Toward an animal model of chronic pancreatitis. Pancreatobiliary secretion in hamsters on long-term treatment with chemical inducers of cytochromes P450.

There is currently no reproducible model of the painful and lithogenic disease, chronic pancreatitis. Its biphasic evolution, from acinar cell hyperplasia and hyperactivity toward effacement of enzyme as well as bicarbonate secretory parenchyma, would be rationalized if it was linked to induction of cytochrome P450 mono-oxygenases (CYP): the increased oxidant load from long-term CYP induction eventually erodes micronutrient antioxidant defenses to injure cells. This philosophy would also rationalize the reported hepatobiliary aberrations associated with the human disease, including increases in free radical oxidation products in bile. Accordingly, pancreatic and biliary secretions were studied in Syrian golden hamsters that were reared for 6 mo on low or high (16% corn oil) fat diets that were supplemented with a prototype inducer of CYP2 (200 ppm phenobarbitone) or CYP1 (100 ppm beta naphthoflavone) enzyme families, with or without a putative enzyme inhibitor (400 ppm cimetidine). The drugs did not alter the reduction in flow rate or bicarbonate concentration of pancreatic juice caused by the high fat diet alone, but, in contrast, evoked pancreatic protein hypersecretion in a number of animals. beta naphthoflavone, but not phenobarbitone, augmented the output of biliary lipid peroxidation products irrespective of dietary fat content, and cimetidine cotreatment with either inducer did the same. We conclude: (1) that drug modifiers of CYP magnify the deleterious pancreatobiliary effects of corn oil-enriched diets and draw them closer to those found in human chronic pancreatitis; (2) that these functional derangements are accompanied by pancreatic lipoatrophy; and (3) that long-term CYP induction does not, of its own, cause fibrosis or the ductal abnormalities that generally accompany loss of pancreatic acinar cells in the human disease and, also in contrast, the changes that are caused appear to be painless.

Bilateral communicating bronchopulmonary foregut malformations in an infant with multiple congenital anomalies.

Communicating bronchopulmonary foregut malformations (BPFMs) are uncommon congenital lesions which usually present in infancy with respiratory distress, which is exacerbated during feeding. We present an unusual case of bilateral oesophageal BPFM in an infant with multiple congenital anomalies.

Abnormal drug metabolism in chronic pancreatitis. Treatment with antioxidants.

Functional and morphological changes in hepatocytes, indicating induction of the drug metabolizing enzymes and free radical-mediated damage, were found in 4 patients with idiopathic chronic pancreatitis. The possibility that reflux of abnormal bile (rich in lipid peroxidation and other products generated through hepatic metabolism of xenobiotics) into the pancreatic duct may initiate pancreatic damage was negated when bile duct ligation and bile diversion did not abolish attacks of pancreatitis in 3 cases, although the evidence of reflux was indisputable in 1 of them who also had a pancreatoduodenectomy. Pancreatic acinar cells from that patient showed extensive microvesiculation, as did hepatocytes from each case. These observations suggest that pancreatic and liver damage in chronic pancreatitis proceed independently but by the same mechanism-heightened, but unmitigated, oxidative detoxification of xenobiotics by cytochromes P450. Therefore, although bile reflux is not a prerequisite, it could compound injury in the head of the gland. Antioxidants were prescribed to the 3 cases mentioned and, from the outset, to a fourth patient who showed the same liver changes. This unconventional approach has held attacks at bay during a follow-up period of 5 yr.

Cholesterol granuloma of the maxillary antrum.

A case of cholesterol granuloma of the maxillary antrum is presented, the eighth reported case in the ENT literature. It is postulated that a maxillary antral cholesterol granuloma could be associated with obstruction of the antral ostia, hemorrhage into polypoidal mucosal disease or that an antral cyst may have developed a cholesterol granuloma in its walls as a result of cholesterol precipitation. A review of the literature on cholesterol granuloma suggests that it is a condition which arises in a closed space with poor ventilation or drainage, with long-standing inflammation with effusion or hemorrhage contributing to the formation of free cholesterol crystals derived from tissue or blood breakdown products. The foreign body granuloma produced in this way is then self-perpetuating and requires complete removal for cure rather than a simple drainage procedure.

Proteolysis and lectin histochemistry.

Lectin binding to formalin-fixed, paraffin-embedded tissue can often be enhanced by pre-treatment of the sections with proteolytic enzymes. However, the pattern of staining may be profoundly influenced by the type of enzyme preparation which is used. Sites of binding of thirteen different lectins to murine ovary and thyroid gland were studied after exposure of tissue sections to crude trypsin, purified trypsin, purified alpha-chymotrypsin, pepsin, protease VII, papain, bromelain, thermolysin or elastase. With most lectins, the results obtained were similar regardless of which enzyme was used for proteolytic digestion. However, the pattern of binding of soy bean lectin to the ovary and of concanavalin A and common pea lectin to the thyroid gland was highly dependent upon the enzyme used to pre-treat the sections. In both tissues, the staining pattern seen in untreated frozen sections was similar to that found in formalin-fixed, paraffin-embedded material digested with purified trypsin, but was different from that observed after exposure of processed sections to crude trypsin. The location of binding sites after treatment of paraffin sections with chymotrypsin was the same as that after digestion with crude trypsin. Results obtained after the use of other proteolytic enzymes varied according to the tissue being studied. These findings imply that the effect of treatment with crude trypsin is due to contaminating chymotrypsin, and demonstrate that the use of purified trypsin may have advantages over other proteolytic enzymes in lectin histochemistry. The observations may also apply to other related cytochemical techniques such as immunocytochemistry.

Elimination of the non-specific binding of avidin to tissue sections.

A simple procedure is described for eliminating non-specific staining with avidin-peroxidase conjugates. Murine ovaries were embedded in either paraffin wax or epoxy resin and, after blocking endogenous peroxidase activity, were treated with 10 micrograms/ml biotinylated Pisum sativum agglutinin. Avidin-peroxidase conjugates (5 micrograms/ml), diluted in standard 0.05 M tris-buffered saline, pH 7.6, containing 0.139 M NaCl, produced considerable background coloration and intense mast cell staining in controls without the lectin. This background diminished as the ionic strength of the buffer was raised. At 0.125 M Tris-buffered saline (containing 0.347 M NaCl) the background was completely unstained, with elimination of all binding to mast cells and only minimal loss of specific lectin binding.

Recalcitrant pancreatitis: eventual control by antioxidants.

A woman, 61 years of age at her first attack of pancreatitis, had further attacks every few months during the next two years despite cholecystectomy for gall stones, and pancreato-duodenectomy for pancreas divisum and duodenal diverticulum. Since starting treatment with antioxidants, she has been free of attacks for two years.

Peroxidised linoleic acid and experimental pancreatitis.

High concentrations of lipid peroxidation (free-radical oxidation) products have been found in bile from patients with recurrent pancreatitis, and the principal component, after hydrolysis, has been identified as an isomerised form of linoleic acid -- typical concentration 25 mmol/l, compared with 4 mmol/l in controls. Chromatographically identical products can be generated by peroxidising linoleic acid using an ultraviolet (UV) source in the presence of albumin, whereas peroxidation by lipoxidase without albumin results in a constellation of products that bear no resemblance to those in biological fluids. These facts, and the suspicion that reflux of abnormal bile may be an initiating mechanism in acute pancreatitis, led us to investigate the effects of linoleic acid peroxidation products in the rat pancreas. Two concentrations of ultraviolet-peroxidised linoleic acid were used (3.6 mmol/l or 25 mmol/l, in a 2.09% solution of bile salts containing albumin 10 g/l) to simulate the human findings and, for comparison, the effects of lipoxidase-peroxidised linoleic acid, 25 mmol/l (in the 2.09% bile salt solution but without albumin), were also studied. 100 microliter of test solution was infused retrogradely into the pancreatic duct using a syringe pump. The results were assessed microscopically at 3-h intervals, and histologically at 12 h: if the animal died before the end of the experiment, the time of death was recorded. Both forms of peroxidised linoleic acid, 25 mmol/l, caused a greater degree of pancreatic injury than that produced by bile salts alone (e.g., macroscopic score at 3 h: ultraviolet, P less than 0.001; lipoxidase, P less than 0.05). Non-peroxidised linoleic acid 25 mmol/l caused less damage than ultraviolet-peroxidised linoleic acid 25 mmol/l, both macroscopically (3 h: P less than 0.01; 12 h: P less than 0.05) and on histology (P less than 0.01). Pancreatic haemorrhage was not a feature.

Malignant melanoma of the conjunctiva.

The clinicopathological features of 37 patients with invasive melanoma of the conjunctiva have been studied. Prognosis was closely related to the subsite and size of the primary tumour. Twenty of 21 patients with small localized bulbar neoplasms (95%) and four of six patients with diffuse bulbar melanomas (67%) have survived with no evidence of secondary spread. By contrast, only one of six patients with neoplasms involving the fornix (17%) and two of four (50%) with caruncular melanomas have survived. Metastatic spread was very uncommon in patients with melanomas less than 1.5 mm in maximum thickness, but the outcome of the disease in patients with tumours greater than 1.5 mm was not always bad. Treatment by local excision biopsy was followed by a high rate of conjunctival recurrence (59%). Exenteration of the affected eye guarded against the development of further orbital disease, but was not infrequently followed by the appearance of metastases. Many (62%) of the tumours appeared to have arisen in a pre-existing melanotic lesion or pigmented naevus of long-standing. Histologically, the tumours could be divided into those with an adjacent intra-epithelial component, manifest as atypical melanocytic hyperplasia in the conjunctival epithelium adjacent to the invasive melanoma, and those without (nodular melanoma). However, clear separation of the former group into the subtypes described for cutaneous melanomas proved impossible. Prognosis was not related to the type of melanoma, mitotic rate, cell type or degree of pigmentation.