Search

How cone photoreceptors are formed during retinal development is only partially known. This is in part because we do not fully understand the gene regulatory network responsible for cone genesis. We reasoned that cis-regulatory elements (enhancers) active in nascent cones would be regulated by the same upstream network that controls cone formation. To dissect this network, we searched for enhancers active in developing cones. By electroporating enhancer-driven fluorescent reporter plasmids, we observed that a sequence within an intron of the cone-specific Pde6c gene acted as an enhancer in developing mouse cones. Similar fluorescent reporter plasmids were used to generate stable transgenic human induced pluripotent stem cells that were then grown into three-dimensional human retinal organoids. These organoids contained fluorescently labeled cones, demonstrating that the Pde6c enhancer was also active in human cones. We observed that enhancer activity was transient and labeled a minor population of developing rod photoreceptors in both mouse and human systems. This cone-enriched pattern argues that the Pde6c enhancer is activated in cells poised between rod and cone fates. Additionally, it suggests that the Pde6c enhancer is activated by the same regulatory network that selects or stabilizes cone fate choice. To further understand this regulatory network, we identified essential enhancer sequence regions through a series of mutagenesis experiments. This suggested that the Pde6c enhancer was regulated by transcription factor binding at five or more locations. Binding site predictions implicated transcription factor families known to control photoreceptor formation and families not previously associated with cone development. These results provide a framework for deciphering the gene regulatory network that controls cone genesis in both human and mouse systems. Our new transgenic human stem cell lines provide a tool for determining which cone developmental mechanisms are shared and distinct between mice and humans., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: The COVID-19 pandemic spurred an increase in online information regarding disease spread and symptomatology., Objective: Our purpose is to systematically assess the quality and readability of articles resulting from frequently Google-searched COVID-19 terms in the United States., Methods: We used Google Trends to determine the 25 most commonly searched health-related phrases between February 29 and April 30, 2020. The first 30 search results for each term were collected, and articles were analyzed using the Quality Evaluation Scoring Tool (QUEST). Three raters scored each article in authorship, attribution, conflict of interest, currency, complementarity, and tone. A readability analysis was conducted., Results: Exactly 709 articles were screened, and 195 fulfilled inclusion criteria. The mean article score was 18.4 (SD 2.6) of 28, with 7% (14/189) scoring in the top quartile. National news outlets published the largest share (70/189, 36%) of articles. Peer-reviewed journals attained the highest average QUEST score compared to national/regional news outlets, national/state government sites, and global health organizations (all P<.05). The average reading level was 11.7 (SD 1.9, range 5.4-16.9). Only 3 (1.6%) articles were written at the recommended sixth grade level., Conclusions: COVID-19-related articles are vastly varied in their attributes and levels of bias, and would benefit from revisions for increased readability., (©Vismaya S Bachu, Heba Mahjoub, Albert E Holler, Tudor Crihalmeanu, Dheevena M Bachu, Varun Ayyaswami, Pearman D Parker, Arpan V Prabhu. Originally published in JMIR Formative Research (https://formative.jmir.org), 11.02.2022.)

Background: Sustained molecular detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in the upper respiratory tract (URT) in mild to moderate coronavirus disease 2019 (COVID-19) is common. We sought to identify host and immune determinants of prolonged SARS-CoV-2 RNA detection., Methods: Ninety-five symptomatic outpatients self-collected midturbinate nasal, oropharyngeal (OP), and gingival crevicular fluid (oral fluid) samples at home and in a research clinic a median of 6 times over 1-3 months. Samples were tested for viral RNA, virus culture, and SARS-CoV-2 and other human coronavirus antibodies, and associations were estimated using Cox proportional hazards models., Results: Viral RNA clearance, as measured by SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR), in 507 URT samples occurred a median (interquartile range) 33.5 (17-63.5) days post-symptom onset. Sixteen nasal-OP samples collected 2-11 days post-symptom onset were virus culture positive out of 183 RT-PCR-positive samples tested. All participants but 1 with positive virus culture were negative for concomitant oral fluid anti-SARS-CoV-2 antibodies. The mean time to first antibody detection in oral fluid was 8-13 days post-symptom onset. A longer time to first detection of oral fluid anti-SARS-CoV-2 S antibodies (adjusted hazard ratio [aHR], 0.96; 95% CI, 0.92-0.99; P = .020) and body mass index (BMI) ≥25 kg/m 2 (aHR, 0.37; 95% CI, 0.18-0.78; P = .009) were independently associated with a longer time to SARS-CoV-2 viral RNA clearance. Fever as 1 of first 3 COVID-19 symptoms correlated with shorter time to viral RNA clearance (aHR, 2.06; 95% CI, 1.02-4.18; P = .044)., Conclusions: We demonstrate that delayed rise of oral fluid SARS-CoV-2-specific antibodies, elevated BMI, and absence of early fever are independently associated with delayed URT viral RNA clearance., (© The Author(s) 2021. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Background: Outpatient coronavirus disease 2019 (COVID-19) has been insufficiently characterized. To determine the progression of disease and determinants of hospitalization, we conducted a prospective cohort study., Methods: Outpatient adults with positive reverse transcription polymerase chain reaction results for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were recruited by phone between April 21 and July 23, 2020, after receiving outpatient or emergency department testing within a large health network in Maryland, United States. Symptoms were collected by participants on days 0, 3, 7, 14, 21, and 28, and portable pulse oximeter oxygen saturation (SaO 2 ), heart rate, and temperature were collected for 15 consecutive days. Baseline demographics, comorbid conditions, and vital signs were evaluated for risk of subsequent hospitalization using negative binomial and logistic regression., Results: Among 118 SARS-CoV-2-infected outpatients, the median age (interquartile range [IQR]) was 56.0 (50.0-63.0) years, and 50 (42.4%) were male. Among individuals in the first week of illness (n = 61), the most common symptoms included weakness/fatigue (65.7%), cough (58.8%), headache (45.6%), chills (38.2%), and anosmia (27.9%). Participants returned to their usual health a median (IQR) of 20 (13-38) days from symptom onset, and 66.0% of respondents were at their usual health during the fourth week of illness. Over 28 days, 10.9% presented to the emergency department and 7.6% required hospitalization. The area under the receiver operating characteristics curve for the initial home SaO 2 for predicting subsequent hospitalization was 0.86 (95% CI, 0.73-0.99)., Conclusions: Symptoms often persisted but uncommonly progressed to hospitalization among outpatients with COVID-19. Home SaO 2 may be a helpful tool to stratify risk of hospitalization., (© The Author(s) 2021. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)