Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acetaldehyde (AA), the first product of ethanol metabolism, has been suggested as an important mediator in alcoholic pancreatitis, but experimental evidence has not been convincing. Prior work using the isolated perfused canine pancreas preparation has suggested that toxic oxygen metabolites generated by xanthine oxidase (XO) may mediate the early injury in pancreatitis. Xanthine oxidase is capable of oxidizing AA, and during this oxidation free radicals are released. The hypothesis that acute alcoholic pancreatitis may be initiated by AA in the presence of active XO (converted from xanthine dehydrogenase [XD]) was tested in the authors' experimental preparation by converting XD to XO by a period of ischemia, and infusing AA. Control preparations remained normal throughout the 4-hour perfusion (weight gain, 7 +/- 4 g; amylase activity, 1162 +/- 202 U/dL). One hour of ischemia or infusion of AA at 25 mg/hr or at 50 mg/hr without ischemia did not induce changes in the preparation. Acetaldehyde at 250 mg/hr induced minimal edema and weight gain (16 +/- 4 g; p less than 0.05), but not significant hyperamylasemia. Changes also were not observed when 1-hour ischemia was followed by a bolus of ethanol (1.5 g) or sodium acetate (3.0 g), or by infusion of 25 mg/hr of AA. One hour of ischemia followed by infusion of AA at 50 mg/hr or at 250 mg/hr induced edema, hemorrhage, weight gain (22 +/- 7 g [p less than 0.05] and 26 +/- 17 g [p less than 0.05]) and hyperamylasemia (2249 +/- 1034 U/dL [p less than 0.05] and 2602 +/- 1412 U/dL [p less than 0.05]). Moreover infusion of AA at 250 mg/hr after 2 hours of ischemia potentiated the weight gain (62 +/- 20 g versus 30 +/- 14 g [p less than 0.05]), but not the hyperamylasemia (3404 +/- 589 U/dL versus 2862 +/- 1525 U/dL) as compared with 2 hours of ischemia alone. Pancreatitis induced by 1 hour of ischemia followed by AA at 50 mg/hr could be inhibited by pretreatment with the free radical scavengers superoxide dismutase and catalase and ameliorated with the XO inhibitor allopurinol. The authors conclude that AA, in the presence of active XO, can initiate acute pancreatitis in the isolated canine pancreas preparation and may be important in the initiation of acute alcoholic pancreatitis in man. Toxic oxygen metabolites appear to play an important intermediary role.
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PMID:The role of acetaldehyde in the pathogenesis of acute alcoholic pancreatitis. 172 Jun 11

The influence of long-term (26 weeks) and long-term plus acute ethanol administration on the development of acute pancreatitis was studied in rats. While both these treatments alone did not induce pancreatitis in any rat, extrapancreatic fat necrosis and histologic lesions of the pancreas were found in the majority of animal 24 hours after additional establishing of a pancreatic juice edema by an obstruction/hypersecretion mechanism. Severity and frequency of findings were significantly increased by additional short-term ischemia (25 min) of the pancreas. In control rats without ethanol ingestion, the edema receded without any lesions, and after additional ischemia significantly fewer rats exhibited signs of acute pancreatitis when compared to the ethanol-treated groups. An experimental model of acute alcoholic pancreatitis is presented with ethanol ingestion, temporary ductal obstruction and stimulation of secretion being essential constituents, which may be of clinical relevance, too.
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PMID:Experimental acute pancreatitis in rats after chronic and chronic plus acute ethanol administration in combination with a pancreatic juice edema. 275 27

Evidence is increasing that individuals vary in their susceptibility to alcoholic pancreatitis. Numerous investigators have attempted to account for this individual susceptibility by studying associations between alcoholic pancreatitis and potential risk factors. Those studies, reviewed here, have focused on the amount, type, and pattern of alcohol consumption, genetic markers (such as blood groups, HLA phenotypes, alpha 1-antitrypsin, and alcohol dehydrogenase isoenzyme distribution), diet, hypertriglyceridemia, tobacco consumption, and pancreatic ischemia. Associations between pancreatitis and several of these factors have been reported, but many studies offer conflicting conclusions. A number of studies are difficult to interpret because of methodologic problems, particularly with regard to inadequate controls and small numbers of index subjects. At present, the evidence is insufficient for one to conclude that any of the above-mentioned factors are well-established risk factors for pancreatitis. As a result, individual susceptibility to alcoholic pancreatitis remains unexplained. Clarification of potential risk factors may ultimately lead to the ability to prevent this relatively common disorder, but additional, appropriately designed studies are required.
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PMID:Individual susceptibility to alcoholic pancreatitis: still an enigma. 789 93

Although alcohol is likely to have direct effects on the subcellular integrity of the pancreas, other factors arising outside the pancreas may modulate or potentiate alcohol-induced damage. Among these factors are the hepatic metabolism of ethanol to acetaldehyde (via isoenzymes of ADH), the hepatic production of free radicals, the release of G.I. hormones, pancreatic ischemia (and reperfusion injury), hyperlipemia, diet and smoking. This article summarises what is known about these extrapancreatic factors. It is suggested that the pathogenesis of alcoholic pancreatitis is multifactorial but that many studies in this field are difficult to interpret because of methodological problems, particularly with regard to inadequate controls.
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PMID:An overview of extrapancreatic factors in the pathogenesis of alcoholic pancreatitis. 897 59

Pancreatic hyperstimulation with simultaneous duct obstruction does not cause the typical features of acute pancreatitis, therefore the role of an additional challenge, such as either ethanol intoxication or short-term ischemia, was studied. Alcoholic pancreatitis was induced in 28 rats by acute ethanol intoxication (0.25 LD50) and an obstruction/hyperstimulation mechanism (clip of the biliopancreatic duct for 20 min and intravenous stimulation with 5 U of cholecystokinin and secretin each). Ischemic pancreatitis was performed by obstruction/hyperstimulation and subsequent pancreatic ischemia by clamping the supplying arteries for 40 min. The macro- and microscopic alterations were evaluated and graded by a scoring system. Additionally, the pancreas was removed in 50% of the animals and the pancreatic acini were prepared. From those acini the intracellular enzymes trypsinogen, kallikreinogen, amylase, lipase, glucuronidase, and acidic phosphatases were determined. While obstruction/hyperstimulation, 40 min of ischemia, or ethanol alone did not induce acute pancreatitis, a combination of obstruction/hyperstimulation with either ethanol or ischemia resulted in acute pancreatitis in 68 and 60% of treated rats, respectively. Similarly, both models were characterized by extrapancreatic fat necrosis and acinar necrosis at the periphery of the lobules. Almost all intracellular enzymes were elevated in both pancreatitis models compared to sham-operated controls. Both alcohol and ischemia were insults that sensitize the pancreas to develop acute pancreatitis after obstruction/hyperstimulation. Since the observed morphologic and enzymatic alterations in both models are very similar, alcohol and ischemia might have some common pathways by which they make the pancreas vulnerable to enzymatic attacks.
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PMID:Similar morphological and intracellular biochemical changes in alcoholic acute pancreatitis and ischemic acute pancreatitis in rats. 898 5

We studied the pancreatic high-energy phosphates in two models of acute pancreatitis using 31P nuclear magnetic resonance (NMR) in rats for the first time in vivo. Alcoholic pancreatitis was induced by acute ethanol intoxication and an obstruction-hyperstimulation mechanism. Taurocholate pancreatitis was generated by intraparenchymal administration of 1 ml of 1-10% taurocholate-Na+. In addition to the obligate control groups, a simple ischemia experiment was performed. The high-energy phosphates were monitored by 31P NMR spectroscopy at 2.0 T. Additionally, by means of a scoring system, the quality and quantity of pathomorphologic parameters were quantified after 24 h. 31P spectra acquired after injection of taurocholate showed an increase in inorganic phosphate with a concomitant decrease in ATP levels, similar to pancreatic ischemia. This irreversible decrease was accompanied histologically by severe pancreatic hemorrhage. After induction of alcoholic acute pancreatitis a reversible decrease in ATP was occasionally seen. Even when alcoholic pancreatitis had been fully established at 24 h, the 31P NMR spectrum was normal in all animals. In conclusion, depletion of high-energy phosphates seems to occur as a result of pancreatic cell death rather than being a cause of pancreatic necrosis. For the first time we applied in vivo NMR in the rat pancreas to study the time course in acute pancreatitis.
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PMID:Different changes in high-energy phosphates in alcoholic acute pancreatitis and taurocholate acute pancreatitis in rats using NMR spectroscopy at 2.0 T. 936 Oct 88

Despite numerous experimental and clinical investigations there is no consensus on the evolution of chronic pancreatitis (CP). In the 1970s and 1980s, Sarles persistently emphasised the de novo evolution of CP due to pancreatolithiasis. In recent years, however, clinical and morphological studies have provided strong evidence for the initial proposal of acute pancreatitis progressing to chronic pancreatitis. The so-called necrosis-fibrosis-sequence theory is supported by immunohistochemical work suggesting that inflammatory mediators primarily contribute to tissue destruction and that infiltration of pancreatic nerves by immune cells is a pathogenetic factor for the generation of pain in CP. While Sarles postulates that acinar hypersecretion and an imbalance of pancreatic stone promoting and inhibiting factors trigger the evaluation of CP, the necrosis-fibrosis-sequence theory also involves other pathomechanisms (e.g. changes in ductal permeability, ischemia, oxidative stress) which have been shown to cause (acute) pancreatic injury. Despite this unifying template, which also lessens the need to identify independent mechanisms for the pathogenesis of acute and chronic alcoholic pancreatitis, there are still open questions, e.g. on genetic factors that (like in hereditary CP) may explain the different susceptibility of the pancreas to injury and the individual immunological response.
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PMID:[New aspects in the pathophysiology of chronic pancreatitis]. 941 Jun 72