The circadian surface of Neuospora crassa - From physiology to molecular mechanisms

Circadian rhythms influence almost every process in almost every organism. Understanding circadian rhythmicity is a crucial tool to understand many other biological processes. In this study Neurospora crassa, a filamentous fungus, was used to investigate the synchronization of internal time and external light-dark cycles (light entrainment). For physiology experiments a circadian surface was done, taking light-dark cycles of different lengths and varying the ratio of light to dark within each cycle. A highly systematic response could be seen: In cycles shorter than the free running period (FRP), conidiation in N. crassa entrains to dawn, in cycles with a length around the FRP conidiation entrains to midnight, and in cycles longer than the FRP conidiation entrains to dusk. This shows that N.c. entrains to light-dark cycles rather than to be driven by them. Additionally, N.c. entrains even to skeleton photoperiods with characteristics similar to other, higher, organisms. The results allowed to deduct a set of simple and highly systematic rules for entrainment to light, which can now be tested in higher organisms with less experimental effort. After entrainment on the physiology level was shown, the next step in this thesis was to investigate the mechanisms on the molecular level. Here a replication and enhancement of previous results was shown: The quick up-regulation of RNA after lights-on was repeated. Further repeating previous results, protein kinetics were shown to not be uniformly coupled to RNA-kinetics. Enhancing previous results, protein degradation seems to play an important role in entrainment, changing systematically with the varying entrainment protocols. Circadian research has been focused on the free-running period. In the future, entrainment - as an expression of the active process of zeitgeber computation by the circadian clock - will be studied more closely to understand the clock wheels of the circadian system. With this thesis it was shown that even a simple organism like Neurospora crassa entrains to light cycles rather than to be merely driven, and it entrains with characteristics that are comparable to higher organisms. This underlines the usefulness of Neurospora crassa as a model organism in circadian research, and lays the ground for entrainment research in higher organisms.Circadiane Rhythmen beeinflussen fast jeden biologischen Prozess in fast jedem Organismus. Das Verständnis von circadianen Rhythmen ist entscheidend um viele andere biologische Prozesse zu verstehen. In dieser Doktorarbeit wurde der Sprosspilz Neurospora crassa benutzt um die Synchronisation von innerer Uhr mit Hell-Dunkel Zyklen zu untersuchen (Licht-„Entrainment“). Durch physiologische Experimente wurde eine circadiane Oberfläche erstellt, indem die Sporulation von Neurospora crassa in Licht-Dunkel-Zyklen verschiedener Länge mit unterschiedlichen Licht-Dunkel-Verhältnissen innerhalb der einzelnen Zyklen analysiert wurde. Das Verhalten von Neurospora war sehr systematisch: In Lichtzyklen, die kürzer als der innere Tag waren, synchronisierte sich die Sporulation bei N. crassa relativ zur Morgendämmerung (Licht an), in Zyklen die in etwa der inneren Uhrlänge entsprachen synchronisierte sie sich zu Mitternacht, und in Zyklen die länger waren zur Abenddämmerung (Licht aus). Dies zeigte, dass sich N.c. aktiv mit Licht-Dunkel-Zyklen synchronisiert anstatt nur auf sie zu reagieren. Zusätzlich konnte gezeigt werden, dass N.c. sich sogar mit skelettierten Licht-Dunkel-Zyklen (Die Licht-an und die Licht-aus-Grenze wurden durch 2-stündige Lichtpulse simuliert) aktiv synchronisiert, und zwar mit einer Systematik die in höheren Organismen schon beschrieben wurde. Mit diesen Ergebnissen konnten einfache aber sehr systematische Regeln für circadiane Lichtsynchronisation erstellt werden. Diese könne nun wiederum benutzt werden, um Lichtsynchronisation in höheren Organismen zu untersuchen, bei denen die aufwendigen Experimente dieser Doktorarbeit logistisch nicht möglich sind. Nachdem die aktive Synchronisation von innerer Uhr und äußeren Zeitgebern gezeigt wurde, wurden in dieser Doktorarbeit die molekularen Mechanismen der Synchronisation von innerer und äußerer Zeit untersucht. Es konnten vorherige Ergebnisse repliziert und erweitert werden: Die schnelle Hoch-Regulierung von RNA durch das Lichtsignal wurde bestätigt, ebenso wie die vorherigen Ergebnisse unserer Gruppe, dass RNA-Kinetik und Proteinkinetik nicht linear verbunden sind. Die bekannten Mechanismen wurden erweitert, indem gezeigt wurde, dass Proteinabbau eine wichtige Rolle in der aktiven Synchronisation von innerer und äußerer Zeit spielt, da sie sich systematisch veränderte als die Lichtzyklen systematisch verändert wurden. Die circadiane Forschung hatte ihren Schwerpunkt bisher auf Versuchen in konstanten Bedingungen. In der Zukunft wird „Entrainment“ (der aktive Synchronisationsprozess von äußerer Zeitinformationen und Zustand der inneren Uhr) in den Mittelpunkt der Forschung treten, um die Arbeit der Zahnräder der inneren Uhr besser zu verstehen. Mit dieser Doktorarbeit konnte gezeigt werden, dass ein einfacher Organismus wie Neurospora crassa sich aktiv mit Lichtzyklen synchronisiert anstatt nur auf sie zu reagieren, und das mit Charakteristika, die dem Verhalten von höheren Organismen entsprechen. Das zeigt den Nutzen von Neurospora crassa als Modellorganismus in der circadianen Forschung und ermöglicht systematischere “Entrainment”-Forschung in höheren Organismen

Electroencephalography in delirium assessment: a scoping review

Background Delirium is a common disorder affecting around 31% of patients in the intensive care unit (ICU). Delirium assessment scores such as the Confusion Assessment Method (CAM) are time-consuming, they cannot differentiate between different types of delirium and their etiologies, and they may have low sensitivities in the clinical setting. While today, electroencephalography (EEG) is increasingly being applied to delirious patients in the ICU, a lack of clear cut EEG signs, leads to inconsistent assessments. Methods We therefore conducted a scoping review on EEG findings in delirium. One thousand two hundred thirty-six articles identified through database search on PubMed and Embase were reviewed. Finally, 33 original articles were included in the synthesis. Results EEG seems to offer manifold possibilities in diagnosing delirium. All 33 studies showed a certain degree of qualitative or quantitative EEG alterations in delirium. Thus, normal routine (rEEG) and continuous EEG (cEEG) make presence of delirium very unlikely. All 33 studies used different research protocols to at least some extent. These include differences in time points, duration, conditions, and recording methods of EEG, as well as different patient populations, and diagnostic methods for delirium. Thus, a quantitative synthesis and common recommendations are so far elusive. Conclusion Future studies should compare the different methods of EEG recording and evaluation to identify robust parameters for everyday use. Evidence for quantitative bi-electrode delirium detection based on increased relative delta power and decreased beta power is growing and should be further pursued. Additionally, EEG studies on the evolution of a delirium including patient outcomes are needed

Color My World: Deterministic Tagging for Memory Safety

Hardware-assisted memory protection features are increasingly being deployed in COTS processors. ARMv8.5 Memory Tagging Extensions (MTE) is a recent example, which has been used to provide probabilistic checks for memory safety. This use of MTE is not secure against the standard adversary with arbitrary read/write access to memory. Consequently MTE is used as a software development tool. In this paper we present the first design for deterministic memory protection using MTE that can resist the standard adversary, and hence is suitable for post-deployment memory safety. We describe our compiler extensions for LLVM Clang implementing static analysis and subsequent MTE instrumentation. Via a comprehensive evaluation we show that our scheme is effective

Uncomplicated Pregnancy and Delivery after Previous Severe Postpartum Cerebral Angiopathy

Postpartum cerebral angiopathy (PCA) is a cerebral vasoconstriction syndrome developing shortly after delivery, without signs of preceding eclampsia. The risk for recurrence of PCA is unknown. Here, we report on a closely monitored, uneventful pregnancy of a woman with a previous severe episode of PCA. In summary, this case report demonstrates that PCA does not necessarily recur in following pregnancies, even after previous severe episodes

Geographical Requirements for the Applicability of the Results of the RACECAT Study to Other Stroke Networks

Prehospital stroke triage; Reperfusion therapyTriaje prehospitalario de ictus; Terapia de reperfusiónTriatge prehospitalari d'ictus; Teràpia de reperfusióBackground The RACECAT (Transfer to the Closest Local Stroke Center vs Direct Transfer to Endovascular Stroke Center of Acute Stroke Patients With Suspected Large Vessel Occlusion in the Catalan Territory) trial was the first randomized trial addressing the prehospital triage of acute stroke patients based on the distribution of thrombolysis centers and intervention centers in Catalonia, Spain. The study compared the drip‐and‐ship with the mothership paradigm in regions where a local thrombolysis center can be reached faster than the nearest intervention center (equipoise region). The present study aims to determine the population‐based applicability of the results of the RACECAT study to 4 stroke networks with a different degree of clustering of the intervention centers (clustered, dispersed). Methods and Results Stroke networks were compared with regard to transport time saved for thrombolysis (under the drip‐and‐ship approach) and transport time saved for endovascular therapy (under the mothership approach). Population‐based transport times were modeled with a local instance of an openrouteservice server using open data from OpenStreetMap.The fraction of the population in the equipoise region differed substantially between clustered networks (Catalonia, 63.4%; France North, 87.7%) and dispersed networks (Southwest Bavaria, 40.1%; Switzerland, 40.0%). Transport time savings for thrombolysis under the drip‐and‐ship approach were more marked in clustered networks (Catalonia, 29 minutes; France North, 27 minutes) than in dispersed networks (Southwest Bavaria and Switzerland, both 18 minutes). Conclusions Infrastructure differences between stroke networks may hamper the applicability of the results of the RACECAT study to other stroke networks with a different distribution of intervention centers. Stroke networks should assess the population densities and hospital type/distribution in the temporal domain before applying prehospital triage algorithms to their specific setting.M.G. has received grants from the Swiss Academy of Medical Sciences/Bangerter‐Rhyner‐Foundation, Swiss Stroke Society, and Mittelbauvereinigung der Universität Bern as well as a congress grant from Pfizer, not related to this project. J.G. reports being global co‐principal investigator of the STAR Study, NCT01327989; consultancy Medtronic; global co‐principal investigator of SWIFT DIRECT, NCT03192332; consultancy Medtronic; principal investigator: Stroke treatment goes personalized: Gaining added diagnostic yield by computer‐assisted treatment selection (the STRAY‐CATS project), Swiss National Funds 170 060. J.K. reports grants from the Swiss Academy of Medical Sciences/Bangerter Foundation, Swiss Stroke Society, and Clinical Trials Unit Bern during the conduct of the study. T.R.M. reports grants from the Swiss Academy of Medical Sciences/Bangerter Foundation, Swiss National Science Society, and Swiss Heart Foundation during the conduct of the study. U.F. reports research grants from Medtronic for the SWIFT DIRECT trial and BEYOND SWIFT registry, Swiss National Science Foundation, Swiss Heart Foundation; consulting fees from Medtronic, Stryker, and CSL Behring (fees paid to institution); membership of a Data Safety Monitoring Board for the IN EXTREMIS trial and TITAN trial and Portola (Alexion), advisory board (fees paid to institution); and vice presidency of the Swiss Neurological Society. The remaining authors have no disclosures to report