Inhibitor-stimulated non-parallel pancreatic secretion in man: hormonal and neural regulation?

Advantages and Disadvantages of Prophylactic Abdominal Drainage in Distal Pancreatectomy

BACKGROUND

A method to completely prevent postoperative pancreatic fistula (PF) in distal pancreatectomy (DP) is lacking. Hence, prophylactic abdominal drains could be used to prevent PF from developing into life-threatening complications.

METHODS

In 152 consecutive patients undergoing DP, three drains were placed routinely toward the pancreatic stump, supra-pancreatic space, and left subphrenic space. Abdominal drains were removed after surgery gradually based on amylase levels and positivity for bacterial infection in abdominal fluids.

RESULTS

Postoperative symptomatic PF occurred in 57 of 152 patients (37.5 %). Prevalence of severe postoperative complications (Clavien-Dindo grade ≥ IIIa) was 16 %, with surgery-associated mortality observed in one patient (0.7 %). Prevalence of infection in drained abdominal fluids increased gradually and was >10 % on postoperative day (POD)-7. Severe postoperative complications led to longer postoperative hospital stays and higher treatment costs. Multivariate analyses revealed that a body mass index ≥ 25 kg/m(2), serum albumin level ≤ 3.8 g/dL, and white blood cell count at POD-3 ≥ 15,000/μL were independent predictors for development of severe postoperative complications.

CONCLUSION

Use of prophylactic abdominal drains in DP seems to be effective for preventing PF from developing into fatal complications. However, definitive criteria should be established for enhancing safety and cost efficiency of DP through selective use and early removal of prophylactic drains.

Visualization of the leakage of pancreatic juice using a chymotrypsin-activated fluorescent probe

BACKGROUND

Pancreatic fistula (PF) remains the most serious complication after digestive surgery. It is difficult to prevent because of the inability to visualize the leakage of pancreatic juice during surgery or to evaluate the protease activity of leaked fluid, which is responsible for PF formation.

METHODS

The fluorescence intensities of a chymotrypsin probe (glutaryl-phenylalanine [corrected] hydroxymethyl rhodamine green with added trypsin) in pancreatic juice and in intestinal or abdominal fluids drained after pancreatic resection were evaluated. The chymotrypsin probe was sprayed on to filter papers that had been placed on the resected pancreatic stump in patients undergoing pancreaticoduodenectomy or central pancreatectomy. The ability of this technique to visualize the leakage of pancreatic juice and predict postoperative PF formation was assessed.

RESULTS

The fluorescence intensity of the chymotrypsin probe in 76 fluid samples correlated positively with amylase levels (r(s) = 0.678, P < 0.001). The fluorescence patterns of the pancreatic stump were classified grossly into the three types: duct (fluorescence signal visualized only on the stump of the main pancreatic duct, 16 patients), diffuse (ductal stump and surrounding pancreatic parenchyma, 7) and negative (no fluorescence signal, 7). Symptomatic PFs developed in 13 of 23 patients with duct- or diffuse-type fluorescence, but in none of the seven patients with negative-type fluorescence (P = 0.008).

CONCLUSION

The chymotrypsin probe enabled determination of the protease activity in drained pancreatic fluid samples and allowed real-time visualization of pancreatic juice leakage during surgery.

The effect of protease inhibitors derived from potato formulated in a minidrink on appetite, food intake and plasma cholecystokinin levels in humans

BACKGROUND

Protease inhibitor 2 derived from potato (PI2) is claimed to reduce appetite and food intake, stimulate the satiety hormone cholecystokinin (CCK) and lower postprandial glucose peaks when taken before a meal. However, current literature is inconclusive with regard to its efficacy and mechanism. Furthermore, the potential effect of PI2 on appetite motivational ratings without an immediately following meal has not previously been reported.

OBJECTIVE

To comprehensively test the effects of 30 mg PI2 in a minidrink on appetite ratings, subsequent food intake, and plasma CCK and glucose responses.

DESIGN

Minidrinks with or without 30 mg PI2 were compared in three separate substudies (A, B and C), each using a two-way, placebo-controlled, balanced-order, cross-over design and 23 or 24 subjects (mean over groups: body mass index 25.0 kg m(-2), range 22.5-30.7 kg m(-2); age 41.3, range 18-62 years). The minidrink was given (A) 120 or (B) 30 min before an ad libitum lunch or (C) 30 min before a fixed lunch. Study parameters were self-reported satiety (substudies A and C), ad libitum meal intake (substudies A and B), and (in an n=12 subset) plasma CCK and blood glucose in all substudies. All results were analyzed using analysis of covariance. Protease-inhibitory activity of the PI2-containing minidrinks was assessed under simulated gut conditions.

RESULTS

PI2 did not differ from control for any study parameters, in any substudy, despite confirmation of the inhibitory activity of PI2.

CONCLUSIONS

In this study protease inhibition using PI2 in a minidrink at a dose of 30 mg, as commercially used, had no (functional) efficacy on a range of behavioral and physiological appetite and intake control measures.

Negative control of human pancreatic secretion: physiological mechanisms and factors

The negative control of pancreatic exocrine secretion in man occurs during the interdigestive and postprandial periods of the digestive cycle. The physiological mechanisms involved include negative feedback mechanisms, well described and accepted in animals, and controlled by the cholecystokinin- and secretin-releasing factors of pancreatic and duodenal origin, along with the active pancreatic proteases present in the upper gut. The presence of these factors and their efficacy in humans, however, have their supporters and detractors, with a possibility for reconciliation among opponents. Besides these releasing factors, hormones, mostly from the intestine, are also involved in this inhibitory process of pancreatic secretion. Somatostatin, peptide YY, pancreatic polypeptide, glucagon, ghrelin, and leptin were described as potentially involved from studies mostly performed on animals. Finally, bile and bile salts have mixed responses on this inhibition, and their effects seem to be at the intestine level with gastrointestinal hormones involved. Future studies will have to be performed in humans to determine the presence of cholecystokinin- and secretin-releasing factors and their role. Finally, the demonstrated modulatory action of hormones and bile acids in other species needs to be confirmed in humans.

Circadian pancreatic enzyme pattern and relationship between secretory and motor activity in fasting humans

It is unknown whether nonparallel pancreatic enzyme output occurs under basal conditions in humans. We aimed to determine whether the circadian or wake-sleep cycle influences the relationship among pancreatic enzymes or between pancreatic secretory and jejunal motor activity. Using orojejunal multilumen intubation, we measured enzyme outputs and proximal jejunal motility index during consecutive daytime and nighttime periods in each of seven fasting, healthy volunteers. Enzyme outputs were correlated tightly during daytime phases of wakefulness and nighttime phases of sleep (r > 0.72, P < 0.001). During nocturnal phases of wakefulness, output of proteases (r = 0.84, P < 0.001), but not of amylase and trypsin (r = 0.12), remained associated. Nocturnally, particularly during sleep, pancreatic secretory activity was directly correlated with jejunal motility index (r > 0.50, P < 0.001). In conclusion, parallel secretion of pancreatic enzymes dominates throughout the circadian cycle. Nonparallel secretion during nocturnal phases of wakefulness may be due to merely circadian effects or to the coupling of the wake-sleep and the circadian cycle. The association between fluctuations of secretory and motor activity appears to be particularly tight during the night.

Pathological evaluation, clinical chemistry and plasma cholecystokinin in neonatal and young miniature swine fed soy trypsin inhibitor from 1 to 39 weeks of age

The potential toxicity of dietary soy trypsin inhibitor (TI) was evaluated in neonatal miniature swine. From 1 to 6 weeks of age, two groups of male piglets were artificially reared in an Autosow and automatically fed either TI or control liquid diet. From 6 to 39 weeks of age, these two groups were fed either TI or control chow diet. A third group, sow control (SC), suckled from birth to 6 weeks of age, were also weaned to control chow from 6 to 39 weeks of age. Clinical chemistry and plasma cholecystokinin (CCK) determined at 6, 18, 30 and 39 weeks of age, and serum amylase activity with gross and histopathological analyses of major organs at 6 and 39 weeks of age are reported. TI had no effect on plasma CCK, serum amylase activity, or numerous clinical chemistry values. TI-fed piglets had a larger relative liver weight at 6 weeks of age. Relative pancreas weight decreased with age but was not affected by TI. Gross and histopathological analyses of major organs, except the spleen, were within normal limits. Increased incidence of extramedullary hematopoiesis was noted in the spleen of the TI group at 6 but not at 39 weeks of age. There was no consistent pattern in immunohistochemical foci for secretin, gastrin releasing polypeptide or CCK, and no change in DNA, RNA, mitotic index or nuclear density of pancreatic cells. At 6 weeks of age, TI increased pancreatic protein and amylase activity but not trypsin or chymotrypsin activity. None of the effects suggested that this dose of TI was toxic to either the neonatal or sexually mature miniature male swine.

A novel human chymotrypsin-like digestive enzyme

The gene of a novel chymotrypsin-like serine protease has been cloned from human pancreas. The chymotrypsin-like enzyme-1 gene is located on chromosome 16q22.1 in a tight cluster with four unrelated genes. The gene has seven exons with the signal and activation peptide and the three main catalytic residues forming the active site encoded by separate exons. Northern blots of pancreatic mRNA showed a major transcript of 1.0 kilobases and a minor transcript of 1.3 kilobases due to alternative polyadenylation. No transcript was found in other tissues. Its presence in pancreatic tissue, duodenal juice, and urine was demonstrated with antisera raised against synthetic peptides from the derived amino acid sequence of the gene. The peptide sequences were chosen for being most dissimilar to chymotrypsin, and the antisera obtained did not react with purified human chymotrypsin. The proteolytically active CTRL-1 has been identified in pancreatic homogenate, duodenal juice, and urine, and a recombinant CTRL-1 has been characterized. Increased pancreatic secretion of CTRL-1 was induced by protease inhibitors indicating that the enzyme is secreted from pancreas upon feedback stimulation. Both native and recombinant CTRL-1 displayed chymotrypsin- and elastase-2-like activities and hydrolyzed the amide bonds of substrates having tyrosine, phenylalanine, or leucine residues at the P1 position. The enzyme was active over a broad pH range (6.5-9. 0), with a maximum at pH 8.0-8.5. CTRL-1 was produced as a zymogen of 264 amino acids as deduced from the gene sequence, with a sequence identity of 54% with human chymotrypsin B. The number and location of intron/exon junctions as well as the sequence similarity to chymotrypsin both at the DNA and protein level and the presence in duodenal juice indicate that this is a novel digestive enzyme of the chymotrypsin superfamily, albeit one with distinct physiological and biochemical features.