Publications by authors named "Dylan Johnson"

Rationale: Reproducible analytical instrumentation system performance is critical for mass spectrometry, particularly metabolomics, aptly named system suitability testing. We identified a need based on literature reports that stated only 2% of papers performed system suitability testing.

Methods: We report MassQLab, built upon open-source, vendor-agnostic software called the mass spectrometry query language (MassQL).

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Chapare virus (CHAPV) is an emerging New World arenavirus that is the causative agent of Chapare haemorrhagic fever (CHHF) responsible for recent outbreaks with alarmingly high case fatality rates in Bolivia near the Brazilian border. Here, we describe a nonhuman primate (NHP) model of CHHF infection which represents an essential tool to understand this emerging biological threat agent. Cynomolgus macaques challenged intravenously with CHAPV develop clinical disease, which recapitulates several key features of human CHHF.

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Background: (1)Mopeia-Lassa reassortant ML29 virus is an investigational, reassortant virus vaccine for the prevention of Lassa fever caused by Lassa virus (LASV).

Methods: (2)The vaccine virus ML29-SF was prepared in Vero cells using a serum-free culture medium under Good Manufacturing Practice. A 2-week repeat dose toxicity study was performed in guinea pigs under Good Laboratory Practice (GLP) regulations to assess the local and systemic toxicological effects.

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Objective: The purpose of this study was to evaluate how various sociodemographic factors such as rurality, age, race, body mass index, and sex affect the surgical management of cholesteatoma. Canal wall-down (CWD) tympanomastoidectomy and longer surgical times were used as potential proxies for increased severity of disease.

Study Design: Retrospective.

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Purpose: This study examined how pre-existing early-life adversity (ELA) and current social support interacted with COVID-specific pandemic stressors in relation to risk of psychiatric disorders in a nationally-representative sample of Canadian adults.

Methods: Participants (n = 9,409) were from the Mental Health and Access to Care Survey, a cross-sectional survey of Canadian adults during later stages of the COVID pandemic (March to July 2022). Measures included pandemic stressors (Statistics Canada), ELA (Childhood Experiences of Violence Questionnaire), social support (Social Provisions Scale), and past 12-month psychiatric problems (WHO-CIDI).

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Background: Attention-deficit hyperactivity disorder (ADHD) may be a risk factor for intra- and inter-parental affective disorders in the perinatal period, placing families at risk for negative outcomes.

Methods: A large prospective cohort of Canadian women and their male partners (N = 2544 couples) were recruited in the postpartum period. Repeated measures data were collected at baseline and six timepoints over 24-months postpartum.

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Viral hemorrhagic Lassa fever (LF), caused by Lassa virus (LASV), is a significant public health concern endemic in West Africa with high morbidity and mortality rates, limited treatment options, and potential for international spread. Despite advances in interrogating its epidemiology and clinical manifestations, the molecular mechanisms driving pathogenesis of LASV and other arenaviruses remain incompletely understood. This review synthesizes current knowledge regarding the role of LASV host-virus interactions in mediating the pathogenesis of LF, with emphasis on interactions between viral and host proteins.

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Chapare virus (CHAPV) is an emerging arenavirus first discovered in Bolivia. Clinical cases have a high case-fatality rate and a concerning capacity for person-to-person spread. Animal models of Chapare hemorrhagic fever are needed to study pathogenesis and development of medical counter measures.

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Article Synopsis
  • Microbiology educators are focusing on helping students grasp essential concepts in virology due to rising vaccine hesitancy and misinformation surrounding COVID-19.
  • There is a shortage of virologists teaching undergraduates, often leading to limited coverage in microbiology courses, which can hinder meaningful discussions about viral issues.
  • A team of educators, supported by the American Society for Virology, developed curriculum guidelines for teaching virology in undergraduate settings, including measurable learning objectives to aid educators in implementing these guidelines.
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Article Synopsis
  • Favipiravir, a ribonucleoside analogue, shows promise as a treatment for Ebola Virus Disease (EVD), but mixed results in clinical trials have delayed its regulatory approval.
  • Recent studies in immune competent mouse and guinea pig models found that a dose of 300 mg/kg/day of favipiravir for 8 days effectively prevented lethal EVD-like disease, regardless of the route of administration and dosing schedule.
  • The findings support further development of favipiravir as a potential therapeutic option against EVD, with encouraging preclinical data indicating reduced mortality in guinea pigs after EBOV challenges.
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Early-life adversity is associated with the development of internalizing and externalizing problems in children. Despite this, there is a need to understand the mechanisms linking these experiences to psychopathology, especially in clinical samples. This cross-sectional study tested emotion dysregulation as a mechanism linking early-life threat to psychopathology in a clinical sample of children with disruptive behavior problems.

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Fluorine-18 fluorodeoxygluocose positron emission tomography (FDG-PET) is increasingly used in the evaluation of response to immune checkpoint inhibitor (ICI) therapy. Incidental findings of increased vessel wall uptake may prompt the concern for ICI-induced large vessel vasculitis (LVV). Precise radiographic and clinical evaluation is required to determine if this represents true vasculitis, as use of immune suppression and ICI discontinuation can have significant impacts on patient outcomes.

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Lymphocytic choriomeningitis virus (LCMV) and Lassa virus (LASV) share many genetic and biological features including subtle differences between pathogenic and apathogenic strains. Despite remarkable genetic similarity, the viscerotropic WE strain of LCMV causes a fatal LASV fever-like hepatitis in non-human primates (NHPs) while the mouse-adapted Armstrong (ARM) strain of LCMV is deeply attenuated in NHPs and can vaccinate against LCMV-WE challenge. Here, we demonstrate that internalization of WE is more sensitive to the depletion of membrane cholesterol than ARM infection while ARM infection is more reliant on endosomal acidification.

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Single-dose, immunogenic DNA (iDNA) vaccines coding for whole live-attenuated viruses are reviewed. This platform, sometimes called immunization DNA, has been used for vaccine development for flavi- and alphaviruses. An iDNA vaccine uses plasmid DNA to launch live-attenuated virus vaccines in vitro or in vivo.

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Background: The COVID-19 pandemic has created significant disruptions, with parents of school-age children being identified as a vulnerable population. Limited research has longitudinally tracked the mental health trajectories of parents over the active pandemic period. In addition, parents' history of adverse (ACEs) and benevolent (BCEs) childhood experiences may compound or attenuate the effect of COVID-19 stressors on parental psychopathology.

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Aberrant fibroblast function plays a key role in the pathogenesis of idiopathic pulmonary fibrosis, a devastating disease of unrelenting extracellular matrix deposition in response to lung injury. Platelet-derived growth factor α-positive (Pdgfra+) lipofibroblasts (LipoFBs) are essential for lung injury response and maintenance of a functional alveolar stem cell niche. Little is known about the effects of lung injury on LipoFB function.

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Objectives: Idiopathic inflammatory myopathies (IIMs) are heterogeneous diseases characterized by skeletal muscle inflammation associated with cutaneous, pulmonary and/or other visceral organ involvement. IVIG has been recommended as an adjunct therapy for IIM patients refractory to conventional therapy. However, IVIG has high resource needs and increased risk of adverse reactions.

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(EBOV) causes Ebola virus disease (EVD), a devastating viral hemorrhagic fever in humans. Nonhuman primate (NHP) models of EVD traditionally use intramuscular infection with higher case fatality rates and reduced mean time-to-death compared to contact transmission typical of human cases of EVD. A cynomolgus macaque model of oral and conjunctival EBOV was used to further characterize the more clinically relevant contact transmission of EVD.

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Objectives: Damage accrual in SSc can be tracked using the Scleroderma Clinical Trials Consortium Damage Index (DI). Our goal was to develop a prediction model for damage accrual in SSc patients with early disease.

Methods: Using patients with <2 years disease duration from Canada and Australia as a derivation cohort, and from the Netherlands as a validation cohort, we used group-based trajectory modelling (GBTM) to determine 'good' and 'bad' latent damage trajectories.

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Molnupiravir (EIDD-2801) is a prodrug of a ribonucleoside analogue that is currently being used under a US FDA emergency use authorization for the treatment of mild to moderate COVID-19. We evaluated molnupiravir for efficacy as an oral treatment in the rhesus macaque model of SARS-CoV-2 infection. Twenty non-human primates (NHPs) were challenged with SARS-CoV-2 and treated with 75 mg/kg (n = 8) or 250 mg/kg (n = 8) of molnupiravir twice daily by oral gavage for 7 days.

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Pregnancy and the early postpartum signify a period of high stress. Perinatal stress can include psychological distress (PD), such as anxiety, depression, and stress, as well as neuroendocrine stress, indexed by activation of the hypothalamic-pituitary-adrenal (HPA) axis and the production of the hormone cortisol. Elevated PD and cortisol levels during the perinatal period can have long-term implications for the mother and child.

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Adverse Childhood Experiences (ACEs) are known to contribute to later mental health. Conversely, Benevolent Childhood Experiences (BCEs) may buffer against mental health difficulties. The importance of ACEs and BCEs for mental health of both parents and children may be most obvious during periods of stress, with potential consequences for functioning of the family.

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Sex offender laws were designed to decrease sexual violence. The current mixed methods study examined attitudes and opinions of parole and probation officers who have supervised individuals convicted of sexual offenses ( = 361) regarding sex offender legislation and how these policies can be most effective in preventing recidivism. About half of the officers reported that registration and notification, sexually violent predator and Halloween laws were largely effective in preventing sexual victimization.

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Curriculum guidelines for virology are needed to best guide student learning due to the continuous and ever-increasing volume of virology information, the need to ensure that undergraduate and graduate students have a foundational understanding of key virology concepts, and the importance in being able to communicate that understanding to both other virologists and nonvirologists. Such guidelines, developed by virology educators and the American Society for Virology Education and Career Development Committee, are described herein.

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