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Rhodopsins are the most universal biological light-energy transducers and abundant phototrophic mechanisms that evolved on Earth and have a remarkable diversity and potential for biotechnological applications. Recently, the first sodium-pumping rhodopsin KR2 from Krokinobacter eikastus was discovered and characterized. However, the existing structures of KR2 are contradictory, and the mechanism of Na+ pumping is not yet understood. Here, we present a structure of the cationic (non H+) light-driven pump at physiological pH in its pentameric form. We also present 13 atomic structures and functional data on the KR2 and its mutants, including potassium pumps, which show that oligomerization of the microbial rhodopsin is obligatory for its biological function. The studies reveal the structure of KR2 at nonphysiological low pH where it acts as a proton pump. The structure provides new insights into the mechanisms of microbial rhodopsins and opens the way to a rational design of novel cation pumps for optogenetics.
Purpose: To investigate the efficacy and safety of Descemet membrane endothelial keratoplasty (DMEK) for corneal decompensation following primary Descemet stripping automated endothelial keratoplasty (DSAEK).
Methods: This was a retrospective case series of 15 patients that underwent DMEK surgery for corneal decompensation after failed DSAEK. Main outcome parameter was corrected distance visual acuity (CDVA) after DMEK and DSAEK. Secondary outcome measures included central corneal thickness (CCT), endothelial cell density (ECD), rebubbling rate, and primary graft failure after DMEK. Explanted DSAEK grafts were evaluated by light microscopy.
Results: The mean (±SD) time period between DSAEK and DMEK surgery was 15±8 months (range, 6–31 months). Preoperative CDVA was 1.72±0.62 (logMAR). After DMEK, CDVA improved significantly to 0.78±0.48 at 1 month and to 0.23±0.24 after 12 months (P=0.022). Visual acuity data after DMEK were significantly better compared to preoperative values. The average CCT after DMEK decreased significantly from 869±210 µm (preoperative) to 505±45 µm (1 month postoperative) (P<0.001) and remained stable over 12 months. The ECD decreased from 2,589±209/mm2 (preoperative) to 1,691±589/mm2 (12 months postoperative). Rebubbling DMEK was required in three patients (=20%).
Conclusion: DMEK represents a feasible and safe procedure in achieving better functional results compared to DSAEK. Visual acuity and optical quality can be effectively reestablished after unsuccessful primary DSAEK surgery even in patients with long-standing corneal decompensation. Further investigations are required to validate the preliminary clinical findings.
Mechanism of the electroneutral sodium/proton antiporter PaNhaP from transition-path shooting
(2019)
Na+/H+ antiporters exchange sodium ions and protons on opposite sides of lipid membranes. The electroneutral Na+/H+ antiporter NhaP from archaea Pyrococcus abyssi (PaNhaP) is a functional homolog of the human Na+/H+ exchanger NHE1, which is an important drug target. Here we resolve the Na+ and H+ transport cycle of PaNhaP by transition-path sampling. The resulting molecular dynamics trajectories of repeated ion transport events proceed without bias force, and overcome the enormous time-scale gap between seconds-scale ion exchange and microseconds simulations. The simulations reveal a hydrophobic gate to the extracellular side that opens and closes in response to the transporter domain motion. Weakening the gate by mutagenesis makes the transporter faster, suggesting that the gate balances competing demands of fidelity and efficiency. Transition-path sampling and a committor-based reaction coordinate optimization identify the essential motions and interactions that realize conformational alternation between the two access states in transporter function.
With an increased understanding of the tumor biology of squamous cell carcinoma of the head and neck (SCCHN), targeted therapies have found their way into the clinical treatment routines against this entity. Nevertheless, to date platinum-based cytostatic agents remain the first line choice and targeting the epidermal growth factor-receptor (EGFR) with combined cetuximab and radiation therapy remains the only targeted therapy approved in the curative setting. Investigation of immune checkpoint inhibitors (ICI), such as antibodies targeting programmed cell death protein 1 (PD-1) and its ligand PD-L1, resulted in a change of paradigms in oncology and in the first approval of new drugs for treating SCCHN. Nivolumab and pembrolizumab, two anti-PD-1 antibodies, were the first agents shown to improve overall survival for patients with metastatic/recurrent tumors in recent years. Currently, several clinical trials investigate the role of ICI in different therapeutic settings. A robust set of biomarkers will be an inevitable tool for future individualized treatment approaches including radiation dose de-escalation and escalation strategies. This review aims to summarize achieved goals, the current status and future perspectives regarding targeted therapies and ICI in the management of SCCHN.
Cyanobacteria are photoautotrophic microorganisms present in almost all ecologically niches on Earth. They exist as single-cell or filamentous forms and the latter often contain specialized cells for N2 fixation known as heterocysts. Heterocysts arise from photosynthetic active vegetative cells by multiple morphological and physiological rearrangements including the absence of O2 evolution and CO2 fixation. The key function of this cell type is carried out by the metalloprotein complex known as nitrogenase. Additionally, many other important processes in heterocysts also depend on metalloproteins. This leads to a high metal demand exceeding the one of other bacteria in content and concentration during heterocyst development and in mature heterocysts. This review provides an overview on the current knowledge of the transition metals and metalloproteins required by heterocysts in heterocyst-forming cyanobacteria. It discusses the molecular, physiological, and physicochemical properties of metalloproteins involved in N2 fixation, H2 metabolism, electron transport chains, oxidative stress management, storage, energy metabolism, and metabolic networks in the diazotrophic filament. This provides a detailed and comprehensive picture on the heterocyst demands for Fe, Cu, Mo, Ni, Mn, V, and Zn as cofactors for metalloproteins and highlights the importance of such metalloproteins for the biology of cyanobacterial heterocysts.
Do household inflation expectations affect consumption-savings decisions? We link survey data on quantitative inflation expectations to administrative data on income and wealth. We document that households with higher inflation expectations save less. Estimating panel data models with year and household fixed effects, we find that a one percentage point increase in a household's inflation expectation over time is associated with a 250-400 euro reduction in the household's change in net worth per year on average. We also document that households with higher inflation expectations are more likely to acquire a car and acquire higher-value cars. In addition, we provide a quantitative model of household-level inflation expectations.
Der vorliegende Band dokumentiert die Erhebungsinstrumente der dritten Phase des BilWiss-Forschungsprogramms BilWiss-UV1 ("Ertrag und Entwicklung des universitären bildungswissenschaftlichen Wissens - Validierung eines Kompetenztests für Lehrkräfte") zu wissenschaftlichen Zwecken. Ziel dieser letzten Projektphase ist die Weiterentwicklung und Verbesserung des in den Vorgängerprojekten "BilWiss" und "BilWiss-Beruf" entwickelten Kompetenztests zur Erfassung des bildungswissenschaftlichen Wissens bei Lehramtsstudierenden und -absolvent(inn)en. Dieses Skalenhandbuch dokumentiert ausschlieÿlich den im Rahmen von BilWiss-UV erhobenen Studierendenlängsschnitt (LSII) der vorwiegend der Frage nachgeht, inwieweit sich bildungswissenschaftliches Wissen als Folge der Instruktion im Lehramtsstudium verändert. Ziel des Studierendenlängsschnittes ist es, eine Verteilung der Studierenden über den kompletten Studienverlauf abzubilden, da davon ausgegangen wird, dass je nach Fortschritt im Studium ein unterschiedlicher Bildungswissenschaftlicher Wissensstand zu erwarten ist. Das Projekt wird im Rahmen des BMBF-Förderprogramms "KoKoHS - Kompetenzmodelle und Instrumente der Kompetenzerfassung im Hochschulsektor-Validierung und methodische Innovationen" gefördert. Das Forschungsprogramm ist ein Verbundprojekt der Goethe-Universität Frankfurt (Prof. Dr. Mareike Kunter, Koordination), der Universität Duisburg-Essen (Prof. Dr. Detlev Leutner) sowie der Technischen Universität München (Prof. Dr. Tina Seidel). Das gesamte Programm zielt darauf ab, zu untersuchen, inwieweit angehende Lehrkräfte durch das Studium der Bildungswissenschaften unterstützt werden, mit den vielfältigen Herausforderungen ihres Berufs professionell umzugehen. Die zentrale Annahme dabei ist, dass konzeptuelles Wissen über bildungswissenschaftliche Inhalte die professionelle Entwicklung im Vorbereitungsdienst und im Berufseinstieg unterstützt. Die Grundhypothese des Projekts lautet: Bildungswissenschaftliche Inhalte und Zusammenhänge stellen einen begrifflichen Rahmen dar, den Lehrkräfte benötigen, um Unterrichts- und Schulereignisse angemessen zu interpretieren, zu reflektieren und so für die eigene Kompetenzentwicklung zu nutzen. Die in der Studie eingesetzten Instrumente sollen öffentlich für wissenschaftliche Zwecke zugänglich gemacht werden und sind vor allem als Hilfestellung für die Arbeit mit dem Längsschnittdatensatz anzusehen. Bereits veröffentlicht unter ISBN: 978-3-00-055380-6 finden Sie die Erhebungsinstrumente der Projektphasen des BilWiss-Forschungsprogramms von 2009-2016. Weiterführende Informationen zum theoretischen Ansatz der Studie und Ergebnissen der Studie können der Internetseite http://www.bilwiss.uni-frankfurt.de sowie den im Literaturverzeichnis aufgeführten Publikationen entnommen werden.