Magnetic voluntary head-fixation in transgenic rats enables lifespan imaging of hippocampal neurons.

The precise neural mechanisms within the brain that contribute to the remarkable lifetime persistence of memory are not fully understood. Two-photon calcium imaging allows the activity of individual cells to be followed across long periods, but conventional approaches require head-fixation, which limits the type of behavior that can be studied. We present a magnetic voluntary head-fixation system that provides stable optical access to the brain during complex behavior. Compared to previous systems that used mechanical restraint, there are no moving parts and animals can engage and disengage entirely at will. This system is failsafe, easy for animals to use and reliable enough to allow long-term experiments to be routinely performed. Animals completed hundreds of trials per session of an odor discrimination task that required 2-4 s fixations. Together with a reflectance fluorescence collection scheme that increases two-photon signal and a transgenic Thy1-GCaMP6f rat line, we are able to reliably image the cellular activity in the hippocampus during behavior over long periods (median 6 months), allowing us track the same neurons over a large fraction of animals' lives (up to 19 months).

Phylogenomic analyses re-examine the evolution of reinforcement and hypothesized hybrid speciation in Phlox wildflowers.

The tree of life is riddled with reticulate evolutionary histories, and some clades, such as the eastern standing Phlox, appear to be hotspots of hybridization. In this group, there are two cases of reinforcement and nine hypothesized hybrid species. Given their historical importance in our understanding of plant speciation, the relationships between these taxa and the role of hybridization in their diversification require genomic validation. Using phylogenomic analyses, we resolve the evolutionary relationships of the eastern standing Phlox and evaluate hypotheses about whether and how hybridization and gene flow played a role in their diversification. Our results provide novel resolution of the phylogenetic relationships in this group, including paraphyly across some taxa. We identify gene flow during one case of reinforcement and find genomic support for a hybrid lineage underlying one of the five hypothesized homoploid hybrid speciation events. Additionally, we estimate the ancestries of four allotetraploid hybrid species. Our results are consistent with hybridization contributing to diverse evolutionary outcomes within this group; although, not as extensively as previously hypothesized. This study demonstrates the importance of phylogenomics in evaluating hypothesized evolutionary histories of non-model systems and adds to the growing support of interspecific genetic exchange in the generation of biodiversity.

National Emergency Tele-Critical Care in a Pandemic: Barriers and Solutions.

The COVID-19 pandemic caused tremendous disruption to the U.S. healthcare system and nearly crippled some hospitals during large patient surges. Limited ICU beds across the country further exacerbated these challenges. Telemedicine, specifically tele-critical care (TCC), can expand a hospital's clinical capabilities through remote expertise and increase capacity by offloading some monitoring to remote teams. Unfortunately, the rapid deployment of telemedicine, especially TCC, is constrained by multiple barriers. In the summer of 2020, to support the National Emergency Tele-Critical Care Network (NETCCN) deployment, more than 50 national leaders in applying telemedicine technologies to critical care assembled to provide their opinions about barriers to NETCCN implementation and strategies to overcome them. Through consensus, these experts developed white papers that formed the basis of this article. Herein, the authors share their experience and propose multiple solutions to barriers presented by laws, local policies and cultures, and individual perspectives according to a minimum, better, best paradigm for TCC delivery in the setting of a national disaster. Cross-state licensure and local privileging of virtual experts were identified as the most significant barriers to rapid deployment of services, whereas refining the model of TCC to achieve the best outcomes and defining the best financial model is the most significant for long-term success. Ultimately, we conclude that a rapidly deployable national telemedicine response system is achievable.

A multidimensional selective landscape drives adaptive divergence between and within closely related Phlox species.

Selection causes local adaptation across populations within species and simultaneously divergence between species. However, it is unclear if either the force of or the response to selection is similar across these scales. We show that natural selection drives divergence between closely related species in a pattern that is distinct from local adaptation within species. We use reciprocal transplant experiments across three species of Phlox wildflowers to characterize widespread adaptive divergence. Using provenance trials, we also find strong local adaptation between populations within a species. Comparing divergence and selection between these two scales of diversity we discover that one suite of traits predicts fitness differences between species and that an independent suite of traits predicts fitness variation within species. Selection drives divergence between species, contributing to speciation, while simultaneously favoring extensive diversity that is maintained across populations within a species. Our work demonstrates how the selection landscape is complex and multidimensional.

Structural and functional profile of phytases across the domains of life.

Phytase enzymes are a crucial component of the natural phosphorus cycle, as they help make phosphate bioavailable by releasing it from phytate, the primary reservoir of organic phosphorus in grain and soil. Phytases also comprise a significant segment of the agricultural enzyme market, used primarily as an animal feed additive. At least four structurally and mechanistically distinct classes of phytases have evolved in bacteria and eukaryotes, and the natural diversity of each class is explored here using advances in protein structure prediction and functional annotation. This graphical review aims to provide a succinct description of the major classes of phytase enzymes across phyla, including their structures, conserved motifs, and mechanisms of action.

A cross-species framework for investigating perceptual evidence accumulation.

Cross-species studies are important for a comprehensive understanding of brain functions. However, direct quantitative comparison of behaviors across species presents a significant challenge. To enable such comparisons in perceptual decision-making, we developed a synchronized evidence accumulation task for rodents and humans, by aligning mechanics, stimuli, and training. Rats, mice and humans readily learned the task and exhibited qualitatively similar performance. Quantitative model comparison revealed that all three species employed an evidence accumulation strategy, but differed in speed, accuracy, and key decision parameters. Human performance prioritized accuracy, whereas rodent performance was limited by internal time-pressure. Rats optimized reward rate, while mice appeared to switch between evidence accumulation and other strategies trial-to-trial. Together, these results reveal striking similarities and species-specific priorities in decision-making. Furthermore, the synchronized behavioral framework we present may facilitate future studies involving cross-species comparisons, such as evaluating the face validity of animal models of neuropsychiatric disorders. Highlights: Development of a free response evidence accumulation task for rats and miceSynchronized video game allows direct comparisons with humansRat, mouse and human behavior are well fit by the same decision modelsModel parameters reveal species-specific priorities in accumulation strategy.

Prosthesis Infolding Incidence and Short-Term Outcomes in Transcatheter Aortic Valve Implantation Using Evolut Self-Expandable Device: A Multicenter Study.

Transcatheter aortic valve implantation (TAVI) is an established treatment strategy in aortic valve disease. Infolding, as a nonuniform expansion of the prosthesis leading to introflection of part of the device circumference, is a complication specific to self-expandable prostheses. The aim of the study is to determine incidence, predictors, treatment strategy, and outcomes of infolding during Medtronic Evolut TAVI (Minneapolis, MN, US). Between January 2018 and March 2022, all patients treated with Evolut TAVI were included in a multicenter observational retrospective study. According to the occurrence of infolding, the enrolled cohort was divided into 2 groups; periprocedural characteristics and 30-day outcomes were compared. A total of 1,470 patients were included; 23 infolding cases (1.6%) were detected. Preprocedural imaging showed larger aortic anatomy and greater calcium burden in the infolding group. Infolding occurred mostly with Evolut Pro+ and size 34 mm and was diagnosed before full prosthesis release in 78.3%. The rate of moderate-to-severe paravalvular regurgitation was higher in the infolding group (21.7% vs 1.9%, p <0.001). Short-term follow-up showed greater all-cause and cardiovascular mortality (respectively, 4.3% vs 0.7% and 4.3% vs 0.6%, p <0.05) and higher rate of pacemaker implantation (33.3% vs 15.7%, p = 0.042) in case of infolding. High right cusp calcium score and resheathing maneuvers were independent predictors of infolding. In conclusion, prosthesis infolding is a TAVI complication burdened by worse cardiovascular outcomes. Prompt intraprocedural infolding diagnosis is pivotal, especially in case of great native valve calcium burden and resheathing maneuvers, to safely overcome this complication by prosthesis recapture or postdilation.

Angiography-derived physiological assessment after percutaneous coronary intervention of chronic total occlusions.

Scant data exploring potential suboptimal physiological results after angiographic successful percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) are available. Sixty cases of successful CTO-PCI were selected for this retrospective analysis. Post-CTO-PCI angiography-based fractional flow reserve was computed using the Murray-based fractional flow reserve (µFR) software. Vessel-specific µFR, residual trans-stent gradient (TSG) and corrected TSGstent were calculated. In physiological suboptimal results (µFR < 0.90), the virtual pullback pressure gradient (PPG) curves were analyzed to localize the main pressure drop-down and characterize the patterns of residual disease. The virtual pullback pressure gradient index (vPPGi) was then calculated to objectively characterize the predominant pattern of residual disease (diffuse vs focal). The physiological result was suboptimal in 28 cases (46.7%). The main pressure drop was localised proximal to the stent in 2 (7.1%), distal in 17 (60.7%) and intra-stent in 9 cases (32.2%). Intra-stent residual disease was diffuse in 7 cases and mixed in 2. Distal residual disease was characterised by a pure focal pattern in 12 cases, diffuse in 2 and mixed in 3. In the predominant diffuse phenotype (vPPGi < 0.65), we found a higher rate of TSG ≥ 0.04 (61.5% vs 20.0%, p = 0.025) and TSGstent ≥ 0.009 (46.2% vs 20.0%, p = 0.017) while in the dominant focal phenotype poor-quality distal vessel was constantly present. In our cohort, post-CTO-PCI suboptimal physiological result was frequent (46.7%). Predominant focal phenotype was constantly associated with poor-quality distal vessel, while in the predominant diffuse phenotype, the rate of TSG ≥ 0.04 and TSGstent ≥ 0.009 were significantly higher.

Performance of the minimalistic hybrid approach algorithm versus other conventional algorithms in the percutaneous treatment of chronic total occlusions.

BACKGROUND: The "Minimalistic Hybrid Approach" (MHA) has been proposed to reduce the invasiveness of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). AIMS: This study aims to assess whether MHA may also reduce the utilization of PCI resources (devices, radiations, and contrast) by comparing it with other conventional algorithms. METHODS: We aimed to assess the impact of MHA on device, radiation, and contrast usage during CTO-PCI analyzing data from the Belgian Working Group on CTO (BWG-CTO) registry. Patients were divided, depending on the algorithm used, into two groups: Conventional versus Minimalistic. Primary objectives were procedure performance measures such as device usage (microcatheters and guidewires), radiological parameters, and contrast use. At 1-year follow-up, patients were evaluated for target vessel failure (TVF), defined as a composite of cardiac death, new myocardial infarction, and target vessel revascularization. RESULTS: Overall, we analyzed 821 CTO-PCIs (Conventional n = 650, Minimalistic n = 171). The Minimalistic group demonstrated higher complexity of CTO lesions. After adjusting for propensity score, the Minimalistic group had a significantly lower number of microcatheters used (1.49 ± 0.85 vs. 1.24 ± 0.64, p = 0.026), while the number of guidewires was comparable (4.80 ± 3.29 vs. 4.35 ± 2.94, p = 0.30). Both groups had similar rates of success and procedural complications, as well as comparable procedural and fluoroscopic times and contrast volume used. At the 1-year follow-up, both groups showed comparable rates of TVF (hazard ratio: 0.57; 95% confidence interval: 0.24-1.34, p = 0.195). CONCLUSION: The MHA may slightly reduce the number of dedicated devices used during CTO-PCI, without adversely affecting the procedural success or long-term outcome.

In vivo imaging in transgenic songbirds reveals superdiffusive neuron migration in the adult brain.

Neuron migration is a key phase of neurogenesis, critical for the assembly and function of neuronal circuits. In songbirds, this process continues throughout life, but how these newborn neurons disperse through the adult brain is unclear. We address this question using in vivo two-photon imaging in transgenic zebra finches that express GFP in young neurons and other cell types. In juvenile and adult birds, migratory cells are present at a high density, travel in all directions, and make frequent course changes. Notably, these dynamic migration patterns are well fit by a superdiffusive model. Simulations reveal that these superdiffusive dynamics are sufficient to disperse new neurons throughout the song nucleus HVC. These results suggest that superdiffusive migration may underlie the formation and maintenance of nuclear brain structures in the postnatal brain and indicate that transgenic songbirds are a useful resource for future studies into the mechanisms of adult neurogenesis.

Scaling up Functional Analyses of the G Protein-Coupled Receptor Rhodopsin.

Eukaryotic cells use G protein-coupled receptors (GPCRs) to convert external stimuli into internal signals to elicit cellular responses. However, how mutations in GPCR-coding genes affect GPCR activation and downstream signaling pathways remain poorly understood. Approaches such as deep mutational scanning show promise in investigations of GPCRs, but a high-throughput method to measure rhodopsin activation has yet to be achieved. Here, we scale up a fluorescent reporter assay in budding yeast that we engineered to study rhodopsin's light-activated signal transduction. Using this approach, we measured the mutational effects of over 1200 individual human rhodopsin mutants, generated by low-frequency random mutagenesis of the GPCR rhodopsin (RHO) gene. Analysis of the data in the context of rhodopsin's three-dimensional structure reveals that transmembrane helices are generally less tolerant to mutations compared to flanking helices that face the lipid bilayer, which suggest that mutational tolerance is contingent on both the local environment surrounding specific residues and the specific position of these residues in the protein structure. Comparison of functional scores from our screen to clinically identified rhodopsin disease variants found many pathogenic mutants to be loss of function. Lastly, functional scores from our assay were consistent with a complex counterion mechanism involved in ligand-binding and rhodopsin activation. Our results demonstrate that deep mutational scanning is possible for rhodopsin activation and can be an effective method for revealing properties of mutational tolerance that may be generalizable to other transmembrane proteins.

In-vitro validation of coronary physiology assessment with 5 French guiding catheters.

BACKGROUND: The trans-radial approach for cardiac catheterization led to an increasing adoption of 5 French (F) catheters. We aim to evaluate reliability and reproducibility of coronary physiology assessment performed with 5F guiding catheter (GC). METHODS: Physiological measurements were performed in a coronary flow simulator, which provides two pulsatile flows, the baseline and hyperaemic flows. Two screws, positioned proximally and distally to the distal sensor of a pressure-temperature guidewire, were used to determine various combinations of stenoses and distal obstructions, simulating different pathophysiological conditions. For each setting, 5 measurements of fractional flow reserve (FFR), coronary flow reserve (CFR) and index of microvascular resistance (IMR) were performed with 6F and 5F GCs. RESULTS: A total amount of 190 measurements were performed, 95 with 6F GC and 95 with 5F GC. Minimal differences between 6F and 5F GCs were detected for FFR [0.91 (IQR: 0.87-0.94) and 0.87 (IQR: 0.82-0.92) respectively, p < 0.001] and IMR (16.5 ± 8.8 and 15.4 ± 8.3 respectively, p = 0.001). Mean CFR was comparable between 6F and 5F GCs (3.6 ± 1.1 and 3.5 ± 0.7 respectively, p = 0.38). Misclassification rates were 1.0 %, 1.0 % and 0 % for FFR, CFR and IMR, respectively. According to Passing-Bablok analysis, an excellent agreement between 6F and 5F GCs was demonstrated for FFR and IMR, and a modest agreement for CFR. All measurements with 5F GC showed high reproducibility. CONCLUSIONS: In our in-vitro model, a complete physiological assessment including FFR, CFR and IMR resulted substantially comparable between 6F and 5F GCs. Further in-vivo analysis is required to support these findings.

Prevalence of Collateral Typology in Coronary Chronic Total Occlusion and Its Impact on Percutaneous Intervention Performance.

The presence of collateral channels providing distal blood supply is a distinctive characteristic of chronic total occlusion (CTO) lesions. However, data about the distinct baseline and procedural characteristics of each collateral subset are scarce. Accordingly, we sought to explore the procedural aspects specific for each collateral typology (ipsilateral collaterals [ICs], contralateral collaterals [CCs] or mixed) in CTO-percutaneous coronary intervention (PCI). A retrospective analysis of our CTO-PCI registry was performed to investigate the prevalence, procedural characteristics, and outcomes specific for each CTO-PCI subset, defined according to the inter-arterial connection anatomy. A total of 209 cases were included. Of the included cases, 45 (22%) and 92 (44%) patients displayed solely IC or CC, respectively, whereas in 72 (34%) both IC and CC were present (mixed). The procedural success rate was high (91.1%) and comparable among the different groups, despite greater lesion complexity in the CC group. The most frequent target vessel was the left circumflex in the IC group (51% of cases) and the right coronary artery in the CC (63%) and mixed (57%) groups. Among the IC cases, 42% showed a poor collateral connection function (2% and 10% for the CC and mixed group, respectively), and 46% showed a suboptimal collateral recipient artery filling (21% and 20% for the CC and mixed group, respectively). Most of the IC cases were performed using a single access (96%). In conclusion, the success and complication rates were comparable among the collateral typology groups, irrespective of the differences in the baseline and procedural characteristics. Phenotyping CTO as hereby proposed might be helpful for targeted procedural considerations.

Minimalistic Hybrid Approach for the Percutaneous Treatment of Coronary Chronic Total Occlusions: Midterm Follow-Up of an International Multicenter Cohort.

The minimalistic hybrid approach (MHA) is a recently proposed algorithm to perform chronic total occlusion (CTO) percutaneous coronary intervention (PCI), reducing the overall invasiveness of the procedure without impacting the acute results. However, data on midterm results are lacking. This study aimed to evaluate the midterm clinical outcomes of a multicenter international cohort of CTO PCI treated according to the MHA. Data from a consecutive series of patients with a CTO who underwent PCI according to the MHA between February 2019 and March 2022 were prospectively collected in 3 European centers and retrospectively analyzed. The main outcome was the first occurrence of a major adverse cardiac event (MACE), defined as a composite outcome of all-cause death, any myocardial infarction, and target vessel revascularization, at the last follow-up available. A total of 212 patients were included. The majority of the patients were symptomatic for angina (Canadian Cardiovascular Society class 2 or 3: 63.7%) at the time of the index procedure. The mean Japanese-CTO and CASTLE scores were 2.1 ± 1.2 and 2.0 ± 1.3, respectively. Technical success (CTO open with optimal flow) was achieved in 198 patients (93.9%) and procedural success (technical success without in-hospital MACEs) in 195 (91.9%). At the last follow-up available (median 677 days), the cumulative incidence rate of MACEs was 11.5%; in particular, all-cause death was 7.4%, any myocardial infarction was 4.3%, and unplanned target vessel revascularization was 6.5%. In conclusion, the midterm results of the MHA seem to be in line with contemporary results of other CTO PCI algorithms, thus potentially validating the MHA as a valuable alternative, provided that interventionalists are already expert CTO operators and accustomed to the definitions and peculiarities of MHA.

Advances in cellular resolution microscopy for brain imaging in rats.

Rats are used in neuroscience research because of their physiological similarities with humans and accessibility as model organisms, trainability, and behavioral repertoire. In particular, rats perform a wide range of sophisticated social, cognitive, motor, and learning behaviors within the contexts of both naturalistic and laboratory environments. Further progress in neuroscience can be facilitated by using advanced imaging methods to measure the complex neural and physiological processes during behavior in rats. However, compared with the mouse, the rat nervous system offers a set of challenges, such as larger brain size, decreased neuron density, and difficulty with head restraint. Here, we review recent advances in in vivo imaging techniques in rats with a special focus on open-source solutions for calcium imaging. Finally, we provide suggestions for both users and developers of in vivo imaging systems for rats.

The First Statewide Implementation of a Regional Disaster Teleconsultation System to Expand Critical Care Surge Capacity: A Case Study in Vermont.

Background: In December 2021, the Region 1 Disaster Health Response System, the state of Vermont, and the National Emergency Tele-Critical Care Network partnered to provide statewide access to disaster teleconsultations during COVID-19 surge conditions. In this case report, we describe how a disaster teleconsultation system was implemented in Vermont to provide access to temporary tele-critical care consultations during the Omicron COVID-19 surge. Methods: We measured the time from request of service to implementation and calculated descriptive statistics. Results: Seven of Vermont's 14 hospitals requested the service. Despite a technology solution capable of providing services within hours, mean time to service implementation was 27 days (interquartile range 20-41 days). Conclusions: Integration of disaster teleconsultation systems into state and local emergency management plans are needed to bring administrative start-up times in line with technical readiness.