Biomedical subjects

Julia Mayerle

Publications and source records attributed to Julia Mayerle.

14 recordsLinked to original sources

PubMed2006

Suppression of transforming growth factor beta signalling aborts caerulein induced pancreatitis and eliminates restricted stimulation at high caerulein concentrations.

BACKGROUND: Transforming growth factors betas (TGF-betas) are implicated in pancreatic tissue repair but their role in acute pancreatitis is not known. To determine whether endogenous TGF-betas modulate the course of caerulein induced acute pancreatitis, caerulein was administered to wild-type (FVB-/-) and transgenic mice that are heterozygous (FVB+/-) for expression of a dominant negative type II TGF-beta receptor. METHODS: After 7 hourly supramaximal injections of caerulein, the pancreas was evaluated histologically and serum was assayed for amylase and lipase levels. Next, the effects of caerulein on amylase secretion were determined in mouse pancreatic acini, and cholecystokinin (CCK) receptor expression was assessed. RESULTS: The normal mouse pancreas was devoid of inflammatory cells whereas the pancreas from transgenic mice contained lymphocytic infiltrates. Caerulein injection in wild-type mice resulted in 6- and 36-fold increases in serum amylase and lipase levels, respectively, increased serum trypsinogen activation peptide (TAP) levels, gross oedema and a marked inflammatory response in the pancreas that consisted mainly of neutrophils and macrophages. By contrast, FVB+/- mice exhibited minimal alterations in response to caerulein with attenuated neutrophil-macrophage infiltrates. Moreover, acini from FVB+/- mice did not exhibit restricted stimulation at high caerulein concentrations, even though CCK receptor mRNA levels were not decreased. CONCLUSION: Our findings indicate that a functional TGF-beta signalling pathway may be required for caerulein to induce acute pancreatitis and for the CCK receptor to induce acinar cell damage at high ligand concentrations. Our results also support the concept that restricted stimulation at high caerulein concentrations contributes to the ability of caerulein to induce acute pancreatitis.

Acute Disease↗

PubMed2006

Germline mutations and gene polymorphism associated with human pancreatitis.

A wide range of mutations and polymorphisms in genes that relate to pancreatic function seem to be involved in the development of pancreatitis. Some of these genetic alterations lead to disease phenotypes with unequivocal mendelian inheritance patterns, whereas others seem to act as modifier genes in conjunction with environ-mental or, as yet unidentified, genetic cofactors. This article reviews germline changes in the genes for trypsin, pancreatic secretory trypsin inhibitor, the cystic fibrosis conductance regulator, lipid metabolism proteins, inflammatory mediators for cytokines, and cathepsin B.

Carrier Proteins↗

PubMed2006

Developmental and metabolic disorders of the pancreas.

The pancreas is an important exocrine and endocrine organ that develops from the dorsal and ventral anlagen during embryogenesis and arises from the endodermal lining of the duodenum within the first month of human embryonic life. A number of developmental disorders can either lead to anatomic abnormalities of the pancreas and its ducts, or can be part of complex disorders that affect multiorgan systems. Other genetic changes can lead to metabolic abnormalities that affect the pancreas exclusively or increase the lifetime risk for developing pancreatitis or pancreatic diabetes. This article reviews some of the developmental and metabolic disorders that can affect the endocrine and exocrine pancreas.

Beckwith-Wiedemann Syndrome↗

PubMed2006

Cell biology of pancreatic proteases.

More than 100 years ago it was proposed that pancreatitis essentially is a disease in which the pancreas undergoes autodigestion by its own prematurely activated digestive enzymes. Why and how digestive zymogens autoactivate within the pancreas early in the disease process has been a matter of controversy and debate. Some of the mechanisms that are considered to be involved indigestive protease activation are inherited and as of recently can be tested for clinically. Here we review the most recent progress in elucidating the mechanisms involved in the onset of pancreatitis. We specifically focus on serine and cysteine proteases in the autodigestive cascade that precedes acinar cell injury and the biochemical processes involved in their activation.

Animals↗

PubMed2006

Genetic basis and pancreatic biology of Johanson-Blizzard syndrome.

The most recent elucidation of an inherited disorder of the pancreas concerns the Johanson-Blizzard syndrome (JBS). Positional cloning identified loss-of-function mutations in the UBRI gene on the long arm of chromosome 15 to be the cause of JBS in more than a dozen patients. In patients with JBS the absence of UBRI results in early prenatal destruction of the exocrine pancreas that involves impaired apoptosis, induced necrosis, and prominent inflammation. Knockout mice with absent UBR1 expression suffer from exocrine pancreatic insufficiency and increased susceptibility to experimental pancreatitis. The UBR1 protein substrate, presumably impaired degradation of which causes JBS, is not yet known.

Abnormalities, Multiple↗

PubMed2005

Deficiency of UBR1, a ubiquitin ligase of the N-end rule pathway, causes pancreatic dysfunction, malformations and mental retardation (Johanson-Blizzard syndrome).

Johanson-Blizzard syndrome (OMIM 243800) is an autosomal recessive disorder that includes congenital exocrine pancreatic insufficiency, multiple malformations such as nasal wing aplasia, and frequent mental retardation. We mapped the disease-associated locus to chromosome 15q14-21.1 and identified mutations, mostly truncating ones, in the gene UBR1 in 12 unrelated families with Johanson-Blizzard syndrome. UBR1 encodes one of at least four functionally overlapping E3 ubiquitin ligases of the N-end rule pathway, a conserved proteolytic system whose substrates include proteins with destabilizing N-terminal residues. Pancreas of individuals with Johanson-Blizzard syndrome did not express UBR1 and had intrauterine-onset destructive pancreatitis. In addition, we found that Ubr1(-/-) mice, whose previously reported phenotypes include reduced weight and behavioral abnormalities, had an exocrine pancreatic insufficiency, with impaired stimulus-secretion coupling and increased susceptibility to pancreatic injury. Our findings indicate that deficiency of UBR1 perturbs the pancreas' acinar cells and other organs, presumably owing to metabolic stabilization of specific substrates of the N-end rule pathway.

Abnormalities, Multiple↗

PubMed2005

Current management of acute pancreatitis.

The incidence of acute pancreatitis varies considerably between regions and is estimated at 5-80 per 100,000 population. The mortality rate of acute edematous-interstitial pancreatitis is below 1%, whereas 10-24% of patients with severe acute pancreatitis die. The early prognostic factors that can be used to determine whether the clinical course is likely to be severe are three or more signs of organ failure according to the Ranson or Imrie scores, the presence of nonpancreatic complications, and the detection of pancreatic necrosis by imaging techniques. Elevated C-reactive protein levels above 130 mg/l can also predict a severe course of acute pancreatitis with high sensitivity. Although no causal treatment exists, replacing the dramatic fluid loss that takes place in the early disease phase is critical and determines the patient's prognosis. Adequate pain relief with opiates is another therapeutic priority. In patients with pancreatic necrosis, the high mortality rate between the third and fourth week after the initial episode is determined largely by the development of pancreatic infection, and can therefore be reduced by early antibiotic treatment. Early enteral nutrition for the treatment of acute pancreatitis has been shown to be superior and much more cost-effective than parenteral nutrition. Infected pancreatic necrosis or pancreatic abscess are two of the few remaining indications for open surgery in acute pancreatitis. Even when indicated, surgery is frequently delayed or even replaced by minimally invasive surgical techniques.

Acute Disease↗

PubMed2005

Extracellular cleavage of E-cadherin by leukocyte elastase during acute experimental pancreatitis in rats.

BACKGROUND & AIMS: Cadherins play an important role in cell-cell contact formation at adherens junctions. During the course of acute pancreatitis, adherens junctions are known to dissociate-a requirement for the interstitial accumulation of fluid and inflammatory cells-but the underlying mechanism is unknown. METHODS: Acute pancreatitis was induced in rats by supramaximal cerulein infusion. The pancreas and lungs were either homogenized for protein analysis or fixed for morphology. Protein sequencing was used to identify proteolytic cleavage sites and freshly prepared acini for ex vivo studies with recombinant proteases. Results were confirmed in vivo by treating experimental pancreatitis animals with specific protease inhibitors. RESULTS: A 15-kilodalton smaller variant of E-cadherin was detected in the pancreas within 60 minutes of pancreatitis, was found to be the product of E-cadherin cleavage at amino acid 394 in the extracellular domain that controls cell-contact formation, and was consistent with E-cadherin cleavage by leukocyte elastase. Employing cell culture and ex vivo acini leukocyte elastase was confirmed to cleave E-cadherin at the identified position, followed by dissociation of cell contacts and the internalization of cleaved E-cadherin to the cytosol. Inhibition of leukocyte elastase in vivo prevented E-cadherin cleavage during pancreatitis and reduced leukocyte transmigration into the pancreas. CONCLUSIONS: These data provide evidence that polymorphonuclear leukocyte elastase is involved in, and required for, the dissociation of cell-cell contacts at adherens junctions, the extracellular cleavage of E-cadherin, and, ultimately, the transmigration of leukocytes into the epithelial tissue during the initial phase of experimental pancreatitis.

Acute Disease↗

PubMed2004

Medical treatment of acute pancreatitis.

Eighty percent of all cases of acute pancreatitis are linked etiologically to gallstone disease or caused by immoderate alcohol consumption. No specific causal treatment for acute pancreatitis exists. Early prognostic factors that indicate severe disease are three or more signs on organ failure scores according to Ranson, Imrie, or Acute Physiology and Chronic Health Evaluation (APACHE) 11, extrapancreatic complications of the disease, or the detection of pancreatic necrosis on CT scans. Elevated CRP levels above 130 mg/L can also predict a severe course of acute pancreatitis. The essential medical treatment for acute pancreatitis is the correction of hypovolemia. Moreover, relief of often severe visceral pain is a high priority. Prophylactic antibiotics should be restricted to patients with necrotizing pancreatitis, infected necrosis, or other infectious complications. Enteral nutrition has no adverse effect compared with parenteral nutrition during the course of acute pancreatitis, and is probably beneficial in regard to outcome.

Acute Disease↗

PubMed2003

[Conservative treatment of acute pancreatitis].

The incidence of acute pancreatitis per 100,000 population ranges from 10 to 46. The mortality of acute edematous interstitial pancreatitis is < 1%, while patients suffering from hemorrhagic necrotizing pancreatitis die from their disease in 10-24%. 80% of all cases of acute pancreatitis are etiologically correlated to diseases of the biliary tract or an excess alcohol consumption. As of today, no specific and causal treatment for acute pancreatitis has been established. Early prognostic factors for the evaluation of the clinical course of acute eipancreatitis are three or more indicators of organ failure in the Ranson or Imrie score, the development of extrapancreatic complications or the detection of pancreatic necrosis on contrast-enhanced CT scans. Elevated C-reactive protein (CRP) levels > 130 mg/l can predict a severe course of acute pancreatitis with a high sensitivity. The foundation of medical treatment in acute pancreatitis is the substitution of fluids to counteract hypovolemia. Furthermore, the relief of sometimes severe visceral pain has the highest priority. Infusion of procaine has been found to be ineffective for this purpose. The use of antibiotics should be restricted to patients with pancreatic necrosis. Enteral nutrition has no adverse effect compared to parenteral nutrition and is likely to be beneficial to the course of pancreatitis.

APACHE↗

PubMed2003

Up-regulation, nuclear import, and tumor growth stimulation of the adhesion protein p120 in pancreatic cancer.

BACKGROUND & AIMS: Cell adhesion proteins have been implicated as tumor suppressors because they prevent malignant cells from dissociating their cell contacts. We have studied the role of p120(ctn), a recently discovered member of the cadherin/catenin family, in human pancreatic cancer. METHODS: In 32 resection specimens of pancreatic adenocarcinoma and 10 control samples the expression of p120(ctn) was studied by Northern blot, immunocytochemistry, and immunogold electron microscopy. Patient survival data, tumor grading, and staging were correlated to the experimental results. In PaTu 8889 T pancreatic cancer cells, p120(ctn) expression was suppressed with 21-nucleotide small interfering RNA (siRNA) duplexes and proliferation was determined by bromodeoxyuridine (BrdU) incorporation. RESULTS: In pancreatic cancer p120(ctn) messenger RNA (mRNA) was increased 3- to 4-fold. Although p120(ctn) was localized exclusively at cell contacts in controls it was found in the cytosol and nucleus of pancreatic cancer cells. This redistribution correlated to the degree of tumor dedifferentiation but was independent of tumor stage. The mean survival of patients with predominant membrane localization of p120(ctn) was 24 +/- 7 (SEM) months vs. 9 +/- 2 months for patients with predominant cytoplasmic p120(ctn) expression (P < 0.05). Silencing of p120(ctn) with siRNA duplexes reduced pancreatic cancer cell growth by 40%. CONCLUSIONS: Up-regulation, cytoplasmic redistribution, and nuclear import of p120(ctn) are associated with a more malignant phenotype of pancreatic cancer. This study further represents conclusive evidence for a direct involvement of p120(ctn) in malignant tumor cell proliferation. Both p120(ctn)-defective tumor cell contacts and p120(ctn)-mediated growth signals appear to contribute to the aggressive spread of pancreatic cancer.

Active Transport, Cell Nucleus↗

PubMed2003

Pathophysiology of alcohol-induced pancreatitis.

Excessive ethanol consumption is a common risk factor for acute and chronic pancreatitis. Ethanol could lead to the onset of pancreatitis in a number of ways; the most recently discovered is its effect on intrapancreatic digestive enzyme activation, by either sensitizing acinar cells to pathologic stimuli or stimulating the release of a secretagogue (cholecystokinin) from duodenal I cells. Recent advances in cell biologic and molecular techniques have permitted us to address the intracellular events involved in digestive enzyme activation in a manner that was previously considered impossible. Investigations that used these novel techniques found that (a) trypsin is, in contrast to its role in the small intestine, not necessarily involved in the premature intracellular activation of other digestive proteases such as proelastase; (b) trypsinogen does not autoactivate intracellularly but is instead largely activated by the lysosomal hydrolase cathepsin B; and (c) the role of trypsin in the intrapancreatic protease cascade is most likely one that involves the degradation, rather than the activation, of active digestive proteases including trypsin itself. These studies, as well as investigations that have addressed the role of mutant trypsin in the disease onset of hereditary pancreatitis, suggest that trypsin may not be critical for triggering pancreatitis but might have a protective role against the action of some of the other digestive proteases. While the specific role of different digestive enzymes in initiating pancreatitis is still a matter of debate and the topic of ongoing investigations, experimental evidence suggests that ethanol can directly interfere with the processes involved in digestive zymogen activation.

Acetaldehyde↗

PubMed2002

Presence of cathepsin B in the human pancreatic secretory pathway and its role in trypsinogen activation during hereditary pancreatitis.

The lysosomal cysteine protease cathepsin B is thought to play a central role in intrapancreatic trypsinogen activation and the onset of experimental pancreatitis. Recent in vitro studies have suggested that this mechanism might be of pathophysiological relevance in hereditary pancreatitis, a human inborn disorder associated with mutations in the cationic trypsinogen gene. In the present study evidence is presented that cathepsin B is abundantly present in the secretory compartment of the human exocrine pancreas, as judged by immunogold electron microscopy. Moreover, pro-cathepsin B and mature cathepsin B are both secreted together with trypsinogen and active trypsin into the pancreatic juice of patients with sporadic pancreatitis or hereditary pancreatitis. Finally, cathepsin B- catalyzed activation of recombinant human cationic trypsinogen with hereditary pancreatitis-associated mutations N29I, N29T, or R122H were characterized. In contrast to a previous report, cathepsin B-mediated activation of wild type and all three mutant trypsinogen forms was essentially identical under a wide range of experimental conditions. These observations confirm the presence of active cathepsin B in the human pancreatic secretory pathway and are consistent with the notion that cathepsin B-mediated trypsinogen activation might play a pathogenic role in human pancreatitis. On the other hand, the results clearly demonstrate that hereditary pancreatitis-associated mutations do not lead to increased or decreased trypsinogen activation by cathepsin B. Therefore, mutation-dependent alterations in cathepsin B-induced trypsinogen activation are not the cause of hereditary pancreatitis.

Blotting, Western↗

PubMed2001

Hereditary pancreatitis caused by a novel PRSS1 mutation (Arg-122 --> Cys) that alters autoactivation and autodegradation of cationic trypsinogen.

Hereditary pancreatitis has been found to be associated with germline mutations in the cationic trypsinogen (PRSS1) gene. Here we report a family with hereditary pancreatitis that carries a novel PRSS1 mutation (R122C). This mutation cannot be diagnosed with the conventional screening method using AflIII restriction enzyme digest. We therefore propose a new assay based on restriction enzyme digest with BstUI, a technique that permits detection of the novel R122C mutation in addition to the most common R122H mutation, and even in the presence of a recently reported neutral polymorphism that prevents its detection by the AflIII method. Recombinantly expressed R122C mutant human trypsinogen was found to undergo greatly reduced autoactivation and cathepsin B-induced activation, which is most likely caused by misfolding or disulfide mismatches of the mutant zymogen. The K(m) of R122C trypsin was found to be unchanged, but its k(cat) was reduced to 37% of the wild type. After correction for enterokinase activatable activity, and specifically in the absence of calcium, the R122C mutant was more resistant to autolysis than the wild type and autoactivated more rapidly at pH 8. Molecular modeling of the R122C mutant trypsin predicted an unimpaired active site but an altered stability of the calcium binding loop. This previously unknown trypsinogen mutation is associated with hereditary pancreatitis, requires a novel diagnostic screening method, and, for the first time, raises the question whether a gain or a loss of trypsin function participates in the onset of pancreatitis.

Amino Acid Sequence↗