Faculty Bibliography

Studies in animal models suggest that oxygen radicals may be important in the pathogenesis of acute pancreatitis. Because glutathione is an essential component of the defense against radical-mediated cellular injury, we investigated whether pancreatic glutathione content is influenced by inducing acute pancreatitis and whether augmenting the intracellular supply of glutathione would alter the course of pancreatitis. Caerulein, a decapeptide cholecystokinin analogue, induces acute necrotizing pancreatitis in mice when given in high doses (50 micrograms/kg per h) over a period of 6 h. The pancreatic glutathione content (total, GSH + GSSG) in mice treated with high-dose caerulein fell to 17% of normal within 4 h of beginning caerulein and recovered toward normal after discontinuing caerulein treatment. Mice treated with glutathione monoethyl ester (20 mmol/kg 1 h before caerulein, 10 mmol/kg 3 and 7 h after starting caerulein) were found to have blunted depletion of pancreatic glutathione, diminished histologic evidence of pancreatitis (necrosis, inflammation, and vacuolization), and lower serum amylase values compared with mice treated with caerulein alone. These findings suggest that the profound depletion of pancreatic glutathione caused by hyperstimulation of the pancreas with caerulein is critically important in the pathogenesis of acute caerulein-induced pancreatitis.

The present studies were done to evaluate the therapeutic potential of several antioxidants and free radical scavengers in three different models of acute pancreatitis. (a) Edematous pancreatitis with acinar cells necrosis was induced by seven hourly intraperitoneal injections of 50 micrograms of caerulein per kg in mice. (b) Hemorrhagic pancreatitis was induced by feeding a choline-deficient, ethionine-supplemented (CDE) diet in mice. (c) Hemorrhagic pancreatitis was induced by retrograde infusion of 0.6 ml of 5% sodium taurocholate into the pancreatic duct in rats. The following antioxidants and free radical scavengers were given at various doses intravenously, subcutaneously, or intraperitoneally before the onset of pancreatitis: Ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one], superoxide dismutase, catalase, deferoxamine (Desferal), dimethyl sulfoxide, or allopurinol. The severity of pancreatitis was assessed at various times after its onset by determination of serum amylase and pancreatic weight (edema), by grading of histological alterations, and by determination of survival (survival determined in models of hemorrhagic pancreatitis). In general, free radical scavengers and antioxidants ameliorated edema and inflammation to a greater degree than necrosis and the increase in serum amylase. Superoxide dismutase (as did Ebselen in previous studies) exerted beneficial effects on survival in diet-induced pancreatitis in the absence of marked effects on pancreatic necrosis, suggesting that these beneficial effects are due to amelioration of extrapancreatic complications that often contribute to mortality in acute pancreatitis. None of the antioxidants had major beneficial effects in taurocholate-induced hemorrhagic pancreatitis. Thus, formation of free radicals may be important for progression and outcome in diet-induced and, to a lesser degree, in caerulein-induced pancreatitis but not at all in taurocholate-induced pancreatitis. Different models of pancreatitis may, therefore, involve different degrees and mechanisms of free radical formation. Despite the amelioration of edema and the beneficial effects on mortality seen for some antioxidants in some of the models, antioxidants and free radical scavengers appear to have only a limited potential for treatment of acute pancreatitis.

The present work evaluates the methodology and standards of acute hemorrhagic-necrotizing pancreatitis induced by feeding a choline-deficient, ethionine-supplemented (CDE) diet to mice. The diet model appears to be a good approximation of severe necrotizing human pancreatitis. Both the gross and histological appearance of the pancreatic and peripancreatic inflammation as well as the clinical and biochemical course of diet-induced pancreatitis resemble human disease. By limiting the period of feeding the diet, one can control the mortality at any desired level between 0 and 100%. Ascites, acidosis, hypoxia and hypovolemia occur in this model as well as in human pancreatitis. The time course of the morphological and biochemical alterations have extensively been studied and are, thus, well defined in this model. Despite the differences in pathogenesis of pancreatitis induced in this model versus human disease, the experimental pancreatitis and clinical pancreatitis share several pathophysiologic features. Therefore, the model is suitable to study pathophysiologic aspects of this disease. The diet model is particularly well suitable to study the potential for new therapeutic substances. The small size of the animals used, however, is a limitation for the evaluation of surgical procedures and of new diagnostic tools. Several pitfalls and problems have to be considered in order to obtain valuable data. The amount of injury produced by the CDE diet depends critically on sex, age and weight of the mice. Special care has to be taken to guarantee that the intake of the CDE diet is identical between different experimental groups. Therefore, each set of experiments needs to include a separate control group of mice which receive the CDE diet without any other special treatment. The potential benefit of an experimental therapy can be assessed by measuring survival, various biochemical and histological features, and alterations in hematocrit, pH and blood gases.

In view of the increasing number of new imaging techniques and serum tumor markers, it is not well established which combination or which order of tests may provide the most information for diagnosis of pancreatic carcinoma. This review determines the diagnostic value of the various tests and evaluates which combination of tests may provide the most information and what may be considered to be a current rational approach to the diagnosis of pancreatic carcinoma. In the present analysis endoscopic retrograde cholangiopancreatography (ERCP) provided a 92% sensitivity that exceeded the 83% and 74% sensitivities calculated for computed tomography (CT) and ultrasound, respectively. The specificity of all three imaging techniques exceeded 90%. Serum determination of CA 19-9 yielded an 83% sensitivity, which was considerably higher than sensitivities of carcinoembryonic antigen and various other tumor markers. The combination of CA 19-9 and ultrasound improved the sensitivity of each test performed alone by 10-15%. Fine-needle biopsy allows diagnosis of pancreatic carcinoma with a sensitivity of 83% and an almost perfect specificity of 99%. On the basis of these data, the combination of ultrasound and determination of CA 19-9 is recommended as the initial tests when pancreatic carcinoma is suspected. CT also must be performed if ultrasound is indeterminant or inconsistent with the clinical evaluation, as well as in patients with negative ultrasound but abnormal CA 19-9. Negative results of CT, ultrasound, and CA 19-9 will exclude pancreatic carcinoma in most patients. A positive ultrasound or CT result usually leads to fine-needle biopsy, which helps avoid most diagnostic laparotomies. ERCP must be performed in patients where ultrasound, CT, and fine-needle biopsy do not clarify the diagnosis. In the majority of patients with pancreatic carcinoma, noninvasive imaging techniques such as ultrasound and CT also allow adequate staging. In some patients, however, laparoscopy and angiography may need to be performed for strategic planning of further therapy. Although modern imaging techniques and serum tumor markers allow diagnosis of pancreatic carcinomas as small as 2-3 cm and help avoid most diagnostic laparotomies, this improvement in diagnostic capability has as yet not significantly improved the prognosis.

OBJECTIVE:To determine the efficacy and safety of octreotide for treatment of refractory, profuse diarrhea in patients with the acquired immunodeficiency syndrome (AIDS). DESIGN/METHODS:A prospective, open-label study. SETTING/METHODS:Inpatient metabolic units of four university medical centers. PATIENTS/METHODS:Fifty-one patients infected with human immunodeficiency virus (HIV) who had uncontrolled diarrhea (greater than or equal to 500-mL liquid stool per day) despite treatment with maximally tolerable doses of antidiarrheal medications. INTERVENTION/METHODS:After initial baseline studies, patients received octreotide, 50 micrograms every 8 hours for 48 hours. If stool volume was not reduced to less than 250 mL/d, the dose of octreotide was increased stepwise to 100, 250, and 500 micrograms. MAIN RESULTS/RESULTS:Fifty men and one woman (mean age, 36.3 +/- 1.1 years) entered and completed the 28-day protocol (14 days of inpatient therapy and 14 days of outpatient therapy). Stool frequency and volume decreased significantly (6.5 +/- 0.5 stools per day on day 0 compared with 3.8 +/- 0.3 stools per day on day 21 [P less than 0.001] and 1604 +/- 180 mL/d on day 0 compared with 1084 +/- 162 mL/d on day 14 [P less than 0.001], respectively). Twenty-one patients (41.2%) were considered to be partial or complete responders (reduction in daily stool volume by greater than or equal to 50% of initial collections or reduction to less than or equal to 250 mL/d). Of the 21 responders, 14 (67%) had no identifiable pathogens at initial screening compared with 9 of 30 (30%) nonresponders (P less than 0.01). CONCLUSION/CONCLUSIONS:Patients with AIDS-associated refractory watery diarrhea, especially those without identifiable pathogens, may respond favorably to subcutaneously administered octreotide. This drug deserves further study in a randomized, placebo-controlled trial.

This study evaluated the effects of the seleno-organic substance Ebselen [2-phenyl-1,2-benzisoselenazol-3(2H)-one] in two models of acute hemorrhagic and acute edematous pancreatitis. Ebselen is known to catalyze glutathione peroxidase-like reactions and to inhibit lipid peroxidation. Hemorrhagic pancreatitis was induced by feeding a choline-deficient, ethionine-supplemented (CDE) diet to mice for 66 h. Edematous pancreatitis was induced by 7-h subcutaneous injections of 50 micrograms/kg of cerulein in mice. Ebselen was given from the beginning of the CDE diet either as a subcutaneous injection of 100 mg/kg at 6-h intervals or was mixed in with the CDE diet to yield a daily dose of 100 mg/kg of Ebselen. In further experiments, Ebselen was given at various time intervals after the beginning of the CDE diet as subcutaneous injections of 100 mg/kg at 6-h intervals. In the cerulein model, Ebselen was given 5 min prior to each cerulein injection at doses from 10-500 mg/kg. Prophylactic administration of Ebselen given orally or subcutaneously significantly improved survival from 38.5% in the control group of saline-injected CDE-fed mice to 61.9 and 65.0%, respectively. Ebselen also reduced increases in serum amylase and pancreatic weight in the diet model. Therapeutic administration of Ebselen significantly increased survival only when injections were started 20 h after the beginning of the CDE diet (64%), but not when started after 40 h (44%). Similarly, increases in serum amylase and pancreatic weight due to the CDE diet were significantly reduced by Ebselen only when injections were started after 20 h but not when started after 40 h.(ABSTRACT TRUNCATED AT 250 WORDS)

In most patients presenting with acute pancreatitis, the cause can be established on the basis of initial history, physical examination, laboratory studies, and abdominal sonography. Patients with unexplained pancreatitis at that point are often considered to have idiopathic disease. However, a cause and, often, effective treatment to prevent recurrent pancreatitis are possible in many of these patients if an aggressive diagnostic approach is taken to discover undiagnosed hyperlipidemia, occult gallstones, abnormalities of the bile and pancreatic ducts, sphincter of Oddi dysfunction, pancreatic cancer and other tumors, and cystic fibrosis (in children and young adults).

Little is known about exocrine pancreatic secretory function in patients with acute pancreatitis, in particular during the early phase of the disease. Therefore, this study evaluates basal and stimulated pancreatic secretion in vivo and in vitro in four different models of acute pancreatitis which reflect its clinical spectrum of severity: (a) edematous pancreatitis induced in the rat by seven IP injections of 50 micrograms/kg cerulein at hourly intervals; (b) edematous pancreatitis with cellular necrosis induced in the mouse by seven IP injections of 50 micrograms/kg cerulein at hourly intervals; (c) hemorrhagic pancreatitis induced in the mouse by feeding an ethionine-supplemented, choline-deficient diet for 66 hours; and (d) hemorrhagic pancreatitis induced in the rat by retrograde infusion of 0.6 mL 5% sodium taurocholate into the pancreatic duct. Secretory studies were performed in vivo and in vitro at various times after onset of pancreatitis. The results show that the exocrine pancreas gradually became resistant to cholecystokinin stimulation after the onset of acute pancreatitis in all four animal models. Cholecystokinin-stimulated secretion was almost abolished in vivo and in vitro at the time of maximal histological damage. In vivo basal secretion was also reduced. In vitro there was an increase in basal release of amylase from isolated acini that was not caused by an increase in luminal secretion but by enzyme release from damaged cells. The time course of improvement of secretory function after acute experimental pancreatitis depended on the severity of the pancreatitis. Recovery of secretory capacity took longer after severe necrotizing pancreatitis than after edematous pancreatitis. However, the ultimate resolution of secretory function was remarkable, in particular after severe hemorrhagic pancreatitis. In all four models, secretory capacity became indistinguishable from normal before the morphological alterations had completely resolved. The present experimental data suggest that pancreatic secretion, and particularly pancreatic secretory response to cholecystokinin, may also be reduced in patients early after the onset of acute pancreatitis.