A Microphysiological HHT-on-a-Chip Platform Recapitulates Patient Vascular Lesions.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare congenital disease in which fragile vascular malformations (VM) - including small telangiectasias and large arteriovenous malformations (AVMs) - focally develop in multiple organs. There are few treatment options and no cure for HHT. Most HHT patients are heterozygous for loss-of-function mutations affecting Endoglin (ENG) or Alk1 (ACVRL1); however, why loss of these genes manifests as VMs remains poorly understood. To complement ongoing work in animal models, we have developed a fully human, cell-based microphysiological model based on our Vascularized Micro-organ (VMO) platform (the HHT-VMO) that recapitulates HHT patient VMs. Using inducible ACVRL1 -knockdown, we control timing and extent of endogenous Alk1 expression in primary human endothelial cells (EC). Resulting HHT-VMO VMs develop over several days. Interestingly, in chimera experiments AVM-like lesions can be comprised of both Alk1-intact and Alk1-deficient EC, suggesting possible cell non-autonomous effects. Single cell RNA sequencing data are consistent with microvessel pruning/regression as contributing to AVM formation, while loss of PDGFB implicates mural cell recruitment. Finally, lesion formation is blocked by the VEGFR inhibitor pazopanib, mirroring positive effects of this drug in patients. In summary, we have developed a novel HHT-on-a-chip model that faithfully reproduces HHT patient lesions and that can be used to better understand HHT disease biology and identify potential new HHT drugs. Word Count: 213 Classification. Biological Sciences, Cell Biology.

Imaging the large-scale and cellular response to focal traumatic brain injury in mouse neocortex.

Traumatic brain injury (TBI) affects neural function at the local injury site and also at distant, connected brain areas. However, the real-time neural dynamics in response to injury and subsequent effects on sensory processing and behavior are not fully resolved, especially across a range of spatial scales. We used in vivo calcium imaging in awake, head-restrained male and female mice to measure large-scale and cellular resolution neuronal activation, respectively, in response to a mild TBI induced by focal controlled cortical impact (CCI) injury of the motor cortex (M1). Widefield imaging revealed an immediate CCI-induced activation at the injury site, followed by a massive slow wave of calcium signal activation that traveled across the majority of the dorsal cortex within approximately 30 s. Correspondingly, two-photon calcium imaging in primary somatosensory cortex (S1) found strong activation of neuropil and neuronal populations during the CCI-induced traveling wave. A depression of calcium signals followed the wave, during which we observed atypical activity of a sparse population of S1 neurons. Longitudinal imaging in the hours and days after CCI revealed increases in the area of whisker-evoked sensory maps at early time points, in parallel to decreases in cortical functional connectivity and behavioral measures. Neural and behavioral changes mostly recovered over hours to days in our mild-TBI model, with a more lasting decrease in the number of active S1 neurons. Our results provide novel spatial and temporal views of neural adaptations that occur at cortical sites remote to a focal brain injury.

Ventilatory Assistance Before Umbilical Cord Clamping in Extremely Preterm Infants: A Randomized Clinical Trial.

Importance: Providing assisted ventilation during delayed umbilical cord clamping may improve outcomes for extremely preterm infants. Objective: To determine whether assisted ventilation in extremely preterm infants (23 0/7 to 28 6/7 weeks' gestational age [GA]) followed by cord clamping reduces intraventricular hemorrhage (IVH) or early death. Design, Setting, and Participants: This phase 3, 1:1, parallel-stratified randomized clinical trial conducted at 12 perinatal centers across the US and Canada from September 2, 2016, through February 21, 2023, assessed IVH and early death outcomes of extremely preterm infants randomized to receive 120 seconds of assisted ventilation followed by cord clamping vs delayed cord clamping for 30 to 60 seconds with ventilatory assistance afterward. Two analysis cohorts, not breathing well and breathing well, were specified a priori based on assessment of breathing 30 seconds after birth. Intervention: After birth, all infants received stimulation and suctioning if needed. From 30 to 120 seconds, infants randomized to the intervention received continuous positive airway pressure if breathing well or positive-pressure ventilation if not, with cord clamping at 120 seconds. Control infants received 30 to 60 seconds of delayed cord clamping followed by standard resuscitation. Main Outcomes and Measures: The primary outcome was any grade IVH on head ultrasonography or death before day 7. Interpretation by site radiologists was confirmed by independent radiologists, all masked to study group. To estimate the association between study group and outcome, data were analyzed using the stratified Cochran-Mantel-Haenszel test for relative risk (RR), with associations summarized by point estimates and 95% CIs. Results: Of 1110 women who consented to participate, 548 were randomized and delivered infants at GA less than 29 weeks. A total of 570 eligible infants were enrolled (median [IQR] GA, 26.6 [24.9-27.7] weeks; 297 male [52.1%]). Intraventricular hemorrhage or death occurred in 34.9% (97 of 278) of infants in the intervention group and 32.5% (95 of 292) in the control group (adjusted RR, 1.02; 95% CI, 0.81-1.27). In the prespecified not-breathing-well cohort (47.5% [271 of 570]; median [IQR] GA, 26.0 [24.7-27.4] weeks; 152 male [56.1%]), IVH or death occurred in 38.7% (58 of 150) of infants in the intervention group and 43.0% (52 of 121) in the control group (RR, 0.91; 95% CI, 0.68-1.21). There was no evidence of differences in death, severe brain injury, or major morbidities between the intervention and control groups in either breathing cohort. Conclusions and Relevance: This study did not show that providing assisted ventilation before cord clamping in extremely preterm infants reduces IVH or early death. Additional study around the feasibility, safety, and efficacy of assisted ventilation before cord clamping may provide additional insight. Trial Registration: ClinicalTrials.gov Identifier: NCT02742454.

SARS-CoV-2 infection of endothelial cells, dependent on flow-induced ACE2 expression, drives hypercytokinemia in a vascularized microphysiological system.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19, has caused nearly 7 million deaths worldwide. Severe cases are marked by an aggressive inflammatory response known as hypercytokinemia, contributing to endothelial damage. Although vaccination has reduced hospitalizations, hypercytokinemia persists in breakthrough infections, emphasizing the need for disease models mimicking this response. Using a 3D microphysiological system (MPS), we explored the vascular role in SARS-CoV-2-induced hypercytokinemia. Methods: The vascularized micro-organ (VMO) MPS, consisting of human-derived primary endothelial cells (ECs) and stromal cells within an extracellular matrix, was used to model SARS-CoV-2 infection. A non-replicative pseudotyped virus fused to GFP was employed, allowing visualization of viral entry into human ECs under physiologic flow conditions. Expression of ACE2, TMPRSS2, and AGTR1 was analyzed, and the impact of viral infection on ACE2 expression, vascular inflammation, and vascular morphology was assessed. Results: The VMO platform facilitated the study of COVID-19 vasculature infection, revealing that ACE2 expression increased significantly in direct response to shear stress, thereby enhancing susceptibility to infection by pseudotyped SARS-CoV-2. Infected ECs secreted pro-inflammatory cytokines, including IL-6 along with coagulation factors. Cytokines released by infected cells were able to activate downstream, non-infected EC, providing an amplification mechanism for inflammation and coagulopathy. Discussion: Our findings highlight the crucial role of vasculature in COVID-19 pathogenesis, emphasizing the significance of flow-induced ACE2 expression and subsequent inflammatory responses. The VMO provides a valuable tool for studying SARS-CoV-2 infection dynamics and evaluating potential therapeutics.

A Microphysiological HHT-on-a-Chip Platform Recapitulates Patient Vascular Lesions.

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare congenital disease in which fragile vascular malformations focally develop in multiple organs. These can be small (telangiectasias) or large (arteriovenous malformations, AVMs) and may rupture leading to frequent, uncontrolled bleeding. There are few treatment options and no cure for HHT. Most HHT patients are heterozygous for loss-of-function mutations for Endoglin (ENG) or Alk1 (ACVRL1), however, why loss of these genes manifests as vascular malformations remains poorly understood. To complement ongoing work in animal models, we have developed a microphysiological system model of HHT. Based on our existing vessel-on-a-chip (VMO) platform, our fully human cell-based HHT-VMO recapitulates HHT patient vascular lesions. Using inducible ACVRL1 (Alk1)-knockdown, we control timing and extent of endogenous Alk1 expression in primary human endothelial cells (EC) in the HHT-VMO. HHT-VMO vascular lesions develop over several days, and are dependent upon timing of Alk1 knockdown. Interestingly, in chimera experiments AVM-like lesions can be comprised of both Alk1-intact and Alk1-deficient EC, suggesting possible cell non-autonomous effects. Single cell RNA sequencing data are consistent with microvessel pruning/regression as contributing to AVM formation, while loss of PDGFB expression implicates mural cell recruitment. Finally, lesion formation is blocked by the VEGFR inhibitor pazopanib, mirroring the positive effects of this drug in patients. In summary, we have developed a novel HHT-on-a-chip model that faithfully reproduces HHT patient lesions and that is sensitive to a treatment effective in patients. The VMO-HHT can be used to better understand HHT disease biology and identify potential new HHT drugs. Significance: This manuscript describes development of an organ-on-a-chip model of Hereditary Hemorrhagic Telangiectasia (HHT), a rare genetic disease involving development of vascular malformations. Our VMO-HHT model produces vascular malformations similar to those seen in human HHT patients, including small (telangiectasias) and large (arteriovenous malformations) lesions. We show that VMO-HHT lesions are sensitive to a drug, pazopanib, that appears to be effective in HHT human patients. We further use the VMO-HHT platform to demonstrate that there is a critical window during vessel formation in which the HHT gene, Alk1, is required to prevent vascular malformation. Lastly, we show that lesions in the VMO-HHT model are comprised of both Alk1-deficient and Alk1-intact endothelial cells.

Virtual Obstetric Hospitalist Support for Obstetric Emergencies and Deliveries: The Mayo Clinic Experience.

Objective: To implement use of obstetric (OB) hospitalist telemedicine services (TeleOB) to support clinicians facing OB emergencies in low-resource hospital settings. Methods: TeleOB was staffed by OB hospitalists working at a tertiary maternity center. The service was available via real-time high-definition audio/video technology for providers at 17 outlying hospitals across a health system spanning two states. The initial 25 service activations are described. Results: TeleOB supported 17 deliveries, two postpartum emergency department (ED) consultations, and four antenatal ED consultations. In 10 of 17 (59%) deliveries, teleneonatology was jointly activated to support neonatal resuscitation. Sixteen (94%) deliveries occurred in multiparas, and five (29%) resulted from spontaneous preterm labor. Eighty percent (20/25) of activations occurred in facilities without maternity services. Conclusions: A TeleOB service staffed by OB hospitalists successfully supports hospitals in an integrated health care system. TeleOB is feasible for support of hospitals with no delivery facilities or with limited maternity care resources.

Telesimulation for neonatal resuscitation training.

Telesimulation uses telecommunication and simulation to educate and assess remote learners, obviating the need for instructors or learners to travel off site. Telesimulation increases access to and convenience of simulation-based education for sites that do not have formal simulation centers, including rural/remote areas. Telesimulation is feasible, improves knowledge and skills, and is favorably received by learners and instructors. In general, telesimulation has been shown to be effective for neonatal resuscitation training, even in low- and middle-income countries. Post telesimulation debriefing, termed teledebriefing, requires many of the skills of in-person debriefing, and teledebriefing can optimize learning by exposing learners to content experts in geographically distant sites or from specialties not available locally. When implementing telesimulation for neonatal resuscitation training, key considerations include program design, telecommunication platform, pre-telesimulation preparation, and teledebriefing. Additional research is needed to identify whether lessons learned during telesimulation translate to clinical practice and impact patient outcomes.

The impact of teleneonatology on the Transport Risk Index of Physiologic Stability score for outborn neonates: A prospective, observational study.

INTRODUCTION: Teleneonatology (TN) allows neonatologists to use real-time, audio-video telemedicine to manage critically ill neonates located in community hospitals (CHs). The California Transport Risk Index of Physiologic Stability (Ca-TRIPS) score is a validated metric that predicts the risk of 7-day mortality for neonates undergoing medical transport. We hypothesized that neonates born in CHs who received TN consults would have lower (better) Ca-TRIPS scores upon arrival of the transport team than those who did not. METHODS: Neonates born in CHs between 8 December 2018 and 31 July 2022 who were transported to the neonatal intensive care unit were screened for eligibility. TN was available at 50% (12/24) of CHs, where care teams decided when to activate the service. Study data were abstracted from the electronic health record and used to calculate Ca-TRIPS scores. Scores were evaluated using zero-inflated negative binomial regression. RESULTS: Forty-two percent (161/385) of neonates received a TN consult. Neonates that received TN had lower birth weight, gestational age, and Apgar scores and were more often admitted with respiratory distress syndrome and respiratory failure. Neonates who received TN were less likely to have a Ca-TRIPS score of zero (odds ratio 0.51; 95% confidence interval 0.33, 0.78). When adjusted for baseline characteristics, this difference was no longer significant. Non-zero Ca-TRIPS scores were not different between groups. DISCUSSION: In this observational study, neonates that received TN did not have lower (better) Ca-TRIPS scores. Findings may be limited by confounding bias given between-group differences in baseline patient characteristics. Randomized studies are needed to determine whether TN impacts the physiologic stability of neonates requiring medical transport.

Targeting TREM1 augments antitumor T cell immunity by inhibiting myeloid-derived suppressor cells and restraining anti-PD-1 resistance.

The triggering receptor expressed on myeloid cell 1 (TREM1) plays a critical role in development of chronic inflammatory disorders and the inflamed tumor microenvironment (TME) associated with most solid tumors. We examined whether loss of TREM1 signaling can abrogate the immunosuppressive TME and enhance cancer immunity. To investigate the therapeutic potential of TREM1 in cancer, we used mice deficient in Trem1 and developed a novel small molecule TREM1 inhibitor, VJDT. We demonstrated that genetic or pharmacological TREM1 silencing significantly delayed tumor growth in murine melanoma (B16F10) and fibrosarcoma (MCA205) models. Single-cell RNA-Seq combined with functional assays during TREM1 deficiency revealed decreased immunosuppressive capacity of myeloid-derived suppressor cells (MDSCs) accompanied by expansion in cytotoxic CD8+ T cells and increased PD-1 expression. Furthermore, TREM1 inhibition enhanced the antitumorigenic effect of anti-PD-1 treatment, in part, by limiting MDSC frequency and abrogating T cell exhaustion. In patient-derived melanoma xenograft tumors, treatment with VJDT downregulated key oncogenic signaling pathways involved in cell proliferation, migration, and survival. Our work highlights the role of TREM1 in cancer progression, both intrinsically expressed in cancer cells and extrinsically in the TME. Thus, targeting TREM1 to modify an immunosuppressive TME and improve efficacy of immune checkpoint therapy represents what we believe to be a promising therapeutic approach to cancer.

A Predictive Model of Adaptive Resistance to BRAF/MEK Inhibitors in Melanoma.

The adaptive acquisition of resistance to BRAF and MEK inhibitor-based therapy is a common feature of melanoma cells and contributes to poor patient treatment outcomes. Leveraging insights from a proteomic study and publicly available transcriptomic data, we evaluated the predictive capacity of a gene panel corresponding to proteins differentially abundant between treatment-sensitive and treatment-resistant cell lines, deciphering predictors of treatment resistance and potential resistance mechanisms to BRAF/MEK inhibitor therapy in patient biopsy samples. From our analysis, a 13-gene signature panel, in both test and validation datasets, could identify treatment-resistant or progressed melanoma cases with an accuracy and sensitivity of over 70%. The dysregulation of HMOX1, ICAM, MMP2, and SPARC defined a BRAF/MEK treatment-resistant landscape, with resistant cases showing a >2-fold risk of expression of these genes. Furthermore, we utilized a combination of functional enrichment- and gene expression-derived scores to model and identify pathways, such as HMOX1-mediated mitochondrial stress response, as potential key drivers of the emergence of a BRAF/MEK inhibitor-resistant state in melanoma cells. Overall, our results highlight the utility of these genes in predicting treatment outcomes and the underlying mechanisms that can be targeted to reduce the development of resistance to BRAF/MEK targeted therapy.

Evaluating the feasibility of a multicenter teleneonatology clinical effectiveness trial.

BACKGROUND: Our research consortium is preparing for a prospective multicenter trial evaluating the impact of teleneonatology on the health outcomes of at-risk neonates born in community hospitals. We completed a 6-month pilot study to determine the feasibility of the trial protocol. METHODS: Four neonatal intensive care units ("hubs") and four community hospitals ("spokes") participated in the pilot-forming four hub-spoke dyads. Two hub-spoke dyads implemented synchronous, audio-video telemedicine consultations with a neonatologist ("teleneonatology"). The primary outcome was a composite feasibility score that included one point for each of the following: site retention, on-time screening log completion, no eligibility errors, on-time data submission, and sponsor site-dyad meeting attendance (score range 0-5). RESULTS: For the 20 hub-spoke dyad months, the mean (range) composite feasibility score was 4.6 (4, 5). All sites were retained during the pilot. Ninety percent (18/20) of screening logs were completed on time. The eligibility error rate was 0.2% (3/1809). On-time data submission rate was 88.4% (84/95 case report forms). Eighty-five percent (17/20) of sponsor site-dyad meetings were attended by both hub and spoke site staff. CONCLUSIONS: A multicenter teleneonatology clinical effectiveness trial is feasible. Learnings from the pilot study may improve the likelihood of success of the main trial. IMPACT: A prospective, multicenter clinical trial evaluating the impact of teleneonatology on the early health outcomes of at-risk neonates born in community hospitals is feasible. A multidimensional composite feasibility score, which includes processes and procedures fundamental to completing a clinical trial, is useful for quantitatively measuring pilot study success. A pilot study allows the investigative team to test trial methods and materials to identify what works well or requires modification. Learnings from a pilot study may improve the quality and efficiency of the main effectiveness trial.

Connexin 37 sequestering of activated-ERK in the cytoplasm promotes p27-mediated endothelial cell cycle arrest.

Connexin37-mediated regulation of cell cycle modulators and, consequently, growth arrest lack mechanistic understanding. We previously showed that arterial shear stress up-regulates Cx37 in endothelial cells and activates a Notch/Cx37/p27 signaling axis to promote G1 cell cycle arrest, and this is required to enable arterial gene expression. However, how induced expression of a gap junction protein, Cx37, up-regulates cyclin-dependent kinase inhibitor p27 to enable endothelial growth suppression and arterial specification is unclear. Herein, we fill this knowledge gap by expressing wild-type and regulatory domain mutants of Cx37 in cultured endothelial cells expressing the Fucci cell cycle reporter. We determined that both the channel-forming and cytoplasmic tail domains of Cx37 are required for p27 up-regulation and late G1 arrest. Mechanistically, the cytoplasmic tail domain of Cx37 interacts with, and sequesters, activated ERK in the cytoplasm. This then stabilizes pERK nuclear target Foxo3a, which up-regulates p27 transcription. Consistent with previous studies, we found this Cx37/pERK/Foxo3a/p27 signaling axis functions downstream of arterial shear stress to promote endothelial late G1 state and enable up-regulation of arterial genes.

Connexin 43-mediated neurovascular interactions regulate neurogenesis in the adult brain subventricular zone.

The subventricular zone (SVZ) is the largest neural stem cell (NSC) niche in the adult brain; herein, the blood-brain barrier is leaky, allowing direct interactions between NSCs and endothelial cells (ECs). Mechanisms by which direct NSC-EC interactions in the adult SVZ control NSC behavior are unclear. We found that Cx43 is highly expressed by SVZ NSCs and ECs, and its deletion in either leads to increased NSC proliferation and neuroblast generation, suggesting that Cx43-mediated NSC-EC interactions maintain NSC quiescence. This is further supported by single-cell RNA sequencing and in vitro studies showing that ECs control NSC proliferation by regulating expression of genes associated with NSC quiescence and/or activation in a Cx43-dependent manner. Cx43 mediates these effects in a channel-independent manner involving its cytoplasmic tail and ERK activation. Such insights inform adult NSC regulation and maintenance aimed at stem cell therapies for neurodegenerative disorders.

Provider Perspectives on the Acceptability, Appropriateness, and Feasibility of Teleneonatology.

OBJECTIVE: We aimed to measure provider perspectives on the acceptability, appropriateness, and feasibility of teleneonatology in neonatal intensive care units (NICUs) and community hospitals. STUDY DESIGN: Providers from five academic tertiary NICUs and 27 community hospitals were surveyed using validated implementation measures to assess the acceptability, appropriateness, and feasibility of teleneonatology. For each of the 12 statements, scale values ranged from 1 to 5 (1 = strongly disagree; 5 = strongly agree), with higher scores indicating greater positive perceptions. Survey results were summarized, and differences across respondents assessed using generalized linear models. RESULTS: The survey response rate was 56% (203/365). Respondents found teleneonatology to be acceptable, appropriate, and feasible. The percent of respondents who agreed with each of the twelve statements ranged from 88.6 to 99.0%, with mean scores of 4.4 to 4.7 and median scores of 4.0 to 5.0. There was no difference in the acceptability, appropriateness, and feasibility of teleneonatology when analyzed by professional role, years of experience in neonatal care, or years of teleneonatology experience. Respondents from Level I well newborn nurseries had greater positive perceptions of teleneonatology than those from Level II special care nurseries. CONCLUSION: Providers in tertiary NICUs and community hospitals perceive teleneonatology to be highly acceptable, appropriate, and feasible for their practices. The wide acceptance by providers of all roles and levels of experience likely demonstrates a broad receptiveness to telemedicine as a tool to deliver neonatal care, particularly in rural communities where specialists are unavailable. KEY POINTS: · Neonatal care providers perceive teleneonatology to be highly acceptable, appropriate, and feasible.. · Perceptions of teleneonatology do not differ based on professional role or years of experience.. · Perceptions of teleneonatology are especially high in smaller hospitals with well newborn nurseries..

Sociodemographic factors and family use of remote infant viewing in neonatal intensive care.

OBJECTIVE: We aimed to determine whether the use of remote infant viewing (RIV) in a neonatal intensive care unit (NICU) differed based on maternal sociodemographic factors. METHODS: The number of RIV camera views and view duration were obtained for NICU patients between 10/01/2019 and 3/31/2021 and standardized relative to patient days. Maternal sociodemographic and neonatal characteristics were obtained from institutional databases. RESULTS: Families in which mothers were unmarried (aOR 1.42, 95% CI 1.03-1.95), did not require an interpreter (aOR 2.86, 95% CI 1.54-5.32), were multiparous (aOR 1.56, 95% CI 1.16-2.10), delivered prior to 37 weeks' gestation (aOR 1.57, 95% CI 1.17-2.12), or resided ≥50 miles from the NICU (aOR 1.38, 95% CI 1.02-1.87) were significantly more likely to use RIV. CONCLUSION: Family use of RIV in the NICU varied by multiple sociodemographic factors. Further investigation to understand and to address potential equity gaps revealed or created by RIV are warranted.

A quality improvement initiative to reduce necrotizing enterocolitis in high-risk neonates.

OBJECTIVE: Prompted by an acute increase in necrotizing enterocolitis (NEC) rates, we aimed to decrease the rate of stage 2 or greater NEC in infants born at <1500 grams or <30 weeks gestational age from 19.5% to less than 9.7% (a 50% reduction) within 18 months, without adversely affecting central line-associated bloodstream infection (CLABSI) rates. STUDY DESIGN: We utilized Define, Measure, Analyze, Improve, and Control (DMAIC) as our improvement model. Informed by our key driver diagram and root cause analyses, six Plan-Do-Study-Act cycles were completed. RESULTS: 147 infants in the QI initiative had a median gestational age of 28.1 weeks and a median birthweight of 1070 grams. NEC rates decreased from the QI baseline of 19.5% to 6% (p = 0.03). Oral care administration increased, and maximal gavage tube dwell time decreased. CONCLUSION: NEC rates decreased during this QI initiative through a combination of multidisciplinary interventions aimed at reducing dysbiosis.

Family Use of Remote Infant Viewing in the Neonatal Intensive Care Unit: Impact of the COVID-19 Pandemic and Patient Room Type.

Background: Remote infant viewing (RIV) uses a bedside camera to allow families to view a livestream video of their neonate 24/7 from anywhere with internet access. Objective: The aim of this study was to evaluate family use of RIV for infants in the neonatal intensive care unit (NICU) during the COVID-19 pandemic and whether RIV use varied by patient room type. Study Design: Use of RIV was evaluated for NICU patients between October 1, 2019, and March 31, 2021. The date, time, and duration of every RIV were exported from the RIV database and linked to the patient's room type. Results: Among 980 patients, 721 (73.6%) were viewed using RIV. The median (interquartile range) number of views per patient-days was 12.5 (5.4-26.0). Based on monthly aggregate data, the proportion of patients with at least one RIV increased during the pandemic from 71.6% in April 2020 to 94.3% in March 2021 (p < 0.001). The monthly number of views and view duration per patient-days also increased (p = 0.003; p = 0.029, respectively). When evaluating patient-level data by room type, the median number of views per patient-days was higher for open-bay than single-family rooms (13.5 vs. 10.5; p < 0.001) and median view duration (minutes) per patient-days was longer (21.8 vs. 12.1; p < 0.001). Conclusions: Use of RIV in the NICU increased during the COVID-19 pandemic. RIV was used more frequently and for longer duration by families with newborns in an open-bay room. RIV allows families to observe their newborn when visitor restrictions are in place or when in-person visits may be less private or do not allow for physical distancing.

Connexin37 Regulates Cell Cycle in the Vasculature.

Control of vascular cell growth responses is critical for development and maintenance of a healthy vasculature. Connexins - the proteins comprising gap junction channels - are key regulators of cell growth in diseases such as cancer, but their involvement in controlling cell growth in the vasculature is less well appreciated. Connexin37 (Cx37) is one of four connexin isotypes expressed in the vessel wall. Its primary role in blood vessels relies on its unique ability to transduce flow-sensitive signals into changes in cell cycle status of endothelial (and perhaps, mural) cells. Here, we review available evidence for Cx37's role in the regulation of vascular growth, vessel organization, and vascular tone in healthy and diseased vasculature. We propose a novel mechanism whereby Cx37 accomplishes this with a phosphorylation-dependent transition between closed (growth-suppressive) and multiple open (growth-permissive) channel conformations that result from interactions of the C-terminus with cell-cycle regulators to limit or support cell cycle progression. Lastly, we discuss Cx37 and its downstream signaling as a novel potential target in the treatment of cardiovascular disease, and we address outstanding research questions that still challenge the development of such therapies.

A mitochondrial contribution to anti-inflammatory shear stress signaling in vascular endothelial cells.

Atherosclerosis, the major cause of myocardial infarction and stroke, results from converging inflammatory, metabolic, and biomechanical factors. Arterial lesions form at sites of low and disturbed blood flow but are suppressed by high laminar shear stress (LSS) mainly via transcriptional induction of the anti-inflammatory transcription factor, Kruppel-like factor 2 (Klf2). We therefore performed a whole genome CRISPR-Cas9 screen to identify genes required for LSS induction of Klf2. Subsequent mechanistic investigation revealed that LSS induces Klf2 via activation of both a MEKK2/3-MEK5-ERK5 kinase module and mitochondrial metabolism. Mitochondrial calcium and ROS signaling regulate assembly of a mitophagy- and p62-dependent scaffolding complex that amplifies MEKK-MEK5-ERK5 signaling. Blocking the mitochondrial pathway in vivo reduces expression of KLF2-dependent genes such as eNOS and inhibits vascular remodeling. Failure to activate the mitochondrial pathway limits Klf2 expression in regions of disturbed flow. This work thus defines a connection between metabolism and vascular inflammation that provides a new framework for understanding and developing treatments for vascular disease.