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W Dummler

Publications and source records attributed to W Dummler.

At least 19 recordsLinked to original sources
PubMed1998

Increased cytosolic Ca2+ amplifies oxygen radical-induced alterations of the ultrastructure and the energy metabolism of isolated rat pancreatic acinar cells.

BACKGROUND: Oxygen radicals have been implicated as important mediators in the early pathogenesis of acute pancreatitis, but the mechanism by which they produce pancreatic tissue injury remains unclear. We have, therefore, investigated the effects of oxygen radicals on isolated rat pancreatic acinar cells as to the ultrastructure, cytosolic Ca2+ concentration and energy metabolism. METHODS: Acinar cells were exposed to an oxygen radical-generating system consisting of xanthine oxidase, hypoxanthine and chelated iron ions. Cell injury was assessed by LDH release and electron microscopy. Cytosolic Ca2+ levels and mitochondrial membrane potential were determined by flow cytometry; adenine nucleotide concentrations by HPLC. Mitochondrial dehydrogenase activity was measured by spectrophotometric assay. RESULTS: Oxygen radicals damaged the plasma membrane as shown by a 6-fold LDH increase in the incubation medium within 180 min. At the ultrastructural level, mitochondria were the most susceptible to oxidative stress. In correlation to the pronounced mitochondrial damage, the mitochondrial dehydrogenase activity declined by 70%, whereas the mitochondrial membrane potential was enhanced by 27% after 120 min. Together this may cause the 85% decrease in the ATP concentration and the corresponding increase in ADP/AMP observed in parallel. In addition, an immediate 26% increase in cytosolic Ca2+ was found, a change which could be inhibited by BAPTA, reducing cellular damage. CONCLUSION: Cytosolic Ca2+ synergizes with oxygen radicals causing alterations of the ultrastructure and energy metabolism of acinar cells which might contribute to the cellular changes found in early stages of acute pancreatitis.

Acute Disease↗
PubMed1997

Cu/Zn-SOD in human pancreatic tissue and pancreatic juice.

CONCLUSION: Cu/Zn-SOD is present in pancreatic juice and tissue. Immunohistochemical studies reveal a localization of this enzyme in islet, duct, and centroacinar cells, but to a much lower extent in pancreatic acinar cells. BACKGROUND: It is generally accepted that oxygen radicals are involved in the pathogenesis of acute and chronic pancreatitis. An imbalance of radical-generating and radical-scavenging processes is thought to lead to the damage of pancreatic acinar cells that initiate the autodigestion of the whole organ. METHODS: We investigated the distribution pattern of the cytosolic radical-scavenging enzyme, copper/zinc-superoxide dismutase (Cu/Zn-SOD), in pancreatic juice and tissue. In patients with chronic pancreatitis or pancreatic malignancies, Cu-Zn-SOD was quantitated in different fractions of pancreatic juice by means of an enzyme immunoassay using two Cu/Zn-SOD-specific monoclonal antibodies. Cryostat or paraffin sections of pancreatic tissue were analyzed by immunohistochemical techniques. RESULTS: We found this enzyme to be present in the first secretin-triggered fraction of endoscopically obtained pancreatic juice in concentrations similar to serum. In contrast, after cholecystokinin stimulation, only low levels could be found in pancreatic juice, indicating that this enzyme is not actively secreted. Interestingly, pancreatic juice of patients with chronic pancreatitis or pancreas tumor contained higher levels (25-29 ng/mL) of Cu/Zn-SOD than juice of controls without pancreatic diseases (15 ng/mL). Immunohistochemical studies of Cu/Zn-SOD in pancreatic tissue revealed a more intense staining of duct cells, islet cells, and centroacinar cells, whereas acinar cells showed almost no staining for Cu/Zn-SOD.

Adult↗
PubMed1997

Similar morphological and intracellular biochemical changes in alcoholic acute pancreatitis and ischemic acute pancreatitis in rats.

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.

Acute Disease↗
PubMed1995

Oxygen radical generation and acute pancreatitis: effects of dibutyltin dichloride/ethanol and ethanol on rat pancreas.

Recent studies suggest that enhanced release of free oxygen radicals plays an important role in the pathogenesis of acute pancreatitis. Therefore, we studied the activity of the oxygen radical generating xanthine oxidase (XOD) in pancreatic tissue from rats treated with either dibutyltin dichloride/ethanol (DBTC/EtOH: 6 mg kg-1/13.7 mg kg-1, i.v.), ethanol alone (EtOH: 13.7 mmol kg-1, i.v.), or isotonic saline (NaCl) as control. We also investigated activities of the oxygen radical scavengers superoxide dismutase (SOD) and glutathione peroxidase (GPX). In addition, levels of the lipid peroxidation marker malondialdehyde (MDA) were determined. Enhanced activity of XOD was not detected. While SOD activity 1 and 6 h after treatment was significantly more reduced by DBTC/EtOH than by EtOH alone, no difference was found thereafter. Correspondingly, both regimens diminished GPX activity. Moreover, DBTC/EtOH and EtOH rapidly increased MDA levels within 1 h, indicating release of oxygen radicals early on after administration. After 16 h the MDA concentration was still elevated only in the DBTC/EtOH group. Although similar metabolic alterations were observed in both groups, only DBTC/EtOH induced acute interstitial pancreatitis within 24 h. We conclude that (a) a tissue imbalance between oxidants and antioxidants might be of importance in the pathogenesis of DBTC/EtOH-induced acute interstitial pancreatitis; (b) although EtOH increases oxygen radical levels, additional damage is required for development of acute pancreatitis; (c) XOD does not seem to be responsible for significant oxygen radical generation; and (d) the DBTC/EtOH model is a useful tool to study acute interstitial pancreatitis in rats.

Acute Disease↗
PubMed1994

[Modification of alcohol-induced pancreatic damage in rats by soybean diet].

Alcohol-induced hypersecretion probably contributes to chronic alcoholic pancreatitis. Feeding of raw soybean flour or soybean trypsin inhibitor also stimulates protein secretion of the pancreas. Therefore, we tested whether or not the pancreatic damage is increased by additional feeding of raw soybean flour in rats fed 20% ethanol. After 11 months, we classified the morphological lesions of the pancreas into seven stages of severity calculated by means of a discriminating procedure. In order to characterize the secretory capacity of the pancreas, we measured the outputs of lipase, phospholipase, A, alpha-amylase, carboxypeptidase A, chymotrypsin, and bicarbonate. Compared with the alcohol-fed animals, the rats fed with alcohol and soya exhibited a lower average degree of morphological damage in the pancreas. Hypertrophy and hyperplasia of the parenchyma and accumulation of secretory products within the acinar cells were main features. On the other hand, some separate regions of the pancreas showed intraductal secretion precipitates as well as plugs, which were sometimes associated with atrophy of acinar cells. Feeding with soybean diet grossly reduced the alcohol-induced enzyme hypersecretion. In the early phase of alcohol-induced pancreatic damage, long-term soybean flour diet thus reduces morphological lesions and hypersecretion of the rat pancreas, whereas protein synthesis in the acinar cells appears increased. However, the precipitation of secretory products on ductal epithelium, the increased formation of plugs, and the more frequent acinar atrophies suggest the development of significant tissue injuries.

Alcoholism↗
PubMed1993

[Excretory pancreas function. Secretion of protein, calcium and citrate in probands with a normal pancreas and in patients with chronic pancreatitis].

Recent studies described an increased concentration of protein and calcium in association with a decreased concentration of citrate in pancreatic juice of patients suffering from chronic pancreatitis. These secretory changes may be of importance in the pathogenesis of chronic pancreatitis. The present study investigates pancreatic juices of 18 patients without pancreatic disease and 12 patients in an early phase of chronic pancreatitis in order to detect changes of the exocrine function of the pancreas in an early stage of the disease. In all persons the pancreatic juice was collected by endoscopic cannulation of the main pancreatic duct after i.v. stimulation with secretin and pancreozymin. The outputs and concentrations of protein, calcium and citrate were estimated. All of these parameters did not differ in control subjects and patients with chronic pancreatitis by univariate statistical analysis. However, a multivariate analysis detects differences in the biochemical composition of the secretions of controls and patients with chronic pancreatitis (efficiency of discrimination = 100%). Both in controls and in patients with chronic pancreatitis two calcium fractions were found after secretin stimulation: one secretory protein-associated fraction of 94 nmol calcium/mg protein and a protein-independent calcium fraction of 0.248 mmol/l, which diffuses paracellularly from the interstitium into the pancreatic juice. The results show that the secretory function of the exocrine pancreas is already disturbed in an early phase of chronic pancreatitis, whereas an increased lithogenity of the pancreatic juice cannot be detected.

Adult↗
PubMed1992

[Correlation between acinar cell fat accumulation and secretory capacity of the rat pancreas in the early stage of alcohol-induced pancreatopathy].

In patients exhibiting chronic alcohol abuse, the accumulation of fat droplets in pancreatic acinar cells, as well as changes in pancreatic secretion, can be interpreted as early signs of pancreatic damage. Using rats, (the animals were fed for 9 +/- 1 months with a solution of 20% v/v ethanol, combined with either a normal or a fat enhanced diet) we tested whether or not these symptoms are related both to each other and to morphological lesions of the tissue. Based on six separate histological criteria, the lesions were classified into five stages of severity. In order to characterize the secretory capacity of the pancreas, we measured the outputs of lipase, alpha-amylase, trypsin, chymotrypsin, carboxypeptidase A, elastase, and phospholipase A. Compared with the control group, we found that the alcohol-fed animals exhibited a significantly higher degree of morphological damage to the pancreas, as well as an increased frequency of fat accumulation in the acinar cells, and, with the exception of alpha-amylase, a rise in the level of enzyme secretion. In the animals exhibiting the highest degree of tissue damage, however, both fat accumulation and hypersecretion appeared to be diminished. This diminution could possibly be interpreted as the first sign of chronic pancreatitis. Increased consumption of fat did not change either the level of fat accumulation in the acinar cells, or the level of pancreatic secretion. Within the group of alcohol-fed rats, the most pronounced levels of hypersection were found in animals exhibiting cellular fat accumulation. However, the secretion levels of the alcohol-fed animals exhibiting no such fat accumulation did not differ significantly from that of the control group. Therefore, a relationship appears to exist in rats between fat accumulation in acinar cells and the level of pancreatic secretion.

Adipose Tissue↗
PubMed1990

Encapsulation of liver microsomes--a further procedure for detoxication.

Due to their partial permeability and their good mechanical properties, the symplex capsules are technically suited for an application in extracorporal detoxification. By this newly developed procedure the activity of encapsulated enzymes is considerably increased; thus, application for extracorporal detoxification seems to be advisable.

Animals↗
PubMed1990

[An improved method for the microencapsulation of liver microsomes for use in extracorporeal detoxication].

Rat liver microsomes were microencapsulated in a pure aqueous medium by means of a new technique. The wall of the microcapsules consists of a semipermeable simplex membrane which is stabilized mainly by electrostatic interactions between a polymeric polyanion (sodium cellulose sulphate) and a polymeric polycation (polydimethyldiallylammonium chloride). The metabolic as well as the mechanic parameters of the microcapsules could be markedly improved by separating the metabolic (liver microsomes) from the membrane component (sodium cellulose sulphate) in such a way that two distinct compartments are formed during the preparation of the microcapsules.

Animals↗
PubMed1990

[Lymph drainage disorder as a pathogenetic co-factor in acute pancreatitis?].

Experiments performed on 71 Wistar rats confirm that preexisting interruption of lymph drainage by ligation of the ductus thoracicus can have a major influence on the development of pancreatitis. The effect of a ductus hepatopancreaticus blockade in experimental group A (32 animals) was greatly exacerbated by previous ligation of the ductus thoracicus (experimental group B; 34 animals). Edema of the interstitial pancreatic tissue led to lipolytic necrotizing pancreatitis with a slight hemorrhagic component, increasing ascites after the 12 th hour of the experiment, and numerous abdominal fat necroses after about 19 hours, but only relatively minor necroses of acinar parenchyma cells in the pancreas. Fat tissue necroses were only found in almost 20% of the animals in group A, and these probably resulted from manipulation of the duodenum during the implantation of a shunt to divert the bile, whereas they were found in all animals of group B after the 19th hour of the experiment, usually in large numbers. The sometimes considerable increases in serum amylase and particularly lipase activity were caused by obstruction of the efferent ducts, but did not increase appreciably after disturbance of the lymph drainage systems. On the contrary, under these circumstances, drainage of the salivary edema via the peritoneal mesothelium and into retroperitoneal fat tissue must be considered responsible for ascites and the initiation of fat cell necroses by lipase and other enzymes.

Acute Disease↗
PubMed1990

[Enzymatic determination of glandular kallikrein in human pancreatic secretions].

A method for the enzymatic determination of tissue kallikrein (EC 3.4. 21.8) in human pancreatic juice using D-Val-cyclohexyl-Ala-Arg-4-nitroaniline as substrate as well as the reaction conditions optimized for 37 degrees C are described. The reaction is characterized by the following kinetic parameters, determined according to Hanes and Eisenthal, Cornish-Bowden: KM = 2.10(-5) mol/l; Vmax = 0.800 mumol/(l.s). The coefficient of intra-assay variation (N = 10) was determined to 2.54%. The detection limit of the assay was found to be 8.63 nmol/(l.s).

Clinical Enzyme Tests↗
PubMed1989

[The determination of trypsin activity in duodenal fluid with N alpha-(p-toluenesulfonyl)-L-arginine-p-nitranilide (L-TAPA)].

The conditions are optimized for the determination of trypsin activity in duodenal juice at 37 degrees C using L-TAPA as a substrate ("Bio-La-Test Trypsin", Lachema, CSSR). Most of the directions of the kit could be accepted, but optimal pH was 0.4 units below that described there. This method allows a highly specific, sensitive, and sufficiently precise determination of trypsin activity in duodenal juice.

Anilides↗
PubMed1989

[Comparative observations of internal and external quality controls in the districts of Neubrandenburg and Rostock].

A useful combination of results from internal quality control and external quality assessment is possible only if the statistical procedures of both systems involve the same limits to accept control data. These limits are shown. For 45 laboratories expected quality groups QG-T are calculated from results of internal quality control. Quality groups QG-RVL are calculated from results of external quality control assessment. In 30 cases the great difference of QG-T and QG-RVL is supposed to be caused by inaccurate performance of internal quality control.

Germany, East↗
PubMed1988

Significance of disturbed lymph flow for the pathogenesis of pancreatitis. I. Ligature of the ductus thoracicus in the rat.

To examine the significance of a disturbed lymph drainage for the pathogenesis of acute necrotizing pancreatitis, thoracic duct ligation was performed in 53 Wistar rats. Histological examination of the pancreas and analysis of serum lipase and serum amylase were carried out at various time intervals from 1 h to 42 days after initiating the experiment. Sudden stop of the lymph flow induced a long lasting pancreatic edema, initially in the perilobular interstitium and eventually also within some lobules, with scattered necroses of whole acini or single acinar cells mainly in the peripheral zones of the lobuli. In addition, a marked interstitial inflammatory infiltrate developed, resembling lipophage granulomas. This was most likely due to alymphangeal reflux of sunflower oil, applicated for the visualization of the thoracic duct. These findings suggest that changes in the lymph flow may favour the development of acute necrotizing pancreatitis.

Amylases↗
PubMed1988

[The pH dependence of lipase and trypsin activity].

We investigated in-vitro the relation of the lipase and trypsin activity, containing in native duodenale juice, to pH-values, similar to them registered in the duodenum of patients with severe exocrine insufficiency. Therefore week alcaline duodenal juice was acidified by native gastric juice or hydrochloric acid to pH-value 7, 6, 5 und 4. The remaining activity was estimated after 5, 10, 15 and 20 minutes. We determined a fast inactivation of lipase at pH 5.0 or below (incubation of 5 minutes only decreased the activity to 35% of origin), and of trypsin at pH 4.0 or below (incubation of 5 minutes at this pH-value decreased the activity to 26% of origin). According to the denaturating effect on the enzymes, there was no difference between gastric juice and hypochloric acid. It is concluded, that the activity of decreased secreted pancreatic enzymes in severe exocrine pancreatic insufficiency and also of the oral substituted enzymes is additionally reduced by acidic duodenal circumstances, so that a gastric acid neutralizing or inhibiting therapy proves as necessary.

Duodenum↗