Increased plasma proteolytic activity due to arginine amidase in patients with pancreatitis

Purtscher's retinopathy and renal cortical necrosis: two rare vaso-occlusive complications in a patient with acute pancreatitis: a case report

BACKGROUND

Purtscher's retinopathy and renal cortical necrosis are two rare vaso-occlusive complications of acute pancreatitis. Purtscher's retinopathy causes sudden impairment of vision, which was first reported in a patient with head trauma. Subsequently, it was also reported as a complication of acute pancreatitis and few other clinical conditions. Acute pancreatitis also rarely causes renal cortical necrosis leading to acute kidney injury. However, the simultaneous presence of both complications is rarely reported.

CASE PRESENTATION

A 20-year-old Bengali man presented to our hospital with a history of acute upper abdominal pain, vomiting, anuria, and disorientation. He was ultimately found to have bilateral complete blindness due to Purtscher's retinopathy and acute kidney injury due to renal cortical necrosis, as sequelae of acute pancreatitis. He became dialysis-dependent, his vision did not recover, and he died 16 months after diagnosis.

CONCLUSIONS

This case highlights Purtscher's retinopathy and renal cortical necrosis might be considered as a recognized pair complication of acute pancreatitis.

Renal cortical necrosis and Purtscher's retinopathy in hemorrhagic pancreatitis

A patient presented with acute hemorrhagic pancreatitis complicated by both renal cortical necrosis and Purtscher's retinopathy. Either of these two complications is rare and never before have both been reported in the same patient. The patient's renal insufficiency required hemodialysis; it gradually improved over two years when dialysis could be discontinued. The patient's retinopathy included bilateral hemorrhages and cotton wool spots; visual fields and acuity remained normal. Funduscopic lesions disappeared by three months after the acute event. These two rare vasculo-occlusive complications of pancreatitis simultaneously occurring in one individual might suggest complement-mediated leukostatic mechanisms.

"Tryptic-like" activity in sera of patients with pancreatitis

Serum trypsin esterolytic activity was measured in 106 sera from 61 controls and 45 patients with pancreatitis. A trypsin specific synthetic substrate, N-alpha-benzoyl-L-arginine-paranitroanilide, was used. High levels of enzymatically active trypsin were shown to be present in serum of patients with pancreatitis. No difference between the two samples was noticed for the serum concentrations of alpha-1-antitrypsin and alpha-2-macroglobulin (the two main serum trypsin inhibitors). Active trypsin was contained in the high molecular weight fraction of plasma proteins, corresponding to a complex with alpha-2-macroglobulin. The determination of serum typsin activity as a sensitive test for detection of pancreatitis was demonstrated to be statistically significant.

A nonpancreatic source of the proteolytic-enzyme amidase and bacteriology in experimental acute pancreatitis

In previous studies of human and experimental acute pancreatitis, three main assumptions have been made. First, that the disease is due to activation of pancreatic proteolytic enzymes in the pancreas with resulting "autodigestion" of the gland. Second, that interstitial pancreatitis is a mild form of hemorrhagic pancreatitis into which it may progress, and third, that bacteria play little part, if any, in the initiation of the disease. These assumptions are now questioned. In the present study in dogs, levels of proteolytic enzymes in blood, thoracicduct lymph and peritoneal fluid were measured using benzoylarginine amide. Raised levels of amidase were found in hemorrhagic, but not with interstitial, pancreatitis, and biochemical examination of amidase suggested it was not a pancreatic protease, but with its broad specificity and stability derived from bacteria. Addition of antibiotic to the blind duodenal loop in hemorrhagic pancreatitis reduced the level of blood amidase, but Trasylol given intravenously did not, nor did it inhibit amidase in vitro. In all animals, histological examination was made of the pancreas at time of death. On bacteriology, it is concluded that experimental interstitial pancreatitis results from damage to the pancreatic duct system without infection, and haemorrhagic pancreatitis mainly from reflux of bacteria into the pancreatic ducts from the duodenum. Only bacteria such as Escherichia coli and Clostridium welchii that produce proteolytic enzymes and cytotoxins appear to be able to cause haemorrhagic pancreatitis, and these bacteria may explain the release of vasoactive polypeptides and the vascular effects. In hemorrhagic pancreatitis such bacteria were found in the pancreas, but none in interstitial pancreatitis. Evidence is given to suggest that pancreatic proteolytic enzymes are unlikely to cause the cell necrosis which is a pathological feature of hemorrhagic pancreatitis, and that "autodigestion" is likewise unlikely to be a cause of this condition. An extrapancreatic source of proteolytic enzymes from bacteria is now suggested in haemorrhagic pancreatitis, and more attention to bacteriology in human acute pancreatitis is urgently needed. Amidase levels were highest in peritoneal fluid, suggesting a rationale for peritoneal lavage in the treatment of acute pancreatitis, and it is unlikely that Trasylol can give any benefit. The assessment of treatment of acute pancreatitis will be unsatisfactory as long as the proportion of haemorrhagic to interstitial pancreatitis in any series is not known accurately.

The assay of exocrinous peptidases in clinical chemistry

The various peptidases secreted by such exocrine tissues as gastric mucosa, pancreas and prostate are usually determined by catalytic methods. Another approach utilizes immunoassay. Endopeptidases were formerly assayed with protein substrates such as hemoglobin and albumin. These techniques are increasingly replaced by more specific ones using artificial peptide derivatives as substrates, some of which allow an increase in absorbance or fluorescence to be continuously recorded. The presently available methods of assaying pepsin, pancreatic trypsin, trypsinogen and carboxypeptidase A, enterokinase and several peptidases of human sperm are reviewed.

Hypotension and release of kinin-forming enzyme into ascitic fluid exudate during experimental pancreatitis in dogs

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