P. Lilja

Feedback Regulation of Pancreatic Enzyme Secretion by Intestinal Trypsin in Man

In a patient a papilla Vateri tumor completely prevented the bile-pancreatic flow into the intestine although the pancreatic juice was secreted into the bile duct via a common channel. Consequently, the bile-pancreatic juice was possible to sample via a percutaneous transhepatic cholangiography (PTC) catheter. This made it possible to study the effect of duodenal infusion of different substances on the bile-pancreatic secretion. In repeated experiments a suppression of the secretion was observed by intraduodenal trypsin as well as the patients own bile-pancreatic juice. In the presence the bile-pancreatic juice intraduodenal trypsin inhibitor infusion caused a marked stimulation of the secretion. The results are in accordance with the hypothesis that trypsin in the upper part of the intestine exerts a negative feedback regulation of the pancreatic secretion in man.

Trypsin as a Regulator of Pancreatic Secretion in the Rat

The effect of intraduodenally administered trypsin on pancreatic exocrine secretion was investigated in conscious rats surgically prepared with bile--pancreatic fistulae. Introduction of NaHCO3 into the duodenum did not influence pancreatic secretion. Reintroduction of bile--pancreatic juice into the duodenum, however, suppressed pancreatic protein output, mainly because of changes in protein concentration. Infusion of trypsin into the duodenum in the absence of intraluminal pancreatic juice significantly suppressed the secretory volume and pancreatic enzyme output; addition of trypsin inhibitor to the trypsin infusion resulted in an immediate increase of pancreatic secretion. Trypsin inhibitor per se, however, was without effect. Bile--pancreatic juice affected amylase, kipase, and trypsinogen output in a parallel fashion; after addition of trypsin inhibitor to the infusion the inhibitory effects on pancreatic enzyme output was reversed in a parallel manner. The results support the hypothesis that pancreatic exocrine secretion is regulated by a feedback mechanism exerted--at least partly--by intraluminal trypsin.

Compton Scattering from the Deuteron and Extracted Neutron Polarizabilities

Differential cross sections for Compton scattering from the deuteron were measured at MAX-Lab for incident photon energies of 55 and 66 MeV at nominal laboratory angles of 45 degrees, 125 degrees, and 135 degrees. Tagged photons were scattered from liquid deuterium and detected in three NaI spectrometers. By comparing the data with theoretical calculations in the framework of a one-boson-exchange potential model, the sum and the difference of the isospin-averaged nucleon polarizabilities, alpha(N)+beta(N)=17.4+/-3.7 and alpha(N)-beta(N)=6.4+/-2.4 (in units of 10(-4) fm(3)), have been determined. By combining the latter with the global-averaged value for alpha(p)-beta(p) and using the predictions of the Baldin sum rule for the sum of the nucleon polarizabilities, we have obtained values for the neutron electric and magnetic polarizabilities of alpha(n)=8.8+/-2.4(total)+/-3.0(model) and beta(n)=6.5-/+2.4(total)-/+3.0(model), respectively.

Influence of dietary fiber on exocrine pancreatic function in the rat.

Dietary fiber inhibits pancreatic enzyme activity--i.e., trypsin, lipase and amylase--in buffer solutions and in human duodenal juice in vitro. It is well established that oral administration of trypsin inhibitor stimulates the secretion and growth of the rat pancreas. In the present study, trypsin inhibitor (Trasylol) as well as dietary fiber such as pectin of low (37%) methoxylic esterification and wheat bran were found to stimulate pancreatic enzyme secretion in acute experiments in conscious rats with bile-pancreatic fistulae. Feeding for 10 days with wheat bran resulted in increased pancreatic weight and in increased protein and trypsinogen content. Administration of pectin of high (73%) methylic esterification caused increased pancreatic protein content and that of low methylic esterification increased pancreatic trypsinogen activity/milligram tissue. The results suggest that pectin and wheat bran may interfere with the feedback regulation of pancreatic enzyme secretion exerted by intraluminal trypsin, and, like trypsin inhibitor, have a secretagogue and trophic effect on the pancreas.

Photoneutron yields from tungsten in the energy range of the giant dipole resonance

Photoneutron production on the nuclei of high-Z components of medical accelerator heads can lead to a significant secondary dose during a course of bremsstrahlung radiotherapy. However, a quantitative evaluation of secondary neutron dose requires improved data on the photoreaction yields. These have been measured as a function of photon energy, neutron energy and neutron angle for natW, using tagged photons at the MAX-Lab photonuclear facility in Sweden. This work presents neutron yields for natW(gamma, n) and compares these with the predictions of the Monte Carlo code MCNP-GN, developed specifically to simulate photoneutron production at medical accelerators.

Intestinal Concentrations of Pancreatic Enzymes following Pancreatic Replacement Therapy

The activities of amylase, lipase, phospholipase, and trypsin in four commercially available preparations of pancreatin with different galenic and adjunctive protective properties were estimated in vitro, using human small-intestinal juice as the incubation medium. These preparations were administered to healthy subjects and to patients with severe pancreatic insufficiency, and their ability to increase the intestinal concentrations of pancreatic enzymes was evaluated. The relations between in vitro and in vivo activities were also studied. In vitro testing showed that the preparations contained high but varying activities of enzymes, with the greatest variations in lipase and trypsin. Pancreatin in the form of tablets, with or without protective measures against acid, did not cause any apparent increase in the activities of pancreatic enzymes in the upper part of the gut in patients with pancreatic insufficiency. Granulated pancreatin, on the other hand, brought about an increase in the activities of amylase, phospholipase, lipase, and trypsin. Relatively higher activities of the enzymes in granulated form reached the small intestine as compared with those of the tablets.

Pancreatic enzymic activities of commercial pancreatic enzyme preparations incubated in human small intestinal juice.

The activities of amylase, lipase, phospholipase and trypsin of twelve commercial pancreatic enzyme preparations were measured under identical conditions. Human small intestinal juice was chosen as incubation medium. A wide variation of enzymatic activities was found in preparations in tablet form contrary to preparations in granulated form. A prerequisite for a successful therapy is enzymically potent pancreatic extracts with high enzyme content per table, capsule or recommended dose of granulated preparation. Therefore, some preparations seem to be preferable to others for clinical purposes.

Effects of Intraduodenal Amylase, Lipase, Trypsin, and Bile on Pancreatic Enzyme Secretion in the Rat

The effect of duodenal infusion of trypsin, amylase, lipase and bile on pancreatic enzyme secretion was studied in conscious rats surgically prepared with bile-pancreatic fistulae. Trypsin infusion resulted in a depression of the secretory volume and protein and trypsinogen output. All these effects were reversed after additional infusion of trypsin inhibitor. Infusion of amylase or lipase in doses comparable to those of trypsin did not influence the secretory volume, protein or enzyme output. Likewise, intraduodenal bile infusion to rats with diverted bile-pancreatic juice did not change these parameters; also in rats with trypsin reinfused into the duodenum, bile infusion was without effect.

Vagal Influences on the Pancreatic Response to Intraluminal Trypsin

The significance of vagal influences on the pancreatic response to intraluminal trypsin was investigated in conscious rats surgically prepared with bile-pancreatic fistulae. Vagotomy as well as cholinergic blockage depressed the hypersecretion of protein in fistula rats. Contrary to in control rats intraduodenal trypsin infusion did not change the protein output after vagotomy or cholinergic blockage. Indirect vagal stimulation induced by insulin hypoglycemia did not further increase the protein output in rats with their bile-pancreatic juice deviated from the intestine. In these latter rats, however, intraduodenal infusion of trypsin markedly inhibited the protein secretion. The results suggest that vagal integrity is essential for the response of the pancreas to intraduodenal trypsin.

Zinc and Copper Concentrations in Serum, Blood and Liver in Moderate Experimental Pancreatic Insufficiency

Serum and liver concentrations of zinc and copper were studied in the rat after ligation of the pancreatic duct. Ligation of the bile duct was done close to the duodenum and high up in the hilum of the liver. The bile flow was by-passed into the intestine via a plastic catheter. The surgical method used was found suitable for a study of moderate exocrine pancreatic insufficiency since significant--although markedly reduced--concentrations of amylase and trypsin were estimated in intestinal contents at sacrifice 19 weeks after the operation. The serum zinc level was unaffected by duct ligation except for a slight decrease after 2 weeks. Similarly zinc in whole blood was unaffected. The copper concentration in serum was, however, significantly enhanced during in first 10 weeks. The copper zinc ration was markedly increased in duct ligated rats during the whole period. Zinc and copper concentrations in liver tissue were significantly decreased after 19 weeks. The findings suggest that a decrease function of exocrine pancreas might induce a disturbed balance of zinc and copper in the rat.