High-resolution single-particle imaging at 100-200 keV with the Gatan Alpine direct electron detector.

Developments in direct electron detector technology have played a pivotal role in enabling high-resolution structural studies by cryo-EM at 200 and 300 keV. Yet, theory and recent experiments indicate advantages to imaging at 100 keV, energies for which the current detectors have not been optimized. In this study, we evaluated the Gatan Alpine detector, designed for operation at 100 and 200 keV. Compared to the Gatan K3, Alpine demonstrated a significant DQE improvement at these voltages, specifically a ~4-fold improvement at Nyquist at 100 keV. In single-particle cryo-EM experiments, Alpine datasets yielded better than 2 Å resolution reconstructions of apoferritin at 120 and 200 keV on a ThermoFisher Scientific (TFS) Glacios microscope. We also achieved a ~3.2 Å resolution reconstruction for a 115 kDa asymmetric protein complex, proving its effectiveness with complex biological samples. In-depth analysis revealed that Alpine reconstructions are comparable to K3 reconstructions at 200 keV, and remarkably, reconstruction from Alpine at 120 keV on a TFS Glacios surpassed all but the 300 keV data from a TFS Titan Krios with GIF/K3. Additionally, we show Alpine's capability for high-resolution data acquisition and screening on lower-end systems by obtaining ~3 Å resolution reconstructions of apoferritin and aldolase at 100 keV and detailed 2D averages of a 55 kDa sample using a side-entry cryo holder. Overall, we show that Gatan Alpine performs well with the standard 200 keV imaging systems and may potentially capture the benefits of lower accelerating voltages, possibly bringing smaller sized particles within the scope of cryo-EM.

Water Vapor Induced Superionic Conductivity in ZnPS3.

Next-generation batteries based on sustainable multivalent working ions, such as Mg2+, Ca2+, or Zn2+, have the potential to improve the performance, safety, and capacity of current battery systems. Development of such multivalent ion batteries is hindered by a lack of understanding of multivalent ionics in solids, which is crucial for many aspects of battery operation. For instance, multivalent ionic transport was assumed to be correlated with electronic transport; however, we have previously shown that Zn2+ can conduct in electronically insulating ZnPS3 with a low activation energy of 350 meV, albeit with low ionic conductivity. Here, we show that exposure of ZnPS3 to environments with water vapor at different relative humidities results in room-temperature conductivity increases of several orders of magnitude, reaching as high as 1.44 mS cm-1 without decomposition or structural changes. We utilize impedance spectroscopy with ion selective electrodes, ionic transference number measurements, and deposition and stripping of Zn metal, to confirm that both Zn2+ and H+ act as mobile ions. The contribution from Zn2+ to the ionic conductivity in water vapor exposed ZnPS3 is high, representing superionic Zn2+ conduction. The present study demonstrates that it is possible to enhance multivalent ion conduction of electronically insulating solids as a result of water adsorption and highlights the importance of ensuring that increased conductivity in water vapor exposed multivalent ion systems is in fact due to mobile multivalent ions and not solely H+.

Characterization of SARS-CoV-2 Aerosols Dispersed During Noninvasive Respiratory Support of Patients With COVID-19.

BACKGROUND: In the midst of the COVID-19 pandemic, noninvasive respiratory support (NRS) therapies such as high-flow nasal cannula (HFNC) and noninvasive ventilation (NIV) were central to respiratory care. The extent to which these treatments increase the generation and dispersion of infectious respiratory aerosols is not fully understood. The objective of this study was to characterize SARS-CoV-2 aerosol dispersion from subjects with COVID-19 undergoing NRS therapy. METHODS: Several different aerosol sampling devices were used to collect air samples in the vicinity of 31 subjects with COVID-19, most of whom were receiving NRS therapy, primarily HFNC. Aerosols were collected onto filters and analyzed for the presence of SARS-CoV-2 RNA. Additional measurements were collected in an aerosol chamber with healthy adult subjects using respiratory therapy devices under controlled and reproducible conditions. RESULTS: Fifty aerosol samples were collected from subjects receiving HFNC or NIV therapy, whereas 6 samples were collected from subjects not receiving NRS. Only 4 of the 56 aerosol samples were positive for SARS-CoV-2 RNA, and all positive samples were collected using a high air flow scavenger mask collection device placed in close proximity to the subject. The chamber measurements with healthy subjects did not show any significant increase in aerosol dispersion caused by the respiratory therapy devices compared to baseline. CONCLUSIONS: Our findings demonstrate very limited detection of SARS-CoV-2-containing aerosols in the vicinity of subjects with COVID-19 receiving NRS therapies in the clinical setting. These results, combined with controlled chamber measurements showing that HFNC and NIV device usage was not associated with increased aerosol dispersion, suggest that NRS therapies do not result in increased dispersal of aerosols in the clinical setting.

Effects of a Tridentate Pincer Ligand on Parahydrogen Induced Polarization.

The role of ligands in rhodium- and iridium-catalyzed Parahydrogen Induced Polarization (PHIP) and SABRE (signal amplification by reversible exchange) chemistry has been studied in the benchmark systems, [Rh(diene)(diphos)]+ and [Ir(NHC)(sub)3 (H)2 ]+ , and shown to have a great impact on the degree of hyperpolarization observed. Here, we examine the role of the flanking moieties in the electron-rich monoanionic bis(carbene) aryl pincer ligand, Ar CCC (Ar=Dipp, 2,6-diisopropyl or Mes, 2,4,6-trimethylphenyl) on the cobalt-catalyzed PHIP and PHIP-IE (PHIP via Insertion and Elimination) chemistry that we have previously reported. The mesityl groups were exchanged for diisopropylphenyl groups to generate the (Dipp CCC)Co(N2 ) catalyst, which resulted in faster hydrogenation and up to 390-fold 1 H signal enhancements, larger than that of the (Mes CCC)Co-py (py=pyridine) catalyst. Additionally, the synthesis of the (Dipp CCC)Rh(N2 ) complex is reported and applied towards the hydrogenation of ethyl acrylate with parahydrogen to generate modest signal enhancements of both 1 H and 13 C nuclei. Lastly, the generation of two (Mes CCC)Ir complexes is presented and applied towards SABRE and PHIP-IE chemistry to only yield small 1 H signal enhancements of the partially hydrogenated product (PHIP) with no SABRE hyperpolarization.

Multimodal cross-registration and quantification of metric distortions in marmoset whole brain histology using diffeomorphic mappings.

Whole brain neuroanatomy using tera-voxel light-microscopic data sets is of much current interest. A fundamental problem in this field is the mapping of individual brain data sets to a reference space. Previous work has not rigorously quantified in-vivo to ex-vivo distortions in brain geometry from tissue processing. Further, existing approaches focus on registering unimodal volumetric data; however, given the increasing interest in the marmoset model for neuroscience research and the importance of addressing individual brain architecture variations, new algorithms are necessary to cross-register multimodal data sets including MRIs and multiple histological series. Here we present a computational approach for same-subject multimodal MRI-guided reconstruction of a series of consecutive histological sections, jointly with diffeomorphic mapping to a reference atlas. We quantify the scale change during different stages of brain histological processing using the Jacobian determinant of the diffeomorphic transformations involved. By mapping the final image stacks to the ex-vivo post-fixation MRI, we show that (a) tape-transfer assisted histological sections can be reassembled accurately into 3D volumes with a local scale change of 2.0 ± 0.4% per axis dimension; in contrast, (b) tissue perfusion/fixation as assessed by mapping the in-vivo MRIs to the ex-vivo post fixation MRIs shows a larger median absolute scale change of 6.9 ± 2.1% per axis dimension. This is the first systematic quantification of local metric distortions associated with whole-brain histological processing, and we expect that the results will generalize to other species. These local scale changes will be important for computing local properties to create reference brain maps.

Relation of koniocellular layers of dorsal lateral geniculate to inferior pulvinar nuclei in common marmosets.

Traditionally, the dorsal lateral geniculate nucleus (LGN) and the inferior pulvinar (IPul) nucleus are considered as anatomically and functionally distinct thalamic nuclei. However, in several primate species it has also been established that the koniocellular (K) layers of LGN and parts of the IPul have a shared pattern of immunoreactivity for the calcium-binding protein calbindin. These calbindin-rich cells constitute a thalamic matrix system which is implicated in thalamocortical synchronisation. Further, the K layers and IPul are both involved in visual processing and have similar connections with retina and superior colliculus. Here, we confirmed the continuity between calbindin-rich cells in LGN K layers and the central lateral division of IPul (IPulCL) in marmoset monkeys. By employing a high-throughput neuronal tracing method, we found that both the K layers and IPulCL form comparable patterns of connections with striate and extrastriate cortices; these connections are largely different to those of the parvocellular and magnocellular laminae of LGN. Retrograde tracer-labelled cells and anterograde tracer-labelled axon terminals merged seamlessly from IPulCL into LGN K layers. These results support continuity between LGN K layers and IPulCL, providing an anatomical basis for functional congruity of this region of the dorsal thalamic matrix and calling into question the traditional segregation between LGN and the inferior pulvinar nucleus.

A high-throughput neurohistological pipeline for brain-wide mesoscale connectivity mapping of the common marmoset.

Understanding the connectivity architecture of entire vertebrate brains is a fundamental but difficult task. Here we present an integrated neuro-histological pipeline as well as a grid-based tracer injection strategy for systematic mesoscale connectivity mapping in the common marmoset (Callithrix jacchus). Individual brains are sectioned into ~1700 20 µm sections using the tape transfer technique, permitting high quality 3D reconstruction of a series of histochemical stains (Nissl, myelin) interleaved with tracer labeled sections. Systematic in-vivo MRI of the individual animals facilitates injection placement into reference-atlas defined anatomical compartments. Further, by combining the resulting 3D volumes, containing informative cytoarchitectonic markers, with in-vivo and ex-vivo MRI, and using an integrated computational pipeline, we are able to accurately map individual brains into a common reference atlas despite the significant individual variation. This approach will facilitate the systematic assembly of a mesoscale connectivity matrix together with unprecedented 3D reconstructions of brain-wide projection patterns in a primate brain.

Diffeomorphic Upsampling of Serially Acquired Sparse 2D Cross-Sections in Cardiac MRI.

In this paper, we propose a new technique for interpolating shapes in order to upsample a sparsely acquired serial-section image stack. The method is based on a maximum a posteriori estimation strategy which models neighboring sections as observations of random deformations of an image to be estimated. We show the computation of diffeomorphic trajectories between observed sections and define estimated upsampled image sections as a Jacobian-weighted sum of flowing images at corresponding distances along those trajectories. We apply this methodology to upsample stacks of sparse 2D magnetic resonance cross-sections through live mouse hearts. We show that the proposed method results in smoother and more accurate reconstructions over linear interpolation, and report a Dice coefficient of 0.8727 against ground truth segmentations in our dataset and statistically significant improvements in both left ventricular segmentation accuracy and image intensity estimates.

On variational solutions for whole brain serial-section histology using a Sobolev prior in the computational anatomy random orbit model.

This paper presents a variational framework for dense diffeomorphic atlas-mapping onto high-throughput histology stacks at the 20 µm meso-scale. The observed sections are modelled as Gaussian random fields conditioned on a sequence of unknown section by section rigid motions and unknown diffeomorphic transformation of a three-dimensional atlas. To regularize over the high-dimensionality of our parameter space (which is a product space of the rigid motion dimensions and the diffeomorphism dimensions), the histology stacks are modelled as arising from a first order Sobolev space smoothness prior. We show that the joint maximum a-posteriori, penalized-likelihood estimator of our high dimensional parameter space emerges as a joint optimization interleaving rigid motion estimation for histology restacking and large deformation diffeomorphic metric mapping to atlas coordinates. We show that joint optimization in this parameter space solves the classical curvature non-identifiability of the histology stacking problem. The algorithms are demonstrated on a collection of whole-brain histological image stacks from the Mouse Brain Architecture Project.

Monitored Anesthesia Care for the Acute Ischemic Stroke Patient with End-stage Pulmonary Disease.

The majority of patients who suffer acute ischemic stroke (AIS) from large vessel occlusion are at a significant risk for disability or death. Because patients on veno-arterial extracorporeal membrane oxygenation (VA ECMO) are therapeutically anticoagulated, intravenous recombinant tissue plasminogen activator is contraindicated. For AIS management, these patients must undergo emergent intra-arterial therapy. Presented is a patient on VA ECMO who subsequently suffered a large vessel embolic stroke requiring emergent surgical intervention. The decision by our anesthetic team to perform the procedure under monitored anesthesia care is discussed.

Personalized, assessment-based, and tiered medical education curriculum integrating treatment guidelines for atrial fibrillation.

BACKGROUND: This continuing medical education (CME) curriculum utilizes the Learner Assessment Platform (LAP), providing learners with personalized educational pathways related to atrial fibrillation treatment. HYPOTHESIS: There are improvements in knowledge among physician learners after CME, especially among LAP learners. METHODS: In this LAP-based curriculum, an evaluation of learner deficits on designated learning objectives was conducted in tier 1 and used to direct learners to individualized tier 2 activities. Performance was assessed across learner tracks from baseline to learners' final intervention. Retention data were measured by the postcurriculum assessment, completed 8 weeks after the learners last intervention. Additionally, each activity included a unique matched set of pretest and post-test questions assessing the 4 learner domains: knowledge, competence, confidence, and practice patterns. RESULTS: Significant learner improvement was measured across the curriculum over all 4 learner-domains: 48% (P < 0.0005), 78% (P < 0.0005), 21% (P < 0.0005), and 20% (P < 0.0005) improvements for knowledge, competence, confidence, and practice, respectively. Significant gains in participant performance scores (28% increase, P < 0.0005) by the final activity was observed. Learners who participated in the LAP (N = 989) demonstrated greater improvement in performance from baseline compared to non-LAP learners (41% increase for LAP vs 23% and 26% increase for non-LAP learners who completed 1 (N = 1899) or ≥2 (N = 533) activities, respectively, P = 0.003). CONCLUSIONS: The participant population (N = 3421) achieved statistically significant improvement across the curriculum, with LAP learners showing greater performance gains compared to non-LAP learners. These findings support the value of the LAP methodology in providing a cumulative and individualized CME experience.

Ketofol for monitored anesthesia care in shoulder arthroscopy and labral repair: a case report.

A 21-year-old male (body mass index: 28.3) with a history of asthma and reactive airway disease since childhood underwent left shoulder arthroscopy and labral repair surgery under monitored anesthesia care. Because the procedure was performed in the beach chair position, access to the patient's airway was limited throughout. To avoid general anesthesia and to limit potential complications associated with monitored anesthesia care, a ketofol admixture was used. This case demonstrates that, in conjunction with regional anesthesia, ketofol may be an acceptable alternative to propofol for maintenance in outpatient orthopedic procedures.

Histocompatibility and in vivo signal throughput for PEDOT, PEDOP, P3MT, and polycarbazole electrodes.

Stimulation and recording of the in vivo electrical activity of neurons are critical functions in contemporary biomedical research and in treatment of patients with neurological disorders. The electrodes presently in use tend to exhibit short effective lifespans due to degradation of signal transmission resulting from the tissue response at the electrode-brain interface, with signal throughput suffering most at the low frequencies relevant for biosignals. To overcome these limitations, new electrode designs to minimize tissue responses, including conducting polymers (CPs) have been explored. Here, we report the short-term histocompatibility and signal throughput results comparing platinum and CP-modified platinum electrodes in a Sprague-Dawley rat model. Two of the polymers tested elicited significantly decreased astrocyte responses relative to platinum. These polymers also showed improved signal throughput at low frequencies and comparable signal-to-noise ratios during targeted intracranial electroencephalograms. These results suggest that CP electrodes may present viable alternatives to the metal electrodes that are currently in use.

Specialist registrars in acute medicine receiving patients in the resuscitation room: a key component in the training curriculum.

A key component of training in Acute Medicine is the assessment and initial resuscitation of severely ill medical patients. The curriculum for General Internal Medicine (Acute Medicine) states that all specialists in Acute Medicine should attain Level 3 competencies in all emergency presentations.1 Different training programmes have variable exposure to the emergency department, to which the majority of these patients present. One module, currently being developed at City Hospital, Birmingham, is for the Acute Medicine Specialist Registrars (SpRs) to attend all medical alerts in Accident and Emergency (A&E) Department. This means that the SpR works as part of the receiving team, seeing patients first hand, rather than taking secondary referrals. At our hospital over 80% of alerts brought in the resuscitation room are medical emergencies.