The need of rebubbling in case of small graft detachments after Descemet Membrane Endothelial Keratoplasty (DMEK).

PURPOSE To investigate the need of rebubbling for small graft detachments after Descemet Membrane Endothelial Keratoplasty (DMEK). METHODS In this retrospective study we evaluated 111 eyes from 111 patients that showed graft detachment after DMEK surgery and have achieved graft adherence by injection of air or 20% sulfur hexafluoride (SF6) to the anterior chamber (rebubbling group; n = 57) or by spontaneous adherence without intervention (control group; n = 54) at final examination. Subgroups in terms of the maximum height and in terms of the detachment area in relation to graft area were formed. Outcome measures were the increase in best-corrected visual acuity (BCVA) and the decrease in central corneal thickness (CCT) from the measurement before DMEK to six months after surgery and postoperative endothelial cell density. RESULTS BCVA increased in the rebubbling group and the control group, the difference being 0.22 logMAR, p = 0.048. For eyes with a maximum height less than 500 µm, the increase of BCVA was 0.39 ± 0,36 logMAR in the control group and 0.62 ± 0,53 logMAR in the rebubbling group, p = 0.045. There was no difference of statistical significance of BCVA between both groups regarding the detachment area of less than 20% in relation to graft area. The mean decrease in CCT and postoperative endothelial cell density showed no significant difference between the rebubbling group and the control group. CONCLUSION Compared to spontaneous graft adherence, a rebubbling shows no beneficial effect on the clinical outcome for small detached DMEK grafts. Rebubbling does not decrease postoperative endothelial cell density

Der Einsatz von E-Learning durch Studierende der Medizin: Eine Untersuchung an derUniversität Leipzig

Mittels E-Learning kann den spezifischen Erfordernissen der universitären medizinischen Ausbildung auf vielfältige Weise Rechnung getragen werden. Eine in den Anfangsjahren des WWW bestehende große Euphorie ist mittlerweile einer realistischeren Betrachtung der Möglichkeiten von E-Learning gewichen. Umso mehr ist ein gezielter Einsatz der speziellen Stärken von E-Learning – sei es als reines Lernen im WWW oder in Kombination mit klassischer Lehre als „Blended Learning“ – wünschenswert. In der vorliegenden Arbeit wurden Studierende aus zwei Studienjahren der medizinischen Fakultät der Universität Leipzig zu verschiedenen Aspekten des E-Learnings im Medizinstudium befragt. Der Fokus lag auf der Nutzungshäufigkeit, der Art des Einsatzes und den gewünschten Perspektiven. Zunächst konnte bestätigt werden, dass die technischen Voraussetzungen für die Nutzung von E-Learning mittlerweile bei praktisch allen Studierenden gegeben sind. Das WWW wird auf breiter Front für Studienzwecke eingesetzt und die Studierenden schätzen ihre eigenen Fähigkeiten im Umgang mit dem WWW als gut ein. Dabei besteht eine positive Korrelation zwischen der Nutzungshäufigkeit zwischen der Nutzungshäufigkeit und den selbst eingeschätzten Fähigkeiten. Es zeigte sich jedoch anhand verschiedener Einzelbefunde, dass von Seiten der Studierenden bei Weitem nicht die Möglichkeiten des Lernens mit dem WWW ausgeschöpft werden. Das WWW wird zwar auf verschiedenste Arten für das Studium eingesetzt, der Anteil aktiv partizipierender Nutzer im Sinne des Web 2.0 ist jedoch gering. Eine hohe Bekanntheit der lokalen Virtual Learning Community steht sehr geringen Bekanntheitsgraden von Portalen gegenüber, die eine Übersicht über die Bandbreite des E-Learnings für das Medizinstudium bieten und als Orientierungshilfe bei der Fülle der verfügbaren Angebote dienen könnten. Des Weiteren wird die Integration verschiedener E-Learning-Techniken in das Studium umso zurückhaltender bewertet, je mehr sie die bekannten Pfade der klassischen Präsenzlehre verlassen. Generell wünschen sich die wenigsten Studierenden einen völligen Ersatz klassischer Lehrmethoden durch E-Learning; vielmehr wird eine Ergänzung der klassischen Präsenzlehre durch E-Learning bevorzugt. Eine kritische Reflexion der online gewonnenen Informationen im Sinne der Medienkompetenz scheint mehrheitlich stattzufinden. Unterschiede zwischen den Semestern fanden sich in der vorliegenden Untersuchung kaum – mit Ausnahme einiger relativ gut erklärbarer Bereiche mit häufigerer Nutzung im höheren Semester. Statistisch signifikante geschlechterspezifische Unterschiede fanden sich lediglich bei der Häufigkeit eigener Beiträge im WWW zugunsten männlicher Studierender. Ein möglicher Ansatzpunkt für künftige Forschungsprojekte, der sich aus der Arbeit ergibt, wäre eine detailliertere Betrachtung derjenigen Studierenden, die sehr aktiv im WWW sind. Obwohl sie zahlenmäßig gering vertreten sind, pragen sie doch die virtuellen Lernumgebungen zum Teil erheblich mit. Bezüglich möglicher Perspektiven für die weitere Ausgestaltung von E-Learning besteht in der Zusammenschau der vorliegenden Ergebnisse sowohl auf studentischer als auch auf universitärer Seite noch viel Gestaltungspotential: Einerseits sollte das studentische Wissen um die vielfältigen Möglichkeiten der Integration des WWW in das Medizinstudium gefördert werden; andererseits ist die Umsetzung der von den Studierenden geforderten E-Learning-Techniken wünschenswert und eine verstärkte curriculare Einbindung von E Learning zu überdenken

Descemet membrane endothelial keratoplasty (DMEK) improves vision-related quality of life.

PURPOSE To evaluate vision-related quality of life (VRQL) before and after Descemet membrane endothelial keratoplasty (DMEK). METHODS The study was conducted in patients with Fuchs endothelial dystrophy or pseudophakic bullous keratopathy undergoing DMEK alone or in combination with cataract surgery (triple-DMEK) between August 2019 and March 2020 at the University of Leipzig Medical Center. Best-corrected visual acuity (BCVA) was measured. Visual acuity factor (VAF) and glare factor (GF) scores were calculated using the Visual Function and Corneal Health Status Instrument questionnaire answered by patients before surgery and 6 months thereafter. Subgroup analyses were performed for DMEK versus triple-DMEK, and for first versus second eyes, in addition to correlation analyses of scores with preoperative BCVA. RESULTS Forty-six patients were included in this analysis. VAF score improved from 0.68 ± 0.54 to 0.02 ± 0.57 (P < 0.0001) and GF score improved from 0.53 ± 0.43 to -0.11 ± 0.39 (P < 0.0001) during follow-up. Both scores improved without significant differences after surgery in the first and in the fellow eye (P < 0.0001) and after DMEK and triple-DMEK (P < 0.0001). The improvement of scores did not correlate with preoperative BCVA (r = 0.06, P = 0.68 for VAF; r =  -0.09, P = 0.54 for GF). CONCLUSION VRQL improves similarly after DMEK and triple-DMEK and between first and second operated eye. The extent of improvement is independent of the preoperative BCVA. The results of this study can be useful when planning DMEK by enabling a prediction of anticipated VRQL gain

Retinometer predicts visual outcome in Descemet membrane endothelial keratoplasty.

PURPOSE To analyze the preoperative predictive value of retinometer visual acuity (VA) in eyes following Descemet membrane endothelial keratoplasty (DMEK). METHODS Patients undergoing DMEK between August 2011 and July 2020 were included. Preoperative interference visual acuity was assessed using Heine Lambda 100 Retinometer. Depending on the presence or absence of concomitant ocular disease, the Retinometer was evaluated for its ability to preoperatively predict best-corrected visual acuity (BCVA) six months after surgery using correlation, simple and multiple linear regression, contingency analyses, and receiver operating characteristic (ROC) analysis. Preoperative corneal backscatter was correlated with Retinometer prediction accuracy. RESULTS A total of 198 eyes were included in the analysis. There was a significant correlation between Retinometer VA and postoperative BCVA (r = 0.647, P < 0.001). Regardless of the presence or absence of concomitant ocular disease and the surgery procedure (DMEK & triple DMEK), Retinometer VA was the most significant predictor of postoperative BCVA (P < 0.001). ROC analysis revealed reliable diagnostic performance of the Retinometer (AUC = 0.829, P < 0.001). A Retinometer VA ≥ 0.5 accurately predicted a postoperative BCVA ≥ 0.5 in 91% of cases. No association was found between corneal backscatter and prediction accuracy (P = 0.566). CONCLUSIONS Retinometer VA can be used for preoperative prediction of postoperative BCVA in DMEK and triple DMEK patients, independent of increased backscatter values and the presence or absence of concomitant ocular disease. By using this simple but effective tool, indication for DMEK can be facilitated and postoperative outcomes can be realistically predicted preoperatively

Reading cognition from the eyes: Association of retinal nerve fiber layer thickness with cognitive performance in a population-based study

With the eye as a window to the brain, non-invasive fast screening of retinal nerve fibre layer thickness poses the opportunity for early detection of cognitive decline leading to dementia. Our objective is to determine whether performance in various neurocognitive tests has an association with itemized retinal nerve fibre layer thickness. Detailed investigation of associations factored in sex and eye-side. The large population-based LIFE-Adult study (Leipzig Research Centre for Civilization Diseases) was conducted at Leipzig University, Germany from 2011 to 2014. Randomly selected participants (N = 10 000) were drawn from population registry in an age- and gender-stratified manner, focusing on 40-80 years. Cognitive function was examined with the CERAD-NP Plus test-battery (Consortium to Establish a Registry for Alzheimer's Disease), Stroop-Test, Reading the Mind in the Eyes-Test and Multiple-Choice Vocabulary Intelligence Test. Circumpapillary retinal nerve fibre layer thickness was measured with Optical Coherence Tomography. Subjects with reliable measurements (≥50 B-scan repetitions, signal-to-noise-ratio ≥20 dB, ≤5% missing A-scans) and without clinical eye pathology (sample A) and additional exclusion due to conditions of the central nervous system (sample B) were evaluated. The relationship between cognitive function and retinal nerve fibre layer thickness was investigated for six segments: temporal, temporal-superior, temporal-inferior, nasal, nasal-superior and nasal-inferior. For comparison with other studies, global mean is given. Brain-side projection analysis links results to the corresponding brain hemisphere. We analysed 11 124 eyes of 6471 subjects [55.5 years of age (19.1-79.8 years), 46.9% male]. Low cognitive performance was predominantly associated with thinner retinal nerve fibre layer thickness. Correlation analysis indicated emphasis on global and temporally located effects. Multivariable regression analysis with adjustments (age, sex and scan radius) presented individual results for each test, differentiating between sex and eye-side. For instance, verbal fluency tests and Trail Making Test-B show stronger association in females; Trail Making Test-A shows right-eye dominance. Findings in Trail-Making-Test-A projected to left brain hemisphere, and the ratio incongruent to neutral in the Stroop test projected to right brain-hemisphere. Separate assessment for sex and eye-side is presented for the first time in a population-based study. Location-specific sectorial retinal nerve fibre layer thickness was found to be an indicator for cognitive performance, giving an option for early detection of cognitive decline and the potential of early treatment. The eye as a window to the brain was studied with optical coherence tomography and connected to cognition. Girbardt et al. report that thinner retinal nerve fibre layer thickness was found to be a meaningful index for poorer cognitive performance which presents the potential for prediction of future cognitive decline

Structural and Biophysical Insights into SPINK1 Bound to Human Cationic Trypsin

(1) The serine protease inhibitor Kazal type 1 (SPINK1) inhibits trypsin activity in zymogen granules of pancreatic acinar cells. Several mutations in the SPINK1 gene are associated with acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP). The most common variant is SPINK1 p.N34S. Although this mutation was identified two decades ago, the mechanism of action has remained elusive. (2) SPINK1 and human cationic trypsin (TRY1) were expressed in E. coli, and inhibitory activities were determined. Crystals of SPINK1–TRY1 complexes were grown by using the hanging-drop method, and phases were solved by molecular replacement. (3) Both SPINK1 variants show similar inhibitory behavior toward TRY1. The crystal structures are almost identical, with minor differences in the mutated loop. Both complexes show an unexpected rotamer conformation of the His63 residue in TRY1, which is a member of the catalytic triad. (4) The SPINK1 p.N34S mutation does not affect the inhibitory behavior or the overall structure of the protein. Therefore, the pathophysiological mechanism of action of the p.N34S variant cannot be explained mechanistically or structurally at the protein level. The observed histidine conformation is part of a mechanism for SPINK1 that can explain the exceptional proteolytic stability of this inhibitor

Regulation of polarised growth in fungi

Polarised growth in fungi occurs through the delivery of secretory vesicles along tracks formed by cytoskeletal elements to specific sites on the cell surface where they dock with a multiprotein structure called the exocyst before fusing with the plasmamembrane. The budding yeast, Saccharomyces cerevisiae has provided a useful model to investigate the mechanisms involved and their control. Cortical markers, provided by bud site selection pathways during budding, the septin ring during cytokinesis or the stimulation of the pheromone response receptors during mating, act through upstream signalling pathways to localise Cdc24, the GEF for the rho family GTPase, Cdc42. Cdc42 in its GTP-bound activates a multiprotein protein complex called the polarisome which nucleates actin cables along which the secretory vesicles are transported to the cell surface. Hyphae can elongate at a rate orders of magnitude faster than the extension of a yeast bud, so understanding hyphal growth will require substantial modification of the yeast paradigm. The rapid rate of hyphal growth is driven by a structure called the Spitzenkörper, located just behind the growing tip and which is rich in secretory vesicles. It is thought that secretory vesicles are delivered to the apical region where they accumulate in the Spitzenkörper. The Spitzenkörper then acts as vesicle supply centre in which vesicles exit the Spitzenkörper in all directions, but because of its proximity, the tip receives a greater concentration of vesicles per unit area than subapical regions. There are no obvious equivalents to the bud site selection pathway to provide a spatial landmark for polarised growth in hyphae. However, an emerging model is the way that the site of polarised growth in the fission yeast, Schizosaccharomyces pombe, is marked by delivery of the kelch repeat protein, Tea1, along microtubules. The relationship of the Spitzenkörper to the polarisome and the mechanisms that promote its formation are key questions that form the focus of current research

Involvement of an Actomyosin Contractile Ring in Saccharomyces cerevisiae Cytokinesis

In Saccharomyces cerevisiae, the mother cell and bud are connected by a narrow neck. The mechanism by which this neck is closed during cytokinesis has been unclear. Here we report on the role of a contractile actomyosin ring in this process. Myo1p (the only type II myosin in S. cerevisiae) forms a ring at the presumptive bud site shortly before bud emergence. Myo1p ring formation depends on the septins but not on F-actin, and preexisting Myo1p rings are stable when F-actin is depolymerized. The Myo1p ring remains in the mother–bud neck until the end of anaphase, when a ring of F-actin forms in association with it. The actomyosin ring then contracts to a point and disappears. In the absence of F-actin, the Myo1p ring does not contract. After ring contraction, cortical actin patches congregate at the mother–bud neck, and septum formation and cell separation rapidly ensue. Strains deleted for MYO1 are viable; they fail to form the actin ring but show apparently normal congregation of actin patches at the neck. Some myo1Δ strains divide nearly as efficiently as wild type; other myo1Δ strains divide less efficiently, but it is unclear whether the primary defect is in cytokinesis, septum formation, or cell separation. Even cells lacking F-actin can divide, although in this case division is considerably delayed. Thus, the contractile actomyosin ring is not essential for cytokinesis in S. cerevisiae. In its absence, cytokinesis can still be completed by a process (possibly localized cell–wall synthesis leading to septum formation) that appears to require septin function and to be facilitated by F-actin

Endocytosis and early endosome motility in filamentous fungi.

types: REVIEWOpen Access funded by Biotechnology and Biological Sciences Research CouncilHyphal growth of filamentous fungi requires microtubule-based long-distance motility of early endosomes. Since the discovery of this process in Ustilago maydis, our understanding of its molecular basis and biological function has greatly advanced. Studies in U. maydis and Aspergillus nidulans reveal a complex interplay of the motor proteins kinesin-3 and dynein, which co-operate to support bi-directional motion of early endosomes. Genetic screening has shed light on the molecular mechanisms underpinning motor regulation, revealing Hook protein as general motor adapters on early endosomes. Recently, fascinating insight into unexpected roles for endosome motility has emerged. This includes septin filament formation and cellular distribution of the machinery for protein translation.BBSR