Browsing by Author "Gaedcke, Jochen"

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    EEPD1 Rescues Stressed Replication Forks and Maintains Genome Stability by Promoting End Resection and Homologous Recombination Repair
    (Public Library of Science (PloS), 2015-12) Wu, Yuehan; Lee, Suk-Hee; Williamson, Elizabeth A.; Reinert, Brian L.; Cho, Ju Hwan; Xia, Fen; Jaiswal, Aruna Shanker; Srinivasan, Gayathri; Patel, Bhavita; Brantley, Alexis; Zhou, Daohong; Shao, Lijian; Pathak, Rupak; Hauer-Jensen, Martin; Singh, Sudha; Kong, Kimi; Wu, Xaiohua; Kim, Hyun-Suk; Beissbarth, Timothy; Gaedcke, Jochen; Burma, Sandeep; Nickoloff, Jac A.; Hromas, Robert A.; Department of Biochemistry and Molecular Biology, IU School of Medicine
    Replication fork stalling and collapse is a major source of genome instability leading to neoplastic transformation or cell death. Such stressed replication forks can be conservatively repaired and restarted using homologous recombination (HR) or non-conservatively repaired using micro-homology mediated end joining (MMEJ). HR repair of stressed forks is initiated by 5' end resection near the fork junction, which permits 3' single strand invasion of a homologous template for fork restart. This 5' end resection also prevents classical non-homologous end-joining (cNHEJ), a competing pathway for DNA double-strand break (DSB) repair. Unopposed NHEJ can cause genome instability during replication stress by abnormally fusing free double strand ends that occur as unstable replication fork repair intermediates. We show here that the previously uncharacterized Exonuclease/Endonuclease/Phosphatase Domain-1 (EEPD1) protein is required for initiating repair and restart of stalled forks. EEPD1 is recruited to stalled forks, enhances 5' DNA end resection, and promotes restart of stalled forks. Interestingly, EEPD1 directs DSB repair away from cNHEJ, and also away from MMEJ, which requires limited end resection for initiation. EEPD1 is also required for proper ATR and CHK1 phosphorylation, and formation of gamma-H2AX, RAD51 and phospho-RPA32 foci. Consistent with a direct role in stalled replication fork cleavage, EEPD1 is a 5' overhang nuclease in an obligate complex with the end resection nuclease Exo1 and BLM. EEPD1 depletion causes nuclear and cytogenetic defects, which are made worse by replication stress. Depleting 53BP1, which slows cNHEJ, fully rescues the nuclear and cytogenetic abnormalities seen with EEPD1 depletion. These data demonstrate that genome stability during replication stress is maintained by EEPD1, which initiates HR and inhibits cNHEJ and MMEJ.
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    Impact of Endoscopic Vacuum Therapy with Low Negative Pressure for Esophageal Perforations and Postoperative Anastomotic Esophageal Leaks
    (Karger, 2020) Jung, Carlo Felix Maria; Müller-Dornieden, Annegret; Gaedcke, Jochen; Kunsch, Steffen; Gromski, Mark A.; Biggemann, Lorenz; Hosseini, Ali Seif Amir; Ghadimi, Michael; Ellenrieder, Volker; Wedi, Edris; Medicine, School of Medicine
    Introduction: Management of esophageal anastomotic leaks (AL) and esophageal perforations (EP) remains difficult and often requires an interdisciplinary treatment modality. For primary endoscopic management, self-expanding metallic stent (SEMS) placement is often considered first-line therapy. Recently, endoscopic vacuum therapy (EVT) has emerged as an alternative or adjunct for management of these conditions. So far, data for EVT in the upper gastrointestinal-tract is restricted to single centre, non-randomized trials. No studies on optimal negative pressure application during EVT exist. The aim of our study is to describe our centre’s experience with low negative pressure (LNP) EVT for these indications over the past 5-years. Patients and Methods: Between January 2014 and December 2018, 30 patients were endoscopically treated for AL (n = 23) or EP (n = 7). All patients were primarily treated with EVT and LNP between –20 and –50 mm Hg. Additional endoscopic treatment was added when EVT failed. Procedural and peri-procedural data, as well as clinical outcomes including morbidity and mortality, were analysed. Results: Clinical successful endoscopic treatment of EP and AL was achieved in 83.3% (n = 25/30), with 73.3% success using EVT alone (n = 22/30). Mean treatment duration until leak closure was 16.1 days (range 2–58 days). Additional treatment modalities for complete leak resolution was necessary in 10% (n = 3/30), including SEMS placement and fibrin glue injection. Mean hospital stay for patients with EP was shorter with 33.7 days compared to AL with 54.4 days (p = 0.08). Estimated preoperative 10-year overall survival (Charlson comorbidity score) was 39.4% in patients with AL and 59.9% in patients with EP (p = 0.26). A mean of 5.1 EVT changes (range 1–12) was needed in EP and 3.6 changes (range 1–13) in AL to achieve complete closure, switch to other treatment modality, or reach endoscopic failure (p = 0.38). Conclusion: LNP EVT enables effective minimally – invasive endoluminal leak closure from anastomotic esophageal leaks and EP in high-morbid patients. In this study, EVT was combined with other endoscopic treatment options such as SEMS placement or fibrin glue injection in order to achieve leak or perforation closure in the vast majority of patients (83.3%). Low aspiration pressures led to slower but still sufficient clinical results.