Simulated bacterial infection induces different changes in DNA methylation between introduced and native house sparrows Passer domesticus

DNA methylation, which can change within‐individuals over time and regulate gene expression, is important to many aspects of avian biology. It is particularly important in avian responses to various stressors associated with introductions, such as infection and environmental changes. However, it remains unclear whether native and introduced bird populations differ in their epigenetic responses to stressors, and how DNA methylation may contribute to the success of non‐native populations because of the limited availability of epigenetic studies. To address this knowledge gap, we used epiRADseq to investigate changes in DNA methylation within‐individual house sparrows Passer domesticus prior to and eight hours after a simulated bacterial infection. We compare wild‐caught house sparrows from introduced populations with those from native populations, assessing the number of genomic locations that exhibit changes in methylation, the magnitude of those changes, and the variance among individuals. Our results show that individuals from introduced populations experience more widespread changes in DNA methylation, with greater magnitude and higher variance, compared to their counterparts from native populations. These findings suggest that DNA methylation plays a significant role in an individual's response to infection. They also indicate that individuals from introduced populations may exhibit distinct epigenetic responses compared to their native counterparts, consistent with the concept of epigenetic buffering

Current Opinions on Optimal Management of Basilar Artery Occlusion: After the BEST of BASICS Survey

Background The best management of basilar artery occlusion (BAO) remains uncertain. The BASICS (Basilar Artery International Cooperation Study) and the BEST (Basilar Artery Occlusion Endovascular Intervention Versus Standard Medical Treatment) trials reported neutral results. We sought to understand physicians’ approaches to BAOs and whether further BAO randomized controlled trials were warranted. Methods We conducted an online international survey from January to March 2022 to stroke neurologists and neurointerventionalists. Survey questions were designed to examine clinical and imaging parameters under which clinicians would offer (or rescind) a patient with BAO to endovascular therapy (EVT) or best medical management versus enrollment into a randomized clinical trial. Results Of >3002 invited participants, 1245 responded (41.4% response rate) from 73 countries, including 54.7% stroke neurologists and 43.6% neurointerventionalists. More than 95% of respondents would offer EVT to patients with BAO, albeit in various clinical circumstances. There were 70.0% of respondents who indicated that the BASICS and BEST trials did not change their practice. Only 22.1% of respondents would perform EVT according to anterior circulation occlusion criteria. The selection of patients for BAO EVT by clinical severity, timing, and imaging modality differed according to geography, specialty, and country income level. Over 80% of respondents agreed that further randomized clinical trials for BAO were warranted. Moreover, 45.6% of respondents indicated they would find it acceptable to enroll all trial‐eligible patients into the medical arm of a BAO trial, whereas 26.3% would not enroll. Conclusion Most stroke physicians continue to believe in the efficacy of EVT in selected patients with BAO in spite of BEST and BASICS. There is no consensus on which selection criteria to use, and few clinicians would use anterior circulation occlusion criteria for BAOs. Further randomized clinical trials for BAO are warranted

Basilar artery occlusion management: An international survey of middle versus high-income countries

Background and Purpose Two early basilar artery occlusion (BAO) randomized controlled trials (RCTs) did not establish the superiority of endovascular thrombectomy (EVT) over medical management. Yet many providers continued to recommend EVT. The goal of the present article is to compare physicians’ diagnostic and management strategies of BAO among middle-income and high-income countries (MICs and HICs, respectively). Methods We conducted an international survey from January to March 2022 regarding management strategies in acute BAO, to examine clinical and imaging parameters influencing clinician management of patients with BAO. We compared responses between physicians from HIC and MIC. Results Among the 1245 respondents from 73 countries, 799 (64.2%) were from HIC, with the remaining 393 (31.6%) from MIC. Most respondents perceived that EVT was superior to medical management for acute BAO, but more so in respondents from HIC (98.0% vs. 94.2%, p < 0.01). MIC respondents were more likely to believe further RCTs were warranted (91.6% vs. 74.0%, p < 0.01) and were more likely to find it acceptable to enroll any patient who met a trial’s criteria in the standard medical treatment arm (58.8% vs. 38.5%, p < 0.01).Conclusions Conclusions In an area where clinical equipoise was called into question despite the lack of RCT evidence, we found that respondents from MIC were more likely to express willingness to enroll patients with BAO in an RCT than their HIC counterparts

Modelling Combined Intravenous Thrombolysis and Mechanical Thrombectomy in Acute Ischaemic Stroke: Understanding the Relationship between Stent Retriever Configuration and Clot Lysis Mechanisms

Background: Combined intravenous thrombolysis and mechanical thrombectomy (IVT-MT) is a common treatment in acute ischaemic stroke, however the interaction between IVT and MT from a physiological standpoint is poorly understood. In this pilot study, we conduct numerical simulations of combined IVT-MT with various idealised stent retriever configurations to evaluate performance in terms of complete recanalisation times and lysis patterns. Methods: A 3D patient-specific geometry of a terminal internal carotid artery with anterior and middle cerebral arteries is reconstructed, and a thrombus is artificially implanted in the MCA branch. Various idealised stent retriever configurations are implemented by varying stent diameter and stent placement, and a configuration without a stent retriever provides a baseline for comparison. A previously validated multi-level model of thrombolysis is used, which incorporates blood flow, drug transport, and fibrinolytic reactions within a fibrin thrombus. Results: Fastest total recanalisation was achieved in the thrombus without a stent retriever, with lysis times increasing with stent retriever diameter. Two mechanisms of clot lysis were established: axial and radial permeation. Axial permeation from the clot front was the primary mechanism of lysis in all configurations, as it facilitated increased protein binding with fibrin fibres. Introducing a stent retriever channel allowed for radial permeation, which occurred at the fluid-thrombus interface, although lysis was much slower in the radial direction because of weaker secondary velocities. Conclusions: Numerical models can be used to better understand the complex physiological relationship between IVT and MT. Two different mechanisms of lysis were established, providing a basis towards improving the efficacy of combined treatments.</jats:p

Data from: A novel mechanism of mixing by pulsing corals

The dynamic pulsation of the xeniid corals is one of the most fascinating phenomena observed in coral reefs. We quantify for the first time the flow near the tentacles of these soft corals whose active pulsations are thought to enhance their symbionts' photosynthetic rates by up to an order of magnitude. These polyps are about 1 cm in diameter and pulse at frequencies between about 0.5 and 1 Hz. As a result, the frequency based Reynolds number calculated using the tentacle length and pulse frequency is on the order of 10 and rapidly decays as one moves away from the polyp. This introduces the question of how these corals minimize the reversibility of the flow and bring in new volumes of fluid during each pulse. We estimate that the Peclet number of the bulk flow generated by the coral as being on the order of 100-1000 while the flow between the bristles of the tentacles as being on the order of 10. This illustrates the importance of advective transport in removing oxygen waste. Flow measurements using particle image velocimetry reveal that the individual polyps generate a jet of water with positive vertical velocities that do not go below 1 mm/s and with average volumetric flow rates of about 700 cubic mm per second. Our results show that there is nearly continual flow in the radial direction towards the polyp with only about 3.3 percent back flow. 3D numerical simulations uncover a region of slow mixing between the tentacles during expansion. We estimate that the average flow that moves through the bristles of the tentacles are about 0.3 mm/s. The combination of nearly continual flow towards the polyp, slow mixing between the bristles, and the subsequent ejection of this fluid volume into an upward jet ensures the polyp continually samples new water with sufficient time for exchange to occur

single_xeniid_polyp

This zip file contains raw images of a single xeniid coral polyp pulsing for several cycles. The coral polyp and the particles in the fluid are illuminated with a laser sheet

four_polyp_xeniid

This zip file contains raw images of four xeniid coral polyps pulsing. The corals and particles in the fluid are illuminated with a laser sheet

A novel mechanism of mixing by pulsing corals

The dynamic pulsation of the xeniid corals is one of the most fascinating phenomena observed in coral reefs. We quantify for the first time the flow near the tentacles of these soft corals whose active pulsations are thought to enhance their symbionts’ photosynthetic rates by up to an order of magnitude. These polyps are about 1 cm in diameter and pulse at frequencies between about 0.5 and 1 Hz. As a result, the frequency-based Reynolds number calculated using the tentacle length and pulse frequency is on the order of 10 and rapidly decays as one moves away from the polyp. This introduces the question of how these corals minimize the reversibility of the flow and bring in new volumes of fluid during each pulse. We estimate that the Péclet number of the bulk flow generated by the coral as being on the order of 100-1000 while the flow between the bristles of the tentacles is on the order of 10. This illustrates the importance of advective transport in removing oxygen waste. Flow measurements using particle image velocimetry reveal that the individual polyps generate a jet of water with positive vertical velocities that do not go below 0.1 cm/s and with average volumetric flow rates of about 0.71 cm3/s. Our results show that there is nearly continual flow in the radial direction towards the polyp with only about 3.3% back flow. 3D numerical simulations uncover a region of slow mixing between the tentacles during expansion. We estimate that the average flow that moves through the bristles of the tentacles is about 0.03 cm/s. The combination of nearly continual flow towards the polyp, slow mixing between the bristles, and the subsequent ejection of this fluid volume into an upward jet ensures the polyp continually samples new water with sufficient time for exchange to occur.</jats:p