Human RAD51 rapidly forms intrinsically dynamic nucleoprotein filaments modulated by nucleotide binding state.

Formation of RAD51 filaments on single-stranded DNA is an essential event during homologous recombination, which is required for homology search, strand exchange and protection of replication forks. Formation of nucleoprotein filaments (NF) is required for development and genomic stability, and its failure is associated with developmental abnormalities and tumorigenesis. Here we describe the structure of the human RAD51 NFs and of its Walker box mutants using electron microscopy. Wild-type RAD51 filaments adopt an 'open' conformation when compared to a 'closed' structure formed by mutants, reflecting alterations in helical pitch. The kinetics of formation/disassembly of RAD51 filaments show rapid and high ssDNA coverage via low cooperativity binding of RAD51 units along the DNA. Subsequently, a series of isomerization or dissociation events mediated by nucleotide binding state creates intrinsically dynamic RAD51 NFs. Our findings highlight important a mechanistic divergence among recombinases from different organisms, in line with the diversity of biological mechanisms of HR initiation and quality control. These data reveal unexpected intrinsic dynamic properties of the RAD51 filament during assembly/disassembly, which may be important for the proper control of homologous recombination

The toposiomerase IIIalpha-RMI1-RMI2 complex orients human Bloom’s syndrome helicase for efficient disruption of D-loops

Homologous recombination (HR) is a ubiquitous and efficient process that serves the repair of severe forms of DNA damage and the generation of genetic diversity during meiosis. HR can proceed via multiple pathways with different outcomes that may aid or impair genome stability and faithful inheritance, underscoring the importance of HR quality control. Human Bloom’s syndrome (BLM, RecQ family) helicase plays central roles in HR pathway selection and quality control via unexplored molecular mechanisms. Here we show that BLM’s multi-domain structural architecture supports a balance between stabilization and disruption of displacement loops (D-loops), early HR intermediates that are key targets for HR regulation. We find that this balance is markedly shifted toward efficient D-loop disruption by the presence of BLM’s interaction partners Topoisomerase IIIα-RMI1-RMI2, which have been shown to be involved in multiple steps of HR-based DNA repair. Our results point to a mechanism whereby BLM can differentially process D-loops and support HR control depending on cellular regulatory mechanisms

Treatment of acute rhinitis with a nasal spray containing tramazoline and essential oils: a multicenter, uncontrolled, observational trial

BACKGROUND: In this observational trial, data were collected on the effectiveness and tolerability/safety of a nasal spray containing tramazoline and essential oils (trade name Rhinospray((R)) Plus) used for symptomatic treatment of acute rhinitis due to common cold. METHODS: The trial was performed in 300 children, adolescents and adults, who were to be treated with Rhinospray((R)) Plus for up to 4 times per day for up to 10 days. Primary endpoints were the change from baseline to final visit in the mean of three single symptom scores (blocked nose, sneezing, and runny nose) and the mean improvement in two quality-of-life parameters (ability to perform normal daytime activities and quality of sleep). RESULTS: A total of 108 children, 30 adolescents and 162 adults were treated with Rhinospray((R)) Plus. No patient discontinued prematurely. There was a mean reduction of 2.0 +/- 0.6 (standard deviation) in nasal symptom scores from baseline to final visit; 297 of 300 of patients (99.0 %) reported an improvement. The mean value for improvement in quality-of-life parameters was 1.3 +/- 0.5. Improvement in daytime activities was reported by all 300 patients (100.0 %) and in quality of sleep by 292 patients (97.4 %). Effectiveness and tolerability were rated as 'very good' or 'good' by 95.4 % and 97.4 % of patients, respectively; the investigators rated effectiveness and tolerability as 'very good' or 'good' for 97.4 % and 100.0 % of patients, respectively. No adverse events were reported. CONCLUSIONS: Community-based patients reported a relief in acute rhinitis symptoms and improvement in quality of life as a result of treatment with Rhinospray((R)) Plus. Treatment was well-tolerated

Discovery of novel gating checkpoints in the Orai1 calcium channel by systematic analysis of constitutively active mutants of its paralogs and orthologs.

In humans, there are three paralogs of the Orai Ca2+ channel that form the core of the store-operated calcium entry (SOCE) machinery. While the STIM-mediated gating mechanism of Orai channels is still under active investigation, several artificial and natural variants are known to cause constitutive activity of the human Orai1 channel. Surprisingly, little is known about the conservation of the gating checkpoints among the different human Orai paralogs and orthologs in other species. In our work, we show that the mutation corresponding to the activating mutation H134A in transmembrane helix 2 (TM2) of human Orai1 also activates Orai2 and Orai3, likely via a similar mechanism. However, this cross-paralog conservation does not apply to the "ANSGA" nexus mutations in TM4 of human Orai1, which is reported to mimic the STIM1-activated state of the channel. In investigating the mechanistic background of these differences, we identified two positions, H171 and F246 in human Orai1, that are not conserved among paralogs and that seem to be crucial for the channel activation triggered by the "ANSGA" mutations in Orai1. However, mutations of the same residues still allow gating of Orai1 by STIM1, suggesting that the ANSGA mutant of Orai1 may not be a surrogate for the STIM1-activated state of the Orai1 channel. Our results shed new light on these important gating checkpoints and show that the gating mechanism of Orai channels is affected by multiple factors that are not necessarily conserved among orai homologs, such as the TM4-TM3 coupling

Decompression of Multimorbidity Along the Disease Trajectories of Diabetes Mellitus Patients

Multimorbidity, the presence of two or more diseases in a patient, is maybe the greatest health challenge for the aging populations of many high-income countries. One of the main drivers of multimorbidity is diabetes mellitus (DM) due to its large number of risk factors and complications. Yet, we currently have very limited understanding of how to quantify multimorbidity beyond a simple counting of diseases and thereby inform prevention and intervention strategies tailored to the needs of elderly DM patients. Here, we conceptualize multimorbidity as typical temporal progression patterns of multiple diseases, so-called trajectories, and develop a framework to perform a matched and sex-specific comparison between DM and non-diabetic patients. We find that these disease trajectories can be organized into a multi-level hierarchy in which DM patients progress from relatively healthy states with low mortality to high-mortality states characterized by cardiovascular diseases, chronic lower respiratory diseases, renal failure, and different combinations thereof. The same disease trajectories can be observed in non-diabetic patients, however, we find that DM patients typically progress at much higher rates along their trajectories. Comparing male and female DM patients, we find a general tendency that females progress faster toward high multimorbidity states than males, in particular along trajectories that involve obesity. Males, on the other hand, appear to progress faster in trajectories that combine heart diseases with cerebrovascular diseases. Our results show that prevention and efficient management of DM are key to achieve a compression of morbidity into higher patient ages. Multidisciplinary efforts involving clinicians as well as experts in machine learning and data visualization are needed to better understand the identified disease trajectories and thereby contribute to solving the current multimorbidity crisis in healthcare

Systematic population-wide ecological analysis of regional variability in disease prevalence

The prevalence of diseases often varies substantially from region to region. Besides basic demographic properties, the factors that drive the variability of each prevalence are to a large extent unknown. Here we show how regional prevalence variations in 115 different diseases relate to demographic, socio-economic, environmental factors and migratory background, as well as access to different types of health services such as primary, specialized and hospital healthcare. We have collected regional data for these risk factors at different levels of resolution; from large regions of care (Versorgungsregion) down to a 250 by 250 m square grid. Using multivariate regression analysis, we quantify the explanatory power of each independent variable in relation to the regional variation of the disease prevalence. We find that for certain diseases, such as acute heart conditions, diseases of the inner ear, mental and behavioral disorders due to substance abuse, up to 80% of the variance can be explained with these risk factors. For other diagnostic blocks, such as blood related diseases, injuries and poisoning however, the explanatory power is close to zero. We find that the time needed to travel from the inhabited center to the relevant hospital ward often contributes significantly to the disease risk, in particular for diabetes mellitus. Our results show that variations in disease burden across different regions can for many diseases be related to variations in demographic and socio-economic factors. Furthermore, our results highlight the relative importance of access to health care facilities in the treatment of chronic diseases like diabetes