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Biomedical subjects

M Büchler

Publications and source records attributed to M Büchler.

At least 55 records · Page 3Linked to original sources
PubMed1996

cDNA cloning of the hepatocyte canalicular isoform of the multidrug resistance protein, cMrp, reveals a novel conjugate export pump deficient in hyperbilirubinemic mutant rats.

ATP-dependent transport of glutathione and glucuronate conjugates from hepatocytes into bile is mediated by a distinct member of the ATP-binding cassette superfamily. We have cloned and sequenced the canalicular isoform of the multidrug resistance protein from rat liver, and termed it cMrp. This membrane glycoprotein is composed of 1541 amino acids with an identity of 47.8% with the human multidrug resistance protein (MRP) and of 41.9% with the yeast cadmium factor (YCF1). The carboxyl-terminal 130 amino acids of the human hepatocyte canalicular isoform of MRP (cMRP) were 80.2% identical with rat cMrp. cMrp was not expressed in the liver of two mutant rat strains, the Eisai hyperbilirubinemic rat and the GY/TR- mutant, which are deficient in the ATP-dependent transport of conjugates across the canalicular membrane. Immunoblotting using an antibody raised against the carboxyl terminus of cMrp detected the glycoprotein of about 190 kDa only in the canalicular membrane from normal liver. Double immunofluorescence and confocal laser scanning microscopy localized cMrp exclusively to the canalicular membrane domain of hepatocytes and demonstrated its loss in the hyperbilirubinemic mutant rat. The results identify cMrp as a canalicular transport protein with a novel sequence and with a function similar to the one of the MRP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Serum phospholipase A2 in patients with multiple organ failure.

Multiple organ failure (MOF) is the most common cause of death in the surgical intensive care unit. We studied the relation of MOF to changes in the concentration of group II phospholipase A2 (PLA2) in serum. Altogether, 215 surgical intensive care patients with multiple injuries, diffuse peritonitis, or sepsis and control patients, who were at a high risk for postoperative sepsis after various surgical interventions, were included in the present prospective study. The clinical performance of the MOF score and the concentrations of group II PLA2 and C-reactive protein (CRP) in serum were studied using receiver operating characteristic (ROC) curves. The group II PLA2 level was considerably above normal in all groups of patients during the first week of observation. There was a highly significant difference in group II PLA2 levels between patients with severe infections (peritonitis and sepsis) and the other patients studied (multiple injuries and elective surgery) (ROC 0.931, P < 0.0001). The concentration of group II PLA2 had a significant positive correlation to the CRP level and body temperature, which indicates that group II PLA2 is an acute phase reactant and that the determination of group II PLA2 is a useful measurement to diagnose severe infections. It was concluded that the concentration of group II PLA2 in serum effectively predicts lethal MOF in patients with multiple injuries after the second day (ROC 0.739, P < 0.01) and in patients with diffuse peritonitis after the fourth day (ROC 0.750, P < 0.02).

Adolescent↗
PubMed1996

Importance of the duodenal passage and pouch volume after total gastrectomy and reconstruction with the Ulm pouch: prospective randomized clinical study.

The objective of this randomized study was to examine which reconstruction method and which pouch volume offer the best preconditions for a good quality of life and extensive physiologic regulation of gastrointestinal hormones after total gastrectomy. Up to now there is no general agreement with regard to the ideal reconstruction after total gastrectomy. The importance of the duodenal passage, the need for a pouch reconstruction, and the ideal pouch volume are matters of controversy. A total of 60 patients underwent the following reconstructions: Ulm pouch (pouch reconstruction with preservation of the duodenal passage), Hunt-Lawrence-Rodino pouch, or Roux-en-Y reconstruction without pouch. The clinical course, quality of life, and regulation of gastrointestinal hormones in correlation to reconstruction type and pouch volume were documented. Quality of life was assessed by means of a standardized specific questionnaire. Blood glucose, insulin, cholecystokinin, motilin, secretin, and pancreatic polypeptide were measured after stimulation by a standardized test meal. Six months after total gastrectomy those patients with an Ulm pouch were found to have a significantly better life quality (p < 0.01), higher body weight, and better physiologic regulation of gastrointestinal hormones; moreover, they developed (in contrast to all other reconstruction types) no pathologic glucose tolerance. Our conclusion is that all patients with a postoperative life expectancy of at least 6 months (i.e., tumor stages UICC I and II) should undergo pouch reconstruction with preservation of the duodenal passage.

Aged↗
PubMed1996

The function of the multidrug resistance proteins (MRP and cMRP) in drug conjugate transport and hepatobiliary excretion.

The MRP gene encodes a 190-kDa integral membrane glycoprotein which functions as a primary-active ATP-dependent export pump for amphiphilic anions. The MRP gene-encoded conjugate export pump and its canalicular isoform represent the transport activity which has been described earlier as multispecific organic anion transporter, non-bile acid organic anion transporter, glutathione S-conjugate export pump, or leukotriene export pump. Analyses of the substrate specificity of the human MRP pump were performed in plasma membrane vesicles from MRP-overexpressing drug-selected cells (7) and cells transfected with an MRP expression vector (8). Substrates for MRP include thioether-linked conjugates of lipophilic compounds with glutathione, cysteinyl glycine, cysteine, and N-acetyl cysteine, but also glutathione disulfide, and glucuronate conjugates such as etoposide glucuronide. This broad-specificity ATP-dependent export pump is not only overexpressed in several multidrug resistant tumor cells and tissues, but is also present in most normal cells and tissues. The expression of cMRP and MRP in human liver and of cMrp and its homolog Mrp in rat liver was demonstrated by reverse transcription PCR, cDNA sequencing, and immunoblotting (13). The important function of the cMRP gene-encoded broad-specificity conjugate export pump in hepatobiliary excretion is illustrated by the selective absence of this canalicular isoform from the hepatocyte canalicular membrane in transport-deficient mutant rats. This altered lack of cMrp is the basis for the hereditary detect of the hepatobiliary excretion of anionic conjugates in the mutant animals (13). The absence of this canalicular Mrp in the mutants is analogous to the defect in the human Dubin-Johnson syndrome which is characterized by an impaired excretion of conjugated anions across the canalicular membrane.

ATP-Binding Cassette Transporters↗
PubMed1996

Perioperative endotoxemia and bacterial translocation during major abdominal surgery: evidence for the protective effect of endogenous prostacyclin?

OBJECTIVE: To investigate the potential role of endogenous prostacyclin (PGI2) released after mesenteric traction during major abdominal surgery on perioperative endotoxemia and bacterial translocation. DESIGN: Prospective, randomized, double-blind clinical study. SETTING: Operating room and surgical intensive care unit in a university hospital. PATIENTS: Fifty consecutive patients scheduled for major abdominal surgery (pancreas resection, abdominal aortic surgery). INTERVENTIONS: Fifteen minutes before skin incision, either 400 mg of ibuprofen or a placebo equivalent were administered intravenously. Immediately after peritoneal incision, eventration and action of the small bowel was intentionally performed in a uniform fashion. MEASUREMENTS AND MAIN RESULTS: Baseline values were obtained before induction of anesthesia. Additional measurements, along with assessments of hemodynamics and gas exchange, were performed before incision of the peritoneum and at 5, 30, and 45 mins and 3, 6, and 24 hrs after mesenteric traction. Arterial plasma concentrations of 6-keto-prostaglandin F1 alpha and thromboxane B2 (stable metabolites of PGI2 and thromboxane A2) were determined by radioimmunoassay. Endotoxin was measured by limulus amebocyte lysate test. Mesenteric lymph nodes were sampled in 31 patients (ibuprofen n = 14, placebo n = 17) and sent for culture under sterile conditions. Transient hypotension and a marked increase of plasma 6-keto-prostaglandin F1 alpha concentrations occurred up to 6 hrs after mesenteric traction in untreated patients with median peak concentrations (2243 vs. 72 ng/L [p < .0001, placebo vs. ibuprofen], observed 5 mins after mesenteric traction). Endotoxemia occurred in both study groups. However, after mesenteric traction, plasma endotoxin concentrations were significantly higher in the ibuprofen group. Median peak concentrations (0.12 vs. 0.27 EU/mL [p < .001, placebo vs. ibuprofen]) were observed 3 hrs after mesenteric traction. Gram-negative bacteria in mesenteric lymph nodes were detected exclusively in the ibuprofen group (n = 5, p < .01). CONCLUSIONS: In ibuprofen-pretreated patients, significantly higher endotoxin concentrations as well as bacterial translocation to mesenteric lymph nodes occurred, despite the absence of a transient decrease in mean arterial pressure that had been associated with PGI2 release. Therefore, we hypothesized that during major abdominal surgery, endogenous PGI2 released in response to mesenteric traction may play a crucial role in maintaining splanchnic microcirculation and thus preserving gut mucosal barrier function.

APACHE↗
PubMed1996

Single-strand conformation polymorphism analysis of the epidermal growth factor receptor at codon 497.

A variant human epidermal growth factor (EGF) receptor (HER) with a transition (G to A) at codon 497, resulting in a substitution of a lysine for an arginine, was recently demonstrated in several human pancreatic cancer cell lines. In the present study, we compared the frequency of expression of wild-type (HER497R) and variant (HER497K) EGF receptors in normal and malignant pancreatic tissue samples using single-strand conformation polymorphism analysis. Both receptors were expressed in normal (42%) and malignant (46%) tissues. Three samples (two normal and one cancer) expressed only HER497K. The cancer sample that was homozygous for HER497K exhibited strong EGF receptor immunoreactivity. The high frequency of HER497K expression suggests that it is due to a relatively common polymorphism in the HER coding region. Its presence in some of the cancer samples suggests that, like the wild-type receptor, HER497K also has a role in pancreatic cancer.

Base Sequence↗
PubMed1995

Expression and in-situ localization of genes coding for extracellular matrix proteins and extracellular matrix degrading proteases in pancreatic cancer.

Pancreatic cancer shows a strong desmoplastic reaction characterized by a remarkable proliferation of interstitial connective tissue (collagens type I and III, fibronectin). In this study we have analyzed the balance of expression of mRNAs encoding extracellular matrix components (collagens I, III and IV, laminin, fibronectin), extracellular matrix-degrading metalloproteinases (MMP-1, -2, -3 and -9) and tissue inhibitors of metalloproteinases (TIMP-1 and -2) in pancreatic cancer and control pancreatic tissue by Northern-blot analysis and mRNA in situ hybridization. Transcripts for MMP-1 (interstitial collagenase) and MMP-3 (stromelysin-1) were not detectable in pancreatic cancer and control tissues. Steady-state levels of transcripts encoding extracellular matrix proteins, MMP-2 (72-kDa collagenase IV), MMP-9 (92-kDa collagenase type IV), TIMP-1 and TIMP-2 were elevated in the majority of pancreatic-cancer tissue samples as compared to control pancreatic tissue. A good correlation was seen between overexpression of these MMPs and TIMPs and the steady-state levels of transcripts coding for extracellular matrix proteins, the amount of collagen protein and the severity of the desmoplastic reaction. In situ hybridization studies localized transcripts coding for collagens type I and III to spindle-shaped stromal cells, whereas transcripts for MMP-2, MMP-9, TIMP-1 and TIMP-2 were found in both stromal and tumor cells. However, MMP-2 transcripts appeared to be more abundant in stromal cells, TIMP-1 and TIMP-2 transcripts were evenly distributed over tumor and stromal cells and relatively more MMP-9 transcripts were found in tumor cells. We conclude that, in human pancreatic cancer, MMP-2, MMP-9, TIMP-1 and TIMP-2 may be involved in processes leading to the strong desmoplastic reaction observed in these tumors. Both stromal and tumor cells appear to be the source of MMPs and TIMPs in human pancreatic cancer.

Blotting, Northern↗
PubMed1995

Cellular and subcellular localization of transforming growth factor-alpha and epidermal growth factor receptor in normal and diseased human and hamster pancreas.

Four normal pancreas, 8 chronic pancreatitis specimens, and 30 non-endocrine pancreatic tumors from humans and 6 normal and 6 induced pancreatic cancers in hamsters were examined immunohistochemically by antibodies against human transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFR). Two normal pancreas and two pancreatic cancer specimens from each species were also studied immunoelectron microscopically by the immunogold method. In chronic pancreatitis, the reactivity and intensity of the staining with both antibodies were much greater in ductal/ductular cells than in the normal pancreas. All 30 pancreatic cancers reacted with both antibodies with a variable degree of reactivity and staining intensity. No correlation was found between the histological type of tumors, the degree of tumor differentiation, and the incidence and patterns of reactivity of either antibody. Immunoelectron microscopically, both EGFR and TGF-alpha were demonstrated primarily on the basal membrane. In the normal hamster pancreas, TGF-alpha was overexpressed in the alpha-cells but not in any other islet cells. Both TGF-alpha and EGFR were marginally detectable in the exocrine pancreas and in induced pancreatic lesions. This is the first demonstration of subcellular localization of TGF-alpha and EGFR in the normal and diseased human and hamster pancreas.

Adult↗
PubMed1995

Changes of protein gene product 9.5 (PGP 9.5) immunoreactive nerves in inflamed appendix.

The existence of chronic appendicitis is controversial. In this prospective study, we investigated possible changes in the innervation of the appendix under different pathological conditions and correlated histological findings with clinical observation. Thirty appendectomy specimens and 14 appendices obtained from organ donors or patients who underwent right hemicolectomy were immediately fixed in Bouin's solution and processed for immunocytochemistry using an antiserum directed against the panneuronal marker protein gene product 9.5 (PGP 9.5). The density of PGP 9.5 immunostaining was evaluated by digitized morphometry. Significant differences in the density of the PGP 9.5-immunoreactive area were detected in the mucosal layer. In the nonacute appendicitis group, PGP 9.5 was increased (10.99 +/- 3.15%) as compared to acute appendicitis (3.89 +/- 1.77%) and controls (4.98 +/- 1.25%). The significant increase of PGP 9.5 in nonacute appendicitis may suggest axonal sprouting leading to hyperinnervation of the mucosa. This may be a neuronal factor in the pathophysiology of the disease and pain symptoms.

Abdominal Pain↗
PubMed1995

Interdigestive cycling in chronic pancreatitis: altered coordination among pancreatic secretion, motility, and hormones.

BACKGROUND & AIMS: Secretions from the exocrine and endocrine pancreas may modulate interdigestive motility. To test this hypothesis in humans, we investigated interdigestive cycling in patients with chronic pancreatitis (CP) as a model of impaired pancreatic function. METHODS: Antroduodenal motility, pancreatic enzyme output, and pancreatic polypeptide release were monitored for two consecutive interdigestive cycles in 13 controls and 9 patients with CP. RESULTS: Interdigestive enzyme output was severely impaired in patients with CP (> 80% decrease); however, secretory cycling was still evident in most patients. All parameters describing interdigestive motility were similar in controls and patients with CP (duration of the migrating motor complex [MMC] was 107 +/- 19 minutes in patients with CP vs. 114 +/- 15 minutes in controls). The time between cyclic peaks of enzyme secretion (76 +/- 4 minutes vs. 101 +/- 4 minutes in controls) and pancreatic polypeptide (63 +/- 4 minutes vs. 106 +/- 7 minutes in controls) was shortened in patients with CP, and peaks were no longer temporally related to the MMC. Only 56% of phase III activity fronts were associated with a concomitant secretory peak in patients with CP compared with 92% in healthy subjects. CONCLUSIONS: CP not only decreases pancreatic secretion but interrupts the coordination among interdigestive cyclic phenomena. Our findings in several animal and human models refute the concept that pancreatic mechanisms exert a major regulatory influence on interdigestive motor activity.

Adult↗
PubMed1995

Expression of the MRP gene-encoded conjugate export pump in liver and its selective absence from the canalicular membrane in transport-deficient mutant hepatocytes.

We have previously shown that the multi-drug resistance protein (MRP) mediates the ATP-dependent membrane transport of glutathione S-conjugates and additional amphiphilic organic anions. In the present study we demonstrate the expression of MRP in hepatocytes where it functions in hepatobiliary excretion. Analysis by reverse transcription-PCR of human and normal rat liver mRNA resulted in two expected cDNA fragments of MRP. Four different antibodies against MRP reacted on immunoblots with the glycoprotein of about 190 kD from human canalicular as well as basolateral hepatocyte membrane preparations. A polyclonal antibody directed against the carboxy-terminal sequence of MRP detected the rat homolog of MRP in liver. Double immunofluorescence microscopy and confocal laser scanning microscopy showed the presence of human MRP and rat Mrp in the canalicular as well as in the lateral membrane domains of hepatocytes. The transport function of the mrp gene-encoded conjugate export pump was assayed in plasma membrane vesicles with leukotriene C4 as a high-affinity glutathione S-conjugate substrate. The deficient ATP-dependent conjugate transport in canalicular membranes from TR- mutant rat hepatocytes was associated with a lack of amplification of one of the mrp cDNA fragments and with a selective loss of Mrp on immunoblots of canalicular membranes. Double immunofluorescence microscopy of livers from transport-deficient TR- mutant rats localized Mrp only to the lateral but not to the canalicular membrane. Our results indicate that the absence of Mrp or an isoform of Mrp from the canalicular membrane is the basis for the hereditary defect of the hepatobiliary excretion of anionic conjugates by the transport-deficient hepatocyte.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Effect of pancreatic ductal and parenchymal changes on exocrine function in chronic pancreatitis.

The effect of pancreatic ductal and parenchymal changes on exocrine pancreatic function was analyzed prospectively in 75 patients with chronic pancreatitis (CP). Endoscopic retrograde pancreatography (ERP), computed tomography (CT), and serum pancreolauryl test (PLT) were performed to evaluate the degree of ductal, parenchymal, and functional changes, respectively. Results were evaluated by stepwise multivariate logistic regression and are expressed as the odds ratio (OR). A strong association was found between the degree of ductal changes in ERP and the degree of exocrine functional impairment (OR = 5.8). However, the association between the degree of parenchymal changes in CT and the degree of pancreatic dysfunction was weaker and was clearly confounded by the degree of ductal changes. On the basis of these findings, we suggest that the development of exocrine pancreatic functional impairment in patients with CP depends primarily on the degree of ductal changes, while parenchymal abnormalities play a less important role.

Adult↗
PubMed1995

Lipid peroxidation and glutathione metabolism in chronic pancreatitis.

In experimental models of pancreatitis lipid peroxidation products are increased possibly because of an enhanced generation of oxygen radicals. The purpose of this study was to determine whether lipid peroxidation products are increased in pancreatic tissue and serum of patients suffering from chronic or acute pancreatitis. In 20 patients undergoing operative treatment for chronic (n = 11) and acute pancreatitis (n = 9) the levels of malondialdehyde, conjugated dienes, and reduced and oxidized glutathione were determined in resected tissue samples. The excised tissue was examined and evaluated by light microscopy. Shortly before operation the serum concentrations of malondialdehyde, alpha-amylase, and lipase were measured. Pancreatic tissue from eight organ donors who had no abdominal trauma or pancreatic disease served as control. In chronic pancreatitis, conjugated dienes as well as malondialdehyde concentrations in the tissue were significantly elevated. Reduced glutathione was significantly decreased, suggesting glutathione depletion due to oxidative stress. In acute pancreatitis only the tissue and serum malondialdehyde levels were significantly high, whereas conjugated dienes remained within the normal range. Serum malondialdehyde levels correlated significantly with tissue concentrations (r = 0.76; p < 0.05) but not with the clinical course or the enzyme levels. In chronic pancreatitis, the increased tissue levels of lipid peroxidation products and the changes in glutathione metabolism suggest ongoing peroxidation of lipids due to an enhanced generation of oxygen radicals. In hemorrhagic necrotizing pancreatitis, however, oxygen radical-induced lipid peroxidation cannot be proven. Apparently, other pathomechanisms are involved in the development of the severe tissue damage.

Acute Disease↗
PubMed1995

Treatment of pain in chronic pancreatitis by inhibition of pancreatic secretion with octreotide.

It has been suggested that pancreatic ductal hypertension, secondary to pancreatic outflow obstruction, is a cause of pain in chronic pancreatitis. This study investigated the effect of inhibiting pancreatic secretion with octreotide in chronic pancreatitis pain. Ten patients with chronic alcoholic pancreatitis and severe daily pain were included in an intraindividual double blind crossover study. All patients received octreotide (3 x 100 micrograms/day subcutaneously) and placebo (3 x 0.9% saline solution subcutaneously) for three days at random. Between both treatment phases a two day washout period was interposed. Intensity of pain (visual analogue scale) and analgesic consumption were carefully registered. Pancreatic secretion was monitored daily by measuring faecal chymotrypsin concentration. It was found that during the administration of octreotide, pancreatic secretion was strongly inhibited (faecal chymotrypsin mean (SD) 1.7 (0.6) U/g) with respect to placebo (9.6 (4.2) U/g) and washout (7.6 (3.1) U/g) periods (p < 0.001). Pain score (29.6 (4.5) v 28.7 (5.8)) and consumption of analgesics were no different during the octreotide and placebo periods. It is concluded that short term inhibition of pancreatic secretion does not result in pain relief in patients with chronic pancreatitis. This finding is in contrast with the hypothesis that outflow obstruction of pancreatic secretion with consequent ductal hypertension is an important cause of severe persistent pain in chronic pancreatitis.

Adult↗
PubMed1995

Exocrine pancreatic function in the early phase of human acute pancreatitis.

BACKGROUND: Little is known about exocrine pancreatic function during human acute pancreatitis. We aimed to evaluate interdigestive exocrine pancreatic secretion and pancreatic polypeptide (PP) release during the early phase of acute pancreatitis in humans. METHODS: Eight patients with acute pancreatitis (six biliary, one alcoholic, and one idiopathic acute pancreatitis) were studied within 72 h from the onset of symptoms. Four patients had necrotizing and four had edematous acute pancreatitis. Normal values were obtained from 26 normal subjects matched by sex and age. Interdigestive pancreatic secretion was studied by a duodenal intubation perfusion technique. Enzyme output was calculated for consecutive 15-min periods over 3-4 h and expressed as units per hour within a secretion cycle and units per hour around a secretion peak. Plasma PP concentrations were measured by radioimmunoassay in 15-min intervals. RESULTS: All variables studied were similar in patients with acute pancreatitis and in controls. PP release in acute pancreatitis was maintained in a normal cyclical pattern closely related to the secretory cycles. CONCLUSIONS: Interdigestive exocrine pancreatic secretion in the early phase of mild to moderate acute pancreatitis in humans remains within the normal range. This finding provides a rational basis for early therapeutic inhibition of pancreatic secretion in human acute pancreatitis.

Acute Disease↗
PubMed1995

[Change in the surgical strategy in acute and complicated colonic diverticulitis].

The records of 312 patients with acute colonic diverticulitis were reviewed. 129 patients required an operation. The operative management is presented and compared to the international literature. One-stage resection was performed in 79% of all patients. In 84% of patients with a localized inflammation a one-stage resection was possible. Fifty-seven percent of patients with peritonitis due to colonic perforation required a multiple stage procedure. In 70% the preferred surgical procedure of multiple stage treatment was Hartmann's operation. These therapeutical regimens are current standard. Lethality was 1.6% for all 129 patients and the postoperative morbidity was 22%.

Acute Disease↗