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Introduction: Juvenile pilocytic astrocytomas are one of the most frequent central nervous system tumours occurring in children. While they are classified as WHO Grade I tumours, their natural progression is difficult to predict with some patients suffering significant morbidity and mortality despite showing similar light microscopic features. Activation of the MAPK pathway of cell proliferation is a consistent finding in these tumours. Studies of these tumours are largely aimed at components of this pathway in an effort to establish reliable prognostic and predictive markers. Aims and objectives: Our study was aimed at reviewing the light microscopic features and also evaluating the BRAF, p16 and protein kinase ERK components of the MAPK pathway. The findings thereof were correlated with the clinical picture to establish if these markers have any prognostic or predictive value. Materials and methods: The total number of cases retrieved was 62. The light microscopic findings were evaluated. The cases were analysed for overexpression of BRAF by fluorescence in-situ hybridisation and p16 and pERK by immunohistochemistry. Our findings were considered statistically significant if P < 0.05. Results: There were no specific light microscopic findings present in those cases associated with disease progression and recurrence. BRAF overexpression was associated with better clinical outcomes (P=0.03). There was no statistically significant correlation between p16 and pERK expression and patient outcomes. Conclusion: Overexpression of BRAF in juvenile pilocytic astrocytomas is associated with better clinical outcomes. BRAF may still serve as a therapeutic target and reduce risks associated with surgery, especially in tumours that are not surgically accessible. Further evaluation of p16, pERK and other components of the MAPK pathway of cellular proliferation will undoubtedly be useful in identifying therapeutic targets for those patients who experience disease recurrence and progression.

Recurrent ulceration following gastrectomy for peptic ulcer disease typically occurs within the first several years postoperatively. Since 1990, we have managed 20 patients who had undergone previous gastrectomy for peptic ulcer and developed ulcer recurrence more than 10 years postoperatively. Mean age at recurrence was 64 years, and the average time from original surgery to recurrent ulceration was 21 years (range, 10-36 years). All patients had undergone vagotomy and antrectomy (17 patients) or subtotal gastrectomy (3 patients). Presenting symptoms included gastric outlet obstruction (70%) and bezoar formation (60%). Endoscopic findings in this group of patients included a stenotic gastric outlet (70%) and marginal ulcerations (80%). Thirteen of 15 patients tested (87%) were Helicobacter pylori positive. Reoperation included partial resection of the gastric pouch and exploration for persistent vagus nerve. Twelve patients underwent Roux-en-Y reconstruction, whereas eight patients had Bilroth II reconstruction. Three of the latter group also had Braun enteroenterostomy performed. Good to excellent clinical results were obtained in 80 per cent of patients. The four patients with poor outcomes shared the following characteristics: 1) H. pylori-positive status, 2) presence of a preoperative bezoar, 3) Roux-en-Y reconstruction. Our current approach is to avoid Roux-en-Y construction in favor of Braun enteroenterostomy. Further prospective analysis of long-term postgastrectomy patients is needed to determine whether this clinical picture represents a new postgastrectomy syndrome.

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Numerous animal models of acute pancreatitis are utilized to assess pathophysiologic events and to evaluate therapeutic options. However, none of the small animal models simulates reversible biliary pancreatitis with long.term follow-up (weeks). The present study was designed to create a reversible model of acute biliary pancreatitis in small experimental animals. Male Sprague-Dawley rats were subjected to laparotomy, and the common bile duct was dissected free at its junction to the duodenum. Experimental animals had a polypropylene tie occluder passed around the common bile duct and brought out through a separate stab wound in the abdominal wall. The duct was occluded for 24 hr;, the blockage was then relieved and the tie withdrawn from the animal. Sham-operative animals had similar surgical procedures but without the occluder. Serum amylase values on Days 1 and 2 following surgery were significantly increased in the experimental group, but were not different from those of control animals on Day 3 or 4, suggesting reversibility of this biliary pancreatitis model. Likewise, serum bilirubin levels were increased in the experimental group on Days 1 and 2. Histologic analysis revealed edema, zymogen degranulation, inflammatory infiltration, vacuolization of acinar cells, and focal areas of fat and parenchymal necrosis in the experimental group. Only mild edema was observed in the sham- operative controls due to surgical manipulation. Pancreatic tissues obtained at 1 week postinduction of pancreatitis showed near total destruction of the architecture and dissolution of zymogen granules; in contrast, histology at the 3rd week showed almost normal-appearing pancreas with return of zymogen granules, suggesting recovery from the acute pancreatitis. This reproducible and reversible model of acute pancreatitis in the rat will provide for further studies in the pathogenesis of pancreatitis and its therapeutic interventions.

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