Atomic Mutagenesis of N6-Methyladenosine Reveals Distinct Recognition Modes by Human m6A Reader and Eraser Proteins.

N6-methyladenosine (m6A) is an important modified nucleoside in cellular RNA associated with multiple cellular processes and is implicated in diseases. The enzymes associated with the dynamic installation and removal of m6A are heavily investigated targets for drug research, which requires detailed knowledge of the recognition modes of m6A by proteins. Here, we use atomic mutagenesis of m6A to systematically investigate the mechanisms of the two human m6A demethylase enzymes FTO and ALKBH5 and the binding modes of YTH reader proteins YTHDF2/DC1/DC2. Atomic mutagenesis refers to atom-specific changes that are introduced by chemical synthesis, such as the replacement of nitrogen by carbon atoms. Synthetic RNA oligonucleotides containing site-specifically incorporated 1-deaza-, 3-deaza-, and 7-deaza-m6A nucleosides were prepared by solid-phase synthesis and their RNA binding and demethylation by recombinant proteins were evaluated. We found distinct differences in substrate recognition and transformation and revealed structural preferences for the enzymatic activity. The deaza m6A analogues introduced in this work will be useful probes for other proteins in m6A research.

A SAM analogue-utilizing ribozyme for site-specific RNA alkylation in living cells.

Post-transcriptional RNA modification methods are in high demand for site-specific RNA labelling and analysis of RNA functions. In vitro-selected ribozymes are attractive tools for RNA research and have the potential to overcome some of the limitations of chemoenzymatic approaches with repurposed methyltransferases. Here we report an alkyltransferase ribozyme that uses a synthetic, stabilized S-adenosylmethionine (SAM) analogue and catalyses the transfer of a propargyl group to a specific adenosine in the target RNA. Almost quantitative conversion was achieved within 1 h under a wide range of reaction conditions in vitro, including physiological magnesium ion concentrations. A genetically encoded version of the SAM analogue-utilizing ribozyme (SAMURI) was expressed in HEK293T cells, and intracellular propargylation of the target adenosine was confirmed by specific fluorescent labelling. SAMURI is a general tool for the site-specific installation of the smallest tag for azide-alkyne click chemistry, which can be further functionalized with fluorophores, affinity tags or other functional probes.

ICESat-2 river surface slope (IRIS): A global reach-scale water surface slope dataset.

The global reach-scale "ICESat-2 River Surface Slope" (IRIS) dataset comprises average and extreme water surface slopes (WSS) derived from ICESat-2 observations between October 2018 and August 2022 as a supplement to 121,583 reaches from the "SWOT Mission River Database" (SWORD). To gain full advantage of ICESat-2's unique measurement geometry with six parallel lidar beams, the WSS is determined across pairs of beams or along individual beams, depending on the intersection angle of spacecraft orbit and river centerline. Combining both approaches maximizes spatial and temporal coverage. IRIS can be used to research river dynamics, estimate river discharge, and correct water level time series from satellite altimetry for shifting ground tracks. Additionally, by referencing SWORD as a common database, IRIS may be used in combination with observations from the recently launched SWOT mission.

Testing three coping strategies for time pressure in categorizations and similarity judgments.

This article compares three psychological mechanisms to make multi-attribute inferences under time pressure in the domains of categorization and similarity judgments. Specifically, we test if people under time pressure attend to fewer object features (attention focus), if they respond less precisely (lower choice sensitivity), or if they simplify a psychological similarity function (simplified similarity). The simpler psychological similarity considers the number of matching features but ignores the actual feature value differences. We conducted three experiments (two of them preregistered) in which we manipulated time pressure: one was a categorization task, which was designed based on optimal experimental design principles, and the other two involved a similarity judgment task. Computational cognitive modeling following an exemplar-similarity framework showed that the behavior of most participants under time pressure is in line with a lower choice sensitivity, this means less precise response selection, especially when people make similarity judgments. We find that the variability of participants' behavior increases with time pressure, to a point where participants are unlikely to make inferences anymore but instead start choosing readily available response options repeatedly. These findings are consistent with related research in other cognitive domains, such as risky choices, and add to growing evidence that time pressure and other forms of cognitive load do not necessarily alter core cognitive processes themselves but rather affect the precision of response selection.

Global coastal attenuation of wind-waves observed with radar altimetry.

Coastal studies of wave climate and evaluations of wave energy resources are mainly regional and based on the use of computationally very expensive models or a network of in-situ data. Considering the significant wave height, satellite radar altimetry provides an established global and relatively long-term source, whose coastal data are nevertheless typically flagged as unreliable within 30 km of the coast. This study exploits the reprocessing of the radar altimetry signals with a dedicated fitting algorithm to retrieve several years of significant wave height records in the coastal zone. We show significant variations in annual cycle amplitudes and mean state in the last 30 km from the coastline compared to offshore, in areas that were up to now not observable with standard radar altimetry. Consequently, a decrease in the average wave energy flux is observed. Globally, we found that the mean significant wave height at 3 km off the coast is on average 22% smaller than offshore, the amplitude of the annual cycle is reduced on average by 14% and the mean energy flux loses 38% of its offshore value.

Mechanism of SARS-CoV-2 polymerase stalling by remdesivir.

Remdesivir is the only FDA-approved drug for the treatment of COVID-19 patients. The active form of remdesivir acts as a nucleoside analog and inhibits the RNA-dependent RNA polymerase (RdRp) of coronaviruses including SARS-CoV-2. Remdesivir is incorporated by the RdRp into the growing RNA product and allows for addition of three more nucleotides before RNA synthesis stalls. Here we use synthetic RNA chemistry, biochemistry and cryo-electron microscopy to establish the molecular mechanism of remdesivir-induced RdRp stalling. We show that addition of the fourth nucleotide following remdesivir incorporation into the RNA product is impaired by a barrier to further RNA translocation. This translocation barrier causes retention of the RNA 3'-nucleotide in the substrate-binding site of the RdRp and interferes with entry of the next nucleoside triphosphate, thereby stalling RdRp. In the structure of the remdesivir-stalled state, the 3'-nucleotide of the RNA product is matched and located with the template base in the active center, and this may impair proofreading by the viral 3'-exonuclease. These mechanistic insights should facilitate the quest for improved antivirals that target coronavirus replication.

[Without Net and Double Floor: Comparison of Umbilical Hernia Repair by Spitzy in Children and Adults]. / Ohne Netz und doppelten Boden: Vergleich der Nabelherniotomie nach Spitzy im Kindes- und Erwachsenenalter.

Umbilical hernia occur in both adults and children. For over 100 years, umbilical hernia in children has been treated surgically by the Spitzy method. With adult patients, meshes are being increasingly used. The purpose of our study was to analyse Spitzy herniotomy with respect to the recurrence rate in children and adults. MATERIAL AND METHODS: Over a period of 7 years, 383 children (age < 16 years) with umbilical hernia were treated surgically; after applying the exclusion criteria, 370 patients were evaluated. At the same time, 106 adult patients (age > 16 years) were operated for an umbilical hernia: 31 patients were treated with direct suture and thus are included in our study as comparison group. RESULTS: The young patients had an average age of 33.81 months and were 44% female and 56% male. After direct Spitzy suture, a low recurrence rate of 1.1% (n = 4) in infancy could be achieved. The average age of the adult patients was 54.55 years; 32% were female, 68% male. In comparison to the group of children, the recurrence rate in adult surgery was 12.9% (n = 4) after direct suture. CONCLUSION: As confirmed in our study, umbilical herniotomy by direct suture in childhood has been the method of choice and gold standard for more than 100 years. Mesh implantation is still not necessary in childhood.

[Unusual Case of a a Severely Injured Toddler - Pre- and Early Hospital Treatment and Happy End Despite Obstacles]. / Ungewöhnlicher Fall eines schweren Polytraumas beim Kleinkind ­ Happy End trotz Fallstricken.

A 16-month-old boy suffers a massive trauma (open dislocated pelvic fracture and decollement with haemorrhagic shock) due to a traffic accident. We present the characteristics and obstacles in the prehospital and early hospital emergency care of this severe and rare trauma in a pediatric patient with an emphasis on medical-operational tactics.

Frequency of blood pressure and estimated glomerular filtration rate monitoring in patients affected by hypertension: a retrospective study with 176 565 patients in Germany.

OBJECTIVE: The aim of this study was to analyze the frequency of blood pressure (BP) and estimated glomerular filtration rate (eGFR) monitoring in hypertension patients followed in primary care practices in Germany. PATIENTS AND METHODS: This study included patients who had received at least two hypertension diagnoses (ICD-10: I10) in 2016. The primary outcome of this study was the frequency of BP and eGFR monitoring in patients with hypertension in the year 2016. The impact of the different demographic and clinical variables on the likelihood of receiving at least two BP and at least one eGFR tests was analyzed using multivariate logistic regression models. These two cutoff values were selected on the basis of the recommendations of the European Society of Hypertension and the European Society of Cardiology. RESULTS: This study included 176 565 patients, 53.0% of whom were women. The mean age was 68.2 years (SD=13.3 years). The mean number of BP tests was 1.9 (SD=3.1), whereas the mean number of eGFR tests was 0.2 (SD=0.8) in 2016. Only 33.7 and 9.1% of the population received at least two BP tests and one eGFR test, respectively. Older age (>60 years), comorbidities (particularly diabetes, hyperlipidemia, and renal insufficiency), and the number of antihypertensive treatments were associated with higher odds of receiving at least two BP and at least one eGFR tests, whereas the duration of hypertension was associated negatively with these odds. CONCLUSION: The frequency of BP and eGFR monitoring was low in Germany in 2016. Several demographic and clinical variables had a significant impact on this frequency.

Intravenous immunoglobulin maintenance treatment in myasthenia gravis: a randomized, controlled trial sample size simulation.

INTRODUCTION: In cases of exacerbation or crisis, myasthenia gravis (MG) patients can be treated with intravenous immunoglobulin (IVIg), plasmapheresis, or immunoadsorption. However, IVIg efficacy data in maintenance treatment are sparse. METHODS: We prospectively observed 16 index patients with chronic and insufficiently controlled MG under standard immunosuppressant therapy and symptomatic treatment. The IVIg treatment response was measured using changes in quantitative myasthenia gravis (QMG) score and surrogates. Based on these results, a sample size calculation for a future randomized, controlled trial (RCT) was simulated. RESULTS: There was an enduring decline in QMG score and other parameters of about 50% under IVIg maintenance treatment. RCT sample size calculation results in 73 or 33 patients per arm to detect at least a 20% vs. 30% clinical difference in QMG score. CONCLUSION: We recommend using the QMG score as a primary endpoint for an RCT of IVIg maintenance for chronic MG.

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state.

The uptake of nanoparticles into cells often involves their engulfment by the plasma membrane and a fission of the latter. Understanding the physical mechanisms underlying these uptake processes may be achieved by the investigation of simple model systems that can be compared to theoretical models. Here, we present experiments on a massive uptake of silica nanoparticles by giant unilamellar lipid vesicles (GUVs). We find that this uptake process depends on the size of the particles as well as on the thermodynamic state of the lipid membrane. Our findings are discussed in the light of several theoretical models and indicate that these models have to be extended in order to capture the interaction between nanomaterials and biological membranes correctly.

Fingolimod reduces recurrence of disease activity after natalizumab withdrawal in multiple sclerosis.

After discontinuation of natalizumab (NAT), multiple sclerosis (MS) disease activity often recurs. We assessed the recurrence of clinical disease activity during the first year after switching from NAT to fingolimod (FTY) in patients with relapsing-remitting MS. The number of relapses and the annualized relapse rate (ARR) before, during and after NAT discontinuation were determined and compared between 26 MS patients who switched to FTY within 24 weeks, and 10 MS patients who remained without disease modifying therapy (therapy free group = TFG). Median follow-up post-NAT discontinuation was 55.1 weeks. In a subgroup (n = 20), the occurrence of contrast-enhancing-lesions (Gd+) on magnetic resonance imaging (MRI) was determined. Eleven patients (42 %) in the FTY group and seven patients (70 %) in the TFG had one or more relapses after cessation of NAT during follow-up (p < 0.05). One of the 11 (9 %) patients in the FTY group and 6/9 (67 %) patients in the TFG showed Gd+ lesions during follow-up (p < 0.05). Patients who switched to FTY ≤ 12 weeks after NAT discontinuation (n = 9) showed a trend for a lower post-NAT ARR compared to patients who started FTY therapy >12 weeks after NAT was stopped (n = 17). Most relapses in the FTY group occurred just before or within 8 weeks after starting FTY. Our observation suggests that initiation of FTY treatment after NAT discontinuation reduces the recurrence of disease activity compared to withdrawal without further immunomodulatory treatment. In the FTY group the ARR tended to depend on the time interval between discontinuation of NAT and initiation of FTY.

Sibling disability risk at onset and during disease progression in familial multiple sclerosis.

BACKGROUND: The objective of this study was to address the differences in onset and disease progression between familial and sporadic multiple sclerosis (MS) and the association within sibling pairs. METHODS: Ninety-eight siblings and their controls were included from a database of 763 sporadic MS-patients, randomly pair-matched for age, gender, clinical course, disease duration and treatment. Sixty-eight available siblings completed a prospective six-year follow-up. Outcome parameters included baseline Expanded Disability Status Scale (EDSS), age at onset, mono- or multifocal onset, disease progression and conversion to secondary progression of initially relapsing-remitting MS. For statistical analyses Wilcoxon's signed-rank statistics for categorical differences, t-statistics for continuous variables, McNemar's test for relative frequencies of categories, intra-class correlations for within sibling-pair associations, or Kaplan-Meier analysis for survival analyses were used; all two-sided at the 5% level. RESULTS: Disease onset was slightly earlier (29.01 vs. 29.44 years, p = 0.0492) and multifocal onset significantly more often (p = 0.0052) in familial than in sporadic MS. Notably, a substantial within sibling-pair correlation for disease progression (rho = 0.40; p = 0.0062) as well as a higher risk for siblings than for controls to convert into secondary progression (0.545 vs. 0.227; p = 0.018) could be observed. CONCLUSIONS: Familial MS differs from sporadic cases with respect to age at onset, multifocal involvement as first clinical event, and conversion into secondary progression. The progression rate of one out of two affected siblings may act as a predictor for the other sib.

Immunization as treatment for Parkinson's disease.

Parkinson's disease and other neurodegenerative disorders share a common pathologic pathway with aggregation and deposition of misfolded proteins causing a disruption of particular neuronal networks. Several mechanisms have been implicated in the downstream events following deposition of misfolded proteins including free radical formation and failure of cellular defences such as autophagy or protein-degradation by the ubiquitin-proteasome pathway among many others. Treatments, however, capable of arresting or at least effectively modifying the course of disease do not yet exist. Recently, immunization approaches including passive and active immunization have been tested in animal models of various neurodegenerative disorders and have already entered into clinical trials for the treatment of Alzheimer's disease. In this review, we specifically focus on the current status of immune-based approaches that are presently developed as a potential therapy of Parkinson's disease.