Taste buds comprise 50-100 epithelial-derived cells, including glial-like cells (Type I) and two types of receptor cells (Types II and III). All of these taste cells are renewed throughout the life of an organism from a pool of uncommitted basal cells. Immature cells enter the bud at its base, maturing into one of the three differentiated cell types. How taste cells die and/or exit the bud, as well as the role of the glial-like cells in this process, remains unclear. Here we present morphological data obtained through Serial Blockface Scanning Electron Microscopy of murine circumvallate taste buds, revealing taste cells at the end of their life. Cells we identify as dying share morphological features typical of apoptosis: swollen endoplasmic reticulum, large lysosomes, degrading organelles, distended outer nuclear membranes, heterochromatin reorganization, cell shrinkage, and cell and/or nuclear fragmentation. Most early-stage dying cells have Type II cell morphologies, while a few display Type III cell features. Many dying cells maintain contacts with nerve fibers, but those postsynaptic fibers often appear to be nerve fragments, detached from the main trunk of an afferent nerve. Dying cells, like mature Type II and III taste cells, are surrounded by glial-like Type I cells. In many instances, Type I cells appear to be engulfing their dying neighbors, which constitutes a novel, phagocytic role. Surprisingly, virtually no Type I cells display features of apoptosis, although they reportedly have the shortest residence time in taste buds. The ultimate fate of Type I cells therefore remains enigmatic.

Purpose: Mitral Regurgitation (MR) can cause left ventricular dilation (remodeling). Reverse remodeling describes improved volumes after intervention. Reverse remodeling carries favorable prognosis, but not all MitraClip patients undergo reverse remodeling. We hypothesized pre-procedural global longitudinal strain (preGLS) will predict reverse remodeling one-year post MitraClip in all-cause MR patients. Methods: Of the 189 MitraClips performed at our institution between 2007-2019, 57 patients had complete echocardiographic data,. Echocardiograms 0-120 days prior to and 6-24 months after procedure were retrospectively reviewed. Reverse remodeling was defined as reduction in end diastolic volume (EDV). Results: In 20 sample echocardiograms, intra and inter-reader GLS variability was r=0.95 and r=0.90, respectively. Our population consisted of 55.2% female, 12.3% functional , 61.4% degenerative and 26.3% mixed mitral regurgitation. A reduction in EDV was demonstrated in 38 patients (67%). EDV, ESV, LAVi, and RVSP significantly decreased post-clip (all p<0.01) but not LVEF. Regression models showed pre-EDV (p<0.01) and pre-ESV (p<0.01) had significant crude and adjusted linear associations and ?pre-GLS? had a significant crude curvilinear association (linear p=0.04, quadratic p =0.04) with EDV reductions post clip. The curvilinear association showed among lower, more abnormal ?pre-GLS? values, higher ?pre-GLS? was associated with greater reductions in EDV. When adjusted for pre-EDV and pre-ESV, GLS lost significance(linear p=0.29, quadratic p=0.29). Conclusion: Our study shows a majority of MitraClip patients demonstrate reverse remodeling and pre-GLS to be associated with reverse remodeling, though not robustly. A study with larger sample sizes is needed to better define the association.

The nasal epithelium houses a population of solitary chemosensory cells (SCCs). SCCs express bitter taste receptors and taste transduction signaling components and are innervated by peptidergic trigeminal polymo-dal nociceptive nerve fibers. Thus, nasal SCCs respond to bitter compounds, including bacterial metabolites, and these reactions evoke protective respiratory reflexes and innate immune and inflammatory responses. We tested whether SCCs are implicated in aversive behavior to specific inhaled nebulized irritants using a cus-tom-built dual-chamber forced-choice device. The behavior of mice was recorded and analyzed for the time spent in each chamber. Wild-type (WT) mice exhibited an aversion to 10 mM denatonium benzoate (Den) or cy-cloheximide and spent more time in the control (saline) chamber. The SCC-pathway knock-out (KO) mice did not exhibit such an aversion response. The bitter avoidance behavior of WT mice was positively correlated with the concentration increase of Den and the number of exposures. Bitter-ageusic P2X2/3 double KO mice similarly showed an avoidance response to nebulized Den, excluding the taste system's involvement and pointing to an SCC-mediated major contributor to the aversive response. Interestingly, SCC-pathway KO mice showed an attraction to higher Den concentrations; however, chemical ablation of the olfactory epithelium eliminated this attraction attributed to the smell of Den. These results demonstrate that activation of SCCs leads to a rapid aversive response to certain classes of irritants with olfaction, but not gustation, contributing to the avoidance behavior during subsequent irritant exposures. This SCC-mediated avoidance behavior rep-resents an important defense mechanism against the inhalation of noxious chemicals.

Alzheimer’s disease (AD) is a neurodegenerative condition of the central nervous system that affects both the brain and the retina, and can lead to visual impairment. However, the factors that modulate AD pathophysiology leading to the wide range of clinical presentations are not well understood. Notably, traumatic brain injury (TBI), which can arise from sport concussions, military combat and other causes, is associated with a 2.3-fold higher risk of developing AD and AD-related dementias. Yet the pathophysiological link between TBI and AD remains poorly understood. In this study we set out to evaluate the effects of TBI, AD, and their combination, on retinal histopathology, by taking advantage of a transgenic rat model (Tg-F344-AD) shown to recapitulate the main features of human AD pathology, and combining it with a controlled cortical impact paradigm of repetitive mild TBI (rmTBI). Male Tg-F344-AD rats and F344 wild-type controls were aged to 12 months and randomly selected to undergo a two-time unilateral controlled cortical impact (2xCCI; one week apart) that mimics rmTBI, or a sham procedure. The animals were sacrificed at four months post-CCI to evaluate long-term effects of the procedure, and the eyes were collected and analyzed using immunofluorescence and standard histological staining techniques to evaluate Alzheimer’s histopathology. Histopathological analyses at four months post-impact confirm the presence of AD markers in Tg-F344-AD retinas. Moreover, we found that AD increases Aβ deposition and neuroinflammation in the retina, and that TBI enhances the severity of this phenotype by increasing the formation of dense core amyloid plaques. We have developed and characterized a model to study the pathophysiology of AD in relation to rmTBI in the retina, which could lead to better treatments and to the development of retinal biomarkers for improved AD diagnosis.

Whitford, Robert1; Hlaing, Maung2; Badesch, David3; Hountras, Peter4; Salcedo, Ernesto5 Author Information

The prevalence of aortic valve disease, particularly aortic stenosis, is increasing in parallel to the aging of the population, making it the most prevalent form of valvular heart disease. Surgery and percutaneous interventions of the aortic valve are conditional to a comprehensive evaluation of the aortic valve and the left ventricle (LV). Favorable results from aortic valve surgery or intervention are influenced by LV ejection fraction (EF), presence and severity of left ventricular hypertrophy (LVH), LV end-systolic volume (LVESV), degree of leaflet calcification, and trans-aortic valve gradients. Deformation imaging, particularly global longitudinal strain, is evolving as a powerful tool in the evaluation of ventricular function in patients with aortic stenosis. GLS is particularly suited to detect subclinical LV dysfunction, before a drop in LV ejection fraction, providing the opportunity to intervene earlier to prevent serious and permanent LV dysfunction. Similar added value has been demonstrated in the application of GLS in the detection of subclinical LV dysfunction in patients with aortic regurgitation. Very little information exists in the use of GLS in patients with mixed aortic valve disease, providing an opportunity for future research in this important group of patients with aortic valve disease.

Teaching and learning embryology pose challenges due to rapid and complex developmental processes occurring in four-dimensions especially without effective visual aids. Previous research studies have shown that virtual and 3D printed embryo models increase learning outcomes and interest in embryology. One of the most challenging and clinically relevant concepts in embryology is the heart outflow tract septation involving 180-degree spatial rotation and precise alignment of the growing septa that can often go awry, resulting in various congenital cardiac septal defects. Unfortunately, there are no visual aids that effectively demonstrate this complex process in 3D. To that end, a 3D embryonic virtual heart development model (EVH) with interchangeable conotruncal septa (Figure 1) was created and its educational efficacy was tested in a COMIRB exempt (# 20-2124), randomized single blind study with the first-year medical students completing a flipped-classroom embryology active learning event occurring in a virtual platform due to COVID-19 restrictions. As a part of the course requirement, all students first watched a pre-recorded lecture video and completed a quiz on their own before attending the synchronous virtual active learning event. During the active learning event, students were randomized into control or experimental breakout session groups. Experimental breakout session groups (16 groups, n=80) were provided access to the EVH with accompanying prompts designed to reinforce 3D spatial orientation and congenital septal defects demonstrated by the EVH (Figure 2). The control groups (14 groups, n=70) were tasked to complete a similar learning activity but on a different developmental process. All students completed a second quiz and a survey after the active learning event. A Kruskal-Wallis test comparing normalized pre-quiz versus post-quiz results revealed a significant increase on the post-quiz performance in the experimental group (p = 0.0198, df = 3) but not in the control group (p>0.05). Descriptive statistics on quantitative survey data revealed that students positively perceived the educational value of the EVH, especially for demonstrating 3D changes of the normally and abnormally developing outflow tract. Consistently, thematic analysis of the survey comments indicated that the spatial and visual aspects of the EVH demonstrating the congenital defects were perceived as essential. The significantly high learning outcomes immediately after the resource interaction with EVH and the favorability of the EVH warrant a further development and research. Group and virtual classroom effects are other confounds that should be reduced in future studies.

Histology, a pillar of anatomical sciences for both health professional and graduate students, requires sufficient time and practice to develop the necessary visual literacy and skills in synthesis to achieve competency. However, histology contact hours in medical and graduate education have reduced significantly in the past decades due to disseminated curricular changes emphasizing integration of basic sciences, clinical content and self-directed learning. In turn, adjunct online resources have been in steady incline and in the past year, in response to COVID-19, quickly became an essential component of anatomical sciences education following campus closures. Self-directed learning is challenging in normal circumstances as success is impacted by the level of student preparedness and engagement, which in turn can be dependent on the quality of the asynchronous learning resources. Although many online histology resources are available, few are comprehensive and provide step-by-step instruction in identification of structures in tissue slides. In this pilot project, the efficacy of using a commercial online histology (COH) course (DaVinci Academy, Cleveland, OH) as a primary preparatory resource in a graduate histology curriculum implementing a flipped-classroom pedagogy was assessed. During fall 2020 (F2020), first-year graduate students enrolled in a hybrid histology course were required to review learning objectives, read textbook sections, and complete the COH lessons, consisting of complete lectures, lab videos, and quizzes as a set of pre-work to prepare for on-campus and virtual classes. The synchronous class sessions had minimal didactic lectures, but instead had a series of small group active learning tasks. In a COMIRB exempt retrospective study (#20-2891), the assessment outcomes of the F2020 cohort (n=26) were compared to a fall 2019 (F2019) cohort of students (n=25) who completed the identical histology curriculum delivered in a flipped-class style by the same instructor, but without the commercial online histology course. All course quiz and exam scores were compared across the F2019 and F2020 cohorts using a Kruskal Wallis test for non-parametric data. There were no significant differences in assessment outcomes between F2019 and F2020 cohorts (p>0.05). Survey of the F2020 cohort throughout the course revealed consistently high rating of the COH with 80% of students believing the resource improved their ability to read and interpret histology slides. Interestingly, students perceived the lecture and lab videos in the COH delivered by the same in-class instructor to be more valuable than those delivered by a third-party instructor, although the assessment performance was independent of the online instructor (p>0.05). The results suggest that the online histology course can be an effective asynchronous learning resource for a histology course, allowing for more efficient use of synchronous class time to support a higher taxonomy of learning.

Background: Filamin C truncating variants ( FLNCtv ) cause a form of arrhythmogenic cardiomyopathy: the mode of presentation, natural history, and risk stratification of FLNCtv remain incompletely explored. We aimed to develop a risk profile for refractory heart failure and life-threatening arrhythmias in a multicenter cohort of FLNCtv carriers. Methods: FLNCtv carriers were identified from 10 tertiary care centers for genetic cardiomyopathies. Clinical and outcome data were compiled. Composite outcomes were all-cause mortality/heart transplantation/left ventricle assist device (D/HT/LVAD), nonarrhythmic death/HT/LVAD, and sudden cardiac death/major ventricular arrhythmias. Previously established cohorts of 46 patients with LMNA and 60 with DSP -related arrhythmogenic cardiomyopathies were used for prognostic comparison. Results: Eighty-five patients carrying FLNCtv were included (42±15 years, 53% men, 45% probands). Phenotypes were heterogeneous at presentation: 49% dilated cardiomyopathy, 25% arrhythmogenic left dominant cardiomyopathy, 3% arrhythmogenic right ventricular cardiomyopathy. Left ventricular ejection fraction was <50% in 64% of carriers and 34% had right ventricular fractional area changes (RVFAC=(right ventricular end-diastolic area – right ventricular end-systolic area)/right ventricular end-diastolic area) <35%. During follow-up (median time 61 months), 19 (22%) carriers experienced D/HT/LVAD, 13 (15%) experienced nonarrhythmic death/HT/LVAD, and 23 (27%) experienced sudden cardiac death/major ventricular arrhythmias. The sudden cardiac death/major ventricular arrhythmias incidence of FLNCtv carriers did not significantly differ from LMNA carriers and DSP carriers. In FLNCtv carriers, left ventricular ejection fraction was associated with the risk of D/HT/LVAD and nonarrhythmic death/HT/LVAD. Conclusions: Among patients referred to tertiary referral centers, FLNCtv arrhythmogenic cardiomyopathy is phenotypically heterogeneous and characterized by a high risk of life-threatening arrhythmias, which does not seem to be associated with the severity of left ventricular dysfunction.

In human development, normal formation of the body cavity involves intricate interplay of tissues folding from a flat disc form into a complex tube‐within‐tube 3D structure over a short period of time. Understanding the normal body cavity formation is imperative to understanding anatomic organizations, variations and congenital conditions. Unfortunately, resources that effectively demonstrate changing body cavity anatomy during the folding process are sparse and their educational effectiveness is not well understood. Therefore, an interactive digital resource, the “Virtual Folding Embryo” (VFE), demonstrating the 4‐dimensional transformation of the folding embryo (Figure 1) was created and its educational value was assessed in a COMIRB exempt (#20‐2125) randomized single blind study. As a part of the flipped curriculum, 155 first‐year medical students enrolled in an integrated anatomy course first viewed a pre‐recorded lecture on embryology of the thorax then completed a quiz to test their foundational knowledge before attending a synchronous online active learning session conducted on the Zoom platform. Students were randomized into small breakout groups of 4‐5 students and half of the groups were given access to the VFE (Figure 2), while the other half were given access to a resource demonstrating a different embryonic process. After 15 minutes, all students completed a quiz and an optional survey.

Alzheimer’s disease (AD) is a neurodegenerative condition that affects 6.2 million people age 65 and older in the U.S. alone, and is the leading cause of dementia. Moreover, AD can lead to visual impairment, and AD histopathology also manifests in the retina. However, the factors that modulate AD pathophysiology and lead to varied susceptibility and presentation in the population are not well understood. In this context, traumatic brain injury (TBI), which can arise from sport concussions, military combat, and other causes, is associated with a 2.3-fold higher risk of developing AD and AD-related dementias (ADRD). Thus, we set out to evaluate the effects of TBI, AD, and their combination, on retinal histopathology. Several animal models have been developed to investigate the mechanisms underlying AD, but many have been limited by imperfect recapitulation of human pathology, and no model of TBI-associated AD (AD-TBI) has been characterized. To address this gap, we generated an innovative model of AD-TBI by taking advantage of a transgenic rat model (Tg-F344-AD) shown to recapitulate the main features of human AD pathology, and combining it with a twotime unilateral controlled cortical impact paradigm to mimic repetitive mild TBI (rmTBI). Histopathological analyses at four months post-impact confirm the presence of AD markers in transgenic retinas, and an increased severity of AD pathology due to TBI. Together, these results contribute to our understanding of the effects of TBI on AD retinopathy, with implications for patient care and therapeutic development.

3D TEE is often used to guide structural heart disease interventions (SHDI). Depth perception plays a crucial role for navigation and placement of interventional devices. In this study, a novel rendering technique, mimicking the normal human visual world, called pseudo-illumination is evaluated and

Introduction: Transseptal puncture (TSP) is an essential step in percutaneous structural heart interventions, such as the MitraClip® procedure. Radiation exposure is a hazard for Interventional Cardiologists, Echocardiographers, and patients. Advancements in shielding and radiation equipment have reduced this exposure, but further reduction is desired. EchoNav® (Philips) fuses fluoroscopy and echocardiography resulting in a single multimodal image display. Prior studies demonstrated reduced time to TSP with use of EchoNav® but failed to show significant reduction in radiation. We hypothesized that increased experience using EchoNav® would further decrease TSP time and radiation dose. Methods: Single center, retrospective analysis evaluated 202 patients undergoing MitraClip® procedure pre and post-EchoNav® from 6/2010 to 12/2019: 8 pre and 194 post. We measured time to TSP and radiation exposure by Air Kerma and dose area product (DAP). For the post-EchoNav® cases, we evaluated these variables by 2-year time periods to examine change over time. Results: Comparing pre and post-EchoNav ® procedures, time to TSP was non-significantly reduced overall (40.00±14.95 to 33.63±15.92, p=0.23). However, post-EchoNav ® had a decreasing trend (48.00±28.39, 43.47±15.86, 28.45±11.94, 27.55±10.64; R 2 =0.89, p =0.009) that was significantly less than pre-EchoNav ® by the third time period (40.00±14.95 vs 28.45±11.94, p=0.05) and remained less in the fourth (40.00±14.95 vs 27.55±10.64, p=0.03). Radiation was reduced post-EchoNav ® by both DAP (264.52±150.03 to 109.00±97.68) (p=0.02) and Air Kerma (1472.92±883.50 to 582.49±485.28) (p=0.05). Significant radiation reduction occurred by the third time period for Air Kerma (1472.92±883.50 vs 494.12±413,79, p=0.03) and second time period for DAP (264.52±150.03 to 127.51±110.35, p=0.03). Conclusion: These results suggest that use of EchoNav® has a learning curve, but ultimately reduces time to TSP and radiation.

Increased catheter‐based interventions in congenital and structural heart disease require imaging modalities to be oriented in the same visual perspective. The use of echocardiography–fluoroscopy fusion (EFF) imaging has been developed for better characterization of complex anatomy and to facilitate key steps in interventional procedures. This review will detail the technology behind EFF, the differences between the two ultrasound fusion systems, and essential features of EFF imaging in congenital and structural heart disease interventions.

Catheter interventions in congenital and structural heart disease have increased in complexity and rely on advanced transesophageal echocardiography (TEE) guidance. The different spatial reference frames of TEE and fluoroscopy necessitate mental co-registration of the images during the procedure.

With the increasing frequency of catheter-based interventions in congenital heart disease and structural heart disease, the use of fusion imaging has become a major enhancement for understanding complex anatomy and facilitating key steps in interventional procedures. Because transesophageal echocardiography and fluoroscopy are displayed in different visual perspectives, the interventional cardiologist must mentally reregister the images from the two modalities during the procedure. Echocardiography-fluoroscopy fusion (EFF) imaging displays the x-ray and ultrasound overlay images in the same visual perspective. This new technology allows for enhanced team communication, improved visual guidance, and more efficient navigation. The purpose of this review is to describe the EFF imaging technology, current uses of EFF imaging in congenital and structural heart disease, and future directions that will enhance this unique imaging technology to guide interventional procedures.

Mucins are a key component of the surface mucus overlying airway epithelium. Given the different functions of the olfactory and respiratory epithelia, we hypothesized that mucins would be differentially expressed between these 2 areas. Secondarily, we evaluated for potential changes in mucin expression with radiation exposure, given the clinical observations of nasal dryness, altered mucus rheology, and smell loss in radiated patients. Immunofluorescence staining was performed to evaluate expression of mucins 1, 2, 5AC, and 5B in nasal respiratory and olfactory epithelia of control mice and 1 week after exposure to 8 Gy of radiation. Mucins 1, 5AC, and 5B exhibited differential expression patterns between olfactory and respiratory epithelium (RE) while mucin 2 showed no difference. In the olfactory epithelium (OE), mucin 1 was located in a lattice-like pattern around gaps corresponding to dendritic knobs of olfactory sensory neurons, whereas in RE it was intermittently expressed by surface goblet cells. Mucin 5AC was expressed by subepithelial glands in both epithelial types but to a higher degree in the OE. Mucin 5B was expressed by submucosal glands in OE and by surface epithelial cells in RE. At 1-week after exposure to single-dose 8 Gy of radiation, no qualitative effects were seen on mucin expression. Our findings demonstrate that murine OE and RE express mucins differently, and characteristic patterns of mucins 1, 5AC, and 5B can be used to define the underlying epithelium. Radiation (8 Gy) does not appear to affect mucin expression at 1 week.LEVEL OF EVIDENCE:N/A (Basic Science Research).IACUC-approved study [Protocol 200065].

BACKGROUND:The effects of edge-to-edge percutaneous mitral valve repair on the shape and size of the mitral annulus and its relation to mitral regurgitation (MR) have not been well characterized. We evaluated acute changes in mitral annular shape and dimensions, and their effect on MR severity, in patients with functional and degenerative MR following MitraClip® .METHODS:Patients that underwent MitraClip® between January 2013 and May 2016 at our institution were retrospectively reviewed.EXCLUSIONS:inadequate images, prior mitral valve repair, and rapid atrial fibrillation. Intra-procedure TEE 3D images acquired prior to and after implantation of MitraClip® were analyzed using software to model the mitral valve apparatus.RESULTS:Of seventy-eight patients that underwent MitraClip® procedure, 60 were eligible. Mean age was 78.3 ± 11 years. Severe MR (4+) was present in 37 patients, moderately/severe MR (3+) in 23. All patients achieved MR reduction to ≤2. 3D annular circumference, bicommissural diameter, and anteroposterior diameter had a significant size reduction after MitraClip® . None of the mitral annular measures had significantly different mean change between the large and small MR change groups at the 0.05 significance level.CONCLUSIONS:In patients with functional or degenerative MR, the MitraClip® significantly affect mitral annular dimensions; however, these changes do not correlate with the immediate MR reduction.