ascorbate (p < 0.0001), but more caeruloplasmin (p < 0.0001). African and British controls had comparable iron and iron-binding capacity. Plasma from African patients had less ascorbate than that from African controls (p < 0.005) and in six samples, ferritin exceeded 300 micrograms/l (677 pmol/l). Low-molecular-mass iron or copper, capable of participating in free radical reactions, was not detected. British patients, had similar caeruloplasmin levels to African patients but higher ascorbate levels. There is no evidence of iron overload in our African samples. Outwardly healthy controls from Soweto have elevated levels of caeruloplasmin, possibly to compensate for dietary deficiency of ascorbate. Persistent oxidative stress is a unifying feature of chronic pancreatitis, but its degree is higher in African than British patients. Supplements of vitamin C should be safe in Blacks of southern Africa.

A radical view of gallstone aetiogenesis.

It is proposed that gallstones stem from insufficiency of micronutrient antioxidants relative to the load of oxidants and/or oxidation-prone substrates within hepatocytes in such a way that ancillary hepatobiliary resources, including bilirubin with lactoferrin and mucin, are mobilized to combat oxidative stress but inadvertently promote lithogenesis. Aberrant activities of hepatic cytochrome P450 mono-oxygenases and of haem oxygenase are integral to this template, because differential inhibition or activation of these enzymes would help to rationalize the spectrum of human gallstone composition and also the different outcomes when animals are fed the same lithogenic diets. The hypothesis is based on a decade of work on another lithogenic disease, chronic pancreatitis. It accommodates observations on human and experimental gallstones, it is testable and, as shown by studies of chronic pancreatitis, has implications for primary disease prevention.

Toward an animal model of chronic pancreatitis. Pancreatobiliary secretion in hamsters on long-term treatment with chemical inducers of cytochromes P450.

There is currently no reproducible model of the painful and lithogenic disease, chronic pancreatitis. Its biphasic evolution, from acinar cell hyperplasia and hyperactivity toward effacement of enzyme as well as bicarbonate secretory parenchyma, would be rationalized if it was linked to induction of cytochrome P450 mono-oxygenases (CYP): the increased oxidant load from long-term CYP induction eventually erodes micronutrient antioxidant defenses to injure cells. This philosophy would also rationalize the reported hepatobiliary aberrations associated with the human disease, including increases in free radical oxidation products in bile. Accordingly, pancreatic and biliary secretions were studied in Syrian golden hamsters that were reared for 6 mo on low or high (16% corn oil) fat diets that were supplemented with a prototype inducer of CYP2 (200 ppm phenobarbitone) or CYP1 (100 ppm beta naphthoflavone) enzyme families, with or without a putative enzyme inhibitor (400 ppm cimetidine). The drugs did not alter the reduction in flow rate or bicarbonate concentration of pancreatic juice caused by the high fat diet alone, but, in contrast, evoked pancreatic protein hypersecretion in a number of animals. beta naphthoflavone, but not phenobarbitone, augmented the output of biliary lipid peroxidation products irrespective of dietary fat content, and cimetidine cotreatment with either inducer did the same. We conclude: (1) that drug modifiers of CYP magnify the deleterious pancreatobiliary effects of corn oil-enriched diets and draw them closer to those found in human chronic pancreatitis; (2) that these functional derangements are accompanied by pancreatic lipoatrophy; and (3) that long-term CYP induction does not, of its own, cause fibrosis or the ductal abnormalities that generally accompany loss of pancreatic acinar cells in the human disease and, also in contrast, the changes that are caused appear to be painless.

Micronutrient antioxidant status in black South Africans with chronic pancreatitis: opportunity for prophylaxis.

Biochemical assessments of micronutrient antioxidant status were done in 14 consecutive black patients with calcific chronic pancreatitis and 15 controls at Soweto, near Johannesburg in southern Africa. The patients showed subnormal levels of vitamin C in plasma; selenium, beta-carotene and alpha-tocopherol in serum; and inorganic sulphate (as an index of long-term sulphur amino acid intake) in urine (P < 0.001 for each): furthermore, among the patients ascorbate constituted a lower fraction of vitamin C (P < 0.002), indicating heightened oxidation of the bioactive form. By comparing the results in Sowetan controls with reference ranges from Manchester, UK, the markedly lower vitamin C and, hence, ascorbate levels in the Sowetans was underlined (P < 0.001) and their selenium levels were also lower (P < 0.001), but beta-carotene, alpha-tocopherol and inorganic sulphate levels were comparable. The very low bioavailability of ascorbate among Sowetan controls is reminiscent of our previous finding in outwardly healthy people at Madras in southern India: in both these areas chronic pancreatitis is currently endemic, has a propensity to pancreatic calculi and runs a virulent course towards premature death from diabetes, malnutrition or pancreatic cancer. Considering that low ascorbate levels are a feature in patients with chronic pancreatitis who develop pancreatic calculi at Manchester and that antioxidant supplements ameliorate painful symptoms, we suggest that poor antioxidant intake may predispose underprivileged tropical communities to the disease. If so, there could be an opportunity for prophylaxis through a daily tablet containing vitamin C, perhaps along with selenium at Soweto and beta-carotene at Madras.

Evidence of toxic metabolite stress in black South Africans with chronic pancreatitis.

We report the results of a further study to test our hypothesis that toxic metabolite stress is germane to heightened free radical activity and hence to the genesis of chronic pancreatitis. Consecutive black South African patients with clinically quiescent chronic pancreatitis were studied, provided that the diagnosis had been made within the previous 2 years and that they did not have overt liver disease. All of them had been advised to stop drinking alcohol. Analysis of an early morning sample of urine showed a lower ratio of inorganic to ester sulphate (P < 0.001) and a higher ratio of D-glucaric acid to creatinine (P < 0.02) in the group of 14 patients than in 15 local controls, while plasma analysis showed a lower concentration of glutathione (GSH) in the patients (P < 0.001). This evidence of increased utilisation of phase II conjugative pathways of xenobiotic disposal was in keeping with on-going toxic metabolite stress from heightened phase I oxidative metabolism in the group of patients. Parallel studies of theophylline pharmacokinetics showed heightened drug clearance compatible with induced cytochrome P-4501A2 in two patients, whereas increased activity of gamma-glutamyl transferase in serum suggested persisting induction of P-4502E1, as by ethanol, in several others. The contemporaneous increases in free radical activity and utilisation of xenobiotic disposal pathways in Sowetan Africans with chronic pancreatitis is in line with the toxic metabolite concept of disease pathogenesis.