Influence of exocrine pancreatic insufficiency on the intraluminal pH of the proximal small intestine

Unpredictable Performance of pH-Dependent Coatings Accentuates the Need for Improved Predictive in Vitro Test Systems

First introduced in the second half of the 19th century, enteric coatings are commonly used to protect acid-labile drugs, reduce the risk of gastric side effects due to irritating drugs, or for local drug delivery to the lower gastrointestinal (GI) tract. The currently available enteric-coatings are based on pH-sensitive weakly acidic polymers. Despite the long history of their use, the causes behind their performance often being unpredictable have not been properly investigated with most of the attention being focused only on the gastric emptying. However, little attention has been given to the postgastric emptying disintegration and dissolution of these dosage forms. This lack of attention has contributed to the difficulty in predicting the in vivo behavior of these dosage forms and to cases of bioavailability problems with some enteric-coated products. Therefore, increased attention needs to be given to this issue.

The Pancreatic Duct Ligated (Mini)pig as a Model for Pancreatic Exocrine Insufficiency in Man

Modern therapy of pancreatic exocrine insufficiency (PEI) using pancreatic enzyme replacement therapy (PERT) has largely been very effective and has greatly helped in improving the nutritional status of patients with PEI and in increasing the life expectancy in cystic fibrosis. It is believed that the use of predictable large animal models could play an important role in assessing and developing new therapies. This article reviews the pancreatic duct ligated (adult) minipig as a chronic model of total PEI, with a detailed look at the influence of PEI and response to PERT on prececal compared to fecal digestibility, to directly investigate effects on protein and starch digestion and absorption. In addition, the piglet with PEI is reviewed as a model for PEI in young patients with the aim of further improving the therapy and nutritional status of young patients with cystic fibrosis.

HCO3- Transport through Anoctamin/Transmembrane Protein ANO1/TMEM16A in Pancreatic Acinar Cells Regulates Luminal pH

The identification of ANO1/TMEM16A as the likely calcium-dependent chloride channel of exocrine glands has led to a more detailed understanding of its biophysical properties. This includes a calcium-dependent change in channel selectivity and evidence that HCO3 (-) permeability can be significant. Here we use freshly isolated pancreatic acini that preserve the luminal structure to measure intraluminal pH and test the idea that ANO1/TMEM16A contributes to luminal pH balance. Our data show that, under physiologically relevant stimulation with 10 pm cholesystokinin, the luminal acid load that results from the exocytic fusion of zymogen granules is significantly blunted by HCO3 (-) buffer in comparison with HEPES, and that this is blocked by the specific TMEM16A inhibitor T16inh-A01. Furthermore, in a model of acute pancreatitis, we observed substantive luminal acidification and provide evidence that ANO1/TMEM16A acts to attenuate this pH shift. We conclude that ANO1/TMEM16A is a significant pathway in pancreatic acinar cells for HCO3 (-) secretion into the lumen.

Role of the gut in modulating lipoprotein metabolism

The intestinal production of lipoproteins is one of the key processes by which the body prepares dietary lipid for dissemination to locations throughout the body where they are required. Paramount to this is the relationship between dietary lipid and the enterocytes that line the gut, along with the processes which prepare this lipid for efficient uptake by these cells. These include those which occur in the mouth and stomach along with those which occur within the intestinal lumen itself. Additionally, the interplay between digested lipid, dual avenues for lipid uptake by enterocytes (passive and lipid transporter proteins), a system of intercellular lipid resynthesis and transport, and a complex system of lipoprotein synthesis yield a system open to significant modulation. In this review, we will attempt to outline the processes of lipid digestion, lipoprotein synthesis and the exogenous and endogenous factors which exert their influence.

Retrospective analysis to investigate the effect of concomitant use of gastric acid-suppressing drugs on the efficacy and safety of pancrelipase/pancreatin (CREON®) in patients with pancreatic exocrine insufficiency

OBJECTIVES

This study aimed to determine whether the efficacy of pancrelipase/pancreatin (CREON®) may be affected by the concomitant use of proton pump inhibitors (PPIs)/histamine-2 receptor antagonists (H2RAs).

METHODS

An analysis of integrated data from all clinical trials of pancrelipase/pancreatin supported by Abbott (34 trials, 1142 unique subjects) was conducted. All trials included patients with pancreatic exocrine insufficiency, and most cases were associated with cystic fibrosis, chronic pancreatitis, or pancreatic surgery. Study designs included single and double blind, open label, parallel group, and crossover, and most were randomized. The primary end point for this analysis was on-treatment coefficient of fat absorption (CFA) according to concomitant PPI/H2RA use (yes/no).

RESULTS

There were no meaningful differences in mean CFA values at the end of pancrelipase/pancreatin treatment by concomitant PPI/H2RA use: yes (n = 254), 82.7% versus no (n = 449), 84.2%. No meaningful differences were observed when the same analysis was carried out by disease type (cystic fibrosis, chronic pancreatitis, and pancreatic surgery).

CONCLUSIONS

This analysis of data from clinical trials enrolling patients with pancreatic exocrine insufficiency suggests that the efficacy of pancrelipase/pancreatin is not affected by concomitant PPI/H2RA use, as determined by end-of-treatment CFA values, and supports the treatment guidelines' recommendation that acid suppression is not routinely required with pancreatic enzyme replacement therapy.

Variant of the Thermomyces lanuginosus lipase with improved kinetic stability: a candidate for enzyme replacement therapy

Lipases with high kinetic stability and enzymatic efficiency in the human gastro-intestinal tract may help against exocrine pancreatic insufficiency. Here we mimic gastric conditions to study how bile salts and pH affect the stability and activity of Thermomyces lanuginosus lipase (TlL) and its stabler variant StL using spectroscopy, calorimetry and gel electrophoresis. Both enzymes resist trypsin digestion with and without bile salts. Bile salts activate native TlL and StL equally well, bind weakly to denatured TlL and StL at lower pH and precipitate native TlL and StL at pH 4. StL refolds more efficiently than TlL from gastric pH in bile salts, regaining activity when refolding from pH as low as 1.8 and above while TlL cannot go below pH 2.6. StL also unfolds 10-40 fold more slowly in the denaturant guanidinium chloride and the anionic surfactant SDS. We ascribe StL's superior performance to general alterations in its electrostatic potential which makes it more acid-resistant. These superior properties make StL a good candidate for pancreatic enzyme replacement therapy.

Enzyme replacement therapy for pancreatic insufficiency: present and future

Pancreatic enzyme replacement therapy is currently the mainstay of treatment for nutrient malabsorption secondary to pancreatic insufficiency. This treatment is safe and has few side effects. Data demonstrate efficacy in reducing steatorrhea and fat malabsorption. Effective therapy has been limited by the ability to replicate the physiologic process of enzyme delivery to the appropriate site, in general the duodenum, at the appropriate time. The challenges include enzyme destruction in the stomach, lack of adequate mixing with the chyme in the duodenum, and failing to deliver and activate at the appropriate time. Treatment is begun when clinically significant malabsorption occurs resulting in steatorrhea and weight loss. Treatment failure is addressed in a sequential fashion. Current research is aimed at studying new enzymes and delivery systems to improve the efficiency of action in the duodenum along with developing better means to monitor therapy.

Protons released during pancreatic acinar cell secretion acidify the lumen and contribute to pancreatitis in mice

BACKGROUND & AIMS

Secretory granules are acidic; cell secretion will therefore lead to extracellular acidification. We propose that during secretion, protons co-released with proteins from secretory granules of pancreatic acinar cells acidify the restricted extracellular space of the pancreatic lumen to regulate normal physiological and pathophysiological functions in this organ

METHODS

Extracellular changes in pH were quantified in real time using 2-photon microscopy analysis of pancreatic tissue fragments from mouse models of acute pancreatitis (mice given physiological concentrations [10 -20 pM] of cholecystokinin or high concentrations of [100 nM] cerulein). The effects of extracellular changes in pH on cell behavior and structures were measured.

RESULTS

With physiological stimulation, secretory granule fusion (exocytosis) caused acidification of the pancreatic lumen. Acidifications specifically affected intracellular calcium responses and accelerated the rate of recovery from agonist-evoked calcium signals. Protons therefore appear to function as negative-feedback, extracellular messengers during coupling of cell stimuli with secretion. At high concentrations of cerulein, large increases in secretory activity were associated with extreme, prolonged acidification of the luminal space. These pathological changes in pH led to disruption of intercellular junctional coupling, measured by movement of occludin and E-cadherin.

CONCLUSIONS

By measuring changes in extracellular pH in pancreas of mice, we observed that luminal acidification resulted from exocytosis of zymogen granules from acinar cells. This process is part of normal organ function but could contribute to the tissue damage in cases of acute pancreatitis.

Mechanisms and emerging treatments of the metabolic complications of chronic pancreatitis

OBJECTIVES

Exocrine and endocrine abnormalities in chronic pancreatitis contribute to the morbidity and mortality risks of the disease. Complications of exocrine insufficiency include malabsorption, vitamin deficiency syndromes, and weight loss. Oral enzyme replacement therapy is usually effective if attention is paid to factors that affect the bioavailability of enzyme preparations. Complications of endocrine insufficiency can be more difficult to treat due in part to an incomplete knowledge of their etiology.

METHODS

This review focuses on the endocrine aspects of chronic pancreatitis and highlights the observations of our laboratory on the pathogenesis of the metabolic complications of the disease.

RESULTS

In addition to decreased insulin secretory capacity, pancreatogenic (or apancreatic) diabetes is characterized by decreased or absent glucagon and pancreatic polypeptide (PP) secretion, a loss of hepatic insulin receptor (IR) expression/availability, and an impairment in hepatic IR function (phosphorylation and endocytosis). Diminished hepatic IR expression in chronic pancreatitis appears to be because of PP deficiency; laboratory animals and patients with PP deficiency demonstrate decreased hepatic IR availability that is reversed by prolonged (8-hour) PP administration. The impairment in hepatic IR function appears independent of PP deficiency but is reversed by prolonged (28-day) treatment with the insulinotropic/insulinomimetic hormone glucagon-like peptide 1. The endocytosis of hepatic IR is linked to the endocytosis of the glucose transporter 2 from the hepatocyte plasma membrane, and studies suggest that the 2 plasma membrane-bound proteins are complexed noncovalently to function and translocate as a unit after insulin binding to the hepatic IR. The process appears vigorous and sensitive enough to account for a significant reduction in hepatic glucose output and may represent a major mechanism for insulin regulation of hepatic glucose production.

CONCLUSIONS

The regulatory mechanisms of PP-mediated hepatic IR expression and combined IR and GLUT2 endocytosis after insulin binding are defective in chronic pancreatitis and contribute to the apancreatic diabetes, which characterizes this disease.

Laboratory procedures for the diagnosis of gastrointestinal tract diseases of dogs and cats

An increasing number of laboratory tests are available for diagnosis of gastrointestinal tract diseases in dogs and cats. Use of these tests can lead to more accurate and rapid diagnoses. This review discusses laboratory tests, both new and old, and the role they currently play in the evaluation of animals presented with gastrointestinal problems. A minimum database helps assess the severity of the disorder, detect extra-gastrointestinal causes of problems and assists in formulating diagnostic and therapeutic plans. Faecal examination remains one of the most important diagnostic procedures in the investigation of gastrointestinal problems. Zinc sulphate faecal flotation is an excellent routine screening technique for helminth and protozoal infections, including giardiasis. Rectal cytology can assist in the diagnosis of large bowel disorders. Interpretation of faecal immunodiagnostic tests is hampered by insufficient knowledge of test sensitivities and specificities. Routine faecal cultures are not warranted and faecal occult blood tests are rarely indicated. Serum tests for gastric inflammation are now under development. The serum trypsin-like immunoreactivity test remains the gold standard technique for the diagnosis of exocrine pancreatic insufficiency. Breath hydrogen tests can be helpful in assessing the functional relevance of mild abnormalities in small-bowel biopsy specimens. Subnormal concentrations of serum cobalamin appear to be more specific indicators of gastrointestinal disease in cats than in dogs. Tests for small intestinal bacterial overgrowth remain controversial and assessment of gastrointestinal permeability has yet to prove its value in the diagnostic assessment of companion animals with gastrointestinal problems. Faecal alpha1-protease inhibitor shows promise for the diagnosis of protein-losing enteropathy.

Conservative treatment of chronic pancreatitis

Chronic pancreatitis has been difficult to treat because the origin, pathophysiologic mechanisms and causes of unrelenting pain are so poorly understood. Furthermore, the pharmacologic agents often employed in other diseases with pain appear to be ineffective in many cases. The conservative management of chronic pancreatitis aims at (1) limiting progression and complications of the disease; (2) replacing lost exocrine and endocrine function; and (3) pain control. Thus, life style changes such as cessation of alcohol consumption and tobacco smoking, trials of pancreatic enzymes, treatment of duct obstruction and pseudocysts, and surgical therapies are currently employed. The good news is that the understanding of the underlying pathophysiological mechanisms is now advancing rapidly, and hopefully patient-specific and highly effective therapies will become available in the near future.

Analysis of the intestinal absorption of essential fatty acids in vivo in the rat

The absorption and competition kinetics of the essential fatty acids (EFAs), linoleic acid (LA), alpha-linolenic acid (alphaLnA) and arachidonic acid (AA) in vivo were studied in the perfused rat jejunum. Uptake of each EFA on its own followed saturable kinetics at low luminal concentrations, suggesting a facilitative transport process, the affinity of which increased with chain length and degree of unsaturation. Absorption of one EFA was enhanced by low, whilst competitively inhibited by high, concentrations of a second EFA. Whereas LA and alphaLnA each interfered with the absorption of one another, both had little effect on AA. There was a strong inverse correlation between the relative unsaturation of an EFA and the change in Km of its absorption observed upon inhibition with another EFA. Overall, the results indicated a specific absorptive mechanism, probably involving a transport protein, the affinity of which increased with the degree of unsaturation of the EFA.

Chronic pancreatitis: complications and management

Chronic pancreatitis is characterized by progressive and irreversible loss of pancreatic exocrine and endocrine function. In the majority of cases, particularly in Western populations, the disease is associated with alcohol abuse. The major complications of chronic pancreatitis include abdominal pain, malabsorption, and diabetes. Of these, pain is the most difficult to treat and is therefore the most frustrating symptom for both the patient and the physician. While analgesics form the cornerstone of pain therapy, a number of other treatment modalities (inhibition of pancreatic secretion, antioxidants, and surgery) have also been described. Unfortunately, the efficacy of these modalities is difficult to assess, principally because of the lack of properly controlled clinical trials. Replacement of pancreatic enzymes (particularly lipase) in the gut is the mainstay of treatment for malabsorption; the recent discovery of a bacterial lipase (with high lipolytic activity and resistance to degradation in gastric and duodenal juice) represents an important advance that may significantly increase the efficacy of enzyme replacement therapy by replacing the easily degradable porcine lipase found in existing enzyme preparations. Diabetes secondary to chronic pancreatitis is difficult to control and its course is often complicated by hypoglycaemic attacks. Therefore, it is essential that caution is exercised when treating this condition with insulin. This paper reviews recent research and prevailing concepts regarding the three major complications of chronic pancreatitis noted above. A comprehensive discussion of current opinion on clinical issues relating to the other known complications of chronic pancreatitis such as pseudocysts, venous thromboses, biliary and duodenal obstruction, biliary cirrhosis, and pancreatic cancer is also presented.

Post-prandial intragastric and duodenal acidity are increased in patients with chronic pancreatitis

OBJECTIVES

Patients with chronic pancreatitis and exocrine insufficiency have lower intraduodenal pH compared to controls. It has been assumed that abnormal low intraduodenal pH in these patients not only results from impaired pancreatic bicarbonate secretion but also from an increased gastric acid load to the duodenum.

METHODS

We have tested this hypothesis by combined intragastric and intraduodenal 24 h pH monitoring in nine chronic pancreatitis patients with exocrine pancreatic insufficiency and nine healthy control subjects during standardized test conditions. Postprandial gastrin and cholecystokinin release were also determined.

RESULTS

Median 24-h intraduodenal pH (5.90 vs. 6.00) and intragastric pH (1.60 vs. 1.70) were not significantly different between patients and controls. However, in the 2-h postprandial periods intraduodenal pH was below five for a significantly higher percentage of time in chronic pancreatitis patients compared to controls (lunch: 14.5% vs. 0.17%, P=0.011; dinner: 24.1% vs. 5.75%, P=0.05). The post-dinner intragastric pH was below three for a significantly higher percentage of time in chronic pancreatitis patients vs. controls (72.2 vs. 48.9%, P=0.04). Postprandial gastrin release was not significantly different between the two groups. Postprandial secretion of cholecystokinin (CCK), as enterogastrone, was significantly (P < 0.01) reduced in chronic pancreatitis patients (78 +/- 13 pmol/L, 120 min) compared to controls (155 +/- 14 pmol/L, 120 min).

CONCLUSIONS

Median intraduodenal and intragastric pH are not significantly decreased in patients with chronic pancreatitis and exocrine insufficiency but the postprandial time with an acidic pH in the duodenum (pH < 5) and in the stomach (pH < 3) is significantly (P </= 0.05) increased.

Pure pancreatic juice from patients with chronic pancreatitis has an impaired antibacterial activity

CONCLUSION

These data show that pure pancreatic juice of AICP patients has a markedly defective antibacterial activity. This finding might be of potential clinical interest in the understanding of the pathophysiology of the disease.

BACKGROUND

The aim of the present study was to test the antibacterial activity of pure pancreatic juice in patients with chronic pancreatitis.

METHODS

The study group consisted of ten patients with ethanol-induced chronic pancreatitis (AICP) and seven control patients free of pancreatic disease. All subjects had recently undergone a secretin-pancreozymin pancreatic function test. After an overnight fast, through a side-viewing endoscope, selective pancreatic duct cannulation was performed. After secretin stimulation, pure pancreatic juice was obtained. Three fractions of different molecular weights were separated. Samples were incubated with 1-mL suspension of 10(5) Escherichia coli ATCC 25,922, and log10 of colony-forming units were counted. Experiments were repeated by grading pancreatic juice concentration, pH of the medium, and inoculum size.

RESULTS

No significant change of pH of pure pancreatic juice appeared between AICP and controls. Starting from 6-h observation, pure pancreatic juice of AICP patients showed a significant bacterial colonization vs controls (p < 0.01). A direct correlation appeared between bacterial colonization and either pH and dilution of pancreatic juice (p < 0.001). Antibacterial activity was independent of inoculum size, enzymatic activation or inhibition, and heat treatment. The fraction with 1000-10,000 molecular weight was the one endowed with antibacterial activity.

Postprandial glucose-dependent insulinotropic polypeptide and insulin responses in patients with chronic pancreatitis with and without secondary diabetes

OBJECTIVE

To study GIP and insulin release after a test meal in patients with chronic pancreatitis with and without secondary diabetes mellitus.

METHODS

28 patients with chronic pancreatitis were classified in groups I and II according to the presence or absence of secondary diabetes mellitus. Twelve healthy subjects were included as controls. After a test meal plasma GIP levels and serum insulin levels were determined at 0, 30, 60, 120 and 180 min.

RESULTS

A significant diminished GIP response was found in the groups of patients with respect to the control group. No association could be detected with severity of pancreatic insufficiency. Higher values of GIP were demonstrated at 60 and 120 min in patients without diabetes than in patients with it.

CONCLUSIONS

An abnormal GIP response is present in cases of chronic pancreatitis irrespective of the presence or severity of pancreatic insufficiency. This response is further affected if secondary diabetes mellitus is present.

Gastrointestinal pH, motility/transit and permeability in cystic fibrosis

I reviewed the literature (1966-1994) concerning gastrointestinal (GI) pH, motility/transit, and permeability in cystic fibrosis (CF). Most studies reported were performed with very small numbers of patients, but even when considered together the published data do not confirm some generally expressed views on these topics. The only clear findings were a high incidence of gastroesophageal reflux in CF; pre- and postprandial duodenal pH is 1-2 U lower in patients with CF than in healthy controls; and small intestinal paracellular permeability is 4-10 times greater than normal in CF. Some patients showed abnormalities of lower esophageal sphincter pressure and of esophageal motility, but apart from one case study other disturbances of GI motility have not been reported. The results of hydrogen breath tests strongly suggest that oro-cecal transit is slowed in CF, but these results must be confirmed by an alternative test. Measurements of colonic transit and colonic permeability have not been reported. The few studies of gastric emptying reported are controversial. Whether GI pH, apart from duodenal pH, is normal in CF or whether a subset of patients has exceptionally acid intestinal contents requiring specialized pancreatic enzyme supplementation to normalize digestion is not clear. Finally, I briefly discuss the findings in relation to their possible impact on the pathogenesis of fibrosing colonopathy.

Effect of omeprazole on changes in gastric and upper small intestine pH levels in patients with chronic pancreatitis

Gastric and upper small intestine pH levels were measured continuously over 24 hours in patients with chronic pancreatitis, and values obtained before and after the administration of omeprazole were compared. Additionally, omeprazole was administered for 2 weeks and the fecal excretion of fat was compared before and after drug therapy. Postprandial gastric pH levels, initially 2.9 to 3.2, increased by 1.6 to 2.1 after treatment. Postprandial upper small intestine pH levels, initially 5.1 to 5.5, increased by 0.7 to 1.0. The lowest pH value of the upper small intestine was 2.2 to 2.4 postprandially; this was increased by > 1.0 after omeprazole, and the amplitude of pH variation was reduced. The cumulative proportions of intraintestinal pH strata of < or = 3, < or = 4, or < or = 5, and higher, initially being 16.4% to 17.1%, 27.4% to 31.7%, and 52.6% to 57.8%, respectively, were remarkably improved after drug treatment. Gastric pH and upper small intestine pH levels showed a positive correlation; an increase in gastric pH levels by 2 corresponded to an increase in small intestine pH levels by 1. After omeprazole administration, mean fecal excretion of fat was decreased to 4.1 +/- 2.6 g/d (range, 1.1 to 9.8 g/d) from 6.5 +/- 3.9 g/d (range, 1.6 to 13.5 g/d). Decreases in excretion of fat averaged 3.4 g/d (range, 2.2 to 4.5 g/d) in patients with steatorrhea. It was concluded that steatorrhea due to chronic pancreatitis can be improved to some extent by improving upper small intestine pH levels following the elevation of gastric pH levels after administration of omeprazole.

Effects of pancreatic digestive enzymes, sodium bicarbonate, and a proton pump inhibitor on steatorrhoea caused by pancreatic diseases

Forty-five patients with pancreatic steatorrhoea (27 with calcified pancreatitis, 13 with non-calcified pancreatitis, two with pancreaticoduodenectomy, one with total pancreatectomy, and two with pancreatic cancer) were divided into four groups and given the following medication for 2 to 4 weeks: 4 to 6 g/day of sodium bicarbonate (group I); 9 g/day of high-lipase pancreatin (lipase, 56,600 U/g, Fédération Internationale Pharmaceutique (FIP); group II); 12 to 24 tablets or 9.0 g of commercial pancreatic enzyme preparations (group III); or 50 mg of omeprazole (group IV). Faecal fat excretion was evaluated before and after drug administration. Faecal fat excretion was reduced by 2.9 g (range, 1.7 to 5.0 g) in group I; 8.8 g (range, 2.9 to 39.9 g) in group II; 10.8 g (range, 2.3 to 21.8 g) in group III; and 4.3 g (range, 3.6 to 5.6 g) in group IV. The pancreatic digestive enzyme preparation was more effective than sodium bicarbonate and agents that raise the pH of the upper small intestine (such as proton-pump inhibitors) in reducing faecal fat excretion. The results indicate that all of the preparations used are effective against mild pancreatic steatorrhoea. If the condition is more advanced, however, a massive dosage of pancreatic digestive enzyme and possibly the combined use of an agent to raise the pH of the upper small intestine are likely to be effective.

Pancreatic triglyceride lipase and colipase: insights into dietary fat digestion

Dietary fats have an impact on health and disease. A pancreatic exocrine protein, pancreatic triglyceride lipase, is essential for the efficient digestion of dietary fats. This enzyme requires another pancreatic exocrine protein, colipase, for full activity in the gut lumen. In addition to its importance in fat digestion, pancreatic triglyceride lipase has potential applications in medical therapy, medical diagnostics, and industry. This potential stimulated interest in lipases; radiograph during the last few years, studies applying the technologies of molecular biology and radiograph crystallography greatly increased our knowledge about pancreatic triglyceride lipase and colipase protein structure, enzyme mechanism, and gene structure. This review focuses on these recent advances and discusses models for the kinetic properties of pancreatic triglyceride lipase and for the interaction of pancreatic triglyceride lipase with colipase.

Comparative effects of adjuvant cimetidine and omeprazole during pancreatic enzyme replacement therapy

In a double-blind, randomized crossover study, the hypotheses were tested that more powerful inhibition of gastric acid secretion by adjuvant omeprazole further improves the efficacy of pancreatic enzyme replacement therapy compared to adjuvant cimetidine and that excluding the influence of pH-related factors, by virtually complete inhibition of gastric acid secretion with 60 mg omeprazole daily, does not lead to total elimination of steatorrhea. During both adjuvant cimetidine and omeprazole treatment, fecal fat excretion was significantly lower compared to pancreatin monotherapy (P < 0.01). Omeprazole showed a trend towards a more favorable decrease of fecal fat excretion compared to cimetidine but no statistically significant difference. Steatorrhea was almost never abolished, even during 60 mg omeprazole daily. Generally, pH-related factors are considered to explain an inadequate therapeutic response during pancreatic enzyme replacement therapy. However, this study indicates that in vivo other factors also play a significant role.

Influence of feeding regimen and postnatal developmental stages on antibacterial activity of pancreatic juice

Antibacterial activity of pancreatic juice in the pig (n = 8) was investigated during early postnatal development and in cattle (n = 6) receiving a different feeding regimen. For pancreatic juice collection, a catheter was surgically implanted in the pancreatic duct. Reintroduction of pancreatic juice was achieved through a T-shaped cannula in the duodenum. Pancreatic juice was collected for 30 min in all cases. In piglets, collections were carried out at 2, 5-6, and 7-10 wk of age, and in cattle, after a standard meal, 48 h starvation, and following 24 h intraduodenal glucose infusion. Antibacterial activity was tested on Micrococcus Pyogenes strain ATTC 6538P by disc agar diffusion technique using nonactivated pancreatic juice, before and after heat treatment for 15 min at 65 and 100 degrees C, respectively. Piglets showed a significant rise in antibacterial activity of pancreatic juice after weaning. In cattle, 48 h of starvation resulted in a marked suppression of antibacterial activity. This activity was found to be normal after a standard meal and comparable to that after 24-h intraduodenal glucose infusion. Heating of pancreatic juice to 65 degrees C caused a 35% increase in the antibacterial potency, whereas heating to 100 degrees C completely abolished it. Additionally, dilution of pancreatic juice to 1:10 did not affect antibacterial potency.

Relative importance of pancreatic, hepatic, and mucosal bicarbonate in duodenal neutralization of acid in anaesthetized pigs

Pancreatic and hepatic bicarbonate secretion and the disappearance rate of acid during duodenal acidification were measured simultaneously in anaesthetized pigs. Perfusion of the duodenum with HCl resulted in an increase in both hepatic and pancreatic bicarbonate secretion. During all acid loads hepatic bicarbonate secretion was significantly greater than pancreatic secretion. Furthermore, the disappearance rate of acid in the duodenum during diversion of both bile and pancreatic juice was significantly greater than the amount of acid which could be neutralized by the concomitant pancreatic bicarbonate secretion. Diversion of pancreatic juice from the duodenum did not affect the disappearance rate of acid at any acid load, whereas diversion of bile caused a significant decrease. Thus, in the anaesthetized pig the liver and the duodenal mucosa are of greater importance than the pancreas for the neutralization of acid in the duodenum. It is suggested that the importance of the pancreatic contribution to duodenal neutralization should be reevaluated in other species, including man.

Pancreatic, hepatic, and duodenal mucosal bicarbonate secretion during infusion of secretin and cholecystokinin. Evidence of the importance of hepatic bicarbonate in the neutralization of acid in the duodenum of anaesthetized pigs

The effect of infusion of secretin alone or in combination with cholecystokinin (CCK) on pancreatic, hepatic, and duodenal mucosal bicarbonate secretion was studied in anaesthetized pigs. After laparotomy, catheters were inserted into the common bile duct, the pancreatic duct, and both ends of the duodenum. Pancreatic, hepatic, and duodenal mucosal secretions were collected during intraportal infusion of increasing doses of secretin, either alone or in combination with CCK. During infusion of secretin in doses that caused physiologic increases in plasma secretin concentrations the liver produced significantly more bicarbonate than the pancreas. A physiologic dose of CCK augmented the effect of secretin on both hepatic and pancreatic bicarbonate secretion, but the hepatic production of bicarbonate was still larger than the pancreatic production. Neither secretin alone nor secretin combined with CCK caused any changes in duodenal mucosal bicarbonate secretion. These results suggest that the liver plays an important role in the neutralization of acid in the duodenum.

Fate of orally ingested enzymes in pancreatic insufficiency: comparison of two pancreatic enzyme preparations

The effect on steatorrhoea of a pH-sensitive enteric-coated pancreatic preparation (Eurobiol 25,000) was compared with a conventional pancreatic enzyme preparation (Eurobiol) in six adult patients with exocrine pancreatic insufficiency. In addition, the fate of orally ingested pancreatic enzymes in the upper digestive tract was evaluated by measuring gastric and duodenal pH, amount of enzymes in the stomach, duodenal enzyme output, and fat absorption at the angle of Treitz for the 4 hours following a standard meal. When compared with placebo, Eurobiol and Eurobiol 25,000 reduced daily faecal fat excretion by 24% (not significant) and 43% (P less than 0.05), respectively. With the conventional preparation, enzyme output and fat absorption at the duodeno-jejunal flexure were significantly improved (P less than 0.05). Marked inter-individual differences in duodenal enzyme recovery (lipase 3% to 80%; chymotrypsin 26% to 100%) and, consequently, in the reduction of steatorrhoea (0% to 67%) were observed, with the gastric emptying rate emerging as a key determinant factor. With the enteric-coated preparation, enzyme output and fat absorption at the duodenojejunal flexure were not significantly improved. Discrepancy between the marked reduction of faecal fat excretion and the low duodenal enzyme recovery could indicate that enzyme delivery from microtablets occurs further down in the small bowel. Efficacy of enteric-coated preparations could be enhanced by adding unprotected enzymes, especially in patients with rapid gastric emptying.

Clinical usefulness of dual-label Schilling test for pancreatic exocrine function

The usefulness of the pancreatic dual-label Schilling test as an indirect test of pancreatic exocrine function was evaluated. This dual-label Schilling test was based on the difference of absorption for [58Co]cobalamin bound to hog R protein and [57Co]cobalamin bound to intrinsic factor. In this study, the test was performed in 7 normal subjects, 5 patients with pancreatectomy, 12 patients with chronic pancreatitis, 10 patients with suspicion of chronic pancreatitis, and 13 patients without chronic pancreatitis. The normal lower limit (mean -2 SD) of excretion ratio for [58Co]/[57Co] in 24-h urine was 0.68. Of the 26 patients on whom endoscopic retrograde pancreatography was performed, none of the 9 patients with normal pancreatogram, 4 of the 9 patients with mild to moderate pancreatitic changes in pancreatogram, and 7 of the 8 patients with advanced pancreatitic changes in pancreatogram showed a positive value lower than the ratio of 0.68 in this test. In 28 patients examined with the direct test of pancreatic secretory capacity, 2 of the 13 patients with normal function, 6 of the 9 patients with mild dysfunction, and 5 of the 6 patients with definite dysfunction were positive in this test. The results of the pancreatic dual-label Schilling test significantly correlated with those of a direct test of pancreatic secretory capacity and the findings of pancreatitic changes in pancreatogram (p less than 0.01, chi 2 test). The ratio for [58Co]/[57Co] correlated (r = 0.73) with the maximal bicarbonate concentration in duodenal juice of the direct test of pancreatic secretory capacity. The impairment of bicarbonate output by the pancreas may adversely affect the transfer of cobalamin from R protein to intrinsic factor. It suggested that the pancreatic dual-label Schilling test is useful for detecting not only patients with severe pancreatic insufficiency but also the relatively early stage of chronic pancreatitis with bicarbonate secretory dysfunction of the pancreas.

Pancreatic enzyme replacement therapy. Importance of gastric acid secretion, H2-antagonists, and enteric coating

The relative efficacy of three commercial pancreatic enzyme supplements in improving fat absorption was studied using the [14C]triolein breath test in 12 patients with chronic pancreatitis. Two of the supplements were enteric coated. The one nonenteric coated product was studied twice: with and without ranitidine coadministration. Doses complied with the manufacturers recommendations. Baseline studies included pentagastrin-stimulated gastric acids, 72-hr fecal fat excretion, and [14C]triolein absorption while not on supplementation. Acid outputs were variable (BAO: 0.3-4.1 meq/hr; MAO: 3.5-34.6 meq/hr). Three patients had mild steatorrhea (i.e., less than 10 g/day) and the remaining severe fat malabsorption (56.9 +/- 41.5 g/day). Although fat absorption was significantly improved by all three supplements, the nonenteric coated preparation was most effective (P less than 0.001). However, laboratory analysis demonstrated that lipase content was four times greater, ie, 17,000 IU/4 tablets. Pretreatment with ranitidine failed to further improve the absorption in patients given nonenteric supplements but was effective in those found to have high or normal acid outputs (P less than 0.001). Our results suggest that the recommended dosage of enteric coated preparations is insufficient for adult patients with severe chronic pancreatitis. Secondly, the marked variability of acid secretion in such patients possibly accounts for the variability of results obtained by others on the usefulness of coadministration of antacids and H2 antagonists. Routine measurement of gastric acid secretion status may help optimize the choice and form of pancreatic enzyme supplementation.

Study to compare the enzyme activity, acid resistance and dissolution characteristics of currently available pancreatic enzyme preparations

An in vitro study of currently available pancreatic enzyme preparations was carried out to compare the three main types of product available, these being simple pancreatin preparations, enteric coated tablets and enteric coated granules. Two products from each of these types were analysed to compare their enzyme contents. The enteric coated preparations were tested for acid resistance and their pH dissolution profiles were also investigated. The measured enzyme contents were generally higher than the declared values but products' enzyme declarations remain valid for comparison. As the BP declaration for protease does not include total protease this value may be misleading. Acid resistance and pH dissolution profiles varied both between the types of preparation and between the actual products tested. The enteric coated granule preparations were more resistant to acid and released their enzyme more rapidly once the pH threshold of dissolution was reached. Of the two enteric coated granule preparations, Creon (Duphar) was more resistant to acid and released its enzyme from a slightly lower pH value.

Comparison of gastrointestinal pH in cystic fibrosis and healthy subjects

The primary objective of this study was to define the pH conditions under which supplemental pancreatic enzyme preparations must function in the upper gastrointestinal tract. The hypothesis was that normal or greater acid output in patients with cystic fibrosis (CF), combined with low pancreatic bicarbonate output, results in an acidic duodenal pH, compromising both dosage-form performance and enzyme activity. Gastrointestinal pH profiles were obtained in 10 CF and 10 healthy volunteers under fasting and postprandial conditions. A radiotelemetric monitoring method, the Heidelberg capsule, was used to continuously monitor pH. Postprandial duodenal pH was lower in CF than in healthy subjects, especially in the first postprandial hour (mean time greater than pH 6 was 5 min in CF, 11 min in healthy subjects, P less than 0.05). Based on the dissolution pH profiles of current enteric-coated pancreatic enzyme products, the duodenal postprandial pH in CF subjects may be too acidic to permit rapid dissolution of current enteric-coated dosage forms. However, the pH was above 4 more than 90% of the time on the average, suggesting that irreversible lipase inactivation in the duodenum is not likely to be a significant limitation to enzyme efficacy. Overall results suggest that slow dissolution of pH-sensitive coatings, rather than enzyme inactivation, may contribute to the failure of enteric-coated enzyme supplements to normalize fat absorption.

Role of nonpancreatic lipolytic activity in exocrine pancreatic insufficiency

Patients with exocrine pancreatic insufficiency may absorb greater than 50% of dietary fat despite the absence of measurable pancreatic lipase activity. Nonpancreatic lipolytic activity was measured in gastric and duodenal aspirates from 5 patients with exocrine pancreatic insufficiency secondary to alcoholism and in aspirates from 5 alcoholics without evidence of exocrine pancreatic dysfunction (controls). Samples were collected under fasting and postprandial conditions. All patients with exocrine pancreatic insufficiency had nonpancreatic lipolytic activity in gastric and duodenal aspirates. Lipolytic activity in gastric aspirates was not significantly different between the patients with exocrine pancreatic insufficiency and the controls during the fasting and postprandial periods. Pancreatic insufficiency was associated with significantly (p less than 0.05) higher nonpancreatic lipolytic activity in the duodenum under fasting conditions. No significant difference between the groups was found in postprandial nonpancreatic lipolytic activity. Nonpancreatic lipolytic activity accounted for approximately 90% of total lipolytic activity at the ligament of Treitz in patients with exocrine pancreatic insufficiency as opposed to 7% in the control subjects. These observations suggest a significant role for nonpancreatic lipolytic activity (lingual lipase and gastric lipase) in fat digestion in patients with pancreatic insufficiency secondary to chronic alcohol abuse.

Bile salt malabsorption in pancreatic insufficiency secondary to alcoholic pancreatitis

Twenty patients with exocrine pancreatic insufficiency secondary to alcohol abuse were studied for the presence of bile salt malabsorption. Fecal bile salts and fecal fat excretion were determined in 15 patients receiving pancreatic enzyme therapy, not receiving enzyme therapy, and on a regimen of pancreatic enzymes plus cimetidine. Serum bile salt levels were measured during fasting and postprandial conditions both during enzyme therapy and after it was stopped in 8 cases. In addition, 5 patients underwent [14C]cholylglycine breath testing during and after discontinuation of enzyme therapy. The fecal bile salt excretion varied between 610 and 3460 mg/day in the untreated patients. Treatment with pancreatic enzymes was associated with significant (p less than 0.05) reduction in fecal bile salt and fecal fat excretion. Cimetidine therapy in addition to enzyme therapy further reduced steatorrhea but failed to alter bile salt excretion significantly. Serum cholylglycine level showed significant (p less than 0.05) postprandial increase in patients receiving enzyme therapy, suggesting improved bile salt absorption. These data suggest a wide range of bile salt malabsorption in alcoholic patients with pancreatic insufficiency, which improves with pancreatic enzyme therapy.

Intraluminal pH in the stomach, duodenum, and proximal jejunum in normal subjects and patients with exocrine pancreatic insufficiency

In situ pH was measured simultaneously with microelectrodes in the stomach, duodenal bulb, midduodenum, duodenojejunal junction, and proximal jejunum. Fourteen healthy subjects and 8 patients with exocrine pancreatic insufficiency were studied under fasting conditions and for 3 h after a standard liquid meal. The luminal pH gradient was steepest in the proximal 10 cm of the duodenum, where acidity was reduced from pH 2 to pH 5 in the fasting state and from pH 1.7 to pH 4.3 in the second and third postprandial hour. Acidity was further reduced in the distal duodenum to a pH between 5 and 6 at the duodenojejunal junction. The frequent wide and rapid pH fluctuations seen in the duodenal bulb were gradually reduced along the duodenum and became rare in the jejunum. In patients with pancreatic insufficiency, duodenal or jejunal acidity did not differ significantly from the controls, with the exception of the single 10-min period occurring 70-80 min after the meal when duodenal bulb pH was 2.1 as compared with 3.1 in the normal subjects (p less than 0.05). All patients, including 2 patients with a very high duodenal acidity, demonstrated a duodenal pH gradient as steep as that found in the normal subjects, indicating sources of bicarbonate other than the pancreas.

Comparison of gastrointestinal pH in dogs and humans: implications on the use of the beagle dog as a model for oral absorption in humans

Gastrointestinal pH as a function of time was recorded for 4 beagle dogs and 10 human subjects using radiotelemetric pH measuring equipment. Results indicated that in the quiescent phase, gastric pH in the dogs (mean = 1.8 +/- 0.07 SEM) was significantly (p less than 0.05) higher than in humans (1.1 +/- 0.15). No significant difference in the time for the pH monitoring device to empty from the stomach was noted for the two species (99.8 +/- 27.2 min for dogs, 59.7 +/- 14.8 min for humans, p greater than 0.05). The fasting intestinal pH in dogs was consistently higher than in humans, with an average canine intestinal pH of 7.3 +/- 0.09 versus 6.0 +/- 0.14 for humans. The implication of these observations for extrapolation of drug absorption data from dogs to humans are discussed.

Effect of intrajejunal acidity on aqueous phase bile acid and lipid concentrations in pancreatic steatorrhoea due to cystic fibrosis

We have investigated whether jejunal hyperacidity leads to bile acid precipitation and thus limits lipid solubilisation in patients with pancreatic steatorrhoea. Jejunal contents from 12 adults with steatorrhoea due to cystic fibrosis were aspirated for three hours after a liquid test meal, and pooled according to their pH. Thirty eight per cent of the total aspirate was collected at pH less than 5 in cystic fibrosis, compared with 18% in healthy controls (p less than 0.05). Forty six per cent of the bile acids were precipitated at pH less than 5, compared with 15% at pH greater than 6 (p less than 0.01), leading to reduced aqueous phase bile acid concentration at low pH (4.7 mmol/l at pH less than 5 vs 12.5 mmol/l at pH greater than 6, p less than 0.01). Aqueous phase lipid concentrations were reduced at low pH (5.6 mmol/l at pH less than 5 vs 10.2 mmol/l at pH greater than 6, p less than 0.01). Lipolysis and total fatty acid concentrations were greatly reduced and did not vary with pH. We therefore conclude that jejunal hyperacidity leads to bile acid precipitation in pancreatic steatorrhoea due to cystic fibrosis, and imposes a further limitation on lipid solubilisation over that of lipase deficiency.

Lingual lipase in cystic fibrosis. Quantitation of enzyme activity in the upper small intestine of patients with exocrine pancreatic insufficiency

We have measured the level of lingual lipase activity in gastric and duodenal aspirates of five patients with cystic fibrosis (CF) and pancreatic insufficiency. Lingual lipase activity (measured in vitro by the hydrolysis of long-chain triglyceride, tri-[3H]olein, at pH 4.2 and expressed in nanomoles FFA released per milliliter aspirate per minute) and pH in gastric and duodenal aspirates were measured at 10-min intervals during a a 30-min basal period and at 15-min intervals during a 2-h period after the ingestion of a test meal. In gastric aspirates, lingual lipase activity decreased from basal levels of 200 +/- 34 nmol FFA released per milliliter per minute (similar to values reported previously in normal subjects (Hamosh M., H. L. Klaeveman, R. O. Wolf, and R. O. Scow, 1975, J. Clin. Invest., 55:908-913) to 79 +/- 15 nmol FFA/ml per min during the first postprandial hour and returned to basal levels during the second postprandial hour, (206 +/- 39 nmol FFA/ml per min). Duodenal aspirates, obtained during basal conditions, had lingual lipase activity similar to that in the stomach, 178 +/- 63 nmol FFA/ml per min. Enzyme activity levels were 56 +/- 14 and 113 +/- 29 during the first and second postprandial hours. Measurements of total lipase activity delivered to the ligament of Treitz showed that lingual lipase amounted to 91.22 +/- 4.06% of the total lipase activity in the upper small intestine during the 150-min study period. The basal and postprandial gastric pH levels in the five CF patients studied (3.2 +/- 0.44, 4.0 +/- 0.16, and 4.4 +/- 0.4 for basal and first and second postprandial hours, respectively) did not differ from previously reported values for normal subjects. The pH of duodenal aspirates was however significantly lower (P less than 0.001) in CF patients, both under basal conditions (5.0 +/- 0.26) and during the first and second postprandial hours (4.9 +/- 0.13 and 4.4 +/- 0.36, respectively), than in normal subjects. The low postprandial duodenal pH enables lingual lipase to act not only in the stomach but to continue the hydrolysis of dietary fat in the upper small intestine of CF patients. The data presented show that lingual lipase remains fully active in CF and accounts for greater than 90% of total lipase activity in the upper small intestine. We suggest that, because of low intestinal pH in CF, enzyme replacement therapy containing lingual lipase could improve fat absorption in CF patients to a greater extent than the pancreatic preparations now in use.

Impaired acid neutralization in the duodenum in pancreatic insufficiency

The influence of severe exocrine pancreatic disease on the acid-neutralizing capacity of the duodenum was studied in five patients with pancreatic insufficiency (PI) and six control subjects using duodenal perfusion-marker technique. Hydrochloric acid (0.1 N containing 1% PEG) was infused at constant rates (1.2, 4.5 and 7.0 ml/min) into the duodenum just distal to the duodenal bulb. Samples were aspirated from the tip of the duodenal perfusion tube located at the ligament of Treitz. All samples were analyzed for volume, pH, titrable acidity, PEG and [14C]PEG (gastric marker) determination. Patients with PI demonstrated significantly diminished ability to neutralize various acid loads as compared to controls who virtually completely neutralized acid loads in the range of maximal gastric acid secretion. Exogenous secretin did not significantly improve percent acid neutralized in PI. These data clearly indicate that patients with PI have significantly impaired ability to neutralize even small loads of acid in the duodenum.