The ototoxic drug cisplatin localises to stress granules altering their dynamics and composition.

Cisplatin is an effective platinum-based chemotherapeutic with several side effects, including ototoxicity. Cochlear cells have low rates of proliferation yet are highly susceptible to cisplatin. We hypothesised that cisplatin ototoxicity might be caused by cisplatin-protein interactions rather than cisplatin-DNA interactions. Two known cisplatin-binding proteins are involved in the stress granule (SG) response. SGs are a pro-survival mechanism involving formation of transient ribonucleoprotein complexes during stress. We examined the effects of cisplatin on SG dynamics and composition in cell lines derived from the cochlea and retinal pigment epithelium. Cisplatin-induced SGs are significantly diminished in size and quantity compared to arsenite-induced SGs and are persistent after 24 h recovery. Additionally, cisplatin pre-treated cells were unable to form a typical SG response to subsequent arsenite stress. Cisplatin-induced SGs had significant reductions in the sequestration of eIF4G and the proteins RACK1 and DDX3X. Live-cell imaging of Texas Red-conjugated cisplatin revealed its localisation to SGs and retention for at least 24 h. We show cisplatin-induced SGs have impaired assembly, altered composition and are persistent, providing evidence of an alternate mechanism for cisplatin-induced ototoxicity via an impaired SG response.

Functional P2X7 Receptors in the Auditory Nerve of Hearing Rodents Localize Exclusively to Peripheral Glia.

P2X7 receptors (P2X7Rs) are associated with numerous pathophysiological mechanisms, and this promotes them as therapeutic targets for certain neurodegenerative conditions. However, the identity of P2X7R-expressing cells in the nervous system remains contentious. Here, we examined P2X7R functionality in auditory nerve cells from rodents of either sex, and determined their functional and anatomic expression pattern. In whole-cell recordings from rat spiral ganglion cultures, the purinergic agonist 2',3'-O-(4-benzoylbenzoyl)-ATP (BzATP) activated desensitizing currents in spiral ganglion neurons (SGNs) but non-desensitizing currents in glia that were blocked by P2X7R-specific antagonists. In imaging experiments, BzATP gated sustained Ca2+ entry into glial cells. BzATP-gated uptake of the fluorescent dye YO-PRO-1 was reduced and slowed by P2X7R-specific antagonists. In rats, P2X7Rs were immuno-localized predominantly within satellite glial cells (SGCs) and Schwann cells (SCs). P2X7R expression was not detected in the portion of the auditory nerve within the central nervous system. Mouse models allowed further exploration of the distribution of cochlear P2X7Rs. In GENSAT reporter mice, EGFP expression driven via the P2rx7 promoter was evident in SGCs and SCs but was undetectable in SGNs. A second transgenic model showed a comparable cellular distribution of EGFP-tagged P2X7Rs. In wild-type mice the discrete glial expression was confirmed using a P2X7-specific nanobody construct. Our study shows that P2X7Rs are expressed by peripheral glial cells, rather than by afferent neurons. Description of functional signatures and cellular distributions of these enigmatic proteins in the peripheral nervous system (PNS) will help our understanding of ATP-dependent effects contributing to hearing loss and other sensory neuropathies.SIGNIFICANCE STATEMENT P2X7 receptors (P2X7Rs) have been the subject of much scrutiny in recent years. They have been promoted as therapeutic targets in a number of diseases of the nervous system, yet the specific cellular location of these receptors remains the subject of intense debate. In the auditory nerve, connecting the inner ear to the brainstem, we show these multimodal ATP-gated channels localize exclusively to peripheral glial cells rather than the sensory neurons, and are not evident in central glia. Physiologic responses in the peripheral glia display classical hallmarks of P2X7R activation, including the formation of ion-permeable and also macromolecule-permeable pores. These qualities suggest these proteins could contribute to glial-mediated inflammatory processes in the auditory periphery under pathologic disease states.

An Analysis of US Academic Medical Center Websites: Usability Study.

BACKGROUND: Health care organizations are tasked with providing web-based health resources and information. Usability refers to the ease of user experience on a website. In this study, we conducted a usability analysis of academic medical centers in the United States, which, to the best of our knowledge, has not been previously carried out. OBJECTIVE: The primary aims of the study were to the following: (1) adapt a preexisting usability scoring methodology to academic medical centers; (2) apply and test this methodology on a sample set of academic medical center websites; and (3) make recommendations from these results on potential areas of improvements for our sample of academic medical center websites. METHODS: All website usability testing took place from June 1, 2020, to December 15, 2020. We replicated a methodology developed in previous literature and applied it to academic medical centers. Our sample included 73 US academic medical centers. Usability was split into four broad categories: accessibility (the ability of those with low levels of computer literacy to access and navigate the hospital's website); marketing (the ability of websites to be found through search engines and the relevance of descriptions to the links provided); content quality (grammar, frequency of information updates, material relevancy, and readability); and technology (download speed, quality of the programming code, and website infrastructure). Using these tools, we scored each website in each category. The composite of key factors in each category contributed to an overall "general usability" score for each website. An overall score was then calculated by applying a weighted percentage across all factors and was used for the final "overall usability" ranking. RESULTS: The category with the highest average score was technology, with a 0.82 (SD 0.068, SE 0.008). The lowest-performing category was content quality, with an average of 0.22 (SD 0.069, SE 0.008). As these numbers reflect weighted percentages as an integer, the higher the score, the greater the overall usability in that category. CONCLUSIONS: Our data suggest that technology, on average, was the highest-scored variable among academic medical center websites. Because website functionality is essential to a user's experience, it is justified that academic medical centers invest in optimal website performance. The overall lowest-scored variable was content quality. A potential reason for this may be that academic medical center websites are usually larger in size, making it difficult to monitor the increased quantity of content. An easy way to improve this variable is to conduct more frequent website audits to assess readability, grammar, and relevance. Marketing is another area in which these organizations have potential for improvement. Our recommendation is that organizations utilize search engine optimization techniques to improve their online visibility and discoverability.

Intercellular Ca2+ signalling in the adult mouse cochlea.

KEY POINTS: Intercellular Ca2+ waves are increases in cytoplasmic Ca2+ levels that propagate between cells. Periodic Ca2+ waves have been linked to gene regulation and are thought to play a crucial role in the development of our hearing epithelium, the organ of Corti and the acquisition of hearing. We observed regular periodic intercellular Ca2+ waves in supporting cells of an ex vivo preparation of the adult mouse organ of Corti, and these waves were found to propagate independently of extracellular ATP and were inhibited by the gap junction blockers 1-octanol and carbenoxolone. Our results establish that the existence of periodic Ca2+ waves in the organ of Corti is not restricted to the prehearing period. ABSTRACT: We have investigated wave-like cytoplasmic calcium (Ca2+ ) signalling in an ex vivo preparation of the adult mouse organ of Corti. Two types of intercellular Ca2+ waves that differ in propagation distance and speed were observed. One type was observed to travel up to 100 µm with an average velocity of 7 µm/s. Such waves were initiated by local tissue damage in the outer hair cell region. The propagation distance was decreased when the purinergic receptor antagonists pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS; 50 µm) or suramin (150 µm) were added to the extracellular buffer. Immunocytochemical analysis and experiments with calcium indicator dyes showed that both P2X and P2Y receptors were present in supporting cells. A second class of waves identified to travel longitudinally along the organ of Corti propagated at a lower velocity of 1-3 µm/s. These 'slow' Ca2+ waves were particularly evident in the inner sulcus and Deiters' cells. They travelled for distances of up to 500 µm. The slow Ca2+ signalling varied periodically (approximately one wave every 10 min) and was maintained for more than 3 h. The slow waves were not affected by apyrase, or by the P2 receptor agonists suramin (150 µm) or PPADS (50 µm) but were blocked by the connexin channel blockers octanol (1 mm) and carbenoxolone (100 µm). It is proposed that the observed Ca2+ waves might be a physiological response to a change in extracellular environment and may be involved in critical gene regulation activities in the supporting cells of the cochlea.

Perinatal Ischemia Alters Global Expression of Synaptosomal Proteins Critical for Neural Plasticity in the Developing Mouse Brain.

Ischemic perinatal stroke (IPS) affects 1 in 2,300-5,000 live births. Despite a survival rate >95%, approximately 60% of IPS infants develop motor and cognitive impairments. Given the importance of axonal growth and synaptic plasticity in neurocognitive development, our objective was to identify the molecular pathways underlying IPS-associated synaptic dysfunction using a mouse model. IPS was induced by unilateral ligation of the common carotid artery of postnatal day 10 (P10) mice. Five days after ischemia, sensorimotor and motor functions were assessed by vibrissae-evoked forepaw placement and the tail suspension test respectively, showing evidence of greater impairments in male pups than in female pups. Twenty-four hours after ischemia, both hemispheres were collected and synaptosomal proteins then prepared for quantification, using isobaric tags for relative and absolute quantitation. Seventy-two of 1,498 qualified proteins were altered in the ischemic hemisphere. Ingenuity Pathway Analysis was used to map these proteins onto molecular networks indicative of reduced neuronal proliferation, survival, and synaptic plasticity, accompanied by reduced PKCα signaling in male, but not female, pups. These effects also occurred in the non-ischemic hemisphere when compared with sham controls. The altered signaling effects may contribute to the sex-specific neurodevelopmental dysfunction following IPS, highlighting potential pathways for targeting during treatment.

Planar polarization of the atypical myosin Dachs orients cell divisions in Drosophila.

Tissues can grow in a particular direction by controlling the orientation of cell divisions. This phenomenon is evident in the developing Drosophila wing epithelium, where the tissue becomes elongated along the proximal-distal axis. We show that orientation of cell divisions in the wing requires planar polarization of an atypical myosin, Dachs. Our evidence suggests that Dachs constricts cell-cell junctions to alter the geometry of cell shapes at the apical surface, and that cell shape then determines the orientation of the mitotic spindle. Using a computational model of a growing epithelium, we show that polarized cell tension is sufficient to orient cell shapes, cell divisions, and tissue growth. Planar polarization of Dachs is ultimately oriented by long-range gradients emanating from compartment boundaries, and is therefore a mechanism linking these gradients with the control of tissue shape.

Generation of sensory hair cells by genetic programming with a combination of transcription factors.

Mechanosensory hair cells (HCs) are the primary receptors of our senses of hearing and balance. Elucidation of the transcriptional networks regulating HC fate determination and differentiation is crucial not only to understand inner ear development but also to improve cell replacement therapies for hearing disorders. Here, we show that combined expression of the transcription factors Gfi1, Pou4f3 and Atoh1 can induce direct programming towards HC fate, both during in vitro mouse embryonic stem cell differentiation and following ectopic expression in chick embryonic otic epithelium. Induced HCs (iHCs) express numerous HC-specific markers and exhibit polarized membrane protrusions reminiscent of stereociliary bundles. Transcriptome profiling confirms the progressive establishment of a HC-specific gene signature during in vitro iHC programming. Overall, this work provides a novel approach to achieve robust and highly efficient HC production in vitro, which could be used as a model to study HC development and to drive inner ear HC regeneration.

Live-cell delamination counterbalances epithelial growth to limit tissue overcrowding.

The development and maintenance of an epithelium requires finely balanced rates of growth and cell death. However, the mechanical and biochemical mechanisms that ensure proper feedback control of tissue growth, which when deregulated contribute to tumorigenesis, are poorly understood. Here we use the fly notum as a model system to identify a novel process of crowding-induced cell delamination that balances growth to ensure the development of well-ordered cell packing. In crowded regions of the tissue, a proportion of cells undergo a serial loss of cell-cell junctions and a progressive loss of apical area, before being squeezed out by their neighbours. This path of delamination is recapitulated by a simple computational model of epithelial mechanics, in which stochastic cell loss relieves overcrowding as the system tends towards equilibrium. We show that this process of delamination is mechanistically distinct from apoptosis-mediated cell extrusion and precedes the first signs of cell death. Overall, this analysis reveals a simple mechanism that buffers epithelia against variations in growth. Because live-cell delamination constitutes a mechanistic link between epithelial hyperplasia and cell invasion, this is likely to have important implications for our understanding of the early stages of cancer development.

Epithelial repair is a two-stage process driven first by dying cells and then by their neighbours.

Epithelial cells maintain an essential barrier despite continuously undergoing mitosis and apoptosis. Biological and biophysical mechanisms have evolved to remove dying cells while maintaining that barrier. Cell extrusion is thought to be driven by a multicellular filamentous actin ring formed by neighbouring cells, the contraction of which provides the mechanical force for extrusion, with little or no contribution from the dying cell. Here, we use live confocal imaging, providing time-resolved three-dimensional observations of actomyosin dynamics, to reveal new mechanical roles for dying cells in their own extrusion from monolayers. Based on our observations, the clearance of dying cells can be subdivided into two stages. The first, previously unidentified, stage is driven by the dying cell, which exerts tension on its neighbours through the action of a cortical contractile F-actin and myosin ring at the cell apex. The second stage, consistent with previous studies, is driven by a multicellular F-actin ring in the neighbouring cells that moves from the apical to the basal plane to extrude the dying cell. Crucially, these data reinstate the dying cell as an active physical participant in cell extrusion.

Delta-like 1 and lateral inhibition during hair cell formation in the chicken inner ear: evidence against cis-inhibition.

The formation of the salt-and-pepper mosaic of hair cells and supporting cells in the sensory epithelia of the inner ear is regulated by Notch signalling and lateral inhibition, but the dynamics of this process and precise mode of action of delta-like 1 (Dll1) in this context are unclear. Here, we transfected the chicken inner ear with a fluorescent reporter that includes elements of the mammalian Hes5 promoter to monitor Notch activity in the developing sensory patches. The Hes5 reporter was active in proliferating cells and supporting cells, and Dll1 expression was highest in prospective hair cells with low levels of Notch activity, which occasionally contacted more differentiated hair cells. To investigate Dll1 functions we used constructs in which Dll1 expression was either constitutive, regulated by the Hes5 promoter, or induced by doxycycline. In support of the standard lateral inhibition model, both continuous and Hes5-regulated expression of Dll1 promoted hair cell differentiation cell-autonomously (in cis) and inhibited hair cell formation in trans. However, some hair cells formed despite contacting Dll1-overexpressing cells, suggesting that some progenitor cells are insensitive to lateral inhibition. This is not due to the cis-inhibition of Notch activity by Dll1 itself, as induction of Dll1 did not cell-autonomously reduce the activity of the Hes5 reporter in progenitor and supporting cells. Altogether, our results show that Dll1 functions primarily in trans to regulate hair cell production but also that additional mechanisms operate downstream of lateral inhibition to eliminate patterning errors in the sensory epithelia of the inner ear.

Caprin-1 is a target of the deafness gene Pou4f3 and is recruited to stress granules in cochlear hair cells in response to ototoxic damage.

The POU4 family of transcription factors are required for survival of specific cell types in different sensory systems. Pou4f3 is essential for the survival of auditory sensory hair cells and several mutations in human POU4F3 cause hearing loss. Thus, genes regulated by Pou4f3 are likely to be essential for hair cell survival. We performed a subtractive hybridisation screen in an inner-ear-derived cell line to find genes with differential expression in response to changes in Pou4f3 levels. The screen identified the stress-granule-associated protein Caprin-1 as being downregulated by Pou4f3. We demonstrated that this regulation occurs through the direct interaction of Pou4f3 with binding sites in the Caprin-1 5' flanking sequence, and describe the expression pattern of Caprin-1 mRNA and protein in the cochlea. Moreover, we found Caprin-1-containing stress granules are induced in cochlear hair cells following aminoglycoside-induced damage. This is the first report of stress granule formation in mammalian hair cells and suggests that the formation of Caprin-1-containing stress granules is a key damage response to a clinically relevant ototoxic agent. Our results have implications for the understanding of aminoglycoside-induced hearing loss and provide further evidence that stress granule formation is a fundamental cellular stress response.

The origin of spontaneous activity in the developing auditory system.

Spontaneous activity in the developing auditory system is required for neuronal survival as well as the refinement and maintenance of tonotopic maps in the brain. However, the mechanisms responsible for initiating auditory nerve firing in the absence of sound have not been determined. Here we show that supporting cells in the developing rat cochlea spontaneously release ATP, which causes nearby inner hair cells to depolarize and release glutamate, triggering discrete bursts of action potentials in primary auditory neurons. This endogenous, ATP-mediated signalling synchronizes the output of neighbouring inner hair cells, which may help refine tonotopic maps in the brain. Spontaneous ATP-dependent signalling rapidly subsides after the onset of hearing, thereby preventing this experience-independent activity from interfering with accurate encoding of sound. These data indicate that supporting cells in the organ of Corti initiate electrical activity in auditory nerves before hearing, pointing to an essential role for peripheral, non-sensory cells in the development of central auditory pathways.

An emerging role for stress granules in neurodegenerative disease and hearing loss.

Stress granules (SGs) are membrane-less cytosolic assemblies that form in response to stress (e.g., heat, oxidative stress, hypoxia, viral infection and UV). Composed of mRNA, RNA binding proteins and signalling proteins, SGs minimise stress-related damage and promote cell survival. Recent research has shown that the stress granule response is vital to the cochlea's response to stress. However, emerging evidence suggests stress granule dysfunction plays a key role in the pathophysiology of multiple neurodegenerative diseases, several of which present with hearing loss as a symptom. Hearing loss has been identified as the largest potentially modifiable risk factor for dementia. The underlying reason for the link between hearing loss and dementia remains to be established. However, several possible mechanisms have been proposed including a common pathological mechanism. Here we will review the role of SGs in the pathophysiology of neurodegenerative diseases and explore possible links and emerging evidence that they may play an important role in maintenance of hearing and may be a common mechanism underlying age-related hearing loss and dementia.

Targeted deletion of the RNA-binding protein Caprin1 leads to progressive hearing loss and impairs recovery from noise exposure in mice.

Cell cycle associated protein 1 (Caprin1) is an RNA-binding protein that can regulate the cellular post-transcriptional response to stress. It is a component of both stress granules and neuronal RNA granules and is implicated in neurodegenerative disease, synaptic plasticity and long-term memory formation. Our previous work suggested that Caprin1 also plays a role in the response of the cochlea to stress. Here, targeted inner ear-deletion of Caprin1 in mice leads to an early onset, progressive hearing loss. Auditory brainstem responses from Caprin1-deficient mice show reduced thresholds, with a significant reduction in wave-I amplitudes compared to wildtype. Whilst hair cell structure and numbers were normal, the inner hair cell-spiral ganglion neuron (IHC-SGN) synapse revealed abnormally large post-synaptic GluA2 receptor puncta, a defect consistent with the observed wave-I reduction. Unlike wildtype mice, mild-noise-induced hearing threshold shifts in Caprin1-deficient mice did not recover. Oxidative stress triggered TIA-1/HuR-positive stress granule formation in ex-vivo cochlear explants from Caprin1-deficient mice, showing that stress granules could still be induced. Taken together, these findings suggest that Caprin1 plays a key role in maintenance of auditory function, where it regulates the normal status of the IHC-SGN synapse.

Supporting cells eliminate dying sensory hair cells to maintain epithelial integrity in the avian inner ear.

Epithelial homeostasis is essential for sensory transduction in the auditory and vestibular organs of the inner ear, but how it is maintained during trauma is poorly understood. To examine potential repair mechanisms, we expressed ß-actin-enhanced green fluorescent protein (EGFP) in the chick inner ear and used live-cell imaging to study how sensory epithelia responded during aminoglycoside-induced hair cell trauma. We found that glial-like supporting cells used two independent mechanisms to rapidly eliminate dying hair cells. Supporting cells assembled an actin cable at the luminal surface that extended around the pericuticular junction and constricted to excise the stereocilia bundle and cuticular plate from the hair cell soma. Hair bundle excision could occur within 3 min of actin-cable formation. After bundle excision, typically with a delay of up to 2-3 h, supporting cells engulfed and phagocytosed the remaining bundle-less hair cell. Dual-channel recordings with ß-actin-EGFP and vital dyes revealed phagocytosis was concurrent with loss of hair cell integrity. We conclude that supporting cells repaired the epithelial barrier before hair cell plasmalemmal integrity was lost and that supporting cell activity was closely linked to hair cell death. Treatment with the Rho-kinase inhibitor Y-27632 did not prevent bundle excision but prolonged phagocytic engulfment and resulted in hair cell corpses accumulating within the epithelium. Our data show that supporting cells not only maintain epithelial integrity during trauma but suggest they may also be an integral part of the hair cell death process itself.

Wound healing recapitulates morphogenesis in Drosophila embryos.

The capacity to repair a wound is a fundamental survival mechanism that is activated at any site of damage throughout embryonic and adult life. To study the cell biology and genetics of this process, we have developed a wounding model in Drosophila melanogaster embryos that allows live imaging of rearrangements and changes in cell shape, and of the cytoskeletal machinery that draws closed an in vivo wound. Using embryos expressing green fluorescent protein (GFP) fusion proteins, we show that two cytoskeletal-dependent elements -- an actin cable and dynamic filopodial/lamellipodial protrusions -- are expressed by epithelial cells at the wound edge and are pivotal for repair. Modulating the activities of the small GTPases Rho and Cdc42 demonstrates that these actin-dependent elements have differing cellular functions, but that either alone can drive wound closure. The actin cable operates as a 'purse-string' to draw the hole closed, whereas filopodia are essential for the final 'knitting' together of epithelial cells at the end of repair. Our data suggest a more complex model for epithelial repair than previously envisaged and highlight remarkable similarities with the well-characterized morphogenetic movement of dorsal closure in Drosophila.

Differential regulation of mammalian and avian ATOH1 by E2F1 and its implication for hair cell regeneration in the inner ear.

The mammalian inner ear has a limited capacity to regenerate its mechanosensory hair cells. This lack of regenerative capacity underlies the high incidence of age-related hearing loss in humans. In contrast, non-mammalian vertebrates can form new hair cells when damage occurs, a mechanism that depends on re-activation of expression of the pro-hair cell transcription factor Atoh1. Here, we show that members of the E2F transcription factor family, known to play a key role in cell cycle progression, regulate the expression of Atoh1. E2F1 activates chicken Atoh1 by directly interacting with a cis-regulatory region distal to the avian Atoh1 gene. E2F does not activate mouse Atoh1 gene expression, since this regulatory element is absent in mammals. We also show that E2F1 expression changes dynamically in the chicken auditory epithelium during ototoxic damage and hair cell regeneration. Therefore, we propose a model in which the mitotic regeneration of non-mammalian hair cells is due to E2F1-mediated activation of Atoh1 expression, a mechanism which has been lost in mammals.

Damage-induced cell-cell communication in different cochlear cell types via two distinct ATP-dependent Ca waves.

UNLABELLED: Intercellular Ca(2+) waves can coordinate the action of large numbers of cells over significant distances. Recent work in many different systems has indicated that the release of ATP is fundamental for the propagation of most Ca(2+) waves. In the organ of hearing, the cochlea, ATP release is involved in critical signalling events during tissue maturation. ATP-dependent signalling is also implicated in the normal hearing process and in sensing cochlear damage. Here, we show that two distinct Ca(2+) waves are triggered during damage to cochlear explants. Both Ca(2+) waves are elicited by extracellular ATP acting on P2 receptors, but they differ in their source of Ca(2+), their velocity, their extent of spread and the cell type through which they propagate. A slower Ca(2+) wave (14 mum/s) communicates between Deiters' cells and is mediated by P2Y receptors and Ca(2+) release from IP(3)-sensitive stores. In contrast, a faster Ca(2+) wave (41 mum/s) propagates through sensory hair cells and is mediated by Ca(2+) influx from the external environment. Using inhibitors and selective agonists of P2 receptors, we suggest that the faster Ca(2+) wave is mediated by P2X(4) receptors. Thus, in complex tissues, the expression of different receptors determines the propagation of distinct intercellular communication signals. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11302-010-9193-8) contains supplementary material, which is available to authorized users.

Bioinspired Multiresonant Acoustic Devices Based on Electrospun Piezoelectric Polymeric Nanofibers.

Cochlear hair cells are critical for the conversion of acoustic into electrical signals and their dysfunction is a primary cause of acquired hearing impairments, which worsen with aging. Piezoelectric materials can reproduce the acoustic-electrical transduction properties of the cochlea and represent promising candidates for future cochlear prostheses. The majority of piezoelectric hearing devices so far developed are based on thin films, which have not managed to simultaneously provide the desired flexibility, high sensitivity, wide frequency selectivity, and biocompatibility. To overcome these issues, we hypothesized that fibrous membranes made up of polymeric piezoelectric biocompatible nanofibers could be employed to mimic the function of the basilar membrane, by selectively vibrating in response to different frequencies of sound and transmitting the resulting electrical impulses to the vestibulocochlear nerve. In this study, poly(vinylidene fluoride-trifluoroethylene) piezoelectric nanofiber-based acoustic circular sensors were designed and fabricated using the electrospinning technique. The performance of the sensors was investigated with particular focus on the identification of the resonance frequencies and acoustic-electrical conversion in fibrous membrane with different size and fiber orientation. The voltage output (1-17 mV) varied in the range of low resonance frequency (100-400 Hz) depending on the diameter of the macroscale sensors and alignment of the fibers. The devices developed can be regarded as a proof-of-concept demonstrating the possibility of using piezoelectric fibers to convert acoustic waves into electrical signals, through possible synergistic effects of piezoelectricity and triboelectricity. The study has paved the way for the development of self-powered nanofibrous implantable auditory sensors.

COVID-19 Status, Symptom Burden, and Characteristics of Dialysis Patients Residing in Areas of Community Transmission: Research Letter.

BACKGROUND: Routine testing of hemodialysis patients for COVID-19 (outside of those identified as "at risk" based on regional practice) is not universally recommended. However, there is variability in the clinical presentation of COVID-19; patients may experience symptoms that do not meet regional criteria for testing and some patients with active infection may be asymptomatic. To avoid missing individuals who are infected, consideration could be made for regular screening, particularly among those residing in areas with evidence of community spread. OBJECTIVE: To describe the clinical characteristics, symptom burden, and COVID-19 status in a cross-section of hemodialysis patients residing in areas with evidence of community spread. DESIGN: Cross-sectional study. SETTING: Three hemodialysis units in a large tertiary care facility in Nova Scotia, Canada. PATIENTS: In-center hemodialysis patients who resided in areas with evidence of community transmission at the time of the study. METHODS: All dialysis patients (irrespective of whether or not they resided in areas with community spread) completed a standard "at-risk" questionnaire for COVID-19 based on (1) 2 or more of new or worsening cough, fever greater than 38°C, sore throat, headache, runny nose/new or acute respiratory illness consistent with infection or (2) any one of close contact with a known/suspected case, travel outside of the province or residence in a facility with an outbreak prior to entry into the dialysis unit at each treatment. Patients residing in areas with evidence of community spread were swabbed for SARS-CoV-2 over a 1-week period (May 1-7, 2020) using a combined oropharyngeal/nares swab irrespective of whether or not they were identified as "at-risk." MEASUREMENTS: Baseline characteristics of patients were acquired using electronic records. In addition to the "at-risk" questionnaire, patients answered "yes" or "no" to any of the following symptoms at the time of the swab (sneeze, fatigue, myalgia, nausea/vomiting, diarrhea, malaise, abdominal pain, loss of taste, and loss of smell). RESULTS: Of the 334 patients receiving dialysis at the time of the study, 133 resided in areas with evidence of community transmission and 104 consented for the study. No patients met our regional criteria for being "at-risk" and no patients reported cough, sore throat or fever at the time of swab. Many other symptoms were noted, including sneezing (24%), fatigue (16%), myalgias (11%), nausea/vomiting (11%), loss of taste (4%), and loss of smell (4%). Overall, 100% of swabs performed for this study were negative for SARS-CoV-2. LIMITATIONS: Single-center study, and the daily new case rate was exceedingly low (4-14) at the time of the study, emphasizing that the findings are not generalizable to areas of higher prevalence of SARS-CoV-2. CONCLUSIONS: In this study of hemodialysis patients residing in areas with community spread who otherwise did not meet symptom criteria for being "at-risk," we did not identify any individual who tested positive for SARS-CoV-2. Future studies are needed to examine the utility of routine testing for COVID-19 (outside of those who are "at-risk") in areas of higher disease prevalence. TRIAL REGISTRATION: Not applicable as this is not a clinical trial.