High-resolution Mapping bei komplexen Rhythmusstörungen

Der Gebrauch des neuen dreidimensionale Mappingsystem RhythmiaHDx© (Boston Scientific, Cambridge, MA, USA) ist bei jeder Prozedur, die von einem dreidimensionalem Navigationssystem profitiert, berechtigt. Dementsprechend ist Rhythmia in den täglichen Klinikalltag im elektrophysiologischen Labor am Klinikum in Großhadern integriert und wird für fast jede dreidimensionale Untersuchung bevorzugt eingesetzt. Die Durchführbarkeit und Sicherheit des Systems konnten bei der Anwendung von 400 Prozeduren bewiesen werden. Es konnte dargestellt werden, dass Anfangsschwierigkeiten bezüglich der Steuerung des Mappingkatheters mit etwas Routine überwunden werden können und eine enorm große Anzahl an Elektrogrammen aufgenommen werden können. Den größten Nutzen gegenüber etablierten Navigationssystemen verspricht Rhythmia in der Behandlung von komplexen linksatrialen Tachykardien, fokalen Tachykardien und ventrikulären Tachykardien. Durch eine höhere Auflösung von kleinamplitudigen Signalen und eine schnelle und automatische Aufnahme von Elektrogrammen ist die Mappingleistung deutlich erhöht. Dementsprechend resultiert aus einem besseren Verständnis des Arrhythmiemechanismus und einer sicheren Aufnahme von unstabilen und schnell wechselnden Rhythmusstörungen ein guter Primärerfolg. Die Stärken von Rhythmia in der Behandlung von komplexen Tachykardien gilt es in der Zukunft weiter zu nutzen. Die Anwendung bei der Behandlung von typischem Vorhofflattern, von AV-Knoten Reentrytachykardien und des Wolff-Parkinson-White Syndroms wird nur bei besonderen anatomischen Voraussetzungen vorbehalten bleiben. Trotz all dieser Verbesserungen und Vorteile konnten bei der initialen Verwendung von Rhythmia auch technische Limitierungen festgestellt werden. Die begrenzte Wendigkeit des Mappingkatheters erforderte bei linksventrikulärem Mapping aufgrund von unvollständigen Maps und nicht passierbaren Aortenklappen in manchen Fällen zusätzliche transseptale Zugänge. Des Weiteren schränkt das Magnetfeld von Rhythmia bei Patienten mit mechanischer Kreislaufunterstützung den Gebrauch auf eine extrakorporale Langzeitunterstützung (ECLS) oder eine intraaortale Ballonpumpe (IABP) ein. Die bisher limitiert vorliegenden Daten des Langzeiterfolgs sind mit dem von anderen Mappingsystemen und Prozeduren ohne ein Navigationssystem vergleichbar. Es sind weitere direkt mit anderen 3D-Systemen vergleichende Studien zur Analyse des Langzeiterfolgs erforderlich, die eine größere Anzahl an Patienten über einen größeren Zeitraum über die Ablation hinaus nach Rezidiven untersuchen

High-resolution Mapping bei komplexen Rhythmusstörungen

Der Gebrauch des neuen dreidimensionale Mappingsystem RhythmiaHDx© (Boston Scientific, Cambridge, MA, USA) ist bei jeder Prozedur, die von einem dreidimensionalem Navigationssystem profitiert, berechtigt. Dementsprechend ist Rhythmia in den täglichen Klinikalltag im elektrophysiologischen Labor am Klinikum in Großhadern integriert und wird für fast jede dreidimensionale Untersuchung bevorzugt eingesetzt. Die Durchführbarkeit und Sicherheit des Systems konnten bei der Anwendung von 400 Prozeduren bewiesen werden. Es konnte dargestellt werden, dass Anfangsschwierigkeiten bezüglich der Steuerung des Mappingkatheters mit etwas Routine überwunden werden können und eine enorm große Anzahl an Elektrogrammen aufgenommen werden können. Den größten Nutzen gegenüber etablierten Navigationssystemen verspricht Rhythmia in der Behandlung von komplexen linksatrialen Tachykardien, fokalen Tachykardien und ventrikulären Tachykardien. Durch eine höhere Auflösung von kleinamplitudigen Signalen und eine schnelle und automatische Aufnahme von Elektrogrammen ist die Mappingleistung deutlich erhöht. Dementsprechend resultiert aus einem besseren Verständnis des Arrhythmiemechanismus und einer sicheren Aufnahme von unstabilen und schnell wechselnden Rhythmusstörungen ein guter Primärerfolg. Die Stärken von Rhythmia in der Behandlung von komplexen Tachykardien gilt es in der Zukunft weiter zu nutzen. Die Anwendung bei der Behandlung von typischem Vorhofflattern, von AV-Knoten Reentrytachykardien und des Wolff-Parkinson-White Syndroms wird nur bei besonderen anatomischen Voraussetzungen vorbehalten bleiben. Trotz all dieser Verbesserungen und Vorteile konnten bei der initialen Verwendung von Rhythmia auch technische Limitierungen festgestellt werden. Die begrenzte Wendigkeit des Mappingkatheters erforderte bei linksventrikulärem Mapping aufgrund von unvollständigen Maps und nicht passierbaren Aortenklappen in manchen Fällen zusätzliche transseptale Zugänge. Des Weiteren schränkt das Magnetfeld von Rhythmia bei Patienten mit mechanischer Kreislaufunterstützung den Gebrauch auf eine extrakorporale Langzeitunterstützung (ECLS) oder eine intraaortale Ballonpumpe (IABP) ein. Die bisher limitiert vorliegenden Daten des Langzeiterfolgs sind mit dem von anderen Mappingsystemen und Prozeduren ohne ein Navigationssystem vergleichbar. Es sind weitere direkt mit anderen 3D-Systemen vergleichende Studien zur Analyse des Langzeiterfolgs erforderlich, die eine größere Anzahl an Patienten über einen größeren Zeitraum über die Ablation hinaus nach Rezidiven untersuchen

Treatment of insomnia in elderly patients

Introduction: Insomnia is one of the most common health conditions amongst the elderly population. It causes suffering and numerous health problems for those affected. Objectives: To review published results of common non-pharmacological and pharmacological interventions of insomnia and to discuss their application in older patient groups. Methods: We conducted a systematic literature review for the topic non-pharmacological treatment of Insomnia in Elderly and non-systematic review on the topic of pharmacological treatment using the electronic databases PubMed, PsycInfo, Google Scholar and Web of Knowledge. Only published articles and reviews were included. Results: Sleep education can support the onset of sleep. As a simple and side-effect-free measure, sleep education should be offered to all elderly individuals with sleep-onset insomnia including those living in retirement homes. Stimulus control means that the bed or the bedroom should only be visited, if there is sufficient tiredness, or left, when tiredness is not sufficient, which is very challenging and sometimes impossible due to the decreasing mobility of the elderly, especially under treatment with hypnotics. Sleep restriction can be conducted in a moderate way, reducing the time spent in bed every week for 30 minutes. Light therapy supports the regulation of the circadian body rhythm by exposing the patients to bright artificial light during the day. As a simple measure with only a few side effects, it is suitable when treating elderly individuals in institutions. Digital therapies are an emerging trend in the treatment of sleep disorders and require further empirical investigation of their effectiveness in the treatment of insomnia in the elderly. Non-pharmacological therapy should be the first-line therapy according to guidelines. Prescribing of sleep medication should take into account the period of time until the maximum effective level is reached, the half-life of the preparation, the binding behaviour to receptors and the metabolism of the preparation, which is especially relevant for elderly populations due to polypharmacy. Conclusion and implications: A modified, short cognitive behavioural therapy for insomnia combined with light therapy is the treatment of choice for elderly patients. However, a short-term pharmacological therapy is recommended as a temporary solution to immediately reduce high levels of distress. It is suggested to integrate both therapeutic approaches into a comprehensive therapeutic concept for insomnia in elderly people. Key words: Insomnia, cognitive behavioural therapy for insomnia, CBT-I, Hypnotics, light therapy, elderl

NAIL-MS reveals the repair of 2-methylthiocytidine by AlkB in E. coli

RNAs contain post-transcriptional modifications, which fulfill a variety of functions in translation, secondary structure stabilization and cellular stress survival. Here, 2-methylthiocytidine (ms(2)C) is identified in tRNA of E. coli and P. aeruginosa using NAIL-MS (nucleic acid isotope labeling coupled mass spectrometry) in combination with genetic screening experiments. ms(2)C is only found in 2-thiocytidine (s(2)C) containing tRNAs, namely tRNA(CCG)(Arg), tRNA(ICG)(Ar)(g), tRNA(UCU)(Arg) and tRNA(GCU)(Ser )at low abundances. ms(2)C is not formed by, commonly known tRNA methyltransferases. Instead, we observe its formation in vitro and in vivo during exposure to methylating agents. More than half of the s(2)C containing tRNA can be methylated to carry ms(2)C. With a pulse-chase NAIL-MS experiment, the repair mechanism by AlkB dependent sulfur demethylation is demonstrated in vivo. Overall, we describe ms(2)C as a bacterial tRNA modification and damage product. Its repair by AlkB and other pathways is demonstrated in vivo by our powerful NAIL-MS approach

Broadly applicable oligonucleotide mass spectrometry for the analysis of RNA writers and erasers in vitro.

RNAs are post-transcriptionally modified by dedicated writer or eraser enzymes that add or remove specific modifications, respectively. Mass spectrometry (MS) of RNA is a useful tool to study the modification state of an oligonucleotide (ON) in a sensitive manner. Here, we developed an ion-pairing reagent free chromatography for positive ion detection of ONs by low- and high-resolution MS, which does not interfere with other types of small compound analyses done on the same instrument. We apply ON-MS to determine the ONs from an RNase T1 digest of in vitro transcribed tRNA, which are purified after ribozyme-fusion transcription by automated size exclusion chromatography. The thus produced tRNAValAAC is substrate of the human tRNA ADAT2/3 enzyme and we confirm the deamination of adenosine to inosine and the formation of tRNAValIACin vitro by ON-MS. Furthermore, low resolution ON-MS is used to monitor the demethylation of ONs containing 1-methyladenosine by bacterial AlkB in vitro. The power of high-resolution ON-MS is demonstrated by the detection and mapping of modified ONs from native total tRNA digested with RNase T1. Overall, we present an oligonucleotide MS method which is broadly applicable to monitor in vitro RNA (de-)modification processes and native RNA

m5U54 tRNA hypomodification by lack of TRMT2A drives the generation of tRNA-derived small RNAs

Transfer RNA (tRNA) molecules contain various post-transcriptional modifications that are crucial for tRNA stability, translation efficiency, and fidelity. Besides their canonical roles in translation, tRNAs also originate tRNA-derived small RNAs (tsRNAs), a class of small non-coding RNAs with regulatory functions ranging from translation regulation to gene expression control and cellular stress response. Recent evidence indicates that tsRNAs are also modified, however, the impact of tRNA epitranscriptome deregulation on tsRNAs generation is only now beginning to be uncovered. The 5-methyluridine (m5U) modification at position 54 of cytosolic tRNAs is one of the most common and conserved tRNA modifications among species. The tRNA methyltransferase TRMT2A catalyzes this modification, but its biological role remains mostly unexplored. Here, we show that TRMT2A knockdown in human cells induces m5U54 tRNA hypomodification and tsRNA formation. More specifically, m5U54 hypomodification is followed by overexpression of the ribonuclease angiogenin (ANG) that cleaves tRNAs near the anticodon, resulting in accumulation of 5′tRNA-derived stress-induced RNAs (5′tiRNAs), namely 5′tiRNA-GlyGCC and 5′tiRNA-GluCTC, among others. Additionally, transcriptomic analysis confirms that down-regulation of TRMT2A and consequently m5U54 hypomodification impacts the cellular stress response and RNA stability, which is often correlated with tiRNA generation. Accordingly, exposure to oxidative stress conditions induces TRMT2A down-regulation and tiRNA formation in mammalian cells. These results establish a link between tRNA hypomethylation and ANG-dependent tsRNAs formation and unravel m5U54 as a tRNA cleavage protective mark.publishe

Related haloarchaeal pleomorphic viruses contain different genome types

Peer reviewe

Production and application of stable isotope-labeled internal standards for RNA modification analysis

Post-transcriptional RNA modifications have been found to be present in a wide variety of organisms and in different types of RNA. Nucleoside modifications are interesting due to their already known roles in translation fidelity, enzyme recognition, disease progression, and RNA stability. In addition, the abundance of modified nucleosides fluctuates based on growth phase, external stress, or possibly other factors not yet explored. With modifications ever changing, a method to determine absolute quantities for multiple nucleoside modifications is required. Here, we report metabolic isotope labeling to produce isotopically labeled internal standards in bacteria and yeast. These can be used for the quantification of 26 different modified nucleosides. We explain in detail how these internal standards are produced and show their mass spectrometric characterization. We apply our internal standards and quantify the modification content of transfer RNA (tRNA) from bacteria and various eukaryotes. We can show that the origin of the internal standard has no impact on the quantification result. Furthermore, we use our internal standard for the quantification of modified nucleosides in mouse tissue messenger RNA (mRNA), where we find different modification profiles in liver and brain tissue

Synthesis of Galactosyl‐Queuosine and Distribution of Hypermodified Q‐Nucleosides in Mouse Tissues

Queuosine (Q) is a hypermodified RNA nucleoside that is found in tRNAHis, tRNAAsn, tRNATyr, and tRNAAsp. It is located at the wobble position of the tRNA anticodon loop, where it can interact with U as well as C bases located at the respective position of the corresponding mRNA codons. In tRNATyr and tRNAAsp of higher eukaryotes, including humans, the Q base is for yet unknown reasons further modified by the addition of a galactose and a mannose sugar, respectively. The reason for this additional modification, and how the sugar modification is orchestrated with Q formation and insertion, is unknown. Here, we report a total synthesis of the hypermodified nucleoside galactosyl‐queuosine (galQ). The availability of the compound enabled us to study the absolute levels of the Q‐family nucleosides in six different organs of newborn and adult mice, and also in human cytosolic tRNA. Our synthesis now paves the way to a more detailed analysis of the biological function of the Q‐nucleoside family

Sequence- and structure-specific cytosine-5 mRNA methylation by NSUN6.

The highly abundant N6-methyladenosine (m6A) RNA modification affects most aspects of mRNA function, yet the precise function of the rarer 5-methylcytidine (m5C) remains largely unknown. Here, we map m5C in the human transcriptome using methylation-dependent individual-nucleotide resolution cross-linking and immunoprecipitation (miCLIP) combined with RNA bisulfite sequencing. We identify NSUN6 as a methyltransferase with strong substrate specificity towards mRNA. NSUN6 primarily targeted three prime untranslated regions (3'UTR) at the consensus sequence motif CTCCA, located in loops of hairpin structures. Knockout and rescue experiments revealed enhanced mRNA and translation levels when NSUN6-targeted mRNAs were methylated. Ribosome profiling further demonstrated that NSUN6-specific methylation correlated with translation termination. While NSUN6 was dispensable for mouse embryonic development, it was down-regulated in human tumours and high expression of NSUN6 indicated better patient outcome of certain cancer types. In summary, our study identifies NSUN6 as a methyltransferase targeting mRNA, potentially as part of a quality control mechanism involved in translation termination fidelity