The role of lysosomal alterations in the damage to the pancreas and liver in acute experimental pancreatitis in dogs.

The role of lysosomal hydrolases in the pathogenesis of acute pancreatitis and secondary liver injury, as an important aspect of multisystem organ failure, remains unclear. The purpose of this study was to assess the lysosomal fragility in both organs in acute experimental pancreatitis (AEP) of graded severity in dogs. In 7 dogs, the moderate (M) and in 13 dogs severe (S) variant of bile--trypsin AEP--was induced; 6 dogs were in control group (C). The 24 h survival time was 6/7 and 6/13, respectively. After that time, the dogs were sacrificed and the lysosomal enriched subfraction (L) from both organs was isolated by ultracentrifugation. The total (T) and free (F) activities of beta-glucuronidase (beta G), cathepsins (Cs) and acid phosphatase (AcP) according to Gianetto and de Duve were assayed. The fractional free activity (% F/T) was adapted as and index of lysosomal stability. The %F/T of BG in the homogenate of the pancreas in AEP(S) was higher than that in AEP(M) (92% vs. 71%, p < 0.05, and vs. 37% in C, p < 0.005). The %F/T of Cs and AcP showed a similar pattern. The %F/T of beta G in L of the liver in AEP(S) was 38% vs. 29% in AEP(M), (p < 0.05), and vs. 20% in C (p < 0.05). In AEP in dogs the %F/T activities of lysosomal hydrolases in the pancreas and liver were increased, suggesting the labilization of lysosomal membranes in severe form of this disease. Our results support the pathogenic role of lysosomal hydrolases in the damage to the pancreas and liver in acute pancreatitis.

Severity of Helicobacter-induced gastric injury correlates with gastric juice ammonia.

We postulated that ammonia produced by Helicobacter pylori may contribute to gastric mucosal injury. This hypothesis was evaluated in Helicobacter-positive patients with chronic renal failure in whom a high urea concentration might amplify this phenomenon. Gastric urea and ammonia were measured, and the severity of gastritis was evaluated by counting mononuclear and polymorphonuclear cells. High gastric ammonia and low urea in Helicobacter-positive patients, and the converse in Helicobacter-negative subjects, were observed. There was a significant correlation between gastric ammonia and interstitial polymorphonuclear leukocytes infiltration (P less than 0.05), suggesting a causal link. Eradication of Helicobacter pylori was associated with a decrease of ammonia and an increase of urea (P less than 0.01). The significant correlation between the severity of gastric inflammation and the gastric juice ammonia concentration suggests that ammonia may play a pathogenic role in Helicobacter-associated gastric injury.

Human exocrine pancreatic secretion changes associated with age.

A retrospective study of data from 2352 secretin tests has been studied. Age-related changes in the structure and function of the gastrointestinal tract have been the subject of many publications. There is a consensus that basal and stimulated gastric secretion declines with age. Studies of pancreatic secretion in the elderly are scattered in the old literature and are rather controversial. Previously published data from this laboratory indicated that age and sex have little or no influence upon the secretory responses of the human pancreas to a standard dose of secretin. Almost 20 years have passed since this publication. The present report is a retrospective analysis of the observations gathered over this period.

The pathogenesis of pancreatic pseudocysts--a canine experimental model.

In summary, an experimental model that mimics the pseudocyst formation in man was produced in dogs. The following conditions were met: encapsulated cyst containing pancreatic juice; an actively secreting pancreas with hyperamylasemia and pancreatitis; a ductal communication; and more pronounced effects with partial pancreatic ductal obstruction.

The renal lysosomes in acute experimental pancreatitis in dogs treated with prostacyclin (PGI2).

The inflammatory process in pancreas affects the function and structure of kidneys both by enzymatic toxemia and impairment of the renal circulation. In this study the stability of renal lysosomes in AEP in dogs treated with cytoprotective agent PGI2 was investigated. AEP was induced by injection of the bile and trypsin into the pancreatic duct; experiments were terminated after 12 hours. In lysosomal enriched subfraction of the kidney cortex (sedimenting in 15 000 x g) in untreated group (N = 5) relative free activity (r.f.a.) of cathepsins (Cs), acid phosphatase (APh) and beta-glucuronidase (BG) increased to 51,67 and 62% respectively, whereas in healthy dogs (N = 6) these activities were 20,38 and 25%. In dogs (N = 6) treated with PGI2 at the dose of 20 ng/kg/min. during 12 hrs, the r.f.a. of Cs, APh and BG was 18,40 and 49%, whereas in dogs (N = 5) additionally pretreated during 1 hr before induction of AEP with the same dose of PGI2, its values achieved 19,40 and 47% respectively. Our results suggest the stabilizing effect of PGI2 on kidney lysosomes damaged in acute experimental pancreatitis in dog. As possible mechanisms of prostacyclin action are discussed: limitation of necrotic process in the pancreas; improvement of renal haemodynamics; direct cytoprotective effect on the kidney.

Lysosomal hydrolases of dog kidney in superior mesenteric artery occlusion (SMAO) shock.

In 6 dogs with superior mesenteric artery occlusion (SMAO) shock and in 6 healthy animals the total and free activity of lysosomal hydrolases (acid phosphatase, betaglucuronidase and cathepsins) in the whole homogenate, the lysosomal enriched subfraction and the supernatant of kidneys were estimated. Statistically significant differences between the two groups were not observed. These results indicate that in SMAO shock, the stability of kidney lysosomes is well preserved during observed period.

Prostacyclin (PGI2) stabilises hepatic lysosomes during acute experimental pancreatitis in dogs.

In 15 mongrel dogs acute experimental pancreatitis (AEP) was induced by injection of bile and trypsin into the pancreatic duct. After 12 hrs in lysosomal enriched subfraction of the liver in untreated group (N = 5) relative free activity of cathepsins (Cs), acid phosphatase (AP) and beta-glucuronidase (beta G) increased to 50,62, and 53% respectively in comparison to the healthy dogs (N = 6) : 19,43 and 20%. In dogs with AEP treated with prostacyclin (PGI2) in the dose of 20 ng/kg X min for 12 hrs these activities of Cs, AP and beta G were lowered to 30,55 and 41% in comparison with the untreated group. In dogs with AEP (N = 5) additionally pretreated during 1 hr before the induction of AEP with the same rate of PGI2 i.v. infusion, the relative free activity of enzymes was similar to the treated group. After two hrs incubation of lysosomal enriched subfraction in acidic medium (pH = 5,0), the highest values of relative free activity were observed in untreated group, the difference being more pronounced in comparison with control group than before incubation. In those animals treated and pretreated with PGI2, postincubation activities were much lower than in untreated dogs. These results suggest the stabilising effect of PGI2 on hepatic lysosomes, damaged during the course of AEP in dogs.

Heparin effect on the activity of certain lysosomal hydrolases in dog pancreas (in vivo investigations).

The effect of heparin doses of 1.5 and 6.0 mg/kg of body weight on pancreatic lysosomes was investigated in vivo in dogs. Latent activity of beta-glucuronidase, acid phosphatase and cathepsins in whole pancreatic homogenate, in the subfraction sedimenting at 15 000 x g, and in the supernatant was determined as an index of lysosomal stability. In the whole homogenate a rise in the total activity of beta-glucuronidase was observed, proportional to heparin dose while there was no effect of heparin on the latent activity of beta-glucuronidase and acid phosphatase. On the other hand, the proportion of the latent activity of cathepsins in their total activity increased in heparin-treated dogs, which points to a direct stabilizing effect of the drug on pancreatic lysosomes in the dog. Investigations of subfractions gave, in part only, results approaching those obtained in the whole homogenate.