Michael Gregor

University of Tuebingen, Tübingen, Baden-Wuerttemberg, Germany

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Publications (241)1349.66 Total impact

  • Zeitschrift für Gastroenterologie 10/2012; 49(10). DOI:10.1055/s-0031-1304774 · 1.67 Impact Factor
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    ABSTRACT: "Quorum sensing" (QS) is the phenomenon which allows single bacterial cells to measure the concentration of bacterial signal molecules. Two principle different QS systems are known, the Autoinducer 1 system (AI-1) for the intraspecies communication using different Acyl-homoserine lactones (AHL) and AI-2 for the interspecies communication. Aim of this study was to investigate QS of Escherichia coli Nissle 1917 (Mutaflor). While E. coli Nissle is producing AI-2 in a density dependent manner, no AI-1 was produced. To study the effect of AI-2 in the DSS (dextran sulphate sodium) induced mouse model of acute colitis, we silenced the corresponding gene luxS by intron insertion. The mutant bacterium E. coli Nissle::luxS was equally effective in colonizing the colon and the mutation turned out to be 100% stable during the course of the experiment. Isolating RNA from the colon mucosa and performing semiquantitative RT PCR, we were able to show that the expression of the pro-inflammatory cytokine IFN-y was suppressed in mice being infected with the E. coli Nissle wild type. Mice infected with the E. coli Nissle::luxS mutant showed a suppressed expression of IL-10 compared to uninfected mice, while the expression of the pro-inflammatory cytokines IL-6 and TNF-α was higher in these mice. The expression of mBD-1 was suppressed in mice being infected with the mutant in comparison to the mice not infected or infected with the wild type. No differences were seen in the histological examination of the colon sections in the different groups of mice. E. coli Nissle is producing AI-2 molecules, which are influencing the expression of cytokines in the mucosa of the colon in the DSS mice. However, if QS has a direct influence on the probiotic properties of E. coli Nissle remains to be elucidated.
    Gut Pathogens 08/2012; 4(1):8. DOI:10.1186/1757-4749-4-8 · 2.07 Impact Factor
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    ABSTRACT: For experimental studies investigating modalities and efficacy of transarterial chemoembolization (TACE) in hepatocellular carcinoma (HCC) an animal model resembling the human situation as closely as possible would be appropriate. Specifically, reproducible tumor growth characteristics with the capability for appropriate in vivo imaging to monitor treatment efficacy are required. Morris hepatoma 3924A was implanted into the liver of 30 ACI rats. Tumor growth was followed by angiography (n = 10), ultrasound (US, n = 30), native computed tomography (CT, n = 16), and native magnetic resonance imaging (MRI, n = 30) between day 8 and day 36 after implantation. The radiological morphological characteristics were compared with the macroscopic and microscopic histological findings of the explanted tumors. In all 30 animals a solitary liver tumor was found and macroscopically no signs of metastases, ascites, or peritoneal tumor were visible. On histopathological examination tumor sizes ranged between 27 +/- 3 mm(3) (day 8) and 3468 +/- 79 mm(3) (day 36). The first signs of tumor necrosis occurred at day 16. US allowed tumor visualization from day 8, MRI from day 8, angiography from day 10, and CT from day 14. The tumor model has the potential to be used for the visualization of tumor growth by MRI and US. The potential for monitoring therapeutic effects of TACE needs to be investigated.
    CardioVascular and Interventional Radiology 04/2012; 23(3):211-7. DOI:10.1007/s002700010045 · 1.97 Impact Factor
  • Zeitschrift für Gastroenterologie 08/2011; 49(08). DOI:10.1055/s-0031-1285398 · 1.67 Impact Factor
  • Zeitschrift für Gastroenterologie 08/2011; 49(08). DOI:10.1055/s-0031-1285160 · 1.67 Impact Factor
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    ABSTRACT: Parenteral nutrition is life-saving for patients with severe intestinal failure. Line-related blood stream infection is the most frequent complication and strategies have been developed to sterilize central lines. Nevertheless, failures of attempted sterilization are not well understood. 19 ports were explanted from 19 patients receiving parenteral nutrition because of port-related blood stream infection and failed sterilization, defined as a) recurrence of the same organism after a recent sterilization attempt <90 days), b) recovery of the causative organism after 10 days of proper antibiotic therapy or c) insufficient clinical improvement. Port chambers were opened and swabs were examined by culture. Pathogens resembled those typically found in successfully treated line-related blood stream infection. Despite proper therapy for a median of 6.5 days the same pathogen was recovered from 18/19 chambers. In 9/19 chambers visible debris were found, from which the pathogen could be cultured. Infected debris or infected biofilms in the chamber are the reason for failure to sterilize a port. Lock techniques, single lumen tunneled catheters or in certain settings the exchange of only the port chamber may be approaches to prevent, circumvent or treat failures of attempted sterilization of an infected port system.
    Zeitschrift für Gastroenterologie 03/2011; 49(3):335-9. DOI:10.1055/s-0029-1245980 · 1.41 Impact Factor
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    ABSTRACT: A 50-year-old patient with alcoholic liver cirrhosis was admitted due to hematemesis and melaena. Endoscopy showed esophageal variceal hemorrhage. A dose of erythromycin was administered before endoscopy for optimal endoscopic view. After conservative treatment with hemopressin, ciprofloxacin, and substitution with blood and fresh frozen plasma, the patient had an episode of atrial fibrillation with rapid ventricular response. The episode was terminated by intravenous administration of amiodarone, with subsequent conversion to sinus rhythm. Later on, the patient suffered from torsades de pointes tachycardia. Secondary torsades de pointes tachycardias have a low incidence, but often fatal outcome. Torsades de pointes tachycardias mostly are the result of administration of QT-active drugs, and other cofactors. Emergency treatment addresses the reestablishment, and stabilization of sinus rhythm. Preferably, drug-induced torsades de pointes tachycardias are prevented by permanent critical review of administered drugs with respect to indications, interactions, and adverse reactions.
    DMW - Deutsche Medizinische Wochenschrift 02/2011; 136(5):217. DOI:10.1055/s-0030-1247621 · 0.65 Impact Factor
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    ABSTRACT: The cytokine tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) has shown promising anticancer activity in early clinical settings by selectively inducing apoptosis in different tumour types. However, some tumour entities such as hepatocellular carcinoma (HCC) display an inherent resistance to TRAIL. A huge effort has been made to unravel strategies for a clinically applicable sensitisation of resistant cancer cells to TRAIL. Reversible epigenetic alterations such as DNA methylation play a major role in development, maintenance and resistance phenomena of tumour cells. Currently, several clinical trials are exploiting the potential of epigenetic drugs, such as 5-azacytidine (5-aza-CR) or 5-aza-2'-deoxycytidine (5-aza-dC) to break primary or secondary resistance phenomena of cancer cells. Therefore, 5-aza-CR and 5-aza-dC were investigated in the context of TRAIL resistance. Alterations in proliferation, apoptosis, regulatory proteins and toxicity were investigated in TRAIL-resistant hepatoma, and also in renal, colon and pancreatic cancer cells as well as non-transformed human-derived primary hepatocytes, tissue slices isolated from human liver and non-malignant colon cells, all of which had been exposed to demethylating drugs and/or TRAIL. Within hours, 5-aza-CR but not 5-aza-dC sensitised in vitro cultured tumour cells to TRAIL, first by activating caspases, followed by a subsequent induction of apoptosis. This surprisingly rapid sensitisation was confirmed in vivo employing a chorioallantoic membrane assay. As a major mechanism, a 5-aza-CR-induced inhibition of cellular protein synthesis was found which led to a breakdown of tumour-protecting factors such as the antiapoptotic factor FLICE inhibitory protein (FLIP). Importantly, TRAIL and 5-aza-CR did not induce relevant toxicity or apoptosis in primary hepatocytes, liver slices from different human donors and in normal colon cells. Molecular evidence is provided for a novel 5-aza-CR-based translational approach enabling a twofold treatment of apoptosis-resistant tumour entities, not only by an epigenetic reversion of the malignancy-associated phenotype but also by an efficient resensitization to apoptosis-inducing substances such as TRAIL.
    Gut 02/2011; 60(2):156-65. DOI:10.1136/gut.2010.208041 · 13.32 Impact Factor
  • Gastroenterology 01/2011; 140(5). DOI:10.1016/S0016-5085(11)62743-1 · 12.82 Impact Factor
  • C P Berg, M Gregor, U M Lauer
    DMW - Deutsche Medizinische Wochenschrift 12/2010; 135(49):2459-60. DOI:10.1055/s-0030-1269417 · 0.65 Impact Factor
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    ABSTRACT: The Cl/HCO(3) exchanger downregulated in adenoma (DRA) mediates electroneutral NaCl absorption in the intestine together with the apical Na/H exchanger NHE3. Lipid rafts (LR) modulate transport activity and are involved in phosphatidylinositol 3-kinase (PI3-kinase)-dependent trafficking of NHE3. Although DRA and NHE3 interact via PDZ adaptor proteins of the NHERF family, the role of LR and PDZ proteins in the regulation of DRA is unknown. We examined the association of DRA with LR using the nonionic detergent Triton X-100. DRA cofractionated with LR independently of its PDZ binding motif. Furthermore, DRA interacts with PDZK1, E3KARP, and IKEPP in LR, although their localization within lipid rafts is independent of DRA. Disruption of LR integrity resulted in the disappearance of DRA from LR, in a decrease of its surface expression and in a reduction of its activity. In HEK cells the inhibition of DRA by LR disruption was entirely dependent on the presence of the PDZ interaction motif. In addition, in Caco-2/BBE cells the inhibition by LR disruption was more pronounced in wild-type DRA than in mutated DRA (DRA-ETKFminus; lacking the PDZ binding motif)-expressing cells. Inhibition of PI3-kinase decreased the activity and the cell surface expression of wild-type DRA but not of DRA-ETKFminus; the partitioning into LR was unaffected. Furthermore, simultaneous inhibition of PI3-kinase and disruption of LR did not further decrease DRA activity and cell surface expression compared with LR disruption only. These results suggest that the activity of DRA depends on its LR association, on its PDZ interaction, and on PI3-kinase activity.
    AJP Gastrointestinal and Liver Physiology 10/2010; 299(4):G907-20. DOI:10.1152/ajpgi.00191.2010 · 3.65 Impact Factor
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    ABSTRACT: The aim of this study was to compare tumor changes in patients with hepatocellular carcinoma receiving sorafenib using evaluation criteria of the American Association for the Study of Liver Diseases (AASLD) and the European Association for the Study of the Liver (EASL) as opposed to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Twenty-five patients with inoperable hepatocellular carcinoma receiving oral sorafenib underwent magnetic resonance imaging at baseline and follow-up every 8 weeks (range, 2-19 weeks; mean, 7.6 weeks). Data were evaluated retrospectively. Survey time until progression ranged from 5 to 102 weeks (mean, 25.6 weeks), with a total of 54 target lesions being monitored. Additionally, evaluation of serum α-fetoprotein was performed at follow-up. The best response at follow-up using RECIST resulted in rates of 4% objective response (complete remission or partial remission), 24% (progressive disease), and 72% (stable disease). In contrast, AASLD and EASL criteria identified objective responses in 28% and 48%. Twenty percent of all patients classified as having progressive disease by RECIST were identified as having "pseudo"-progression due to extensive necrosis. Eleven percent of patients classified as having stable disease by RECIST were disclosed as essentially progressive. AASLD area and AASLD diameter disclosed 36% and 40% of patients as having partial remission, respectively, whereas EASL criteria discovered only 24%. There was no significant correlation between serum α-fetoprotein progression and AASLD, EASL, or RECIST evaluation criteria. Response monitoring via functional criteria such as AASLD or EASL criteria is likely to more accurately reflect vital tumor burden in hepatocellular carcinoma compared to RECIST.
    Academic radiology 10/2010; 18(1):89-96. DOI:10.1016/j.acra.2010.08.008 · 2.09 Impact Factor
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    ABSTRACT: Autoantibodies to the human muscarinic acetylcholine receptor of the M3 type (hmAchR M3) have been suggested to play an etiopathogenic role in Sjögren's syndrome. Primary biliary cirrhosis (PBC) often is associated with this syndrome. Therefore, we studied the co-presence of hmAchR M3 autoantibodies in patients with PBC. Frequency of hmAchR M3 autoantibodies was assessed by Western blotting analysis as well as by an ELISA using a 25-mer peptide of the 2nd extracellular loop of hmAchR M3. Co-localization of hmAchR M3/PBC-specific autoantibodies was studied by confocal laser scanning microscopy. Finally, sera from patients with PBC as well as from healthy controls were tested. Western blotting analysis as well as results from ELISA testing revealed a significantly enhanced IgG reactivity in PBC patients in contrast to healthy controls. Co-localization of autoantibodies with the hmAchR M3 receptor-specific autoantibodies was observed in 10 out of 12 PBC-patients but none of the 5 healthy controls. Antibodies of the IgM type were not found to be affected. For the first time, our data demonstrate the presence of autoantibodies to the hmAchR M3 in PBC patients. These findings might contribute to the understanding of the pathogenesis of this disease. Further studies have to focus on the functionality of hmAchR M3 autoantibodies in PBC patients.
    BMC Gastroenterology 10/2010; 10:120. DOI:10.1186/1471-230X-10-120 · 2.11 Impact Factor
    This article is viewable in ResearchGate's enriched format
  • Zeitschrift für Gastroenterologie 08/2010; 48(08). DOI:10.1055/s-0030-1263697 · 1.67 Impact Factor
  • Zeitschrift für Gastroenterologie 08/2010; 48(08). DOI:10.1055/s-0030-1263656 · 1.67 Impact Factor
  • Zeitschrift für Gastroenterologie 08/2010; 48(08). DOI:10.1055/s-0030-1263771 · 1.67 Impact Factor
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    ABSTRACT: To compare anxiety and depression levels in adult patients with celiac disease (CD) on a gluten-free diet (GFD) with controls. The levels of anxiety, depression and of a probable anxiety or depressive disorder were assessed by the Hospital Anxiety and Depression Scale in 441 adult patients with CD recruited by the German Celiac Society, in 235 age- and sex-matched patients with inflammatory bowel disease (IBD) in remission or with slight disease activity, and in 441 adult persons of a representative German general population sample (GP). Potential demographic (age, sex, social class, family status) and disease-related (latency to diagnosis, duration of GFD, compliance with GFD, thyroid disease) predictors of anxiety and depression in CD were tested for by regression analyses. The level of anxiety in CD patients was predicted (R(2) = 0.07) by female gender (P = 0.01). Female sex (OR = 3.6, 95% CI: 1.3-9.4, P = 0.01) was associated with a probable anxiety disorder. Living alone (OR = 0.5, 95% CI: 0.2-0.9, P = 0.05) was associated with a reduced risk of an anxiety disorder. The level of depression and a probable depressive disorder were not predicted by any of the demographic and medical variables tested for. The levels of anxiety in patients with CD (6.6 +/- 3.4) and with IBD (6.9 +/- 3.7) were higher than those of persons in the GP (4.6 +/- 3.3) (both P < 0.001). The levels of depression in persons with CD (4.2 +/- 3.4), IBD (4.6 +/- 3.4) and of the GP (4.2 +/- 3.8) did not differ (P = 0.3). The prevalence of a probable anxiety disorder in persons with CD (16.8%) and IBD (14.0%) was higher than that of the GP (5.7%) (P < 0.001). The prevalence of a probable depressive disorder did not differ significantly between the three groups (P = 0.1). Anxiety in adult German female celiacs on a GFD is higher than in persons of the GP. Female celiacs on a GFD should be screened for anxiety.
    World Journal of Gastroenterology 06/2010; 16(22):2780-7. · 2.43 Impact Factor
  • Gastroenterology 05/2010; 138(5). DOI:10.1016/S0016-5085(10)60215-6 · 12.82 Impact Factor
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    ABSTRACT: A young, previously healthy and immunocompetent patient was transferred to our hospital to recover a suspected Ascaris worm from his gall bladder. Although the diagnosis of Ascaris infection could not be confirmed, the patient suffered from cholecystitis. To our surprise, the respiratory situation of the patient deteriorated within 24 h under antibiotic therapy and he had to be transferred to the intensive care unit for mechanical respiration. Human cytomegalovirus (HCMV) was isolated directly from a bronchoalveolar lavage (BAL) sample, and Mycoplasma pneumoniae DNA was detected by PCR in an enrichment culture of the same BAL sample. Serology for HCMV and M. pneumoniae clearly supported a primary/post-primary infection for both agents (IgM detection, increase of IgG titres and, in the case of HCMV, a low avidity index of only 22 %). Therefore, we assumed that a rare HCMV and M. pneumoniae coinfection was the aetiology of the fulminant pneumonia. Under broad antibiotic and antiviral treatment, the situation of the patient improved only very slowly.
    Journal of Medical Microbiology 05/2010; 59(Pt 8):980-3. DOI:10.1099/jmm.0.017988-0 · 2.27 Impact Factor
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    Journal of Hepatology 04/2010; 52. DOI:10.1016/S0168-8278(10)61102-6 · 10.40 Impact Factor

Publication Stats

4k Citations
1,349.66 Total Impact Points


  • 1996–2012
    • University of Tuebingen
      • Department of Internal Medicine
      Tübingen, Baden-Wuerttemberg, Germany
  • 1997–2009
    • Universitätsklinikum Tübingen
      Tübingen, Baden-Württemberg, Germany
  • 2005
    • Emory University
      • Division of Digestive Diseases
      Atlanta, Georgia, United States
  • 2004
    • University of Cincinnati
      Cincinnati, Ohio, United States
  • 2003
    • University of Cambridge
      Cambridge, England, United Kingdom
    • Hannover Medical School
      Hanover, Lower Saxony, Germany
  • 2002
    • University of Münster
      Muenster, North Rhine-Westphalia, Germany
  • 2001
    • Johns Hopkins University
      Baltimore, Maryland, United States
    • Evangelische Hochschule Freiburg, Germany
      Freiburg, Baden-Württemberg, Germany
  • 1998
    • Max Planck Institute of Biochemistry
      München, Bavaria, Germany