Stress-dependent condensate formation regulated by the ubiquitin-related modifier Urm1.

The ability of proteins and RNA to coalesce into phase-separated assemblies, such as the nucleolus and stress granules, is a basic principle in organizing membraneless cellular compartments. While the constituents of biomolecular condensates are generally well documented, the mechanisms underlying their formation under stress are only partially understood. Here, we show in yeast that covalent modification with the ubiquitin-like modifier Urm1 promotes the phase separation of a wide range of proteins. We find that the drop in cellular pH induced by stress triggers Urm1 self-association and its interaction with both target proteins and the Urm1-conjugating enzyme Uba4. Urmylation of stress-sensitive proteins promotes their deposition into stress granules and nuclear condensates. Yeast cells lacking Urm1 exhibit condensate defects that manifest in reduced stress resilience. We propose that Urm1 acts as a reversible molecular "adhesive" to drive protective phase separation of functionally critical proteins under cellular stress.

Mechanisms of readthrough mitigation reveal principles of GCN1-mediated translational quality control.

Readthrough into the 3' untranslated region (3' UTR) of the mRNA results in the production of aberrant proteins. Metazoans efficiently clear readthrough proteins, but the underlying mechanisms remain unknown. Here, we show in Caenorhabditis elegans and mammalian cells that readthrough proteins are targeted by a coupled, two-level quality control pathway involving the BAG6 chaperone complex and the ribosome-collision-sensing protein GCN1. Readthrough proteins with hydrophobic C-terminal extensions (CTEs) are recognized by SGTA-BAG6 and ubiquitylated by RNF126 for proteasomal degradation. Additionally, cotranslational mRNA decay initiated by GCN1 and CCR4/NOT limits the accumulation of readthrough products. Unexpectedly, selective ribosome profiling uncovered a general role of GCN1 in regulating translation dynamics when ribosomes collide at nonoptimal codons, enriched in 3' UTRs, transmembrane proteins, and collagens. GCN1 dysfunction increasingly perturbs these protein classes during aging, resulting in mRNA and proteome imbalance. Our results define GCN1 as a key factor acting during translation in maintaining protein homeostasis.

SARS-CoV-2 variants B.1.351 and P.1 escape from neutralizing antibodies.

The global spread of SARS-CoV-2/COVID-19 is devastating health systems and economies worldwide. Recombinant or vaccine-induced neutralizing antibodies are used to combat the COVID-19 pandemic. However, the recently emerged SARS-CoV-2 variants B.1.1.7 (UK), B.1.351 (South Africa), and P.1 (Brazil) harbor mutations in the viral spike (S) protein that may alter virus-host cell interactions and confer resistance to inhibitors and antibodies. Here, using pseudoparticles, we show that entry of all variants into human cells is susceptible to blockade by the entry inhibitors soluble ACE2, Camostat, EK-1, and EK-1-C4. In contrast, entry of the B.1.351 and P.1 variant was partially (Casirivimab) or fully (Bamlanivimab) resistant to antibodies used for COVID-19 treatment. Moreover, entry of these variants was less efficiently inhibited by plasma from convalescent COVID-19 patients and sera from BNT162b2-vaccinated individuals. These results suggest that SARS-CoV-2 may escape neutralizing antibody responses, which has important implications for efforts to contain the pandemic.

Antibodies and complement are key drivers of thrombosis.

Venous thromboembolism (VTE) is a common, deadly disease with an increasing incidence despite preventive efforts. Clinical observations have associated elevated antibody concentrations or antibody-based therapies with thrombotic events. However, how antibodies contribute to thrombosis is unknown. Here, we show that reduced blood flow enabled immunoglobulin M (IgM) to bind to FcµR and the polymeric immunoglobulin receptor (pIgR), initiating endothelial activation and platelet recruitment. Subsequently, the procoagulant surface of activated platelets accommodated antigen- and FcγR-independent IgG deposition. This leads to classical complement activation, setting in motion a prothrombotic vicious circle. Key elements of this mechanism were present in humans in the setting of venous stasis as well as in the dysregulated immunothrombosis of COVID-19. This antibody-driven thrombosis can be prevented by pharmacologically targeting complement. Hence, our results uncover antibodies as previously unrecognized central regulators of thrombosis. These findings carry relevance for therapeutic application of antibodies and open innovative avenues to target thrombosis without compromising hemostasis.

The evolutionarily conserved kinase SnRK1 orchestrates resource mobilization during Arabidopsis seedling establishment.

The onset of plant life is characterized by a major phase transition. During early heterotrophic seedling establishment, seed storage reserves fuel metabolic demands, allowing the plant to switch to autotrophic metabolism. Although metabolic pathways leading to storage compound mobilization are well-described, the regulatory circuits remain largely unresolved. Using an inducible knockdown approach of the evolutionarily conserved energy master regulator Snf1-RELATED-PROTEIN-KINASE1 (SnRK1), phenotypic studies reveal its crucial function in Arabidopsis thaliana seedling establishment. Importantly, glucose feeding largely restores growth defects of the kinase mutant, supporting its major impact in resource mobilization. Detailed metabolite studies reveal sucrose as a primary resource early in seedling establishment, in a SnRK1-independent manner. Later, SnRK1 orchestrates catabolism of triacylglycerols and amino acids. Concurrent transcriptomic studies highlight SnRK1 functions in controlling metabolic hubs fuelling gluconeogenesis, as exemplified by cytosolic PYRUVATE ORTHOPHOSPHATE DIKINASE (cyPPDK). Here, SnRK1 establishes its function via phosphorylation of the transcription factor BASIC LEUCINE ZIPPER63 (bZIP63), which directly targets and activates the cyPPDK promoter. Taken together, our results disclose developmental and catabolic functions of SnRK1 in seed storage mobilization and describe a prototypic gene regulatory mechanism. As seedling establishment is important for plant vigor and crop yield, our findings are of agronomical importance.

ORF3c is expressed in SARS-CoV-2-infected cells and inhibits innate sensing by targeting MAVS.

Most SARS-CoV-2 proteins are translated from subgenomic RNAs (sgRNAs). While the majority of these sgRNAs are monocistronic, some viral mRNAs encode more than one protein. One example is the ORF3a sgRNA that also encodes ORF3c, an enigmatic 41-amino-acid peptide. Here, we show that ORF3c is expressed in SARS-CoV-2-infected cells and suppresses RIG-I- and MDA5-mediated IFN-ß induction. ORF3c interacts with the signaling adaptor MAVS, induces its C-terminal cleavage, and inhibits the interaction of RIG-I with MAVS. The immunosuppressive activity of ORF3c is conserved among members of the subgenus sarbecovirus, including SARS-CoV and coronaviruses isolated from bats. Notably, however, the SARS-CoV-2 delta and kappa variants harbor premature stop codons in ORF3c, demonstrating that this reading frame is not essential for efficient viral replication in vivo and is likely compensated by other viral proteins. In agreement with this, disruption of ORF3c does not significantly affect SARS-CoV-2 replication in CaCo-2, CaLu-3, or Rhinolophus alcyone cells. In summary, we here identify ORF3c as an immune evasion factor of SARS-CoV-2 that suppresses innate sensing in infected cells.

Rapid homeostatic modulation of transsynaptic nanocolumn rings.

Robust neural information transfer relies on a delicate molecular nano-architecture of chemical synapses. Neurotransmitter release is controlled by a specific arrangement of proteins within presynaptic active zones. How the specific presynaptic molecular architecture relates to postsynaptic organization and how synaptic nano-architecture is transsynaptically regulated to enable stable synaptic transmission remain enigmatic. Using time-gated stimulated emission-depletion microscopy at the Drosophila neuromuscular junction, we found that presynaptic nanorings formed by the active-zone scaffold Bruchpilot (Brp) align with postsynaptic glutamate receptor (GluR) rings. Individual rings harbor approximately four transsynaptically aligned Brp-GluR nanocolumns. Similar nanocolumn rings are formed by the presynaptic protein Unc13A and GluRs. Intriguingly, acute GluR impairment triggers transsynaptic nanocolumn formation on the minute timescale during homeostatic plasticity. We reveal distinct phases of structural transsynaptic homeostatic plasticity, with postsynaptic GluR reorganization preceding presynaptic Brp modulation. Finally, homeostatic control of transsynaptic nano-architecture and neurotransmitter release requires the auxiliary GluR subunit Neto. Thus, transsynaptic nanocolumn rings provide a substrate for rapid homeostatic stabilization of synaptic efficacy.

Presynaptic quantal size enhancement counteracts post-tetanic release depression.

Repetitive synaptic stimulation can induce different forms of synaptic plasticity but may also limit the robustness of synaptic transmission by exhausting key resources. Little is known about how synaptic transmission is stabilized after high-frequency stimulation. In the present study, we observed that tetanic stimulation of the Drosophila neuromuscular junction (NMJ) decreases quantal content, release-ready vesicle pool size and synaptic vesicle density for minutes after stimulation. This was accompanied by a pronounced increase in quantal size. Interestingly, action potential-evoked synaptic transmission remained largely unchanged. EPSC amplitude fluctuation analysis confirmed the post-tetanic increase in quantal size and the decrease in quantal content, suggesting that the quantal size increase counteracts release depression to maintain evoked transmission. The magnitude of the post-tetanic quantal size increase and release depression correlated with stimulation frequency and duration, indicating activity-dependent stabilization of synaptic transmission. The post-tetanic quantal size increase persisted after genetic ablation of the glutamate receptor subunits GluRIIA or GluRIIB, and glutamate receptor calcium permeability, as well as blockade of postsynaptic calcium channels. By contrast, it was strongly attenuated by pharmacological or presynaptic genetic perturbation of the GTPase dynamin. Similar observations were made after inhibition of the H+-ATPase, suggesting that the quantal size increase is presynaptically driven. Additionally, dynamin and H+-ATPase perturbation resulted in a post-tetanic decrease in evoked amplitudes. Finally, we observed an increase in synaptic vesicle diameter after tetanic stimulation. Thus, a presynaptically-driven quantal size increase, likely mediated by larger synaptic vesicles, counterbalances post-tetanic release depression, thereby conferring robustness to synaptic transmission on the minute time scale. KEY POINTS: Many synapses transmit robustly after sustained activity despite the limitation of key resources, such as release-ready synaptic vesicles. We report robust synaptic transmission after sustained high-frequency stimulation of the Drosophila neuromuscular junction despite a reduction in release-ready vesicle number. An increased postsynaptic response to individual vesicles, likely driven by an increase in vesicle size due to endocytosis defects, stabilizes synaptic efficacy for minutes after sustained activity. Our study provides novel insights into the mechanisms governing synaptic stability after sustained neural activity.

Plasma-Engineering of Oxygen Vacancies on NiCo2O4 Nanowires with Enhanced Bifunctional Electrocatalytic Performance for Rechargeable Zinc-air Battery.

Designing an efficient, durable, and inexpensive bifunctional electrocatalyst toward oxygen evolution reactions (OER) and oxygen reduction reactions (ORR) remains a significant challenge for the development of rechargeable zinc-air batteries (ZABs). The generation of oxygen vacancies plays a vital role in modifying the surface properties of transition-metal-oxides (TMOs) and thus optimizing their electrocatalytic performances. Herein, a H2/Ar plasma is employed to generate abundant oxygen vacancies at the surfaces of NiCo2O4 nanowires. Compared with the Ar plasma, the H2/Ar plasma generated more oxygen vacancies at the catalyst surface owing to the synergic effect of the Ar-related ions and H-radicals in the plasma. As a result, the NiCo2O4 catalyst treated for 7.5 min in H2/Ar plasma exhibited the best bifunctional electrocatalytic activities and its gap potential between Ej = 10 for OER and E1/2 for ORR is even smaller than that of the noble-metal-based catalyst. In situ electrochemical experiments are also conducted to reveal the proposed mechanisms for the enhanced electrocatalytic performance. The rechargeable ZABs, when equipped with cathodes utilizing the aforementioned catalyst, achieved an outstanding charge-discharge gap, as well as superior cycling stability, outperforming batteries employing noble-metal catalyst counterparts.

Interface and Morphology Engineered Amorphous Si for Ultrafast Electrochemical Lithium Storage.

Ultrafast high-capacity lithium-ion batteries are extremely desirable for portable electronic devices, where Si is the most promising alternative to the conventional graphite anode due to its very high theoretical capacity. However, the low electronic conductivity and poor Li-diffusivity limit its rate capability. Moreover, high volume expansion/contraction upon Li-intake/uptake causes severe pulverization of the electrode, leading to drastic capacity fading. Here, interface and morphology-engineered amorphous Si matrix is being reported utilizing a few-layer vertical graphene (VG) buffer layer to retain high capacity at both slow and fast (dis)charging rates. The flexible mechanical support of VG due to the van-der-Waals interaction between the graphene layers, the weak adhesion between Si and graphene, and the highly porous geometry mitigated stress, while the three-dimensional mass loading enhanced specific capacity. Additionally, the high electronic conductivity of VG boosted rate-capability, resulting in a reversible gravimetric capacity of ≈1270 mAh g-1 (areal capacity of ≈37 µAh cm-2) even after 100 cycles at an ultrafast cycling rate of 20C, which provides a fascinating way for conductivity and stress management to obtain high-performance storage devices.

Efficient sampling-based Bayesian Active Learning for synaptic characterization.

Bayesian Active Learning (BAL) is an efficient framework for learning the parameters of a model, in which input stimuli are selected to maximize the mutual information between the observations and the unknown parameters. However, the applicability of BAL to experiments is limited as it requires performing high-dimensional integrations and optimizations in real time. Current methods are either too time consuming, or only applicable to specific models. Here, we propose an Efficient Sampling-Based Bayesian Active Learning (ESB-BAL) framework, which is efficient enough to be used in real-time biological experiments. We apply our method to the problem of estimating the parameters of a chemical synapse from the postsynaptic responses to evoked presynaptic action potentials. Using synthetic data and synaptic whole-cell patch-clamp recordings, we show that our method can improve the precision of model-based inferences, thereby paving the way towards more systematic and efficient experimental designs in physiology.

Sex differences in early experience and the development of aggression in wild chimpanzees.

Sex differences in physical aggression occur across human cultures and are thought to be influenced by active sex role reinforcement. However, sex differences in aggression also exist in our close evolutionary relatives, chimpanzees, who do not engage in active teaching, but do exhibit long juvenile periods and complex social systems that allow differential experience to shape behavior. Here we ask whether early life exposure to aggression is sexually dimorphic in wild chimpanzees and, if so, whether other aspects of early sociality contribute to this difference. Using 13 y of all-occurrence aggression data collected from the Kanyawara community of chimpanzees (2005 to 2017), we determined that young male chimpanzees were victims of aggression more often than females by between 4 and 5 (i.e., early in juvenility). Combining long-term aggression data with data from a targeted study of social development (2015 to 2017), we found that two potential risk factors for aggression-time spent near adult males and time spent away from mothers-did not differ between young males and females. Instead, the major risk factor for receiving aggression was the amount of aggression that young chimpanzees displayed, which was higher for males than females throughout the juvenile period. In multivariate models, sex did not mediate this relationship, suggesting that other chimpanzees did not target young males specifically, but instead responded to individual behavior that differed by sex. Thus, social experience differed by sex even in the absence of explicit gender socialization, but experiential differences were shaped by early-emerging sex differences in behavior.

Perturbations in plant energy homeostasis prime lateral root initiation via SnRK1-bZIP63-ARF19 signaling.

Plants adjust their energy metabolism to continuous environmental fluctuations, resulting in a tremendous plasticity in their architecture. The regulatory circuits involved, however, remain largely unresolved. In Arabidopsis, moderate perturbations in photosynthetic activity, administered by short-term low light exposure or unexpected darkness, lead to increased lateral root (LR) initiation. Consistent with expression of low-energy markers, these treatments alter energy homeostasis and reduce sugar availability in roots. Here, we demonstrate that the LR response requires the metabolic stress sensor kinase Snf1-RELATED-KINASE1 (SnRK1), which phosphorylates the transcription factor BASIC LEUCINE ZIPPER63 (bZIP63) that directly binds and activates the promoter of AUXIN RESPONSE FACTOR19 (ARF19), a key regulator of LR initiation. Consistently, starvation-induced ARF19 transcription is impaired in bzip63 mutants. This study highlights a positive developmental function of SnRK1. During energy limitation, LRs are initiated and primed for outgrowth upon recovery. Hence, this study provides mechanistic insights into how energy shapes the agronomically important root system.

Symptoms and Management of Aseptic Liver Abscesses.

Aseptic liver abscesses occur very rarely. Clinical guidelines on the management of the disease do not exist, and the diagnosis is challenging.We screen MEDLINE and PUBMED databases for relevant case reports from inception to November 2022. Information on patient age, sex, initial symptoms, the extent of abscess formation, further diagnoses, treatment, and course of the disease is analyzed.Thirty cases with sterile hepatic abscess formation are identified. In most patients (n=18), the spleen is affected as well. Patients typically present with fever, abdominal pain, and increased inflammatory values. Comorbidity with inflammatory bowel disease is very common (n=18) and is associated with a significantly younger age at the time of hepatic abscess development. In addition, many patients show autoimmune-mediated cutaneous, ocular, or arthritic rheumatoid manifestations. Histological examination of abscess material reveals neutrophilic infiltration. The majority of patients initially receive corticosteroid therapy. Furthermore, response to azathioprine, anti-TNF-α antibodies, and other immunomodulatory drugs is reported. Ten out of fourteen patients with a long-term follow-up (≥ 36 months) have at least one relapse of hepatic abscess formation.Aseptic hepatic abscesses should be considered in the case of sterile punctures and non-response to antibiotics. Patients with aseptic liver abscesses have a high risk of recurrence warranting immunomodulatory maintenance therapy.

Virtual reality simulation to enhance advanced trauma life support trainings - a randomized controlled trial.

BACKGROUND: Advanced Trauma Life Support (ATLS) is the gold standard of initial assessment of trauma patients and therefore a widely used training program for medical professionals. Practical application of the knowledge taught can be challenging for medical students and inexperienced clinicians. Simulation-based training, including virtual reality (VR), has proven to be a valuable adjunct to real-world experiences in trauma education. Previous studies have demonstrated the effectiveness of VR simulations for surgical and technical skills training. However, there is limited evidence on VR simulation training specifically for trauma education, particularly within the ATLS curriculum. The purpose of this pilot study is to evaluate the feasibility, effectiveness, and acceptance of using a fully immersive VR trauma simulation to prepare medical students for the ATLS course. METHODS: This was a prospective randomised controlled pilot study on a convenience sample of advanced medical students (n = 56; intervention group with adjunct training using a commercially available semi-automated trauma VR simulation, n = 28, vs control group, n = 28) taking part in the ATLS course of the Military Physician Officer School. Feasibility was assessed by evaluating factors related to technical factors of the VR training (e.g. rate of interruptions and premature termination). Objective and subjective effectiveness was assessed using confidence ratings at four pre-specified points in the curriculum, validated surveys, clinical scenario scores, multiple choice knowledge tests, and ATLS final clinical scenario and course pass rates. Acceptance was measured using validated instruments to assess variables of media use (Technology acceptance, usability, presence and immersion, workload, and user satisfaction). RESULTS: The feasibility assessment demonstrated that only one premature termination occurred and that all remaining participants in the intervention group correctly stabilised the patient. No significant differences between the two groups in terms of objective effectiveness were observed (p = 0.832 and p = 0.237 for the pretest and final knowledge test, respectively; p = 0.485 for the pass rates for the final clinical scenario on the first attempt; all participants passed the ATLS course). In terms of subjective effectiveness, the authors found significantly improved confidence post-VR intervention (p < .001) in providing emergency care using the ATLS principles. Perceived usefulness in the TEI was stated with a mean of 4 (SD 0.8; range 0-5). Overall acceptance and usability of the VR simulation was rated as positive (System Usability Scale total score mean 79.4 (SD 11.3, range 0-100). CONCLUSIONS: The findings of this prospective pilot study indicate the potential of using VR trauma simulations as a feasible and acceptable supplementary tool for the ATLS training course. Where objective effectiveness regarding test and scenario scores remained unchanged, subjective effectiveness demonstrated improvement. Future research should focus on identifying specific scenarios and domains where VR can outperform or enhance traditional learning methods in trauma simulation.

Emergency department utilisation and treatment for trauma-related presentations of adolescents aged 16-18: a retrospective cross-sectional study.

BACKGROUND: A recent study conducted at our tertiary hospital emergency department (ED) reviewed ED consultations and found that adolescents aged 16-18 years present significantly more often for trauma and psychiatric problems than adults over 18 years. Accidental injuries are one of the greatest health risks for children and adolescents. In view of the increased vulnerability of the adolescent population, this study aimed to further analyse trauma-related presentations in adolescents. METHODS: We conducted a single-centre, retrospective, cross-sectional study of all adolescent trauma patients aged 16 to 18 years presenting to the adult ED at the University Hospital (Inselspital) in Bern, Switzerland, from January 2013 to July 2017. We analysed presentation data as well as inpatient treatment and cost-related data. Data of female and male patients were compared by univariable analysis. A comparison group was formed consisting of 200 randomly chosen patients aged 19-25 years old with the same presentation characteristics. Predictive factors for surgical treatment were obtained by multivariable analysis. RESULTS: The study population included a total of 1,626 adolescent patients aged 16-18 years. The predominant causes for ED presentation were consistent within case and comparison groups for sex and age and were sports accidents, falls and violence. Male patients were more likely to need surgical treatment (OR 1.8 [95% CI: 1.2-2.5], p = 0.001) and consequently inpatient treatment (OR 1.5 [95% CI: 1.1-2.1], p = 0.01), associated with higher costs (median 792 Swiss francs [IQR: 491-1,598]). Other independent risk factors for surgical treatment were violence-related visits (OR 2.1 [95% CI: 1.3-3.5, p = 0.004]) and trauma to the upper extremities (OR 2.02 [95% CI: 1.5-2.8], p < 0.001). Night shift (OR 0.56 [95% CI: 0.37-0.86], 0.008) and walk-in consultations (OR 0.3 [95% CI: 0.2; 0.4, < 0.001] were preventive factors for surgical treatment. CONCLUSIONS: Male adolescents account for the majority of emergency visits and appear to be at higher risk for accidents as well as for surgical treatment and/or inpatient admission due to sports accidents or injuries from violence. We suggest that further preventive measures and recommendations should be implemented and that these should focus on sport activities and injuries from violence.

Epidemiology of maxillofacial trauma in elderly patients receiving oral anticoagulant or antithrombotic medication; a Swiss retrospective study.

BACKGROUND: The percentage of elderly trauma patients under anticoagulation and antiplatelet agents has been rising lately. As newer agents are introduced, each comes with its own advantages and precautions. Our study covered elderly patients admitted to the ED with maxillofacial trauma while on anticoagulation (AC) or antiplatelet therapy (APT). We aimed to investigate the demographic characteristics, causes, and types of maxillofacial trauma, along with concomitant injuries, duration of hospitalisation, haemorrhagic complications, and the overall costs of care in the emergency department (ED). METHODS: Data were gathered from the ED of Bern University Hospital. In this retrospective analysis, patients over 65 of age were included, who presented at our ED with maxillofacial trauma between 2013 and 2019 while undergoing treatment with therapeutic AC/APT. RESULTS: The study involved 188 patients with a median age of 81 years (IQR: 81 [74; 87]), of whom 55.3% (n=104) were male. More than half (54.8%, n=103) were aged 80 years or older. Cardiovascular diseases were present in 69.7% (n=131) of the patients, with the most common indications for AC/APT use being previous thromboembolic events (41.5%, n=78) and atrial fibrillation (25.5%, n=48). The predominant cause of facial injury was falls, accounting for 83.5% (n=157) of cases, followed by bicycle accidents (6.9%, n=13) and road-traffic accidents (5.3%, n=10). The most common primary injuries were fractures of the orbital floor and/or medial/lateral wall (60.1%, n=113), zygomatic bone (30.3%, n=57), followed by isolated orbital floor fractures (23.4%, n=44) and nasal bone fractures (19.1%, n=36). Fractures of the mandible occurred in 14.9% (n=28). Facial hematomas occurred in 68.6% of patients (129 cases), primarily in the midface area. Relevant facial bleeding complications were intracerebral haemorrhage being the most frequent (28.2%, n=53), followed by epistaxis (12.2%, n=23) and retrobulbar/intraorbital hematoma (9%, n=17). Sixteen patients (8.5%) experienced heavy bleeding that required emergency treatment. The in-hospital mortality rate was 2.1% (4 cases). CONCLUSIONS: This study indicates that falls are the leading cause of maxillofacial trauma in the elderly, with the most common diagnoses being orbital, zygomatic, and nasal fractures. Haemorrhagic complications primarily involve facial hematomas, especially in the middle third of the face, with intracerebral haemorrhage being the second most frequent. Surgical intervention for bleeding was required in 8.5% of cases. Given the aging population, it is essential to improve prevention strategies and update safety protocols, particularly for patients on anticoagulant/antiplatelet therapy (AC/APT). This can ensure rapid diagnostic imaging and prompt treatment in emergencies.

Computation of X-ray and Neutron Scattering Patterns to Benchmark Atomistic Simulations against Experiments.

Molecular Dynamics simulations study material structure and dynamics at the atomic level. X-ray and neutron scattering experiments probe exactly the same time- and length scales as the simulations. In order to benchmark simulations against measured scattering data, a program is required that computes scattering patterns from simulations with good single-core performance and support for parallelization. In this work, the existing program Sassena is used as a potent solution to this requirement for a range of scattering methods, covering pico- to nanosecond dynamics, as well as the structure from some Ångströms to hundreds of nanometers. In the case of nanometer-level structures, the finite size of the simulation box, which is referred to as the finite size effect, has to be factored into the computations for which a method is described and implemented into Sassena. Additionally, the single-core and parallelization performance of Sassena is investigated, and several improvements are introduced.

Impaired dynamic cerebral autoregulation measured in the middle cerebral artery in patients with vertebrobasilar ischemia is associated with autonomic failure.

OBJECTIVES: To assess whether vertebrobasilar artery ischemia (VBI) affects cortical cerebral blood flow (CBF) regulation. MATERIAL AND METHODS: 107 consecutive patients (mean age 65 ± 15 years; women 21) with VBI underwent structured stroke care with assessment of dynamic cerebral autoregulation (dCA) in both middle cerebral arteries (MCAs) by transfer function analysis using spontaneous oscillations of blood pressure (BP) and CBF velocity that yields by extraction of phase and gain information in the very low (0.02-0.07 Hz), low (0.07-0.15 Hz) and high frequency (0.15-0.5 Hz) ranges. Additionally, power spectrum analysis of BP and heart rate variability (HRV) was performed. The control group consists of 29 age- and sex-matched healthy persons. RESULTS: Compared to controls, phase in the VBI patients was significantly reduced and gain increased in the very low frequencies (VLF), in the low (LF), phase was significantly reduced only ipsilaterally. In the high frequencies (HF), phase reduction was only marginally significant. BP power spectral density (PSD) was much higher in the patients than in the controls across all frequencies. In the PSD of heart rate variability the controls but not the patients exhibited a strong peak around 0.11Hz, while the patients, but not the controls, exhibit a strong peak around 0.36 Hz. In regression analysis, patient's phase and gain results were not related to age, sex, arterial hypertension, diabetes mellitus, renal dysfunction, heart failure as indicated by left ventricular ejection fraction, stroke subtype, presence or absence of cerebral small vessel disease. CONCLUSION: Patients with VBI exhibit bilateral cortical autoregulation impairment in association with an autonomic nervous system disbalance. GOV IDENTIFIER: NCT04611672.

Conformational Space of the Translocation Domain of Botulinum Toxin: Atomistic Modeling and Mesoscopic Description of the Coiled-Coil Helix Bundle.

The toxicity of botulinum multi-domain neurotoxins (BoNTs) arises from a sequence of molecular events, in which the translocation of the catalytic domain through the membrane of a neurotransmitter vesicle plays a key role. A recent structural study of the translocation domain of BoNTs suggests that the interaction with the membrane is driven by the transition of an α helical switch towards a ß hairpin. Atomistic simulations in conjunction with the mesoscopic Twister model are used to investigate the consequences of this proposition for the toxin-membrane interaction. The conformational mobilities of the domain, as well as the effect of the membrane, implicitly examined by comparing water and water-ethanol solvents, lead to the conclusion that the transition of the switch modifies the internal dynamics and the effect of membrane hydrophobicity on the whole protein. The central two α helices, helix 1 and helix 2, forming two coiled-coil motifs, are analyzed using the Twister model, in which the initial deformation of the membrane by the protein is caused by the presence of local torques arising from asymmetric positions of hydrophobic residues. Different torque distributions are observed depending on the switch conformations and permit an origin for the mechanism opening the membrane to be proposed.