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S Liebe

Publications and source records attributed to S Liebe.

At least 37 records · Page 2Linked to original sources
PubMed1999

Injection of encapsulated cells producing an ifosfamide-activating cytochrome P450 for targeted chemotherapy to pancreatic tumors.

The prognosis of pancreatic cancer is poor, and current medical treatment is mostly ineffective. The aim of this study was to design a new treatment modality in an animal model system. We describe here a novel treatment strategy employing a mouse model system for pancreatic carcinoma. Embryonal kidney epithelial cells were genetically modified to express the cytochrome P450 subenzyme 2B1 under the control of a cytomegalovirus (CMV) immediate early promoter. This CYP2B1 gene converts ifosfamide to its active cytotoxic compounds, phosphoramide mustard, which alkylates DNA, and acrolein, which alkylates proteins. The cells were then encapsulated in a cellulose sulphate formulation and implanted into preestablished tumors derived from a human pancreatic tumor cell line. Intraperitoneal administration of low-dose ifosfamide to tumor bearing mice that received the encapsulated cells results in partial or even complete tumor ablation. Such an in situ chemotherapy strategy utilizing genetically modified cells in an immunoprotected environment may prove useful for solid tumor therapy in man.

Animals↗
PubMed1999

[Intestinal lymphoma. A long diagnostic path].

CASE REPORT: We describe the case of a 43-year-old patient with a Burkitt lymphoma in the small intestine, who initially presented with abdominal discomfort, weight loss, constipation and neurological symptoms. DIAGNOSIS: In terms of differential diagnosis other inflammatory and tumorous diseases had to be considered. Non-Hodgkin lymphomas are common malignant afflictions of the GI-tract. The total body tumor burden is the principal determinant of prognosis. Serum lactate dehydrogenase (LDH) level is one parameter that reflects the tumor burden. On the other hand abdominal mass, bone marrow and central nervous system involvement are negative prognostic factors. Lymphomas can invade in the CNS at any time during the course of disease. This is generally associated with a poor prognosis if not treated immediately. TREATMENT: High doses of cyclophosphamid and MTX have been shown successful in the treatment of Burkitt lymphoma. Almost all relapses occur on therapy or shortly after termination of treatment. Therefore, criteria are needed to select patients of higher and lesser risk to protect the latter from the further intensification of therapy.

Adult↗
PubMed1999

Does bile of patients with acute gallstone pancreatitis cause pancreatic inflammatory lesions? A study of the pancreatic toxicity of choledochal secretions collected at ERCP.

BACKGROUND: Bile flow into the pancreatic duct has been proposed as the cause of acute biliary pancreatitis. However, the pancreatic toxicity of choledochal bile from patients with acute gallstone pancreatitis has not been studied. METHODS: Bile was collected endoscopically from the common bile ducts of 21 patients with acute gallstone pancreatitis within 72 hours after the onset of disease. The bile samples were instilled into the pancreatic duct of rabbits, and light microscopic examination of the pancreas morphology was performed to assess the toxicity of human bile. Microbiologic quantitative analysis of the aerobic and anaerobic bacterial bile flora was performed. RESULTS: Bile of six patients with acute gallstone pancreatitis (29%) induced interstitial inflammation in the rabbit pancreas. Choledochal bile of these patients harbored more than 10(4) CFU/mL bacteria (Proteus vulgaris, n = 1; Klebsiella pneumoniae, n = 1; Escherichia coli, n = 2; enterococci, n = 2). After sterilization, the bile samples did not induce acute pancreatitis. In 15 patients (71%), bile did not cause acute pancreatitis in the rabbit pancreas. These choledochal secretions were sterile or contained less than 10(4) CFU/mL. CONCLUSIONS: Reflux of infected bile may be a potential cause of acute pancreatitis in the minority of patients with bacterobilia. In most patients with gallstone pancreatitis, bile is neither infected nor harmful to the pancreas, and its flow into the gland is unlikely to be the cause of inflammation.

Acute Disease↗
PubMed1999

The anti-proliferative agent jasplakinolide rearranges the actin cytoskeleton of plant cells.

In the present study, we have characterized the action of the natural cyclodepsipeptide jasplakinolide (JAS) on the cytoplasmic architecture, actin-based cytoplasmic motility, and the organization of the actin cytoskeleton in selected examples of green algae (Acetabularia, Pseudobryopsis and Nitella) and higher plant cells (Allium bulb scale cells and Sinapis root hairs). JAS was capable of influencing the actin cytoskeleton and inhibiting cytoplasmic streaming in a differential, cell type-specific manner. With the exception of Nitella, two consecutive responses were observed upon incubation with 2.5 microM JAS: In the first phase cytoplasmic streaming increased transiently alongside with minor modifications of the actin cytoskeleton in the form of adventitious actin spots and spikes appearing throughout the cell cortex in addition to the normal actin bundle system typical for each cell type. In the second phase, cytoplasmic streaming stopped and the actin cytoskeleton became heavily reorganized into shorter, straight, more and more randomly oriented bundle segments. JAS exerted severe long-term effects on the actin cytoskeleton when treatments exceeded 30min at a concentration of 2.5 microM. An in situ competition assay using equimolar concentrations of JAS and FITC-phalloidin suggested that JAS has a phalloidin-like action. Effects of JAS were significantly different from those of cytochalasin D with respect to the resulting degree of perturbance of cytoplasmic organization, the distribution of actin filaments and the speed of reversibility.

Actins↗
PubMed1999

Molecular adsorbent recycling system (MARS): clinical results of a new membrane-based blood purification system for bioartificial liver support.

The use of xenogenic or genetically engineered cell types in bioartificial liver support systems requires separation methods between the patients' blood and the liver support bioreactors that guarantee the sufficient transfer of pathophysiologically relevant substances but prevent complications. The present paper describes a new membrane separation system that is nearly impermeable to proteins but enables the exchange of water soluble and protein bound toxins by a special membrane and a recycled protein containing dialysate. Because the full range of toxins in hepatic failure has still not been identified, the value of this membrane separation method was evaluated clinically. Thirteen patients suffering from life threatening hepatic failure who had not responded to state of the art therapy were treated with this device, the molecular adsorbent recycling system (MARS). The overall survival rate was 69%. All patients showed positive response to the therapy, indicating that the presented membrane separator combines therapeutic effectivity with the highest safety criteria for the patient by cutting the exchange of substances below the level of proteins.

Adsorption↗
PubMed1999

Simple method for DNA extraction from pancreatic juice for PCR amplification assays.

CONCLUSION: Preparation of DNA from pancreatic juice for subsequent polymerase chain reaction (PCR) is difficult, but manageable. The protocol presented offers a simple and fast solution. This method might be applicable to other complicated samples, such as saliva, would secretions, or stool washings. BACKGROUND: Of all the biological samples used for PCR amplification, pancreatic juice is the most problematic because of the presence of potential inhibitory substances and the amount of nucleases. This demands a DNA preparation procedure that is suitable for routine diagnostic PCR, and is therefore efficient and safe. This is particularly true for pancreatic juice obtained during routine endoscopy. METHODS: We describe here a simple method utilizing modified phenol/chloroform extraction and precipitation directly from native pancreatic juice suitable for diagnostic PCR applications, such as oncogenes. RESULTS: DNA could be prepared in quantitative amounts from routine endoscopic specimens. DNA could also be prepared from samples kept several days at room temperature.

DNA↗
PubMed1998

Intratumoral injection of encapsulated cells producing an oxazaphosphorine activating cytochrome P450 for targeted chemotherapy.

The prognosis of pancreatic adenocarcinoma is poor and current treatment is for the most part ineffective. We describe here a novel treatment strategy using a mouse model system for pancreatic cancer. Human embryonic epithelial cells have been genetically modified to express the cytochrome P450 2B1 enzyme under the control of a CMV immediate-early promoter. This CYP2B1 gene converts oxazaphosphorines (ifosfamide or cyclophosphamide) to their active cytotoxic compounds, phosphoramide mustard, which alkylates DNA, and acrolein, which alkylates proteins. A number of assays were performed to demonstrate the CYP2B1 gene function as well as toxic effects on neighbouring cells (bystander effect). The cells were then encapsulated in a cellulose sulphate formulation shown to be well tolerated in the pancreas of immunocompetent mice, and injected 1 cm away from pre-established tumours derived from a human pancreatic tumour cell line (PaCa-44). Intraperitoneal administration of low-dose ifosfamide to tumour bearing mice that received the encapsulated cells results in partial or even complete tumour ablation. Such an in situ chemotherapy strategy utilizing genetically modified cells in an immunoprotected environment may prove useful for solid tumour therapy in man.

Adenocarcinoma↗
PubMed1998

Targeted chemotherapy by intratumour injection of encapsulated cells engineered to produce CYP2B1, an ifosfamide activating cytochrome P450.

The prognosis of pancreatic adenocarcinoma is poor and current treatment ineffective. A novel treatment strategy is described here using a mouse model system for pancreatic cancer. Cells that have been genetically modified to express the cytochrome P450 2B1 enzyme are encapsulated in cellulose sulphate and implanted into pre-established tumours derived from human pancreatic cells. Cytochrome P450 2B1 converts the chemotherapeutic agent ifosfamide to toxic metabolites. Administration of ifosfamide to tumour-bearing mice that were recipients of implanted encapsulated cells results in partial or even complete tumour ablation. These results suggest that in situ chemotherapy with genetically modified cells in an immunoprotected environment may prove useful for application in man.

Adenocarcinoma↗
PubMed1998

Increasing the transfection efficacy and subsequent long-term culture of resting human pancreatic duct epithelial cells.

Preparation of pancreatic duct epithelial cells from adult organs is possible by limited digestion and outgrowth of cells. These primary cells are mitotically active for only a short period. Therefore transfection with SV40 large-T antigen is one method to obtain an immortalized cell clone. Because the transfection efficacy of primary cells with conventional vectors is comparatively low, our aim was to develop conditions with improved transfection rates. Best transfection rates (approximately 6% of the resting cells) were obtained by using the BES buffered saline (BBS) calcium phosphate (Ca-P) coprecipitation technique at low pH. By using these optimized transfection parameters, primary cultures of human pancreatic duct epithelial cells were successfully transfected with the plasmid pSV3neo, bearing the large- and small-T antigen of SV40. A G 418 resistant clone (E4) was maintained in culture for 14 months before reaching terminal crisis.

Animals↗
PubMed1998

Secretory immunoglobulin A in pancreatic juice and pancreatic tissue of patients with chronic pancreatitis.

BACKGROUND: The predominance of secretory IgA (S-IgA) in intestinal secretions compared with blood is well established, but concentrations of this protein in pancreatic juice and its origin, especially in chronic pancreatitis, are unknown. AIMS: To investigate the role of S-IgA in chronic pancreatitis. PATIENTS: Twenty one patients with chronic pancreatitis (group I), three patients with proven malignancies (group II), and 12 patients without pancreatic disease (group III). METHODS: Pure human pancreatic juice was collected endoscopically in four fractions after consecutive stimulation with secretin and cholecystokinin (CCK). Samples were analysed for S-IgA, protein, trypsinogen, and proteolytic activity. RESULTS: The S-IgA level was significant increased in fraction 1 of pancreatic juice of group I (1210 (1411) ng/ml) compared with controls (33 (70) ng/ml). Protein concentrations and trypsinogen content were lower in group I than in the other groups. Proteolytic activity could be observed in 53% of all 133 pancreatic juice samples, but in 87% of fraction 1. In pancreatic tissue of three patients with chronic pancreatitis both IgA and secretory component were detected by immunohistology. Expression of the secretory component by human pancreatic epithelial cells was increased in patients with chronic pancreatitis compared with normal controls. The concentration of S-IgA in pancreatic juice did not correlate with the serum S-IgA level. In contrast, serum levels of S-IgA were decreased in patients with chronic pancreatitis. CONCLUSION: There are high levels of S-IgA in human pancreatic juice following chronic inflammation and a protective role is suggested for this immunoglobulin.

Adult↗
PubMed1998

Faecal elastase 1: not helpful in diagnosing chronic pancreatitis associated with mild to moderate exocrine pancreatic insufficiency.

BACKGROUND/AIM: The suggestion that estimation of faecal elastase 1 is a valuable new tubeless pancreatic function test was evaluated by comparing it with faecal chymotrypsin estimation in patients categorised according to grades of exocrine pancreatic insufficiency (EPI) based on the gold standard tests, the secretin-pancreozymin test (SPT) and faecal fat analysis. METHODS: In 64 patients in whom EPI was suspected, the following tests were performed: SPT, faecal fat analysis, faecal chymotrypsin estimation, faecal elastase 1 estimation. EPI was graded according to the results of the SPT and faecal fat analysis as absent, mild, moderate, or severe. The upper limit of normal for faecal elastase 1 was taken as 200 micrograms/g, and for faecal chymotrypsin 3 U/g stool. Levels between 3 and 6 U/g stool for faecal chymotrypsin are usually considered to be suspicious for EPI. In this study, both 3 and 6 U/g stool were evaluated as the upper limit of normal. RESULTS: Exocrine pancreatic function was normal in 34 patients, of whom 94, 91, and 79% had normal faecal elastase 1 and faecal chymotrypsin levels (< 3 U/g and < 6 U/g) respectively. Thirty patients had EPI, of whom 53, 37, and 57% had abnormal faecal enzyme levels (differences not significant). When EPI was graded as mild, moderate, or severe, 63% of patients had mild to moderate EPI, and 37% had severe EPI. In the latter group, between 73 and 91% of patients had abnormal faecal enzymes. In the group with mild to moderate EPI, abnormal test results were obtained for both faecal enzymes in less than 50% of the patients (differences not significant). Some 40% of the patients had pancreatic calcifications. There were no significant differences for either faecal enzyme between the two groups with and without pancreatic calcifications. In 62% of the patients who underwent an endoscopic retrograde cholangiopancreatography (ERCP), abnormal duct changes were found. Again, there were no significant differences for either faecal enzyme between the two groups with abnormal and normal ERCP. CONCLUSION: Estimation of faecal elastase 1 is not distinctly superior to the traditional faecal chymotrypsin estimation. The former is particularly helpful only in detecting severe EPI, but not the mild to moderate form, which poses the more frequent and difficult clinical problem and does not correlate significantly with the severe morphological changes seen in chronic pancreatitis.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1998

Immunohistochemical characterization of the pancreatic cellular infiltrate in normal pancreas, chronic pancreatitis and pancreatic carcinoma.

BACKGROUND/AIMS: Chronic pancreatitis is histologically characterized by an extended fibrosis and infiltration of leukocytes. We intended to differentiate the infiltration to evaluate the inflammatory process. METHODS: Samples of tissues of normal pancreas (NP, n = 12), of chronic pancreatitis (CP, n = 7), and pancreatic tissues surrounding pancreatic carcinoma (CA, n = 7) were investigated by immunohistochemical staining using the APAAP technique. RESULTS: In normal pancreas, mononuclear cells (47.1 +/- 26.0 cells/mm2) were observed with a predominance of macrophages (56.3%) and T lymphocytes (31.3%) which were differentiated in CD8+ lymphocytes (9.3 +/- 7.2 cells/ mm2) and CD4+ lymphocytes (6.7 +/- 3.2 cells/mm2). Rarely, plasma cells (5.3%) and B lymphocytes (7.1%) could be detected. In pancreatic tissue of patients with CP and in CA there was a significant increase of mononuclear cells to 264.4 +/- 120.3 cells/mm2 and 284.3 +/- 67.8 cells/mm2, respectively. In both diseases percentages of T lymphocytes (CP: 50.5%; CA: 48.1%) were higher than in normal controls. CD4+/CD8+ ratio of 0.77 in CP and 0.82 in CA demonstrated a predominance of CD8+ cells compared to the peripheral blood. In NP and CA, nearly all T lymphocytes expressed CD45R0 identifying memory cells, while only 58% of T lymphocytes were CD45R0 positive in CP. CONCLUSION: Our data suggest that the investigated cases of CP were of a common inflammatory type rather than due to an autoimmunological reaction. CD8+ T lymphocytes were the predominant T cell subset in the inflammatory infiltrates in both CP and CA.

Adenocarcinoma↗