Einfluss von Xyloglucan Endotransglucosylasen/Hydrolasen auf die Wurzelentwicklung in Arabidopsis thaliana (L.) HEYNH.

Xyloglucane sind Bestandteile der Zellwand Höherer Pflanzen und gehören zu den Hemizellulosen. Xyloglucan Endotransglucosylasen/Hydrolasen (XTHs) sind Enzyme, die spezifisch Xyloglucane spalten und ligieren. Daher wird angenommen, dass sie an der Bildung und Modifizierung primärer Zellwände beteiligt sind und dabei eine wichtige Rolle bei der kontrollierten Expansion von Zellen einnehmen. Im Genom von Arabidopsis sind 33 XTHs identifiziert worden, ihre genaue Funktion ist jedoch weitgehend ungeklärt. Um einen Einblick in die Rolle von XTHs bei der Etablierung der Wurzelarchitektur zu erlangen, wurden XTH15, XTH16, XTH17, XTH18 und XTH19 untersucht. Für genetische Analysen wurden Einfach- und Mehrfach-KO-Linien identifiziert. Da für XTH16 und XTH18 keine KO-Linien zur Verfügung standen, wurden diese mit Hilfe des CRISPR/Cas9-Systems generiert. Es zeigte sich, dass der Funktionsverlust von XTH16 oder XTH18 dazu führt, dass Zellen der Lateralwurzeln weniger stark wachsen, wodurch die Lateralwurzeln von xth16- und xth18-Keimlingen insgesamt kürzer bleiben. Um eine Beteiligung von XTH16 und XTH18 an der Zellstreckung zu untermauern, wurden Hypokotyle etiolierter Keimlinge untersucht, da diese postembryonal ausschließlich durch Zellstreckung wachsen. Es wurde jedoch in den KO-Linien keine Veränderung des Streckungswachstums beobachtet, sodass von einer spezifischen Funktion von XTH16 und XTH18 in wachsenden Lateralwurzelzellen ausgegangen werden kann. Des Weiteren zeigte die Analyse der Expression auf, dass XTH15 und XTH16 während der Blütenentwicklung eine starke Expression in den reproduktiven Organen aufweisen. Beim Funktionsverlust einer oder beider Gene konnte eine verminderte Anzahl von Samenanlagen festgestellt werden. Dies könnte auf eine Funktion von XTH15 und XTH16 an der Entwicklung des Gynoeceums hinweisen. Trotz der hohen Sequenzähnlichkeit zueinander, scheinen die fünf XTH-Gene differenzierte Funktionen in der Entwicklung der Pflanze entwickelt zu haben

In Situ Laser Light Scattering for Temporally and Locally Resolved Studies on Nanoparticle Trapping in a Gas Aggregation Source

Gas phase synthesis of nanoparticles (NPs) via magnetron sputtering in a gas aggregation source (GAS) has become a well-established method since its conceptualization three decades ago. NP formation is commonly described in terms of nucleation, growth, and transport alongside the gas stream. However, the NP formation and transport involve complex non-equilibrium processes, which are still the subject of investigation. The development of in situ investigation techniques such as UV–Vis spectroscopy and small angle X-ray scattering enabled further insights into the dynamic processes inside the GAS and have recently revealed NP trapping at different distances from the magnetron source. The main drawback of these techniques is their limited spatial resolution. To understand the spatio-temporal behavior of NP trapping, an in situ laser light scattering technique is applied in this study. By this approach, silver NPs are made visible inside the GAS with good spatial and temporal resolution. It is found that the argon gas pressure, as well as different gas inlet configurations, have a strong impact on the trapping behavior of NPs inside the GAS. The different gas inlet configurations not only affect the trapping of NPs, but also the size distribution and deposition rate of NPs

Identification of NS2 determinants stimulating intrinsic HCV NS2 protease activity

Hepatitis C Virus NS2-NS3 cleavage is mediated by NS2 autoprotease (NS2pro) and this cleavage is important for genome replication and virus assembly. Efficient NS2-NS3 cleavage relies on the stimulation of an intrinsic NS2pro activity by the NS3 protease domain. NS2pro activation depends on conserved hydrophobic NS3 surface residues and yet unknown NS2-NS3 surface interactions. Guided by an in silico NS2-NS3 precursor model, we experimentally identified two NS2 surface residues, F103 and L144, that are important for NS2pro activation by NS3. When analyzed in the absence of NS3, a combination of defined amino acid exchanges, namely F103A and L144I, acts together to increase intrinsic NS2pro activity. This effect is conserved between different HCV genotypes. For mutation L144I its stimulatory effect on NS2pro could be also demonstrated for two other mammalian hepaciviruses, highlighting the functional significance of this finding. We hypothesize that the two exchanges stimulating the intrinsic NS2pro activity mimic structural changes occurring during NS3-mediated NS2pro activation. Introducing these activating NS2pro mutations into a NS2-NS5B replicon reduced NS2-NS3 cleavage and RNA replication, indicating their interference with NS2-NS3 surface interactions pivotal for NS2pro activation by NS3. Data from chimeric hepaciviral NS2-NS3 precursor constructs, suggest that NS2 F103 is involved in the reception or transfer of the NS3 stimulus by NS3 P115. Accordingly, fine-tuned NS2-NS3 surface interactions are a salient feature of HCV NS2-NS3 cleavage. Together, these novel insights provide an exciting basis to dissect molecular mechanisms of NS2pro activation by NS3

Endovaskuläre Rekonstruktion der thorakalen Aorta bei Aortendissektion

Die Thorakale EndoVaskuläre AortenRekonstruktion (TEVAR) ist eine minimal-invasive Therapiealternative für Patienten mit Typ B-Aortendissektion, die auf der perkutanen Implantation von Stent-Grafts beruht. Die wissenschaftlichen Studien und Analysen, die in dieser Habilitationsschrift zusammengefasst sind, belegen die sehr gute technische Durchführbarkeit und hohe Sicherheit der TEVAR sowie die Bedeutung der transösophagealen Echokardiographie, des intravaskulären Ultraschall und der Schrittmacher-induzierten Hypotension während der Implantation von Stent-Grafts

Leiomyosarcoma of the inferior vena cava: Radical surgery and vascular reconstruction

<p>Abstract</p> <p>Background</p> <p>Vascular leiomyosarcoma are rare tumors typically originating from the inferior vena cava (IVC). Due to nonspecific clinical signs most tumors are diagnosed at advanced stages. Complete surgical resection remains the only potential curative therapeutic option. Surgical strategy is particularly influenced by the level of the IVC affected. Due to the topographic relation to the renal veins level-II involvement of the IVC raises special surgical challenges with respect to the maintenance of venous outflow.</p> <p>Case presentation</p> <p>We herein report two cases of leiomyosarcoma of the IVC with successful en bloc resection and individualized caval reconstruction. One patient presented with a large intramural and intraluminal mass and received a complete circumferential resection. Reconstruction was performed by graft replacement of the caval segment affected. The other patient displayed a predominantly extraluminal tumor growth and underwent semicircumferential resection of the IVC including the confluence of the left renal vein. In this case vascular reconstruction was performed by cavoplasty and reinsertion of the left renal vein into the proximal portion of the IVC. Resection margins of both patients were tumor free and no clinical signs of venous insufficiency of the lower extremity occurred.</p> <p>Conclusion</p> <p>This paper presents two cases of successfully managed leiomyosarcomas of the vena cava and exemplifies two different options for vascular reconstruction in level II sarcomas and includes a thorough review of the literature.</p

Recurrent Fistula between Ileal Pouch and Vagina—Successful Treatment with a Gracilis Muscle Flap

Fistulae between an ileal pouch and the vagina are an uncommon complication of ileal pouch-anal anastomosis following proctocolectomy and mucosectomy in patients with familial adenomatous polyposis coli. Several reports describe the successful use of muscle flaps to close recurrent pouch-vaginal-fistulae (PVF). However, series only contain small numbers and an optimal management has not yet been determined. We report the case of a 26-year old woman with a third recurrence of a PVF after proctocolectomy for treatment of familial adenomatous polyposis in October 2005. Because local approaches failed, definitive closure of the fistula was achieved by interposition of a gracilis muscle flap between the pouch-anal anastomosis and the vagina. The postoperative course was uneventful; the patient was discharged 7 days after surgery and remained free of recurrence and symptomatic complaints for 22 months now. The gracilis muscle flap proved to be an effective method in the treatment of recurrent PVF

Laparotomy enables retrograde dilatation and stent placement for malignant esophago-respiratory fistula

<p>Abstract</p> <p>Background</p> <p>Malignant esophageal stenosis with complete obstruction and esophagorespiratory fistula (ERF) is difficult to treat with standard endoscopic techniques.</p> <p>Case presentation</p> <p>We report a patient in whom with local recurrence of esophageal carcinoma an esophagotracheal fistula occurred. Initially the patient had undergone esophageal resection with interposition of a gastric tube. Due to complete obstruction of the lumen by recurrent tumor conventional transoral stent placement failed. For retrograde dilatation a laparotomy was performed. Via a duodenal incision endoscopic access to the gastric tube was achieved. Using a guidewire the esophageal obstruction was traversed and dilated. Then it was possible to place an esophageal stent via an antegrade approach.</p> <p>Conclusion</p> <p>Open surgery enables a safe access for retrograde endoscopic therapy in patients who had undergone esophageal resection with gastric interposition.</p